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> 24ae259a9cSChristoph Hellwig #include <linux/iomap.h> 251da177e4SLinus Torvalds #include <linux/mm.h> 261da177e4SLinus Torvalds #include <linux/percpu.h> 271da177e4SLinus Torvalds #include <linux/slab.h> 2816f7e0feSRandy Dunlap #include <linux/capability.h> 291da177e4SLinus Torvalds #include <linux/blkdev.h> 301da177e4SLinus Torvalds #include <linux/file.h> 311da177e4SLinus Torvalds #include <linux/quotaops.h> 321da177e4SLinus Torvalds #include <linux/highmem.h> 33630d9c47SPaul Gortmaker #include <linux/export.h> 34bafc0dbaSTejun Heo #include <linux/backing-dev.h> 351da177e4SLinus Torvalds #include <linux/writeback.h> 361da177e4SLinus Torvalds #include <linux/hash.h> 371da177e4SLinus Torvalds #include <linux/suspend.h> 381da177e4SLinus Torvalds #include <linux/buffer_head.h> 3955e829afSAndrew Morton #include <linux/task_io_accounting_ops.h> 401da177e4SLinus Torvalds #include <linux/bio.h> 411da177e4SLinus Torvalds #include <linux/notifier.h> 421da177e4SLinus Torvalds #include <linux/cpu.h> 431da177e4SLinus Torvalds #include <linux/bitops.h> 441da177e4SLinus Torvalds #include <linux/mpage.h> 45fb1c8f93SIngo Molnar #include <linux/bit_spinlock.h> 465305cb83STejun Heo #include <trace/events/block.h> 471da177e4SLinus Torvalds 481da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); 492a222ca9SMike Christie static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, 50bafc0dbaSTejun Heo unsigned long bio_flags, 51b16b1debSTejun Heo struct writeback_control *wbc); 521da177e4SLinus Torvalds 531da177e4SLinus Torvalds #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) 541da177e4SLinus Torvalds 55a3f3c29cSYan Hong void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) 561da177e4SLinus Torvalds { 571da177e4SLinus Torvalds bh->b_end_io = handler; 581da177e4SLinus Torvalds bh->b_private = private; 591da177e4SLinus Torvalds } 601fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(init_buffer); 611da177e4SLinus Torvalds 62f0059afdSTejun Heo inline void touch_buffer(struct buffer_head *bh) 63f0059afdSTejun Heo { 645305cb83STejun Heo trace_block_touch_buffer(bh); 65f0059afdSTejun Heo mark_page_accessed(bh->b_page); 66f0059afdSTejun Heo } 67f0059afdSTejun Heo EXPORT_SYMBOL(touch_buffer); 68f0059afdSTejun Heo 69fc9b52cdSHarvey Harrison void __lock_buffer(struct buffer_head *bh) 701da177e4SLinus Torvalds { 7174316201SNeilBrown wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 721da177e4SLinus Torvalds } 731da177e4SLinus Torvalds EXPORT_SYMBOL(__lock_buffer); 741da177e4SLinus Torvalds 75fc9b52cdSHarvey Harrison void unlock_buffer(struct buffer_head *bh) 761da177e4SLinus Torvalds { 7751b07fc3SNick Piggin clear_bit_unlock(BH_Lock, &bh->b_state); 784e857c58SPeter Zijlstra smp_mb__after_atomic(); 791da177e4SLinus Torvalds wake_up_bit(&bh->b_state, BH_Lock); 801da177e4SLinus Torvalds } 811fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(unlock_buffer); 821da177e4SLinus Torvalds 831da177e4SLinus Torvalds /* 84b4597226SMel Gorman * Returns if the page has dirty or writeback buffers. If all the buffers 85b4597226SMel Gorman * are unlocked and clean then the PageDirty information is stale. If 86b4597226SMel Gorman * any of the pages are locked, it is assumed they are locked for IO. 87b4597226SMel Gorman */ 88b4597226SMel Gorman void buffer_check_dirty_writeback(struct page *page, 89b4597226SMel Gorman bool *dirty, bool *writeback) 90b4597226SMel Gorman { 91b4597226SMel Gorman struct buffer_head *head, *bh; 92b4597226SMel Gorman *dirty = false; 93b4597226SMel Gorman *writeback = false; 94b4597226SMel Gorman 95b4597226SMel Gorman BUG_ON(!PageLocked(page)); 96b4597226SMel Gorman 97b4597226SMel Gorman if (!page_has_buffers(page)) 98b4597226SMel Gorman return; 99b4597226SMel Gorman 100b4597226SMel Gorman if (PageWriteback(page)) 101b4597226SMel Gorman *writeback = true; 102b4597226SMel Gorman 103b4597226SMel Gorman head = page_buffers(page); 104b4597226SMel Gorman bh = head; 105b4597226SMel Gorman do { 106b4597226SMel Gorman if (buffer_locked(bh)) 107b4597226SMel Gorman *writeback = true; 108b4597226SMel Gorman 109b4597226SMel Gorman if (buffer_dirty(bh)) 110b4597226SMel Gorman *dirty = true; 111b4597226SMel Gorman 112b4597226SMel Gorman bh = bh->b_this_page; 113b4597226SMel Gorman } while (bh != head); 114b4597226SMel Gorman } 115b4597226SMel Gorman EXPORT_SYMBOL(buffer_check_dirty_writeback); 116b4597226SMel Gorman 117b4597226SMel Gorman /* 1181da177e4SLinus Torvalds * Block until a buffer comes unlocked. This doesn't stop it 1191da177e4SLinus Torvalds * from becoming locked again - you have to lock it yourself 1201da177e4SLinus Torvalds * if you want to preserve its state. 1211da177e4SLinus Torvalds */ 1221da177e4SLinus Torvalds void __wait_on_buffer(struct buffer_head * bh) 1231da177e4SLinus Torvalds { 12474316201SNeilBrown wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 1251da177e4SLinus Torvalds } 1261fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__wait_on_buffer); 1271da177e4SLinus Torvalds 1281da177e4SLinus Torvalds static void 1291da177e4SLinus Torvalds __clear_page_buffers(struct page *page) 1301da177e4SLinus Torvalds { 1311da177e4SLinus Torvalds ClearPagePrivate(page); 1324c21e2f2SHugh Dickins set_page_private(page, 0); 13309cbfeafSKirill A. Shutemov put_page(page); 1341da177e4SLinus Torvalds } 1351da177e4SLinus Torvalds 136b744c2acSRobert Elliott static void buffer_io_error(struct buffer_head *bh, char *msg) 1371da177e4SLinus Torvalds { 138432f16e6SRobert Elliott if (!test_bit(BH_Quiet, &bh->b_state)) 139432f16e6SRobert Elliott printk_ratelimited(KERN_ERR 140a1c6f057SDmitry Monakhov "Buffer I/O error on dev %pg, logical block %llu%s\n", 141a1c6f057SDmitry Monakhov bh->b_bdev, (unsigned long long)bh->b_blocknr, msg); 1421da177e4SLinus Torvalds } 1431da177e4SLinus Torvalds 1441da177e4SLinus Torvalds /* 14568671f35SDmitry Monakhov * End-of-IO handler helper function which does not touch the bh after 14668671f35SDmitry Monakhov * unlocking it. 14768671f35SDmitry Monakhov * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but 14868671f35SDmitry Monakhov * a race there is benign: unlock_buffer() only use the bh's address for 14968671f35SDmitry Monakhov * hashing after unlocking the buffer, so it doesn't actually touch the bh 15068671f35SDmitry Monakhov * itself. 1511da177e4SLinus Torvalds */ 15268671f35SDmitry Monakhov static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) 1531da177e4SLinus Torvalds { 1541da177e4SLinus Torvalds if (uptodate) { 1551da177e4SLinus Torvalds set_buffer_uptodate(bh); 1561da177e4SLinus Torvalds } else { 15770246286SChristoph Hellwig /* This happens, due to failed read-ahead attempts. */ 1581da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1591da177e4SLinus Torvalds } 1601da177e4SLinus Torvalds unlock_buffer(bh); 16168671f35SDmitry Monakhov } 16268671f35SDmitry Monakhov 16368671f35SDmitry Monakhov /* 16468671f35SDmitry Monakhov * Default synchronous end-of-IO handler.. Just mark it up-to-date and 16568671f35SDmitry Monakhov * unlock the buffer. This is what ll_rw_block uses too. 16668671f35SDmitry Monakhov */ 16768671f35SDmitry Monakhov void end_buffer_read_sync(struct buffer_head *bh, int uptodate) 16868671f35SDmitry Monakhov { 16968671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 1701da177e4SLinus Torvalds put_bh(bh); 1711da177e4SLinus Torvalds } 1721fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_read_sync); 1731da177e4SLinus Torvalds 1741da177e4SLinus Torvalds void end_buffer_write_sync(struct buffer_head *bh, int uptodate) 1751da177e4SLinus Torvalds { 1761da177e4SLinus Torvalds if (uptodate) { 1771da177e4SLinus Torvalds set_buffer_uptodate(bh); 1781da177e4SLinus Torvalds } else { 179b744c2acSRobert Elliott buffer_io_error(bh, ", lost sync page write"); 1801da177e4SLinus Torvalds set_buffer_write_io_error(bh); 1811da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1821da177e4SLinus Torvalds } 1831da177e4SLinus Torvalds unlock_buffer(bh); 1841da177e4SLinus Torvalds put_bh(bh); 1851da177e4SLinus Torvalds } 1861fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_write_sync); 1871da177e4SLinus Torvalds 1881da177e4SLinus Torvalds /* 1891da177e4SLinus Torvalds * Various filesystems appear to want __find_get_block to be non-blocking. 1901da177e4SLinus Torvalds * But it's the page lock which protects the buffers. To get around this, 1911da177e4SLinus Torvalds * we get exclusion from try_to_free_buffers with the blockdev mapping's 1921da177e4SLinus Torvalds * private_lock. 1931da177e4SLinus Torvalds * 1941da177e4SLinus Torvalds * Hack idea: for the blockdev mapping, i_bufferlist_lock contention 1951da177e4SLinus Torvalds * may be quite high. This code could TryLock the page, and if that 1961da177e4SLinus Torvalds * succeeds, there is no need to take private_lock. (But if 1971da177e4SLinus Torvalds * private_lock is contended then so is mapping->tree_lock). 1981da177e4SLinus Torvalds */ 1991da177e4SLinus Torvalds static struct buffer_head * 200385fd4c5SCoywolf Qi Hunt __find_get_block_slow(struct block_device *bdev, sector_t block) 2011da177e4SLinus Torvalds { 2021da177e4SLinus Torvalds struct inode *bd_inode = bdev->bd_inode; 2031da177e4SLinus Torvalds struct address_space *bd_mapping = bd_inode->i_mapping; 2041da177e4SLinus Torvalds struct buffer_head *ret = NULL; 2051da177e4SLinus Torvalds pgoff_t index; 2061da177e4SLinus Torvalds struct buffer_head *bh; 2071da177e4SLinus Torvalds struct buffer_head *head; 2081da177e4SLinus Torvalds struct page *page; 2091da177e4SLinus Torvalds int all_mapped = 1; 2101da177e4SLinus Torvalds 21109cbfeafSKirill A. Shutemov index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); 2122457aec6SMel Gorman page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED); 2131da177e4SLinus Torvalds if (!page) 2141da177e4SLinus Torvalds goto out; 2151da177e4SLinus Torvalds 2161da177e4SLinus Torvalds spin_lock(&bd_mapping->private_lock); 2171da177e4SLinus Torvalds if (!page_has_buffers(page)) 2181da177e4SLinus Torvalds goto out_unlock; 2191da177e4SLinus Torvalds head = page_buffers(page); 2201da177e4SLinus Torvalds bh = head; 2211da177e4SLinus Torvalds do { 22297f76d3dSNikanth Karthikesan if (!buffer_mapped(bh)) 22397f76d3dSNikanth Karthikesan all_mapped = 0; 22497f76d3dSNikanth Karthikesan else if (bh->b_blocknr == block) { 2251da177e4SLinus Torvalds ret = bh; 2261da177e4SLinus Torvalds get_bh(bh); 2271da177e4SLinus Torvalds goto out_unlock; 2281da177e4SLinus Torvalds } 2291da177e4SLinus Torvalds bh = bh->b_this_page; 2301da177e4SLinus Torvalds } while (bh != head); 2311da177e4SLinus Torvalds 2321da177e4SLinus Torvalds /* we might be here because some of the buffers on this page are 2331da177e4SLinus Torvalds * not mapped. This is due to various races between 2341da177e4SLinus Torvalds * file io on the block device and getblk. It gets dealt with 2351da177e4SLinus Torvalds * elsewhere, don't buffer_error if we had some unmapped buffers 2361da177e4SLinus Torvalds */ 2371da177e4SLinus Torvalds if (all_mapped) { 2381da177e4SLinus Torvalds printk("__find_get_block_slow() failed. " 2391da177e4SLinus Torvalds "block=%llu, b_blocknr=%llu\n", 240205f87f6SBadari Pulavarty (unsigned long long)block, 241205f87f6SBadari Pulavarty (unsigned long long)bh->b_blocknr); 242205f87f6SBadari Pulavarty printk("b_state=0x%08lx, b_size=%zu\n", 243205f87f6SBadari Pulavarty bh->b_state, bh->b_size); 244a1c6f057SDmitry Monakhov printk("device %pg blocksize: %d\n", bdev, 24572a2ebd8STao Ma 1 << bd_inode->i_blkbits); 2461da177e4SLinus Torvalds } 2471da177e4SLinus Torvalds out_unlock: 2481da177e4SLinus Torvalds spin_unlock(&bd_mapping->private_lock); 24909cbfeafSKirill A. Shutemov put_page(page); 2501da177e4SLinus Torvalds out: 2511da177e4SLinus Torvalds return ret; 2521da177e4SLinus Torvalds } 2531da177e4SLinus Torvalds 2541da177e4SLinus Torvalds /* 2555b0830cbSJens Axboe * Kick the writeback threads then try to free up some ZONE_NORMAL memory. 2561da177e4SLinus Torvalds */ 2571da177e4SLinus Torvalds static void free_more_memory(void) 2581da177e4SLinus Torvalds { 259c33d6c06SMel Gorman struct zoneref *z; 2600e88460dSMel Gorman int nid; 2611da177e4SLinus Torvalds 2620e175a18SCurt Wohlgemuth wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM); 2631da177e4SLinus Torvalds yield(); 2641da177e4SLinus Torvalds 2650e88460dSMel Gorman for_each_online_node(nid) { 266c33d6c06SMel Gorman 267c33d6c06SMel Gorman z = first_zones_zonelist(node_zonelist(nid, GFP_NOFS), 268c33d6c06SMel Gorman gfp_zone(GFP_NOFS), NULL); 269c33d6c06SMel Gorman if (z->zone) 27054a6eb5cSMel Gorman try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0, 271327c0e96SKAMEZAWA Hiroyuki GFP_NOFS, NULL); 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds } 2741da177e4SLinus Torvalds 2751da177e4SLinus Torvalds /* 2761da177e4SLinus Torvalds * I/O completion handler for block_read_full_page() - pages 2771da177e4SLinus Torvalds * which come unlocked at the end of I/O. 2781da177e4SLinus Torvalds */ 2791da177e4SLinus Torvalds static void end_buffer_async_read(struct buffer_head *bh, int uptodate) 2801da177e4SLinus Torvalds { 2811da177e4SLinus Torvalds unsigned long flags; 282a3972203SNick Piggin struct buffer_head *first; 2831da177e4SLinus Torvalds struct buffer_head *tmp; 2841da177e4SLinus Torvalds struct page *page; 2851da177e4SLinus Torvalds int page_uptodate = 1; 2861da177e4SLinus Torvalds 2871da177e4SLinus Torvalds BUG_ON(!buffer_async_read(bh)); 2881da177e4SLinus Torvalds 2891da177e4SLinus Torvalds page = bh->b_page; 2901da177e4SLinus Torvalds if (uptodate) { 2911da177e4SLinus Torvalds set_buffer_uptodate(bh); 2921da177e4SLinus Torvalds } else { 2931da177e4SLinus Torvalds clear_buffer_uptodate(bh); 294b744c2acSRobert Elliott buffer_io_error(bh, ", async page read"); 2951da177e4SLinus Torvalds SetPageError(page); 2961da177e4SLinus Torvalds } 2971da177e4SLinus Torvalds 2981da177e4SLinus Torvalds /* 2991da177e4SLinus Torvalds * Be _very_ careful from here on. Bad things can happen if 3001da177e4SLinus Torvalds * two buffer heads end IO at almost the same time and both 3011da177e4SLinus Torvalds * decide that the page is now completely done. 3021da177e4SLinus Torvalds */ 303a3972203SNick Piggin first = page_buffers(page); 304a3972203SNick Piggin local_irq_save(flags); 305a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 3061da177e4SLinus Torvalds clear_buffer_async_read(bh); 3071da177e4SLinus Torvalds unlock_buffer(bh); 3081da177e4SLinus Torvalds tmp = bh; 3091da177e4SLinus Torvalds do { 3101da177e4SLinus Torvalds if (!buffer_uptodate(tmp)) 3111da177e4SLinus Torvalds page_uptodate = 0; 3121da177e4SLinus Torvalds if (buffer_async_read(tmp)) { 3131da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3141da177e4SLinus Torvalds goto still_busy; 3151da177e4SLinus Torvalds } 3161da177e4SLinus Torvalds tmp = tmp->b_this_page; 3171da177e4SLinus Torvalds } while (tmp != bh); 318a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 319a3972203SNick Piggin local_irq_restore(flags); 3201da177e4SLinus Torvalds 3211da177e4SLinus Torvalds /* 3221da177e4SLinus Torvalds * If none of the buffers had errors and they are all 3231da177e4SLinus Torvalds * uptodate then we can set the page uptodate. 3241da177e4SLinus Torvalds */ 3251da177e4SLinus Torvalds if (page_uptodate && !PageError(page)) 3261da177e4SLinus Torvalds SetPageUptodate(page); 3271da177e4SLinus Torvalds unlock_page(page); 3281da177e4SLinus Torvalds return; 3291da177e4SLinus Torvalds 3301da177e4SLinus Torvalds still_busy: 331a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 332a3972203SNick Piggin local_irq_restore(flags); 3331da177e4SLinus Torvalds return; 3341da177e4SLinus Torvalds } 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 3371da177e4SLinus Torvalds * Completion handler for block_write_full_page() - pages which are unlocked 3381da177e4SLinus Torvalds * during I/O, and which have PageWriteback cleared upon I/O completion. 3391da177e4SLinus Torvalds */ 34035c80d5fSChris Mason void end_buffer_async_write(struct buffer_head *bh, int uptodate) 3411da177e4SLinus Torvalds { 3421da177e4SLinus Torvalds unsigned long flags; 343a3972203SNick Piggin struct buffer_head *first; 3441da177e4SLinus Torvalds struct buffer_head *tmp; 3451da177e4SLinus Torvalds struct page *page; 3461da177e4SLinus Torvalds 3471da177e4SLinus Torvalds BUG_ON(!buffer_async_write(bh)); 3481da177e4SLinus Torvalds 3491da177e4SLinus Torvalds page = bh->b_page; 3501da177e4SLinus Torvalds if (uptodate) { 3511da177e4SLinus Torvalds set_buffer_uptodate(bh); 3521da177e4SLinus Torvalds } else { 353b744c2acSRobert Elliott buffer_io_error(bh, ", lost async page write"); 3545114a97aSMichal Hocko mapping_set_error(page->mapping, -EIO); 35558ff407bSJan Kara set_buffer_write_io_error(bh); 3561da177e4SLinus Torvalds clear_buffer_uptodate(bh); 3571da177e4SLinus Torvalds SetPageError(page); 3581da177e4SLinus Torvalds } 3591da177e4SLinus Torvalds 360a3972203SNick Piggin first = page_buffers(page); 361a3972203SNick Piggin local_irq_save(flags); 362a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 363a3972203SNick Piggin 3641da177e4SLinus Torvalds clear_buffer_async_write(bh); 3651da177e4SLinus Torvalds unlock_buffer(bh); 3661da177e4SLinus Torvalds tmp = bh->b_this_page; 3671da177e4SLinus Torvalds while (tmp != bh) { 3681da177e4SLinus Torvalds if (buffer_async_write(tmp)) { 3691da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3701da177e4SLinus Torvalds goto still_busy; 3711da177e4SLinus Torvalds } 3721da177e4SLinus Torvalds tmp = tmp->b_this_page; 3731da177e4SLinus Torvalds } 374a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 375a3972203SNick Piggin local_irq_restore(flags); 3761da177e4SLinus Torvalds end_page_writeback(page); 3771da177e4SLinus Torvalds return; 3781da177e4SLinus Torvalds 3791da177e4SLinus Torvalds still_busy: 380a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 381a3972203SNick Piggin local_irq_restore(flags); 3821da177e4SLinus Torvalds return; 3831da177e4SLinus Torvalds } 3841fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_async_write); 3851da177e4SLinus Torvalds 3861da177e4SLinus Torvalds /* 3871da177e4SLinus Torvalds * If a page's buffers are under async readin (end_buffer_async_read 3881da177e4SLinus Torvalds * completion) then there is a possibility that another thread of 3891da177e4SLinus Torvalds * control could lock one of the buffers after it has completed 3901da177e4SLinus Torvalds * but while some of the other buffers have not completed. This 3911da177e4SLinus Torvalds * locked buffer would confuse end_buffer_async_read() into not unlocking 3921da177e4SLinus Torvalds * the page. So the absence of BH_Async_Read tells end_buffer_async_read() 3931da177e4SLinus Torvalds * that this buffer is not under async I/O. 3941da177e4SLinus Torvalds * 3951da177e4SLinus Torvalds * The page comes unlocked when it has no locked buffer_async buffers 3961da177e4SLinus Torvalds * left. 3971da177e4SLinus Torvalds * 3981da177e4SLinus Torvalds * PageLocked prevents anyone starting new async I/O reads any of 3991da177e4SLinus Torvalds * the buffers. 4001da177e4SLinus Torvalds * 4011da177e4SLinus Torvalds * PageWriteback is used to prevent simultaneous writeout of the same 4021da177e4SLinus Torvalds * page. 4031da177e4SLinus Torvalds * 4041da177e4SLinus Torvalds * PageLocked prevents anyone from starting writeback of a page which is 4051da177e4SLinus Torvalds * under read I/O (PageWriteback is only ever set against a locked page). 4061da177e4SLinus Torvalds */ 4071da177e4SLinus Torvalds static void mark_buffer_async_read(struct buffer_head *bh) 4081da177e4SLinus Torvalds { 4091da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_read; 4101da177e4SLinus Torvalds set_buffer_async_read(bh); 4111da177e4SLinus Torvalds } 4121da177e4SLinus Torvalds 4131fe72eaaSH Hartley Sweeten static void mark_buffer_async_write_endio(struct buffer_head *bh, 41435c80d5fSChris Mason bh_end_io_t *handler) 41535c80d5fSChris Mason { 41635c80d5fSChris Mason bh->b_end_io = handler; 41735c80d5fSChris Mason set_buffer_async_write(bh); 41835c80d5fSChris Mason } 41935c80d5fSChris Mason 4201da177e4SLinus Torvalds void mark_buffer_async_write(struct buffer_head *bh) 4211da177e4SLinus Torvalds { 42235c80d5fSChris Mason mark_buffer_async_write_endio(bh, end_buffer_async_write); 4231da177e4SLinus Torvalds } 4241da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_async_write); 4251da177e4SLinus Torvalds 4261da177e4SLinus Torvalds 4271da177e4SLinus Torvalds /* 4281da177e4SLinus Torvalds * fs/buffer.c contains helper functions for buffer-backed address space's 4291da177e4SLinus Torvalds * fsync functions. A common requirement for buffer-based filesystems is 4301da177e4SLinus Torvalds * that certain data from the backing blockdev needs to be written out for 4311da177e4SLinus Torvalds * a successful fsync(). For example, ext2 indirect blocks need to be 4321da177e4SLinus Torvalds * written back and waited upon before fsync() returns. 4331da177e4SLinus Torvalds * 4341da177e4SLinus Torvalds * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), 4351da177e4SLinus Torvalds * inode_has_buffers() and invalidate_inode_buffers() are provided for the 4361da177e4SLinus Torvalds * management of a list of dependent buffers at ->i_mapping->private_list. 4371da177e4SLinus Torvalds * 4381da177e4SLinus Torvalds * Locking is a little subtle: try_to_free_buffers() will remove buffers 4391da177e4SLinus Torvalds * from their controlling inode's queue when they are being freed. But 4401da177e4SLinus Torvalds * try_to_free_buffers() will be operating against the *blockdev* mapping 4411da177e4SLinus Torvalds * at the time, not against the S_ISREG file which depends on those buffers. 4421da177e4SLinus Torvalds * So the locking for private_list is via the private_lock in the address_space 4431da177e4SLinus Torvalds * which backs the buffers. Which is different from the address_space 4441da177e4SLinus Torvalds * against which the buffers are listed. So for a particular address_space, 4451da177e4SLinus Torvalds * mapping->private_lock does *not* protect mapping->private_list! In fact, 4461da177e4SLinus Torvalds * mapping->private_list will always be protected by the backing blockdev's 4471da177e4SLinus Torvalds * ->private_lock. 4481da177e4SLinus Torvalds * 4491da177e4SLinus Torvalds * Which introduces a requirement: all buffers on an address_space's 4501da177e4SLinus Torvalds * ->private_list must be from the same address_space: the blockdev's. 4511da177e4SLinus Torvalds * 4521da177e4SLinus Torvalds * address_spaces which do not place buffers at ->private_list via these 4531da177e4SLinus Torvalds * utility functions are free to use private_lock and private_list for 4541da177e4SLinus Torvalds * whatever they want. The only requirement is that list_empty(private_list) 4551da177e4SLinus Torvalds * be true at clear_inode() time. 4561da177e4SLinus Torvalds * 4571da177e4SLinus Torvalds * FIXME: clear_inode should not call invalidate_inode_buffers(). The 4581da177e4SLinus Torvalds * filesystems should do that. invalidate_inode_buffers() should just go 4591da177e4SLinus Torvalds * BUG_ON(!list_empty). 4601da177e4SLinus Torvalds * 4611da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should 4621da177e4SLinus Torvalds * take an address_space, not an inode. And it should be called 4631da177e4SLinus Torvalds * mark_buffer_dirty_fsync() to clearly define why those buffers are being 4641da177e4SLinus Torvalds * queued up. 4651da177e4SLinus Torvalds * 4661da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the 4671da177e4SLinus Torvalds * list if it is already on a list. Because if the buffer is on a list, 4681da177e4SLinus Torvalds * it *must* already be on the right one. If not, the filesystem is being 4691da177e4SLinus Torvalds * silly. This will save a ton of locking. But first we have to ensure 4701da177e4SLinus Torvalds * that buffers are taken *off* the old inode's list when they are freed 4711da177e4SLinus Torvalds * (presumably in truncate). That requires careful auditing of all 4721da177e4SLinus Torvalds * filesystems (do it inside bforget()). It could also be done by bringing 4731da177e4SLinus Torvalds * b_inode back. 4741da177e4SLinus Torvalds */ 4751da177e4SLinus Torvalds 4761da177e4SLinus Torvalds /* 4771da177e4SLinus Torvalds * The buffer's backing address_space's private_lock must be held 4781da177e4SLinus Torvalds */ 479dbacefc9SThomas Petazzoni static void __remove_assoc_queue(struct buffer_head *bh) 4801da177e4SLinus Torvalds { 4811da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 48258ff407bSJan Kara WARN_ON(!bh->b_assoc_map); 48358ff407bSJan Kara if (buffer_write_io_error(bh)) 48458ff407bSJan Kara set_bit(AS_EIO, &bh->b_assoc_map->flags); 48558ff407bSJan Kara bh->b_assoc_map = NULL; 4861da177e4SLinus Torvalds } 4871da177e4SLinus Torvalds 4881da177e4SLinus Torvalds int inode_has_buffers(struct inode *inode) 4891da177e4SLinus Torvalds { 4901da177e4SLinus Torvalds return !list_empty(&inode->i_data.private_list); 4911da177e4SLinus Torvalds } 4921da177e4SLinus Torvalds 4931da177e4SLinus Torvalds /* 4941da177e4SLinus Torvalds * osync is designed to support O_SYNC io. It waits synchronously for 4951da177e4SLinus Torvalds * all already-submitted IO to complete, but does not queue any new 4961da177e4SLinus Torvalds * writes to the disk. 4971da177e4SLinus Torvalds * 4981da177e4SLinus Torvalds * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as 4991da177e4SLinus Torvalds * you dirty the buffers, and then use osync_inode_buffers to wait for 5001da177e4SLinus Torvalds * completion. Any other dirty buffers which are not yet queued for 5011da177e4SLinus Torvalds * write will not be flushed to disk by the osync. 5021da177e4SLinus Torvalds */ 5031da177e4SLinus Torvalds static int osync_buffers_list(spinlock_t *lock, struct list_head *list) 5041da177e4SLinus Torvalds { 5051da177e4SLinus Torvalds struct buffer_head *bh; 5061da177e4SLinus Torvalds struct list_head *p; 5071da177e4SLinus Torvalds int err = 0; 5081da177e4SLinus Torvalds 5091da177e4SLinus Torvalds spin_lock(lock); 5101da177e4SLinus Torvalds repeat: 5111da177e4SLinus Torvalds list_for_each_prev(p, list) { 5121da177e4SLinus Torvalds bh = BH_ENTRY(p); 5131da177e4SLinus Torvalds if (buffer_locked(bh)) { 5141da177e4SLinus Torvalds get_bh(bh); 5151da177e4SLinus Torvalds spin_unlock(lock); 5161da177e4SLinus Torvalds wait_on_buffer(bh); 5171da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 5181da177e4SLinus Torvalds err = -EIO; 5191da177e4SLinus Torvalds brelse(bh); 5201da177e4SLinus Torvalds spin_lock(lock); 5211da177e4SLinus Torvalds goto repeat; 5221da177e4SLinus Torvalds } 5231da177e4SLinus Torvalds } 5241da177e4SLinus Torvalds spin_unlock(lock); 5251da177e4SLinus Torvalds return err; 5261da177e4SLinus Torvalds } 5271da177e4SLinus Torvalds 52801a05b33SAl Viro static void do_thaw_one(struct super_block *sb, void *unused) 529c2d75438SEric Sandeen { 530c2d75438SEric Sandeen while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) 531a1c6f057SDmitry Monakhov printk(KERN_WARNING "Emergency Thaw on %pg\n", sb->s_bdev); 532c2d75438SEric Sandeen } 53301a05b33SAl Viro 53401a05b33SAl Viro static void do_thaw_all(struct work_struct *work) 53501a05b33SAl Viro { 53601a05b33SAl Viro iterate_supers(do_thaw_one, NULL); 537053c525fSJens Axboe kfree(work); 538c2d75438SEric Sandeen printk(KERN_WARNING "Emergency Thaw complete\n"); 539c2d75438SEric Sandeen } 540c2d75438SEric Sandeen 541c2d75438SEric Sandeen /** 542c2d75438SEric Sandeen * emergency_thaw_all -- forcibly thaw every frozen filesystem 543c2d75438SEric Sandeen * 544c2d75438SEric Sandeen * Used for emergency unfreeze of all filesystems via SysRq 545c2d75438SEric Sandeen */ 546c2d75438SEric Sandeen void emergency_thaw_all(void) 547c2d75438SEric Sandeen { 548053c525fSJens Axboe struct work_struct *work; 549053c525fSJens Axboe 550053c525fSJens Axboe work = kmalloc(sizeof(*work), GFP_ATOMIC); 551053c525fSJens Axboe if (work) { 552053c525fSJens Axboe INIT_WORK(work, do_thaw_all); 553053c525fSJens Axboe schedule_work(work); 554053c525fSJens Axboe } 555c2d75438SEric Sandeen } 556c2d75438SEric Sandeen 5571da177e4SLinus Torvalds /** 55878a4a50aSRandy Dunlap * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers 55967be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 5601da177e4SLinus Torvalds * 5611da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 5621da177e4SLinus Torvalds * that I/O. 5631da177e4SLinus Torvalds * 56467be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 56567be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 56667be2dd1SMartin Waitz * a successful fsync(). 5671da177e4SLinus Torvalds */ 5681da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 5691da177e4SLinus Torvalds { 570252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 5711da177e4SLinus Torvalds 5721da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 5731da177e4SLinus Torvalds return 0; 5741da177e4SLinus Torvalds 5751da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 5761da177e4SLinus Torvalds &mapping->private_list); 5771da177e4SLinus Torvalds } 5781da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 5791da177e4SLinus Torvalds 5801da177e4SLinus Torvalds /* 5811da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 5821da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 5831da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 5841da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 5851da177e4SLinus Torvalds */ 5861da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 5871da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 5881da177e4SLinus Torvalds { 5891da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 5901da177e4SLinus Torvalds if (bh) { 5911da177e4SLinus Torvalds if (buffer_dirty(bh)) 592dfec8a14SMike Christie ll_rw_block(REQ_OP_WRITE, 0, 1, &bh); 5931da177e4SLinus Torvalds put_bh(bh); 5941da177e4SLinus Torvalds } 5951da177e4SLinus Torvalds } 5961da177e4SLinus Torvalds 5971da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 5981da177e4SLinus Torvalds { 5991da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 6001da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 6011da177e4SLinus Torvalds 6021da177e4SLinus Torvalds mark_buffer_dirty(bh); 603252aa6f5SRafael Aquini if (!mapping->private_data) { 604252aa6f5SRafael Aquini mapping->private_data = buffer_mapping; 6051da177e4SLinus Torvalds } else { 606252aa6f5SRafael Aquini BUG_ON(mapping->private_data != buffer_mapping); 6071da177e4SLinus Torvalds } 608535ee2fbSJan Kara if (!bh->b_assoc_map) { 6091da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 6101da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 6111da177e4SLinus Torvalds &mapping->private_list); 61258ff407bSJan Kara bh->b_assoc_map = mapping; 6131da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds } 6161da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 6171da177e4SLinus Torvalds 6181da177e4SLinus Torvalds /* 619787d2214SNick Piggin * Mark the page dirty, and set it dirty in the radix tree, and mark the inode 620787d2214SNick Piggin * dirty. 621787d2214SNick Piggin * 622787d2214SNick Piggin * If warn is true, then emit a warning if the page is not uptodate and has 623787d2214SNick Piggin * not been truncated. 624c4843a75SGreg Thelen * 62581f8c3a4SJohannes Weiner * The caller must hold lock_page_memcg(). 626787d2214SNick Piggin */ 627c4843a75SGreg Thelen static void __set_page_dirty(struct page *page, struct address_space *mapping, 62862cccb8cSJohannes Weiner int warn) 629787d2214SNick Piggin { 630227d53b3SKOSAKI Motohiro unsigned long flags; 631227d53b3SKOSAKI Motohiro 632227d53b3SKOSAKI Motohiro spin_lock_irqsave(&mapping->tree_lock, flags); 633787d2214SNick Piggin if (page->mapping) { /* Race with truncate? */ 634787d2214SNick Piggin WARN_ON_ONCE(warn && !PageUptodate(page)); 63562cccb8cSJohannes Weiner account_page_dirtied(page, mapping); 636787d2214SNick Piggin radix_tree_tag_set(&mapping->page_tree, 637787d2214SNick Piggin page_index(page), PAGECACHE_TAG_DIRTY); 638787d2214SNick Piggin } 639227d53b3SKOSAKI Motohiro spin_unlock_irqrestore(&mapping->tree_lock, flags); 640787d2214SNick Piggin } 641787d2214SNick Piggin 642787d2214SNick Piggin /* 6431da177e4SLinus Torvalds * Add a page to the dirty page list. 6441da177e4SLinus Torvalds * 6451da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 6461da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 6471da177e4SLinus Torvalds * 6481da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 6491da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 6501da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 6511da177e4SLinus Torvalds * dirty. 6521da177e4SLinus Torvalds * 6531da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 6541da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 6551da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 6561da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 6571da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 6581da177e4SLinus Torvalds * page on the dirty page list. 6591da177e4SLinus Torvalds * 6601da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 6611da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 6621da177e4SLinus Torvalds * added to the page after it was set dirty. 6631da177e4SLinus Torvalds * 6641da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 6651da177e4SLinus Torvalds * address_space though. 6661da177e4SLinus Torvalds */ 6671da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 6681da177e4SLinus Torvalds { 669a8e7d49aSLinus Torvalds int newly_dirty; 670787d2214SNick Piggin struct address_space *mapping = page_mapping(page); 671ebf7a227SNick Piggin 672ebf7a227SNick Piggin if (unlikely(!mapping)) 673ebf7a227SNick Piggin return !TestSetPageDirty(page); 6741da177e4SLinus Torvalds 6751da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 6761da177e4SLinus Torvalds if (page_has_buffers(page)) { 6771da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 6781da177e4SLinus Torvalds struct buffer_head *bh = head; 6791da177e4SLinus Torvalds 6801da177e4SLinus Torvalds do { 6811da177e4SLinus Torvalds set_buffer_dirty(bh); 6821da177e4SLinus Torvalds bh = bh->b_this_page; 6831da177e4SLinus Torvalds } while (bh != head); 6841da177e4SLinus Torvalds } 685c4843a75SGreg Thelen /* 68681f8c3a4SJohannes Weiner * Lock out page->mem_cgroup migration to keep PageDirty 68781f8c3a4SJohannes Weiner * synchronized with per-memcg dirty page counters. 688c4843a75SGreg Thelen */ 68962cccb8cSJohannes Weiner lock_page_memcg(page); 690a8e7d49aSLinus Torvalds newly_dirty = !TestSetPageDirty(page); 6911da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 6921da177e4SLinus Torvalds 693a8e7d49aSLinus Torvalds if (newly_dirty) 69462cccb8cSJohannes Weiner __set_page_dirty(page, mapping, 1); 695c4843a75SGreg Thelen 69662cccb8cSJohannes Weiner unlock_page_memcg(page); 697c4843a75SGreg Thelen 698c4843a75SGreg Thelen if (newly_dirty) 699c4843a75SGreg Thelen __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 700c4843a75SGreg Thelen 701a8e7d49aSLinus Torvalds return newly_dirty; 7021da177e4SLinus Torvalds } 7031da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 7041da177e4SLinus Torvalds 7051da177e4SLinus Torvalds /* 7061da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 7071da177e4SLinus Torvalds * 7081da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 7091da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 7101da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 7111da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 7121da177e4SLinus Torvalds * 7131da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 7141da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 7151da177e4SLinus Torvalds * up, waiting for those writes to complete. 7161da177e4SLinus Torvalds * 7171da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 7181da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 7191da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 7201da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 7211da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 7221da177e4SLinus Torvalds * any newly dirty buffers for write. 7231da177e4SLinus Torvalds */ 7241da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 7251da177e4SLinus Torvalds { 7261da177e4SLinus Torvalds struct buffer_head *bh; 7271da177e4SLinus Torvalds struct list_head tmp; 7287eaceaccSJens Axboe struct address_space *mapping; 7291da177e4SLinus Torvalds int err = 0, err2; 7304ee2491eSJens Axboe struct blk_plug plug; 7311da177e4SLinus Torvalds 7321da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 7334ee2491eSJens Axboe blk_start_plug(&plug); 7341da177e4SLinus Torvalds 7351da177e4SLinus Torvalds spin_lock(lock); 7361da177e4SLinus Torvalds while (!list_empty(list)) { 7371da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 738535ee2fbSJan Kara mapping = bh->b_assoc_map; 73958ff407bSJan Kara __remove_assoc_queue(bh); 740535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 741535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 742535ee2fbSJan Kara smp_mb(); 7431da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 7441da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 745535ee2fbSJan Kara bh->b_assoc_map = mapping; 7461da177e4SLinus Torvalds if (buffer_dirty(bh)) { 7471da177e4SLinus Torvalds get_bh(bh); 7481da177e4SLinus Torvalds spin_unlock(lock); 7491da177e4SLinus Torvalds /* 7501da177e4SLinus Torvalds * Ensure any pending I/O completes so that 7519cb569d6SChristoph Hellwig * write_dirty_buffer() actually writes the 7529cb569d6SChristoph Hellwig * current contents - it is a noop if I/O is 7539cb569d6SChristoph Hellwig * still in flight on potentially older 7549cb569d6SChristoph Hellwig * contents. 7551da177e4SLinus Torvalds */ 756721a9602SJens Axboe write_dirty_buffer(bh, WRITE_SYNC); 7579cf6b720SJens Axboe 7589cf6b720SJens Axboe /* 7599cf6b720SJens Axboe * Kick off IO for the previous mapping. Note 7609cf6b720SJens Axboe * that we will not run the very last mapping, 7619cf6b720SJens Axboe * wait_on_buffer() will do that for us 7629cf6b720SJens Axboe * through sync_buffer(). 7639cf6b720SJens Axboe */ 7641da177e4SLinus Torvalds brelse(bh); 7651da177e4SLinus Torvalds spin_lock(lock); 7661da177e4SLinus Torvalds } 7671da177e4SLinus Torvalds } 7681da177e4SLinus Torvalds } 7691da177e4SLinus Torvalds 7704ee2491eSJens Axboe spin_unlock(lock); 7714ee2491eSJens Axboe blk_finish_plug(&plug); 7724ee2491eSJens Axboe spin_lock(lock); 7734ee2491eSJens Axboe 7741da177e4SLinus Torvalds while (!list_empty(&tmp)) { 7751da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 7761da177e4SLinus Torvalds get_bh(bh); 777535ee2fbSJan Kara mapping = bh->b_assoc_map; 778535ee2fbSJan Kara __remove_assoc_queue(bh); 779535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 780535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 781535ee2fbSJan Kara smp_mb(); 782535ee2fbSJan Kara if (buffer_dirty(bh)) { 783535ee2fbSJan Kara list_add(&bh->b_assoc_buffers, 784e3892296SJan Kara &mapping->private_list); 785535ee2fbSJan Kara bh->b_assoc_map = mapping; 786535ee2fbSJan Kara } 7871da177e4SLinus Torvalds spin_unlock(lock); 7881da177e4SLinus Torvalds wait_on_buffer(bh); 7891da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 7901da177e4SLinus Torvalds err = -EIO; 7911da177e4SLinus Torvalds brelse(bh); 7921da177e4SLinus Torvalds spin_lock(lock); 7931da177e4SLinus Torvalds } 7941da177e4SLinus Torvalds 7951da177e4SLinus Torvalds spin_unlock(lock); 7961da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 7971da177e4SLinus Torvalds if (err) 7981da177e4SLinus Torvalds return err; 7991da177e4SLinus Torvalds else 8001da177e4SLinus Torvalds return err2; 8011da177e4SLinus Torvalds } 8021da177e4SLinus Torvalds 8031da177e4SLinus Torvalds /* 8041da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 8051da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 8061da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 8071da177e4SLinus Torvalds * 8081da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 8091da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 8101da177e4SLinus Torvalds * for reiserfs. 8111da177e4SLinus Torvalds */ 8121da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 8131da177e4SLinus Torvalds { 8141da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8151da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8161da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 817252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 8181da177e4SLinus Torvalds 8191da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8201da177e4SLinus Torvalds while (!list_empty(list)) 8211da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 8221da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8231da177e4SLinus Torvalds } 8241da177e4SLinus Torvalds } 82552b19ac9SJan Kara EXPORT_SYMBOL(invalidate_inode_buffers); 8261da177e4SLinus Torvalds 8271da177e4SLinus Torvalds /* 8281da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 8291da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 8301da177e4SLinus Torvalds * 8311da177e4SLinus Torvalds * Returns true if all buffers were removed. 8321da177e4SLinus Torvalds */ 8331da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 8341da177e4SLinus Torvalds { 8351da177e4SLinus Torvalds int ret = 1; 8361da177e4SLinus Torvalds 8371da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8381da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8391da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 840252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 8411da177e4SLinus Torvalds 8421da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8431da177e4SLinus Torvalds while (!list_empty(list)) { 8441da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 8451da177e4SLinus Torvalds if (buffer_dirty(bh)) { 8461da177e4SLinus Torvalds ret = 0; 8471da177e4SLinus Torvalds break; 8481da177e4SLinus Torvalds } 8491da177e4SLinus Torvalds __remove_assoc_queue(bh); 8501da177e4SLinus Torvalds } 8511da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8521da177e4SLinus Torvalds } 8531da177e4SLinus Torvalds return ret; 8541da177e4SLinus Torvalds } 8551da177e4SLinus Torvalds 8561da177e4SLinus Torvalds /* 8571da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 8581da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 8591da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 8601da177e4SLinus Torvalds * buffers. 8611da177e4SLinus Torvalds * 8621da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 8631da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 8641da177e4SLinus Torvalds */ 8651da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 8661da177e4SLinus Torvalds int retry) 8671da177e4SLinus Torvalds { 8681da177e4SLinus Torvalds struct buffer_head *bh, *head; 8691da177e4SLinus Torvalds long offset; 8701da177e4SLinus Torvalds 8711da177e4SLinus Torvalds try_again: 8721da177e4SLinus Torvalds head = NULL; 8731da177e4SLinus Torvalds offset = PAGE_SIZE; 8741da177e4SLinus Torvalds while ((offset -= size) >= 0) { 8751da177e4SLinus Torvalds bh = alloc_buffer_head(GFP_NOFS); 8761da177e4SLinus Torvalds if (!bh) 8771da177e4SLinus Torvalds goto no_grow; 8781da177e4SLinus Torvalds 8791da177e4SLinus Torvalds bh->b_this_page = head; 8801da177e4SLinus Torvalds bh->b_blocknr = -1; 8811da177e4SLinus Torvalds head = bh; 8821da177e4SLinus Torvalds 8831da177e4SLinus Torvalds bh->b_size = size; 8841da177e4SLinus Torvalds 8851da177e4SLinus Torvalds /* Link the buffer to its page */ 8861da177e4SLinus Torvalds set_bh_page(bh, page, offset); 8871da177e4SLinus Torvalds } 8881da177e4SLinus Torvalds return head; 8891da177e4SLinus Torvalds /* 8901da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 8911da177e4SLinus Torvalds */ 8921da177e4SLinus Torvalds no_grow: 8931da177e4SLinus Torvalds if (head) { 8941da177e4SLinus Torvalds do { 8951da177e4SLinus Torvalds bh = head; 8961da177e4SLinus Torvalds head = head->b_this_page; 8971da177e4SLinus Torvalds free_buffer_head(bh); 8981da177e4SLinus Torvalds } while (head); 8991da177e4SLinus Torvalds } 9001da177e4SLinus Torvalds 9011da177e4SLinus Torvalds /* 9021da177e4SLinus Torvalds * Return failure for non-async IO requests. Async IO requests 9031da177e4SLinus Torvalds * are not allowed to fail, so we have to wait until buffer heads 9041da177e4SLinus Torvalds * become available. But we don't want tasks sleeping with 9051da177e4SLinus Torvalds * partially complete buffers, so all were released above. 9061da177e4SLinus Torvalds */ 9071da177e4SLinus Torvalds if (!retry) 9081da177e4SLinus Torvalds return NULL; 9091da177e4SLinus Torvalds 9101da177e4SLinus Torvalds /* We're _really_ low on memory. Now we just 9111da177e4SLinus Torvalds * wait for old buffer heads to become free due to 9121da177e4SLinus Torvalds * finishing IO. Since this is an async request and 9131da177e4SLinus Torvalds * the reserve list is empty, we're sure there are 9141da177e4SLinus Torvalds * async buffer heads in use. 9151da177e4SLinus Torvalds */ 9161da177e4SLinus Torvalds free_more_memory(); 9171da177e4SLinus Torvalds goto try_again; 9181da177e4SLinus Torvalds } 9191da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 9201da177e4SLinus Torvalds 9211da177e4SLinus Torvalds static inline void 9221da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 9231da177e4SLinus Torvalds { 9241da177e4SLinus Torvalds struct buffer_head *bh, *tail; 9251da177e4SLinus Torvalds 9261da177e4SLinus Torvalds bh = head; 9271da177e4SLinus Torvalds do { 9281da177e4SLinus Torvalds tail = bh; 9291da177e4SLinus Torvalds bh = bh->b_this_page; 9301da177e4SLinus Torvalds } while (bh); 9311da177e4SLinus Torvalds tail->b_this_page = head; 9321da177e4SLinus Torvalds attach_page_buffers(page, head); 9331da177e4SLinus Torvalds } 9341da177e4SLinus Torvalds 935bbec0270SLinus Torvalds static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) 936bbec0270SLinus Torvalds { 937bbec0270SLinus Torvalds sector_t retval = ~((sector_t)0); 938bbec0270SLinus Torvalds loff_t sz = i_size_read(bdev->bd_inode); 939bbec0270SLinus Torvalds 940bbec0270SLinus Torvalds if (sz) { 941bbec0270SLinus Torvalds unsigned int sizebits = blksize_bits(size); 942bbec0270SLinus Torvalds retval = (sz >> sizebits); 943bbec0270SLinus Torvalds } 944bbec0270SLinus Torvalds return retval; 945bbec0270SLinus Torvalds } 946bbec0270SLinus Torvalds 9471da177e4SLinus Torvalds /* 9481da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 9491da177e4SLinus Torvalds */ 950676ce6d5SHugh Dickins static sector_t 9511da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 9521da177e4SLinus Torvalds sector_t block, int size) 9531da177e4SLinus Torvalds { 9541da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 9551da177e4SLinus Torvalds struct buffer_head *bh = head; 9561da177e4SLinus Torvalds int uptodate = PageUptodate(page); 957bbec0270SLinus Torvalds sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size); 9581da177e4SLinus Torvalds 9591da177e4SLinus Torvalds do { 9601da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 9611da177e4SLinus Torvalds init_buffer(bh, NULL, NULL); 9621da177e4SLinus Torvalds bh->b_bdev = bdev; 9631da177e4SLinus Torvalds bh->b_blocknr = block; 9641da177e4SLinus Torvalds if (uptodate) 9651da177e4SLinus Torvalds set_buffer_uptodate(bh); 966080399aaSJeff Moyer if (block < end_block) 9671da177e4SLinus Torvalds set_buffer_mapped(bh); 9681da177e4SLinus Torvalds } 9691da177e4SLinus Torvalds block++; 9701da177e4SLinus Torvalds bh = bh->b_this_page; 9711da177e4SLinus Torvalds } while (bh != head); 972676ce6d5SHugh Dickins 973676ce6d5SHugh Dickins /* 974676ce6d5SHugh Dickins * Caller needs to validate requested block against end of device. 975676ce6d5SHugh Dickins */ 976676ce6d5SHugh Dickins return end_block; 9771da177e4SLinus Torvalds } 9781da177e4SLinus Torvalds 9791da177e4SLinus Torvalds /* 9801da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 9811da177e4SLinus Torvalds * 982676ce6d5SHugh Dickins * This is used purely for blockdev mappings. 9831da177e4SLinus Torvalds */ 984676ce6d5SHugh Dickins static int 9851da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 9863b5e6454SGioh Kim pgoff_t index, int size, int sizebits, gfp_t gfp) 9871da177e4SLinus Torvalds { 9881da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 9891da177e4SLinus Torvalds struct page *page; 9901da177e4SLinus Torvalds struct buffer_head *bh; 991676ce6d5SHugh Dickins sector_t end_block; 992676ce6d5SHugh Dickins int ret = 0; /* Will call free_more_memory() */ 99384235de3SJohannes Weiner gfp_t gfp_mask; 9941da177e4SLinus Torvalds 995c62d2555SMichal Hocko gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp; 9963b5e6454SGioh Kim 99784235de3SJohannes Weiner /* 99884235de3SJohannes Weiner * XXX: __getblk_slow() can not really deal with failure and 99984235de3SJohannes Weiner * will endlessly loop on improvised global reclaim. Prefer 100084235de3SJohannes Weiner * looping in the allocator rather than here, at least that 100184235de3SJohannes Weiner * code knows what it's doing. 100284235de3SJohannes Weiner */ 100384235de3SJohannes Weiner gfp_mask |= __GFP_NOFAIL; 100484235de3SJohannes Weiner 100584235de3SJohannes Weiner page = find_or_create_page(inode->i_mapping, index, gfp_mask); 10061da177e4SLinus Torvalds if (!page) 1007676ce6d5SHugh Dickins return ret; 10081da177e4SLinus Torvalds 1009e827f923SEric Sesterhenn BUG_ON(!PageLocked(page)); 10101da177e4SLinus Torvalds 10111da177e4SLinus Torvalds if (page_has_buffers(page)) { 10121da177e4SLinus Torvalds bh = page_buffers(page); 10131da177e4SLinus Torvalds if (bh->b_size == size) { 1014676ce6d5SHugh Dickins end_block = init_page_buffers(page, bdev, 1015f2d5a944SAnton Altaparmakov (sector_t)index << sizebits, 1016f2d5a944SAnton Altaparmakov size); 1017676ce6d5SHugh Dickins goto done; 10181da177e4SLinus Torvalds } 10191da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 10201da177e4SLinus Torvalds goto failed; 10211da177e4SLinus Torvalds } 10221da177e4SLinus Torvalds 10231da177e4SLinus Torvalds /* 10241da177e4SLinus Torvalds * Allocate some buffers for this page 10251da177e4SLinus Torvalds */ 10261da177e4SLinus Torvalds bh = alloc_page_buffers(page, size, 0); 10271da177e4SLinus Torvalds if (!bh) 10281da177e4SLinus Torvalds goto failed; 10291da177e4SLinus Torvalds 10301da177e4SLinus Torvalds /* 10311da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 10321da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 10331da177e4SLinus Torvalds * run under the page lock. 10341da177e4SLinus Torvalds */ 10351da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 10361da177e4SLinus Torvalds link_dev_buffers(page, bh); 1037f2d5a944SAnton Altaparmakov end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits, 1038f2d5a944SAnton Altaparmakov size); 10391da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 1040676ce6d5SHugh Dickins done: 1041676ce6d5SHugh Dickins ret = (block < end_block) ? 1 : -ENXIO; 10421da177e4SLinus Torvalds failed: 10431da177e4SLinus Torvalds unlock_page(page); 104409cbfeafSKirill A. Shutemov put_page(page); 1045676ce6d5SHugh Dickins return ret; 10461da177e4SLinus Torvalds } 10471da177e4SLinus Torvalds 10481da177e4SLinus Torvalds /* 10491da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 10501da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 10511da177e4SLinus Torvalds */ 1052858119e1SArjan van de Ven static int 10533b5e6454SGioh Kim grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) 10541da177e4SLinus Torvalds { 10551da177e4SLinus Torvalds pgoff_t index; 10561da177e4SLinus Torvalds int sizebits; 10571da177e4SLinus Torvalds 10581da177e4SLinus Torvalds sizebits = -1; 10591da177e4SLinus Torvalds do { 10601da177e4SLinus Torvalds sizebits++; 10611da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 10621da177e4SLinus Torvalds 10631da177e4SLinus Torvalds index = block >> sizebits; 10641da177e4SLinus Torvalds 1065e5657933SAndrew Morton /* 1066e5657933SAndrew Morton * Check for a block which wants to lie outside our maximum possible 1067e5657933SAndrew Morton * pagecache index. (this comparison is done using sector_t types). 1068e5657933SAndrew Morton */ 1069e5657933SAndrew Morton if (unlikely(index != block >> sizebits)) { 1070e5657933SAndrew Morton printk(KERN_ERR "%s: requested out-of-range block %llu for " 1071a1c6f057SDmitry Monakhov "device %pg\n", 10728e24eea7SHarvey Harrison __func__, (unsigned long long)block, 1073a1c6f057SDmitry Monakhov bdev); 1074e5657933SAndrew Morton return -EIO; 1075e5657933SAndrew Morton } 1076676ce6d5SHugh Dickins 10771da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 10783b5e6454SGioh Kim return grow_dev_page(bdev, block, index, size, sizebits, gfp); 10791da177e4SLinus Torvalds } 10801da177e4SLinus Torvalds 10810026ba40SEric Biggers static struct buffer_head * 10823b5e6454SGioh Kim __getblk_slow(struct block_device *bdev, sector_t block, 10833b5e6454SGioh Kim unsigned size, gfp_t gfp) 10841da177e4SLinus Torvalds { 10851da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 1086e1defc4fSMartin K. Petersen if (unlikely(size & (bdev_logical_block_size(bdev)-1) || 10871da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 10881da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 10891da177e4SLinus Torvalds size); 1090e1defc4fSMartin K. Petersen printk(KERN_ERR "logical block size: %d\n", 1091e1defc4fSMartin K. Petersen bdev_logical_block_size(bdev)); 10921da177e4SLinus Torvalds 10931da177e4SLinus Torvalds dump_stack(); 10941da177e4SLinus Torvalds return NULL; 10951da177e4SLinus Torvalds } 10961da177e4SLinus Torvalds 1097676ce6d5SHugh Dickins for (;;) { 1098676ce6d5SHugh Dickins struct buffer_head *bh; 1099676ce6d5SHugh Dickins int ret; 1100676ce6d5SHugh Dickins 11011da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 11021da177e4SLinus Torvalds if (bh) 11031da177e4SLinus Torvalds return bh; 11041da177e4SLinus Torvalds 11053b5e6454SGioh Kim ret = grow_buffers(bdev, block, size, gfp); 1106676ce6d5SHugh Dickins if (ret < 0) 110791f68c89SJeff Moyer return NULL; 1108676ce6d5SHugh Dickins if (ret == 0) 1109676ce6d5SHugh Dickins free_more_memory(); 1110676ce6d5SHugh Dickins } 11111da177e4SLinus Torvalds } 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; 12282a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, 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)) { 139870246286SChristoph Hellwig ll_rw_block(REQ_OP_READ, REQ_RAHEAD, 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 */ 1690b4bba389SBenjamin 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; 17002a222ca9SMike Christie int write_flags = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : 0); 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)) { 17892a222ca9SMike Christie submit_bh_wbc(REQ_OP_WRITE, write_flags, 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); 18432a222ca9SMike Christie submit_bh_wbc(REQ_OP_WRITE, write_flags, 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 } 1851b4bba389SBenjamin 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 1895ae259a9cSChristoph Hellwig static void 1896ae259a9cSChristoph Hellwig iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, 1897ae259a9cSChristoph Hellwig struct iomap *iomap) 1898ae259a9cSChristoph Hellwig { 1899ae259a9cSChristoph Hellwig loff_t offset = block << inode->i_blkbits; 1900ae259a9cSChristoph Hellwig 1901ae259a9cSChristoph Hellwig bh->b_bdev = iomap->bdev; 1902ae259a9cSChristoph Hellwig 1903ae259a9cSChristoph Hellwig /* 1904ae259a9cSChristoph Hellwig * Block points to offset in file we need to map, iomap contains 1905ae259a9cSChristoph Hellwig * the offset at which the map starts. If the map ends before the 1906ae259a9cSChristoph Hellwig * current block, then do not map the buffer and let the caller 1907ae259a9cSChristoph Hellwig * handle it. 1908ae259a9cSChristoph Hellwig */ 1909ae259a9cSChristoph Hellwig BUG_ON(offset >= iomap->offset + iomap->length); 1910ae259a9cSChristoph Hellwig 1911ae259a9cSChristoph Hellwig switch (iomap->type) { 1912ae259a9cSChristoph Hellwig case IOMAP_HOLE: 1913ae259a9cSChristoph Hellwig /* 1914ae259a9cSChristoph Hellwig * If the buffer is not up to date or beyond the current EOF, 1915ae259a9cSChristoph Hellwig * we need to mark it as new to ensure sub-block zeroing is 1916ae259a9cSChristoph Hellwig * executed if necessary. 1917ae259a9cSChristoph Hellwig */ 1918ae259a9cSChristoph Hellwig if (!buffer_uptodate(bh) || 1919ae259a9cSChristoph Hellwig (offset >= i_size_read(inode))) 1920ae259a9cSChristoph Hellwig set_buffer_new(bh); 1921ae259a9cSChristoph Hellwig break; 1922ae259a9cSChristoph Hellwig case IOMAP_DELALLOC: 1923ae259a9cSChristoph Hellwig if (!buffer_uptodate(bh) || 1924ae259a9cSChristoph Hellwig (offset >= i_size_read(inode))) 1925ae259a9cSChristoph Hellwig set_buffer_new(bh); 1926ae259a9cSChristoph Hellwig set_buffer_uptodate(bh); 1927ae259a9cSChristoph Hellwig set_buffer_mapped(bh); 1928ae259a9cSChristoph Hellwig set_buffer_delay(bh); 1929ae259a9cSChristoph Hellwig break; 1930ae259a9cSChristoph Hellwig case IOMAP_UNWRITTEN: 1931ae259a9cSChristoph Hellwig /* 1932ae259a9cSChristoph Hellwig * For unwritten regions, we always need to ensure that 1933ae259a9cSChristoph Hellwig * sub-block writes cause the regions in the block we are not 1934ae259a9cSChristoph Hellwig * writing to are zeroed. Set the buffer as new to ensure this. 1935ae259a9cSChristoph Hellwig */ 1936ae259a9cSChristoph Hellwig set_buffer_new(bh); 1937ae259a9cSChristoph Hellwig set_buffer_unwritten(bh); 1938ae259a9cSChristoph Hellwig /* FALLTHRU */ 1939ae259a9cSChristoph Hellwig case IOMAP_MAPPED: 1940ae259a9cSChristoph Hellwig if (offset >= i_size_read(inode)) 1941ae259a9cSChristoph Hellwig set_buffer_new(bh); 1942ae259a9cSChristoph Hellwig bh->b_blocknr = (iomap->blkno >> (inode->i_blkbits - 9)) + 1943ae259a9cSChristoph Hellwig ((offset - iomap->offset) >> inode->i_blkbits); 1944ae259a9cSChristoph Hellwig set_buffer_mapped(bh); 1945ae259a9cSChristoph Hellwig break; 1946ae259a9cSChristoph Hellwig } 1947ae259a9cSChristoph Hellwig } 1948ae259a9cSChristoph Hellwig 1949ae259a9cSChristoph Hellwig int __block_write_begin_int(struct page *page, loff_t pos, unsigned len, 1950ae259a9cSChristoph Hellwig get_block_t *get_block, struct iomap *iomap) 19511da177e4SLinus Torvalds { 195209cbfeafSKirill A. Shutemov unsigned from = pos & (PAGE_SIZE - 1); 1953ebdec241SChristoph Hellwig unsigned to = from + len; 19546e1db88dSChristoph Hellwig struct inode *inode = page->mapping->host; 19551da177e4SLinus Torvalds unsigned block_start, block_end; 19561da177e4SLinus Torvalds sector_t block; 19571da177e4SLinus Torvalds int err = 0; 19581da177e4SLinus Torvalds unsigned blocksize, bbits; 19591da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 19601da177e4SLinus Torvalds 19611da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 196209cbfeafSKirill A. Shutemov BUG_ON(from > PAGE_SIZE); 196309cbfeafSKirill A. Shutemov BUG_ON(to > PAGE_SIZE); 19641da177e4SLinus Torvalds BUG_ON(from > to); 19651da177e4SLinus Torvalds 196645bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 196745bce8f3SLinus Torvalds blocksize = head->b_size; 196845bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 19691da177e4SLinus Torvalds 197009cbfeafSKirill A. Shutemov block = (sector_t)page->index << (PAGE_SHIFT - bbits); 19711da177e4SLinus Torvalds 19721da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 19731da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 19741da177e4SLinus Torvalds block_end = block_start + blocksize; 19751da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19761da177e4SLinus Torvalds if (PageUptodate(page)) { 19771da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19781da177e4SLinus Torvalds set_buffer_uptodate(bh); 19791da177e4SLinus Torvalds } 19801da177e4SLinus Torvalds continue; 19811da177e4SLinus Torvalds } 19821da177e4SLinus Torvalds if (buffer_new(bh)) 19831da177e4SLinus Torvalds clear_buffer_new(bh); 19841da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 1985b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 1986ae259a9cSChristoph Hellwig if (get_block) { 19871da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 19881da177e4SLinus Torvalds if (err) 1989f3ddbdc6SNick Piggin break; 1990ae259a9cSChristoph Hellwig } else { 1991ae259a9cSChristoph Hellwig iomap_to_bh(inode, block, bh, iomap); 1992ae259a9cSChristoph Hellwig } 1993ae259a9cSChristoph Hellwig 19941da177e4SLinus Torvalds if (buffer_new(bh)) { 19951da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 19961da177e4SLinus Torvalds bh->b_blocknr); 19971da177e4SLinus Torvalds if (PageUptodate(page)) { 1998637aff46SNick Piggin clear_buffer_new(bh); 19991da177e4SLinus Torvalds set_buffer_uptodate(bh); 2000637aff46SNick Piggin mark_buffer_dirty(bh); 20011da177e4SLinus Torvalds continue; 20021da177e4SLinus Torvalds } 2003eebd2aa3SChristoph Lameter if (block_end > to || block_start < from) 2004eebd2aa3SChristoph Lameter zero_user_segments(page, 2005eebd2aa3SChristoph Lameter to, block_end, 2006eebd2aa3SChristoph Lameter block_start, from); 20071da177e4SLinus Torvalds continue; 20081da177e4SLinus Torvalds } 20091da177e4SLinus Torvalds } 20101da177e4SLinus Torvalds if (PageUptodate(page)) { 20111da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 20121da177e4SLinus Torvalds set_buffer_uptodate(bh); 20131da177e4SLinus Torvalds continue; 20141da177e4SLinus Torvalds } 20151da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 201633a266ddSDavid Chinner !buffer_unwritten(bh) && 20171da177e4SLinus Torvalds (block_start < from || block_end > to)) { 2018dfec8a14SMike Christie ll_rw_block(REQ_OP_READ, 0, 1, &bh); 20191da177e4SLinus Torvalds *wait_bh++=bh; 20201da177e4SLinus Torvalds } 20211da177e4SLinus Torvalds } 20221da177e4SLinus Torvalds /* 20231da177e4SLinus Torvalds * If we issued read requests - let them complete. 20241da177e4SLinus Torvalds */ 20251da177e4SLinus Torvalds while(wait_bh > wait) { 20261da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 20271da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 2028f3ddbdc6SNick Piggin err = -EIO; 20291da177e4SLinus Torvalds } 2030f9f07b6cSJan Kara if (unlikely(err)) 2031afddba49SNick Piggin page_zero_new_buffers(page, from, to); 20321da177e4SLinus Torvalds return err; 20331da177e4SLinus Torvalds } 2034ae259a9cSChristoph Hellwig 2035ae259a9cSChristoph Hellwig int __block_write_begin(struct page *page, loff_t pos, unsigned len, 2036ae259a9cSChristoph Hellwig get_block_t *get_block) 2037ae259a9cSChristoph Hellwig { 2038ae259a9cSChristoph Hellwig return __block_write_begin_int(page, pos, len, get_block, NULL); 2039ae259a9cSChristoph Hellwig } 2040ebdec241SChristoph Hellwig EXPORT_SYMBOL(__block_write_begin); 20411da177e4SLinus Torvalds 20421da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 20431da177e4SLinus Torvalds unsigned from, unsigned to) 20441da177e4SLinus Torvalds { 20451da177e4SLinus Torvalds unsigned block_start, block_end; 20461da177e4SLinus Torvalds int partial = 0; 20471da177e4SLinus Torvalds unsigned blocksize; 20481da177e4SLinus Torvalds struct buffer_head *bh, *head; 20491da177e4SLinus Torvalds 205045bce8f3SLinus Torvalds bh = head = page_buffers(page); 205145bce8f3SLinus Torvalds blocksize = bh->b_size; 20521da177e4SLinus Torvalds 205345bce8f3SLinus Torvalds block_start = 0; 205445bce8f3SLinus Torvalds do { 20551da177e4SLinus Torvalds block_end = block_start + blocksize; 20561da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 20571da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 20581da177e4SLinus Torvalds partial = 1; 20591da177e4SLinus Torvalds } else { 20601da177e4SLinus Torvalds set_buffer_uptodate(bh); 20611da177e4SLinus Torvalds mark_buffer_dirty(bh); 20621da177e4SLinus Torvalds } 2063afddba49SNick Piggin clear_buffer_new(bh); 206445bce8f3SLinus Torvalds 206545bce8f3SLinus Torvalds block_start = block_end; 206645bce8f3SLinus Torvalds bh = bh->b_this_page; 206745bce8f3SLinus Torvalds } while (bh != head); 20681da177e4SLinus Torvalds 20691da177e4SLinus Torvalds /* 20701da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 20711da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 20721da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 20731da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 20741da177e4SLinus Torvalds */ 20751da177e4SLinus Torvalds if (!partial) 20761da177e4SLinus Torvalds SetPageUptodate(page); 20771da177e4SLinus Torvalds return 0; 20781da177e4SLinus Torvalds } 20791da177e4SLinus Torvalds 20801da177e4SLinus Torvalds /* 2081155130a4SChristoph Hellwig * block_write_begin takes care of the basic task of block allocation and 2082155130a4SChristoph Hellwig * bringing partial write blocks uptodate first. 2083155130a4SChristoph Hellwig * 20847bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 2085afddba49SNick Piggin */ 2086155130a4SChristoph Hellwig int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, 2087155130a4SChristoph Hellwig unsigned flags, struct page **pagep, get_block_t *get_block) 2088afddba49SNick Piggin { 208909cbfeafSKirill A. Shutemov pgoff_t index = pos >> PAGE_SHIFT; 2090afddba49SNick Piggin struct page *page; 20916e1db88dSChristoph Hellwig int status; 2092afddba49SNick Piggin 209354566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 20946e1db88dSChristoph Hellwig if (!page) 20956e1db88dSChristoph Hellwig return -ENOMEM; 2096afddba49SNick Piggin 20976e1db88dSChristoph Hellwig status = __block_write_begin(page, pos, len, get_block); 2098afddba49SNick Piggin if (unlikely(status)) { 2099afddba49SNick Piggin unlock_page(page); 210009cbfeafSKirill A. Shutemov put_page(page); 21016e1db88dSChristoph Hellwig page = NULL; 2102afddba49SNick Piggin } 2103afddba49SNick Piggin 21046e1db88dSChristoph Hellwig *pagep = page; 2105afddba49SNick Piggin return status; 2106afddba49SNick Piggin } 2107afddba49SNick Piggin EXPORT_SYMBOL(block_write_begin); 2108afddba49SNick Piggin 2109afddba49SNick Piggin int block_write_end(struct file *file, struct address_space *mapping, 2110afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2111afddba49SNick Piggin struct page *page, void *fsdata) 2112afddba49SNick Piggin { 2113afddba49SNick Piggin struct inode *inode = mapping->host; 2114afddba49SNick Piggin unsigned start; 2115afddba49SNick Piggin 211609cbfeafSKirill A. Shutemov start = pos & (PAGE_SIZE - 1); 2117afddba49SNick Piggin 2118afddba49SNick Piggin if (unlikely(copied < len)) { 2119afddba49SNick Piggin /* 2120afddba49SNick Piggin * The buffers that were written will now be uptodate, so we 2121afddba49SNick Piggin * don't have to worry about a readpage reading them and 2122afddba49SNick Piggin * overwriting a partial write. However if we have encountered 2123afddba49SNick Piggin * a short write and only partially written into a buffer, it 2124afddba49SNick Piggin * will not be marked uptodate, so a readpage might come in and 2125afddba49SNick Piggin * destroy our partial write. 2126afddba49SNick Piggin * 2127afddba49SNick Piggin * Do the simplest thing, and just treat any short write to a 2128afddba49SNick Piggin * non uptodate page as a zero-length write, and force the 2129afddba49SNick Piggin * caller to redo the whole thing. 2130afddba49SNick Piggin */ 2131afddba49SNick Piggin if (!PageUptodate(page)) 2132afddba49SNick Piggin copied = 0; 2133afddba49SNick Piggin 2134afddba49SNick Piggin page_zero_new_buffers(page, start+copied, start+len); 2135afddba49SNick Piggin } 2136afddba49SNick Piggin flush_dcache_page(page); 2137afddba49SNick Piggin 2138afddba49SNick Piggin /* This could be a short (even 0-length) commit */ 2139afddba49SNick Piggin __block_commit_write(inode, page, start, start+copied); 2140afddba49SNick Piggin 2141afddba49SNick Piggin return copied; 2142afddba49SNick Piggin } 2143afddba49SNick Piggin EXPORT_SYMBOL(block_write_end); 2144afddba49SNick Piggin 2145afddba49SNick Piggin int generic_write_end(struct file *file, struct address_space *mapping, 2146afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2147afddba49SNick Piggin struct page *page, void *fsdata) 2148afddba49SNick Piggin { 2149afddba49SNick Piggin struct inode *inode = mapping->host; 215090a80202SJan Kara loff_t old_size = inode->i_size; 2151c7d206b3SJan Kara int i_size_changed = 0; 2152afddba49SNick Piggin 2153afddba49SNick Piggin copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); 2154afddba49SNick Piggin 2155afddba49SNick Piggin /* 2156afddba49SNick Piggin * No need to use i_size_read() here, the i_size 2157afddba49SNick Piggin * cannot change under us because we hold i_mutex. 2158afddba49SNick Piggin * 2159afddba49SNick Piggin * But it's important to update i_size while still holding page lock: 2160afddba49SNick Piggin * page writeout could otherwise come in and zero beyond i_size. 2161afddba49SNick Piggin */ 2162afddba49SNick Piggin if (pos+copied > inode->i_size) { 2163afddba49SNick Piggin i_size_write(inode, pos+copied); 2164c7d206b3SJan Kara i_size_changed = 1; 2165afddba49SNick Piggin } 2166afddba49SNick Piggin 2167afddba49SNick Piggin unlock_page(page); 216809cbfeafSKirill A. Shutemov put_page(page); 2169afddba49SNick Piggin 217090a80202SJan Kara if (old_size < pos) 217190a80202SJan Kara pagecache_isize_extended(inode, old_size, pos); 2172c7d206b3SJan Kara /* 2173c7d206b3SJan Kara * Don't mark the inode dirty under page lock. First, it unnecessarily 2174c7d206b3SJan Kara * makes the holding time of page lock longer. Second, it forces lock 2175c7d206b3SJan Kara * ordering of page lock and transaction start for journaling 2176c7d206b3SJan Kara * filesystems. 2177c7d206b3SJan Kara */ 2178c7d206b3SJan Kara if (i_size_changed) 2179c7d206b3SJan Kara mark_inode_dirty(inode); 2180c7d206b3SJan Kara 2181afddba49SNick Piggin return copied; 2182afddba49SNick Piggin } 2183afddba49SNick Piggin EXPORT_SYMBOL(generic_write_end); 2184afddba49SNick Piggin 2185afddba49SNick Piggin /* 21868ab22b9aSHisashi Hifumi * block_is_partially_uptodate checks whether buffers within a page are 21878ab22b9aSHisashi Hifumi * uptodate or not. 21888ab22b9aSHisashi Hifumi * 21898ab22b9aSHisashi Hifumi * Returns true if all buffers which correspond to a file portion 21908ab22b9aSHisashi Hifumi * we want to read are uptodate. 21918ab22b9aSHisashi Hifumi */ 2192c186afb4SAl Viro int block_is_partially_uptodate(struct page *page, unsigned long from, 2193c186afb4SAl Viro unsigned long count) 21948ab22b9aSHisashi Hifumi { 21958ab22b9aSHisashi Hifumi unsigned block_start, block_end, blocksize; 21968ab22b9aSHisashi Hifumi unsigned to; 21978ab22b9aSHisashi Hifumi struct buffer_head *bh, *head; 21988ab22b9aSHisashi Hifumi int ret = 1; 21998ab22b9aSHisashi Hifumi 22008ab22b9aSHisashi Hifumi if (!page_has_buffers(page)) 22018ab22b9aSHisashi Hifumi return 0; 22028ab22b9aSHisashi Hifumi 220345bce8f3SLinus Torvalds head = page_buffers(page); 220445bce8f3SLinus Torvalds blocksize = head->b_size; 220509cbfeafSKirill A. Shutemov to = min_t(unsigned, PAGE_SIZE - from, count); 22068ab22b9aSHisashi Hifumi to = from + to; 220709cbfeafSKirill A. Shutemov if (from < blocksize && to > PAGE_SIZE - blocksize) 22088ab22b9aSHisashi Hifumi return 0; 22098ab22b9aSHisashi Hifumi 22108ab22b9aSHisashi Hifumi bh = head; 22118ab22b9aSHisashi Hifumi block_start = 0; 22128ab22b9aSHisashi Hifumi do { 22138ab22b9aSHisashi Hifumi block_end = block_start + blocksize; 22148ab22b9aSHisashi Hifumi if (block_end > from && block_start < to) { 22158ab22b9aSHisashi Hifumi if (!buffer_uptodate(bh)) { 22168ab22b9aSHisashi Hifumi ret = 0; 22178ab22b9aSHisashi Hifumi break; 22188ab22b9aSHisashi Hifumi } 22198ab22b9aSHisashi Hifumi if (block_end >= to) 22208ab22b9aSHisashi Hifumi break; 22218ab22b9aSHisashi Hifumi } 22228ab22b9aSHisashi Hifumi block_start = block_end; 22238ab22b9aSHisashi Hifumi bh = bh->b_this_page; 22248ab22b9aSHisashi Hifumi } while (bh != head); 22258ab22b9aSHisashi Hifumi 22268ab22b9aSHisashi Hifumi return ret; 22278ab22b9aSHisashi Hifumi } 22288ab22b9aSHisashi Hifumi EXPORT_SYMBOL(block_is_partially_uptodate); 22298ab22b9aSHisashi Hifumi 22308ab22b9aSHisashi Hifumi /* 22311da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 22321da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 22331da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 22341da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 22351da177e4SLinus Torvalds * page struct once IO has completed. 22361da177e4SLinus Torvalds */ 22371da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 22381da177e4SLinus Torvalds { 22391da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 22401da177e4SLinus Torvalds sector_t iblock, lblock; 22411da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 224245bce8f3SLinus Torvalds unsigned int blocksize, bbits; 22431da177e4SLinus Torvalds int nr, i; 22441da177e4SLinus Torvalds int fully_mapped = 1; 22451da177e4SLinus Torvalds 224645bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 224745bce8f3SLinus Torvalds blocksize = head->b_size; 224845bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 22491da177e4SLinus Torvalds 225009cbfeafSKirill A. Shutemov iblock = (sector_t)page->index << (PAGE_SHIFT - bbits); 225145bce8f3SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> bbits; 22521da177e4SLinus Torvalds bh = head; 22531da177e4SLinus Torvalds nr = 0; 22541da177e4SLinus Torvalds i = 0; 22551da177e4SLinus Torvalds 22561da177e4SLinus Torvalds do { 22571da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22581da177e4SLinus Torvalds continue; 22591da177e4SLinus Torvalds 22601da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2261c64610baSAndrew Morton int err = 0; 2262c64610baSAndrew Morton 22631da177e4SLinus Torvalds fully_mapped = 0; 22641da177e4SLinus Torvalds if (iblock < lblock) { 2265b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 2266c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 2267c64610baSAndrew Morton if (err) 22681da177e4SLinus Torvalds SetPageError(page); 22691da177e4SLinus Torvalds } 22701da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2271eebd2aa3SChristoph Lameter zero_user(page, i * blocksize, blocksize); 2272c64610baSAndrew Morton if (!err) 22731da177e4SLinus Torvalds set_buffer_uptodate(bh); 22741da177e4SLinus Torvalds continue; 22751da177e4SLinus Torvalds } 22761da177e4SLinus Torvalds /* 22771da177e4SLinus Torvalds * get_block() might have updated the buffer 22781da177e4SLinus Torvalds * synchronously 22791da177e4SLinus Torvalds */ 22801da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22811da177e4SLinus Torvalds continue; 22821da177e4SLinus Torvalds } 22831da177e4SLinus Torvalds arr[nr++] = bh; 22841da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 22851da177e4SLinus Torvalds 22861da177e4SLinus Torvalds if (fully_mapped) 22871da177e4SLinus Torvalds SetPageMappedToDisk(page); 22881da177e4SLinus Torvalds 22891da177e4SLinus Torvalds if (!nr) { 22901da177e4SLinus Torvalds /* 22911da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 22921da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 22931da177e4SLinus Torvalds */ 22941da177e4SLinus Torvalds if (!PageError(page)) 22951da177e4SLinus Torvalds SetPageUptodate(page); 22961da177e4SLinus Torvalds unlock_page(page); 22971da177e4SLinus Torvalds return 0; 22981da177e4SLinus Torvalds } 22991da177e4SLinus Torvalds 23001da177e4SLinus Torvalds /* Stage two: lock the buffers */ 23011da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 23021da177e4SLinus Torvalds bh = arr[i]; 23031da177e4SLinus Torvalds lock_buffer(bh); 23041da177e4SLinus Torvalds mark_buffer_async_read(bh); 23051da177e4SLinus Torvalds } 23061da177e4SLinus Torvalds 23071da177e4SLinus Torvalds /* 23081da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 23091da177e4SLinus Torvalds * inside the buffer lock in case another process reading 23101da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 23111da177e4SLinus Torvalds */ 23121da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 23131da177e4SLinus Torvalds bh = arr[i]; 23141da177e4SLinus Torvalds if (buffer_uptodate(bh)) 23151da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 23161da177e4SLinus Torvalds else 23172a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 23181da177e4SLinus Torvalds } 23191da177e4SLinus Torvalds return 0; 23201da177e4SLinus Torvalds } 23211fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_read_full_page); 23221da177e4SLinus Torvalds 23231da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 232489e10787SNick Piggin * truncates. Uses filesystem pagecache writes to allow the filesystem to 23251da177e4SLinus Torvalds * deal with the hole. 23261da177e4SLinus Torvalds */ 232789e10787SNick Piggin int generic_cont_expand_simple(struct inode *inode, loff_t size) 23281da177e4SLinus Torvalds { 23291da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 23301da177e4SLinus Torvalds struct page *page; 233189e10787SNick Piggin void *fsdata; 23321da177e4SLinus Torvalds int err; 23331da177e4SLinus Torvalds 2334c08d3b0eSnpiggin@suse.de err = inode_newsize_ok(inode, size); 2335c08d3b0eSnpiggin@suse.de if (err) 23361da177e4SLinus Torvalds goto out; 23371da177e4SLinus Torvalds 233889e10787SNick Piggin err = pagecache_write_begin(NULL, mapping, size, 0, 233989e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, 234089e10787SNick Piggin &page, &fsdata); 234189e10787SNick Piggin if (err) 234205eb0b51SOGAWA Hirofumi goto out; 234305eb0b51SOGAWA Hirofumi 234489e10787SNick Piggin err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); 234589e10787SNick Piggin BUG_ON(err > 0); 234605eb0b51SOGAWA Hirofumi 234705eb0b51SOGAWA Hirofumi out: 234805eb0b51SOGAWA Hirofumi return err; 234905eb0b51SOGAWA Hirofumi } 23501fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_cont_expand_simple); 235105eb0b51SOGAWA Hirofumi 2352f1e3af72SAdrian Bunk static int cont_expand_zero(struct file *file, struct address_space *mapping, 235389e10787SNick Piggin loff_t pos, loff_t *bytes) 235405eb0b51SOGAWA Hirofumi { 235589e10787SNick Piggin struct inode *inode = mapping->host; 235689e10787SNick Piggin unsigned blocksize = 1 << inode->i_blkbits; 235789e10787SNick Piggin struct page *page; 235889e10787SNick Piggin void *fsdata; 235989e10787SNick Piggin pgoff_t index, curidx; 236089e10787SNick Piggin loff_t curpos; 236189e10787SNick Piggin unsigned zerofrom, offset, len; 236289e10787SNick Piggin int err = 0; 236305eb0b51SOGAWA Hirofumi 236409cbfeafSKirill A. Shutemov index = pos >> PAGE_SHIFT; 236509cbfeafSKirill A. Shutemov offset = pos & ~PAGE_MASK; 236689e10787SNick Piggin 236709cbfeafSKirill A. Shutemov while (index > (curidx = (curpos = *bytes)>>PAGE_SHIFT)) { 236809cbfeafSKirill A. Shutemov zerofrom = curpos & ~PAGE_MASK; 236989e10787SNick Piggin if (zerofrom & (blocksize-1)) { 237089e10787SNick Piggin *bytes |= (blocksize-1); 237189e10787SNick Piggin (*bytes)++; 237289e10787SNick Piggin } 237309cbfeafSKirill A. Shutemov len = PAGE_SIZE - zerofrom; 237489e10787SNick Piggin 237589e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 237689e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 237789e10787SNick Piggin &page, &fsdata); 237889e10787SNick Piggin if (err) 237989e10787SNick Piggin goto out; 2380eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 238189e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 238289e10787SNick Piggin page, fsdata); 238389e10787SNick Piggin if (err < 0) 238489e10787SNick Piggin goto out; 238589e10787SNick Piggin BUG_ON(err != len); 238689e10787SNick Piggin err = 0; 2387061e9746SOGAWA Hirofumi 2388061e9746SOGAWA Hirofumi balance_dirty_pages_ratelimited(mapping); 2389c2ca0fcdSMikulas Patocka 2390c2ca0fcdSMikulas Patocka if (unlikely(fatal_signal_pending(current))) { 2391c2ca0fcdSMikulas Patocka err = -EINTR; 2392c2ca0fcdSMikulas Patocka goto out; 2393c2ca0fcdSMikulas Patocka } 239489e10787SNick Piggin } 239589e10787SNick Piggin 239689e10787SNick Piggin /* page covers the boundary, find the boundary offset */ 239789e10787SNick Piggin if (index == curidx) { 239809cbfeafSKirill A. Shutemov zerofrom = curpos & ~PAGE_MASK; 239989e10787SNick Piggin /* if we will expand the thing last block will be filled */ 240089e10787SNick Piggin if (offset <= zerofrom) { 240189e10787SNick Piggin goto out; 240289e10787SNick Piggin } 240389e10787SNick Piggin if (zerofrom & (blocksize-1)) { 240489e10787SNick Piggin *bytes |= (blocksize-1); 240589e10787SNick Piggin (*bytes)++; 240689e10787SNick Piggin } 240789e10787SNick Piggin len = offset - zerofrom; 240889e10787SNick Piggin 240989e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 241089e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 241189e10787SNick Piggin &page, &fsdata); 241289e10787SNick Piggin if (err) 241389e10787SNick Piggin goto out; 2414eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 241589e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 241689e10787SNick Piggin page, fsdata); 241789e10787SNick Piggin if (err < 0) 241889e10787SNick Piggin goto out; 241989e10787SNick Piggin BUG_ON(err != len); 242089e10787SNick Piggin err = 0; 242189e10787SNick Piggin } 242289e10787SNick Piggin out: 242389e10787SNick Piggin return err; 24241da177e4SLinus Torvalds } 24251da177e4SLinus Torvalds 24261da177e4SLinus Torvalds /* 24271da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 24281da177e4SLinus Torvalds * We may have to extend the file. 24291da177e4SLinus Torvalds */ 2430282dc178SChristoph Hellwig int cont_write_begin(struct file *file, struct address_space *mapping, 243189e10787SNick Piggin loff_t pos, unsigned len, unsigned flags, 243289e10787SNick Piggin struct page **pagep, void **fsdata, 243389e10787SNick Piggin get_block_t *get_block, loff_t *bytes) 24341da177e4SLinus Torvalds { 24351da177e4SLinus Torvalds struct inode *inode = mapping->host; 24361da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 243789e10787SNick Piggin unsigned zerofrom; 243889e10787SNick Piggin int err; 24391da177e4SLinus Torvalds 244089e10787SNick Piggin err = cont_expand_zero(file, mapping, pos, bytes); 244189e10787SNick Piggin if (err) 2442155130a4SChristoph Hellwig return err; 24431da177e4SLinus Torvalds 244409cbfeafSKirill A. Shutemov zerofrom = *bytes & ~PAGE_MASK; 244589e10787SNick Piggin if (pos+len > *bytes && zerofrom & (blocksize-1)) { 24461da177e4SLinus Torvalds *bytes |= (blocksize-1); 24471da177e4SLinus Torvalds (*bytes)++; 24481da177e4SLinus Torvalds } 24491da177e4SLinus Torvalds 2450155130a4SChristoph Hellwig return block_write_begin(mapping, pos, len, flags, pagep, get_block); 24511da177e4SLinus Torvalds } 24521fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(cont_write_begin); 24531da177e4SLinus Torvalds 24541da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 24551da177e4SLinus Torvalds { 24561da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 24571da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 24581da177e4SLinus Torvalds return 0; 24591da177e4SLinus Torvalds } 24601fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_commit_write); 24611da177e4SLinus Torvalds 246254171690SDavid Chinner /* 246354171690SDavid Chinner * block_page_mkwrite() is not allowed to change the file size as it gets 246454171690SDavid Chinner * called from a page fault handler when a page is first dirtied. Hence we must 246554171690SDavid Chinner * be careful to check for EOF conditions here. We set the page up correctly 246654171690SDavid Chinner * for a written page which means we get ENOSPC checking when writing into 246754171690SDavid Chinner * holes and correct delalloc and unwritten extent mapping on filesystems that 246854171690SDavid Chinner * support these features. 246954171690SDavid Chinner * 247054171690SDavid Chinner * We are not allowed to take the i_mutex here so we have to play games to 247154171690SDavid Chinner * protect against truncate races as the page could now be beyond EOF. Because 24727bb46a67Snpiggin@suse.de * truncate writes the inode size before removing pages, once we have the 247354171690SDavid Chinner * page lock we can determine safely if the page is beyond EOF. If it is not 247454171690SDavid Chinner * beyond EOF, then the page is guaranteed safe against truncation until we 247554171690SDavid Chinner * unlock the page. 2476ea13a864SJan Kara * 247714da9200SJan Kara * Direct callers of this function should protect against filesystem freezing 24785c500029SRoss Zwisler * using sb_start_pagefault() - sb_end_pagefault() functions. 247954171690SDavid Chinner */ 24805c500029SRoss Zwisler int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 248154171690SDavid Chinner get_block_t get_block) 248254171690SDavid Chinner { 2483c2ec175cSNick Piggin struct page *page = vmf->page; 2484496ad9aaSAl Viro struct inode *inode = file_inode(vma->vm_file); 248554171690SDavid Chinner unsigned long end; 248654171690SDavid Chinner loff_t size; 248724da4fabSJan Kara int ret; 248854171690SDavid Chinner 248954171690SDavid Chinner lock_page(page); 249054171690SDavid Chinner size = i_size_read(inode); 249154171690SDavid Chinner if ((page->mapping != inode->i_mapping) || 249218336338SNick Piggin (page_offset(page) > size)) { 249324da4fabSJan Kara /* We overload EFAULT to mean page got truncated */ 249424da4fabSJan Kara ret = -EFAULT; 249524da4fabSJan Kara goto out_unlock; 249654171690SDavid Chinner } 249754171690SDavid Chinner 249854171690SDavid Chinner /* page is wholly or partially inside EOF */ 249909cbfeafSKirill A. Shutemov if (((page->index + 1) << PAGE_SHIFT) > size) 250009cbfeafSKirill A. Shutemov end = size & ~PAGE_MASK; 250154171690SDavid Chinner else 250209cbfeafSKirill A. Shutemov end = PAGE_SIZE; 250354171690SDavid Chinner 2504ebdec241SChristoph Hellwig ret = __block_write_begin(page, 0, end, get_block); 250554171690SDavid Chinner if (!ret) 250654171690SDavid Chinner ret = block_commit_write(page, 0, end); 250754171690SDavid Chinner 250824da4fabSJan Kara if (unlikely(ret < 0)) 250924da4fabSJan Kara goto out_unlock; 2510ea13a864SJan Kara set_page_dirty(page); 25111d1d1a76SDarrick J. Wong wait_for_stable_page(page); 251224da4fabSJan Kara return 0; 251324da4fabSJan Kara out_unlock: 2514b827e496SNick Piggin unlock_page(page); 251554171690SDavid Chinner return ret; 251654171690SDavid Chinner } 25171fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_page_mkwrite); 25181da177e4SLinus Torvalds 25191da177e4SLinus Torvalds /* 252003158cd7SNick Piggin * nobh_write_begin()'s prereads are special: the buffer_heads are freed 25211da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 25221da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 25231da177e4SLinus Torvalds */ 25241da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 25251da177e4SLinus Torvalds { 252668671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 25271da177e4SLinus Torvalds } 25281da177e4SLinus Torvalds 25291da177e4SLinus Torvalds /* 253003158cd7SNick Piggin * Attach the singly-linked list of buffers created by nobh_write_begin, to 253103158cd7SNick Piggin * the page (converting it to circular linked list and taking care of page 253203158cd7SNick Piggin * dirty races). 253303158cd7SNick Piggin */ 253403158cd7SNick Piggin static void attach_nobh_buffers(struct page *page, struct buffer_head *head) 253503158cd7SNick Piggin { 253603158cd7SNick Piggin struct buffer_head *bh; 253703158cd7SNick Piggin 253803158cd7SNick Piggin BUG_ON(!PageLocked(page)); 253903158cd7SNick Piggin 254003158cd7SNick Piggin spin_lock(&page->mapping->private_lock); 254103158cd7SNick Piggin bh = head; 254203158cd7SNick Piggin do { 254303158cd7SNick Piggin if (PageDirty(page)) 254403158cd7SNick Piggin set_buffer_dirty(bh); 254503158cd7SNick Piggin if (!bh->b_this_page) 254603158cd7SNick Piggin bh->b_this_page = head; 254703158cd7SNick Piggin bh = bh->b_this_page; 254803158cd7SNick Piggin } while (bh != head); 254903158cd7SNick Piggin attach_page_buffers(page, head); 255003158cd7SNick Piggin spin_unlock(&page->mapping->private_lock); 255103158cd7SNick Piggin } 255203158cd7SNick Piggin 255303158cd7SNick Piggin /* 2554ea0f04e5SChristoph Hellwig * On entry, the page is fully not uptodate. 2555ea0f04e5SChristoph Hellwig * On exit the page is fully uptodate in the areas outside (from,to) 25567bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 25571da177e4SLinus Torvalds */ 2558ea0f04e5SChristoph Hellwig int nobh_write_begin(struct address_space *mapping, 255903158cd7SNick Piggin loff_t pos, unsigned len, unsigned flags, 256003158cd7SNick Piggin struct page **pagep, void **fsdata, 25611da177e4SLinus Torvalds get_block_t *get_block) 25621da177e4SLinus Torvalds { 256303158cd7SNick Piggin struct inode *inode = mapping->host; 25641da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 25651da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 2566a4b0672dSNick Piggin struct buffer_head *head, *bh; 256703158cd7SNick Piggin struct page *page; 256803158cd7SNick Piggin pgoff_t index; 256903158cd7SNick Piggin unsigned from, to; 25701da177e4SLinus Torvalds unsigned block_in_page; 2571a4b0672dSNick Piggin unsigned block_start, block_end; 25721da177e4SLinus Torvalds sector_t block_in_file; 25731da177e4SLinus Torvalds int nr_reads = 0; 25741da177e4SLinus Torvalds int ret = 0; 25751da177e4SLinus Torvalds int is_mapped_to_disk = 1; 25761da177e4SLinus Torvalds 257709cbfeafSKirill A. Shutemov index = pos >> PAGE_SHIFT; 257809cbfeafSKirill A. Shutemov from = pos & (PAGE_SIZE - 1); 257903158cd7SNick Piggin to = from + len; 258003158cd7SNick Piggin 258154566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 258203158cd7SNick Piggin if (!page) 258303158cd7SNick Piggin return -ENOMEM; 258403158cd7SNick Piggin *pagep = page; 258503158cd7SNick Piggin *fsdata = NULL; 258603158cd7SNick Piggin 258703158cd7SNick Piggin if (page_has_buffers(page)) { 2588309f77adSNamhyung Kim ret = __block_write_begin(page, pos, len, get_block); 2589309f77adSNamhyung Kim if (unlikely(ret)) 2590309f77adSNamhyung Kim goto out_release; 2591309f77adSNamhyung Kim return ret; 259203158cd7SNick Piggin } 2593a4b0672dSNick Piggin 25941da177e4SLinus Torvalds if (PageMappedToDisk(page)) 25951da177e4SLinus Torvalds return 0; 25961da177e4SLinus Torvalds 2597a4b0672dSNick Piggin /* 2598a4b0672dSNick Piggin * Allocate buffers so that we can keep track of state, and potentially 2599a4b0672dSNick Piggin * attach them to the page if an error occurs. In the common case of 2600a4b0672dSNick Piggin * no error, they will just be freed again without ever being attached 2601a4b0672dSNick Piggin * to the page (which is all OK, because we're under the page lock). 2602a4b0672dSNick Piggin * 2603a4b0672dSNick Piggin * Be careful: the buffer linked list is a NULL terminated one, rather 2604a4b0672dSNick Piggin * than the circular one we're used to. 2605a4b0672dSNick Piggin */ 2606a4b0672dSNick Piggin head = alloc_page_buffers(page, blocksize, 0); 260703158cd7SNick Piggin if (!head) { 260803158cd7SNick Piggin ret = -ENOMEM; 260903158cd7SNick Piggin goto out_release; 261003158cd7SNick Piggin } 2611a4b0672dSNick Piggin 261209cbfeafSKirill A. Shutemov block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits); 26131da177e4SLinus Torvalds 26141da177e4SLinus Torvalds /* 26151da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 26161da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 26171da177e4SLinus Torvalds * page is fully mapped-to-disk. 26181da177e4SLinus Torvalds */ 2619a4b0672dSNick Piggin for (block_start = 0, block_in_page = 0, bh = head; 262009cbfeafSKirill A. Shutemov block_start < PAGE_SIZE; 2621a4b0672dSNick Piggin block_in_page++, block_start += blocksize, bh = bh->b_this_page) { 26221da177e4SLinus Torvalds int create; 26231da177e4SLinus Torvalds 2624a4b0672dSNick Piggin block_end = block_start + blocksize; 2625a4b0672dSNick Piggin bh->b_state = 0; 26261da177e4SLinus Torvalds create = 1; 26271da177e4SLinus Torvalds if (block_start >= to) 26281da177e4SLinus Torvalds create = 0; 26291da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 2630a4b0672dSNick Piggin bh, create); 26311da177e4SLinus Torvalds if (ret) 26321da177e4SLinus Torvalds goto failed; 2633a4b0672dSNick Piggin if (!buffer_mapped(bh)) 26341da177e4SLinus Torvalds is_mapped_to_disk = 0; 2635a4b0672dSNick Piggin if (buffer_new(bh)) 2636a4b0672dSNick Piggin unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 2637a4b0672dSNick Piggin if (PageUptodate(page)) { 2638a4b0672dSNick Piggin set_buffer_uptodate(bh); 26391da177e4SLinus Torvalds continue; 2640a4b0672dSNick Piggin } 2641a4b0672dSNick Piggin if (buffer_new(bh) || !buffer_mapped(bh)) { 2642eebd2aa3SChristoph Lameter zero_user_segments(page, block_start, from, 2643eebd2aa3SChristoph Lameter to, block_end); 26441da177e4SLinus Torvalds continue; 26451da177e4SLinus Torvalds } 2646a4b0672dSNick Piggin if (buffer_uptodate(bh)) 26471da177e4SLinus Torvalds continue; /* reiserfs does this */ 26481da177e4SLinus Torvalds if (block_start < from || block_end > to) { 2649a4b0672dSNick Piggin lock_buffer(bh); 2650a4b0672dSNick Piggin bh->b_end_io = end_buffer_read_nobh; 26512a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 2652a4b0672dSNick Piggin nr_reads++; 26531da177e4SLinus Torvalds } 26541da177e4SLinus Torvalds } 26551da177e4SLinus Torvalds 26561da177e4SLinus Torvalds if (nr_reads) { 26571da177e4SLinus Torvalds /* 26581da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 26591da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 26601da177e4SLinus Torvalds * for the buffer_head refcounts. 26611da177e4SLinus Torvalds */ 2662a4b0672dSNick Piggin for (bh = head; bh; bh = bh->b_this_page) { 26631da177e4SLinus Torvalds wait_on_buffer(bh); 26641da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 26651da177e4SLinus Torvalds ret = -EIO; 26661da177e4SLinus Torvalds } 26671da177e4SLinus Torvalds if (ret) 26681da177e4SLinus Torvalds goto failed; 26691da177e4SLinus Torvalds } 26701da177e4SLinus Torvalds 26711da177e4SLinus Torvalds if (is_mapped_to_disk) 26721da177e4SLinus Torvalds SetPageMappedToDisk(page); 26731da177e4SLinus Torvalds 267403158cd7SNick Piggin *fsdata = head; /* to be released by nobh_write_end */ 2675a4b0672dSNick Piggin 26761da177e4SLinus Torvalds return 0; 26771da177e4SLinus Torvalds 26781da177e4SLinus Torvalds failed: 267903158cd7SNick Piggin BUG_ON(!ret); 26801da177e4SLinus Torvalds /* 2681a4b0672dSNick Piggin * Error recovery is a bit difficult. We need to zero out blocks that 2682a4b0672dSNick Piggin * were newly allocated, and dirty them to ensure they get written out. 2683a4b0672dSNick Piggin * Buffers need to be attached to the page at this point, otherwise 2684a4b0672dSNick Piggin * the handling of potential IO errors during writeout would be hard 2685a4b0672dSNick Piggin * (could try doing synchronous writeout, but what if that fails too?) 26861da177e4SLinus Torvalds */ 268703158cd7SNick Piggin attach_nobh_buffers(page, head); 268803158cd7SNick Piggin page_zero_new_buffers(page, from, to); 2689a4b0672dSNick Piggin 269003158cd7SNick Piggin out_release: 269103158cd7SNick Piggin unlock_page(page); 269209cbfeafSKirill A. Shutemov put_page(page); 269303158cd7SNick Piggin *pagep = NULL; 2694a4b0672dSNick Piggin 26957bb46a67Snpiggin@suse.de return ret; 26967bb46a67Snpiggin@suse.de } 269703158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_begin); 26981da177e4SLinus Torvalds 269903158cd7SNick Piggin int nobh_write_end(struct file *file, struct address_space *mapping, 270003158cd7SNick Piggin loff_t pos, unsigned len, unsigned copied, 270103158cd7SNick Piggin struct page *page, void *fsdata) 27021da177e4SLinus Torvalds { 27031da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 2704efdc3131SNick Piggin struct buffer_head *head = fsdata; 270503158cd7SNick Piggin struct buffer_head *bh; 27065b41e74aSDmitri Monakhov BUG_ON(fsdata != NULL && page_has_buffers(page)); 27071da177e4SLinus Torvalds 2708d4cf109fSDave Kleikamp if (unlikely(copied < len) && head) 270903158cd7SNick Piggin attach_nobh_buffers(page, head); 2710a4b0672dSNick Piggin if (page_has_buffers(page)) 271103158cd7SNick Piggin return generic_write_end(file, mapping, pos, len, 271203158cd7SNick Piggin copied, page, fsdata); 2713a4b0672dSNick Piggin 271422c8ca78SNick Piggin SetPageUptodate(page); 27151da177e4SLinus Torvalds set_page_dirty(page); 271603158cd7SNick Piggin if (pos+copied > inode->i_size) { 271703158cd7SNick Piggin i_size_write(inode, pos+copied); 27181da177e4SLinus Torvalds mark_inode_dirty(inode); 27191da177e4SLinus Torvalds } 272003158cd7SNick Piggin 272103158cd7SNick Piggin unlock_page(page); 272209cbfeafSKirill A. Shutemov put_page(page); 272303158cd7SNick Piggin 272403158cd7SNick Piggin while (head) { 272503158cd7SNick Piggin bh = head; 272603158cd7SNick Piggin head = head->b_this_page; 272703158cd7SNick Piggin free_buffer_head(bh); 27281da177e4SLinus Torvalds } 272903158cd7SNick Piggin 273003158cd7SNick Piggin return copied; 273103158cd7SNick Piggin } 273203158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_end); 27331da177e4SLinus Torvalds 27341da177e4SLinus Torvalds /* 27351da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 27361da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 27371da177e4SLinus Torvalds * the page. 27381da177e4SLinus Torvalds */ 27391da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 27401da177e4SLinus Torvalds struct writeback_control *wbc) 27411da177e4SLinus Torvalds { 27421da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 27431da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 274409cbfeafSKirill A. Shutemov const pgoff_t end_index = i_size >> PAGE_SHIFT; 27451da177e4SLinus Torvalds unsigned offset; 27461da177e4SLinus Torvalds int ret; 27471da177e4SLinus Torvalds 27481da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 27491da177e4SLinus Torvalds if (page->index < end_index) 27501da177e4SLinus Torvalds goto out; 27511da177e4SLinus Torvalds 27521da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 275309cbfeafSKirill A. Shutemov offset = i_size & (PAGE_SIZE-1); 27541da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 27551da177e4SLinus Torvalds /* 27561da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 27571da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 27581da177e4SLinus Torvalds * freeable here, so the page does not leak. 27591da177e4SLinus Torvalds */ 27601da177e4SLinus Torvalds #if 0 27611da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 27621da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 27631da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 27641da177e4SLinus Torvalds #endif 27651da177e4SLinus Torvalds unlock_page(page); 27661da177e4SLinus Torvalds return 0; /* don't care */ 27671da177e4SLinus Torvalds } 27681da177e4SLinus Torvalds 27691da177e4SLinus Torvalds /* 27701da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 27711da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 27721da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 27731da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 27741da177e4SLinus Torvalds * writes to that region are not written out to the file." 27751da177e4SLinus Torvalds */ 277609cbfeafSKirill A. Shutemov zero_user_segment(page, offset, PAGE_SIZE); 27771da177e4SLinus Torvalds out: 27781da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 27791da177e4SLinus Torvalds if (ret == -EAGAIN) 278035c80d5fSChris Mason ret = __block_write_full_page(inode, page, get_block, wbc, 278135c80d5fSChris Mason end_buffer_async_write); 27821da177e4SLinus Torvalds return ret; 27831da177e4SLinus Torvalds } 27841da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 27851da177e4SLinus Torvalds 278603158cd7SNick Piggin int nobh_truncate_page(struct address_space *mapping, 278703158cd7SNick Piggin loff_t from, get_block_t *get_block) 27881da177e4SLinus Torvalds { 278909cbfeafSKirill A. Shutemov pgoff_t index = from >> PAGE_SHIFT; 279009cbfeafSKirill A. Shutemov unsigned offset = from & (PAGE_SIZE-1); 279103158cd7SNick Piggin unsigned blocksize; 279203158cd7SNick Piggin sector_t iblock; 279303158cd7SNick Piggin unsigned length, pos; 279403158cd7SNick Piggin struct inode *inode = mapping->host; 27951da177e4SLinus Torvalds struct page *page; 279603158cd7SNick Piggin struct buffer_head map_bh; 279703158cd7SNick Piggin int err; 27981da177e4SLinus Torvalds 279903158cd7SNick Piggin blocksize = 1 << inode->i_blkbits; 280003158cd7SNick Piggin length = offset & (blocksize - 1); 28011da177e4SLinus Torvalds 280203158cd7SNick Piggin /* Block boundary? Nothing to do */ 280303158cd7SNick Piggin if (!length) 280403158cd7SNick Piggin return 0; 280503158cd7SNick Piggin 280603158cd7SNick Piggin length = blocksize - length; 280709cbfeafSKirill A. Shutemov iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); 280803158cd7SNick Piggin 28091da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 281003158cd7SNick Piggin err = -ENOMEM; 28111da177e4SLinus Torvalds if (!page) 28121da177e4SLinus Torvalds goto out; 28131da177e4SLinus Torvalds 281403158cd7SNick Piggin if (page_has_buffers(page)) { 281503158cd7SNick Piggin has_buffers: 281603158cd7SNick Piggin unlock_page(page); 281709cbfeafSKirill A. Shutemov put_page(page); 281803158cd7SNick Piggin return block_truncate_page(mapping, from, get_block); 28191da177e4SLinus Torvalds } 282003158cd7SNick Piggin 282103158cd7SNick Piggin /* Find the buffer that contains "offset" */ 282203158cd7SNick Piggin pos = blocksize; 282303158cd7SNick Piggin while (offset >= pos) { 282403158cd7SNick Piggin iblock++; 282503158cd7SNick Piggin pos += blocksize; 282603158cd7SNick Piggin } 282703158cd7SNick Piggin 2828460bcf57STheodore Ts'o map_bh.b_size = blocksize; 2829460bcf57STheodore Ts'o map_bh.b_state = 0; 283003158cd7SNick Piggin err = get_block(inode, iblock, &map_bh, 0); 283103158cd7SNick Piggin if (err) 283203158cd7SNick Piggin goto unlock; 283303158cd7SNick Piggin /* unmapped? It's a hole - nothing to do */ 283403158cd7SNick Piggin if (!buffer_mapped(&map_bh)) 283503158cd7SNick Piggin goto unlock; 283603158cd7SNick Piggin 283703158cd7SNick Piggin /* Ok, it's mapped. Make sure it's up-to-date */ 283803158cd7SNick Piggin if (!PageUptodate(page)) { 283903158cd7SNick Piggin err = mapping->a_ops->readpage(NULL, page); 284003158cd7SNick Piggin if (err) { 284109cbfeafSKirill A. Shutemov put_page(page); 284203158cd7SNick Piggin goto out; 284303158cd7SNick Piggin } 284403158cd7SNick Piggin lock_page(page); 284503158cd7SNick Piggin if (!PageUptodate(page)) { 284603158cd7SNick Piggin err = -EIO; 284703158cd7SNick Piggin goto unlock; 284803158cd7SNick Piggin } 284903158cd7SNick Piggin if (page_has_buffers(page)) 285003158cd7SNick Piggin goto has_buffers; 285103158cd7SNick Piggin } 2852eebd2aa3SChristoph Lameter zero_user(page, offset, length); 285303158cd7SNick Piggin set_page_dirty(page); 285403158cd7SNick Piggin err = 0; 285503158cd7SNick Piggin 285603158cd7SNick Piggin unlock: 28571da177e4SLinus Torvalds unlock_page(page); 285809cbfeafSKirill A. Shutemov put_page(page); 28591da177e4SLinus Torvalds out: 286003158cd7SNick Piggin return err; 28611da177e4SLinus Torvalds } 28621da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 28631da177e4SLinus Torvalds 28641da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 28651da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 28661da177e4SLinus Torvalds { 286709cbfeafSKirill A. Shutemov pgoff_t index = from >> PAGE_SHIFT; 286809cbfeafSKirill A. Shutemov unsigned offset = from & (PAGE_SIZE-1); 28691da177e4SLinus Torvalds unsigned blocksize; 287054b21a79SAndrew Morton sector_t iblock; 28711da177e4SLinus Torvalds unsigned length, pos; 28721da177e4SLinus Torvalds struct inode *inode = mapping->host; 28731da177e4SLinus Torvalds struct page *page; 28741da177e4SLinus Torvalds struct buffer_head *bh; 28751da177e4SLinus Torvalds int err; 28761da177e4SLinus Torvalds 28771da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 28781da177e4SLinus Torvalds length = offset & (blocksize - 1); 28791da177e4SLinus Torvalds 28801da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 28811da177e4SLinus Torvalds if (!length) 28821da177e4SLinus Torvalds return 0; 28831da177e4SLinus Torvalds 28841da177e4SLinus Torvalds length = blocksize - length; 288509cbfeafSKirill A. Shutemov iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); 28861da177e4SLinus Torvalds 28871da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 28881da177e4SLinus Torvalds err = -ENOMEM; 28891da177e4SLinus Torvalds if (!page) 28901da177e4SLinus Torvalds goto out; 28911da177e4SLinus Torvalds 28921da177e4SLinus Torvalds if (!page_has_buffers(page)) 28931da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 28941da177e4SLinus Torvalds 28951da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 28961da177e4SLinus Torvalds bh = page_buffers(page); 28971da177e4SLinus Torvalds pos = blocksize; 28981da177e4SLinus Torvalds while (offset >= pos) { 28991da177e4SLinus Torvalds bh = bh->b_this_page; 29001da177e4SLinus Torvalds iblock++; 29011da177e4SLinus Torvalds pos += blocksize; 29021da177e4SLinus Torvalds } 29031da177e4SLinus Torvalds 29041da177e4SLinus Torvalds err = 0; 29051da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2906b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 29071da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 29081da177e4SLinus Torvalds if (err) 29091da177e4SLinus Torvalds goto unlock; 29101da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 29111da177e4SLinus Torvalds if (!buffer_mapped(bh)) 29121da177e4SLinus Torvalds goto unlock; 29131da177e4SLinus Torvalds } 29141da177e4SLinus Torvalds 29151da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 29161da177e4SLinus Torvalds if (PageUptodate(page)) 29171da177e4SLinus Torvalds set_buffer_uptodate(bh); 29181da177e4SLinus Torvalds 291933a266ddSDavid Chinner if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { 29201da177e4SLinus Torvalds err = -EIO; 2921dfec8a14SMike Christie ll_rw_block(REQ_OP_READ, 0, 1, &bh); 29221da177e4SLinus Torvalds wait_on_buffer(bh); 29231da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 29241da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 29251da177e4SLinus Torvalds goto unlock; 29261da177e4SLinus Torvalds } 29271da177e4SLinus Torvalds 2928eebd2aa3SChristoph Lameter zero_user(page, offset, length); 29291da177e4SLinus Torvalds mark_buffer_dirty(bh); 29301da177e4SLinus Torvalds err = 0; 29311da177e4SLinus Torvalds 29321da177e4SLinus Torvalds unlock: 29331da177e4SLinus Torvalds unlock_page(page); 293409cbfeafSKirill A. Shutemov put_page(page); 29351da177e4SLinus Torvalds out: 29361da177e4SLinus Torvalds return err; 29371da177e4SLinus Torvalds } 29381fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_truncate_page); 29391da177e4SLinus Torvalds 29401da177e4SLinus Torvalds /* 29411da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 29421da177e4SLinus Torvalds */ 29431b938c08SMatthew Wilcox int block_write_full_page(struct page *page, get_block_t *get_block, 29441b938c08SMatthew Wilcox struct writeback_control *wbc) 29451da177e4SLinus Torvalds { 29461da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 29471da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 294809cbfeafSKirill A. Shutemov const pgoff_t end_index = i_size >> PAGE_SHIFT; 29491da177e4SLinus Torvalds unsigned offset; 29501da177e4SLinus Torvalds 29511da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 29521da177e4SLinus Torvalds if (page->index < end_index) 295335c80d5fSChris Mason return __block_write_full_page(inode, page, get_block, wbc, 29541b938c08SMatthew Wilcox end_buffer_async_write); 29551da177e4SLinus Torvalds 29561da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 295709cbfeafSKirill A. Shutemov offset = i_size & (PAGE_SIZE-1); 29581da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 29591da177e4SLinus Torvalds /* 29601da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 29611da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 29621da177e4SLinus Torvalds * freeable here, so the page does not leak. 29631da177e4SLinus Torvalds */ 296409cbfeafSKirill A. Shutemov do_invalidatepage(page, 0, PAGE_SIZE); 29651da177e4SLinus Torvalds unlock_page(page); 29661da177e4SLinus Torvalds return 0; /* don't care */ 29671da177e4SLinus Torvalds } 29681da177e4SLinus Torvalds 29691da177e4SLinus Torvalds /* 29701da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 29712a61aa40SAdam Buchbinder * writepage invocation because it may be mmapped. "A file is mapped 29721da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 29731da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 29741da177e4SLinus Torvalds * writes to that region are not written out to the file." 29751da177e4SLinus Torvalds */ 297609cbfeafSKirill A. Shutemov zero_user_segment(page, offset, PAGE_SIZE); 29771b938c08SMatthew Wilcox return __block_write_full_page(inode, page, get_block, wbc, 297835c80d5fSChris Mason end_buffer_async_write); 297935c80d5fSChris Mason } 29801fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_write_full_page); 298135c80d5fSChris Mason 29821da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 29831da177e4SLinus Torvalds get_block_t *get_block) 29841da177e4SLinus Torvalds { 29851da177e4SLinus Torvalds struct buffer_head tmp; 29861da177e4SLinus Torvalds struct inode *inode = mapping->host; 29871da177e4SLinus Torvalds tmp.b_state = 0; 29881da177e4SLinus Torvalds tmp.b_blocknr = 0; 2989b0cf2321SBadari Pulavarty tmp.b_size = 1 << inode->i_blkbits; 29901da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 29911da177e4SLinus Torvalds return tmp.b_blocknr; 29921da177e4SLinus Torvalds } 29931fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_block_bmap); 29941da177e4SLinus Torvalds 29954246a0b6SChristoph Hellwig static void end_bio_bh_io_sync(struct bio *bio) 29961da177e4SLinus Torvalds { 29971da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 29981da177e4SLinus Torvalds 2999b7c44ed9SJens Axboe if (unlikely(bio_flagged(bio, BIO_QUIET))) 300008bafc03SKeith Mannthey set_bit(BH_Quiet, &bh->b_state); 300108bafc03SKeith Mannthey 30024246a0b6SChristoph Hellwig bh->b_end_io(bh, !bio->bi_error); 30031da177e4SLinus Torvalds bio_put(bio); 30041da177e4SLinus Torvalds } 30051da177e4SLinus Torvalds 300657302e0dSLinus Torvalds /* 300757302e0dSLinus Torvalds * This allows us to do IO even on the odd last sectors 300859d43914SAkinobu Mita * of a device, even if the block size is some multiple 300957302e0dSLinus Torvalds * of the physical sector size. 301057302e0dSLinus Torvalds * 301157302e0dSLinus Torvalds * We'll just truncate the bio to the size of the device, 301257302e0dSLinus Torvalds * and clear the end of the buffer head manually. 301357302e0dSLinus Torvalds * 301457302e0dSLinus Torvalds * Truly out-of-range accesses will turn into actual IO 301557302e0dSLinus Torvalds * errors, this only handles the "we need to be able to 301657302e0dSLinus Torvalds * do IO at the final sector" case. 301757302e0dSLinus Torvalds */ 30182a222ca9SMike Christie void guard_bio_eod(int op, struct bio *bio) 301957302e0dSLinus Torvalds { 302057302e0dSLinus Torvalds sector_t maxsector; 302159d43914SAkinobu Mita struct bio_vec *bvec = &bio->bi_io_vec[bio->bi_vcnt - 1]; 302259d43914SAkinobu Mita unsigned truncated_bytes; 302357302e0dSLinus Torvalds 302457302e0dSLinus Torvalds maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; 302557302e0dSLinus Torvalds if (!maxsector) 302657302e0dSLinus Torvalds return; 302757302e0dSLinus Torvalds 302857302e0dSLinus Torvalds /* 302957302e0dSLinus Torvalds * If the *whole* IO is past the end of the device, 303057302e0dSLinus Torvalds * let it through, and the IO layer will turn it into 303157302e0dSLinus Torvalds * an EIO. 303257302e0dSLinus Torvalds */ 30334f024f37SKent Overstreet if (unlikely(bio->bi_iter.bi_sector >= maxsector)) 303457302e0dSLinus Torvalds return; 303557302e0dSLinus Torvalds 30364f024f37SKent Overstreet maxsector -= bio->bi_iter.bi_sector; 303759d43914SAkinobu Mita if (likely((bio->bi_iter.bi_size >> 9) <= maxsector)) 303857302e0dSLinus Torvalds return; 303957302e0dSLinus Torvalds 304059d43914SAkinobu Mita /* Uhhuh. We've got a bio that straddles the device size! */ 304159d43914SAkinobu Mita truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9); 304257302e0dSLinus Torvalds 304357302e0dSLinus Torvalds /* Truncate the bio.. */ 304459d43914SAkinobu Mita bio->bi_iter.bi_size -= truncated_bytes; 304559d43914SAkinobu Mita bvec->bv_len -= truncated_bytes; 304657302e0dSLinus Torvalds 304757302e0dSLinus Torvalds /* ..and clear the end of the buffer for reads */ 30482a222ca9SMike Christie if (op == REQ_OP_READ) { 304959d43914SAkinobu Mita zero_user(bvec->bv_page, bvec->bv_offset + bvec->bv_len, 305059d43914SAkinobu Mita truncated_bytes); 305157302e0dSLinus Torvalds } 305257302e0dSLinus Torvalds } 305357302e0dSLinus Torvalds 30542a222ca9SMike Christie static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, 3055b16b1debSTejun Heo unsigned long bio_flags, struct writeback_control *wbc) 30561da177e4SLinus Torvalds { 30571da177e4SLinus Torvalds struct bio *bio; 30581da177e4SLinus Torvalds 30591da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 30601da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 30611da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 30628fb0e342SAneesh Kumar K.V BUG_ON(buffer_delay(bh)); 30638fb0e342SAneesh Kumar K.V BUG_ON(buffer_unwritten(bh)); 30641da177e4SLinus Torvalds 306548fd4f93SJens Axboe /* 306648fd4f93SJens Axboe * Only clear out a write error when rewriting 30671da177e4SLinus Torvalds */ 30682a222ca9SMike Christie if (test_set_buffer_req(bh) && (op == REQ_OP_WRITE)) 30691da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 30701da177e4SLinus Torvalds 30711da177e4SLinus Torvalds /* 30721da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 30731da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 30741da177e4SLinus Torvalds */ 30751da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 30761da177e4SLinus Torvalds 30772a814908STejun Heo if (wbc) { 3078b16b1debSTejun Heo wbc_init_bio(wbc, bio); 30792a814908STejun Heo wbc_account_io(wbc, bh->b_page, bh->b_size); 30802a814908STejun Heo } 3081bafc0dbaSTejun Heo 30824f024f37SKent Overstreet bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); 30831da177e4SLinus Torvalds bio->bi_bdev = bh->b_bdev; 30841da177e4SLinus Torvalds 30856cf66b4cSKent Overstreet bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh)); 30866cf66b4cSKent Overstreet BUG_ON(bio->bi_iter.bi_size != bh->b_size); 30871da177e4SLinus Torvalds 30881da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 30891da177e4SLinus Torvalds bio->bi_private = bh; 309071368511SDarrick J. Wong bio->bi_flags |= bio_flags; 30911da177e4SLinus Torvalds 309257302e0dSLinus Torvalds /* Take care of bh's that straddle the end of the device */ 30932a222ca9SMike Christie guard_bio_eod(op, bio); 309457302e0dSLinus Torvalds 3095877f962cSTheodore Ts'o if (buffer_meta(bh)) 30962a222ca9SMike Christie op_flags |= REQ_META; 3097877f962cSTheodore Ts'o if (buffer_prio(bh)) 30982a222ca9SMike Christie op_flags |= REQ_PRIO; 30992a222ca9SMike Christie bio_set_op_attrs(bio, op, op_flags); 3100877f962cSTheodore Ts'o 31014e49ea4aSMike Christie submit_bio(bio); 3102f6454b04SJulia Lawall return 0; 31031da177e4SLinus Torvalds } 3104bafc0dbaSTejun Heo 31052a222ca9SMike Christie int _submit_bh(int op, int op_flags, struct buffer_head *bh, 31062a222ca9SMike Christie unsigned long bio_flags) 3107bafc0dbaSTejun Heo { 31082a222ca9SMike Christie return submit_bh_wbc(op, op_flags, bh, bio_flags, NULL); 3109bafc0dbaSTejun Heo } 311071368511SDarrick J. Wong EXPORT_SYMBOL_GPL(_submit_bh); 311171368511SDarrick J. Wong 31122a222ca9SMike Christie int submit_bh(int op, int op_flags, struct buffer_head *bh) 311371368511SDarrick J. Wong { 31142a222ca9SMike Christie return submit_bh_wbc(op, op_flags, bh, 0, NULL); 311571368511SDarrick J. Wong } 31161fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(submit_bh); 31171da177e4SLinus Torvalds 31181da177e4SLinus Torvalds /** 31191da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 3120dfec8a14SMike Christie * @op: whether to %READ or %WRITE 3121*ef295ecfSChristoph Hellwig * @op_flags: req_flag_bits 31221da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 31231da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 31241da177e4SLinus Torvalds * 3125a7662236SJan Kara * ll_rw_block() takes an array of pointers to &struct buffer_heads, and 312670246286SChristoph Hellwig * requests an I/O operation on them, either a %REQ_OP_READ or a %REQ_OP_WRITE. 312770246286SChristoph Hellwig * @op_flags contains flags modifying the detailed I/O behavior, most notably 312870246286SChristoph Hellwig * %REQ_RAHEAD. 31291da177e4SLinus Torvalds * 31301da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 31319cb569d6SChristoph Hellwig * BH_Lock state bit), any buffer that appears to be clean when doing a write 31329cb569d6SChristoph Hellwig * request, and any buffer that appears to be up-to-date when doing read 31339cb569d6SChristoph Hellwig * request. Further it marks as clean buffers that are processed for 31349cb569d6SChristoph Hellwig * writing (the buffer cache won't assume that they are actually clean 31359cb569d6SChristoph Hellwig * until the buffer gets unlocked). 31361da177e4SLinus Torvalds * 31371da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 3138e227867fSMasanari Iida * the buffer up-to-date (if appropriate), unlocks the buffer and wakes 31391da177e4SLinus Torvalds * any waiters. 31401da177e4SLinus Torvalds * 31411da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 31421da177e4SLinus Torvalds * multiple of the current approved size for the device. 31431da177e4SLinus Torvalds */ 3144dfec8a14SMike Christie void ll_rw_block(int op, int op_flags, int nr, struct buffer_head *bhs[]) 31451da177e4SLinus Torvalds { 31461da177e4SLinus Torvalds int i; 31471da177e4SLinus Torvalds 31481da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 31491da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 31501da177e4SLinus Torvalds 31519cb569d6SChristoph Hellwig if (!trylock_buffer(bh)) 31521da177e4SLinus Torvalds continue; 3153dfec8a14SMike Christie if (op == WRITE) { 31541da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 315576c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 3156e60e5c50SOGAWA Hirofumi get_bh(bh); 3157dfec8a14SMike Christie submit_bh(op, op_flags, bh); 31581da177e4SLinus Torvalds continue; 31591da177e4SLinus Torvalds } 31601da177e4SLinus Torvalds } else { 31611da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 316276c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 3163e60e5c50SOGAWA Hirofumi get_bh(bh); 3164dfec8a14SMike Christie submit_bh(op, op_flags, bh); 31651da177e4SLinus Torvalds continue; 31661da177e4SLinus Torvalds } 31671da177e4SLinus Torvalds } 31681da177e4SLinus Torvalds unlock_buffer(bh); 31691da177e4SLinus Torvalds } 31701da177e4SLinus Torvalds } 31711fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(ll_rw_block); 31721da177e4SLinus Torvalds 31732a222ca9SMike Christie void write_dirty_buffer(struct buffer_head *bh, int op_flags) 31749cb569d6SChristoph Hellwig { 31759cb569d6SChristoph Hellwig lock_buffer(bh); 31769cb569d6SChristoph Hellwig if (!test_clear_buffer_dirty(bh)) { 31779cb569d6SChristoph Hellwig unlock_buffer(bh); 31789cb569d6SChristoph Hellwig return; 31799cb569d6SChristoph Hellwig } 31809cb569d6SChristoph Hellwig bh->b_end_io = end_buffer_write_sync; 31819cb569d6SChristoph Hellwig get_bh(bh); 31822a222ca9SMike Christie submit_bh(REQ_OP_WRITE, op_flags, bh); 31839cb569d6SChristoph Hellwig } 31849cb569d6SChristoph Hellwig EXPORT_SYMBOL(write_dirty_buffer); 31859cb569d6SChristoph Hellwig 31861da177e4SLinus Torvalds /* 31871da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 31881da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 31891da177e4SLinus Torvalds * the buffer_head. 31901da177e4SLinus Torvalds */ 31912a222ca9SMike Christie int __sync_dirty_buffer(struct buffer_head *bh, int op_flags) 31921da177e4SLinus Torvalds { 31931da177e4SLinus Torvalds int ret = 0; 31941da177e4SLinus Torvalds 31951da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 31961da177e4SLinus Torvalds lock_buffer(bh); 31971da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 31981da177e4SLinus Torvalds get_bh(bh); 31991da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 32002a222ca9SMike Christie ret = submit_bh(REQ_OP_WRITE, op_flags, bh); 32011da177e4SLinus Torvalds wait_on_buffer(bh); 32021da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 32031da177e4SLinus Torvalds ret = -EIO; 32041da177e4SLinus Torvalds } else { 32051da177e4SLinus Torvalds unlock_buffer(bh); 32061da177e4SLinus Torvalds } 32071da177e4SLinus Torvalds return ret; 32081da177e4SLinus Torvalds } 320987e99511SChristoph Hellwig EXPORT_SYMBOL(__sync_dirty_buffer); 321087e99511SChristoph Hellwig 321187e99511SChristoph Hellwig int sync_dirty_buffer(struct buffer_head *bh) 321287e99511SChristoph Hellwig { 321387e99511SChristoph Hellwig return __sync_dirty_buffer(bh, WRITE_SYNC); 321487e99511SChristoph Hellwig } 32151fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(sync_dirty_buffer); 32161da177e4SLinus Torvalds 32171da177e4SLinus Torvalds /* 32181da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 32191da177e4SLinus Torvalds * are unused, and releases them if so. 32201da177e4SLinus Torvalds * 32211da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 32221da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 32231da177e4SLinus Torvalds * 32241da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 32251da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 32261da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 32271da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 32281da177e4SLinus Torvalds * filesystem data on the same device. 32291da177e4SLinus Torvalds * 32301da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 32311da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 32321da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 32331da177e4SLinus Torvalds * private_lock. 32341da177e4SLinus Torvalds * 32351da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 32361da177e4SLinus Torvalds */ 32371da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 32381da177e4SLinus Torvalds { 32391da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 32401da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 32411da177e4SLinus Torvalds } 32421da177e4SLinus Torvalds 32431da177e4SLinus Torvalds static int 32441da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 32451da177e4SLinus Torvalds { 32461da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 32471da177e4SLinus Torvalds struct buffer_head *bh; 32481da177e4SLinus Torvalds 32491da177e4SLinus Torvalds bh = head; 32501da177e4SLinus Torvalds do { 3251de7d5a3bSakpm@osdl.org if (buffer_write_io_error(bh) && page->mapping) 32525114a97aSMichal Hocko mapping_set_error(page->mapping, -EIO); 32531da177e4SLinus Torvalds if (buffer_busy(bh)) 32541da177e4SLinus Torvalds goto failed; 32551da177e4SLinus Torvalds bh = bh->b_this_page; 32561da177e4SLinus Torvalds } while (bh != head); 32571da177e4SLinus Torvalds 32581da177e4SLinus Torvalds do { 32591da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 32601da177e4SLinus Torvalds 3261535ee2fbSJan Kara if (bh->b_assoc_map) 32621da177e4SLinus Torvalds __remove_assoc_queue(bh); 32631da177e4SLinus Torvalds bh = next; 32641da177e4SLinus Torvalds } while (bh != head); 32651da177e4SLinus Torvalds *buffers_to_free = head; 32661da177e4SLinus Torvalds __clear_page_buffers(page); 32671da177e4SLinus Torvalds return 1; 32681da177e4SLinus Torvalds failed: 32691da177e4SLinus Torvalds return 0; 32701da177e4SLinus Torvalds } 32711da177e4SLinus Torvalds 32721da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 32731da177e4SLinus Torvalds { 32741da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 32751da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 32761da177e4SLinus Torvalds int ret = 0; 32771da177e4SLinus Torvalds 32781da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 3279ecdfc978SLinus Torvalds if (PageWriteback(page)) 32801da177e4SLinus Torvalds return 0; 32811da177e4SLinus Torvalds 32821da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 32831da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 32841da177e4SLinus Torvalds goto out; 32851da177e4SLinus Torvalds } 32861da177e4SLinus Torvalds 32871da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 32881da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 3289ecdfc978SLinus Torvalds 3290ecdfc978SLinus Torvalds /* 3291ecdfc978SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 3292ecdfc978SLinus Torvalds * then we can have clean buffers against a dirty page. We 3293ecdfc978SLinus Torvalds * clean the page here; otherwise the VM will never notice 3294ecdfc978SLinus Torvalds * that the filesystem did any IO at all. 3295ecdfc978SLinus Torvalds * 3296ecdfc978SLinus Torvalds * Also, during truncate, discard_buffer will have marked all 3297ecdfc978SLinus Torvalds * the page's buffers clean. We discover that here and clean 3298ecdfc978SLinus Torvalds * the page also. 329987df7241SNick Piggin * 330087df7241SNick Piggin * private_lock must be held over this entire operation in order 330187df7241SNick Piggin * to synchronise against __set_page_dirty_buffers and prevent the 330287df7241SNick Piggin * dirty bit from being lost. 3303ecdfc978SLinus Torvalds */ 330411f81becSTejun Heo if (ret) 330511f81becSTejun Heo cancel_dirty_page(page); 330687df7241SNick Piggin spin_unlock(&mapping->private_lock); 33071da177e4SLinus Torvalds out: 33081da177e4SLinus Torvalds if (buffers_to_free) { 33091da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 33101da177e4SLinus Torvalds 33111da177e4SLinus Torvalds do { 33121da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 33131da177e4SLinus Torvalds free_buffer_head(bh); 33141da177e4SLinus Torvalds bh = next; 33151da177e4SLinus Torvalds } while (bh != buffers_to_free); 33161da177e4SLinus Torvalds } 33171da177e4SLinus Torvalds return ret; 33181da177e4SLinus Torvalds } 33191da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 33201da177e4SLinus Torvalds 33211da177e4SLinus Torvalds /* 33221da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 33231da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 33241da177e4SLinus Torvalds * 33251da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 33265b0830cbSJens Axboe * The `flush-X' kernel threads fully replace bdflush daemons and this call. 33271da177e4SLinus Torvalds */ 3328bdc480e3SHeiko Carstens SYSCALL_DEFINE2(bdflush, int, func, long, data) 33291da177e4SLinus Torvalds { 33301da177e4SLinus Torvalds static int msg_count; 33311da177e4SLinus Torvalds 33321da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 33331da177e4SLinus Torvalds return -EPERM; 33341da177e4SLinus Torvalds 33351da177e4SLinus Torvalds if (msg_count < 5) { 33361da177e4SLinus Torvalds msg_count++; 33371da177e4SLinus Torvalds printk(KERN_INFO 33381da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 33391da177e4SLinus Torvalds " system call\n", current->comm); 33401da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 33411da177e4SLinus Torvalds } 33421da177e4SLinus Torvalds 33431da177e4SLinus Torvalds if (func == 1) 33441da177e4SLinus Torvalds do_exit(0); 33451da177e4SLinus Torvalds return 0; 33461da177e4SLinus Torvalds } 33471da177e4SLinus Torvalds 33481da177e4SLinus Torvalds /* 33491da177e4SLinus Torvalds * Buffer-head allocation 33501da177e4SLinus Torvalds */ 3351a0a9b043SShai Fultheim static struct kmem_cache *bh_cachep __read_mostly; 33521da177e4SLinus Torvalds 33531da177e4SLinus Torvalds /* 33541da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 33551da177e4SLinus Torvalds * stripping them in writeback. 33561da177e4SLinus Torvalds */ 335743be594aSZhang Yanfei static unsigned long max_buffer_heads; 33581da177e4SLinus Torvalds 33591da177e4SLinus Torvalds int buffer_heads_over_limit; 33601da177e4SLinus Torvalds 33611da177e4SLinus Torvalds struct bh_accounting { 33621da177e4SLinus Torvalds int nr; /* Number of live bh's */ 33631da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 33641da177e4SLinus Torvalds }; 33651da177e4SLinus Torvalds 33661da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 33671da177e4SLinus Torvalds 33681da177e4SLinus Torvalds static void recalc_bh_state(void) 33691da177e4SLinus Torvalds { 33701da177e4SLinus Torvalds int i; 33711da177e4SLinus Torvalds int tot = 0; 33721da177e4SLinus Torvalds 3373ee1be862SChristoph Lameter if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) 33741da177e4SLinus Torvalds return; 3375c7b92516SChristoph Lameter __this_cpu_write(bh_accounting.ratelimit, 0); 33768a143426SEric Dumazet for_each_online_cpu(i) 33771da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 33781da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 33791da177e4SLinus Torvalds } 33801da177e4SLinus Torvalds 3381dd0fc66fSAl Viro struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) 33821da177e4SLinus Torvalds { 3383019b4d12SRichard Kennedy struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); 33841da177e4SLinus Torvalds if (ret) { 3385a35afb83SChristoph Lameter INIT_LIST_HEAD(&ret->b_assoc_buffers); 3386c7b92516SChristoph Lameter preempt_disable(); 3387c7b92516SChristoph Lameter __this_cpu_inc(bh_accounting.nr); 33881da177e4SLinus Torvalds recalc_bh_state(); 3389c7b92516SChristoph Lameter preempt_enable(); 33901da177e4SLinus Torvalds } 33911da177e4SLinus Torvalds return ret; 33921da177e4SLinus Torvalds } 33931da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 33941da177e4SLinus Torvalds 33951da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 33961da177e4SLinus Torvalds { 33971da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 33981da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 3399c7b92516SChristoph Lameter preempt_disable(); 3400c7b92516SChristoph Lameter __this_cpu_dec(bh_accounting.nr); 34011da177e4SLinus Torvalds recalc_bh_state(); 3402c7b92516SChristoph Lameter preempt_enable(); 34031da177e4SLinus Torvalds } 34041da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 34051da177e4SLinus Torvalds 34061da177e4SLinus Torvalds static void buffer_exit_cpu(int cpu) 34071da177e4SLinus Torvalds { 34081da177e4SLinus Torvalds int i; 34091da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 34101da177e4SLinus Torvalds 34111da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 34121da177e4SLinus Torvalds brelse(b->bhs[i]); 34131da177e4SLinus Torvalds b->bhs[i] = NULL; 34141da177e4SLinus Torvalds } 3415c7b92516SChristoph Lameter this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); 34168a143426SEric Dumazet per_cpu(bh_accounting, cpu).nr = 0; 34171da177e4SLinus Torvalds } 34181da177e4SLinus Torvalds 34191da177e4SLinus Torvalds static int buffer_cpu_notify(struct notifier_block *self, 34201da177e4SLinus Torvalds unsigned long action, void *hcpu) 34211da177e4SLinus Torvalds { 34228bb78442SRafael J. Wysocki if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) 34231da177e4SLinus Torvalds buffer_exit_cpu((unsigned long)hcpu); 34241da177e4SLinus Torvalds return NOTIFY_OK; 34251da177e4SLinus Torvalds } 34261da177e4SLinus Torvalds 3427389d1b08SAneesh Kumar K.V /** 3428a6b91919SRandy Dunlap * bh_uptodate_or_lock - Test whether the buffer is uptodate 3429389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3430389d1b08SAneesh Kumar K.V * 3431389d1b08SAneesh Kumar K.V * Return true if the buffer is up-to-date and false, 3432389d1b08SAneesh Kumar K.V * with the buffer locked, if not. 3433389d1b08SAneesh Kumar K.V */ 3434389d1b08SAneesh Kumar K.V int bh_uptodate_or_lock(struct buffer_head *bh) 3435389d1b08SAneesh Kumar K.V { 3436389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) { 3437389d1b08SAneesh Kumar K.V lock_buffer(bh); 3438389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) 3439389d1b08SAneesh Kumar K.V return 0; 3440389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3441389d1b08SAneesh Kumar K.V } 3442389d1b08SAneesh Kumar K.V return 1; 3443389d1b08SAneesh Kumar K.V } 3444389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_uptodate_or_lock); 3445389d1b08SAneesh Kumar K.V 3446389d1b08SAneesh Kumar K.V /** 3447a6b91919SRandy Dunlap * bh_submit_read - Submit a locked buffer for reading 3448389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3449389d1b08SAneesh Kumar K.V * 3450389d1b08SAneesh Kumar K.V * Returns zero on success and -EIO on error. 3451389d1b08SAneesh Kumar K.V */ 3452389d1b08SAneesh Kumar K.V int bh_submit_read(struct buffer_head *bh) 3453389d1b08SAneesh Kumar K.V { 3454389d1b08SAneesh Kumar K.V BUG_ON(!buffer_locked(bh)); 3455389d1b08SAneesh Kumar K.V 3456389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) { 3457389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3458389d1b08SAneesh Kumar K.V return 0; 3459389d1b08SAneesh Kumar K.V } 3460389d1b08SAneesh Kumar K.V 3461389d1b08SAneesh Kumar K.V get_bh(bh); 3462389d1b08SAneesh Kumar K.V bh->b_end_io = end_buffer_read_sync; 34632a222ca9SMike Christie submit_bh(REQ_OP_READ, 0, bh); 3464389d1b08SAneesh Kumar K.V wait_on_buffer(bh); 3465389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) 3466389d1b08SAneesh Kumar K.V return 0; 3467389d1b08SAneesh Kumar K.V return -EIO; 3468389d1b08SAneesh Kumar K.V } 3469389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_submit_read); 3470389d1b08SAneesh Kumar K.V 34711da177e4SLinus Torvalds void __init buffer_init(void) 34721da177e4SLinus Torvalds { 347343be594aSZhang Yanfei unsigned long nrpages; 34741da177e4SLinus Torvalds 3475b98938c3SChristoph Lameter bh_cachep = kmem_cache_create("buffer_head", 3476b98938c3SChristoph Lameter sizeof(struct buffer_head), 0, 3477b98938c3SChristoph Lameter (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| 3478b98938c3SChristoph Lameter SLAB_MEM_SPREAD), 3479019b4d12SRichard Kennedy NULL); 34801da177e4SLinus Torvalds 34811da177e4SLinus Torvalds /* 34821da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 34831da177e4SLinus Torvalds */ 34841da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 34851da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 34861da177e4SLinus Torvalds hotcpu_notifier(buffer_cpu_notify, 0); 34871da177e4SLinus Torvalds } 3488