11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/buffer.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992, 2002 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95 91da177e4SLinus Torvalds * 101da177e4SLinus Torvalds * Removed a lot of unnecessary code and simplified things now that 111da177e4SLinus Torvalds * the buffer cache isn't our primary cache - Andrew Tridgell 12/96 121da177e4SLinus Torvalds * 131da177e4SLinus Torvalds * Speed up hash, lru, and free list operations. Use gfp() for allocating 141da177e4SLinus Torvalds * hash table, use SLAB cache for buffer heads. SMP threading. -DaveM 151da177e4SLinus Torvalds * 161da177e4SLinus Torvalds * Added 32k buffer block sizes - these are required older ARM systems. - RMK 171da177e4SLinus Torvalds * 181da177e4SLinus Torvalds * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de> 191da177e4SLinus Torvalds */ 201da177e4SLinus Torvalds 211da177e4SLinus Torvalds #include <linux/kernel.h> 221da177e4SLinus Torvalds #include <linux/syscalls.h> 231da177e4SLinus Torvalds #include <linux/fs.h> 241da177e4SLinus Torvalds #include <linux/mm.h> 251da177e4SLinus Torvalds #include <linux/percpu.h> 261da177e4SLinus Torvalds #include <linux/slab.h> 2716f7e0feSRandy Dunlap #include <linux/capability.h> 281da177e4SLinus Torvalds #include <linux/blkdev.h> 291da177e4SLinus Torvalds #include <linux/file.h> 301da177e4SLinus Torvalds #include <linux/quotaops.h> 311da177e4SLinus Torvalds #include <linux/highmem.h> 32630d9c47SPaul Gortmaker #include <linux/export.h> 331da177e4SLinus Torvalds #include <linux/writeback.h> 341da177e4SLinus Torvalds #include <linux/hash.h> 351da177e4SLinus Torvalds #include <linux/suspend.h> 361da177e4SLinus Torvalds #include <linux/buffer_head.h> 3755e829afSAndrew Morton #include <linux/task_io_accounting_ops.h> 381da177e4SLinus Torvalds #include <linux/bio.h> 391da177e4SLinus Torvalds #include <linux/notifier.h> 401da177e4SLinus Torvalds #include <linux/cpu.h> 411da177e4SLinus Torvalds #include <linux/bitops.h> 421da177e4SLinus Torvalds #include <linux/mpage.h> 43fb1c8f93SIngo Molnar #include <linux/bit_spinlock.h> 445305cb83STejun Heo #include <trace/events/block.h> 451da177e4SLinus Torvalds 461da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); 471da177e4SLinus Torvalds 481da177e4SLinus Torvalds #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) 491da177e4SLinus Torvalds 50a3f3c29cSYan Hong void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) 511da177e4SLinus Torvalds { 521da177e4SLinus Torvalds bh->b_end_io = handler; 531da177e4SLinus Torvalds bh->b_private = private; 541da177e4SLinus Torvalds } 551fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(init_buffer); 561da177e4SLinus Torvalds 57f0059afdSTejun Heo inline void touch_buffer(struct buffer_head *bh) 58f0059afdSTejun Heo { 595305cb83STejun Heo trace_block_touch_buffer(bh); 60f0059afdSTejun Heo mark_page_accessed(bh->b_page); 61f0059afdSTejun Heo } 62f0059afdSTejun Heo EXPORT_SYMBOL(touch_buffer); 63f0059afdSTejun Heo 64fc9b52cdSHarvey Harrison void __lock_buffer(struct buffer_head *bh) 651da177e4SLinus Torvalds { 66*74316201SNeilBrown wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 671da177e4SLinus Torvalds } 681da177e4SLinus Torvalds EXPORT_SYMBOL(__lock_buffer); 691da177e4SLinus Torvalds 70fc9b52cdSHarvey Harrison void unlock_buffer(struct buffer_head *bh) 711da177e4SLinus Torvalds { 7251b07fc3SNick Piggin clear_bit_unlock(BH_Lock, &bh->b_state); 734e857c58SPeter Zijlstra smp_mb__after_atomic(); 741da177e4SLinus Torvalds wake_up_bit(&bh->b_state, BH_Lock); 751da177e4SLinus Torvalds } 761fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(unlock_buffer); 771da177e4SLinus Torvalds 781da177e4SLinus Torvalds /* 79b4597226SMel Gorman * Returns if the page has dirty or writeback buffers. If all the buffers 80b4597226SMel Gorman * are unlocked and clean then the PageDirty information is stale. If 81b4597226SMel Gorman * any of the pages are locked, it is assumed they are locked for IO. 82b4597226SMel Gorman */ 83b4597226SMel Gorman void buffer_check_dirty_writeback(struct page *page, 84b4597226SMel Gorman bool *dirty, bool *writeback) 85b4597226SMel Gorman { 86b4597226SMel Gorman struct buffer_head *head, *bh; 87b4597226SMel Gorman *dirty = false; 88b4597226SMel Gorman *writeback = false; 89b4597226SMel Gorman 90b4597226SMel Gorman BUG_ON(!PageLocked(page)); 91b4597226SMel Gorman 92b4597226SMel Gorman if (!page_has_buffers(page)) 93b4597226SMel Gorman return; 94b4597226SMel Gorman 95b4597226SMel Gorman if (PageWriteback(page)) 96b4597226SMel Gorman *writeback = true; 97b4597226SMel Gorman 98b4597226SMel Gorman head = page_buffers(page); 99b4597226SMel Gorman bh = head; 100b4597226SMel Gorman do { 101b4597226SMel Gorman if (buffer_locked(bh)) 102b4597226SMel Gorman *writeback = true; 103b4597226SMel Gorman 104b4597226SMel Gorman if (buffer_dirty(bh)) 105b4597226SMel Gorman *dirty = true; 106b4597226SMel Gorman 107b4597226SMel Gorman bh = bh->b_this_page; 108b4597226SMel Gorman } while (bh != head); 109b4597226SMel Gorman } 110b4597226SMel Gorman EXPORT_SYMBOL(buffer_check_dirty_writeback); 111b4597226SMel Gorman 112b4597226SMel Gorman /* 1131da177e4SLinus Torvalds * Block until a buffer comes unlocked. This doesn't stop it 1141da177e4SLinus Torvalds * from becoming locked again - you have to lock it yourself 1151da177e4SLinus Torvalds * if you want to preserve its state. 1161da177e4SLinus Torvalds */ 1171da177e4SLinus Torvalds void __wait_on_buffer(struct buffer_head * bh) 1181da177e4SLinus Torvalds { 119*74316201SNeilBrown wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); 1201da177e4SLinus Torvalds } 1211fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__wait_on_buffer); 1221da177e4SLinus Torvalds 1231da177e4SLinus Torvalds static void 1241da177e4SLinus Torvalds __clear_page_buffers(struct page *page) 1251da177e4SLinus Torvalds { 1261da177e4SLinus Torvalds ClearPagePrivate(page); 1274c21e2f2SHugh Dickins set_page_private(page, 0); 1281da177e4SLinus Torvalds page_cache_release(page); 1291da177e4SLinus Torvalds } 1301da177e4SLinus Torvalds 13108bafc03SKeith Mannthey 13208bafc03SKeith Mannthey static int quiet_error(struct buffer_head *bh) 13308bafc03SKeith Mannthey { 13408bafc03SKeith Mannthey if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit()) 13508bafc03SKeith Mannthey return 0; 13608bafc03SKeith Mannthey return 1; 13708bafc03SKeith Mannthey } 13808bafc03SKeith Mannthey 13908bafc03SKeith Mannthey 1401da177e4SLinus Torvalds static void buffer_io_error(struct buffer_head *bh) 1411da177e4SLinus Torvalds { 1421da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 1431da177e4SLinus Torvalds printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", 1441da177e4SLinus Torvalds bdevname(bh->b_bdev, b), 1451da177e4SLinus Torvalds (unsigned long long)bh->b_blocknr); 1461da177e4SLinus Torvalds } 1471da177e4SLinus Torvalds 1481da177e4SLinus Torvalds /* 14968671f35SDmitry Monakhov * End-of-IO handler helper function which does not touch the bh after 15068671f35SDmitry Monakhov * unlocking it. 15168671f35SDmitry Monakhov * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but 15268671f35SDmitry Monakhov * a race there is benign: unlock_buffer() only use the bh's address for 15368671f35SDmitry Monakhov * hashing after unlocking the buffer, so it doesn't actually touch the bh 15468671f35SDmitry Monakhov * itself. 1551da177e4SLinus Torvalds */ 15668671f35SDmitry Monakhov static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) 1571da177e4SLinus Torvalds { 1581da177e4SLinus Torvalds if (uptodate) { 1591da177e4SLinus Torvalds set_buffer_uptodate(bh); 1601da177e4SLinus Torvalds } else { 1611da177e4SLinus Torvalds /* This happens, due to failed READA attempts. */ 1621da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1631da177e4SLinus Torvalds } 1641da177e4SLinus Torvalds unlock_buffer(bh); 16568671f35SDmitry Monakhov } 16668671f35SDmitry Monakhov 16768671f35SDmitry Monakhov /* 16868671f35SDmitry Monakhov * Default synchronous end-of-IO handler.. Just mark it up-to-date and 16968671f35SDmitry Monakhov * unlock the buffer. This is what ll_rw_block uses too. 17068671f35SDmitry Monakhov */ 17168671f35SDmitry Monakhov void end_buffer_read_sync(struct buffer_head *bh, int uptodate) 17268671f35SDmitry Monakhov { 17368671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 1741da177e4SLinus Torvalds put_bh(bh); 1751da177e4SLinus Torvalds } 1761fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_read_sync); 1771da177e4SLinus Torvalds 1781da177e4SLinus Torvalds void end_buffer_write_sync(struct buffer_head *bh, int uptodate) 1791da177e4SLinus Torvalds { 1801da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 1811da177e4SLinus Torvalds 1821da177e4SLinus Torvalds if (uptodate) { 1831da177e4SLinus Torvalds set_buffer_uptodate(bh); 1841da177e4SLinus Torvalds } else { 1850edd55faSChristoph Hellwig if (!quiet_error(bh)) { 1861da177e4SLinus Torvalds buffer_io_error(bh); 1871da177e4SLinus Torvalds printk(KERN_WARNING "lost page write due to " 1881da177e4SLinus Torvalds "I/O error on %s\n", 1891da177e4SLinus Torvalds bdevname(bh->b_bdev, b)); 1901da177e4SLinus Torvalds } 1911da177e4SLinus Torvalds set_buffer_write_io_error(bh); 1921da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1931da177e4SLinus Torvalds } 1941da177e4SLinus Torvalds unlock_buffer(bh); 1951da177e4SLinus Torvalds put_bh(bh); 1961da177e4SLinus Torvalds } 1971fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_write_sync); 1981da177e4SLinus Torvalds 1991da177e4SLinus Torvalds /* 2001da177e4SLinus Torvalds * Various filesystems appear to want __find_get_block to be non-blocking. 2011da177e4SLinus Torvalds * But it's the page lock which protects the buffers. To get around this, 2021da177e4SLinus Torvalds * we get exclusion from try_to_free_buffers with the blockdev mapping's 2031da177e4SLinus Torvalds * private_lock. 2041da177e4SLinus Torvalds * 2051da177e4SLinus Torvalds * Hack idea: for the blockdev mapping, i_bufferlist_lock contention 2061da177e4SLinus Torvalds * may be quite high. This code could TryLock the page, and if that 2071da177e4SLinus Torvalds * succeeds, there is no need to take private_lock. (But if 2081da177e4SLinus Torvalds * private_lock is contended then so is mapping->tree_lock). 2091da177e4SLinus Torvalds */ 2101da177e4SLinus Torvalds static struct buffer_head * 211385fd4c5SCoywolf Qi Hunt __find_get_block_slow(struct block_device *bdev, sector_t block) 2121da177e4SLinus Torvalds { 2131da177e4SLinus Torvalds struct inode *bd_inode = bdev->bd_inode; 2141da177e4SLinus Torvalds struct address_space *bd_mapping = bd_inode->i_mapping; 2151da177e4SLinus Torvalds struct buffer_head *ret = NULL; 2161da177e4SLinus Torvalds pgoff_t index; 2171da177e4SLinus Torvalds struct buffer_head *bh; 2181da177e4SLinus Torvalds struct buffer_head *head; 2191da177e4SLinus Torvalds struct page *page; 2201da177e4SLinus Torvalds int all_mapped = 1; 2211da177e4SLinus Torvalds 2221da177e4SLinus Torvalds index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); 2232457aec6SMel Gorman page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED); 2241da177e4SLinus Torvalds if (!page) 2251da177e4SLinus Torvalds goto out; 2261da177e4SLinus Torvalds 2271da177e4SLinus Torvalds spin_lock(&bd_mapping->private_lock); 2281da177e4SLinus Torvalds if (!page_has_buffers(page)) 2291da177e4SLinus Torvalds goto out_unlock; 2301da177e4SLinus Torvalds head = page_buffers(page); 2311da177e4SLinus Torvalds bh = head; 2321da177e4SLinus Torvalds do { 23397f76d3dSNikanth Karthikesan if (!buffer_mapped(bh)) 23497f76d3dSNikanth Karthikesan all_mapped = 0; 23597f76d3dSNikanth Karthikesan else if (bh->b_blocknr == block) { 2361da177e4SLinus Torvalds ret = bh; 2371da177e4SLinus Torvalds get_bh(bh); 2381da177e4SLinus Torvalds goto out_unlock; 2391da177e4SLinus Torvalds } 2401da177e4SLinus Torvalds bh = bh->b_this_page; 2411da177e4SLinus Torvalds } while (bh != head); 2421da177e4SLinus Torvalds 2431da177e4SLinus Torvalds /* we might be here because some of the buffers on this page are 2441da177e4SLinus Torvalds * not mapped. This is due to various races between 2451da177e4SLinus Torvalds * file io on the block device and getblk. It gets dealt with 2461da177e4SLinus Torvalds * elsewhere, don't buffer_error if we had some unmapped buffers 2471da177e4SLinus Torvalds */ 2481da177e4SLinus Torvalds if (all_mapped) { 24972a2ebd8STao Ma char b[BDEVNAME_SIZE]; 25072a2ebd8STao Ma 2511da177e4SLinus Torvalds printk("__find_get_block_slow() failed. " 2521da177e4SLinus Torvalds "block=%llu, b_blocknr=%llu\n", 253205f87f6SBadari Pulavarty (unsigned long long)block, 254205f87f6SBadari Pulavarty (unsigned long long)bh->b_blocknr); 255205f87f6SBadari Pulavarty printk("b_state=0x%08lx, b_size=%zu\n", 256205f87f6SBadari Pulavarty bh->b_state, bh->b_size); 25772a2ebd8STao Ma printk("device %s blocksize: %d\n", bdevname(bdev, b), 25872a2ebd8STao Ma 1 << bd_inode->i_blkbits); 2591da177e4SLinus Torvalds } 2601da177e4SLinus Torvalds out_unlock: 2611da177e4SLinus Torvalds spin_unlock(&bd_mapping->private_lock); 2621da177e4SLinus Torvalds page_cache_release(page); 2631da177e4SLinus Torvalds out: 2641da177e4SLinus Torvalds return ret; 2651da177e4SLinus Torvalds } 2661da177e4SLinus Torvalds 2671da177e4SLinus Torvalds /* 2685b0830cbSJens Axboe * Kick the writeback threads then try to free up some ZONE_NORMAL memory. 2691da177e4SLinus Torvalds */ 2701da177e4SLinus Torvalds static void free_more_memory(void) 2711da177e4SLinus Torvalds { 27219770b32SMel Gorman struct zone *zone; 2730e88460dSMel Gorman int nid; 2741da177e4SLinus Torvalds 2750e175a18SCurt Wohlgemuth wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM); 2761da177e4SLinus Torvalds yield(); 2771da177e4SLinus Torvalds 2780e88460dSMel Gorman for_each_online_node(nid) { 27919770b32SMel Gorman (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS), 28019770b32SMel Gorman gfp_zone(GFP_NOFS), NULL, 28119770b32SMel Gorman &zone); 28219770b32SMel Gorman if (zone) 28354a6eb5cSMel Gorman try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0, 284327c0e96SKAMEZAWA Hiroyuki GFP_NOFS, NULL); 2851da177e4SLinus Torvalds } 2861da177e4SLinus Torvalds } 2871da177e4SLinus Torvalds 2881da177e4SLinus Torvalds /* 2891da177e4SLinus Torvalds * I/O completion handler for block_read_full_page() - pages 2901da177e4SLinus Torvalds * which come unlocked at the end of I/O. 2911da177e4SLinus Torvalds */ 2921da177e4SLinus Torvalds static void end_buffer_async_read(struct buffer_head *bh, int uptodate) 2931da177e4SLinus Torvalds { 2941da177e4SLinus Torvalds unsigned long flags; 295a3972203SNick Piggin struct buffer_head *first; 2961da177e4SLinus Torvalds struct buffer_head *tmp; 2971da177e4SLinus Torvalds struct page *page; 2981da177e4SLinus Torvalds int page_uptodate = 1; 2991da177e4SLinus Torvalds 3001da177e4SLinus Torvalds BUG_ON(!buffer_async_read(bh)); 3011da177e4SLinus Torvalds 3021da177e4SLinus Torvalds page = bh->b_page; 3031da177e4SLinus Torvalds if (uptodate) { 3041da177e4SLinus Torvalds set_buffer_uptodate(bh); 3051da177e4SLinus Torvalds } else { 3061da177e4SLinus Torvalds clear_buffer_uptodate(bh); 30708bafc03SKeith Mannthey if (!quiet_error(bh)) 3081da177e4SLinus Torvalds buffer_io_error(bh); 3091da177e4SLinus Torvalds SetPageError(page); 3101da177e4SLinus Torvalds } 3111da177e4SLinus Torvalds 3121da177e4SLinus Torvalds /* 3131da177e4SLinus Torvalds * Be _very_ careful from here on. Bad things can happen if 3141da177e4SLinus Torvalds * two buffer heads end IO at almost the same time and both 3151da177e4SLinus Torvalds * decide that the page is now completely done. 3161da177e4SLinus Torvalds */ 317a3972203SNick Piggin first = page_buffers(page); 318a3972203SNick Piggin local_irq_save(flags); 319a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 3201da177e4SLinus Torvalds clear_buffer_async_read(bh); 3211da177e4SLinus Torvalds unlock_buffer(bh); 3221da177e4SLinus Torvalds tmp = bh; 3231da177e4SLinus Torvalds do { 3241da177e4SLinus Torvalds if (!buffer_uptodate(tmp)) 3251da177e4SLinus Torvalds page_uptodate = 0; 3261da177e4SLinus Torvalds if (buffer_async_read(tmp)) { 3271da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3281da177e4SLinus Torvalds goto still_busy; 3291da177e4SLinus Torvalds } 3301da177e4SLinus Torvalds tmp = tmp->b_this_page; 3311da177e4SLinus Torvalds } while (tmp != bh); 332a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 333a3972203SNick Piggin local_irq_restore(flags); 3341da177e4SLinus Torvalds 3351da177e4SLinus Torvalds /* 3361da177e4SLinus Torvalds * If none of the buffers had errors and they are all 3371da177e4SLinus Torvalds * uptodate then we can set the page uptodate. 3381da177e4SLinus Torvalds */ 3391da177e4SLinus Torvalds if (page_uptodate && !PageError(page)) 3401da177e4SLinus Torvalds SetPageUptodate(page); 3411da177e4SLinus Torvalds unlock_page(page); 3421da177e4SLinus Torvalds return; 3431da177e4SLinus Torvalds 3441da177e4SLinus Torvalds still_busy: 345a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 346a3972203SNick Piggin local_irq_restore(flags); 3471da177e4SLinus Torvalds return; 3481da177e4SLinus Torvalds } 3491da177e4SLinus Torvalds 3501da177e4SLinus Torvalds /* 3511da177e4SLinus Torvalds * Completion handler for block_write_full_page() - pages which are unlocked 3521da177e4SLinus Torvalds * during I/O, and which have PageWriteback cleared upon I/O completion. 3531da177e4SLinus Torvalds */ 35435c80d5fSChris Mason void end_buffer_async_write(struct buffer_head *bh, int uptodate) 3551da177e4SLinus Torvalds { 3561da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 3571da177e4SLinus Torvalds unsigned long flags; 358a3972203SNick Piggin struct buffer_head *first; 3591da177e4SLinus Torvalds struct buffer_head *tmp; 3601da177e4SLinus Torvalds struct page *page; 3611da177e4SLinus Torvalds 3621da177e4SLinus Torvalds BUG_ON(!buffer_async_write(bh)); 3631da177e4SLinus Torvalds 3641da177e4SLinus Torvalds page = bh->b_page; 3651da177e4SLinus Torvalds if (uptodate) { 3661da177e4SLinus Torvalds set_buffer_uptodate(bh); 3671da177e4SLinus Torvalds } else { 36808bafc03SKeith Mannthey if (!quiet_error(bh)) { 3691da177e4SLinus Torvalds buffer_io_error(bh); 3701da177e4SLinus Torvalds printk(KERN_WARNING "lost page write due to " 3711da177e4SLinus Torvalds "I/O error on %s\n", 3721da177e4SLinus Torvalds bdevname(bh->b_bdev, b)); 3731da177e4SLinus Torvalds } 3741da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 37558ff407bSJan Kara set_buffer_write_io_error(bh); 3761da177e4SLinus Torvalds clear_buffer_uptodate(bh); 3771da177e4SLinus Torvalds SetPageError(page); 3781da177e4SLinus Torvalds } 3791da177e4SLinus Torvalds 380a3972203SNick Piggin first = page_buffers(page); 381a3972203SNick Piggin local_irq_save(flags); 382a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 383a3972203SNick Piggin 3841da177e4SLinus Torvalds clear_buffer_async_write(bh); 3851da177e4SLinus Torvalds unlock_buffer(bh); 3861da177e4SLinus Torvalds tmp = bh->b_this_page; 3871da177e4SLinus Torvalds while (tmp != bh) { 3881da177e4SLinus Torvalds if (buffer_async_write(tmp)) { 3891da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 3901da177e4SLinus Torvalds goto still_busy; 3911da177e4SLinus Torvalds } 3921da177e4SLinus Torvalds tmp = tmp->b_this_page; 3931da177e4SLinus Torvalds } 394a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 395a3972203SNick Piggin local_irq_restore(flags); 3961da177e4SLinus Torvalds end_page_writeback(page); 3971da177e4SLinus Torvalds return; 3981da177e4SLinus Torvalds 3991da177e4SLinus Torvalds still_busy: 400a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 401a3972203SNick Piggin local_irq_restore(flags); 4021da177e4SLinus Torvalds return; 4031da177e4SLinus Torvalds } 4041fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(end_buffer_async_write); 4051da177e4SLinus Torvalds 4061da177e4SLinus Torvalds /* 4071da177e4SLinus Torvalds * If a page's buffers are under async readin (end_buffer_async_read 4081da177e4SLinus Torvalds * completion) then there is a possibility that another thread of 4091da177e4SLinus Torvalds * control could lock one of the buffers after it has completed 4101da177e4SLinus Torvalds * but while some of the other buffers have not completed. This 4111da177e4SLinus Torvalds * locked buffer would confuse end_buffer_async_read() into not unlocking 4121da177e4SLinus Torvalds * the page. So the absence of BH_Async_Read tells end_buffer_async_read() 4131da177e4SLinus Torvalds * that this buffer is not under async I/O. 4141da177e4SLinus Torvalds * 4151da177e4SLinus Torvalds * The page comes unlocked when it has no locked buffer_async buffers 4161da177e4SLinus Torvalds * left. 4171da177e4SLinus Torvalds * 4181da177e4SLinus Torvalds * PageLocked prevents anyone starting new async I/O reads any of 4191da177e4SLinus Torvalds * the buffers. 4201da177e4SLinus Torvalds * 4211da177e4SLinus Torvalds * PageWriteback is used to prevent simultaneous writeout of the same 4221da177e4SLinus Torvalds * page. 4231da177e4SLinus Torvalds * 4241da177e4SLinus Torvalds * PageLocked prevents anyone from starting writeback of a page which is 4251da177e4SLinus Torvalds * under read I/O (PageWriteback is only ever set against a locked page). 4261da177e4SLinus Torvalds */ 4271da177e4SLinus Torvalds static void mark_buffer_async_read(struct buffer_head *bh) 4281da177e4SLinus Torvalds { 4291da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_read; 4301da177e4SLinus Torvalds set_buffer_async_read(bh); 4311da177e4SLinus Torvalds } 4321da177e4SLinus Torvalds 4331fe72eaaSH Hartley Sweeten static void mark_buffer_async_write_endio(struct buffer_head *bh, 43435c80d5fSChris Mason bh_end_io_t *handler) 43535c80d5fSChris Mason { 43635c80d5fSChris Mason bh->b_end_io = handler; 43735c80d5fSChris Mason set_buffer_async_write(bh); 43835c80d5fSChris Mason } 43935c80d5fSChris Mason 4401da177e4SLinus Torvalds void mark_buffer_async_write(struct buffer_head *bh) 4411da177e4SLinus Torvalds { 44235c80d5fSChris Mason mark_buffer_async_write_endio(bh, end_buffer_async_write); 4431da177e4SLinus Torvalds } 4441da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_async_write); 4451da177e4SLinus Torvalds 4461da177e4SLinus Torvalds 4471da177e4SLinus Torvalds /* 4481da177e4SLinus Torvalds * fs/buffer.c contains helper functions for buffer-backed address space's 4491da177e4SLinus Torvalds * fsync functions. A common requirement for buffer-based filesystems is 4501da177e4SLinus Torvalds * that certain data from the backing blockdev needs to be written out for 4511da177e4SLinus Torvalds * a successful fsync(). For example, ext2 indirect blocks need to be 4521da177e4SLinus Torvalds * written back and waited upon before fsync() returns. 4531da177e4SLinus Torvalds * 4541da177e4SLinus Torvalds * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), 4551da177e4SLinus Torvalds * inode_has_buffers() and invalidate_inode_buffers() are provided for the 4561da177e4SLinus Torvalds * management of a list of dependent buffers at ->i_mapping->private_list. 4571da177e4SLinus Torvalds * 4581da177e4SLinus Torvalds * Locking is a little subtle: try_to_free_buffers() will remove buffers 4591da177e4SLinus Torvalds * from their controlling inode's queue when they are being freed. But 4601da177e4SLinus Torvalds * try_to_free_buffers() will be operating against the *blockdev* mapping 4611da177e4SLinus Torvalds * at the time, not against the S_ISREG file which depends on those buffers. 4621da177e4SLinus Torvalds * So the locking for private_list is via the private_lock in the address_space 4631da177e4SLinus Torvalds * which backs the buffers. Which is different from the address_space 4641da177e4SLinus Torvalds * against which the buffers are listed. So for a particular address_space, 4651da177e4SLinus Torvalds * mapping->private_lock does *not* protect mapping->private_list! In fact, 4661da177e4SLinus Torvalds * mapping->private_list will always be protected by the backing blockdev's 4671da177e4SLinus Torvalds * ->private_lock. 4681da177e4SLinus Torvalds * 4691da177e4SLinus Torvalds * Which introduces a requirement: all buffers on an address_space's 4701da177e4SLinus Torvalds * ->private_list must be from the same address_space: the blockdev's. 4711da177e4SLinus Torvalds * 4721da177e4SLinus Torvalds * address_spaces which do not place buffers at ->private_list via these 4731da177e4SLinus Torvalds * utility functions are free to use private_lock and private_list for 4741da177e4SLinus Torvalds * whatever they want. The only requirement is that list_empty(private_list) 4751da177e4SLinus Torvalds * be true at clear_inode() time. 4761da177e4SLinus Torvalds * 4771da177e4SLinus Torvalds * FIXME: clear_inode should not call invalidate_inode_buffers(). The 4781da177e4SLinus Torvalds * filesystems should do that. invalidate_inode_buffers() should just go 4791da177e4SLinus Torvalds * BUG_ON(!list_empty). 4801da177e4SLinus Torvalds * 4811da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should 4821da177e4SLinus Torvalds * take an address_space, not an inode. And it should be called 4831da177e4SLinus Torvalds * mark_buffer_dirty_fsync() to clearly define why those buffers are being 4841da177e4SLinus Torvalds * queued up. 4851da177e4SLinus Torvalds * 4861da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the 4871da177e4SLinus Torvalds * list if it is already on a list. Because if the buffer is on a list, 4881da177e4SLinus Torvalds * it *must* already be on the right one. If not, the filesystem is being 4891da177e4SLinus Torvalds * silly. This will save a ton of locking. But first we have to ensure 4901da177e4SLinus Torvalds * that buffers are taken *off* the old inode's list when they are freed 4911da177e4SLinus Torvalds * (presumably in truncate). That requires careful auditing of all 4921da177e4SLinus Torvalds * filesystems (do it inside bforget()). It could also be done by bringing 4931da177e4SLinus Torvalds * b_inode back. 4941da177e4SLinus Torvalds */ 4951da177e4SLinus Torvalds 4961da177e4SLinus Torvalds /* 4971da177e4SLinus Torvalds * The buffer's backing address_space's private_lock must be held 4981da177e4SLinus Torvalds */ 499dbacefc9SThomas Petazzoni static void __remove_assoc_queue(struct buffer_head *bh) 5001da177e4SLinus Torvalds { 5011da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 50258ff407bSJan Kara WARN_ON(!bh->b_assoc_map); 50358ff407bSJan Kara if (buffer_write_io_error(bh)) 50458ff407bSJan Kara set_bit(AS_EIO, &bh->b_assoc_map->flags); 50558ff407bSJan Kara bh->b_assoc_map = NULL; 5061da177e4SLinus Torvalds } 5071da177e4SLinus Torvalds 5081da177e4SLinus Torvalds int inode_has_buffers(struct inode *inode) 5091da177e4SLinus Torvalds { 5101da177e4SLinus Torvalds return !list_empty(&inode->i_data.private_list); 5111da177e4SLinus Torvalds } 5121da177e4SLinus Torvalds 5131da177e4SLinus Torvalds /* 5141da177e4SLinus Torvalds * osync is designed to support O_SYNC io. It waits synchronously for 5151da177e4SLinus Torvalds * all already-submitted IO to complete, but does not queue any new 5161da177e4SLinus Torvalds * writes to the disk. 5171da177e4SLinus Torvalds * 5181da177e4SLinus Torvalds * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as 5191da177e4SLinus Torvalds * you dirty the buffers, and then use osync_inode_buffers to wait for 5201da177e4SLinus Torvalds * completion. Any other dirty buffers which are not yet queued for 5211da177e4SLinus Torvalds * write will not be flushed to disk by the osync. 5221da177e4SLinus Torvalds */ 5231da177e4SLinus Torvalds static int osync_buffers_list(spinlock_t *lock, struct list_head *list) 5241da177e4SLinus Torvalds { 5251da177e4SLinus Torvalds struct buffer_head *bh; 5261da177e4SLinus Torvalds struct list_head *p; 5271da177e4SLinus Torvalds int err = 0; 5281da177e4SLinus Torvalds 5291da177e4SLinus Torvalds spin_lock(lock); 5301da177e4SLinus Torvalds repeat: 5311da177e4SLinus Torvalds list_for_each_prev(p, list) { 5321da177e4SLinus Torvalds bh = BH_ENTRY(p); 5331da177e4SLinus Torvalds if (buffer_locked(bh)) { 5341da177e4SLinus Torvalds get_bh(bh); 5351da177e4SLinus Torvalds spin_unlock(lock); 5361da177e4SLinus Torvalds wait_on_buffer(bh); 5371da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 5381da177e4SLinus Torvalds err = -EIO; 5391da177e4SLinus Torvalds brelse(bh); 5401da177e4SLinus Torvalds spin_lock(lock); 5411da177e4SLinus Torvalds goto repeat; 5421da177e4SLinus Torvalds } 5431da177e4SLinus Torvalds } 5441da177e4SLinus Torvalds spin_unlock(lock); 5451da177e4SLinus Torvalds return err; 5461da177e4SLinus Torvalds } 5471da177e4SLinus Torvalds 54801a05b33SAl Viro static void do_thaw_one(struct super_block *sb, void *unused) 549c2d75438SEric Sandeen { 550c2d75438SEric Sandeen char b[BDEVNAME_SIZE]; 551c2d75438SEric Sandeen while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) 552c2d75438SEric Sandeen printk(KERN_WARNING "Emergency Thaw on %s\n", 553c2d75438SEric Sandeen bdevname(sb->s_bdev, b)); 554c2d75438SEric Sandeen } 55501a05b33SAl Viro 55601a05b33SAl Viro static void do_thaw_all(struct work_struct *work) 55701a05b33SAl Viro { 55801a05b33SAl Viro iterate_supers(do_thaw_one, NULL); 559053c525fSJens Axboe kfree(work); 560c2d75438SEric Sandeen printk(KERN_WARNING "Emergency Thaw complete\n"); 561c2d75438SEric Sandeen } 562c2d75438SEric Sandeen 563c2d75438SEric Sandeen /** 564c2d75438SEric Sandeen * emergency_thaw_all -- forcibly thaw every frozen filesystem 565c2d75438SEric Sandeen * 566c2d75438SEric Sandeen * Used for emergency unfreeze of all filesystems via SysRq 567c2d75438SEric Sandeen */ 568c2d75438SEric Sandeen void emergency_thaw_all(void) 569c2d75438SEric Sandeen { 570053c525fSJens Axboe struct work_struct *work; 571053c525fSJens Axboe 572053c525fSJens Axboe work = kmalloc(sizeof(*work), GFP_ATOMIC); 573053c525fSJens Axboe if (work) { 574053c525fSJens Axboe INIT_WORK(work, do_thaw_all); 575053c525fSJens Axboe schedule_work(work); 576053c525fSJens Axboe } 577c2d75438SEric Sandeen } 578c2d75438SEric Sandeen 5791da177e4SLinus Torvalds /** 58078a4a50aSRandy Dunlap * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers 58167be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 5821da177e4SLinus Torvalds * 5831da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 5841da177e4SLinus Torvalds * that I/O. 5851da177e4SLinus Torvalds * 58667be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 58767be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 58867be2dd1SMartin Waitz * a successful fsync(). 5891da177e4SLinus Torvalds */ 5901da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 5911da177e4SLinus Torvalds { 592252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 5931da177e4SLinus Torvalds 5941da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 5951da177e4SLinus Torvalds return 0; 5961da177e4SLinus Torvalds 5971da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 5981da177e4SLinus Torvalds &mapping->private_list); 5991da177e4SLinus Torvalds } 6001da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 6011da177e4SLinus Torvalds 6021da177e4SLinus Torvalds /* 6031da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 6041da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 6051da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 6061da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 6071da177e4SLinus Torvalds */ 6081da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 6091da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 6101da177e4SLinus Torvalds { 6111da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 6121da177e4SLinus Torvalds if (bh) { 6131da177e4SLinus Torvalds if (buffer_dirty(bh)) 6141da177e4SLinus Torvalds ll_rw_block(WRITE, 1, &bh); 6151da177e4SLinus Torvalds put_bh(bh); 6161da177e4SLinus Torvalds } 6171da177e4SLinus Torvalds } 6181da177e4SLinus Torvalds 6191da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 6201da177e4SLinus Torvalds { 6211da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 6221da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 6231da177e4SLinus Torvalds 6241da177e4SLinus Torvalds mark_buffer_dirty(bh); 625252aa6f5SRafael Aquini if (!mapping->private_data) { 626252aa6f5SRafael Aquini mapping->private_data = buffer_mapping; 6271da177e4SLinus Torvalds } else { 628252aa6f5SRafael Aquini BUG_ON(mapping->private_data != buffer_mapping); 6291da177e4SLinus Torvalds } 630535ee2fbSJan Kara if (!bh->b_assoc_map) { 6311da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 6321da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 6331da177e4SLinus Torvalds &mapping->private_list); 63458ff407bSJan Kara bh->b_assoc_map = mapping; 6351da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 6361da177e4SLinus Torvalds } 6371da177e4SLinus Torvalds } 6381da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 6391da177e4SLinus Torvalds 6401da177e4SLinus Torvalds /* 641787d2214SNick Piggin * Mark the page dirty, and set it dirty in the radix tree, and mark the inode 642787d2214SNick Piggin * dirty. 643787d2214SNick Piggin * 644787d2214SNick Piggin * If warn is true, then emit a warning if the page is not uptodate and has 645787d2214SNick Piggin * not been truncated. 646787d2214SNick Piggin */ 647a8e7d49aSLinus Torvalds static void __set_page_dirty(struct page *page, 648787d2214SNick Piggin struct address_space *mapping, int warn) 649787d2214SNick Piggin { 650227d53b3SKOSAKI Motohiro unsigned long flags; 651227d53b3SKOSAKI Motohiro 652227d53b3SKOSAKI Motohiro spin_lock_irqsave(&mapping->tree_lock, flags); 653787d2214SNick Piggin if (page->mapping) { /* Race with truncate? */ 654787d2214SNick Piggin WARN_ON_ONCE(warn && !PageUptodate(page)); 655e3a7cca1SEdward Shishkin account_page_dirtied(page, mapping); 656787d2214SNick Piggin radix_tree_tag_set(&mapping->page_tree, 657787d2214SNick Piggin page_index(page), PAGECACHE_TAG_DIRTY); 658787d2214SNick Piggin } 659227d53b3SKOSAKI Motohiro spin_unlock_irqrestore(&mapping->tree_lock, flags); 660787d2214SNick Piggin __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 661787d2214SNick Piggin } 662787d2214SNick Piggin 663787d2214SNick Piggin /* 6641da177e4SLinus Torvalds * Add a page to the dirty page list. 6651da177e4SLinus Torvalds * 6661da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 6671da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 6681da177e4SLinus Torvalds * 6691da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 6701da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 6711da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 6721da177e4SLinus Torvalds * dirty. 6731da177e4SLinus Torvalds * 6741da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 6751da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 6761da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 6771da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 6781da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 6791da177e4SLinus Torvalds * page on the dirty page list. 6801da177e4SLinus Torvalds * 6811da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 6821da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 6831da177e4SLinus Torvalds * added to the page after it was set dirty. 6841da177e4SLinus Torvalds * 6851da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 6861da177e4SLinus Torvalds * address_space though. 6871da177e4SLinus Torvalds */ 6881da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 6891da177e4SLinus Torvalds { 690a8e7d49aSLinus Torvalds int newly_dirty; 691787d2214SNick Piggin struct address_space *mapping = page_mapping(page); 692ebf7a227SNick Piggin 693ebf7a227SNick Piggin if (unlikely(!mapping)) 694ebf7a227SNick Piggin return !TestSetPageDirty(page); 6951da177e4SLinus Torvalds 6961da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 6971da177e4SLinus Torvalds if (page_has_buffers(page)) { 6981da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 6991da177e4SLinus Torvalds struct buffer_head *bh = head; 7001da177e4SLinus Torvalds 7011da177e4SLinus Torvalds do { 7021da177e4SLinus Torvalds set_buffer_dirty(bh); 7031da177e4SLinus Torvalds bh = bh->b_this_page; 7041da177e4SLinus Torvalds } while (bh != head); 7051da177e4SLinus Torvalds } 706a8e7d49aSLinus Torvalds newly_dirty = !TestSetPageDirty(page); 7071da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 7081da177e4SLinus Torvalds 709a8e7d49aSLinus Torvalds if (newly_dirty) 710a8e7d49aSLinus Torvalds __set_page_dirty(page, mapping, 1); 711a8e7d49aSLinus Torvalds return newly_dirty; 7121da177e4SLinus Torvalds } 7131da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 7141da177e4SLinus Torvalds 7151da177e4SLinus Torvalds /* 7161da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 7171da177e4SLinus Torvalds * 7181da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 7191da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 7201da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 7211da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 7221da177e4SLinus Torvalds * 7231da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 7241da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 7251da177e4SLinus Torvalds * up, waiting for those writes to complete. 7261da177e4SLinus Torvalds * 7271da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 7281da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 7291da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 7301da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 7311da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 7321da177e4SLinus Torvalds * any newly dirty buffers for write. 7331da177e4SLinus Torvalds */ 7341da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 7351da177e4SLinus Torvalds { 7361da177e4SLinus Torvalds struct buffer_head *bh; 7371da177e4SLinus Torvalds struct list_head tmp; 7387eaceaccSJens Axboe struct address_space *mapping; 7391da177e4SLinus Torvalds int err = 0, err2; 7404ee2491eSJens Axboe struct blk_plug plug; 7411da177e4SLinus Torvalds 7421da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 7434ee2491eSJens Axboe blk_start_plug(&plug); 7441da177e4SLinus Torvalds 7451da177e4SLinus Torvalds spin_lock(lock); 7461da177e4SLinus Torvalds while (!list_empty(list)) { 7471da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 748535ee2fbSJan Kara mapping = bh->b_assoc_map; 74958ff407bSJan Kara __remove_assoc_queue(bh); 750535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 751535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 752535ee2fbSJan Kara smp_mb(); 7531da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 7541da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 755535ee2fbSJan Kara bh->b_assoc_map = mapping; 7561da177e4SLinus Torvalds if (buffer_dirty(bh)) { 7571da177e4SLinus Torvalds get_bh(bh); 7581da177e4SLinus Torvalds spin_unlock(lock); 7591da177e4SLinus Torvalds /* 7601da177e4SLinus Torvalds * Ensure any pending I/O completes so that 7619cb569d6SChristoph Hellwig * write_dirty_buffer() actually writes the 7629cb569d6SChristoph Hellwig * current contents - it is a noop if I/O is 7639cb569d6SChristoph Hellwig * still in flight on potentially older 7649cb569d6SChristoph Hellwig * contents. 7651da177e4SLinus Torvalds */ 766721a9602SJens Axboe write_dirty_buffer(bh, WRITE_SYNC); 7679cf6b720SJens Axboe 7689cf6b720SJens Axboe /* 7699cf6b720SJens Axboe * Kick off IO for the previous mapping. Note 7709cf6b720SJens Axboe * that we will not run the very last mapping, 7719cf6b720SJens Axboe * wait_on_buffer() will do that for us 7729cf6b720SJens Axboe * through sync_buffer(). 7739cf6b720SJens Axboe */ 7741da177e4SLinus Torvalds brelse(bh); 7751da177e4SLinus Torvalds spin_lock(lock); 7761da177e4SLinus Torvalds } 7771da177e4SLinus Torvalds } 7781da177e4SLinus Torvalds } 7791da177e4SLinus Torvalds 7804ee2491eSJens Axboe spin_unlock(lock); 7814ee2491eSJens Axboe blk_finish_plug(&plug); 7824ee2491eSJens Axboe spin_lock(lock); 7834ee2491eSJens Axboe 7841da177e4SLinus Torvalds while (!list_empty(&tmp)) { 7851da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 7861da177e4SLinus Torvalds get_bh(bh); 787535ee2fbSJan Kara mapping = bh->b_assoc_map; 788535ee2fbSJan Kara __remove_assoc_queue(bh); 789535ee2fbSJan Kara /* Avoid race with mark_buffer_dirty_inode() which does 790535ee2fbSJan Kara * a lockless check and we rely on seeing the dirty bit */ 791535ee2fbSJan Kara smp_mb(); 792535ee2fbSJan Kara if (buffer_dirty(bh)) { 793535ee2fbSJan Kara list_add(&bh->b_assoc_buffers, 794e3892296SJan Kara &mapping->private_list); 795535ee2fbSJan Kara bh->b_assoc_map = mapping; 796535ee2fbSJan Kara } 7971da177e4SLinus Torvalds spin_unlock(lock); 7981da177e4SLinus Torvalds wait_on_buffer(bh); 7991da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 8001da177e4SLinus Torvalds err = -EIO; 8011da177e4SLinus Torvalds brelse(bh); 8021da177e4SLinus Torvalds spin_lock(lock); 8031da177e4SLinus Torvalds } 8041da177e4SLinus Torvalds 8051da177e4SLinus Torvalds spin_unlock(lock); 8061da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 8071da177e4SLinus Torvalds if (err) 8081da177e4SLinus Torvalds return err; 8091da177e4SLinus Torvalds else 8101da177e4SLinus Torvalds return err2; 8111da177e4SLinus Torvalds } 8121da177e4SLinus Torvalds 8131da177e4SLinus Torvalds /* 8141da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 8151da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 8161da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 8171da177e4SLinus Torvalds * 8181da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 8191da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 8201da177e4SLinus Torvalds * for reiserfs. 8211da177e4SLinus Torvalds */ 8221da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 8231da177e4SLinus Torvalds { 8241da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8251da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8261da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 827252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 8281da177e4SLinus Torvalds 8291da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8301da177e4SLinus Torvalds while (!list_empty(list)) 8311da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 8321da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8331da177e4SLinus Torvalds } 8341da177e4SLinus Torvalds } 83552b19ac9SJan Kara EXPORT_SYMBOL(invalidate_inode_buffers); 8361da177e4SLinus Torvalds 8371da177e4SLinus Torvalds /* 8381da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 8391da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 8401da177e4SLinus Torvalds * 8411da177e4SLinus Torvalds * Returns true if all buffers were removed. 8421da177e4SLinus Torvalds */ 8431da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 8441da177e4SLinus Torvalds { 8451da177e4SLinus Torvalds int ret = 1; 8461da177e4SLinus Torvalds 8471da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8481da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8491da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 850252aa6f5SRafael Aquini struct address_space *buffer_mapping = mapping->private_data; 8511da177e4SLinus Torvalds 8521da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8531da177e4SLinus Torvalds while (!list_empty(list)) { 8541da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 8551da177e4SLinus Torvalds if (buffer_dirty(bh)) { 8561da177e4SLinus Torvalds ret = 0; 8571da177e4SLinus Torvalds break; 8581da177e4SLinus Torvalds } 8591da177e4SLinus Torvalds __remove_assoc_queue(bh); 8601da177e4SLinus Torvalds } 8611da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8621da177e4SLinus Torvalds } 8631da177e4SLinus Torvalds return ret; 8641da177e4SLinus Torvalds } 8651da177e4SLinus Torvalds 8661da177e4SLinus Torvalds /* 8671da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 8681da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 8691da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 8701da177e4SLinus Torvalds * buffers. 8711da177e4SLinus Torvalds * 8721da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 8731da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 8741da177e4SLinus Torvalds */ 8751da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 8761da177e4SLinus Torvalds int retry) 8771da177e4SLinus Torvalds { 8781da177e4SLinus Torvalds struct buffer_head *bh, *head; 8791da177e4SLinus Torvalds long offset; 8801da177e4SLinus Torvalds 8811da177e4SLinus Torvalds try_again: 8821da177e4SLinus Torvalds head = NULL; 8831da177e4SLinus Torvalds offset = PAGE_SIZE; 8841da177e4SLinus Torvalds while ((offset -= size) >= 0) { 8851da177e4SLinus Torvalds bh = alloc_buffer_head(GFP_NOFS); 8861da177e4SLinus Torvalds if (!bh) 8871da177e4SLinus Torvalds goto no_grow; 8881da177e4SLinus Torvalds 8891da177e4SLinus Torvalds bh->b_this_page = head; 8901da177e4SLinus Torvalds bh->b_blocknr = -1; 8911da177e4SLinus Torvalds head = bh; 8921da177e4SLinus Torvalds 8931da177e4SLinus Torvalds bh->b_size = size; 8941da177e4SLinus Torvalds 8951da177e4SLinus Torvalds /* Link the buffer to its page */ 8961da177e4SLinus Torvalds set_bh_page(bh, page, offset); 8971da177e4SLinus Torvalds } 8981da177e4SLinus Torvalds return head; 8991da177e4SLinus Torvalds /* 9001da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 9011da177e4SLinus Torvalds */ 9021da177e4SLinus Torvalds no_grow: 9031da177e4SLinus Torvalds if (head) { 9041da177e4SLinus Torvalds do { 9051da177e4SLinus Torvalds bh = head; 9061da177e4SLinus Torvalds head = head->b_this_page; 9071da177e4SLinus Torvalds free_buffer_head(bh); 9081da177e4SLinus Torvalds } while (head); 9091da177e4SLinus Torvalds } 9101da177e4SLinus Torvalds 9111da177e4SLinus Torvalds /* 9121da177e4SLinus Torvalds * Return failure for non-async IO requests. Async IO requests 9131da177e4SLinus Torvalds * are not allowed to fail, so we have to wait until buffer heads 9141da177e4SLinus Torvalds * become available. But we don't want tasks sleeping with 9151da177e4SLinus Torvalds * partially complete buffers, so all were released above. 9161da177e4SLinus Torvalds */ 9171da177e4SLinus Torvalds if (!retry) 9181da177e4SLinus Torvalds return NULL; 9191da177e4SLinus Torvalds 9201da177e4SLinus Torvalds /* We're _really_ low on memory. Now we just 9211da177e4SLinus Torvalds * wait for old buffer heads to become free due to 9221da177e4SLinus Torvalds * finishing IO. Since this is an async request and 9231da177e4SLinus Torvalds * the reserve list is empty, we're sure there are 9241da177e4SLinus Torvalds * async buffer heads in use. 9251da177e4SLinus Torvalds */ 9261da177e4SLinus Torvalds free_more_memory(); 9271da177e4SLinus Torvalds goto try_again; 9281da177e4SLinus Torvalds } 9291da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 9301da177e4SLinus Torvalds 9311da177e4SLinus Torvalds static inline void 9321da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 9331da177e4SLinus Torvalds { 9341da177e4SLinus Torvalds struct buffer_head *bh, *tail; 9351da177e4SLinus Torvalds 9361da177e4SLinus Torvalds bh = head; 9371da177e4SLinus Torvalds do { 9381da177e4SLinus Torvalds tail = bh; 9391da177e4SLinus Torvalds bh = bh->b_this_page; 9401da177e4SLinus Torvalds } while (bh); 9411da177e4SLinus Torvalds tail->b_this_page = head; 9421da177e4SLinus Torvalds attach_page_buffers(page, head); 9431da177e4SLinus Torvalds } 9441da177e4SLinus Torvalds 945bbec0270SLinus Torvalds static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) 946bbec0270SLinus Torvalds { 947bbec0270SLinus Torvalds sector_t retval = ~((sector_t)0); 948bbec0270SLinus Torvalds loff_t sz = i_size_read(bdev->bd_inode); 949bbec0270SLinus Torvalds 950bbec0270SLinus Torvalds if (sz) { 951bbec0270SLinus Torvalds unsigned int sizebits = blksize_bits(size); 952bbec0270SLinus Torvalds retval = (sz >> sizebits); 953bbec0270SLinus Torvalds } 954bbec0270SLinus Torvalds return retval; 955bbec0270SLinus Torvalds } 956bbec0270SLinus Torvalds 9571da177e4SLinus Torvalds /* 9581da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 9591da177e4SLinus Torvalds */ 960676ce6d5SHugh Dickins static sector_t 9611da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 9621da177e4SLinus Torvalds sector_t block, int size) 9631da177e4SLinus Torvalds { 9641da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 9651da177e4SLinus Torvalds struct buffer_head *bh = head; 9661da177e4SLinus Torvalds int uptodate = PageUptodate(page); 967bbec0270SLinus Torvalds sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size); 9681da177e4SLinus Torvalds 9691da177e4SLinus Torvalds do { 9701da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 9711da177e4SLinus Torvalds init_buffer(bh, NULL, NULL); 9721da177e4SLinus Torvalds bh->b_bdev = bdev; 9731da177e4SLinus Torvalds bh->b_blocknr = block; 9741da177e4SLinus Torvalds if (uptodate) 9751da177e4SLinus Torvalds set_buffer_uptodate(bh); 976080399aaSJeff Moyer if (block < end_block) 9771da177e4SLinus Torvalds set_buffer_mapped(bh); 9781da177e4SLinus Torvalds } 9791da177e4SLinus Torvalds block++; 9801da177e4SLinus Torvalds bh = bh->b_this_page; 9811da177e4SLinus Torvalds } while (bh != head); 982676ce6d5SHugh Dickins 983676ce6d5SHugh Dickins /* 984676ce6d5SHugh Dickins * Caller needs to validate requested block against end of device. 985676ce6d5SHugh Dickins */ 986676ce6d5SHugh Dickins return end_block; 9871da177e4SLinus Torvalds } 9881da177e4SLinus Torvalds 9891da177e4SLinus Torvalds /* 9901da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 9911da177e4SLinus Torvalds * 992676ce6d5SHugh Dickins * This is used purely for blockdev mappings. 9931da177e4SLinus Torvalds */ 994676ce6d5SHugh Dickins static int 9951da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 996676ce6d5SHugh Dickins pgoff_t index, int size, int sizebits) 9971da177e4SLinus Torvalds { 9981da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 9991da177e4SLinus Torvalds struct page *page; 10001da177e4SLinus Torvalds struct buffer_head *bh; 1001676ce6d5SHugh Dickins sector_t end_block; 1002676ce6d5SHugh Dickins int ret = 0; /* Will call free_more_memory() */ 100384235de3SJohannes Weiner gfp_t gfp_mask; 10041da177e4SLinus Torvalds 100584235de3SJohannes Weiner gfp_mask = mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS; 100684235de3SJohannes Weiner gfp_mask |= __GFP_MOVABLE; 100784235de3SJohannes Weiner /* 100884235de3SJohannes Weiner * XXX: __getblk_slow() can not really deal with failure and 100984235de3SJohannes Weiner * will endlessly loop on improvised global reclaim. Prefer 101084235de3SJohannes Weiner * looping in the allocator rather than here, at least that 101184235de3SJohannes Weiner * code knows what it's doing. 101284235de3SJohannes Weiner */ 101384235de3SJohannes Weiner gfp_mask |= __GFP_NOFAIL; 101484235de3SJohannes Weiner 101584235de3SJohannes Weiner page = find_or_create_page(inode->i_mapping, index, gfp_mask); 10161da177e4SLinus Torvalds if (!page) 1017676ce6d5SHugh Dickins return ret; 10181da177e4SLinus Torvalds 1019e827f923SEric Sesterhenn BUG_ON(!PageLocked(page)); 10201da177e4SLinus Torvalds 10211da177e4SLinus Torvalds if (page_has_buffers(page)) { 10221da177e4SLinus Torvalds bh = page_buffers(page); 10231da177e4SLinus Torvalds if (bh->b_size == size) { 1024676ce6d5SHugh Dickins end_block = init_page_buffers(page, bdev, 1025676ce6d5SHugh Dickins index << sizebits, size); 1026676ce6d5SHugh Dickins goto done; 10271da177e4SLinus Torvalds } 10281da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 10291da177e4SLinus Torvalds goto failed; 10301da177e4SLinus Torvalds } 10311da177e4SLinus Torvalds 10321da177e4SLinus Torvalds /* 10331da177e4SLinus Torvalds * Allocate some buffers for this page 10341da177e4SLinus Torvalds */ 10351da177e4SLinus Torvalds bh = alloc_page_buffers(page, size, 0); 10361da177e4SLinus Torvalds if (!bh) 10371da177e4SLinus Torvalds goto failed; 10381da177e4SLinus Torvalds 10391da177e4SLinus Torvalds /* 10401da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 10411da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 10421da177e4SLinus Torvalds * run under the page lock. 10431da177e4SLinus Torvalds */ 10441da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 10451da177e4SLinus Torvalds link_dev_buffers(page, bh); 1046676ce6d5SHugh Dickins end_block = init_page_buffers(page, bdev, index << sizebits, size); 10471da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 1048676ce6d5SHugh Dickins done: 1049676ce6d5SHugh Dickins ret = (block < end_block) ? 1 : -ENXIO; 10501da177e4SLinus Torvalds failed: 10511da177e4SLinus Torvalds unlock_page(page); 10521da177e4SLinus Torvalds page_cache_release(page); 1053676ce6d5SHugh Dickins return ret; 10541da177e4SLinus Torvalds } 10551da177e4SLinus Torvalds 10561da177e4SLinus Torvalds /* 10571da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 10581da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 10591da177e4SLinus Torvalds */ 1060858119e1SArjan van de Ven static int 10611da177e4SLinus Torvalds grow_buffers(struct block_device *bdev, sector_t block, int size) 10621da177e4SLinus Torvalds { 10631da177e4SLinus Torvalds pgoff_t index; 10641da177e4SLinus Torvalds int sizebits; 10651da177e4SLinus Torvalds 10661da177e4SLinus Torvalds sizebits = -1; 10671da177e4SLinus Torvalds do { 10681da177e4SLinus Torvalds sizebits++; 10691da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 10701da177e4SLinus Torvalds 10711da177e4SLinus Torvalds index = block >> sizebits; 10721da177e4SLinus Torvalds 1073e5657933SAndrew Morton /* 1074e5657933SAndrew Morton * Check for a block which wants to lie outside our maximum possible 1075e5657933SAndrew Morton * pagecache index. (this comparison is done using sector_t types). 1076e5657933SAndrew Morton */ 1077e5657933SAndrew Morton if (unlikely(index != block >> sizebits)) { 1078e5657933SAndrew Morton char b[BDEVNAME_SIZE]; 1079e5657933SAndrew Morton 1080e5657933SAndrew Morton printk(KERN_ERR "%s: requested out-of-range block %llu for " 1081e5657933SAndrew Morton "device %s\n", 10828e24eea7SHarvey Harrison __func__, (unsigned long long)block, 1083e5657933SAndrew Morton bdevname(bdev, b)); 1084e5657933SAndrew Morton return -EIO; 1085e5657933SAndrew Morton } 1086676ce6d5SHugh Dickins 10871da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 1088676ce6d5SHugh Dickins return grow_dev_page(bdev, block, index, size, sizebits); 10891da177e4SLinus Torvalds } 10901da177e4SLinus Torvalds 109175c96f85SAdrian Bunk static struct buffer_head * 10921da177e4SLinus Torvalds __getblk_slow(struct block_device *bdev, sector_t block, int size) 10931da177e4SLinus Torvalds { 10941da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 1095e1defc4fSMartin K. Petersen if (unlikely(size & (bdev_logical_block_size(bdev)-1) || 10961da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 10971da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 10981da177e4SLinus Torvalds size); 1099e1defc4fSMartin K. Petersen printk(KERN_ERR "logical block size: %d\n", 1100e1defc4fSMartin K. Petersen bdev_logical_block_size(bdev)); 11011da177e4SLinus Torvalds 11021da177e4SLinus Torvalds dump_stack(); 11031da177e4SLinus Torvalds return NULL; 11041da177e4SLinus Torvalds } 11051da177e4SLinus Torvalds 1106676ce6d5SHugh Dickins for (;;) { 1107676ce6d5SHugh Dickins struct buffer_head *bh; 1108676ce6d5SHugh Dickins int ret; 1109676ce6d5SHugh Dickins 11101da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 11111da177e4SLinus Torvalds if (bh) 11121da177e4SLinus Torvalds return bh; 11131da177e4SLinus Torvalds 1114e5657933SAndrew Morton ret = grow_buffers(bdev, block, size); 1115676ce6d5SHugh Dickins if (ret < 0) 111691f68c89SJeff Moyer return NULL; 1117676ce6d5SHugh Dickins if (ret == 0) 1118676ce6d5SHugh Dickins free_more_memory(); 1119676ce6d5SHugh Dickins } 11201da177e4SLinus Torvalds } 11211da177e4SLinus Torvalds 11221da177e4SLinus Torvalds /* 11231da177e4SLinus Torvalds * The relationship between dirty buffers and dirty pages: 11241da177e4SLinus Torvalds * 11251da177e4SLinus Torvalds * Whenever a page has any dirty buffers, the page's dirty bit is set, and 11261da177e4SLinus Torvalds * the page is tagged dirty in its radix tree. 11271da177e4SLinus Torvalds * 11281da177e4SLinus Torvalds * At all times, the dirtiness of the buffers represents the dirtiness of 11291da177e4SLinus Torvalds * subsections of the page. If the page has buffers, the page dirty bit is 11301da177e4SLinus Torvalds * merely a hint about the true dirty state. 11311da177e4SLinus Torvalds * 11321da177e4SLinus Torvalds * When a page is set dirty in its entirety, all its buffers are marked dirty 11331da177e4SLinus Torvalds * (if the page has buffers). 11341da177e4SLinus Torvalds * 11351da177e4SLinus Torvalds * When a buffer is marked dirty, its page is dirtied, but the page's other 11361da177e4SLinus Torvalds * buffers are not. 11371da177e4SLinus Torvalds * 11381da177e4SLinus Torvalds * Also. When blockdev buffers are explicitly read with bread(), they 11391da177e4SLinus Torvalds * individually become uptodate. But their backing page remains not 11401da177e4SLinus Torvalds * uptodate - even if all of its buffers are uptodate. A subsequent 11411da177e4SLinus Torvalds * block_read_full_page() against that page will discover all the uptodate 11421da177e4SLinus Torvalds * buffers, will set the page uptodate and will perform no I/O. 11431da177e4SLinus Torvalds */ 11441da177e4SLinus Torvalds 11451da177e4SLinus Torvalds /** 11461da177e4SLinus Torvalds * mark_buffer_dirty - mark a buffer_head as needing writeout 114767be2dd1SMartin Waitz * @bh: the buffer_head to mark dirty 11481da177e4SLinus Torvalds * 11491da177e4SLinus Torvalds * mark_buffer_dirty() will set the dirty bit against the buffer, then set its 11501da177e4SLinus Torvalds * backing page dirty, then tag the page as dirty in its address_space's radix 11511da177e4SLinus Torvalds * tree and then attach the address_space's inode to its superblock's dirty 11521da177e4SLinus Torvalds * inode list. 11531da177e4SLinus Torvalds * 11541da177e4SLinus Torvalds * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, 1155250df6edSDave Chinner * mapping->tree_lock and mapping->host->i_lock. 11561da177e4SLinus Torvalds */ 1157fc9b52cdSHarvey Harrison void mark_buffer_dirty(struct buffer_head *bh) 11581da177e4SLinus Torvalds { 1159787d2214SNick Piggin WARN_ON_ONCE(!buffer_uptodate(bh)); 11601be62dc1SLinus Torvalds 11615305cb83STejun Heo trace_block_dirty_buffer(bh); 11625305cb83STejun Heo 11631be62dc1SLinus Torvalds /* 11641be62dc1SLinus Torvalds * Very *carefully* optimize the it-is-already-dirty case. 11651be62dc1SLinus Torvalds * 11661be62dc1SLinus Torvalds * Don't let the final "is it dirty" escape to before we 11671be62dc1SLinus Torvalds * perhaps modified the buffer. 11681be62dc1SLinus Torvalds */ 11691be62dc1SLinus Torvalds if (buffer_dirty(bh)) { 11701be62dc1SLinus Torvalds smp_mb(); 11711be62dc1SLinus Torvalds if (buffer_dirty(bh)) 11721be62dc1SLinus Torvalds return; 11731be62dc1SLinus Torvalds } 11741be62dc1SLinus Torvalds 1175a8e7d49aSLinus Torvalds if (!test_set_buffer_dirty(bh)) { 1176a8e7d49aSLinus Torvalds struct page *page = bh->b_page; 11778e9d78edSLinus Torvalds if (!TestSetPageDirty(page)) { 11788e9d78edSLinus Torvalds struct address_space *mapping = page_mapping(page); 11798e9d78edSLinus Torvalds if (mapping) 11808e9d78edSLinus Torvalds __set_page_dirty(page, mapping, 0); 11818e9d78edSLinus Torvalds } 1182a8e7d49aSLinus Torvalds } 11831da177e4SLinus Torvalds } 11841fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(mark_buffer_dirty); 11851da177e4SLinus Torvalds 11861da177e4SLinus Torvalds /* 11871da177e4SLinus Torvalds * Decrement a buffer_head's reference count. If all buffers against a page 11881da177e4SLinus Torvalds * have zero reference count, are clean and unlocked, and if the page is clean 11891da177e4SLinus Torvalds * and unlocked then try_to_free_buffers() may strip the buffers from the page 11901da177e4SLinus Torvalds * in preparation for freeing it (sometimes, rarely, buffers are removed from 11911da177e4SLinus Torvalds * a page but it ends up not being freed, and buffers may later be reattached). 11921da177e4SLinus Torvalds */ 11931da177e4SLinus Torvalds void __brelse(struct buffer_head * buf) 11941da177e4SLinus Torvalds { 11951da177e4SLinus Torvalds if (atomic_read(&buf->b_count)) { 11961da177e4SLinus Torvalds put_bh(buf); 11971da177e4SLinus Torvalds return; 11981da177e4SLinus Torvalds } 11995c752ad9SArjan van de Ven WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); 12001da177e4SLinus Torvalds } 12011fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__brelse); 12021da177e4SLinus Torvalds 12031da177e4SLinus Torvalds /* 12041da177e4SLinus Torvalds * bforget() is like brelse(), except it discards any 12051da177e4SLinus Torvalds * potentially dirty data. 12061da177e4SLinus Torvalds */ 12071da177e4SLinus Torvalds void __bforget(struct buffer_head *bh) 12081da177e4SLinus Torvalds { 12091da177e4SLinus Torvalds clear_buffer_dirty(bh); 1210535ee2fbSJan Kara if (bh->b_assoc_map) { 12111da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 12121da177e4SLinus Torvalds 12131da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 12141da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 121558ff407bSJan Kara bh->b_assoc_map = NULL; 12161da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 12171da177e4SLinus Torvalds } 12181da177e4SLinus Torvalds __brelse(bh); 12191da177e4SLinus Torvalds } 12201fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(__bforget); 12211da177e4SLinus Torvalds 12221da177e4SLinus Torvalds static struct buffer_head *__bread_slow(struct buffer_head *bh) 12231da177e4SLinus Torvalds { 12241da177e4SLinus Torvalds lock_buffer(bh); 12251da177e4SLinus Torvalds if (buffer_uptodate(bh)) { 12261da177e4SLinus Torvalds unlock_buffer(bh); 12271da177e4SLinus Torvalds return bh; 12281da177e4SLinus Torvalds } else { 12291da177e4SLinus Torvalds get_bh(bh); 12301da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_sync; 12311da177e4SLinus Torvalds submit_bh(READ, bh); 12321da177e4SLinus Torvalds wait_on_buffer(bh); 12331da177e4SLinus Torvalds if (buffer_uptodate(bh)) 12341da177e4SLinus Torvalds return bh; 12351da177e4SLinus Torvalds } 12361da177e4SLinus Torvalds brelse(bh); 12371da177e4SLinus Torvalds return NULL; 12381da177e4SLinus Torvalds } 12391da177e4SLinus Torvalds 12401da177e4SLinus Torvalds /* 12411da177e4SLinus Torvalds * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). 12421da177e4SLinus Torvalds * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their 12431da177e4SLinus Torvalds * refcount elevated by one when they're in an LRU. A buffer can only appear 12441da177e4SLinus Torvalds * once in a particular CPU's LRU. A single buffer can be present in multiple 12451da177e4SLinus Torvalds * CPU's LRUs at the same time. 12461da177e4SLinus Torvalds * 12471da177e4SLinus Torvalds * This is a transparent caching front-end to sb_bread(), sb_getblk() and 12481da177e4SLinus Torvalds * sb_find_get_block(). 12491da177e4SLinus Torvalds * 12501da177e4SLinus Torvalds * The LRUs themselves only need locking against invalidate_bh_lrus. We use 12511da177e4SLinus Torvalds * a local interrupt disable for that. 12521da177e4SLinus Torvalds */ 12531da177e4SLinus Torvalds 12541da177e4SLinus Torvalds #define BH_LRU_SIZE 8 12551da177e4SLinus Torvalds 12561da177e4SLinus Torvalds struct bh_lru { 12571da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12581da177e4SLinus Torvalds }; 12591da177e4SLinus Torvalds 12601da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; 12611da177e4SLinus Torvalds 12621da177e4SLinus Torvalds #ifdef CONFIG_SMP 12631da177e4SLinus Torvalds #define bh_lru_lock() local_irq_disable() 12641da177e4SLinus Torvalds #define bh_lru_unlock() local_irq_enable() 12651da177e4SLinus Torvalds #else 12661da177e4SLinus Torvalds #define bh_lru_lock() preempt_disable() 12671da177e4SLinus Torvalds #define bh_lru_unlock() preempt_enable() 12681da177e4SLinus Torvalds #endif 12691da177e4SLinus Torvalds 12701da177e4SLinus Torvalds static inline void check_irqs_on(void) 12711da177e4SLinus Torvalds { 12721da177e4SLinus Torvalds #ifdef irqs_disabled 12731da177e4SLinus Torvalds BUG_ON(irqs_disabled()); 12741da177e4SLinus Torvalds #endif 12751da177e4SLinus Torvalds } 12761da177e4SLinus Torvalds 12771da177e4SLinus Torvalds /* 12781da177e4SLinus Torvalds * The LRU management algorithm is dopey-but-simple. Sorry. 12791da177e4SLinus Torvalds */ 12801da177e4SLinus Torvalds static void bh_lru_install(struct buffer_head *bh) 12811da177e4SLinus Torvalds { 12821da177e4SLinus Torvalds struct buffer_head *evictee = NULL; 12831da177e4SLinus Torvalds 12841da177e4SLinus Torvalds check_irqs_on(); 12851da177e4SLinus Torvalds bh_lru_lock(); 1286c7b92516SChristoph Lameter if (__this_cpu_read(bh_lrus.bhs[0]) != bh) { 12871da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12881da177e4SLinus Torvalds int in; 12891da177e4SLinus Torvalds int out = 0; 12901da177e4SLinus Torvalds 12911da177e4SLinus Torvalds get_bh(bh); 12921da177e4SLinus Torvalds bhs[out++] = bh; 12931da177e4SLinus Torvalds for (in = 0; in < BH_LRU_SIZE; in++) { 1294c7b92516SChristoph Lameter struct buffer_head *bh2 = 1295c7b92516SChristoph Lameter __this_cpu_read(bh_lrus.bhs[in]); 12961da177e4SLinus Torvalds 12971da177e4SLinus Torvalds if (bh2 == bh) { 12981da177e4SLinus Torvalds __brelse(bh2); 12991da177e4SLinus Torvalds } else { 13001da177e4SLinus Torvalds if (out >= BH_LRU_SIZE) { 13011da177e4SLinus Torvalds BUG_ON(evictee != NULL); 13021da177e4SLinus Torvalds evictee = bh2; 13031da177e4SLinus Torvalds } else { 13041da177e4SLinus Torvalds bhs[out++] = bh2; 13051da177e4SLinus Torvalds } 13061da177e4SLinus Torvalds } 13071da177e4SLinus Torvalds } 13081da177e4SLinus Torvalds while (out < BH_LRU_SIZE) 13091da177e4SLinus Torvalds bhs[out++] = NULL; 1310ca6673b0SChristoph Lameter memcpy(this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs)); 13111da177e4SLinus Torvalds } 13121da177e4SLinus Torvalds bh_lru_unlock(); 13131da177e4SLinus Torvalds 13141da177e4SLinus Torvalds if (evictee) 13151da177e4SLinus Torvalds __brelse(evictee); 13161da177e4SLinus Torvalds } 13171da177e4SLinus Torvalds 13181da177e4SLinus Torvalds /* 13191da177e4SLinus Torvalds * Look up the bh in this cpu's LRU. If it's there, move it to the head. 13201da177e4SLinus Torvalds */ 1321858119e1SArjan van de Ven static struct buffer_head * 13223991d3bdSTomasz Kvarsin lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) 13231da177e4SLinus Torvalds { 13241da177e4SLinus Torvalds struct buffer_head *ret = NULL; 13253991d3bdSTomasz Kvarsin unsigned int i; 13261da177e4SLinus Torvalds 13271da177e4SLinus Torvalds check_irqs_on(); 13281da177e4SLinus Torvalds bh_lru_lock(); 13291da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 1330c7b92516SChristoph Lameter struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); 13311da177e4SLinus Torvalds 13321da177e4SLinus Torvalds if (bh && bh->b_bdev == bdev && 13331da177e4SLinus Torvalds bh->b_blocknr == block && bh->b_size == size) { 13341da177e4SLinus Torvalds if (i) { 13351da177e4SLinus Torvalds while (i) { 1336c7b92516SChristoph Lameter __this_cpu_write(bh_lrus.bhs[i], 1337c7b92516SChristoph Lameter __this_cpu_read(bh_lrus.bhs[i - 1])); 13381da177e4SLinus Torvalds i--; 13391da177e4SLinus Torvalds } 1340c7b92516SChristoph Lameter __this_cpu_write(bh_lrus.bhs[0], bh); 13411da177e4SLinus Torvalds } 13421da177e4SLinus Torvalds get_bh(bh); 13431da177e4SLinus Torvalds ret = bh; 13441da177e4SLinus Torvalds break; 13451da177e4SLinus Torvalds } 13461da177e4SLinus Torvalds } 13471da177e4SLinus Torvalds bh_lru_unlock(); 13481da177e4SLinus Torvalds return ret; 13491da177e4SLinus Torvalds } 13501da177e4SLinus Torvalds 13511da177e4SLinus Torvalds /* 13521da177e4SLinus Torvalds * Perform a pagecache lookup for the matching buffer. If it's there, refresh 13531da177e4SLinus Torvalds * it in the LRU and mark it as accessed. If it is not present then return 13541da177e4SLinus Torvalds * NULL 13551da177e4SLinus Torvalds */ 13561da177e4SLinus Torvalds struct buffer_head * 13573991d3bdSTomasz Kvarsin __find_get_block(struct block_device *bdev, sector_t block, unsigned size) 13581da177e4SLinus Torvalds { 13591da177e4SLinus Torvalds struct buffer_head *bh = lookup_bh_lru(bdev, block, size); 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds if (bh == NULL) { 13622457aec6SMel Gorman /* __find_get_block_slow will mark the page accessed */ 1363385fd4c5SCoywolf Qi Hunt bh = __find_get_block_slow(bdev, block); 13641da177e4SLinus Torvalds if (bh) 13651da177e4SLinus Torvalds bh_lru_install(bh); 13662457aec6SMel Gorman } else 13671da177e4SLinus Torvalds touch_buffer(bh); 13682457aec6SMel Gorman 13691da177e4SLinus Torvalds return bh; 13701da177e4SLinus Torvalds } 13711da177e4SLinus Torvalds EXPORT_SYMBOL(__find_get_block); 13721da177e4SLinus Torvalds 13731da177e4SLinus Torvalds /* 13741da177e4SLinus Torvalds * __getblk will locate (and, if necessary, create) the buffer_head 13751da177e4SLinus Torvalds * which corresponds to the passed block_device, block and size. The 13761da177e4SLinus Torvalds * returned buffer has its reference count incremented. 13771da177e4SLinus Torvalds * 13781da177e4SLinus Torvalds * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() 13791da177e4SLinus Torvalds * attempt is failing. FIXME, perhaps? 13801da177e4SLinus Torvalds */ 13811da177e4SLinus Torvalds struct buffer_head * 13823991d3bdSTomasz Kvarsin __getblk(struct block_device *bdev, sector_t block, unsigned size) 13831da177e4SLinus Torvalds { 13841da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, block, size); 13851da177e4SLinus Torvalds 13861da177e4SLinus Torvalds might_sleep(); 13871da177e4SLinus Torvalds if (bh == NULL) 13881da177e4SLinus Torvalds bh = __getblk_slow(bdev, block, size); 13891da177e4SLinus Torvalds return bh; 13901da177e4SLinus Torvalds } 13911da177e4SLinus Torvalds EXPORT_SYMBOL(__getblk); 13921da177e4SLinus Torvalds 13931da177e4SLinus Torvalds /* 13941da177e4SLinus Torvalds * Do async read-ahead on a buffer.. 13951da177e4SLinus Torvalds */ 13963991d3bdSTomasz Kvarsin void __breadahead(struct block_device *bdev, sector_t block, unsigned size) 13971da177e4SLinus Torvalds { 13981da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 1399a3e713b5SAndrew Morton if (likely(bh)) { 14001da177e4SLinus Torvalds ll_rw_block(READA, 1, &bh); 14011da177e4SLinus Torvalds brelse(bh); 14021da177e4SLinus Torvalds } 1403a3e713b5SAndrew Morton } 14041da177e4SLinus Torvalds EXPORT_SYMBOL(__breadahead); 14051da177e4SLinus Torvalds 14061da177e4SLinus Torvalds /** 14071da177e4SLinus Torvalds * __bread() - reads a specified block and returns the bh 140867be2dd1SMartin Waitz * @bdev: the block_device to read from 14091da177e4SLinus Torvalds * @block: number of block 14101da177e4SLinus Torvalds * @size: size (in bytes) to read 14111da177e4SLinus Torvalds * 14121da177e4SLinus Torvalds * Reads a specified block, and returns buffer head that contains it. 14131da177e4SLinus Torvalds * It returns NULL if the block was unreadable. 14141da177e4SLinus Torvalds */ 14151da177e4SLinus Torvalds struct buffer_head * 14163991d3bdSTomasz Kvarsin __bread(struct block_device *bdev, sector_t block, unsigned size) 14171da177e4SLinus Torvalds { 14181da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 14191da177e4SLinus Torvalds 1420a3e713b5SAndrew Morton if (likely(bh) && !buffer_uptodate(bh)) 14211da177e4SLinus Torvalds bh = __bread_slow(bh); 14221da177e4SLinus Torvalds return bh; 14231da177e4SLinus Torvalds } 14241da177e4SLinus Torvalds EXPORT_SYMBOL(__bread); 14251da177e4SLinus Torvalds 14261da177e4SLinus Torvalds /* 14271da177e4SLinus Torvalds * invalidate_bh_lrus() is called rarely - but not only at unmount. 14281da177e4SLinus Torvalds * This doesn't race because it runs in each cpu either in irq 14291da177e4SLinus Torvalds * or with preempt disabled. 14301da177e4SLinus Torvalds */ 14311da177e4SLinus Torvalds static void invalidate_bh_lru(void *arg) 14321da177e4SLinus Torvalds { 14331da177e4SLinus Torvalds struct bh_lru *b = &get_cpu_var(bh_lrus); 14341da177e4SLinus Torvalds int i; 14351da177e4SLinus Torvalds 14361da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 14371da177e4SLinus Torvalds brelse(b->bhs[i]); 14381da177e4SLinus Torvalds b->bhs[i] = NULL; 14391da177e4SLinus Torvalds } 14401da177e4SLinus Torvalds put_cpu_var(bh_lrus); 14411da177e4SLinus Torvalds } 14421da177e4SLinus Torvalds 144342be35d0SGilad Ben-Yossef static bool has_bh_in_lru(int cpu, void *dummy) 144442be35d0SGilad Ben-Yossef { 144542be35d0SGilad Ben-Yossef struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); 144642be35d0SGilad Ben-Yossef int i; 144742be35d0SGilad Ben-Yossef 144842be35d0SGilad Ben-Yossef for (i = 0; i < BH_LRU_SIZE; i++) { 144942be35d0SGilad Ben-Yossef if (b->bhs[i]) 145042be35d0SGilad Ben-Yossef return 1; 145142be35d0SGilad Ben-Yossef } 145242be35d0SGilad Ben-Yossef 145342be35d0SGilad Ben-Yossef return 0; 145442be35d0SGilad Ben-Yossef } 145542be35d0SGilad Ben-Yossef 1456f9a14399SPeter Zijlstra void invalidate_bh_lrus(void) 14571da177e4SLinus Torvalds { 145842be35d0SGilad Ben-Yossef on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); 14591da177e4SLinus Torvalds } 14609db5579bSNick Piggin EXPORT_SYMBOL_GPL(invalidate_bh_lrus); 14611da177e4SLinus Torvalds 14621da177e4SLinus Torvalds void set_bh_page(struct buffer_head *bh, 14631da177e4SLinus Torvalds struct page *page, unsigned long offset) 14641da177e4SLinus Torvalds { 14651da177e4SLinus Torvalds bh->b_page = page; 1466e827f923SEric Sesterhenn BUG_ON(offset >= PAGE_SIZE); 14671da177e4SLinus Torvalds if (PageHighMem(page)) 14681da177e4SLinus Torvalds /* 14691da177e4SLinus Torvalds * This catches illegal uses and preserves the offset: 14701da177e4SLinus Torvalds */ 14711da177e4SLinus Torvalds bh->b_data = (char *)(0 + offset); 14721da177e4SLinus Torvalds else 14731da177e4SLinus Torvalds bh->b_data = page_address(page) + offset; 14741da177e4SLinus Torvalds } 14751da177e4SLinus Torvalds EXPORT_SYMBOL(set_bh_page); 14761da177e4SLinus Torvalds 14771da177e4SLinus Torvalds /* 14781da177e4SLinus Torvalds * Called when truncating a buffer on a page completely. 14791da177e4SLinus Torvalds */ 1480e7470ee8SMel Gorman 1481e7470ee8SMel Gorman /* Bits that are cleared during an invalidate */ 1482e7470ee8SMel Gorman #define BUFFER_FLAGS_DISCARD \ 1483e7470ee8SMel Gorman (1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \ 1484e7470ee8SMel Gorman 1 << BH_Delay | 1 << BH_Unwritten) 1485e7470ee8SMel Gorman 1486858119e1SArjan van de Ven static void discard_buffer(struct buffer_head * bh) 14871da177e4SLinus Torvalds { 1488e7470ee8SMel Gorman unsigned long b_state, b_state_old; 1489e7470ee8SMel Gorman 14901da177e4SLinus Torvalds lock_buffer(bh); 14911da177e4SLinus Torvalds clear_buffer_dirty(bh); 14921da177e4SLinus Torvalds bh->b_bdev = NULL; 1493e7470ee8SMel Gorman b_state = bh->b_state; 1494e7470ee8SMel Gorman for (;;) { 1495e7470ee8SMel Gorman b_state_old = cmpxchg(&bh->b_state, b_state, 1496e7470ee8SMel Gorman (b_state & ~BUFFER_FLAGS_DISCARD)); 1497e7470ee8SMel Gorman if (b_state_old == b_state) 1498e7470ee8SMel Gorman break; 1499e7470ee8SMel Gorman b_state = b_state_old; 1500e7470ee8SMel Gorman } 15011da177e4SLinus Torvalds unlock_buffer(bh); 15021da177e4SLinus Torvalds } 15031da177e4SLinus Torvalds 15041da177e4SLinus Torvalds /** 1505814e1d25SWang Sheng-Hui * block_invalidatepage - invalidate part or all of a buffer-backed page 15061da177e4SLinus Torvalds * 15071da177e4SLinus Torvalds * @page: the page which is affected 1508d47992f8SLukas Czerner * @offset: start of the range to invalidate 1509d47992f8SLukas Czerner * @length: length of the range to invalidate 15101da177e4SLinus Torvalds * 15111da177e4SLinus Torvalds * block_invalidatepage() is called when all or part of the page has become 15121da177e4SLinus Torvalds * invalidated by a truncate operation. 15131da177e4SLinus Torvalds * 15141da177e4SLinus Torvalds * block_invalidatepage() does not have to release all buffers, but it must 15151da177e4SLinus Torvalds * ensure that no dirty buffer is left outside @offset and that no I/O 15161da177e4SLinus Torvalds * is underway against any of the blocks which are outside the truncation 15171da177e4SLinus Torvalds * point. Because the caller is about to free (and possibly reuse) those 15181da177e4SLinus Torvalds * blocks on-disk. 15191da177e4SLinus Torvalds */ 1520d47992f8SLukas Czerner void block_invalidatepage(struct page *page, unsigned int offset, 1521d47992f8SLukas Czerner unsigned int length) 15221da177e4SLinus Torvalds { 15231da177e4SLinus Torvalds struct buffer_head *head, *bh, *next; 15241da177e4SLinus Torvalds unsigned int curr_off = 0; 1525d47992f8SLukas Czerner unsigned int stop = length + offset; 15261da177e4SLinus Torvalds 15271da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 15281da177e4SLinus Torvalds if (!page_has_buffers(page)) 15291da177e4SLinus Torvalds goto out; 15301da177e4SLinus Torvalds 1531d47992f8SLukas Czerner /* 1532d47992f8SLukas Czerner * Check for overflow 1533d47992f8SLukas Czerner */ 1534d47992f8SLukas Czerner BUG_ON(stop > PAGE_CACHE_SIZE || stop < length); 1535d47992f8SLukas Czerner 15361da177e4SLinus Torvalds head = page_buffers(page); 15371da177e4SLinus Torvalds bh = head; 15381da177e4SLinus Torvalds do { 15391da177e4SLinus Torvalds unsigned int next_off = curr_off + bh->b_size; 15401da177e4SLinus Torvalds next = bh->b_this_page; 15411da177e4SLinus Torvalds 15421da177e4SLinus Torvalds /* 1543d47992f8SLukas Czerner * Are we still fully in range ? 1544d47992f8SLukas Czerner */ 1545d47992f8SLukas Czerner if (next_off > stop) 1546d47992f8SLukas Czerner goto out; 1547d47992f8SLukas Czerner 1548d47992f8SLukas Czerner /* 15491da177e4SLinus Torvalds * is this block fully invalidated? 15501da177e4SLinus Torvalds */ 15511da177e4SLinus Torvalds if (offset <= curr_off) 15521da177e4SLinus Torvalds discard_buffer(bh); 15531da177e4SLinus Torvalds curr_off = next_off; 15541da177e4SLinus Torvalds bh = next; 15551da177e4SLinus Torvalds } while (bh != head); 15561da177e4SLinus Torvalds 15571da177e4SLinus Torvalds /* 15581da177e4SLinus Torvalds * We release buffers only if the entire page is being invalidated. 15591da177e4SLinus Torvalds * The get_block cached value has been unconditionally invalidated, 15601da177e4SLinus Torvalds * so real IO is not possible anymore. 15611da177e4SLinus Torvalds */ 15621da177e4SLinus Torvalds if (offset == 0) 15632ff28e22SNeilBrown try_to_release_page(page, 0); 15641da177e4SLinus Torvalds out: 15652ff28e22SNeilBrown return; 15661da177e4SLinus Torvalds } 15671da177e4SLinus Torvalds EXPORT_SYMBOL(block_invalidatepage); 15681da177e4SLinus Torvalds 1569d47992f8SLukas Czerner 15701da177e4SLinus Torvalds /* 15711da177e4SLinus Torvalds * We attach and possibly dirty the buffers atomically wrt 15721da177e4SLinus Torvalds * __set_page_dirty_buffers() via private_lock. try_to_free_buffers 15731da177e4SLinus Torvalds * is already excluded via the page lock. 15741da177e4SLinus Torvalds */ 15751da177e4SLinus Torvalds void create_empty_buffers(struct page *page, 15761da177e4SLinus Torvalds unsigned long blocksize, unsigned long b_state) 15771da177e4SLinus Torvalds { 15781da177e4SLinus Torvalds struct buffer_head *bh, *head, *tail; 15791da177e4SLinus Torvalds 15801da177e4SLinus Torvalds head = alloc_page_buffers(page, blocksize, 1); 15811da177e4SLinus Torvalds bh = head; 15821da177e4SLinus Torvalds do { 15831da177e4SLinus Torvalds bh->b_state |= b_state; 15841da177e4SLinus Torvalds tail = bh; 15851da177e4SLinus Torvalds bh = bh->b_this_page; 15861da177e4SLinus Torvalds } while (bh); 15871da177e4SLinus Torvalds tail->b_this_page = head; 15881da177e4SLinus Torvalds 15891da177e4SLinus Torvalds spin_lock(&page->mapping->private_lock); 15901da177e4SLinus Torvalds if (PageUptodate(page) || PageDirty(page)) { 15911da177e4SLinus Torvalds bh = head; 15921da177e4SLinus Torvalds do { 15931da177e4SLinus Torvalds if (PageDirty(page)) 15941da177e4SLinus Torvalds set_buffer_dirty(bh); 15951da177e4SLinus Torvalds if (PageUptodate(page)) 15961da177e4SLinus Torvalds set_buffer_uptodate(bh); 15971da177e4SLinus Torvalds bh = bh->b_this_page; 15981da177e4SLinus Torvalds } while (bh != head); 15991da177e4SLinus Torvalds } 16001da177e4SLinus Torvalds attach_page_buffers(page, head); 16011da177e4SLinus Torvalds spin_unlock(&page->mapping->private_lock); 16021da177e4SLinus Torvalds } 16031da177e4SLinus Torvalds EXPORT_SYMBOL(create_empty_buffers); 16041da177e4SLinus Torvalds 16051da177e4SLinus Torvalds /* 16061da177e4SLinus Torvalds * We are taking a block for data and we don't want any output from any 16071da177e4SLinus Torvalds * buffer-cache aliases starting from return from that function and 16081da177e4SLinus Torvalds * until the moment when something will explicitly mark the buffer 16091da177e4SLinus Torvalds * dirty (hopefully that will not happen until we will free that block ;-) 16101da177e4SLinus Torvalds * We don't even need to mark it not-uptodate - nobody can expect 16111da177e4SLinus Torvalds * anything from a newly allocated buffer anyway. We used to used 16121da177e4SLinus Torvalds * unmap_buffer() for such invalidation, but that was wrong. We definitely 16131da177e4SLinus Torvalds * don't want to mark the alias unmapped, for example - it would confuse 16141da177e4SLinus Torvalds * anyone who might pick it with bread() afterwards... 16151da177e4SLinus Torvalds * 16161da177e4SLinus Torvalds * Also.. Note that bforget() doesn't lock the buffer. So there can 16171da177e4SLinus Torvalds * be writeout I/O going on against recently-freed buffers. We don't 16181da177e4SLinus Torvalds * wait on that I/O in bforget() - it's more efficient to wait on the I/O 16191da177e4SLinus Torvalds * only if we really need to. That happens here. 16201da177e4SLinus Torvalds */ 16211da177e4SLinus Torvalds void unmap_underlying_metadata(struct block_device *bdev, sector_t block) 16221da177e4SLinus Torvalds { 16231da177e4SLinus Torvalds struct buffer_head *old_bh; 16241da177e4SLinus Torvalds 16251da177e4SLinus Torvalds might_sleep(); 16261da177e4SLinus Torvalds 1627385fd4c5SCoywolf Qi Hunt old_bh = __find_get_block_slow(bdev, block); 16281da177e4SLinus Torvalds if (old_bh) { 16291da177e4SLinus Torvalds clear_buffer_dirty(old_bh); 16301da177e4SLinus Torvalds wait_on_buffer(old_bh); 16311da177e4SLinus Torvalds clear_buffer_req(old_bh); 16321da177e4SLinus Torvalds __brelse(old_bh); 16331da177e4SLinus Torvalds } 16341da177e4SLinus Torvalds } 16351da177e4SLinus Torvalds EXPORT_SYMBOL(unmap_underlying_metadata); 16361da177e4SLinus Torvalds 16371da177e4SLinus Torvalds /* 163845bce8f3SLinus Torvalds * Size is a power-of-two in the range 512..PAGE_SIZE, 163945bce8f3SLinus Torvalds * and the case we care about most is PAGE_SIZE. 164045bce8f3SLinus Torvalds * 164145bce8f3SLinus Torvalds * So this *could* possibly be written with those 164245bce8f3SLinus Torvalds * constraints in mind (relevant mostly if some 164345bce8f3SLinus Torvalds * architecture has a slow bit-scan instruction) 164445bce8f3SLinus Torvalds */ 164545bce8f3SLinus Torvalds static inline int block_size_bits(unsigned int blocksize) 164645bce8f3SLinus Torvalds { 164745bce8f3SLinus Torvalds return ilog2(blocksize); 164845bce8f3SLinus Torvalds } 164945bce8f3SLinus Torvalds 165045bce8f3SLinus Torvalds static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state) 165145bce8f3SLinus Torvalds { 165245bce8f3SLinus Torvalds BUG_ON(!PageLocked(page)); 165345bce8f3SLinus Torvalds 165445bce8f3SLinus Torvalds if (!page_has_buffers(page)) 165545bce8f3SLinus Torvalds create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state); 165645bce8f3SLinus Torvalds return page_buffers(page); 165745bce8f3SLinus Torvalds } 165845bce8f3SLinus Torvalds 165945bce8f3SLinus Torvalds /* 16601da177e4SLinus Torvalds * NOTE! All mapped/uptodate combinations are valid: 16611da177e4SLinus Torvalds * 16621da177e4SLinus Torvalds * Mapped Uptodate Meaning 16631da177e4SLinus Torvalds * 16641da177e4SLinus Torvalds * No No "unknown" - must do get_block() 16651da177e4SLinus Torvalds * No Yes "hole" - zero-filled 16661da177e4SLinus Torvalds * Yes No "allocated" - allocated on disk, not read in 16671da177e4SLinus Torvalds * Yes Yes "valid" - allocated and up-to-date in memory. 16681da177e4SLinus Torvalds * 16691da177e4SLinus Torvalds * "Dirty" is valid only with the last case (mapped+uptodate). 16701da177e4SLinus Torvalds */ 16711da177e4SLinus Torvalds 16721da177e4SLinus Torvalds /* 16731da177e4SLinus Torvalds * While block_write_full_page is writing back the dirty buffers under 16741da177e4SLinus Torvalds * the page lock, whoever dirtied the buffers may decide to clean them 16751da177e4SLinus Torvalds * again at any time. We handle that by only looking at the buffer 16761da177e4SLinus Torvalds * state inside lock_buffer(). 16771da177e4SLinus Torvalds * 16781da177e4SLinus Torvalds * If block_write_full_page() is called for regular writeback 16791da177e4SLinus Torvalds * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a 16801da177e4SLinus Torvalds * locked buffer. This only can happen if someone has written the buffer 16811da177e4SLinus Torvalds * directly, with submit_bh(). At the address_space level PageWriteback 16821da177e4SLinus Torvalds * prevents this contention from occurring. 16836e34eeddSTheodore Ts'o * 16846e34eeddSTheodore Ts'o * If block_write_full_page() is called with wbc->sync_mode == 1685721a9602SJens Axboe * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this 1686721a9602SJens Axboe * causes the writes to be flagged as synchronous writes. 16871da177e4SLinus Torvalds */ 16881da177e4SLinus Torvalds static int __block_write_full_page(struct inode *inode, struct page *page, 168935c80d5fSChris Mason get_block_t *get_block, struct writeback_control *wbc, 169035c80d5fSChris Mason bh_end_io_t *handler) 16911da177e4SLinus Torvalds { 16921da177e4SLinus Torvalds int err; 16931da177e4SLinus Torvalds sector_t block; 16941da177e4SLinus Torvalds sector_t last_block; 1695f0fbd5fcSAndrew Morton struct buffer_head *bh, *head; 169645bce8f3SLinus Torvalds unsigned int blocksize, bbits; 16971da177e4SLinus Torvalds int nr_underway = 0; 16986e34eeddSTheodore Ts'o int write_op = (wbc->sync_mode == WB_SYNC_ALL ? 1699721a9602SJens Axboe WRITE_SYNC : WRITE); 17001da177e4SLinus Torvalds 170145bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 17021da177e4SLinus Torvalds (1 << BH_Dirty)|(1 << BH_Uptodate)); 17031da177e4SLinus Torvalds 17041da177e4SLinus Torvalds /* 17051da177e4SLinus Torvalds * Be very careful. We have no exclusion from __set_page_dirty_buffers 17061da177e4SLinus Torvalds * here, and the (potentially unmapped) buffers may become dirty at 17071da177e4SLinus Torvalds * any time. If a buffer becomes dirty here after we've inspected it 17081da177e4SLinus Torvalds * then we just miss that fact, and the page stays dirty. 17091da177e4SLinus Torvalds * 17101da177e4SLinus Torvalds * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; 17111da177e4SLinus Torvalds * handle that here by just cleaning them. 17121da177e4SLinus Torvalds */ 17131da177e4SLinus Torvalds 17141da177e4SLinus Torvalds bh = head; 171545bce8f3SLinus Torvalds blocksize = bh->b_size; 171645bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 171745bce8f3SLinus Torvalds 171845bce8f3SLinus Torvalds block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 171945bce8f3SLinus Torvalds last_block = (i_size_read(inode) - 1) >> bbits; 17201da177e4SLinus Torvalds 17211da177e4SLinus Torvalds /* 17221da177e4SLinus Torvalds * Get all the dirty buffers mapped to disk addresses and 17231da177e4SLinus Torvalds * handle any aliases from the underlying blockdev's mapping. 17241da177e4SLinus Torvalds */ 17251da177e4SLinus Torvalds do { 17261da177e4SLinus Torvalds if (block > last_block) { 17271da177e4SLinus Torvalds /* 17281da177e4SLinus Torvalds * mapped buffers outside i_size will occur, because 17291da177e4SLinus Torvalds * this page can be outside i_size when there is a 17301da177e4SLinus Torvalds * truncate in progress. 17311da177e4SLinus Torvalds */ 17321da177e4SLinus Torvalds /* 17331da177e4SLinus Torvalds * The buffer was zeroed by block_write_full_page() 17341da177e4SLinus Torvalds */ 17351da177e4SLinus Torvalds clear_buffer_dirty(bh); 17361da177e4SLinus Torvalds set_buffer_uptodate(bh); 173729a814d2SAlex Tomas } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && 173829a814d2SAlex Tomas buffer_dirty(bh)) { 1739b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 17401da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 17411da177e4SLinus Torvalds if (err) 17421da177e4SLinus Torvalds goto recover; 174329a814d2SAlex Tomas clear_buffer_delay(bh); 17441da177e4SLinus Torvalds if (buffer_new(bh)) { 17451da177e4SLinus Torvalds /* blockdev mappings never come here */ 17461da177e4SLinus Torvalds clear_buffer_new(bh); 17471da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 17481da177e4SLinus Torvalds bh->b_blocknr); 17491da177e4SLinus Torvalds } 17501da177e4SLinus Torvalds } 17511da177e4SLinus Torvalds bh = bh->b_this_page; 17521da177e4SLinus Torvalds block++; 17531da177e4SLinus Torvalds } while (bh != head); 17541da177e4SLinus Torvalds 17551da177e4SLinus Torvalds do { 17561da177e4SLinus Torvalds if (!buffer_mapped(bh)) 17571da177e4SLinus Torvalds continue; 17581da177e4SLinus Torvalds /* 17591da177e4SLinus Torvalds * If it's a fully non-blocking write attempt and we cannot 17601da177e4SLinus Torvalds * lock the buffer then redirty the page. Note that this can 17615b0830cbSJens Axboe * potentially cause a busy-wait loop from writeback threads 17625b0830cbSJens Axboe * and kswapd activity, but those code paths have their own 17635b0830cbSJens Axboe * higher-level throttling. 17641da177e4SLinus Torvalds */ 17651b430beeSWu Fengguang if (wbc->sync_mode != WB_SYNC_NONE) { 17661da177e4SLinus Torvalds lock_buffer(bh); 1767ca5de404SNick Piggin } else if (!trylock_buffer(bh)) { 17681da177e4SLinus Torvalds redirty_page_for_writepage(wbc, page); 17691da177e4SLinus Torvalds continue; 17701da177e4SLinus Torvalds } 17711da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 177235c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 17731da177e4SLinus Torvalds } else { 17741da177e4SLinus Torvalds unlock_buffer(bh); 17751da177e4SLinus Torvalds } 17761da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17771da177e4SLinus Torvalds 17781da177e4SLinus Torvalds /* 17791da177e4SLinus Torvalds * The page and its buffers are protected by PageWriteback(), so we can 17801da177e4SLinus Torvalds * drop the bh refcounts early. 17811da177e4SLinus Torvalds */ 17821da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17831da177e4SLinus Torvalds set_page_writeback(page); 17841da177e4SLinus Torvalds 17851da177e4SLinus Torvalds do { 17861da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17871da177e4SLinus Torvalds if (buffer_async_write(bh)) { 1788a64c8610STheodore Ts'o submit_bh(write_op, bh); 17891da177e4SLinus Torvalds nr_underway++; 1790ad576e63SNick Piggin } 17911da177e4SLinus Torvalds bh = next; 17921da177e4SLinus Torvalds } while (bh != head); 179305937baaSAndrew Morton unlock_page(page); 17941da177e4SLinus Torvalds 17951da177e4SLinus Torvalds err = 0; 17961da177e4SLinus Torvalds done: 17971da177e4SLinus Torvalds if (nr_underway == 0) { 17981da177e4SLinus Torvalds /* 17991da177e4SLinus Torvalds * The page was marked dirty, but the buffers were 18001da177e4SLinus Torvalds * clean. Someone wrote them back by hand with 18011da177e4SLinus Torvalds * ll_rw_block/submit_bh. A rare case. 18021da177e4SLinus Torvalds */ 18031da177e4SLinus Torvalds end_page_writeback(page); 18043d67f2d7SNick Piggin 18051da177e4SLinus Torvalds /* 18061da177e4SLinus Torvalds * The page and buffer_heads can be released at any time from 18071da177e4SLinus Torvalds * here on. 18081da177e4SLinus Torvalds */ 18091da177e4SLinus Torvalds } 18101da177e4SLinus Torvalds return err; 18111da177e4SLinus Torvalds 18121da177e4SLinus Torvalds recover: 18131da177e4SLinus Torvalds /* 18141da177e4SLinus Torvalds * ENOSPC, or some other error. We may already have added some 18151da177e4SLinus Torvalds * blocks to the file, so we need to write these out to avoid 18161da177e4SLinus Torvalds * exposing stale data. 18171da177e4SLinus Torvalds * The page is currently locked and not marked for writeback 18181da177e4SLinus Torvalds */ 18191da177e4SLinus Torvalds bh = head; 18201da177e4SLinus Torvalds /* Recovery: lock and submit the mapped buffers */ 18211da177e4SLinus Torvalds do { 182229a814d2SAlex Tomas if (buffer_mapped(bh) && buffer_dirty(bh) && 182329a814d2SAlex Tomas !buffer_delay(bh)) { 18241da177e4SLinus Torvalds lock_buffer(bh); 182535c80d5fSChris Mason mark_buffer_async_write_endio(bh, handler); 18261da177e4SLinus Torvalds } else { 18271da177e4SLinus Torvalds /* 18281da177e4SLinus Torvalds * The buffer may have been set dirty during 18291da177e4SLinus Torvalds * attachment to a dirty page. 18301da177e4SLinus Torvalds */ 18311da177e4SLinus Torvalds clear_buffer_dirty(bh); 18321da177e4SLinus Torvalds } 18331da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 18341da177e4SLinus Torvalds SetPageError(page); 18351da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 18367e4c3690SAndrew Morton mapping_set_error(page->mapping, err); 18371da177e4SLinus Torvalds set_page_writeback(page); 18381da177e4SLinus Torvalds do { 18391da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 18401da177e4SLinus Torvalds if (buffer_async_write(bh)) { 18411da177e4SLinus Torvalds clear_buffer_dirty(bh); 1842a64c8610STheodore Ts'o submit_bh(write_op, bh); 18431da177e4SLinus Torvalds nr_underway++; 1844ad576e63SNick Piggin } 18451da177e4SLinus Torvalds bh = next; 18461da177e4SLinus Torvalds } while (bh != head); 1847ffda9d30SNick Piggin unlock_page(page); 18481da177e4SLinus Torvalds goto done; 18491da177e4SLinus Torvalds } 18501da177e4SLinus Torvalds 1851afddba49SNick Piggin /* 1852afddba49SNick Piggin * If a page has any new buffers, zero them out here, and mark them uptodate 1853afddba49SNick Piggin * and dirty so they'll be written out (in order to prevent uninitialised 1854afddba49SNick Piggin * block data from leaking). And clear the new bit. 1855afddba49SNick Piggin */ 1856afddba49SNick Piggin void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) 1857afddba49SNick Piggin { 1858afddba49SNick Piggin unsigned int block_start, block_end; 1859afddba49SNick Piggin struct buffer_head *head, *bh; 1860afddba49SNick Piggin 1861afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1862afddba49SNick Piggin if (!page_has_buffers(page)) 1863afddba49SNick Piggin return; 1864afddba49SNick Piggin 1865afddba49SNick Piggin bh = head = page_buffers(page); 1866afddba49SNick Piggin block_start = 0; 1867afddba49SNick Piggin do { 1868afddba49SNick Piggin block_end = block_start + bh->b_size; 1869afddba49SNick Piggin 1870afddba49SNick Piggin if (buffer_new(bh)) { 1871afddba49SNick Piggin if (block_end > from && block_start < to) { 1872afddba49SNick Piggin if (!PageUptodate(page)) { 1873afddba49SNick Piggin unsigned start, size; 1874afddba49SNick Piggin 1875afddba49SNick Piggin start = max(from, block_start); 1876afddba49SNick Piggin size = min(to, block_end) - start; 1877afddba49SNick Piggin 1878eebd2aa3SChristoph Lameter zero_user(page, start, size); 1879afddba49SNick Piggin set_buffer_uptodate(bh); 1880afddba49SNick Piggin } 1881afddba49SNick Piggin 1882afddba49SNick Piggin clear_buffer_new(bh); 1883afddba49SNick Piggin mark_buffer_dirty(bh); 1884afddba49SNick Piggin } 1885afddba49SNick Piggin } 1886afddba49SNick Piggin 1887afddba49SNick Piggin block_start = block_end; 1888afddba49SNick Piggin bh = bh->b_this_page; 1889afddba49SNick Piggin } while (bh != head); 1890afddba49SNick Piggin } 1891afddba49SNick Piggin EXPORT_SYMBOL(page_zero_new_buffers); 1892afddba49SNick Piggin 1893ebdec241SChristoph Hellwig int __block_write_begin(struct page *page, loff_t pos, unsigned len, 18946e1db88dSChristoph Hellwig get_block_t *get_block) 18951da177e4SLinus Torvalds { 1896ebdec241SChristoph Hellwig unsigned from = pos & (PAGE_CACHE_SIZE - 1); 1897ebdec241SChristoph Hellwig unsigned to = from + len; 18986e1db88dSChristoph Hellwig struct inode *inode = page->mapping->host; 18991da177e4SLinus Torvalds unsigned block_start, block_end; 19001da177e4SLinus Torvalds sector_t block; 19011da177e4SLinus Torvalds int err = 0; 19021da177e4SLinus Torvalds unsigned blocksize, bbits; 19031da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 19041da177e4SLinus Torvalds 19051da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 19061da177e4SLinus Torvalds BUG_ON(from > PAGE_CACHE_SIZE); 19071da177e4SLinus Torvalds BUG_ON(to > PAGE_CACHE_SIZE); 19081da177e4SLinus Torvalds BUG_ON(from > to); 19091da177e4SLinus Torvalds 191045bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 191145bce8f3SLinus Torvalds blocksize = head->b_size; 191245bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 19131da177e4SLinus Torvalds 19141da177e4SLinus Torvalds block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 19151da177e4SLinus Torvalds 19161da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 19171da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 19181da177e4SLinus Torvalds block_end = block_start + blocksize; 19191da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19201da177e4SLinus Torvalds if (PageUptodate(page)) { 19211da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19221da177e4SLinus Torvalds set_buffer_uptodate(bh); 19231da177e4SLinus Torvalds } 19241da177e4SLinus Torvalds continue; 19251da177e4SLinus Torvalds } 19261da177e4SLinus Torvalds if (buffer_new(bh)) 19271da177e4SLinus Torvalds clear_buffer_new(bh); 19281da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 1929b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 19301da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 19311da177e4SLinus Torvalds if (err) 1932f3ddbdc6SNick Piggin break; 19331da177e4SLinus Torvalds if (buffer_new(bh)) { 19341da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 19351da177e4SLinus Torvalds bh->b_blocknr); 19361da177e4SLinus Torvalds if (PageUptodate(page)) { 1937637aff46SNick Piggin clear_buffer_new(bh); 19381da177e4SLinus Torvalds set_buffer_uptodate(bh); 1939637aff46SNick Piggin mark_buffer_dirty(bh); 19401da177e4SLinus Torvalds continue; 19411da177e4SLinus Torvalds } 1942eebd2aa3SChristoph Lameter if (block_end > to || block_start < from) 1943eebd2aa3SChristoph Lameter zero_user_segments(page, 1944eebd2aa3SChristoph Lameter to, block_end, 1945eebd2aa3SChristoph Lameter block_start, from); 19461da177e4SLinus Torvalds continue; 19471da177e4SLinus Torvalds } 19481da177e4SLinus Torvalds } 19491da177e4SLinus Torvalds if (PageUptodate(page)) { 19501da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19511da177e4SLinus Torvalds set_buffer_uptodate(bh); 19521da177e4SLinus Torvalds continue; 19531da177e4SLinus Torvalds } 19541da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 195533a266ddSDavid Chinner !buffer_unwritten(bh) && 19561da177e4SLinus Torvalds (block_start < from || block_end > to)) { 19571da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 19581da177e4SLinus Torvalds *wait_bh++=bh; 19591da177e4SLinus Torvalds } 19601da177e4SLinus Torvalds } 19611da177e4SLinus Torvalds /* 19621da177e4SLinus Torvalds * If we issued read requests - let them complete. 19631da177e4SLinus Torvalds */ 19641da177e4SLinus Torvalds while(wait_bh > wait) { 19651da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 19661da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 1967f3ddbdc6SNick Piggin err = -EIO; 19681da177e4SLinus Torvalds } 1969f9f07b6cSJan Kara if (unlikely(err)) 1970afddba49SNick Piggin page_zero_new_buffers(page, from, to); 19711da177e4SLinus Torvalds return err; 19721da177e4SLinus Torvalds } 1973ebdec241SChristoph Hellwig EXPORT_SYMBOL(__block_write_begin); 19741da177e4SLinus Torvalds 19751da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 19761da177e4SLinus Torvalds unsigned from, unsigned to) 19771da177e4SLinus Torvalds { 19781da177e4SLinus Torvalds unsigned block_start, block_end; 19791da177e4SLinus Torvalds int partial = 0; 19801da177e4SLinus Torvalds unsigned blocksize; 19811da177e4SLinus Torvalds struct buffer_head *bh, *head; 19821da177e4SLinus Torvalds 198345bce8f3SLinus Torvalds bh = head = page_buffers(page); 198445bce8f3SLinus Torvalds blocksize = bh->b_size; 19851da177e4SLinus Torvalds 198645bce8f3SLinus Torvalds block_start = 0; 198745bce8f3SLinus Torvalds do { 19881da177e4SLinus Torvalds block_end = block_start + blocksize; 19891da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19901da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19911da177e4SLinus Torvalds partial = 1; 19921da177e4SLinus Torvalds } else { 19931da177e4SLinus Torvalds set_buffer_uptodate(bh); 19941da177e4SLinus Torvalds mark_buffer_dirty(bh); 19951da177e4SLinus Torvalds } 1996afddba49SNick Piggin clear_buffer_new(bh); 199745bce8f3SLinus Torvalds 199845bce8f3SLinus Torvalds block_start = block_end; 199945bce8f3SLinus Torvalds bh = bh->b_this_page; 200045bce8f3SLinus Torvalds } while (bh != head); 20011da177e4SLinus Torvalds 20021da177e4SLinus Torvalds /* 20031da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 20041da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 20051da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 20061da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 20071da177e4SLinus Torvalds */ 20081da177e4SLinus Torvalds if (!partial) 20091da177e4SLinus Torvalds SetPageUptodate(page); 20101da177e4SLinus Torvalds return 0; 20111da177e4SLinus Torvalds } 20121da177e4SLinus Torvalds 20131da177e4SLinus Torvalds /* 2014155130a4SChristoph Hellwig * block_write_begin takes care of the basic task of block allocation and 2015155130a4SChristoph Hellwig * bringing partial write blocks uptodate first. 2016155130a4SChristoph Hellwig * 20177bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 2018afddba49SNick Piggin */ 2019155130a4SChristoph Hellwig int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, 2020155130a4SChristoph Hellwig unsigned flags, struct page **pagep, get_block_t *get_block) 2021afddba49SNick Piggin { 20226e1db88dSChristoph Hellwig pgoff_t index = pos >> PAGE_CACHE_SHIFT; 2023afddba49SNick Piggin struct page *page; 20246e1db88dSChristoph Hellwig int status; 2025afddba49SNick Piggin 202654566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 20276e1db88dSChristoph Hellwig if (!page) 20286e1db88dSChristoph Hellwig return -ENOMEM; 2029afddba49SNick Piggin 20306e1db88dSChristoph Hellwig status = __block_write_begin(page, pos, len, get_block); 2031afddba49SNick Piggin if (unlikely(status)) { 2032afddba49SNick Piggin unlock_page(page); 2033afddba49SNick Piggin page_cache_release(page); 20346e1db88dSChristoph Hellwig page = NULL; 2035afddba49SNick Piggin } 2036afddba49SNick Piggin 20376e1db88dSChristoph Hellwig *pagep = page; 2038afddba49SNick Piggin return status; 2039afddba49SNick Piggin } 2040afddba49SNick Piggin EXPORT_SYMBOL(block_write_begin); 2041afddba49SNick Piggin 2042afddba49SNick Piggin int block_write_end(struct file *file, struct address_space *mapping, 2043afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2044afddba49SNick Piggin struct page *page, void *fsdata) 2045afddba49SNick Piggin { 2046afddba49SNick Piggin struct inode *inode = mapping->host; 2047afddba49SNick Piggin unsigned start; 2048afddba49SNick Piggin 2049afddba49SNick Piggin start = pos & (PAGE_CACHE_SIZE - 1); 2050afddba49SNick Piggin 2051afddba49SNick Piggin if (unlikely(copied < len)) { 2052afddba49SNick Piggin /* 2053afddba49SNick Piggin * The buffers that were written will now be uptodate, so we 2054afddba49SNick Piggin * don't have to worry about a readpage reading them and 2055afddba49SNick Piggin * overwriting a partial write. However if we have encountered 2056afddba49SNick Piggin * a short write and only partially written into a buffer, it 2057afddba49SNick Piggin * will not be marked uptodate, so a readpage might come in and 2058afddba49SNick Piggin * destroy our partial write. 2059afddba49SNick Piggin * 2060afddba49SNick Piggin * Do the simplest thing, and just treat any short write to a 2061afddba49SNick Piggin * non uptodate page as a zero-length write, and force the 2062afddba49SNick Piggin * caller to redo the whole thing. 2063afddba49SNick Piggin */ 2064afddba49SNick Piggin if (!PageUptodate(page)) 2065afddba49SNick Piggin copied = 0; 2066afddba49SNick Piggin 2067afddba49SNick Piggin page_zero_new_buffers(page, start+copied, start+len); 2068afddba49SNick Piggin } 2069afddba49SNick Piggin flush_dcache_page(page); 2070afddba49SNick Piggin 2071afddba49SNick Piggin /* This could be a short (even 0-length) commit */ 2072afddba49SNick Piggin __block_commit_write(inode, page, start, start+copied); 2073afddba49SNick Piggin 2074afddba49SNick Piggin return copied; 2075afddba49SNick Piggin } 2076afddba49SNick Piggin EXPORT_SYMBOL(block_write_end); 2077afddba49SNick Piggin 2078afddba49SNick Piggin int generic_write_end(struct file *file, struct address_space *mapping, 2079afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2080afddba49SNick Piggin struct page *page, void *fsdata) 2081afddba49SNick Piggin { 2082afddba49SNick Piggin struct inode *inode = mapping->host; 2083c7d206b3SJan Kara int i_size_changed = 0; 2084afddba49SNick Piggin 2085afddba49SNick Piggin copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); 2086afddba49SNick Piggin 2087afddba49SNick Piggin /* 2088afddba49SNick Piggin * No need to use i_size_read() here, the i_size 2089afddba49SNick Piggin * cannot change under us because we hold i_mutex. 2090afddba49SNick Piggin * 2091afddba49SNick Piggin * But it's important to update i_size while still holding page lock: 2092afddba49SNick Piggin * page writeout could otherwise come in and zero beyond i_size. 2093afddba49SNick Piggin */ 2094afddba49SNick Piggin if (pos+copied > inode->i_size) { 2095afddba49SNick Piggin i_size_write(inode, pos+copied); 2096c7d206b3SJan Kara i_size_changed = 1; 2097afddba49SNick Piggin } 2098afddba49SNick Piggin 2099afddba49SNick Piggin unlock_page(page); 2100afddba49SNick Piggin page_cache_release(page); 2101afddba49SNick Piggin 2102c7d206b3SJan Kara /* 2103c7d206b3SJan Kara * Don't mark the inode dirty under page lock. First, it unnecessarily 2104c7d206b3SJan Kara * makes the holding time of page lock longer. Second, it forces lock 2105c7d206b3SJan Kara * ordering of page lock and transaction start for journaling 2106c7d206b3SJan Kara * filesystems. 2107c7d206b3SJan Kara */ 2108c7d206b3SJan Kara if (i_size_changed) 2109c7d206b3SJan Kara mark_inode_dirty(inode); 2110c7d206b3SJan Kara 2111afddba49SNick Piggin return copied; 2112afddba49SNick Piggin } 2113afddba49SNick Piggin EXPORT_SYMBOL(generic_write_end); 2114afddba49SNick Piggin 2115afddba49SNick Piggin /* 21168ab22b9aSHisashi Hifumi * block_is_partially_uptodate checks whether buffers within a page are 21178ab22b9aSHisashi Hifumi * uptodate or not. 21188ab22b9aSHisashi Hifumi * 21198ab22b9aSHisashi Hifumi * Returns true if all buffers which correspond to a file portion 21208ab22b9aSHisashi Hifumi * we want to read are uptodate. 21218ab22b9aSHisashi Hifumi */ 2122c186afb4SAl Viro int block_is_partially_uptodate(struct page *page, unsigned long from, 2123c186afb4SAl Viro unsigned long count) 21248ab22b9aSHisashi Hifumi { 21258ab22b9aSHisashi Hifumi unsigned block_start, block_end, blocksize; 21268ab22b9aSHisashi Hifumi unsigned to; 21278ab22b9aSHisashi Hifumi struct buffer_head *bh, *head; 21288ab22b9aSHisashi Hifumi int ret = 1; 21298ab22b9aSHisashi Hifumi 21308ab22b9aSHisashi Hifumi if (!page_has_buffers(page)) 21318ab22b9aSHisashi Hifumi return 0; 21328ab22b9aSHisashi Hifumi 213345bce8f3SLinus Torvalds head = page_buffers(page); 213445bce8f3SLinus Torvalds blocksize = head->b_size; 2135c186afb4SAl Viro to = min_t(unsigned, PAGE_CACHE_SIZE - from, count); 21368ab22b9aSHisashi Hifumi to = from + to; 21378ab22b9aSHisashi Hifumi if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize) 21388ab22b9aSHisashi Hifumi return 0; 21398ab22b9aSHisashi Hifumi 21408ab22b9aSHisashi Hifumi bh = head; 21418ab22b9aSHisashi Hifumi block_start = 0; 21428ab22b9aSHisashi Hifumi do { 21438ab22b9aSHisashi Hifumi block_end = block_start + blocksize; 21448ab22b9aSHisashi Hifumi if (block_end > from && block_start < to) { 21458ab22b9aSHisashi Hifumi if (!buffer_uptodate(bh)) { 21468ab22b9aSHisashi Hifumi ret = 0; 21478ab22b9aSHisashi Hifumi break; 21488ab22b9aSHisashi Hifumi } 21498ab22b9aSHisashi Hifumi if (block_end >= to) 21508ab22b9aSHisashi Hifumi break; 21518ab22b9aSHisashi Hifumi } 21528ab22b9aSHisashi Hifumi block_start = block_end; 21538ab22b9aSHisashi Hifumi bh = bh->b_this_page; 21548ab22b9aSHisashi Hifumi } while (bh != head); 21558ab22b9aSHisashi Hifumi 21568ab22b9aSHisashi Hifumi return ret; 21578ab22b9aSHisashi Hifumi } 21588ab22b9aSHisashi Hifumi EXPORT_SYMBOL(block_is_partially_uptodate); 21598ab22b9aSHisashi Hifumi 21608ab22b9aSHisashi Hifumi /* 21611da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 21621da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 21631da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 21641da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 21651da177e4SLinus Torvalds * page struct once IO has completed. 21661da177e4SLinus Torvalds */ 21671da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 21681da177e4SLinus Torvalds { 21691da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 21701da177e4SLinus Torvalds sector_t iblock, lblock; 21711da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 217245bce8f3SLinus Torvalds unsigned int blocksize, bbits; 21731da177e4SLinus Torvalds int nr, i; 21741da177e4SLinus Torvalds int fully_mapped = 1; 21751da177e4SLinus Torvalds 217645bce8f3SLinus Torvalds head = create_page_buffers(page, inode, 0); 217745bce8f3SLinus Torvalds blocksize = head->b_size; 217845bce8f3SLinus Torvalds bbits = block_size_bits(blocksize); 21791da177e4SLinus Torvalds 218045bce8f3SLinus Torvalds iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 218145bce8f3SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> bbits; 21821da177e4SLinus Torvalds bh = head; 21831da177e4SLinus Torvalds nr = 0; 21841da177e4SLinus Torvalds i = 0; 21851da177e4SLinus Torvalds 21861da177e4SLinus Torvalds do { 21871da177e4SLinus Torvalds if (buffer_uptodate(bh)) 21881da177e4SLinus Torvalds continue; 21891da177e4SLinus Torvalds 21901da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2191c64610baSAndrew Morton int err = 0; 2192c64610baSAndrew Morton 21931da177e4SLinus Torvalds fully_mapped = 0; 21941da177e4SLinus Torvalds if (iblock < lblock) { 2195b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 2196c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 2197c64610baSAndrew Morton if (err) 21981da177e4SLinus Torvalds SetPageError(page); 21991da177e4SLinus Torvalds } 22001da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2201eebd2aa3SChristoph Lameter zero_user(page, i * blocksize, blocksize); 2202c64610baSAndrew Morton if (!err) 22031da177e4SLinus Torvalds set_buffer_uptodate(bh); 22041da177e4SLinus Torvalds continue; 22051da177e4SLinus Torvalds } 22061da177e4SLinus Torvalds /* 22071da177e4SLinus Torvalds * get_block() might have updated the buffer 22081da177e4SLinus Torvalds * synchronously 22091da177e4SLinus Torvalds */ 22101da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22111da177e4SLinus Torvalds continue; 22121da177e4SLinus Torvalds } 22131da177e4SLinus Torvalds arr[nr++] = bh; 22141da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 22151da177e4SLinus Torvalds 22161da177e4SLinus Torvalds if (fully_mapped) 22171da177e4SLinus Torvalds SetPageMappedToDisk(page); 22181da177e4SLinus Torvalds 22191da177e4SLinus Torvalds if (!nr) { 22201da177e4SLinus Torvalds /* 22211da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 22221da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 22231da177e4SLinus Torvalds */ 22241da177e4SLinus Torvalds if (!PageError(page)) 22251da177e4SLinus Torvalds SetPageUptodate(page); 22261da177e4SLinus Torvalds unlock_page(page); 22271da177e4SLinus Torvalds return 0; 22281da177e4SLinus Torvalds } 22291da177e4SLinus Torvalds 22301da177e4SLinus Torvalds /* Stage two: lock the buffers */ 22311da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22321da177e4SLinus Torvalds bh = arr[i]; 22331da177e4SLinus Torvalds lock_buffer(bh); 22341da177e4SLinus Torvalds mark_buffer_async_read(bh); 22351da177e4SLinus Torvalds } 22361da177e4SLinus Torvalds 22371da177e4SLinus Torvalds /* 22381da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 22391da177e4SLinus Torvalds * inside the buffer lock in case another process reading 22401da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 22411da177e4SLinus Torvalds */ 22421da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 22431da177e4SLinus Torvalds bh = arr[i]; 22441da177e4SLinus Torvalds if (buffer_uptodate(bh)) 22451da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 22461da177e4SLinus Torvalds else 22471da177e4SLinus Torvalds submit_bh(READ, bh); 22481da177e4SLinus Torvalds } 22491da177e4SLinus Torvalds return 0; 22501da177e4SLinus Torvalds } 22511fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_read_full_page); 22521da177e4SLinus Torvalds 22531da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 225489e10787SNick Piggin * truncates. Uses filesystem pagecache writes to allow the filesystem to 22551da177e4SLinus Torvalds * deal with the hole. 22561da177e4SLinus Torvalds */ 225789e10787SNick Piggin int generic_cont_expand_simple(struct inode *inode, loff_t size) 22581da177e4SLinus Torvalds { 22591da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 22601da177e4SLinus Torvalds struct page *page; 226189e10787SNick Piggin void *fsdata; 22621da177e4SLinus Torvalds int err; 22631da177e4SLinus Torvalds 2264c08d3b0eSnpiggin@suse.de err = inode_newsize_ok(inode, size); 2265c08d3b0eSnpiggin@suse.de if (err) 22661da177e4SLinus Torvalds goto out; 22671da177e4SLinus Torvalds 226889e10787SNick Piggin err = pagecache_write_begin(NULL, mapping, size, 0, 226989e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, 227089e10787SNick Piggin &page, &fsdata); 227189e10787SNick Piggin if (err) 227205eb0b51SOGAWA Hirofumi goto out; 227305eb0b51SOGAWA Hirofumi 227489e10787SNick Piggin err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); 227589e10787SNick Piggin BUG_ON(err > 0); 227605eb0b51SOGAWA Hirofumi 227705eb0b51SOGAWA Hirofumi out: 227805eb0b51SOGAWA Hirofumi return err; 227905eb0b51SOGAWA Hirofumi } 22801fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_cont_expand_simple); 228105eb0b51SOGAWA Hirofumi 2282f1e3af72SAdrian Bunk static int cont_expand_zero(struct file *file, struct address_space *mapping, 228389e10787SNick Piggin loff_t pos, loff_t *bytes) 228405eb0b51SOGAWA Hirofumi { 228589e10787SNick Piggin struct inode *inode = mapping->host; 228689e10787SNick Piggin unsigned blocksize = 1 << inode->i_blkbits; 228789e10787SNick Piggin struct page *page; 228889e10787SNick Piggin void *fsdata; 228989e10787SNick Piggin pgoff_t index, curidx; 229089e10787SNick Piggin loff_t curpos; 229189e10787SNick Piggin unsigned zerofrom, offset, len; 229289e10787SNick Piggin int err = 0; 229305eb0b51SOGAWA Hirofumi 229489e10787SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 229589e10787SNick Piggin offset = pos & ~PAGE_CACHE_MASK; 229689e10787SNick Piggin 229789e10787SNick Piggin while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) { 229889e10787SNick Piggin zerofrom = curpos & ~PAGE_CACHE_MASK; 229989e10787SNick Piggin if (zerofrom & (blocksize-1)) { 230089e10787SNick Piggin *bytes |= (blocksize-1); 230189e10787SNick Piggin (*bytes)++; 230289e10787SNick Piggin } 230389e10787SNick Piggin len = PAGE_CACHE_SIZE - zerofrom; 230489e10787SNick Piggin 230589e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 230689e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 230789e10787SNick Piggin &page, &fsdata); 230889e10787SNick Piggin if (err) 230989e10787SNick Piggin goto out; 2310eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 231189e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 231289e10787SNick Piggin page, fsdata); 231389e10787SNick Piggin if (err < 0) 231489e10787SNick Piggin goto out; 231589e10787SNick Piggin BUG_ON(err != len); 231689e10787SNick Piggin err = 0; 2317061e9746SOGAWA Hirofumi 2318061e9746SOGAWA Hirofumi balance_dirty_pages_ratelimited(mapping); 231989e10787SNick Piggin } 232089e10787SNick Piggin 232189e10787SNick Piggin /* page covers the boundary, find the boundary offset */ 232289e10787SNick Piggin if (index == curidx) { 232389e10787SNick Piggin zerofrom = curpos & ~PAGE_CACHE_MASK; 232489e10787SNick Piggin /* if we will expand the thing last block will be filled */ 232589e10787SNick Piggin if (offset <= zerofrom) { 232689e10787SNick Piggin goto out; 232789e10787SNick Piggin } 232889e10787SNick Piggin if (zerofrom & (blocksize-1)) { 232989e10787SNick Piggin *bytes |= (blocksize-1); 233089e10787SNick Piggin (*bytes)++; 233189e10787SNick Piggin } 233289e10787SNick Piggin len = offset - zerofrom; 233389e10787SNick Piggin 233489e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 233589e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 233689e10787SNick Piggin &page, &fsdata); 233789e10787SNick Piggin if (err) 233889e10787SNick Piggin goto out; 2339eebd2aa3SChristoph Lameter zero_user(page, zerofrom, len); 234089e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 234189e10787SNick Piggin page, fsdata); 234289e10787SNick Piggin if (err < 0) 234389e10787SNick Piggin goto out; 234489e10787SNick Piggin BUG_ON(err != len); 234589e10787SNick Piggin err = 0; 234689e10787SNick Piggin } 234789e10787SNick Piggin out: 234889e10787SNick Piggin return err; 23491da177e4SLinus Torvalds } 23501da177e4SLinus Torvalds 23511da177e4SLinus Torvalds /* 23521da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 23531da177e4SLinus Torvalds * We may have to extend the file. 23541da177e4SLinus Torvalds */ 2355282dc178SChristoph Hellwig int cont_write_begin(struct file *file, struct address_space *mapping, 235689e10787SNick Piggin loff_t pos, unsigned len, unsigned flags, 235789e10787SNick Piggin struct page **pagep, void **fsdata, 235889e10787SNick Piggin get_block_t *get_block, loff_t *bytes) 23591da177e4SLinus Torvalds { 23601da177e4SLinus Torvalds struct inode *inode = mapping->host; 23611da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 236289e10787SNick Piggin unsigned zerofrom; 236389e10787SNick Piggin int err; 23641da177e4SLinus Torvalds 236589e10787SNick Piggin err = cont_expand_zero(file, mapping, pos, bytes); 236689e10787SNick Piggin if (err) 2367155130a4SChristoph Hellwig return err; 23681da177e4SLinus Torvalds 23691da177e4SLinus Torvalds zerofrom = *bytes & ~PAGE_CACHE_MASK; 237089e10787SNick Piggin if (pos+len > *bytes && zerofrom & (blocksize-1)) { 23711da177e4SLinus Torvalds *bytes |= (blocksize-1); 23721da177e4SLinus Torvalds (*bytes)++; 23731da177e4SLinus Torvalds } 23741da177e4SLinus Torvalds 2375155130a4SChristoph Hellwig return block_write_begin(mapping, pos, len, flags, pagep, get_block); 23761da177e4SLinus Torvalds } 23771fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(cont_write_begin); 23781da177e4SLinus Torvalds 23791da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 23801da177e4SLinus Torvalds { 23811da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23821da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 23831da177e4SLinus Torvalds return 0; 23841da177e4SLinus Torvalds } 23851fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_commit_write); 23861da177e4SLinus Torvalds 238754171690SDavid Chinner /* 238854171690SDavid Chinner * block_page_mkwrite() is not allowed to change the file size as it gets 238954171690SDavid Chinner * called from a page fault handler when a page is first dirtied. Hence we must 239054171690SDavid Chinner * be careful to check for EOF conditions here. We set the page up correctly 239154171690SDavid Chinner * for a written page which means we get ENOSPC checking when writing into 239254171690SDavid Chinner * holes and correct delalloc and unwritten extent mapping on filesystems that 239354171690SDavid Chinner * support these features. 239454171690SDavid Chinner * 239554171690SDavid Chinner * We are not allowed to take the i_mutex here so we have to play games to 239654171690SDavid Chinner * protect against truncate races as the page could now be beyond EOF. Because 23977bb46a67Snpiggin@suse.de * truncate writes the inode size before removing pages, once we have the 239854171690SDavid Chinner * page lock we can determine safely if the page is beyond EOF. If it is not 239954171690SDavid Chinner * beyond EOF, then the page is guaranteed safe against truncation until we 240054171690SDavid Chinner * unlock the page. 2401ea13a864SJan Kara * 240214da9200SJan Kara * Direct callers of this function should protect against filesystem freezing 240314da9200SJan Kara * using sb_start_write() - sb_end_write() functions. 240454171690SDavid Chinner */ 240524da4fabSJan Kara int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 240654171690SDavid Chinner get_block_t get_block) 240754171690SDavid Chinner { 2408c2ec175cSNick Piggin struct page *page = vmf->page; 2409496ad9aaSAl Viro struct inode *inode = file_inode(vma->vm_file); 241054171690SDavid Chinner unsigned long end; 241154171690SDavid Chinner loff_t size; 241224da4fabSJan Kara int ret; 241354171690SDavid Chinner 241454171690SDavid Chinner lock_page(page); 241554171690SDavid Chinner size = i_size_read(inode); 241654171690SDavid Chinner if ((page->mapping != inode->i_mapping) || 241718336338SNick Piggin (page_offset(page) > size)) { 241824da4fabSJan Kara /* We overload EFAULT to mean page got truncated */ 241924da4fabSJan Kara ret = -EFAULT; 242024da4fabSJan Kara goto out_unlock; 242154171690SDavid Chinner } 242254171690SDavid Chinner 242354171690SDavid Chinner /* page is wholly or partially inside EOF */ 242454171690SDavid Chinner if (((page->index + 1) << PAGE_CACHE_SHIFT) > size) 242554171690SDavid Chinner end = size & ~PAGE_CACHE_MASK; 242654171690SDavid Chinner else 242754171690SDavid Chinner end = PAGE_CACHE_SIZE; 242854171690SDavid Chinner 2429ebdec241SChristoph Hellwig ret = __block_write_begin(page, 0, end, get_block); 243054171690SDavid Chinner if (!ret) 243154171690SDavid Chinner ret = block_commit_write(page, 0, end); 243254171690SDavid Chinner 243324da4fabSJan Kara if (unlikely(ret < 0)) 243424da4fabSJan Kara goto out_unlock; 2435ea13a864SJan Kara set_page_dirty(page); 24361d1d1a76SDarrick J. Wong wait_for_stable_page(page); 243724da4fabSJan Kara return 0; 243824da4fabSJan Kara out_unlock: 2439b827e496SNick Piggin unlock_page(page); 244054171690SDavid Chinner return ret; 244154171690SDavid Chinner } 244224da4fabSJan Kara EXPORT_SYMBOL(__block_page_mkwrite); 244324da4fabSJan Kara 244424da4fabSJan Kara int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 244524da4fabSJan Kara get_block_t get_block) 244624da4fabSJan Kara { 2447ea13a864SJan Kara int ret; 2448496ad9aaSAl Viro struct super_block *sb = file_inode(vma->vm_file)->i_sb; 244924da4fabSJan Kara 245014da9200SJan Kara sb_start_pagefault(sb); 2451041bbb6dSTheodore Ts'o 2452041bbb6dSTheodore Ts'o /* 2453041bbb6dSTheodore Ts'o * Update file times before taking page lock. We may end up failing the 2454041bbb6dSTheodore Ts'o * fault so this update may be superfluous but who really cares... 2455041bbb6dSTheodore Ts'o */ 2456041bbb6dSTheodore Ts'o file_update_time(vma->vm_file); 2457041bbb6dSTheodore Ts'o 2458ea13a864SJan Kara ret = __block_page_mkwrite(vma, vmf, get_block); 245914da9200SJan Kara sb_end_pagefault(sb); 246024da4fabSJan Kara return block_page_mkwrite_return(ret); 246124da4fabSJan Kara } 24621fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_page_mkwrite); 24631da177e4SLinus Torvalds 24641da177e4SLinus Torvalds /* 246503158cd7SNick Piggin * nobh_write_begin()'s prereads are special: the buffer_heads are freed 24661da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 24671da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 24681da177e4SLinus Torvalds */ 24691da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 24701da177e4SLinus Torvalds { 247168671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 24721da177e4SLinus Torvalds } 24731da177e4SLinus Torvalds 24741da177e4SLinus Torvalds /* 247503158cd7SNick Piggin * Attach the singly-linked list of buffers created by nobh_write_begin, to 247603158cd7SNick Piggin * the page (converting it to circular linked list and taking care of page 247703158cd7SNick Piggin * dirty races). 247803158cd7SNick Piggin */ 247903158cd7SNick Piggin static void attach_nobh_buffers(struct page *page, struct buffer_head *head) 248003158cd7SNick Piggin { 248103158cd7SNick Piggin struct buffer_head *bh; 248203158cd7SNick Piggin 248303158cd7SNick Piggin BUG_ON(!PageLocked(page)); 248403158cd7SNick Piggin 248503158cd7SNick Piggin spin_lock(&page->mapping->private_lock); 248603158cd7SNick Piggin bh = head; 248703158cd7SNick Piggin do { 248803158cd7SNick Piggin if (PageDirty(page)) 248903158cd7SNick Piggin set_buffer_dirty(bh); 249003158cd7SNick Piggin if (!bh->b_this_page) 249103158cd7SNick Piggin bh->b_this_page = head; 249203158cd7SNick Piggin bh = bh->b_this_page; 249303158cd7SNick Piggin } while (bh != head); 249403158cd7SNick Piggin attach_page_buffers(page, head); 249503158cd7SNick Piggin spin_unlock(&page->mapping->private_lock); 249603158cd7SNick Piggin } 249703158cd7SNick Piggin 249803158cd7SNick Piggin /* 2499ea0f04e5SChristoph Hellwig * On entry, the page is fully not uptodate. 2500ea0f04e5SChristoph Hellwig * On exit the page is fully uptodate in the areas outside (from,to) 25017bb46a67Snpiggin@suse.de * The filesystem needs to handle block truncation upon failure. 25021da177e4SLinus Torvalds */ 2503ea0f04e5SChristoph Hellwig int nobh_write_begin(struct address_space *mapping, 250403158cd7SNick Piggin loff_t pos, unsigned len, unsigned flags, 250503158cd7SNick Piggin struct page **pagep, void **fsdata, 25061da177e4SLinus Torvalds get_block_t *get_block) 25071da177e4SLinus Torvalds { 250803158cd7SNick Piggin struct inode *inode = mapping->host; 25091da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 25101da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 2511a4b0672dSNick Piggin struct buffer_head *head, *bh; 251203158cd7SNick Piggin struct page *page; 251303158cd7SNick Piggin pgoff_t index; 251403158cd7SNick Piggin unsigned from, to; 25151da177e4SLinus Torvalds unsigned block_in_page; 2516a4b0672dSNick Piggin unsigned block_start, block_end; 25171da177e4SLinus Torvalds sector_t block_in_file; 25181da177e4SLinus Torvalds int nr_reads = 0; 25191da177e4SLinus Torvalds int ret = 0; 25201da177e4SLinus Torvalds int is_mapped_to_disk = 1; 25211da177e4SLinus Torvalds 252203158cd7SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 252303158cd7SNick Piggin from = pos & (PAGE_CACHE_SIZE - 1); 252403158cd7SNick Piggin to = from + len; 252503158cd7SNick Piggin 252654566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 252703158cd7SNick Piggin if (!page) 252803158cd7SNick Piggin return -ENOMEM; 252903158cd7SNick Piggin *pagep = page; 253003158cd7SNick Piggin *fsdata = NULL; 253103158cd7SNick Piggin 253203158cd7SNick Piggin if (page_has_buffers(page)) { 2533309f77adSNamhyung Kim ret = __block_write_begin(page, pos, len, get_block); 2534309f77adSNamhyung Kim if (unlikely(ret)) 2535309f77adSNamhyung Kim goto out_release; 2536309f77adSNamhyung Kim return ret; 253703158cd7SNick Piggin } 2538a4b0672dSNick Piggin 25391da177e4SLinus Torvalds if (PageMappedToDisk(page)) 25401da177e4SLinus Torvalds return 0; 25411da177e4SLinus Torvalds 2542a4b0672dSNick Piggin /* 2543a4b0672dSNick Piggin * Allocate buffers so that we can keep track of state, and potentially 2544a4b0672dSNick Piggin * attach them to the page if an error occurs. In the common case of 2545a4b0672dSNick Piggin * no error, they will just be freed again without ever being attached 2546a4b0672dSNick Piggin * to the page (which is all OK, because we're under the page lock). 2547a4b0672dSNick Piggin * 2548a4b0672dSNick Piggin * Be careful: the buffer linked list is a NULL terminated one, rather 2549a4b0672dSNick Piggin * than the circular one we're used to. 2550a4b0672dSNick Piggin */ 2551a4b0672dSNick Piggin head = alloc_page_buffers(page, blocksize, 0); 255203158cd7SNick Piggin if (!head) { 255303158cd7SNick Piggin ret = -ENOMEM; 255403158cd7SNick Piggin goto out_release; 255503158cd7SNick Piggin } 2556a4b0672dSNick Piggin 25571da177e4SLinus Torvalds block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); 25581da177e4SLinus Torvalds 25591da177e4SLinus Torvalds /* 25601da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 25611da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 25621da177e4SLinus Torvalds * page is fully mapped-to-disk. 25631da177e4SLinus Torvalds */ 2564a4b0672dSNick Piggin for (block_start = 0, block_in_page = 0, bh = head; 25651da177e4SLinus Torvalds block_start < PAGE_CACHE_SIZE; 2566a4b0672dSNick Piggin block_in_page++, block_start += blocksize, bh = bh->b_this_page) { 25671da177e4SLinus Torvalds int create; 25681da177e4SLinus Torvalds 2569a4b0672dSNick Piggin block_end = block_start + blocksize; 2570a4b0672dSNick Piggin bh->b_state = 0; 25711da177e4SLinus Torvalds create = 1; 25721da177e4SLinus Torvalds if (block_start >= to) 25731da177e4SLinus Torvalds create = 0; 25741da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 2575a4b0672dSNick Piggin bh, create); 25761da177e4SLinus Torvalds if (ret) 25771da177e4SLinus Torvalds goto failed; 2578a4b0672dSNick Piggin if (!buffer_mapped(bh)) 25791da177e4SLinus Torvalds is_mapped_to_disk = 0; 2580a4b0672dSNick Piggin if (buffer_new(bh)) 2581a4b0672dSNick Piggin unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 2582a4b0672dSNick Piggin if (PageUptodate(page)) { 2583a4b0672dSNick Piggin set_buffer_uptodate(bh); 25841da177e4SLinus Torvalds continue; 2585a4b0672dSNick Piggin } 2586a4b0672dSNick Piggin if (buffer_new(bh) || !buffer_mapped(bh)) { 2587eebd2aa3SChristoph Lameter zero_user_segments(page, block_start, from, 2588eebd2aa3SChristoph Lameter to, block_end); 25891da177e4SLinus Torvalds continue; 25901da177e4SLinus Torvalds } 2591a4b0672dSNick Piggin if (buffer_uptodate(bh)) 25921da177e4SLinus Torvalds continue; /* reiserfs does this */ 25931da177e4SLinus Torvalds if (block_start < from || block_end > to) { 2594a4b0672dSNick Piggin lock_buffer(bh); 2595a4b0672dSNick Piggin bh->b_end_io = end_buffer_read_nobh; 2596a4b0672dSNick Piggin submit_bh(READ, bh); 2597a4b0672dSNick Piggin nr_reads++; 25981da177e4SLinus Torvalds } 25991da177e4SLinus Torvalds } 26001da177e4SLinus Torvalds 26011da177e4SLinus Torvalds if (nr_reads) { 26021da177e4SLinus Torvalds /* 26031da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 26041da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 26051da177e4SLinus Torvalds * for the buffer_head refcounts. 26061da177e4SLinus Torvalds */ 2607a4b0672dSNick Piggin for (bh = head; bh; bh = bh->b_this_page) { 26081da177e4SLinus Torvalds wait_on_buffer(bh); 26091da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 26101da177e4SLinus Torvalds ret = -EIO; 26111da177e4SLinus Torvalds } 26121da177e4SLinus Torvalds if (ret) 26131da177e4SLinus Torvalds goto failed; 26141da177e4SLinus Torvalds } 26151da177e4SLinus Torvalds 26161da177e4SLinus Torvalds if (is_mapped_to_disk) 26171da177e4SLinus Torvalds SetPageMappedToDisk(page); 26181da177e4SLinus Torvalds 261903158cd7SNick Piggin *fsdata = head; /* to be released by nobh_write_end */ 2620a4b0672dSNick Piggin 26211da177e4SLinus Torvalds return 0; 26221da177e4SLinus Torvalds 26231da177e4SLinus Torvalds failed: 262403158cd7SNick Piggin BUG_ON(!ret); 26251da177e4SLinus Torvalds /* 2626a4b0672dSNick Piggin * Error recovery is a bit difficult. We need to zero out blocks that 2627a4b0672dSNick Piggin * were newly allocated, and dirty them to ensure they get written out. 2628a4b0672dSNick Piggin * Buffers need to be attached to the page at this point, otherwise 2629a4b0672dSNick Piggin * the handling of potential IO errors during writeout would be hard 2630a4b0672dSNick Piggin * (could try doing synchronous writeout, but what if that fails too?) 26311da177e4SLinus Torvalds */ 263203158cd7SNick Piggin attach_nobh_buffers(page, head); 263303158cd7SNick Piggin page_zero_new_buffers(page, from, to); 2634a4b0672dSNick Piggin 263503158cd7SNick Piggin out_release: 263603158cd7SNick Piggin unlock_page(page); 263703158cd7SNick Piggin page_cache_release(page); 263803158cd7SNick Piggin *pagep = NULL; 2639a4b0672dSNick Piggin 26407bb46a67Snpiggin@suse.de return ret; 26417bb46a67Snpiggin@suse.de } 264203158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_begin); 26431da177e4SLinus Torvalds 264403158cd7SNick Piggin int nobh_write_end(struct file *file, struct address_space *mapping, 264503158cd7SNick Piggin loff_t pos, unsigned len, unsigned copied, 264603158cd7SNick Piggin struct page *page, void *fsdata) 26471da177e4SLinus Torvalds { 26481da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 2649efdc3131SNick Piggin struct buffer_head *head = fsdata; 265003158cd7SNick Piggin struct buffer_head *bh; 26515b41e74aSDmitri Monakhov BUG_ON(fsdata != NULL && page_has_buffers(page)); 26521da177e4SLinus Torvalds 2653d4cf109fSDave Kleikamp if (unlikely(copied < len) && head) 265403158cd7SNick Piggin attach_nobh_buffers(page, head); 2655a4b0672dSNick Piggin if (page_has_buffers(page)) 265603158cd7SNick Piggin return generic_write_end(file, mapping, pos, len, 265703158cd7SNick Piggin copied, page, fsdata); 2658a4b0672dSNick Piggin 265922c8ca78SNick Piggin SetPageUptodate(page); 26601da177e4SLinus Torvalds set_page_dirty(page); 266103158cd7SNick Piggin if (pos+copied > inode->i_size) { 266203158cd7SNick Piggin i_size_write(inode, pos+copied); 26631da177e4SLinus Torvalds mark_inode_dirty(inode); 26641da177e4SLinus Torvalds } 266503158cd7SNick Piggin 266603158cd7SNick Piggin unlock_page(page); 266703158cd7SNick Piggin page_cache_release(page); 266803158cd7SNick Piggin 266903158cd7SNick Piggin while (head) { 267003158cd7SNick Piggin bh = head; 267103158cd7SNick Piggin head = head->b_this_page; 267203158cd7SNick Piggin free_buffer_head(bh); 26731da177e4SLinus Torvalds } 267403158cd7SNick Piggin 267503158cd7SNick Piggin return copied; 267603158cd7SNick Piggin } 267703158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_end); 26781da177e4SLinus Torvalds 26791da177e4SLinus Torvalds /* 26801da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 26811da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 26821da177e4SLinus Torvalds * the page. 26831da177e4SLinus Torvalds */ 26841da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 26851da177e4SLinus Torvalds struct writeback_control *wbc) 26861da177e4SLinus Torvalds { 26871da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 26881da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 26891da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 26901da177e4SLinus Torvalds unsigned offset; 26911da177e4SLinus Torvalds int ret; 26921da177e4SLinus Torvalds 26931da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 26941da177e4SLinus Torvalds if (page->index < end_index) 26951da177e4SLinus Torvalds goto out; 26961da177e4SLinus Torvalds 26971da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 26981da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 26991da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 27001da177e4SLinus Torvalds /* 27011da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 27021da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 27031da177e4SLinus Torvalds * freeable here, so the page does not leak. 27041da177e4SLinus Torvalds */ 27051da177e4SLinus Torvalds #if 0 27061da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 27071da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 27081da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 27091da177e4SLinus Torvalds #endif 27101da177e4SLinus Torvalds unlock_page(page); 27111da177e4SLinus Torvalds return 0; /* don't care */ 27121da177e4SLinus Torvalds } 27131da177e4SLinus Torvalds 27141da177e4SLinus Torvalds /* 27151da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 27161da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 27171da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 27181da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 27191da177e4SLinus Torvalds * writes to that region are not written out to the file." 27201da177e4SLinus Torvalds */ 2721eebd2aa3SChristoph Lameter zero_user_segment(page, offset, PAGE_CACHE_SIZE); 27221da177e4SLinus Torvalds out: 27231da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 27241da177e4SLinus Torvalds if (ret == -EAGAIN) 272535c80d5fSChris Mason ret = __block_write_full_page(inode, page, get_block, wbc, 272635c80d5fSChris Mason end_buffer_async_write); 27271da177e4SLinus Torvalds return ret; 27281da177e4SLinus Torvalds } 27291da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 27301da177e4SLinus Torvalds 273103158cd7SNick Piggin int nobh_truncate_page(struct address_space *mapping, 273203158cd7SNick Piggin loff_t from, get_block_t *get_block) 27331da177e4SLinus Torvalds { 27341da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 27351da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 273603158cd7SNick Piggin unsigned blocksize; 273703158cd7SNick Piggin sector_t iblock; 273803158cd7SNick Piggin unsigned length, pos; 273903158cd7SNick Piggin struct inode *inode = mapping->host; 27401da177e4SLinus Torvalds struct page *page; 274103158cd7SNick Piggin struct buffer_head map_bh; 274203158cd7SNick Piggin int err; 27431da177e4SLinus Torvalds 274403158cd7SNick Piggin blocksize = 1 << inode->i_blkbits; 274503158cd7SNick Piggin length = offset & (blocksize - 1); 27461da177e4SLinus Torvalds 274703158cd7SNick Piggin /* Block boundary? Nothing to do */ 274803158cd7SNick Piggin if (!length) 274903158cd7SNick Piggin return 0; 275003158cd7SNick Piggin 275103158cd7SNick Piggin length = blocksize - length; 275203158cd7SNick Piggin iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 275303158cd7SNick Piggin 27541da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 275503158cd7SNick Piggin err = -ENOMEM; 27561da177e4SLinus Torvalds if (!page) 27571da177e4SLinus Torvalds goto out; 27581da177e4SLinus Torvalds 275903158cd7SNick Piggin if (page_has_buffers(page)) { 276003158cd7SNick Piggin has_buffers: 276103158cd7SNick Piggin unlock_page(page); 276203158cd7SNick Piggin page_cache_release(page); 276303158cd7SNick Piggin return block_truncate_page(mapping, from, get_block); 27641da177e4SLinus Torvalds } 276503158cd7SNick Piggin 276603158cd7SNick Piggin /* Find the buffer that contains "offset" */ 276703158cd7SNick Piggin pos = blocksize; 276803158cd7SNick Piggin while (offset >= pos) { 276903158cd7SNick Piggin iblock++; 277003158cd7SNick Piggin pos += blocksize; 277103158cd7SNick Piggin } 277203158cd7SNick Piggin 2773460bcf57STheodore Ts'o map_bh.b_size = blocksize; 2774460bcf57STheodore Ts'o map_bh.b_state = 0; 277503158cd7SNick Piggin err = get_block(inode, iblock, &map_bh, 0); 277603158cd7SNick Piggin if (err) 277703158cd7SNick Piggin goto unlock; 277803158cd7SNick Piggin /* unmapped? It's a hole - nothing to do */ 277903158cd7SNick Piggin if (!buffer_mapped(&map_bh)) 278003158cd7SNick Piggin goto unlock; 278103158cd7SNick Piggin 278203158cd7SNick Piggin /* Ok, it's mapped. Make sure it's up-to-date */ 278303158cd7SNick Piggin if (!PageUptodate(page)) { 278403158cd7SNick Piggin err = mapping->a_ops->readpage(NULL, page); 278503158cd7SNick Piggin if (err) { 278603158cd7SNick Piggin page_cache_release(page); 278703158cd7SNick Piggin goto out; 278803158cd7SNick Piggin } 278903158cd7SNick Piggin lock_page(page); 279003158cd7SNick Piggin if (!PageUptodate(page)) { 279103158cd7SNick Piggin err = -EIO; 279203158cd7SNick Piggin goto unlock; 279303158cd7SNick Piggin } 279403158cd7SNick Piggin if (page_has_buffers(page)) 279503158cd7SNick Piggin goto has_buffers; 279603158cd7SNick Piggin } 2797eebd2aa3SChristoph Lameter zero_user(page, offset, length); 279803158cd7SNick Piggin set_page_dirty(page); 279903158cd7SNick Piggin err = 0; 280003158cd7SNick Piggin 280103158cd7SNick Piggin unlock: 28021da177e4SLinus Torvalds unlock_page(page); 28031da177e4SLinus Torvalds page_cache_release(page); 28041da177e4SLinus Torvalds out: 280503158cd7SNick Piggin return err; 28061da177e4SLinus Torvalds } 28071da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 28081da177e4SLinus Torvalds 28091da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 28101da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 28111da177e4SLinus Torvalds { 28121da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 28131da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 28141da177e4SLinus Torvalds unsigned blocksize; 281554b21a79SAndrew Morton sector_t iblock; 28161da177e4SLinus Torvalds unsigned length, pos; 28171da177e4SLinus Torvalds struct inode *inode = mapping->host; 28181da177e4SLinus Torvalds struct page *page; 28191da177e4SLinus Torvalds struct buffer_head *bh; 28201da177e4SLinus Torvalds int err; 28211da177e4SLinus Torvalds 28221da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 28231da177e4SLinus Torvalds length = offset & (blocksize - 1); 28241da177e4SLinus Torvalds 28251da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 28261da177e4SLinus Torvalds if (!length) 28271da177e4SLinus Torvalds return 0; 28281da177e4SLinus Torvalds 28291da177e4SLinus Torvalds length = blocksize - length; 283054b21a79SAndrew Morton iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 28311da177e4SLinus Torvalds 28321da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 28331da177e4SLinus Torvalds err = -ENOMEM; 28341da177e4SLinus Torvalds if (!page) 28351da177e4SLinus Torvalds goto out; 28361da177e4SLinus Torvalds 28371da177e4SLinus Torvalds if (!page_has_buffers(page)) 28381da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 28391da177e4SLinus Torvalds 28401da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 28411da177e4SLinus Torvalds bh = page_buffers(page); 28421da177e4SLinus Torvalds pos = blocksize; 28431da177e4SLinus Torvalds while (offset >= pos) { 28441da177e4SLinus Torvalds bh = bh->b_this_page; 28451da177e4SLinus Torvalds iblock++; 28461da177e4SLinus Torvalds pos += blocksize; 28471da177e4SLinus Torvalds } 28481da177e4SLinus Torvalds 28491da177e4SLinus Torvalds err = 0; 28501da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2851b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 28521da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 28531da177e4SLinus Torvalds if (err) 28541da177e4SLinus Torvalds goto unlock; 28551da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 28561da177e4SLinus Torvalds if (!buffer_mapped(bh)) 28571da177e4SLinus Torvalds goto unlock; 28581da177e4SLinus Torvalds } 28591da177e4SLinus Torvalds 28601da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 28611da177e4SLinus Torvalds if (PageUptodate(page)) 28621da177e4SLinus Torvalds set_buffer_uptodate(bh); 28631da177e4SLinus Torvalds 286433a266ddSDavid Chinner if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { 28651da177e4SLinus Torvalds err = -EIO; 28661da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 28671da177e4SLinus Torvalds wait_on_buffer(bh); 28681da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 28691da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 28701da177e4SLinus Torvalds goto unlock; 28711da177e4SLinus Torvalds } 28721da177e4SLinus Torvalds 2873eebd2aa3SChristoph Lameter zero_user(page, offset, length); 28741da177e4SLinus Torvalds mark_buffer_dirty(bh); 28751da177e4SLinus Torvalds err = 0; 28761da177e4SLinus Torvalds 28771da177e4SLinus Torvalds unlock: 28781da177e4SLinus Torvalds unlock_page(page); 28791da177e4SLinus Torvalds page_cache_release(page); 28801da177e4SLinus Torvalds out: 28811da177e4SLinus Torvalds return err; 28821da177e4SLinus Torvalds } 28831fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_truncate_page); 28841da177e4SLinus Torvalds 28851da177e4SLinus Torvalds /* 28861da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 28871da177e4SLinus Torvalds */ 28881b938c08SMatthew Wilcox int block_write_full_page(struct page *page, get_block_t *get_block, 28891b938c08SMatthew Wilcox struct writeback_control *wbc) 28901da177e4SLinus Torvalds { 28911da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 28921da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 28931da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 28941da177e4SLinus Torvalds unsigned offset; 28951da177e4SLinus Torvalds 28961da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 28971da177e4SLinus Torvalds if (page->index < end_index) 289835c80d5fSChris Mason return __block_write_full_page(inode, page, get_block, wbc, 28991b938c08SMatthew Wilcox end_buffer_async_write); 29001da177e4SLinus Torvalds 29011da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 29021da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 29031da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 29041da177e4SLinus Torvalds /* 29051da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 29061da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 29071da177e4SLinus Torvalds * freeable here, so the page does not leak. 29081da177e4SLinus Torvalds */ 2909d47992f8SLukas Czerner do_invalidatepage(page, 0, PAGE_CACHE_SIZE); 29101da177e4SLinus Torvalds unlock_page(page); 29111da177e4SLinus Torvalds return 0; /* don't care */ 29121da177e4SLinus Torvalds } 29131da177e4SLinus Torvalds 29141da177e4SLinus Torvalds /* 29151da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 29162a61aa40SAdam Buchbinder * writepage invocation because it may be mmapped. "A file is mapped 29171da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 29181da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 29191da177e4SLinus Torvalds * writes to that region are not written out to the file." 29201da177e4SLinus Torvalds */ 2921eebd2aa3SChristoph Lameter zero_user_segment(page, offset, PAGE_CACHE_SIZE); 29221b938c08SMatthew Wilcox return __block_write_full_page(inode, page, get_block, wbc, 292335c80d5fSChris Mason end_buffer_async_write); 292435c80d5fSChris Mason } 29251fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(block_write_full_page); 292635c80d5fSChris Mason 29271da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 29281da177e4SLinus Torvalds get_block_t *get_block) 29291da177e4SLinus Torvalds { 29301da177e4SLinus Torvalds struct buffer_head tmp; 29311da177e4SLinus Torvalds struct inode *inode = mapping->host; 29321da177e4SLinus Torvalds tmp.b_state = 0; 29331da177e4SLinus Torvalds tmp.b_blocknr = 0; 2934b0cf2321SBadari Pulavarty tmp.b_size = 1 << inode->i_blkbits; 29351da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 29361da177e4SLinus Torvalds return tmp.b_blocknr; 29371da177e4SLinus Torvalds } 29381fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(generic_block_bmap); 29391da177e4SLinus Torvalds 29406712ecf8SNeilBrown static void end_bio_bh_io_sync(struct bio *bio, int err) 29411da177e4SLinus Torvalds { 29421da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 29431da177e4SLinus Torvalds 29441da177e4SLinus Torvalds if (err == -EOPNOTSUPP) { 29451da177e4SLinus Torvalds set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); 29461da177e4SLinus Torvalds } 29471da177e4SLinus Torvalds 294808bafc03SKeith Mannthey if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags))) 294908bafc03SKeith Mannthey set_bit(BH_Quiet, &bh->b_state); 295008bafc03SKeith Mannthey 29511da177e4SLinus Torvalds bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); 29521da177e4SLinus Torvalds bio_put(bio); 29531da177e4SLinus Torvalds } 29541da177e4SLinus Torvalds 295557302e0dSLinus Torvalds /* 295657302e0dSLinus Torvalds * This allows us to do IO even on the odd last sectors 295757302e0dSLinus Torvalds * of a device, even if the bh block size is some multiple 295857302e0dSLinus Torvalds * of the physical sector size. 295957302e0dSLinus Torvalds * 296057302e0dSLinus Torvalds * We'll just truncate the bio to the size of the device, 296157302e0dSLinus Torvalds * and clear the end of the buffer head manually. 296257302e0dSLinus Torvalds * 296357302e0dSLinus Torvalds * Truly out-of-range accesses will turn into actual IO 296457302e0dSLinus Torvalds * errors, this only handles the "we need to be able to 296557302e0dSLinus Torvalds * do IO at the final sector" case. 296657302e0dSLinus Torvalds */ 296757302e0dSLinus Torvalds static void guard_bh_eod(int rw, struct bio *bio, struct buffer_head *bh) 296857302e0dSLinus Torvalds { 296957302e0dSLinus Torvalds sector_t maxsector; 297057302e0dSLinus Torvalds unsigned bytes; 297157302e0dSLinus Torvalds 297257302e0dSLinus Torvalds maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; 297357302e0dSLinus Torvalds if (!maxsector) 297457302e0dSLinus Torvalds return; 297557302e0dSLinus Torvalds 297657302e0dSLinus Torvalds /* 297757302e0dSLinus Torvalds * If the *whole* IO is past the end of the device, 297857302e0dSLinus Torvalds * let it through, and the IO layer will turn it into 297957302e0dSLinus Torvalds * an EIO. 298057302e0dSLinus Torvalds */ 29814f024f37SKent Overstreet if (unlikely(bio->bi_iter.bi_sector >= maxsector)) 298257302e0dSLinus Torvalds return; 298357302e0dSLinus Torvalds 29844f024f37SKent Overstreet maxsector -= bio->bi_iter.bi_sector; 29854f024f37SKent Overstreet bytes = bio->bi_iter.bi_size; 298657302e0dSLinus Torvalds if (likely((bytes >> 9) <= maxsector)) 298757302e0dSLinus Torvalds return; 298857302e0dSLinus Torvalds 298957302e0dSLinus Torvalds /* Uhhuh. We've got a bh that straddles the device size! */ 299057302e0dSLinus Torvalds bytes = maxsector << 9; 299157302e0dSLinus Torvalds 299257302e0dSLinus Torvalds /* Truncate the bio.. */ 29934f024f37SKent Overstreet bio->bi_iter.bi_size = bytes; 299457302e0dSLinus Torvalds bio->bi_io_vec[0].bv_len = bytes; 299557302e0dSLinus Torvalds 299657302e0dSLinus Torvalds /* ..and clear the end of the buffer for reads */ 299727d7c2a0SDan Carpenter if ((rw & RW_MASK) == READ) { 299857302e0dSLinus Torvalds void *kaddr = kmap_atomic(bh->b_page); 299957302e0dSLinus Torvalds memset(kaddr + bh_offset(bh) + bytes, 0, bh->b_size - bytes); 300057302e0dSLinus Torvalds kunmap_atomic(kaddr); 30016d283dbaSLinus Torvalds flush_dcache_page(bh->b_page); 300257302e0dSLinus Torvalds } 300357302e0dSLinus Torvalds } 300457302e0dSLinus Torvalds 300571368511SDarrick J. Wong int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags) 30061da177e4SLinus Torvalds { 30071da177e4SLinus Torvalds struct bio *bio; 30081da177e4SLinus Torvalds int ret = 0; 30091da177e4SLinus Torvalds 30101da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 30111da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 30121da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 30138fb0e342SAneesh Kumar K.V BUG_ON(buffer_delay(bh)); 30148fb0e342SAneesh Kumar K.V BUG_ON(buffer_unwritten(bh)); 30151da177e4SLinus Torvalds 301648fd4f93SJens Axboe /* 301748fd4f93SJens Axboe * Only clear out a write error when rewriting 30181da177e4SLinus Torvalds */ 301948fd4f93SJens Axboe if (test_set_buffer_req(bh) && (rw & WRITE)) 30201da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 30211da177e4SLinus Torvalds 30221da177e4SLinus Torvalds /* 30231da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 30241da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 30251da177e4SLinus Torvalds */ 30261da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 30271da177e4SLinus Torvalds 30284f024f37SKent Overstreet bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); 30291da177e4SLinus Torvalds bio->bi_bdev = bh->b_bdev; 30301da177e4SLinus Torvalds bio->bi_io_vec[0].bv_page = bh->b_page; 30311da177e4SLinus Torvalds bio->bi_io_vec[0].bv_len = bh->b_size; 30321da177e4SLinus Torvalds bio->bi_io_vec[0].bv_offset = bh_offset(bh); 30331da177e4SLinus Torvalds 30341da177e4SLinus Torvalds bio->bi_vcnt = 1; 30354f024f37SKent Overstreet bio->bi_iter.bi_size = bh->b_size; 30361da177e4SLinus Torvalds 30371da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 30381da177e4SLinus Torvalds bio->bi_private = bh; 303971368511SDarrick J. Wong bio->bi_flags |= bio_flags; 30401da177e4SLinus Torvalds 304157302e0dSLinus Torvalds /* Take care of bh's that straddle the end of the device */ 304257302e0dSLinus Torvalds guard_bh_eod(rw, bio, bh); 304357302e0dSLinus Torvalds 3044877f962cSTheodore Ts'o if (buffer_meta(bh)) 3045877f962cSTheodore Ts'o rw |= REQ_META; 3046877f962cSTheodore Ts'o if (buffer_prio(bh)) 3047877f962cSTheodore Ts'o rw |= REQ_PRIO; 3048877f962cSTheodore Ts'o 30491da177e4SLinus Torvalds bio_get(bio); 30501da177e4SLinus Torvalds submit_bio(rw, bio); 30511da177e4SLinus Torvalds 30521da177e4SLinus Torvalds if (bio_flagged(bio, BIO_EOPNOTSUPP)) 30531da177e4SLinus Torvalds ret = -EOPNOTSUPP; 30541da177e4SLinus Torvalds 30551da177e4SLinus Torvalds bio_put(bio); 30561da177e4SLinus Torvalds return ret; 30571da177e4SLinus Torvalds } 305871368511SDarrick J. Wong EXPORT_SYMBOL_GPL(_submit_bh); 305971368511SDarrick J. Wong 306071368511SDarrick J. Wong int submit_bh(int rw, struct buffer_head *bh) 306171368511SDarrick J. Wong { 306271368511SDarrick J. Wong return _submit_bh(rw, bh, 0); 306371368511SDarrick J. Wong } 30641fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(submit_bh); 30651da177e4SLinus Torvalds 30661da177e4SLinus Torvalds /** 30671da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 30689cb569d6SChristoph Hellwig * @rw: whether to %READ or %WRITE or maybe %READA (readahead) 30691da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 30701da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 30711da177e4SLinus Torvalds * 3072a7662236SJan Kara * ll_rw_block() takes an array of pointers to &struct buffer_heads, and 3073a7662236SJan Kara * requests an I/O operation on them, either a %READ or a %WRITE. The third 30749cb569d6SChristoph Hellwig * %READA option is described in the documentation for generic_make_request() 30759cb569d6SChristoph Hellwig * which ll_rw_block() calls. 30761da177e4SLinus Torvalds * 30771da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 30789cb569d6SChristoph Hellwig * BH_Lock state bit), any buffer that appears to be clean when doing a write 30799cb569d6SChristoph Hellwig * request, and any buffer that appears to be up-to-date when doing read 30809cb569d6SChristoph Hellwig * request. Further it marks as clean buffers that are processed for 30819cb569d6SChristoph Hellwig * writing (the buffer cache won't assume that they are actually clean 30829cb569d6SChristoph Hellwig * until the buffer gets unlocked). 30831da177e4SLinus Torvalds * 30841da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 3085e227867fSMasanari Iida * the buffer up-to-date (if appropriate), unlocks the buffer and wakes 30861da177e4SLinus Torvalds * any waiters. 30871da177e4SLinus Torvalds * 30881da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 30891da177e4SLinus Torvalds * multiple of the current approved size for the device. 30901da177e4SLinus Torvalds */ 30911da177e4SLinus Torvalds void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) 30921da177e4SLinus Torvalds { 30931da177e4SLinus Torvalds int i; 30941da177e4SLinus Torvalds 30951da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 30961da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 30971da177e4SLinus Torvalds 30989cb569d6SChristoph Hellwig if (!trylock_buffer(bh)) 30991da177e4SLinus Torvalds continue; 31009cb569d6SChristoph Hellwig if (rw == WRITE) { 31011da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 310276c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 3103e60e5c50SOGAWA Hirofumi get_bh(bh); 31041da177e4SLinus Torvalds submit_bh(WRITE, bh); 31051da177e4SLinus Torvalds continue; 31061da177e4SLinus Torvalds } 31071da177e4SLinus Torvalds } else { 31081da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 310976c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 3110e60e5c50SOGAWA Hirofumi get_bh(bh); 31111da177e4SLinus Torvalds submit_bh(rw, bh); 31121da177e4SLinus Torvalds continue; 31131da177e4SLinus Torvalds } 31141da177e4SLinus Torvalds } 31151da177e4SLinus Torvalds unlock_buffer(bh); 31161da177e4SLinus Torvalds } 31171da177e4SLinus Torvalds } 31181fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(ll_rw_block); 31191da177e4SLinus Torvalds 31209cb569d6SChristoph Hellwig void write_dirty_buffer(struct buffer_head *bh, int rw) 31219cb569d6SChristoph Hellwig { 31229cb569d6SChristoph Hellwig lock_buffer(bh); 31239cb569d6SChristoph Hellwig if (!test_clear_buffer_dirty(bh)) { 31249cb569d6SChristoph Hellwig unlock_buffer(bh); 31259cb569d6SChristoph Hellwig return; 31269cb569d6SChristoph Hellwig } 31279cb569d6SChristoph Hellwig bh->b_end_io = end_buffer_write_sync; 31289cb569d6SChristoph Hellwig get_bh(bh); 31299cb569d6SChristoph Hellwig submit_bh(rw, bh); 31309cb569d6SChristoph Hellwig } 31319cb569d6SChristoph Hellwig EXPORT_SYMBOL(write_dirty_buffer); 31329cb569d6SChristoph Hellwig 31331da177e4SLinus Torvalds /* 31341da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 31351da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 31361da177e4SLinus Torvalds * the buffer_head. 31371da177e4SLinus Torvalds */ 313887e99511SChristoph Hellwig int __sync_dirty_buffer(struct buffer_head *bh, int rw) 31391da177e4SLinus Torvalds { 31401da177e4SLinus Torvalds int ret = 0; 31411da177e4SLinus Torvalds 31421da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 31431da177e4SLinus Torvalds lock_buffer(bh); 31441da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 31451da177e4SLinus Torvalds get_bh(bh); 31461da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 314787e99511SChristoph Hellwig ret = submit_bh(rw, bh); 31481da177e4SLinus Torvalds wait_on_buffer(bh); 31491da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 31501da177e4SLinus Torvalds ret = -EIO; 31511da177e4SLinus Torvalds } else { 31521da177e4SLinus Torvalds unlock_buffer(bh); 31531da177e4SLinus Torvalds } 31541da177e4SLinus Torvalds return ret; 31551da177e4SLinus Torvalds } 315687e99511SChristoph Hellwig EXPORT_SYMBOL(__sync_dirty_buffer); 315787e99511SChristoph Hellwig 315887e99511SChristoph Hellwig int sync_dirty_buffer(struct buffer_head *bh) 315987e99511SChristoph Hellwig { 316087e99511SChristoph Hellwig return __sync_dirty_buffer(bh, WRITE_SYNC); 316187e99511SChristoph Hellwig } 31621fe72eaaSH Hartley Sweeten EXPORT_SYMBOL(sync_dirty_buffer); 31631da177e4SLinus Torvalds 31641da177e4SLinus Torvalds /* 31651da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 31661da177e4SLinus Torvalds * are unused, and releases them if so. 31671da177e4SLinus Torvalds * 31681da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 31691da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 31701da177e4SLinus Torvalds * 31711da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 31721da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 31731da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 31741da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 31751da177e4SLinus Torvalds * filesystem data on the same device. 31761da177e4SLinus Torvalds * 31771da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 31781da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 31791da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 31801da177e4SLinus Torvalds * private_lock. 31811da177e4SLinus Torvalds * 31821da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 31831da177e4SLinus Torvalds */ 31841da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 31851da177e4SLinus Torvalds { 31861da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 31871da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 31881da177e4SLinus Torvalds } 31891da177e4SLinus Torvalds 31901da177e4SLinus Torvalds static int 31911da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 31921da177e4SLinus Torvalds { 31931da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 31941da177e4SLinus Torvalds struct buffer_head *bh; 31951da177e4SLinus Torvalds 31961da177e4SLinus Torvalds bh = head; 31971da177e4SLinus Torvalds do { 3198de7d5a3bSakpm@osdl.org if (buffer_write_io_error(bh) && page->mapping) 31991da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 32001da177e4SLinus Torvalds if (buffer_busy(bh)) 32011da177e4SLinus Torvalds goto failed; 32021da177e4SLinus Torvalds bh = bh->b_this_page; 32031da177e4SLinus Torvalds } while (bh != head); 32041da177e4SLinus Torvalds 32051da177e4SLinus Torvalds do { 32061da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 32071da177e4SLinus Torvalds 3208535ee2fbSJan Kara if (bh->b_assoc_map) 32091da177e4SLinus Torvalds __remove_assoc_queue(bh); 32101da177e4SLinus Torvalds bh = next; 32111da177e4SLinus Torvalds } while (bh != head); 32121da177e4SLinus Torvalds *buffers_to_free = head; 32131da177e4SLinus Torvalds __clear_page_buffers(page); 32141da177e4SLinus Torvalds return 1; 32151da177e4SLinus Torvalds failed: 32161da177e4SLinus Torvalds return 0; 32171da177e4SLinus Torvalds } 32181da177e4SLinus Torvalds 32191da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 32201da177e4SLinus Torvalds { 32211da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 32221da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 32231da177e4SLinus Torvalds int ret = 0; 32241da177e4SLinus Torvalds 32251da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 3226ecdfc978SLinus Torvalds if (PageWriteback(page)) 32271da177e4SLinus Torvalds return 0; 32281da177e4SLinus Torvalds 32291da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 32301da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 32311da177e4SLinus Torvalds goto out; 32321da177e4SLinus Torvalds } 32331da177e4SLinus Torvalds 32341da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 32351da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 3236ecdfc978SLinus Torvalds 3237ecdfc978SLinus Torvalds /* 3238ecdfc978SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 3239ecdfc978SLinus Torvalds * then we can have clean buffers against a dirty page. We 3240ecdfc978SLinus Torvalds * clean the page here; otherwise the VM will never notice 3241ecdfc978SLinus Torvalds * that the filesystem did any IO at all. 3242ecdfc978SLinus Torvalds * 3243ecdfc978SLinus Torvalds * Also, during truncate, discard_buffer will have marked all 3244ecdfc978SLinus Torvalds * the page's buffers clean. We discover that here and clean 3245ecdfc978SLinus Torvalds * the page also. 324687df7241SNick Piggin * 324787df7241SNick Piggin * private_lock must be held over this entire operation in order 324887df7241SNick Piggin * to synchronise against __set_page_dirty_buffers and prevent the 324987df7241SNick Piggin * dirty bit from being lost. 3250ecdfc978SLinus Torvalds */ 3251ecdfc978SLinus Torvalds if (ret) 3252ecdfc978SLinus Torvalds cancel_dirty_page(page, PAGE_CACHE_SIZE); 325387df7241SNick Piggin spin_unlock(&mapping->private_lock); 32541da177e4SLinus Torvalds out: 32551da177e4SLinus Torvalds if (buffers_to_free) { 32561da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 32571da177e4SLinus Torvalds 32581da177e4SLinus Torvalds do { 32591da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 32601da177e4SLinus Torvalds free_buffer_head(bh); 32611da177e4SLinus Torvalds bh = next; 32621da177e4SLinus Torvalds } while (bh != buffers_to_free); 32631da177e4SLinus Torvalds } 32641da177e4SLinus Torvalds return ret; 32651da177e4SLinus Torvalds } 32661da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 32671da177e4SLinus Torvalds 32681da177e4SLinus Torvalds /* 32691da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 32701da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 32711da177e4SLinus Torvalds * 32721da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 32735b0830cbSJens Axboe * The `flush-X' kernel threads fully replace bdflush daemons and this call. 32741da177e4SLinus Torvalds */ 3275bdc480e3SHeiko Carstens SYSCALL_DEFINE2(bdflush, int, func, long, data) 32761da177e4SLinus Torvalds { 32771da177e4SLinus Torvalds static int msg_count; 32781da177e4SLinus Torvalds 32791da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 32801da177e4SLinus Torvalds return -EPERM; 32811da177e4SLinus Torvalds 32821da177e4SLinus Torvalds if (msg_count < 5) { 32831da177e4SLinus Torvalds msg_count++; 32841da177e4SLinus Torvalds printk(KERN_INFO 32851da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 32861da177e4SLinus Torvalds " system call\n", current->comm); 32871da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 32881da177e4SLinus Torvalds } 32891da177e4SLinus Torvalds 32901da177e4SLinus Torvalds if (func == 1) 32911da177e4SLinus Torvalds do_exit(0); 32921da177e4SLinus Torvalds return 0; 32931da177e4SLinus Torvalds } 32941da177e4SLinus Torvalds 32951da177e4SLinus Torvalds /* 32961da177e4SLinus Torvalds * Buffer-head allocation 32971da177e4SLinus Torvalds */ 3298a0a9b043SShai Fultheim static struct kmem_cache *bh_cachep __read_mostly; 32991da177e4SLinus Torvalds 33001da177e4SLinus Torvalds /* 33011da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 33021da177e4SLinus Torvalds * stripping them in writeback. 33031da177e4SLinus Torvalds */ 330443be594aSZhang Yanfei static unsigned long max_buffer_heads; 33051da177e4SLinus Torvalds 33061da177e4SLinus Torvalds int buffer_heads_over_limit; 33071da177e4SLinus Torvalds 33081da177e4SLinus Torvalds struct bh_accounting { 33091da177e4SLinus Torvalds int nr; /* Number of live bh's */ 33101da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 33111da177e4SLinus Torvalds }; 33121da177e4SLinus Torvalds 33131da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 33141da177e4SLinus Torvalds 33151da177e4SLinus Torvalds static void recalc_bh_state(void) 33161da177e4SLinus Torvalds { 33171da177e4SLinus Torvalds int i; 33181da177e4SLinus Torvalds int tot = 0; 33191da177e4SLinus Torvalds 3320ee1be862SChristoph Lameter if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) 33211da177e4SLinus Torvalds return; 3322c7b92516SChristoph Lameter __this_cpu_write(bh_accounting.ratelimit, 0); 33238a143426SEric Dumazet for_each_online_cpu(i) 33241da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 33251da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 33261da177e4SLinus Torvalds } 33271da177e4SLinus Torvalds 3328dd0fc66fSAl Viro struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) 33291da177e4SLinus Torvalds { 3330019b4d12SRichard Kennedy struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); 33311da177e4SLinus Torvalds if (ret) { 3332a35afb83SChristoph Lameter INIT_LIST_HEAD(&ret->b_assoc_buffers); 3333c7b92516SChristoph Lameter preempt_disable(); 3334c7b92516SChristoph Lameter __this_cpu_inc(bh_accounting.nr); 33351da177e4SLinus Torvalds recalc_bh_state(); 3336c7b92516SChristoph Lameter preempt_enable(); 33371da177e4SLinus Torvalds } 33381da177e4SLinus Torvalds return ret; 33391da177e4SLinus Torvalds } 33401da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 33411da177e4SLinus Torvalds 33421da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 33431da177e4SLinus Torvalds { 33441da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 33451da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 3346c7b92516SChristoph Lameter preempt_disable(); 3347c7b92516SChristoph Lameter __this_cpu_dec(bh_accounting.nr); 33481da177e4SLinus Torvalds recalc_bh_state(); 3349c7b92516SChristoph Lameter preempt_enable(); 33501da177e4SLinus Torvalds } 33511da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 33521da177e4SLinus Torvalds 33531da177e4SLinus Torvalds static void buffer_exit_cpu(int cpu) 33541da177e4SLinus Torvalds { 33551da177e4SLinus Torvalds int i; 33561da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 33571da177e4SLinus Torvalds 33581da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 33591da177e4SLinus Torvalds brelse(b->bhs[i]); 33601da177e4SLinus Torvalds b->bhs[i] = NULL; 33611da177e4SLinus Torvalds } 3362c7b92516SChristoph Lameter this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); 33638a143426SEric Dumazet per_cpu(bh_accounting, cpu).nr = 0; 33641da177e4SLinus Torvalds } 33651da177e4SLinus Torvalds 33661da177e4SLinus Torvalds static int buffer_cpu_notify(struct notifier_block *self, 33671da177e4SLinus Torvalds unsigned long action, void *hcpu) 33681da177e4SLinus Torvalds { 33698bb78442SRafael J. Wysocki if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) 33701da177e4SLinus Torvalds buffer_exit_cpu((unsigned long)hcpu); 33711da177e4SLinus Torvalds return NOTIFY_OK; 33721da177e4SLinus Torvalds } 33731da177e4SLinus Torvalds 3374389d1b08SAneesh Kumar K.V /** 3375a6b91919SRandy Dunlap * bh_uptodate_or_lock - Test whether the buffer is uptodate 3376389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3377389d1b08SAneesh Kumar K.V * 3378389d1b08SAneesh Kumar K.V * Return true if the buffer is up-to-date and false, 3379389d1b08SAneesh Kumar K.V * with the buffer locked, if not. 3380389d1b08SAneesh Kumar K.V */ 3381389d1b08SAneesh Kumar K.V int bh_uptodate_or_lock(struct buffer_head *bh) 3382389d1b08SAneesh Kumar K.V { 3383389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) { 3384389d1b08SAneesh Kumar K.V lock_buffer(bh); 3385389d1b08SAneesh Kumar K.V if (!buffer_uptodate(bh)) 3386389d1b08SAneesh Kumar K.V return 0; 3387389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3388389d1b08SAneesh Kumar K.V } 3389389d1b08SAneesh Kumar K.V return 1; 3390389d1b08SAneesh Kumar K.V } 3391389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_uptodate_or_lock); 3392389d1b08SAneesh Kumar K.V 3393389d1b08SAneesh Kumar K.V /** 3394a6b91919SRandy Dunlap * bh_submit_read - Submit a locked buffer for reading 3395389d1b08SAneesh Kumar K.V * @bh: struct buffer_head 3396389d1b08SAneesh Kumar K.V * 3397389d1b08SAneesh Kumar K.V * Returns zero on success and -EIO on error. 3398389d1b08SAneesh Kumar K.V */ 3399389d1b08SAneesh Kumar K.V int bh_submit_read(struct buffer_head *bh) 3400389d1b08SAneesh Kumar K.V { 3401389d1b08SAneesh Kumar K.V BUG_ON(!buffer_locked(bh)); 3402389d1b08SAneesh Kumar K.V 3403389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) { 3404389d1b08SAneesh Kumar K.V unlock_buffer(bh); 3405389d1b08SAneesh Kumar K.V return 0; 3406389d1b08SAneesh Kumar K.V } 3407389d1b08SAneesh Kumar K.V 3408389d1b08SAneesh Kumar K.V get_bh(bh); 3409389d1b08SAneesh Kumar K.V bh->b_end_io = end_buffer_read_sync; 3410389d1b08SAneesh Kumar K.V submit_bh(READ, bh); 3411389d1b08SAneesh Kumar K.V wait_on_buffer(bh); 3412389d1b08SAneesh Kumar K.V if (buffer_uptodate(bh)) 3413389d1b08SAneesh Kumar K.V return 0; 3414389d1b08SAneesh Kumar K.V return -EIO; 3415389d1b08SAneesh Kumar K.V } 3416389d1b08SAneesh Kumar K.V EXPORT_SYMBOL(bh_submit_read); 3417389d1b08SAneesh Kumar K.V 34181da177e4SLinus Torvalds void __init buffer_init(void) 34191da177e4SLinus Torvalds { 342043be594aSZhang Yanfei unsigned long nrpages; 34211da177e4SLinus Torvalds 3422b98938c3SChristoph Lameter bh_cachep = kmem_cache_create("buffer_head", 3423b98938c3SChristoph Lameter sizeof(struct buffer_head), 0, 3424b98938c3SChristoph Lameter (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| 3425b98938c3SChristoph Lameter SLAB_MEM_SPREAD), 3426019b4d12SRichard Kennedy NULL); 34271da177e4SLinus Torvalds 34281da177e4SLinus Torvalds /* 34291da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 34301da177e4SLinus Torvalds */ 34311da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 34321da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 34331da177e4SLinus Torvalds hotcpu_notifier(buffer_cpu_notify, 0); 34341da177e4SLinus Torvalds } 3435