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> 271da177e4SLinus Torvalds #include <linux/smp_lock.h> 2816f7e0feSRandy Dunlap #include <linux/capability.h> 291da177e4SLinus Torvalds #include <linux/blkdev.h> 301da177e4SLinus Torvalds #include <linux/file.h> 311da177e4SLinus Torvalds #include <linux/quotaops.h> 321da177e4SLinus Torvalds #include <linux/highmem.h> 331da177e4SLinus Torvalds #include <linux/module.h> 341da177e4SLinus Torvalds #include <linux/writeback.h> 351da177e4SLinus Torvalds #include <linux/hash.h> 361da177e4SLinus Torvalds #include <linux/suspend.h> 371da177e4SLinus Torvalds #include <linux/buffer_head.h> 3855e829afSAndrew Morton #include <linux/task_io_accounting_ops.h> 391da177e4SLinus Torvalds #include <linux/bio.h> 401da177e4SLinus Torvalds #include <linux/notifier.h> 411da177e4SLinus Torvalds #include <linux/cpu.h> 421da177e4SLinus Torvalds #include <linux/bitops.h> 431da177e4SLinus Torvalds #include <linux/mpage.h> 44fb1c8f93SIngo Molnar #include <linux/bit_spinlock.h> 451da177e4SLinus Torvalds 461da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); 471da177e4SLinus Torvalds static void invalidate_bh_lrus(void); 481da177e4SLinus Torvalds 491da177e4SLinus Torvalds #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) 501da177e4SLinus Torvalds 511da177e4SLinus Torvalds inline void 521da177e4SLinus Torvalds init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) 531da177e4SLinus Torvalds { 541da177e4SLinus Torvalds bh->b_end_io = handler; 551da177e4SLinus Torvalds bh->b_private = private; 561da177e4SLinus Torvalds } 571da177e4SLinus Torvalds 581da177e4SLinus Torvalds static int sync_buffer(void *word) 591da177e4SLinus Torvalds { 601da177e4SLinus Torvalds struct block_device *bd; 611da177e4SLinus Torvalds struct buffer_head *bh 621da177e4SLinus Torvalds = container_of(word, struct buffer_head, b_state); 631da177e4SLinus Torvalds 641da177e4SLinus Torvalds smp_mb(); 651da177e4SLinus Torvalds bd = bh->b_bdev; 661da177e4SLinus Torvalds if (bd) 671da177e4SLinus Torvalds blk_run_address_space(bd->bd_inode->i_mapping); 681da177e4SLinus Torvalds io_schedule(); 691da177e4SLinus Torvalds return 0; 701da177e4SLinus Torvalds } 711da177e4SLinus Torvalds 721da177e4SLinus Torvalds void fastcall __lock_buffer(struct buffer_head *bh) 731da177e4SLinus Torvalds { 741da177e4SLinus Torvalds wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer, 751da177e4SLinus Torvalds TASK_UNINTERRUPTIBLE); 761da177e4SLinus Torvalds } 771da177e4SLinus Torvalds EXPORT_SYMBOL(__lock_buffer); 781da177e4SLinus Torvalds 791da177e4SLinus Torvalds void fastcall unlock_buffer(struct buffer_head *bh) 801da177e4SLinus Torvalds { 811da177e4SLinus Torvalds clear_buffer_locked(bh); 821da177e4SLinus Torvalds smp_mb__after_clear_bit(); 831da177e4SLinus Torvalds wake_up_bit(&bh->b_state, BH_Lock); 841da177e4SLinus Torvalds } 851da177e4SLinus Torvalds 861da177e4SLinus Torvalds /* 871da177e4SLinus Torvalds * Block until a buffer comes unlocked. This doesn't stop it 881da177e4SLinus Torvalds * from becoming locked again - you have to lock it yourself 891da177e4SLinus Torvalds * if you want to preserve its state. 901da177e4SLinus Torvalds */ 911da177e4SLinus Torvalds void __wait_on_buffer(struct buffer_head * bh) 921da177e4SLinus Torvalds { 931da177e4SLinus Torvalds wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE); 941da177e4SLinus Torvalds } 951da177e4SLinus Torvalds 961da177e4SLinus Torvalds static void 971da177e4SLinus Torvalds __clear_page_buffers(struct page *page) 981da177e4SLinus Torvalds { 991da177e4SLinus Torvalds ClearPagePrivate(page); 1004c21e2f2SHugh Dickins set_page_private(page, 0); 1011da177e4SLinus Torvalds page_cache_release(page); 1021da177e4SLinus Torvalds } 1031da177e4SLinus Torvalds 1041da177e4SLinus Torvalds static void buffer_io_error(struct buffer_head *bh) 1051da177e4SLinus Torvalds { 1061da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 1071da177e4SLinus Torvalds 1081da177e4SLinus Torvalds printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", 1091da177e4SLinus Torvalds bdevname(bh->b_bdev, b), 1101da177e4SLinus Torvalds (unsigned long long)bh->b_blocknr); 1111da177e4SLinus Torvalds } 1121da177e4SLinus Torvalds 1131da177e4SLinus Torvalds /* 1141da177e4SLinus Torvalds * Default synchronous end-of-IO handler.. Just mark it up-to-date and 1151da177e4SLinus Torvalds * unlock the buffer. This is what ll_rw_block uses too. 1161da177e4SLinus Torvalds */ 1171da177e4SLinus Torvalds void end_buffer_read_sync(struct buffer_head *bh, int uptodate) 1181da177e4SLinus Torvalds { 1191da177e4SLinus Torvalds if (uptodate) { 1201da177e4SLinus Torvalds set_buffer_uptodate(bh); 1211da177e4SLinus Torvalds } else { 1221da177e4SLinus Torvalds /* This happens, due to failed READA attempts. */ 1231da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1241da177e4SLinus Torvalds } 1251da177e4SLinus Torvalds unlock_buffer(bh); 1261da177e4SLinus Torvalds put_bh(bh); 1271da177e4SLinus Torvalds } 1281da177e4SLinus Torvalds 1291da177e4SLinus Torvalds void end_buffer_write_sync(struct buffer_head *bh, int uptodate) 1301da177e4SLinus Torvalds { 1311da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 1321da177e4SLinus Torvalds 1331da177e4SLinus Torvalds if (uptodate) { 1341da177e4SLinus Torvalds set_buffer_uptodate(bh); 1351da177e4SLinus Torvalds } else { 1361da177e4SLinus Torvalds if (!buffer_eopnotsupp(bh) && printk_ratelimit()) { 1371da177e4SLinus Torvalds buffer_io_error(bh); 1381da177e4SLinus Torvalds printk(KERN_WARNING "lost page write due to " 1391da177e4SLinus Torvalds "I/O error on %s\n", 1401da177e4SLinus Torvalds bdevname(bh->b_bdev, b)); 1411da177e4SLinus Torvalds } 1421da177e4SLinus Torvalds set_buffer_write_io_error(bh); 1431da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1441da177e4SLinus Torvalds } 1451da177e4SLinus Torvalds unlock_buffer(bh); 1461da177e4SLinus Torvalds put_bh(bh); 1471da177e4SLinus Torvalds } 1481da177e4SLinus Torvalds 1491da177e4SLinus Torvalds /* 1501da177e4SLinus Torvalds * Write out and wait upon all the dirty data associated with a block 1511da177e4SLinus Torvalds * device via its mapping. Does not take the superblock lock. 1521da177e4SLinus Torvalds */ 1531da177e4SLinus Torvalds int sync_blockdev(struct block_device *bdev) 1541da177e4SLinus Torvalds { 1551da177e4SLinus Torvalds int ret = 0; 1561da177e4SLinus Torvalds 15728fd1298SOGAWA Hirofumi if (bdev) 15828fd1298SOGAWA Hirofumi ret = filemap_write_and_wait(bdev->bd_inode->i_mapping); 1591da177e4SLinus Torvalds return ret; 1601da177e4SLinus Torvalds } 1611da177e4SLinus Torvalds EXPORT_SYMBOL(sync_blockdev); 1621da177e4SLinus Torvalds 1631da177e4SLinus Torvalds /* 1641da177e4SLinus Torvalds * Write out and wait upon all dirty data associated with this 1651da177e4SLinus Torvalds * device. Filesystem data as well as the underlying block 1661da177e4SLinus Torvalds * device. Takes the superblock lock. 1671da177e4SLinus Torvalds */ 1681da177e4SLinus Torvalds int fsync_bdev(struct block_device *bdev) 1691da177e4SLinus Torvalds { 1701da177e4SLinus Torvalds struct super_block *sb = get_super(bdev); 1711da177e4SLinus Torvalds if (sb) { 1721da177e4SLinus Torvalds int res = fsync_super(sb); 1731da177e4SLinus Torvalds drop_super(sb); 1741da177e4SLinus Torvalds return res; 1751da177e4SLinus Torvalds } 1761da177e4SLinus Torvalds return sync_blockdev(bdev); 1771da177e4SLinus Torvalds } 1781da177e4SLinus Torvalds 1791da177e4SLinus Torvalds /** 1801da177e4SLinus Torvalds * freeze_bdev -- lock a filesystem and force it into a consistent state 1811da177e4SLinus Torvalds * @bdev: blockdevice to lock 1821da177e4SLinus Torvalds * 183f73ca1b7SDavid Chinner * This takes the block device bd_mount_sem to make sure no new mounts 1841da177e4SLinus Torvalds * happen on bdev until thaw_bdev() is called. 1851da177e4SLinus Torvalds * If a superblock is found on this device, we take the s_umount semaphore 1861da177e4SLinus Torvalds * on it to make sure nobody unmounts until the snapshot creation is done. 1871da177e4SLinus Torvalds */ 1881da177e4SLinus Torvalds struct super_block *freeze_bdev(struct block_device *bdev) 1891da177e4SLinus Torvalds { 1901da177e4SLinus Torvalds struct super_block *sb; 1911da177e4SLinus Torvalds 192f73ca1b7SDavid Chinner down(&bdev->bd_mount_sem); 1931da177e4SLinus Torvalds sb = get_super(bdev); 1941da177e4SLinus Torvalds if (sb && !(sb->s_flags & MS_RDONLY)) { 1951da177e4SLinus Torvalds sb->s_frozen = SB_FREEZE_WRITE; 196d59dd462Sakpm@osdl.org smp_wmb(); 1971da177e4SLinus Torvalds 198d25b9a1fSOGAWA Hirofumi __fsync_super(sb); 1991da177e4SLinus Torvalds 2001da177e4SLinus Torvalds sb->s_frozen = SB_FREEZE_TRANS; 201d59dd462Sakpm@osdl.org smp_wmb(); 2021da177e4SLinus Torvalds 2031da177e4SLinus Torvalds sync_blockdev(sb->s_bdev); 2041da177e4SLinus Torvalds 2051da177e4SLinus Torvalds if (sb->s_op->write_super_lockfs) 2061da177e4SLinus Torvalds sb->s_op->write_super_lockfs(sb); 2071da177e4SLinus Torvalds } 2081da177e4SLinus Torvalds 2091da177e4SLinus Torvalds sync_blockdev(bdev); 2101da177e4SLinus Torvalds return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */ 2111da177e4SLinus Torvalds } 2121da177e4SLinus Torvalds EXPORT_SYMBOL(freeze_bdev); 2131da177e4SLinus Torvalds 2141da177e4SLinus Torvalds /** 2151da177e4SLinus Torvalds * thaw_bdev -- unlock filesystem 2161da177e4SLinus Torvalds * @bdev: blockdevice to unlock 2171da177e4SLinus Torvalds * @sb: associated superblock 2181da177e4SLinus Torvalds * 2191da177e4SLinus Torvalds * Unlocks the filesystem and marks it writeable again after freeze_bdev(). 2201da177e4SLinus Torvalds */ 2211da177e4SLinus Torvalds void thaw_bdev(struct block_device *bdev, struct super_block *sb) 2221da177e4SLinus Torvalds { 2231da177e4SLinus Torvalds if (sb) { 2241da177e4SLinus Torvalds BUG_ON(sb->s_bdev != bdev); 2251da177e4SLinus Torvalds 2261da177e4SLinus Torvalds if (sb->s_op->unlockfs) 2271da177e4SLinus Torvalds sb->s_op->unlockfs(sb); 2281da177e4SLinus Torvalds sb->s_frozen = SB_UNFROZEN; 229d59dd462Sakpm@osdl.org smp_wmb(); 2301da177e4SLinus Torvalds wake_up(&sb->s_wait_unfrozen); 2311da177e4SLinus Torvalds drop_super(sb); 2321da177e4SLinus Torvalds } 2331da177e4SLinus Torvalds 234f73ca1b7SDavid Chinner up(&bdev->bd_mount_sem); 2351da177e4SLinus Torvalds } 2361da177e4SLinus Torvalds EXPORT_SYMBOL(thaw_bdev); 2371da177e4SLinus Torvalds 2381da177e4SLinus Torvalds /* 2391da177e4SLinus Torvalds * Various filesystems appear to want __find_get_block to be non-blocking. 2401da177e4SLinus Torvalds * But it's the page lock which protects the buffers. To get around this, 2411da177e4SLinus Torvalds * we get exclusion from try_to_free_buffers with the blockdev mapping's 2421da177e4SLinus Torvalds * private_lock. 2431da177e4SLinus Torvalds * 2441da177e4SLinus Torvalds * Hack idea: for the blockdev mapping, i_bufferlist_lock contention 2451da177e4SLinus Torvalds * may be quite high. This code could TryLock the page, and if that 2461da177e4SLinus Torvalds * succeeds, there is no need to take private_lock. (But if 2471da177e4SLinus Torvalds * private_lock is contended then so is mapping->tree_lock). 2481da177e4SLinus Torvalds */ 2491da177e4SLinus Torvalds static struct buffer_head * 250385fd4c5SCoywolf Qi Hunt __find_get_block_slow(struct block_device *bdev, sector_t block) 2511da177e4SLinus Torvalds { 2521da177e4SLinus Torvalds struct inode *bd_inode = bdev->bd_inode; 2531da177e4SLinus Torvalds struct address_space *bd_mapping = bd_inode->i_mapping; 2541da177e4SLinus Torvalds struct buffer_head *ret = NULL; 2551da177e4SLinus Torvalds pgoff_t index; 2561da177e4SLinus Torvalds struct buffer_head *bh; 2571da177e4SLinus Torvalds struct buffer_head *head; 2581da177e4SLinus Torvalds struct page *page; 2591da177e4SLinus Torvalds int all_mapped = 1; 2601da177e4SLinus Torvalds 2611da177e4SLinus Torvalds index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); 2621da177e4SLinus Torvalds page = find_get_page(bd_mapping, index); 2631da177e4SLinus Torvalds if (!page) 2641da177e4SLinus Torvalds goto out; 2651da177e4SLinus Torvalds 2661da177e4SLinus Torvalds spin_lock(&bd_mapping->private_lock); 2671da177e4SLinus Torvalds if (!page_has_buffers(page)) 2681da177e4SLinus Torvalds goto out_unlock; 2691da177e4SLinus Torvalds head = page_buffers(page); 2701da177e4SLinus Torvalds bh = head; 2711da177e4SLinus Torvalds do { 2721da177e4SLinus Torvalds if (bh->b_blocknr == block) { 2731da177e4SLinus Torvalds ret = bh; 2741da177e4SLinus Torvalds get_bh(bh); 2751da177e4SLinus Torvalds goto out_unlock; 2761da177e4SLinus Torvalds } 2771da177e4SLinus Torvalds if (!buffer_mapped(bh)) 2781da177e4SLinus Torvalds all_mapped = 0; 2791da177e4SLinus Torvalds bh = bh->b_this_page; 2801da177e4SLinus Torvalds } while (bh != head); 2811da177e4SLinus Torvalds 2821da177e4SLinus Torvalds /* we might be here because some of the buffers on this page are 2831da177e4SLinus Torvalds * not mapped. This is due to various races between 2841da177e4SLinus Torvalds * file io on the block device and getblk. It gets dealt with 2851da177e4SLinus Torvalds * elsewhere, don't buffer_error if we had some unmapped buffers 2861da177e4SLinus Torvalds */ 2871da177e4SLinus Torvalds if (all_mapped) { 2881da177e4SLinus Torvalds printk("__find_get_block_slow() failed. " 2891da177e4SLinus Torvalds "block=%llu, b_blocknr=%llu\n", 290205f87f6SBadari Pulavarty (unsigned long long)block, 291205f87f6SBadari Pulavarty (unsigned long long)bh->b_blocknr); 292205f87f6SBadari Pulavarty printk("b_state=0x%08lx, b_size=%zu\n", 293205f87f6SBadari Pulavarty bh->b_state, bh->b_size); 2941da177e4SLinus Torvalds printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); 2951da177e4SLinus Torvalds } 2961da177e4SLinus Torvalds out_unlock: 2971da177e4SLinus Torvalds spin_unlock(&bd_mapping->private_lock); 2981da177e4SLinus Torvalds page_cache_release(page); 2991da177e4SLinus Torvalds out: 3001da177e4SLinus Torvalds return ret; 3011da177e4SLinus Torvalds } 3021da177e4SLinus Torvalds 3031da177e4SLinus Torvalds /* If invalidate_buffers() will trash dirty buffers, it means some kind 3041da177e4SLinus Torvalds of fs corruption is going on. Trashing dirty data always imply losing 3051da177e4SLinus Torvalds information that was supposed to be just stored on the physical layer 3061da177e4SLinus Torvalds by the user. 3071da177e4SLinus Torvalds 3081da177e4SLinus Torvalds Thus invalidate_buffers in general usage is not allwowed to trash 3091da177e4SLinus Torvalds dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to 3101da177e4SLinus Torvalds be preserved. These buffers are simply skipped. 3111da177e4SLinus Torvalds 3121da177e4SLinus Torvalds We also skip buffers which are still in use. For example this can 3131da177e4SLinus Torvalds happen if a userspace program is reading the block device. 3141da177e4SLinus Torvalds 3151da177e4SLinus Torvalds NOTE: In the case where the user removed a removable-media-disk even if 3161da177e4SLinus Torvalds there's still dirty data not synced on disk (due a bug in the device driver 3171da177e4SLinus Torvalds or due an error of the user), by not destroying the dirty buffers we could 3181da177e4SLinus Torvalds generate corruption also on the next media inserted, thus a parameter is 3191da177e4SLinus Torvalds necessary to handle this case in the most safe way possible (trying 3201da177e4SLinus Torvalds to not corrupt also the new disk inserted with the data belonging to 3211da177e4SLinus Torvalds the old now corrupted disk). Also for the ramdisk the natural thing 3221da177e4SLinus Torvalds to do in order to release the ramdisk memory is to destroy dirty buffers. 3231da177e4SLinus Torvalds 3241da177e4SLinus Torvalds These are two special cases. Normal usage imply the device driver 3251da177e4SLinus Torvalds to issue a sync on the device (without waiting I/O completion) and 3261da177e4SLinus Torvalds then an invalidate_buffers call that doesn't trash dirty buffers. 3271da177e4SLinus Torvalds 3281da177e4SLinus Torvalds For handling cache coherency with the blkdev pagecache the 'update' case 3291da177e4SLinus Torvalds is been introduced. It is needed to re-read from disk any pinned 3301da177e4SLinus Torvalds buffer. NOTE: re-reading from disk is destructive so we can do it only 3311da177e4SLinus Torvalds when we assume nobody is changing the buffercache under our I/O and when 3321da177e4SLinus Torvalds we think the disk contains more recent information than the buffercache. 3331da177e4SLinus Torvalds The update == 1 pass marks the buffers we need to update, the update == 2 3341da177e4SLinus Torvalds pass does the actual I/O. */ 3351da177e4SLinus Torvalds void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers) 3361da177e4SLinus Torvalds { 3370e1dfc66SAndrew Morton struct address_space *mapping = bdev->bd_inode->i_mapping; 3380e1dfc66SAndrew Morton 3390e1dfc66SAndrew Morton if (mapping->nrpages == 0) 3400e1dfc66SAndrew Morton return; 3410e1dfc66SAndrew Morton 3421da177e4SLinus Torvalds invalidate_bh_lrus(); 3431da177e4SLinus Torvalds /* 3441da177e4SLinus Torvalds * FIXME: what about destroy_dirty_buffers? 3451da177e4SLinus Torvalds * We really want to use invalidate_inode_pages2() for 3461da177e4SLinus Torvalds * that, but not until that's cleaned up. 3471da177e4SLinus Torvalds */ 348*fc0ecff6SAndrew Morton invalidate_mapping_pages(mapping, 0, -1); 3491da177e4SLinus Torvalds } 3501da177e4SLinus Torvalds 3511da177e4SLinus Torvalds /* 3521da177e4SLinus Torvalds * Kick pdflush then try to free up some ZONE_NORMAL memory. 3531da177e4SLinus Torvalds */ 3541da177e4SLinus Torvalds static void free_more_memory(void) 3551da177e4SLinus Torvalds { 3561da177e4SLinus Torvalds struct zone **zones; 3571da177e4SLinus Torvalds pg_data_t *pgdat; 3581da177e4SLinus Torvalds 359687a21ceSPekka J Enberg wakeup_pdflush(1024); 3601da177e4SLinus Torvalds yield(); 3611da177e4SLinus Torvalds 362ec936fc5SKAMEZAWA Hiroyuki for_each_online_pgdat(pgdat) { 363af4ca457SAl Viro zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones; 3641da177e4SLinus Torvalds if (*zones) 3651ad539b2SDarren Hart try_to_free_pages(zones, GFP_NOFS); 3661da177e4SLinus Torvalds } 3671da177e4SLinus Torvalds } 3681da177e4SLinus Torvalds 3691da177e4SLinus Torvalds /* 3701da177e4SLinus Torvalds * I/O completion handler for block_read_full_page() - pages 3711da177e4SLinus Torvalds * which come unlocked at the end of I/O. 3721da177e4SLinus Torvalds */ 3731da177e4SLinus Torvalds static void end_buffer_async_read(struct buffer_head *bh, int uptodate) 3741da177e4SLinus Torvalds { 3751da177e4SLinus Torvalds unsigned long flags; 376a3972203SNick Piggin struct buffer_head *first; 3771da177e4SLinus Torvalds struct buffer_head *tmp; 3781da177e4SLinus Torvalds struct page *page; 3791da177e4SLinus Torvalds int page_uptodate = 1; 3801da177e4SLinus Torvalds 3811da177e4SLinus Torvalds BUG_ON(!buffer_async_read(bh)); 3821da177e4SLinus Torvalds 3831da177e4SLinus Torvalds page = bh->b_page; 3841da177e4SLinus Torvalds if (uptodate) { 3851da177e4SLinus Torvalds set_buffer_uptodate(bh); 3861da177e4SLinus Torvalds } else { 3871da177e4SLinus Torvalds clear_buffer_uptodate(bh); 3881da177e4SLinus Torvalds if (printk_ratelimit()) 3891da177e4SLinus Torvalds buffer_io_error(bh); 3901da177e4SLinus Torvalds SetPageError(page); 3911da177e4SLinus Torvalds } 3921da177e4SLinus Torvalds 3931da177e4SLinus Torvalds /* 3941da177e4SLinus Torvalds * Be _very_ careful from here on. Bad things can happen if 3951da177e4SLinus Torvalds * two buffer heads end IO at almost the same time and both 3961da177e4SLinus Torvalds * decide that the page is now completely done. 3971da177e4SLinus Torvalds */ 398a3972203SNick Piggin first = page_buffers(page); 399a3972203SNick Piggin local_irq_save(flags); 400a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 4011da177e4SLinus Torvalds clear_buffer_async_read(bh); 4021da177e4SLinus Torvalds unlock_buffer(bh); 4031da177e4SLinus Torvalds tmp = bh; 4041da177e4SLinus Torvalds do { 4051da177e4SLinus Torvalds if (!buffer_uptodate(tmp)) 4061da177e4SLinus Torvalds page_uptodate = 0; 4071da177e4SLinus Torvalds if (buffer_async_read(tmp)) { 4081da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 4091da177e4SLinus Torvalds goto still_busy; 4101da177e4SLinus Torvalds } 4111da177e4SLinus Torvalds tmp = tmp->b_this_page; 4121da177e4SLinus Torvalds } while (tmp != bh); 413a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 414a3972203SNick Piggin local_irq_restore(flags); 4151da177e4SLinus Torvalds 4161da177e4SLinus Torvalds /* 4171da177e4SLinus Torvalds * If none of the buffers had errors and they are all 4181da177e4SLinus Torvalds * uptodate then we can set the page uptodate. 4191da177e4SLinus Torvalds */ 4201da177e4SLinus Torvalds if (page_uptodate && !PageError(page)) 4211da177e4SLinus Torvalds SetPageUptodate(page); 4221da177e4SLinus Torvalds unlock_page(page); 4231da177e4SLinus Torvalds return; 4241da177e4SLinus Torvalds 4251da177e4SLinus Torvalds still_busy: 426a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 427a3972203SNick Piggin local_irq_restore(flags); 4281da177e4SLinus Torvalds return; 4291da177e4SLinus Torvalds } 4301da177e4SLinus Torvalds 4311da177e4SLinus Torvalds /* 4321da177e4SLinus Torvalds * Completion handler for block_write_full_page() - pages which are unlocked 4331da177e4SLinus Torvalds * during I/O, and which have PageWriteback cleared upon I/O completion. 4341da177e4SLinus Torvalds */ 435b6cd0b77SAdrian Bunk static void end_buffer_async_write(struct buffer_head *bh, int uptodate) 4361da177e4SLinus Torvalds { 4371da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 4381da177e4SLinus Torvalds unsigned long flags; 439a3972203SNick Piggin struct buffer_head *first; 4401da177e4SLinus Torvalds struct buffer_head *tmp; 4411da177e4SLinus Torvalds struct page *page; 4421da177e4SLinus Torvalds 4431da177e4SLinus Torvalds BUG_ON(!buffer_async_write(bh)); 4441da177e4SLinus Torvalds 4451da177e4SLinus Torvalds page = bh->b_page; 4461da177e4SLinus Torvalds if (uptodate) { 4471da177e4SLinus Torvalds set_buffer_uptodate(bh); 4481da177e4SLinus Torvalds } else { 4491da177e4SLinus Torvalds if (printk_ratelimit()) { 4501da177e4SLinus Torvalds buffer_io_error(bh); 4511da177e4SLinus Torvalds printk(KERN_WARNING "lost page write due to " 4521da177e4SLinus Torvalds "I/O error on %s\n", 4531da177e4SLinus Torvalds bdevname(bh->b_bdev, b)); 4541da177e4SLinus Torvalds } 4551da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 45658ff407bSJan Kara set_buffer_write_io_error(bh); 4571da177e4SLinus Torvalds clear_buffer_uptodate(bh); 4581da177e4SLinus Torvalds SetPageError(page); 4591da177e4SLinus Torvalds } 4601da177e4SLinus Torvalds 461a3972203SNick Piggin first = page_buffers(page); 462a3972203SNick Piggin local_irq_save(flags); 463a3972203SNick Piggin bit_spin_lock(BH_Uptodate_Lock, &first->b_state); 464a3972203SNick Piggin 4651da177e4SLinus Torvalds clear_buffer_async_write(bh); 4661da177e4SLinus Torvalds unlock_buffer(bh); 4671da177e4SLinus Torvalds tmp = bh->b_this_page; 4681da177e4SLinus Torvalds while (tmp != bh) { 4691da177e4SLinus Torvalds if (buffer_async_write(tmp)) { 4701da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 4711da177e4SLinus Torvalds goto still_busy; 4721da177e4SLinus Torvalds } 4731da177e4SLinus Torvalds tmp = tmp->b_this_page; 4741da177e4SLinus Torvalds } 475a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 476a3972203SNick Piggin local_irq_restore(flags); 4771da177e4SLinus Torvalds end_page_writeback(page); 4781da177e4SLinus Torvalds return; 4791da177e4SLinus Torvalds 4801da177e4SLinus Torvalds still_busy: 481a3972203SNick Piggin bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); 482a3972203SNick Piggin local_irq_restore(flags); 4831da177e4SLinus Torvalds return; 4841da177e4SLinus Torvalds } 4851da177e4SLinus Torvalds 4861da177e4SLinus Torvalds /* 4871da177e4SLinus Torvalds * If a page's buffers are under async readin (end_buffer_async_read 4881da177e4SLinus Torvalds * completion) then there is a possibility that another thread of 4891da177e4SLinus Torvalds * control could lock one of the buffers after it has completed 4901da177e4SLinus Torvalds * but while some of the other buffers have not completed. This 4911da177e4SLinus Torvalds * locked buffer would confuse end_buffer_async_read() into not unlocking 4921da177e4SLinus Torvalds * the page. So the absence of BH_Async_Read tells end_buffer_async_read() 4931da177e4SLinus Torvalds * that this buffer is not under async I/O. 4941da177e4SLinus Torvalds * 4951da177e4SLinus Torvalds * The page comes unlocked when it has no locked buffer_async buffers 4961da177e4SLinus Torvalds * left. 4971da177e4SLinus Torvalds * 4981da177e4SLinus Torvalds * PageLocked prevents anyone starting new async I/O reads any of 4991da177e4SLinus Torvalds * the buffers. 5001da177e4SLinus Torvalds * 5011da177e4SLinus Torvalds * PageWriteback is used to prevent simultaneous writeout of the same 5021da177e4SLinus Torvalds * page. 5031da177e4SLinus Torvalds * 5041da177e4SLinus Torvalds * PageLocked prevents anyone from starting writeback of a page which is 5051da177e4SLinus Torvalds * under read I/O (PageWriteback is only ever set against a locked page). 5061da177e4SLinus Torvalds */ 5071da177e4SLinus Torvalds static void mark_buffer_async_read(struct buffer_head *bh) 5081da177e4SLinus Torvalds { 5091da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_read; 5101da177e4SLinus Torvalds set_buffer_async_read(bh); 5111da177e4SLinus Torvalds } 5121da177e4SLinus Torvalds 5131da177e4SLinus Torvalds void mark_buffer_async_write(struct buffer_head *bh) 5141da177e4SLinus Torvalds { 5151da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_write; 5161da177e4SLinus Torvalds set_buffer_async_write(bh); 5171da177e4SLinus Torvalds } 5181da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_async_write); 5191da177e4SLinus Torvalds 5201da177e4SLinus Torvalds 5211da177e4SLinus Torvalds /* 5221da177e4SLinus Torvalds * fs/buffer.c contains helper functions for buffer-backed address space's 5231da177e4SLinus Torvalds * fsync functions. A common requirement for buffer-based filesystems is 5241da177e4SLinus Torvalds * that certain data from the backing blockdev needs to be written out for 5251da177e4SLinus Torvalds * a successful fsync(). For example, ext2 indirect blocks need to be 5261da177e4SLinus Torvalds * written back and waited upon before fsync() returns. 5271da177e4SLinus Torvalds * 5281da177e4SLinus Torvalds * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), 5291da177e4SLinus Torvalds * inode_has_buffers() and invalidate_inode_buffers() are provided for the 5301da177e4SLinus Torvalds * management of a list of dependent buffers at ->i_mapping->private_list. 5311da177e4SLinus Torvalds * 5321da177e4SLinus Torvalds * Locking is a little subtle: try_to_free_buffers() will remove buffers 5331da177e4SLinus Torvalds * from their controlling inode's queue when they are being freed. But 5341da177e4SLinus Torvalds * try_to_free_buffers() will be operating against the *blockdev* mapping 5351da177e4SLinus Torvalds * at the time, not against the S_ISREG file which depends on those buffers. 5361da177e4SLinus Torvalds * So the locking for private_list is via the private_lock in the address_space 5371da177e4SLinus Torvalds * which backs the buffers. Which is different from the address_space 5381da177e4SLinus Torvalds * against which the buffers are listed. So for a particular address_space, 5391da177e4SLinus Torvalds * mapping->private_lock does *not* protect mapping->private_list! In fact, 5401da177e4SLinus Torvalds * mapping->private_list will always be protected by the backing blockdev's 5411da177e4SLinus Torvalds * ->private_lock. 5421da177e4SLinus Torvalds * 5431da177e4SLinus Torvalds * Which introduces a requirement: all buffers on an address_space's 5441da177e4SLinus Torvalds * ->private_list must be from the same address_space: the blockdev's. 5451da177e4SLinus Torvalds * 5461da177e4SLinus Torvalds * address_spaces which do not place buffers at ->private_list via these 5471da177e4SLinus Torvalds * utility functions are free to use private_lock and private_list for 5481da177e4SLinus Torvalds * whatever they want. The only requirement is that list_empty(private_list) 5491da177e4SLinus Torvalds * be true at clear_inode() time. 5501da177e4SLinus Torvalds * 5511da177e4SLinus Torvalds * FIXME: clear_inode should not call invalidate_inode_buffers(). The 5521da177e4SLinus Torvalds * filesystems should do that. invalidate_inode_buffers() should just go 5531da177e4SLinus Torvalds * BUG_ON(!list_empty). 5541da177e4SLinus Torvalds * 5551da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should 5561da177e4SLinus Torvalds * take an address_space, not an inode. And it should be called 5571da177e4SLinus Torvalds * mark_buffer_dirty_fsync() to clearly define why those buffers are being 5581da177e4SLinus Torvalds * queued up. 5591da177e4SLinus Torvalds * 5601da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the 5611da177e4SLinus Torvalds * list if it is already on a list. Because if the buffer is on a list, 5621da177e4SLinus Torvalds * it *must* already be on the right one. If not, the filesystem is being 5631da177e4SLinus Torvalds * silly. This will save a ton of locking. But first we have to ensure 5641da177e4SLinus Torvalds * that buffers are taken *off* the old inode's list when they are freed 5651da177e4SLinus Torvalds * (presumably in truncate). That requires careful auditing of all 5661da177e4SLinus Torvalds * filesystems (do it inside bforget()). It could also be done by bringing 5671da177e4SLinus Torvalds * b_inode back. 5681da177e4SLinus Torvalds */ 5691da177e4SLinus Torvalds 5701da177e4SLinus Torvalds /* 5711da177e4SLinus Torvalds * The buffer's backing address_space's private_lock must be held 5721da177e4SLinus Torvalds */ 5731da177e4SLinus Torvalds static inline void __remove_assoc_queue(struct buffer_head *bh) 5741da177e4SLinus Torvalds { 5751da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 57658ff407bSJan Kara WARN_ON(!bh->b_assoc_map); 57758ff407bSJan Kara if (buffer_write_io_error(bh)) 57858ff407bSJan Kara set_bit(AS_EIO, &bh->b_assoc_map->flags); 57958ff407bSJan Kara bh->b_assoc_map = NULL; 5801da177e4SLinus Torvalds } 5811da177e4SLinus Torvalds 5821da177e4SLinus Torvalds int inode_has_buffers(struct inode *inode) 5831da177e4SLinus Torvalds { 5841da177e4SLinus Torvalds return !list_empty(&inode->i_data.private_list); 5851da177e4SLinus Torvalds } 5861da177e4SLinus Torvalds 5871da177e4SLinus Torvalds /* 5881da177e4SLinus Torvalds * osync is designed to support O_SYNC io. It waits synchronously for 5891da177e4SLinus Torvalds * all already-submitted IO to complete, but does not queue any new 5901da177e4SLinus Torvalds * writes to the disk. 5911da177e4SLinus Torvalds * 5921da177e4SLinus Torvalds * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as 5931da177e4SLinus Torvalds * you dirty the buffers, and then use osync_inode_buffers to wait for 5941da177e4SLinus Torvalds * completion. Any other dirty buffers which are not yet queued for 5951da177e4SLinus Torvalds * write will not be flushed to disk by the osync. 5961da177e4SLinus Torvalds */ 5971da177e4SLinus Torvalds static int osync_buffers_list(spinlock_t *lock, struct list_head *list) 5981da177e4SLinus Torvalds { 5991da177e4SLinus Torvalds struct buffer_head *bh; 6001da177e4SLinus Torvalds struct list_head *p; 6011da177e4SLinus Torvalds int err = 0; 6021da177e4SLinus Torvalds 6031da177e4SLinus Torvalds spin_lock(lock); 6041da177e4SLinus Torvalds repeat: 6051da177e4SLinus Torvalds list_for_each_prev(p, list) { 6061da177e4SLinus Torvalds bh = BH_ENTRY(p); 6071da177e4SLinus Torvalds if (buffer_locked(bh)) { 6081da177e4SLinus Torvalds get_bh(bh); 6091da177e4SLinus Torvalds spin_unlock(lock); 6101da177e4SLinus Torvalds wait_on_buffer(bh); 6111da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 6121da177e4SLinus Torvalds err = -EIO; 6131da177e4SLinus Torvalds brelse(bh); 6141da177e4SLinus Torvalds spin_lock(lock); 6151da177e4SLinus Torvalds goto repeat; 6161da177e4SLinus Torvalds } 6171da177e4SLinus Torvalds } 6181da177e4SLinus Torvalds spin_unlock(lock); 6191da177e4SLinus Torvalds return err; 6201da177e4SLinus Torvalds } 6211da177e4SLinus Torvalds 6221da177e4SLinus Torvalds /** 6231da177e4SLinus Torvalds * sync_mapping_buffers - write out and wait upon a mapping's "associated" 6241da177e4SLinus Torvalds * buffers 62567be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 6261da177e4SLinus Torvalds * 6271da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 6281da177e4SLinus Torvalds * that I/O. 6291da177e4SLinus Torvalds * 63067be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 63167be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 63267be2dd1SMartin Waitz * a successful fsync(). 6331da177e4SLinus Torvalds */ 6341da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 6351da177e4SLinus Torvalds { 6361da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 6371da177e4SLinus Torvalds 6381da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 6391da177e4SLinus Torvalds return 0; 6401da177e4SLinus Torvalds 6411da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 6421da177e4SLinus Torvalds &mapping->private_list); 6431da177e4SLinus Torvalds } 6441da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 6451da177e4SLinus Torvalds 6461da177e4SLinus Torvalds /* 6471da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 6481da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 6491da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 6501da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 6511da177e4SLinus Torvalds */ 6521da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 6531da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 6541da177e4SLinus Torvalds { 6551da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 6561da177e4SLinus Torvalds if (bh) { 6571da177e4SLinus Torvalds if (buffer_dirty(bh)) 6581da177e4SLinus Torvalds ll_rw_block(WRITE, 1, &bh); 6591da177e4SLinus Torvalds put_bh(bh); 6601da177e4SLinus Torvalds } 6611da177e4SLinus Torvalds } 6621da177e4SLinus Torvalds 6631da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 6641da177e4SLinus Torvalds { 6651da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 6661da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 6671da177e4SLinus Torvalds 6681da177e4SLinus Torvalds mark_buffer_dirty(bh); 6691da177e4SLinus Torvalds if (!mapping->assoc_mapping) { 6701da177e4SLinus Torvalds mapping->assoc_mapping = buffer_mapping; 6711da177e4SLinus Torvalds } else { 672e827f923SEric Sesterhenn BUG_ON(mapping->assoc_mapping != buffer_mapping); 6731da177e4SLinus Torvalds } 6741da177e4SLinus Torvalds if (list_empty(&bh->b_assoc_buffers)) { 6751da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 6761da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 6771da177e4SLinus Torvalds &mapping->private_list); 67858ff407bSJan Kara bh->b_assoc_map = mapping; 6791da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 6801da177e4SLinus Torvalds } 6811da177e4SLinus Torvalds } 6821da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 6831da177e4SLinus Torvalds 6841da177e4SLinus Torvalds /* 6851da177e4SLinus Torvalds * Add a page to the dirty page list. 6861da177e4SLinus Torvalds * 6871da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 6881da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 6891da177e4SLinus Torvalds * 6901da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 6911da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 6921da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 6931da177e4SLinus Torvalds * dirty. 6941da177e4SLinus Torvalds * 6951da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 6961da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 6971da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 6981da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 6991da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 7001da177e4SLinus Torvalds * page on the dirty page list. 7011da177e4SLinus Torvalds * 7021da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 7031da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 7041da177e4SLinus Torvalds * added to the page after it was set dirty. 7051da177e4SLinus Torvalds * 7061da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 7071da177e4SLinus Torvalds * address_space though. 7081da177e4SLinus Torvalds */ 7091da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 7101da177e4SLinus Torvalds { 711ebf7a227SNick Piggin struct address_space * const mapping = page_mapping(page); 712ebf7a227SNick Piggin 713ebf7a227SNick Piggin if (unlikely(!mapping)) 714ebf7a227SNick Piggin return !TestSetPageDirty(page); 7151da177e4SLinus Torvalds 7161da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 7171da177e4SLinus Torvalds if (page_has_buffers(page)) { 7181da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 7191da177e4SLinus Torvalds struct buffer_head *bh = head; 7201da177e4SLinus Torvalds 7211da177e4SLinus Torvalds do { 7221da177e4SLinus Torvalds set_buffer_dirty(bh); 7231da177e4SLinus Torvalds bh = bh->b_this_page; 7241da177e4SLinus Torvalds } while (bh != head); 7251da177e4SLinus Torvalds } 7261da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 7271da177e4SLinus Torvalds 7288c08540fSAndrew Morton if (TestSetPageDirty(page)) 7298c08540fSAndrew Morton return 0; 7308c08540fSAndrew Morton 7311da177e4SLinus Torvalds write_lock_irq(&mapping->tree_lock); 7321da177e4SLinus Torvalds if (page->mapping) { /* Race with truncate? */ 73355e829afSAndrew Morton if (mapping_cap_account_dirty(mapping)) { 734b1e7a8fdSChristoph Lameter __inc_zone_page_state(page, NR_FILE_DIRTY); 73555e829afSAndrew Morton task_io_account_write(PAGE_CACHE_SIZE); 73655e829afSAndrew Morton } 7371da177e4SLinus Torvalds radix_tree_tag_set(&mapping->page_tree, 7388c08540fSAndrew Morton page_index(page), PAGECACHE_TAG_DIRTY); 7391da177e4SLinus Torvalds } 7401da177e4SLinus Torvalds write_unlock_irq(&mapping->tree_lock); 7411da177e4SLinus Torvalds __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 7424741c9fdSAndrew Morton return 1; 7431da177e4SLinus Torvalds } 7441da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 7451da177e4SLinus Torvalds 7461da177e4SLinus Torvalds /* 7471da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 7481da177e4SLinus Torvalds * 7491da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 7501da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 7511da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 7521da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 7531da177e4SLinus Torvalds * 7541da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 7551da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 7561da177e4SLinus Torvalds * up, waiting for those writes to complete. 7571da177e4SLinus Torvalds * 7581da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 7591da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 7601da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 7611da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 7621da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 7631da177e4SLinus Torvalds * any newly dirty buffers for write. 7641da177e4SLinus Torvalds */ 7651da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 7661da177e4SLinus Torvalds { 7671da177e4SLinus Torvalds struct buffer_head *bh; 7681da177e4SLinus Torvalds struct list_head tmp; 7691da177e4SLinus Torvalds int err = 0, err2; 7701da177e4SLinus Torvalds 7711da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 7721da177e4SLinus Torvalds 7731da177e4SLinus Torvalds spin_lock(lock); 7741da177e4SLinus Torvalds while (!list_empty(list)) { 7751da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 77658ff407bSJan Kara __remove_assoc_queue(bh); 7771da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 7781da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 7791da177e4SLinus Torvalds if (buffer_dirty(bh)) { 7801da177e4SLinus Torvalds get_bh(bh); 7811da177e4SLinus Torvalds spin_unlock(lock); 7821da177e4SLinus Torvalds /* 7831da177e4SLinus Torvalds * Ensure any pending I/O completes so that 7841da177e4SLinus Torvalds * ll_rw_block() actually writes the current 7851da177e4SLinus Torvalds * contents - it is a noop if I/O is still in 7861da177e4SLinus Torvalds * flight on potentially older contents. 7871da177e4SLinus Torvalds */ 788a7662236SJan Kara ll_rw_block(SWRITE, 1, &bh); 7891da177e4SLinus Torvalds brelse(bh); 7901da177e4SLinus Torvalds spin_lock(lock); 7911da177e4SLinus Torvalds } 7921da177e4SLinus Torvalds } 7931da177e4SLinus Torvalds } 7941da177e4SLinus Torvalds 7951da177e4SLinus Torvalds while (!list_empty(&tmp)) { 7961da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 79758ff407bSJan Kara list_del_init(&bh->b_assoc_buffers); 7981da177e4SLinus Torvalds get_bh(bh); 7991da177e4SLinus Torvalds spin_unlock(lock); 8001da177e4SLinus Torvalds wait_on_buffer(bh); 8011da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 8021da177e4SLinus Torvalds err = -EIO; 8031da177e4SLinus Torvalds brelse(bh); 8041da177e4SLinus Torvalds spin_lock(lock); 8051da177e4SLinus Torvalds } 8061da177e4SLinus Torvalds 8071da177e4SLinus Torvalds spin_unlock(lock); 8081da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 8091da177e4SLinus Torvalds if (err) 8101da177e4SLinus Torvalds return err; 8111da177e4SLinus Torvalds else 8121da177e4SLinus Torvalds return err2; 8131da177e4SLinus Torvalds } 8141da177e4SLinus Torvalds 8151da177e4SLinus Torvalds /* 8161da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 8171da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 8181da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 8191da177e4SLinus Torvalds * 8201da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 8211da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 8221da177e4SLinus Torvalds * for reiserfs. 8231da177e4SLinus Torvalds */ 8241da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 8251da177e4SLinus Torvalds { 8261da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8271da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8281da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 8291da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 8301da177e4SLinus Torvalds 8311da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8321da177e4SLinus Torvalds while (!list_empty(list)) 8331da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 8341da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8351da177e4SLinus Torvalds } 8361da177e4SLinus Torvalds } 8371da177e4SLinus Torvalds 8381da177e4SLinus Torvalds /* 8391da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 8401da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 8411da177e4SLinus Torvalds * 8421da177e4SLinus Torvalds * Returns true if all buffers were removed. 8431da177e4SLinus Torvalds */ 8441da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 8451da177e4SLinus Torvalds { 8461da177e4SLinus Torvalds int ret = 1; 8471da177e4SLinus Torvalds 8481da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 8491da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 8501da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 8511da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 8521da177e4SLinus Torvalds 8531da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8541da177e4SLinus Torvalds while (!list_empty(list)) { 8551da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 8561da177e4SLinus Torvalds if (buffer_dirty(bh)) { 8571da177e4SLinus Torvalds ret = 0; 8581da177e4SLinus Torvalds break; 8591da177e4SLinus Torvalds } 8601da177e4SLinus Torvalds __remove_assoc_queue(bh); 8611da177e4SLinus Torvalds } 8621da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8631da177e4SLinus Torvalds } 8641da177e4SLinus Torvalds return ret; 8651da177e4SLinus Torvalds } 8661da177e4SLinus Torvalds 8671da177e4SLinus Torvalds /* 8681da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 8691da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 8701da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 8711da177e4SLinus Torvalds * buffers. 8721da177e4SLinus Torvalds * 8731da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 8741da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 8751da177e4SLinus Torvalds */ 8761da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 8771da177e4SLinus Torvalds int retry) 8781da177e4SLinus Torvalds { 8791da177e4SLinus Torvalds struct buffer_head *bh, *head; 8801da177e4SLinus Torvalds long offset; 8811da177e4SLinus Torvalds 8821da177e4SLinus Torvalds try_again: 8831da177e4SLinus Torvalds head = NULL; 8841da177e4SLinus Torvalds offset = PAGE_SIZE; 8851da177e4SLinus Torvalds while ((offset -= size) >= 0) { 8861da177e4SLinus Torvalds bh = alloc_buffer_head(GFP_NOFS); 8871da177e4SLinus Torvalds if (!bh) 8881da177e4SLinus Torvalds goto no_grow; 8891da177e4SLinus Torvalds 8901da177e4SLinus Torvalds bh->b_bdev = NULL; 8911da177e4SLinus Torvalds bh->b_this_page = head; 8921da177e4SLinus Torvalds bh->b_blocknr = -1; 8931da177e4SLinus Torvalds head = bh; 8941da177e4SLinus Torvalds 8951da177e4SLinus Torvalds bh->b_state = 0; 8961da177e4SLinus Torvalds atomic_set(&bh->b_count, 0); 897fc5cd582SChris Mason bh->b_private = NULL; 8981da177e4SLinus Torvalds bh->b_size = size; 8991da177e4SLinus Torvalds 9001da177e4SLinus Torvalds /* Link the buffer to its page */ 9011da177e4SLinus Torvalds set_bh_page(bh, page, offset); 9021da177e4SLinus Torvalds 90301ffe339SNathan Scott init_buffer(bh, NULL, NULL); 9041da177e4SLinus Torvalds } 9051da177e4SLinus Torvalds return head; 9061da177e4SLinus Torvalds /* 9071da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 9081da177e4SLinus Torvalds */ 9091da177e4SLinus Torvalds no_grow: 9101da177e4SLinus Torvalds if (head) { 9111da177e4SLinus Torvalds do { 9121da177e4SLinus Torvalds bh = head; 9131da177e4SLinus Torvalds head = head->b_this_page; 9141da177e4SLinus Torvalds free_buffer_head(bh); 9151da177e4SLinus Torvalds } while (head); 9161da177e4SLinus Torvalds } 9171da177e4SLinus Torvalds 9181da177e4SLinus Torvalds /* 9191da177e4SLinus Torvalds * Return failure for non-async IO requests. Async IO requests 9201da177e4SLinus Torvalds * are not allowed to fail, so we have to wait until buffer heads 9211da177e4SLinus Torvalds * become available. But we don't want tasks sleeping with 9221da177e4SLinus Torvalds * partially complete buffers, so all were released above. 9231da177e4SLinus Torvalds */ 9241da177e4SLinus Torvalds if (!retry) 9251da177e4SLinus Torvalds return NULL; 9261da177e4SLinus Torvalds 9271da177e4SLinus Torvalds /* We're _really_ low on memory. Now we just 9281da177e4SLinus Torvalds * wait for old buffer heads to become free due to 9291da177e4SLinus Torvalds * finishing IO. Since this is an async request and 9301da177e4SLinus Torvalds * the reserve list is empty, we're sure there are 9311da177e4SLinus Torvalds * async buffer heads in use. 9321da177e4SLinus Torvalds */ 9331da177e4SLinus Torvalds free_more_memory(); 9341da177e4SLinus Torvalds goto try_again; 9351da177e4SLinus Torvalds } 9361da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 9371da177e4SLinus Torvalds 9381da177e4SLinus Torvalds static inline void 9391da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 9401da177e4SLinus Torvalds { 9411da177e4SLinus Torvalds struct buffer_head *bh, *tail; 9421da177e4SLinus Torvalds 9431da177e4SLinus Torvalds bh = head; 9441da177e4SLinus Torvalds do { 9451da177e4SLinus Torvalds tail = bh; 9461da177e4SLinus Torvalds bh = bh->b_this_page; 9471da177e4SLinus Torvalds } while (bh); 9481da177e4SLinus Torvalds tail->b_this_page = head; 9491da177e4SLinus Torvalds attach_page_buffers(page, head); 9501da177e4SLinus Torvalds } 9511da177e4SLinus Torvalds 9521da177e4SLinus Torvalds /* 9531da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 9541da177e4SLinus Torvalds */ 9551da177e4SLinus Torvalds static void 9561da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 9571da177e4SLinus Torvalds sector_t block, int size) 9581da177e4SLinus Torvalds { 9591da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 9601da177e4SLinus Torvalds struct buffer_head *bh = head; 9611da177e4SLinus Torvalds int uptodate = PageUptodate(page); 9621da177e4SLinus Torvalds 9631da177e4SLinus Torvalds do { 9641da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 9651da177e4SLinus Torvalds init_buffer(bh, NULL, NULL); 9661da177e4SLinus Torvalds bh->b_bdev = bdev; 9671da177e4SLinus Torvalds bh->b_blocknr = block; 9681da177e4SLinus Torvalds if (uptodate) 9691da177e4SLinus Torvalds set_buffer_uptodate(bh); 9701da177e4SLinus Torvalds set_buffer_mapped(bh); 9711da177e4SLinus Torvalds } 9721da177e4SLinus Torvalds block++; 9731da177e4SLinus Torvalds bh = bh->b_this_page; 9741da177e4SLinus Torvalds } while (bh != head); 9751da177e4SLinus Torvalds } 9761da177e4SLinus Torvalds 9771da177e4SLinus Torvalds /* 9781da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 9791da177e4SLinus Torvalds * 9801da177e4SLinus Torvalds * This is user purely for blockdev mappings. 9811da177e4SLinus Torvalds */ 9821da177e4SLinus Torvalds static struct page * 9831da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 9841da177e4SLinus Torvalds pgoff_t index, int size) 9851da177e4SLinus Torvalds { 9861da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 9871da177e4SLinus Torvalds struct page *page; 9881da177e4SLinus Torvalds struct buffer_head *bh; 9891da177e4SLinus Torvalds 9901da177e4SLinus Torvalds page = find_or_create_page(inode->i_mapping, index, GFP_NOFS); 9911da177e4SLinus Torvalds if (!page) 9921da177e4SLinus Torvalds return NULL; 9931da177e4SLinus Torvalds 994e827f923SEric Sesterhenn BUG_ON(!PageLocked(page)); 9951da177e4SLinus Torvalds 9961da177e4SLinus Torvalds if (page_has_buffers(page)) { 9971da177e4SLinus Torvalds bh = page_buffers(page); 9981da177e4SLinus Torvalds if (bh->b_size == size) { 9991da177e4SLinus Torvalds init_page_buffers(page, bdev, block, size); 10001da177e4SLinus Torvalds return page; 10011da177e4SLinus Torvalds } 10021da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 10031da177e4SLinus Torvalds goto failed; 10041da177e4SLinus Torvalds } 10051da177e4SLinus Torvalds 10061da177e4SLinus Torvalds /* 10071da177e4SLinus Torvalds * Allocate some buffers for this page 10081da177e4SLinus Torvalds */ 10091da177e4SLinus Torvalds bh = alloc_page_buffers(page, size, 0); 10101da177e4SLinus Torvalds if (!bh) 10111da177e4SLinus Torvalds goto failed; 10121da177e4SLinus Torvalds 10131da177e4SLinus Torvalds /* 10141da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 10151da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 10161da177e4SLinus Torvalds * run under the page lock. 10171da177e4SLinus Torvalds */ 10181da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 10191da177e4SLinus Torvalds link_dev_buffers(page, bh); 10201da177e4SLinus Torvalds init_page_buffers(page, bdev, block, size); 10211da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 10221da177e4SLinus Torvalds return page; 10231da177e4SLinus Torvalds 10241da177e4SLinus Torvalds failed: 10251da177e4SLinus Torvalds BUG(); 10261da177e4SLinus Torvalds unlock_page(page); 10271da177e4SLinus Torvalds page_cache_release(page); 10281da177e4SLinus Torvalds return NULL; 10291da177e4SLinus Torvalds } 10301da177e4SLinus Torvalds 10311da177e4SLinus Torvalds /* 10321da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 10331da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 10341da177e4SLinus Torvalds * 10351da177e4SLinus Torvalds * Except that's a bug. Attaching dirty buffers to a dirty 10361da177e4SLinus Torvalds * blockdev's page can result in filesystem corruption, because 10371da177e4SLinus Torvalds * some of those buffers may be aliases of filesystem data. 10381da177e4SLinus Torvalds * grow_dev_page() will go BUG() if this happens. 10391da177e4SLinus Torvalds */ 1040858119e1SArjan van de Ven static int 10411da177e4SLinus Torvalds grow_buffers(struct block_device *bdev, sector_t block, int size) 10421da177e4SLinus Torvalds { 10431da177e4SLinus Torvalds struct page *page; 10441da177e4SLinus Torvalds pgoff_t index; 10451da177e4SLinus Torvalds int sizebits; 10461da177e4SLinus Torvalds 10471da177e4SLinus Torvalds sizebits = -1; 10481da177e4SLinus Torvalds do { 10491da177e4SLinus Torvalds sizebits++; 10501da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 10511da177e4SLinus Torvalds 10521da177e4SLinus Torvalds index = block >> sizebits; 10531da177e4SLinus Torvalds 1054e5657933SAndrew Morton /* 1055e5657933SAndrew Morton * Check for a block which wants to lie outside our maximum possible 1056e5657933SAndrew Morton * pagecache index. (this comparison is done using sector_t types). 1057e5657933SAndrew Morton */ 1058e5657933SAndrew Morton if (unlikely(index != block >> sizebits)) { 1059e5657933SAndrew Morton char b[BDEVNAME_SIZE]; 1060e5657933SAndrew Morton 1061e5657933SAndrew Morton printk(KERN_ERR "%s: requested out-of-range block %llu for " 1062e5657933SAndrew Morton "device %s\n", 1063e5657933SAndrew Morton __FUNCTION__, (unsigned long long)block, 1064e5657933SAndrew Morton bdevname(bdev, b)); 1065e5657933SAndrew Morton return -EIO; 1066e5657933SAndrew Morton } 1067e5657933SAndrew Morton block = index << sizebits; 10681da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 10691da177e4SLinus Torvalds page = grow_dev_page(bdev, block, index, size); 10701da177e4SLinus Torvalds if (!page) 10711da177e4SLinus Torvalds return 0; 10721da177e4SLinus Torvalds unlock_page(page); 10731da177e4SLinus Torvalds page_cache_release(page); 10741da177e4SLinus Torvalds return 1; 10751da177e4SLinus Torvalds } 10761da177e4SLinus Torvalds 107775c96f85SAdrian Bunk static struct buffer_head * 10781da177e4SLinus Torvalds __getblk_slow(struct block_device *bdev, sector_t block, int size) 10791da177e4SLinus Torvalds { 10801da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 10811da177e4SLinus Torvalds if (unlikely(size & (bdev_hardsect_size(bdev)-1) || 10821da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 10831da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 10841da177e4SLinus Torvalds size); 10851da177e4SLinus Torvalds printk(KERN_ERR "hardsect size: %d\n", 10861da177e4SLinus Torvalds bdev_hardsect_size(bdev)); 10871da177e4SLinus Torvalds 10881da177e4SLinus Torvalds dump_stack(); 10891da177e4SLinus Torvalds return NULL; 10901da177e4SLinus Torvalds } 10911da177e4SLinus Torvalds 10921da177e4SLinus Torvalds for (;;) { 10931da177e4SLinus Torvalds struct buffer_head * bh; 1094e5657933SAndrew Morton int ret; 10951da177e4SLinus Torvalds 10961da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 10971da177e4SLinus Torvalds if (bh) 10981da177e4SLinus Torvalds return bh; 10991da177e4SLinus Torvalds 1100e5657933SAndrew Morton ret = grow_buffers(bdev, block, size); 1101e5657933SAndrew Morton if (ret < 0) 1102e5657933SAndrew Morton return NULL; 1103e5657933SAndrew Morton if (ret == 0) 11041da177e4SLinus Torvalds free_more_memory(); 11051da177e4SLinus Torvalds } 11061da177e4SLinus Torvalds } 11071da177e4SLinus Torvalds 11081da177e4SLinus Torvalds /* 11091da177e4SLinus Torvalds * The relationship between dirty buffers and dirty pages: 11101da177e4SLinus Torvalds * 11111da177e4SLinus Torvalds * Whenever a page has any dirty buffers, the page's dirty bit is set, and 11121da177e4SLinus Torvalds * the page is tagged dirty in its radix tree. 11131da177e4SLinus Torvalds * 11141da177e4SLinus Torvalds * At all times, the dirtiness of the buffers represents the dirtiness of 11151da177e4SLinus Torvalds * subsections of the page. If the page has buffers, the page dirty bit is 11161da177e4SLinus Torvalds * merely a hint about the true dirty state. 11171da177e4SLinus Torvalds * 11181da177e4SLinus Torvalds * When a page is set dirty in its entirety, all its buffers are marked dirty 11191da177e4SLinus Torvalds * (if the page has buffers). 11201da177e4SLinus Torvalds * 11211da177e4SLinus Torvalds * When a buffer is marked dirty, its page is dirtied, but the page's other 11221da177e4SLinus Torvalds * buffers are not. 11231da177e4SLinus Torvalds * 11241da177e4SLinus Torvalds * Also. When blockdev buffers are explicitly read with bread(), they 11251da177e4SLinus Torvalds * individually become uptodate. But their backing page remains not 11261da177e4SLinus Torvalds * uptodate - even if all of its buffers are uptodate. A subsequent 11271da177e4SLinus Torvalds * block_read_full_page() against that page will discover all the uptodate 11281da177e4SLinus Torvalds * buffers, will set the page uptodate and will perform no I/O. 11291da177e4SLinus Torvalds */ 11301da177e4SLinus Torvalds 11311da177e4SLinus Torvalds /** 11321da177e4SLinus Torvalds * mark_buffer_dirty - mark a buffer_head as needing writeout 113367be2dd1SMartin Waitz * @bh: the buffer_head to mark dirty 11341da177e4SLinus Torvalds * 11351da177e4SLinus Torvalds * mark_buffer_dirty() will set the dirty bit against the buffer, then set its 11361da177e4SLinus Torvalds * backing page dirty, then tag the page as dirty in its address_space's radix 11371da177e4SLinus Torvalds * tree and then attach the address_space's inode to its superblock's dirty 11381da177e4SLinus Torvalds * inode list. 11391da177e4SLinus Torvalds * 11401da177e4SLinus Torvalds * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, 11411da177e4SLinus Torvalds * mapping->tree_lock and the global inode_lock. 11421da177e4SLinus Torvalds */ 11431da177e4SLinus Torvalds void fastcall mark_buffer_dirty(struct buffer_head *bh) 11441da177e4SLinus Torvalds { 11451da177e4SLinus Torvalds if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh)) 11461da177e4SLinus Torvalds __set_page_dirty_nobuffers(bh->b_page); 11471da177e4SLinus Torvalds } 11481da177e4SLinus Torvalds 11491da177e4SLinus Torvalds /* 11501da177e4SLinus Torvalds * Decrement a buffer_head's reference count. If all buffers against a page 11511da177e4SLinus Torvalds * have zero reference count, are clean and unlocked, and if the page is clean 11521da177e4SLinus Torvalds * and unlocked then try_to_free_buffers() may strip the buffers from the page 11531da177e4SLinus Torvalds * in preparation for freeing it (sometimes, rarely, buffers are removed from 11541da177e4SLinus Torvalds * a page but it ends up not being freed, and buffers may later be reattached). 11551da177e4SLinus Torvalds */ 11561da177e4SLinus Torvalds void __brelse(struct buffer_head * buf) 11571da177e4SLinus Torvalds { 11581da177e4SLinus Torvalds if (atomic_read(&buf->b_count)) { 11591da177e4SLinus Torvalds put_bh(buf); 11601da177e4SLinus Torvalds return; 11611da177e4SLinus Torvalds } 11621da177e4SLinus Torvalds printk(KERN_ERR "VFS: brelse: Trying to free free buffer\n"); 11631da177e4SLinus Torvalds WARN_ON(1); 11641da177e4SLinus Torvalds } 11651da177e4SLinus Torvalds 11661da177e4SLinus Torvalds /* 11671da177e4SLinus Torvalds * bforget() is like brelse(), except it discards any 11681da177e4SLinus Torvalds * potentially dirty data. 11691da177e4SLinus Torvalds */ 11701da177e4SLinus Torvalds void __bforget(struct buffer_head *bh) 11711da177e4SLinus Torvalds { 11721da177e4SLinus Torvalds clear_buffer_dirty(bh); 11731da177e4SLinus Torvalds if (!list_empty(&bh->b_assoc_buffers)) { 11741da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 11751da177e4SLinus Torvalds 11761da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 11771da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 117858ff407bSJan Kara bh->b_assoc_map = NULL; 11791da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 11801da177e4SLinus Torvalds } 11811da177e4SLinus Torvalds __brelse(bh); 11821da177e4SLinus Torvalds } 11831da177e4SLinus Torvalds 11841da177e4SLinus Torvalds static struct buffer_head *__bread_slow(struct buffer_head *bh) 11851da177e4SLinus Torvalds { 11861da177e4SLinus Torvalds lock_buffer(bh); 11871da177e4SLinus Torvalds if (buffer_uptodate(bh)) { 11881da177e4SLinus Torvalds unlock_buffer(bh); 11891da177e4SLinus Torvalds return bh; 11901da177e4SLinus Torvalds } else { 11911da177e4SLinus Torvalds get_bh(bh); 11921da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_sync; 11931da177e4SLinus Torvalds submit_bh(READ, bh); 11941da177e4SLinus Torvalds wait_on_buffer(bh); 11951da177e4SLinus Torvalds if (buffer_uptodate(bh)) 11961da177e4SLinus Torvalds return bh; 11971da177e4SLinus Torvalds } 11981da177e4SLinus Torvalds brelse(bh); 11991da177e4SLinus Torvalds return NULL; 12001da177e4SLinus Torvalds } 12011da177e4SLinus Torvalds 12021da177e4SLinus Torvalds /* 12031da177e4SLinus Torvalds * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). 12041da177e4SLinus Torvalds * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their 12051da177e4SLinus Torvalds * refcount elevated by one when they're in an LRU. A buffer can only appear 12061da177e4SLinus Torvalds * once in a particular CPU's LRU. A single buffer can be present in multiple 12071da177e4SLinus Torvalds * CPU's LRUs at the same time. 12081da177e4SLinus Torvalds * 12091da177e4SLinus Torvalds * This is a transparent caching front-end to sb_bread(), sb_getblk() and 12101da177e4SLinus Torvalds * sb_find_get_block(). 12111da177e4SLinus Torvalds * 12121da177e4SLinus Torvalds * The LRUs themselves only need locking against invalidate_bh_lrus. We use 12131da177e4SLinus Torvalds * a local interrupt disable for that. 12141da177e4SLinus Torvalds */ 12151da177e4SLinus Torvalds 12161da177e4SLinus Torvalds #define BH_LRU_SIZE 8 12171da177e4SLinus Torvalds 12181da177e4SLinus Torvalds struct bh_lru { 12191da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12201da177e4SLinus Torvalds }; 12211da177e4SLinus Torvalds 12221da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; 12231da177e4SLinus Torvalds 12241da177e4SLinus Torvalds #ifdef CONFIG_SMP 12251da177e4SLinus Torvalds #define bh_lru_lock() local_irq_disable() 12261da177e4SLinus Torvalds #define bh_lru_unlock() local_irq_enable() 12271da177e4SLinus Torvalds #else 12281da177e4SLinus Torvalds #define bh_lru_lock() preempt_disable() 12291da177e4SLinus Torvalds #define bh_lru_unlock() preempt_enable() 12301da177e4SLinus Torvalds #endif 12311da177e4SLinus Torvalds 12321da177e4SLinus Torvalds static inline void check_irqs_on(void) 12331da177e4SLinus Torvalds { 12341da177e4SLinus Torvalds #ifdef irqs_disabled 12351da177e4SLinus Torvalds BUG_ON(irqs_disabled()); 12361da177e4SLinus Torvalds #endif 12371da177e4SLinus Torvalds } 12381da177e4SLinus Torvalds 12391da177e4SLinus Torvalds /* 12401da177e4SLinus Torvalds * The LRU management algorithm is dopey-but-simple. Sorry. 12411da177e4SLinus Torvalds */ 12421da177e4SLinus Torvalds static void bh_lru_install(struct buffer_head *bh) 12431da177e4SLinus Torvalds { 12441da177e4SLinus Torvalds struct buffer_head *evictee = NULL; 12451da177e4SLinus Torvalds struct bh_lru *lru; 12461da177e4SLinus Torvalds 12471da177e4SLinus Torvalds check_irqs_on(); 12481da177e4SLinus Torvalds bh_lru_lock(); 12491da177e4SLinus Torvalds lru = &__get_cpu_var(bh_lrus); 12501da177e4SLinus Torvalds if (lru->bhs[0] != bh) { 12511da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 12521da177e4SLinus Torvalds int in; 12531da177e4SLinus Torvalds int out = 0; 12541da177e4SLinus Torvalds 12551da177e4SLinus Torvalds get_bh(bh); 12561da177e4SLinus Torvalds bhs[out++] = bh; 12571da177e4SLinus Torvalds for (in = 0; in < BH_LRU_SIZE; in++) { 12581da177e4SLinus Torvalds struct buffer_head *bh2 = lru->bhs[in]; 12591da177e4SLinus Torvalds 12601da177e4SLinus Torvalds if (bh2 == bh) { 12611da177e4SLinus Torvalds __brelse(bh2); 12621da177e4SLinus Torvalds } else { 12631da177e4SLinus Torvalds if (out >= BH_LRU_SIZE) { 12641da177e4SLinus Torvalds BUG_ON(evictee != NULL); 12651da177e4SLinus Torvalds evictee = bh2; 12661da177e4SLinus Torvalds } else { 12671da177e4SLinus Torvalds bhs[out++] = bh2; 12681da177e4SLinus Torvalds } 12691da177e4SLinus Torvalds } 12701da177e4SLinus Torvalds } 12711da177e4SLinus Torvalds while (out < BH_LRU_SIZE) 12721da177e4SLinus Torvalds bhs[out++] = NULL; 12731da177e4SLinus Torvalds memcpy(lru->bhs, bhs, sizeof(bhs)); 12741da177e4SLinus Torvalds } 12751da177e4SLinus Torvalds bh_lru_unlock(); 12761da177e4SLinus Torvalds 12771da177e4SLinus Torvalds if (evictee) 12781da177e4SLinus Torvalds __brelse(evictee); 12791da177e4SLinus Torvalds } 12801da177e4SLinus Torvalds 12811da177e4SLinus Torvalds /* 12821da177e4SLinus Torvalds * Look up the bh in this cpu's LRU. If it's there, move it to the head. 12831da177e4SLinus Torvalds */ 1284858119e1SArjan van de Ven static struct buffer_head * 12851da177e4SLinus Torvalds lookup_bh_lru(struct block_device *bdev, sector_t block, int size) 12861da177e4SLinus Torvalds { 12871da177e4SLinus Torvalds struct buffer_head *ret = NULL; 12881da177e4SLinus Torvalds struct bh_lru *lru; 12891da177e4SLinus Torvalds int i; 12901da177e4SLinus Torvalds 12911da177e4SLinus Torvalds check_irqs_on(); 12921da177e4SLinus Torvalds bh_lru_lock(); 12931da177e4SLinus Torvalds lru = &__get_cpu_var(bh_lrus); 12941da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 12951da177e4SLinus Torvalds struct buffer_head *bh = lru->bhs[i]; 12961da177e4SLinus Torvalds 12971da177e4SLinus Torvalds if (bh && bh->b_bdev == bdev && 12981da177e4SLinus Torvalds bh->b_blocknr == block && bh->b_size == size) { 12991da177e4SLinus Torvalds if (i) { 13001da177e4SLinus Torvalds while (i) { 13011da177e4SLinus Torvalds lru->bhs[i] = lru->bhs[i - 1]; 13021da177e4SLinus Torvalds i--; 13031da177e4SLinus Torvalds } 13041da177e4SLinus Torvalds lru->bhs[0] = bh; 13051da177e4SLinus Torvalds } 13061da177e4SLinus Torvalds get_bh(bh); 13071da177e4SLinus Torvalds ret = bh; 13081da177e4SLinus Torvalds break; 13091da177e4SLinus Torvalds } 13101da177e4SLinus Torvalds } 13111da177e4SLinus Torvalds bh_lru_unlock(); 13121da177e4SLinus Torvalds return ret; 13131da177e4SLinus Torvalds } 13141da177e4SLinus Torvalds 13151da177e4SLinus Torvalds /* 13161da177e4SLinus Torvalds * Perform a pagecache lookup for the matching buffer. If it's there, refresh 13171da177e4SLinus Torvalds * it in the LRU and mark it as accessed. If it is not present then return 13181da177e4SLinus Torvalds * NULL 13191da177e4SLinus Torvalds */ 13201da177e4SLinus Torvalds struct buffer_head * 13211da177e4SLinus Torvalds __find_get_block(struct block_device *bdev, sector_t block, int size) 13221da177e4SLinus Torvalds { 13231da177e4SLinus Torvalds struct buffer_head *bh = lookup_bh_lru(bdev, block, size); 13241da177e4SLinus Torvalds 13251da177e4SLinus Torvalds if (bh == NULL) { 1326385fd4c5SCoywolf Qi Hunt bh = __find_get_block_slow(bdev, block); 13271da177e4SLinus Torvalds if (bh) 13281da177e4SLinus Torvalds bh_lru_install(bh); 13291da177e4SLinus Torvalds } 13301da177e4SLinus Torvalds if (bh) 13311da177e4SLinus Torvalds touch_buffer(bh); 13321da177e4SLinus Torvalds return bh; 13331da177e4SLinus Torvalds } 13341da177e4SLinus Torvalds EXPORT_SYMBOL(__find_get_block); 13351da177e4SLinus Torvalds 13361da177e4SLinus Torvalds /* 13371da177e4SLinus Torvalds * __getblk will locate (and, if necessary, create) the buffer_head 13381da177e4SLinus Torvalds * which corresponds to the passed block_device, block and size. The 13391da177e4SLinus Torvalds * returned buffer has its reference count incremented. 13401da177e4SLinus Torvalds * 13411da177e4SLinus Torvalds * __getblk() cannot fail - it just keeps trying. If you pass it an 13421da177e4SLinus Torvalds * illegal block number, __getblk() will happily return a buffer_head 13431da177e4SLinus Torvalds * which represents the non-existent block. Very weird. 13441da177e4SLinus Torvalds * 13451da177e4SLinus Torvalds * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() 13461da177e4SLinus Torvalds * attempt is failing. FIXME, perhaps? 13471da177e4SLinus Torvalds */ 13481da177e4SLinus Torvalds struct buffer_head * 13491da177e4SLinus Torvalds __getblk(struct block_device *bdev, sector_t block, int size) 13501da177e4SLinus Torvalds { 13511da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, block, size); 13521da177e4SLinus Torvalds 13531da177e4SLinus Torvalds might_sleep(); 13541da177e4SLinus Torvalds if (bh == NULL) 13551da177e4SLinus Torvalds bh = __getblk_slow(bdev, block, size); 13561da177e4SLinus Torvalds return bh; 13571da177e4SLinus Torvalds } 13581da177e4SLinus Torvalds EXPORT_SYMBOL(__getblk); 13591da177e4SLinus Torvalds 13601da177e4SLinus Torvalds /* 13611da177e4SLinus Torvalds * Do async read-ahead on a buffer.. 13621da177e4SLinus Torvalds */ 13631da177e4SLinus Torvalds void __breadahead(struct block_device *bdev, sector_t block, int size) 13641da177e4SLinus Torvalds { 13651da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 1366a3e713b5SAndrew Morton if (likely(bh)) { 13671da177e4SLinus Torvalds ll_rw_block(READA, 1, &bh); 13681da177e4SLinus Torvalds brelse(bh); 13691da177e4SLinus Torvalds } 1370a3e713b5SAndrew Morton } 13711da177e4SLinus Torvalds EXPORT_SYMBOL(__breadahead); 13721da177e4SLinus Torvalds 13731da177e4SLinus Torvalds /** 13741da177e4SLinus Torvalds * __bread() - reads a specified block and returns the bh 137567be2dd1SMartin Waitz * @bdev: the block_device to read from 13761da177e4SLinus Torvalds * @block: number of block 13771da177e4SLinus Torvalds * @size: size (in bytes) to read 13781da177e4SLinus Torvalds * 13791da177e4SLinus Torvalds * Reads a specified block, and returns buffer head that contains it. 13801da177e4SLinus Torvalds * It returns NULL if the block was unreadable. 13811da177e4SLinus Torvalds */ 13821da177e4SLinus Torvalds struct buffer_head * 13831da177e4SLinus Torvalds __bread(struct block_device *bdev, sector_t block, int size) 13841da177e4SLinus Torvalds { 13851da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 13861da177e4SLinus Torvalds 1387a3e713b5SAndrew Morton if (likely(bh) && !buffer_uptodate(bh)) 13881da177e4SLinus Torvalds bh = __bread_slow(bh); 13891da177e4SLinus Torvalds return bh; 13901da177e4SLinus Torvalds } 13911da177e4SLinus Torvalds EXPORT_SYMBOL(__bread); 13921da177e4SLinus Torvalds 13931da177e4SLinus Torvalds /* 13941da177e4SLinus Torvalds * invalidate_bh_lrus() is called rarely - but not only at unmount. 13951da177e4SLinus Torvalds * This doesn't race because it runs in each cpu either in irq 13961da177e4SLinus Torvalds * or with preempt disabled. 13971da177e4SLinus Torvalds */ 13981da177e4SLinus Torvalds static void invalidate_bh_lru(void *arg) 13991da177e4SLinus Torvalds { 14001da177e4SLinus Torvalds struct bh_lru *b = &get_cpu_var(bh_lrus); 14011da177e4SLinus Torvalds int i; 14021da177e4SLinus Torvalds 14031da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 14041da177e4SLinus Torvalds brelse(b->bhs[i]); 14051da177e4SLinus Torvalds b->bhs[i] = NULL; 14061da177e4SLinus Torvalds } 14071da177e4SLinus Torvalds put_cpu_var(bh_lrus); 14081da177e4SLinus Torvalds } 14091da177e4SLinus Torvalds 14101da177e4SLinus Torvalds static void invalidate_bh_lrus(void) 14111da177e4SLinus Torvalds { 14121da177e4SLinus Torvalds on_each_cpu(invalidate_bh_lru, NULL, 1, 1); 14131da177e4SLinus Torvalds } 14141da177e4SLinus Torvalds 14151da177e4SLinus Torvalds void set_bh_page(struct buffer_head *bh, 14161da177e4SLinus Torvalds struct page *page, unsigned long offset) 14171da177e4SLinus Torvalds { 14181da177e4SLinus Torvalds bh->b_page = page; 1419e827f923SEric Sesterhenn BUG_ON(offset >= PAGE_SIZE); 14201da177e4SLinus Torvalds if (PageHighMem(page)) 14211da177e4SLinus Torvalds /* 14221da177e4SLinus Torvalds * This catches illegal uses and preserves the offset: 14231da177e4SLinus Torvalds */ 14241da177e4SLinus Torvalds bh->b_data = (char *)(0 + offset); 14251da177e4SLinus Torvalds else 14261da177e4SLinus Torvalds bh->b_data = page_address(page) + offset; 14271da177e4SLinus Torvalds } 14281da177e4SLinus Torvalds EXPORT_SYMBOL(set_bh_page); 14291da177e4SLinus Torvalds 14301da177e4SLinus Torvalds /* 14311da177e4SLinus Torvalds * Called when truncating a buffer on a page completely. 14321da177e4SLinus Torvalds */ 1433858119e1SArjan van de Ven static void discard_buffer(struct buffer_head * bh) 14341da177e4SLinus Torvalds { 14351da177e4SLinus Torvalds lock_buffer(bh); 14361da177e4SLinus Torvalds clear_buffer_dirty(bh); 14371da177e4SLinus Torvalds bh->b_bdev = NULL; 14381da177e4SLinus Torvalds clear_buffer_mapped(bh); 14391da177e4SLinus Torvalds clear_buffer_req(bh); 14401da177e4SLinus Torvalds clear_buffer_new(bh); 14411da177e4SLinus Torvalds clear_buffer_delay(bh); 14421da177e4SLinus Torvalds unlock_buffer(bh); 14431da177e4SLinus Torvalds } 14441da177e4SLinus Torvalds 14451da177e4SLinus Torvalds /** 14461da177e4SLinus Torvalds * block_invalidatepage - invalidate part of all of a buffer-backed page 14471da177e4SLinus Torvalds * 14481da177e4SLinus Torvalds * @page: the page which is affected 14491da177e4SLinus Torvalds * @offset: the index of the truncation point 14501da177e4SLinus Torvalds * 14511da177e4SLinus Torvalds * block_invalidatepage() is called when all or part of the page has become 14521da177e4SLinus Torvalds * invalidatedby a truncate operation. 14531da177e4SLinus Torvalds * 14541da177e4SLinus Torvalds * block_invalidatepage() does not have to release all buffers, but it must 14551da177e4SLinus Torvalds * ensure that no dirty buffer is left outside @offset and that no I/O 14561da177e4SLinus Torvalds * is underway against any of the blocks which are outside the truncation 14571da177e4SLinus Torvalds * point. Because the caller is about to free (and possibly reuse) those 14581da177e4SLinus Torvalds * blocks on-disk. 14591da177e4SLinus Torvalds */ 14602ff28e22SNeilBrown void block_invalidatepage(struct page *page, unsigned long offset) 14611da177e4SLinus Torvalds { 14621da177e4SLinus Torvalds struct buffer_head *head, *bh, *next; 14631da177e4SLinus Torvalds unsigned int curr_off = 0; 14641da177e4SLinus Torvalds 14651da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 14661da177e4SLinus Torvalds if (!page_has_buffers(page)) 14671da177e4SLinus Torvalds goto out; 14681da177e4SLinus Torvalds 14691da177e4SLinus Torvalds head = page_buffers(page); 14701da177e4SLinus Torvalds bh = head; 14711da177e4SLinus Torvalds do { 14721da177e4SLinus Torvalds unsigned int next_off = curr_off + bh->b_size; 14731da177e4SLinus Torvalds next = bh->b_this_page; 14741da177e4SLinus Torvalds 14751da177e4SLinus Torvalds /* 14761da177e4SLinus Torvalds * is this block fully invalidated? 14771da177e4SLinus Torvalds */ 14781da177e4SLinus Torvalds if (offset <= curr_off) 14791da177e4SLinus Torvalds discard_buffer(bh); 14801da177e4SLinus Torvalds curr_off = next_off; 14811da177e4SLinus Torvalds bh = next; 14821da177e4SLinus Torvalds } while (bh != head); 14831da177e4SLinus Torvalds 14841da177e4SLinus Torvalds /* 14851da177e4SLinus Torvalds * We release buffers only if the entire page is being invalidated. 14861da177e4SLinus Torvalds * The get_block cached value has been unconditionally invalidated, 14871da177e4SLinus Torvalds * so real IO is not possible anymore. 14881da177e4SLinus Torvalds */ 14891da177e4SLinus Torvalds if (offset == 0) 14902ff28e22SNeilBrown try_to_release_page(page, 0); 14911da177e4SLinus Torvalds out: 14922ff28e22SNeilBrown return; 14931da177e4SLinus Torvalds } 14941da177e4SLinus Torvalds EXPORT_SYMBOL(block_invalidatepage); 14951da177e4SLinus Torvalds 14961da177e4SLinus Torvalds /* 14971da177e4SLinus Torvalds * We attach and possibly dirty the buffers atomically wrt 14981da177e4SLinus Torvalds * __set_page_dirty_buffers() via private_lock. try_to_free_buffers 14991da177e4SLinus Torvalds * is already excluded via the page lock. 15001da177e4SLinus Torvalds */ 15011da177e4SLinus Torvalds void create_empty_buffers(struct page *page, 15021da177e4SLinus Torvalds unsigned long blocksize, unsigned long b_state) 15031da177e4SLinus Torvalds { 15041da177e4SLinus Torvalds struct buffer_head *bh, *head, *tail; 15051da177e4SLinus Torvalds 15061da177e4SLinus Torvalds head = alloc_page_buffers(page, blocksize, 1); 15071da177e4SLinus Torvalds bh = head; 15081da177e4SLinus Torvalds do { 15091da177e4SLinus Torvalds bh->b_state |= b_state; 15101da177e4SLinus Torvalds tail = bh; 15111da177e4SLinus Torvalds bh = bh->b_this_page; 15121da177e4SLinus Torvalds } while (bh); 15131da177e4SLinus Torvalds tail->b_this_page = head; 15141da177e4SLinus Torvalds 15151da177e4SLinus Torvalds spin_lock(&page->mapping->private_lock); 15161da177e4SLinus Torvalds if (PageUptodate(page) || PageDirty(page)) { 15171da177e4SLinus Torvalds bh = head; 15181da177e4SLinus Torvalds do { 15191da177e4SLinus Torvalds if (PageDirty(page)) 15201da177e4SLinus Torvalds set_buffer_dirty(bh); 15211da177e4SLinus Torvalds if (PageUptodate(page)) 15221da177e4SLinus Torvalds set_buffer_uptodate(bh); 15231da177e4SLinus Torvalds bh = bh->b_this_page; 15241da177e4SLinus Torvalds } while (bh != head); 15251da177e4SLinus Torvalds } 15261da177e4SLinus Torvalds attach_page_buffers(page, head); 15271da177e4SLinus Torvalds spin_unlock(&page->mapping->private_lock); 15281da177e4SLinus Torvalds } 15291da177e4SLinus Torvalds EXPORT_SYMBOL(create_empty_buffers); 15301da177e4SLinus Torvalds 15311da177e4SLinus Torvalds /* 15321da177e4SLinus Torvalds * We are taking a block for data and we don't want any output from any 15331da177e4SLinus Torvalds * buffer-cache aliases starting from return from that function and 15341da177e4SLinus Torvalds * until the moment when something will explicitly mark the buffer 15351da177e4SLinus Torvalds * dirty (hopefully that will not happen until we will free that block ;-) 15361da177e4SLinus Torvalds * We don't even need to mark it not-uptodate - nobody can expect 15371da177e4SLinus Torvalds * anything from a newly allocated buffer anyway. We used to used 15381da177e4SLinus Torvalds * unmap_buffer() for such invalidation, but that was wrong. We definitely 15391da177e4SLinus Torvalds * don't want to mark the alias unmapped, for example - it would confuse 15401da177e4SLinus Torvalds * anyone who might pick it with bread() afterwards... 15411da177e4SLinus Torvalds * 15421da177e4SLinus Torvalds * Also.. Note that bforget() doesn't lock the buffer. So there can 15431da177e4SLinus Torvalds * be writeout I/O going on against recently-freed buffers. We don't 15441da177e4SLinus Torvalds * wait on that I/O in bforget() - it's more efficient to wait on the I/O 15451da177e4SLinus Torvalds * only if we really need to. That happens here. 15461da177e4SLinus Torvalds */ 15471da177e4SLinus Torvalds void unmap_underlying_metadata(struct block_device *bdev, sector_t block) 15481da177e4SLinus Torvalds { 15491da177e4SLinus Torvalds struct buffer_head *old_bh; 15501da177e4SLinus Torvalds 15511da177e4SLinus Torvalds might_sleep(); 15521da177e4SLinus Torvalds 1553385fd4c5SCoywolf Qi Hunt old_bh = __find_get_block_slow(bdev, block); 15541da177e4SLinus Torvalds if (old_bh) { 15551da177e4SLinus Torvalds clear_buffer_dirty(old_bh); 15561da177e4SLinus Torvalds wait_on_buffer(old_bh); 15571da177e4SLinus Torvalds clear_buffer_req(old_bh); 15581da177e4SLinus Torvalds __brelse(old_bh); 15591da177e4SLinus Torvalds } 15601da177e4SLinus Torvalds } 15611da177e4SLinus Torvalds EXPORT_SYMBOL(unmap_underlying_metadata); 15621da177e4SLinus Torvalds 15631da177e4SLinus Torvalds /* 15641da177e4SLinus Torvalds * NOTE! All mapped/uptodate combinations are valid: 15651da177e4SLinus Torvalds * 15661da177e4SLinus Torvalds * Mapped Uptodate Meaning 15671da177e4SLinus Torvalds * 15681da177e4SLinus Torvalds * No No "unknown" - must do get_block() 15691da177e4SLinus Torvalds * No Yes "hole" - zero-filled 15701da177e4SLinus Torvalds * Yes No "allocated" - allocated on disk, not read in 15711da177e4SLinus Torvalds * Yes Yes "valid" - allocated and up-to-date in memory. 15721da177e4SLinus Torvalds * 15731da177e4SLinus Torvalds * "Dirty" is valid only with the last case (mapped+uptodate). 15741da177e4SLinus Torvalds */ 15751da177e4SLinus Torvalds 15761da177e4SLinus Torvalds /* 15771da177e4SLinus Torvalds * While block_write_full_page is writing back the dirty buffers under 15781da177e4SLinus Torvalds * the page lock, whoever dirtied the buffers may decide to clean them 15791da177e4SLinus Torvalds * again at any time. We handle that by only looking at the buffer 15801da177e4SLinus Torvalds * state inside lock_buffer(). 15811da177e4SLinus Torvalds * 15821da177e4SLinus Torvalds * If block_write_full_page() is called for regular writeback 15831da177e4SLinus Torvalds * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a 15841da177e4SLinus Torvalds * locked buffer. This only can happen if someone has written the buffer 15851da177e4SLinus Torvalds * directly, with submit_bh(). At the address_space level PageWriteback 15861da177e4SLinus Torvalds * prevents this contention from occurring. 15871da177e4SLinus Torvalds */ 15881da177e4SLinus Torvalds static int __block_write_full_page(struct inode *inode, struct page *page, 15891da177e4SLinus Torvalds get_block_t *get_block, struct writeback_control *wbc) 15901da177e4SLinus Torvalds { 15911da177e4SLinus Torvalds int err; 15921da177e4SLinus Torvalds sector_t block; 15931da177e4SLinus Torvalds sector_t last_block; 1594f0fbd5fcSAndrew Morton struct buffer_head *bh, *head; 1595b0cf2321SBadari Pulavarty const unsigned blocksize = 1 << inode->i_blkbits; 15961da177e4SLinus Torvalds int nr_underway = 0; 15971da177e4SLinus Torvalds 15981da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 15991da177e4SLinus Torvalds 16001da177e4SLinus Torvalds last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; 16011da177e4SLinus Torvalds 16021da177e4SLinus Torvalds if (!page_has_buffers(page)) { 1603b0cf2321SBadari Pulavarty create_empty_buffers(page, blocksize, 16041da177e4SLinus Torvalds (1 << BH_Dirty)|(1 << BH_Uptodate)); 16051da177e4SLinus Torvalds } 16061da177e4SLinus Torvalds 16071da177e4SLinus Torvalds /* 16081da177e4SLinus Torvalds * Be very careful. We have no exclusion from __set_page_dirty_buffers 16091da177e4SLinus Torvalds * here, and the (potentially unmapped) buffers may become dirty at 16101da177e4SLinus Torvalds * any time. If a buffer becomes dirty here after we've inspected it 16111da177e4SLinus Torvalds * then we just miss that fact, and the page stays dirty. 16121da177e4SLinus Torvalds * 16131da177e4SLinus Torvalds * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; 16141da177e4SLinus Torvalds * handle that here by just cleaning them. 16151da177e4SLinus Torvalds */ 16161da177e4SLinus Torvalds 161754b21a79SAndrew Morton block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 16181da177e4SLinus Torvalds head = page_buffers(page); 16191da177e4SLinus Torvalds bh = head; 16201da177e4SLinus Torvalds 16211da177e4SLinus Torvalds /* 16221da177e4SLinus Torvalds * Get all the dirty buffers mapped to disk addresses and 16231da177e4SLinus Torvalds * handle any aliases from the underlying blockdev's mapping. 16241da177e4SLinus Torvalds */ 16251da177e4SLinus Torvalds do { 16261da177e4SLinus Torvalds if (block > last_block) { 16271da177e4SLinus Torvalds /* 16281da177e4SLinus Torvalds * mapped buffers outside i_size will occur, because 16291da177e4SLinus Torvalds * this page can be outside i_size when there is a 16301da177e4SLinus Torvalds * truncate in progress. 16311da177e4SLinus Torvalds */ 16321da177e4SLinus Torvalds /* 16331da177e4SLinus Torvalds * The buffer was zeroed by block_write_full_page() 16341da177e4SLinus Torvalds */ 16351da177e4SLinus Torvalds clear_buffer_dirty(bh); 16361da177e4SLinus Torvalds set_buffer_uptodate(bh); 16371da177e4SLinus Torvalds } else if (!buffer_mapped(bh) && buffer_dirty(bh)) { 1638b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 16391da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 16401da177e4SLinus Torvalds if (err) 16411da177e4SLinus Torvalds goto recover; 16421da177e4SLinus Torvalds if (buffer_new(bh)) { 16431da177e4SLinus Torvalds /* blockdev mappings never come here */ 16441da177e4SLinus Torvalds clear_buffer_new(bh); 16451da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 16461da177e4SLinus Torvalds bh->b_blocknr); 16471da177e4SLinus Torvalds } 16481da177e4SLinus Torvalds } 16491da177e4SLinus Torvalds bh = bh->b_this_page; 16501da177e4SLinus Torvalds block++; 16511da177e4SLinus Torvalds } while (bh != head); 16521da177e4SLinus Torvalds 16531da177e4SLinus Torvalds do { 16541da177e4SLinus Torvalds if (!buffer_mapped(bh)) 16551da177e4SLinus Torvalds continue; 16561da177e4SLinus Torvalds /* 16571da177e4SLinus Torvalds * If it's a fully non-blocking write attempt and we cannot 16581da177e4SLinus Torvalds * lock the buffer then redirty the page. Note that this can 16591da177e4SLinus Torvalds * potentially cause a busy-wait loop from pdflush and kswapd 16601da177e4SLinus Torvalds * activity, but those code paths have their own higher-level 16611da177e4SLinus Torvalds * throttling. 16621da177e4SLinus Torvalds */ 16631da177e4SLinus Torvalds if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { 16641da177e4SLinus Torvalds lock_buffer(bh); 16651da177e4SLinus Torvalds } else if (test_set_buffer_locked(bh)) { 16661da177e4SLinus Torvalds redirty_page_for_writepage(wbc, page); 16671da177e4SLinus Torvalds continue; 16681da177e4SLinus Torvalds } 16691da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 16701da177e4SLinus Torvalds mark_buffer_async_write(bh); 16711da177e4SLinus Torvalds } else { 16721da177e4SLinus Torvalds unlock_buffer(bh); 16731da177e4SLinus Torvalds } 16741da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 16751da177e4SLinus Torvalds 16761da177e4SLinus Torvalds /* 16771da177e4SLinus Torvalds * The page and its buffers are protected by PageWriteback(), so we can 16781da177e4SLinus Torvalds * drop the bh refcounts early. 16791da177e4SLinus Torvalds */ 16801da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 16811da177e4SLinus Torvalds set_page_writeback(page); 16821da177e4SLinus Torvalds 16831da177e4SLinus Torvalds do { 16841da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 16851da177e4SLinus Torvalds if (buffer_async_write(bh)) { 16861da177e4SLinus Torvalds submit_bh(WRITE, bh); 16871da177e4SLinus Torvalds nr_underway++; 1688ad576e63SNick Piggin } 16891da177e4SLinus Torvalds bh = next; 16901da177e4SLinus Torvalds } while (bh != head); 169105937baaSAndrew Morton unlock_page(page); 16921da177e4SLinus Torvalds 16931da177e4SLinus Torvalds err = 0; 16941da177e4SLinus Torvalds done: 16951da177e4SLinus Torvalds if (nr_underway == 0) { 16961da177e4SLinus Torvalds /* 16971da177e4SLinus Torvalds * The page was marked dirty, but the buffers were 16981da177e4SLinus Torvalds * clean. Someone wrote them back by hand with 16991da177e4SLinus Torvalds * ll_rw_block/submit_bh. A rare case. 17001da177e4SLinus Torvalds */ 17011da177e4SLinus Torvalds int uptodate = 1; 17021da177e4SLinus Torvalds do { 17031da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 17041da177e4SLinus Torvalds uptodate = 0; 17051da177e4SLinus Torvalds break; 17061da177e4SLinus Torvalds } 17071da177e4SLinus Torvalds bh = bh->b_this_page; 17081da177e4SLinus Torvalds } while (bh != head); 17091da177e4SLinus Torvalds if (uptodate) 17101da177e4SLinus Torvalds SetPageUptodate(page); 17111da177e4SLinus Torvalds end_page_writeback(page); 17121da177e4SLinus Torvalds /* 17131da177e4SLinus Torvalds * The page and buffer_heads can be released at any time from 17141da177e4SLinus Torvalds * here on. 17151da177e4SLinus Torvalds */ 17161da177e4SLinus Torvalds wbc->pages_skipped++; /* We didn't write this page */ 17171da177e4SLinus Torvalds } 17181da177e4SLinus Torvalds return err; 17191da177e4SLinus Torvalds 17201da177e4SLinus Torvalds recover: 17211da177e4SLinus Torvalds /* 17221da177e4SLinus Torvalds * ENOSPC, or some other error. We may already have added some 17231da177e4SLinus Torvalds * blocks to the file, so we need to write these out to avoid 17241da177e4SLinus Torvalds * exposing stale data. 17251da177e4SLinus Torvalds * The page is currently locked and not marked for writeback 17261da177e4SLinus Torvalds */ 17271da177e4SLinus Torvalds bh = head; 17281da177e4SLinus Torvalds /* Recovery: lock and submit the mapped buffers */ 17291da177e4SLinus Torvalds do { 17301da177e4SLinus Torvalds if (buffer_mapped(bh) && buffer_dirty(bh)) { 17311da177e4SLinus Torvalds lock_buffer(bh); 17321da177e4SLinus Torvalds mark_buffer_async_write(bh); 17331da177e4SLinus Torvalds } else { 17341da177e4SLinus Torvalds /* 17351da177e4SLinus Torvalds * The buffer may have been set dirty during 17361da177e4SLinus Torvalds * attachment to a dirty page. 17371da177e4SLinus Torvalds */ 17381da177e4SLinus Torvalds clear_buffer_dirty(bh); 17391da177e4SLinus Torvalds } 17401da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 17411da177e4SLinus Torvalds SetPageError(page); 17421da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 17431da177e4SLinus Torvalds set_page_writeback(page); 17441da177e4SLinus Torvalds unlock_page(page); 17451da177e4SLinus Torvalds do { 17461da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 17471da177e4SLinus Torvalds if (buffer_async_write(bh)) { 17481da177e4SLinus Torvalds clear_buffer_dirty(bh); 17491da177e4SLinus Torvalds submit_bh(WRITE, bh); 17501da177e4SLinus Torvalds nr_underway++; 1751ad576e63SNick Piggin } 17521da177e4SLinus Torvalds bh = next; 17531da177e4SLinus Torvalds } while (bh != head); 17541da177e4SLinus Torvalds goto done; 17551da177e4SLinus Torvalds } 17561da177e4SLinus Torvalds 17571da177e4SLinus Torvalds static int __block_prepare_write(struct inode *inode, struct page *page, 17581da177e4SLinus Torvalds unsigned from, unsigned to, get_block_t *get_block) 17591da177e4SLinus Torvalds { 17601da177e4SLinus Torvalds unsigned block_start, block_end; 17611da177e4SLinus Torvalds sector_t block; 17621da177e4SLinus Torvalds int err = 0; 17631da177e4SLinus Torvalds unsigned blocksize, bbits; 17641da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 17651da177e4SLinus Torvalds 17661da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 17671da177e4SLinus Torvalds BUG_ON(from > PAGE_CACHE_SIZE); 17681da177e4SLinus Torvalds BUG_ON(to > PAGE_CACHE_SIZE); 17691da177e4SLinus Torvalds BUG_ON(from > to); 17701da177e4SLinus Torvalds 17711da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 17721da177e4SLinus Torvalds if (!page_has_buffers(page)) 17731da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 17741da177e4SLinus Torvalds head = page_buffers(page); 17751da177e4SLinus Torvalds 17761da177e4SLinus Torvalds bbits = inode->i_blkbits; 17771da177e4SLinus Torvalds block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 17781da177e4SLinus Torvalds 17791da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 17801da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 17811da177e4SLinus Torvalds block_end = block_start + blocksize; 17821da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 17831da177e4SLinus Torvalds if (PageUptodate(page)) { 17841da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 17851da177e4SLinus Torvalds set_buffer_uptodate(bh); 17861da177e4SLinus Torvalds } 17871da177e4SLinus Torvalds continue; 17881da177e4SLinus Torvalds } 17891da177e4SLinus Torvalds if (buffer_new(bh)) 17901da177e4SLinus Torvalds clear_buffer_new(bh); 17911da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 1792b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 17931da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 17941da177e4SLinus Torvalds if (err) 1795f3ddbdc6SNick Piggin break; 17961da177e4SLinus Torvalds if (buffer_new(bh)) { 17971da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 17981da177e4SLinus Torvalds bh->b_blocknr); 17991da177e4SLinus Torvalds if (PageUptodate(page)) { 18001da177e4SLinus Torvalds set_buffer_uptodate(bh); 18011da177e4SLinus Torvalds continue; 18021da177e4SLinus Torvalds } 18031da177e4SLinus Torvalds if (block_end > to || block_start < from) { 18041da177e4SLinus Torvalds void *kaddr; 18051da177e4SLinus Torvalds 18061da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 18071da177e4SLinus Torvalds if (block_end > to) 18081da177e4SLinus Torvalds memset(kaddr+to, 0, 18091da177e4SLinus Torvalds block_end-to); 18101da177e4SLinus Torvalds if (block_start < from) 18111da177e4SLinus Torvalds memset(kaddr+block_start, 18121da177e4SLinus Torvalds 0, from-block_start); 18131da177e4SLinus Torvalds flush_dcache_page(page); 18141da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 18151da177e4SLinus Torvalds } 18161da177e4SLinus Torvalds continue; 18171da177e4SLinus Torvalds } 18181da177e4SLinus Torvalds } 18191da177e4SLinus Torvalds if (PageUptodate(page)) { 18201da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 18211da177e4SLinus Torvalds set_buffer_uptodate(bh); 18221da177e4SLinus Torvalds continue; 18231da177e4SLinus Torvalds } 18241da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 18251da177e4SLinus Torvalds (block_start < from || block_end > to)) { 18261da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 18271da177e4SLinus Torvalds *wait_bh++=bh; 18281da177e4SLinus Torvalds } 18291da177e4SLinus Torvalds } 18301da177e4SLinus Torvalds /* 18311da177e4SLinus Torvalds * If we issued read requests - let them complete. 18321da177e4SLinus Torvalds */ 18331da177e4SLinus Torvalds while(wait_bh > wait) { 18341da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 18351da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 1836f3ddbdc6SNick Piggin err = -EIO; 18371da177e4SLinus Torvalds } 1838152becd2SAnton Altaparmakov if (!err) { 1839152becd2SAnton Altaparmakov bh = head; 1840152becd2SAnton Altaparmakov do { 1841152becd2SAnton Altaparmakov if (buffer_new(bh)) 1842152becd2SAnton Altaparmakov clear_buffer_new(bh); 1843152becd2SAnton Altaparmakov } while ((bh = bh->b_this_page) != head); 1844152becd2SAnton Altaparmakov return 0; 1845152becd2SAnton Altaparmakov } 1846f3ddbdc6SNick Piggin /* Error case: */ 18471da177e4SLinus Torvalds /* 18481da177e4SLinus Torvalds * Zero out any newly allocated blocks to avoid exposing stale 18491da177e4SLinus Torvalds * data. If BH_New is set, we know that the block was newly 18501da177e4SLinus Torvalds * allocated in the above loop. 18511da177e4SLinus Torvalds */ 18521da177e4SLinus Torvalds bh = head; 18531da177e4SLinus Torvalds block_start = 0; 18541da177e4SLinus Torvalds do { 18551da177e4SLinus Torvalds block_end = block_start+blocksize; 18561da177e4SLinus Torvalds if (block_end <= from) 18571da177e4SLinus Torvalds goto next_bh; 18581da177e4SLinus Torvalds if (block_start >= to) 18591da177e4SLinus Torvalds break; 18601da177e4SLinus Torvalds if (buffer_new(bh)) { 18611da177e4SLinus Torvalds void *kaddr; 18621da177e4SLinus Torvalds 18631da177e4SLinus Torvalds clear_buffer_new(bh); 18641da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 18651da177e4SLinus Torvalds memset(kaddr+block_start, 0, bh->b_size); 18668c581651SMonakhov Dmitriy flush_dcache_page(page); 18671da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 18681da177e4SLinus Torvalds set_buffer_uptodate(bh); 18691da177e4SLinus Torvalds mark_buffer_dirty(bh); 18701da177e4SLinus Torvalds } 18711da177e4SLinus Torvalds next_bh: 18721da177e4SLinus Torvalds block_start = block_end; 18731da177e4SLinus Torvalds bh = bh->b_this_page; 18741da177e4SLinus Torvalds } while (bh != head); 18751da177e4SLinus Torvalds return err; 18761da177e4SLinus Torvalds } 18771da177e4SLinus Torvalds 18781da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 18791da177e4SLinus Torvalds unsigned from, unsigned to) 18801da177e4SLinus Torvalds { 18811da177e4SLinus Torvalds unsigned block_start, block_end; 18821da177e4SLinus Torvalds int partial = 0; 18831da177e4SLinus Torvalds unsigned blocksize; 18841da177e4SLinus Torvalds struct buffer_head *bh, *head; 18851da177e4SLinus Torvalds 18861da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 18871da177e4SLinus Torvalds 18881da177e4SLinus Torvalds for(bh = head = page_buffers(page), block_start = 0; 18891da177e4SLinus Torvalds bh != head || !block_start; 18901da177e4SLinus Torvalds block_start=block_end, bh = bh->b_this_page) { 18911da177e4SLinus Torvalds block_end = block_start + blocksize; 18921da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 18931da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 18941da177e4SLinus Torvalds partial = 1; 18951da177e4SLinus Torvalds } else { 18961da177e4SLinus Torvalds set_buffer_uptodate(bh); 18971da177e4SLinus Torvalds mark_buffer_dirty(bh); 18981da177e4SLinus Torvalds } 18991da177e4SLinus Torvalds } 19001da177e4SLinus Torvalds 19011da177e4SLinus Torvalds /* 19021da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 19031da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 19041da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 19051da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 19061da177e4SLinus Torvalds */ 19071da177e4SLinus Torvalds if (!partial) 19081da177e4SLinus Torvalds SetPageUptodate(page); 19091da177e4SLinus Torvalds return 0; 19101da177e4SLinus Torvalds } 19111da177e4SLinus Torvalds 19121da177e4SLinus Torvalds /* 19131da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 19141da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 19151da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 19161da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 19171da177e4SLinus Torvalds * page struct once IO has completed. 19181da177e4SLinus Torvalds */ 19191da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 19201da177e4SLinus Torvalds { 19211da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 19221da177e4SLinus Torvalds sector_t iblock, lblock; 19231da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 19241da177e4SLinus Torvalds unsigned int blocksize; 19251da177e4SLinus Torvalds int nr, i; 19261da177e4SLinus Torvalds int fully_mapped = 1; 19271da177e4SLinus Torvalds 1928cd7619d6SMatt Mackall BUG_ON(!PageLocked(page)); 19291da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 19301da177e4SLinus Torvalds if (!page_has_buffers(page)) 19311da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 19321da177e4SLinus Torvalds head = page_buffers(page); 19331da177e4SLinus Torvalds 19341da177e4SLinus Torvalds iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 19351da177e4SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; 19361da177e4SLinus Torvalds bh = head; 19371da177e4SLinus Torvalds nr = 0; 19381da177e4SLinus Torvalds i = 0; 19391da177e4SLinus Torvalds 19401da177e4SLinus Torvalds do { 19411da177e4SLinus Torvalds if (buffer_uptodate(bh)) 19421da177e4SLinus Torvalds continue; 19431da177e4SLinus Torvalds 19441da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 1945c64610baSAndrew Morton int err = 0; 1946c64610baSAndrew Morton 19471da177e4SLinus Torvalds fully_mapped = 0; 19481da177e4SLinus Torvalds if (iblock < lblock) { 1949b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 1950c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 1951c64610baSAndrew Morton if (err) 19521da177e4SLinus Torvalds SetPageError(page); 19531da177e4SLinus Torvalds } 19541da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 19551da177e4SLinus Torvalds void *kaddr = kmap_atomic(page, KM_USER0); 19561da177e4SLinus Torvalds memset(kaddr + i * blocksize, 0, blocksize); 19571da177e4SLinus Torvalds flush_dcache_page(page); 19581da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 1959c64610baSAndrew Morton if (!err) 19601da177e4SLinus Torvalds set_buffer_uptodate(bh); 19611da177e4SLinus Torvalds continue; 19621da177e4SLinus Torvalds } 19631da177e4SLinus Torvalds /* 19641da177e4SLinus Torvalds * get_block() might have updated the buffer 19651da177e4SLinus Torvalds * synchronously 19661da177e4SLinus Torvalds */ 19671da177e4SLinus Torvalds if (buffer_uptodate(bh)) 19681da177e4SLinus Torvalds continue; 19691da177e4SLinus Torvalds } 19701da177e4SLinus Torvalds arr[nr++] = bh; 19711da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 19721da177e4SLinus Torvalds 19731da177e4SLinus Torvalds if (fully_mapped) 19741da177e4SLinus Torvalds SetPageMappedToDisk(page); 19751da177e4SLinus Torvalds 19761da177e4SLinus Torvalds if (!nr) { 19771da177e4SLinus Torvalds /* 19781da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 19791da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 19801da177e4SLinus Torvalds */ 19811da177e4SLinus Torvalds if (!PageError(page)) 19821da177e4SLinus Torvalds SetPageUptodate(page); 19831da177e4SLinus Torvalds unlock_page(page); 19841da177e4SLinus Torvalds return 0; 19851da177e4SLinus Torvalds } 19861da177e4SLinus Torvalds 19871da177e4SLinus Torvalds /* Stage two: lock the buffers */ 19881da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 19891da177e4SLinus Torvalds bh = arr[i]; 19901da177e4SLinus Torvalds lock_buffer(bh); 19911da177e4SLinus Torvalds mark_buffer_async_read(bh); 19921da177e4SLinus Torvalds } 19931da177e4SLinus Torvalds 19941da177e4SLinus Torvalds /* 19951da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 19961da177e4SLinus Torvalds * inside the buffer lock in case another process reading 19971da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 19981da177e4SLinus Torvalds */ 19991da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 20001da177e4SLinus Torvalds bh = arr[i]; 20011da177e4SLinus Torvalds if (buffer_uptodate(bh)) 20021da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 20031da177e4SLinus Torvalds else 20041da177e4SLinus Torvalds submit_bh(READ, bh); 20051da177e4SLinus Torvalds } 20061da177e4SLinus Torvalds return 0; 20071da177e4SLinus Torvalds } 20081da177e4SLinus Torvalds 20091da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 20101da177e4SLinus Torvalds * truncates. Uses prepare/commit_write to allow the filesystem to 20111da177e4SLinus Torvalds * deal with the hole. 20121da177e4SLinus Torvalds */ 201305eb0b51SOGAWA Hirofumi static int __generic_cont_expand(struct inode *inode, loff_t size, 201405eb0b51SOGAWA Hirofumi pgoff_t index, unsigned int offset) 20151da177e4SLinus Torvalds { 20161da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 20171da177e4SLinus Torvalds struct page *page; 201805eb0b51SOGAWA Hirofumi unsigned long limit; 20191da177e4SLinus Torvalds int err; 20201da177e4SLinus Torvalds 20211da177e4SLinus Torvalds err = -EFBIG; 20221da177e4SLinus Torvalds limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 20231da177e4SLinus Torvalds if (limit != RLIM_INFINITY && size > (loff_t)limit) { 20241da177e4SLinus Torvalds send_sig(SIGXFSZ, current, 0); 20251da177e4SLinus Torvalds goto out; 20261da177e4SLinus Torvalds } 20271da177e4SLinus Torvalds if (size > inode->i_sb->s_maxbytes) 20281da177e4SLinus Torvalds goto out; 20291da177e4SLinus Torvalds 203005eb0b51SOGAWA Hirofumi err = -ENOMEM; 203105eb0b51SOGAWA Hirofumi page = grab_cache_page(mapping, index); 203205eb0b51SOGAWA Hirofumi if (!page) 203305eb0b51SOGAWA Hirofumi goto out; 203405eb0b51SOGAWA Hirofumi err = mapping->a_ops->prepare_write(NULL, page, offset, offset); 203505eb0b51SOGAWA Hirofumi if (err) { 203605eb0b51SOGAWA Hirofumi /* 203705eb0b51SOGAWA Hirofumi * ->prepare_write() may have instantiated a few blocks 203805eb0b51SOGAWA Hirofumi * outside i_size. Trim these off again. 203905eb0b51SOGAWA Hirofumi */ 204005eb0b51SOGAWA Hirofumi unlock_page(page); 204105eb0b51SOGAWA Hirofumi page_cache_release(page); 204205eb0b51SOGAWA Hirofumi vmtruncate(inode, inode->i_size); 204305eb0b51SOGAWA Hirofumi goto out; 204405eb0b51SOGAWA Hirofumi } 204505eb0b51SOGAWA Hirofumi 204605eb0b51SOGAWA Hirofumi err = mapping->a_ops->commit_write(NULL, page, offset, offset); 204705eb0b51SOGAWA Hirofumi 204805eb0b51SOGAWA Hirofumi unlock_page(page); 204905eb0b51SOGAWA Hirofumi page_cache_release(page); 205005eb0b51SOGAWA Hirofumi if (err > 0) 205105eb0b51SOGAWA Hirofumi err = 0; 205205eb0b51SOGAWA Hirofumi out: 205305eb0b51SOGAWA Hirofumi return err; 205405eb0b51SOGAWA Hirofumi } 205505eb0b51SOGAWA Hirofumi 205605eb0b51SOGAWA Hirofumi int generic_cont_expand(struct inode *inode, loff_t size) 205705eb0b51SOGAWA Hirofumi { 205805eb0b51SOGAWA Hirofumi pgoff_t index; 205905eb0b51SOGAWA Hirofumi unsigned int offset; 206005eb0b51SOGAWA Hirofumi 20611da177e4SLinus Torvalds offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */ 20621da177e4SLinus Torvalds 20631da177e4SLinus Torvalds /* ugh. in prepare/commit_write, if from==to==start of block, we 20641da177e4SLinus Torvalds ** skip the prepare. make sure we never send an offset for the start 20651da177e4SLinus Torvalds ** of a block 20661da177e4SLinus Torvalds */ 20671da177e4SLinus Torvalds if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) { 206805eb0b51SOGAWA Hirofumi /* caller must handle this extra byte. */ 20691da177e4SLinus Torvalds offset++; 20701da177e4SLinus Torvalds } 20711da177e4SLinus Torvalds index = size >> PAGE_CACHE_SHIFT; 207205eb0b51SOGAWA Hirofumi 207305eb0b51SOGAWA Hirofumi return __generic_cont_expand(inode, size, index, offset); 20741da177e4SLinus Torvalds } 207505eb0b51SOGAWA Hirofumi 207605eb0b51SOGAWA Hirofumi int generic_cont_expand_simple(struct inode *inode, loff_t size) 207705eb0b51SOGAWA Hirofumi { 207805eb0b51SOGAWA Hirofumi loff_t pos = size - 1; 207905eb0b51SOGAWA Hirofumi pgoff_t index = pos >> PAGE_CACHE_SHIFT; 208005eb0b51SOGAWA Hirofumi unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1; 208105eb0b51SOGAWA Hirofumi 208205eb0b51SOGAWA Hirofumi /* prepare/commit_write can handle even if from==to==start of block. */ 208305eb0b51SOGAWA Hirofumi return __generic_cont_expand(inode, size, index, offset); 20841da177e4SLinus Torvalds } 20851da177e4SLinus Torvalds 20861da177e4SLinus Torvalds /* 20871da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 20881da177e4SLinus Torvalds * We may have to extend the file. 20891da177e4SLinus Torvalds */ 20901da177e4SLinus Torvalds 20911da177e4SLinus Torvalds int cont_prepare_write(struct page *page, unsigned offset, 20921da177e4SLinus Torvalds unsigned to, get_block_t *get_block, loff_t *bytes) 20931da177e4SLinus Torvalds { 20941da177e4SLinus Torvalds struct address_space *mapping = page->mapping; 20951da177e4SLinus Torvalds struct inode *inode = mapping->host; 20961da177e4SLinus Torvalds struct page *new_page; 20971da177e4SLinus Torvalds pgoff_t pgpos; 20981da177e4SLinus Torvalds long status; 20991da177e4SLinus Torvalds unsigned zerofrom; 21001da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 21011da177e4SLinus Torvalds void *kaddr; 21021da177e4SLinus Torvalds 21031da177e4SLinus Torvalds while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) { 21041da177e4SLinus Torvalds status = -ENOMEM; 21051da177e4SLinus Torvalds new_page = grab_cache_page(mapping, pgpos); 21061da177e4SLinus Torvalds if (!new_page) 21071da177e4SLinus Torvalds goto out; 21081da177e4SLinus Torvalds /* we might sleep */ 21091da177e4SLinus Torvalds if (*bytes>>PAGE_CACHE_SHIFT != pgpos) { 21101da177e4SLinus Torvalds unlock_page(new_page); 21111da177e4SLinus Torvalds page_cache_release(new_page); 21121da177e4SLinus Torvalds continue; 21131da177e4SLinus Torvalds } 21141da177e4SLinus Torvalds zerofrom = *bytes & ~PAGE_CACHE_MASK; 21151da177e4SLinus Torvalds if (zerofrom & (blocksize-1)) { 21161da177e4SLinus Torvalds *bytes |= (blocksize-1); 21171da177e4SLinus Torvalds (*bytes)++; 21181da177e4SLinus Torvalds } 21191da177e4SLinus Torvalds status = __block_prepare_write(inode, new_page, zerofrom, 21201da177e4SLinus Torvalds PAGE_CACHE_SIZE, get_block); 21211da177e4SLinus Torvalds if (status) 21221da177e4SLinus Torvalds goto out_unmap; 21231da177e4SLinus Torvalds kaddr = kmap_atomic(new_page, KM_USER0); 21241da177e4SLinus Torvalds memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom); 21251da177e4SLinus Torvalds flush_dcache_page(new_page); 21261da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 21271da177e4SLinus Torvalds generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE); 21281da177e4SLinus Torvalds unlock_page(new_page); 21291da177e4SLinus Torvalds page_cache_release(new_page); 21301da177e4SLinus Torvalds } 21311da177e4SLinus Torvalds 21321da177e4SLinus Torvalds if (page->index < pgpos) { 21331da177e4SLinus Torvalds /* completely inside the area */ 21341da177e4SLinus Torvalds zerofrom = offset; 21351da177e4SLinus Torvalds } else { 21361da177e4SLinus Torvalds /* page covers the boundary, find the boundary offset */ 21371da177e4SLinus Torvalds zerofrom = *bytes & ~PAGE_CACHE_MASK; 21381da177e4SLinus Torvalds 21391da177e4SLinus Torvalds /* if we will expand the thing last block will be filled */ 21401da177e4SLinus Torvalds if (to > zerofrom && (zerofrom & (blocksize-1))) { 21411da177e4SLinus Torvalds *bytes |= (blocksize-1); 21421da177e4SLinus Torvalds (*bytes)++; 21431da177e4SLinus Torvalds } 21441da177e4SLinus Torvalds 21451da177e4SLinus Torvalds /* starting below the boundary? Nothing to zero out */ 21461da177e4SLinus Torvalds if (offset <= zerofrom) 21471da177e4SLinus Torvalds zerofrom = offset; 21481da177e4SLinus Torvalds } 21491da177e4SLinus Torvalds status = __block_prepare_write(inode, page, zerofrom, to, get_block); 21501da177e4SLinus Torvalds if (status) 21511da177e4SLinus Torvalds goto out1; 21521da177e4SLinus Torvalds if (zerofrom < offset) { 21531da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 21541da177e4SLinus Torvalds memset(kaddr+zerofrom, 0, offset-zerofrom); 21551da177e4SLinus Torvalds flush_dcache_page(page); 21561da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 21571da177e4SLinus Torvalds __block_commit_write(inode, page, zerofrom, offset); 21581da177e4SLinus Torvalds } 21591da177e4SLinus Torvalds return 0; 21601da177e4SLinus Torvalds out1: 21611da177e4SLinus Torvalds ClearPageUptodate(page); 21621da177e4SLinus Torvalds return status; 21631da177e4SLinus Torvalds 21641da177e4SLinus Torvalds out_unmap: 21651da177e4SLinus Torvalds ClearPageUptodate(new_page); 21661da177e4SLinus Torvalds unlock_page(new_page); 21671da177e4SLinus Torvalds page_cache_release(new_page); 21681da177e4SLinus Torvalds out: 21691da177e4SLinus Torvalds return status; 21701da177e4SLinus Torvalds } 21711da177e4SLinus Torvalds 21721da177e4SLinus Torvalds int block_prepare_write(struct page *page, unsigned from, unsigned to, 21731da177e4SLinus Torvalds get_block_t *get_block) 21741da177e4SLinus Torvalds { 21751da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 21761da177e4SLinus Torvalds int err = __block_prepare_write(inode, page, from, to, get_block); 21771da177e4SLinus Torvalds if (err) 21781da177e4SLinus Torvalds ClearPageUptodate(page); 21791da177e4SLinus Torvalds return err; 21801da177e4SLinus Torvalds } 21811da177e4SLinus Torvalds 21821da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 21831da177e4SLinus Torvalds { 21841da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 21851da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 21861da177e4SLinus Torvalds return 0; 21871da177e4SLinus Torvalds } 21881da177e4SLinus Torvalds 21891da177e4SLinus Torvalds int generic_commit_write(struct file *file, struct page *page, 21901da177e4SLinus Torvalds unsigned from, unsigned to) 21911da177e4SLinus Torvalds { 21921da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 21931da177e4SLinus Torvalds loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; 21941da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 21951da177e4SLinus Torvalds /* 21961da177e4SLinus Torvalds * No need to use i_size_read() here, the i_size 21971b1dcc1bSJes Sorensen * cannot change under us because we hold i_mutex. 21981da177e4SLinus Torvalds */ 21991da177e4SLinus Torvalds if (pos > inode->i_size) { 22001da177e4SLinus Torvalds i_size_write(inode, pos); 22011da177e4SLinus Torvalds mark_inode_dirty(inode); 22021da177e4SLinus Torvalds } 22031da177e4SLinus Torvalds return 0; 22041da177e4SLinus Torvalds } 22051da177e4SLinus Torvalds 22061da177e4SLinus Torvalds 22071da177e4SLinus Torvalds /* 22081da177e4SLinus Torvalds * nobh_prepare_write()'s prereads are special: the buffer_heads are freed 22091da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 22101da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 22111da177e4SLinus Torvalds * 22121da177e4SLinus Torvalds * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but 22131da177e4SLinus Torvalds * a race there is benign: unlock_buffer() only use the bh's address for 22141da177e4SLinus Torvalds * hashing after unlocking the buffer, so it doesn't actually touch the bh 22151da177e4SLinus Torvalds * itself. 22161da177e4SLinus Torvalds */ 22171da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 22181da177e4SLinus Torvalds { 22191da177e4SLinus Torvalds if (uptodate) { 22201da177e4SLinus Torvalds set_buffer_uptodate(bh); 22211da177e4SLinus Torvalds } else { 22221da177e4SLinus Torvalds /* This happens, due to failed READA attempts. */ 22231da177e4SLinus Torvalds clear_buffer_uptodate(bh); 22241da177e4SLinus Torvalds } 22251da177e4SLinus Torvalds unlock_buffer(bh); 22261da177e4SLinus Torvalds } 22271da177e4SLinus Torvalds 22281da177e4SLinus Torvalds /* 22291da177e4SLinus Torvalds * On entry, the page is fully not uptodate. 22301da177e4SLinus Torvalds * On exit the page is fully uptodate in the areas outside (from,to) 22311da177e4SLinus Torvalds */ 22321da177e4SLinus Torvalds int nobh_prepare_write(struct page *page, unsigned from, unsigned to, 22331da177e4SLinus Torvalds get_block_t *get_block) 22341da177e4SLinus Torvalds { 22351da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 22361da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 22371da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 22381da177e4SLinus Torvalds struct buffer_head map_bh; 22391da177e4SLinus Torvalds struct buffer_head *read_bh[MAX_BUF_PER_PAGE]; 22401da177e4SLinus Torvalds unsigned block_in_page; 22411da177e4SLinus Torvalds unsigned block_start; 22421da177e4SLinus Torvalds sector_t block_in_file; 22431da177e4SLinus Torvalds char *kaddr; 22441da177e4SLinus Torvalds int nr_reads = 0; 22451da177e4SLinus Torvalds int i; 22461da177e4SLinus Torvalds int ret = 0; 22471da177e4SLinus Torvalds int is_mapped_to_disk = 1; 22481da177e4SLinus Torvalds int dirtied_it = 0; 22491da177e4SLinus Torvalds 22501da177e4SLinus Torvalds if (PageMappedToDisk(page)) 22511da177e4SLinus Torvalds return 0; 22521da177e4SLinus Torvalds 22531da177e4SLinus Torvalds block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); 22541da177e4SLinus Torvalds map_bh.b_page = page; 22551da177e4SLinus Torvalds 22561da177e4SLinus Torvalds /* 22571da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 22581da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 22591da177e4SLinus Torvalds * page is fully mapped-to-disk. 22601da177e4SLinus Torvalds */ 22611da177e4SLinus Torvalds for (block_start = 0, block_in_page = 0; 22621da177e4SLinus Torvalds block_start < PAGE_CACHE_SIZE; 22631da177e4SLinus Torvalds block_in_page++, block_start += blocksize) { 22641da177e4SLinus Torvalds unsigned block_end = block_start + blocksize; 22651da177e4SLinus Torvalds int create; 22661da177e4SLinus Torvalds 22671da177e4SLinus Torvalds map_bh.b_state = 0; 22681da177e4SLinus Torvalds create = 1; 22691da177e4SLinus Torvalds if (block_start >= to) 22701da177e4SLinus Torvalds create = 0; 2271b0cf2321SBadari Pulavarty map_bh.b_size = blocksize; 22721da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 22731da177e4SLinus Torvalds &map_bh, create); 22741da177e4SLinus Torvalds if (ret) 22751da177e4SLinus Torvalds goto failed; 22761da177e4SLinus Torvalds if (!buffer_mapped(&map_bh)) 22771da177e4SLinus Torvalds is_mapped_to_disk = 0; 22781da177e4SLinus Torvalds if (buffer_new(&map_bh)) 22791da177e4SLinus Torvalds unmap_underlying_metadata(map_bh.b_bdev, 22801da177e4SLinus Torvalds map_bh.b_blocknr); 22811da177e4SLinus Torvalds if (PageUptodate(page)) 22821da177e4SLinus Torvalds continue; 22831da177e4SLinus Torvalds if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) { 22841da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 22851da177e4SLinus Torvalds if (block_start < from) { 22861da177e4SLinus Torvalds memset(kaddr+block_start, 0, from-block_start); 22871da177e4SLinus Torvalds dirtied_it = 1; 22881da177e4SLinus Torvalds } 22891da177e4SLinus Torvalds if (block_end > to) { 22901da177e4SLinus Torvalds memset(kaddr + to, 0, block_end - to); 22911da177e4SLinus Torvalds dirtied_it = 1; 22921da177e4SLinus Torvalds } 22931da177e4SLinus Torvalds flush_dcache_page(page); 22941da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 22951da177e4SLinus Torvalds continue; 22961da177e4SLinus Torvalds } 22971da177e4SLinus Torvalds if (buffer_uptodate(&map_bh)) 22981da177e4SLinus Torvalds continue; /* reiserfs does this */ 22991da177e4SLinus Torvalds if (block_start < from || block_end > to) { 23001da177e4SLinus Torvalds struct buffer_head *bh = alloc_buffer_head(GFP_NOFS); 23011da177e4SLinus Torvalds 23021da177e4SLinus Torvalds if (!bh) { 23031da177e4SLinus Torvalds ret = -ENOMEM; 23041da177e4SLinus Torvalds goto failed; 23051da177e4SLinus Torvalds } 23061da177e4SLinus Torvalds bh->b_state = map_bh.b_state; 23071da177e4SLinus Torvalds atomic_set(&bh->b_count, 0); 23081da177e4SLinus Torvalds bh->b_this_page = NULL; 23091da177e4SLinus Torvalds bh->b_page = page; 23101da177e4SLinus Torvalds bh->b_blocknr = map_bh.b_blocknr; 23111da177e4SLinus Torvalds bh->b_size = blocksize; 23121da177e4SLinus Torvalds bh->b_data = (char *)(long)block_start; 23131da177e4SLinus Torvalds bh->b_bdev = map_bh.b_bdev; 23141da177e4SLinus Torvalds bh->b_private = NULL; 23151da177e4SLinus Torvalds read_bh[nr_reads++] = bh; 23161da177e4SLinus Torvalds } 23171da177e4SLinus Torvalds } 23181da177e4SLinus Torvalds 23191da177e4SLinus Torvalds if (nr_reads) { 23201da177e4SLinus Torvalds struct buffer_head *bh; 23211da177e4SLinus Torvalds 23221da177e4SLinus Torvalds /* 23231da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 23241da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 23251da177e4SLinus Torvalds * for the buffer_head refcounts. 23261da177e4SLinus Torvalds */ 23271da177e4SLinus Torvalds for (i = 0; i < nr_reads; i++) { 23281da177e4SLinus Torvalds bh = read_bh[i]; 23291da177e4SLinus Torvalds lock_buffer(bh); 23301da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_nobh; 23311da177e4SLinus Torvalds submit_bh(READ, bh); 23321da177e4SLinus Torvalds } 23331da177e4SLinus Torvalds for (i = 0; i < nr_reads; i++) { 23341da177e4SLinus Torvalds bh = read_bh[i]; 23351da177e4SLinus Torvalds wait_on_buffer(bh); 23361da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 23371da177e4SLinus Torvalds ret = -EIO; 23381da177e4SLinus Torvalds free_buffer_head(bh); 23391da177e4SLinus Torvalds read_bh[i] = NULL; 23401da177e4SLinus Torvalds } 23411da177e4SLinus Torvalds if (ret) 23421da177e4SLinus Torvalds goto failed; 23431da177e4SLinus Torvalds } 23441da177e4SLinus Torvalds 23451da177e4SLinus Torvalds if (is_mapped_to_disk) 23461da177e4SLinus Torvalds SetPageMappedToDisk(page); 23471da177e4SLinus Torvalds SetPageUptodate(page); 23481da177e4SLinus Torvalds 23491da177e4SLinus Torvalds /* 23501da177e4SLinus Torvalds * Setting the page dirty here isn't necessary for the prepare_write 23511da177e4SLinus Torvalds * function - commit_write will do that. But if/when this function is 23521da177e4SLinus Torvalds * used within the pagefault handler to ensure that all mmapped pages 23531da177e4SLinus Torvalds * have backing space in the filesystem, we will need to dirty the page 23541da177e4SLinus Torvalds * if its contents were altered. 23551da177e4SLinus Torvalds */ 23561da177e4SLinus Torvalds if (dirtied_it) 23571da177e4SLinus Torvalds set_page_dirty(page); 23581da177e4SLinus Torvalds 23591da177e4SLinus Torvalds return 0; 23601da177e4SLinus Torvalds 23611da177e4SLinus Torvalds failed: 23621da177e4SLinus Torvalds for (i = 0; i < nr_reads; i++) { 23631da177e4SLinus Torvalds if (read_bh[i]) 23641da177e4SLinus Torvalds free_buffer_head(read_bh[i]); 23651da177e4SLinus Torvalds } 23661da177e4SLinus Torvalds 23671da177e4SLinus Torvalds /* 23681da177e4SLinus Torvalds * Error recovery is pretty slack. Clear the page and mark it dirty 23691da177e4SLinus Torvalds * so we'll later zero out any blocks which _were_ allocated. 23701da177e4SLinus Torvalds */ 23711da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 23721da177e4SLinus Torvalds memset(kaddr, 0, PAGE_CACHE_SIZE); 23738c581651SMonakhov Dmitriy flush_dcache_page(page); 23741da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 23751da177e4SLinus Torvalds SetPageUptodate(page); 23761da177e4SLinus Torvalds set_page_dirty(page); 23771da177e4SLinus Torvalds return ret; 23781da177e4SLinus Torvalds } 23791da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_prepare_write); 23801da177e4SLinus Torvalds 23811da177e4SLinus Torvalds int nobh_commit_write(struct file *file, struct page *page, 23821da177e4SLinus Torvalds unsigned from, unsigned to) 23831da177e4SLinus Torvalds { 23841da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23851da177e4SLinus Torvalds loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; 23861da177e4SLinus Torvalds 23871da177e4SLinus Torvalds set_page_dirty(page); 23881da177e4SLinus Torvalds if (pos > inode->i_size) { 23891da177e4SLinus Torvalds i_size_write(inode, pos); 23901da177e4SLinus Torvalds mark_inode_dirty(inode); 23911da177e4SLinus Torvalds } 23921da177e4SLinus Torvalds return 0; 23931da177e4SLinus Torvalds } 23941da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_commit_write); 23951da177e4SLinus Torvalds 23961da177e4SLinus Torvalds /* 23971da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 23981da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 23991da177e4SLinus Torvalds * the page. 24001da177e4SLinus Torvalds */ 24011da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 24021da177e4SLinus Torvalds struct writeback_control *wbc) 24031da177e4SLinus Torvalds { 24041da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 24051da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 24061da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 24071da177e4SLinus Torvalds unsigned offset; 24081da177e4SLinus Torvalds void *kaddr; 24091da177e4SLinus Torvalds int ret; 24101da177e4SLinus Torvalds 24111da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 24121da177e4SLinus Torvalds if (page->index < end_index) 24131da177e4SLinus Torvalds goto out; 24141da177e4SLinus Torvalds 24151da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 24161da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 24171da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 24181da177e4SLinus Torvalds /* 24191da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 24201da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 24211da177e4SLinus Torvalds * freeable here, so the page does not leak. 24221da177e4SLinus Torvalds */ 24231da177e4SLinus Torvalds #if 0 24241da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 24251da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 24261da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 24271da177e4SLinus Torvalds #endif 24281da177e4SLinus Torvalds unlock_page(page); 24291da177e4SLinus Torvalds return 0; /* don't care */ 24301da177e4SLinus Torvalds } 24311da177e4SLinus Torvalds 24321da177e4SLinus Torvalds /* 24331da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 24341da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 24351da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 24361da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 24371da177e4SLinus Torvalds * writes to that region are not written out to the file." 24381da177e4SLinus Torvalds */ 24391da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 24401da177e4SLinus Torvalds memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); 24411da177e4SLinus Torvalds flush_dcache_page(page); 24421da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 24431da177e4SLinus Torvalds out: 24441da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 24451da177e4SLinus Torvalds if (ret == -EAGAIN) 24461da177e4SLinus Torvalds ret = __block_write_full_page(inode, page, get_block, wbc); 24471da177e4SLinus Torvalds return ret; 24481da177e4SLinus Torvalds } 24491da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 24501da177e4SLinus Torvalds 24511da177e4SLinus Torvalds /* 24521da177e4SLinus Torvalds * This function assumes that ->prepare_write() uses nobh_prepare_write(). 24531da177e4SLinus Torvalds */ 24541da177e4SLinus Torvalds int nobh_truncate_page(struct address_space *mapping, loff_t from) 24551da177e4SLinus Torvalds { 24561da177e4SLinus Torvalds struct inode *inode = mapping->host; 24571da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 24581da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 24591da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 24601da177e4SLinus Torvalds unsigned to; 24611da177e4SLinus Torvalds struct page *page; 2462f5e54d6eSChristoph Hellwig const struct address_space_operations *a_ops = mapping->a_ops; 24631da177e4SLinus Torvalds char *kaddr; 24641da177e4SLinus Torvalds int ret = 0; 24651da177e4SLinus Torvalds 24661da177e4SLinus Torvalds if ((offset & (blocksize - 1)) == 0) 24671da177e4SLinus Torvalds goto out; 24681da177e4SLinus Torvalds 24691da177e4SLinus Torvalds ret = -ENOMEM; 24701da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 24711da177e4SLinus Torvalds if (!page) 24721da177e4SLinus Torvalds goto out; 24731da177e4SLinus Torvalds 24741da177e4SLinus Torvalds to = (offset + blocksize) & ~(blocksize - 1); 24751da177e4SLinus Torvalds ret = a_ops->prepare_write(NULL, page, offset, to); 24761da177e4SLinus Torvalds if (ret == 0) { 24771da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 24781da177e4SLinus Torvalds memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); 24791da177e4SLinus Torvalds flush_dcache_page(page); 24801da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 24811da177e4SLinus Torvalds set_page_dirty(page); 24821da177e4SLinus Torvalds } 24831da177e4SLinus Torvalds unlock_page(page); 24841da177e4SLinus Torvalds page_cache_release(page); 24851da177e4SLinus Torvalds out: 24861da177e4SLinus Torvalds return ret; 24871da177e4SLinus Torvalds } 24881da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 24891da177e4SLinus Torvalds 24901da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 24911da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 24921da177e4SLinus Torvalds { 24931da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 24941da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 24951da177e4SLinus Torvalds unsigned blocksize; 249654b21a79SAndrew Morton sector_t iblock; 24971da177e4SLinus Torvalds unsigned length, pos; 24981da177e4SLinus Torvalds struct inode *inode = mapping->host; 24991da177e4SLinus Torvalds struct page *page; 25001da177e4SLinus Torvalds struct buffer_head *bh; 25011da177e4SLinus Torvalds void *kaddr; 25021da177e4SLinus Torvalds int err; 25031da177e4SLinus Torvalds 25041da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 25051da177e4SLinus Torvalds length = offset & (blocksize - 1); 25061da177e4SLinus Torvalds 25071da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 25081da177e4SLinus Torvalds if (!length) 25091da177e4SLinus Torvalds return 0; 25101da177e4SLinus Torvalds 25111da177e4SLinus Torvalds length = blocksize - length; 251254b21a79SAndrew Morton iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 25131da177e4SLinus Torvalds 25141da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 25151da177e4SLinus Torvalds err = -ENOMEM; 25161da177e4SLinus Torvalds if (!page) 25171da177e4SLinus Torvalds goto out; 25181da177e4SLinus Torvalds 25191da177e4SLinus Torvalds if (!page_has_buffers(page)) 25201da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 25211da177e4SLinus Torvalds 25221da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 25231da177e4SLinus Torvalds bh = page_buffers(page); 25241da177e4SLinus Torvalds pos = blocksize; 25251da177e4SLinus Torvalds while (offset >= pos) { 25261da177e4SLinus Torvalds bh = bh->b_this_page; 25271da177e4SLinus Torvalds iblock++; 25281da177e4SLinus Torvalds pos += blocksize; 25291da177e4SLinus Torvalds } 25301da177e4SLinus Torvalds 25311da177e4SLinus Torvalds err = 0; 25321da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2533b0cf2321SBadari Pulavarty WARN_ON(bh->b_size != blocksize); 25341da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 25351da177e4SLinus Torvalds if (err) 25361da177e4SLinus Torvalds goto unlock; 25371da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 25381da177e4SLinus Torvalds if (!buffer_mapped(bh)) 25391da177e4SLinus Torvalds goto unlock; 25401da177e4SLinus Torvalds } 25411da177e4SLinus Torvalds 25421da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 25431da177e4SLinus Torvalds if (PageUptodate(page)) 25441da177e4SLinus Torvalds set_buffer_uptodate(bh); 25451da177e4SLinus Torvalds 25461da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh)) { 25471da177e4SLinus Torvalds err = -EIO; 25481da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 25491da177e4SLinus Torvalds wait_on_buffer(bh); 25501da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 25511da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 25521da177e4SLinus Torvalds goto unlock; 25531da177e4SLinus Torvalds } 25541da177e4SLinus Torvalds 25551da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 25561da177e4SLinus Torvalds memset(kaddr + offset, 0, length); 25571da177e4SLinus Torvalds flush_dcache_page(page); 25581da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 25591da177e4SLinus Torvalds 25601da177e4SLinus Torvalds mark_buffer_dirty(bh); 25611da177e4SLinus Torvalds err = 0; 25621da177e4SLinus Torvalds 25631da177e4SLinus Torvalds unlock: 25641da177e4SLinus Torvalds unlock_page(page); 25651da177e4SLinus Torvalds page_cache_release(page); 25661da177e4SLinus Torvalds out: 25671da177e4SLinus Torvalds return err; 25681da177e4SLinus Torvalds } 25691da177e4SLinus Torvalds 25701da177e4SLinus Torvalds /* 25711da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 25721da177e4SLinus Torvalds */ 25731da177e4SLinus Torvalds int block_write_full_page(struct page *page, get_block_t *get_block, 25741da177e4SLinus Torvalds struct writeback_control *wbc) 25751da177e4SLinus Torvalds { 25761da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 25771da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 25781da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 25791da177e4SLinus Torvalds unsigned offset; 25801da177e4SLinus Torvalds void *kaddr; 25811da177e4SLinus Torvalds 25821da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 25831da177e4SLinus Torvalds if (page->index < end_index) 25841da177e4SLinus Torvalds return __block_write_full_page(inode, page, get_block, wbc); 25851da177e4SLinus Torvalds 25861da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 25871da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 25881da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 25891da177e4SLinus Torvalds /* 25901da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 25911da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 25921da177e4SLinus Torvalds * freeable here, so the page does not leak. 25931da177e4SLinus Torvalds */ 2594aaa4059bSJan Kara do_invalidatepage(page, 0); 25951da177e4SLinus Torvalds unlock_page(page); 25961da177e4SLinus Torvalds return 0; /* don't care */ 25971da177e4SLinus Torvalds } 25981da177e4SLinus Torvalds 25991da177e4SLinus Torvalds /* 26001da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 26011da177e4SLinus Torvalds * writepage invokation because it may be mmapped. "A file is mapped 26021da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 26031da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 26041da177e4SLinus Torvalds * writes to that region are not written out to the file." 26051da177e4SLinus Torvalds */ 26061da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 26071da177e4SLinus Torvalds memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); 26081da177e4SLinus Torvalds flush_dcache_page(page); 26091da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 26101da177e4SLinus Torvalds return __block_write_full_page(inode, page, get_block, wbc); 26111da177e4SLinus Torvalds } 26121da177e4SLinus Torvalds 26131da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 26141da177e4SLinus Torvalds get_block_t *get_block) 26151da177e4SLinus Torvalds { 26161da177e4SLinus Torvalds struct buffer_head tmp; 26171da177e4SLinus Torvalds struct inode *inode = mapping->host; 26181da177e4SLinus Torvalds tmp.b_state = 0; 26191da177e4SLinus Torvalds tmp.b_blocknr = 0; 2620b0cf2321SBadari Pulavarty tmp.b_size = 1 << inode->i_blkbits; 26211da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 26221da177e4SLinus Torvalds return tmp.b_blocknr; 26231da177e4SLinus Torvalds } 26241da177e4SLinus Torvalds 26251da177e4SLinus Torvalds static int end_bio_bh_io_sync(struct bio *bio, unsigned int bytes_done, int err) 26261da177e4SLinus Torvalds { 26271da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 26281da177e4SLinus Torvalds 26291da177e4SLinus Torvalds if (bio->bi_size) 26301da177e4SLinus Torvalds return 1; 26311da177e4SLinus Torvalds 26321da177e4SLinus Torvalds if (err == -EOPNOTSUPP) { 26331da177e4SLinus Torvalds set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); 26341da177e4SLinus Torvalds set_bit(BH_Eopnotsupp, &bh->b_state); 26351da177e4SLinus Torvalds } 26361da177e4SLinus Torvalds 26371da177e4SLinus Torvalds bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); 26381da177e4SLinus Torvalds bio_put(bio); 26391da177e4SLinus Torvalds return 0; 26401da177e4SLinus Torvalds } 26411da177e4SLinus Torvalds 26421da177e4SLinus Torvalds int submit_bh(int rw, struct buffer_head * bh) 26431da177e4SLinus Torvalds { 26441da177e4SLinus Torvalds struct bio *bio; 26451da177e4SLinus Torvalds int ret = 0; 26461da177e4SLinus Torvalds 26471da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 26481da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 26491da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 26501da177e4SLinus Torvalds 26511da177e4SLinus Torvalds if (buffer_ordered(bh) && (rw == WRITE)) 26521da177e4SLinus Torvalds rw = WRITE_BARRIER; 26531da177e4SLinus Torvalds 26541da177e4SLinus Torvalds /* 26551da177e4SLinus Torvalds * Only clear out a write error when rewriting, should this 26561da177e4SLinus Torvalds * include WRITE_SYNC as well? 26571da177e4SLinus Torvalds */ 26581da177e4SLinus Torvalds if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER)) 26591da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 26601da177e4SLinus Torvalds 26611da177e4SLinus Torvalds /* 26621da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 26631da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 26641da177e4SLinus Torvalds */ 26651da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 26661da177e4SLinus Torvalds 26671da177e4SLinus Torvalds bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); 26681da177e4SLinus Torvalds bio->bi_bdev = bh->b_bdev; 26691da177e4SLinus Torvalds bio->bi_io_vec[0].bv_page = bh->b_page; 26701da177e4SLinus Torvalds bio->bi_io_vec[0].bv_len = bh->b_size; 26711da177e4SLinus Torvalds bio->bi_io_vec[0].bv_offset = bh_offset(bh); 26721da177e4SLinus Torvalds 26731da177e4SLinus Torvalds bio->bi_vcnt = 1; 26741da177e4SLinus Torvalds bio->bi_idx = 0; 26751da177e4SLinus Torvalds bio->bi_size = bh->b_size; 26761da177e4SLinus Torvalds 26771da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 26781da177e4SLinus Torvalds bio->bi_private = bh; 26791da177e4SLinus Torvalds 26801da177e4SLinus Torvalds bio_get(bio); 26811da177e4SLinus Torvalds submit_bio(rw, bio); 26821da177e4SLinus Torvalds 26831da177e4SLinus Torvalds if (bio_flagged(bio, BIO_EOPNOTSUPP)) 26841da177e4SLinus Torvalds ret = -EOPNOTSUPP; 26851da177e4SLinus Torvalds 26861da177e4SLinus Torvalds bio_put(bio); 26871da177e4SLinus Torvalds return ret; 26881da177e4SLinus Torvalds } 26891da177e4SLinus Torvalds 26901da177e4SLinus Torvalds /** 26911da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 2692a7662236SJan Kara * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead) 26931da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 26941da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 26951da177e4SLinus Torvalds * 2696a7662236SJan Kara * ll_rw_block() takes an array of pointers to &struct buffer_heads, and 2697a7662236SJan Kara * requests an I/O operation on them, either a %READ or a %WRITE. The third 2698a7662236SJan Kara * %SWRITE is like %WRITE only we make sure that the *current* data in buffers 2699a7662236SJan Kara * are sent to disk. The fourth %READA option is described in the documentation 2700a7662236SJan Kara * for generic_make_request() which ll_rw_block() calls. 27011da177e4SLinus Torvalds * 27021da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 2703a7662236SJan Kara * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be 2704a7662236SJan Kara * clean when doing a write request, and any buffer that appears to be 2705a7662236SJan Kara * up-to-date when doing read request. Further it marks as clean buffers that 2706a7662236SJan Kara * are processed for writing (the buffer cache won't assume that they are 2707a7662236SJan Kara * actually clean until the buffer gets unlocked). 27081da177e4SLinus Torvalds * 27091da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 27101da177e4SLinus Torvalds * the buffer up-to-date (if approriate), unlocks the buffer and wakes 27111da177e4SLinus Torvalds * any waiters. 27121da177e4SLinus Torvalds * 27131da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 27141da177e4SLinus Torvalds * multiple of the current approved size for the device. 27151da177e4SLinus Torvalds */ 27161da177e4SLinus Torvalds void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) 27171da177e4SLinus Torvalds { 27181da177e4SLinus Torvalds int i; 27191da177e4SLinus Torvalds 27201da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 27211da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 27221da177e4SLinus Torvalds 2723a7662236SJan Kara if (rw == SWRITE) 2724a7662236SJan Kara lock_buffer(bh); 2725a7662236SJan Kara else if (test_set_buffer_locked(bh)) 27261da177e4SLinus Torvalds continue; 27271da177e4SLinus Torvalds 2728a7662236SJan Kara if (rw == WRITE || rw == SWRITE) { 27291da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 273076c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 2731e60e5c50SOGAWA Hirofumi get_bh(bh); 27321da177e4SLinus Torvalds submit_bh(WRITE, bh); 27331da177e4SLinus Torvalds continue; 27341da177e4SLinus Torvalds } 27351da177e4SLinus Torvalds } else { 27361da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 273776c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 2738e60e5c50SOGAWA Hirofumi get_bh(bh); 27391da177e4SLinus Torvalds submit_bh(rw, bh); 27401da177e4SLinus Torvalds continue; 27411da177e4SLinus Torvalds } 27421da177e4SLinus Torvalds } 27431da177e4SLinus Torvalds unlock_buffer(bh); 27441da177e4SLinus Torvalds } 27451da177e4SLinus Torvalds } 27461da177e4SLinus Torvalds 27471da177e4SLinus Torvalds /* 27481da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 27491da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 27501da177e4SLinus Torvalds * the buffer_head. 27511da177e4SLinus Torvalds */ 27521da177e4SLinus Torvalds int sync_dirty_buffer(struct buffer_head *bh) 27531da177e4SLinus Torvalds { 27541da177e4SLinus Torvalds int ret = 0; 27551da177e4SLinus Torvalds 27561da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 27571da177e4SLinus Torvalds lock_buffer(bh); 27581da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 27591da177e4SLinus Torvalds get_bh(bh); 27601da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 27611da177e4SLinus Torvalds ret = submit_bh(WRITE, bh); 27621da177e4SLinus Torvalds wait_on_buffer(bh); 27631da177e4SLinus Torvalds if (buffer_eopnotsupp(bh)) { 27641da177e4SLinus Torvalds clear_buffer_eopnotsupp(bh); 27651da177e4SLinus Torvalds ret = -EOPNOTSUPP; 27661da177e4SLinus Torvalds } 27671da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 27681da177e4SLinus Torvalds ret = -EIO; 27691da177e4SLinus Torvalds } else { 27701da177e4SLinus Torvalds unlock_buffer(bh); 27711da177e4SLinus Torvalds } 27721da177e4SLinus Torvalds return ret; 27731da177e4SLinus Torvalds } 27741da177e4SLinus Torvalds 27751da177e4SLinus Torvalds /* 27761da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 27771da177e4SLinus Torvalds * are unused, and releases them if so. 27781da177e4SLinus Torvalds * 27791da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 27801da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 27811da177e4SLinus Torvalds * 27821da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 27831da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 27841da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 27851da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 27861da177e4SLinus Torvalds * filesystem data on the same device. 27871da177e4SLinus Torvalds * 27881da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 27891da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 27901da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 27911da177e4SLinus Torvalds * private_lock. 27921da177e4SLinus Torvalds * 27931da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 27941da177e4SLinus Torvalds */ 27951da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 27961da177e4SLinus Torvalds { 27971da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 27981da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 27991da177e4SLinus Torvalds } 28001da177e4SLinus Torvalds 28011da177e4SLinus Torvalds static int 28021da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 28031da177e4SLinus Torvalds { 28041da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 28051da177e4SLinus Torvalds struct buffer_head *bh; 28061da177e4SLinus Torvalds 28071da177e4SLinus Torvalds bh = head; 28081da177e4SLinus Torvalds do { 2809de7d5a3bSakpm@osdl.org if (buffer_write_io_error(bh) && page->mapping) 28101da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 28111da177e4SLinus Torvalds if (buffer_busy(bh)) 28121da177e4SLinus Torvalds goto failed; 28131da177e4SLinus Torvalds bh = bh->b_this_page; 28141da177e4SLinus Torvalds } while (bh != head); 28151da177e4SLinus Torvalds 28161da177e4SLinus Torvalds do { 28171da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 28181da177e4SLinus Torvalds 28191da177e4SLinus Torvalds if (!list_empty(&bh->b_assoc_buffers)) 28201da177e4SLinus Torvalds __remove_assoc_queue(bh); 28211da177e4SLinus Torvalds bh = next; 28221da177e4SLinus Torvalds } while (bh != head); 28231da177e4SLinus Torvalds *buffers_to_free = head; 28241da177e4SLinus Torvalds __clear_page_buffers(page); 28251da177e4SLinus Torvalds return 1; 28261da177e4SLinus Torvalds failed: 28271da177e4SLinus Torvalds return 0; 28281da177e4SLinus Torvalds } 28291da177e4SLinus Torvalds 28301da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 28311da177e4SLinus Torvalds { 28321da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 28331da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 28341da177e4SLinus Torvalds int ret = 0; 28351da177e4SLinus Torvalds 28361da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 2837ecdfc978SLinus Torvalds if (PageWriteback(page)) 28381da177e4SLinus Torvalds return 0; 28391da177e4SLinus Torvalds 28401da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 28411da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 28421da177e4SLinus Torvalds goto out; 28431da177e4SLinus Torvalds } 28441da177e4SLinus Torvalds 28451da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 28461da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 2847ecdfc978SLinus Torvalds 2848ecdfc978SLinus Torvalds /* 2849ecdfc978SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 2850ecdfc978SLinus Torvalds * then we can have clean buffers against a dirty page. We 2851ecdfc978SLinus Torvalds * clean the page here; otherwise the VM will never notice 2852ecdfc978SLinus Torvalds * that the filesystem did any IO at all. 2853ecdfc978SLinus Torvalds * 2854ecdfc978SLinus Torvalds * Also, during truncate, discard_buffer will have marked all 2855ecdfc978SLinus Torvalds * the page's buffers clean. We discover that here and clean 2856ecdfc978SLinus Torvalds * the page also. 285787df7241SNick Piggin * 285887df7241SNick Piggin * private_lock must be held over this entire operation in order 285987df7241SNick Piggin * to synchronise against __set_page_dirty_buffers and prevent the 286087df7241SNick Piggin * dirty bit from being lost. 2861ecdfc978SLinus Torvalds */ 2862ecdfc978SLinus Torvalds if (ret) 2863ecdfc978SLinus Torvalds cancel_dirty_page(page, PAGE_CACHE_SIZE); 286487df7241SNick Piggin spin_unlock(&mapping->private_lock); 28651da177e4SLinus Torvalds out: 28661da177e4SLinus Torvalds if (buffers_to_free) { 28671da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 28681da177e4SLinus Torvalds 28691da177e4SLinus Torvalds do { 28701da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 28711da177e4SLinus Torvalds free_buffer_head(bh); 28721da177e4SLinus Torvalds bh = next; 28731da177e4SLinus Torvalds } while (bh != buffers_to_free); 28741da177e4SLinus Torvalds } 28751da177e4SLinus Torvalds return ret; 28761da177e4SLinus Torvalds } 28771da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 28781da177e4SLinus Torvalds 28793978d717SNeilBrown void block_sync_page(struct page *page) 28801da177e4SLinus Torvalds { 28811da177e4SLinus Torvalds struct address_space *mapping; 28821da177e4SLinus Torvalds 28831da177e4SLinus Torvalds smp_mb(); 28841da177e4SLinus Torvalds mapping = page_mapping(page); 28851da177e4SLinus Torvalds if (mapping) 28861da177e4SLinus Torvalds blk_run_backing_dev(mapping->backing_dev_info, page); 28871da177e4SLinus Torvalds } 28881da177e4SLinus Torvalds 28891da177e4SLinus Torvalds /* 28901da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 28911da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 28921da177e4SLinus Torvalds * 28931da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 28941da177e4SLinus Torvalds * The `pdflush' kernel threads fully replace bdflush daemons and this call. 28951da177e4SLinus Torvalds */ 28961da177e4SLinus Torvalds asmlinkage long sys_bdflush(int func, long data) 28971da177e4SLinus Torvalds { 28981da177e4SLinus Torvalds static int msg_count; 28991da177e4SLinus Torvalds 29001da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 29011da177e4SLinus Torvalds return -EPERM; 29021da177e4SLinus Torvalds 29031da177e4SLinus Torvalds if (msg_count < 5) { 29041da177e4SLinus Torvalds msg_count++; 29051da177e4SLinus Torvalds printk(KERN_INFO 29061da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 29071da177e4SLinus Torvalds " system call\n", current->comm); 29081da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 29091da177e4SLinus Torvalds } 29101da177e4SLinus Torvalds 29111da177e4SLinus Torvalds if (func == 1) 29121da177e4SLinus Torvalds do_exit(0); 29131da177e4SLinus Torvalds return 0; 29141da177e4SLinus Torvalds } 29151da177e4SLinus Torvalds 29161da177e4SLinus Torvalds /* 29171da177e4SLinus Torvalds * Buffer-head allocation 29181da177e4SLinus Torvalds */ 2919e18b890bSChristoph Lameter static struct kmem_cache *bh_cachep; 29201da177e4SLinus Torvalds 29211da177e4SLinus Torvalds /* 29221da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 29231da177e4SLinus Torvalds * stripping them in writeback. 29241da177e4SLinus Torvalds */ 29251da177e4SLinus Torvalds static int max_buffer_heads; 29261da177e4SLinus Torvalds 29271da177e4SLinus Torvalds int buffer_heads_over_limit; 29281da177e4SLinus Torvalds 29291da177e4SLinus Torvalds struct bh_accounting { 29301da177e4SLinus Torvalds int nr; /* Number of live bh's */ 29311da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 29321da177e4SLinus Torvalds }; 29331da177e4SLinus Torvalds 29341da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 29351da177e4SLinus Torvalds 29361da177e4SLinus Torvalds static void recalc_bh_state(void) 29371da177e4SLinus Torvalds { 29381da177e4SLinus Torvalds int i; 29391da177e4SLinus Torvalds int tot = 0; 29401da177e4SLinus Torvalds 29411da177e4SLinus Torvalds if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) 29421da177e4SLinus Torvalds return; 29431da177e4SLinus Torvalds __get_cpu_var(bh_accounting).ratelimit = 0; 29448a143426SEric Dumazet for_each_online_cpu(i) 29451da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 29461da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 29471da177e4SLinus Torvalds } 29481da177e4SLinus Torvalds 2949dd0fc66fSAl Viro struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) 29501da177e4SLinus Torvalds { 29511da177e4SLinus Torvalds struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags); 29521da177e4SLinus Torvalds if (ret) { 2953736c7b80SCoywolf Qi Hunt get_cpu_var(bh_accounting).nr++; 29541da177e4SLinus Torvalds recalc_bh_state(); 2955736c7b80SCoywolf Qi Hunt put_cpu_var(bh_accounting); 29561da177e4SLinus Torvalds } 29571da177e4SLinus Torvalds return ret; 29581da177e4SLinus Torvalds } 29591da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 29601da177e4SLinus Torvalds 29611da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 29621da177e4SLinus Torvalds { 29631da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 29641da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 2965736c7b80SCoywolf Qi Hunt get_cpu_var(bh_accounting).nr--; 29661da177e4SLinus Torvalds recalc_bh_state(); 2967736c7b80SCoywolf Qi Hunt put_cpu_var(bh_accounting); 29681da177e4SLinus Torvalds } 29691da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 29701da177e4SLinus Torvalds 29711da177e4SLinus Torvalds static void 2972e18b890bSChristoph Lameter init_buffer_head(void *data, struct kmem_cache *cachep, unsigned long flags) 29731da177e4SLinus Torvalds { 29741da177e4SLinus Torvalds if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == 29751da177e4SLinus Torvalds SLAB_CTOR_CONSTRUCTOR) { 29761da177e4SLinus Torvalds struct buffer_head * bh = (struct buffer_head *)data; 29771da177e4SLinus Torvalds 29781da177e4SLinus Torvalds memset(bh, 0, sizeof(*bh)); 29791da177e4SLinus Torvalds INIT_LIST_HEAD(&bh->b_assoc_buffers); 29801da177e4SLinus Torvalds } 29811da177e4SLinus Torvalds } 29821da177e4SLinus Torvalds 29831da177e4SLinus Torvalds static void buffer_exit_cpu(int cpu) 29841da177e4SLinus Torvalds { 29851da177e4SLinus Torvalds int i; 29861da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 29871da177e4SLinus Torvalds 29881da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 29891da177e4SLinus Torvalds brelse(b->bhs[i]); 29901da177e4SLinus Torvalds b->bhs[i] = NULL; 29911da177e4SLinus Torvalds } 29928a143426SEric Dumazet get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr; 29938a143426SEric Dumazet per_cpu(bh_accounting, cpu).nr = 0; 29948a143426SEric Dumazet put_cpu_var(bh_accounting); 29951da177e4SLinus Torvalds } 29961da177e4SLinus Torvalds 29971da177e4SLinus Torvalds static int buffer_cpu_notify(struct notifier_block *self, 29981da177e4SLinus Torvalds unsigned long action, void *hcpu) 29991da177e4SLinus Torvalds { 30001da177e4SLinus Torvalds if (action == CPU_DEAD) 30011da177e4SLinus Torvalds buffer_exit_cpu((unsigned long)hcpu); 30021da177e4SLinus Torvalds return NOTIFY_OK; 30031da177e4SLinus Torvalds } 30041da177e4SLinus Torvalds 30051da177e4SLinus Torvalds void __init buffer_init(void) 30061da177e4SLinus Torvalds { 30071da177e4SLinus Torvalds int nrpages; 30081da177e4SLinus Torvalds 30091da177e4SLinus Torvalds bh_cachep = kmem_cache_create("buffer_head", 30101da177e4SLinus Torvalds sizeof(struct buffer_head), 0, 3011b0196009SPaul Jackson (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| 3012b0196009SPaul Jackson SLAB_MEM_SPREAD), 3013b0196009SPaul Jackson init_buffer_head, 3014b0196009SPaul Jackson NULL); 30151da177e4SLinus Torvalds 30161da177e4SLinus Torvalds /* 30171da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 30181da177e4SLinus Torvalds */ 30191da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 30201da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 30211da177e4SLinus Torvalds hotcpu_notifier(buffer_cpu_notify, 0); 30221da177e4SLinus Torvalds } 30231da177e4SLinus Torvalds 30241da177e4SLinus Torvalds EXPORT_SYMBOL(__bforget); 30251da177e4SLinus Torvalds EXPORT_SYMBOL(__brelse); 30261da177e4SLinus Torvalds EXPORT_SYMBOL(__wait_on_buffer); 30271da177e4SLinus Torvalds EXPORT_SYMBOL(block_commit_write); 30281da177e4SLinus Torvalds EXPORT_SYMBOL(block_prepare_write); 30291da177e4SLinus Torvalds EXPORT_SYMBOL(block_read_full_page); 30301da177e4SLinus Torvalds EXPORT_SYMBOL(block_sync_page); 30311da177e4SLinus Torvalds EXPORT_SYMBOL(block_truncate_page); 30321da177e4SLinus Torvalds EXPORT_SYMBOL(block_write_full_page); 30331da177e4SLinus Torvalds EXPORT_SYMBOL(cont_prepare_write); 30341da177e4SLinus Torvalds EXPORT_SYMBOL(end_buffer_read_sync); 30351da177e4SLinus Torvalds EXPORT_SYMBOL(end_buffer_write_sync); 30361da177e4SLinus Torvalds EXPORT_SYMBOL(file_fsync); 30371da177e4SLinus Torvalds EXPORT_SYMBOL(fsync_bdev); 30381da177e4SLinus Torvalds EXPORT_SYMBOL(generic_block_bmap); 30391da177e4SLinus Torvalds EXPORT_SYMBOL(generic_commit_write); 30401da177e4SLinus Torvalds EXPORT_SYMBOL(generic_cont_expand); 304105eb0b51SOGAWA Hirofumi EXPORT_SYMBOL(generic_cont_expand_simple); 30421da177e4SLinus Torvalds EXPORT_SYMBOL(init_buffer); 30431da177e4SLinus Torvalds EXPORT_SYMBOL(invalidate_bdev); 30441da177e4SLinus Torvalds EXPORT_SYMBOL(ll_rw_block); 30451da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty); 30461da177e4SLinus Torvalds EXPORT_SYMBOL(submit_bh); 30471da177e4SLinus Torvalds EXPORT_SYMBOL(sync_dirty_buffer); 30481da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_buffer); 3049