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> 221da177e4SLinus Torvalds #include <linux/syscalls.h> 231da177e4SLinus Torvalds #include <linux/fs.h> 241da177e4SLinus Torvalds #include <linux/mm.h> 251da177e4SLinus Torvalds #include <linux/percpu.h> 261da177e4SLinus Torvalds #include <linux/slab.h> 2716f7e0feSRandy Dunlap #include <linux/capability.h> 281da177e4SLinus Torvalds #include <linux/blkdev.h> 291da177e4SLinus Torvalds #include <linux/file.h> 301da177e4SLinus Torvalds #include <linux/quotaops.h> 311da177e4SLinus Torvalds #include <linux/highmem.h> 32630d9c47SPaul Gortmaker #include <linux/export.h> 33bafc0dbaSTejun Heo #include <linux/backing-dev.h> 341da177e4SLinus Torvalds #include <linux/writeback.h> 351da177e4SLinus Torvalds #include <linux/hash.h> 361da177e4SLinus Torvalds #include <linux/suspend.h> 371da177e4SLinus Torvalds #include <linux/buffer_head.h> 3855e829afSAndrew Morton #include <linux/task_io_accounting_ops.h> 391da177e4SLinus Torvalds #include <linux/bio.h> 401da177e4SLinus Torvalds #include <linux/notifier.h> 411da177e4SLinus Torvalds #include <linux/cpu.h> 421da177e4SLinus Torvalds #include <linux/bitops.h> 431da177e4SLinus Torvalds #include <linux/mpage.h> 44fb1c8f93SIngo Molnar #include <linux/bit_spinlock.h> 455305cb83STejun Heo #include <trace/events/block.h> 461da177e4SLinus Torvalds 471da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); 48b16b1debSTejun Heo static int submit_bh_wbc(int rw, struct buffer_head *bh, 49bafc0dbaSTejun Heo unsigned long bio_flags, 50b16b1debSTejun Heo struct writeback_control *wbc); 511da177e4SLinus Torvalds 521da177e4SLinus Torvalds #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) 531da177e4SLinus Torvalds 54a3f3c29cSYan Hong void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) 551da177e4SLinus Torvalds { 561da177e4SLinus Torvalds bh->b_end_io = handler; 571da177e4SLinus Torvalds bh->b_private = private; 581da177e4SLinus Torvalds } 591fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(init_buffer); 601da177e4SLinus Torvalds 61f0059afdSTejun Heo inline void touch_buffer(struct buffer_head *bh) 62f0059afdSTejun Heo { 635305cb83STejun Heo trace_block_touch_buffer(bh); 64f0059afdSTejun Heo mark_page_accessed(bh->b_page); 65f0059afdSTejun Heo } 66f0059afdSTejun Heo EXPORT_SYMBOL(touch_buffer); 67f0059afdSTejun Heo 68fc9b52cdSHarvey Harrison void __lock_buffer(struct buffer_head *bh) 691da177e4SLinus Torvalds { 7074316201SNeilBrown wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 711da177e4SLinus Torvalds } 721da177e4SLinus Torvalds EXPORT_SYMBOL(__lock_buffer); 731da177e4SLinus Torvalds 74fc9b52cdSHarvey Harrison void unlock_buffer(struct buffer_head *bh) 751da177e4SLinus Torvalds { 7651b07fc3SNick Piggin clear_bit_unlock(BH_Lock, &bh->b_state); 774e857c58SPeter Zijlstra smp_mb__after_atomic(); 781da177e4SLinus Torvalds wake_up_bit(&bh->b_state, BH_Lock); 791da177e4SLinus Torvalds } 801fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(unlock_buffer); 811da177e4SLinus Torvalds 821da177e4SLinus Torvalds /* 83b4597226SMel Gorman * Returns if the page has dirty or writeback buffers. If all the buffers 84b4597226SMel Gorman * are unlocked and clean then the PageDirty information is stale. If 85b4597226SMel Gorman * any of the pages are locked, it is assumed they are locked for IO. 86b4597226SMel Gorman */ 87b4597226SMel Gorman void buffer_check_dirty_writeback(struct page *page, 88b4597226SMel Gorman bool *dirty, bool *writeback) 89b4597226SMel Gorman { 90b4597226SMel Gorman struct buffer_head *head, *bh; 91b4597226SMel Gorman *dirty = false; 92b4597226SMel Gorman *writeback = false; 93b4597226SMel Gorman 94b4597226SMel Gorman BUG_ON(!PageLocked(page)); 95b4597226SMel Gorman 96b4597226SMel Gorman if (!page_has_buffers(page)) 97b4597226SMel Gorman return; 98b4597226SMel Gorman 99b4597226SMel Gorman if (PageWriteback(page)) 100b4597226SMel Gorman *writeback = true; 101b4597226SMel Gorman 102b4597226SMel Gorman head = page_buffers(page); 103b4597226SMel Gorman bh = head; 104b4597226SMel Gorman do { 105b4597226SMel Gorman if (buffer_locked(bh)) 106b4597226SMel Gorman *writeback = true; 107b4597226SMel Gorman 108b4597226SMel Gorman if (buffer_dirty(bh)) 109b4597226SMel Gorman *dirty = true; 110b4597226SMel Gorman 111b4597226SMel Gorman bh = bh->b_this_page; 112b4597226SMel Gorman } while (bh != head); 113b4597226SMel Gorman } 114b4597226SMel Gorman EXPORT_SYMBOL(buffer_check_dirty_writeback); 115b4597226SMel Gorman 116b4597226SMel Gorman /* 1171da177e4SLinus Torvalds * Block until a buffer comes unlocked. This doesn't stop it 1181da177e4SLinus Torvalds * from becoming locked again - you have to lock it yourself 1191da177e4SLinus Torvalds * if you want to preserve its state. 1201da177e4SLinus Torvalds */ 1211da177e4SLinus Torvalds void __wait_on_buffer(struct buffer_head * bh) 1221da177e4SLinus Torvalds { 12374316201SNeilBrown wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 1241da177e4SLinus Torvalds } 1251fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__wait_on_buffer); 1261da177e4SLinus Torvalds 1271da177e4SLinus Torvalds static void 1281da177e4SLinus Torvalds __clear_page_buffers(struct page *page) 1291da177e4SLinus Torvalds { 1301da177e4SLinus Torvalds ClearPagePrivate(page); 1314c21e2f2SHugh Dickins set_page_private(page, 0); 13209cbfeafSKirill A. Shutemov put_page(page); 1331da177e4SLinus Torvalds } 1341da177e4SLinus Torvalds 135b744c2acSRobert Elliott static void buffer_io_error(struct buffer_head *bh, char *msg) 1361da177e4SLinus Torvalds { 137432f16e6SRobert Elliott if (!test_bit(BH_Quiet, &bh->b_state)) 138432f16e6SRobert Elliott printk_ratelimited(KERN_ERR 139a1c6f057SDmitry Monakhov "Buffer I/O error on dev %pg, logical block %llu%s\n", 140a1c6f057SDmitry Monakhov bh->b_bdev, (unsigned long long)bh->b_blocknr, msg); 1411da177e4SLinus Torvalds } 1421da177e4SLinus Torvalds 1431da177e4SLinus Torvalds /* 14468671f35SDmitry Monakhov * End-of-IO handler helper function which does not touch the bh after 14568671f35SDmitry Monakhov * unlocking it. 14668671f35SDmitry Monakhov * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but 14768671f35SDmitry Monakhov * a race there is benign: unlock_buffer() only use the bh's address for 14868671f35SDmitry Monakhov * hashing after unlocking the buffer, so it doesn't actually touch the bh 14968671f35SDmitry Monakhov * itself. 1501da177e4SLinus Torvalds */ 15168671f35SDmitry Monakhov static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) 1521da177e4SLinus Torvalds { 1531da177e4SLinus Torvalds if (uptodate) { 1541da177e4SLinus Torvalds set_buffer_uptodate(bh); 1551da177e4SLinus Torvalds } else { 1561da177e4SLinus Torvalds /* This happens, due to failed READA attempts. */ 1571da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds unlock_buffer(bh); 16068671f35SDmitry Monakhov } 16168671f35SDmitry Monakhov 16268671f35SDmitry Monakhov /* 16368671f35SDmitry Monakhov * Default synchronous end-of-IO handler.. Just mark it up-to-date and 16468671f35SDmitry Monakhov * unlock the buffer. This is what ll_rw_block uses too. 16568671f35SDmitry Monakhov */ 16668671f35SDmitry Monakhov void end_buffer_read_sync(struct buffer_head *bh, int uptodate) 16768671f35SDmitry Monakhov { 16868671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 1691da177e4SLinus Torvalds put_bh(bh); 1701da177e4SLinus Torvalds } 1711fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_read_sync); 1721da177e4SLinus Torvalds 1731da177e4SLinus Torvalds void end_buffer_write_sync(struct buffer_head *bh, int uptodate) 1741da177e4SLinus Torvalds { 1751da177e4SLinus Torvalds if (uptodate) { 1761da177e4SLinus Torvalds set_buffer_uptodate(bh); 1771da177e4SLinus Torvalds } else { 178b744c2acSRobert Elliott buffer_io_error(bh, ", lost sync page write"); 1791da177e4SLinus Torvalds set_buffer_write_io_error(bh); 1801da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1811da177e4SLinus Torvalds } 1821da177e4SLinus Torvalds unlock_buffer(bh); 1831da177e4SLinus Torvalds put_bh(bh); 1841da177e4SLinus Torvalds } 1851fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_write_sync); 1861da177e4SLinus Torvalds 1871da177e4SLinus Torvalds /* 1881da177e4SLinus Torvalds * Various filesystems appear to want __find_get_block to be non-blocking. 1891da177e4SLinus Torvalds * But it's the page lock which protects the buffers. To get around this, 1901da177e4SLinus Torvalds * we get exclusion from try_to_free_buffers with the blockdev mapping's 1911da177e4SLinus Torvalds * private_lock. 1921da177e4SLinus Torvalds * 1931da177e4SLinus Torvalds * Hack idea: for the blockdev mapping, i_bufferlist_lock contention 1941da177e4SLinus Torvalds * may be quite high. This code could TryLock the page, and if that 1951da177e4SLinus Torvalds * succeeds, there is no need to take private_lock. (But if 1961da177e4SLinus Torvalds * private_lock is contended then so is mapping->tree_lock). 1971da177e4SLinus Torvalds */ 1981da177e4SLinus Torvalds static struct buffer_head * 199385fd4c5SCoywolf Qi Hunt __find_get_block_slow(struct block_device *bdev, sector_t block) 2001da177e4SLinus Torvalds { 2011da177e4SLinus Torvalds struct inode *bd_inode = bdev->bd_inode; 2021da177e4SLinus Torvalds struct address_space *bd_mapping = bd_inode->i_mapping; 2031da177e4SLinus Torvalds struct buffer_head *ret = NULL; 2041da177e4SLinus Torvalds pgoff_t index; 2051da177e4SLinus Torvalds struct buffer_head *bh; 2061da177e4SLinus Torvalds struct buffer_head *head; 2071da177e4SLinus Torvalds struct page *page; 2081da177e4SLinus Torvalds int all_mapped = 1; 2091da177e4SLinus Torvalds 21009cbfeafSKirill A. Shutemov index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); 2112457aec6SMel Gorman page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED); 2121da177e4SLinus Torvalds if (!page) 2131da177e4SLinus Torvalds goto out; 2141da177e4SLinus Torvalds 2151da177e4SLinus Torvalds spin_lock(&bd_mapping->private_lock); 2161da177e4SLinus Torvalds if (!page_has_buffers(page)) 2171da177e4SLinus Torvalds goto out_unlock; 2181da177e4SLinus Torvalds head = page_buffers(page); 2191da177e4SLinus Torvalds bh = head; 2201da177e4SLinus Torvalds do { 22197f76d3dSNikanth Karthikesan if (!buffer_mapped(bh)) 22297f76d3dSNikanth Karthikesan all_mapped = 0; 22397f76d3dSNikanth Karthikesan else if (bh->b_blocknr == block) { 2241da177e4SLinus Torvalds ret = bh; 2251da177e4SLinus Torvalds get_bh(bh); 2261da177e4SLinus Torvalds goto out_unlock; 2271da177e4SLinus Torvalds } 2281da177e4SLinus Torvalds bh = bh->b_this_page; 2291da177e4SLinus Torvalds } while (bh != head); 2301da177e4SLinus Torvalds 2311da177e4SLinus Torvalds /* we might be here because some of the buffers on this page are 2321da177e4SLinus Torvalds * not mapped. This is due to various races between 2331da177e4SLinus Torvalds * file io on the block device and getblk. It gets dealt with 2341da177e4SLinus Torvalds * elsewhere, don't buffer_error if we had some unmapped buffers 2351da177e4SLinus Torvalds */ 2361da177e4SLinus Torvalds if (all_mapped) { 2371da177e4SLinus Torvalds printk("__find_get_block_slow() failed. " 2381da177e4SLinus Torvalds "block=%llu, b_blocknr=%llu\n", 239205f87f6SBadari Pulavarty (unsigned long long)block, 240205f87f6SBadari Pulavarty (unsigned long long)bh->b_blocknr); 241205f87f6SBadari Pulavarty printk("b_state=0x%08lx, b_size=%zu\n", 242205f87f6SBadari Pulavarty bh->b_state, bh->b_size); 243a1c6f057SDmitry Monakhov printk("device %pg blocksize: %d\n", bdev, 24472a2ebd8STao Ma 1 << bd_inode->i_blkbits); 2451da177e4SLinus Torvalds } 2461da177e4SLinus Torvalds out_unlock: 2471da177e4SLinus Torvalds spin_unlock(&bd_mapping->private_lock); 24809cbfeafSKirill A. Shutemov put_page(page); 2491da177e4SLinus Torvalds out: 2501da177e4SLinus Torvalds return ret; 2511da177e4SLinus Torvalds } 2521da177e4SLinus Torvalds 2531da177e4SLinus Torvalds /* 2545b0830cbSJens Axboe * Kick the writeback threads then try to free up some ZONE_NORMAL memory. 2551da177e4SLinus Torvalds */ 2561da177e4SLinus Torvalds static void free_more_memory(void) 2571da177e4SLinus Torvalds { 258c33d6c06SMel Gorman struct zoneref *z; 2590e88460dSMel Gorman int nid; 2601da177e4SLinus Torvalds 2610e175a18SCurt Wohlgemuth wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM); 2621da177e4SLinus Torvalds yield(); 2631da177e4SLinus Torvalds 2640e88460dSMel Gorman for_each_online_node(nid) { 265c33d6c06SMel Gorman 266c33d6c06SMel Gorman z = first_zones_zonelist(node_zonelist(nid, GFP_NOFS), 267c33d6c06SMel Gorman gfp_zone(GFP_NOFS), NULL); 268c33d6c06SMel Gorman if (z->zone) 26954a6eb5cSMel Gorman try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0, 270327c0e96SKAMEZAWA Hiroyuki GFP_NOFS, NULL); 2711da177e4SLinus Torvalds } 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds 2741da177e4SLinus Torvalds /* 2751da177e4SLinus Torvalds * I/O completion handler for block_read_full_page() - pages 2761da177e4SLinus Torvalds * which come unlocked at the end of I/O. 2771da177e4SLinus Torvalds */ 2781da177e4SLinus Torvalds static void end_buffer_async_read(struct buffer_head *bh, int uptodate) 2791da177e4SLinus Torvalds { 2801da177e4SLinus Torvalds unsigned long flags; 281a3972203SNick Piggin struct buffer_head *first; 2821da177e4SLinus Torvalds struct buffer_head *tmp; 2831da177e4SLinus Torvalds struct page *page; 2841da177e4SLinus Torvalds int page_uptodate = 1; 2851da177e4SLinus Torvalds 2861da177e4SLinus Torvalds BUG_ON(!buffer_async_read(bh)); 2871da177e4SLinus Torvalds 2881da177e4SLinus Torvalds page = bh->b_page; 2891da177e4SLinus Torvalds if (uptodate) { 2901da177e4SLinus Torvalds set_buffer_uptodate(bh); 2911da177e4SLinus Torvalds } else { 2921da177e4SLinus Torvalds clear_buffer_uptodate(bh); 293b744c2acSRobert Elliott buffer_io_error(bh, ", async page read"); 2941da177e4SLinus Torvalds SetPageError(page); 2951da177e4SLinus Torvalds } 2961da177e4SLinus Torvalds 2971da177e4SLinus Torvalds /* 2981da177e4SLinus Torvalds * Be _very_ careful from here on. Bad things can happen if 2991da177e4SLinus Torvalds * two buffer heads end IO at almost the same time and both 3001da177e4SLinus Torvalds * decide that the page is now completely done. 3011da177e4SLinus Torvalds */ 302a3972203SNick Piggin first = page_buffers(page); 303a3972203SNick Piggin local_irq_save(flags); 304a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 3051da177e4SLinus Torvalds clear_buffer_async_read(bh); 3061da177e4SLinus Torvalds unlock_buffer(bh); 3071da177e4SLinus Torvalds tmp = bh; 3081da177e4SLinus Torvalds do { 3091da177e4SLinus Torvalds if (!buffer_uptodate(tmp)) 3101da177e4SLinus Torvalds page_uptodate = 0; 3111da177e4SLinus Torvalds if (buffer_async_read(tmp)) { 3121da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3131da177e4SLinus Torvalds goto still_busy; 3141da177e4SLinus Torvalds } 3151da177e4SLinus Torvalds tmp = tmp->b_this_page; 3161da177e4SLinus Torvalds } while (tmp != bh); 317a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 318a3972203SNick Piggin local_irq_restore(flags); 3191da177e4SLinus Torvalds 3201da177e4SLinus Torvalds /* 3211da177e4SLinus Torvalds * If none of the buffers had errors and they are all 3221da177e4SLinus Torvalds * uptodate then we can set the page uptodate. 3231da177e4SLinus Torvalds */ 3241da177e4SLinus Torvalds if (page_uptodate && !PageError(page)) 3251da177e4SLinus Torvalds SetPageUptodate(page); 3261da177e4SLinus Torvalds unlock_page(page); 3271da177e4SLinus Torvalds return; 3281da177e4SLinus Torvalds 3291da177e4SLinus Torvalds still_busy: 330a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 331a3972203SNick Piggin local_irq_restore(flags); 3321da177e4SLinus Torvalds return; 3331da177e4SLinus Torvalds } 3341da177e4SLinus Torvalds 3351da177e4SLinus Torvalds /* 3361da177e4SLinus Torvalds * Completion handler for block_write_full_page() - pages which are unlocked 3371da177e4SLinus Torvalds * during I/O, and which have PageWriteback cleared upon I/O completion. 3381da177e4SLinus Torvalds */ 33935c80d5fSChris Mason void end_buffer_async_write(struct buffer_head *bh, int uptodate) 3401da177e4SLinus Torvalds { 3411da177e4SLinus Torvalds unsigned long flags; 342a3972203SNick Piggin struct buffer_head *first; 3431da177e4SLinus Torvalds struct buffer_head *tmp; 3441da177e4SLinus Torvalds struct page *page; 3451da177e4SLinus Torvalds 3461da177e4SLinus Torvalds BUG_ON(!buffer_async_write(bh)); 3471da177e4SLinus Torvalds 3481da177e4SLinus Torvalds page = bh->b_page; 3491da177e4SLinus Torvalds if (uptodate) { 3501da177e4SLinus Torvalds set_buffer_uptodate(bh); 3511da177e4SLinus Torvalds } else { 352b744c2acSRobert Elliott buffer_io_error(bh, ", lost async page write"); 3531da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 35458ff407bSJan Kara set_buffer_write_io_error(bh); 3551da177e4SLinus Torvalds clear_buffer_uptodate(bh); 3561da177e4SLinus Torvalds SetPageError(page); 3571da177e4SLinus Torvalds } 3581da177e4SLinus Torvalds 359a3972203SNick Piggin first = page_buffers(page); 360a3972203SNick Piggin local_irq_save(flags); 361a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 362a3972203SNick Piggin 3631da177e4SLinus Torvalds clear_buffer_async_write(bh); 3641da177e4SLinus Torvalds unlock_buffer(bh); 3651da177e4SLinus Torvalds tmp = bh->b_this_page; 3661da177e4SLinus Torvalds while (tmp != bh) { 3671da177e4SLinus Torvalds if (buffer_async_write(tmp)) { 3681da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3691da177e4SLinus Torvalds goto still_busy; 3701da177e4SLinus Torvalds } 3711da177e4SLinus Torvalds tmp = tmp->b_this_page; 3721da177e4SLinus Torvalds } 373a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 374a3972203SNick Piggin local_irq_restore(flags); 3751da177e4SLinus Torvalds end_page_writeback(page); 3761da177e4SLinus Torvalds return; 3771da177e4SLinus Torvalds 3781da177e4SLinus Torvalds still_busy: 379a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 380a3972203SNick Piggin local_irq_restore(flags); 3811da177e4SLinus Torvalds return; 3821da177e4SLinus Torvalds } 3831fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_async_write); 3841da177e4SLinus Torvalds 3851da177e4SLinus Torvalds /* 3861da177e4SLinus Torvalds * If a page's buffers are under async readin (end_buffer_async_read 3871da177e4SLinus Torvalds * completion) then there is a possibility that another thread of 3881da177e4SLinus Torvalds * control could lock one of the buffers after it has completed 3891da177e4SLinus Torvalds * but while some of the other buffers have not completed. This 3901da177e4SLinus Torvalds * locked buffer would confuse end_buffer_async_read() into not unlocking 3911da177e4SLinus Torvalds * the page. So the absence of BH_Async_Read tells end_buffer_async_read() 3921da177e4SLinus Torvalds * that this buffer is not under async I/O. 3931da177e4SLinus Torvalds * 3941da177e4SLinus Torvalds * The page comes unlocked when it has no locked buffer_async buffers 3951da177e4SLinus Torvalds * left. 3961da177e4SLinus Torvalds * 3971da177e4SLinus Torvalds * PageLocked prevents anyone starting new async I/O reads any of 3981da177e4SLinus Torvalds * the buffers. 3991da177e4SLinus Torvalds * 4001da177e4SLinus Torvalds * PageWriteback is used to prevent simultaneous writeout of the same 4011da177e4SLinus Torvalds * page. 4021da177e4SLinus Torvalds * 4031da177e4SLinus Torvalds * PageLocked prevents anyone from starting writeback of a page which is 4041da177e4SLinus Torvalds * under read I/O (PageWriteback is only ever set against a locked page). 4051da177e4SLinus Torvalds */ 4061da177e4SLinus Torvalds static void mark_buffer_async_read(struct buffer_head *bh) 4071da177e4SLinus Torvalds { 4081da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_read; 4091da177e4SLinus Torvalds set_buffer_async_read(bh); 4101da177e4SLinus Torvalds } 4111da177e4SLinus Torvalds 4121fe72eaaSH Hartley Sweeten static void mark_buffer_async_write_endio(struct buffer_head *bh, 41335c80d5fSChris Mason bh_end_io_t *handler) 41435c80d5fSChris Mason { 41535c80d5fSChris Mason bh->b_end_io = handler; 41635c80d5fSChris Mason set_buffer_async_write(bh); 41735c80d5fSChris Mason } 41835c80d5fSChris Mason 4191da177e4SLinus Torvalds void mark_buffer_async_write(struct buffer_head *bh) 4201da177e4SLinus Torvalds { 42135c80d5fSChris Mason mark_buffer_async_write_endio(bh, end_buffer_async_write); 4221da177e4SLinus Torvalds } 4231da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_async_write); 4241da177e4SLinus Torvalds 4251da177e4SLinus Torvalds 4261da177e4SLinus Torvalds /* 4271da177e4SLinus Torvalds * fs/buffer.c contains helper functions for buffer-backed address space's 4281da177e4SLinus Torvalds * fsync functions. A common requirement for buffer-based filesystems is 4291da177e4SLinus Torvalds * that certain data from the backing blockdev needs to be written out for 4301da177e4SLinus Torvalds * a successful fsync(). For example, ext2 indirect blocks need to be 4311da177e4SLinus Torvalds * written back and waited upon before fsync() returns. 4321da177e4SLinus Torvalds * 4331da177e4SLinus Torvalds * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), 4341da177e4SLinus Torvalds * inode_has_buffers() and invalidate_inode_buffers() are provided for the 4351da177e4SLinus Torvalds * management of a list of dependent buffers at ->i_mapping->private_list. 4361da177e4SLinus Torvalds * 4371da177e4SLinus Torvalds * Locking is a little subtle: try_to_free_buffers() will remove buffers 4381da177e4SLinus Torvalds * from their controlling inode's queue when they are being freed. But 4391da177e4SLinus Torvalds * try_to_free_buffers() will be operating against the *blockdev* mapping 4401da177e4SLinus Torvalds * at the time, not against the S_ISREG file which depends on those buffers. 4411da177e4SLinus Torvalds * So the locking for private_list is via the private_lock in the address_space 4421da177e4SLinus Torvalds * which backs the buffers. Which is different from the address_space 4431da177e4SLinus Torvalds * against which the buffers are listed. So for a particular address_space, 4441da177e4SLinus Torvalds * mapping->private_lock does *not* protect mapping->private_list! In fact, 4451da177e4SLinus Torvalds * mapping->private_list will always be protected by the backing blockdev's 4461da177e4SLinus Torvalds * ->private_lock. 4471da177e4SLinus Torvalds * 4481da177e4SLinus Torvalds * Which introduces a requirement: all buffers on an address_space's 4491da177e4SLinus Torvalds * ->private_list must be from the same address_space: the blockdev's. 4501da177e4SLinus Torvalds * 4511da177e4SLinus Torvalds * address_spaces which do not place buffers at ->private_list via these 4521da177e4SLinus Torvalds * utility functions are free to use private_lock and private_list for 4531da177e4SLinus Torvalds * whatever they want. The only requirement is that list_empty(private_list) 4541da177e4SLinus Torvalds * be true at clear_inode() time. 4551da177e4SLinus Torvalds * 4561da177e4SLinus Torvalds * FIXME: clear_inode should not call invalidate_inode_buffers(). The 4571da177e4SLinus Torvalds * filesystems should do that. invalidate_inode_buffers() should just go 4581da177e4SLinus Torvalds * BUG_ON(!list_empty). 4591da177e4SLinus Torvalds * 4601da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should 4611da177e4SLinus Torvalds * take an address_space, not an inode. And it should be called 4621da177e4SLinus Torvalds * mark_buffer_dirty_fsync() to clearly define why those buffers are being 4631da177e4SLinus Torvalds * queued up. 4641da177e4SLinus Torvalds * 4651da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the 4661da177e4SLinus Torvalds * list if it is already on a list. Because if the buffer is on a list, 4671da177e4SLinus Torvalds * it *must* already be on the right one. If not, the filesystem is being 4681da177e4SLinus Torvalds * silly. This will save a ton of locking. But first we have to ensure 4691da177e4SLinus Torvalds * that buffers are taken *off* the old inode's list when they are freed 4701da177e4SLinus Torvalds * (presumably in truncate). That requires careful auditing of all 4711da177e4SLinus Torvalds * filesystems (do it inside bforget()). It could also be done by bringing 4721da177e4SLinus Torvalds * b_inode back. 4731da177e4SLinus Torvalds */ 4741da177e4SLinus Torvalds 4751da177e4SLinus Torvalds /* 4761da177e4SLinus Torvalds * The buffer's backing address_space's private_lock must be held 4771da177e4SLinus Torvalds */ 478dbacefc9SThomas Petazzoni static void __remove_assoc_queue(struct buffer_head *bh) 4791da177e4SLinus Torvalds { 4801da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 48158ff407bSJan Kara WARN_ON(!bh->b_assoc_map); 48258ff407bSJan Kara if (buffer_write_io_error(bh)) 48358ff407bSJan Kara set_bit(AS_EIO, &bh->b_assoc_map->flags); 48458ff407bSJan Kara bh->b_assoc_map = NULL; 4851da177e4SLinus Torvalds } 4861da177e4SLinus Torvalds 4871da177e4SLinus Torvalds int inode_has_buffers(struct inode *inode) 4881da177e4SLinus Torvalds { 4891da177e4SLinus Torvalds return !list_empty(&inode->i_data.private_list); 4901da177e4SLinus Torvalds } 4911da177e4SLinus Torvalds 4921da177e4SLinus Torvalds /* 4931da177e4SLinus Torvalds * osync is designed to support O_SYNC io. It waits synchronously for 4941da177e4SLinus Torvalds * all already-submitted IO to complete, but does not queue any new 4951da177e4SLinus Torvalds * writes to the disk. 4961da177e4SLinus Torvalds * 4971da177e4SLinus Torvalds * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as 4981da177e4SLinus Torvalds * you dirty the buffers, and then use osync_inode_buffers to wait for 4991da177e4SLinus Torvalds * completion. Any other dirty buffers which are not yet queued for 5001da177e4SLinus Torvalds * write will not be flushed to disk by the osync. 5011da177e4SLinus Torvalds */ 5021da177e4SLinus Torvalds static int osync_buffers_list(spinlock_t *lock, struct list_head *list) 5031da177e4SLinus Torvalds { 5041da177e4SLinus Torvalds struct buffer_head *bh; 5051da177e4SLinus Torvalds struct list_head *p; 5061da177e4SLinus Torvalds int err = 0; 5071da177e4SLinus Torvalds 5081da177e4SLinus Torvalds spin_lock(lock); 5091da177e4SLinus Torvalds repeat: 5101da177e4SLinus Torvalds list_for_each_prev(p, list) { 5111da177e4SLinus Torvalds bh = BH_ENTRY(p); 5121da177e4SLinus Torvalds if (buffer_locked(bh)) { 5131da177e4SLinus Torvalds get_bh(bh); 5141da177e4SLinus Torvalds spin_unlock(lock); 5151da177e4SLinus Torvalds wait_on_buffer(bh); 5161da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 5171da177e4SLinus Torvalds err = -EIO; 5181da177e4SLinus Torvalds brelse(bh); 5191da177e4SLinus Torvalds spin_lock(lock); 5201da177e4SLinus Torvalds goto repeat; 5211da177e4SLinus Torvalds } 5221da177e4SLinus Torvalds } 5231da177e4SLinus Torvalds spin_unlock(lock); 5241da177e4SLinus Torvalds return err; 5251da177e4SLinus Torvalds } 5261da177e4SLinus Torvalds 52701a05b33SAl Viro static void do_thaw_one(struct super_block *sb, void *unused) 528c2d75438SEric Sandeen { 529c2d75438SEric Sandeen while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) 530a1c6f057SDmitry Monakhov printk(KERN_WARNING "Emergency Thaw on %pg\n", sb->s_bdev); 531c2d75438SEric Sandeen } 53201a05b33SAl Viro 53301a05b33SAl Viro static void do_thaw_all(struct work_struct *work) 53401a05b33SAl Viro { 53501a05b33SAl Viro iterate_supers(do_thaw_one, NULL); 536053c525fSJens Axboe kfree(work); 537c2d75438SEric Sandeen printk(KERN_WARNING "Emergency Thaw complete\n"); 538c2d75438SEric Sandeen } 539c2d75438SEric Sandeen 540c2d75438SEric Sandeen /** 541c2d75438SEric Sandeen * emergency_thaw_all -- forcibly thaw every frozen filesystem 542c2d75438SEric Sandeen * 543c2d75438SEric Sandeen * Used for emergency unfreeze of all filesystems via SysRq 544c2d75438SEric Sandeen */ 545c2d75438SEric Sandeen void emergency_thaw_all(void) 546c2d75438SEric Sandeen { 547053c525fSJens Axboe struct work_struct *work; 548053c525fSJens Axboe 549053c525fSJens Axboe work = kmalloc(sizeof(*work), GFP_ATOMIC); 550053c525fSJens Axboe if (work) { 551053c525fSJens Axboe INIT_WORK(work, do_thaw_all); 552053c525fSJens Axboe schedule_work(work); 553053c525fSJens Axboe } 554c2d75438SEric Sandeen } 555c2d75438SEric Sandeen 5561da177e4SLinus Torvalds /** 55778a4a50aSRandy Dunlap * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers 55867be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 5591da177e4SLinus Torvalds * 5601da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 5611da177e4SLinus Torvalds * that I/O. 5621da177e4SLinus Torvalds * 56367be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 56467be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 56567be2dd1SMartin Waitz * a successful fsync(). 5661da177e4SLinus Torvalds */ 5671da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 5681da177e4SLinus Torvalds { 569252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 5701da177e4SLinus Torvalds 5711da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 5721da177e4SLinus Torvalds return 0; 5731da177e4SLinus Torvalds 5741da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 5751da177e4SLinus Torvalds &mapping->private_list); 5761da177e4SLinus Torvalds } 5771da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 5781da177e4SLinus Torvalds 5791da177e4SLinus Torvalds /* 5801da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 5811da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 5821da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 5831da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 5841da177e4SLinus Torvalds */ 5851da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 5861da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 5871da177e4SLinus Torvalds { 5881da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 5891da177e4SLinus Torvalds if (bh) { 5901da177e4SLinus Torvalds if (buffer_dirty(bh)) 5911da177e4SLinus Torvalds ll_rw_block(WRITE, 1, &bh); 5921da177e4SLinus Torvalds put_bh(bh); 5931da177e4SLinus Torvalds } 5941da177e4SLinus Torvalds } 5951da177e4SLinus Torvalds 5961da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 5971da177e4SLinus Torvalds { 5981da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 5991da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 6001da177e4SLinus Torvalds 6011da177e4SLinus Torvalds mark_buffer_dirty(bh); 602252aa6f5SRafael Aquini if (!mapping->private_data) { 603252aa6f5SRafael Aquini mapping->private_data = buffer_mapping; 6041da177e4SLinus Torvalds } else { 605252aa6f5SRafael Aquini BUG_ON(mapping->private_data != buffer_mapping); 6061da177e4SLinus Torvalds } 607535ee2fbSJan Kara if (!bh->b_assoc_map) { 6081da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 6091da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 6101da177e4SLinus Torvalds &mapping->private_list); 61158ff407bSJan Kara bh->b_assoc_map = mapping; 6121da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 6131da177e4SLinus Torvalds } 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 6161da177e4SLinus Torvalds 6171da177e4SLinus Torvalds /* 618787d2214SNick Piggin * Mark the page dirty, and set it dirty in the radix tree, and mark the inode 619787d2214SNick Piggin * dirty. 620787d2214SNick Piggin * 621787d2214SNick Piggin * If warn is true, then emit a warning if the page is not uptodate and has 622787d2214SNick Piggin * not been truncated. 623c4843a75SGreg Thelen * 62481f8c3a4SJohannes Weiner * The caller must hold lock_page_memcg(). 625787d2214SNick Piggin */ 626c4843a75SGreg Thelen static void __set_page_dirty(struct page *page, struct address_space *mapping, 62762cccb8cSJohannes Weiner int warn) 628787d2214SNick Piggin { 629227d53b3SKOSAKI Motohiro unsigned long flags; 630227d53b3SKOSAKI Motohiro 631227d53b3SKOSAKI Motohiro spin_lock_irqsave(&mapping->tree_lock, flags); 632787d2214SNick Piggin if (page->mapping) { /* Race with truncate? */ 633787d2214SNick Piggin WARN_ON_ONCE(warn && !PageUptodate(page)); 63462cccb8cSJohannes Weiner account_page_dirtied(page, mapping); 635787d2214SNick Piggin radix_tree_tag_set(&mapping->page_tree, 636787d2214SNick Piggin page_index(page), PAGECACHE_TAG_DIRTY); 637787d2214SNick Piggin } 638227d53b3SKOSAKI Motohiro spin_unlock_irqrestore(&mapping->tree_lock, flags); 639787d2214SNick Piggin } 640787d2214SNick Piggin 641787d2214SNick Piggin /* 6421da177e4SLinus Torvalds * Add a page to the dirty page list. 6431da177e4SLinus Torvalds * 6441da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 6451da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 6461da177e4SLinus Torvalds * 6471da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 6481da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 6491da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 6501da177e4SLinus Torvalds * dirty. 6511da177e4SLinus Torvalds * 6521da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 6531da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 6541da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 6551da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 6561da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 6571da177e4SLinus Torvalds * page on the dirty page list. 6581da177e4SLinus Torvalds * 6591da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 6601da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 6611da177e4SLinus Torvalds * added to the page after it was set dirty. 6621da177e4SLinus Torvalds * 6631da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 6641da177e4SLinus Torvalds * address_space though. 6651da177e4SLinus Torvalds */ 6661da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 6671da177e4SLinus Torvalds { 668a8e7d49aSLinus Torvalds int newly_dirty; 669787d2214SNick Piggin struct address_space *mapping = page_mapping(page); 670ebf7a227SNick Piggin 671ebf7a227SNick Piggin if (unlikely(!mapping)) 672ebf7a227SNick Piggin return !TestSetPageDirty(page); 6731da177e4SLinus Torvalds 6741da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 6751da177e4SLinus Torvalds if (page_has_buffers(page)) { 6761da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 6771da177e4SLinus Torvalds struct buffer_head *bh = head; 6781da177e4SLinus Torvalds 6791da177e4SLinus Torvalds do { 6801da177e4SLinus Torvalds set_buffer_dirty(bh); 6811da177e4SLinus Torvalds bh = bh->b_this_page; 6821da177e4SLinus Torvalds } while (bh != head); 6831da177e4SLinus Torvalds } 684c4843a75SGreg Thelen /* 68581f8c3a4SJohannes Weiner * Lock out page->mem_cgroup migration to keep PageDirty 68681f8c3a4SJohannes Weiner * synchronized with per-memcg dirty page counters. 687c4843a75SGreg Thelen */ 68862cccb8cSJohannes Weiner lock_page_memcg(page); 689a8e7d49aSLinus Torvalds newly_dirty = !TestSetPageDirty(page); 6901da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 6911da177e4SLinus Torvalds 692a8e7d49aSLinus Torvalds if (newly_dirty) 69362cccb8cSJohannes Weiner __set_page_dirty(page, mapping, 1); 694c4843a75SGreg Thelen 69562cccb8cSJohannes Weiner unlock_page_memcg(page); 696c4843a75SGreg Thelen 697c4843a75SGreg Thelen if (newly_dirty) 698c4843a75SGreg Thelen __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 699c4843a75SGreg Thelen 700a8e7d49aSLinus Torvalds return newly_dirty; 7011da177e4SLinus Torvalds } 7021da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 7031da177e4SLinus Torvalds 7041da177e4SLinus Torvalds /* 7051da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 7061da177e4SLinus Torvalds * 7071da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 7081da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 7091da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 7101da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 7111da177e4SLinus Torvalds * 7121da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 7131da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 7141da177e4SLinus Torvalds * up, waiting for those writes to complete. 7151da177e4SLinus Torvalds * 7161da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 7171da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 7181da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 7191da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 7201da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 7211da177e4SLinus Torvalds * any newly dirty buffers for write. 7221da177e4SLinus Torvalds */ 7231da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 7241da177e4SLinus Torvalds { 7251da177e4SLinus Torvalds struct buffer_head *bh; 7261da177e4SLinus Torvalds struct list_head tmp; 7277eaceaccSJens Axboe struct address_space *mapping; 7281da177e4SLinus Torvalds int err = 0, err2; 7294ee2491eSJens Axboe struct blk_plug plug; 7301da177e4SLinus Torvalds 7311da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 7324ee2491eSJens Axboe blk_start_plug(&plug); 7331da177e4SLinus Torvalds 7341da177e4SLinus Torvalds spin_lock(lock); 7351da177e4SLinus Torvalds while (!list_empty(list)) { 7361da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 737535ee2fbSJan Kara mapping = bh->b_assoc_map; 73858ff407bSJan Kara __remove_assoc_queue(bh); 739535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 740535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 741535ee2fbSJan Kara smp_mb(); 7421da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 7431da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 744535ee2fbSJan Kara bh->b_assoc_map = mapping; 7451da177e4SLinus Torvalds if (buffer_dirty(bh)) { 7461da177e4SLinus Torvalds get_bh(bh); 7471da177e4SLinus Torvalds spin_unlock(lock); 7481da177e4SLinus Torvalds /* 7491da177e4SLinus Torvalds * Ensure any pending I/O completes so that 7509cb569d6SChristoph Hellwig * write_dirty_buffer() actually writes the 7519cb569d6SChristoph Hellwig * current contents - it is a noop if I/O is 7529cb569d6SChristoph Hellwig * still in flight on potentially older 7539cb569d6SChristoph Hellwig * contents. 7541da177e4SLinus Torvalds */ 755721a9602SJens Axboe write_dirty_buffer(bh, WRITE_SYNC); 7569cf6b720SJens Axboe 7579cf6b720SJens Axboe /* 7589cf6b720SJens Axboe * Kick off IO for the previous mapping. Note 7599cf6b720SJens Axboe * that we will not run the very last mapping, 7609cf6b720SJens Axboe * wait_on_buffer() will do that for us 7619cf6b720SJens Axboe * through sync_buffer(). 7629cf6b720SJens Axboe */ 7631da177e4SLinus Torvalds brelse(bh); 7641da177e4SLinus Torvalds spin_lock(lock); 7651da177e4SLinus Torvalds } 7661da177e4SLinus Torvalds } 7671da177e4SLinus Torvalds } 7681da177e4SLinus Torvalds 7694ee2491eSJens Axboe spin_unlock(lock); 7704ee2491eSJens Axboe blk_finish_plug(&plug); 7714ee2491eSJens Axboe spin_lock(lock); 7724ee2491eSJens Axboe 7731da177e4SLinus Torvalds while (!list_empty(&tmp)) { 7741da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 7751da177e4SLinus Torvalds get_bh(bh); 776535ee2fbSJan Kara mapping = bh->b_assoc_map; 777535ee2fbSJan Kara __remove_assoc_queue(bh); 778535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 779535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 780535ee2fbSJan Kara smp_mb(); 781535ee2fbSJan Kara if (buffer_dirty(bh)) { 782535ee2fbSJan Kara list_add(&bh->b_assoc_buffers, 783e3892296SJan Kara &mapping->private_list); 784535ee2fbSJan Kara bh->b_assoc_map = mapping; 785535ee2fbSJan Kara } 7861da177e4SLinus Torvalds spin_unlock(lock); 7871da177e4SLinus Torvalds wait_on_buffer(bh); 7881da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 7891da177e4SLinus Torvalds err = -EIO; 7901da177e4SLinus Torvalds brelse(bh); 7911da177e4SLinus Torvalds spin_lock(lock); 7921da177e4SLinus Torvalds } 7931da177e4SLinus Torvalds 7941da177e4SLinus Torvalds spin_unlock(lock); 7951da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 7961da177e4SLinus Torvalds if (err) 7971da177e4SLinus Torvalds return err; 7981da177e4SLinus Torvalds else 7991da177e4SLinus Torvalds return err2; 8001da177e4SLinus Torvalds } 8011da177e4SLinus Torvalds 8021da177e4SLinus Torvalds /* 8031da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 8041da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 8051da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 8061da177e4SLinus Torvalds * 8071da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 8081da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 8091da177e4SLinus Torvalds * for reiserfs. 8101da177e4SLinus Torvalds */ 8111da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 8121da177e4SLinus Torvalds { 8131da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8141da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8151da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 816252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 8171da177e4SLinus Torvalds 8181da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8191da177e4SLinus Torvalds while (!list_empty(list)) 8201da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 8211da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8221da177e4SLinus Torvalds } 8231da177e4SLinus Torvalds } 82452b19ac9SJan Kara EXPORT_SYMBOL(invalidate_inode_buffers); 8251da177e4SLinus Torvalds 8261da177e4SLinus Torvalds /* 8271da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 8281da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 8291da177e4SLinus Torvalds * 8301da177e4SLinus Torvalds * Returns true if all buffers were removed. 8311da177e4SLinus Torvalds */ 8321da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 8331da177e4SLinus Torvalds { 8341da177e4SLinus Torvalds int ret = 1; 8351da177e4SLinus Torvalds 8361da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8371da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8381da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 839252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 8401da177e4SLinus Torvalds 8411da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8421da177e4SLinus Torvalds while (!list_empty(list)) { 8431da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 8441da177e4SLinus Torvalds if (buffer_dirty(bh)) { 8451da177e4SLinus Torvalds ret = 0; 8461da177e4SLinus Torvalds break; 8471da177e4SLinus Torvalds } 8481da177e4SLinus Torvalds __remove_assoc_queue(bh); 8491da177e4SLinus Torvalds } 8501da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8511da177e4SLinus Torvalds } 8521da177e4SLinus Torvalds return ret; 8531da177e4SLinus Torvalds } 8541da177e4SLinus Torvalds 8551da177e4SLinus Torvalds /* 8561da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 8571da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 8581da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 8591da177e4SLinus Torvalds * buffers. 8601da177e4SLinus Torvalds * 8611da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 8621da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 8631da177e4SLinus Torvalds */ 8641da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 8651da177e4SLinus Torvalds int retry) 8661da177e4SLinus Torvalds { 8671da177e4SLinus Torvalds struct buffer_head *bh, *head; 8681da177e4SLinus Torvalds long offset; 8691da177e4SLinus Torvalds 8701da177e4SLinus Torvalds try_again: 8711da177e4SLinus Torvalds head = NULL; 8721da177e4SLinus Torvalds offset = PAGE_SIZE; 8731da177e4SLinus Torvalds while ((offset -= size) >= 0) { 8741da177e4SLinus Torvalds bh = alloc_buffer_head(GFP_NOFS); 8751da177e4SLinus Torvalds if (!bh) 8761da177e4SLinus Torvalds goto no_grow; 8771da177e4SLinus Torvalds 8781da177e4SLinus Torvalds bh->b_this_page = head; 8791da177e4SLinus Torvalds bh->b_blocknr = -1; 8801da177e4SLinus Torvalds head = bh; 8811da177e4SLinus Torvalds 8821da177e4SLinus Torvalds bh->b_size = size; 8831da177e4SLinus Torvalds 8841da177e4SLinus Torvalds /* Link the buffer to its page */ 8851da177e4SLinus Torvalds set_bh_page(bh, page, offset); 8861da177e4SLinus Torvalds } 8871da177e4SLinus Torvalds return head; 8881da177e4SLinus Torvalds /* 8891da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 8901da177e4SLinus Torvalds */ 8911da177e4SLinus Torvalds no_grow: 8921da177e4SLinus Torvalds if (head) { 8931da177e4SLinus Torvalds do { 8941da177e4SLinus Torvalds bh = head; 8951da177e4SLinus Torvalds head = head->b_this_page; 8961da177e4SLinus Torvalds free_buffer_head(bh); 8971da177e4SLinus Torvalds } while (head); 8981da177e4SLinus Torvalds } 8991da177e4SLinus Torvalds 9001da177e4SLinus Torvalds /* 9011da177e4SLinus Torvalds * Return failure for non-async IO requests. Async IO requests 9021da177e4SLinus Torvalds * are not allowed to fail, so we have to wait until buffer heads 9031da177e4SLinus Torvalds * become available. But we don't want tasks sleeping with 9041da177e4SLinus Torvalds * partially complete buffers, so all were released above. 9051da177e4SLinus Torvalds */ 9061da177e4SLinus Torvalds if (!retry) 9071da177e4SLinus Torvalds return NULL; 9081da177e4SLinus Torvalds 9091da177e4SLinus Torvalds /* We're _really_ low on memory. Now we just 9101da177e4SLinus Torvalds * wait for old buffer heads to become free due to 9111da177e4SLinus Torvalds * finishing IO. Since this is an async request and 9121da177e4SLinus Torvalds * the reserve list is empty, we're sure there are 9131da177e4SLinus Torvalds * async buffer heads in use. 9141da177e4SLinus Torvalds */ 9151da177e4SLinus Torvalds free_more_memory(); 9161da177e4SLinus Torvalds goto try_again; 9171da177e4SLinus Torvalds } 9181da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 9191da177e4SLinus Torvalds 9201da177e4SLinus Torvalds static inline void 9211da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 9221da177e4SLinus Torvalds { 9231da177e4SLinus Torvalds struct buffer_head *bh, *tail; 9241da177e4SLinus Torvalds 9251da177e4SLinus Torvalds bh = head; 9261da177e4SLinus Torvalds do { 9271da177e4SLinus Torvalds tail = bh; 9281da177e4SLinus Torvalds bh = bh->b_this_page; 9291da177e4SLinus Torvalds } while (bh); 9301da177e4SLinus Torvalds tail->b_this_page = head; 9311da177e4SLinus Torvalds attach_page_buffers(page, head); 9321da177e4SLinus Torvalds } 9331da177e4SLinus Torvalds 934bbec0270SLinus Torvalds static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) 935bbec0270SLinus Torvalds { 936bbec0270SLinus Torvalds sector_t retval = ~((sector_t)0); 937bbec0270SLinus Torvalds loff_t sz = i_size_read(bdev->bd_inode); 938bbec0270SLinus Torvalds 939bbec0270SLinus Torvalds if (sz) { 940bbec0270SLinus Torvalds unsigned int sizebits = blksize_bits(size); 941bbec0270SLinus Torvalds retval = (sz >> sizebits); 942bbec0270SLinus Torvalds } 943bbec0270SLinus Torvalds return retval; 944bbec0270SLinus Torvalds } 945bbec0270SLinus Torvalds 9461da177e4SLinus Torvalds /* 9471da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 9481da177e4SLinus Torvalds */ 949676ce6d5SHugh Dickins static sector_t 9501da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 9511da177e4SLinus Torvalds sector_t block, int size) 9521da177e4SLinus Torvalds { 9531da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 9541da177e4SLinus Torvalds struct buffer_head *bh = head; 9551da177e4SLinus Torvalds int uptodate = PageUptodate(page); 956bbec0270SLinus Torvalds sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size); 9571da177e4SLinus Torvalds 9581da177e4SLinus Torvalds do { 9591da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 9601da177e4SLinus Torvalds init_buffer(bh, NULL, NULL); 9611da177e4SLinus Torvalds bh->b_bdev = bdev; 9621da177e4SLinus Torvalds bh->b_blocknr = block; 9631da177e4SLinus Torvalds if (uptodate) 9641da177e4SLinus Torvalds set_buffer_uptodate(bh); 965080399aaSJeff Moyer if (block < end_block) 9661da177e4SLinus Torvalds set_buffer_mapped(bh); 9671da177e4SLinus Torvalds } 9681da177e4SLinus Torvalds block++; 9691da177e4SLinus Torvalds bh = bh->b_this_page; 9701da177e4SLinus Torvalds } while (bh != head); 971676ce6d5SHugh Dickins 972676ce6d5SHugh Dickins /* 973676ce6d5SHugh Dickins * Caller needs to validate requested block against end of device. 974676ce6d5SHugh Dickins */ 975676ce6d5SHugh Dickins return end_block; 9761da177e4SLinus Torvalds } 9771da177e4SLinus Torvalds 9781da177e4SLinus Torvalds /* 9791da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 9801da177e4SLinus Torvalds * 981676ce6d5SHugh Dickins * This is used purely for blockdev mappings. 9821da177e4SLinus Torvalds */ 983676ce6d5SHugh Dickins static int 9841da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 9853b5e6454SGioh Kim pgoff_t index, int size, int sizebits, gfp_t gfp) 9861da177e4SLinus Torvalds { 9871da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 9881da177e4SLinus Torvalds struct page *page; 9891da177e4SLinus Torvalds struct buffer_head *bh; 990676ce6d5SHugh Dickins sector_t end_block; 991676ce6d5SHugh Dickins int ret = 0; /* Will call free_more_memory() */ 99284235de3SJohannes Weiner gfp_t gfp_mask; 9931da177e4SLinus Torvalds 994c62d2555SMichal Hocko gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp; 9953b5e6454SGioh Kim 99684235de3SJohannes Weiner /* 99784235de3SJohannes Weiner * XXX: __getblk_slow() can not really deal with failure and 99884235de3SJohannes Weiner * will endlessly loop on improvised global reclaim. Prefer 99984235de3SJohannes Weiner * looping in the allocator rather than here, at least that 100084235de3SJohannes Weiner * code knows what it's doing. 100184235de3SJohannes Weiner */ 100284235de3SJohannes Weiner gfp_mask |= __GFP_NOFAIL; 100384235de3SJohannes Weiner 100484235de3SJohannes Weiner page = find_or_create_page(inode->i_mapping, index, gfp_mask); 10051da177e4SLinus Torvalds if (!page) 1006676ce6d5SHugh Dickins return ret; 10071da177e4SLinus Torvalds 1008e827f923SEric Sesterhenn BUG_ON(!PageLocked(page)); 10091da177e4SLinus Torvalds 10101da177e4SLinus Torvalds if (page_has_buffers(page)) { 10111da177e4SLinus Torvalds bh = page_buffers(page); 10121da177e4SLinus Torvalds if (bh->b_size == size) { 1013676ce6d5SHugh Dickins end_block = init_page_buffers(page, bdev, 1014f2d5a944SAnton Altaparmakov (sector_t)index << sizebits, 1015f2d5a944SAnton Altaparmakov size); 1016676ce6d5SHugh Dickins goto done; 10171da177e4SLinus Torvalds } 10181da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 10191da177e4SLinus Torvalds goto failed; 10201da177e4SLinus Torvalds } 10211da177e4SLinus Torvalds 10221da177e4SLinus Torvalds /* 10231da177e4SLinus Torvalds * Allocate some buffers for this page 10241da177e4SLinus Torvalds */ 10251da177e4SLinus Torvalds bh = alloc_page_buffers(page, size, 0); 10261da177e4SLinus Torvalds if (!bh) 10271da177e4SLinus Torvalds goto failed; 10281da177e4SLinus Torvalds 10291da177e4SLinus Torvalds /* 10301da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 10311da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 10321da177e4SLinus Torvalds * run under the page lock. 10331da177e4SLinus Torvalds */ 10341da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 10351da177e4SLinus Torvalds link_dev_buffers(page, bh); 1036f2d5a944SAnton Altaparmakov end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits, 1037f2d5a944SAnton Altaparmakov size); 10381da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 1039676ce6d5SHugh Dickins done: 1040676ce6d5SHugh Dickins ret = (block < end_block) ? 1 : -ENXIO; 10411da177e4SLinus Torvalds failed: 10421da177e4SLinus Torvalds unlock_page(page); 104309cbfeafSKirill A. Shutemov put_page(page); 1044676ce6d5SHugh Dickins return ret; 10451da177e4SLinus Torvalds } 10461da177e4SLinus Torvalds 10471da177e4SLinus Torvalds /* 10481da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 10491da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 10501da177e4SLinus Torvalds */ 1051858119e1SArjan van de Ven static int 10523b5e6454SGioh Kim grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) 10531da177e4SLinus Torvalds { 10541da177e4SLinus Torvalds pgoff_t index; 10551da177e4SLinus Torvalds int sizebits; 10561da177e4SLinus Torvalds 10571da177e4SLinus Torvalds sizebits = -1; 10581da177e4SLinus Torvalds do { 10591da177e4SLinus Torvalds sizebits++; 10601da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 10611da177e4SLinus Torvalds 10621da177e4SLinus Torvalds index = block >> sizebits; 10631da177e4SLinus Torvalds 1064e5657933SAndrew Morton /* 1065e5657933SAndrew Morton * Check for a block which wants to lie outside our maximum possible 1066e5657933SAndrew Morton * pagecache index. (this comparison is done using sector_t types). 1067e5657933SAndrew Morton */ 1068e5657933SAndrew Morton if (unlikely(index != block >> sizebits)) { 1069e5657933SAndrew Morton printk(KERN_ERR "%s: requested out-of-range block %llu for " 1070a1c6f057SDmitry Monakhov "device %pg\n", 10718e24eea7SHarvey Harrison __func__, (unsigned long long)block, 1072a1c6f057SDmitry Monakhov bdev); 1073e5657933SAndrew Morton return -EIO; 1074e5657933SAndrew Morton } 1075676ce6d5SHugh Dickins 10761da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 10773b5e6454SGioh Kim return grow_dev_page(bdev, block, index, size, sizebits, gfp); 10781da177e4SLinus Torvalds } 10791da177e4SLinus Torvalds 10803b5e6454SGioh Kim struct buffer_head * 10813b5e6454SGioh Kim __getblk_slow(struct block_device *bdev, sector_t block, 10823b5e6454SGioh Kim unsigned size, gfp_t gfp) 10831da177e4SLinus Torvalds { 10841da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 1085e1defc4fSMartin K. Petersen if (unlikely(size & (bdev_logical_block_size(bdev)-1) || 10861da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 10871da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 10881da177e4SLinus Torvalds size); 1089e1defc4fSMartin K. Petersen printk(KERN_ERR "logical block size: %d\n", 1090e1defc4fSMartin K. Petersen bdev_logical_block_size(bdev)); 10911da177e4SLinus Torvalds 10921da177e4SLinus Torvalds dump_stack(); 10931da177e4SLinus Torvalds return NULL; 10941da177e4SLinus Torvalds } 10951da177e4SLinus Torvalds 1096676ce6d5SHugh Dickins for (;;) { 1097676ce6d5SHugh Dickins struct buffer_head *bh; 1098676ce6d5SHugh Dickins int ret; 1099676ce6d5SHugh Dickins 11001da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 11011da177e4SLinus Torvalds if (bh) 11021da177e4SLinus Torvalds return bh; 11031da177e4SLinus Torvalds 11043b5e6454SGioh Kim ret = grow_buffers(bdev, block, size, gfp); 1105676ce6d5SHugh Dickins if (ret < 0) 110691f68c89SJeff Moyer return NULL; 1107676ce6d5SHugh Dickins if (ret == 0) 1108676ce6d5SHugh Dickins free_more_memory(); 1109676ce6d5SHugh Dickins } 11101da177e4SLinus Torvalds } 11113b5e6454SGioh Kim EXPORT_SYMBOL(__getblk_slow); 11121da177e4SLinus Torvalds 11131da177e4SLinus Torvalds /* 11141da177e4SLinus Torvalds * The relationship between dirty buffers and dirty pages: 11151da177e4SLinus Torvalds * 11161da177e4SLinus Torvalds * Whenever a page has any dirty buffers, the page's dirty bit is set, and 11171da177e4SLinus Torvalds * the page is tagged dirty in its radix tree. 11181da177e4SLinus Torvalds * 11191da177e4SLinus Torvalds * At all times, the dirtiness of the buffers represents the dirtiness of 11201da177e4SLinus Torvalds * subsections of the page. If the page has buffers, the page dirty bit is 11211da177e4SLinus Torvalds * merely a hint about the true dirty state. 11221da177e4SLinus Torvalds * 11231da177e4SLinus Torvalds * When a page is set dirty in its entirety, all its buffers are marked dirty 11241da177e4SLinus Torvalds * (if the page has buffers). 11251da177e4SLinus Torvalds * 11261da177e4SLinus Torvalds * When a buffer is marked dirty, its page is dirtied, but the page's other 11271da177e4SLinus Torvalds * buffers are not. 11281da177e4SLinus Torvalds * 11291da177e4SLinus Torvalds * Also. When blockdev buffers are explicitly read with bread(), they 11301da177e4SLinus Torvalds * individually become uptodate. But their backing page remains not 11311da177e4SLinus Torvalds * uptodate - even if all of its buffers are uptodate. A subsequent 11321da177e4SLinus Torvalds * block_read_full_page() against that page will discover all the uptodate 11331da177e4SLinus Torvalds * buffers, will set the page uptodate and will perform no I/O. 11341da177e4SLinus Torvalds */ 11351da177e4SLinus Torvalds 11361da177e4SLinus Torvalds /** 11371da177e4SLinus Torvalds * mark_buffer_dirty - mark a buffer_head as needing writeout 113867be2dd1SMartin Waitz * @bh: the buffer_head to mark dirty 11391da177e4SLinus Torvalds * 11401da177e4SLinus Torvalds * mark_buffer_dirty() will set the dirty bit against the buffer, then set its 11411da177e4SLinus Torvalds * backing page dirty, then tag the page as dirty in its address_space's radix 11421da177e4SLinus Torvalds * tree and then attach the address_space's inode to its superblock's dirty 11431da177e4SLinus Torvalds * inode list. 11441da177e4SLinus Torvalds * 11451da177e4SLinus Torvalds * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, 1146250df6edSDave Chinner * mapping->tree_lock and mapping->host->i_lock. 11471da177e4SLinus Torvalds */ 1148fc9b52cdSHarvey Harrison void mark_buffer_dirty(struct buffer_head *bh) 11491da177e4SLinus Torvalds { 1150787d2214SNick Piggin WARN_ON_ONCE(!buffer_uptodate(bh)); 11511be62dc1SLinus Torvalds 11525305cb83STejun Heo trace_block_dirty_buffer(bh); 11535305cb83STejun Heo 11541be62dc1SLinus Torvalds /* 11551be62dc1SLinus Torvalds * Very *carefully* optimize the it-is-already-dirty case. 11561be62dc1SLinus Torvalds * 11571be62dc1SLinus Torvalds * Don't let the final "is it dirty" escape to before we 11581be62dc1SLinus Torvalds * perhaps modified the buffer. 11591be62dc1SLinus Torvalds */ 11601be62dc1SLinus Torvalds if (buffer_dirty(bh)) { 11611be62dc1SLinus Torvalds smp_mb(); 11621be62dc1SLinus Torvalds if (buffer_dirty(bh)) 11631be62dc1SLinus Torvalds return; 11641be62dc1SLinus Torvalds } 11651be62dc1SLinus Torvalds 1166a8e7d49aSLinus Torvalds if (!test_set_buffer_dirty(bh)) { 1167a8e7d49aSLinus Torvalds struct page *page = bh->b_page; 1168c4843a75SGreg Thelen struct address_space *mapping = NULL; 1169c4843a75SGreg Thelen 117062cccb8cSJohannes Weiner lock_page_memcg(page); 11718e9d78edSLinus Torvalds if (!TestSetPageDirty(page)) { 1172c4843a75SGreg Thelen mapping = page_mapping(page); 11738e9d78edSLinus Torvalds if (mapping) 117462cccb8cSJohannes Weiner __set_page_dirty(page, mapping, 0); 11758e9d78edSLinus Torvalds } 117662cccb8cSJohannes Weiner unlock_page_memcg(page); 1177c4843a75SGreg Thelen if (mapping) 1178c4843a75SGreg Thelen __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 1179a8e7d49aSLinus Torvalds } 11801da177e4SLinus Torvalds } 11811fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(mark_buffer_dirty); 11821da177e4SLinus Torvalds 11831da177e4SLinus Torvalds /* 11841da177e4SLinus Torvalds * Decrement a buffer_head's reference count. If all buffers against a page 11851da177e4SLinus Torvalds * have zero reference count, are clean and unlocked, and if the page is clean 11861da177e4SLinus Torvalds * and unlocked then try_to_free_buffers() may strip the buffers from the page 11871da177e4SLinus Torvalds * in preparation for freeing it (sometimes, rarely, buffers are removed from 11881da177e4SLinus Torvalds * a page but it ends up not being freed, and buffers may later be reattached). 11891da177e4SLinus Torvalds */ 11901da177e4SLinus Torvalds void __brelse(struct buffer_head * buf) 11911da177e4SLinus Torvalds { 11921da177e4SLinus Torvalds if (atomic_read(&buf->b_count)) { 11931da177e4SLinus Torvalds put_bh(buf); 11941da177e4SLinus Torvalds return; 11951da177e4SLinus Torvalds } 11965c752ad9SArjan van de Ven WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); 11971da177e4SLinus Torvalds } 11981fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__brelse); 11991da177e4SLinus Torvalds 12001da177e4SLinus Torvalds /* 12011da177e4SLinus Torvalds * bforget() is like brelse(), except it discards any 12021da177e4SLinus Torvalds * potentially dirty data. 12031da177e4SLinus Torvalds */ 12041da177e4SLinus Torvalds void __bforget(struct buffer_head *bh) 12051da177e4SLinus Torvalds { 12061da177e4SLinus Torvalds clear_buffer_dirty(bh); 1207535ee2fbSJan Kara if (bh->b_assoc_map) { 12081da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 12091da177e4SLinus Torvalds 12101da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 12111da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 121258ff407bSJan Kara bh->b_assoc_map = NULL; 12131da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 12141da177e4SLinus Torvalds } 12151da177e4SLinus Torvalds __brelse(bh); 12161da177e4SLinus Torvalds } 12171fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__bforget); 12181da177e4SLinus Torvalds 12191da177e4SLinus Torvalds static struct buffer_head *__bread_slow(struct buffer_head *bh) 12201da177e4SLinus Torvalds { 12211da177e4SLinus Torvalds lock_buffer(bh); 12221da177e4SLinus Torvalds if (buffer_uptodate(bh)) { 12231da177e4SLinus Torvalds unlock_buffer(bh); 12241da177e4SLinus Torvalds return bh; 12251da177e4SLinus Torvalds } else { 12261da177e4SLinus Torvalds get_bh(bh); 12271da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_sync; 12281da177e4SLinus Torvalds submit_bh(READ, bh); 12291da177e4SLinus Torvalds wait_on_buffer(bh); 12301da177e4SLinus Torvalds if (buffer_uptodate(bh)) 12311da177e4SLinus Torvalds return bh; 12321da177e4SLinus Torvalds } 12331da177e4SLinus Torvalds brelse(bh); 12341da177e4SLinus Torvalds return NULL; 12351da177e4SLinus Torvalds } 12361da177e4SLinus Torvalds 12371da177e4SLinus Torvalds /* 12381da177e4SLinus Torvalds * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). 12391da177e4SLinus Torvalds * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their 12401da177e4SLinus Torvalds * refcount elevated by one when they're in an LRU. A buffer can only appear 12411da177e4SLinus Torvalds * once in a particular CPU's LRU. A single buffer can be present in multiple 12421da177e4SLinus Torvalds * CPU's LRUs at the same time. 12431da177e4SLinus Torvalds * 12441da177e4SLinus Torvalds * This is a transparent caching front-end to sb_bread(), sb_getblk() and 12451da177e4SLinus Torvalds * sb_find_get_block(). 12461da177e4SLinus Torvalds * 12471da177e4SLinus Torvalds * The LRUs themselves only need locking against invalidate_bh_lrus. We use 12481da177e4SLinus Torvalds * a local interrupt disable for that. 12491da177e4SLinus Torvalds */ 12501da177e4SLinus Torvalds 125186cf78d7SSebastien Buisson #define BH_LRU_SIZE 16 12521da177e4SLinus Torvalds 12531da177e4SLinus Torvalds struct bh_lru { 12541da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12551da177e4SLinus Torvalds }; 12561da177e4SLinus Torvalds 12571da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; 12581da177e4SLinus Torvalds 12591da177e4SLinus Torvalds #ifdef CONFIG_SMP 12601da177e4SLinus Torvalds #define bh_lru_lock() local_irq_disable() 12611da177e4SLinus Torvalds #define bh_lru_unlock() local_irq_enable() 12621da177e4SLinus Torvalds #else 12631da177e4SLinus Torvalds #define bh_lru_lock() preempt_disable() 12641da177e4SLinus Torvalds #define bh_lru_unlock() preempt_enable() 12651da177e4SLinus Torvalds #endif 12661da177e4SLinus Torvalds 12671da177e4SLinus Torvalds static inline void check_irqs_on(void) 12681da177e4SLinus Torvalds { 12691da177e4SLinus Torvalds #ifdef irqs_disabled 12701da177e4SLinus Torvalds BUG_ON(irqs_disabled()); 12711da177e4SLinus Torvalds #endif 12721da177e4SLinus Torvalds } 12731da177e4SLinus Torvalds 12741da177e4SLinus Torvalds /* 12751da177e4SLinus Torvalds * The LRU management algorithm is dopey-but-simple. Sorry. 12761da177e4SLinus Torvalds */ 12771da177e4SLinus Torvalds static void bh_lru_install(struct buffer_head *bh) 12781da177e4SLinus Torvalds { 12791da177e4SLinus Torvalds struct buffer_head *evictee = NULL; 12801da177e4SLinus Torvalds 12811da177e4SLinus Torvalds check_irqs_on(); 12821da177e4SLinus Torvalds bh_lru_lock(); 1283c7b92516SChristoph Lameter if (__this_cpu_read(bh_lrus.bhs[0]) != bh) { 12841da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12851da177e4SLinus Torvalds int in; 12861da177e4SLinus Torvalds int out = 0; 12871da177e4SLinus Torvalds 12881da177e4SLinus Torvalds get_bh(bh); 12891da177e4SLinus Torvalds bhs[out++] = bh; 12901da177e4SLinus Torvalds for (in = 0; in < BH_LRU_SIZE; in++) { 1291c7b92516SChristoph Lameter struct buffer_head *bh2 = 1292c7b92516SChristoph Lameter __this_cpu_read(bh_lrus.bhs[in]); 12931da177e4SLinus Torvalds 12941da177e4SLinus Torvalds if (bh2 == bh) { 12951da177e4SLinus Torvalds __brelse(bh2); 12961da177e4SLinus Torvalds } else { 12971da177e4SLinus Torvalds if (out >= BH_LRU_SIZE) { 12981da177e4SLinus Torvalds BUG_ON(evictee != NULL); 12991da177e4SLinus Torvalds evictee = bh2; 13001da177e4SLinus Torvalds } else { 13011da177e4SLinus Torvalds bhs[out++] = bh2; 13021da177e4SLinus Torvalds } 13031da177e4SLinus Torvalds } 13041da177e4SLinus Torvalds } 13051da177e4SLinus Torvalds while (out < BH_LRU_SIZE) 13061da177e4SLinus Torvalds bhs[out++] = NULL; 1307ca6673b0SChristoph Lameter memcpy(this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs)); 13081da177e4SLinus Torvalds } 13091da177e4SLinus Torvalds bh_lru_unlock(); 13101da177e4SLinus Torvalds 13111da177e4SLinus Torvalds if (evictee) 13121da177e4SLinus Torvalds __brelse(evictee); 13131da177e4SLinus Torvalds } 13141da177e4SLinus Torvalds 13151da177e4SLinus Torvalds /* 13161da177e4SLinus Torvalds * Look up the bh in this cpu's LRU. If it's there, move it to the head. 13171da177e4SLinus Torvalds */ 1318858119e1SArjan van de Ven static struct buffer_head * 13193991d3bdSTomasz Kvarsin lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) 13201da177e4SLinus Torvalds { 13211da177e4SLinus Torvalds struct buffer_head *ret = NULL; 13223991d3bdSTomasz Kvarsin unsigned int i; 13231da177e4SLinus Torvalds 13241da177e4SLinus Torvalds check_irqs_on(); 13251da177e4SLinus Torvalds bh_lru_lock(); 13261da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 1327c7b92516SChristoph Lameter struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); 13281da177e4SLinus Torvalds 13299470dd5dSZach Brown if (bh && bh->b_blocknr == block && bh->b_bdev == bdev && 13309470dd5dSZach Brown bh->b_size == size) { 13311da177e4SLinus Torvalds if (i) { 13321da177e4SLinus Torvalds while (i) { 1333c7b92516SChristoph Lameter __this_cpu_write(bh_lrus.bhs[i], 1334c7b92516SChristoph Lameter __this_cpu_read(bh_lrus.bhs[i - 1])); 13351da177e4SLinus Torvalds i--; 13361da177e4SLinus Torvalds } 1337c7b92516SChristoph Lameter __this_cpu_write(bh_lrus.bhs[0], bh); 13381da177e4SLinus Torvalds } 13391da177e4SLinus Torvalds get_bh(bh); 13401da177e4SLinus Torvalds ret = bh; 13411da177e4SLinus Torvalds break; 13421da177e4SLinus Torvalds } 13431da177e4SLinus Torvalds } 13441da177e4SLinus Torvalds bh_lru_unlock(); 13451da177e4SLinus Torvalds return ret; 13461da177e4SLinus Torvalds } 13471da177e4SLinus Torvalds 13481da177e4SLinus Torvalds /* 13491da177e4SLinus Torvalds * Perform a pagecache lookup for the matching buffer. If it's there, refresh 13501da177e4SLinus Torvalds * it in the LRU and mark it as accessed. If it is not present then return 13511da177e4SLinus Torvalds * NULL 13521da177e4SLinus Torvalds */ 13531da177e4SLinus Torvalds struct buffer_head * 13543991d3bdSTomasz Kvarsin __find_get_block(struct block_device *bdev, sector_t block, unsigned size) 13551da177e4SLinus Torvalds { 13561da177e4SLinus Torvalds struct buffer_head *bh = lookup_bh_lru(bdev, block, size); 13571da177e4SLinus Torvalds 13581da177e4SLinus Torvalds if (bh == NULL) { 13592457aec6SMel Gorman /* __find_get_block_slow will mark the page accessed */ 1360385fd4c5SCoywolf Qi Hunt bh = __find_get_block_slow(bdev, block); 13611da177e4SLinus Torvalds if (bh) 13621da177e4SLinus Torvalds bh_lru_install(bh); 13632457aec6SMel Gorman } else 13641da177e4SLinus Torvalds touch_buffer(bh); 13652457aec6SMel Gorman 13661da177e4SLinus Torvalds return bh; 13671da177e4SLinus Torvalds } 13681da177e4SLinus Torvalds EXPORT_SYMBOL(__find_get_block); 13691da177e4SLinus Torvalds 13701da177e4SLinus Torvalds /* 13713b5e6454SGioh Kim * __getblk_gfp() will locate (and, if necessary, create) the buffer_head 13721da177e4SLinus Torvalds * which corresponds to the passed block_device, block and size. The 13731da177e4SLinus Torvalds * returned buffer has its reference count incremented. 13741da177e4SLinus Torvalds * 13753b5e6454SGioh Kim * __getblk_gfp() will lock up the machine if grow_dev_page's 13763b5e6454SGioh Kim * try_to_free_buffers() attempt is failing. FIXME, perhaps? 13771da177e4SLinus Torvalds */ 13781da177e4SLinus Torvalds struct buffer_head * 13793b5e6454SGioh Kim __getblk_gfp(struct block_device *bdev, sector_t block, 13803b5e6454SGioh Kim unsigned size, gfp_t gfp) 13811da177e4SLinus Torvalds { 13821da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, block, size); 13831da177e4SLinus Torvalds 13841da177e4SLinus Torvalds might_sleep(); 13851da177e4SLinus Torvalds if (bh == NULL) 13863b5e6454SGioh Kim bh = __getblk_slow(bdev, block, size, gfp); 13871da177e4SLinus Torvalds return bh; 13881da177e4SLinus Torvalds } 13893b5e6454SGioh Kim EXPORT_SYMBOL(__getblk_gfp); 13901da177e4SLinus Torvalds 13911da177e4SLinus Torvalds /* 13921da177e4SLinus Torvalds * Do async read-ahead on a buffer.. 13931da177e4SLinus Torvalds */ 13943991d3bdSTomasz Kvarsin void __breadahead(struct block_device *bdev, sector_t block, unsigned size) 13951da177e4SLinus Torvalds { 13961da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 1397a3e713b5SAndrew Morton if (likely(bh)) { 13981da177e4SLinus Torvalds ll_rw_block(READA, 1, &bh); 13991da177e4SLinus Torvalds brelse(bh); 14001da177e4SLinus Torvalds } 1401a3e713b5SAndrew Morton } 14021da177e4SLinus Torvalds EXPORT_SYMBOL(__breadahead); 14031da177e4SLinus Torvalds 14041da177e4SLinus Torvalds /** 14053b5e6454SGioh Kim * __bread_gfp() - reads a specified block and returns the bh 140667be2dd1SMartin Waitz * @bdev: the block_device to read from 14071da177e4SLinus Torvalds * @block: number of block 14081da177e4SLinus Torvalds * @size: size (in bytes) to read 14093b5e6454SGioh Kim * @gfp: page allocation flag 14101da177e4SLinus Torvalds * 14111da177e4SLinus Torvalds * Reads a specified block, and returns buffer head that contains it. 14123b5e6454SGioh Kim * The page cache can be allocated from non-movable area 14133b5e6454SGioh Kim * not to prevent page migration if you set gfp to zero. 14141da177e4SLinus Torvalds * It returns NULL if the block was unreadable. 14151da177e4SLinus Torvalds */ 14161da177e4SLinus Torvalds struct buffer_head * 14173b5e6454SGioh Kim __bread_gfp(struct block_device *bdev, sector_t block, 14183b5e6454SGioh Kim unsigned size, gfp_t gfp) 14191da177e4SLinus Torvalds { 14203b5e6454SGioh Kim struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp); 14211da177e4SLinus Torvalds 1422a3e713b5SAndrew Morton if (likely(bh) && !buffer_uptodate(bh)) 14231da177e4SLinus Torvalds bh = __bread_slow(bh); 14241da177e4SLinus Torvalds return bh; 14251da177e4SLinus Torvalds } 14263b5e6454SGioh Kim EXPORT_SYMBOL(__bread_gfp); 14271da177e4SLinus Torvalds 14281da177e4SLinus Torvalds /* 14291da177e4SLinus Torvalds * invalidate_bh_lrus() is called rarely - but not only at unmount. 14301da177e4SLinus Torvalds * This doesn't race because it runs in each cpu either in irq 14311da177e4SLinus Torvalds * or with preempt disabled. 14321da177e4SLinus Torvalds */ 14331da177e4SLinus Torvalds static void invalidate_bh_lru(void *arg) 14341da177e4SLinus Torvalds { 14351da177e4SLinus Torvalds struct bh_lru *b = &get_cpu_var(bh_lrus); 14361da177e4SLinus Torvalds int i; 14371da177e4SLinus Torvalds 14381da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 14391da177e4SLinus Torvalds brelse(b->bhs[i]); 14401da177e4SLinus Torvalds b->bhs[i] = NULL; 14411da177e4SLinus Torvalds } 14421da177e4SLinus Torvalds put_cpu_var(bh_lrus); 14431da177e4SLinus Torvalds } 14441da177e4SLinus Torvalds 144542be35d0SGilad Ben-Yossef static bool has_bh_in_lru(int cpu, void *dummy) 144642be35d0SGilad Ben-Yossef { 144742be35d0SGilad Ben-Yossef struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); 144842be35d0SGilad Ben-Yossef int i; 144942be35d0SGilad Ben-Yossef 145042be35d0SGilad Ben-Yossef for (i = 0; i < BH_LRU_SIZE; i++) { 145142be35d0SGilad Ben-Yossef if (b->bhs[i]) 145242be35d0SGilad Ben-Yossef return 1; 145342be35d0SGilad Ben-Yossef } 145442be35d0SGilad Ben-Yossef 145542be35d0SGilad Ben-Yossef return 0; 145642be35d0SGilad Ben-Yossef } 145742be35d0SGilad Ben-Yossef 1458f9a14399SPeter Zijlstra void invalidate_bh_lrus(void) 14591da177e4SLinus Torvalds { 146042be35d0SGilad Ben-Yossef on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); 14611da177e4SLinus Torvalds } 14629db5579bSNick Piggin EXPORT_SYMBOL_GPL(invalidate_bh_lrus); 14631da177e4SLinus Torvalds 14641da177e4SLinus Torvalds void set_bh_page(struct buffer_head *bh, 14651da177e4SLinus Torvalds struct page *page, unsigned long offset) 14661da177e4SLinus Torvalds { 14671da177e4SLinus Torvalds bh->b_page = page; 1468e827f923SEric Sesterhenn BUG_ON(offset >= PAGE_SIZE); 14691da177e4SLinus Torvalds if (PageHighMem(page)) 14701da177e4SLinus Torvalds /* 14711da177e4SLinus Torvalds * This catches illegal uses and preserves the offset: 14721da177e4SLinus Torvalds */ 14731da177e4SLinus Torvalds bh->b_data = (char *)(0 + offset); 14741da177e4SLinus Torvalds else 14751da177e4SLinus Torvalds bh->b_data = page_address(page) + offset; 14761da177e4SLinus Torvalds } 14771da177e4SLinus Torvalds EXPORT_SYMBOL(set_bh_page); 14781da177e4SLinus Torvalds 14791da177e4SLinus Torvalds /* 14801da177e4SLinus Torvalds * Called when truncating a buffer on a page completely. 14811da177e4SLinus Torvalds */ 1482e7470ee8SMel Gorman 1483e7470ee8SMel Gorman /* Bits that are cleared during an invalidate */ 1484e7470ee8SMel Gorman #define BUFFER_FLAGS_DISCARD \ 1485e7470ee8SMel Gorman (1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \ 1486e7470ee8SMel Gorman 1 << BH_Delay | 1 << BH_Unwritten) 1487e7470ee8SMel Gorman 1488858119e1SArjan van de Ven static void discard_buffer(struct buffer_head * bh) 14891da177e4SLinus Torvalds { 1490e7470ee8SMel Gorman unsigned long b_state, b_state_old; 1491e7470ee8SMel Gorman 14921da177e4SLinus Torvalds lock_buffer(bh); 14931da177e4SLinus Torvalds clear_buffer_dirty(bh); 14941da177e4SLinus Torvalds bh->b_bdev = NULL; 1495e7470ee8SMel Gorman b_state = bh->b_state; 1496e7470ee8SMel Gorman for (;;) { 1497e7470ee8SMel Gorman b_state_old = cmpxchg(&bh->b_state, b_state, 1498e7470ee8SMel Gorman (b_state & ~BUFFER_FLAGS_DISCARD)); 1499e7470ee8SMel Gorman if (b_state_old == b_state) 1500e7470ee8SMel Gorman break; 1501e7470ee8SMel Gorman b_state = b_state_old; 1502e7470ee8SMel Gorman } 15031da177e4SLinus Torvalds unlock_buffer(bh); 15041da177e4SLinus Torvalds } 15051da177e4SLinus Torvalds 15061da177e4SLinus Torvalds /** 1507814e1d25SWang Sheng-Hui * block_invalidatepage - invalidate part or all of a buffer-backed page 15081da177e4SLinus Torvalds * 15091da177e4SLinus Torvalds * @page: the page which is affected 1510d47992f8SLukas Czerner * @offset: start of the range to invalidate 1511d47992f8SLukas Czerner * @length: length of the range to invalidate 15121da177e4SLinus Torvalds * 15131da177e4SLinus Torvalds * block_invalidatepage() is called when all or part of the page has become 15141da177e4SLinus Torvalds * invalidated by a truncate operation. 15151da177e4SLinus Torvalds * 15161da177e4SLinus Torvalds * block_invalidatepage() does not have to release all buffers, but it must 15171da177e4SLinus Torvalds * ensure that no dirty buffer is left outside @offset and that no I/O 15181da177e4SLinus Torvalds * is underway against any of the blocks which are outside the truncation 15191da177e4SLinus Torvalds * point. Because the caller is about to free (and possibly reuse) those 15201da177e4SLinus Torvalds * blocks on-disk. 15211da177e4SLinus Torvalds */ 1522d47992f8SLukas Czerner void block_invalidatepage(struct page *page, unsigned int offset, 1523d47992f8SLukas Czerner unsigned int length) 15241da177e4SLinus Torvalds { 15251da177e4SLinus Torvalds struct buffer_head *head, *bh, *next; 15261da177e4SLinus Torvalds unsigned int curr_off = 0; 1527d47992f8SLukas Czerner unsigned int stop = length + offset; 15281da177e4SLinus Torvalds 15291da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 15301da177e4SLinus Torvalds if (!page_has_buffers(page)) 15311da177e4SLinus Torvalds goto out; 15321da177e4SLinus Torvalds 1533d47992f8SLukas Czerner /* 1534d47992f8SLukas Czerner * Check for overflow 1535d47992f8SLukas Czerner */ 153609cbfeafSKirill A. Shutemov BUG_ON(stop > PAGE_SIZE || stop < length); 1537d47992f8SLukas Czerner 15381da177e4SLinus Torvalds head = page_buffers(page); 15391da177e4SLinus Torvalds bh = head; 15401da177e4SLinus Torvalds do { 15411da177e4SLinus Torvalds unsigned int next_off = curr_off + bh->b_size; 15421da177e4SLinus Torvalds next = bh->b_this_page; 15431da177e4SLinus Torvalds 15441da177e4SLinus Torvalds /* 1545d47992f8SLukas Czerner * Are we still fully in range ? 1546d47992f8SLukas Czerner */ 1547d47992f8SLukas Czerner if (next_off > stop) 1548d47992f8SLukas Czerner goto out; 1549d47992f8SLukas Czerner 1550d47992f8SLukas Czerner /* 15511da177e4SLinus Torvalds * is this block fully invalidated? 15521da177e4SLinus Torvalds */ 15531da177e4SLinus Torvalds if (offset <= curr_off) 15541da177e4SLinus Torvalds discard_buffer(bh); 15551da177e4SLinus Torvalds curr_off = next_off; 15561da177e4SLinus Torvalds bh = next; 15571da177e4SLinus Torvalds } while (bh != head); 15581da177e4SLinus Torvalds 15591da177e4SLinus Torvalds /* 15601da177e4SLinus Torvalds * We release buffers only if the entire page is being invalidated. 15611da177e4SLinus Torvalds * The get_block cached value has been unconditionally invalidated, 15621da177e4SLinus Torvalds * so real IO is not possible anymore. 15631da177e4SLinus Torvalds */ 15641da177e4SLinus Torvalds if (offset == 0) 15652ff28e22SNeilBrown try_to_release_page(page, 0); 15661da177e4SLinus Torvalds out: 15672ff28e22SNeilBrown return; 15681da177e4SLinus Torvalds } 15691da177e4SLinus Torvalds EXPORT_SYMBOL(block_invalidatepage); 15701da177e4SLinus Torvalds 1571d47992f8SLukas Czerner 15721da177e4SLinus Torvalds /* 15731da177e4SLinus Torvalds * We attach and possibly dirty the buffers atomically wrt 15741da177e4SLinus Torvalds * __set_page_dirty_buffers() via private_lock. try_to_free_buffers 15751da177e4SLinus Torvalds * is already excluded via the page lock. 15761da177e4SLinus Torvalds */ 15771da177e4SLinus Torvalds void create_empty_buffers(struct page *page, 15781da177e4SLinus Torvalds unsigned long blocksize, unsigned long b_state) 15791da177e4SLinus Torvalds { 15801da177e4SLinus Torvalds struct buffer_head *bh, *head, *tail; 15811da177e4SLinus Torvalds 15821da177e4SLinus Torvalds head = alloc_page_buffers(page, blocksize, 1); 15831da177e4SLinus Torvalds bh = head; 15841da177e4SLinus Torvalds do { 15851da177e4SLinus Torvalds bh->b_state |= b_state; 15861da177e4SLinus Torvalds tail = bh; 15871da177e4SLinus Torvalds bh = bh->b_this_page; 15881da177e4SLinus Torvalds } while (bh); 15891da177e4SLinus Torvalds tail->b_this_page = head; 15901da177e4SLinus Torvalds 15911da177e4SLinus Torvalds spin_lock(&page->mapping->private_lock); 15921da177e4SLinus Torvalds if (PageUptodate(page) || PageDirty(page)) { 15931da177e4SLinus Torvalds bh = head; 15941da177e4SLinus Torvalds do { 15951da177e4SLinus Torvalds if (PageDirty(page)) 15961da177e4SLinus Torvalds set_buffer_dirty(bh); 15971da177e4SLinus Torvalds if (PageUptodate(page)) 15981da177e4SLinus Torvalds set_buffer_uptodate(bh); 15991da177e4SLinus Torvalds bh = bh->b_this_page; 16001da177e4SLinus Torvalds } while (bh != head); 16011da177e4SLinus Torvalds } 16021da177e4SLinus Torvalds attach_page_buffers(page, head); 16031da177e4SLinus Torvalds spin_unlock(&page->mapping->private_lock); 16041da177e4SLinus Torvalds } 16051da177e4SLinus Torvalds EXPORT_SYMBOL(create_empty_buffers); 16061da177e4SLinus Torvalds 16071da177e4SLinus Torvalds /* 16081da177e4SLinus Torvalds * We are taking a block for data and we don't want any output from any 16091da177e4SLinus Torvalds * buffer-cache aliases starting from return from that function and 16101da177e4SLinus Torvalds * until the moment when something will explicitly mark the buffer 16111da177e4SLinus Torvalds * dirty (hopefully that will not happen until we will free that block ;-) 16121da177e4SLinus Torvalds * We don't even need to mark it not-uptodate - nobody can expect 16131da177e4SLinus Torvalds * anything from a newly allocated buffer anyway. We used to used 16141da177e4SLinus Torvalds * unmap_buffer() for such invalidation, but that was wrong. We definitely 16151da177e4SLinus Torvalds * don't want to mark the alias unmapped, for example - it would confuse 16161da177e4SLinus Torvalds * anyone who might pick it with bread() afterwards... 16171da177e4SLinus Torvalds * 16181da177e4SLinus Torvalds * Also.. Note that bforget() doesn't lock the buffer. So there can 16191da177e4SLinus Torvalds * be writeout I/O going on against recently-freed buffers. We don't 16201da177e4SLinus Torvalds * wait on that I/O in bforget() - it's more efficient to wait on the I/O 16211da177e4SLinus Torvalds * only if we really need to. That happens here. 16221da177e4SLinus Torvalds */ 16231da177e4SLinus Torvalds void unmap_underlying_metadata(struct block_device *bdev, sector_t block) 16241da177e4SLinus Torvalds { 16251da177e4SLinus Torvalds struct buffer_head *old_bh; 16261da177e4SLinus Torvalds 16271da177e4SLinus Torvalds might_sleep(); 16281da177e4SLinus Torvalds 1629385fd4c5SCoywolf Qi Hunt old_bh = __find_get_block_slow(bdev, block); 16301da177e4SLinus Torvalds if (old_bh) { 16311da177e4SLinus Torvalds clear_buffer_dirty(old_bh); 16321da177e4SLinus Torvalds wait_on_buffer(old_bh); 16331da177e4SLinus Torvalds clear_buffer_req(old_bh); 16341da177e4SLinus Torvalds __brelse(old_bh); 16351da177e4SLinus Torvalds } 16361da177e4SLinus Torvalds } 16371da177e4SLinus Torvalds EXPORT_SYMBOL(unmap_underlying_metadata); 16381da177e4SLinus Torvalds 16391da177e4SLinus Torvalds /* 164045bce8f3SLinus Torvalds * Size is a power-of-two in the range 512..PAGE_SIZE, 164145bce8f3SLinus Torvalds * and the case we care about most is PAGE_SIZE. 164245bce8f3SLinus Torvalds * 164345bce8f3SLinus Torvalds * So this *could* possibly be written with those 164445bce8f3SLinus Torvalds * constraints in mind (relevant mostly if some 164545bce8f3SLinus Torvalds * architecture has a slow bit-scan instruction) 164645bce8f3SLinus Torvalds */ 164745bce8f3SLinus Torvalds static inline int block_size_bits(unsigned int blocksize) 164845bce8f3SLinus Torvalds { 164945bce8f3SLinus Torvalds return ilog2(blocksize); 165045bce8f3SLinus Torvalds } 165145bce8f3SLinus Torvalds 165245bce8f3SLinus Torvalds static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state) 165345bce8f3SLinus Torvalds { 165445bce8f3SLinus Torvalds BUG_ON(!PageLocked(page)); 165545bce8f3SLinus Torvalds 165645bce8f3SLinus Torvalds if (!page_has_buffers(page)) 165745bce8f3SLinus Torvalds create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state); 165845bce8f3SLinus Torvalds return page_buffers(page); 165945bce8f3SLinus Torvalds } 166045bce8f3SLinus Torvalds 166145bce8f3SLinus Torvalds /* 16621da177e4SLinus Torvalds * NOTE! All mapped/uptodate combinations are valid: 16631da177e4SLinus Torvalds * 16641da177e4SLinus Torvalds * Mapped Uptodate Meaning 16651da177e4SLinus Torvalds * 16661da177e4SLinus Torvalds * No No "unknown" - must do get_block() 16671da177e4SLinus Torvalds * No Yes "hole" - zero-filled 16681da177e4SLinus Torvalds * Yes No "allocated" - allocated on disk, not read in 16691da177e4SLinus Torvalds * Yes Yes "valid" - allocated and up-to-date in memory. 16701da177e4SLinus Torvalds * 16711da177e4SLinus Torvalds * "Dirty" is valid only with the last case (mapped+uptodate). 16721da177e4SLinus Torvalds */ 16731da177e4SLinus Torvalds 16741da177e4SLinus Torvalds /* 16751da177e4SLinus Torvalds * While block_write_full_page is writing back the dirty buffers under 16761da177e4SLinus Torvalds * the page lock, whoever dirtied the buffers may decide to clean them 16771da177e4SLinus Torvalds * again at any time. We handle that by only looking at the buffer 16781da177e4SLinus Torvalds * state inside lock_buffer(). 16791da177e4SLinus Torvalds * 16801da177e4SLinus Torvalds * If block_write_full_page() is called for regular writeback 16811da177e4SLinus Torvalds * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a 16821da177e4SLinus Torvalds * locked buffer. This only can happen if someone has written the buffer 16831da177e4SLinus Torvalds * directly, with submit_bh(). At the address_space level PageWriteback 16841da177e4SLinus Torvalds * prevents this contention from occurring. 16856e34eeddSTheodore Ts'o * 16866e34eeddSTheodore Ts'o * If block_write_full_page() is called with wbc->sync_mode == 1687721a9602SJens Axboe * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this 1688721a9602SJens Axboe * causes the writes to be flagged as synchronous writes. 16891da177e4SLinus Torvalds */ 1690*b4bba389SBenjamin Marzinski int __block_write_full_page(struct inode *inode, struct page *page, 169135c80d5fSChris Mason get_block_t *get_block, struct writeback_control *wbc, 169235c80d5fSChris Mason bh_end_io_t *handler) 16931da177e4SLinus Torvalds { 16941da177e4SLinus Torvalds int err; 16951da177e4SLinus Torvalds sector_t block; 16961da177e4SLinus Torvalds sector_t last_block; 1697f0fbd5fcSAndrew Morton struct buffer_head *bh, *head; 169845bce8f3SLinus Torvalds unsigned int blocksize, bbits; 16991da177e4SLinus Torvalds int nr_underway = 0; 1700bafc0dbaSTejun Heo int write_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE); 17011da177e4SLinus Torvalds 170245bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 17031da177e4SLinus Torvalds (1 << BH_Dirty)|(1 << BH_Uptodate)); 17041da177e4SLinus Torvalds 17051da177e4SLinus Torvalds /* 17061da177e4SLinus Torvalds * Be very careful. We have no exclusion from __set_page_dirty_buffers 17071da177e4SLinus Torvalds * here, and the (potentially unmapped) buffers may become dirty at 17081da177e4SLinus Torvalds * any time. If a buffer becomes dirty here after we've inspected it 17091da177e4SLinus Torvalds * then we just miss that fact, and the page stays dirty. 17101da177e4SLinus Torvalds * 17111da177e4SLinus Torvalds * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; 17121da177e4SLinus Torvalds * handle that here by just cleaning them. 17131da177e4SLinus Torvalds */ 17141da177e4SLinus Torvalds 17151da177e4SLinus Torvalds bh = head; 171645bce8f3SLinus Torvalds blocksize = bh->b_size; 171745bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 171845bce8f3SLinus Torvalds 171909cbfeafSKirill A. Shutemov block = (sector_t)page->index << (PAGE_SHIFT - bbits); 172045bce8f3SLinus Torvalds last_block = (i_size_read(inode) - 1) >> bbits; 17211da177e4SLinus Torvalds 17221da177e4SLinus Torvalds /* 17231da177e4SLinus Torvalds * Get all the dirty buffers mapped to disk addresses and 17241da177e4SLinus Torvalds * handle any aliases from the underlying blockdev's mapping. 17251da177e4SLinus Torvalds */ 17261da177e4SLinus Torvalds do { 17271da177e4SLinus Torvalds if (block > last_block) { 17281da177e4SLinus Torvalds /* 17291da177e4SLinus Torvalds * mapped buffers outside i_size will occur, because 17301da177e4SLinus Torvalds * this page can be outside i_size when there is a 17311da177e4SLinus Torvalds * truncate in progress. 17321da177e4SLinus Torvalds */ 17331da177e4SLinus Torvalds /* 17341da177e4SLinus Torvalds * The buffer was zeroed by block_write_full_page() 17351da177e4SLinus Torvalds */ 17361da177e4SLinus Torvalds clear_buffer_dirty(bh); 17371da177e4SLinus Torvalds set_buffer_uptodate(bh); 173829a814d2SAlex Tomas } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && 173929a814d2SAlex Tomas buffer_dirty(bh)) { 1740b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 17411da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 17421da177e4SLinus Torvalds if (err) 17431da177e4SLinus Torvalds goto recover; 174429a814d2SAlex Tomas clear_buffer_delay(bh); 17451da177e4SLinus Torvalds if (buffer_new(bh)) { 17461da177e4SLinus Torvalds /* blockdev mappings never come here */ 17471da177e4SLinus Torvalds clear_buffer_new(bh); 17481da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 17491da177e4SLinus Torvalds bh->b_blocknr); 17501da177e4SLinus Torvalds } 17511da177e4SLinus Torvalds } 17521da177e4SLinus Torvalds bh = bh->b_this_page; 17531da177e4SLinus Torvalds block++; 17541da177e4SLinus Torvalds } while (bh != head); 17551da177e4SLinus Torvalds 17561da177e4SLinus Torvalds do { 17571da177e4SLinus Torvalds if (!buffer_mapped(bh)) 17581da177e4SLinus Torvalds continue; 17591da177e4SLinus Torvalds /* 17601da177e4SLinus Torvalds * If it's a fully non-blocking write attempt and we cannot 17611da177e4SLinus Torvalds * lock the buffer then redirty the page. Note that this can 17625b0830cbSJens Axboe * potentially cause a busy-wait loop from writeback threads 17635b0830cbSJens Axboe * and kswapd activity, but those code paths have their own 17645b0830cbSJens Axboe * higher-level throttling. 17651da177e4SLinus Torvalds */ 17661b430beeSWu Fengguang if (wbc->sync_mode != WB_SYNC_NONE) { 17671da177e4SLinus Torvalds lock_buffer(bh); 1768ca5de404SNick Piggin } else if (!trylock_buffer(bh)) { 17691da177e4SLinus Torvalds redirty_page_for_writepage(wbc, page); 17701da177e4SLinus Torvalds continue; 17711da177e4SLinus Torvalds } 17721da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 177335c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 17741da177e4SLinus Torvalds } else { 17751da177e4SLinus Torvalds unlock_buffer(bh); 17761da177e4SLinus Torvalds } 17771da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17781da177e4SLinus Torvalds 17791da177e4SLinus Torvalds /* 17801da177e4SLinus Torvalds * The page and its buffers are protected by PageWriteback(), so we can 17811da177e4SLinus Torvalds * drop the bh refcounts early. 17821da177e4SLinus Torvalds */ 17831da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17841da177e4SLinus Torvalds set_page_writeback(page); 17851da177e4SLinus Torvalds 17861da177e4SLinus Torvalds do { 17871da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17881da177e4SLinus Torvalds if (buffer_async_write(bh)) { 1789b16b1debSTejun Heo submit_bh_wbc(write_op, bh, 0, wbc); 17901da177e4SLinus Torvalds nr_underway++; 1791ad576e63SNick Piggin } 17921da177e4SLinus Torvalds bh = next; 17931da177e4SLinus Torvalds } while (bh != head); 179405937baaSAndrew Morton unlock_page(page); 17951da177e4SLinus Torvalds 17961da177e4SLinus Torvalds err = 0; 17971da177e4SLinus Torvalds done: 17981da177e4SLinus Torvalds if (nr_underway == 0) { 17991da177e4SLinus Torvalds /* 18001da177e4SLinus Torvalds * The page was marked dirty, but the buffers were 18011da177e4SLinus Torvalds * clean. Someone wrote them back by hand with 18021da177e4SLinus Torvalds * ll_rw_block/submit_bh. A rare case. 18031da177e4SLinus Torvalds */ 18041da177e4SLinus Torvalds end_page_writeback(page); 18053d67f2d7SNick Piggin 18061da177e4SLinus Torvalds /* 18071da177e4SLinus Torvalds * The page and buffer_heads can be released at any time from 18081da177e4SLinus Torvalds * here on. 18091da177e4SLinus Torvalds */ 18101da177e4SLinus Torvalds } 18111da177e4SLinus Torvalds return err; 18121da177e4SLinus Torvalds 18131da177e4SLinus Torvalds recover: 18141da177e4SLinus Torvalds /* 18151da177e4SLinus Torvalds * ENOSPC, or some other error. We may already have added some 18161da177e4SLinus Torvalds * blocks to the file, so we need to write these out to avoid 18171da177e4SLinus Torvalds * exposing stale data. 18181da177e4SLinus Torvalds * The page is currently locked and not marked for writeback 18191da177e4SLinus Torvalds */ 18201da177e4SLinus Torvalds bh = head; 18211da177e4SLinus Torvalds /* Recovery: lock and submit the mapped buffers */ 18221da177e4SLinus Torvalds do { 182329a814d2SAlex Tomas if (buffer_mapped(bh) && buffer_dirty(bh) && 182429a814d2SAlex Tomas !buffer_delay(bh)) { 18251da177e4SLinus Torvalds lock_buffer(bh); 182635c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 18271da177e4SLinus Torvalds } else { 18281da177e4SLinus Torvalds /* 18291da177e4SLinus Torvalds * The buffer may have been set dirty during 18301da177e4SLinus Torvalds * attachment to a dirty page. 18311da177e4SLinus Torvalds */ 18321da177e4SLinus Torvalds clear_buffer_dirty(bh); 18331da177e4SLinus Torvalds } 18341da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 18351da177e4SLinus Torvalds SetPageError(page); 18361da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 18377e4c3690SAndrew Morton mapping_set_error(page->mapping, err); 18381da177e4SLinus Torvalds set_page_writeback(page); 18391da177e4SLinus Torvalds do { 18401da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 18411da177e4SLinus Torvalds if (buffer_async_write(bh)) { 18421da177e4SLinus Torvalds clear_buffer_dirty(bh); 1843b16b1debSTejun Heo submit_bh_wbc(write_op, bh, 0, wbc); 18441da177e4SLinus Torvalds nr_underway++; 1845ad576e63SNick Piggin } 18461da177e4SLinus Torvalds bh = next; 18471da177e4SLinus Torvalds } while (bh != head); 1848ffda9d30SNick Piggin unlock_page(page); 18491da177e4SLinus Torvalds goto done; 18501da177e4SLinus Torvalds } 1851*b4bba389SBenjamin Marzinski EXPORT_SYMBOL(__block_write_full_page); 18521da177e4SLinus Torvalds 1853afddba49SNick Piggin /* 1854afddba49SNick Piggin * If a page has any new buffers, zero them out here, and mark them uptodate 1855afddba49SNick Piggin * and dirty so they'll be written out (in order to prevent uninitialised 1856afddba49SNick Piggin * block data from leaking). And clear the new bit. 1857afddba49SNick Piggin */ 1858afddba49SNick Piggin void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) 1859afddba49SNick Piggin { 1860afddba49SNick Piggin unsigned int block_start, block_end; 1861afddba49SNick Piggin struct buffer_head *head, *bh; 1862afddba49SNick Piggin 1863afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1864afddba49SNick Piggin if (!page_has_buffers(page)) 1865afddba49SNick Piggin return; 1866afddba49SNick Piggin 1867afddba49SNick Piggin bh = head = page_buffers(page); 1868afddba49SNick Piggin block_start = 0; 1869afddba49SNick Piggin do { 1870afddba49SNick Piggin block_end = block_start + bh->b_size; 1871afddba49SNick Piggin 1872afddba49SNick Piggin if (buffer_new(bh)) { 1873afddba49SNick Piggin if (block_end > from && block_start < to) { 1874afddba49SNick Piggin if (!PageUptodate(page)) { 1875afddba49SNick Piggin unsigned start, size; 1876afddba49SNick Piggin 1877afddba49SNick Piggin start = max(from, block_start); 1878afddba49SNick Piggin size = min(to, block_end) - start; 1879afddba49SNick Piggin 1880eebd2aa3SChristoph Lameter zero_user(page, start, size); 1881afddba49SNick Piggin set_buffer_uptodate(bh); 1882afddba49SNick Piggin } 1883afddba49SNick Piggin 1884afddba49SNick Piggin clear_buffer_new(bh); 1885afddba49SNick Piggin mark_buffer_dirty(bh); 1886afddba49SNick Piggin } 1887afddba49SNick Piggin } 1888afddba49SNick Piggin 1889afddba49SNick Piggin block_start = block_end; 1890afddba49SNick Piggin bh = bh->b_this_page; 1891afddba49SNick Piggin } while (bh != head); 1892afddba49SNick Piggin } 1893afddba49SNick Piggin EXPORT_SYMBOL(page_zero_new_buffers); 1894afddba49SNick Piggin 1895ebdec241SChristoph Hellwig int __block_write_begin(struct page *page, loff_t pos, unsigned len, 18966e1db88dSChristoph Hellwig get_block_t *get_block) 18971da177e4SLinus Torvalds { 189809cbfeafSKirill A. Shutemov unsigned from = pos & (PAGE_SIZE - 1); 1899ebdec241SChristoph Hellwig unsigned to = from + len; 19006e1db88dSChristoph Hellwig struct inode *inode = page->mapping->host; 19011da177e4SLinus Torvalds unsigned block_start, block_end; 19021da177e4SLinus Torvalds sector_t block; 19031da177e4SLinus Torvalds int err = 0; 19041da177e4SLinus Torvalds unsigned blocksize, bbits; 19051da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 19061da177e4SLinus Torvalds 19071da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 190809cbfeafSKirill A. Shutemov BUG_ON(from > PAGE_SIZE); 190909cbfeafSKirill A. Shutemov BUG_ON(to > PAGE_SIZE); 19101da177e4SLinus Torvalds BUG_ON(from > to); 19111da177e4SLinus Torvalds 191245bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 191345bce8f3SLinus Torvalds blocksize = head->b_size; 191445bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 19151da177e4SLinus Torvalds 191609cbfeafSKirill A. Shutemov block = (sector_t)page->index << (PAGE_SHIFT - bbits); 19171da177e4SLinus Torvalds 19181da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 19191da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 19201da177e4SLinus Torvalds block_end = block_start + blocksize; 19211da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19221da177e4SLinus Torvalds if (PageUptodate(page)) { 19231da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19241da177e4SLinus Torvalds set_buffer_uptodate(bh); 19251da177e4SLinus Torvalds } 19261da177e4SLinus Torvalds continue; 19271da177e4SLinus Torvalds } 19281da177e4SLinus Torvalds if (buffer_new(bh)) 19291da177e4SLinus Torvalds clear_buffer_new(bh); 19301da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 1931b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 19321da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 19331da177e4SLinus Torvalds if (err) 1934f3ddbdc6SNick Piggin break; 19351da177e4SLinus Torvalds if (buffer_new(bh)) { 19361da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 19371da177e4SLinus Torvalds bh->b_blocknr); 19381da177e4SLinus Torvalds if (PageUptodate(page)) { 1939637aff46SNick Piggin clear_buffer_new(bh); 19401da177e4SLinus Torvalds set_buffer_uptodate(bh); 1941637aff46SNick Piggin mark_buffer_dirty(bh); 19421da177e4SLinus Torvalds continue; 19431da177e4SLinus Torvalds } 1944eebd2aa3SChristoph Lameter if (block_end > to || block_start < from) 1945eebd2aa3SChristoph Lameter zero_user_segments(page, 1946eebd2aa3SChristoph Lameter to, block_end, 1947eebd2aa3SChristoph Lameter block_start, from); 19481da177e4SLinus Torvalds continue; 19491da177e4SLinus Torvalds } 19501da177e4SLinus Torvalds } 19511da177e4SLinus Torvalds if (PageUptodate(page)) { 19521da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19531da177e4SLinus Torvalds set_buffer_uptodate(bh); 19541da177e4SLinus Torvalds continue; 19551da177e4SLinus Torvalds } 19561da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 195733a266ddSDavid Chinner !buffer_unwritten(bh) && 19581da177e4SLinus Torvalds (block_start < from || block_end > to)) { 19591da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 19601da177e4SLinus Torvalds *wait_bh++=bh; 19611da177e4SLinus Torvalds } 19621da177e4SLinus Torvalds } 19631da177e4SLinus Torvalds /* 19641da177e4SLinus Torvalds * If we issued read requests - let them complete. 19651da177e4SLinus Torvalds */ 19661da177e4SLinus Torvalds while(wait_bh > wait) { 19671da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 19681da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 1969f3ddbdc6SNick Piggin err = -EIO; 19701da177e4SLinus Torvalds } 1971f9f07b6cSJan Kara if (unlikely(err)) 1972afddba49SNick Piggin page_zero_new_buffers(page, from, to); 19731da177e4SLinus Torvalds return err; 19741da177e4SLinus Torvalds } 1975ebdec241SChristoph Hellwig EXPORT_SYMBOL(__block_write_begin); 19761da177e4SLinus Torvalds 19771da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 19781da177e4SLinus Torvalds unsigned from, unsigned to) 19791da177e4SLinus Torvalds { 19801da177e4SLinus Torvalds unsigned block_start, block_end; 19811da177e4SLinus Torvalds int partial = 0; 19821da177e4SLinus Torvalds unsigned blocksize; 19831da177e4SLinus Torvalds struct buffer_head *bh, *head; 19841da177e4SLinus Torvalds 198545bce8f3SLinus Torvalds bh = head = page_buffers(page); 198645bce8f3SLinus Torvalds blocksize = bh->b_size; 19871da177e4SLinus Torvalds 198845bce8f3SLinus Torvalds block_start = 0; 198945bce8f3SLinus Torvalds do { 19901da177e4SLinus Torvalds block_end = block_start + blocksize; 19911da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19921da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19931da177e4SLinus Torvalds partial = 1; 19941da177e4SLinus Torvalds } else { 19951da177e4SLinus Torvalds set_buffer_uptodate(bh); 19961da177e4SLinus Torvalds mark_buffer_dirty(bh); 19971da177e4SLinus Torvalds } 1998afddba49SNick Piggin clear_buffer_new(bh); 199945bce8f3SLinus Torvalds 200045bce8f3SLinus Torvalds block_start = block_end; 200145bce8f3SLinus Torvalds bh = bh->b_this_page; 200245bce8f3SLinus Torvalds } while (bh != head); 20031da177e4SLinus Torvalds 20041da177e4SLinus Torvalds /* 20051da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 20061da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 20071da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 20081da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 20091da177e4SLinus Torvalds */ 20101da177e4SLinus Torvalds if (!partial) 20111da177e4SLinus Torvalds SetPageUptodate(page); 20121da177e4SLinus Torvalds return 0; 20131da177e4SLinus Torvalds } 20141da177e4SLinus Torvalds 20151da177e4SLinus Torvalds /* 2016155130a4SChristoph Hellwig * block_write_begin takes care of the basic task of block allocation and 2017155130a4SChristoph Hellwig * bringing partial write blocks uptodate first. 2018155130a4SChristoph Hellwig * 20197bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 2020afddba49SNick Piggin */ 2021155130a4SChristoph Hellwig int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, 2022155130a4SChristoph Hellwig unsigned flags, struct page **pagep, get_block_t *get_block) 2023afddba49SNick Piggin { 202409cbfeafSKirill A. Shutemov pgoff_t index = pos >> PAGE_SHIFT; 2025afddba49SNick Piggin struct page *page; 20266e1db88dSChristoph Hellwig int status; 2027afddba49SNick Piggin 202854566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 20296e1db88dSChristoph Hellwig if (!page) 20306e1db88dSChristoph Hellwig return -ENOMEM; 2031afddba49SNick Piggin 20326e1db88dSChristoph Hellwig status = __block_write_begin(page, pos, len, get_block); 2033afddba49SNick Piggin if (unlikely(status)) { 2034afddba49SNick Piggin unlock_page(page); 203509cbfeafSKirill A. Shutemov put_page(page); 20366e1db88dSChristoph Hellwig page = NULL; 2037afddba49SNick Piggin } 2038afddba49SNick Piggin 20396e1db88dSChristoph Hellwig *pagep = page; 2040afddba49SNick Piggin return status; 2041afddba49SNick Piggin } 2042afddba49SNick Piggin EXPORT_SYMBOL(block_write_begin); 2043afddba49SNick Piggin 2044afddba49SNick Piggin int block_write_end(struct file *file, struct address_space *mapping, 2045afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2046afddba49SNick Piggin struct page *page, void *fsdata) 2047afddba49SNick Piggin { 2048afddba49SNick Piggin struct inode *inode = mapping->host; 2049afddba49SNick Piggin unsigned start; 2050afddba49SNick Piggin 205109cbfeafSKirill A. Shutemov start = pos & (PAGE_SIZE - 1); 2052afddba49SNick Piggin 2053afddba49SNick Piggin if (unlikely(copied < len)) { 2054afddba49SNick Piggin /* 2055afddba49SNick Piggin * The buffers that were written will now be uptodate, so we 2056afddba49SNick Piggin * don't have to worry about a readpage reading them and 2057afddba49SNick Piggin * overwriting a partial write. However if we have encountered 2058afddba49SNick Piggin * a short write and only partially written into a buffer, it 2059afddba49SNick Piggin * will not be marked uptodate, so a readpage might come in and 2060afddba49SNick Piggin * destroy our partial write. 2061afddba49SNick Piggin * 2062afddba49SNick Piggin * Do the simplest thing, and just treat any short write to a 2063afddba49SNick Piggin * non uptodate page as a zero-length write, and force the 2064afddba49SNick Piggin * caller to redo the whole thing. 2065afddba49SNick Piggin */ 2066afddba49SNick Piggin if (!PageUptodate(page)) 2067afddba49SNick Piggin copied = 0; 2068afddba49SNick Piggin 2069afddba49SNick Piggin page_zero_new_buffers(page, start+copied, start+len); 2070afddba49SNick Piggin } 2071afddba49SNick Piggin flush_dcache_page(page); 2072afddba49SNick Piggin 2073afddba49SNick Piggin /* This could be a short (even 0-length) commit */ 2074afddba49SNick Piggin __block_commit_write(inode, page, start, start+copied); 2075afddba49SNick Piggin 2076afddba49SNick Piggin return copied; 2077afddba49SNick Piggin } 2078afddba49SNick Piggin EXPORT_SYMBOL(block_write_end); 2079afddba49SNick Piggin 2080afddba49SNick Piggin int generic_write_end(struct file *file, struct address_space *mapping, 2081afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2082afddba49SNick Piggin struct page *page, void *fsdata) 2083afddba49SNick Piggin { 2084afddba49SNick Piggin struct inode *inode = mapping->host; 208590a80202SJan Kara loff_t old_size = inode->i_size; 2086c7d206b3SJan Kara int i_size_changed = 0; 2087afddba49SNick Piggin 2088afddba49SNick Piggin copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); 2089afddba49SNick Piggin 2090afddba49SNick Piggin /* 2091afddba49SNick Piggin * No need to use i_size_read() here, the i_size 2092afddba49SNick Piggin * cannot change under us because we hold i_mutex. 2093afddba49SNick Piggin * 2094afddba49SNick Piggin * But it's important to update i_size while still holding page lock: 2095afddba49SNick Piggin * page writeout could otherwise come in and zero beyond i_size. 2096afddba49SNick Piggin */ 2097afddba49SNick Piggin if (pos+copied > inode->i_size) { 2098afddba49SNick Piggin i_size_write(inode, pos+copied); 2099c7d206b3SJan Kara i_size_changed = 1; 2100afddba49SNick Piggin } 2101afddba49SNick Piggin 2102afddba49SNick Piggin unlock_page(page); 210309cbfeafSKirill A. Shutemov put_page(page); 2104afddba49SNick Piggin 210590a80202SJan Kara if (old_size < pos) 210690a80202SJan Kara pagecache_isize_extended(inode, old_size, pos); 2107c7d206b3SJan Kara /* 2108c7d206b3SJan Kara * Don't mark the inode dirty under page lock. First, it unnecessarily 2109c7d206b3SJan Kara * makes the holding time of page lock longer. Second, it forces lock 2110c7d206b3SJan Kara * ordering of page lock and transaction start for journaling 2111c7d206b3SJan Kara * filesystems. 2112c7d206b3SJan Kara */ 2113c7d206b3SJan Kara if (i_size_changed) 2114c7d206b3SJan Kara mark_inode_dirty(inode); 2115c7d206b3SJan Kara 2116afddba49SNick Piggin return copied; 2117afddba49SNick Piggin } 2118afddba49SNick Piggin EXPORT_SYMBOL(generic_write_end); 2119afddba49SNick Piggin 2120afddba49SNick Piggin /* 21218ab22b9aSHisashi Hifumi * block_is_partially_uptodate checks whether buffers within a page are 21228ab22b9aSHisashi Hifumi * uptodate or not. 21238ab22b9aSHisashi Hifumi * 21248ab22b9aSHisashi Hifumi * Returns true if all buffers which correspond to a file portion 21258ab22b9aSHisashi Hifumi * we want to read are uptodate. 21268ab22b9aSHisashi Hifumi */ 2127c186afb4SAl Viro int block_is_partially_uptodate(struct page *page, unsigned long from, 2128c186afb4SAl Viro unsigned long count) 21298ab22b9aSHisashi Hifumi { 21308ab22b9aSHisashi Hifumi unsigned block_start, block_end, blocksize; 21318ab22b9aSHisashi Hifumi unsigned to; 21328ab22b9aSHisashi Hifumi struct buffer_head *bh, *head; 21338ab22b9aSHisashi Hifumi int ret = 1; 21348ab22b9aSHisashi Hifumi 21358ab22b9aSHisashi Hifumi if (!page_has_buffers(page)) 21368ab22b9aSHisashi Hifumi return 0; 21378ab22b9aSHisashi Hifumi 213845bce8f3SLinus Torvalds head = page_buffers(page); 213945bce8f3SLinus Torvalds blocksize = head->b_size; 214009cbfeafSKirill A. Shutemov to = min_t(unsigned, PAGE_SIZE - from, count); 21418ab22b9aSHisashi Hifumi to = from + to; 214209cbfeafSKirill A. Shutemov if (from < blocksize && to > PAGE_SIZE - blocksize) 21438ab22b9aSHisashi Hifumi return 0; 21448ab22b9aSHisashi Hifumi 21458ab22b9aSHisashi Hifumi bh = head; 21468ab22b9aSHisashi Hifumi block_start = 0; 21478ab22b9aSHisashi Hifumi do { 21488ab22b9aSHisashi Hifumi block_end = block_start + blocksize; 21498ab22b9aSHisashi Hifumi if (block_end > from && block_start < to) { 21508ab22b9aSHisashi Hifumi if (!buffer_uptodate(bh)) { 21518ab22b9aSHisashi Hifumi ret = 0; 21528ab22b9aSHisashi Hifumi break; 21538ab22b9aSHisashi Hifumi } 21548ab22b9aSHisashi Hifumi if (block_end >= to) 21558ab22b9aSHisashi Hifumi break; 21568ab22b9aSHisashi Hifumi } 21578ab22b9aSHisashi Hifumi block_start = block_end; 21588ab22b9aSHisashi Hifumi bh = bh->b_this_page; 21598ab22b9aSHisashi Hifumi } while (bh != head); 21608ab22b9aSHisashi Hifumi 21618ab22b9aSHisashi Hifumi return ret; 21628ab22b9aSHisashi Hifumi } 21638ab22b9aSHisashi Hifumi EXPORT_SYMBOL(block_is_partially_uptodate); 21648ab22b9aSHisashi Hifumi 21658ab22b9aSHisashi Hifumi /* 21661da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 21671da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 21681da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 21691da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 21701da177e4SLinus Torvalds * page struct once IO has completed. 21711da177e4SLinus Torvalds */ 21721da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 21731da177e4SLinus Torvalds { 21741da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 21751da177e4SLinus Torvalds sector_t iblock, lblock; 21761da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 217745bce8f3SLinus Torvalds unsigned int blocksize, bbits; 21781da177e4SLinus Torvalds int nr, i; 21791da177e4SLinus Torvalds int fully_mapped = 1; 21801da177e4SLinus Torvalds 218145bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 218245bce8f3SLinus Torvalds blocksize = head->b_size; 218345bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 21841da177e4SLinus Torvalds 218509cbfeafSKirill A. Shutemov iblock = (sector_t)page->index << (PAGE_SHIFT - bbits); 218645bce8f3SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> bbits; 21871da177e4SLinus Torvalds bh = head; 21881da177e4SLinus Torvalds nr = 0; 21891da177e4SLinus Torvalds i = 0; 21901da177e4SLinus Torvalds 21911da177e4SLinus Torvalds do { 21921da177e4SLinus Torvalds if (buffer_uptodate(bh)) 21931da177e4SLinus Torvalds continue; 21941da177e4SLinus Torvalds 21951da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2196c64610baSAndrew Morton int err = 0; 2197c64610baSAndrew Morton 21981da177e4SLinus Torvalds fully_mapped = 0; 21991da177e4SLinus Torvalds if (iblock < lblock) { 2200b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 2201c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 2202c64610baSAndrew Morton if (err) 22031da177e4SLinus Torvalds SetPageError(page); 22041da177e4SLinus Torvalds } 22051da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2206eebd2aa3SChristoph Lameter zero_user(page, i * blocksize, blocksize); 2207c64610baSAndrew Morton if (!err) 22081da177e4SLinus Torvalds set_buffer_uptodate(bh); 22091da177e4SLinus Torvalds continue; 22101da177e4SLinus Torvalds } 22111da177e4SLinus Torvalds /* 22121da177e4SLinus Torvalds * get_block() might have updated the buffer 22131da177e4SLinus Torvalds * synchronously 22141da177e4SLinus Torvalds */ 22151da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22161da177e4SLinus Torvalds continue; 22171da177e4SLinus Torvalds } 22181da177e4SLinus Torvalds arr[nr++] = bh; 22191da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 22201da177e4SLinus Torvalds 22211da177e4SLinus Torvalds if (fully_mapped) 22221da177e4SLinus Torvalds SetPageMappedToDisk(page); 22231da177e4SLinus Torvalds 22241da177e4SLinus Torvalds if (!nr) { 22251da177e4SLinus Torvalds /* 22261da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 22271da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 22281da177e4SLinus Torvalds */ 22291da177e4SLinus Torvalds if (!PageError(page)) 22301da177e4SLinus Torvalds SetPageUptodate(page); 22311da177e4SLinus Torvalds unlock_page(page); 22321da177e4SLinus Torvalds return 0; 22331da177e4SLinus Torvalds } 22341da177e4SLinus Torvalds 22351da177e4SLinus Torvalds /* Stage two: lock the buffers */ 22361da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22371da177e4SLinus Torvalds bh = arr[i]; 22381da177e4SLinus Torvalds lock_buffer(bh); 22391da177e4SLinus Torvalds mark_buffer_async_read(bh); 22401da177e4SLinus Torvalds } 22411da177e4SLinus Torvalds 22421da177e4SLinus Torvalds /* 22431da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 22441da177e4SLinus Torvalds * inside the buffer lock in case another process reading 22451da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 22461da177e4SLinus Torvalds */ 22471da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22481da177e4SLinus Torvalds bh = arr[i]; 22491da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22501da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 22511da177e4SLinus Torvalds else 22521da177e4SLinus Torvalds submit_bh(READ, bh); 22531da177e4SLinus Torvalds } 22541da177e4SLinus Torvalds return 0; 22551da177e4SLinus Torvalds } 22561fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_read_full_page); 22571da177e4SLinus Torvalds 22581da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 225989e10787SNick Piggin * truncates. Uses filesystem pagecache writes to allow the filesystem to 22601da177e4SLinus Torvalds * deal with the hole. 22611da177e4SLinus Torvalds */ 226289e10787SNick Piggin int generic_cont_expand_simple(struct inode *inode, loff_t size) 22631da177e4SLinus Torvalds { 22641da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 22651da177e4SLinus Torvalds struct page *page; 226689e10787SNick Piggin void *fsdata; 22671da177e4SLinus Torvalds int err; 22681da177e4SLinus Torvalds 2269c08d3b0eSnpiggin@suse.de err = inode_newsize_ok(inode, size); 2270c08d3b0eSnpiggin@suse.de if (err) 22711da177e4SLinus Torvalds goto out; 22721da177e4SLinus Torvalds 227389e10787SNick Piggin err = pagecache_write_begin(NULL, mapping, size, 0, 227489e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, 227589e10787SNick Piggin &page, &fsdata); 227689e10787SNick Piggin if (err) 227705eb0b51SOGAWA Hirofumi goto out; 227805eb0b51SOGAWA Hirofumi 227989e10787SNick Piggin err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); 228089e10787SNick Piggin BUG_ON(err > 0); 228105eb0b51SOGAWA Hirofumi 228205eb0b51SOGAWA Hirofumi out: 228305eb0b51SOGAWA Hirofumi return err; 228405eb0b51SOGAWA Hirofumi } 22851fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_cont_expand_simple); 228605eb0b51SOGAWA Hirofumi 2287f1e3af72SAdrian Bunk static int cont_expand_zero(struct file *file, struct address_space *mapping, 228889e10787SNick Piggin loff_t pos, loff_t *bytes) 228905eb0b51SOGAWA Hirofumi { 229089e10787SNick Piggin struct inode *inode = mapping->host; 229189e10787SNick Piggin unsigned blocksize = 1 << inode->i_blkbits; 229289e10787SNick Piggin struct page *page; 229389e10787SNick Piggin void *fsdata; 229489e10787SNick Piggin pgoff_t index, curidx; 229589e10787SNick Piggin loff_t curpos; 229689e10787SNick Piggin unsigned zerofrom, offset, len; 229789e10787SNick Piggin int err = 0; 229805eb0b51SOGAWA Hirofumi 229909cbfeafSKirill A. Shutemov index = pos >> PAGE_SHIFT; 230009cbfeafSKirill A. Shutemov offset = pos & ~PAGE_MASK; 230189e10787SNick Piggin 230209cbfeafSKirill A. Shutemov while (index > (curidx = (curpos = *bytes)>>PAGE_SHIFT)) { 230309cbfeafSKirill A. Shutemov zerofrom = curpos & ~PAGE_MASK; 230489e10787SNick Piggin if (zerofrom & (blocksize-1)) { 230589e10787SNick Piggin *bytes |= (blocksize-1); 230689e10787SNick Piggin (*bytes)++; 230789e10787SNick Piggin } 230809cbfeafSKirill A. Shutemov len = PAGE_SIZE - zerofrom; 230989e10787SNick Piggin 231089e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 231189e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 231289e10787SNick Piggin &page, &fsdata); 231389e10787SNick Piggin if (err) 231489e10787SNick Piggin goto out; 2315eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 231689e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 231789e10787SNick Piggin page, fsdata); 231889e10787SNick Piggin if (err < 0) 231989e10787SNick Piggin goto out; 232089e10787SNick Piggin BUG_ON(err != len); 232189e10787SNick Piggin err = 0; 2322061e9746SOGAWA Hirofumi 2323061e9746SOGAWA Hirofumi balance_dirty_pages_ratelimited(mapping); 2324c2ca0fcdSMikulas Patocka 2325c2ca0fcdSMikulas Patocka if (unlikely(fatal_signal_pending(current))) { 2326c2ca0fcdSMikulas Patocka err = -EINTR; 2327c2ca0fcdSMikulas Patocka goto out; 2328c2ca0fcdSMikulas Patocka } 232989e10787SNick Piggin } 233089e10787SNick Piggin 233189e10787SNick Piggin /* page covers the boundary, find the boundary offset */ 233289e10787SNick Piggin if (index == curidx) { 233309cbfeafSKirill A. Shutemov zerofrom = curpos & ~PAGE_MASK; 233489e10787SNick Piggin /* if we will expand the thing last block will be filled */ 233589e10787SNick Piggin if (offset <= zerofrom) { 233689e10787SNick Piggin goto out; 233789e10787SNick Piggin } 233889e10787SNick Piggin if (zerofrom & (blocksize-1)) { 233989e10787SNick Piggin *bytes |= (blocksize-1); 234089e10787SNick Piggin (*bytes)++; 234189e10787SNick Piggin } 234289e10787SNick Piggin len = offset - zerofrom; 234389e10787SNick Piggin 234489e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 234589e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 234689e10787SNick Piggin &page, &fsdata); 234789e10787SNick Piggin if (err) 234889e10787SNick Piggin goto out; 2349eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 235089e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 235189e10787SNick Piggin page, fsdata); 235289e10787SNick Piggin if (err < 0) 235389e10787SNick Piggin goto out; 235489e10787SNick Piggin BUG_ON(err != len); 235589e10787SNick Piggin err = 0; 235689e10787SNick Piggin } 235789e10787SNick Piggin out: 235889e10787SNick Piggin return err; 23591da177e4SLinus Torvalds } 23601da177e4SLinus Torvalds 23611da177e4SLinus Torvalds /* 23621da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 23631da177e4SLinus Torvalds * We may have to extend the file. 23641da177e4SLinus Torvalds */ 2365282dc178SChristoph Hellwig int cont_write_begin(struct file *file, struct address_space *mapping, 236689e10787SNick Piggin loff_t pos, unsigned len, unsigned flags, 236789e10787SNick Piggin struct page **pagep, void **fsdata, 236889e10787SNick Piggin get_block_t *get_block, loff_t *bytes) 23691da177e4SLinus Torvalds { 23701da177e4SLinus Torvalds struct inode *inode = mapping->host; 23711da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 237289e10787SNick Piggin unsigned zerofrom; 237389e10787SNick Piggin int err; 23741da177e4SLinus Torvalds 237589e10787SNick Piggin err = cont_expand_zero(file, mapping, pos, bytes); 237689e10787SNick Piggin if (err) 2377155130a4SChristoph Hellwig return err; 23781da177e4SLinus Torvalds 237909cbfeafSKirill A. Shutemov zerofrom = *bytes & ~PAGE_MASK; 238089e10787SNick Piggin if (pos+len > *bytes && zerofrom & (blocksize-1)) { 23811da177e4SLinus Torvalds *bytes |= (blocksize-1); 23821da177e4SLinus Torvalds (*bytes)++; 23831da177e4SLinus Torvalds } 23841da177e4SLinus Torvalds 2385155130a4SChristoph Hellwig return block_write_begin(mapping, pos, len, flags, pagep, get_block); 23861da177e4SLinus Torvalds } 23871fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(cont_write_begin); 23881da177e4SLinus Torvalds 23891da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 23901da177e4SLinus Torvalds { 23911da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23921da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 23931da177e4SLinus Torvalds return 0; 23941da177e4SLinus Torvalds } 23951fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_commit_write); 23961da177e4SLinus Torvalds 239754171690SDavid Chinner /* 239854171690SDavid Chinner * block_page_mkwrite() is not allowed to change the file size as it gets 239954171690SDavid Chinner * called from a page fault handler when a page is first dirtied. Hence we must 240054171690SDavid Chinner * be careful to check for EOF conditions here. We set the page up correctly 240154171690SDavid Chinner * for a written page which means we get ENOSPC checking when writing into 240254171690SDavid Chinner * holes and correct delalloc and unwritten extent mapping on filesystems that 240354171690SDavid Chinner * support these features. 240454171690SDavid Chinner * 240554171690SDavid Chinner * We are not allowed to take the i_mutex here so we have to play games to 240654171690SDavid Chinner * protect against truncate races as the page could now be beyond EOF. Because 24077bb46a67Snpiggin@suse.de * truncate writes the inode size before removing pages, once we have the 240854171690SDavid Chinner * page lock we can determine safely if the page is beyond EOF. If it is not 240954171690SDavid Chinner * beyond EOF, then the page is guaranteed safe against truncation until we 241054171690SDavid Chinner * unlock the page. 2411ea13a864SJan Kara * 241214da9200SJan Kara * Direct callers of this function should protect against filesystem freezing 24135c500029SRoss Zwisler * using sb_start_pagefault() - sb_end_pagefault() functions. 241454171690SDavid Chinner */ 24155c500029SRoss Zwisler int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 241654171690SDavid Chinner get_block_t get_block) 241754171690SDavid Chinner { 2418c2ec175cSNick Piggin struct page *page = vmf->page; 2419496ad9aaSAl Viro struct inode *inode = file_inode(vma->vm_file); 242054171690SDavid Chinner unsigned long end; 242154171690SDavid Chinner loff_t size; 242224da4fabSJan Kara int ret; 242354171690SDavid Chinner 242454171690SDavid Chinner lock_page(page); 242554171690SDavid Chinner size = i_size_read(inode); 242654171690SDavid Chinner if ((page->mapping != inode->i_mapping) || 242718336338SNick Piggin (page_offset(page) > size)) { 242824da4fabSJan Kara /* We overload EFAULT to mean page got truncated */ 242924da4fabSJan Kara ret = -EFAULT; 243024da4fabSJan Kara goto out_unlock; 243154171690SDavid Chinner } 243254171690SDavid Chinner 243354171690SDavid Chinner /* page is wholly or partially inside EOF */ 243409cbfeafSKirill A. Shutemov if (((page->index + 1) << PAGE_SHIFT) > size) 243509cbfeafSKirill A. Shutemov end = size & ~PAGE_MASK; 243654171690SDavid Chinner else 243709cbfeafSKirill A. Shutemov end = PAGE_SIZE; 243854171690SDavid Chinner 2439ebdec241SChristoph Hellwig ret = __block_write_begin(page, 0, end, get_block); 244054171690SDavid Chinner if (!ret) 244154171690SDavid Chinner ret = block_commit_write(page, 0, end); 244254171690SDavid Chinner 244324da4fabSJan Kara if (unlikely(ret < 0)) 244424da4fabSJan Kara goto out_unlock; 2445ea13a864SJan Kara set_page_dirty(page); 24461d1d1a76SDarrick J. Wong wait_for_stable_page(page); 244724da4fabSJan Kara return 0; 244824da4fabSJan Kara out_unlock: 2449b827e496SNick Piggin unlock_page(page); 245054171690SDavid Chinner return ret; 245154171690SDavid Chinner } 24521fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_page_mkwrite); 24531da177e4SLinus Torvalds 24541da177e4SLinus Torvalds /* 245503158cd7SNick Piggin * nobh_write_begin()'s prereads are special: the buffer_heads are freed 24561da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 24571da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 24581da177e4SLinus Torvalds */ 24591da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 24601da177e4SLinus Torvalds { 246168671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 24621da177e4SLinus Torvalds } 24631da177e4SLinus Torvalds 24641da177e4SLinus Torvalds /* 246503158cd7SNick Piggin * Attach the singly-linked list of buffers created by nobh_write_begin, to 246603158cd7SNick Piggin * the page (converting it to circular linked list and taking care of page 246703158cd7SNick Piggin * dirty races). 246803158cd7SNick Piggin */ 246903158cd7SNick Piggin static void attach_nobh_buffers(struct page *page, struct buffer_head *head) 247003158cd7SNick Piggin { 247103158cd7SNick Piggin struct buffer_head *bh; 247203158cd7SNick Piggin 247303158cd7SNick Piggin BUG_ON(!PageLocked(page)); 247403158cd7SNick Piggin 247503158cd7SNick Piggin spin_lock(&page->mapping->private_lock); 247603158cd7SNick Piggin bh = head; 247703158cd7SNick Piggin do { 247803158cd7SNick Piggin if (PageDirty(page)) 247903158cd7SNick Piggin set_buffer_dirty(bh); 248003158cd7SNick Piggin if (!bh->b_this_page) 248103158cd7SNick Piggin bh->b_this_page = head; 248203158cd7SNick Piggin bh = bh->b_this_page; 248303158cd7SNick Piggin } while (bh != head); 248403158cd7SNick Piggin attach_page_buffers(page, head); 248503158cd7SNick Piggin spin_unlock(&page->mapping->private_lock); 248603158cd7SNick Piggin } 248703158cd7SNick Piggin 248803158cd7SNick Piggin /* 2489ea0f04e5SChristoph Hellwig * On entry, the page is fully not uptodate. 2490ea0f04e5SChristoph Hellwig * On exit the page is fully uptodate in the areas outside (from,to) 24917bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 24921da177e4SLinus Torvalds */ 2493ea0f04e5SChristoph Hellwig int nobh_write_begin(struct address_space *mapping, 249403158cd7SNick Piggin loff_t pos, unsigned len, unsigned flags, 249503158cd7SNick Piggin struct page **pagep, void **fsdata, 24961da177e4SLinus Torvalds get_block_t *get_block) 24971da177e4SLinus Torvalds { 249803158cd7SNick Piggin struct inode *inode = mapping->host; 24991da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 25001da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 2501a4b0672dSNick Piggin struct buffer_head *head, *bh; 250203158cd7SNick Piggin struct page *page; 250303158cd7SNick Piggin pgoff_t index; 250403158cd7SNick Piggin unsigned from, to; 25051da177e4SLinus Torvalds unsigned block_in_page; 2506a4b0672dSNick Piggin unsigned block_start, block_end; 25071da177e4SLinus Torvalds sector_t block_in_file; 25081da177e4SLinus Torvalds int nr_reads = 0; 25091da177e4SLinus Torvalds int ret = 0; 25101da177e4SLinus Torvalds int is_mapped_to_disk = 1; 25111da177e4SLinus Torvalds 251209cbfeafSKirill A. Shutemov index = pos >> PAGE_SHIFT; 251309cbfeafSKirill A. Shutemov from = pos & (PAGE_SIZE - 1); 251403158cd7SNick Piggin to = from + len; 251503158cd7SNick Piggin 251654566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 251703158cd7SNick Piggin if (!page) 251803158cd7SNick Piggin return -ENOMEM; 251903158cd7SNick Piggin *pagep = page; 252003158cd7SNick Piggin *fsdata = NULL; 252103158cd7SNick Piggin 252203158cd7SNick Piggin if (page_has_buffers(page)) { 2523309f77adSNamhyung Kim ret = __block_write_begin(page, pos, len, get_block); 2524309f77adSNamhyung Kim if (unlikely(ret)) 2525309f77adSNamhyung Kim goto out_release; 2526309f77adSNamhyung Kim return ret; 252703158cd7SNick Piggin } 2528a4b0672dSNick Piggin 25291da177e4SLinus Torvalds if (PageMappedToDisk(page)) 25301da177e4SLinus Torvalds return 0; 25311da177e4SLinus Torvalds 2532a4b0672dSNick Piggin /* 2533a4b0672dSNick Piggin * Allocate buffers so that we can keep track of state, and potentially 2534a4b0672dSNick Piggin * attach them to the page if an error occurs. In the common case of 2535a4b0672dSNick Piggin * no error, they will just be freed again without ever being attached 2536a4b0672dSNick Piggin * to the page (which is all OK, because we're under the page lock). 2537a4b0672dSNick Piggin * 2538a4b0672dSNick Piggin * Be careful: the buffer linked list is a NULL terminated one, rather 2539a4b0672dSNick Piggin * than the circular one we're used to. 2540a4b0672dSNick Piggin */ 2541a4b0672dSNick Piggin head = alloc_page_buffers(page, blocksize, 0); 254203158cd7SNick Piggin if (!head) { 254303158cd7SNick Piggin ret = -ENOMEM; 254403158cd7SNick Piggin goto out_release; 254503158cd7SNick Piggin } 2546a4b0672dSNick Piggin 254709cbfeafSKirill A. Shutemov block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits); 25481da177e4SLinus Torvalds 25491da177e4SLinus Torvalds /* 25501da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 25511da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 25521da177e4SLinus Torvalds * page is fully mapped-to-disk. 25531da177e4SLinus Torvalds */ 2554a4b0672dSNick Piggin for (block_start = 0, block_in_page = 0, bh = head; 255509cbfeafSKirill A. Shutemov block_start < PAGE_SIZE; 2556a4b0672dSNick Piggin block_in_page++, block_start += blocksize, bh = bh->b_this_page) { 25571da177e4SLinus Torvalds int create; 25581da177e4SLinus Torvalds 2559a4b0672dSNick Piggin block_end = block_start + blocksize; 2560a4b0672dSNick Piggin bh->b_state = 0; 25611da177e4SLinus Torvalds create = 1; 25621da177e4SLinus Torvalds if (block_start >= to) 25631da177e4SLinus Torvalds create = 0; 25641da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 2565a4b0672dSNick Piggin bh, create); 25661da177e4SLinus Torvalds if (ret) 25671da177e4SLinus Torvalds goto failed; 2568a4b0672dSNick Piggin if (!buffer_mapped(bh)) 25691da177e4SLinus Torvalds is_mapped_to_disk = 0; 2570a4b0672dSNick Piggin if (buffer_new(bh)) 2571a4b0672dSNick Piggin unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 2572a4b0672dSNick Piggin if (PageUptodate(page)) { 2573a4b0672dSNick Piggin set_buffer_uptodate(bh); 25741da177e4SLinus Torvalds continue; 2575a4b0672dSNick Piggin } 2576a4b0672dSNick Piggin if (buffer_new(bh) || !buffer_mapped(bh)) { 2577eebd2aa3SChristoph Lameter zero_user_segments(page, block_start, from, 2578eebd2aa3SChristoph Lameter to, block_end); 25791da177e4SLinus Torvalds continue; 25801da177e4SLinus Torvalds } 2581a4b0672dSNick Piggin if (buffer_uptodate(bh)) 25821da177e4SLinus Torvalds continue; /* reiserfs does this */ 25831da177e4SLinus Torvalds if (block_start < from || block_end > to) { 2584a4b0672dSNick Piggin lock_buffer(bh); 2585a4b0672dSNick Piggin bh->b_end_io = end_buffer_read_nobh; 2586a4b0672dSNick Piggin submit_bh(READ, bh); 2587a4b0672dSNick Piggin nr_reads++; 25881da177e4SLinus Torvalds } 25891da177e4SLinus Torvalds } 25901da177e4SLinus Torvalds 25911da177e4SLinus Torvalds if (nr_reads) { 25921da177e4SLinus Torvalds /* 25931da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 25941da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 25951da177e4SLinus Torvalds * for the buffer_head refcounts. 25961da177e4SLinus Torvalds */ 2597a4b0672dSNick Piggin for (bh = head; bh; bh = bh->b_this_page) { 25981da177e4SLinus Torvalds wait_on_buffer(bh); 25991da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 26001da177e4SLinus Torvalds ret = -EIO; 26011da177e4SLinus Torvalds } 26021da177e4SLinus Torvalds if (ret) 26031da177e4SLinus Torvalds goto failed; 26041da177e4SLinus Torvalds } 26051da177e4SLinus Torvalds 26061da177e4SLinus Torvalds if (is_mapped_to_disk) 26071da177e4SLinus Torvalds SetPageMappedToDisk(page); 26081da177e4SLinus Torvalds 260903158cd7SNick Piggin *fsdata = head; /* to be released by nobh_write_end */ 2610a4b0672dSNick Piggin 26111da177e4SLinus Torvalds return 0; 26121da177e4SLinus Torvalds 26131da177e4SLinus Torvalds failed: 261403158cd7SNick Piggin BUG_ON(!ret); 26151da177e4SLinus Torvalds /* 2616a4b0672dSNick Piggin * Error recovery is a bit difficult. We need to zero out blocks that 2617a4b0672dSNick Piggin * were newly allocated, and dirty them to ensure they get written out. 2618a4b0672dSNick Piggin * Buffers need to be attached to the page at this point, otherwise 2619a4b0672dSNick Piggin * the handling of potential IO errors during writeout would be hard 2620a4b0672dSNick Piggin * (could try doing synchronous writeout, but what if that fails too?) 26211da177e4SLinus Torvalds */ 262203158cd7SNick Piggin attach_nobh_buffers(page, head); 262303158cd7SNick Piggin page_zero_new_buffers(page, from, to); 2624a4b0672dSNick Piggin 262503158cd7SNick Piggin out_release: 262603158cd7SNick Piggin unlock_page(page); 262709cbfeafSKirill A. Shutemov put_page(page); 262803158cd7SNick Piggin *pagep = NULL; 2629a4b0672dSNick Piggin 26307bb46a67Snpiggin@suse.de return ret; 26317bb46a67Snpiggin@suse.de } 263203158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_begin); 26331da177e4SLinus Torvalds 263403158cd7SNick Piggin int nobh_write_end(struct file *file, struct address_space *mapping, 263503158cd7SNick Piggin loff_t pos, unsigned len, unsigned copied, 263603158cd7SNick Piggin struct page *page, void *fsdata) 26371da177e4SLinus Torvalds { 26381da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 2639efdc3131SNick Piggin struct buffer_head *head = fsdata; 264003158cd7SNick Piggin struct buffer_head *bh; 26415b41e74aSDmitri Monakhov BUG_ON(fsdata != NULL && page_has_buffers(page)); 26421da177e4SLinus Torvalds 2643d4cf109fSDave Kleikamp if (unlikely(copied < len) && head) 264403158cd7SNick Piggin attach_nobh_buffers(page, head); 2645a4b0672dSNick Piggin if (page_has_buffers(page)) 264603158cd7SNick Piggin return generic_write_end(file, mapping, pos, len, 264703158cd7SNick Piggin copied, page, fsdata); 2648a4b0672dSNick Piggin 264922c8ca78SNick Piggin SetPageUptodate(page); 26501da177e4SLinus Torvalds set_page_dirty(page); 265103158cd7SNick Piggin if (pos+copied > inode->i_size) { 265203158cd7SNick Piggin i_size_write(inode, pos+copied); 26531da177e4SLinus Torvalds mark_inode_dirty(inode); 26541da177e4SLinus Torvalds } 265503158cd7SNick Piggin 265603158cd7SNick Piggin unlock_page(page); 265709cbfeafSKirill A. Shutemov put_page(page); 265803158cd7SNick Piggin 265903158cd7SNick Piggin while (head) { 266003158cd7SNick Piggin bh = head; 266103158cd7SNick Piggin head = head->b_this_page; 266203158cd7SNick Piggin free_buffer_head(bh); 26631da177e4SLinus Torvalds } 266403158cd7SNick Piggin 266503158cd7SNick Piggin return copied; 266603158cd7SNick Piggin } 266703158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_end); 26681da177e4SLinus Torvalds 26691da177e4SLinus Torvalds /* 26701da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 26711da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 26721da177e4SLinus Torvalds * the page. 26731da177e4SLinus Torvalds */ 26741da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 26751da177e4SLinus Torvalds struct writeback_control *wbc) 26761da177e4SLinus Torvalds { 26771da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 26781da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 267909cbfeafSKirill A. Shutemov const pgoff_t end_index = i_size >> PAGE_SHIFT; 26801da177e4SLinus Torvalds unsigned offset; 26811da177e4SLinus Torvalds int ret; 26821da177e4SLinus Torvalds 26831da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 26841da177e4SLinus Torvalds if (page->index < end_index) 26851da177e4SLinus Torvalds goto out; 26861da177e4SLinus Torvalds 26871da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 268809cbfeafSKirill A. Shutemov offset = i_size & (PAGE_SIZE-1); 26891da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 26901da177e4SLinus Torvalds /* 26911da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 26921da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 26931da177e4SLinus Torvalds * freeable here, so the page does not leak. 26941da177e4SLinus Torvalds */ 26951da177e4SLinus Torvalds #if 0 26961da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 26971da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 26981da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 26991da177e4SLinus Torvalds #endif 27001da177e4SLinus Torvalds unlock_page(page); 27011da177e4SLinus Torvalds return 0; /* don't care */ 27021da177e4SLinus Torvalds } 27031da177e4SLinus Torvalds 27041da177e4SLinus Torvalds /* 27051da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 27061da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 27071da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 27081da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 27091da177e4SLinus Torvalds * writes to that region are not written out to the file." 27101da177e4SLinus Torvalds */ 271109cbfeafSKirill A. Shutemov zero_user_segment(page, offset, PAGE_SIZE); 27121da177e4SLinus Torvalds out: 27131da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 27141da177e4SLinus Torvalds if (ret == -EAGAIN) 271535c80d5fSChris Mason ret = __block_write_full_page(inode, page, get_block, wbc, 271635c80d5fSChris Mason end_buffer_async_write); 27171da177e4SLinus Torvalds return ret; 27181da177e4SLinus Torvalds } 27191da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 27201da177e4SLinus Torvalds 272103158cd7SNick Piggin int nobh_truncate_page(struct address_space *mapping, 272203158cd7SNick Piggin loff_t from, get_block_t *get_block) 27231da177e4SLinus Torvalds { 272409cbfeafSKirill A. Shutemov pgoff_t index = from >> PAGE_SHIFT; 272509cbfeafSKirill A. Shutemov unsigned offset = from & (PAGE_SIZE-1); 272603158cd7SNick Piggin unsigned blocksize; 272703158cd7SNick Piggin sector_t iblock; 272803158cd7SNick Piggin unsigned length, pos; 272903158cd7SNick Piggin struct inode *inode = mapping->host; 27301da177e4SLinus Torvalds struct page *page; 273103158cd7SNick Piggin struct buffer_head map_bh; 273203158cd7SNick Piggin int err; 27331da177e4SLinus Torvalds 273403158cd7SNick Piggin blocksize = 1 << inode->i_blkbits; 273503158cd7SNick Piggin length = offset & (blocksize - 1); 27361da177e4SLinus Torvalds 273703158cd7SNick Piggin /* Block boundary? Nothing to do */ 273803158cd7SNick Piggin if (!length) 273903158cd7SNick Piggin return 0; 274003158cd7SNick Piggin 274103158cd7SNick Piggin length = blocksize - length; 274209cbfeafSKirill A. Shutemov iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); 274303158cd7SNick Piggin 27441da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 274503158cd7SNick Piggin err = -ENOMEM; 27461da177e4SLinus Torvalds if (!page) 27471da177e4SLinus Torvalds goto out; 27481da177e4SLinus Torvalds 274903158cd7SNick Piggin if (page_has_buffers(page)) { 275003158cd7SNick Piggin has_buffers: 275103158cd7SNick Piggin unlock_page(page); 275209cbfeafSKirill A. Shutemov put_page(page); 275303158cd7SNick Piggin return block_truncate_page(mapping, from, get_block); 27541da177e4SLinus Torvalds } 275503158cd7SNick Piggin 275603158cd7SNick Piggin /* Find the buffer that contains "offset" */ 275703158cd7SNick Piggin pos = blocksize; 275803158cd7SNick Piggin while (offset >= pos) { 275903158cd7SNick Piggin iblock++; 276003158cd7SNick Piggin pos += blocksize; 276103158cd7SNick Piggin } 276203158cd7SNick Piggin 2763460bcf57STheodore Ts'o map_bh.b_size = blocksize; 2764460bcf57STheodore Ts'o map_bh.b_state = 0; 276503158cd7SNick Piggin err = get_block(inode, iblock, &map_bh, 0); 276603158cd7SNick Piggin if (err) 276703158cd7SNick Piggin goto unlock; 276803158cd7SNick Piggin /* unmapped? It's a hole - nothing to do */ 276903158cd7SNick Piggin if (!buffer_mapped(&map_bh)) 277003158cd7SNick Piggin goto unlock; 277103158cd7SNick Piggin 277203158cd7SNick Piggin /* Ok, it's mapped. Make sure it's up-to-date */ 277303158cd7SNick Piggin if (!PageUptodate(page)) { 277403158cd7SNick Piggin err = mapping->a_ops->readpage(NULL, page); 277503158cd7SNick Piggin if (err) { 277609cbfeafSKirill A. Shutemov put_page(page); 277703158cd7SNick Piggin goto out; 277803158cd7SNick Piggin } 277903158cd7SNick Piggin lock_page(page); 278003158cd7SNick Piggin if (!PageUptodate(page)) { 278103158cd7SNick Piggin err = -EIO; 278203158cd7SNick Piggin goto unlock; 278303158cd7SNick Piggin } 278403158cd7SNick Piggin if (page_has_buffers(page)) 278503158cd7SNick Piggin goto has_buffers; 278603158cd7SNick Piggin } 2787eebd2aa3SChristoph Lameter zero_user(page, offset, length); 278803158cd7SNick Piggin set_page_dirty(page); 278903158cd7SNick Piggin err = 0; 279003158cd7SNick Piggin 279103158cd7SNick Piggin unlock: 27921da177e4SLinus Torvalds unlock_page(page); 279309cbfeafSKirill A. Shutemov put_page(page); 27941da177e4SLinus Torvalds out: 279503158cd7SNick Piggin return err; 27961da177e4SLinus Torvalds } 27971da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 27981da177e4SLinus Torvalds 27991da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 28001da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 28011da177e4SLinus Torvalds { 280209cbfeafSKirill A. Shutemov pgoff_t index = from >> PAGE_SHIFT; 280309cbfeafSKirill A. Shutemov unsigned offset = from & (PAGE_SIZE-1); 28041da177e4SLinus Torvalds unsigned blocksize; 280554b21a79SAndrew Morton sector_t iblock; 28061da177e4SLinus Torvalds unsigned length, pos; 28071da177e4SLinus Torvalds struct inode *inode = mapping->host; 28081da177e4SLinus Torvalds struct page *page; 28091da177e4SLinus Torvalds struct buffer_head *bh; 28101da177e4SLinus Torvalds int err; 28111da177e4SLinus Torvalds 28121da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 28131da177e4SLinus Torvalds length = offset & (blocksize - 1); 28141da177e4SLinus Torvalds 28151da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 28161da177e4SLinus Torvalds if (!length) 28171da177e4SLinus Torvalds return 0; 28181da177e4SLinus Torvalds 28191da177e4SLinus Torvalds length = blocksize - length; 282009cbfeafSKirill A. Shutemov iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); 28211da177e4SLinus Torvalds 28221da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 28231da177e4SLinus Torvalds err = -ENOMEM; 28241da177e4SLinus Torvalds if (!page) 28251da177e4SLinus Torvalds goto out; 28261da177e4SLinus Torvalds 28271da177e4SLinus Torvalds if (!page_has_buffers(page)) 28281da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 28291da177e4SLinus Torvalds 28301da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 28311da177e4SLinus Torvalds bh = page_buffers(page); 28321da177e4SLinus Torvalds pos = blocksize; 28331da177e4SLinus Torvalds while (offset >= pos) { 28341da177e4SLinus Torvalds bh = bh->b_this_page; 28351da177e4SLinus Torvalds iblock++; 28361da177e4SLinus Torvalds pos += blocksize; 28371da177e4SLinus Torvalds } 28381da177e4SLinus Torvalds 28391da177e4SLinus Torvalds err = 0; 28401da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2841b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 28421da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 28431da177e4SLinus Torvalds if (err) 28441da177e4SLinus Torvalds goto unlock; 28451da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 28461da177e4SLinus Torvalds if (!buffer_mapped(bh)) 28471da177e4SLinus Torvalds goto unlock; 28481da177e4SLinus Torvalds } 28491da177e4SLinus Torvalds 28501da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 28511da177e4SLinus Torvalds if (PageUptodate(page)) 28521da177e4SLinus Torvalds set_buffer_uptodate(bh); 28531da177e4SLinus Torvalds 285433a266ddSDavid Chinner if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { 28551da177e4SLinus Torvalds err = -EIO; 28561da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 28571da177e4SLinus Torvalds wait_on_buffer(bh); 28581da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 28591da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 28601da177e4SLinus Torvalds goto unlock; 28611da177e4SLinus Torvalds } 28621da177e4SLinus Torvalds 2863eebd2aa3SChristoph Lameter zero_user(page, offset, length); 28641da177e4SLinus Torvalds mark_buffer_dirty(bh); 28651da177e4SLinus Torvalds err = 0; 28661da177e4SLinus Torvalds 28671da177e4SLinus Torvalds unlock: 28681da177e4SLinus Torvalds unlock_page(page); 286909cbfeafSKirill A. Shutemov put_page(page); 28701da177e4SLinus Torvalds out: 28711da177e4SLinus Torvalds return err; 28721da177e4SLinus Torvalds } 28731fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_truncate_page); 28741da177e4SLinus Torvalds 28751da177e4SLinus Torvalds /* 28761da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 28771da177e4SLinus Torvalds */ 28781b938c08SMatthew Wilcox int block_write_full_page(struct page *page, get_block_t *get_block, 28791b938c08SMatthew Wilcox struct writeback_control *wbc) 28801da177e4SLinus Torvalds { 28811da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 28821da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 288309cbfeafSKirill A. Shutemov const pgoff_t end_index = i_size >> PAGE_SHIFT; 28841da177e4SLinus Torvalds unsigned offset; 28851da177e4SLinus Torvalds 28861da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 28871da177e4SLinus Torvalds if (page->index < end_index) 288835c80d5fSChris Mason return __block_write_full_page(inode, page, get_block, wbc, 28891b938c08SMatthew Wilcox end_buffer_async_write); 28901da177e4SLinus Torvalds 28911da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 289209cbfeafSKirill A. Shutemov offset = i_size & (PAGE_SIZE-1); 28931da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 28941da177e4SLinus Torvalds /* 28951da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 28961da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 28971da177e4SLinus Torvalds * freeable here, so the page does not leak. 28981da177e4SLinus Torvalds */ 289909cbfeafSKirill A. Shutemov do_invalidatepage(page, 0, PAGE_SIZE); 29001da177e4SLinus Torvalds unlock_page(page); 29011da177e4SLinus Torvalds return 0; /* don't care */ 29021da177e4SLinus Torvalds } 29031da177e4SLinus Torvalds 29041da177e4SLinus Torvalds /* 29051da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 29062a61aa40SAdam Buchbinder * writepage invocation because it may be mmapped. "A file is mapped 29071da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 29081da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 29091da177e4SLinus Torvalds * writes to that region are not written out to the file." 29101da177e4SLinus Torvalds */ 291109cbfeafSKirill A. Shutemov zero_user_segment(page, offset, PAGE_SIZE); 29121b938c08SMatthew Wilcox return __block_write_full_page(inode, page, get_block, wbc, 291335c80d5fSChris Mason end_buffer_async_write); 291435c80d5fSChris Mason } 29151fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_write_full_page); 291635c80d5fSChris Mason 29171da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 29181da177e4SLinus Torvalds get_block_t *get_block) 29191da177e4SLinus Torvalds { 29201da177e4SLinus Torvalds struct buffer_head tmp; 29211da177e4SLinus Torvalds struct inode *inode = mapping->host; 29221da177e4SLinus Torvalds tmp.b_state = 0; 29231da177e4SLinus Torvalds tmp.b_blocknr = 0; 2924b0cf2321SBadari Pulavarty tmp.b_size = 1 << inode->i_blkbits; 29251da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 29261da177e4SLinus Torvalds return tmp.b_blocknr; 29271da177e4SLinus Torvalds } 29281fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_block_bmap); 29291da177e4SLinus Torvalds 29304246a0b6SChristoph Hellwig static void end_bio_bh_io_sync(struct bio *bio) 29311da177e4SLinus Torvalds { 29321da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 29331da177e4SLinus Torvalds 2934b7c44ed9SJens Axboe if (unlikely(bio_flagged(bio, BIO_QUIET))) 293508bafc03SKeith Mannthey set_bit(BH_Quiet, &bh->b_state); 293608bafc03SKeith Mannthey 29374246a0b6SChristoph Hellwig bh->b_end_io(bh, !bio->bi_error); 29381da177e4SLinus Torvalds bio_put(bio); 29391da177e4SLinus Torvalds } 29401da177e4SLinus Torvalds 294157302e0dSLinus Torvalds /* 294257302e0dSLinus Torvalds * This allows us to do IO even on the odd last sectors 294359d43914SAkinobu Mita * of a device, even if the block size is some multiple 294457302e0dSLinus Torvalds * of the physical sector size. 294557302e0dSLinus Torvalds * 294657302e0dSLinus Torvalds * We'll just truncate the bio to the size of the device, 294757302e0dSLinus Torvalds * and clear the end of the buffer head manually. 294857302e0dSLinus Torvalds * 294957302e0dSLinus Torvalds * Truly out-of-range accesses will turn into actual IO 295057302e0dSLinus Torvalds * errors, this only handles the "we need to be able to 295157302e0dSLinus Torvalds * do IO at the final sector" case. 295257302e0dSLinus Torvalds */ 29534db96b71SAkinobu Mita void guard_bio_eod(int rw, struct bio *bio) 295457302e0dSLinus Torvalds { 295557302e0dSLinus Torvalds sector_t maxsector; 295659d43914SAkinobu Mita struct bio_vec *bvec = &bio->bi_io_vec[bio->bi_vcnt - 1]; 295759d43914SAkinobu Mita unsigned truncated_bytes; 295857302e0dSLinus Torvalds 295957302e0dSLinus Torvalds maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; 296057302e0dSLinus Torvalds if (!maxsector) 296157302e0dSLinus Torvalds return; 296257302e0dSLinus Torvalds 296357302e0dSLinus Torvalds /* 296457302e0dSLinus Torvalds * If the *whole* IO is past the end of the device, 296557302e0dSLinus Torvalds * let it through, and the IO layer will turn it into 296657302e0dSLinus Torvalds * an EIO. 296757302e0dSLinus Torvalds */ 29684f024f37SKent Overstreet if (unlikely(bio->bi_iter.bi_sector >= maxsector)) 296957302e0dSLinus Torvalds return; 297057302e0dSLinus Torvalds 29714f024f37SKent Overstreet maxsector -= bio->bi_iter.bi_sector; 297259d43914SAkinobu Mita if (likely((bio->bi_iter.bi_size >> 9) <= maxsector)) 297357302e0dSLinus Torvalds return; 297457302e0dSLinus Torvalds 297559d43914SAkinobu Mita /* Uhhuh. We've got a bio that straddles the device size! */ 297659d43914SAkinobu Mita truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9); 297757302e0dSLinus Torvalds 297857302e0dSLinus Torvalds /* Truncate the bio.. */ 297959d43914SAkinobu Mita bio->bi_iter.bi_size -= truncated_bytes; 298059d43914SAkinobu Mita bvec->bv_len -= truncated_bytes; 298157302e0dSLinus Torvalds 298257302e0dSLinus Torvalds /* ..and clear the end of the buffer for reads */ 298327d7c2a0SDan Carpenter if ((rw & RW_MASK) == READ) { 298459d43914SAkinobu Mita zero_user(bvec->bv_page, bvec->bv_offset + bvec->bv_len, 298559d43914SAkinobu Mita truncated_bytes); 298657302e0dSLinus Torvalds } 298757302e0dSLinus Torvalds } 298857302e0dSLinus Torvalds 2989b16b1debSTejun Heo static int submit_bh_wbc(int rw, struct buffer_head *bh, 2990b16b1debSTejun Heo unsigned long bio_flags, struct writeback_control *wbc) 29911da177e4SLinus Torvalds { 29921da177e4SLinus Torvalds struct bio *bio; 29931da177e4SLinus Torvalds 29941da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 29951da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 29961da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 29978fb0e342SAneesh Kumar K.V BUG_ON(buffer_delay(bh)); 29988fb0e342SAneesh Kumar K.V BUG_ON(buffer_unwritten(bh)); 29991da177e4SLinus Torvalds 300048fd4f93SJens Axboe /* 300148fd4f93SJens Axboe * Only clear out a write error when rewriting 30021da177e4SLinus Torvalds */ 300348fd4f93SJens Axboe if (test_set_buffer_req(bh) && (rw & WRITE)) 30041da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 30051da177e4SLinus Torvalds 30061da177e4SLinus Torvalds /* 30071da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 30081da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 30091da177e4SLinus Torvalds */ 30101da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 30111da177e4SLinus Torvalds 30122a814908STejun Heo if (wbc) { 3013b16b1debSTejun Heo wbc_init_bio(wbc, bio); 30142a814908STejun Heo wbc_account_io(wbc, bh->b_page, bh->b_size); 30152a814908STejun Heo } 3016bafc0dbaSTejun Heo 30174f024f37SKent Overstreet bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); 30181da177e4SLinus Torvalds bio->bi_bdev = bh->b_bdev; 30191da177e4SLinus Torvalds 30206cf66b4cSKent Overstreet bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh)); 30216cf66b4cSKent Overstreet BUG_ON(bio->bi_iter.bi_size != bh->b_size); 30221da177e4SLinus Torvalds 30231da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 30241da177e4SLinus Torvalds bio->bi_private = bh; 302571368511SDarrick J. Wong bio->bi_flags |= bio_flags; 30261da177e4SLinus Torvalds 302757302e0dSLinus Torvalds /* Take care of bh's that straddle the end of the device */ 302859d43914SAkinobu Mita guard_bio_eod(rw, bio); 302957302e0dSLinus Torvalds 3030877f962cSTheodore Ts'o if (buffer_meta(bh)) 3031877f962cSTheodore Ts'o rw |= REQ_META; 3032877f962cSTheodore Ts'o if (buffer_prio(bh)) 3033877f962cSTheodore Ts'o rw |= REQ_PRIO; 3034877f962cSTheodore Ts'o 30351da177e4SLinus Torvalds submit_bio(rw, bio); 3036f6454b04SJulia Lawall return 0; 30371da177e4SLinus Torvalds } 3038bafc0dbaSTejun Heo 3039bafc0dbaSTejun Heo int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags) 3040bafc0dbaSTejun Heo { 3041b16b1debSTejun Heo return submit_bh_wbc(rw, bh, bio_flags, NULL); 3042bafc0dbaSTejun Heo } 304371368511SDarrick J. Wong EXPORT_SYMBOL_GPL(_submit_bh); 304471368511SDarrick J. Wong 304571368511SDarrick J. Wong int submit_bh(int rw, struct buffer_head *bh) 304671368511SDarrick J. Wong { 3047b16b1debSTejun Heo return submit_bh_wbc(rw, bh, 0, NULL); 304871368511SDarrick J. Wong } 30491fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(submit_bh); 30501da177e4SLinus Torvalds 30511da177e4SLinus Torvalds /** 30521da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 30539cb569d6SChristoph Hellwig * @rw: whether to %READ or %WRITE or maybe %READA (readahead) 30541da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 30551da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 30561da177e4SLinus Torvalds * 3057a7662236SJan Kara * ll_rw_block() takes an array of pointers to &struct buffer_heads, and 3058a7662236SJan Kara * requests an I/O operation on them, either a %READ or a %WRITE. The third 30599cb569d6SChristoph Hellwig * %READA option is described in the documentation for generic_make_request() 30609cb569d6SChristoph Hellwig * which ll_rw_block() calls. 30611da177e4SLinus Torvalds * 30621da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 30639cb569d6SChristoph Hellwig * BH_Lock state bit), any buffer that appears to be clean when doing a write 30649cb569d6SChristoph Hellwig * request, and any buffer that appears to be up-to-date when doing read 30659cb569d6SChristoph Hellwig * request. Further it marks as clean buffers that are processed for 30669cb569d6SChristoph Hellwig * writing (the buffer cache won't assume that they are actually clean 30679cb569d6SChristoph Hellwig * until the buffer gets unlocked). 30681da177e4SLinus Torvalds * 30691da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 3070e227867fSMasanari Iida * the buffer up-to-date (if appropriate), unlocks the buffer and wakes 30711da177e4SLinus Torvalds * any waiters. 30721da177e4SLinus Torvalds * 30731da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 30741da177e4SLinus Torvalds * multiple of the current approved size for the device. 30751da177e4SLinus Torvalds */ 30761da177e4SLinus Torvalds void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) 30771da177e4SLinus Torvalds { 30781da177e4SLinus Torvalds int i; 30791da177e4SLinus Torvalds 30801da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 30811da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 30821da177e4SLinus Torvalds 30839cb569d6SChristoph Hellwig if (!trylock_buffer(bh)) 30841da177e4SLinus Torvalds continue; 30859cb569d6SChristoph Hellwig if (rw == WRITE) { 30861da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 308776c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 3088e60e5c50SOGAWA Hirofumi get_bh(bh); 30891da177e4SLinus Torvalds submit_bh(WRITE, bh); 30901da177e4SLinus Torvalds continue; 30911da177e4SLinus Torvalds } 30921da177e4SLinus Torvalds } else { 30931da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 309476c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 3095e60e5c50SOGAWA Hirofumi get_bh(bh); 30961da177e4SLinus Torvalds submit_bh(rw, bh); 30971da177e4SLinus Torvalds continue; 30981da177e4SLinus Torvalds } 30991da177e4SLinus Torvalds } 31001da177e4SLinus Torvalds unlock_buffer(bh); 31011da177e4SLinus Torvalds } 31021da177e4SLinus Torvalds } 31031fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(ll_rw_block); 31041da177e4SLinus Torvalds 31059cb569d6SChristoph Hellwig void write_dirty_buffer(struct buffer_head *bh, int rw) 31069cb569d6SChristoph Hellwig { 31079cb569d6SChristoph Hellwig lock_buffer(bh); 31089cb569d6SChristoph Hellwig if (!test_clear_buffer_dirty(bh)) { 31099cb569d6SChristoph Hellwig unlock_buffer(bh); 31109cb569d6SChristoph Hellwig return; 31119cb569d6SChristoph Hellwig } 31129cb569d6SChristoph Hellwig bh->b_end_io = end_buffer_write_sync; 31139cb569d6SChristoph Hellwig get_bh(bh); 31149cb569d6SChristoph Hellwig submit_bh(rw, bh); 31159cb569d6SChristoph Hellwig } 31169cb569d6SChristoph Hellwig EXPORT_SYMBOL(write_dirty_buffer); 31179cb569d6SChristoph Hellwig 31181da177e4SLinus Torvalds /* 31191da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 31201da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 31211da177e4SLinus Torvalds * the buffer_head. 31221da177e4SLinus Torvalds */ 312387e99511SChristoph Hellwig int __sync_dirty_buffer(struct buffer_head *bh, int rw) 31241da177e4SLinus Torvalds { 31251da177e4SLinus Torvalds int ret = 0; 31261da177e4SLinus Torvalds 31271da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 31281da177e4SLinus Torvalds lock_buffer(bh); 31291da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 31301da177e4SLinus Torvalds get_bh(bh); 31311da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 313287e99511SChristoph Hellwig ret = submit_bh(rw, bh); 31331da177e4SLinus Torvalds wait_on_buffer(bh); 31341da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 31351da177e4SLinus Torvalds ret = -EIO; 31361da177e4SLinus Torvalds } else { 31371da177e4SLinus Torvalds unlock_buffer(bh); 31381da177e4SLinus Torvalds } 31391da177e4SLinus Torvalds return ret; 31401da177e4SLinus Torvalds } 314187e99511SChristoph Hellwig EXPORT_SYMBOL(__sync_dirty_buffer); 314287e99511SChristoph Hellwig 314387e99511SChristoph Hellwig int sync_dirty_buffer(struct buffer_head *bh) 314487e99511SChristoph Hellwig { 314587e99511SChristoph Hellwig return __sync_dirty_buffer(bh, WRITE_SYNC); 314687e99511SChristoph Hellwig } 31471fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(sync_dirty_buffer); 31481da177e4SLinus Torvalds 31491da177e4SLinus Torvalds /* 31501da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 31511da177e4SLinus Torvalds * are unused, and releases them if so. 31521da177e4SLinus Torvalds * 31531da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 31541da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 31551da177e4SLinus Torvalds * 31561da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 31571da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 31581da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 31591da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 31601da177e4SLinus Torvalds * filesystem data on the same device. 31611da177e4SLinus Torvalds * 31621da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 31631da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 31641da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 31651da177e4SLinus Torvalds * private_lock. 31661da177e4SLinus Torvalds * 31671da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 31681da177e4SLinus Torvalds */ 31691da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 31701da177e4SLinus Torvalds { 31711da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 31721da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 31731da177e4SLinus Torvalds } 31741da177e4SLinus Torvalds 31751da177e4SLinus Torvalds static int 31761da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 31771da177e4SLinus Torvalds { 31781da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 31791da177e4SLinus Torvalds struct buffer_head *bh; 31801da177e4SLinus Torvalds 31811da177e4SLinus Torvalds bh = head; 31821da177e4SLinus Torvalds do { 3183de7d5a3bSakpm@osdl.org if (buffer_write_io_error(bh) && page->mapping) 31841da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 31851da177e4SLinus Torvalds if (buffer_busy(bh)) 31861da177e4SLinus Torvalds goto failed; 31871da177e4SLinus Torvalds bh = bh->b_this_page; 31881da177e4SLinus Torvalds } while (bh != head); 31891da177e4SLinus Torvalds 31901da177e4SLinus Torvalds do { 31911da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 31921da177e4SLinus Torvalds 3193535ee2fbSJan Kara if (bh->b_assoc_map) 31941da177e4SLinus Torvalds __remove_assoc_queue(bh); 31951da177e4SLinus Torvalds bh = next; 31961da177e4SLinus Torvalds } while (bh != head); 31971da177e4SLinus Torvalds *buffers_to_free = head; 31981da177e4SLinus Torvalds __clear_page_buffers(page); 31991da177e4SLinus Torvalds return 1; 32001da177e4SLinus Torvalds failed: 32011da177e4SLinus Torvalds return 0; 32021da177e4SLinus Torvalds } 32031da177e4SLinus Torvalds 32041da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 32051da177e4SLinus Torvalds { 32061da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 32071da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 32081da177e4SLinus Torvalds int ret = 0; 32091da177e4SLinus Torvalds 32101da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 3211ecdfc978SLinus Torvalds if (PageWriteback(page)) 32121da177e4SLinus Torvalds return 0; 32131da177e4SLinus Torvalds 32141da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 32151da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 32161da177e4SLinus Torvalds goto out; 32171da177e4SLinus Torvalds } 32181da177e4SLinus Torvalds 32191da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 32201da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 3221ecdfc978SLinus Torvalds 3222ecdfc978SLinus Torvalds /* 3223ecdfc978SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 3224ecdfc978SLinus Torvalds * then we can have clean buffers against a dirty page. We 3225ecdfc978SLinus Torvalds * clean the page here; otherwise the VM will never notice 3226ecdfc978SLinus Torvalds * that the filesystem did any IO at all. 3227ecdfc978SLinus Torvalds * 3228ecdfc978SLinus Torvalds * Also, during truncate, discard_buffer will have marked all 3229ecdfc978SLinus Torvalds * the page's buffers clean. We discover that here and clean 3230ecdfc978SLinus Torvalds * the page also. 323187df7241SNick Piggin * 323287df7241SNick Piggin * private_lock must be held over this entire operation in order 323387df7241SNick Piggin * to synchronise against __set_page_dirty_buffers and prevent the 323487df7241SNick Piggin * dirty bit from being lost. 3235ecdfc978SLinus Torvalds */ 323611f81becSTejun Heo if (ret) 323711f81becSTejun Heo cancel_dirty_page(page); 323887df7241SNick Piggin spin_unlock(&mapping->private_lock); 32391da177e4SLinus Torvalds out: 32401da177e4SLinus Torvalds if (buffers_to_free) { 32411da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 32421da177e4SLinus Torvalds 32431da177e4SLinus Torvalds do { 32441da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 32451da177e4SLinus Torvalds free_buffer_head(bh); 32461da177e4SLinus Torvalds bh = next; 32471da177e4SLinus Torvalds } while (bh != buffers_to_free); 32481da177e4SLinus Torvalds } 32491da177e4SLinus Torvalds return ret; 32501da177e4SLinus Torvalds } 32511da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 32521da177e4SLinus Torvalds 32531da177e4SLinus Torvalds /* 32541da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 32551da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 32561da177e4SLinus Torvalds * 32571da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 32585b0830cbSJens Axboe * The `flush-X' kernel threads fully replace bdflush daemons and this call. 32591da177e4SLinus Torvalds */ 3260bdc480e3SHeiko Carstens SYSCALL_DEFINE2(bdflush, int, func, long, data) 32611da177e4SLinus Torvalds { 32621da177e4SLinus Torvalds static int msg_count; 32631da177e4SLinus Torvalds 32641da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 32651da177e4SLinus Torvalds return -EPERM; 32661da177e4SLinus Torvalds 32671da177e4SLinus Torvalds if (msg_count < 5) { 32681da177e4SLinus Torvalds msg_count++; 32691da177e4SLinus Torvalds printk(KERN_INFO 32701da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 32711da177e4SLinus Torvalds " system call\n", current->comm); 32721da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 32731da177e4SLinus Torvalds } 32741da177e4SLinus Torvalds 32751da177e4SLinus Torvalds if (func == 1) 32761da177e4SLinus Torvalds do_exit(0); 32771da177e4SLinus Torvalds return 0; 32781da177e4SLinus Torvalds } 32791da177e4SLinus Torvalds 32801da177e4SLinus Torvalds /* 32811da177e4SLinus Torvalds * Buffer-head allocation 32821da177e4SLinus Torvalds */ 3283a0a9b043SShai Fultheim static struct kmem_cache *bh_cachep __read_mostly; 32841da177e4SLinus Torvalds 32851da177e4SLinus Torvalds /* 32861da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 32871da177e4SLinus Torvalds * stripping them in writeback. 32881da177e4SLinus Torvalds */ 328943be594aSZhang Yanfei static unsigned long max_buffer_heads; 32901da177e4SLinus Torvalds 32911da177e4SLinus Torvalds int buffer_heads_over_limit; 32921da177e4SLinus Torvalds 32931da177e4SLinus Torvalds struct bh_accounting { 32941da177e4SLinus Torvalds int nr; /* Number of live bh's */ 32951da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 32961da177e4SLinus Torvalds }; 32971da177e4SLinus Torvalds 32981da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 32991da177e4SLinus Torvalds 33001da177e4SLinus Torvalds static void recalc_bh_state(void) 33011da177e4SLinus Torvalds { 33021da177e4SLinus Torvalds int i; 33031da177e4SLinus Torvalds int tot = 0; 33041da177e4SLinus Torvalds 3305ee1be862SChristoph Lameter if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) 33061da177e4SLinus Torvalds return; 3307c7b92516SChristoph Lameter __this_cpu_write(bh_accounting.ratelimit, 0); 33088a143426SEric Dumazet for_each_online_cpu(i) 33091da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 33101da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 33111da177e4SLinus Torvalds } 33121da177e4SLinus Torvalds 3313dd0fc66fSAl Viro struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) 33141da177e4SLinus Torvalds { 3315019b4d12SRichard Kennedy struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); 33161da177e4SLinus Torvalds if (ret) { 3317a35afb83SChristoph Lameter INIT_LIST_HEAD(&ret->b_assoc_buffers); 3318c7b92516SChristoph Lameter preempt_disable(); 3319c7b92516SChristoph Lameter __this_cpu_inc(bh_accounting.nr); 33201da177e4SLinus Torvalds recalc_bh_state(); 3321c7b92516SChristoph Lameter preempt_enable(); 33221da177e4SLinus Torvalds } 33231da177e4SLinus Torvalds return ret; 33241da177e4SLinus Torvalds } 33251da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 33261da177e4SLinus Torvalds 33271da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 33281da177e4SLinus Torvalds { 33291da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 33301da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 3331c7b92516SChristoph Lameter preempt_disable(); 3332c7b92516SChristoph Lameter __this_cpu_dec(bh_accounting.nr); 33331da177e4SLinus Torvalds recalc_bh_state(); 3334c7b92516SChristoph Lameter preempt_enable(); 33351da177e4SLinus Torvalds } 33361da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 33371da177e4SLinus Torvalds 33381da177e4SLinus Torvalds static void buffer_exit_cpu(int cpu) 33391da177e4SLinus Torvalds { 33401da177e4SLinus Torvalds int i; 33411da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 33421da177e4SLinus Torvalds 33431da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 33441da177e4SLinus Torvalds brelse(b->bhs[i]); 33451da177e4SLinus Torvalds b->bhs[i] = NULL; 33461da177e4SLinus Torvalds } 3347c7b92516SChristoph Lameter this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); 33488a143426SEric Dumazet per_cpu(bh_accounting, cpu).nr = 0; 33491da177e4SLinus Torvalds } 33501da177e4SLinus Torvalds 33511da177e4SLinus Torvalds static int buffer_cpu_notify(struct notifier_block *self, 33521da177e4SLinus Torvalds unsigned long action, void *hcpu) 33531da177e4SLinus Torvalds { 33548bb78442SRafael J. Wysocki if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) 33551da177e4SLinus Torvalds buffer_exit_cpu((unsigned long)hcpu); 33561da177e4SLinus Torvalds return NOTIFY_OK; 33571da177e4SLinus Torvalds } 33581da177e4SLinus Torvalds 3359389d1b08SAneesh Kumar K.V /** 3360a6b91919SRandy Dunlap * bh_uptodate_or_lock - Test whether the buffer is uptodate 3361389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3362389d1b08SAneesh Kumar K.V * 3363389d1b08SAneesh Kumar K.V * Return true if the buffer is up-to-date and false, 3364389d1b08SAneesh Kumar K.V * with the buffer locked, if not. 3365389d1b08SAneesh Kumar K.V */ 3366389d1b08SAneesh Kumar K.V int bh_uptodate_or_lock(struct buffer_head *bh) 3367389d1b08SAneesh Kumar K.V { 3368389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) { 3369389d1b08SAneesh Kumar K.V lock_buffer(bh); 3370389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) 3371389d1b08SAneesh Kumar K.V return 0; 3372389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3373389d1b08SAneesh Kumar K.V } 3374389d1b08SAneesh Kumar K.V return 1; 3375389d1b08SAneesh Kumar K.V } 3376389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_uptodate_or_lock); 3377389d1b08SAneesh Kumar K.V 3378389d1b08SAneesh Kumar K.V /** 3379a6b91919SRandy Dunlap * bh_submit_read - Submit a locked buffer for reading 3380389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3381389d1b08SAneesh Kumar K.V * 3382389d1b08SAneesh Kumar K.V * Returns zero on success and -EIO on error. 3383389d1b08SAneesh Kumar K.V */ 3384389d1b08SAneesh Kumar K.V int bh_submit_read(struct buffer_head *bh) 3385389d1b08SAneesh Kumar K.V { 3386389d1b08SAneesh Kumar K.V BUG_ON(!buffer_locked(bh)); 3387389d1b08SAneesh Kumar K.V 3388389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) { 3389389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3390389d1b08SAneesh Kumar K.V return 0; 3391389d1b08SAneesh Kumar K.V } 3392389d1b08SAneesh Kumar K.V 3393389d1b08SAneesh Kumar K.V get_bh(bh); 3394389d1b08SAneesh Kumar K.V bh->b_end_io = end_buffer_read_sync; 3395389d1b08SAneesh Kumar K.V submit_bh(READ, bh); 3396389d1b08SAneesh Kumar K.V wait_on_buffer(bh); 3397389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) 3398389d1b08SAneesh Kumar K.V return 0; 3399389d1b08SAneesh Kumar K.V return -EIO; 3400389d1b08SAneesh Kumar K.V } 3401389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_submit_read); 3402389d1b08SAneesh Kumar K.V 34031da177e4SLinus Torvalds void __init buffer_init(void) 34041da177e4SLinus Torvalds { 340543be594aSZhang Yanfei unsigned long nrpages; 34061da177e4SLinus Torvalds 3407b98938c3SChristoph Lameter bh_cachep = kmem_cache_create("buffer_head", 3408b98938c3SChristoph Lameter sizeof(struct buffer_head), 0, 3409b98938c3SChristoph Lameter (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| 3410b98938c3SChristoph Lameter SLAB_MEM_SPREAD), 3411019b4d12SRichard Kennedy NULL); 34121da177e4SLinus Torvalds 34131da177e4SLinus Torvalds /* 34141da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 34151da177e4SLinus Torvalds */ 34161da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 34171da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 34181da177e4SLinus Torvalds hotcpu_notifier(buffer_cpu_notify, 0); 34191da177e4SLinus Torvalds } 3420