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> 321da177e4SLinus Torvalds #include <linux/module.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> 441da177e4SLinus Torvalds 451da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); 461da177e4SLinus Torvalds 471da177e4SLinus Torvalds #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) 481da177e4SLinus Torvalds 491da177e4SLinus Torvalds inline void 501da177e4SLinus Torvalds 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 } 551da177e4SLinus Torvalds 561da177e4SLinus Torvalds static int sync_buffer(void *word) 571da177e4SLinus Torvalds { 581da177e4SLinus Torvalds struct block_device *bd; 591da177e4SLinus Torvalds struct buffer_head *bh 601da177e4SLinus Torvalds = container_of(word, struct buffer_head, b_state); 611da177e4SLinus Torvalds 621da177e4SLinus Torvalds smp_mb(); 631da177e4SLinus Torvalds bd = bh->b_bdev; 641da177e4SLinus Torvalds if (bd) 651da177e4SLinus Torvalds blk_run_address_space(bd->bd_inode->i_mapping); 661da177e4SLinus Torvalds io_schedule(); 671da177e4SLinus Torvalds return 0; 681da177e4SLinus Torvalds } 691da177e4SLinus Torvalds 701da177e4SLinus Torvalds void fastcall __lock_buffer(struct buffer_head *bh) 711da177e4SLinus Torvalds { 721da177e4SLinus Torvalds wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer, 731da177e4SLinus Torvalds TASK_UNINTERRUPTIBLE); 741da177e4SLinus Torvalds } 751da177e4SLinus Torvalds EXPORT_SYMBOL(__lock_buffer); 761da177e4SLinus Torvalds 771da177e4SLinus Torvalds void fastcall unlock_buffer(struct buffer_head *bh) 781da177e4SLinus Torvalds { 7972ed3d03SNick Piggin smp_mb__before_clear_bit(); 801da177e4SLinus Torvalds clear_buffer_locked(bh); 811da177e4SLinus Torvalds smp_mb__after_clear_bit(); 821da177e4SLinus Torvalds wake_up_bit(&bh->b_state, BH_Lock); 831da177e4SLinus Torvalds } 841da177e4SLinus Torvalds 851da177e4SLinus Torvalds /* 861da177e4SLinus Torvalds * Block until a buffer comes unlocked. This doesn't stop it 871da177e4SLinus Torvalds * from becoming locked again - you have to lock it yourself 881da177e4SLinus Torvalds * if you want to preserve its state. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds void __wait_on_buffer(struct buffer_head * bh) 911da177e4SLinus Torvalds { 921da177e4SLinus Torvalds wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE); 931da177e4SLinus Torvalds } 941da177e4SLinus Torvalds 951da177e4SLinus Torvalds static void 961da177e4SLinus Torvalds __clear_page_buffers(struct page *page) 971da177e4SLinus Torvalds { 981da177e4SLinus Torvalds ClearPagePrivate(page); 994c21e2f2SHugh Dickins set_page_private(page, 0); 1001da177e4SLinus Torvalds page_cache_release(page); 1011da177e4SLinus Torvalds } 1021da177e4SLinus Torvalds 1031da177e4SLinus Torvalds static void buffer_io_error(struct buffer_head *bh) 1041da177e4SLinus Torvalds { 1051da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 1061da177e4SLinus Torvalds 1071da177e4SLinus Torvalds printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", 1081da177e4SLinus Torvalds bdevname(bh->b_bdev, b), 1091da177e4SLinus Torvalds (unsigned long long)bh->b_blocknr); 1101da177e4SLinus Torvalds } 1111da177e4SLinus Torvalds 1121da177e4SLinus Torvalds /* 11368671f35SDmitry Monakhov * End-of-IO handler helper function which does not touch the bh after 11468671f35SDmitry Monakhov * unlocking it. 11568671f35SDmitry Monakhov * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but 11668671f35SDmitry Monakhov * a race there is benign: unlock_buffer() only use the bh's address for 11768671f35SDmitry Monakhov * hashing after unlocking the buffer, so it doesn't actually touch the bh 11868671f35SDmitry Monakhov * itself. 1191da177e4SLinus Torvalds */ 12068671f35SDmitry Monakhov static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) 1211da177e4SLinus Torvalds { 1221da177e4SLinus Torvalds if (uptodate) { 1231da177e4SLinus Torvalds set_buffer_uptodate(bh); 1241da177e4SLinus Torvalds } else { 1251da177e4SLinus Torvalds /* This happens, due to failed READA attempts. */ 1261da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1271da177e4SLinus Torvalds } 1281da177e4SLinus Torvalds unlock_buffer(bh); 12968671f35SDmitry Monakhov } 13068671f35SDmitry Monakhov 13168671f35SDmitry Monakhov /* 13268671f35SDmitry Monakhov * Default synchronous end-of-IO handler.. Just mark it up-to-date and 13368671f35SDmitry Monakhov * unlock the buffer. This is what ll_rw_block uses too. 13468671f35SDmitry Monakhov */ 13568671f35SDmitry Monakhov void end_buffer_read_sync(struct buffer_head *bh, int uptodate) 13668671f35SDmitry Monakhov { 13768671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 1381da177e4SLinus Torvalds put_bh(bh); 1391da177e4SLinus Torvalds } 1401da177e4SLinus Torvalds 1411da177e4SLinus Torvalds void end_buffer_write_sync(struct buffer_head *bh, int uptodate) 1421da177e4SLinus Torvalds { 1431da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 1441da177e4SLinus Torvalds 1451da177e4SLinus Torvalds if (uptodate) { 1461da177e4SLinus Torvalds set_buffer_uptodate(bh); 1471da177e4SLinus Torvalds } else { 1481da177e4SLinus Torvalds if (!buffer_eopnotsupp(bh) && printk_ratelimit()) { 1491da177e4SLinus Torvalds buffer_io_error(bh); 1501da177e4SLinus Torvalds printk(KERN_WARNING "lost page write due to " 1511da177e4SLinus Torvalds "I/O error on %s\n", 1521da177e4SLinus Torvalds bdevname(bh->b_bdev, b)); 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds set_buffer_write_io_error(bh); 1551da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1561da177e4SLinus Torvalds } 1571da177e4SLinus Torvalds unlock_buffer(bh); 1581da177e4SLinus Torvalds put_bh(bh); 1591da177e4SLinus Torvalds } 1601da177e4SLinus Torvalds 1611da177e4SLinus Torvalds /* 1621da177e4SLinus Torvalds * Write out and wait upon all the dirty data associated with a block 1631da177e4SLinus Torvalds * device via its mapping. Does not take the superblock lock. 1641da177e4SLinus Torvalds */ 1651da177e4SLinus Torvalds int sync_blockdev(struct block_device *bdev) 1661da177e4SLinus Torvalds { 1671da177e4SLinus Torvalds int ret = 0; 1681da177e4SLinus Torvalds 16928fd1298SOGAWA Hirofumi if (bdev) 17028fd1298SOGAWA Hirofumi ret = filemap_write_and_wait(bdev->bd_inode->i_mapping); 1711da177e4SLinus Torvalds return ret; 1721da177e4SLinus Torvalds } 1731da177e4SLinus Torvalds EXPORT_SYMBOL(sync_blockdev); 1741da177e4SLinus Torvalds 1751da177e4SLinus Torvalds /* 1761da177e4SLinus Torvalds * Write out and wait upon all dirty data associated with this 1771da177e4SLinus Torvalds * device. Filesystem data as well as the underlying block 1781da177e4SLinus Torvalds * device. Takes the superblock lock. 1791da177e4SLinus Torvalds */ 1801da177e4SLinus Torvalds int fsync_bdev(struct block_device *bdev) 1811da177e4SLinus Torvalds { 1821da177e4SLinus Torvalds struct super_block *sb = get_super(bdev); 1831da177e4SLinus Torvalds if (sb) { 1841da177e4SLinus Torvalds int res = fsync_super(sb); 1851da177e4SLinus Torvalds drop_super(sb); 1861da177e4SLinus Torvalds return res; 1871da177e4SLinus Torvalds } 1881da177e4SLinus Torvalds return sync_blockdev(bdev); 1891da177e4SLinus Torvalds } 1901da177e4SLinus Torvalds 1911da177e4SLinus Torvalds /** 1921da177e4SLinus Torvalds * freeze_bdev -- lock a filesystem and force it into a consistent state 1931da177e4SLinus Torvalds * @bdev: blockdevice to lock 1941da177e4SLinus Torvalds * 195f73ca1b7SDavid Chinner * This takes the block device bd_mount_sem to make sure no new mounts 1961da177e4SLinus Torvalds * happen on bdev until thaw_bdev() is called. 1971da177e4SLinus Torvalds * If a superblock is found on this device, we take the s_umount semaphore 1981da177e4SLinus Torvalds * on it to make sure nobody unmounts until the snapshot creation is done. 1991da177e4SLinus Torvalds */ 2001da177e4SLinus Torvalds struct super_block *freeze_bdev(struct block_device *bdev) 2011da177e4SLinus Torvalds { 2021da177e4SLinus Torvalds struct super_block *sb; 2031da177e4SLinus Torvalds 204f73ca1b7SDavid Chinner down(&bdev->bd_mount_sem); 2051da177e4SLinus Torvalds sb = get_super(bdev); 2061da177e4SLinus Torvalds if (sb && !(sb->s_flags & MS_RDONLY)) { 2071da177e4SLinus Torvalds sb->s_frozen = SB_FREEZE_WRITE; 208d59dd462Sakpm@osdl.org smp_wmb(); 2091da177e4SLinus Torvalds 210d25b9a1fSOGAWA Hirofumi __fsync_super(sb); 2111da177e4SLinus Torvalds 2121da177e4SLinus Torvalds sb->s_frozen = SB_FREEZE_TRANS; 213d59dd462Sakpm@osdl.org smp_wmb(); 2141da177e4SLinus Torvalds 2151da177e4SLinus Torvalds sync_blockdev(sb->s_bdev); 2161da177e4SLinus Torvalds 2171da177e4SLinus Torvalds if (sb->s_op->write_super_lockfs) 2181da177e4SLinus Torvalds sb->s_op->write_super_lockfs(sb); 2191da177e4SLinus Torvalds } 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds sync_blockdev(bdev); 2221da177e4SLinus Torvalds return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */ 2231da177e4SLinus Torvalds } 2241da177e4SLinus Torvalds EXPORT_SYMBOL(freeze_bdev); 2251da177e4SLinus Torvalds 2261da177e4SLinus Torvalds /** 2271da177e4SLinus Torvalds * thaw_bdev -- unlock filesystem 2281da177e4SLinus Torvalds * @bdev: blockdevice to unlock 2291da177e4SLinus Torvalds * @sb: associated superblock 2301da177e4SLinus Torvalds * 2311da177e4SLinus Torvalds * Unlocks the filesystem and marks it writeable again after freeze_bdev(). 2321da177e4SLinus Torvalds */ 2331da177e4SLinus Torvalds void thaw_bdev(struct block_device *bdev, struct super_block *sb) 2341da177e4SLinus Torvalds { 2351da177e4SLinus Torvalds if (sb) { 2361da177e4SLinus Torvalds BUG_ON(sb->s_bdev != bdev); 2371da177e4SLinus Torvalds 2381da177e4SLinus Torvalds if (sb->s_op->unlockfs) 2391da177e4SLinus Torvalds sb->s_op->unlockfs(sb); 2401da177e4SLinus Torvalds sb->s_frozen = SB_UNFROZEN; 241d59dd462Sakpm@osdl.org smp_wmb(); 2421da177e4SLinus Torvalds wake_up(&sb->s_wait_unfrozen); 2431da177e4SLinus Torvalds drop_super(sb); 2441da177e4SLinus Torvalds } 2451da177e4SLinus Torvalds 246f73ca1b7SDavid Chinner up(&bdev->bd_mount_sem); 2471da177e4SLinus Torvalds } 2481da177e4SLinus Torvalds EXPORT_SYMBOL(thaw_bdev); 2491da177e4SLinus Torvalds 2501da177e4SLinus Torvalds /* 2511da177e4SLinus Torvalds * Various filesystems appear to want __find_get_block to be non-blocking. 2521da177e4SLinus Torvalds * But it's the page lock which protects the buffers. To get around this, 2531da177e4SLinus Torvalds * we get exclusion from try_to_free_buffers with the blockdev mapping's 2541da177e4SLinus Torvalds * private_lock. 2551da177e4SLinus Torvalds * 2561da177e4SLinus Torvalds * Hack idea: for the blockdev mapping, i_bufferlist_lock contention 2571da177e4SLinus Torvalds * may be quite high. This code could TryLock the page, and if that 2581da177e4SLinus Torvalds * succeeds, there is no need to take private_lock. (But if 2591da177e4SLinus Torvalds * private_lock is contended then so is mapping->tree_lock). 2601da177e4SLinus Torvalds */ 2611da177e4SLinus Torvalds static struct buffer_head * 262385fd4c5SCoywolf Qi Hunt __find_get_block_slow(struct block_device *bdev, sector_t block) 2631da177e4SLinus Torvalds { 2641da177e4SLinus Torvalds struct inode *bd_inode = bdev->bd_inode; 2651da177e4SLinus Torvalds struct address_space *bd_mapping = bd_inode->i_mapping; 2661da177e4SLinus Torvalds struct buffer_head *ret = NULL; 2671da177e4SLinus Torvalds pgoff_t index; 2681da177e4SLinus Torvalds struct buffer_head *bh; 2691da177e4SLinus Torvalds struct buffer_head *head; 2701da177e4SLinus Torvalds struct page *page; 2711da177e4SLinus Torvalds int all_mapped = 1; 2721da177e4SLinus Torvalds 2731da177e4SLinus Torvalds index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); 2741da177e4SLinus Torvalds page = find_get_page(bd_mapping, index); 2751da177e4SLinus Torvalds if (!page) 2761da177e4SLinus Torvalds goto out; 2771da177e4SLinus Torvalds 2781da177e4SLinus Torvalds spin_lock(&bd_mapping->private_lock); 2791da177e4SLinus Torvalds if (!page_has_buffers(page)) 2801da177e4SLinus Torvalds goto out_unlock; 2811da177e4SLinus Torvalds head = page_buffers(page); 2821da177e4SLinus Torvalds bh = head; 2831da177e4SLinus Torvalds do { 2841da177e4SLinus Torvalds if (bh->b_blocknr == block) { 2851da177e4SLinus Torvalds ret = bh; 2861da177e4SLinus Torvalds get_bh(bh); 2871da177e4SLinus Torvalds goto out_unlock; 2881da177e4SLinus Torvalds } 2891da177e4SLinus Torvalds if (!buffer_mapped(bh)) 2901da177e4SLinus Torvalds all_mapped = 0; 2911da177e4SLinus Torvalds bh = bh->b_this_page; 2921da177e4SLinus Torvalds } while (bh != head); 2931da177e4SLinus Torvalds 2941da177e4SLinus Torvalds /* we might be here because some of the buffers on this page are 2951da177e4SLinus Torvalds * not mapped. This is due to various races between 2961da177e4SLinus Torvalds * file io on the block device and getblk. It gets dealt with 2971da177e4SLinus Torvalds * elsewhere, don't buffer_error if we had some unmapped buffers 2981da177e4SLinus Torvalds */ 2991da177e4SLinus Torvalds if (all_mapped) { 3001da177e4SLinus Torvalds printk("__find_get_block_slow() failed. " 3011da177e4SLinus Torvalds "block=%llu, b_blocknr=%llu\n", 302205f87f6SBadari Pulavarty (unsigned long long)block, 303205f87f6SBadari Pulavarty (unsigned long long)bh->b_blocknr); 304205f87f6SBadari Pulavarty printk("b_state=0x%08lx, b_size=%zu\n", 305205f87f6SBadari Pulavarty bh->b_state, bh->b_size); 3061da177e4SLinus Torvalds printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); 3071da177e4SLinus Torvalds } 3081da177e4SLinus Torvalds out_unlock: 3091da177e4SLinus Torvalds spin_unlock(&bd_mapping->private_lock); 3101da177e4SLinus Torvalds page_cache_release(page); 3111da177e4SLinus Torvalds out: 3121da177e4SLinus Torvalds return ret; 3131da177e4SLinus Torvalds } 3141da177e4SLinus Torvalds 3151da177e4SLinus Torvalds /* If invalidate_buffers() will trash dirty buffers, it means some kind 3161da177e4SLinus Torvalds of fs corruption is going on. Trashing dirty data always imply losing 3171da177e4SLinus Torvalds information that was supposed to be just stored on the physical layer 3181da177e4SLinus Torvalds by the user. 3191da177e4SLinus Torvalds 3201da177e4SLinus Torvalds Thus invalidate_buffers in general usage is not allwowed to trash 3211da177e4SLinus Torvalds dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to 3221da177e4SLinus Torvalds be preserved. These buffers are simply skipped. 3231da177e4SLinus Torvalds 3241da177e4SLinus Torvalds We also skip buffers which are still in use. For example this can 3251da177e4SLinus Torvalds happen if a userspace program is reading the block device. 3261da177e4SLinus Torvalds 3271da177e4SLinus Torvalds NOTE: In the case where the user removed a removable-media-disk even if 3281da177e4SLinus Torvalds there's still dirty data not synced on disk (due a bug in the device driver 3291da177e4SLinus Torvalds or due an error of the user), by not destroying the dirty buffers we could 3301da177e4SLinus Torvalds generate corruption also on the next media inserted, thus a parameter is 3311da177e4SLinus Torvalds necessary to handle this case in the most safe way possible (trying 3321da177e4SLinus Torvalds to not corrupt also the new disk inserted with the data belonging to 3331da177e4SLinus Torvalds the old now corrupted disk). Also for the ramdisk the natural thing 3341da177e4SLinus Torvalds to do in order to release the ramdisk memory is to destroy dirty buffers. 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds These are two special cases. Normal usage imply the device driver 3371da177e4SLinus Torvalds to issue a sync on the device (without waiting I/O completion) and 3381da177e4SLinus Torvalds then an invalidate_buffers call that doesn't trash dirty buffers. 3391da177e4SLinus Torvalds 3401da177e4SLinus Torvalds For handling cache coherency with the blkdev pagecache the 'update' case 3411da177e4SLinus Torvalds is been introduced. It is needed to re-read from disk any pinned 3421da177e4SLinus Torvalds buffer. NOTE: re-reading from disk is destructive so we can do it only 3431da177e4SLinus Torvalds when we assume nobody is changing the buffercache under our I/O and when 3441da177e4SLinus Torvalds we think the disk contains more recent information than the buffercache. 3451da177e4SLinus Torvalds The update == 1 pass marks the buffers we need to update, the update == 2 3461da177e4SLinus Torvalds pass does the actual I/O. */ 347f98393a6SPeter Zijlstra void invalidate_bdev(struct block_device *bdev) 3481da177e4SLinus Torvalds { 3490e1dfc66SAndrew Morton struct address_space *mapping = bdev->bd_inode->i_mapping; 3500e1dfc66SAndrew Morton 3510e1dfc66SAndrew Morton if (mapping->nrpages == 0) 3520e1dfc66SAndrew Morton return; 3530e1dfc66SAndrew Morton 3541da177e4SLinus Torvalds invalidate_bh_lrus(); 355fc0ecff6SAndrew Morton invalidate_mapping_pages(mapping, 0, -1); 3561da177e4SLinus Torvalds } 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Kick pdflush then try to free up some ZONE_NORMAL memory. 3601da177e4SLinus Torvalds */ 3611da177e4SLinus Torvalds static void free_more_memory(void) 3621da177e4SLinus Torvalds { 3631da177e4SLinus Torvalds struct zone **zones; 3641da177e4SLinus Torvalds pg_data_t *pgdat; 3651da177e4SLinus Torvalds 366687a21ceSPekka J Enberg wakeup_pdflush(1024); 3671da177e4SLinus Torvalds yield(); 3681da177e4SLinus Torvalds 369ec936fc5SKAMEZAWA Hiroyuki for_each_online_pgdat(pgdat) { 370af4ca457SAl Viro zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones; 3711da177e4SLinus Torvalds if (*zones) 3725ad333ebSAndy Whitcroft try_to_free_pages(zones, 0, GFP_NOFS); 3731da177e4SLinus Torvalds } 3741da177e4SLinus Torvalds } 3751da177e4SLinus Torvalds 3761da177e4SLinus Torvalds /* 3771da177e4SLinus Torvalds * I/O completion handler for block_read_full_page() - pages 3781da177e4SLinus Torvalds * which come unlocked at the end of I/O. 3791da177e4SLinus Torvalds */ 3801da177e4SLinus Torvalds static void end_buffer_async_read(struct buffer_head *bh, int uptodate) 3811da177e4SLinus Torvalds { 3821da177e4SLinus Torvalds unsigned long flags; 383a3972203SNick Piggin struct buffer_head *first; 3841da177e4SLinus Torvalds struct buffer_head *tmp; 3851da177e4SLinus Torvalds struct page *page; 3861da177e4SLinus Torvalds int page_uptodate = 1; 3871da177e4SLinus Torvalds 3881da177e4SLinus Torvalds BUG_ON(!buffer_async_read(bh)); 3891da177e4SLinus Torvalds 3901da177e4SLinus Torvalds page = bh->b_page; 3911da177e4SLinus Torvalds if (uptodate) { 3921da177e4SLinus Torvalds set_buffer_uptodate(bh); 3931da177e4SLinus Torvalds } else { 3941da177e4SLinus Torvalds clear_buffer_uptodate(bh); 3951da177e4SLinus Torvalds if (printk_ratelimit()) 3961da177e4SLinus Torvalds buffer_io_error(bh); 3971da177e4SLinus Torvalds SetPageError(page); 3981da177e4SLinus Torvalds } 3991da177e4SLinus Torvalds 4001da177e4SLinus Torvalds /* 4011da177e4SLinus Torvalds * Be _very_ careful from here on. Bad things can happen if 4021da177e4SLinus Torvalds * two buffer heads end IO at almost the same time and both 4031da177e4SLinus Torvalds * decide that the page is now completely done. 4041da177e4SLinus Torvalds */ 405a3972203SNick Piggin first = page_buffers(page); 406a3972203SNick Piggin local_irq_save(flags); 407a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 4081da177e4SLinus Torvalds clear_buffer_async_read(bh); 4091da177e4SLinus Torvalds unlock_buffer(bh); 4101da177e4SLinus Torvalds tmp = bh; 4111da177e4SLinus Torvalds do { 4121da177e4SLinus Torvalds if (!buffer_uptodate(tmp)) 4131da177e4SLinus Torvalds page_uptodate = 0; 4141da177e4SLinus Torvalds if (buffer_async_read(tmp)) { 4151da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 4161da177e4SLinus Torvalds goto still_busy; 4171da177e4SLinus Torvalds } 4181da177e4SLinus Torvalds tmp = tmp->b_this_page; 4191da177e4SLinus Torvalds } while (tmp != bh); 420a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 421a3972203SNick Piggin local_irq_restore(flags); 4221da177e4SLinus Torvalds 4231da177e4SLinus Torvalds /* 4241da177e4SLinus Torvalds * If none of the buffers had errors and they are all 4251da177e4SLinus Torvalds * uptodate then we can set the page uptodate. 4261da177e4SLinus Torvalds */ 4271da177e4SLinus Torvalds if (page_uptodate && !PageError(page)) 4281da177e4SLinus Torvalds SetPageUptodate(page); 4291da177e4SLinus Torvalds unlock_page(page); 4301da177e4SLinus Torvalds return; 4311da177e4SLinus Torvalds 4321da177e4SLinus Torvalds still_busy: 433a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 434a3972203SNick Piggin local_irq_restore(flags); 4351da177e4SLinus Torvalds return; 4361da177e4SLinus Torvalds } 4371da177e4SLinus Torvalds 4381da177e4SLinus Torvalds /* 4391da177e4SLinus Torvalds * Completion handler for block_write_full_page() - pages which are unlocked 4401da177e4SLinus Torvalds * during I/O, and which have PageWriteback cleared upon I/O completion. 4411da177e4SLinus Torvalds */ 442b6cd0b77SAdrian Bunk static void end_buffer_async_write(struct buffer_head *bh, int uptodate) 4431da177e4SLinus Torvalds { 4441da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 4451da177e4SLinus Torvalds unsigned long flags; 446a3972203SNick Piggin struct buffer_head *first; 4471da177e4SLinus Torvalds struct buffer_head *tmp; 4481da177e4SLinus Torvalds struct page *page; 4491da177e4SLinus Torvalds 4501da177e4SLinus Torvalds BUG_ON(!buffer_async_write(bh)); 4511da177e4SLinus Torvalds 4521da177e4SLinus Torvalds page = bh->b_page; 4531da177e4SLinus Torvalds if (uptodate) { 4541da177e4SLinus Torvalds set_buffer_uptodate(bh); 4551da177e4SLinus Torvalds } else { 4561da177e4SLinus Torvalds if (printk_ratelimit()) { 4571da177e4SLinus Torvalds buffer_io_error(bh); 4581da177e4SLinus Torvalds printk(KERN_WARNING "lost page write due to " 4591da177e4SLinus Torvalds "I/O error on %s\n", 4601da177e4SLinus Torvalds bdevname(bh->b_bdev, b)); 4611da177e4SLinus Torvalds } 4621da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 46358ff407bSJan Kara set_buffer_write_io_error(bh); 4641da177e4SLinus Torvalds clear_buffer_uptodate(bh); 4651da177e4SLinus Torvalds SetPageError(page); 4661da177e4SLinus Torvalds } 4671da177e4SLinus Torvalds 468a3972203SNick Piggin first = page_buffers(page); 469a3972203SNick Piggin local_irq_save(flags); 470a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 471a3972203SNick Piggin 4721da177e4SLinus Torvalds clear_buffer_async_write(bh); 4731da177e4SLinus Torvalds unlock_buffer(bh); 4741da177e4SLinus Torvalds tmp = bh->b_this_page; 4751da177e4SLinus Torvalds while (tmp != bh) { 4761da177e4SLinus Torvalds if (buffer_async_write(tmp)) { 4771da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 4781da177e4SLinus Torvalds goto still_busy; 4791da177e4SLinus Torvalds } 4801da177e4SLinus Torvalds tmp = tmp->b_this_page; 4811da177e4SLinus Torvalds } 482a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 483a3972203SNick Piggin local_irq_restore(flags); 4841da177e4SLinus Torvalds end_page_writeback(page); 4851da177e4SLinus Torvalds return; 4861da177e4SLinus Torvalds 4871da177e4SLinus Torvalds still_busy: 488a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 489a3972203SNick Piggin local_irq_restore(flags); 4901da177e4SLinus Torvalds return; 4911da177e4SLinus Torvalds } 4921da177e4SLinus Torvalds 4931da177e4SLinus Torvalds /* 4941da177e4SLinus Torvalds * If a page's buffers are under async readin (end_buffer_async_read 4951da177e4SLinus Torvalds * completion) then there is a possibility that another thread of 4961da177e4SLinus Torvalds * control could lock one of the buffers after it has completed 4971da177e4SLinus Torvalds * but while some of the other buffers have not completed. This 4981da177e4SLinus Torvalds * locked buffer would confuse end_buffer_async_read() into not unlocking 4991da177e4SLinus Torvalds * the page. So the absence of BH_Async_Read tells end_buffer_async_read() 5001da177e4SLinus Torvalds * that this buffer is not under async I/O. 5011da177e4SLinus Torvalds * 5021da177e4SLinus Torvalds * The page comes unlocked when it has no locked buffer_async buffers 5031da177e4SLinus Torvalds * left. 5041da177e4SLinus Torvalds * 5051da177e4SLinus Torvalds * PageLocked prevents anyone starting new async I/O reads any of 5061da177e4SLinus Torvalds * the buffers. 5071da177e4SLinus Torvalds * 5081da177e4SLinus Torvalds * PageWriteback is used to prevent simultaneous writeout of the same 5091da177e4SLinus Torvalds * page. 5101da177e4SLinus Torvalds * 5111da177e4SLinus Torvalds * PageLocked prevents anyone from starting writeback of a page which is 5121da177e4SLinus Torvalds * under read I/O (PageWriteback is only ever set against a locked page). 5131da177e4SLinus Torvalds */ 5141da177e4SLinus Torvalds static void mark_buffer_async_read(struct buffer_head *bh) 5151da177e4SLinus Torvalds { 5161da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_read; 5171da177e4SLinus Torvalds set_buffer_async_read(bh); 5181da177e4SLinus Torvalds } 5191da177e4SLinus Torvalds 5201da177e4SLinus Torvalds void mark_buffer_async_write(struct buffer_head *bh) 5211da177e4SLinus Torvalds { 5221da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_write; 5231da177e4SLinus Torvalds set_buffer_async_write(bh); 5241da177e4SLinus Torvalds } 5251da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_async_write); 5261da177e4SLinus Torvalds 5271da177e4SLinus Torvalds 5281da177e4SLinus Torvalds /* 5291da177e4SLinus Torvalds * fs/buffer.c contains helper functions for buffer-backed address space's 5301da177e4SLinus Torvalds * fsync functions. A common requirement for buffer-based filesystems is 5311da177e4SLinus Torvalds * that certain data from the backing blockdev needs to be written out for 5321da177e4SLinus Torvalds * a successful fsync(). For example, ext2 indirect blocks need to be 5331da177e4SLinus Torvalds * written back and waited upon before fsync() returns. 5341da177e4SLinus Torvalds * 5351da177e4SLinus Torvalds * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), 5361da177e4SLinus Torvalds * inode_has_buffers() and invalidate_inode_buffers() are provided for the 5371da177e4SLinus Torvalds * management of a list of dependent buffers at ->i_mapping->private_list. 5381da177e4SLinus Torvalds * 5391da177e4SLinus Torvalds * Locking is a little subtle: try_to_free_buffers() will remove buffers 5401da177e4SLinus Torvalds * from their controlling inode's queue when they are being freed. But 5411da177e4SLinus Torvalds * try_to_free_buffers() will be operating against the *blockdev* mapping 5421da177e4SLinus Torvalds * at the time, not against the S_ISREG file which depends on those buffers. 5431da177e4SLinus Torvalds * So the locking for private_list is via the private_lock in the address_space 5441da177e4SLinus Torvalds * which backs the buffers. Which is different from the address_space 5451da177e4SLinus Torvalds * against which the buffers are listed. So for a particular address_space, 5461da177e4SLinus Torvalds * mapping->private_lock does *not* protect mapping->private_list! In fact, 5471da177e4SLinus Torvalds * mapping->private_list will always be protected by the backing blockdev's 5481da177e4SLinus Torvalds * ->private_lock. 5491da177e4SLinus Torvalds * 5501da177e4SLinus Torvalds * Which introduces a requirement: all buffers on an address_space's 5511da177e4SLinus Torvalds * ->private_list must be from the same address_space: the blockdev's. 5521da177e4SLinus Torvalds * 5531da177e4SLinus Torvalds * address_spaces which do not place buffers at ->private_list via these 5541da177e4SLinus Torvalds * utility functions are free to use private_lock and private_list for 5551da177e4SLinus Torvalds * whatever they want. The only requirement is that list_empty(private_list) 5561da177e4SLinus Torvalds * be true at clear_inode() time. 5571da177e4SLinus Torvalds * 5581da177e4SLinus Torvalds * FIXME: clear_inode should not call invalidate_inode_buffers(). The 5591da177e4SLinus Torvalds * filesystems should do that. invalidate_inode_buffers() should just go 5601da177e4SLinus Torvalds * BUG_ON(!list_empty). 5611da177e4SLinus Torvalds * 5621da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should 5631da177e4SLinus Torvalds * take an address_space, not an inode. And it should be called 5641da177e4SLinus Torvalds * mark_buffer_dirty_fsync() to clearly define why those buffers are being 5651da177e4SLinus Torvalds * queued up. 5661da177e4SLinus Torvalds * 5671da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the 5681da177e4SLinus Torvalds * list if it is already on a list. Because if the buffer is on a list, 5691da177e4SLinus Torvalds * it *must* already be on the right one. If not, the filesystem is being 5701da177e4SLinus Torvalds * silly. This will save a ton of locking. But first we have to ensure 5711da177e4SLinus Torvalds * that buffers are taken *off* the old inode's list when they are freed 5721da177e4SLinus Torvalds * (presumably in truncate). That requires careful auditing of all 5731da177e4SLinus Torvalds * filesystems (do it inside bforget()). It could also be done by bringing 5741da177e4SLinus Torvalds * b_inode back. 5751da177e4SLinus Torvalds */ 5761da177e4SLinus Torvalds 5771da177e4SLinus Torvalds /* 5781da177e4SLinus Torvalds * The buffer's backing address_space's private_lock must be held 5791da177e4SLinus Torvalds */ 5801da177e4SLinus Torvalds static inline void __remove_assoc_queue(struct buffer_head *bh) 5811da177e4SLinus Torvalds { 5821da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 58358ff407bSJan Kara WARN_ON(!bh->b_assoc_map); 58458ff407bSJan Kara if (buffer_write_io_error(bh)) 58558ff407bSJan Kara set_bit(AS_EIO, &bh->b_assoc_map->flags); 58658ff407bSJan Kara bh->b_assoc_map = NULL; 5871da177e4SLinus Torvalds } 5881da177e4SLinus Torvalds 5891da177e4SLinus Torvalds int inode_has_buffers(struct inode *inode) 5901da177e4SLinus Torvalds { 5911da177e4SLinus Torvalds return !list_empty(&inode->i_data.private_list); 5921da177e4SLinus Torvalds } 5931da177e4SLinus Torvalds 5941da177e4SLinus Torvalds /* 5951da177e4SLinus Torvalds * osync is designed to support O_SYNC io. It waits synchronously for 5961da177e4SLinus Torvalds * all already-submitted IO to complete, but does not queue any new 5971da177e4SLinus Torvalds * writes to the disk. 5981da177e4SLinus Torvalds * 5991da177e4SLinus Torvalds * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as 6001da177e4SLinus Torvalds * you dirty the buffers, and then use osync_inode_buffers to wait for 6011da177e4SLinus Torvalds * completion. Any other dirty buffers which are not yet queued for 6021da177e4SLinus Torvalds * write will not be flushed to disk by the osync. 6031da177e4SLinus Torvalds */ 6041da177e4SLinus Torvalds static int osync_buffers_list(spinlock_t *lock, struct list_head *list) 6051da177e4SLinus Torvalds { 6061da177e4SLinus Torvalds struct buffer_head *bh; 6071da177e4SLinus Torvalds struct list_head *p; 6081da177e4SLinus Torvalds int err = 0; 6091da177e4SLinus Torvalds 6101da177e4SLinus Torvalds spin_lock(lock); 6111da177e4SLinus Torvalds repeat: 6121da177e4SLinus Torvalds list_for_each_prev(p, list) { 6131da177e4SLinus Torvalds bh = BH_ENTRY(p); 6141da177e4SLinus Torvalds if (buffer_locked(bh)) { 6151da177e4SLinus Torvalds get_bh(bh); 6161da177e4SLinus Torvalds spin_unlock(lock); 6171da177e4SLinus Torvalds wait_on_buffer(bh); 6181da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 6191da177e4SLinus Torvalds err = -EIO; 6201da177e4SLinus Torvalds brelse(bh); 6211da177e4SLinus Torvalds spin_lock(lock); 6221da177e4SLinus Torvalds goto repeat; 6231da177e4SLinus Torvalds } 6241da177e4SLinus Torvalds } 6251da177e4SLinus Torvalds spin_unlock(lock); 6261da177e4SLinus Torvalds return err; 6271da177e4SLinus Torvalds } 6281da177e4SLinus Torvalds 6291da177e4SLinus Torvalds /** 6301da177e4SLinus Torvalds * sync_mapping_buffers - write out and wait upon a mapping's "associated" 6311da177e4SLinus Torvalds * buffers 63267be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 6331da177e4SLinus Torvalds * 6341da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 6351da177e4SLinus Torvalds * that I/O. 6361da177e4SLinus Torvalds * 63767be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 63867be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 63967be2dd1SMartin Waitz * a successful fsync(). 6401da177e4SLinus Torvalds */ 6411da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 6421da177e4SLinus Torvalds { 6431da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 6441da177e4SLinus Torvalds 6451da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 6461da177e4SLinus Torvalds return 0; 6471da177e4SLinus Torvalds 6481da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 6491da177e4SLinus Torvalds &mapping->private_list); 6501da177e4SLinus Torvalds } 6511da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 6521da177e4SLinus Torvalds 6531da177e4SLinus Torvalds /* 6541da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 6551da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 6561da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 6571da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 6581da177e4SLinus Torvalds */ 6591da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 6601da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 6611da177e4SLinus Torvalds { 6621da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 6631da177e4SLinus Torvalds if (bh) { 6641da177e4SLinus Torvalds if (buffer_dirty(bh)) 6651da177e4SLinus Torvalds ll_rw_block(WRITE, 1, &bh); 6661da177e4SLinus Torvalds put_bh(bh); 6671da177e4SLinus Torvalds } 6681da177e4SLinus Torvalds } 6691da177e4SLinus Torvalds 6701da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 6711da177e4SLinus Torvalds { 6721da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 6731da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 6741da177e4SLinus Torvalds 6751da177e4SLinus Torvalds mark_buffer_dirty(bh); 6761da177e4SLinus Torvalds if (!mapping->assoc_mapping) { 6771da177e4SLinus Torvalds mapping->assoc_mapping = buffer_mapping; 6781da177e4SLinus Torvalds } else { 679e827f923SEric Sesterhenn BUG_ON(mapping->assoc_mapping != buffer_mapping); 6801da177e4SLinus Torvalds } 6811da177e4SLinus Torvalds if (list_empty(&bh->b_assoc_buffers)) { 6821da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 6831da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 6841da177e4SLinus Torvalds &mapping->private_list); 68558ff407bSJan Kara bh->b_assoc_map = mapping; 6861da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 6871da177e4SLinus Torvalds } 6881da177e4SLinus Torvalds } 6891da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 6901da177e4SLinus Torvalds 6911da177e4SLinus Torvalds /* 692787d2214SNick Piggin * Mark the page dirty, and set it dirty in the radix tree, and mark the inode 693787d2214SNick Piggin * dirty. 694787d2214SNick Piggin * 695787d2214SNick Piggin * If warn is true, then emit a warning if the page is not uptodate and has 696787d2214SNick Piggin * not been truncated. 697787d2214SNick Piggin */ 698787d2214SNick Piggin static int __set_page_dirty(struct page *page, 699787d2214SNick Piggin struct address_space *mapping, int warn) 700787d2214SNick Piggin { 701787d2214SNick Piggin if (unlikely(!mapping)) 702787d2214SNick Piggin return !TestSetPageDirty(page); 703787d2214SNick Piggin 704787d2214SNick Piggin if (TestSetPageDirty(page)) 705787d2214SNick Piggin return 0; 706787d2214SNick Piggin 707787d2214SNick Piggin write_lock_irq(&mapping->tree_lock); 708787d2214SNick Piggin if (page->mapping) { /* Race with truncate? */ 709787d2214SNick Piggin WARN_ON_ONCE(warn && !PageUptodate(page)); 710787d2214SNick Piggin 711787d2214SNick Piggin if (mapping_cap_account_dirty(mapping)) { 712787d2214SNick Piggin __inc_zone_page_state(page, NR_FILE_DIRTY); 713*c9e51e41SPeter Zijlstra __inc_bdi_stat(mapping->backing_dev_info, 714*c9e51e41SPeter Zijlstra BDI_RECLAIMABLE); 715787d2214SNick Piggin task_io_account_write(PAGE_CACHE_SIZE); 716787d2214SNick Piggin } 717787d2214SNick Piggin radix_tree_tag_set(&mapping->page_tree, 718787d2214SNick Piggin page_index(page), PAGECACHE_TAG_DIRTY); 719787d2214SNick Piggin } 720787d2214SNick Piggin write_unlock_irq(&mapping->tree_lock); 721787d2214SNick Piggin __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 722787d2214SNick Piggin 723787d2214SNick Piggin return 1; 724787d2214SNick Piggin } 725787d2214SNick Piggin 726787d2214SNick Piggin /* 7271da177e4SLinus Torvalds * Add a page to the dirty page list. 7281da177e4SLinus Torvalds * 7291da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 7301da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 7311da177e4SLinus Torvalds * 7321da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 7331da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 7341da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 7351da177e4SLinus Torvalds * dirty. 7361da177e4SLinus Torvalds * 7371da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 7381da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 7391da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 7401da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 7411da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 7421da177e4SLinus Torvalds * page on the dirty page list. 7431da177e4SLinus Torvalds * 7441da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 7451da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 7461da177e4SLinus Torvalds * added to the page after it was set dirty. 7471da177e4SLinus Torvalds * 7481da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 7491da177e4SLinus Torvalds * address_space though. 7501da177e4SLinus Torvalds */ 7511da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 7521da177e4SLinus Torvalds { 753787d2214SNick Piggin struct address_space *mapping = page_mapping(page); 754ebf7a227SNick Piggin 755ebf7a227SNick Piggin if (unlikely(!mapping)) 756ebf7a227SNick Piggin return !TestSetPageDirty(page); 7571da177e4SLinus Torvalds 7581da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 7591da177e4SLinus Torvalds if (page_has_buffers(page)) { 7601da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 7611da177e4SLinus Torvalds struct buffer_head *bh = head; 7621da177e4SLinus Torvalds 7631da177e4SLinus Torvalds do { 7641da177e4SLinus Torvalds set_buffer_dirty(bh); 7651da177e4SLinus Torvalds bh = bh->b_this_page; 7661da177e4SLinus Torvalds } while (bh != head); 7671da177e4SLinus Torvalds } 7681da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 7691da177e4SLinus Torvalds 770787d2214SNick Piggin return __set_page_dirty(page, mapping, 1); 7711da177e4SLinus Torvalds } 7721da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 7731da177e4SLinus Torvalds 7741da177e4SLinus Torvalds /* 7751da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 7761da177e4SLinus Torvalds * 7771da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 7781da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 7791da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 7801da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 7811da177e4SLinus Torvalds * 7821da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 7831da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 7841da177e4SLinus Torvalds * up, waiting for those writes to complete. 7851da177e4SLinus Torvalds * 7861da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 7871da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 7881da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 7891da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 7901da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 7911da177e4SLinus Torvalds * any newly dirty buffers for write. 7921da177e4SLinus Torvalds */ 7931da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 7941da177e4SLinus Torvalds { 7951da177e4SLinus Torvalds struct buffer_head *bh; 7961da177e4SLinus Torvalds struct list_head tmp; 7971da177e4SLinus Torvalds int err = 0, err2; 7981da177e4SLinus Torvalds 7991da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 8001da177e4SLinus Torvalds 8011da177e4SLinus Torvalds spin_lock(lock); 8021da177e4SLinus Torvalds while (!list_empty(list)) { 8031da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 80458ff407bSJan Kara __remove_assoc_queue(bh); 8051da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 8061da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 8071da177e4SLinus Torvalds if (buffer_dirty(bh)) { 8081da177e4SLinus Torvalds get_bh(bh); 8091da177e4SLinus Torvalds spin_unlock(lock); 8101da177e4SLinus Torvalds /* 8111da177e4SLinus Torvalds * Ensure any pending I/O completes so that 8121da177e4SLinus Torvalds * ll_rw_block() actually writes the current 8131da177e4SLinus Torvalds * contents - it is a noop if I/O is still in 8141da177e4SLinus Torvalds * flight on potentially older contents. 8151da177e4SLinus Torvalds */ 816a7662236SJan Kara ll_rw_block(SWRITE, 1, &bh); 8171da177e4SLinus Torvalds brelse(bh); 8181da177e4SLinus Torvalds spin_lock(lock); 8191da177e4SLinus Torvalds } 8201da177e4SLinus Torvalds } 8211da177e4SLinus Torvalds } 8221da177e4SLinus Torvalds 8231da177e4SLinus Torvalds while (!list_empty(&tmp)) { 8241da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 82558ff407bSJan Kara list_del_init(&bh->b_assoc_buffers); 8261da177e4SLinus Torvalds get_bh(bh); 8271da177e4SLinus Torvalds spin_unlock(lock); 8281da177e4SLinus Torvalds wait_on_buffer(bh); 8291da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 8301da177e4SLinus Torvalds err = -EIO; 8311da177e4SLinus Torvalds brelse(bh); 8321da177e4SLinus Torvalds spin_lock(lock); 8331da177e4SLinus Torvalds } 8341da177e4SLinus Torvalds 8351da177e4SLinus Torvalds spin_unlock(lock); 8361da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 8371da177e4SLinus Torvalds if (err) 8381da177e4SLinus Torvalds return err; 8391da177e4SLinus Torvalds else 8401da177e4SLinus Torvalds return err2; 8411da177e4SLinus Torvalds } 8421da177e4SLinus Torvalds 8431da177e4SLinus Torvalds /* 8441da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 8451da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 8461da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 8471da177e4SLinus Torvalds * 8481da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 8491da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 8501da177e4SLinus Torvalds * for reiserfs. 8511da177e4SLinus Torvalds */ 8521da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 8531da177e4SLinus Torvalds { 8541da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8551da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8561da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 8571da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 8581da177e4SLinus Torvalds 8591da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8601da177e4SLinus Torvalds while (!list_empty(list)) 8611da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 8621da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8631da177e4SLinus Torvalds } 8641da177e4SLinus Torvalds } 8651da177e4SLinus Torvalds 8661da177e4SLinus Torvalds /* 8671da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 8681da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 8691da177e4SLinus Torvalds * 8701da177e4SLinus Torvalds * Returns true if all buffers were removed. 8711da177e4SLinus Torvalds */ 8721da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 8731da177e4SLinus Torvalds { 8741da177e4SLinus Torvalds int ret = 1; 8751da177e4SLinus Torvalds 8761da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8771da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8781da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 8791da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 8801da177e4SLinus Torvalds 8811da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8821da177e4SLinus Torvalds while (!list_empty(list)) { 8831da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 8841da177e4SLinus Torvalds if (buffer_dirty(bh)) { 8851da177e4SLinus Torvalds ret = 0; 8861da177e4SLinus Torvalds break; 8871da177e4SLinus Torvalds } 8881da177e4SLinus Torvalds __remove_assoc_queue(bh); 8891da177e4SLinus Torvalds } 8901da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8911da177e4SLinus Torvalds } 8921da177e4SLinus Torvalds return ret; 8931da177e4SLinus Torvalds } 8941da177e4SLinus Torvalds 8951da177e4SLinus Torvalds /* 8961da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 8971da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 8981da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 8991da177e4SLinus Torvalds * buffers. 9001da177e4SLinus Torvalds * 9011da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 9021da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 9031da177e4SLinus Torvalds */ 9041da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 9051da177e4SLinus Torvalds int retry) 9061da177e4SLinus Torvalds { 9071da177e4SLinus Torvalds struct buffer_head *bh, *head; 9081da177e4SLinus Torvalds long offset; 9091da177e4SLinus Torvalds 9101da177e4SLinus Torvalds try_again: 9111da177e4SLinus Torvalds head = NULL; 9121da177e4SLinus Torvalds offset = PAGE_SIZE; 9131da177e4SLinus Torvalds while ((offset -= size) >= 0) { 9141da177e4SLinus Torvalds bh = alloc_buffer_head(GFP_NOFS); 9151da177e4SLinus Torvalds if (!bh) 9161da177e4SLinus Torvalds goto no_grow; 9171da177e4SLinus Torvalds 9181da177e4SLinus Torvalds bh->b_bdev = NULL; 9191da177e4SLinus Torvalds bh->b_this_page = head; 9201da177e4SLinus Torvalds bh->b_blocknr = -1; 9211da177e4SLinus Torvalds head = bh; 9221da177e4SLinus Torvalds 9231da177e4SLinus Torvalds bh->b_state = 0; 9241da177e4SLinus Torvalds atomic_set(&bh->b_count, 0); 925fc5cd582SChris Mason bh->b_private = NULL; 9261da177e4SLinus Torvalds bh->b_size = size; 9271da177e4SLinus Torvalds 9281da177e4SLinus Torvalds /* Link the buffer to its page */ 9291da177e4SLinus Torvalds set_bh_page(bh, page, offset); 9301da177e4SLinus Torvalds 93101ffe339SNathan Scott init_buffer(bh, NULL, NULL); 9321da177e4SLinus Torvalds } 9331da177e4SLinus Torvalds return head; 9341da177e4SLinus Torvalds /* 9351da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 9361da177e4SLinus Torvalds */ 9371da177e4SLinus Torvalds no_grow: 9381da177e4SLinus Torvalds if (head) { 9391da177e4SLinus Torvalds do { 9401da177e4SLinus Torvalds bh = head; 9411da177e4SLinus Torvalds head = head->b_this_page; 9421da177e4SLinus Torvalds free_buffer_head(bh); 9431da177e4SLinus Torvalds } while (head); 9441da177e4SLinus Torvalds } 9451da177e4SLinus Torvalds 9461da177e4SLinus Torvalds /* 9471da177e4SLinus Torvalds * Return failure for non-async IO requests. Async IO requests 9481da177e4SLinus Torvalds * are not allowed to fail, so we have to wait until buffer heads 9491da177e4SLinus Torvalds * become available. But we don't want tasks sleeping with 9501da177e4SLinus Torvalds * partially complete buffers, so all were released above. 9511da177e4SLinus Torvalds */ 9521da177e4SLinus Torvalds if (!retry) 9531da177e4SLinus Torvalds return NULL; 9541da177e4SLinus Torvalds 9551da177e4SLinus Torvalds /* We're _really_ low on memory. Now we just 9561da177e4SLinus Torvalds * wait for old buffer heads to become free due to 9571da177e4SLinus Torvalds * finishing IO. Since this is an async request and 9581da177e4SLinus Torvalds * the reserve list is empty, we're sure there are 9591da177e4SLinus Torvalds * async buffer heads in use. 9601da177e4SLinus Torvalds */ 9611da177e4SLinus Torvalds free_more_memory(); 9621da177e4SLinus Torvalds goto try_again; 9631da177e4SLinus Torvalds } 9641da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 9651da177e4SLinus Torvalds 9661da177e4SLinus Torvalds static inline void 9671da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 9681da177e4SLinus Torvalds { 9691da177e4SLinus Torvalds struct buffer_head *bh, *tail; 9701da177e4SLinus Torvalds 9711da177e4SLinus Torvalds bh = head; 9721da177e4SLinus Torvalds do { 9731da177e4SLinus Torvalds tail = bh; 9741da177e4SLinus Torvalds bh = bh->b_this_page; 9751da177e4SLinus Torvalds } while (bh); 9761da177e4SLinus Torvalds tail->b_this_page = head; 9771da177e4SLinus Torvalds attach_page_buffers(page, head); 9781da177e4SLinus Torvalds } 9791da177e4SLinus Torvalds 9801da177e4SLinus Torvalds /* 9811da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 9821da177e4SLinus Torvalds */ 9831da177e4SLinus Torvalds static void 9841da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 9851da177e4SLinus Torvalds sector_t block, int size) 9861da177e4SLinus Torvalds { 9871da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 9881da177e4SLinus Torvalds struct buffer_head *bh = head; 9891da177e4SLinus Torvalds int uptodate = PageUptodate(page); 9901da177e4SLinus Torvalds 9911da177e4SLinus Torvalds do { 9921da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 9931da177e4SLinus Torvalds init_buffer(bh, NULL, NULL); 9941da177e4SLinus Torvalds bh->b_bdev = bdev; 9951da177e4SLinus Torvalds bh->b_blocknr = block; 9961da177e4SLinus Torvalds if (uptodate) 9971da177e4SLinus Torvalds set_buffer_uptodate(bh); 9981da177e4SLinus Torvalds set_buffer_mapped(bh); 9991da177e4SLinus Torvalds } 10001da177e4SLinus Torvalds block++; 10011da177e4SLinus Torvalds bh = bh->b_this_page; 10021da177e4SLinus Torvalds } while (bh != head); 10031da177e4SLinus Torvalds } 10041da177e4SLinus Torvalds 10051da177e4SLinus Torvalds /* 10061da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 10071da177e4SLinus Torvalds * 10081da177e4SLinus Torvalds * This is user purely for blockdev mappings. 10091da177e4SLinus Torvalds */ 10101da177e4SLinus Torvalds static struct page * 10111da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 10121da177e4SLinus Torvalds pgoff_t index, int size) 10131da177e4SLinus Torvalds { 10141da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 10151da177e4SLinus Torvalds struct page *page; 10161da177e4SLinus Torvalds struct buffer_head *bh; 10171da177e4SLinus Torvalds 1018ea125892SChristoph Lameter page = find_or_create_page(inode->i_mapping, index, 1019769848c0SMel Gorman (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE); 10201da177e4SLinus Torvalds if (!page) 10211da177e4SLinus Torvalds return NULL; 10221da177e4SLinus Torvalds 1023e827f923SEric Sesterhenn BUG_ON(!PageLocked(page)); 10241da177e4SLinus Torvalds 10251da177e4SLinus Torvalds if (page_has_buffers(page)) { 10261da177e4SLinus Torvalds bh = page_buffers(page); 10271da177e4SLinus Torvalds if (bh->b_size == size) { 10281da177e4SLinus Torvalds init_page_buffers(page, bdev, block, size); 10291da177e4SLinus Torvalds return page; 10301da177e4SLinus Torvalds } 10311da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 10321da177e4SLinus Torvalds goto failed; 10331da177e4SLinus Torvalds } 10341da177e4SLinus Torvalds 10351da177e4SLinus Torvalds /* 10361da177e4SLinus Torvalds * Allocate some buffers for this page 10371da177e4SLinus Torvalds */ 10381da177e4SLinus Torvalds bh = alloc_page_buffers(page, size, 0); 10391da177e4SLinus Torvalds if (!bh) 10401da177e4SLinus Torvalds goto failed; 10411da177e4SLinus Torvalds 10421da177e4SLinus Torvalds /* 10431da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 10441da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 10451da177e4SLinus Torvalds * run under the page lock. 10461da177e4SLinus Torvalds */ 10471da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 10481da177e4SLinus Torvalds link_dev_buffers(page, bh); 10491da177e4SLinus Torvalds init_page_buffers(page, bdev, block, size); 10501da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 10511da177e4SLinus Torvalds return page; 10521da177e4SLinus Torvalds 10531da177e4SLinus Torvalds failed: 10541da177e4SLinus Torvalds BUG(); 10551da177e4SLinus Torvalds unlock_page(page); 10561da177e4SLinus Torvalds page_cache_release(page); 10571da177e4SLinus Torvalds return NULL; 10581da177e4SLinus Torvalds } 10591da177e4SLinus Torvalds 10601da177e4SLinus Torvalds /* 10611da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 10621da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 10631da177e4SLinus Torvalds */ 1064858119e1SArjan van de Ven static int 10651da177e4SLinus Torvalds grow_buffers(struct block_device *bdev, sector_t block, int size) 10661da177e4SLinus Torvalds { 10671da177e4SLinus Torvalds struct page *page; 10681da177e4SLinus Torvalds pgoff_t index; 10691da177e4SLinus Torvalds int sizebits; 10701da177e4SLinus Torvalds 10711da177e4SLinus Torvalds sizebits = -1; 10721da177e4SLinus Torvalds do { 10731da177e4SLinus Torvalds sizebits++; 10741da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 10751da177e4SLinus Torvalds 10761da177e4SLinus Torvalds index = block >> sizebits; 10771da177e4SLinus Torvalds 1078e5657933SAndrew Morton /* 1079e5657933SAndrew Morton * Check for a block which wants to lie outside our maximum possible 1080e5657933SAndrew Morton * pagecache index. (this comparison is done using sector_t types). 1081e5657933SAndrew Morton */ 1082e5657933SAndrew Morton if (unlikely(index != block >> sizebits)) { 1083e5657933SAndrew Morton char b[BDEVNAME_SIZE]; 1084e5657933SAndrew Morton 1085e5657933SAndrew Morton printk(KERN_ERR "%s: requested out-of-range block %llu for " 1086e5657933SAndrew Morton "device %s\n", 1087e5657933SAndrew Morton __FUNCTION__, (unsigned long long)block, 1088e5657933SAndrew Morton bdevname(bdev, b)); 1089e5657933SAndrew Morton return -EIO; 1090e5657933SAndrew Morton } 1091e5657933SAndrew Morton block = index << sizebits; 10921da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 10931da177e4SLinus Torvalds page = grow_dev_page(bdev, block, index, size); 10941da177e4SLinus Torvalds if (!page) 10951da177e4SLinus Torvalds return 0; 10961da177e4SLinus Torvalds unlock_page(page); 10971da177e4SLinus Torvalds page_cache_release(page); 10981da177e4SLinus Torvalds return 1; 10991da177e4SLinus Torvalds } 11001da177e4SLinus Torvalds 110175c96f85SAdrian Bunk static struct buffer_head * 11021da177e4SLinus Torvalds __getblk_slow(struct block_device *bdev, sector_t block, int size) 11031da177e4SLinus Torvalds { 11041da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 11051da177e4SLinus Torvalds if (unlikely(size & (bdev_hardsect_size(bdev)-1) || 11061da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 11071da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 11081da177e4SLinus Torvalds size); 11091da177e4SLinus Torvalds printk(KERN_ERR "hardsect size: %d\n", 11101da177e4SLinus Torvalds bdev_hardsect_size(bdev)); 11111da177e4SLinus Torvalds 11121da177e4SLinus Torvalds dump_stack(); 11131da177e4SLinus Torvalds return NULL; 11141da177e4SLinus Torvalds } 11151da177e4SLinus Torvalds 11161da177e4SLinus Torvalds for (;;) { 11171da177e4SLinus Torvalds struct buffer_head * bh; 1118e5657933SAndrew Morton int ret; 11191da177e4SLinus Torvalds 11201da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 11211da177e4SLinus Torvalds if (bh) 11221da177e4SLinus Torvalds return bh; 11231da177e4SLinus Torvalds 1124e5657933SAndrew Morton ret = grow_buffers(bdev, block, size); 1125e5657933SAndrew Morton if (ret < 0) 1126e5657933SAndrew Morton return NULL; 1127e5657933SAndrew Morton if (ret == 0) 11281da177e4SLinus Torvalds free_more_memory(); 11291da177e4SLinus Torvalds } 11301da177e4SLinus Torvalds } 11311da177e4SLinus Torvalds 11321da177e4SLinus Torvalds /* 11331da177e4SLinus Torvalds * The relationship between dirty buffers and dirty pages: 11341da177e4SLinus Torvalds * 11351da177e4SLinus Torvalds * Whenever a page has any dirty buffers, the page's dirty bit is set, and 11361da177e4SLinus Torvalds * the page is tagged dirty in its radix tree. 11371da177e4SLinus Torvalds * 11381da177e4SLinus Torvalds * At all times, the dirtiness of the buffers represents the dirtiness of 11391da177e4SLinus Torvalds * subsections of the page. If the page has buffers, the page dirty bit is 11401da177e4SLinus Torvalds * merely a hint about the true dirty state. 11411da177e4SLinus Torvalds * 11421da177e4SLinus Torvalds * When a page is set dirty in its entirety, all its buffers are marked dirty 11431da177e4SLinus Torvalds * (if the page has buffers). 11441da177e4SLinus Torvalds * 11451da177e4SLinus Torvalds * When a buffer is marked dirty, its page is dirtied, but the page's other 11461da177e4SLinus Torvalds * buffers are not. 11471da177e4SLinus Torvalds * 11481da177e4SLinus Torvalds * Also. When blockdev buffers are explicitly read with bread(), they 11491da177e4SLinus Torvalds * individually become uptodate. But their backing page remains not 11501da177e4SLinus Torvalds * uptodate - even if all of its buffers are uptodate. A subsequent 11511da177e4SLinus Torvalds * block_read_full_page() against that page will discover all the uptodate 11521da177e4SLinus Torvalds * buffers, will set the page uptodate and will perform no I/O. 11531da177e4SLinus Torvalds */ 11541da177e4SLinus Torvalds 11551da177e4SLinus Torvalds /** 11561da177e4SLinus Torvalds * mark_buffer_dirty - mark a buffer_head as needing writeout 115767be2dd1SMartin Waitz * @bh: the buffer_head to mark dirty 11581da177e4SLinus Torvalds * 11591da177e4SLinus Torvalds * mark_buffer_dirty() will set the dirty bit against the buffer, then set its 11601da177e4SLinus Torvalds * backing page dirty, then tag the page as dirty in its address_space's radix 11611da177e4SLinus Torvalds * tree and then attach the address_space's inode to its superblock's dirty 11621da177e4SLinus Torvalds * inode list. 11631da177e4SLinus Torvalds * 11641da177e4SLinus Torvalds * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, 11651da177e4SLinus Torvalds * mapping->tree_lock and the global inode_lock. 11661da177e4SLinus Torvalds */ 11671da177e4SLinus Torvalds void fastcall mark_buffer_dirty(struct buffer_head *bh) 11681da177e4SLinus Torvalds { 1169787d2214SNick Piggin WARN_ON_ONCE(!buffer_uptodate(bh)); 11701da177e4SLinus Torvalds if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh)) 1171787d2214SNick Piggin __set_page_dirty(bh->b_page, page_mapping(bh->b_page), 0); 11721da177e4SLinus Torvalds } 11731da177e4SLinus Torvalds 11741da177e4SLinus Torvalds /* 11751da177e4SLinus Torvalds * Decrement a buffer_head's reference count. If all buffers against a page 11761da177e4SLinus Torvalds * have zero reference count, are clean and unlocked, and if the page is clean 11771da177e4SLinus Torvalds * and unlocked then try_to_free_buffers() may strip the buffers from the page 11781da177e4SLinus Torvalds * in preparation for freeing it (sometimes, rarely, buffers are removed from 11791da177e4SLinus Torvalds * a page but it ends up not being freed, and buffers may later be reattached). 11801da177e4SLinus Torvalds */ 11811da177e4SLinus Torvalds void __brelse(struct buffer_head * buf) 11821da177e4SLinus Torvalds { 11831da177e4SLinus Torvalds if (atomic_read(&buf->b_count)) { 11841da177e4SLinus Torvalds put_bh(buf); 11851da177e4SLinus Torvalds return; 11861da177e4SLinus Torvalds } 11871da177e4SLinus Torvalds printk(KERN_ERR "VFS: brelse: Trying to free free buffer\n"); 11881da177e4SLinus Torvalds WARN_ON(1); 11891da177e4SLinus Torvalds } 11901da177e4SLinus Torvalds 11911da177e4SLinus Torvalds /* 11921da177e4SLinus Torvalds * bforget() is like brelse(), except it discards any 11931da177e4SLinus Torvalds * potentially dirty data. 11941da177e4SLinus Torvalds */ 11951da177e4SLinus Torvalds void __bforget(struct buffer_head *bh) 11961da177e4SLinus Torvalds { 11971da177e4SLinus Torvalds clear_buffer_dirty(bh); 11981da177e4SLinus Torvalds if (!list_empty(&bh->b_assoc_buffers)) { 11991da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 12001da177e4SLinus Torvalds 12011da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 12021da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 120358ff407bSJan Kara bh->b_assoc_map = NULL; 12041da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 12051da177e4SLinus Torvalds } 12061da177e4SLinus Torvalds __brelse(bh); 12071da177e4SLinus Torvalds } 12081da177e4SLinus Torvalds 12091da177e4SLinus Torvalds static struct buffer_head *__bread_slow(struct buffer_head *bh) 12101da177e4SLinus Torvalds { 12111da177e4SLinus Torvalds lock_buffer(bh); 12121da177e4SLinus Torvalds if (buffer_uptodate(bh)) { 12131da177e4SLinus Torvalds unlock_buffer(bh); 12141da177e4SLinus Torvalds return bh; 12151da177e4SLinus Torvalds } else { 12161da177e4SLinus Torvalds get_bh(bh); 12171da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_sync; 12181da177e4SLinus Torvalds submit_bh(READ, bh); 12191da177e4SLinus Torvalds wait_on_buffer(bh); 12201da177e4SLinus Torvalds if (buffer_uptodate(bh)) 12211da177e4SLinus Torvalds return bh; 12221da177e4SLinus Torvalds } 12231da177e4SLinus Torvalds brelse(bh); 12241da177e4SLinus Torvalds return NULL; 12251da177e4SLinus Torvalds } 12261da177e4SLinus Torvalds 12271da177e4SLinus Torvalds /* 12281da177e4SLinus Torvalds * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). 12291da177e4SLinus Torvalds * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their 12301da177e4SLinus Torvalds * refcount elevated by one when they're in an LRU. A buffer can only appear 12311da177e4SLinus Torvalds * once in a particular CPU's LRU. A single buffer can be present in multiple 12321da177e4SLinus Torvalds * CPU's LRUs at the same time. 12331da177e4SLinus Torvalds * 12341da177e4SLinus Torvalds * This is a transparent caching front-end to sb_bread(), sb_getblk() and 12351da177e4SLinus Torvalds * sb_find_get_block(). 12361da177e4SLinus Torvalds * 12371da177e4SLinus Torvalds * The LRUs themselves only need locking against invalidate_bh_lrus. We use 12381da177e4SLinus Torvalds * a local interrupt disable for that. 12391da177e4SLinus Torvalds */ 12401da177e4SLinus Torvalds 12411da177e4SLinus Torvalds #define BH_LRU_SIZE 8 12421da177e4SLinus Torvalds 12431da177e4SLinus Torvalds struct bh_lru { 12441da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12451da177e4SLinus Torvalds }; 12461da177e4SLinus Torvalds 12471da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; 12481da177e4SLinus Torvalds 12491da177e4SLinus Torvalds #ifdef CONFIG_SMP 12501da177e4SLinus Torvalds #define bh_lru_lock() local_irq_disable() 12511da177e4SLinus Torvalds #define bh_lru_unlock() local_irq_enable() 12521da177e4SLinus Torvalds #else 12531da177e4SLinus Torvalds #define bh_lru_lock() preempt_disable() 12541da177e4SLinus Torvalds #define bh_lru_unlock() preempt_enable() 12551da177e4SLinus Torvalds #endif 12561da177e4SLinus Torvalds 12571da177e4SLinus Torvalds static inline void check_irqs_on(void) 12581da177e4SLinus Torvalds { 12591da177e4SLinus Torvalds #ifdef irqs_disabled 12601da177e4SLinus Torvalds BUG_ON(irqs_disabled()); 12611da177e4SLinus Torvalds #endif 12621da177e4SLinus Torvalds } 12631da177e4SLinus Torvalds 12641da177e4SLinus Torvalds /* 12651da177e4SLinus Torvalds * The LRU management algorithm is dopey-but-simple. Sorry. 12661da177e4SLinus Torvalds */ 12671da177e4SLinus Torvalds static void bh_lru_install(struct buffer_head *bh) 12681da177e4SLinus Torvalds { 12691da177e4SLinus Torvalds struct buffer_head *evictee = NULL; 12701da177e4SLinus Torvalds struct bh_lru *lru; 12711da177e4SLinus Torvalds 12721da177e4SLinus Torvalds check_irqs_on(); 12731da177e4SLinus Torvalds bh_lru_lock(); 12741da177e4SLinus Torvalds lru = &__get_cpu_var(bh_lrus); 12751da177e4SLinus Torvalds if (lru->bhs[0] != bh) { 12761da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12771da177e4SLinus Torvalds int in; 12781da177e4SLinus Torvalds int out = 0; 12791da177e4SLinus Torvalds 12801da177e4SLinus Torvalds get_bh(bh); 12811da177e4SLinus Torvalds bhs[out++] = bh; 12821da177e4SLinus Torvalds for (in = 0; in < BH_LRU_SIZE; in++) { 12831da177e4SLinus Torvalds struct buffer_head *bh2 = lru->bhs[in]; 12841da177e4SLinus Torvalds 12851da177e4SLinus Torvalds if (bh2 == bh) { 12861da177e4SLinus Torvalds __brelse(bh2); 12871da177e4SLinus Torvalds } else { 12881da177e4SLinus Torvalds if (out >= BH_LRU_SIZE) { 12891da177e4SLinus Torvalds BUG_ON(evictee != NULL); 12901da177e4SLinus Torvalds evictee = bh2; 12911da177e4SLinus Torvalds } else { 12921da177e4SLinus Torvalds bhs[out++] = bh2; 12931da177e4SLinus Torvalds } 12941da177e4SLinus Torvalds } 12951da177e4SLinus Torvalds } 12961da177e4SLinus Torvalds while (out < BH_LRU_SIZE) 12971da177e4SLinus Torvalds bhs[out++] = NULL; 12981da177e4SLinus Torvalds memcpy(lru->bhs, bhs, sizeof(bhs)); 12991da177e4SLinus Torvalds } 13001da177e4SLinus Torvalds bh_lru_unlock(); 13011da177e4SLinus Torvalds 13021da177e4SLinus Torvalds if (evictee) 13031da177e4SLinus Torvalds __brelse(evictee); 13041da177e4SLinus Torvalds } 13051da177e4SLinus Torvalds 13061da177e4SLinus Torvalds /* 13071da177e4SLinus Torvalds * Look up the bh in this cpu's LRU. If it's there, move it to the head. 13081da177e4SLinus Torvalds */ 1309858119e1SArjan van de Ven static struct buffer_head * 13103991d3bdSTomasz Kvarsin lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) 13111da177e4SLinus Torvalds { 13121da177e4SLinus Torvalds struct buffer_head *ret = NULL; 13131da177e4SLinus Torvalds struct bh_lru *lru; 13143991d3bdSTomasz Kvarsin unsigned int i; 13151da177e4SLinus Torvalds 13161da177e4SLinus Torvalds check_irqs_on(); 13171da177e4SLinus Torvalds bh_lru_lock(); 13181da177e4SLinus Torvalds lru = &__get_cpu_var(bh_lrus); 13191da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 13201da177e4SLinus Torvalds struct buffer_head *bh = lru->bhs[i]; 13211da177e4SLinus Torvalds 13221da177e4SLinus Torvalds if (bh && bh->b_bdev == bdev && 13231da177e4SLinus Torvalds bh->b_blocknr == block && bh->b_size == size) { 13241da177e4SLinus Torvalds if (i) { 13251da177e4SLinus Torvalds while (i) { 13261da177e4SLinus Torvalds lru->bhs[i] = lru->bhs[i - 1]; 13271da177e4SLinus Torvalds i--; 13281da177e4SLinus Torvalds } 13291da177e4SLinus Torvalds lru->bhs[0] = bh; 13301da177e4SLinus Torvalds } 13311da177e4SLinus Torvalds get_bh(bh); 13321da177e4SLinus Torvalds ret = bh; 13331da177e4SLinus Torvalds break; 13341da177e4SLinus Torvalds } 13351da177e4SLinus Torvalds } 13361da177e4SLinus Torvalds bh_lru_unlock(); 13371da177e4SLinus Torvalds return ret; 13381da177e4SLinus Torvalds } 13391da177e4SLinus Torvalds 13401da177e4SLinus Torvalds /* 13411da177e4SLinus Torvalds * Perform a pagecache lookup for the matching buffer. If it's there, refresh 13421da177e4SLinus Torvalds * it in the LRU and mark it as accessed. If it is not present then return 13431da177e4SLinus Torvalds * NULL 13441da177e4SLinus Torvalds */ 13451da177e4SLinus Torvalds struct buffer_head * 13463991d3bdSTomasz Kvarsin __find_get_block(struct block_device *bdev, sector_t block, unsigned size) 13471da177e4SLinus Torvalds { 13481da177e4SLinus Torvalds struct buffer_head *bh = lookup_bh_lru(bdev, block, size); 13491da177e4SLinus Torvalds 13501da177e4SLinus Torvalds if (bh == NULL) { 1351385fd4c5SCoywolf Qi Hunt bh = __find_get_block_slow(bdev, block); 13521da177e4SLinus Torvalds if (bh) 13531da177e4SLinus Torvalds bh_lru_install(bh); 13541da177e4SLinus Torvalds } 13551da177e4SLinus Torvalds if (bh) 13561da177e4SLinus Torvalds touch_buffer(bh); 13571da177e4SLinus Torvalds return bh; 13581da177e4SLinus Torvalds } 13591da177e4SLinus Torvalds EXPORT_SYMBOL(__find_get_block); 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds /* 13621da177e4SLinus Torvalds * __getblk will locate (and, if necessary, create) the buffer_head 13631da177e4SLinus Torvalds * which corresponds to the passed block_device, block and size. The 13641da177e4SLinus Torvalds * returned buffer has its reference count incremented. 13651da177e4SLinus Torvalds * 13661da177e4SLinus Torvalds * __getblk() cannot fail - it just keeps trying. If you pass it an 13671da177e4SLinus Torvalds * illegal block number, __getblk() will happily return a buffer_head 13681da177e4SLinus Torvalds * which represents the non-existent block. Very weird. 13691da177e4SLinus Torvalds * 13701da177e4SLinus Torvalds * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() 13711da177e4SLinus Torvalds * attempt is failing. FIXME, perhaps? 13721da177e4SLinus Torvalds */ 13731da177e4SLinus Torvalds struct buffer_head * 13743991d3bdSTomasz Kvarsin __getblk(struct block_device *bdev, sector_t block, unsigned size) 13751da177e4SLinus Torvalds { 13761da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, block, size); 13771da177e4SLinus Torvalds 13781da177e4SLinus Torvalds might_sleep(); 13791da177e4SLinus Torvalds if (bh == NULL) 13801da177e4SLinus Torvalds bh = __getblk_slow(bdev, block, size); 13811da177e4SLinus Torvalds return bh; 13821da177e4SLinus Torvalds } 13831da177e4SLinus Torvalds EXPORT_SYMBOL(__getblk); 13841da177e4SLinus Torvalds 13851da177e4SLinus Torvalds /* 13861da177e4SLinus Torvalds * Do async read-ahead on a buffer.. 13871da177e4SLinus Torvalds */ 13883991d3bdSTomasz Kvarsin void __breadahead(struct block_device *bdev, sector_t block, unsigned size) 13891da177e4SLinus Torvalds { 13901da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 1391a3e713b5SAndrew Morton if (likely(bh)) { 13921da177e4SLinus Torvalds ll_rw_block(READA, 1, &bh); 13931da177e4SLinus Torvalds brelse(bh); 13941da177e4SLinus Torvalds } 1395a3e713b5SAndrew Morton } 13961da177e4SLinus Torvalds EXPORT_SYMBOL(__breadahead); 13971da177e4SLinus Torvalds 13981da177e4SLinus Torvalds /** 13991da177e4SLinus Torvalds * __bread() - reads a specified block and returns the bh 140067be2dd1SMartin Waitz * @bdev: the block_device to read from 14011da177e4SLinus Torvalds * @block: number of block 14021da177e4SLinus Torvalds * @size: size (in bytes) to read 14031da177e4SLinus Torvalds * 14041da177e4SLinus Torvalds * Reads a specified block, and returns buffer head that contains it. 14051da177e4SLinus Torvalds * It returns NULL if the block was unreadable. 14061da177e4SLinus Torvalds */ 14071da177e4SLinus Torvalds struct buffer_head * 14083991d3bdSTomasz Kvarsin __bread(struct block_device *bdev, sector_t block, unsigned size) 14091da177e4SLinus Torvalds { 14101da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 14111da177e4SLinus Torvalds 1412a3e713b5SAndrew Morton if (likely(bh) && !buffer_uptodate(bh)) 14131da177e4SLinus Torvalds bh = __bread_slow(bh); 14141da177e4SLinus Torvalds return bh; 14151da177e4SLinus Torvalds } 14161da177e4SLinus Torvalds EXPORT_SYMBOL(__bread); 14171da177e4SLinus Torvalds 14181da177e4SLinus Torvalds /* 14191da177e4SLinus Torvalds * invalidate_bh_lrus() is called rarely - but not only at unmount. 14201da177e4SLinus Torvalds * This doesn't race because it runs in each cpu either in irq 14211da177e4SLinus Torvalds * or with preempt disabled. 14221da177e4SLinus Torvalds */ 14231da177e4SLinus Torvalds static void invalidate_bh_lru(void *arg) 14241da177e4SLinus Torvalds { 14251da177e4SLinus Torvalds struct bh_lru *b = &get_cpu_var(bh_lrus); 14261da177e4SLinus Torvalds int i; 14271da177e4SLinus Torvalds 14281da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 14291da177e4SLinus Torvalds brelse(b->bhs[i]); 14301da177e4SLinus Torvalds b->bhs[i] = NULL; 14311da177e4SLinus Torvalds } 14321da177e4SLinus Torvalds put_cpu_var(bh_lrus); 14331da177e4SLinus Torvalds } 14341da177e4SLinus Torvalds 1435f9a14399SPeter Zijlstra void invalidate_bh_lrus(void) 14361da177e4SLinus Torvalds { 14371da177e4SLinus Torvalds on_each_cpu(invalidate_bh_lru, NULL, 1, 1); 14381da177e4SLinus Torvalds } 14391da177e4SLinus Torvalds 14401da177e4SLinus Torvalds void set_bh_page(struct buffer_head *bh, 14411da177e4SLinus Torvalds struct page *page, unsigned long offset) 14421da177e4SLinus Torvalds { 14431da177e4SLinus Torvalds bh->b_page = page; 1444e827f923SEric Sesterhenn BUG_ON(offset >= PAGE_SIZE); 14451da177e4SLinus Torvalds if (PageHighMem(page)) 14461da177e4SLinus Torvalds /* 14471da177e4SLinus Torvalds * This catches illegal uses and preserves the offset: 14481da177e4SLinus Torvalds */ 14491da177e4SLinus Torvalds bh->b_data = (char *)(0 + offset); 14501da177e4SLinus Torvalds else 14511da177e4SLinus Torvalds bh->b_data = page_address(page) + offset; 14521da177e4SLinus Torvalds } 14531da177e4SLinus Torvalds EXPORT_SYMBOL(set_bh_page); 14541da177e4SLinus Torvalds 14551da177e4SLinus Torvalds /* 14561da177e4SLinus Torvalds * Called when truncating a buffer on a page completely. 14571da177e4SLinus Torvalds */ 1458858119e1SArjan van de Ven static void discard_buffer(struct buffer_head * bh) 14591da177e4SLinus Torvalds { 14601da177e4SLinus Torvalds lock_buffer(bh); 14611da177e4SLinus Torvalds clear_buffer_dirty(bh); 14621da177e4SLinus Torvalds bh->b_bdev = NULL; 14631da177e4SLinus Torvalds clear_buffer_mapped(bh); 14641da177e4SLinus Torvalds clear_buffer_req(bh); 14651da177e4SLinus Torvalds clear_buffer_new(bh); 14661da177e4SLinus Torvalds clear_buffer_delay(bh); 146733a266ddSDavid Chinner clear_buffer_unwritten(bh); 14681da177e4SLinus Torvalds unlock_buffer(bh); 14691da177e4SLinus Torvalds } 14701da177e4SLinus Torvalds 14711da177e4SLinus Torvalds /** 14721da177e4SLinus Torvalds * block_invalidatepage - invalidate part of all of a buffer-backed page 14731da177e4SLinus Torvalds * 14741da177e4SLinus Torvalds * @page: the page which is affected 14751da177e4SLinus Torvalds * @offset: the index of the truncation point 14761da177e4SLinus Torvalds * 14771da177e4SLinus Torvalds * block_invalidatepage() is called when all or part of the page has become 14781da177e4SLinus Torvalds * invalidatedby a truncate operation. 14791da177e4SLinus Torvalds * 14801da177e4SLinus Torvalds * block_invalidatepage() does not have to release all buffers, but it must 14811da177e4SLinus Torvalds * ensure that no dirty buffer is left outside @offset and that no I/O 14821da177e4SLinus Torvalds * is underway against any of the blocks which are outside the truncation 14831da177e4SLinus Torvalds * point. Because the caller is about to free (and possibly reuse) those 14841da177e4SLinus Torvalds * blocks on-disk. 14851da177e4SLinus Torvalds */ 14862ff28e22SNeilBrown void block_invalidatepage(struct page *page, unsigned long offset) 14871da177e4SLinus Torvalds { 14881da177e4SLinus Torvalds struct buffer_head *head, *bh, *next; 14891da177e4SLinus Torvalds unsigned int curr_off = 0; 14901da177e4SLinus Torvalds 14911da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 14921da177e4SLinus Torvalds if (!page_has_buffers(page)) 14931da177e4SLinus Torvalds goto out; 14941da177e4SLinus Torvalds 14951da177e4SLinus Torvalds head = page_buffers(page); 14961da177e4SLinus Torvalds bh = head; 14971da177e4SLinus Torvalds do { 14981da177e4SLinus Torvalds unsigned int next_off = curr_off + bh->b_size; 14991da177e4SLinus Torvalds next = bh->b_this_page; 15001da177e4SLinus Torvalds 15011da177e4SLinus Torvalds /* 15021da177e4SLinus Torvalds * is this block fully invalidated? 15031da177e4SLinus Torvalds */ 15041da177e4SLinus Torvalds if (offset <= curr_off) 15051da177e4SLinus Torvalds discard_buffer(bh); 15061da177e4SLinus Torvalds curr_off = next_off; 15071da177e4SLinus Torvalds bh = next; 15081da177e4SLinus Torvalds } while (bh != head); 15091da177e4SLinus Torvalds 15101da177e4SLinus Torvalds /* 15111da177e4SLinus Torvalds * We release buffers only if the entire page is being invalidated. 15121da177e4SLinus Torvalds * The get_block cached value has been unconditionally invalidated, 15131da177e4SLinus Torvalds * so real IO is not possible anymore. 15141da177e4SLinus Torvalds */ 15151da177e4SLinus Torvalds if (offset == 0) 15162ff28e22SNeilBrown try_to_release_page(page, 0); 15171da177e4SLinus Torvalds out: 15182ff28e22SNeilBrown return; 15191da177e4SLinus Torvalds } 15201da177e4SLinus Torvalds EXPORT_SYMBOL(block_invalidatepage); 15211da177e4SLinus Torvalds 15221da177e4SLinus Torvalds /* 15231da177e4SLinus Torvalds * We attach and possibly dirty the buffers atomically wrt 15241da177e4SLinus Torvalds * __set_page_dirty_buffers() via private_lock. try_to_free_buffers 15251da177e4SLinus Torvalds * is already excluded via the page lock. 15261da177e4SLinus Torvalds */ 15271da177e4SLinus Torvalds void create_empty_buffers(struct page *page, 15281da177e4SLinus Torvalds unsigned long blocksize, unsigned long b_state) 15291da177e4SLinus Torvalds { 15301da177e4SLinus Torvalds struct buffer_head *bh, *head, *tail; 15311da177e4SLinus Torvalds 15321da177e4SLinus Torvalds head = alloc_page_buffers(page, blocksize, 1); 15331da177e4SLinus Torvalds bh = head; 15341da177e4SLinus Torvalds do { 15351da177e4SLinus Torvalds bh->b_state |= b_state; 15361da177e4SLinus Torvalds tail = bh; 15371da177e4SLinus Torvalds bh = bh->b_this_page; 15381da177e4SLinus Torvalds } while (bh); 15391da177e4SLinus Torvalds tail->b_this_page = head; 15401da177e4SLinus Torvalds 15411da177e4SLinus Torvalds spin_lock(&page->mapping->private_lock); 15421da177e4SLinus Torvalds if (PageUptodate(page) || PageDirty(page)) { 15431da177e4SLinus Torvalds bh = head; 15441da177e4SLinus Torvalds do { 15451da177e4SLinus Torvalds if (PageDirty(page)) 15461da177e4SLinus Torvalds set_buffer_dirty(bh); 15471da177e4SLinus Torvalds if (PageUptodate(page)) 15481da177e4SLinus Torvalds set_buffer_uptodate(bh); 15491da177e4SLinus Torvalds bh = bh->b_this_page; 15501da177e4SLinus Torvalds } while (bh != head); 15511da177e4SLinus Torvalds } 15521da177e4SLinus Torvalds attach_page_buffers(page, head); 15531da177e4SLinus Torvalds spin_unlock(&page->mapping->private_lock); 15541da177e4SLinus Torvalds } 15551da177e4SLinus Torvalds EXPORT_SYMBOL(create_empty_buffers); 15561da177e4SLinus Torvalds 15571da177e4SLinus Torvalds /* 15581da177e4SLinus Torvalds * We are taking a block for data and we don't want any output from any 15591da177e4SLinus Torvalds * buffer-cache aliases starting from return from that function and 15601da177e4SLinus Torvalds * until the moment when something will explicitly mark the buffer 15611da177e4SLinus Torvalds * dirty (hopefully that will not happen until we will free that block ;-) 15621da177e4SLinus Torvalds * We don't even need to mark it not-uptodate - nobody can expect 15631da177e4SLinus Torvalds * anything from a newly allocated buffer anyway. We used to used 15641da177e4SLinus Torvalds * unmap_buffer() for such invalidation, but that was wrong. We definitely 15651da177e4SLinus Torvalds * don't want to mark the alias unmapped, for example - it would confuse 15661da177e4SLinus Torvalds * anyone who might pick it with bread() afterwards... 15671da177e4SLinus Torvalds * 15681da177e4SLinus Torvalds * Also.. Note that bforget() doesn't lock the buffer. So there can 15691da177e4SLinus Torvalds * be writeout I/O going on against recently-freed buffers. We don't 15701da177e4SLinus Torvalds * wait on that I/O in bforget() - it's more efficient to wait on the I/O 15711da177e4SLinus Torvalds * only if we really need to. That happens here. 15721da177e4SLinus Torvalds */ 15731da177e4SLinus Torvalds void unmap_underlying_metadata(struct block_device *bdev, sector_t block) 15741da177e4SLinus Torvalds { 15751da177e4SLinus Torvalds struct buffer_head *old_bh; 15761da177e4SLinus Torvalds 15771da177e4SLinus Torvalds might_sleep(); 15781da177e4SLinus Torvalds 1579385fd4c5SCoywolf Qi Hunt old_bh = __find_get_block_slow(bdev, block); 15801da177e4SLinus Torvalds if (old_bh) { 15811da177e4SLinus Torvalds clear_buffer_dirty(old_bh); 15821da177e4SLinus Torvalds wait_on_buffer(old_bh); 15831da177e4SLinus Torvalds clear_buffer_req(old_bh); 15841da177e4SLinus Torvalds __brelse(old_bh); 15851da177e4SLinus Torvalds } 15861da177e4SLinus Torvalds } 15871da177e4SLinus Torvalds EXPORT_SYMBOL(unmap_underlying_metadata); 15881da177e4SLinus Torvalds 15891da177e4SLinus Torvalds /* 15901da177e4SLinus Torvalds * NOTE! All mapped/uptodate combinations are valid: 15911da177e4SLinus Torvalds * 15921da177e4SLinus Torvalds * Mapped Uptodate Meaning 15931da177e4SLinus Torvalds * 15941da177e4SLinus Torvalds * No No "unknown" - must do get_block() 15951da177e4SLinus Torvalds * No Yes "hole" - zero-filled 15961da177e4SLinus Torvalds * Yes No "allocated" - allocated on disk, not read in 15971da177e4SLinus Torvalds * Yes Yes "valid" - allocated and up-to-date in memory. 15981da177e4SLinus Torvalds * 15991da177e4SLinus Torvalds * "Dirty" is valid only with the last case (mapped+uptodate). 16001da177e4SLinus Torvalds */ 16011da177e4SLinus Torvalds 16021da177e4SLinus Torvalds /* 16031da177e4SLinus Torvalds * While block_write_full_page is writing back the dirty buffers under 16041da177e4SLinus Torvalds * the page lock, whoever dirtied the buffers may decide to clean them 16051da177e4SLinus Torvalds * again at any time. We handle that by only looking at the buffer 16061da177e4SLinus Torvalds * state inside lock_buffer(). 16071da177e4SLinus Torvalds * 16081da177e4SLinus Torvalds * If block_write_full_page() is called for regular writeback 16091da177e4SLinus Torvalds * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a 16101da177e4SLinus Torvalds * locked buffer. This only can happen if someone has written the buffer 16111da177e4SLinus Torvalds * directly, with submit_bh(). At the address_space level PageWriteback 16121da177e4SLinus Torvalds * prevents this contention from occurring. 16131da177e4SLinus Torvalds */ 16141da177e4SLinus Torvalds static int __block_write_full_page(struct inode *inode, struct page *page, 16151da177e4SLinus Torvalds get_block_t *get_block, struct writeback_control *wbc) 16161da177e4SLinus Torvalds { 16171da177e4SLinus Torvalds int err; 16181da177e4SLinus Torvalds sector_t block; 16191da177e4SLinus Torvalds sector_t last_block; 1620f0fbd5fcSAndrew Morton struct buffer_head *bh, *head; 1621b0cf2321SBadari Pulavarty const unsigned blocksize = 1 << inode->i_blkbits; 16221da177e4SLinus Torvalds int nr_underway = 0; 16231da177e4SLinus Torvalds 16241da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 16251da177e4SLinus Torvalds 16261da177e4SLinus Torvalds last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; 16271da177e4SLinus Torvalds 16281da177e4SLinus Torvalds if (!page_has_buffers(page)) { 1629b0cf2321SBadari Pulavarty create_empty_buffers(page, blocksize, 16301da177e4SLinus Torvalds (1 << BH_Dirty)|(1 << BH_Uptodate)); 16311da177e4SLinus Torvalds } 16321da177e4SLinus Torvalds 16331da177e4SLinus Torvalds /* 16341da177e4SLinus Torvalds * Be very careful. We have no exclusion from __set_page_dirty_buffers 16351da177e4SLinus Torvalds * here, and the (potentially unmapped) buffers may become dirty at 16361da177e4SLinus Torvalds * any time. If a buffer becomes dirty here after we've inspected it 16371da177e4SLinus Torvalds * then we just miss that fact, and the page stays dirty. 16381da177e4SLinus Torvalds * 16391da177e4SLinus Torvalds * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; 16401da177e4SLinus Torvalds * handle that here by just cleaning them. 16411da177e4SLinus Torvalds */ 16421da177e4SLinus Torvalds 164354b21a79SAndrew Morton block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 16441da177e4SLinus Torvalds head = page_buffers(page); 16451da177e4SLinus Torvalds bh = head; 16461da177e4SLinus Torvalds 16471da177e4SLinus Torvalds /* 16481da177e4SLinus Torvalds * Get all the dirty buffers mapped to disk addresses and 16491da177e4SLinus Torvalds * handle any aliases from the underlying blockdev's mapping. 16501da177e4SLinus Torvalds */ 16511da177e4SLinus Torvalds do { 16521da177e4SLinus Torvalds if (block > last_block) { 16531da177e4SLinus Torvalds /* 16541da177e4SLinus Torvalds * mapped buffers outside i_size will occur, because 16551da177e4SLinus Torvalds * this page can be outside i_size when there is a 16561da177e4SLinus Torvalds * truncate in progress. 16571da177e4SLinus Torvalds */ 16581da177e4SLinus Torvalds /* 16591da177e4SLinus Torvalds * The buffer was zeroed by block_write_full_page() 16601da177e4SLinus Torvalds */ 16611da177e4SLinus Torvalds clear_buffer_dirty(bh); 16621da177e4SLinus Torvalds set_buffer_uptodate(bh); 16631da177e4SLinus Torvalds } else if (!buffer_mapped(bh) && buffer_dirty(bh)) { 1664b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 16651da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 16661da177e4SLinus Torvalds if (err) 16671da177e4SLinus Torvalds goto recover; 16681da177e4SLinus Torvalds if (buffer_new(bh)) { 16691da177e4SLinus Torvalds /* blockdev mappings never come here */ 16701da177e4SLinus Torvalds clear_buffer_new(bh); 16711da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 16721da177e4SLinus Torvalds bh->b_blocknr); 16731da177e4SLinus Torvalds } 16741da177e4SLinus Torvalds } 16751da177e4SLinus Torvalds bh = bh->b_this_page; 16761da177e4SLinus Torvalds block++; 16771da177e4SLinus Torvalds } while (bh != head); 16781da177e4SLinus Torvalds 16791da177e4SLinus Torvalds do { 16801da177e4SLinus Torvalds if (!buffer_mapped(bh)) 16811da177e4SLinus Torvalds continue; 16821da177e4SLinus Torvalds /* 16831da177e4SLinus Torvalds * If it's a fully non-blocking write attempt and we cannot 16841da177e4SLinus Torvalds * lock the buffer then redirty the page. Note that this can 16851da177e4SLinus Torvalds * potentially cause a busy-wait loop from pdflush and kswapd 16861da177e4SLinus Torvalds * activity, but those code paths have their own higher-level 16871da177e4SLinus Torvalds * throttling. 16881da177e4SLinus Torvalds */ 16891da177e4SLinus Torvalds if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { 16901da177e4SLinus Torvalds lock_buffer(bh); 16911da177e4SLinus Torvalds } else if (test_set_buffer_locked(bh)) { 16921da177e4SLinus Torvalds redirty_page_for_writepage(wbc, page); 16931da177e4SLinus Torvalds continue; 16941da177e4SLinus Torvalds } 16951da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 16961da177e4SLinus Torvalds mark_buffer_async_write(bh); 16971da177e4SLinus Torvalds } else { 16981da177e4SLinus Torvalds unlock_buffer(bh); 16991da177e4SLinus Torvalds } 17001da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17011da177e4SLinus Torvalds 17021da177e4SLinus Torvalds /* 17031da177e4SLinus Torvalds * The page and its buffers are protected by PageWriteback(), so we can 17041da177e4SLinus Torvalds * drop the bh refcounts early. 17051da177e4SLinus Torvalds */ 17061da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17071da177e4SLinus Torvalds set_page_writeback(page); 17081da177e4SLinus Torvalds 17091da177e4SLinus Torvalds do { 17101da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17111da177e4SLinus Torvalds if (buffer_async_write(bh)) { 17121da177e4SLinus Torvalds submit_bh(WRITE, bh); 17131da177e4SLinus Torvalds nr_underway++; 1714ad576e63SNick Piggin } 17151da177e4SLinus Torvalds bh = next; 17161da177e4SLinus Torvalds } while (bh != head); 171705937baaSAndrew Morton unlock_page(page); 17181da177e4SLinus Torvalds 17191da177e4SLinus Torvalds err = 0; 17201da177e4SLinus Torvalds done: 17211da177e4SLinus Torvalds if (nr_underway == 0) { 17221da177e4SLinus Torvalds /* 17231da177e4SLinus Torvalds * The page was marked dirty, but the buffers were 17241da177e4SLinus Torvalds * clean. Someone wrote them back by hand with 17251da177e4SLinus Torvalds * ll_rw_block/submit_bh. A rare case. 17261da177e4SLinus Torvalds */ 17271da177e4SLinus Torvalds end_page_writeback(page); 17283d67f2d7SNick Piggin 17291da177e4SLinus Torvalds /* 17301da177e4SLinus Torvalds * The page and buffer_heads can be released at any time from 17311da177e4SLinus Torvalds * here on. 17321da177e4SLinus Torvalds */ 17331da177e4SLinus Torvalds wbc->pages_skipped++; /* We didn't write this page */ 17341da177e4SLinus Torvalds } 17351da177e4SLinus Torvalds return err; 17361da177e4SLinus Torvalds 17371da177e4SLinus Torvalds recover: 17381da177e4SLinus Torvalds /* 17391da177e4SLinus Torvalds * ENOSPC, or some other error. We may already have added some 17401da177e4SLinus Torvalds * blocks to the file, so we need to write these out to avoid 17411da177e4SLinus Torvalds * exposing stale data. 17421da177e4SLinus Torvalds * The page is currently locked and not marked for writeback 17431da177e4SLinus Torvalds */ 17441da177e4SLinus Torvalds bh = head; 17451da177e4SLinus Torvalds /* Recovery: lock and submit the mapped buffers */ 17461da177e4SLinus Torvalds do { 17471da177e4SLinus Torvalds if (buffer_mapped(bh) && buffer_dirty(bh)) { 17481da177e4SLinus Torvalds lock_buffer(bh); 17491da177e4SLinus Torvalds mark_buffer_async_write(bh); 17501da177e4SLinus Torvalds } else { 17511da177e4SLinus Torvalds /* 17521da177e4SLinus Torvalds * The buffer may have been set dirty during 17531da177e4SLinus Torvalds * attachment to a dirty page. 17541da177e4SLinus Torvalds */ 17551da177e4SLinus Torvalds clear_buffer_dirty(bh); 17561da177e4SLinus Torvalds } 17571da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17581da177e4SLinus Torvalds SetPageError(page); 17591da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17607e4c3690SAndrew Morton mapping_set_error(page->mapping, err); 17611da177e4SLinus Torvalds set_page_writeback(page); 17621da177e4SLinus Torvalds do { 17631da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17641da177e4SLinus Torvalds if (buffer_async_write(bh)) { 17651da177e4SLinus Torvalds clear_buffer_dirty(bh); 17661da177e4SLinus Torvalds submit_bh(WRITE, bh); 17671da177e4SLinus Torvalds nr_underway++; 1768ad576e63SNick Piggin } 17691da177e4SLinus Torvalds bh = next; 17701da177e4SLinus Torvalds } while (bh != head); 1771ffda9d30SNick Piggin unlock_page(page); 17721da177e4SLinus Torvalds goto done; 17731da177e4SLinus Torvalds } 17741da177e4SLinus Torvalds 1775afddba49SNick Piggin /* 1776afddba49SNick Piggin * If a page has any new buffers, zero them out here, and mark them uptodate 1777afddba49SNick Piggin * and dirty so they'll be written out (in order to prevent uninitialised 1778afddba49SNick Piggin * block data from leaking). And clear the new bit. 1779afddba49SNick Piggin */ 1780afddba49SNick Piggin void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) 1781afddba49SNick Piggin { 1782afddba49SNick Piggin unsigned int block_start, block_end; 1783afddba49SNick Piggin struct buffer_head *head, *bh; 1784afddba49SNick Piggin 1785afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1786afddba49SNick Piggin if (!page_has_buffers(page)) 1787afddba49SNick Piggin return; 1788afddba49SNick Piggin 1789afddba49SNick Piggin bh = head = page_buffers(page); 1790afddba49SNick Piggin block_start = 0; 1791afddba49SNick Piggin do { 1792afddba49SNick Piggin block_end = block_start + bh->b_size; 1793afddba49SNick Piggin 1794afddba49SNick Piggin if (buffer_new(bh)) { 1795afddba49SNick Piggin if (block_end > from && block_start < to) { 1796afddba49SNick Piggin if (!PageUptodate(page)) { 1797afddba49SNick Piggin unsigned start, size; 1798afddba49SNick Piggin 1799afddba49SNick Piggin start = max(from, block_start); 1800afddba49SNick Piggin size = min(to, block_end) - start; 1801afddba49SNick Piggin 1802afddba49SNick Piggin zero_user_page(page, start, size, KM_USER0); 1803afddba49SNick Piggin set_buffer_uptodate(bh); 1804afddba49SNick Piggin } 1805afddba49SNick Piggin 1806afddba49SNick Piggin clear_buffer_new(bh); 1807afddba49SNick Piggin mark_buffer_dirty(bh); 1808afddba49SNick Piggin } 1809afddba49SNick Piggin } 1810afddba49SNick Piggin 1811afddba49SNick Piggin block_start = block_end; 1812afddba49SNick Piggin bh = bh->b_this_page; 1813afddba49SNick Piggin } while (bh != head); 1814afddba49SNick Piggin } 1815afddba49SNick Piggin EXPORT_SYMBOL(page_zero_new_buffers); 1816afddba49SNick Piggin 18171da177e4SLinus Torvalds static int __block_prepare_write(struct inode *inode, struct page *page, 18181da177e4SLinus Torvalds unsigned from, unsigned to, get_block_t *get_block) 18191da177e4SLinus Torvalds { 18201da177e4SLinus Torvalds unsigned block_start, block_end; 18211da177e4SLinus Torvalds sector_t block; 18221da177e4SLinus Torvalds int err = 0; 18231da177e4SLinus Torvalds unsigned blocksize, bbits; 18241da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 18251da177e4SLinus Torvalds 18261da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 18271da177e4SLinus Torvalds BUG_ON(from > PAGE_CACHE_SIZE); 18281da177e4SLinus Torvalds BUG_ON(to > PAGE_CACHE_SIZE); 18291da177e4SLinus Torvalds BUG_ON(from > to); 18301da177e4SLinus Torvalds 18311da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 18321da177e4SLinus Torvalds if (!page_has_buffers(page)) 18331da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 18341da177e4SLinus Torvalds head = page_buffers(page); 18351da177e4SLinus Torvalds 18361da177e4SLinus Torvalds bbits = inode->i_blkbits; 18371da177e4SLinus Torvalds block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 18381da177e4SLinus Torvalds 18391da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 18401da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 18411da177e4SLinus Torvalds block_end = block_start + blocksize; 18421da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 18431da177e4SLinus Torvalds if (PageUptodate(page)) { 18441da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 18451da177e4SLinus Torvalds set_buffer_uptodate(bh); 18461da177e4SLinus Torvalds } 18471da177e4SLinus Torvalds continue; 18481da177e4SLinus Torvalds } 18491da177e4SLinus Torvalds if (buffer_new(bh)) 18501da177e4SLinus Torvalds clear_buffer_new(bh); 18511da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 1852b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 18531da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 18541da177e4SLinus Torvalds if (err) 1855f3ddbdc6SNick Piggin break; 18561da177e4SLinus Torvalds if (buffer_new(bh)) { 18571da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 18581da177e4SLinus Torvalds bh->b_blocknr); 18591da177e4SLinus Torvalds if (PageUptodate(page)) { 1860637aff46SNick Piggin clear_buffer_new(bh); 18611da177e4SLinus Torvalds set_buffer_uptodate(bh); 1862637aff46SNick Piggin mark_buffer_dirty(bh); 18631da177e4SLinus Torvalds continue; 18641da177e4SLinus Torvalds } 18651da177e4SLinus Torvalds if (block_end > to || block_start < from) { 18661da177e4SLinus Torvalds void *kaddr; 18671da177e4SLinus Torvalds 18681da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 18691da177e4SLinus Torvalds if (block_end > to) 18701da177e4SLinus Torvalds memset(kaddr+to, 0, 18711da177e4SLinus Torvalds block_end-to); 18721da177e4SLinus Torvalds if (block_start < from) 18731da177e4SLinus Torvalds memset(kaddr+block_start, 18741da177e4SLinus Torvalds 0, from-block_start); 18751da177e4SLinus Torvalds flush_dcache_page(page); 18761da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 18771da177e4SLinus Torvalds } 18781da177e4SLinus Torvalds continue; 18791da177e4SLinus Torvalds } 18801da177e4SLinus Torvalds } 18811da177e4SLinus Torvalds if (PageUptodate(page)) { 18821da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 18831da177e4SLinus Torvalds set_buffer_uptodate(bh); 18841da177e4SLinus Torvalds continue; 18851da177e4SLinus Torvalds } 18861da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 188733a266ddSDavid Chinner !buffer_unwritten(bh) && 18881da177e4SLinus Torvalds (block_start < from || block_end > to)) { 18891da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 18901da177e4SLinus Torvalds *wait_bh++=bh; 18911da177e4SLinus Torvalds } 18921da177e4SLinus Torvalds } 18931da177e4SLinus Torvalds /* 18941da177e4SLinus Torvalds * If we issued read requests - let them complete. 18951da177e4SLinus Torvalds */ 18961da177e4SLinus Torvalds while(wait_bh > wait) { 18971da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 18981da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 1899f3ddbdc6SNick Piggin err = -EIO; 19001da177e4SLinus Torvalds } 1901afddba49SNick Piggin if (unlikely(err)) 1902afddba49SNick Piggin page_zero_new_buffers(page, from, to); 19031da177e4SLinus Torvalds return err; 19041da177e4SLinus Torvalds } 19051da177e4SLinus Torvalds 19061da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 19071da177e4SLinus Torvalds unsigned from, unsigned to) 19081da177e4SLinus Torvalds { 19091da177e4SLinus Torvalds unsigned block_start, block_end; 19101da177e4SLinus Torvalds int partial = 0; 19111da177e4SLinus Torvalds unsigned blocksize; 19121da177e4SLinus Torvalds struct buffer_head *bh, *head; 19131da177e4SLinus Torvalds 19141da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 19151da177e4SLinus Torvalds 19161da177e4SLinus Torvalds for(bh = head = page_buffers(page), block_start = 0; 19171da177e4SLinus Torvalds bh != head || !block_start; 19181da177e4SLinus Torvalds block_start=block_end, bh = bh->b_this_page) { 19191da177e4SLinus Torvalds block_end = block_start + blocksize; 19201da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19211da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19221da177e4SLinus Torvalds partial = 1; 19231da177e4SLinus Torvalds } else { 19241da177e4SLinus Torvalds set_buffer_uptodate(bh); 19251da177e4SLinus Torvalds mark_buffer_dirty(bh); 19261da177e4SLinus Torvalds } 1927afddba49SNick Piggin clear_buffer_new(bh); 19281da177e4SLinus Torvalds } 19291da177e4SLinus Torvalds 19301da177e4SLinus Torvalds /* 19311da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 19321da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 19331da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 19341da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 19351da177e4SLinus Torvalds */ 19361da177e4SLinus Torvalds if (!partial) 19371da177e4SLinus Torvalds SetPageUptodate(page); 19381da177e4SLinus Torvalds return 0; 19391da177e4SLinus Torvalds } 19401da177e4SLinus Torvalds 19411da177e4SLinus Torvalds /* 1942afddba49SNick Piggin * block_write_begin takes care of the basic task of block allocation and 1943afddba49SNick Piggin * bringing partial write blocks uptodate first. 1944afddba49SNick Piggin * 1945afddba49SNick Piggin * If *pagep is not NULL, then block_write_begin uses the locked page 1946afddba49SNick Piggin * at *pagep rather than allocating its own. In this case, the page will 1947afddba49SNick Piggin * not be unlocked or deallocated on failure. 1948afddba49SNick Piggin */ 1949afddba49SNick Piggin int block_write_begin(struct file *file, struct address_space *mapping, 1950afddba49SNick Piggin loff_t pos, unsigned len, unsigned flags, 1951afddba49SNick Piggin struct page **pagep, void **fsdata, 1952afddba49SNick Piggin get_block_t *get_block) 1953afddba49SNick Piggin { 1954afddba49SNick Piggin struct inode *inode = mapping->host; 1955afddba49SNick Piggin int status = 0; 1956afddba49SNick Piggin struct page *page; 1957afddba49SNick Piggin pgoff_t index; 1958afddba49SNick Piggin unsigned start, end; 1959afddba49SNick Piggin int ownpage = 0; 1960afddba49SNick Piggin 1961afddba49SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 1962afddba49SNick Piggin start = pos & (PAGE_CACHE_SIZE - 1); 1963afddba49SNick Piggin end = start + len; 1964afddba49SNick Piggin 1965afddba49SNick Piggin page = *pagep; 1966afddba49SNick Piggin if (page == NULL) { 1967afddba49SNick Piggin ownpage = 1; 1968afddba49SNick Piggin page = __grab_cache_page(mapping, index); 1969afddba49SNick Piggin if (!page) { 1970afddba49SNick Piggin status = -ENOMEM; 1971afddba49SNick Piggin goto out; 1972afddba49SNick Piggin } 1973afddba49SNick Piggin *pagep = page; 1974afddba49SNick Piggin } else 1975afddba49SNick Piggin BUG_ON(!PageLocked(page)); 1976afddba49SNick Piggin 1977afddba49SNick Piggin status = __block_prepare_write(inode, page, start, end, get_block); 1978afddba49SNick Piggin if (unlikely(status)) { 1979afddba49SNick Piggin ClearPageUptodate(page); 1980afddba49SNick Piggin 1981afddba49SNick Piggin if (ownpage) { 1982afddba49SNick Piggin unlock_page(page); 1983afddba49SNick Piggin page_cache_release(page); 1984afddba49SNick Piggin *pagep = NULL; 1985afddba49SNick Piggin 1986afddba49SNick Piggin /* 1987afddba49SNick Piggin * prepare_write() may have instantiated a few blocks 1988afddba49SNick Piggin * outside i_size. Trim these off again. Don't need 1989afddba49SNick Piggin * i_size_read because we hold i_mutex. 1990afddba49SNick Piggin */ 1991afddba49SNick Piggin if (pos + len > inode->i_size) 1992afddba49SNick Piggin vmtruncate(inode, inode->i_size); 1993afddba49SNick Piggin } 1994afddba49SNick Piggin goto out; 1995afddba49SNick Piggin } 1996afddba49SNick Piggin 1997afddba49SNick Piggin out: 1998afddba49SNick Piggin return status; 1999afddba49SNick Piggin } 2000afddba49SNick Piggin EXPORT_SYMBOL(block_write_begin); 2001afddba49SNick Piggin 2002afddba49SNick Piggin int block_write_end(struct file *file, struct address_space *mapping, 2003afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2004afddba49SNick Piggin struct page *page, void *fsdata) 2005afddba49SNick Piggin { 2006afddba49SNick Piggin struct inode *inode = mapping->host; 2007afddba49SNick Piggin unsigned start; 2008afddba49SNick Piggin 2009afddba49SNick Piggin start = pos & (PAGE_CACHE_SIZE - 1); 2010afddba49SNick Piggin 2011afddba49SNick Piggin if (unlikely(copied < len)) { 2012afddba49SNick Piggin /* 2013afddba49SNick Piggin * The buffers that were written will now be uptodate, so we 2014afddba49SNick Piggin * don't have to worry about a readpage reading them and 2015afddba49SNick Piggin * overwriting a partial write. However if we have encountered 2016afddba49SNick Piggin * a short write and only partially written into a buffer, it 2017afddba49SNick Piggin * will not be marked uptodate, so a readpage might come in and 2018afddba49SNick Piggin * destroy our partial write. 2019afddba49SNick Piggin * 2020afddba49SNick Piggin * Do the simplest thing, and just treat any short write to a 2021afddba49SNick Piggin * non uptodate page as a zero-length write, and force the 2022afddba49SNick Piggin * caller to redo the whole thing. 2023afddba49SNick Piggin */ 2024afddba49SNick Piggin if (!PageUptodate(page)) 2025afddba49SNick Piggin copied = 0; 2026afddba49SNick Piggin 2027afddba49SNick Piggin page_zero_new_buffers(page, start+copied, start+len); 2028afddba49SNick Piggin } 2029afddba49SNick Piggin flush_dcache_page(page); 2030afddba49SNick Piggin 2031afddba49SNick Piggin /* This could be a short (even 0-length) commit */ 2032afddba49SNick Piggin __block_commit_write(inode, page, start, start+copied); 2033afddba49SNick Piggin 2034afddba49SNick Piggin return copied; 2035afddba49SNick Piggin } 2036afddba49SNick Piggin EXPORT_SYMBOL(block_write_end); 2037afddba49SNick Piggin 2038afddba49SNick Piggin int generic_write_end(struct file *file, struct address_space *mapping, 2039afddba49SNick Piggin loff_t pos, unsigned len, unsigned copied, 2040afddba49SNick Piggin struct page *page, void *fsdata) 2041afddba49SNick Piggin { 2042afddba49SNick Piggin struct inode *inode = mapping->host; 2043afddba49SNick Piggin 2044afddba49SNick Piggin copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); 2045afddba49SNick Piggin 2046afddba49SNick Piggin /* 2047afddba49SNick Piggin * No need to use i_size_read() here, the i_size 2048afddba49SNick Piggin * cannot change under us because we hold i_mutex. 2049afddba49SNick Piggin * 2050afddba49SNick Piggin * But it's important to update i_size while still holding page lock: 2051afddba49SNick Piggin * page writeout could otherwise come in and zero beyond i_size. 2052afddba49SNick Piggin */ 2053afddba49SNick Piggin if (pos+copied > inode->i_size) { 2054afddba49SNick Piggin i_size_write(inode, pos+copied); 2055afddba49SNick Piggin mark_inode_dirty(inode); 2056afddba49SNick Piggin } 2057afddba49SNick Piggin 2058afddba49SNick Piggin unlock_page(page); 2059afddba49SNick Piggin page_cache_release(page); 2060afddba49SNick Piggin 2061afddba49SNick Piggin return copied; 2062afddba49SNick Piggin } 2063afddba49SNick Piggin EXPORT_SYMBOL(generic_write_end); 2064afddba49SNick Piggin 2065afddba49SNick Piggin /* 20661da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 20671da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 20681da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 20691da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 20701da177e4SLinus Torvalds * page struct once IO has completed. 20711da177e4SLinus Torvalds */ 20721da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 20731da177e4SLinus Torvalds { 20741da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 20751da177e4SLinus Torvalds sector_t iblock, lblock; 20761da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 20771da177e4SLinus Torvalds unsigned int blocksize; 20781da177e4SLinus Torvalds int nr, i; 20791da177e4SLinus Torvalds int fully_mapped = 1; 20801da177e4SLinus Torvalds 2081cd7619d6SMatt Mackall BUG_ON(!PageLocked(page)); 20821da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 20831da177e4SLinus Torvalds if (!page_has_buffers(page)) 20841da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 20851da177e4SLinus Torvalds head = page_buffers(page); 20861da177e4SLinus Torvalds 20871da177e4SLinus Torvalds iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 20881da177e4SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; 20891da177e4SLinus Torvalds bh = head; 20901da177e4SLinus Torvalds nr = 0; 20911da177e4SLinus Torvalds i = 0; 20921da177e4SLinus Torvalds 20931da177e4SLinus Torvalds do { 20941da177e4SLinus Torvalds if (buffer_uptodate(bh)) 20951da177e4SLinus Torvalds continue; 20961da177e4SLinus Torvalds 20971da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2098c64610baSAndrew Morton int err = 0; 2099c64610baSAndrew Morton 21001da177e4SLinus Torvalds fully_mapped = 0; 21011da177e4SLinus Torvalds if (iblock < lblock) { 2102b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 2103c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 2104c64610baSAndrew Morton if (err) 21051da177e4SLinus Torvalds SetPageError(page); 21061da177e4SLinus Torvalds } 21071da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 210801f2705dSNate Diller zero_user_page(page, i * blocksize, blocksize, 210901f2705dSNate Diller KM_USER0); 2110c64610baSAndrew Morton if (!err) 21111da177e4SLinus Torvalds set_buffer_uptodate(bh); 21121da177e4SLinus Torvalds continue; 21131da177e4SLinus Torvalds } 21141da177e4SLinus Torvalds /* 21151da177e4SLinus Torvalds * get_block() might have updated the buffer 21161da177e4SLinus Torvalds * synchronously 21171da177e4SLinus Torvalds */ 21181da177e4SLinus Torvalds if (buffer_uptodate(bh)) 21191da177e4SLinus Torvalds continue; 21201da177e4SLinus Torvalds } 21211da177e4SLinus Torvalds arr[nr++] = bh; 21221da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 21231da177e4SLinus Torvalds 21241da177e4SLinus Torvalds if (fully_mapped) 21251da177e4SLinus Torvalds SetPageMappedToDisk(page); 21261da177e4SLinus Torvalds 21271da177e4SLinus Torvalds if (!nr) { 21281da177e4SLinus Torvalds /* 21291da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 21301da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 21311da177e4SLinus Torvalds */ 21321da177e4SLinus Torvalds if (!PageError(page)) 21331da177e4SLinus Torvalds SetPageUptodate(page); 21341da177e4SLinus Torvalds unlock_page(page); 21351da177e4SLinus Torvalds return 0; 21361da177e4SLinus Torvalds } 21371da177e4SLinus Torvalds 21381da177e4SLinus Torvalds /* Stage two: lock the buffers */ 21391da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 21401da177e4SLinus Torvalds bh = arr[i]; 21411da177e4SLinus Torvalds lock_buffer(bh); 21421da177e4SLinus Torvalds mark_buffer_async_read(bh); 21431da177e4SLinus Torvalds } 21441da177e4SLinus Torvalds 21451da177e4SLinus Torvalds /* 21461da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 21471da177e4SLinus Torvalds * inside the buffer lock in case another process reading 21481da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 21491da177e4SLinus Torvalds */ 21501da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 21511da177e4SLinus Torvalds bh = arr[i]; 21521da177e4SLinus Torvalds if (buffer_uptodate(bh)) 21531da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 21541da177e4SLinus Torvalds else 21551da177e4SLinus Torvalds submit_bh(READ, bh); 21561da177e4SLinus Torvalds } 21571da177e4SLinus Torvalds return 0; 21581da177e4SLinus Torvalds } 21591da177e4SLinus Torvalds 21601da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 216189e10787SNick Piggin * truncates. Uses filesystem pagecache writes to allow the filesystem to 21621da177e4SLinus Torvalds * deal with the hole. 21631da177e4SLinus Torvalds */ 216489e10787SNick Piggin int generic_cont_expand_simple(struct inode *inode, loff_t size) 21651da177e4SLinus Torvalds { 21661da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 21671da177e4SLinus Torvalds struct page *page; 216889e10787SNick Piggin void *fsdata; 216905eb0b51SOGAWA Hirofumi unsigned long limit; 21701da177e4SLinus Torvalds int err; 21711da177e4SLinus Torvalds 21721da177e4SLinus Torvalds err = -EFBIG; 21731da177e4SLinus Torvalds limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 21741da177e4SLinus Torvalds if (limit != RLIM_INFINITY && size > (loff_t)limit) { 21751da177e4SLinus Torvalds send_sig(SIGXFSZ, current, 0); 21761da177e4SLinus Torvalds goto out; 21771da177e4SLinus Torvalds } 21781da177e4SLinus Torvalds if (size > inode->i_sb->s_maxbytes) 21791da177e4SLinus Torvalds goto out; 21801da177e4SLinus Torvalds 218189e10787SNick Piggin err = pagecache_write_begin(NULL, mapping, size, 0, 218289e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, 218389e10787SNick Piggin &page, &fsdata); 218489e10787SNick Piggin if (err) 218505eb0b51SOGAWA Hirofumi goto out; 218605eb0b51SOGAWA Hirofumi 218789e10787SNick Piggin err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); 218889e10787SNick Piggin BUG_ON(err > 0); 218905eb0b51SOGAWA Hirofumi 219005eb0b51SOGAWA Hirofumi out: 219105eb0b51SOGAWA Hirofumi return err; 219205eb0b51SOGAWA Hirofumi } 219305eb0b51SOGAWA Hirofumi 219489e10787SNick Piggin int cont_expand_zero(struct file *file, struct address_space *mapping, 219589e10787SNick Piggin loff_t pos, loff_t *bytes) 219605eb0b51SOGAWA Hirofumi { 219789e10787SNick Piggin struct inode *inode = mapping->host; 219889e10787SNick Piggin unsigned blocksize = 1 << inode->i_blkbits; 219989e10787SNick Piggin struct page *page; 220089e10787SNick Piggin void *fsdata; 220189e10787SNick Piggin pgoff_t index, curidx; 220289e10787SNick Piggin loff_t curpos; 220389e10787SNick Piggin unsigned zerofrom, offset, len; 220489e10787SNick Piggin int err = 0; 220505eb0b51SOGAWA Hirofumi 220689e10787SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 220789e10787SNick Piggin offset = pos & ~PAGE_CACHE_MASK; 220889e10787SNick Piggin 220989e10787SNick Piggin while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) { 221089e10787SNick Piggin zerofrom = curpos & ~PAGE_CACHE_MASK; 221189e10787SNick Piggin if (zerofrom & (blocksize-1)) { 221289e10787SNick Piggin *bytes |= (blocksize-1); 221389e10787SNick Piggin (*bytes)++; 221489e10787SNick Piggin } 221589e10787SNick Piggin len = PAGE_CACHE_SIZE - zerofrom; 221689e10787SNick Piggin 221789e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 221889e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 221989e10787SNick Piggin &page, &fsdata); 222089e10787SNick Piggin if (err) 222189e10787SNick Piggin goto out; 222289e10787SNick Piggin zero_user_page(page, zerofrom, len, KM_USER0); 222389e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 222489e10787SNick Piggin page, fsdata); 222589e10787SNick Piggin if (err < 0) 222689e10787SNick Piggin goto out; 222789e10787SNick Piggin BUG_ON(err != len); 222889e10787SNick Piggin err = 0; 222989e10787SNick Piggin } 223089e10787SNick Piggin 223189e10787SNick Piggin /* page covers the boundary, find the boundary offset */ 223289e10787SNick Piggin if (index == curidx) { 223389e10787SNick Piggin zerofrom = curpos & ~PAGE_CACHE_MASK; 223489e10787SNick Piggin /* if we will expand the thing last block will be filled */ 223589e10787SNick Piggin if (offset <= zerofrom) { 223689e10787SNick Piggin goto out; 223789e10787SNick Piggin } 223889e10787SNick Piggin if (zerofrom & (blocksize-1)) { 223989e10787SNick Piggin *bytes |= (blocksize-1); 224089e10787SNick Piggin (*bytes)++; 224189e10787SNick Piggin } 224289e10787SNick Piggin len = offset - zerofrom; 224389e10787SNick Piggin 224489e10787SNick Piggin err = pagecache_write_begin(file, mapping, curpos, len, 224589e10787SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, 224689e10787SNick Piggin &page, &fsdata); 224789e10787SNick Piggin if (err) 224889e10787SNick Piggin goto out; 224989e10787SNick Piggin zero_user_page(page, zerofrom, len, KM_USER0); 225089e10787SNick Piggin err = pagecache_write_end(file, mapping, curpos, len, len, 225189e10787SNick Piggin page, fsdata); 225289e10787SNick Piggin if (err < 0) 225389e10787SNick Piggin goto out; 225489e10787SNick Piggin BUG_ON(err != len); 225589e10787SNick Piggin err = 0; 225689e10787SNick Piggin } 225789e10787SNick Piggin out: 225889e10787SNick Piggin return err; 22591da177e4SLinus Torvalds } 22601da177e4SLinus Torvalds 22611da177e4SLinus Torvalds /* 22621da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 22631da177e4SLinus Torvalds * We may have to extend the file. 22641da177e4SLinus Torvalds */ 226589e10787SNick Piggin int cont_write_begin(struct file *file, struct address_space *mapping, 226689e10787SNick Piggin loff_t pos, unsigned len, unsigned flags, 226789e10787SNick Piggin struct page **pagep, void **fsdata, 226889e10787SNick Piggin get_block_t *get_block, loff_t *bytes) 22691da177e4SLinus Torvalds { 22701da177e4SLinus Torvalds struct inode *inode = mapping->host; 22711da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 227289e10787SNick Piggin unsigned zerofrom; 227389e10787SNick Piggin int err; 22741da177e4SLinus Torvalds 227589e10787SNick Piggin err = cont_expand_zero(file, mapping, pos, bytes); 227689e10787SNick Piggin if (err) 22771da177e4SLinus Torvalds goto out; 22781da177e4SLinus Torvalds 22791da177e4SLinus Torvalds zerofrom = *bytes & ~PAGE_CACHE_MASK; 228089e10787SNick Piggin if (pos+len > *bytes && zerofrom & (blocksize-1)) { 22811da177e4SLinus Torvalds *bytes |= (blocksize-1); 22821da177e4SLinus Torvalds (*bytes)++; 22831da177e4SLinus Torvalds } 22841da177e4SLinus Torvalds 228589e10787SNick Piggin *pagep = NULL; 228689e10787SNick Piggin err = block_write_begin(file, mapping, pos, len, 228789e10787SNick Piggin flags, pagep, fsdata, get_block); 22881da177e4SLinus Torvalds out: 228989e10787SNick Piggin return err; 22901da177e4SLinus Torvalds } 22911da177e4SLinus Torvalds 22921da177e4SLinus Torvalds int block_prepare_write(struct page *page, unsigned from, unsigned to, 22931da177e4SLinus Torvalds get_block_t *get_block) 22941da177e4SLinus Torvalds { 22951da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 22961da177e4SLinus Torvalds int err = __block_prepare_write(inode, page, from, to, get_block); 22971da177e4SLinus Torvalds if (err) 22981da177e4SLinus Torvalds ClearPageUptodate(page); 22991da177e4SLinus Torvalds return err; 23001da177e4SLinus Torvalds } 23011da177e4SLinus Torvalds 23021da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 23031da177e4SLinus Torvalds { 23041da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23051da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 23061da177e4SLinus Torvalds return 0; 23071da177e4SLinus Torvalds } 23081da177e4SLinus Torvalds 23091da177e4SLinus Torvalds int generic_commit_write(struct file *file, struct page *page, 23101da177e4SLinus Torvalds unsigned from, unsigned to) 23111da177e4SLinus Torvalds { 23121da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23131da177e4SLinus Torvalds loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; 23141da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 23151da177e4SLinus Torvalds /* 23161da177e4SLinus Torvalds * No need to use i_size_read() here, the i_size 23171b1dcc1bSJes Sorensen * cannot change under us because we hold i_mutex. 23181da177e4SLinus Torvalds */ 23191da177e4SLinus Torvalds if (pos > inode->i_size) { 23201da177e4SLinus Torvalds i_size_write(inode, pos); 23211da177e4SLinus Torvalds mark_inode_dirty(inode); 23221da177e4SLinus Torvalds } 23231da177e4SLinus Torvalds return 0; 23241da177e4SLinus Torvalds } 23251da177e4SLinus Torvalds 232654171690SDavid Chinner /* 232754171690SDavid Chinner * block_page_mkwrite() is not allowed to change the file size as it gets 232854171690SDavid Chinner * called from a page fault handler when a page is first dirtied. Hence we must 232954171690SDavid Chinner * be careful to check for EOF conditions here. We set the page up correctly 233054171690SDavid Chinner * for a written page which means we get ENOSPC checking when writing into 233154171690SDavid Chinner * holes and correct delalloc and unwritten extent mapping on filesystems that 233254171690SDavid Chinner * support these features. 233354171690SDavid Chinner * 233454171690SDavid Chinner * We are not allowed to take the i_mutex here so we have to play games to 233554171690SDavid Chinner * protect against truncate races as the page could now be beyond EOF. Because 233654171690SDavid Chinner * vmtruncate() writes the inode size before removing pages, once we have the 233754171690SDavid Chinner * page lock we can determine safely if the page is beyond EOF. If it is not 233854171690SDavid Chinner * beyond EOF, then the page is guaranteed safe against truncation until we 233954171690SDavid Chinner * unlock the page. 234054171690SDavid Chinner */ 234154171690SDavid Chinner int 234254171690SDavid Chinner block_page_mkwrite(struct vm_area_struct *vma, struct page *page, 234354171690SDavid Chinner get_block_t get_block) 234454171690SDavid Chinner { 234554171690SDavid Chinner struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 234654171690SDavid Chinner unsigned long end; 234754171690SDavid Chinner loff_t size; 234854171690SDavid Chinner int ret = -EINVAL; 234954171690SDavid Chinner 235054171690SDavid Chinner lock_page(page); 235154171690SDavid Chinner size = i_size_read(inode); 235254171690SDavid Chinner if ((page->mapping != inode->i_mapping) || 235318336338SNick Piggin (page_offset(page) > size)) { 235454171690SDavid Chinner /* page got truncated out from underneath us */ 235554171690SDavid Chinner goto out_unlock; 235654171690SDavid Chinner } 235754171690SDavid Chinner 235854171690SDavid Chinner /* page is wholly or partially inside EOF */ 235954171690SDavid Chinner if (((page->index + 1) << PAGE_CACHE_SHIFT) > size) 236054171690SDavid Chinner end = size & ~PAGE_CACHE_MASK; 236154171690SDavid Chinner else 236254171690SDavid Chinner end = PAGE_CACHE_SIZE; 236354171690SDavid Chinner 236454171690SDavid Chinner ret = block_prepare_write(page, 0, end, get_block); 236554171690SDavid Chinner if (!ret) 236654171690SDavid Chinner ret = block_commit_write(page, 0, end); 236754171690SDavid Chinner 236854171690SDavid Chinner out_unlock: 236954171690SDavid Chinner unlock_page(page); 237054171690SDavid Chinner return ret; 237154171690SDavid Chinner } 23721da177e4SLinus Torvalds 23731da177e4SLinus Torvalds /* 237403158cd7SNick Piggin * nobh_write_begin()'s prereads are special: the buffer_heads are freed 23751da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 23761da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 23771da177e4SLinus Torvalds */ 23781da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 23791da177e4SLinus Torvalds { 238068671f35SDmitry Monakhov __end_buffer_read_notouch(bh, uptodate); 23811da177e4SLinus Torvalds } 23821da177e4SLinus Torvalds 23831da177e4SLinus Torvalds /* 238403158cd7SNick Piggin * Attach the singly-linked list of buffers created by nobh_write_begin, to 238503158cd7SNick Piggin * the page (converting it to circular linked list and taking care of page 238603158cd7SNick Piggin * dirty races). 238703158cd7SNick Piggin */ 238803158cd7SNick Piggin static void attach_nobh_buffers(struct page *page, struct buffer_head *head) 238903158cd7SNick Piggin { 239003158cd7SNick Piggin struct buffer_head *bh; 239103158cd7SNick Piggin 239203158cd7SNick Piggin BUG_ON(!PageLocked(page)); 239303158cd7SNick Piggin 239403158cd7SNick Piggin spin_lock(&page->mapping->private_lock); 239503158cd7SNick Piggin bh = head; 239603158cd7SNick Piggin do { 239703158cd7SNick Piggin if (PageDirty(page)) 239803158cd7SNick Piggin set_buffer_dirty(bh); 239903158cd7SNick Piggin if (!bh->b_this_page) 240003158cd7SNick Piggin bh->b_this_page = head; 240103158cd7SNick Piggin bh = bh->b_this_page; 240203158cd7SNick Piggin } while (bh != head); 240303158cd7SNick Piggin attach_page_buffers(page, head); 240403158cd7SNick Piggin spin_unlock(&page->mapping->private_lock); 240503158cd7SNick Piggin } 240603158cd7SNick Piggin 240703158cd7SNick Piggin /* 24081da177e4SLinus Torvalds * On entry, the page is fully not uptodate. 24091da177e4SLinus Torvalds * On exit the page is fully uptodate in the areas outside (from,to) 24101da177e4SLinus Torvalds */ 241103158cd7SNick Piggin int nobh_write_begin(struct file *file, struct address_space *mapping, 241203158cd7SNick Piggin loff_t pos, unsigned len, unsigned flags, 241303158cd7SNick Piggin struct page **pagep, void **fsdata, 24141da177e4SLinus Torvalds get_block_t *get_block) 24151da177e4SLinus Torvalds { 241603158cd7SNick Piggin struct inode *inode = mapping->host; 24171da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 24181da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 2419a4b0672dSNick Piggin struct buffer_head *head, *bh; 242003158cd7SNick Piggin struct page *page; 242103158cd7SNick Piggin pgoff_t index; 242203158cd7SNick Piggin unsigned from, to; 24231da177e4SLinus Torvalds unsigned block_in_page; 2424a4b0672dSNick Piggin unsigned block_start, block_end; 24251da177e4SLinus Torvalds sector_t block_in_file; 24261da177e4SLinus Torvalds char *kaddr; 24271da177e4SLinus Torvalds int nr_reads = 0; 24281da177e4SLinus Torvalds int ret = 0; 24291da177e4SLinus Torvalds int is_mapped_to_disk = 1; 24301da177e4SLinus Torvalds 243103158cd7SNick Piggin index = pos >> PAGE_CACHE_SHIFT; 243203158cd7SNick Piggin from = pos & (PAGE_CACHE_SIZE - 1); 243303158cd7SNick Piggin to = from + len; 243403158cd7SNick Piggin 243503158cd7SNick Piggin page = __grab_cache_page(mapping, index); 243603158cd7SNick Piggin if (!page) 243703158cd7SNick Piggin return -ENOMEM; 243803158cd7SNick Piggin *pagep = page; 243903158cd7SNick Piggin *fsdata = NULL; 244003158cd7SNick Piggin 244103158cd7SNick Piggin if (page_has_buffers(page)) { 244203158cd7SNick Piggin unlock_page(page); 244303158cd7SNick Piggin page_cache_release(page); 244403158cd7SNick Piggin *pagep = NULL; 244503158cd7SNick Piggin return block_write_begin(file, mapping, pos, len, flags, pagep, 244603158cd7SNick Piggin fsdata, get_block); 244703158cd7SNick Piggin } 2448a4b0672dSNick Piggin 24491da177e4SLinus Torvalds if (PageMappedToDisk(page)) 24501da177e4SLinus Torvalds return 0; 24511da177e4SLinus Torvalds 2452a4b0672dSNick Piggin /* 2453a4b0672dSNick Piggin * Allocate buffers so that we can keep track of state, and potentially 2454a4b0672dSNick Piggin * attach them to the page if an error occurs. In the common case of 2455a4b0672dSNick Piggin * no error, they will just be freed again without ever being attached 2456a4b0672dSNick Piggin * to the page (which is all OK, because we're under the page lock). 2457a4b0672dSNick Piggin * 2458a4b0672dSNick Piggin * Be careful: the buffer linked list is a NULL terminated one, rather 2459a4b0672dSNick Piggin * than the circular one we're used to. 2460a4b0672dSNick Piggin */ 2461a4b0672dSNick Piggin head = alloc_page_buffers(page, blocksize, 0); 246203158cd7SNick Piggin if (!head) { 246303158cd7SNick Piggin ret = -ENOMEM; 246403158cd7SNick Piggin goto out_release; 246503158cd7SNick Piggin } 2466a4b0672dSNick Piggin 24671da177e4SLinus Torvalds block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); 24681da177e4SLinus Torvalds 24691da177e4SLinus Torvalds /* 24701da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 24711da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 24721da177e4SLinus Torvalds * page is fully mapped-to-disk. 24731da177e4SLinus Torvalds */ 2474a4b0672dSNick Piggin for (block_start = 0, block_in_page = 0, bh = head; 24751da177e4SLinus Torvalds block_start < PAGE_CACHE_SIZE; 2476a4b0672dSNick Piggin block_in_page++, block_start += blocksize, bh = bh->b_this_page) { 24771da177e4SLinus Torvalds int create; 24781da177e4SLinus Torvalds 2479a4b0672dSNick Piggin block_end = block_start + blocksize; 2480a4b0672dSNick Piggin bh->b_state = 0; 24811da177e4SLinus Torvalds create = 1; 24821da177e4SLinus Torvalds if (block_start >= to) 24831da177e4SLinus Torvalds create = 0; 24841da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 2485a4b0672dSNick Piggin bh, create); 24861da177e4SLinus Torvalds if (ret) 24871da177e4SLinus Torvalds goto failed; 2488a4b0672dSNick Piggin if (!buffer_mapped(bh)) 24891da177e4SLinus Torvalds is_mapped_to_disk = 0; 2490a4b0672dSNick Piggin if (buffer_new(bh)) 2491a4b0672dSNick Piggin unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 2492a4b0672dSNick Piggin if (PageUptodate(page)) { 2493a4b0672dSNick Piggin set_buffer_uptodate(bh); 24941da177e4SLinus Torvalds continue; 2495a4b0672dSNick Piggin } 2496a4b0672dSNick Piggin if (buffer_new(bh) || !buffer_mapped(bh)) { 24971da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 249822c8ca78SNick Piggin if (block_start < from) 24991da177e4SLinus Torvalds memset(kaddr+block_start, 0, from-block_start); 250022c8ca78SNick Piggin if (block_end > to) 25011da177e4SLinus Torvalds memset(kaddr + to, 0, block_end - to); 25021da177e4SLinus Torvalds flush_dcache_page(page); 25031da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 25041da177e4SLinus Torvalds continue; 25051da177e4SLinus Torvalds } 2506a4b0672dSNick Piggin if (buffer_uptodate(bh)) 25071da177e4SLinus Torvalds continue; /* reiserfs does this */ 25081da177e4SLinus Torvalds if (block_start < from || block_end > to) { 2509a4b0672dSNick Piggin lock_buffer(bh); 2510a4b0672dSNick Piggin bh->b_end_io = end_buffer_read_nobh; 2511a4b0672dSNick Piggin submit_bh(READ, bh); 2512a4b0672dSNick Piggin nr_reads++; 25131da177e4SLinus Torvalds } 25141da177e4SLinus Torvalds } 25151da177e4SLinus Torvalds 25161da177e4SLinus Torvalds if (nr_reads) { 25171da177e4SLinus Torvalds /* 25181da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 25191da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 25201da177e4SLinus Torvalds * for the buffer_head refcounts. 25211da177e4SLinus Torvalds */ 2522a4b0672dSNick Piggin for (bh = head; bh; bh = bh->b_this_page) { 25231da177e4SLinus Torvalds wait_on_buffer(bh); 25241da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 25251da177e4SLinus Torvalds ret = -EIO; 25261da177e4SLinus Torvalds } 25271da177e4SLinus Torvalds if (ret) 25281da177e4SLinus Torvalds goto failed; 25291da177e4SLinus Torvalds } 25301da177e4SLinus Torvalds 25311da177e4SLinus Torvalds if (is_mapped_to_disk) 25321da177e4SLinus Torvalds SetPageMappedToDisk(page); 25331da177e4SLinus Torvalds 253403158cd7SNick Piggin *fsdata = head; /* to be released by nobh_write_end */ 2535a4b0672dSNick Piggin 25361da177e4SLinus Torvalds return 0; 25371da177e4SLinus Torvalds 25381da177e4SLinus Torvalds failed: 253903158cd7SNick Piggin BUG_ON(!ret); 25401da177e4SLinus Torvalds /* 2541a4b0672dSNick Piggin * Error recovery is a bit difficult. We need to zero out blocks that 2542a4b0672dSNick Piggin * were newly allocated, and dirty them to ensure they get written out. 2543a4b0672dSNick Piggin * Buffers need to be attached to the page at this point, otherwise 2544a4b0672dSNick Piggin * the handling of potential IO errors during writeout would be hard 2545a4b0672dSNick Piggin * (could try doing synchronous writeout, but what if that fails too?) 25461da177e4SLinus Torvalds */ 254703158cd7SNick Piggin attach_nobh_buffers(page, head); 254803158cd7SNick Piggin page_zero_new_buffers(page, from, to); 2549a4b0672dSNick Piggin 255003158cd7SNick Piggin out_release: 255103158cd7SNick Piggin unlock_page(page); 255203158cd7SNick Piggin page_cache_release(page); 255303158cd7SNick Piggin *pagep = NULL; 2554a4b0672dSNick Piggin 255503158cd7SNick Piggin if (pos + len > inode->i_size) 255603158cd7SNick Piggin vmtruncate(inode, inode->i_size); 2557a4b0672dSNick Piggin 25581da177e4SLinus Torvalds return ret; 25591da177e4SLinus Torvalds } 256003158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_begin); 25611da177e4SLinus Torvalds 256203158cd7SNick Piggin int nobh_write_end(struct file *file, struct address_space *mapping, 256303158cd7SNick Piggin loff_t pos, unsigned len, unsigned copied, 256403158cd7SNick Piggin struct page *page, void *fsdata) 25651da177e4SLinus Torvalds { 25661da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 256703158cd7SNick Piggin struct buffer_head *head = NULL; 256803158cd7SNick Piggin struct buffer_head *bh; 25691da177e4SLinus Torvalds 257003158cd7SNick Piggin if (!PageMappedToDisk(page)) { 257103158cd7SNick Piggin if (unlikely(copied < len) && !page_has_buffers(page)) 257203158cd7SNick Piggin attach_nobh_buffers(page, head); 2573a4b0672dSNick Piggin if (page_has_buffers(page)) 257403158cd7SNick Piggin return generic_write_end(file, mapping, pos, len, 257503158cd7SNick Piggin copied, page, fsdata); 257603158cd7SNick Piggin } 2577a4b0672dSNick Piggin 257822c8ca78SNick Piggin SetPageUptodate(page); 25791da177e4SLinus Torvalds set_page_dirty(page); 258003158cd7SNick Piggin if (pos+copied > inode->i_size) { 258103158cd7SNick Piggin i_size_write(inode, pos+copied); 25821da177e4SLinus Torvalds mark_inode_dirty(inode); 25831da177e4SLinus Torvalds } 258403158cd7SNick Piggin 258503158cd7SNick Piggin unlock_page(page); 258603158cd7SNick Piggin page_cache_release(page); 258703158cd7SNick Piggin 258803158cd7SNick Piggin head = fsdata; 258903158cd7SNick Piggin while (head) { 259003158cd7SNick Piggin bh = head; 259103158cd7SNick Piggin head = head->b_this_page; 259203158cd7SNick Piggin free_buffer_head(bh); 25931da177e4SLinus Torvalds } 259403158cd7SNick Piggin 259503158cd7SNick Piggin return copied; 259603158cd7SNick Piggin } 259703158cd7SNick Piggin EXPORT_SYMBOL(nobh_write_end); 25981da177e4SLinus Torvalds 25991da177e4SLinus Torvalds /* 26001da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 26011da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 26021da177e4SLinus Torvalds * the page. 26031da177e4SLinus Torvalds */ 26041da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 26051da177e4SLinus Torvalds struct writeback_control *wbc) 26061da177e4SLinus Torvalds { 26071da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 26081da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 26091da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 26101da177e4SLinus Torvalds unsigned offset; 26111da177e4SLinus Torvalds int ret; 26121da177e4SLinus Torvalds 26131da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 26141da177e4SLinus Torvalds if (page->index < end_index) 26151da177e4SLinus Torvalds goto out; 26161da177e4SLinus Torvalds 26171da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 26181da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 26191da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 26201da177e4SLinus Torvalds /* 26211da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 26221da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 26231da177e4SLinus Torvalds * freeable here, so the page does not leak. 26241da177e4SLinus Torvalds */ 26251da177e4SLinus Torvalds #if 0 26261da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 26271da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 26281da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 26291da177e4SLinus Torvalds #endif 26301da177e4SLinus Torvalds unlock_page(page); 26311da177e4SLinus Torvalds return 0; /* don't care */ 26321da177e4SLinus Torvalds } 26331da177e4SLinus Torvalds 26341da177e4SLinus Torvalds /* 26351da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 26361da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 26371da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 26381da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 26391da177e4SLinus Torvalds * writes to that region are not written out to the file." 26401da177e4SLinus Torvalds */ 264101f2705dSNate Diller zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0); 26421da177e4SLinus Torvalds out: 26431da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 26441da177e4SLinus Torvalds if (ret == -EAGAIN) 26451da177e4SLinus Torvalds ret = __block_write_full_page(inode, page, get_block, wbc); 26461da177e4SLinus Torvalds return ret; 26471da177e4SLinus Torvalds } 26481da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 26491da177e4SLinus Torvalds 265003158cd7SNick Piggin int nobh_truncate_page(struct address_space *mapping, 265103158cd7SNick Piggin loff_t from, get_block_t *get_block) 26521da177e4SLinus Torvalds { 26531da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 26541da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 265503158cd7SNick Piggin unsigned blocksize; 265603158cd7SNick Piggin sector_t iblock; 265703158cd7SNick Piggin unsigned length, pos; 265803158cd7SNick Piggin struct inode *inode = mapping->host; 26591da177e4SLinus Torvalds struct page *page; 266003158cd7SNick Piggin struct buffer_head map_bh; 266103158cd7SNick Piggin int err; 26621da177e4SLinus Torvalds 266303158cd7SNick Piggin blocksize = 1 << inode->i_blkbits; 266403158cd7SNick Piggin length = offset & (blocksize - 1); 26651da177e4SLinus Torvalds 266603158cd7SNick Piggin /* Block boundary? Nothing to do */ 266703158cd7SNick Piggin if (!length) 266803158cd7SNick Piggin return 0; 266903158cd7SNick Piggin 267003158cd7SNick Piggin length = blocksize - length; 267103158cd7SNick Piggin iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 267203158cd7SNick Piggin 26731da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 267403158cd7SNick Piggin err = -ENOMEM; 26751da177e4SLinus Torvalds if (!page) 26761da177e4SLinus Torvalds goto out; 26771da177e4SLinus Torvalds 267803158cd7SNick Piggin if (page_has_buffers(page)) { 267903158cd7SNick Piggin has_buffers: 268003158cd7SNick Piggin unlock_page(page); 268103158cd7SNick Piggin page_cache_release(page); 268203158cd7SNick Piggin return block_truncate_page(mapping, from, get_block); 26831da177e4SLinus Torvalds } 268403158cd7SNick Piggin 268503158cd7SNick Piggin /* Find the buffer that contains "offset" */ 268603158cd7SNick Piggin pos = blocksize; 268703158cd7SNick Piggin while (offset >= pos) { 268803158cd7SNick Piggin iblock++; 268903158cd7SNick Piggin pos += blocksize; 269003158cd7SNick Piggin } 269103158cd7SNick Piggin 269203158cd7SNick Piggin err = get_block(inode, iblock, &map_bh, 0); 269303158cd7SNick Piggin if (err) 269403158cd7SNick Piggin goto unlock; 269503158cd7SNick Piggin /* unmapped? It's a hole - nothing to do */ 269603158cd7SNick Piggin if (!buffer_mapped(&map_bh)) 269703158cd7SNick Piggin goto unlock; 269803158cd7SNick Piggin 269903158cd7SNick Piggin /* Ok, it's mapped. Make sure it's up-to-date */ 270003158cd7SNick Piggin if (!PageUptodate(page)) { 270103158cd7SNick Piggin err = mapping->a_ops->readpage(NULL, page); 270203158cd7SNick Piggin if (err) { 270303158cd7SNick Piggin page_cache_release(page); 270403158cd7SNick Piggin goto out; 270503158cd7SNick Piggin } 270603158cd7SNick Piggin lock_page(page); 270703158cd7SNick Piggin if (!PageUptodate(page)) { 270803158cd7SNick Piggin err = -EIO; 270903158cd7SNick Piggin goto unlock; 271003158cd7SNick Piggin } 271103158cd7SNick Piggin if (page_has_buffers(page)) 271203158cd7SNick Piggin goto has_buffers; 271303158cd7SNick Piggin } 271403158cd7SNick Piggin zero_user_page(page, offset, length, KM_USER0); 271503158cd7SNick Piggin set_page_dirty(page); 271603158cd7SNick Piggin err = 0; 271703158cd7SNick Piggin 271803158cd7SNick Piggin unlock: 27191da177e4SLinus Torvalds unlock_page(page); 27201da177e4SLinus Torvalds page_cache_release(page); 27211da177e4SLinus Torvalds out: 272203158cd7SNick Piggin return err; 27231da177e4SLinus Torvalds } 27241da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 27251da177e4SLinus Torvalds 27261da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 27271da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 27281da177e4SLinus Torvalds { 27291da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 27301da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 27311da177e4SLinus Torvalds unsigned blocksize; 273254b21a79SAndrew Morton sector_t iblock; 27331da177e4SLinus Torvalds unsigned length, pos; 27341da177e4SLinus Torvalds struct inode *inode = mapping->host; 27351da177e4SLinus Torvalds struct page *page; 27361da177e4SLinus Torvalds struct buffer_head *bh; 27371da177e4SLinus Torvalds int err; 27381da177e4SLinus Torvalds 27391da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 27401da177e4SLinus Torvalds length = offset & (blocksize - 1); 27411da177e4SLinus Torvalds 27421da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 27431da177e4SLinus Torvalds if (!length) 27441da177e4SLinus Torvalds return 0; 27451da177e4SLinus Torvalds 27461da177e4SLinus Torvalds length = blocksize - length; 274754b21a79SAndrew Morton iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 27481da177e4SLinus Torvalds 27491da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 27501da177e4SLinus Torvalds err = -ENOMEM; 27511da177e4SLinus Torvalds if (!page) 27521da177e4SLinus Torvalds goto out; 27531da177e4SLinus Torvalds 27541da177e4SLinus Torvalds if (!page_has_buffers(page)) 27551da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 27561da177e4SLinus Torvalds 27571da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 27581da177e4SLinus Torvalds bh = page_buffers(page); 27591da177e4SLinus Torvalds pos = blocksize; 27601da177e4SLinus Torvalds while (offset >= pos) { 27611da177e4SLinus Torvalds bh = bh->b_this_page; 27621da177e4SLinus Torvalds iblock++; 27631da177e4SLinus Torvalds pos += blocksize; 27641da177e4SLinus Torvalds } 27651da177e4SLinus Torvalds 27661da177e4SLinus Torvalds err = 0; 27671da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2768b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 27691da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 27701da177e4SLinus Torvalds if (err) 27711da177e4SLinus Torvalds goto unlock; 27721da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 27731da177e4SLinus Torvalds if (!buffer_mapped(bh)) 27741da177e4SLinus Torvalds goto unlock; 27751da177e4SLinus Torvalds } 27761da177e4SLinus Torvalds 27771da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 27781da177e4SLinus Torvalds if (PageUptodate(page)) 27791da177e4SLinus Torvalds set_buffer_uptodate(bh); 27801da177e4SLinus Torvalds 278133a266ddSDavid Chinner if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { 27821da177e4SLinus Torvalds err = -EIO; 27831da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 27841da177e4SLinus Torvalds wait_on_buffer(bh); 27851da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 27861da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 27871da177e4SLinus Torvalds goto unlock; 27881da177e4SLinus Torvalds } 27891da177e4SLinus Torvalds 279001f2705dSNate Diller zero_user_page(page, offset, length, KM_USER0); 27911da177e4SLinus Torvalds mark_buffer_dirty(bh); 27921da177e4SLinus Torvalds err = 0; 27931da177e4SLinus Torvalds 27941da177e4SLinus Torvalds unlock: 27951da177e4SLinus Torvalds unlock_page(page); 27961da177e4SLinus Torvalds page_cache_release(page); 27971da177e4SLinus Torvalds out: 27981da177e4SLinus Torvalds return err; 27991da177e4SLinus Torvalds } 28001da177e4SLinus Torvalds 28011da177e4SLinus Torvalds /* 28021da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 28031da177e4SLinus Torvalds */ 28041da177e4SLinus Torvalds int block_write_full_page(struct page *page, get_block_t *get_block, 28051da177e4SLinus Torvalds struct writeback_control *wbc) 28061da177e4SLinus Torvalds { 28071da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 28081da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 28091da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 28101da177e4SLinus Torvalds unsigned offset; 28111da177e4SLinus Torvalds 28121da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 28131da177e4SLinus Torvalds if (page->index < end_index) 28141da177e4SLinus Torvalds return __block_write_full_page(inode, page, get_block, wbc); 28151da177e4SLinus Torvalds 28161da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 28171da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 28181da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 28191da177e4SLinus Torvalds /* 28201da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 28211da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 28221da177e4SLinus Torvalds * freeable here, so the page does not leak. 28231da177e4SLinus Torvalds */ 2824aaa4059bSJan Kara do_invalidatepage(page, 0); 28251da177e4SLinus Torvalds unlock_page(page); 28261da177e4SLinus Torvalds return 0; /* don't care */ 28271da177e4SLinus Torvalds } 28281da177e4SLinus Torvalds 28291da177e4SLinus Torvalds /* 28301da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 28311da177e4SLinus Torvalds * writepage invokation because it may be mmapped. "A file is mapped 28321da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 28331da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 28341da177e4SLinus Torvalds * writes to that region are not written out to the file." 28351da177e4SLinus Torvalds */ 283601f2705dSNate Diller zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0); 28371da177e4SLinus Torvalds return __block_write_full_page(inode, page, get_block, wbc); 28381da177e4SLinus Torvalds } 28391da177e4SLinus Torvalds 28401da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 28411da177e4SLinus Torvalds get_block_t *get_block) 28421da177e4SLinus Torvalds { 28431da177e4SLinus Torvalds struct buffer_head tmp; 28441da177e4SLinus Torvalds struct inode *inode = mapping->host; 28451da177e4SLinus Torvalds tmp.b_state = 0; 28461da177e4SLinus Torvalds tmp.b_blocknr = 0; 2847b0cf2321SBadari Pulavarty tmp.b_size = 1 << inode->i_blkbits; 28481da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 28491da177e4SLinus Torvalds return tmp.b_blocknr; 28501da177e4SLinus Torvalds } 28511da177e4SLinus Torvalds 28526712ecf8SNeilBrown static void end_bio_bh_io_sync(struct bio *bio, int err) 28531da177e4SLinus Torvalds { 28541da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 28551da177e4SLinus Torvalds 28561da177e4SLinus Torvalds if (err == -EOPNOTSUPP) { 28571da177e4SLinus Torvalds set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); 28581da177e4SLinus Torvalds set_bit(BH_Eopnotsupp, &bh->b_state); 28591da177e4SLinus Torvalds } 28601da177e4SLinus Torvalds 28611da177e4SLinus Torvalds bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); 28621da177e4SLinus Torvalds bio_put(bio); 28631da177e4SLinus Torvalds } 28641da177e4SLinus Torvalds 28651da177e4SLinus Torvalds int submit_bh(int rw, struct buffer_head * bh) 28661da177e4SLinus Torvalds { 28671da177e4SLinus Torvalds struct bio *bio; 28681da177e4SLinus Torvalds int ret = 0; 28691da177e4SLinus Torvalds 28701da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 28711da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 28721da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 28731da177e4SLinus Torvalds 28741da177e4SLinus Torvalds if (buffer_ordered(bh) && (rw == WRITE)) 28751da177e4SLinus Torvalds rw = WRITE_BARRIER; 28761da177e4SLinus Torvalds 28771da177e4SLinus Torvalds /* 28781da177e4SLinus Torvalds * Only clear out a write error when rewriting, should this 28791da177e4SLinus Torvalds * include WRITE_SYNC as well? 28801da177e4SLinus Torvalds */ 28811da177e4SLinus Torvalds if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER)) 28821da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 28831da177e4SLinus Torvalds 28841da177e4SLinus Torvalds /* 28851da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 28861da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 28871da177e4SLinus Torvalds */ 28881da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 28891da177e4SLinus Torvalds 28901da177e4SLinus Torvalds bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); 28911da177e4SLinus Torvalds bio->bi_bdev = bh->b_bdev; 28921da177e4SLinus Torvalds bio->bi_io_vec[0].bv_page = bh->b_page; 28931da177e4SLinus Torvalds bio->bi_io_vec[0].bv_len = bh->b_size; 28941da177e4SLinus Torvalds bio->bi_io_vec[0].bv_offset = bh_offset(bh); 28951da177e4SLinus Torvalds 28961da177e4SLinus Torvalds bio->bi_vcnt = 1; 28971da177e4SLinus Torvalds bio->bi_idx = 0; 28981da177e4SLinus Torvalds bio->bi_size = bh->b_size; 28991da177e4SLinus Torvalds 29001da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 29011da177e4SLinus Torvalds bio->bi_private = bh; 29021da177e4SLinus Torvalds 29031da177e4SLinus Torvalds bio_get(bio); 29041da177e4SLinus Torvalds submit_bio(rw, bio); 29051da177e4SLinus Torvalds 29061da177e4SLinus Torvalds if (bio_flagged(bio, BIO_EOPNOTSUPP)) 29071da177e4SLinus Torvalds ret = -EOPNOTSUPP; 29081da177e4SLinus Torvalds 29091da177e4SLinus Torvalds bio_put(bio); 29101da177e4SLinus Torvalds return ret; 29111da177e4SLinus Torvalds } 29121da177e4SLinus Torvalds 29131da177e4SLinus Torvalds /** 29141da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 2915a7662236SJan Kara * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead) 29161da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 29171da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 29181da177e4SLinus Torvalds * 2919a7662236SJan Kara * ll_rw_block() takes an array of pointers to &struct buffer_heads, and 2920a7662236SJan Kara * requests an I/O operation on them, either a %READ or a %WRITE. The third 2921a7662236SJan Kara * %SWRITE is like %WRITE only we make sure that the *current* data in buffers 2922a7662236SJan Kara * are sent to disk. The fourth %READA option is described in the documentation 2923a7662236SJan Kara * for generic_make_request() which ll_rw_block() calls. 29241da177e4SLinus Torvalds * 29251da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 2926a7662236SJan Kara * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be 2927a7662236SJan Kara * clean when doing a write request, and any buffer that appears to be 2928a7662236SJan Kara * up-to-date when doing read request. Further it marks as clean buffers that 2929a7662236SJan Kara * are processed for writing (the buffer cache won't assume that they are 2930a7662236SJan Kara * actually clean until the buffer gets unlocked). 29311da177e4SLinus Torvalds * 29321da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 29331da177e4SLinus Torvalds * the buffer up-to-date (if approriate), unlocks the buffer and wakes 29341da177e4SLinus Torvalds * any waiters. 29351da177e4SLinus Torvalds * 29361da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 29371da177e4SLinus Torvalds * multiple of the current approved size for the device. 29381da177e4SLinus Torvalds */ 29391da177e4SLinus Torvalds void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) 29401da177e4SLinus Torvalds { 29411da177e4SLinus Torvalds int i; 29421da177e4SLinus Torvalds 29431da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 29441da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 29451da177e4SLinus Torvalds 2946a7662236SJan Kara if (rw == SWRITE) 2947a7662236SJan Kara lock_buffer(bh); 2948a7662236SJan Kara else if (test_set_buffer_locked(bh)) 29491da177e4SLinus Torvalds continue; 29501da177e4SLinus Torvalds 2951a7662236SJan Kara if (rw == WRITE || rw == SWRITE) { 29521da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 295376c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 2954e60e5c50SOGAWA Hirofumi get_bh(bh); 29551da177e4SLinus Torvalds submit_bh(WRITE, bh); 29561da177e4SLinus Torvalds continue; 29571da177e4SLinus Torvalds } 29581da177e4SLinus Torvalds } else { 29591da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 296076c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 2961e60e5c50SOGAWA Hirofumi get_bh(bh); 29621da177e4SLinus Torvalds submit_bh(rw, bh); 29631da177e4SLinus Torvalds continue; 29641da177e4SLinus Torvalds } 29651da177e4SLinus Torvalds } 29661da177e4SLinus Torvalds unlock_buffer(bh); 29671da177e4SLinus Torvalds } 29681da177e4SLinus Torvalds } 29691da177e4SLinus Torvalds 29701da177e4SLinus Torvalds /* 29711da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 29721da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 29731da177e4SLinus Torvalds * the buffer_head. 29741da177e4SLinus Torvalds */ 29751da177e4SLinus Torvalds int sync_dirty_buffer(struct buffer_head *bh) 29761da177e4SLinus Torvalds { 29771da177e4SLinus Torvalds int ret = 0; 29781da177e4SLinus Torvalds 29791da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 29801da177e4SLinus Torvalds lock_buffer(bh); 29811da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 29821da177e4SLinus Torvalds get_bh(bh); 29831da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 29841da177e4SLinus Torvalds ret = submit_bh(WRITE, bh); 29851da177e4SLinus Torvalds wait_on_buffer(bh); 29861da177e4SLinus Torvalds if (buffer_eopnotsupp(bh)) { 29871da177e4SLinus Torvalds clear_buffer_eopnotsupp(bh); 29881da177e4SLinus Torvalds ret = -EOPNOTSUPP; 29891da177e4SLinus Torvalds } 29901da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 29911da177e4SLinus Torvalds ret = -EIO; 29921da177e4SLinus Torvalds } else { 29931da177e4SLinus Torvalds unlock_buffer(bh); 29941da177e4SLinus Torvalds } 29951da177e4SLinus Torvalds return ret; 29961da177e4SLinus Torvalds } 29971da177e4SLinus Torvalds 29981da177e4SLinus Torvalds /* 29991da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 30001da177e4SLinus Torvalds * are unused, and releases them if so. 30011da177e4SLinus Torvalds * 30021da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 30031da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 30041da177e4SLinus Torvalds * 30051da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 30061da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 30071da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 30081da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 30091da177e4SLinus Torvalds * filesystem data on the same device. 30101da177e4SLinus Torvalds * 30111da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 30121da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 30131da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 30141da177e4SLinus Torvalds * private_lock. 30151da177e4SLinus Torvalds * 30161da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 30171da177e4SLinus Torvalds */ 30181da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 30191da177e4SLinus Torvalds { 30201da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 30211da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 30221da177e4SLinus Torvalds } 30231da177e4SLinus Torvalds 30241da177e4SLinus Torvalds static int 30251da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 30261da177e4SLinus Torvalds { 30271da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 30281da177e4SLinus Torvalds struct buffer_head *bh; 30291da177e4SLinus Torvalds 30301da177e4SLinus Torvalds bh = head; 30311da177e4SLinus Torvalds do { 3032de7d5a3bSakpm@osdl.org if (buffer_write_io_error(bh) && page->mapping) 30331da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 30341da177e4SLinus Torvalds if (buffer_busy(bh)) 30351da177e4SLinus Torvalds goto failed; 30361da177e4SLinus Torvalds bh = bh->b_this_page; 30371da177e4SLinus Torvalds } while (bh != head); 30381da177e4SLinus Torvalds 30391da177e4SLinus Torvalds do { 30401da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 30411da177e4SLinus Torvalds 30421da177e4SLinus Torvalds if (!list_empty(&bh->b_assoc_buffers)) 30431da177e4SLinus Torvalds __remove_assoc_queue(bh); 30441da177e4SLinus Torvalds bh = next; 30451da177e4SLinus Torvalds } while (bh != head); 30461da177e4SLinus Torvalds *buffers_to_free = head; 30471da177e4SLinus Torvalds __clear_page_buffers(page); 30481da177e4SLinus Torvalds return 1; 30491da177e4SLinus Torvalds failed: 30501da177e4SLinus Torvalds return 0; 30511da177e4SLinus Torvalds } 30521da177e4SLinus Torvalds 30531da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 30541da177e4SLinus Torvalds { 30551da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 30561da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 30571da177e4SLinus Torvalds int ret = 0; 30581da177e4SLinus Torvalds 30591da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 3060ecdfc978SLinus Torvalds if (PageWriteback(page)) 30611da177e4SLinus Torvalds return 0; 30621da177e4SLinus Torvalds 30631da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 30641da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 30651da177e4SLinus Torvalds goto out; 30661da177e4SLinus Torvalds } 30671da177e4SLinus Torvalds 30681da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 30691da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 3070ecdfc978SLinus Torvalds 3071ecdfc978SLinus Torvalds /* 3072ecdfc978SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 3073ecdfc978SLinus Torvalds * then we can have clean buffers against a dirty page. We 3074ecdfc978SLinus Torvalds * clean the page here; otherwise the VM will never notice 3075ecdfc978SLinus Torvalds * that the filesystem did any IO at all. 3076ecdfc978SLinus Torvalds * 3077ecdfc978SLinus Torvalds * Also, during truncate, discard_buffer will have marked all 3078ecdfc978SLinus Torvalds * the page's buffers clean. We discover that here and clean 3079ecdfc978SLinus Torvalds * the page also. 308087df7241SNick Piggin * 308187df7241SNick Piggin * private_lock must be held over this entire operation in order 308287df7241SNick Piggin * to synchronise against __set_page_dirty_buffers and prevent the 308387df7241SNick Piggin * dirty bit from being lost. 3084ecdfc978SLinus Torvalds */ 3085ecdfc978SLinus Torvalds if (ret) 3086ecdfc978SLinus Torvalds cancel_dirty_page(page, PAGE_CACHE_SIZE); 308787df7241SNick Piggin spin_unlock(&mapping->private_lock); 30881da177e4SLinus Torvalds out: 30891da177e4SLinus Torvalds if (buffers_to_free) { 30901da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 30911da177e4SLinus Torvalds 30921da177e4SLinus Torvalds do { 30931da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 30941da177e4SLinus Torvalds free_buffer_head(bh); 30951da177e4SLinus Torvalds bh = next; 30961da177e4SLinus Torvalds } while (bh != buffers_to_free); 30971da177e4SLinus Torvalds } 30981da177e4SLinus Torvalds return ret; 30991da177e4SLinus Torvalds } 31001da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 31011da177e4SLinus Torvalds 31023978d717SNeilBrown void block_sync_page(struct page *page) 31031da177e4SLinus Torvalds { 31041da177e4SLinus Torvalds struct address_space *mapping; 31051da177e4SLinus Torvalds 31061da177e4SLinus Torvalds smp_mb(); 31071da177e4SLinus Torvalds mapping = page_mapping(page); 31081da177e4SLinus Torvalds if (mapping) 31091da177e4SLinus Torvalds blk_run_backing_dev(mapping->backing_dev_info, page); 31101da177e4SLinus Torvalds } 31111da177e4SLinus Torvalds 31121da177e4SLinus Torvalds /* 31131da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 31141da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 31151da177e4SLinus Torvalds * 31161da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 31171da177e4SLinus Torvalds * The `pdflush' kernel threads fully replace bdflush daemons and this call. 31181da177e4SLinus Torvalds */ 31191da177e4SLinus Torvalds asmlinkage long sys_bdflush(int func, long data) 31201da177e4SLinus Torvalds { 31211da177e4SLinus Torvalds static int msg_count; 31221da177e4SLinus Torvalds 31231da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 31241da177e4SLinus Torvalds return -EPERM; 31251da177e4SLinus Torvalds 31261da177e4SLinus Torvalds if (msg_count < 5) { 31271da177e4SLinus Torvalds msg_count++; 31281da177e4SLinus Torvalds printk(KERN_INFO 31291da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 31301da177e4SLinus Torvalds " system call\n", current->comm); 31311da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 31321da177e4SLinus Torvalds } 31331da177e4SLinus Torvalds 31341da177e4SLinus Torvalds if (func == 1) 31351da177e4SLinus Torvalds do_exit(0); 31361da177e4SLinus Torvalds return 0; 31371da177e4SLinus Torvalds } 31381da177e4SLinus Torvalds 31391da177e4SLinus Torvalds /* 31401da177e4SLinus Torvalds * Buffer-head allocation 31411da177e4SLinus Torvalds */ 3142e18b890bSChristoph Lameter static struct kmem_cache *bh_cachep; 31431da177e4SLinus Torvalds 31441da177e4SLinus Torvalds /* 31451da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 31461da177e4SLinus Torvalds * stripping them in writeback. 31471da177e4SLinus Torvalds */ 31481da177e4SLinus Torvalds static int max_buffer_heads; 31491da177e4SLinus Torvalds 31501da177e4SLinus Torvalds int buffer_heads_over_limit; 31511da177e4SLinus Torvalds 31521da177e4SLinus Torvalds struct bh_accounting { 31531da177e4SLinus Torvalds int nr; /* Number of live bh's */ 31541da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 31551da177e4SLinus Torvalds }; 31561da177e4SLinus Torvalds 31571da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 31581da177e4SLinus Torvalds 31591da177e4SLinus Torvalds static void recalc_bh_state(void) 31601da177e4SLinus Torvalds { 31611da177e4SLinus Torvalds int i; 31621da177e4SLinus Torvalds int tot = 0; 31631da177e4SLinus Torvalds 31641da177e4SLinus Torvalds if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) 31651da177e4SLinus Torvalds return; 31661da177e4SLinus Torvalds __get_cpu_var(bh_accounting).ratelimit = 0; 31678a143426SEric Dumazet for_each_online_cpu(i) 31681da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 31691da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 31701da177e4SLinus Torvalds } 31711da177e4SLinus Torvalds 3172dd0fc66fSAl Viro struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) 31731da177e4SLinus Torvalds { 3174e12ba74dSMel Gorman struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, 3175e12ba74dSMel Gorman set_migrateflags(gfp_flags, __GFP_RECLAIMABLE)); 31761da177e4SLinus Torvalds if (ret) { 3177a35afb83SChristoph Lameter INIT_LIST_HEAD(&ret->b_assoc_buffers); 3178736c7b80SCoywolf Qi Hunt get_cpu_var(bh_accounting).nr++; 31791da177e4SLinus Torvalds recalc_bh_state(); 3180736c7b80SCoywolf Qi Hunt put_cpu_var(bh_accounting); 31811da177e4SLinus Torvalds } 31821da177e4SLinus Torvalds return ret; 31831da177e4SLinus Torvalds } 31841da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 31851da177e4SLinus Torvalds 31861da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 31871da177e4SLinus Torvalds { 31881da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 31891da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 3190736c7b80SCoywolf Qi Hunt get_cpu_var(bh_accounting).nr--; 31911da177e4SLinus Torvalds recalc_bh_state(); 3192736c7b80SCoywolf Qi Hunt put_cpu_var(bh_accounting); 31931da177e4SLinus Torvalds } 31941da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 31951da177e4SLinus Torvalds 31961da177e4SLinus Torvalds static void buffer_exit_cpu(int cpu) 31971da177e4SLinus Torvalds { 31981da177e4SLinus Torvalds int i; 31991da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 32001da177e4SLinus Torvalds 32011da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 32021da177e4SLinus Torvalds brelse(b->bhs[i]); 32031da177e4SLinus Torvalds b->bhs[i] = NULL; 32041da177e4SLinus Torvalds } 32058a143426SEric Dumazet get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr; 32068a143426SEric Dumazet per_cpu(bh_accounting, cpu).nr = 0; 32078a143426SEric Dumazet put_cpu_var(bh_accounting); 32081da177e4SLinus Torvalds } 32091da177e4SLinus Torvalds 32101da177e4SLinus Torvalds static int buffer_cpu_notify(struct notifier_block *self, 32111da177e4SLinus Torvalds unsigned long action, void *hcpu) 32121da177e4SLinus Torvalds { 32138bb78442SRafael J. Wysocki if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) 32141da177e4SLinus Torvalds buffer_exit_cpu((unsigned long)hcpu); 32151da177e4SLinus Torvalds return NOTIFY_OK; 32161da177e4SLinus Torvalds } 32171da177e4SLinus Torvalds 32181da177e4SLinus Torvalds void __init buffer_init(void) 32191da177e4SLinus Torvalds { 32201da177e4SLinus Torvalds int nrpages; 32211da177e4SLinus Torvalds 3222a35afb83SChristoph Lameter bh_cachep = KMEM_CACHE(buffer_head, 3223a35afb83SChristoph Lameter SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); 32241da177e4SLinus Torvalds 32251da177e4SLinus Torvalds /* 32261da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 32271da177e4SLinus Torvalds */ 32281da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 32291da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 32301da177e4SLinus Torvalds hotcpu_notifier(buffer_cpu_notify, 0); 32311da177e4SLinus Torvalds } 32321da177e4SLinus Torvalds 32331da177e4SLinus Torvalds EXPORT_SYMBOL(__bforget); 32341da177e4SLinus Torvalds EXPORT_SYMBOL(__brelse); 32351da177e4SLinus Torvalds EXPORT_SYMBOL(__wait_on_buffer); 32361da177e4SLinus Torvalds EXPORT_SYMBOL(block_commit_write); 32371da177e4SLinus Torvalds EXPORT_SYMBOL(block_prepare_write); 323854171690SDavid Chinner EXPORT_SYMBOL(block_page_mkwrite); 32391da177e4SLinus Torvalds EXPORT_SYMBOL(block_read_full_page); 32401da177e4SLinus Torvalds EXPORT_SYMBOL(block_sync_page); 32411da177e4SLinus Torvalds EXPORT_SYMBOL(block_truncate_page); 32421da177e4SLinus Torvalds EXPORT_SYMBOL(block_write_full_page); 324389e10787SNick Piggin EXPORT_SYMBOL(cont_write_begin); 32441da177e4SLinus Torvalds EXPORT_SYMBOL(end_buffer_read_sync); 32451da177e4SLinus Torvalds EXPORT_SYMBOL(end_buffer_write_sync); 32461da177e4SLinus Torvalds EXPORT_SYMBOL(file_fsync); 32471da177e4SLinus Torvalds EXPORT_SYMBOL(fsync_bdev); 32481da177e4SLinus Torvalds EXPORT_SYMBOL(generic_block_bmap); 32491da177e4SLinus Torvalds EXPORT_SYMBOL(generic_commit_write); 325005eb0b51SOGAWA Hirofumi EXPORT_SYMBOL(generic_cont_expand_simple); 32511da177e4SLinus Torvalds EXPORT_SYMBOL(init_buffer); 32521da177e4SLinus Torvalds EXPORT_SYMBOL(invalidate_bdev); 32531da177e4SLinus Torvalds EXPORT_SYMBOL(ll_rw_block); 32541da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty); 32551da177e4SLinus Torvalds EXPORT_SYMBOL(submit_bh); 32561da177e4SLinus Torvalds EXPORT_SYMBOL(sync_dirty_buffer); 32571da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_buffer); 3258