11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/buffer.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992, 2002 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95 91da177e4SLinus Torvalds * 101da177e4SLinus Torvalds * Removed a lot of unnecessary code and simplified things now that 111da177e4SLinus Torvalds * the buffer cache isn't our primary cache - Andrew Tridgell 12/96 121da177e4SLinus Torvalds * 131da177e4SLinus Torvalds * Speed up hash, lru, and free list operations. Use gfp() for allocating 141da177e4SLinus Torvalds * hash table, use SLAB cache for buffer heads. SMP threading. -DaveM 151da177e4SLinus Torvalds * 161da177e4SLinus Torvalds * Added 32k buffer block sizes - these are required older ARM systems. - RMK 171da177e4SLinus Torvalds * 181da177e4SLinus Torvalds * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de> 191da177e4SLinus Torvalds */ 201da177e4SLinus Torvalds 211da177e4SLinus Torvalds #include <linux/kernel.h> 22f361bf4aSIngo Molnar #include <linux/sched/signal.h> 231da177e4SLinus Torvalds #include <linux/syscalls.h> 241da177e4SLinus Torvalds #include <linux/fs.h> 25ae259a9cSChristoph Hellwig #include <linux/iomap.h> 261da177e4SLinus Torvalds #include <linux/mm.h> 271da177e4SLinus Torvalds #include <linux/percpu.h> 281da177e4SLinus Torvalds #include <linux/slab.h> 2916f7e0feSRandy Dunlap #include <linux/capability.h> 301da177e4SLinus Torvalds #include <linux/blkdev.h> 311da177e4SLinus Torvalds #include <linux/file.h> 321da177e4SLinus Torvalds #include <linux/quotaops.h> 331da177e4SLinus Torvalds #include <linux/highmem.h> 34630d9c47SPaul Gortmaker #include <linux/export.h> 35bafc0dbaSTejun Heo #include <linux/backing-dev.h> 361da177e4SLinus Torvalds #include <linux/writeback.h> 371da177e4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <linux/suspend.h> 391da177e4SLinus Torvalds #include <linux/buffer_head.h> 4055e829afSAndrew Morton #include <linux/task_io_accounting_ops.h> 411da177e4SLinus Torvalds #include <linux/bio.h> 421da177e4SLinus Torvalds #include <linux/notifier.h> 431da177e4SLinus Torvalds #include <linux/cpu.h> 441da177e4SLinus Torvalds #include <linux/bitops.h> 451da177e4SLinus Torvalds #include <linux/mpage.h> 46fb1c8f93SIngo Molnar #include <linux/bit_spinlock.h> 4729f3ad7dSJan Kara #include <linux/pagevec.h> 485305cb83STejun Heo #include <trace/events/block.h> 491da177e4SLinus Torvalds 501da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); 512a222ca9SMike Christie static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, 528e8f9298SJens Axboe enum rw_hint hint, struct writeback_control *wbc); 531da177e4SLinus Torvalds 541da177e4SLinus Torvalds #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) 551da177e4SLinus Torvalds 56a3f3c29cSYan Hong void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) 571da177e4SLinus Torvalds { 581da177e4SLinus Torvalds bh->b_end_io = handler; 591da177e4SLinus Torvalds bh->b_private = private; 601da177e4SLinus Torvalds } 611fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(init_buffer); 621da177e4SLinus Torvalds 63f0059afdSTejun Heo inline void touch_buffer(struct buffer_head *bh) 64f0059afdSTejun Heo { 655305cb83STejun Heo trace_block_touch_buffer(bh); 66f0059afdSTejun Heo mark_page_accessed(bh->b_page); 67f0059afdSTejun Heo } 68f0059afdSTejun Heo EXPORT_SYMBOL(touch_buffer); 69f0059afdSTejun Heo 70fc9b52cdSHarvey Harrison void __lock_buffer(struct buffer_head *bh) 711da177e4SLinus Torvalds { 7274316201SNeilBrown wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 731da177e4SLinus Torvalds } 741da177e4SLinus Torvalds EXPORT_SYMBOL(__lock_buffer); 751da177e4SLinus Torvalds 76fc9b52cdSHarvey Harrison void unlock_buffer(struct buffer_head *bh) 771da177e4SLinus Torvalds { 7851b07fc3SNick Piggin clear_bit_unlock(BH_Lock, &bh->b_state); 794e857c58SPeter Zijlstra smp_mb__after_atomic(); 801da177e4SLinus Torvalds wake_up_bit(&bh->b_state, BH_Lock); 811da177e4SLinus Torvalds } 821fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(unlock_buffer); 831da177e4SLinus Torvalds 841da177e4SLinus Torvalds /* 85b4597226SMel Gorman * Returns if the page has dirty or writeback buffers. If all the buffers 86b4597226SMel Gorman * are unlocked and clean then the PageDirty information is stale. If 87b4597226SMel Gorman * any of the pages are locked, it is assumed they are locked for IO. 88b4597226SMel Gorman */ 89b4597226SMel Gorman void buffer_check_dirty_writeback(struct page *page, 90b4597226SMel Gorman bool *dirty, bool *writeback) 91b4597226SMel Gorman { 92b4597226SMel Gorman struct buffer_head *head, *bh; 93b4597226SMel Gorman *dirty = false; 94b4597226SMel Gorman *writeback = false; 95b4597226SMel Gorman 96b4597226SMel Gorman BUG_ON(!PageLocked(page)); 97b4597226SMel Gorman 98b4597226SMel Gorman if (!page_has_buffers(page)) 99b4597226SMel Gorman return; 100b4597226SMel Gorman 101b4597226SMel Gorman if (PageWriteback(page)) 102b4597226SMel Gorman *writeback = true; 103b4597226SMel Gorman 104b4597226SMel Gorman head = page_buffers(page); 105b4597226SMel Gorman bh = head; 106b4597226SMel Gorman do { 107b4597226SMel Gorman if (buffer_locked(bh)) 108b4597226SMel Gorman *writeback = true; 109b4597226SMel Gorman 110b4597226SMel Gorman if (buffer_dirty(bh)) 111b4597226SMel Gorman *dirty = true; 112b4597226SMel Gorman 113b4597226SMel Gorman bh = bh->b_this_page; 114b4597226SMel Gorman } while (bh != head); 115b4597226SMel Gorman } 116b4597226SMel Gorman EXPORT_SYMBOL(buffer_check_dirty_writeback); 117b4597226SMel Gorman 118b4597226SMel Gorman /* 1191da177e4SLinus Torvalds * Block until a buffer comes unlocked. This doesn't stop it 1201da177e4SLinus Torvalds * from becoming locked again - you have to lock it yourself 1211da177e4SLinus Torvalds * if you want to preserve its state. 1221da177e4SLinus Torvalds */ 1231da177e4SLinus Torvalds void __wait_on_buffer(struct buffer_head * bh) 1241da177e4SLinus Torvalds { 12574316201SNeilBrown wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 1261da177e4SLinus Torvalds } 1271fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__wait_on_buffer); 1281da177e4SLinus Torvalds 1291da177e4SLinus Torvalds static void 1301da177e4SLinus Torvalds __clear_page_buffers(struct page *page) 1311da177e4SLinus Torvalds { 1321da177e4SLinus Torvalds ClearPagePrivate(page); 1334c21e2f2SHugh Dickins set_page_private(page, 0); 13409cbfeafSKirill A. Shutemov put_page(page); 1351da177e4SLinus Torvalds } 1361da177e4SLinus Torvalds 137b744c2acSRobert Elliott static void buffer_io_error(struct buffer_head *bh, char *msg) 1381da177e4SLinus Torvalds { 139432f16e6SRobert Elliott if (!test_bit(BH_Quiet, &bh->b_state)) 140432f16e6SRobert Elliott printk_ratelimited(KERN_ERR 141a1c6f057SDmitry Monakhov "Buffer I/O error on dev %pg, logical block %llu%s\n", 142a1c6f057SDmitry Monakhov bh->b_bdev, (unsigned long long)bh->b_blocknr, msg); 1431da177e4SLinus Torvalds } 1441da177e4SLinus Torvalds 1451da177e4SLinus Torvalds /* 14668671f35SDmitry Monakhov * End-of-IO handler helper function which does not touch the bh after 14768671f35SDmitry Monakhov * unlocking it. 14868671f35SDmitry Monakhov * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but 14968671f35SDmitry Monakhov * a race there is benign: unlock_buffer() only use the bh's address for 15068671f35SDmitry Monakhov * hashing after unlocking the buffer, so it doesn't actually touch the bh 15168671f35SDmitry Monakhov * itself. 1521da177e4SLinus Torvalds */ 15368671f35SDmitry Monakhov static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) 1541da177e4SLinus Torvalds { 1551da177e4SLinus Torvalds if (uptodate) { 1561da177e4SLinus Torvalds set_buffer_uptodate(bh); 1571da177e4SLinus Torvalds } else { 15870246286SChristoph Hellwig /* This happens, due to failed read-ahead attempts. */ 1591da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1601da177e4SLinus Torvalds } 1611da177e4SLinus Torvalds unlock_buffer(bh); 16268671f35SDmitry Monakhov } 16368671f35SDmitry Monakhov 16468671f35SDmitry Monakhov /* 16568671f35SDmitry Monakhov * Default synchronous end-of-IO handler.. Just mark it up-to-date and 16668671f35SDmitry Monakhov * unlock the buffer. This is what ll_rw_block uses too. 16768671f35SDmitry Monakhov */ 16868671f35SDmitry Monakhov void end_buffer_read_sync(struct buffer_head *bh, int uptodate) 16968671f35SDmitry Monakhov { 17068671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 1711da177e4SLinus Torvalds put_bh(bh); 1721da177e4SLinus Torvalds } 1731fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_read_sync); 1741da177e4SLinus Torvalds 1751da177e4SLinus Torvalds void end_buffer_write_sync(struct buffer_head *bh, int uptodate) 1761da177e4SLinus Torvalds { 1771da177e4SLinus Torvalds if (uptodate) { 1781da177e4SLinus Torvalds set_buffer_uptodate(bh); 1791da177e4SLinus Torvalds } else { 180b744c2acSRobert Elliott buffer_io_error(bh, ", lost sync page write"); 18187354e5dSJeff Layton mark_buffer_write_io_error(bh); 1821da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1831da177e4SLinus Torvalds } 1841da177e4SLinus Torvalds unlock_buffer(bh); 1851da177e4SLinus Torvalds put_bh(bh); 1861da177e4SLinus Torvalds } 1871fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_write_sync); 1881da177e4SLinus Torvalds 1891da177e4SLinus Torvalds /* 1901da177e4SLinus Torvalds * Various filesystems appear to want __find_get_block to be non-blocking. 1911da177e4SLinus Torvalds * But it's the page lock which protects the buffers. To get around this, 1921da177e4SLinus Torvalds * we get exclusion from try_to_free_buffers with the blockdev mapping's 1931da177e4SLinus Torvalds * private_lock. 1941da177e4SLinus Torvalds * 1951da177e4SLinus Torvalds * Hack idea: for the blockdev mapping, i_bufferlist_lock contention 1961da177e4SLinus Torvalds * may be quite high. This code could TryLock the page, and if that 1971da177e4SLinus Torvalds * succeeds, there is no need to take private_lock. (But if 1981da177e4SLinus Torvalds * private_lock is contended then so is mapping->tree_lock). 1991da177e4SLinus Torvalds */ 2001da177e4SLinus Torvalds static struct buffer_head * 201385fd4c5SCoywolf Qi Hunt __find_get_block_slow(struct block_device *bdev, sector_t block) 2021da177e4SLinus Torvalds { 2031da177e4SLinus Torvalds struct inode *bd_inode = bdev->bd_inode; 2041da177e4SLinus Torvalds struct address_space *bd_mapping = bd_inode->i_mapping; 2051da177e4SLinus Torvalds struct buffer_head *ret = NULL; 2061da177e4SLinus Torvalds pgoff_t index; 2071da177e4SLinus Torvalds struct buffer_head *bh; 2081da177e4SLinus Torvalds struct buffer_head *head; 2091da177e4SLinus Torvalds struct page *page; 2101da177e4SLinus Torvalds int all_mapped = 1; 2111da177e4SLinus Torvalds 21209cbfeafSKirill A. Shutemov index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); 2132457aec6SMel Gorman page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED); 2141da177e4SLinus Torvalds if (!page) 2151da177e4SLinus Torvalds goto out; 2161da177e4SLinus Torvalds 2171da177e4SLinus Torvalds spin_lock(&bd_mapping->private_lock); 2181da177e4SLinus Torvalds if (!page_has_buffers(page)) 2191da177e4SLinus Torvalds goto out_unlock; 2201da177e4SLinus Torvalds head = page_buffers(page); 2211da177e4SLinus Torvalds bh = head; 2221da177e4SLinus Torvalds do { 22397f76d3dSNikanth Karthikesan if (!buffer_mapped(bh)) 22497f76d3dSNikanth Karthikesan all_mapped = 0; 22597f76d3dSNikanth Karthikesan else if (bh->b_blocknr == block) { 2261da177e4SLinus Torvalds ret = bh; 2271da177e4SLinus Torvalds get_bh(bh); 2281da177e4SLinus Torvalds goto out_unlock; 2291da177e4SLinus Torvalds } 2301da177e4SLinus Torvalds bh = bh->b_this_page; 2311da177e4SLinus Torvalds } while (bh != head); 2321da177e4SLinus Torvalds 2331da177e4SLinus Torvalds /* we might be here because some of the buffers on this page are 2341da177e4SLinus Torvalds * not mapped. This is due to various races between 2351da177e4SLinus Torvalds * file io on the block device and getblk. It gets dealt with 2361da177e4SLinus Torvalds * elsewhere, don't buffer_error if we had some unmapped buffers 2371da177e4SLinus Torvalds */ 2381da177e4SLinus Torvalds if (all_mapped) { 2391da177e4SLinus Torvalds printk("__find_get_block_slow() failed. " 2401da177e4SLinus Torvalds "block=%llu, b_blocknr=%llu\n", 241205f87f6SBadari Pulavarty (unsigned long long)block, 242205f87f6SBadari Pulavarty (unsigned long long)bh->b_blocknr); 243205f87f6SBadari Pulavarty printk("b_state=0x%08lx, b_size=%zu\n", 244205f87f6SBadari Pulavarty bh->b_state, bh->b_size); 245a1c6f057SDmitry Monakhov printk("device %pg blocksize: %d\n", bdev, 24672a2ebd8STao Ma 1 << bd_inode->i_blkbits); 2471da177e4SLinus Torvalds } 2481da177e4SLinus Torvalds out_unlock: 2491da177e4SLinus Torvalds spin_unlock(&bd_mapping->private_lock); 25009cbfeafSKirill A. Shutemov put_page(page); 2511da177e4SLinus Torvalds out: 2521da177e4SLinus Torvalds return ret; 2531da177e4SLinus Torvalds } 2541da177e4SLinus Torvalds 2551da177e4SLinus Torvalds /* 2565b0830cbSJens Axboe * Kick the writeback threads then try to free up some ZONE_NORMAL memory. 2571da177e4SLinus Torvalds */ 2581da177e4SLinus Torvalds static void free_more_memory(void) 2591da177e4SLinus Torvalds { 260c33d6c06SMel Gorman struct zoneref *z; 2610e88460dSMel Gorman int nid; 2621da177e4SLinus Torvalds 2630e175a18SCurt Wohlgemuth wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM); 2641da177e4SLinus Torvalds yield(); 2651da177e4SLinus Torvalds 2660e88460dSMel Gorman for_each_online_node(nid) { 267c33d6c06SMel Gorman 268c33d6c06SMel Gorman z = first_zones_zonelist(node_zonelist(nid, GFP_NOFS), 269c33d6c06SMel Gorman gfp_zone(GFP_NOFS), NULL); 270c33d6c06SMel Gorman if (z->zone) 27154a6eb5cSMel Gorman try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0, 272327c0e96SKAMEZAWA Hiroyuki GFP_NOFS, NULL); 2731da177e4SLinus Torvalds } 2741da177e4SLinus Torvalds } 2751da177e4SLinus Torvalds 2761da177e4SLinus Torvalds /* 2771da177e4SLinus Torvalds * I/O completion handler for block_read_full_page() - pages 2781da177e4SLinus Torvalds * which come unlocked at the end of I/O. 2791da177e4SLinus Torvalds */ 2801da177e4SLinus Torvalds static void end_buffer_async_read(struct buffer_head *bh, int uptodate) 2811da177e4SLinus Torvalds { 2821da177e4SLinus Torvalds unsigned long flags; 283a3972203SNick Piggin struct buffer_head *first; 2841da177e4SLinus Torvalds struct buffer_head *tmp; 2851da177e4SLinus Torvalds struct page *page; 2861da177e4SLinus Torvalds int page_uptodate = 1; 2871da177e4SLinus Torvalds 2881da177e4SLinus Torvalds BUG_ON(!buffer_async_read(bh)); 2891da177e4SLinus Torvalds 2901da177e4SLinus Torvalds page = bh->b_page; 2911da177e4SLinus Torvalds if (uptodate) { 2921da177e4SLinus Torvalds set_buffer_uptodate(bh); 2931da177e4SLinus Torvalds } else { 2941da177e4SLinus Torvalds clear_buffer_uptodate(bh); 295b744c2acSRobert Elliott buffer_io_error(bh, ", async page read"); 2961da177e4SLinus Torvalds SetPageError(page); 2971da177e4SLinus Torvalds } 2981da177e4SLinus Torvalds 2991da177e4SLinus Torvalds /* 3001da177e4SLinus Torvalds * Be _very_ careful from here on. Bad things can happen if 3011da177e4SLinus Torvalds * two buffer heads end IO at almost the same time and both 3021da177e4SLinus Torvalds * decide that the page is now completely done. 3031da177e4SLinus Torvalds */ 304a3972203SNick Piggin first = page_buffers(page); 305a3972203SNick Piggin local_irq_save(flags); 306a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 3071da177e4SLinus Torvalds clear_buffer_async_read(bh); 3081da177e4SLinus Torvalds unlock_buffer(bh); 3091da177e4SLinus Torvalds tmp = bh; 3101da177e4SLinus Torvalds do { 3111da177e4SLinus Torvalds if (!buffer_uptodate(tmp)) 3121da177e4SLinus Torvalds page_uptodate = 0; 3131da177e4SLinus Torvalds if (buffer_async_read(tmp)) { 3141da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3151da177e4SLinus Torvalds goto still_busy; 3161da177e4SLinus Torvalds } 3171da177e4SLinus Torvalds tmp = tmp->b_this_page; 3181da177e4SLinus Torvalds } while (tmp != bh); 319a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 320a3972203SNick Piggin local_irq_restore(flags); 3211da177e4SLinus Torvalds 3221da177e4SLinus Torvalds /* 3231da177e4SLinus Torvalds * If none of the buffers had errors and they are all 3241da177e4SLinus Torvalds * uptodate then we can set the page uptodate. 3251da177e4SLinus Torvalds */ 3261da177e4SLinus Torvalds if (page_uptodate && !PageError(page)) 3271da177e4SLinus Torvalds SetPageUptodate(page); 3281da177e4SLinus Torvalds unlock_page(page); 3291da177e4SLinus Torvalds return; 3301da177e4SLinus Torvalds 3311da177e4SLinus Torvalds still_busy: 332a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 333a3972203SNick Piggin local_irq_restore(flags); 3341da177e4SLinus Torvalds return; 3351da177e4SLinus Torvalds } 3361da177e4SLinus Torvalds 3371da177e4SLinus Torvalds /* 3381da177e4SLinus Torvalds * Completion handler for block_write_full_page() - pages which are unlocked 3391da177e4SLinus Torvalds * during I/O, and which have PageWriteback cleared upon I/O completion. 3401da177e4SLinus Torvalds */ 34135c80d5fSChris Mason void end_buffer_async_write(struct buffer_head *bh, int uptodate) 3421da177e4SLinus Torvalds { 3431da177e4SLinus Torvalds unsigned long flags; 344a3972203SNick Piggin struct buffer_head *first; 3451da177e4SLinus Torvalds struct buffer_head *tmp; 3461da177e4SLinus Torvalds struct page *page; 3471da177e4SLinus Torvalds 3481da177e4SLinus Torvalds BUG_ON(!buffer_async_write(bh)); 3491da177e4SLinus Torvalds 3501da177e4SLinus Torvalds page = bh->b_page; 3511da177e4SLinus Torvalds if (uptodate) { 3521da177e4SLinus Torvalds set_buffer_uptodate(bh); 3531da177e4SLinus Torvalds } else { 354b744c2acSRobert Elliott buffer_io_error(bh, ", lost async page write"); 35587354e5dSJeff Layton mark_buffer_write_io_error(bh); 3561da177e4SLinus Torvalds clear_buffer_uptodate(bh); 3571da177e4SLinus Torvalds SetPageError(page); 3581da177e4SLinus Torvalds } 3591da177e4SLinus Torvalds 360a3972203SNick Piggin first = page_buffers(page); 361a3972203SNick Piggin local_irq_save(flags); 362a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 363a3972203SNick Piggin 3641da177e4SLinus Torvalds clear_buffer_async_write(bh); 3651da177e4SLinus Torvalds unlock_buffer(bh); 3661da177e4SLinus Torvalds tmp = bh->b_this_page; 3671da177e4SLinus Torvalds while (tmp != bh) { 3681da177e4SLinus Torvalds if (buffer_async_write(tmp)) { 3691da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3701da177e4SLinus Torvalds goto still_busy; 3711da177e4SLinus Torvalds } 3721da177e4SLinus Torvalds tmp = tmp->b_this_page; 3731da177e4SLinus Torvalds } 374a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 375a3972203SNick Piggin local_irq_restore(flags); 3761da177e4SLinus Torvalds end_page_writeback(page); 3771da177e4SLinus Torvalds return; 3781da177e4SLinus Torvalds 3791da177e4SLinus Torvalds still_busy: 380a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 381a3972203SNick Piggin local_irq_restore(flags); 3821da177e4SLinus Torvalds return; 3831da177e4SLinus Torvalds } 3841fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_async_write); 3851da177e4SLinus Torvalds 3861da177e4SLinus Torvalds /* 3871da177e4SLinus Torvalds * If a page's buffers are under async readin (end_buffer_async_read 3881da177e4SLinus Torvalds * completion) then there is a possibility that another thread of 3891da177e4SLinus Torvalds * control could lock one of the buffers after it has completed 3901da177e4SLinus Torvalds * but while some of the other buffers have not completed. This 3911da177e4SLinus Torvalds * locked buffer would confuse end_buffer_async_read() into not unlocking 3921da177e4SLinus Torvalds * the page. So the absence of BH_Async_Read tells end_buffer_async_read() 3931da177e4SLinus Torvalds * that this buffer is not under async I/O. 3941da177e4SLinus Torvalds * 3951da177e4SLinus Torvalds * The page comes unlocked when it has no locked buffer_async buffers 3961da177e4SLinus Torvalds * left. 3971da177e4SLinus Torvalds * 3981da177e4SLinus Torvalds * PageLocked prevents anyone starting new async I/O reads any of 3991da177e4SLinus Torvalds * the buffers. 4001da177e4SLinus Torvalds * 4011da177e4SLinus Torvalds * PageWriteback is used to prevent simultaneous writeout of the same 4021da177e4SLinus Torvalds * page. 4031da177e4SLinus Torvalds * 4041da177e4SLinus Torvalds * PageLocked prevents anyone from starting writeback of a page which is 4051da177e4SLinus Torvalds * under read I/O (PageWriteback is only ever set against a locked page). 4061da177e4SLinus Torvalds */ 4071da177e4SLinus Torvalds static void mark_buffer_async_read(struct buffer_head *bh) 4081da177e4SLinus Torvalds { 4091da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_read; 4101da177e4SLinus Torvalds set_buffer_async_read(bh); 4111da177e4SLinus Torvalds } 4121da177e4SLinus Torvalds 4131fe72eaaSH Hartley Sweeten static void mark_buffer_async_write_endio(struct buffer_head *bh, 41435c80d5fSChris Mason bh_end_io_t *handler) 41535c80d5fSChris Mason { 41635c80d5fSChris Mason bh->b_end_io = handler; 41735c80d5fSChris Mason set_buffer_async_write(bh); 41835c80d5fSChris Mason } 41935c80d5fSChris Mason 4201da177e4SLinus Torvalds void mark_buffer_async_write(struct buffer_head *bh) 4211da177e4SLinus Torvalds { 42235c80d5fSChris Mason mark_buffer_async_write_endio(bh, end_buffer_async_write); 4231da177e4SLinus Torvalds } 4241da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_async_write); 4251da177e4SLinus Torvalds 4261da177e4SLinus Torvalds 4271da177e4SLinus Torvalds /* 4281da177e4SLinus Torvalds * fs/buffer.c contains helper functions for buffer-backed address space's 4291da177e4SLinus Torvalds * fsync functions. A common requirement for buffer-based filesystems is 4301da177e4SLinus Torvalds * that certain data from the backing blockdev needs to be written out for 4311da177e4SLinus Torvalds * a successful fsync(). For example, ext2 indirect blocks need to be 4321da177e4SLinus Torvalds * written back and waited upon before fsync() returns. 4331da177e4SLinus Torvalds * 4341da177e4SLinus Torvalds * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), 4351da177e4SLinus Torvalds * inode_has_buffers() and invalidate_inode_buffers() are provided for the 4361da177e4SLinus Torvalds * management of a list of dependent buffers at ->i_mapping->private_list. 4371da177e4SLinus Torvalds * 4381da177e4SLinus Torvalds * Locking is a little subtle: try_to_free_buffers() will remove buffers 4391da177e4SLinus Torvalds * from their controlling inode's queue when they are being freed. But 4401da177e4SLinus Torvalds * try_to_free_buffers() will be operating against the *blockdev* mapping 4411da177e4SLinus Torvalds * at the time, not against the S_ISREG file which depends on those buffers. 4421da177e4SLinus Torvalds * So the locking for private_list is via the private_lock in the address_space 4431da177e4SLinus Torvalds * which backs the buffers. Which is different from the address_space 4441da177e4SLinus Torvalds * against which the buffers are listed. So for a particular address_space, 4451da177e4SLinus Torvalds * mapping->private_lock does *not* protect mapping->private_list! In fact, 4461da177e4SLinus Torvalds * mapping->private_list will always be protected by the backing blockdev's 4471da177e4SLinus Torvalds * ->private_lock. 4481da177e4SLinus Torvalds * 4491da177e4SLinus Torvalds * Which introduces a requirement: all buffers on an address_space's 4501da177e4SLinus Torvalds * ->private_list must be from the same address_space: the blockdev's. 4511da177e4SLinus Torvalds * 4521da177e4SLinus Torvalds * address_spaces which do not place buffers at ->private_list via these 4531da177e4SLinus Torvalds * utility functions are free to use private_lock and private_list for 4541da177e4SLinus Torvalds * whatever they want. The only requirement is that list_empty(private_list) 4551da177e4SLinus Torvalds * be true at clear_inode() time. 4561da177e4SLinus Torvalds * 4571da177e4SLinus Torvalds * FIXME: clear_inode should not call invalidate_inode_buffers(). The 4581da177e4SLinus Torvalds * filesystems should do that. invalidate_inode_buffers() should just go 4591da177e4SLinus Torvalds * BUG_ON(!list_empty). 4601da177e4SLinus Torvalds * 4611da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should 4621da177e4SLinus Torvalds * take an address_space, not an inode. And it should be called 4631da177e4SLinus Torvalds * mark_buffer_dirty_fsync() to clearly define why those buffers are being 4641da177e4SLinus Torvalds * queued up. 4651da177e4SLinus Torvalds * 4661da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the 4671da177e4SLinus Torvalds * list if it is already on a list. Because if the buffer is on a list, 4681da177e4SLinus Torvalds * it *must* already be on the right one. If not, the filesystem is being 4691da177e4SLinus Torvalds * silly. This will save a ton of locking. But first we have to ensure 4701da177e4SLinus Torvalds * that buffers are taken *off* the old inode's list when they are freed 4711da177e4SLinus Torvalds * (presumably in truncate). That requires careful auditing of all 4721da177e4SLinus Torvalds * filesystems (do it inside bforget()). It could also be done by bringing 4731da177e4SLinus Torvalds * b_inode back. 4741da177e4SLinus Torvalds */ 4751da177e4SLinus Torvalds 4761da177e4SLinus Torvalds /* 4771da177e4SLinus Torvalds * The buffer's backing address_space's private_lock must be held 4781da177e4SLinus Torvalds */ 479dbacefc9SThomas Petazzoni static void __remove_assoc_queue(struct buffer_head *bh) 4801da177e4SLinus Torvalds { 4811da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 48258ff407bSJan Kara WARN_ON(!bh->b_assoc_map); 48358ff407bSJan Kara bh->b_assoc_map = NULL; 4841da177e4SLinus Torvalds } 4851da177e4SLinus Torvalds 4861da177e4SLinus Torvalds int inode_has_buffers(struct inode *inode) 4871da177e4SLinus Torvalds { 4881da177e4SLinus Torvalds return !list_empty(&inode->i_data.private_list); 4891da177e4SLinus Torvalds } 4901da177e4SLinus Torvalds 4911da177e4SLinus Torvalds /* 4921da177e4SLinus Torvalds * osync is designed to support O_SYNC io. It waits synchronously for 4931da177e4SLinus Torvalds * all already-submitted IO to complete, but does not queue any new 4941da177e4SLinus Torvalds * writes to the disk. 4951da177e4SLinus Torvalds * 4961da177e4SLinus Torvalds * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as 4971da177e4SLinus Torvalds * you dirty the buffers, and then use osync_inode_buffers to wait for 4981da177e4SLinus Torvalds * completion. Any other dirty buffers which are not yet queued for 4991da177e4SLinus Torvalds * write will not be flushed to disk by the osync. 5001da177e4SLinus Torvalds */ 5011da177e4SLinus Torvalds static int osync_buffers_list(spinlock_t *lock, struct list_head *list) 5021da177e4SLinus Torvalds { 5031da177e4SLinus Torvalds struct buffer_head *bh; 5041da177e4SLinus Torvalds struct list_head *p; 5051da177e4SLinus Torvalds int err = 0; 5061da177e4SLinus Torvalds 5071da177e4SLinus Torvalds spin_lock(lock); 5081da177e4SLinus Torvalds repeat: 5091da177e4SLinus Torvalds list_for_each_prev(p, list) { 5101da177e4SLinus Torvalds bh = BH_ENTRY(p); 5111da177e4SLinus Torvalds if (buffer_locked(bh)) { 5121da177e4SLinus Torvalds get_bh(bh); 5131da177e4SLinus Torvalds spin_unlock(lock); 5141da177e4SLinus Torvalds wait_on_buffer(bh); 5151da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 5161da177e4SLinus Torvalds err = -EIO; 5171da177e4SLinus Torvalds brelse(bh); 5181da177e4SLinus Torvalds spin_lock(lock); 5191da177e4SLinus Torvalds goto repeat; 5201da177e4SLinus Torvalds } 5211da177e4SLinus Torvalds } 5221da177e4SLinus Torvalds spin_unlock(lock); 5231da177e4SLinus Torvalds return err; 5241da177e4SLinus Torvalds } 5251da177e4SLinus Torvalds 526*08fdc8a0SMateusz Guzik void emergency_thaw_bdev(struct super_block *sb) 527c2d75438SEric Sandeen { 528c2d75438SEric Sandeen while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) 529a1c6f057SDmitry Monakhov printk(KERN_WARNING "Emergency Thaw on %pg\n", sb->s_bdev); 530c2d75438SEric Sandeen } 53101a05b33SAl Viro 5321da177e4SLinus Torvalds /** 53378a4a50aSRandy Dunlap * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers 53467be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 5351da177e4SLinus Torvalds * 5361da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 5371da177e4SLinus Torvalds * that I/O. 5381da177e4SLinus Torvalds * 53967be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 54067be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 54167be2dd1SMartin Waitz * a successful fsync(). 5421da177e4SLinus Torvalds */ 5431da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 5441da177e4SLinus Torvalds { 545252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 5461da177e4SLinus Torvalds 5471da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 5481da177e4SLinus Torvalds return 0; 5491da177e4SLinus Torvalds 5501da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 5511da177e4SLinus Torvalds &mapping->private_list); 5521da177e4SLinus Torvalds } 5531da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 5541da177e4SLinus Torvalds 5551da177e4SLinus Torvalds /* 5561da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 5571da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 5581da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 5591da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 5601da177e4SLinus Torvalds */ 5611da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 5621da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 5631da177e4SLinus Torvalds { 5641da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 5651da177e4SLinus Torvalds if (bh) { 5661da177e4SLinus Torvalds if (buffer_dirty(bh)) 567dfec8a14SMike Christie ll_rw_block(REQ_OP_WRITE, 0, 1, &bh); 5681da177e4SLinus Torvalds put_bh(bh); 5691da177e4SLinus Torvalds } 5701da177e4SLinus Torvalds } 5711da177e4SLinus Torvalds 5721da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 5731da177e4SLinus Torvalds { 5741da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 5751da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 5761da177e4SLinus Torvalds 5771da177e4SLinus Torvalds mark_buffer_dirty(bh); 578252aa6f5SRafael Aquini if (!mapping->private_data) { 579252aa6f5SRafael Aquini mapping->private_data = buffer_mapping; 5801da177e4SLinus Torvalds } else { 581252aa6f5SRafael Aquini BUG_ON(mapping->private_data != buffer_mapping); 5821da177e4SLinus Torvalds } 583535ee2fbSJan Kara if (!bh->b_assoc_map) { 5841da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 5851da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 5861da177e4SLinus Torvalds &mapping->private_list); 58758ff407bSJan Kara bh->b_assoc_map = mapping; 5881da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 5891da177e4SLinus Torvalds } 5901da177e4SLinus Torvalds } 5911da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 5921da177e4SLinus Torvalds 5931da177e4SLinus Torvalds /* 594787d2214SNick Piggin * Mark the page dirty, and set it dirty in the radix tree, and mark the inode 595787d2214SNick Piggin * dirty. 596787d2214SNick Piggin * 597787d2214SNick Piggin * If warn is true, then emit a warning if the page is not uptodate and has 598787d2214SNick Piggin * not been truncated. 599c4843a75SGreg Thelen * 60081f8c3a4SJohannes Weiner * The caller must hold lock_page_memcg(). 601787d2214SNick Piggin */ 602c4843a75SGreg Thelen static void __set_page_dirty(struct page *page, struct address_space *mapping, 60362cccb8cSJohannes Weiner int warn) 604787d2214SNick Piggin { 605227d53b3SKOSAKI Motohiro unsigned long flags; 606227d53b3SKOSAKI Motohiro 607227d53b3SKOSAKI Motohiro spin_lock_irqsave(&mapping->tree_lock, flags); 608787d2214SNick Piggin if (page->mapping) { /* Race with truncate? */ 609787d2214SNick Piggin WARN_ON_ONCE(warn && !PageUptodate(page)); 61062cccb8cSJohannes Weiner account_page_dirtied(page, mapping); 611787d2214SNick Piggin radix_tree_tag_set(&mapping->page_tree, 612787d2214SNick Piggin page_index(page), PAGECACHE_TAG_DIRTY); 613787d2214SNick Piggin } 614227d53b3SKOSAKI Motohiro spin_unlock_irqrestore(&mapping->tree_lock, flags); 615787d2214SNick Piggin } 616787d2214SNick Piggin 617787d2214SNick Piggin /* 6181da177e4SLinus Torvalds * Add a page to the dirty page list. 6191da177e4SLinus Torvalds * 6201da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 6211da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 6221da177e4SLinus Torvalds * 6231da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 6241da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 6251da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 6261da177e4SLinus Torvalds * dirty. 6271da177e4SLinus Torvalds * 6281da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 6291da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 6301da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 6311da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 6321da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 6331da177e4SLinus Torvalds * page on the dirty page list. 6341da177e4SLinus Torvalds * 6351da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 6361da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 6371da177e4SLinus Torvalds * added to the page after it was set dirty. 6381da177e4SLinus Torvalds * 6391da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 6401da177e4SLinus Torvalds * address_space though. 6411da177e4SLinus Torvalds */ 6421da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 6431da177e4SLinus Torvalds { 644a8e7d49aSLinus Torvalds int newly_dirty; 645787d2214SNick Piggin struct address_space *mapping = page_mapping(page); 646ebf7a227SNick Piggin 647ebf7a227SNick Piggin if (unlikely(!mapping)) 648ebf7a227SNick Piggin return !TestSetPageDirty(page); 6491da177e4SLinus Torvalds 6501da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 6511da177e4SLinus Torvalds if (page_has_buffers(page)) { 6521da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 6531da177e4SLinus Torvalds struct buffer_head *bh = head; 6541da177e4SLinus Torvalds 6551da177e4SLinus Torvalds do { 6561da177e4SLinus Torvalds set_buffer_dirty(bh); 6571da177e4SLinus Torvalds bh = bh->b_this_page; 6581da177e4SLinus Torvalds } while (bh != head); 6591da177e4SLinus Torvalds } 660c4843a75SGreg Thelen /* 66181f8c3a4SJohannes Weiner * Lock out page->mem_cgroup migration to keep PageDirty 66281f8c3a4SJohannes Weiner * synchronized with per-memcg dirty page counters. 663c4843a75SGreg Thelen */ 66462cccb8cSJohannes Weiner lock_page_memcg(page); 665a8e7d49aSLinus Torvalds newly_dirty = !TestSetPageDirty(page); 6661da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 6671da177e4SLinus Torvalds 668a8e7d49aSLinus Torvalds if (newly_dirty) 66962cccb8cSJohannes Weiner __set_page_dirty(page, mapping, 1); 670c4843a75SGreg Thelen 67162cccb8cSJohannes Weiner unlock_page_memcg(page); 672c4843a75SGreg Thelen 673c4843a75SGreg Thelen if (newly_dirty) 674c4843a75SGreg Thelen __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 675c4843a75SGreg Thelen 676a8e7d49aSLinus Torvalds return newly_dirty; 6771da177e4SLinus Torvalds } 6781da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 6791da177e4SLinus Torvalds 6801da177e4SLinus Torvalds /* 6811da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 6821da177e4SLinus Torvalds * 6831da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 6841da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 6851da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 6861da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 6871da177e4SLinus Torvalds * 6881da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 6891da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 6901da177e4SLinus Torvalds * up, waiting for those writes to complete. 6911da177e4SLinus Torvalds * 6921da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 6931da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 6941da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 6951da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 6961da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 6971da177e4SLinus Torvalds * any newly dirty buffers for write. 6981da177e4SLinus Torvalds */ 6991da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 7001da177e4SLinus Torvalds { 7011da177e4SLinus Torvalds struct buffer_head *bh; 7021da177e4SLinus Torvalds struct list_head tmp; 7037eaceaccSJens Axboe struct address_space *mapping; 7041da177e4SLinus Torvalds int err = 0, err2; 7054ee2491eSJens Axboe struct blk_plug plug; 7061da177e4SLinus Torvalds 7071da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 7084ee2491eSJens Axboe blk_start_plug(&plug); 7091da177e4SLinus Torvalds 7101da177e4SLinus Torvalds spin_lock(lock); 7111da177e4SLinus Torvalds while (!list_empty(list)) { 7121da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 713535ee2fbSJan Kara mapping = bh->b_assoc_map; 71458ff407bSJan Kara __remove_assoc_queue(bh); 715535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 716535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 717535ee2fbSJan Kara smp_mb(); 7181da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 7191da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 720535ee2fbSJan Kara bh->b_assoc_map = mapping; 7211da177e4SLinus Torvalds if (buffer_dirty(bh)) { 7221da177e4SLinus Torvalds get_bh(bh); 7231da177e4SLinus Torvalds spin_unlock(lock); 7241da177e4SLinus Torvalds /* 7251da177e4SLinus Torvalds * Ensure any pending I/O completes so that 7269cb569d6SChristoph Hellwig * write_dirty_buffer() actually writes the 7279cb569d6SChristoph Hellwig * current contents - it is a noop if I/O is 7289cb569d6SChristoph Hellwig * still in flight on potentially older 7299cb569d6SChristoph Hellwig * contents. 7301da177e4SLinus Torvalds */ 73170fd7614SChristoph Hellwig write_dirty_buffer(bh, REQ_SYNC); 7329cf6b720SJens Axboe 7339cf6b720SJens Axboe /* 7349cf6b720SJens Axboe * Kick off IO for the previous mapping. Note 7359cf6b720SJens Axboe * that we will not run the very last mapping, 7369cf6b720SJens Axboe * wait_on_buffer() will do that for us 7379cf6b720SJens Axboe * through sync_buffer(). 7389cf6b720SJens Axboe */ 7391da177e4SLinus Torvalds brelse(bh); 7401da177e4SLinus Torvalds spin_lock(lock); 7411da177e4SLinus Torvalds } 7421da177e4SLinus Torvalds } 7431da177e4SLinus Torvalds } 7441da177e4SLinus Torvalds 7454ee2491eSJens Axboe spin_unlock(lock); 7464ee2491eSJens Axboe blk_finish_plug(&plug); 7474ee2491eSJens Axboe spin_lock(lock); 7484ee2491eSJens Axboe 7491da177e4SLinus Torvalds while (!list_empty(&tmp)) { 7501da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 7511da177e4SLinus Torvalds get_bh(bh); 752535ee2fbSJan Kara mapping = bh->b_assoc_map; 753535ee2fbSJan Kara __remove_assoc_queue(bh); 754535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 755535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 756535ee2fbSJan Kara smp_mb(); 757535ee2fbSJan Kara if (buffer_dirty(bh)) { 758535ee2fbSJan Kara list_add(&bh->b_assoc_buffers, 759e3892296SJan Kara &mapping->private_list); 760535ee2fbSJan Kara bh->b_assoc_map = mapping; 761535ee2fbSJan Kara } 7621da177e4SLinus Torvalds spin_unlock(lock); 7631da177e4SLinus Torvalds wait_on_buffer(bh); 7641da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 7651da177e4SLinus Torvalds err = -EIO; 7661da177e4SLinus Torvalds brelse(bh); 7671da177e4SLinus Torvalds spin_lock(lock); 7681da177e4SLinus Torvalds } 7691da177e4SLinus Torvalds 7701da177e4SLinus Torvalds spin_unlock(lock); 7711da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 7721da177e4SLinus Torvalds if (err) 7731da177e4SLinus Torvalds return err; 7741da177e4SLinus Torvalds else 7751da177e4SLinus Torvalds return err2; 7761da177e4SLinus Torvalds } 7771da177e4SLinus Torvalds 7781da177e4SLinus Torvalds /* 7791da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 7801da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 7811da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 7821da177e4SLinus Torvalds * 7831da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 7841da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 7851da177e4SLinus Torvalds * for reiserfs. 7861da177e4SLinus Torvalds */ 7871da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 7881da177e4SLinus Torvalds { 7891da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 7901da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 7911da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 792252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 7931da177e4SLinus Torvalds 7941da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 7951da177e4SLinus Torvalds while (!list_empty(list)) 7961da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 7971da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 7981da177e4SLinus Torvalds } 7991da177e4SLinus Torvalds } 80052b19ac9SJan Kara EXPORT_SYMBOL(invalidate_inode_buffers); 8011da177e4SLinus Torvalds 8021da177e4SLinus Torvalds /* 8031da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 8041da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 8051da177e4SLinus Torvalds * 8061da177e4SLinus Torvalds * Returns true if all buffers were removed. 8071da177e4SLinus Torvalds */ 8081da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 8091da177e4SLinus Torvalds { 8101da177e4SLinus Torvalds int ret = 1; 8111da177e4SLinus Torvalds 8121da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8131da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8141da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 815252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 8161da177e4SLinus Torvalds 8171da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8181da177e4SLinus Torvalds while (!list_empty(list)) { 8191da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 8201da177e4SLinus Torvalds if (buffer_dirty(bh)) { 8211da177e4SLinus Torvalds ret = 0; 8221da177e4SLinus Torvalds break; 8231da177e4SLinus Torvalds } 8241da177e4SLinus Torvalds __remove_assoc_queue(bh); 8251da177e4SLinus Torvalds } 8261da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8271da177e4SLinus Torvalds } 8281da177e4SLinus Torvalds return ret; 8291da177e4SLinus Torvalds } 8301da177e4SLinus Torvalds 8311da177e4SLinus Torvalds /* 8321da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 8331da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 8341da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 8351da177e4SLinus Torvalds * buffers. 8361da177e4SLinus Torvalds * 8371da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 8381da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 8391da177e4SLinus Torvalds */ 8401da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 8411da177e4SLinus Torvalds int retry) 8421da177e4SLinus Torvalds { 8431da177e4SLinus Torvalds struct buffer_head *bh, *head; 8441da177e4SLinus Torvalds long offset; 8451da177e4SLinus Torvalds 8461da177e4SLinus Torvalds try_again: 8471da177e4SLinus Torvalds head = NULL; 8481da177e4SLinus Torvalds offset = PAGE_SIZE; 8491da177e4SLinus Torvalds while ((offset -= size) >= 0) { 8501da177e4SLinus Torvalds bh = alloc_buffer_head(GFP_NOFS); 8511da177e4SLinus Torvalds if (!bh) 8521da177e4SLinus Torvalds goto no_grow; 8531da177e4SLinus Torvalds 8541da177e4SLinus Torvalds bh->b_this_page = head; 8551da177e4SLinus Torvalds bh->b_blocknr = -1; 8561da177e4SLinus Torvalds head = bh; 8571da177e4SLinus Torvalds 8581da177e4SLinus Torvalds bh->b_size = size; 8591da177e4SLinus Torvalds 8601da177e4SLinus Torvalds /* Link the buffer to its page */ 8611da177e4SLinus Torvalds set_bh_page(bh, page, offset); 8621da177e4SLinus Torvalds } 8631da177e4SLinus Torvalds return head; 8641da177e4SLinus Torvalds /* 8651da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 8661da177e4SLinus Torvalds */ 8671da177e4SLinus Torvalds no_grow: 8681da177e4SLinus Torvalds if (head) { 8691da177e4SLinus Torvalds do { 8701da177e4SLinus Torvalds bh = head; 8711da177e4SLinus Torvalds head = head->b_this_page; 8721da177e4SLinus Torvalds free_buffer_head(bh); 8731da177e4SLinus Torvalds } while (head); 8741da177e4SLinus Torvalds } 8751da177e4SLinus Torvalds 8761da177e4SLinus Torvalds /* 8771da177e4SLinus Torvalds * Return failure for non-async IO requests. Async IO requests 8781da177e4SLinus Torvalds * are not allowed to fail, so we have to wait until buffer heads 8791da177e4SLinus Torvalds * become available. But we don't want tasks sleeping with 8801da177e4SLinus Torvalds * partially complete buffers, so all were released above. 8811da177e4SLinus Torvalds */ 8821da177e4SLinus Torvalds if (!retry) 8831da177e4SLinus Torvalds return NULL; 8841da177e4SLinus Torvalds 8851da177e4SLinus Torvalds /* We're _really_ low on memory. Now we just 8861da177e4SLinus Torvalds * wait for old buffer heads to become free due to 8871da177e4SLinus Torvalds * finishing IO. Since this is an async request and 8881da177e4SLinus Torvalds * the reserve list is empty, we're sure there are 8891da177e4SLinus Torvalds * async buffer heads in use. 8901da177e4SLinus Torvalds */ 8911da177e4SLinus Torvalds free_more_memory(); 8921da177e4SLinus Torvalds goto try_again; 8931da177e4SLinus Torvalds } 8941da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 8951da177e4SLinus Torvalds 8961da177e4SLinus Torvalds static inline void 8971da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 8981da177e4SLinus Torvalds { 8991da177e4SLinus Torvalds struct buffer_head *bh, *tail; 9001da177e4SLinus Torvalds 9011da177e4SLinus Torvalds bh = head; 9021da177e4SLinus Torvalds do { 9031da177e4SLinus Torvalds tail = bh; 9041da177e4SLinus Torvalds bh = bh->b_this_page; 9051da177e4SLinus Torvalds } while (bh); 9061da177e4SLinus Torvalds tail->b_this_page = head; 9071da177e4SLinus Torvalds attach_page_buffers(page, head); 9081da177e4SLinus Torvalds } 9091da177e4SLinus Torvalds 910bbec0270SLinus Torvalds static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) 911bbec0270SLinus Torvalds { 912bbec0270SLinus Torvalds sector_t retval = ~((sector_t)0); 913bbec0270SLinus Torvalds loff_t sz = i_size_read(bdev->bd_inode); 914bbec0270SLinus Torvalds 915bbec0270SLinus Torvalds if (sz) { 916bbec0270SLinus Torvalds unsigned int sizebits = blksize_bits(size); 917bbec0270SLinus Torvalds retval = (sz >> sizebits); 918bbec0270SLinus Torvalds } 919bbec0270SLinus Torvalds return retval; 920bbec0270SLinus Torvalds } 921bbec0270SLinus Torvalds 9221da177e4SLinus Torvalds /* 9231da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 9241da177e4SLinus Torvalds */ 925676ce6d5SHugh Dickins static sector_t 9261da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 9271da177e4SLinus Torvalds sector_t block, int size) 9281da177e4SLinus Torvalds { 9291da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 9301da177e4SLinus Torvalds struct buffer_head *bh = head; 9311da177e4SLinus Torvalds int uptodate = PageUptodate(page); 932bbec0270SLinus Torvalds sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size); 9331da177e4SLinus Torvalds 9341da177e4SLinus Torvalds do { 9351da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 9361da177e4SLinus Torvalds init_buffer(bh, NULL, NULL); 9371da177e4SLinus Torvalds bh->b_bdev = bdev; 9381da177e4SLinus Torvalds bh->b_blocknr = block; 9391da177e4SLinus Torvalds if (uptodate) 9401da177e4SLinus Torvalds set_buffer_uptodate(bh); 941080399aaSJeff Moyer if (block < end_block) 9421da177e4SLinus Torvalds set_buffer_mapped(bh); 9431da177e4SLinus Torvalds } 9441da177e4SLinus Torvalds block++; 9451da177e4SLinus Torvalds bh = bh->b_this_page; 9461da177e4SLinus Torvalds } while (bh != head); 947676ce6d5SHugh Dickins 948676ce6d5SHugh Dickins /* 949676ce6d5SHugh Dickins * Caller needs to validate requested block against end of device. 950676ce6d5SHugh Dickins */ 951676ce6d5SHugh Dickins return end_block; 9521da177e4SLinus Torvalds } 9531da177e4SLinus Torvalds 9541da177e4SLinus Torvalds /* 9551da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 9561da177e4SLinus Torvalds * 957676ce6d5SHugh Dickins * This is used purely for blockdev mappings. 9581da177e4SLinus Torvalds */ 959676ce6d5SHugh Dickins static int 9601da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 9613b5e6454SGioh Kim pgoff_t index, int size, int sizebits, gfp_t gfp) 9621da177e4SLinus Torvalds { 9631da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 9641da177e4SLinus Torvalds struct page *page; 9651da177e4SLinus Torvalds struct buffer_head *bh; 966676ce6d5SHugh Dickins sector_t end_block; 967676ce6d5SHugh Dickins int ret = 0; /* Will call free_more_memory() */ 96884235de3SJohannes Weiner gfp_t gfp_mask; 9691da177e4SLinus Torvalds 970c62d2555SMichal Hocko gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp; 9713b5e6454SGioh Kim 97284235de3SJohannes Weiner /* 97384235de3SJohannes Weiner * XXX: __getblk_slow() can not really deal with failure and 97484235de3SJohannes Weiner * will endlessly loop on improvised global reclaim. Prefer 97584235de3SJohannes Weiner * looping in the allocator rather than here, at least that 97684235de3SJohannes Weiner * code knows what it's doing. 97784235de3SJohannes Weiner */ 97884235de3SJohannes Weiner gfp_mask |= __GFP_NOFAIL; 97984235de3SJohannes Weiner 98084235de3SJohannes Weiner page = find_or_create_page(inode->i_mapping, index, gfp_mask); 9811da177e4SLinus Torvalds if (!page) 982676ce6d5SHugh Dickins return ret; 9831da177e4SLinus Torvalds 984e827f923SEric Sesterhenn BUG_ON(!PageLocked(page)); 9851da177e4SLinus Torvalds 9861da177e4SLinus Torvalds if (page_has_buffers(page)) { 9871da177e4SLinus Torvalds bh = page_buffers(page); 9881da177e4SLinus Torvalds if (bh->b_size == size) { 989676ce6d5SHugh Dickins end_block = init_page_buffers(page, bdev, 990f2d5a944SAnton Altaparmakov (sector_t)index << sizebits, 991f2d5a944SAnton Altaparmakov size); 992676ce6d5SHugh Dickins goto done; 9931da177e4SLinus Torvalds } 9941da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 9951da177e4SLinus Torvalds goto failed; 9961da177e4SLinus Torvalds } 9971da177e4SLinus Torvalds 9981da177e4SLinus Torvalds /* 9991da177e4SLinus Torvalds * Allocate some buffers for this page 10001da177e4SLinus Torvalds */ 10011da177e4SLinus Torvalds bh = alloc_page_buffers(page, size, 0); 10021da177e4SLinus Torvalds if (!bh) 10031da177e4SLinus Torvalds goto failed; 10041da177e4SLinus Torvalds 10051da177e4SLinus Torvalds /* 10061da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 10071da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 10081da177e4SLinus Torvalds * run under the page lock. 10091da177e4SLinus Torvalds */ 10101da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 10111da177e4SLinus Torvalds link_dev_buffers(page, bh); 1012f2d5a944SAnton Altaparmakov end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits, 1013f2d5a944SAnton Altaparmakov size); 10141da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 1015676ce6d5SHugh Dickins done: 1016676ce6d5SHugh Dickins ret = (block < end_block) ? 1 : -ENXIO; 10171da177e4SLinus Torvalds failed: 10181da177e4SLinus Torvalds unlock_page(page); 101909cbfeafSKirill A. Shutemov put_page(page); 1020676ce6d5SHugh Dickins return ret; 10211da177e4SLinus Torvalds } 10221da177e4SLinus Torvalds 10231da177e4SLinus Torvalds /* 10241da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 10251da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 10261da177e4SLinus Torvalds */ 1027858119e1SArjan van de Ven static int 10283b5e6454SGioh Kim grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) 10291da177e4SLinus Torvalds { 10301da177e4SLinus Torvalds pgoff_t index; 10311da177e4SLinus Torvalds int sizebits; 10321da177e4SLinus Torvalds 10331da177e4SLinus Torvalds sizebits = -1; 10341da177e4SLinus Torvalds do { 10351da177e4SLinus Torvalds sizebits++; 10361da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 10371da177e4SLinus Torvalds 10381da177e4SLinus Torvalds index = block >> sizebits; 10391da177e4SLinus Torvalds 1040e5657933SAndrew Morton /* 1041e5657933SAndrew Morton * Check for a block which wants to lie outside our maximum possible 1042e5657933SAndrew Morton * pagecache index. (this comparison is done using sector_t types). 1043e5657933SAndrew Morton */ 1044e5657933SAndrew Morton if (unlikely(index != block >> sizebits)) { 1045e5657933SAndrew Morton printk(KERN_ERR "%s: requested out-of-range block %llu for " 1046a1c6f057SDmitry Monakhov "device %pg\n", 10478e24eea7SHarvey Harrison __func__, (unsigned long long)block, 1048a1c6f057SDmitry Monakhov bdev); 1049e5657933SAndrew Morton return -EIO; 1050e5657933SAndrew Morton } 1051676ce6d5SHugh Dickins 10521da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 10533b5e6454SGioh Kim return grow_dev_page(bdev, block, index, size, sizebits, gfp); 10541da177e4SLinus Torvalds } 10551da177e4SLinus Torvalds 10560026ba40SEric Biggers static struct buffer_head * 10573b5e6454SGioh Kim __getblk_slow(struct block_device *bdev, sector_t block, 10583b5e6454SGioh Kim unsigned size, gfp_t gfp) 10591da177e4SLinus Torvalds { 10601da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 1061e1defc4fSMartin K. Petersen if (unlikely(size & (bdev_logical_block_size(bdev)-1) || 10621da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 10631da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 10641da177e4SLinus Torvalds size); 1065e1defc4fSMartin K. Petersen printk(KERN_ERR "logical block size: %d\n", 1066e1defc4fSMartin K. Petersen bdev_logical_block_size(bdev)); 10671da177e4SLinus Torvalds 10681da177e4SLinus Torvalds dump_stack(); 10691da177e4SLinus Torvalds return NULL; 10701da177e4SLinus Torvalds } 10711da177e4SLinus Torvalds 1072676ce6d5SHugh Dickins for (;;) { 1073676ce6d5SHugh Dickins struct buffer_head *bh; 1074676ce6d5SHugh Dickins int ret; 1075676ce6d5SHugh Dickins 10761da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 10771da177e4SLinus Torvalds if (bh) 10781da177e4SLinus Torvalds return bh; 10791da177e4SLinus Torvalds 10803b5e6454SGioh Kim ret = grow_buffers(bdev, block, size, gfp); 1081676ce6d5SHugh Dickins if (ret < 0) 108291f68c89SJeff Moyer return NULL; 1083676ce6d5SHugh Dickins if (ret == 0) 1084676ce6d5SHugh Dickins free_more_memory(); 1085676ce6d5SHugh Dickins } 10861da177e4SLinus Torvalds } 10871da177e4SLinus Torvalds 10881da177e4SLinus Torvalds /* 10891da177e4SLinus Torvalds * The relationship between dirty buffers and dirty pages: 10901da177e4SLinus Torvalds * 10911da177e4SLinus Torvalds * Whenever a page has any dirty buffers, the page's dirty bit is set, and 10921da177e4SLinus Torvalds * the page is tagged dirty in its radix tree. 10931da177e4SLinus Torvalds * 10941da177e4SLinus Torvalds * At all times, the dirtiness of the buffers represents the dirtiness of 10951da177e4SLinus Torvalds * subsections of the page. If the page has buffers, the page dirty bit is 10961da177e4SLinus Torvalds * merely a hint about the true dirty state. 10971da177e4SLinus Torvalds * 10981da177e4SLinus Torvalds * When a page is set dirty in its entirety, all its buffers are marked dirty 10991da177e4SLinus Torvalds * (if the page has buffers). 11001da177e4SLinus Torvalds * 11011da177e4SLinus Torvalds * When a buffer is marked dirty, its page is dirtied, but the page's other 11021da177e4SLinus Torvalds * buffers are not. 11031da177e4SLinus Torvalds * 11041da177e4SLinus Torvalds * Also. When blockdev buffers are explicitly read with bread(), they 11051da177e4SLinus Torvalds * individually become uptodate. But their backing page remains not 11061da177e4SLinus Torvalds * uptodate - even if all of its buffers are uptodate. A subsequent 11071da177e4SLinus Torvalds * block_read_full_page() against that page will discover all the uptodate 11081da177e4SLinus Torvalds * buffers, will set the page uptodate and will perform no I/O. 11091da177e4SLinus Torvalds */ 11101da177e4SLinus Torvalds 11111da177e4SLinus Torvalds /** 11121da177e4SLinus Torvalds * mark_buffer_dirty - mark a buffer_head as needing writeout 111367be2dd1SMartin Waitz * @bh: the buffer_head to mark dirty 11141da177e4SLinus Torvalds * 11151da177e4SLinus Torvalds * mark_buffer_dirty() will set the dirty bit against the buffer, then set its 11161da177e4SLinus Torvalds * backing page dirty, then tag the page as dirty in its address_space's radix 11171da177e4SLinus Torvalds * tree and then attach the address_space's inode to its superblock's dirty 11181da177e4SLinus Torvalds * inode list. 11191da177e4SLinus Torvalds * 11201da177e4SLinus Torvalds * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, 1121250df6edSDave Chinner * mapping->tree_lock and mapping->host->i_lock. 11221da177e4SLinus Torvalds */ 1123fc9b52cdSHarvey Harrison void mark_buffer_dirty(struct buffer_head *bh) 11241da177e4SLinus Torvalds { 1125787d2214SNick Piggin WARN_ON_ONCE(!buffer_uptodate(bh)); 11261be62dc1SLinus Torvalds 11275305cb83STejun Heo trace_block_dirty_buffer(bh); 11285305cb83STejun Heo 11291be62dc1SLinus Torvalds /* 11301be62dc1SLinus Torvalds * Very *carefully* optimize the it-is-already-dirty case. 11311be62dc1SLinus Torvalds * 11321be62dc1SLinus Torvalds * Don't let the final "is it dirty" escape to before we 11331be62dc1SLinus Torvalds * perhaps modified the buffer. 11341be62dc1SLinus Torvalds */ 11351be62dc1SLinus Torvalds if (buffer_dirty(bh)) { 11361be62dc1SLinus Torvalds smp_mb(); 11371be62dc1SLinus Torvalds if (buffer_dirty(bh)) 11381be62dc1SLinus Torvalds return; 11391be62dc1SLinus Torvalds } 11401be62dc1SLinus Torvalds 1141a8e7d49aSLinus Torvalds if (!test_set_buffer_dirty(bh)) { 1142a8e7d49aSLinus Torvalds struct page *page = bh->b_page; 1143c4843a75SGreg Thelen struct address_space *mapping = NULL; 1144c4843a75SGreg Thelen 114562cccb8cSJohannes Weiner lock_page_memcg(page); 11468e9d78edSLinus Torvalds if (!TestSetPageDirty(page)) { 1147c4843a75SGreg Thelen mapping = page_mapping(page); 11488e9d78edSLinus Torvalds if (mapping) 114962cccb8cSJohannes Weiner __set_page_dirty(page, mapping, 0); 11508e9d78edSLinus Torvalds } 115162cccb8cSJohannes Weiner unlock_page_memcg(page); 1152c4843a75SGreg Thelen if (mapping) 1153c4843a75SGreg Thelen __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 1154a8e7d49aSLinus Torvalds } 11551da177e4SLinus Torvalds } 11561fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(mark_buffer_dirty); 11571da177e4SLinus Torvalds 115887354e5dSJeff Layton void mark_buffer_write_io_error(struct buffer_head *bh) 115987354e5dSJeff Layton { 116087354e5dSJeff Layton set_buffer_write_io_error(bh); 116187354e5dSJeff Layton /* FIXME: do we need to set this in both places? */ 116287354e5dSJeff Layton if (bh->b_page && bh->b_page->mapping) 116387354e5dSJeff Layton mapping_set_error(bh->b_page->mapping, -EIO); 116487354e5dSJeff Layton if (bh->b_assoc_map) 116587354e5dSJeff Layton mapping_set_error(bh->b_assoc_map, -EIO); 116687354e5dSJeff Layton } 116787354e5dSJeff Layton EXPORT_SYMBOL(mark_buffer_write_io_error); 116887354e5dSJeff Layton 11691da177e4SLinus Torvalds /* 11701da177e4SLinus Torvalds * Decrement a buffer_head's reference count. If all buffers against a page 11711da177e4SLinus Torvalds * have zero reference count, are clean and unlocked, and if the page is clean 11721da177e4SLinus Torvalds * and unlocked then try_to_free_buffers() may strip the buffers from the page 11731da177e4SLinus Torvalds * in preparation for freeing it (sometimes, rarely, buffers are removed from 11741da177e4SLinus Torvalds * a page but it ends up not being freed, and buffers may later be reattached). 11751da177e4SLinus Torvalds */ 11761da177e4SLinus Torvalds void __brelse(struct buffer_head * buf) 11771da177e4SLinus Torvalds { 11781da177e4SLinus Torvalds if (atomic_read(&buf->b_count)) { 11791da177e4SLinus Torvalds put_bh(buf); 11801da177e4SLinus Torvalds return; 11811da177e4SLinus Torvalds } 11825c752ad9SArjan van de Ven WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); 11831da177e4SLinus Torvalds } 11841fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__brelse); 11851da177e4SLinus Torvalds 11861da177e4SLinus Torvalds /* 11871da177e4SLinus Torvalds * bforget() is like brelse(), except it discards any 11881da177e4SLinus Torvalds * potentially dirty data. 11891da177e4SLinus Torvalds */ 11901da177e4SLinus Torvalds void __bforget(struct buffer_head *bh) 11911da177e4SLinus Torvalds { 11921da177e4SLinus Torvalds clear_buffer_dirty(bh); 1193535ee2fbSJan Kara if (bh->b_assoc_map) { 11941da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 11951da177e4SLinus Torvalds 11961da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 11971da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 119858ff407bSJan Kara bh->b_assoc_map = NULL; 11991da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 12001da177e4SLinus Torvalds } 12011da177e4SLinus Torvalds __brelse(bh); 12021da177e4SLinus Torvalds } 12031fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__bforget); 12041da177e4SLinus Torvalds 12051da177e4SLinus Torvalds static struct buffer_head *__bread_slow(struct buffer_head *bh) 12061da177e4SLinus Torvalds { 12071da177e4SLinus Torvalds lock_buffer(bh); 12081da177e4SLinus Torvalds if (buffer_uptodate(bh)) { 12091da177e4SLinus Torvalds unlock_buffer(bh); 12101da177e4SLinus Torvalds return bh; 12111da177e4SLinus Torvalds } else { 12121da177e4SLinus Torvalds get_bh(bh); 12131da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_sync; 12142a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 12151da177e4SLinus Torvalds wait_on_buffer(bh); 12161da177e4SLinus Torvalds if (buffer_uptodate(bh)) 12171da177e4SLinus Torvalds return bh; 12181da177e4SLinus Torvalds } 12191da177e4SLinus Torvalds brelse(bh); 12201da177e4SLinus Torvalds return NULL; 12211da177e4SLinus Torvalds } 12221da177e4SLinus Torvalds 12231da177e4SLinus Torvalds /* 12241da177e4SLinus Torvalds * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). 12251da177e4SLinus Torvalds * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their 12261da177e4SLinus Torvalds * refcount elevated by one when they're in an LRU. A buffer can only appear 12271da177e4SLinus Torvalds * once in a particular CPU's LRU. A single buffer can be present in multiple 12281da177e4SLinus Torvalds * CPU's LRUs at the same time. 12291da177e4SLinus Torvalds * 12301da177e4SLinus Torvalds * This is a transparent caching front-end to sb_bread(), sb_getblk() and 12311da177e4SLinus Torvalds * sb_find_get_block(). 12321da177e4SLinus Torvalds * 12331da177e4SLinus Torvalds * The LRUs themselves only need locking against invalidate_bh_lrus. We use 12341da177e4SLinus Torvalds * a local interrupt disable for that. 12351da177e4SLinus Torvalds */ 12361da177e4SLinus Torvalds 123786cf78d7SSebastien Buisson #define BH_LRU_SIZE 16 12381da177e4SLinus Torvalds 12391da177e4SLinus Torvalds struct bh_lru { 12401da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12411da177e4SLinus Torvalds }; 12421da177e4SLinus Torvalds 12431da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; 12441da177e4SLinus Torvalds 12451da177e4SLinus Torvalds #ifdef CONFIG_SMP 12461da177e4SLinus Torvalds #define bh_lru_lock() local_irq_disable() 12471da177e4SLinus Torvalds #define bh_lru_unlock() local_irq_enable() 12481da177e4SLinus Torvalds #else 12491da177e4SLinus Torvalds #define bh_lru_lock() preempt_disable() 12501da177e4SLinus Torvalds #define bh_lru_unlock() preempt_enable() 12511da177e4SLinus Torvalds #endif 12521da177e4SLinus Torvalds 12531da177e4SLinus Torvalds static inline void check_irqs_on(void) 12541da177e4SLinus Torvalds { 12551da177e4SLinus Torvalds #ifdef irqs_disabled 12561da177e4SLinus Torvalds BUG_ON(irqs_disabled()); 12571da177e4SLinus Torvalds #endif 12581da177e4SLinus Torvalds } 12591da177e4SLinus Torvalds 12601da177e4SLinus Torvalds /* 1261241f01fbSEric Biggers * Install a buffer_head into this cpu's LRU. If not already in the LRU, it is 1262241f01fbSEric Biggers * inserted at the front, and the buffer_head at the back if any is evicted. 1263241f01fbSEric Biggers * Or, if already in the LRU it is moved to the front. 12641da177e4SLinus Torvalds */ 12651da177e4SLinus Torvalds static void bh_lru_install(struct buffer_head *bh) 12661da177e4SLinus Torvalds { 1267241f01fbSEric Biggers struct buffer_head *evictee = bh; 1268241f01fbSEric Biggers struct bh_lru *b; 1269241f01fbSEric Biggers int i; 12701da177e4SLinus Torvalds 12711da177e4SLinus Torvalds check_irqs_on(); 12721da177e4SLinus Torvalds bh_lru_lock(); 1273241f01fbSEric Biggers 1274241f01fbSEric Biggers b = this_cpu_ptr(&bh_lrus); 1275241f01fbSEric Biggers for (i = 0; i < BH_LRU_SIZE; i++) { 1276241f01fbSEric Biggers swap(evictee, b->bhs[i]); 1277241f01fbSEric Biggers if (evictee == bh) { 1278241f01fbSEric Biggers bh_lru_unlock(); 1279241f01fbSEric Biggers return; 1280241f01fbSEric Biggers } 1281241f01fbSEric Biggers } 12821da177e4SLinus Torvalds 12831da177e4SLinus Torvalds get_bh(bh); 12841da177e4SLinus Torvalds bh_lru_unlock(); 1285241f01fbSEric Biggers brelse(evictee); 12861da177e4SLinus Torvalds } 12871da177e4SLinus Torvalds 12881da177e4SLinus Torvalds /* 12891da177e4SLinus Torvalds * Look up the bh in this cpu's LRU. If it's there, move it to the head. 12901da177e4SLinus Torvalds */ 1291858119e1SArjan van de Ven static struct buffer_head * 12923991d3bdSTomasz Kvarsin lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) 12931da177e4SLinus Torvalds { 12941da177e4SLinus Torvalds struct buffer_head *ret = NULL; 12953991d3bdSTomasz Kvarsin unsigned int i; 12961da177e4SLinus Torvalds 12971da177e4SLinus Torvalds check_irqs_on(); 12981da177e4SLinus Torvalds bh_lru_lock(); 12991da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 1300c7b92516SChristoph Lameter struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); 13011da177e4SLinus Torvalds 13029470dd5dSZach Brown if (bh && bh->b_blocknr == block && bh->b_bdev == bdev && 13039470dd5dSZach Brown bh->b_size == size) { 13041da177e4SLinus Torvalds if (i) { 13051da177e4SLinus Torvalds while (i) { 1306c7b92516SChristoph Lameter __this_cpu_write(bh_lrus.bhs[i], 1307c7b92516SChristoph Lameter __this_cpu_read(bh_lrus.bhs[i - 1])); 13081da177e4SLinus Torvalds i--; 13091da177e4SLinus Torvalds } 1310c7b92516SChristoph Lameter __this_cpu_write(bh_lrus.bhs[0], bh); 13111da177e4SLinus Torvalds } 13121da177e4SLinus Torvalds get_bh(bh); 13131da177e4SLinus Torvalds ret = bh; 13141da177e4SLinus Torvalds break; 13151da177e4SLinus Torvalds } 13161da177e4SLinus Torvalds } 13171da177e4SLinus Torvalds bh_lru_unlock(); 13181da177e4SLinus Torvalds return ret; 13191da177e4SLinus Torvalds } 13201da177e4SLinus Torvalds 13211da177e4SLinus Torvalds /* 13221da177e4SLinus Torvalds * Perform a pagecache lookup for the matching buffer. If it's there, refresh 13231da177e4SLinus Torvalds * it in the LRU and mark it as accessed. If it is not present then return 13241da177e4SLinus Torvalds * NULL 13251da177e4SLinus Torvalds */ 13261da177e4SLinus Torvalds struct buffer_head * 13273991d3bdSTomasz Kvarsin __find_get_block(struct block_device *bdev, sector_t block, unsigned size) 13281da177e4SLinus Torvalds { 13291da177e4SLinus Torvalds struct buffer_head *bh = lookup_bh_lru(bdev, block, size); 13301da177e4SLinus Torvalds 13311da177e4SLinus Torvalds if (bh == NULL) { 13322457aec6SMel Gorman /* __find_get_block_slow will mark the page accessed */ 1333385fd4c5SCoywolf Qi Hunt bh = __find_get_block_slow(bdev, block); 13341da177e4SLinus Torvalds if (bh) 13351da177e4SLinus Torvalds bh_lru_install(bh); 13362457aec6SMel Gorman } else 13371da177e4SLinus Torvalds touch_buffer(bh); 13382457aec6SMel Gorman 13391da177e4SLinus Torvalds return bh; 13401da177e4SLinus Torvalds } 13411da177e4SLinus Torvalds EXPORT_SYMBOL(__find_get_block); 13421da177e4SLinus Torvalds 13431da177e4SLinus Torvalds /* 13443b5e6454SGioh Kim * __getblk_gfp() will locate (and, if necessary, create) the buffer_head 13451da177e4SLinus Torvalds * which corresponds to the passed block_device, block and size. The 13461da177e4SLinus Torvalds * returned buffer has its reference count incremented. 13471da177e4SLinus Torvalds * 13483b5e6454SGioh Kim * __getblk_gfp() will lock up the machine if grow_dev_page's 13493b5e6454SGioh Kim * try_to_free_buffers() attempt is failing. FIXME, perhaps? 13501da177e4SLinus Torvalds */ 13511da177e4SLinus Torvalds struct buffer_head * 13523b5e6454SGioh Kim __getblk_gfp(struct block_device *bdev, sector_t block, 13533b5e6454SGioh Kim unsigned size, gfp_t gfp) 13541da177e4SLinus Torvalds { 13551da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, block, size); 13561da177e4SLinus Torvalds 13571da177e4SLinus Torvalds might_sleep(); 13581da177e4SLinus Torvalds if (bh == NULL) 13593b5e6454SGioh Kim bh = __getblk_slow(bdev, block, size, gfp); 13601da177e4SLinus Torvalds return bh; 13611da177e4SLinus Torvalds } 13623b5e6454SGioh Kim EXPORT_SYMBOL(__getblk_gfp); 13631da177e4SLinus Torvalds 13641da177e4SLinus Torvalds /* 13651da177e4SLinus Torvalds * Do async read-ahead on a buffer.. 13661da177e4SLinus Torvalds */ 13673991d3bdSTomasz Kvarsin void __breadahead(struct block_device *bdev, sector_t block, unsigned size) 13681da177e4SLinus Torvalds { 13691da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 1370a3e713b5SAndrew Morton if (likely(bh)) { 137170246286SChristoph Hellwig ll_rw_block(REQ_OP_READ, REQ_RAHEAD, 1, &bh); 13721da177e4SLinus Torvalds brelse(bh); 13731da177e4SLinus Torvalds } 1374a3e713b5SAndrew Morton } 13751da177e4SLinus Torvalds EXPORT_SYMBOL(__breadahead); 13761da177e4SLinus Torvalds 13771da177e4SLinus Torvalds /** 13783b5e6454SGioh Kim * __bread_gfp() - reads a specified block and returns the bh 137967be2dd1SMartin Waitz * @bdev: the block_device to read from 13801da177e4SLinus Torvalds * @block: number of block 13811da177e4SLinus Torvalds * @size: size (in bytes) to read 13823b5e6454SGioh Kim * @gfp: page allocation flag 13831da177e4SLinus Torvalds * 13841da177e4SLinus Torvalds * Reads a specified block, and returns buffer head that contains it. 13853b5e6454SGioh Kim * The page cache can be allocated from non-movable area 13863b5e6454SGioh Kim * not to prevent page migration if you set gfp to zero. 13871da177e4SLinus Torvalds * It returns NULL if the block was unreadable. 13881da177e4SLinus Torvalds */ 13891da177e4SLinus Torvalds struct buffer_head * 13903b5e6454SGioh Kim __bread_gfp(struct block_device *bdev, sector_t block, 13913b5e6454SGioh Kim unsigned size, gfp_t gfp) 13921da177e4SLinus Torvalds { 13933b5e6454SGioh Kim struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp); 13941da177e4SLinus Torvalds 1395a3e713b5SAndrew Morton if (likely(bh) && !buffer_uptodate(bh)) 13961da177e4SLinus Torvalds bh = __bread_slow(bh); 13971da177e4SLinus Torvalds return bh; 13981da177e4SLinus Torvalds } 13993b5e6454SGioh Kim EXPORT_SYMBOL(__bread_gfp); 14001da177e4SLinus Torvalds 14011da177e4SLinus Torvalds /* 14021da177e4SLinus Torvalds * invalidate_bh_lrus() is called rarely - but not only at unmount. 14031da177e4SLinus Torvalds * This doesn't race because it runs in each cpu either in irq 14041da177e4SLinus Torvalds * or with preempt disabled. 14051da177e4SLinus Torvalds */ 14061da177e4SLinus Torvalds static void invalidate_bh_lru(void *arg) 14071da177e4SLinus Torvalds { 14081da177e4SLinus Torvalds struct bh_lru *b = &get_cpu_var(bh_lrus); 14091da177e4SLinus Torvalds int i; 14101da177e4SLinus Torvalds 14111da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 14121da177e4SLinus Torvalds brelse(b->bhs[i]); 14131da177e4SLinus Torvalds b->bhs[i] = NULL; 14141da177e4SLinus Torvalds } 14151da177e4SLinus Torvalds put_cpu_var(bh_lrus); 14161da177e4SLinus Torvalds } 14171da177e4SLinus Torvalds 141842be35d0SGilad Ben-Yossef static bool has_bh_in_lru(int cpu, void *dummy) 141942be35d0SGilad Ben-Yossef { 142042be35d0SGilad Ben-Yossef struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); 142142be35d0SGilad Ben-Yossef int i; 142242be35d0SGilad Ben-Yossef 142342be35d0SGilad Ben-Yossef for (i = 0; i < BH_LRU_SIZE; i++) { 142442be35d0SGilad Ben-Yossef if (b->bhs[i]) 142542be35d0SGilad Ben-Yossef return 1; 142642be35d0SGilad Ben-Yossef } 142742be35d0SGilad Ben-Yossef 142842be35d0SGilad Ben-Yossef return 0; 142942be35d0SGilad Ben-Yossef } 143042be35d0SGilad Ben-Yossef 1431f9a14399SPeter Zijlstra void invalidate_bh_lrus(void) 14321da177e4SLinus Torvalds { 143342be35d0SGilad Ben-Yossef on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); 14341da177e4SLinus Torvalds } 14359db5579bSNick Piggin EXPORT_SYMBOL_GPL(invalidate_bh_lrus); 14361da177e4SLinus Torvalds 14371da177e4SLinus Torvalds void set_bh_page(struct buffer_head *bh, 14381da177e4SLinus Torvalds struct page *page, unsigned long offset) 14391da177e4SLinus Torvalds { 14401da177e4SLinus Torvalds bh->b_page = page; 1441e827f923SEric Sesterhenn BUG_ON(offset >= PAGE_SIZE); 14421da177e4SLinus Torvalds if (PageHighMem(page)) 14431da177e4SLinus Torvalds /* 14441da177e4SLinus Torvalds * This catches illegal uses and preserves the offset: 14451da177e4SLinus Torvalds */ 14461da177e4SLinus Torvalds bh->b_data = (char *)(0 + offset); 14471da177e4SLinus Torvalds else 14481da177e4SLinus Torvalds bh->b_data = page_address(page) + offset; 14491da177e4SLinus Torvalds } 14501da177e4SLinus Torvalds EXPORT_SYMBOL(set_bh_page); 14511da177e4SLinus Torvalds 14521da177e4SLinus Torvalds /* 14531da177e4SLinus Torvalds * Called when truncating a buffer on a page completely. 14541da177e4SLinus Torvalds */ 1455e7470ee8SMel Gorman 1456e7470ee8SMel Gorman /* Bits that are cleared during an invalidate */ 1457e7470ee8SMel Gorman #define BUFFER_FLAGS_DISCARD \ 1458e7470ee8SMel Gorman (1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \ 1459e7470ee8SMel Gorman 1 << BH_Delay | 1 << BH_Unwritten) 1460e7470ee8SMel Gorman 1461858119e1SArjan van de Ven static void discard_buffer(struct buffer_head * bh) 14621da177e4SLinus Torvalds { 1463e7470ee8SMel Gorman unsigned long b_state, b_state_old; 1464e7470ee8SMel Gorman 14651da177e4SLinus Torvalds lock_buffer(bh); 14661da177e4SLinus Torvalds clear_buffer_dirty(bh); 14671da177e4SLinus Torvalds bh->b_bdev = NULL; 1468e7470ee8SMel Gorman b_state = bh->b_state; 1469e7470ee8SMel Gorman for (;;) { 1470e7470ee8SMel Gorman b_state_old = cmpxchg(&bh->b_state, b_state, 1471e7470ee8SMel Gorman (b_state & ~BUFFER_FLAGS_DISCARD)); 1472e7470ee8SMel Gorman if (b_state_old == b_state) 1473e7470ee8SMel Gorman break; 1474e7470ee8SMel Gorman b_state = b_state_old; 1475e7470ee8SMel Gorman } 14761da177e4SLinus Torvalds unlock_buffer(bh); 14771da177e4SLinus Torvalds } 14781da177e4SLinus Torvalds 14791da177e4SLinus Torvalds /** 1480814e1d25SWang Sheng-Hui * block_invalidatepage - invalidate part or all of a buffer-backed page 14811da177e4SLinus Torvalds * 14821da177e4SLinus Torvalds * @page: the page which is affected 1483d47992f8SLukas Czerner * @offset: start of the range to invalidate 1484d47992f8SLukas Czerner * @length: length of the range to invalidate 14851da177e4SLinus Torvalds * 14861da177e4SLinus Torvalds * block_invalidatepage() is called when all or part of the page has become 14871da177e4SLinus Torvalds * invalidated by a truncate operation. 14881da177e4SLinus Torvalds * 14891da177e4SLinus Torvalds * block_invalidatepage() does not have to release all buffers, but it must 14901da177e4SLinus Torvalds * ensure that no dirty buffer is left outside @offset and that no I/O 14911da177e4SLinus Torvalds * is underway against any of the blocks which are outside the truncation 14921da177e4SLinus Torvalds * point. Because the caller is about to free (and possibly reuse) those 14931da177e4SLinus Torvalds * blocks on-disk. 14941da177e4SLinus Torvalds */ 1495d47992f8SLukas Czerner void block_invalidatepage(struct page *page, unsigned int offset, 1496d47992f8SLukas Czerner unsigned int length) 14971da177e4SLinus Torvalds { 14981da177e4SLinus Torvalds struct buffer_head *head, *bh, *next; 14991da177e4SLinus Torvalds unsigned int curr_off = 0; 1500d47992f8SLukas Czerner unsigned int stop = length + offset; 15011da177e4SLinus Torvalds 15021da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 15031da177e4SLinus Torvalds if (!page_has_buffers(page)) 15041da177e4SLinus Torvalds goto out; 15051da177e4SLinus Torvalds 1506d47992f8SLukas Czerner /* 1507d47992f8SLukas Czerner * Check for overflow 1508d47992f8SLukas Czerner */ 150909cbfeafSKirill A. Shutemov BUG_ON(stop > PAGE_SIZE || stop < length); 1510d47992f8SLukas Czerner 15111da177e4SLinus Torvalds head = page_buffers(page); 15121da177e4SLinus Torvalds bh = head; 15131da177e4SLinus Torvalds do { 15141da177e4SLinus Torvalds unsigned int next_off = curr_off + bh->b_size; 15151da177e4SLinus Torvalds next = bh->b_this_page; 15161da177e4SLinus Torvalds 15171da177e4SLinus Torvalds /* 1518d47992f8SLukas Czerner * Are we still fully in range ? 1519d47992f8SLukas Czerner */ 1520d47992f8SLukas Czerner if (next_off > stop) 1521d47992f8SLukas Czerner goto out; 1522d47992f8SLukas Czerner 1523d47992f8SLukas Czerner /* 15241da177e4SLinus Torvalds * is this block fully invalidated? 15251da177e4SLinus Torvalds */ 15261da177e4SLinus Torvalds if (offset <= curr_off) 15271da177e4SLinus Torvalds discard_buffer(bh); 15281da177e4SLinus Torvalds curr_off = next_off; 15291da177e4SLinus Torvalds bh = next; 15301da177e4SLinus Torvalds } while (bh != head); 15311da177e4SLinus Torvalds 15321da177e4SLinus Torvalds /* 15331da177e4SLinus Torvalds * We release buffers only if the entire page is being invalidated. 15341da177e4SLinus Torvalds * The get_block cached value has been unconditionally invalidated, 15351da177e4SLinus Torvalds * so real IO is not possible anymore. 15361da177e4SLinus Torvalds */ 15371da177e4SLinus Torvalds if (offset == 0) 15382ff28e22SNeilBrown try_to_release_page(page, 0); 15391da177e4SLinus Torvalds out: 15402ff28e22SNeilBrown return; 15411da177e4SLinus Torvalds } 15421da177e4SLinus Torvalds EXPORT_SYMBOL(block_invalidatepage); 15431da177e4SLinus Torvalds 1544d47992f8SLukas Czerner 15451da177e4SLinus Torvalds /* 15461da177e4SLinus Torvalds * We attach and possibly dirty the buffers atomically wrt 15471da177e4SLinus Torvalds * __set_page_dirty_buffers() via private_lock. try_to_free_buffers 15481da177e4SLinus Torvalds * is already excluded via the page lock. 15491da177e4SLinus Torvalds */ 15501da177e4SLinus Torvalds void create_empty_buffers(struct page *page, 15511da177e4SLinus Torvalds unsigned long blocksize, unsigned long b_state) 15521da177e4SLinus Torvalds { 15531da177e4SLinus Torvalds struct buffer_head *bh, *head, *tail; 15541da177e4SLinus Torvalds 15551da177e4SLinus Torvalds head = alloc_page_buffers(page, blocksize, 1); 15561da177e4SLinus Torvalds bh = head; 15571da177e4SLinus Torvalds do { 15581da177e4SLinus Torvalds bh->b_state |= b_state; 15591da177e4SLinus Torvalds tail = bh; 15601da177e4SLinus Torvalds bh = bh->b_this_page; 15611da177e4SLinus Torvalds } while (bh); 15621da177e4SLinus Torvalds tail->b_this_page = head; 15631da177e4SLinus Torvalds 15641da177e4SLinus Torvalds spin_lock(&page->mapping->private_lock); 15651da177e4SLinus Torvalds if (PageUptodate(page) || PageDirty(page)) { 15661da177e4SLinus Torvalds bh = head; 15671da177e4SLinus Torvalds do { 15681da177e4SLinus Torvalds if (PageDirty(page)) 15691da177e4SLinus Torvalds set_buffer_dirty(bh); 15701da177e4SLinus Torvalds if (PageUptodate(page)) 15711da177e4SLinus Torvalds set_buffer_uptodate(bh); 15721da177e4SLinus Torvalds bh = bh->b_this_page; 15731da177e4SLinus Torvalds } while (bh != head); 15741da177e4SLinus Torvalds } 15751da177e4SLinus Torvalds attach_page_buffers(page, head); 15761da177e4SLinus Torvalds spin_unlock(&page->mapping->private_lock); 15771da177e4SLinus Torvalds } 15781da177e4SLinus Torvalds EXPORT_SYMBOL(create_empty_buffers); 15791da177e4SLinus Torvalds 158029f3ad7dSJan Kara /** 158129f3ad7dSJan Kara * clean_bdev_aliases: clean a range of buffers in block device 158229f3ad7dSJan Kara * @bdev: Block device to clean buffers in 158329f3ad7dSJan Kara * @block: Start of a range of blocks to clean 158429f3ad7dSJan Kara * @len: Number of blocks to clean 15851da177e4SLinus Torvalds * 158629f3ad7dSJan Kara * We are taking a range of blocks for data and we don't want writeback of any 158729f3ad7dSJan Kara * buffer-cache aliases starting from return from this function and until the 158829f3ad7dSJan Kara * moment when something will explicitly mark the buffer dirty (hopefully that 158929f3ad7dSJan Kara * will not happen until we will free that block ;-) We don't even need to mark 159029f3ad7dSJan Kara * it not-uptodate - nobody can expect anything from a newly allocated buffer 159129f3ad7dSJan Kara * anyway. We used to use unmap_buffer() for such invalidation, but that was 159229f3ad7dSJan Kara * wrong. We definitely don't want to mark the alias unmapped, for example - it 159329f3ad7dSJan Kara * would confuse anyone who might pick it with bread() afterwards... 159429f3ad7dSJan Kara * 159529f3ad7dSJan Kara * Also.. Note that bforget() doesn't lock the buffer. So there can be 159629f3ad7dSJan Kara * writeout I/O going on against recently-freed buffers. We don't wait on that 159729f3ad7dSJan Kara * I/O in bforget() - it's more efficient to wait on the I/O only if we really 159829f3ad7dSJan Kara * need to. That happens here. 15991da177e4SLinus Torvalds */ 160029f3ad7dSJan Kara void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) 16011da177e4SLinus Torvalds { 160229f3ad7dSJan Kara struct inode *bd_inode = bdev->bd_inode; 160329f3ad7dSJan Kara struct address_space *bd_mapping = bd_inode->i_mapping; 160429f3ad7dSJan Kara struct pagevec pvec; 160529f3ad7dSJan Kara pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); 160629f3ad7dSJan Kara pgoff_t end; 1607c10f778dSJan Kara int i, count; 160829f3ad7dSJan Kara struct buffer_head *bh; 160929f3ad7dSJan Kara struct buffer_head *head; 16101da177e4SLinus Torvalds 161129f3ad7dSJan Kara end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits); 161229f3ad7dSJan Kara pagevec_init(&pvec, 0); 1613397162ffSJan Kara while (pagevec_lookup_range(&pvec, bd_mapping, &index, end)) { 1614c10f778dSJan Kara count = pagevec_count(&pvec); 1615c10f778dSJan Kara for (i = 0; i < count; i++) { 161629f3ad7dSJan Kara struct page *page = pvec.pages[i]; 16171da177e4SLinus Torvalds 161829f3ad7dSJan Kara if (!page_has_buffers(page)) 161929f3ad7dSJan Kara continue; 162029f3ad7dSJan Kara /* 162129f3ad7dSJan Kara * We use page lock instead of bd_mapping->private_lock 162229f3ad7dSJan Kara * to pin buffers here since we can afford to sleep and 162329f3ad7dSJan Kara * it scales better than a global spinlock lock. 162429f3ad7dSJan Kara */ 162529f3ad7dSJan Kara lock_page(page); 162629f3ad7dSJan Kara /* Recheck when the page is locked which pins bhs */ 162729f3ad7dSJan Kara if (!page_has_buffers(page)) 162829f3ad7dSJan Kara goto unlock_page; 162929f3ad7dSJan Kara head = page_buffers(page); 163029f3ad7dSJan Kara bh = head; 163129f3ad7dSJan Kara do { 16326c006a9dSChandan Rajendra if (!buffer_mapped(bh) || (bh->b_blocknr < block)) 163329f3ad7dSJan Kara goto next; 163429f3ad7dSJan Kara if (bh->b_blocknr >= block + len) 163529f3ad7dSJan Kara break; 163629f3ad7dSJan Kara clear_buffer_dirty(bh); 163729f3ad7dSJan Kara wait_on_buffer(bh); 163829f3ad7dSJan Kara clear_buffer_req(bh); 163929f3ad7dSJan Kara next: 164029f3ad7dSJan Kara bh = bh->b_this_page; 164129f3ad7dSJan Kara } while (bh != head); 164229f3ad7dSJan Kara unlock_page: 164329f3ad7dSJan Kara unlock_page(page); 164429f3ad7dSJan Kara } 164529f3ad7dSJan Kara pagevec_release(&pvec); 164629f3ad7dSJan Kara cond_resched(); 1647c10f778dSJan Kara /* End of range already reached? */ 1648c10f778dSJan Kara if (index > end || !index) 1649c10f778dSJan Kara break; 16501da177e4SLinus Torvalds } 16511da177e4SLinus Torvalds } 165229f3ad7dSJan Kara EXPORT_SYMBOL(clean_bdev_aliases); 16531da177e4SLinus Torvalds 16541da177e4SLinus Torvalds /* 165545bce8f3SLinus Torvalds * Size is a power-of-two in the range 512..PAGE_SIZE, 165645bce8f3SLinus Torvalds * and the case we care about most is PAGE_SIZE. 165745bce8f3SLinus Torvalds * 165845bce8f3SLinus Torvalds * So this *could* possibly be written with those 165945bce8f3SLinus Torvalds * constraints in mind (relevant mostly if some 166045bce8f3SLinus Torvalds * architecture has a slow bit-scan instruction) 166145bce8f3SLinus Torvalds */ 166245bce8f3SLinus Torvalds static inline int block_size_bits(unsigned int blocksize) 166345bce8f3SLinus Torvalds { 166445bce8f3SLinus Torvalds return ilog2(blocksize); 166545bce8f3SLinus Torvalds } 166645bce8f3SLinus Torvalds 166745bce8f3SLinus Torvalds static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state) 166845bce8f3SLinus Torvalds { 166945bce8f3SLinus Torvalds BUG_ON(!PageLocked(page)); 167045bce8f3SLinus Torvalds 167145bce8f3SLinus Torvalds if (!page_has_buffers(page)) 167245bce8f3SLinus Torvalds create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state); 167345bce8f3SLinus Torvalds return page_buffers(page); 167445bce8f3SLinus Torvalds } 167545bce8f3SLinus Torvalds 167645bce8f3SLinus Torvalds /* 16771da177e4SLinus Torvalds * NOTE! All mapped/uptodate combinations are valid: 16781da177e4SLinus Torvalds * 16791da177e4SLinus Torvalds * Mapped Uptodate Meaning 16801da177e4SLinus Torvalds * 16811da177e4SLinus Torvalds * No No "unknown" - must do get_block() 16821da177e4SLinus Torvalds * No Yes "hole" - zero-filled 16831da177e4SLinus Torvalds * Yes No "allocated" - allocated on disk, not read in 16841da177e4SLinus Torvalds * Yes Yes "valid" - allocated and up-to-date in memory. 16851da177e4SLinus Torvalds * 16861da177e4SLinus Torvalds * "Dirty" is valid only with the last case (mapped+uptodate). 16871da177e4SLinus Torvalds */ 16881da177e4SLinus Torvalds 16891da177e4SLinus Torvalds /* 16901da177e4SLinus Torvalds * While block_write_full_page is writing back the dirty buffers under 16911da177e4SLinus Torvalds * the page lock, whoever dirtied the buffers may decide to clean them 16921da177e4SLinus Torvalds * again at any time. We handle that by only looking at the buffer 16931da177e4SLinus Torvalds * state inside lock_buffer(). 16941da177e4SLinus Torvalds * 16951da177e4SLinus Torvalds * If block_write_full_page() is called for regular writeback 16961da177e4SLinus Torvalds * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a 16971da177e4SLinus Torvalds * locked buffer. This only can happen if someone has written the buffer 16981da177e4SLinus Torvalds * directly, with submit_bh(). At the address_space level PageWriteback 16991da177e4SLinus Torvalds * prevents this contention from occurring. 17006e34eeddSTheodore Ts'o * 17016e34eeddSTheodore Ts'o * If block_write_full_page() is called with wbc->sync_mode == 170270fd7614SChristoph Hellwig * WB_SYNC_ALL, the writes are posted using REQ_SYNC; this 1703721a9602SJens Axboe * causes the writes to be flagged as synchronous writes. 17041da177e4SLinus Torvalds */ 1705b4bba389SBenjamin Marzinski int __block_write_full_page(struct inode *inode, struct page *page, 170635c80d5fSChris Mason get_block_t *get_block, struct writeback_control *wbc, 170735c80d5fSChris Mason bh_end_io_t *handler) 17081da177e4SLinus Torvalds { 17091da177e4SLinus Torvalds int err; 17101da177e4SLinus Torvalds sector_t block; 17111da177e4SLinus Torvalds sector_t last_block; 1712f0fbd5fcSAndrew Morton struct buffer_head *bh, *head; 171345bce8f3SLinus Torvalds unsigned int blocksize, bbits; 17141da177e4SLinus Torvalds int nr_underway = 0; 17157637241eSJens Axboe int write_flags = wbc_to_write_flags(wbc); 17161da177e4SLinus Torvalds 171745bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 17181da177e4SLinus Torvalds (1 << BH_Dirty)|(1 << BH_Uptodate)); 17191da177e4SLinus Torvalds 17201da177e4SLinus Torvalds /* 17211da177e4SLinus Torvalds * Be very careful. We have no exclusion from __set_page_dirty_buffers 17221da177e4SLinus Torvalds * here, and the (potentially unmapped) buffers may become dirty at 17231da177e4SLinus Torvalds * any time. If a buffer becomes dirty here after we've inspected it 17241da177e4SLinus Torvalds * then we just miss that fact, and the page stays dirty. 17251da177e4SLinus Torvalds * 17261da177e4SLinus Torvalds * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; 17271da177e4SLinus Torvalds * handle that here by just cleaning them. 17281da177e4SLinus Torvalds */ 17291da177e4SLinus Torvalds 17301da177e4SLinus Torvalds bh = head; 173145bce8f3SLinus Torvalds blocksize = bh->b_size; 173245bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 173345bce8f3SLinus Torvalds 173409cbfeafSKirill A. Shutemov block = (sector_t)page->index << (PAGE_SHIFT - bbits); 173545bce8f3SLinus Torvalds last_block = (i_size_read(inode) - 1) >> bbits; 17361da177e4SLinus Torvalds 17371da177e4SLinus Torvalds /* 17381da177e4SLinus Torvalds * Get all the dirty buffers mapped to disk addresses and 17391da177e4SLinus Torvalds * handle any aliases from the underlying blockdev's mapping. 17401da177e4SLinus Torvalds */ 17411da177e4SLinus Torvalds do { 17421da177e4SLinus Torvalds if (block > last_block) { 17431da177e4SLinus Torvalds /* 17441da177e4SLinus Torvalds * mapped buffers outside i_size will occur, because 17451da177e4SLinus Torvalds * this page can be outside i_size when there is a 17461da177e4SLinus Torvalds * truncate in progress. 17471da177e4SLinus Torvalds */ 17481da177e4SLinus Torvalds /* 17491da177e4SLinus Torvalds * The buffer was zeroed by block_write_full_page() 17501da177e4SLinus Torvalds */ 17511da177e4SLinus Torvalds clear_buffer_dirty(bh); 17521da177e4SLinus Torvalds set_buffer_uptodate(bh); 175329a814d2SAlex Tomas } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && 175429a814d2SAlex Tomas buffer_dirty(bh)) { 1755b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 17561da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 17571da177e4SLinus Torvalds if (err) 17581da177e4SLinus Torvalds goto recover; 175929a814d2SAlex Tomas clear_buffer_delay(bh); 17601da177e4SLinus Torvalds if (buffer_new(bh)) { 17611da177e4SLinus Torvalds /* blockdev mappings never come here */ 17621da177e4SLinus Torvalds clear_buffer_new(bh); 1763e64855c6SJan Kara clean_bdev_bh_alias(bh); 17641da177e4SLinus Torvalds } 17651da177e4SLinus Torvalds } 17661da177e4SLinus Torvalds bh = bh->b_this_page; 17671da177e4SLinus Torvalds block++; 17681da177e4SLinus Torvalds } while (bh != head); 17691da177e4SLinus Torvalds 17701da177e4SLinus Torvalds do { 17711da177e4SLinus Torvalds if (!buffer_mapped(bh)) 17721da177e4SLinus Torvalds continue; 17731da177e4SLinus Torvalds /* 17741da177e4SLinus Torvalds * If it's a fully non-blocking write attempt and we cannot 17751da177e4SLinus Torvalds * lock the buffer then redirty the page. Note that this can 17765b0830cbSJens Axboe * potentially cause a busy-wait loop from writeback threads 17775b0830cbSJens Axboe * and kswapd activity, but those code paths have their own 17785b0830cbSJens Axboe * higher-level throttling. 17791da177e4SLinus Torvalds */ 17801b430beeSWu Fengguang if (wbc->sync_mode != WB_SYNC_NONE) { 17811da177e4SLinus Torvalds lock_buffer(bh); 1782ca5de404SNick Piggin } else if (!trylock_buffer(bh)) { 17831da177e4SLinus Torvalds redirty_page_for_writepage(wbc, page); 17841da177e4SLinus Torvalds continue; 17851da177e4SLinus Torvalds } 17861da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 178735c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 17881da177e4SLinus Torvalds } else { 17891da177e4SLinus Torvalds unlock_buffer(bh); 17901da177e4SLinus Torvalds } 17911da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17921da177e4SLinus Torvalds 17931da177e4SLinus Torvalds /* 17941da177e4SLinus Torvalds * The page and its buffers are protected by PageWriteback(), so we can 17951da177e4SLinus Torvalds * drop the bh refcounts early. 17961da177e4SLinus Torvalds */ 17971da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17981da177e4SLinus Torvalds set_page_writeback(page); 17991da177e4SLinus Torvalds 18001da177e4SLinus Torvalds do { 18011da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 18021da177e4SLinus Torvalds if (buffer_async_write(bh)) { 18038e8f9298SJens Axboe submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, 18048e8f9298SJens Axboe inode->i_write_hint, wbc); 18051da177e4SLinus Torvalds nr_underway++; 1806ad576e63SNick Piggin } 18071da177e4SLinus Torvalds bh = next; 18081da177e4SLinus Torvalds } while (bh != head); 180905937baaSAndrew Morton unlock_page(page); 18101da177e4SLinus Torvalds 18111da177e4SLinus Torvalds err = 0; 18121da177e4SLinus Torvalds done: 18131da177e4SLinus Torvalds if (nr_underway == 0) { 18141da177e4SLinus Torvalds /* 18151da177e4SLinus Torvalds * The page was marked dirty, but the buffers were 18161da177e4SLinus Torvalds * clean. Someone wrote them back by hand with 18171da177e4SLinus Torvalds * ll_rw_block/submit_bh. A rare case. 18181da177e4SLinus Torvalds */ 18191da177e4SLinus Torvalds end_page_writeback(page); 18203d67f2d7SNick Piggin 18211da177e4SLinus Torvalds /* 18221da177e4SLinus Torvalds * The page and buffer_heads can be released at any time from 18231da177e4SLinus Torvalds * here on. 18241da177e4SLinus Torvalds */ 18251da177e4SLinus Torvalds } 18261da177e4SLinus Torvalds return err; 18271da177e4SLinus Torvalds 18281da177e4SLinus Torvalds recover: 18291da177e4SLinus Torvalds /* 18301da177e4SLinus Torvalds * ENOSPC, or some other error. We may already have added some 18311da177e4SLinus Torvalds * blocks to the file, so we need to write these out to avoid 18321da177e4SLinus Torvalds * exposing stale data. 18331da177e4SLinus Torvalds * The page is currently locked and not marked for writeback 18341da177e4SLinus Torvalds */ 18351da177e4SLinus Torvalds bh = head; 18361da177e4SLinus Torvalds /* Recovery: lock and submit the mapped buffers */ 18371da177e4SLinus Torvalds do { 183829a814d2SAlex Tomas if (buffer_mapped(bh) && buffer_dirty(bh) && 183929a814d2SAlex Tomas !buffer_delay(bh)) { 18401da177e4SLinus Torvalds lock_buffer(bh); 184135c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 18421da177e4SLinus Torvalds } else { 18431da177e4SLinus Torvalds /* 18441da177e4SLinus Torvalds * The buffer may have been set dirty during 18451da177e4SLinus Torvalds * attachment to a dirty page. 18461da177e4SLinus Torvalds */ 18471da177e4SLinus Torvalds clear_buffer_dirty(bh); 18481da177e4SLinus Torvalds } 18491da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 18501da177e4SLinus Torvalds SetPageError(page); 18511da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 18527e4c3690SAndrew Morton mapping_set_error(page->mapping, err); 18531da177e4SLinus Torvalds set_page_writeback(page); 18541da177e4SLinus Torvalds do { 18551da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 18561da177e4SLinus Torvalds if (buffer_async_write(bh)) { 18571da177e4SLinus Torvalds clear_buffer_dirty(bh); 18588e8f9298SJens Axboe submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, 18598e8f9298SJens Axboe inode->i_write_hint, wbc); 18601da177e4SLinus Torvalds nr_underway++; 1861ad576e63SNick Piggin } 18621da177e4SLinus Torvalds bh = next; 18631da177e4SLinus Torvalds } while (bh != head); 1864ffda9d30SNick Piggin unlock_page(page); 18651da177e4SLinus Torvalds goto done; 18661da177e4SLinus Torvalds } 1867b4bba389SBenjamin Marzinski EXPORT_SYMBOL(__block_write_full_page); 18681da177e4SLinus Torvalds 1869afddba49SNick Piggin /* 1870afddba49SNick Piggin * If a page has any new buffers, zero them out here, and mark them uptodate 1871afddba49SNick Piggin * and dirty so they'll be written out (in order to prevent uninitialised 1872afddba49SNick Piggin * block data from leaking). And clear the new bit. 1873afddba49SNick Piggin */ 1874afddba49SNick Piggin void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) 1875afddba49SNick Piggin { 1876afddba49SNick Piggin unsigned int block_start, block_end; 1877afddba49SNick Piggin struct buffer_head *head, *bh; 1878afddba49SNick Piggin 1879afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1880afddba49SNick Piggin if (!page_has_buffers(page)) 1881afddba49SNick Piggin return; 1882afddba49SNick Piggin 1883afddba49SNick Piggin bh = head = page_buffers(page); 1884afddba49SNick Piggin block_start = 0; 1885afddba49SNick Piggin do { 1886afddba49SNick Piggin block_end = block_start + bh->b_size; 1887afddba49SNick Piggin 1888afddba49SNick Piggin if (buffer_new(bh)) { 1889afddba49SNick Piggin if (block_end > from && block_start < to) { 1890afddba49SNick Piggin if (!PageUptodate(page)) { 1891afddba49SNick Piggin unsigned start, size; 1892afddba49SNick Piggin 1893afddba49SNick Piggin start = max(from, block_start); 1894afddba49SNick Piggin size = min(to, block_end) - start; 1895afddba49SNick Piggin 1896eebd2aa3SChristoph Lameter zero_user(page, start, size); 1897afddba49SNick Piggin set_buffer_uptodate(bh); 1898afddba49SNick Piggin } 1899afddba49SNick Piggin 1900afddba49SNick Piggin clear_buffer_new(bh); 1901afddba49SNick Piggin mark_buffer_dirty(bh); 1902afddba49SNick Piggin } 1903afddba49SNick Piggin } 1904afddba49SNick Piggin 1905afddba49SNick Piggin block_start = block_end; 1906afddba49SNick Piggin bh = bh->b_this_page; 1907afddba49SNick Piggin } while (bh != head); 1908afddba49SNick Piggin } 1909afddba49SNick Piggin EXPORT_SYMBOL(page_zero_new_buffers); 1910afddba49SNick Piggin 1911ae259a9cSChristoph Hellwig static void 1912ae259a9cSChristoph Hellwig iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, 1913ae259a9cSChristoph Hellwig struct iomap *iomap) 1914ae259a9cSChristoph Hellwig { 1915ae259a9cSChristoph Hellwig loff_t offset = block << inode->i_blkbits; 1916ae259a9cSChristoph Hellwig 1917ae259a9cSChristoph Hellwig bh->b_bdev = iomap->bdev; 1918ae259a9cSChristoph Hellwig 1919ae259a9cSChristoph Hellwig /* 1920ae259a9cSChristoph Hellwig * Block points to offset in file we need to map, iomap contains 1921ae259a9cSChristoph Hellwig * the offset at which the map starts. If the map ends before the 1922ae259a9cSChristoph Hellwig * current block, then do not map the buffer and let the caller 1923ae259a9cSChristoph Hellwig * handle it. 1924ae259a9cSChristoph Hellwig */ 1925ae259a9cSChristoph Hellwig BUG_ON(offset >= iomap->offset + iomap->length); 1926ae259a9cSChristoph Hellwig 1927ae259a9cSChristoph Hellwig switch (iomap->type) { 1928ae259a9cSChristoph Hellwig case IOMAP_HOLE: 1929ae259a9cSChristoph Hellwig /* 1930ae259a9cSChristoph Hellwig * If the buffer is not up to date or beyond the current EOF, 1931ae259a9cSChristoph Hellwig * we need to mark it as new to ensure sub-block zeroing is 1932ae259a9cSChristoph Hellwig * executed if necessary. 1933ae259a9cSChristoph Hellwig */ 1934ae259a9cSChristoph Hellwig if (!buffer_uptodate(bh) || 1935ae259a9cSChristoph Hellwig (offset >= i_size_read(inode))) 1936ae259a9cSChristoph Hellwig set_buffer_new(bh); 1937ae259a9cSChristoph Hellwig break; 1938ae259a9cSChristoph Hellwig case IOMAP_DELALLOC: 1939ae259a9cSChristoph Hellwig if (!buffer_uptodate(bh) || 1940ae259a9cSChristoph Hellwig (offset >= i_size_read(inode))) 1941ae259a9cSChristoph Hellwig set_buffer_new(bh); 1942ae259a9cSChristoph Hellwig set_buffer_uptodate(bh); 1943ae259a9cSChristoph Hellwig set_buffer_mapped(bh); 1944ae259a9cSChristoph Hellwig set_buffer_delay(bh); 1945ae259a9cSChristoph Hellwig break; 1946ae259a9cSChristoph Hellwig case IOMAP_UNWRITTEN: 1947ae259a9cSChristoph Hellwig /* 1948ae259a9cSChristoph Hellwig * For unwritten regions, we always need to ensure that 1949ae259a9cSChristoph Hellwig * sub-block writes cause the regions in the block we are not 1950ae259a9cSChristoph Hellwig * writing to are zeroed. Set the buffer as new to ensure this. 1951ae259a9cSChristoph Hellwig */ 1952ae259a9cSChristoph Hellwig set_buffer_new(bh); 1953ae259a9cSChristoph Hellwig set_buffer_unwritten(bh); 1954ae259a9cSChristoph Hellwig /* FALLTHRU */ 1955ae259a9cSChristoph Hellwig case IOMAP_MAPPED: 1956ae259a9cSChristoph Hellwig if (offset >= i_size_read(inode)) 1957ae259a9cSChristoph Hellwig set_buffer_new(bh); 1958ae259a9cSChristoph Hellwig bh->b_blocknr = (iomap->blkno >> (inode->i_blkbits - 9)) + 1959ae259a9cSChristoph Hellwig ((offset - iomap->offset) >> inode->i_blkbits); 1960ae259a9cSChristoph Hellwig set_buffer_mapped(bh); 1961ae259a9cSChristoph Hellwig break; 1962ae259a9cSChristoph Hellwig } 1963ae259a9cSChristoph Hellwig } 1964ae259a9cSChristoph Hellwig 1965ae259a9cSChristoph Hellwig int __block_write_begin_int(struct page *page, loff_t pos, unsigned len, 1966ae259a9cSChristoph Hellwig get_block_t *get_block, struct iomap *iomap) 19671da177e4SLinus Torvalds { 196809cbfeafSKirill A. Shutemov unsigned from = pos & (PAGE_SIZE - 1); 1969ebdec241SChristoph Hellwig unsigned to = from + len; 19706e1db88dSChristoph Hellwig struct inode *inode = page->mapping->host; 19711da177e4SLinus Torvalds unsigned block_start, block_end; 19721da177e4SLinus Torvalds sector_t block; 19731da177e4SLinus Torvalds int err = 0; 19741da177e4SLinus Torvalds unsigned blocksize, bbits; 19751da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 19761da177e4SLinus Torvalds 19771da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 197809cbfeafSKirill A. Shutemov BUG_ON(from > PAGE_SIZE); 197909cbfeafSKirill A. Shutemov BUG_ON(to > PAGE_SIZE); 19801da177e4SLinus Torvalds BUG_ON(from > to); 19811da177e4SLinus Torvalds 198245bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 198345bce8f3SLinus Torvalds blocksize = head->b_size; 198445bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 19851da177e4SLinus Torvalds 198609cbfeafSKirill A. Shutemov block = (sector_t)page->index << (PAGE_SHIFT - bbits); 19871da177e4SLinus Torvalds 19881da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 19891da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 19901da177e4SLinus Torvalds block_end = block_start + blocksize; 19911da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19921da177e4SLinus Torvalds if (PageUptodate(page)) { 19931da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19941da177e4SLinus Torvalds set_buffer_uptodate(bh); 19951da177e4SLinus Torvalds } 19961da177e4SLinus Torvalds continue; 19971da177e4SLinus Torvalds } 19981da177e4SLinus Torvalds if (buffer_new(bh)) 19991da177e4SLinus Torvalds clear_buffer_new(bh); 20001da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2001b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 2002ae259a9cSChristoph Hellwig if (get_block) { 20031da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 20041da177e4SLinus Torvalds if (err) 2005f3ddbdc6SNick Piggin break; 2006ae259a9cSChristoph Hellwig } else { 2007ae259a9cSChristoph Hellwig iomap_to_bh(inode, block, bh, iomap); 2008ae259a9cSChristoph Hellwig } 2009ae259a9cSChristoph Hellwig 20101da177e4SLinus Torvalds if (buffer_new(bh)) { 2011e64855c6SJan Kara clean_bdev_bh_alias(bh); 20121da177e4SLinus Torvalds if (PageUptodate(page)) { 2013637aff46SNick Piggin clear_buffer_new(bh); 20141da177e4SLinus Torvalds set_buffer_uptodate(bh); 2015637aff46SNick Piggin mark_buffer_dirty(bh); 20161da177e4SLinus Torvalds continue; 20171da177e4SLinus Torvalds } 2018eebd2aa3SChristoph Lameter if (block_end > to || block_start < from) 2019eebd2aa3SChristoph Lameter zero_user_segments(page, 2020eebd2aa3SChristoph Lameter to, block_end, 2021eebd2aa3SChristoph Lameter block_start, from); 20221da177e4SLinus Torvalds continue; 20231da177e4SLinus Torvalds } 20241da177e4SLinus Torvalds } 20251da177e4SLinus Torvalds if (PageUptodate(page)) { 20261da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 20271da177e4SLinus Torvalds set_buffer_uptodate(bh); 20281da177e4SLinus Torvalds continue; 20291da177e4SLinus Torvalds } 20301da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 203133a266ddSDavid Chinner !buffer_unwritten(bh) && 20321da177e4SLinus Torvalds (block_start < from || block_end > to)) { 2033dfec8a14SMike Christie ll_rw_block(REQ_OP_READ, 0, 1, &bh); 20341da177e4SLinus Torvalds *wait_bh++=bh; 20351da177e4SLinus Torvalds } 20361da177e4SLinus Torvalds } 20371da177e4SLinus Torvalds /* 20381da177e4SLinus Torvalds * If we issued read requests - let them complete. 20391da177e4SLinus Torvalds */ 20401da177e4SLinus Torvalds while(wait_bh > wait) { 20411da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 20421da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 2043f3ddbdc6SNick Piggin err = -EIO; 20441da177e4SLinus Torvalds } 2045f9f07b6cSJan Kara if (unlikely(err)) 2046afddba49SNick Piggin page_zero_new_buffers(page, from, to); 20471da177e4SLinus Torvalds return err; 20481da177e4SLinus Torvalds } 2049ae259a9cSChristoph Hellwig 2050ae259a9cSChristoph Hellwig int __block_write_begin(struct page *page, loff_t pos, unsigned len, 2051ae259a9cSChristoph Hellwig get_block_t *get_block) 2052ae259a9cSChristoph Hellwig { 2053ae259a9cSChristoph Hellwig return __block_write_begin_int(page, pos, len, get_block, NULL); 2054ae259a9cSChristoph Hellwig } 2055ebdec241SChristoph Hellwig EXPORT_SYMBOL(__block_write_begin); 20561da177e4SLinus Torvalds 20571da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 20581da177e4SLinus Torvalds unsigned from, unsigned to) 20591da177e4SLinus Torvalds { 20601da177e4SLinus Torvalds unsigned block_start, block_end; 20611da177e4SLinus Torvalds int partial = 0; 20621da177e4SLinus Torvalds unsigned blocksize; 20631da177e4SLinus Torvalds struct buffer_head *bh, *head; 20641da177e4SLinus Torvalds 206545bce8f3SLinus Torvalds bh = head = page_buffers(page); 206645bce8f3SLinus Torvalds blocksize = bh->b_size; 20671da177e4SLinus Torvalds 206845bce8f3SLinus Torvalds block_start = 0; 206945bce8f3SLinus Torvalds do { 20701da177e4SLinus Torvalds block_end = block_start + blocksize; 20711da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 20721da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 20731da177e4SLinus Torvalds partial = 1; 20741da177e4SLinus Torvalds } else { 20751da177e4SLinus Torvalds set_buffer_uptodate(bh); 20761da177e4SLinus Torvalds mark_buffer_dirty(bh); 20771da177e4SLinus Torvalds } 2078afddba49SNick Piggin clear_buffer_new(bh); 207945bce8f3SLinus Torvalds 208045bce8f3SLinus Torvalds block_start = block_end; 208145bce8f3SLinus Torvalds bh = bh->b_this_page; 208245bce8f3SLinus Torvalds } while (bh != head); 20831da177e4SLinus Torvalds 20841da177e4SLinus Torvalds /* 20851da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 20861da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 20871da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 20881da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 20891da177e4SLinus Torvalds */ 20901da177e4SLinus Torvalds if (!partial) 20911da177e4SLinus Torvalds SetPageUptodate(page); 20921da177e4SLinus Torvalds return 0; 20931da177e4SLinus Torvalds } 20941da177e4SLinus Torvalds 20951da177e4SLinus Torvalds /* 2096155130a4SChristoph Hellwig * block_write_begin takes care of the basic task of block allocation and 2097155130a4SChristoph Hellwig * bringing partial write blocks uptodate first. 2098155130a4SChristoph Hellwig * 20997bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 2100afddba49SNick Piggin */ 2101155130a4SChristoph Hellwig int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, 2102155130a4SChristoph Hellwig unsigned flags, struct page **pagep, get_block_t *get_block) 2103afddba49SNick Piggin { 210409cbfeafSKirill A. Shutemov pgoff_t index = pos >> PAGE_SHIFT; 2105afddba49SNick Piggin struct page *page; 21066e1db88dSChristoph Hellwig int status; 2107afddba49SNick Piggin 210854566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 21096e1db88dSChristoph Hellwig if (!page) 21106e1db88dSChristoph Hellwig return -ENOMEM; 2111afddba49SNick Piggin 21126e1db88dSChristoph Hellwig status = __block_write_begin(page, pos, len, get_block); 2113afddba49SNick Piggin if (unlikely(status)) { 2114afddba49SNick Piggin unlock_page(page); 211509cbfeafSKirill A. Shutemov put_page(page); 21166e1db88dSChristoph Hellwig page = NULL; 2117afddba49SNick Piggin } 2118afddba49SNick Piggin 21196e1db88dSChristoph Hellwig *pagep = page; 2120afddba49SNick Piggin return status; 2121afddba49SNick Piggin } 2122afddba49SNick Piggin EXPORT_SYMBOL(block_write_begin); 2123afddba49SNick Piggin 2124afddba49SNick Piggin int block_write_end(struct file *file, struct address_space *mapping, 2125afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2126afddba49SNick Piggin struct page *page, void *fsdata) 2127afddba49SNick Piggin { 2128afddba49SNick Piggin struct inode *inode = mapping->host; 2129afddba49SNick Piggin unsigned start; 2130afddba49SNick Piggin 213109cbfeafSKirill A. Shutemov start = pos & (PAGE_SIZE - 1); 2132afddba49SNick Piggin 2133afddba49SNick Piggin if (unlikely(copied < len)) { 2134afddba49SNick Piggin /* 2135afddba49SNick Piggin * The buffers that were written will now be uptodate, so we 2136afddba49SNick Piggin * don't have to worry about a readpage reading them and 2137afddba49SNick Piggin * overwriting a partial write. However if we have encountered 2138afddba49SNick Piggin * a short write and only partially written into a buffer, it 2139afddba49SNick Piggin * will not be marked uptodate, so a readpage might come in and 2140afddba49SNick Piggin * destroy our partial write. 2141afddba49SNick Piggin * 2142afddba49SNick Piggin * Do the simplest thing, and just treat any short write to a 2143afddba49SNick Piggin * non uptodate page as a zero-length write, and force the 2144afddba49SNick Piggin * caller to redo the whole thing. 2145afddba49SNick Piggin */ 2146afddba49SNick Piggin if (!PageUptodate(page)) 2147afddba49SNick Piggin copied = 0; 2148afddba49SNick Piggin 2149afddba49SNick Piggin page_zero_new_buffers(page, start+copied, start+len); 2150afddba49SNick Piggin } 2151afddba49SNick Piggin flush_dcache_page(page); 2152afddba49SNick Piggin 2153afddba49SNick Piggin /* This could be a short (even 0-length) commit */ 2154afddba49SNick Piggin __block_commit_write(inode, page, start, start+copied); 2155afddba49SNick Piggin 2156afddba49SNick Piggin return copied; 2157afddba49SNick Piggin } 2158afddba49SNick Piggin EXPORT_SYMBOL(block_write_end); 2159afddba49SNick Piggin 2160afddba49SNick Piggin int generic_write_end(struct file *file, struct address_space *mapping, 2161afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2162afddba49SNick Piggin struct page *page, void *fsdata) 2163afddba49SNick Piggin { 2164afddba49SNick Piggin struct inode *inode = mapping->host; 216590a80202SJan Kara loff_t old_size = inode->i_size; 2166c7d206b3SJan Kara int i_size_changed = 0; 2167afddba49SNick Piggin 2168afddba49SNick Piggin copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); 2169afddba49SNick Piggin 2170afddba49SNick Piggin /* 2171afddba49SNick Piggin * No need to use i_size_read() here, the i_size 2172afddba49SNick Piggin * cannot change under us because we hold i_mutex. 2173afddba49SNick Piggin * 2174afddba49SNick Piggin * But it's important to update i_size while still holding page lock: 2175afddba49SNick Piggin * page writeout could otherwise come in and zero beyond i_size. 2176afddba49SNick Piggin */ 2177afddba49SNick Piggin if (pos+copied > inode->i_size) { 2178afddba49SNick Piggin i_size_write(inode, pos+copied); 2179c7d206b3SJan Kara i_size_changed = 1; 2180afddba49SNick Piggin } 2181afddba49SNick Piggin 2182afddba49SNick Piggin unlock_page(page); 218309cbfeafSKirill A. Shutemov put_page(page); 2184afddba49SNick Piggin 218590a80202SJan Kara if (old_size < pos) 218690a80202SJan Kara pagecache_isize_extended(inode, old_size, pos); 2187c7d206b3SJan Kara /* 2188c7d206b3SJan Kara * Don't mark the inode dirty under page lock. First, it unnecessarily 2189c7d206b3SJan Kara * makes the holding time of page lock longer. Second, it forces lock 2190c7d206b3SJan Kara * ordering of page lock and transaction start for journaling 2191c7d206b3SJan Kara * filesystems. 2192c7d206b3SJan Kara */ 2193c7d206b3SJan Kara if (i_size_changed) 2194c7d206b3SJan Kara mark_inode_dirty(inode); 2195c7d206b3SJan Kara 2196afddba49SNick Piggin return copied; 2197afddba49SNick Piggin } 2198afddba49SNick Piggin EXPORT_SYMBOL(generic_write_end); 2199afddba49SNick Piggin 2200afddba49SNick Piggin /* 22018ab22b9aSHisashi Hifumi * block_is_partially_uptodate checks whether buffers within a page are 22028ab22b9aSHisashi Hifumi * uptodate or not. 22038ab22b9aSHisashi Hifumi * 22048ab22b9aSHisashi Hifumi * Returns true if all buffers which correspond to a file portion 22058ab22b9aSHisashi Hifumi * we want to read are uptodate. 22068ab22b9aSHisashi Hifumi */ 2207c186afb4SAl Viro int block_is_partially_uptodate(struct page *page, unsigned long from, 2208c186afb4SAl Viro unsigned long count) 22098ab22b9aSHisashi Hifumi { 22108ab22b9aSHisashi Hifumi unsigned block_start, block_end, blocksize; 22118ab22b9aSHisashi Hifumi unsigned to; 22128ab22b9aSHisashi Hifumi struct buffer_head *bh, *head; 22138ab22b9aSHisashi Hifumi int ret = 1; 22148ab22b9aSHisashi Hifumi 22158ab22b9aSHisashi Hifumi if (!page_has_buffers(page)) 22168ab22b9aSHisashi Hifumi return 0; 22178ab22b9aSHisashi Hifumi 221845bce8f3SLinus Torvalds head = page_buffers(page); 221945bce8f3SLinus Torvalds blocksize = head->b_size; 222009cbfeafSKirill A. Shutemov to = min_t(unsigned, PAGE_SIZE - from, count); 22218ab22b9aSHisashi Hifumi to = from + to; 222209cbfeafSKirill A. Shutemov if (from < blocksize && to > PAGE_SIZE - blocksize) 22238ab22b9aSHisashi Hifumi return 0; 22248ab22b9aSHisashi Hifumi 22258ab22b9aSHisashi Hifumi bh = head; 22268ab22b9aSHisashi Hifumi block_start = 0; 22278ab22b9aSHisashi Hifumi do { 22288ab22b9aSHisashi Hifumi block_end = block_start + blocksize; 22298ab22b9aSHisashi Hifumi if (block_end > from && block_start < to) { 22308ab22b9aSHisashi Hifumi if (!buffer_uptodate(bh)) { 22318ab22b9aSHisashi Hifumi ret = 0; 22328ab22b9aSHisashi Hifumi break; 22338ab22b9aSHisashi Hifumi } 22348ab22b9aSHisashi Hifumi if (block_end >= to) 22358ab22b9aSHisashi Hifumi break; 22368ab22b9aSHisashi Hifumi } 22378ab22b9aSHisashi Hifumi block_start = block_end; 22388ab22b9aSHisashi Hifumi bh = bh->b_this_page; 22398ab22b9aSHisashi Hifumi } while (bh != head); 22408ab22b9aSHisashi Hifumi 22418ab22b9aSHisashi Hifumi return ret; 22428ab22b9aSHisashi Hifumi } 22438ab22b9aSHisashi Hifumi EXPORT_SYMBOL(block_is_partially_uptodate); 22448ab22b9aSHisashi Hifumi 22458ab22b9aSHisashi Hifumi /* 22461da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 22471da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 22481da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 22491da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 22501da177e4SLinus Torvalds * page struct once IO has completed. 22511da177e4SLinus Torvalds */ 22521da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 22531da177e4SLinus Torvalds { 22541da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 22551da177e4SLinus Torvalds sector_t iblock, lblock; 22561da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 225745bce8f3SLinus Torvalds unsigned int blocksize, bbits; 22581da177e4SLinus Torvalds int nr, i; 22591da177e4SLinus Torvalds int fully_mapped = 1; 22601da177e4SLinus Torvalds 226145bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 226245bce8f3SLinus Torvalds blocksize = head->b_size; 226345bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 22641da177e4SLinus Torvalds 226509cbfeafSKirill A. Shutemov iblock = (sector_t)page->index << (PAGE_SHIFT - bbits); 226645bce8f3SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> bbits; 22671da177e4SLinus Torvalds bh = head; 22681da177e4SLinus Torvalds nr = 0; 22691da177e4SLinus Torvalds i = 0; 22701da177e4SLinus Torvalds 22711da177e4SLinus Torvalds do { 22721da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22731da177e4SLinus Torvalds continue; 22741da177e4SLinus Torvalds 22751da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2276c64610baSAndrew Morton int err = 0; 2277c64610baSAndrew Morton 22781da177e4SLinus Torvalds fully_mapped = 0; 22791da177e4SLinus Torvalds if (iblock < lblock) { 2280b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 2281c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 2282c64610baSAndrew Morton if (err) 22831da177e4SLinus Torvalds SetPageError(page); 22841da177e4SLinus Torvalds } 22851da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2286eebd2aa3SChristoph Lameter zero_user(page, i * blocksize, blocksize); 2287c64610baSAndrew Morton if (!err) 22881da177e4SLinus Torvalds set_buffer_uptodate(bh); 22891da177e4SLinus Torvalds continue; 22901da177e4SLinus Torvalds } 22911da177e4SLinus Torvalds /* 22921da177e4SLinus Torvalds * get_block() might have updated the buffer 22931da177e4SLinus Torvalds * synchronously 22941da177e4SLinus Torvalds */ 22951da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22961da177e4SLinus Torvalds continue; 22971da177e4SLinus Torvalds } 22981da177e4SLinus Torvalds arr[nr++] = bh; 22991da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 23001da177e4SLinus Torvalds 23011da177e4SLinus Torvalds if (fully_mapped) 23021da177e4SLinus Torvalds SetPageMappedToDisk(page); 23031da177e4SLinus Torvalds 23041da177e4SLinus Torvalds if (!nr) { 23051da177e4SLinus Torvalds /* 23061da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 23071da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 23081da177e4SLinus Torvalds */ 23091da177e4SLinus Torvalds if (!PageError(page)) 23101da177e4SLinus Torvalds SetPageUptodate(page); 23111da177e4SLinus Torvalds unlock_page(page); 23121da177e4SLinus Torvalds return 0; 23131da177e4SLinus Torvalds } 23141da177e4SLinus Torvalds 23151da177e4SLinus Torvalds /* Stage two: lock the buffers */ 23161da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 23171da177e4SLinus Torvalds bh = arr[i]; 23181da177e4SLinus Torvalds lock_buffer(bh); 23191da177e4SLinus Torvalds mark_buffer_async_read(bh); 23201da177e4SLinus Torvalds } 23211da177e4SLinus Torvalds 23221da177e4SLinus Torvalds /* 23231da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 23241da177e4SLinus Torvalds * inside the buffer lock in case another process reading 23251da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 23261da177e4SLinus Torvalds */ 23271da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 23281da177e4SLinus Torvalds bh = arr[i]; 23291da177e4SLinus Torvalds if (buffer_uptodate(bh)) 23301da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 23311da177e4SLinus Torvalds else 23322a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 23331da177e4SLinus Torvalds } 23341da177e4SLinus Torvalds return 0; 23351da177e4SLinus Torvalds } 23361fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_read_full_page); 23371da177e4SLinus Torvalds 23381da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 233989e10787SNick Piggin * truncates. Uses filesystem pagecache writes to allow the filesystem to 23401da177e4SLinus Torvalds * deal with the hole. 23411da177e4SLinus Torvalds */ 234289e10787SNick Piggin int generic_cont_expand_simple(struct inode *inode, loff_t size) 23431da177e4SLinus Torvalds { 23441da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 23451da177e4SLinus Torvalds struct page *page; 234689e10787SNick Piggin void *fsdata; 23471da177e4SLinus Torvalds int err; 23481da177e4SLinus Torvalds 2349c08d3b0eSnpiggin@suse.de err = inode_newsize_ok(inode, size); 2350c08d3b0eSnpiggin@suse.de if (err) 23511da177e4SLinus Torvalds goto out; 23521da177e4SLinus Torvalds 235389e10787SNick Piggin err = pagecache_write_begin(NULL, mapping, size, 0, 2354c718a975STetsuo Handa AOP_FLAG_CONT_EXPAND, &page, &fsdata); 235589e10787SNick Piggin if (err) 235605eb0b51SOGAWA Hirofumi goto out; 235705eb0b51SOGAWA Hirofumi 235889e10787SNick Piggin err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); 235989e10787SNick Piggin BUG_ON(err > 0); 236005eb0b51SOGAWA Hirofumi 236105eb0b51SOGAWA Hirofumi out: 236205eb0b51SOGAWA Hirofumi return err; 236305eb0b51SOGAWA Hirofumi } 23641fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_cont_expand_simple); 236505eb0b51SOGAWA Hirofumi 2366f1e3af72SAdrian Bunk static int cont_expand_zero(struct file *file, struct address_space *mapping, 236789e10787SNick Piggin loff_t pos, loff_t *bytes) 236805eb0b51SOGAWA Hirofumi { 236989e10787SNick Piggin struct inode *inode = mapping->host; 237093407472SFabian Frederick unsigned int blocksize = i_blocksize(inode); 237189e10787SNick Piggin struct page *page; 237289e10787SNick Piggin void *fsdata; 237389e10787SNick Piggin pgoff_t index, curidx; 237489e10787SNick Piggin loff_t curpos; 237589e10787SNick Piggin unsigned zerofrom, offset, len; 237689e10787SNick Piggin int err = 0; 237705eb0b51SOGAWA Hirofumi 237809cbfeafSKirill A. Shutemov index = pos >> PAGE_SHIFT; 237909cbfeafSKirill A. Shutemov offset = pos & ~PAGE_MASK; 238089e10787SNick Piggin 238109cbfeafSKirill A. Shutemov while (index > (curidx = (curpos = *bytes)>>PAGE_SHIFT)) { 238209cbfeafSKirill A. Shutemov zerofrom = curpos & ~PAGE_MASK; 238389e10787SNick Piggin if (zerofrom & (blocksize-1)) { 238489e10787SNick Piggin *bytes |= (blocksize-1); 238589e10787SNick Piggin (*bytes)++; 238689e10787SNick Piggin } 238709cbfeafSKirill A. Shutemov len = PAGE_SIZE - zerofrom; 238889e10787SNick Piggin 2389c718a975STetsuo Handa err = pagecache_write_begin(file, mapping, curpos, len, 0, 239089e10787SNick Piggin &page, &fsdata); 239189e10787SNick Piggin if (err) 239289e10787SNick Piggin goto out; 2393eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 239489e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 239589e10787SNick Piggin page, fsdata); 239689e10787SNick Piggin if (err < 0) 239789e10787SNick Piggin goto out; 239889e10787SNick Piggin BUG_ON(err != len); 239989e10787SNick Piggin err = 0; 2400061e9746SOGAWA Hirofumi 2401061e9746SOGAWA Hirofumi balance_dirty_pages_ratelimited(mapping); 2402c2ca0fcdSMikulas Patocka 2403c2ca0fcdSMikulas Patocka if (unlikely(fatal_signal_pending(current))) { 2404c2ca0fcdSMikulas Patocka err = -EINTR; 2405c2ca0fcdSMikulas Patocka goto out; 2406c2ca0fcdSMikulas Patocka } 240789e10787SNick Piggin } 240889e10787SNick Piggin 240989e10787SNick Piggin /* page covers the boundary, find the boundary offset */ 241089e10787SNick Piggin if (index == curidx) { 241109cbfeafSKirill A. Shutemov zerofrom = curpos & ~PAGE_MASK; 241289e10787SNick Piggin /* if we will expand the thing last block will be filled */ 241389e10787SNick Piggin if (offset <= zerofrom) { 241489e10787SNick Piggin goto out; 241589e10787SNick Piggin } 241689e10787SNick Piggin if (zerofrom & (blocksize-1)) { 241789e10787SNick Piggin *bytes |= (blocksize-1); 241889e10787SNick Piggin (*bytes)++; 241989e10787SNick Piggin } 242089e10787SNick Piggin len = offset - zerofrom; 242189e10787SNick Piggin 2422c718a975STetsuo Handa err = pagecache_write_begin(file, mapping, curpos, len, 0, 242389e10787SNick Piggin &page, &fsdata); 242489e10787SNick Piggin if (err) 242589e10787SNick Piggin goto out; 2426eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 242789e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 242889e10787SNick Piggin page, fsdata); 242989e10787SNick Piggin if (err < 0) 243089e10787SNick Piggin goto out; 243189e10787SNick Piggin BUG_ON(err != len); 243289e10787SNick Piggin err = 0; 243389e10787SNick Piggin } 243489e10787SNick Piggin out: 243589e10787SNick Piggin return err; 24361da177e4SLinus Torvalds } 24371da177e4SLinus Torvalds 24381da177e4SLinus Torvalds /* 24391da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 24401da177e4SLinus Torvalds * We may have to extend the file. 24411da177e4SLinus Torvalds */ 2442282dc178SChristoph Hellwig int cont_write_begin(struct file *file, struct address_space *mapping, 244389e10787SNick Piggin loff_t pos, unsigned len, unsigned flags, 244489e10787SNick Piggin struct page **pagep, void **fsdata, 244589e10787SNick Piggin get_block_t *get_block, loff_t *bytes) 24461da177e4SLinus Torvalds { 24471da177e4SLinus Torvalds struct inode *inode = mapping->host; 244893407472SFabian Frederick unsigned int blocksize = i_blocksize(inode); 244993407472SFabian Frederick unsigned int zerofrom; 245089e10787SNick Piggin int err; 24511da177e4SLinus Torvalds 245289e10787SNick Piggin err = cont_expand_zero(file, mapping, pos, bytes); 245389e10787SNick Piggin if (err) 2454155130a4SChristoph Hellwig return err; 24551da177e4SLinus Torvalds 245609cbfeafSKirill A. Shutemov zerofrom = *bytes & ~PAGE_MASK; 245789e10787SNick Piggin if (pos+len > *bytes && zerofrom & (blocksize-1)) { 24581da177e4SLinus Torvalds *bytes |= (blocksize-1); 24591da177e4SLinus Torvalds (*bytes)++; 24601da177e4SLinus Torvalds } 24611da177e4SLinus Torvalds 2462155130a4SChristoph Hellwig return block_write_begin(mapping, pos, len, flags, pagep, get_block); 24631da177e4SLinus Torvalds } 24641fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(cont_write_begin); 24651da177e4SLinus Torvalds 24661da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 24671da177e4SLinus Torvalds { 24681da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 24691da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 24701da177e4SLinus Torvalds return 0; 24711da177e4SLinus Torvalds } 24721fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_commit_write); 24731da177e4SLinus Torvalds 247454171690SDavid Chinner /* 247554171690SDavid Chinner * block_page_mkwrite() is not allowed to change the file size as it gets 247654171690SDavid Chinner * called from a page fault handler when a page is first dirtied. Hence we must 247754171690SDavid Chinner * be careful to check for EOF conditions here. We set the page up correctly 247854171690SDavid Chinner * for a written page which means we get ENOSPC checking when writing into 247954171690SDavid Chinner * holes and correct delalloc and unwritten extent mapping on filesystems that 248054171690SDavid Chinner * support these features. 248154171690SDavid Chinner * 248254171690SDavid Chinner * We are not allowed to take the i_mutex here so we have to play games to 248354171690SDavid Chinner * protect against truncate races as the page could now be beyond EOF. Because 24847bb46a67Snpiggin@suse.de * truncate writes the inode size before removing pages, once we have the 248554171690SDavid Chinner * page lock we can determine safely if the page is beyond EOF. If it is not 248654171690SDavid Chinner * beyond EOF, then the page is guaranteed safe against truncation until we 248754171690SDavid Chinner * unlock the page. 2488ea13a864SJan Kara * 248914da9200SJan Kara * Direct callers of this function should protect against filesystem freezing 24905c500029SRoss Zwisler * using sb_start_pagefault() - sb_end_pagefault() functions. 249154171690SDavid Chinner */ 24925c500029SRoss Zwisler int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 249354171690SDavid Chinner get_block_t get_block) 249454171690SDavid Chinner { 2495c2ec175cSNick Piggin struct page *page = vmf->page; 2496496ad9aaSAl Viro struct inode *inode = file_inode(vma->vm_file); 249754171690SDavid Chinner unsigned long end; 249854171690SDavid Chinner loff_t size; 249924da4fabSJan Kara int ret; 250054171690SDavid Chinner 250154171690SDavid Chinner lock_page(page); 250254171690SDavid Chinner size = i_size_read(inode); 250354171690SDavid Chinner if ((page->mapping != inode->i_mapping) || 250418336338SNick Piggin (page_offset(page) > size)) { 250524da4fabSJan Kara /* We overload EFAULT to mean page got truncated */ 250624da4fabSJan Kara ret = -EFAULT; 250724da4fabSJan Kara goto out_unlock; 250854171690SDavid Chinner } 250954171690SDavid Chinner 251054171690SDavid Chinner /* page is wholly or partially inside EOF */ 251109cbfeafSKirill A. Shutemov if (((page->index + 1) << PAGE_SHIFT) > size) 251209cbfeafSKirill A. Shutemov end = size & ~PAGE_MASK; 251354171690SDavid Chinner else 251409cbfeafSKirill A. Shutemov end = PAGE_SIZE; 251554171690SDavid Chinner 2516ebdec241SChristoph Hellwig ret = __block_write_begin(page, 0, end, get_block); 251754171690SDavid Chinner if (!ret) 251854171690SDavid Chinner ret = block_commit_write(page, 0, end); 251954171690SDavid Chinner 252024da4fabSJan Kara if (unlikely(ret < 0)) 252124da4fabSJan Kara goto out_unlock; 2522ea13a864SJan Kara set_page_dirty(page); 25231d1d1a76SDarrick J. Wong wait_for_stable_page(page); 252424da4fabSJan Kara return 0; 252524da4fabSJan Kara out_unlock: 2526b827e496SNick Piggin unlock_page(page); 252754171690SDavid Chinner return ret; 252854171690SDavid Chinner } 25291fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_page_mkwrite); 25301da177e4SLinus Torvalds 25311da177e4SLinus Torvalds /* 253203158cd7SNick Piggin * nobh_write_begin()'s prereads are special: the buffer_heads are freed 25331da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 25341da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 25351da177e4SLinus Torvalds */ 25361da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 25371da177e4SLinus Torvalds { 253868671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 25391da177e4SLinus Torvalds } 25401da177e4SLinus Torvalds 25411da177e4SLinus Torvalds /* 254203158cd7SNick Piggin * Attach the singly-linked list of buffers created by nobh_write_begin, to 254303158cd7SNick Piggin * the page (converting it to circular linked list and taking care of page 254403158cd7SNick Piggin * dirty races). 254503158cd7SNick Piggin */ 254603158cd7SNick Piggin static void attach_nobh_buffers(struct page *page, struct buffer_head *head) 254703158cd7SNick Piggin { 254803158cd7SNick Piggin struct buffer_head *bh; 254903158cd7SNick Piggin 255003158cd7SNick Piggin BUG_ON(!PageLocked(page)); 255103158cd7SNick Piggin 255203158cd7SNick Piggin spin_lock(&page->mapping->private_lock); 255303158cd7SNick Piggin bh = head; 255403158cd7SNick Piggin do { 255503158cd7SNick Piggin if (PageDirty(page)) 255603158cd7SNick Piggin set_buffer_dirty(bh); 255703158cd7SNick Piggin if (!bh->b_this_page) 255803158cd7SNick Piggin bh->b_this_page = head; 255903158cd7SNick Piggin bh = bh->b_this_page; 256003158cd7SNick Piggin } while (bh != head); 256103158cd7SNick Piggin attach_page_buffers(page, head); 256203158cd7SNick Piggin spin_unlock(&page->mapping->private_lock); 256303158cd7SNick Piggin } 256403158cd7SNick Piggin 256503158cd7SNick Piggin /* 2566ea0f04e5SChristoph Hellwig * On entry, the page is fully not uptodate. 2567ea0f04e5SChristoph Hellwig * On exit the page is fully uptodate in the areas outside (from,to) 25687bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 25691da177e4SLinus Torvalds */ 2570ea0f04e5SChristoph Hellwig int nobh_write_begin(struct address_space *mapping, 257103158cd7SNick Piggin loff_t pos, unsigned len, unsigned flags, 257203158cd7SNick Piggin struct page **pagep, void **fsdata, 25731da177e4SLinus Torvalds get_block_t *get_block) 25741da177e4SLinus Torvalds { 257503158cd7SNick Piggin struct inode *inode = mapping->host; 25761da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 25771da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 2578a4b0672dSNick Piggin struct buffer_head *head, *bh; 257903158cd7SNick Piggin struct page *page; 258003158cd7SNick Piggin pgoff_t index; 258103158cd7SNick Piggin unsigned from, to; 25821da177e4SLinus Torvalds unsigned block_in_page; 2583a4b0672dSNick Piggin unsigned block_start, block_end; 25841da177e4SLinus Torvalds sector_t block_in_file; 25851da177e4SLinus Torvalds int nr_reads = 0; 25861da177e4SLinus Torvalds int ret = 0; 25871da177e4SLinus Torvalds int is_mapped_to_disk = 1; 25881da177e4SLinus Torvalds 258909cbfeafSKirill A. Shutemov index = pos >> PAGE_SHIFT; 259009cbfeafSKirill A. Shutemov from = pos & (PAGE_SIZE - 1); 259103158cd7SNick Piggin to = from + len; 259203158cd7SNick Piggin 259354566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 259403158cd7SNick Piggin if (!page) 259503158cd7SNick Piggin return -ENOMEM; 259603158cd7SNick Piggin *pagep = page; 259703158cd7SNick Piggin *fsdata = NULL; 259803158cd7SNick Piggin 259903158cd7SNick Piggin if (page_has_buffers(page)) { 2600309f77adSNamhyung Kim ret = __block_write_begin(page, pos, len, get_block); 2601309f77adSNamhyung Kim if (unlikely(ret)) 2602309f77adSNamhyung Kim goto out_release; 2603309f77adSNamhyung Kim return ret; 260403158cd7SNick Piggin } 2605a4b0672dSNick Piggin 26061da177e4SLinus Torvalds if (PageMappedToDisk(page)) 26071da177e4SLinus Torvalds return 0; 26081da177e4SLinus Torvalds 2609a4b0672dSNick Piggin /* 2610a4b0672dSNick Piggin * Allocate buffers so that we can keep track of state, and potentially 2611a4b0672dSNick Piggin * attach them to the page if an error occurs. In the common case of 2612a4b0672dSNick Piggin * no error, they will just be freed again without ever being attached 2613a4b0672dSNick Piggin * to the page (which is all OK, because we're under the page lock). 2614a4b0672dSNick Piggin * 2615a4b0672dSNick Piggin * Be careful: the buffer linked list is a NULL terminated one, rather 2616a4b0672dSNick Piggin * than the circular one we're used to. 2617a4b0672dSNick Piggin */ 2618a4b0672dSNick Piggin head = alloc_page_buffers(page, blocksize, 0); 261903158cd7SNick Piggin if (!head) { 262003158cd7SNick Piggin ret = -ENOMEM; 262103158cd7SNick Piggin goto out_release; 262203158cd7SNick Piggin } 2623a4b0672dSNick Piggin 262409cbfeafSKirill A. Shutemov block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits); 26251da177e4SLinus Torvalds 26261da177e4SLinus Torvalds /* 26271da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 26281da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 26291da177e4SLinus Torvalds * page is fully mapped-to-disk. 26301da177e4SLinus Torvalds */ 2631a4b0672dSNick Piggin for (block_start = 0, block_in_page = 0, bh = head; 263209cbfeafSKirill A. Shutemov block_start < PAGE_SIZE; 2633a4b0672dSNick Piggin block_in_page++, block_start += blocksize, bh = bh->b_this_page) { 26341da177e4SLinus Torvalds int create; 26351da177e4SLinus Torvalds 2636a4b0672dSNick Piggin block_end = block_start + blocksize; 2637a4b0672dSNick Piggin bh->b_state = 0; 26381da177e4SLinus Torvalds create = 1; 26391da177e4SLinus Torvalds if (block_start >= to) 26401da177e4SLinus Torvalds create = 0; 26411da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 2642a4b0672dSNick Piggin bh, create); 26431da177e4SLinus Torvalds if (ret) 26441da177e4SLinus Torvalds goto failed; 2645a4b0672dSNick Piggin if (!buffer_mapped(bh)) 26461da177e4SLinus Torvalds is_mapped_to_disk = 0; 2647a4b0672dSNick Piggin if (buffer_new(bh)) 2648e64855c6SJan Kara clean_bdev_bh_alias(bh); 2649a4b0672dSNick Piggin if (PageUptodate(page)) { 2650a4b0672dSNick Piggin set_buffer_uptodate(bh); 26511da177e4SLinus Torvalds continue; 2652a4b0672dSNick Piggin } 2653a4b0672dSNick Piggin if (buffer_new(bh) || !buffer_mapped(bh)) { 2654eebd2aa3SChristoph Lameter zero_user_segments(page, block_start, from, 2655eebd2aa3SChristoph Lameter to, block_end); 26561da177e4SLinus Torvalds continue; 26571da177e4SLinus Torvalds } 2658a4b0672dSNick Piggin if (buffer_uptodate(bh)) 26591da177e4SLinus Torvalds continue; /* reiserfs does this */ 26601da177e4SLinus Torvalds if (block_start < from || block_end > to) { 2661a4b0672dSNick Piggin lock_buffer(bh); 2662a4b0672dSNick Piggin bh->b_end_io = end_buffer_read_nobh; 26632a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 2664a4b0672dSNick Piggin nr_reads++; 26651da177e4SLinus Torvalds } 26661da177e4SLinus Torvalds } 26671da177e4SLinus Torvalds 26681da177e4SLinus Torvalds if (nr_reads) { 26691da177e4SLinus Torvalds /* 26701da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 26711da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 26721da177e4SLinus Torvalds * for the buffer_head refcounts. 26731da177e4SLinus Torvalds */ 2674a4b0672dSNick Piggin for (bh = head; bh; bh = bh->b_this_page) { 26751da177e4SLinus Torvalds wait_on_buffer(bh); 26761da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 26771da177e4SLinus Torvalds ret = -EIO; 26781da177e4SLinus Torvalds } 26791da177e4SLinus Torvalds if (ret) 26801da177e4SLinus Torvalds goto failed; 26811da177e4SLinus Torvalds } 26821da177e4SLinus Torvalds 26831da177e4SLinus Torvalds if (is_mapped_to_disk) 26841da177e4SLinus Torvalds SetPageMappedToDisk(page); 26851da177e4SLinus Torvalds 268603158cd7SNick Piggin *fsdata = head; /* to be released by nobh_write_end */ 2687a4b0672dSNick Piggin 26881da177e4SLinus Torvalds return 0; 26891da177e4SLinus Torvalds 26901da177e4SLinus Torvalds failed: 269103158cd7SNick Piggin BUG_ON(!ret); 26921da177e4SLinus Torvalds /* 2693a4b0672dSNick Piggin * Error recovery is a bit difficult. We need to zero out blocks that 2694a4b0672dSNick Piggin * were newly allocated, and dirty them to ensure they get written out. 2695a4b0672dSNick Piggin * Buffers need to be attached to the page at this point, otherwise 2696a4b0672dSNick Piggin * the handling of potential IO errors during writeout would be hard 2697a4b0672dSNick Piggin * (could try doing synchronous writeout, but what if that fails too?) 26981da177e4SLinus Torvalds */ 269903158cd7SNick Piggin attach_nobh_buffers(page, head); 270003158cd7SNick Piggin page_zero_new_buffers(page, from, to); 2701a4b0672dSNick Piggin 270203158cd7SNick Piggin out_release: 270303158cd7SNick Piggin unlock_page(page); 270409cbfeafSKirill A. Shutemov put_page(page); 270503158cd7SNick Piggin *pagep = NULL; 2706a4b0672dSNick Piggin 27077bb46a67Snpiggin@suse.de return ret; 27087bb46a67Snpiggin@suse.de } 270903158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_begin); 27101da177e4SLinus Torvalds 271103158cd7SNick Piggin int nobh_write_end(struct file *file, struct address_space *mapping, 271203158cd7SNick Piggin loff_t pos, unsigned len, unsigned copied, 271303158cd7SNick Piggin struct page *page, void *fsdata) 27141da177e4SLinus Torvalds { 27151da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 2716efdc3131SNick Piggin struct buffer_head *head = fsdata; 271703158cd7SNick Piggin struct buffer_head *bh; 27185b41e74aSDmitri Monakhov BUG_ON(fsdata != NULL && page_has_buffers(page)); 27191da177e4SLinus Torvalds 2720d4cf109fSDave Kleikamp if (unlikely(copied < len) && head) 272103158cd7SNick Piggin attach_nobh_buffers(page, head); 2722a4b0672dSNick Piggin if (page_has_buffers(page)) 272303158cd7SNick Piggin return generic_write_end(file, mapping, pos, len, 272403158cd7SNick Piggin copied, page, fsdata); 2725a4b0672dSNick Piggin 272622c8ca78SNick Piggin SetPageUptodate(page); 27271da177e4SLinus Torvalds set_page_dirty(page); 272803158cd7SNick Piggin if (pos+copied > inode->i_size) { 272903158cd7SNick Piggin i_size_write(inode, pos+copied); 27301da177e4SLinus Torvalds mark_inode_dirty(inode); 27311da177e4SLinus Torvalds } 273203158cd7SNick Piggin 273303158cd7SNick Piggin unlock_page(page); 273409cbfeafSKirill A. Shutemov put_page(page); 273503158cd7SNick Piggin 273603158cd7SNick Piggin while (head) { 273703158cd7SNick Piggin bh = head; 273803158cd7SNick Piggin head = head->b_this_page; 273903158cd7SNick Piggin free_buffer_head(bh); 27401da177e4SLinus Torvalds } 274103158cd7SNick Piggin 274203158cd7SNick Piggin return copied; 274303158cd7SNick Piggin } 274403158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_end); 27451da177e4SLinus Torvalds 27461da177e4SLinus Torvalds /* 27471da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 27481da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 27491da177e4SLinus Torvalds * the page. 27501da177e4SLinus Torvalds */ 27511da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 27521da177e4SLinus Torvalds struct writeback_control *wbc) 27531da177e4SLinus Torvalds { 27541da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 27551da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 275609cbfeafSKirill A. Shutemov const pgoff_t end_index = i_size >> PAGE_SHIFT; 27571da177e4SLinus Torvalds unsigned offset; 27581da177e4SLinus Torvalds int ret; 27591da177e4SLinus Torvalds 27601da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 27611da177e4SLinus Torvalds if (page->index < end_index) 27621da177e4SLinus Torvalds goto out; 27631da177e4SLinus Torvalds 27641da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 276509cbfeafSKirill A. Shutemov offset = i_size & (PAGE_SIZE-1); 27661da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 27671da177e4SLinus Torvalds /* 27681da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 27691da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 27701da177e4SLinus Torvalds * freeable here, so the page does not leak. 27711da177e4SLinus Torvalds */ 27721da177e4SLinus Torvalds #if 0 27731da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 27741da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 27751da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 27761da177e4SLinus Torvalds #endif 27771da177e4SLinus Torvalds unlock_page(page); 27781da177e4SLinus Torvalds return 0; /* don't care */ 27791da177e4SLinus Torvalds } 27801da177e4SLinus Torvalds 27811da177e4SLinus Torvalds /* 27821da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 27831da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 27841da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 27851da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 27861da177e4SLinus Torvalds * writes to that region are not written out to the file." 27871da177e4SLinus Torvalds */ 278809cbfeafSKirill A. Shutemov zero_user_segment(page, offset, PAGE_SIZE); 27891da177e4SLinus Torvalds out: 27901da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 27911da177e4SLinus Torvalds if (ret == -EAGAIN) 279235c80d5fSChris Mason ret = __block_write_full_page(inode, page, get_block, wbc, 279335c80d5fSChris Mason end_buffer_async_write); 27941da177e4SLinus Torvalds return ret; 27951da177e4SLinus Torvalds } 27961da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 27971da177e4SLinus Torvalds 279803158cd7SNick Piggin int nobh_truncate_page(struct address_space *mapping, 279903158cd7SNick Piggin loff_t from, get_block_t *get_block) 28001da177e4SLinus Torvalds { 280109cbfeafSKirill A. Shutemov pgoff_t index = from >> PAGE_SHIFT; 280209cbfeafSKirill A. Shutemov unsigned offset = from & (PAGE_SIZE-1); 280303158cd7SNick Piggin unsigned blocksize; 280403158cd7SNick Piggin sector_t iblock; 280503158cd7SNick Piggin unsigned length, pos; 280603158cd7SNick Piggin struct inode *inode = mapping->host; 28071da177e4SLinus Torvalds struct page *page; 280803158cd7SNick Piggin struct buffer_head map_bh; 280903158cd7SNick Piggin int err; 28101da177e4SLinus Torvalds 281193407472SFabian Frederick blocksize = i_blocksize(inode); 281203158cd7SNick Piggin length = offset & (blocksize - 1); 28131da177e4SLinus Torvalds 281403158cd7SNick Piggin /* Block boundary? Nothing to do */ 281503158cd7SNick Piggin if (!length) 281603158cd7SNick Piggin return 0; 281703158cd7SNick Piggin 281803158cd7SNick Piggin length = blocksize - length; 281909cbfeafSKirill A. Shutemov iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); 282003158cd7SNick Piggin 28211da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 282203158cd7SNick Piggin err = -ENOMEM; 28231da177e4SLinus Torvalds if (!page) 28241da177e4SLinus Torvalds goto out; 28251da177e4SLinus Torvalds 282603158cd7SNick Piggin if (page_has_buffers(page)) { 282703158cd7SNick Piggin has_buffers: 282803158cd7SNick Piggin unlock_page(page); 282909cbfeafSKirill A. Shutemov put_page(page); 283003158cd7SNick Piggin return block_truncate_page(mapping, from, get_block); 28311da177e4SLinus Torvalds } 283203158cd7SNick Piggin 283303158cd7SNick Piggin /* Find the buffer that contains "offset" */ 283403158cd7SNick Piggin pos = blocksize; 283503158cd7SNick Piggin while (offset >= pos) { 283603158cd7SNick Piggin iblock++; 283703158cd7SNick Piggin pos += blocksize; 283803158cd7SNick Piggin } 283903158cd7SNick Piggin 2840460bcf57STheodore Ts'o map_bh.b_size = blocksize; 2841460bcf57STheodore Ts'o map_bh.b_state = 0; 284203158cd7SNick Piggin err = get_block(inode, iblock, &map_bh, 0); 284303158cd7SNick Piggin if (err) 284403158cd7SNick Piggin goto unlock; 284503158cd7SNick Piggin /* unmapped? It's a hole - nothing to do */ 284603158cd7SNick Piggin if (!buffer_mapped(&map_bh)) 284703158cd7SNick Piggin goto unlock; 284803158cd7SNick Piggin 284903158cd7SNick Piggin /* Ok, it's mapped. Make sure it's up-to-date */ 285003158cd7SNick Piggin if (!PageUptodate(page)) { 285103158cd7SNick Piggin err = mapping->a_ops->readpage(NULL, page); 285203158cd7SNick Piggin if (err) { 285309cbfeafSKirill A. Shutemov put_page(page); 285403158cd7SNick Piggin goto out; 285503158cd7SNick Piggin } 285603158cd7SNick Piggin lock_page(page); 285703158cd7SNick Piggin if (!PageUptodate(page)) { 285803158cd7SNick Piggin err = -EIO; 285903158cd7SNick Piggin goto unlock; 286003158cd7SNick Piggin } 286103158cd7SNick Piggin if (page_has_buffers(page)) 286203158cd7SNick Piggin goto has_buffers; 286303158cd7SNick Piggin } 2864eebd2aa3SChristoph Lameter zero_user(page, offset, length); 286503158cd7SNick Piggin set_page_dirty(page); 286603158cd7SNick Piggin err = 0; 286703158cd7SNick Piggin 286803158cd7SNick Piggin unlock: 28691da177e4SLinus Torvalds unlock_page(page); 287009cbfeafSKirill A. Shutemov put_page(page); 28711da177e4SLinus Torvalds out: 287203158cd7SNick Piggin return err; 28731da177e4SLinus Torvalds } 28741da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 28751da177e4SLinus Torvalds 28761da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 28771da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 28781da177e4SLinus Torvalds { 287909cbfeafSKirill A. Shutemov pgoff_t index = from >> PAGE_SHIFT; 288009cbfeafSKirill A. Shutemov unsigned offset = from & (PAGE_SIZE-1); 28811da177e4SLinus Torvalds unsigned blocksize; 288254b21a79SAndrew Morton sector_t iblock; 28831da177e4SLinus Torvalds unsigned length, pos; 28841da177e4SLinus Torvalds struct inode *inode = mapping->host; 28851da177e4SLinus Torvalds struct page *page; 28861da177e4SLinus Torvalds struct buffer_head *bh; 28871da177e4SLinus Torvalds int err; 28881da177e4SLinus Torvalds 288993407472SFabian Frederick blocksize = i_blocksize(inode); 28901da177e4SLinus Torvalds length = offset & (blocksize - 1); 28911da177e4SLinus Torvalds 28921da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 28931da177e4SLinus Torvalds if (!length) 28941da177e4SLinus Torvalds return 0; 28951da177e4SLinus Torvalds 28961da177e4SLinus Torvalds length = blocksize - length; 289709cbfeafSKirill A. Shutemov iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); 28981da177e4SLinus Torvalds 28991da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 29001da177e4SLinus Torvalds err = -ENOMEM; 29011da177e4SLinus Torvalds if (!page) 29021da177e4SLinus Torvalds goto out; 29031da177e4SLinus Torvalds 29041da177e4SLinus Torvalds if (!page_has_buffers(page)) 29051da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 29061da177e4SLinus Torvalds 29071da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 29081da177e4SLinus Torvalds bh = page_buffers(page); 29091da177e4SLinus Torvalds pos = blocksize; 29101da177e4SLinus Torvalds while (offset >= pos) { 29111da177e4SLinus Torvalds bh = bh->b_this_page; 29121da177e4SLinus Torvalds iblock++; 29131da177e4SLinus Torvalds pos += blocksize; 29141da177e4SLinus Torvalds } 29151da177e4SLinus Torvalds 29161da177e4SLinus Torvalds err = 0; 29171da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2918b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 29191da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 29201da177e4SLinus Torvalds if (err) 29211da177e4SLinus Torvalds goto unlock; 29221da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 29231da177e4SLinus Torvalds if (!buffer_mapped(bh)) 29241da177e4SLinus Torvalds goto unlock; 29251da177e4SLinus Torvalds } 29261da177e4SLinus Torvalds 29271da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 29281da177e4SLinus Torvalds if (PageUptodate(page)) 29291da177e4SLinus Torvalds set_buffer_uptodate(bh); 29301da177e4SLinus Torvalds 293133a266ddSDavid Chinner if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { 29321da177e4SLinus Torvalds err = -EIO; 2933dfec8a14SMike Christie ll_rw_block(REQ_OP_READ, 0, 1, &bh); 29341da177e4SLinus Torvalds wait_on_buffer(bh); 29351da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 29361da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 29371da177e4SLinus Torvalds goto unlock; 29381da177e4SLinus Torvalds } 29391da177e4SLinus Torvalds 2940eebd2aa3SChristoph Lameter zero_user(page, offset, length); 29411da177e4SLinus Torvalds mark_buffer_dirty(bh); 29421da177e4SLinus Torvalds err = 0; 29431da177e4SLinus Torvalds 29441da177e4SLinus Torvalds unlock: 29451da177e4SLinus Torvalds unlock_page(page); 294609cbfeafSKirill A. Shutemov put_page(page); 29471da177e4SLinus Torvalds out: 29481da177e4SLinus Torvalds return err; 29491da177e4SLinus Torvalds } 29501fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_truncate_page); 29511da177e4SLinus Torvalds 29521da177e4SLinus Torvalds /* 29531da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 29541da177e4SLinus Torvalds */ 29551b938c08SMatthew Wilcox int block_write_full_page(struct page *page, get_block_t *get_block, 29561b938c08SMatthew Wilcox struct writeback_control *wbc) 29571da177e4SLinus Torvalds { 29581da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 29591da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 296009cbfeafSKirill A. Shutemov const pgoff_t end_index = i_size >> PAGE_SHIFT; 29611da177e4SLinus Torvalds unsigned offset; 29621da177e4SLinus Torvalds 29631da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 29641da177e4SLinus Torvalds if (page->index < end_index) 296535c80d5fSChris Mason return __block_write_full_page(inode, page, get_block, wbc, 29661b938c08SMatthew Wilcox end_buffer_async_write); 29671da177e4SLinus Torvalds 29681da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 296909cbfeafSKirill A. Shutemov offset = i_size & (PAGE_SIZE-1); 29701da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 29711da177e4SLinus Torvalds /* 29721da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 29731da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 29741da177e4SLinus Torvalds * freeable here, so the page does not leak. 29751da177e4SLinus Torvalds */ 297609cbfeafSKirill A. Shutemov do_invalidatepage(page, 0, PAGE_SIZE); 29771da177e4SLinus Torvalds unlock_page(page); 29781da177e4SLinus Torvalds return 0; /* don't care */ 29791da177e4SLinus Torvalds } 29801da177e4SLinus Torvalds 29811da177e4SLinus Torvalds /* 29821da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 29832a61aa40SAdam Buchbinder * writepage invocation because it may be mmapped. "A file is mapped 29841da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 29851da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 29861da177e4SLinus Torvalds * writes to that region are not written out to the file." 29871da177e4SLinus Torvalds */ 298809cbfeafSKirill A. Shutemov zero_user_segment(page, offset, PAGE_SIZE); 29891b938c08SMatthew Wilcox return __block_write_full_page(inode, page, get_block, wbc, 299035c80d5fSChris Mason end_buffer_async_write); 299135c80d5fSChris Mason } 29921fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_write_full_page); 299335c80d5fSChris Mason 29941da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 29951da177e4SLinus Torvalds get_block_t *get_block) 29961da177e4SLinus Torvalds { 29971da177e4SLinus Torvalds struct inode *inode = mapping->host; 29982a527d68SAlexander Potapenko struct buffer_head tmp = { 29992a527d68SAlexander Potapenko .b_size = i_blocksize(inode), 30002a527d68SAlexander Potapenko }; 30012a527d68SAlexander Potapenko 30021da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 30031da177e4SLinus Torvalds return tmp.b_blocknr; 30041da177e4SLinus Torvalds } 30051fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_block_bmap); 30061da177e4SLinus Torvalds 30074246a0b6SChristoph Hellwig static void end_bio_bh_io_sync(struct bio *bio) 30081da177e4SLinus Torvalds { 30091da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 30101da177e4SLinus Torvalds 3011b7c44ed9SJens Axboe if (unlikely(bio_flagged(bio, BIO_QUIET))) 301208bafc03SKeith Mannthey set_bit(BH_Quiet, &bh->b_state); 301308bafc03SKeith Mannthey 30144e4cbee9SChristoph Hellwig bh->b_end_io(bh, !bio->bi_status); 30151da177e4SLinus Torvalds bio_put(bio); 30161da177e4SLinus Torvalds } 30171da177e4SLinus Torvalds 301857302e0dSLinus Torvalds /* 301957302e0dSLinus Torvalds * This allows us to do IO even on the odd last sectors 302059d43914SAkinobu Mita * of a device, even if the block size is some multiple 302157302e0dSLinus Torvalds * of the physical sector size. 302257302e0dSLinus Torvalds * 302357302e0dSLinus Torvalds * We'll just truncate the bio to the size of the device, 302457302e0dSLinus Torvalds * and clear the end of the buffer head manually. 302557302e0dSLinus Torvalds * 302657302e0dSLinus Torvalds * Truly out-of-range accesses will turn into actual IO 302757302e0dSLinus Torvalds * errors, this only handles the "we need to be able to 302857302e0dSLinus Torvalds * do IO at the final sector" case. 302957302e0dSLinus Torvalds */ 30302a222ca9SMike Christie void guard_bio_eod(int op, struct bio *bio) 303157302e0dSLinus Torvalds { 303257302e0dSLinus Torvalds sector_t maxsector; 303359d43914SAkinobu Mita struct bio_vec *bvec = &bio->bi_io_vec[bio->bi_vcnt - 1]; 303459d43914SAkinobu Mita unsigned truncated_bytes; 303557302e0dSLinus Torvalds 303674d46992SChristoph Hellwig maxsector = get_capacity(bio->bi_disk); 303757302e0dSLinus Torvalds if (!maxsector) 303857302e0dSLinus Torvalds return; 303957302e0dSLinus Torvalds 304057302e0dSLinus Torvalds /* 304157302e0dSLinus Torvalds * If the *whole* IO is past the end of the device, 304257302e0dSLinus Torvalds * let it through, and the IO layer will turn it into 304357302e0dSLinus Torvalds * an EIO. 304457302e0dSLinus Torvalds */ 30454f024f37SKent Overstreet if (unlikely(bio->bi_iter.bi_sector >= maxsector)) 304657302e0dSLinus Torvalds return; 304757302e0dSLinus Torvalds 30484f024f37SKent Overstreet maxsector -= bio->bi_iter.bi_sector; 304959d43914SAkinobu Mita if (likely((bio->bi_iter.bi_size >> 9) <= maxsector)) 305057302e0dSLinus Torvalds return; 305157302e0dSLinus Torvalds 305259d43914SAkinobu Mita /* Uhhuh. We've got a bio that straddles the device size! */ 305359d43914SAkinobu Mita truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9); 305457302e0dSLinus Torvalds 305557302e0dSLinus Torvalds /* Truncate the bio.. */ 305659d43914SAkinobu Mita bio->bi_iter.bi_size -= truncated_bytes; 305759d43914SAkinobu Mita bvec->bv_len -= truncated_bytes; 305857302e0dSLinus Torvalds 305957302e0dSLinus Torvalds /* ..and clear the end of the buffer for reads */ 30602a222ca9SMike Christie if (op == REQ_OP_READ) { 306159d43914SAkinobu Mita zero_user(bvec->bv_page, bvec->bv_offset + bvec->bv_len, 306259d43914SAkinobu Mita truncated_bytes); 306357302e0dSLinus Torvalds } 306457302e0dSLinus Torvalds } 306557302e0dSLinus Torvalds 30662a222ca9SMike Christie static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, 30678e8f9298SJens Axboe enum rw_hint write_hint, struct writeback_control *wbc) 30681da177e4SLinus Torvalds { 30691da177e4SLinus Torvalds struct bio *bio; 30701da177e4SLinus Torvalds 30711da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 30721da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 30731da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 30748fb0e342SAneesh Kumar K.V BUG_ON(buffer_delay(bh)); 30758fb0e342SAneesh Kumar K.V BUG_ON(buffer_unwritten(bh)); 30761da177e4SLinus Torvalds 307748fd4f93SJens Axboe /* 307848fd4f93SJens Axboe * Only clear out a write error when rewriting 30791da177e4SLinus Torvalds */ 30802a222ca9SMike Christie if (test_set_buffer_req(bh) && (op == REQ_OP_WRITE)) 30811da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 30821da177e4SLinus Torvalds 30831da177e4SLinus Torvalds /* 30841da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 30851da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 30861da177e4SLinus Torvalds */ 30871da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 30881da177e4SLinus Torvalds 30892a814908STejun Heo if (wbc) { 3090b16b1debSTejun Heo wbc_init_bio(wbc, bio); 30912a814908STejun Heo wbc_account_io(wbc, bh->b_page, bh->b_size); 30922a814908STejun Heo } 3093bafc0dbaSTejun Heo 30944f024f37SKent Overstreet bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); 309574d46992SChristoph Hellwig bio_set_dev(bio, bh->b_bdev); 30968e8f9298SJens Axboe bio->bi_write_hint = write_hint; 30971da177e4SLinus Torvalds 30986cf66b4cSKent Overstreet bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh)); 30996cf66b4cSKent Overstreet BUG_ON(bio->bi_iter.bi_size != bh->b_size); 31001da177e4SLinus Torvalds 31011da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 31021da177e4SLinus Torvalds bio->bi_private = bh; 31031da177e4SLinus Torvalds 310457302e0dSLinus Torvalds /* Take care of bh's that straddle the end of the device */ 31052a222ca9SMike Christie guard_bio_eod(op, bio); 310657302e0dSLinus Torvalds 3107877f962cSTheodore Ts'o if (buffer_meta(bh)) 31082a222ca9SMike Christie op_flags |= REQ_META; 3109877f962cSTheodore Ts'o if (buffer_prio(bh)) 31102a222ca9SMike Christie op_flags |= REQ_PRIO; 31112a222ca9SMike Christie bio_set_op_attrs(bio, op, op_flags); 3112877f962cSTheodore Ts'o 31134e49ea4aSMike Christie submit_bio(bio); 3114f6454b04SJulia Lawall return 0; 31151da177e4SLinus Torvalds } 3116bafc0dbaSTejun Heo 31172a222ca9SMike Christie int submit_bh(int op, int op_flags, struct buffer_head *bh) 311871368511SDarrick J. Wong { 31198e8f9298SJens Axboe return submit_bh_wbc(op, op_flags, bh, 0, NULL); 312071368511SDarrick J. Wong } 31211fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(submit_bh); 31221da177e4SLinus Torvalds 31231da177e4SLinus Torvalds /** 31241da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 3125dfec8a14SMike Christie * @op: whether to %READ or %WRITE 3126ef295ecfSChristoph Hellwig * @op_flags: req_flag_bits 31271da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 31281da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 31291da177e4SLinus Torvalds * 3130a7662236SJan Kara * ll_rw_block() takes an array of pointers to &struct buffer_heads, and 313170246286SChristoph Hellwig * requests an I/O operation on them, either a %REQ_OP_READ or a %REQ_OP_WRITE. 313270246286SChristoph Hellwig * @op_flags contains flags modifying the detailed I/O behavior, most notably 313370246286SChristoph Hellwig * %REQ_RAHEAD. 31341da177e4SLinus Torvalds * 31351da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 31369cb569d6SChristoph Hellwig * BH_Lock state bit), any buffer that appears to be clean when doing a write 31379cb569d6SChristoph Hellwig * request, and any buffer that appears to be up-to-date when doing read 31389cb569d6SChristoph Hellwig * request. Further it marks as clean buffers that are processed for 31399cb569d6SChristoph Hellwig * writing (the buffer cache won't assume that they are actually clean 31409cb569d6SChristoph Hellwig * until the buffer gets unlocked). 31411da177e4SLinus Torvalds * 31421da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 3143e227867fSMasanari Iida * the buffer up-to-date (if appropriate), unlocks the buffer and wakes 31441da177e4SLinus Torvalds * any waiters. 31451da177e4SLinus Torvalds * 31461da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 31471da177e4SLinus Torvalds * multiple of the current approved size for the device. 31481da177e4SLinus Torvalds */ 3149dfec8a14SMike Christie void ll_rw_block(int op, int op_flags, int nr, struct buffer_head *bhs[]) 31501da177e4SLinus Torvalds { 31511da177e4SLinus Torvalds int i; 31521da177e4SLinus Torvalds 31531da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 31541da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 31551da177e4SLinus Torvalds 31569cb569d6SChristoph Hellwig if (!trylock_buffer(bh)) 31571da177e4SLinus Torvalds continue; 3158dfec8a14SMike Christie if (op == WRITE) { 31591da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 316076c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 3161e60e5c50SOGAWA Hirofumi get_bh(bh); 3162dfec8a14SMike Christie submit_bh(op, op_flags, bh); 31631da177e4SLinus Torvalds continue; 31641da177e4SLinus Torvalds } 31651da177e4SLinus Torvalds } else { 31661da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 316776c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 3168e60e5c50SOGAWA Hirofumi get_bh(bh); 3169dfec8a14SMike Christie submit_bh(op, op_flags, bh); 31701da177e4SLinus Torvalds continue; 31711da177e4SLinus Torvalds } 31721da177e4SLinus Torvalds } 31731da177e4SLinus Torvalds unlock_buffer(bh); 31741da177e4SLinus Torvalds } 31751da177e4SLinus Torvalds } 31761fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(ll_rw_block); 31771da177e4SLinus Torvalds 31782a222ca9SMike Christie void write_dirty_buffer(struct buffer_head *bh, int op_flags) 31799cb569d6SChristoph Hellwig { 31809cb569d6SChristoph Hellwig lock_buffer(bh); 31819cb569d6SChristoph Hellwig if (!test_clear_buffer_dirty(bh)) { 31829cb569d6SChristoph Hellwig unlock_buffer(bh); 31839cb569d6SChristoph Hellwig return; 31849cb569d6SChristoph Hellwig } 31859cb569d6SChristoph Hellwig bh->b_end_io = end_buffer_write_sync; 31869cb569d6SChristoph Hellwig get_bh(bh); 31872a222ca9SMike Christie submit_bh(REQ_OP_WRITE, op_flags, bh); 31889cb569d6SChristoph Hellwig } 31899cb569d6SChristoph Hellwig EXPORT_SYMBOL(write_dirty_buffer); 31909cb569d6SChristoph Hellwig 31911da177e4SLinus Torvalds /* 31921da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 31931da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 31941da177e4SLinus Torvalds * the buffer_head. 31951da177e4SLinus Torvalds */ 31962a222ca9SMike Christie int __sync_dirty_buffer(struct buffer_head *bh, int op_flags) 31971da177e4SLinus Torvalds { 31981da177e4SLinus Torvalds int ret = 0; 31991da177e4SLinus Torvalds 32001da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 32011da177e4SLinus Torvalds lock_buffer(bh); 32021da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 32031da177e4SLinus Torvalds get_bh(bh); 32041da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 32052a222ca9SMike Christie ret = submit_bh(REQ_OP_WRITE, op_flags, bh); 32061da177e4SLinus Torvalds wait_on_buffer(bh); 32071da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 32081da177e4SLinus Torvalds ret = -EIO; 32091da177e4SLinus Torvalds } else { 32101da177e4SLinus Torvalds unlock_buffer(bh); 32111da177e4SLinus Torvalds } 32121da177e4SLinus Torvalds return ret; 32131da177e4SLinus Torvalds } 321487e99511SChristoph Hellwig EXPORT_SYMBOL(__sync_dirty_buffer); 321587e99511SChristoph Hellwig 321687e99511SChristoph Hellwig int sync_dirty_buffer(struct buffer_head *bh) 321787e99511SChristoph Hellwig { 321870fd7614SChristoph Hellwig return __sync_dirty_buffer(bh, REQ_SYNC); 321987e99511SChristoph Hellwig } 32201fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(sync_dirty_buffer); 32211da177e4SLinus Torvalds 32221da177e4SLinus Torvalds /* 32231da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 32241da177e4SLinus Torvalds * are unused, and releases them if so. 32251da177e4SLinus Torvalds * 32261da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 32271da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 32281da177e4SLinus Torvalds * 32291da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 32301da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 32311da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 32321da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 32331da177e4SLinus Torvalds * filesystem data on the same device. 32341da177e4SLinus Torvalds * 32351da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 32361da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 32371da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 32381da177e4SLinus Torvalds * private_lock. 32391da177e4SLinus Torvalds * 32401da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 32411da177e4SLinus Torvalds */ 32421da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 32431da177e4SLinus Torvalds { 32441da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 32451da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 32461da177e4SLinus Torvalds } 32471da177e4SLinus Torvalds 32481da177e4SLinus Torvalds static int 32491da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 32501da177e4SLinus Torvalds { 32511da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 32521da177e4SLinus Torvalds struct buffer_head *bh; 32531da177e4SLinus Torvalds 32541da177e4SLinus Torvalds bh = head; 32551da177e4SLinus Torvalds do { 32561da177e4SLinus Torvalds if (buffer_busy(bh)) 32571da177e4SLinus Torvalds goto failed; 32581da177e4SLinus Torvalds bh = bh->b_this_page; 32591da177e4SLinus Torvalds } while (bh != head); 32601da177e4SLinus Torvalds 32611da177e4SLinus Torvalds do { 32621da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 32631da177e4SLinus Torvalds 3264535ee2fbSJan Kara if (bh->b_assoc_map) 32651da177e4SLinus Torvalds __remove_assoc_queue(bh); 32661da177e4SLinus Torvalds bh = next; 32671da177e4SLinus Torvalds } while (bh != head); 32681da177e4SLinus Torvalds *buffers_to_free = head; 32691da177e4SLinus Torvalds __clear_page_buffers(page); 32701da177e4SLinus Torvalds return 1; 32711da177e4SLinus Torvalds failed: 32721da177e4SLinus Torvalds return 0; 32731da177e4SLinus Torvalds } 32741da177e4SLinus Torvalds 32751da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 32761da177e4SLinus Torvalds { 32771da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 32781da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 32791da177e4SLinus Torvalds int ret = 0; 32801da177e4SLinus Torvalds 32811da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 3282ecdfc978SLinus Torvalds if (PageWriteback(page)) 32831da177e4SLinus Torvalds return 0; 32841da177e4SLinus Torvalds 32851da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 32861da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 32871da177e4SLinus Torvalds goto out; 32881da177e4SLinus Torvalds } 32891da177e4SLinus Torvalds 32901da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 32911da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 3292ecdfc978SLinus Torvalds 3293ecdfc978SLinus Torvalds /* 3294ecdfc978SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 3295ecdfc978SLinus Torvalds * then we can have clean buffers against a dirty page. We 3296ecdfc978SLinus Torvalds * clean the page here; otherwise the VM will never notice 3297ecdfc978SLinus Torvalds * that the filesystem did any IO at all. 3298ecdfc978SLinus Torvalds * 3299ecdfc978SLinus Torvalds * Also, during truncate, discard_buffer will have marked all 3300ecdfc978SLinus Torvalds * the page's buffers clean. We discover that here and clean 3301ecdfc978SLinus Torvalds * the page also. 330287df7241SNick Piggin * 330387df7241SNick Piggin * private_lock must be held over this entire operation in order 330487df7241SNick Piggin * to synchronise against __set_page_dirty_buffers and prevent the 330587df7241SNick Piggin * dirty bit from being lost. 3306ecdfc978SLinus Torvalds */ 330711f81becSTejun Heo if (ret) 330811f81becSTejun Heo cancel_dirty_page(page); 330987df7241SNick Piggin spin_unlock(&mapping->private_lock); 33101da177e4SLinus Torvalds out: 33111da177e4SLinus Torvalds if (buffers_to_free) { 33121da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 33131da177e4SLinus Torvalds 33141da177e4SLinus Torvalds do { 33151da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 33161da177e4SLinus Torvalds free_buffer_head(bh); 33171da177e4SLinus Torvalds bh = next; 33181da177e4SLinus Torvalds } while (bh != buffers_to_free); 33191da177e4SLinus Torvalds } 33201da177e4SLinus Torvalds return ret; 33211da177e4SLinus Torvalds } 33221da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 33231da177e4SLinus Torvalds 33241da177e4SLinus Torvalds /* 33251da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 33261da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 33271da177e4SLinus Torvalds * 33281da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 33295b0830cbSJens Axboe * The `flush-X' kernel threads fully replace bdflush daemons and this call. 33301da177e4SLinus Torvalds */ 3331bdc480e3SHeiko Carstens SYSCALL_DEFINE2(bdflush, int, func, long, data) 33321da177e4SLinus Torvalds { 33331da177e4SLinus Torvalds static int msg_count; 33341da177e4SLinus Torvalds 33351da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 33361da177e4SLinus Torvalds return -EPERM; 33371da177e4SLinus Torvalds 33381da177e4SLinus Torvalds if (msg_count < 5) { 33391da177e4SLinus Torvalds msg_count++; 33401da177e4SLinus Torvalds printk(KERN_INFO 33411da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 33421da177e4SLinus Torvalds " system call\n", current->comm); 33431da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 33441da177e4SLinus Torvalds } 33451da177e4SLinus Torvalds 33461da177e4SLinus Torvalds if (func == 1) 33471da177e4SLinus Torvalds do_exit(0); 33481da177e4SLinus Torvalds return 0; 33491da177e4SLinus Torvalds } 33501da177e4SLinus Torvalds 33511da177e4SLinus Torvalds /* 33521da177e4SLinus Torvalds * Buffer-head allocation 33531da177e4SLinus Torvalds */ 3354a0a9b043SShai Fultheim static struct kmem_cache *bh_cachep __read_mostly; 33551da177e4SLinus Torvalds 33561da177e4SLinus Torvalds /* 33571da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 33581da177e4SLinus Torvalds * stripping them in writeback. 33591da177e4SLinus Torvalds */ 336043be594aSZhang Yanfei static unsigned long max_buffer_heads; 33611da177e4SLinus Torvalds 33621da177e4SLinus Torvalds int buffer_heads_over_limit; 33631da177e4SLinus Torvalds 33641da177e4SLinus Torvalds struct bh_accounting { 33651da177e4SLinus Torvalds int nr; /* Number of live bh's */ 33661da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 33671da177e4SLinus Torvalds }; 33681da177e4SLinus Torvalds 33691da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 33701da177e4SLinus Torvalds 33711da177e4SLinus Torvalds static void recalc_bh_state(void) 33721da177e4SLinus Torvalds { 33731da177e4SLinus Torvalds int i; 33741da177e4SLinus Torvalds int tot = 0; 33751da177e4SLinus Torvalds 3376ee1be862SChristoph Lameter if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) 33771da177e4SLinus Torvalds return; 3378c7b92516SChristoph Lameter __this_cpu_write(bh_accounting.ratelimit, 0); 33798a143426SEric Dumazet for_each_online_cpu(i) 33801da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 33811da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 33821da177e4SLinus Torvalds } 33831da177e4SLinus Torvalds 3384dd0fc66fSAl Viro struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) 33851da177e4SLinus Torvalds { 3386019b4d12SRichard Kennedy struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); 33871da177e4SLinus Torvalds if (ret) { 3388a35afb83SChristoph Lameter INIT_LIST_HEAD(&ret->b_assoc_buffers); 3389c7b92516SChristoph Lameter preempt_disable(); 3390c7b92516SChristoph Lameter __this_cpu_inc(bh_accounting.nr); 33911da177e4SLinus Torvalds recalc_bh_state(); 3392c7b92516SChristoph Lameter preempt_enable(); 33931da177e4SLinus Torvalds } 33941da177e4SLinus Torvalds return ret; 33951da177e4SLinus Torvalds } 33961da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 33971da177e4SLinus Torvalds 33981da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 33991da177e4SLinus Torvalds { 34001da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 34011da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 3402c7b92516SChristoph Lameter preempt_disable(); 3403c7b92516SChristoph Lameter __this_cpu_dec(bh_accounting.nr); 34041da177e4SLinus Torvalds recalc_bh_state(); 3405c7b92516SChristoph Lameter preempt_enable(); 34061da177e4SLinus Torvalds } 34071da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 34081da177e4SLinus Torvalds 3409fc4d24c9SSebastian Andrzej Siewior static int buffer_exit_cpu_dead(unsigned int cpu) 34101da177e4SLinus Torvalds { 34111da177e4SLinus Torvalds int i; 34121da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 34131da177e4SLinus Torvalds 34141da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 34151da177e4SLinus Torvalds brelse(b->bhs[i]); 34161da177e4SLinus Torvalds b->bhs[i] = NULL; 34171da177e4SLinus Torvalds } 3418c7b92516SChristoph Lameter this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); 34198a143426SEric Dumazet per_cpu(bh_accounting, cpu).nr = 0; 3420fc4d24c9SSebastian Andrzej Siewior return 0; 34211da177e4SLinus Torvalds } 34221da177e4SLinus Torvalds 3423389d1b08SAneesh Kumar K.V /** 3424a6b91919SRandy Dunlap * bh_uptodate_or_lock - Test whether the buffer is uptodate 3425389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3426389d1b08SAneesh Kumar K.V * 3427389d1b08SAneesh Kumar K.V * Return true if the buffer is up-to-date and false, 3428389d1b08SAneesh Kumar K.V * with the buffer locked, if not. 3429389d1b08SAneesh Kumar K.V */ 3430389d1b08SAneesh Kumar K.V int bh_uptodate_or_lock(struct buffer_head *bh) 3431389d1b08SAneesh Kumar K.V { 3432389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) { 3433389d1b08SAneesh Kumar K.V lock_buffer(bh); 3434389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) 3435389d1b08SAneesh Kumar K.V return 0; 3436389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3437389d1b08SAneesh Kumar K.V } 3438389d1b08SAneesh Kumar K.V return 1; 3439389d1b08SAneesh Kumar K.V } 3440389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_uptodate_or_lock); 3441389d1b08SAneesh Kumar K.V 3442389d1b08SAneesh Kumar K.V /** 3443a6b91919SRandy Dunlap * bh_submit_read - Submit a locked buffer for reading 3444389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3445389d1b08SAneesh Kumar K.V * 3446389d1b08SAneesh Kumar K.V * Returns zero on success and -EIO on error. 3447389d1b08SAneesh Kumar K.V */ 3448389d1b08SAneesh Kumar K.V int bh_submit_read(struct buffer_head *bh) 3449389d1b08SAneesh Kumar K.V { 3450389d1b08SAneesh Kumar K.V BUG_ON(!buffer_locked(bh)); 3451389d1b08SAneesh Kumar K.V 3452389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) { 3453389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3454389d1b08SAneesh Kumar K.V return 0; 3455389d1b08SAneesh Kumar K.V } 3456389d1b08SAneesh Kumar K.V 3457389d1b08SAneesh Kumar K.V get_bh(bh); 3458389d1b08SAneesh Kumar K.V bh->b_end_io = end_buffer_read_sync; 34592a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 3460389d1b08SAneesh Kumar K.V wait_on_buffer(bh); 3461389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) 3462389d1b08SAneesh Kumar K.V return 0; 3463389d1b08SAneesh Kumar K.V return -EIO; 3464389d1b08SAneesh Kumar K.V } 3465389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_submit_read); 3466389d1b08SAneesh Kumar K.V 3467334fd34dSAndreas Gruenbacher /* 3468334fd34dSAndreas Gruenbacher * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff. 3469334fd34dSAndreas Gruenbacher * 3470334fd34dSAndreas Gruenbacher * Returns the offset within the file on success, and -ENOENT otherwise. 3471334fd34dSAndreas Gruenbacher */ 3472334fd34dSAndreas Gruenbacher static loff_t 3473334fd34dSAndreas Gruenbacher page_seek_hole_data(struct page *page, loff_t lastoff, int whence) 3474334fd34dSAndreas Gruenbacher { 3475334fd34dSAndreas Gruenbacher loff_t offset = page_offset(page); 3476334fd34dSAndreas Gruenbacher struct buffer_head *bh, *head; 3477334fd34dSAndreas Gruenbacher bool seek_data = whence == SEEK_DATA; 3478334fd34dSAndreas Gruenbacher 3479334fd34dSAndreas Gruenbacher if (lastoff < offset) 3480334fd34dSAndreas Gruenbacher lastoff = offset; 3481334fd34dSAndreas Gruenbacher 3482334fd34dSAndreas Gruenbacher bh = head = page_buffers(page); 3483334fd34dSAndreas Gruenbacher do { 3484334fd34dSAndreas Gruenbacher offset += bh->b_size; 3485334fd34dSAndreas Gruenbacher if (lastoff >= offset) 3486334fd34dSAndreas Gruenbacher continue; 3487334fd34dSAndreas Gruenbacher 3488334fd34dSAndreas Gruenbacher /* 3489334fd34dSAndreas Gruenbacher * Unwritten extents that have data in the page cache covering 3490334fd34dSAndreas Gruenbacher * them can be identified by the BH_Unwritten state flag. 3491334fd34dSAndreas Gruenbacher * Pages with multiple buffers might have a mix of holes, data 3492334fd34dSAndreas Gruenbacher * and unwritten extents - any buffer with valid data in it 3493334fd34dSAndreas Gruenbacher * should have BH_Uptodate flag set on it. 3494334fd34dSAndreas Gruenbacher */ 3495334fd34dSAndreas Gruenbacher 3496334fd34dSAndreas Gruenbacher if ((buffer_unwritten(bh) || buffer_uptodate(bh)) == seek_data) 3497334fd34dSAndreas Gruenbacher return lastoff; 3498334fd34dSAndreas Gruenbacher 3499334fd34dSAndreas Gruenbacher lastoff = offset; 3500334fd34dSAndreas Gruenbacher } while ((bh = bh->b_this_page) != head); 3501334fd34dSAndreas Gruenbacher return -ENOENT; 3502334fd34dSAndreas Gruenbacher } 3503334fd34dSAndreas Gruenbacher 3504334fd34dSAndreas Gruenbacher /* 3505334fd34dSAndreas Gruenbacher * Seek for SEEK_DATA / SEEK_HOLE in the page cache. 3506334fd34dSAndreas Gruenbacher * 3507334fd34dSAndreas Gruenbacher * Within unwritten extents, the page cache determines which parts are holes 3508334fd34dSAndreas Gruenbacher * and which are data: unwritten and uptodate buffer heads count as data; 3509334fd34dSAndreas Gruenbacher * everything else counts as a hole. 3510334fd34dSAndreas Gruenbacher * 3511334fd34dSAndreas Gruenbacher * Returns the resulting offset on successs, and -ENOENT otherwise. 3512334fd34dSAndreas Gruenbacher */ 3513334fd34dSAndreas Gruenbacher loff_t 3514334fd34dSAndreas Gruenbacher page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length, 3515334fd34dSAndreas Gruenbacher int whence) 3516334fd34dSAndreas Gruenbacher { 3517334fd34dSAndreas Gruenbacher pgoff_t index = offset >> PAGE_SHIFT; 3518334fd34dSAndreas Gruenbacher pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE); 3519334fd34dSAndreas Gruenbacher loff_t lastoff = offset; 3520334fd34dSAndreas Gruenbacher struct pagevec pvec; 3521334fd34dSAndreas Gruenbacher 3522334fd34dSAndreas Gruenbacher if (length <= 0) 3523334fd34dSAndreas Gruenbacher return -ENOENT; 3524334fd34dSAndreas Gruenbacher 3525334fd34dSAndreas Gruenbacher pagevec_init(&pvec, 0); 3526334fd34dSAndreas Gruenbacher 3527334fd34dSAndreas Gruenbacher do { 35288338141fSJan Kara unsigned nr_pages, i; 3529334fd34dSAndreas Gruenbacher 35308338141fSJan Kara nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index, 3531397162ffSJan Kara end - 1); 3532334fd34dSAndreas Gruenbacher if (nr_pages == 0) 3533334fd34dSAndreas Gruenbacher break; 3534334fd34dSAndreas Gruenbacher 3535334fd34dSAndreas Gruenbacher for (i = 0; i < nr_pages; i++) { 3536334fd34dSAndreas Gruenbacher struct page *page = pvec.pages[i]; 3537334fd34dSAndreas Gruenbacher 3538334fd34dSAndreas Gruenbacher /* 3539334fd34dSAndreas Gruenbacher * At this point, the page may be truncated or 3540334fd34dSAndreas Gruenbacher * invalidated (changing page->mapping to NULL), or 3541334fd34dSAndreas Gruenbacher * even swizzled back from swapper_space to tmpfs file 3542334fd34dSAndreas Gruenbacher * mapping. However, page->index will not change 3543334fd34dSAndreas Gruenbacher * because we have a reference on the page. 3544334fd34dSAndreas Gruenbacher * 3545334fd34dSAndreas Gruenbacher * If current page offset is beyond where we've ended, 3546334fd34dSAndreas Gruenbacher * we've found a hole. 3547334fd34dSAndreas Gruenbacher */ 3548334fd34dSAndreas Gruenbacher if (whence == SEEK_HOLE && 3549334fd34dSAndreas Gruenbacher lastoff < page_offset(page)) 3550334fd34dSAndreas Gruenbacher goto check_range; 3551334fd34dSAndreas Gruenbacher 3552334fd34dSAndreas Gruenbacher lock_page(page); 3553334fd34dSAndreas Gruenbacher if (likely(page->mapping == inode->i_mapping) && 3554334fd34dSAndreas Gruenbacher page_has_buffers(page)) { 3555334fd34dSAndreas Gruenbacher lastoff = page_seek_hole_data(page, lastoff, whence); 3556334fd34dSAndreas Gruenbacher if (lastoff >= 0) { 3557334fd34dSAndreas Gruenbacher unlock_page(page); 3558334fd34dSAndreas Gruenbacher goto check_range; 3559334fd34dSAndreas Gruenbacher } 3560334fd34dSAndreas Gruenbacher } 3561334fd34dSAndreas Gruenbacher unlock_page(page); 3562334fd34dSAndreas Gruenbacher lastoff = page_offset(page) + PAGE_SIZE; 3563334fd34dSAndreas Gruenbacher } 3564334fd34dSAndreas Gruenbacher pagevec_release(&pvec); 3565334fd34dSAndreas Gruenbacher } while (index < end); 3566334fd34dSAndreas Gruenbacher 3567334fd34dSAndreas Gruenbacher /* When no page at lastoff and we are not done, we found a hole. */ 3568334fd34dSAndreas Gruenbacher if (whence != SEEK_HOLE) 3569334fd34dSAndreas Gruenbacher goto not_found; 3570334fd34dSAndreas Gruenbacher 3571334fd34dSAndreas Gruenbacher check_range: 3572334fd34dSAndreas Gruenbacher if (lastoff < offset + length) 3573334fd34dSAndreas Gruenbacher goto out; 3574334fd34dSAndreas Gruenbacher not_found: 3575334fd34dSAndreas Gruenbacher lastoff = -ENOENT; 3576334fd34dSAndreas Gruenbacher out: 3577334fd34dSAndreas Gruenbacher pagevec_release(&pvec); 3578334fd34dSAndreas Gruenbacher return lastoff; 3579334fd34dSAndreas Gruenbacher } 3580334fd34dSAndreas Gruenbacher 35811da177e4SLinus Torvalds void __init buffer_init(void) 35821da177e4SLinus Torvalds { 358343be594aSZhang Yanfei unsigned long nrpages; 3584fc4d24c9SSebastian Andrzej Siewior int ret; 35851da177e4SLinus Torvalds 3586b98938c3SChristoph Lameter bh_cachep = kmem_cache_create("buffer_head", 3587b98938c3SChristoph Lameter sizeof(struct buffer_head), 0, 3588b98938c3SChristoph Lameter (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| 3589b98938c3SChristoph Lameter SLAB_MEM_SPREAD), 3590019b4d12SRichard Kennedy NULL); 35911da177e4SLinus Torvalds 35921da177e4SLinus Torvalds /* 35931da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 35941da177e4SLinus Torvalds */ 35951da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 35961da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 3597fc4d24c9SSebastian Andrzej Siewior ret = cpuhp_setup_state_nocalls(CPUHP_FS_BUFF_DEAD, "fs/buffer:dead", 3598fc4d24c9SSebastian Andrzej Siewior NULL, buffer_exit_cpu_dead); 3599fc4d24c9SSebastian Andrzej Siewior WARN_ON(ret < 0); 36001da177e4SLinus Torvalds } 3601