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/config.h> 221da177e4SLinus Torvalds #include <linux/kernel.h> 231da177e4SLinus Torvalds #include <linux/syscalls.h> 241da177e4SLinus Torvalds #include <linux/fs.h> 251da177e4SLinus Torvalds #include <linux/mm.h> 261da177e4SLinus Torvalds #include <linux/percpu.h> 271da177e4SLinus Torvalds #include <linux/slab.h> 281da177e4SLinus Torvalds #include <linux/smp_lock.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> 381da177e4SLinus Torvalds #include <linux/bio.h> 391da177e4SLinus Torvalds #include <linux/notifier.h> 401da177e4SLinus Torvalds #include <linux/cpu.h> 411da177e4SLinus Torvalds #include <linux/bitops.h> 421da177e4SLinus Torvalds #include <linux/mpage.h> 431da177e4SLinus Torvalds 441da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); 451da177e4SLinus Torvalds static void invalidate_bh_lrus(void); 461da177e4SLinus Torvalds 471da177e4SLinus Torvalds #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) 481da177e4SLinus Torvalds 491da177e4SLinus Torvalds inline void 501da177e4SLinus Torvalds init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) 511da177e4SLinus Torvalds { 521da177e4SLinus Torvalds bh->b_end_io = handler; 531da177e4SLinus Torvalds bh->b_private = private; 541da177e4SLinus Torvalds } 551da177e4SLinus Torvalds 561da177e4SLinus Torvalds static int sync_buffer(void *word) 571da177e4SLinus Torvalds { 581da177e4SLinus Torvalds struct block_device *bd; 591da177e4SLinus Torvalds struct buffer_head *bh 601da177e4SLinus Torvalds = container_of(word, struct buffer_head, b_state); 611da177e4SLinus Torvalds 621da177e4SLinus Torvalds smp_mb(); 631da177e4SLinus Torvalds bd = bh->b_bdev; 641da177e4SLinus Torvalds if (bd) 651da177e4SLinus Torvalds blk_run_address_space(bd->bd_inode->i_mapping); 661da177e4SLinus Torvalds io_schedule(); 671da177e4SLinus Torvalds return 0; 681da177e4SLinus Torvalds } 691da177e4SLinus Torvalds 701da177e4SLinus Torvalds void fastcall __lock_buffer(struct buffer_head *bh) 711da177e4SLinus Torvalds { 721da177e4SLinus Torvalds wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer, 731da177e4SLinus Torvalds TASK_UNINTERRUPTIBLE); 741da177e4SLinus Torvalds } 751da177e4SLinus Torvalds EXPORT_SYMBOL(__lock_buffer); 761da177e4SLinus Torvalds 771da177e4SLinus Torvalds void fastcall unlock_buffer(struct buffer_head *bh) 781da177e4SLinus Torvalds { 791da177e4SLinus Torvalds clear_buffer_locked(bh); 801da177e4SLinus Torvalds smp_mb__after_clear_bit(); 811da177e4SLinus Torvalds wake_up_bit(&bh->b_state, BH_Lock); 821da177e4SLinus Torvalds } 831da177e4SLinus Torvalds 841da177e4SLinus Torvalds /* 851da177e4SLinus Torvalds * Block until a buffer comes unlocked. This doesn't stop it 861da177e4SLinus Torvalds * from becoming locked again - you have to lock it yourself 871da177e4SLinus Torvalds * if you want to preserve its state. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds void __wait_on_buffer(struct buffer_head * bh) 901da177e4SLinus Torvalds { 911da177e4SLinus Torvalds wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE); 921da177e4SLinus Torvalds } 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds static void 951da177e4SLinus Torvalds __clear_page_buffers(struct page *page) 961da177e4SLinus Torvalds { 971da177e4SLinus Torvalds ClearPagePrivate(page); 981da177e4SLinus Torvalds page->private = 0; 991da177e4SLinus Torvalds page_cache_release(page); 1001da177e4SLinus Torvalds } 1011da177e4SLinus Torvalds 1021da177e4SLinus Torvalds static void buffer_io_error(struct buffer_head *bh) 1031da177e4SLinus Torvalds { 1041da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 1051da177e4SLinus Torvalds 1061da177e4SLinus Torvalds printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", 1071da177e4SLinus Torvalds bdevname(bh->b_bdev, b), 1081da177e4SLinus Torvalds (unsigned long long)bh->b_blocknr); 1091da177e4SLinus Torvalds } 1101da177e4SLinus Torvalds 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * Default synchronous end-of-IO handler.. Just mark it up-to-date and 1131da177e4SLinus Torvalds * unlock the buffer. This is what ll_rw_block uses too. 1141da177e4SLinus Torvalds */ 1151da177e4SLinus Torvalds void end_buffer_read_sync(struct buffer_head *bh, int uptodate) 1161da177e4SLinus Torvalds { 1171da177e4SLinus Torvalds if (uptodate) { 1181da177e4SLinus Torvalds set_buffer_uptodate(bh); 1191da177e4SLinus Torvalds } else { 1201da177e4SLinus Torvalds /* This happens, due to failed READA attempts. */ 1211da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1221da177e4SLinus Torvalds } 1231da177e4SLinus Torvalds unlock_buffer(bh); 1241da177e4SLinus Torvalds put_bh(bh); 1251da177e4SLinus Torvalds } 1261da177e4SLinus Torvalds 1271da177e4SLinus Torvalds void end_buffer_write_sync(struct buffer_head *bh, int uptodate) 1281da177e4SLinus Torvalds { 1291da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 1301da177e4SLinus Torvalds 1311da177e4SLinus Torvalds if (uptodate) { 1321da177e4SLinus Torvalds set_buffer_uptodate(bh); 1331da177e4SLinus Torvalds } else { 1341da177e4SLinus Torvalds if (!buffer_eopnotsupp(bh) && printk_ratelimit()) { 1351da177e4SLinus Torvalds buffer_io_error(bh); 1361da177e4SLinus Torvalds printk(KERN_WARNING "lost page write due to " 1371da177e4SLinus Torvalds "I/O error on %s\n", 1381da177e4SLinus Torvalds bdevname(bh->b_bdev, b)); 1391da177e4SLinus Torvalds } 1401da177e4SLinus Torvalds set_buffer_write_io_error(bh); 1411da177e4SLinus Torvalds clear_buffer_uptodate(bh); 1421da177e4SLinus Torvalds } 1431da177e4SLinus Torvalds unlock_buffer(bh); 1441da177e4SLinus Torvalds put_bh(bh); 1451da177e4SLinus Torvalds } 1461da177e4SLinus Torvalds 1471da177e4SLinus Torvalds /* 1481da177e4SLinus Torvalds * Write out and wait upon all the dirty data associated with a block 1491da177e4SLinus Torvalds * device via its mapping. Does not take the superblock lock. 1501da177e4SLinus Torvalds */ 1511da177e4SLinus Torvalds int sync_blockdev(struct block_device *bdev) 1521da177e4SLinus Torvalds { 1531da177e4SLinus Torvalds int ret = 0; 1541da177e4SLinus Torvalds 1551da177e4SLinus Torvalds if (bdev) { 1561da177e4SLinus Torvalds int err; 1571da177e4SLinus Torvalds 1581da177e4SLinus Torvalds ret = filemap_fdatawrite(bdev->bd_inode->i_mapping); 1591da177e4SLinus Torvalds err = filemap_fdatawait(bdev->bd_inode->i_mapping); 1601da177e4SLinus Torvalds if (!ret) 1611da177e4SLinus Torvalds ret = err; 1621da177e4SLinus Torvalds } 1631da177e4SLinus Torvalds return ret; 1641da177e4SLinus Torvalds } 1651da177e4SLinus Torvalds EXPORT_SYMBOL(sync_blockdev); 1661da177e4SLinus Torvalds 1671da177e4SLinus Torvalds /* 1681da177e4SLinus Torvalds * Write out and wait upon all dirty data associated with this 1691da177e4SLinus Torvalds * superblock. Filesystem data as well as the underlying block 1701da177e4SLinus Torvalds * device. Takes the superblock lock. 1711da177e4SLinus Torvalds */ 1721da177e4SLinus Torvalds int fsync_super(struct super_block *sb) 1731da177e4SLinus Torvalds { 1741da177e4SLinus Torvalds sync_inodes_sb(sb, 0); 1751da177e4SLinus Torvalds DQUOT_SYNC(sb); 1761da177e4SLinus Torvalds lock_super(sb); 1771da177e4SLinus Torvalds if (sb->s_dirt && sb->s_op->write_super) 1781da177e4SLinus Torvalds sb->s_op->write_super(sb); 1791da177e4SLinus Torvalds unlock_super(sb); 1801da177e4SLinus Torvalds if (sb->s_op->sync_fs) 1811da177e4SLinus Torvalds sb->s_op->sync_fs(sb, 1); 1821da177e4SLinus Torvalds sync_blockdev(sb->s_bdev); 1831da177e4SLinus Torvalds sync_inodes_sb(sb, 1); 1841da177e4SLinus Torvalds 1851da177e4SLinus Torvalds return sync_blockdev(sb->s_bdev); 1861da177e4SLinus Torvalds } 1871da177e4SLinus Torvalds 1881da177e4SLinus Torvalds /* 1891da177e4SLinus Torvalds * Write out and wait upon all dirty data associated with this 1901da177e4SLinus Torvalds * device. Filesystem data as well as the underlying block 1911da177e4SLinus Torvalds * device. Takes the superblock lock. 1921da177e4SLinus Torvalds */ 1931da177e4SLinus Torvalds int fsync_bdev(struct block_device *bdev) 1941da177e4SLinus Torvalds { 1951da177e4SLinus Torvalds struct super_block *sb = get_super(bdev); 1961da177e4SLinus Torvalds if (sb) { 1971da177e4SLinus Torvalds int res = fsync_super(sb); 1981da177e4SLinus Torvalds drop_super(sb); 1991da177e4SLinus Torvalds return res; 2001da177e4SLinus Torvalds } 2011da177e4SLinus Torvalds return sync_blockdev(bdev); 2021da177e4SLinus Torvalds } 2031da177e4SLinus Torvalds 2041da177e4SLinus Torvalds /** 2051da177e4SLinus Torvalds * freeze_bdev -- lock a filesystem and force it into a consistent state 2061da177e4SLinus Torvalds * @bdev: blockdevice to lock 2071da177e4SLinus Torvalds * 2081da177e4SLinus Torvalds * This takes the block device bd_mount_sem to make sure no new mounts 2091da177e4SLinus Torvalds * happen on bdev until thaw_bdev() is called. 2101da177e4SLinus Torvalds * If a superblock is found on this device, we take the s_umount semaphore 2111da177e4SLinus Torvalds * on it to make sure nobody unmounts until the snapshot creation is done. 2121da177e4SLinus Torvalds */ 2131da177e4SLinus Torvalds struct super_block *freeze_bdev(struct block_device *bdev) 2141da177e4SLinus Torvalds { 2151da177e4SLinus Torvalds struct super_block *sb; 2161da177e4SLinus Torvalds 2171da177e4SLinus Torvalds down(&bdev->bd_mount_sem); 2181da177e4SLinus Torvalds sb = get_super(bdev); 2191da177e4SLinus Torvalds if (sb && !(sb->s_flags & MS_RDONLY)) { 2201da177e4SLinus Torvalds sb->s_frozen = SB_FREEZE_WRITE; 221d59dd462Sakpm@osdl.org smp_wmb(); 2221da177e4SLinus Torvalds 2231da177e4SLinus Torvalds sync_inodes_sb(sb, 0); 2241da177e4SLinus Torvalds DQUOT_SYNC(sb); 2251da177e4SLinus Torvalds 2261da177e4SLinus Torvalds lock_super(sb); 2271da177e4SLinus Torvalds if (sb->s_dirt && sb->s_op->write_super) 2281da177e4SLinus Torvalds sb->s_op->write_super(sb); 2291da177e4SLinus Torvalds unlock_super(sb); 2301da177e4SLinus Torvalds 2311da177e4SLinus Torvalds if (sb->s_op->sync_fs) 2321da177e4SLinus Torvalds sb->s_op->sync_fs(sb, 1); 2331da177e4SLinus Torvalds 2341da177e4SLinus Torvalds sync_blockdev(sb->s_bdev); 2351da177e4SLinus Torvalds sync_inodes_sb(sb, 1); 2361da177e4SLinus Torvalds 2371da177e4SLinus Torvalds sb->s_frozen = SB_FREEZE_TRANS; 238d59dd462Sakpm@osdl.org smp_wmb(); 2391da177e4SLinus Torvalds 2401da177e4SLinus Torvalds sync_blockdev(sb->s_bdev); 2411da177e4SLinus Torvalds 2421da177e4SLinus Torvalds if (sb->s_op->write_super_lockfs) 2431da177e4SLinus Torvalds sb->s_op->write_super_lockfs(sb); 2441da177e4SLinus Torvalds } 2451da177e4SLinus Torvalds 2461da177e4SLinus Torvalds sync_blockdev(bdev); 2471da177e4SLinus Torvalds return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */ 2481da177e4SLinus Torvalds } 2491da177e4SLinus Torvalds EXPORT_SYMBOL(freeze_bdev); 2501da177e4SLinus Torvalds 2511da177e4SLinus Torvalds /** 2521da177e4SLinus Torvalds * thaw_bdev -- unlock filesystem 2531da177e4SLinus Torvalds * @bdev: blockdevice to unlock 2541da177e4SLinus Torvalds * @sb: associated superblock 2551da177e4SLinus Torvalds * 2561da177e4SLinus Torvalds * Unlocks the filesystem and marks it writeable again after freeze_bdev(). 2571da177e4SLinus Torvalds */ 2581da177e4SLinus Torvalds void thaw_bdev(struct block_device *bdev, struct super_block *sb) 2591da177e4SLinus Torvalds { 2601da177e4SLinus Torvalds if (sb) { 2611da177e4SLinus Torvalds BUG_ON(sb->s_bdev != bdev); 2621da177e4SLinus Torvalds 2631da177e4SLinus Torvalds if (sb->s_op->unlockfs) 2641da177e4SLinus Torvalds sb->s_op->unlockfs(sb); 2651da177e4SLinus Torvalds sb->s_frozen = SB_UNFROZEN; 266d59dd462Sakpm@osdl.org smp_wmb(); 2671da177e4SLinus Torvalds wake_up(&sb->s_wait_unfrozen); 2681da177e4SLinus Torvalds drop_super(sb); 2691da177e4SLinus Torvalds } 2701da177e4SLinus Torvalds 2711da177e4SLinus Torvalds up(&bdev->bd_mount_sem); 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds EXPORT_SYMBOL(thaw_bdev); 2741da177e4SLinus Torvalds 2751da177e4SLinus Torvalds /* 2761da177e4SLinus Torvalds * sync everything. Start out by waking pdflush, because that writes back 2771da177e4SLinus Torvalds * all queues in parallel. 2781da177e4SLinus Torvalds */ 2791da177e4SLinus Torvalds static void do_sync(unsigned long wait) 2801da177e4SLinus Torvalds { 281*687a21ceSPekka J Enberg wakeup_pdflush(0); 2821da177e4SLinus Torvalds sync_inodes(0); /* All mappings, inodes and their blockdevs */ 2831da177e4SLinus Torvalds DQUOT_SYNC(NULL); 2841da177e4SLinus Torvalds sync_supers(); /* Write the superblocks */ 2851da177e4SLinus Torvalds sync_filesystems(0); /* Start syncing the filesystems */ 2861da177e4SLinus Torvalds sync_filesystems(wait); /* Waitingly sync the filesystems */ 2871da177e4SLinus Torvalds sync_inodes(wait); /* Mappings, inodes and blockdevs, again. */ 2881da177e4SLinus Torvalds if (!wait) 2891da177e4SLinus Torvalds printk("Emergency Sync complete\n"); 2901da177e4SLinus Torvalds if (unlikely(laptop_mode)) 2911da177e4SLinus Torvalds laptop_sync_completion(); 2921da177e4SLinus Torvalds } 2931da177e4SLinus Torvalds 2941da177e4SLinus Torvalds asmlinkage long sys_sync(void) 2951da177e4SLinus Torvalds { 2961da177e4SLinus Torvalds do_sync(1); 2971da177e4SLinus Torvalds return 0; 2981da177e4SLinus Torvalds } 2991da177e4SLinus Torvalds 3001da177e4SLinus Torvalds void emergency_sync(void) 3011da177e4SLinus Torvalds { 3021da177e4SLinus Torvalds pdflush_operation(do_sync, 0); 3031da177e4SLinus Torvalds } 3041da177e4SLinus Torvalds 3051da177e4SLinus Torvalds /* 3061da177e4SLinus Torvalds * Generic function to fsync a file. 3071da177e4SLinus Torvalds * 3081da177e4SLinus Torvalds * filp may be NULL if called via the msync of a vma. 3091da177e4SLinus Torvalds */ 3101da177e4SLinus Torvalds 3111da177e4SLinus Torvalds int file_fsync(struct file *filp, struct dentry *dentry, int datasync) 3121da177e4SLinus Torvalds { 3131da177e4SLinus Torvalds struct inode * inode = dentry->d_inode; 3141da177e4SLinus Torvalds struct super_block * sb; 3151da177e4SLinus Torvalds int ret, err; 3161da177e4SLinus Torvalds 3171da177e4SLinus Torvalds /* sync the inode to buffers */ 3181da177e4SLinus Torvalds ret = write_inode_now(inode, 0); 3191da177e4SLinus Torvalds 3201da177e4SLinus Torvalds /* sync the superblock to buffers */ 3211da177e4SLinus Torvalds sb = inode->i_sb; 3221da177e4SLinus Torvalds lock_super(sb); 3231da177e4SLinus Torvalds if (sb->s_op->write_super) 3241da177e4SLinus Torvalds sb->s_op->write_super(sb); 3251da177e4SLinus Torvalds unlock_super(sb); 3261da177e4SLinus Torvalds 3271da177e4SLinus Torvalds /* .. finally sync the buffers to disk */ 3281da177e4SLinus Torvalds err = sync_blockdev(sb->s_bdev); 3291da177e4SLinus Torvalds if (!ret) 3301da177e4SLinus Torvalds ret = err; 3311da177e4SLinus Torvalds return ret; 3321da177e4SLinus Torvalds } 3331da177e4SLinus Torvalds 334dfb388bfSOleg Nesterov static long do_fsync(unsigned int fd, int datasync) 3351da177e4SLinus Torvalds { 3361da177e4SLinus Torvalds struct file * file; 3371da177e4SLinus Torvalds struct address_space *mapping; 3381da177e4SLinus Torvalds int ret, err; 3391da177e4SLinus Torvalds 3401da177e4SLinus Torvalds ret = -EBADF; 3411da177e4SLinus Torvalds file = fget(fd); 3421da177e4SLinus Torvalds if (!file) 3431da177e4SLinus Torvalds goto out; 3441da177e4SLinus Torvalds 3451da177e4SLinus Torvalds ret = -EINVAL; 3461da177e4SLinus Torvalds if (!file->f_op || !file->f_op->fsync) { 3471da177e4SLinus Torvalds /* Why? We can still call filemap_fdatawrite */ 3481da177e4SLinus Torvalds goto out_putf; 3491da177e4SLinus Torvalds } 3501da177e4SLinus Torvalds 351dfb388bfSOleg Nesterov mapping = file->f_mapping; 352dfb388bfSOleg Nesterov 3531da177e4SLinus Torvalds current->flags |= PF_SYNCWRITE; 3541da177e4SLinus Torvalds ret = filemap_fdatawrite(mapping); 3551da177e4SLinus Torvalds 3561da177e4SLinus Torvalds /* 3571da177e4SLinus Torvalds * We need to protect against concurrent writers, 3581da177e4SLinus Torvalds * which could cause livelocks in fsync_buffers_list 3591da177e4SLinus Torvalds */ 3601da177e4SLinus Torvalds down(&mapping->host->i_sem); 361dfb388bfSOleg Nesterov err = file->f_op->fsync(file, file->f_dentry, datasync); 3621da177e4SLinus Torvalds if (!ret) 3631da177e4SLinus Torvalds ret = err; 3641da177e4SLinus Torvalds up(&mapping->host->i_sem); 3651da177e4SLinus Torvalds err = filemap_fdatawait(mapping); 3661da177e4SLinus Torvalds if (!ret) 3671da177e4SLinus Torvalds ret = err; 3681da177e4SLinus Torvalds current->flags &= ~PF_SYNCWRITE; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds out_putf: 3711da177e4SLinus Torvalds fput(file); 3721da177e4SLinus Torvalds out: 3731da177e4SLinus Torvalds return ret; 3741da177e4SLinus Torvalds } 3751da177e4SLinus Torvalds 376dfb388bfSOleg Nesterov asmlinkage long sys_fsync(unsigned int fd) 377dfb388bfSOleg Nesterov { 378dfb388bfSOleg Nesterov return do_fsync(fd, 0); 379dfb388bfSOleg Nesterov } 380dfb388bfSOleg Nesterov 3811da177e4SLinus Torvalds asmlinkage long sys_fdatasync(unsigned int fd) 3821da177e4SLinus Torvalds { 383dfb388bfSOleg Nesterov return do_fsync(fd, 1); 3841da177e4SLinus Torvalds } 3851da177e4SLinus Torvalds 3861da177e4SLinus Torvalds /* 3871da177e4SLinus Torvalds * Various filesystems appear to want __find_get_block to be non-blocking. 3881da177e4SLinus Torvalds * But it's the page lock which protects the buffers. To get around this, 3891da177e4SLinus Torvalds * we get exclusion from try_to_free_buffers with the blockdev mapping's 3901da177e4SLinus Torvalds * private_lock. 3911da177e4SLinus Torvalds * 3921da177e4SLinus Torvalds * Hack idea: for the blockdev mapping, i_bufferlist_lock contention 3931da177e4SLinus Torvalds * may be quite high. This code could TryLock the page, and if that 3941da177e4SLinus Torvalds * succeeds, there is no need to take private_lock. (But if 3951da177e4SLinus Torvalds * private_lock is contended then so is mapping->tree_lock). 3961da177e4SLinus Torvalds */ 3971da177e4SLinus Torvalds static struct buffer_head * 3981da177e4SLinus Torvalds __find_get_block_slow(struct block_device *bdev, sector_t block, int unused) 3991da177e4SLinus Torvalds { 4001da177e4SLinus Torvalds struct inode *bd_inode = bdev->bd_inode; 4011da177e4SLinus Torvalds struct address_space *bd_mapping = bd_inode->i_mapping; 4021da177e4SLinus Torvalds struct buffer_head *ret = NULL; 4031da177e4SLinus Torvalds pgoff_t index; 4041da177e4SLinus Torvalds struct buffer_head *bh; 4051da177e4SLinus Torvalds struct buffer_head *head; 4061da177e4SLinus Torvalds struct page *page; 4071da177e4SLinus Torvalds int all_mapped = 1; 4081da177e4SLinus Torvalds 4091da177e4SLinus Torvalds index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); 4101da177e4SLinus Torvalds page = find_get_page(bd_mapping, index); 4111da177e4SLinus Torvalds if (!page) 4121da177e4SLinus Torvalds goto out; 4131da177e4SLinus Torvalds 4141da177e4SLinus Torvalds spin_lock(&bd_mapping->private_lock); 4151da177e4SLinus Torvalds if (!page_has_buffers(page)) 4161da177e4SLinus Torvalds goto out_unlock; 4171da177e4SLinus Torvalds head = page_buffers(page); 4181da177e4SLinus Torvalds bh = head; 4191da177e4SLinus Torvalds do { 4201da177e4SLinus Torvalds if (bh->b_blocknr == block) { 4211da177e4SLinus Torvalds ret = bh; 4221da177e4SLinus Torvalds get_bh(bh); 4231da177e4SLinus Torvalds goto out_unlock; 4241da177e4SLinus Torvalds } 4251da177e4SLinus Torvalds if (!buffer_mapped(bh)) 4261da177e4SLinus Torvalds all_mapped = 0; 4271da177e4SLinus Torvalds bh = bh->b_this_page; 4281da177e4SLinus Torvalds } while (bh != head); 4291da177e4SLinus Torvalds 4301da177e4SLinus Torvalds /* we might be here because some of the buffers on this page are 4311da177e4SLinus Torvalds * not mapped. This is due to various races between 4321da177e4SLinus Torvalds * file io on the block device and getblk. It gets dealt with 4331da177e4SLinus Torvalds * elsewhere, don't buffer_error if we had some unmapped buffers 4341da177e4SLinus Torvalds */ 4351da177e4SLinus Torvalds if (all_mapped) { 4361da177e4SLinus Torvalds printk("__find_get_block_slow() failed. " 4371da177e4SLinus Torvalds "block=%llu, b_blocknr=%llu\n", 4381da177e4SLinus Torvalds (unsigned long long)block, (unsigned long long)bh->b_blocknr); 4391da177e4SLinus Torvalds printk("b_state=0x%08lx, b_size=%u\n", bh->b_state, bh->b_size); 4401da177e4SLinus Torvalds printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); 4411da177e4SLinus Torvalds } 4421da177e4SLinus Torvalds out_unlock: 4431da177e4SLinus Torvalds spin_unlock(&bd_mapping->private_lock); 4441da177e4SLinus Torvalds page_cache_release(page); 4451da177e4SLinus Torvalds out: 4461da177e4SLinus Torvalds return ret; 4471da177e4SLinus Torvalds } 4481da177e4SLinus Torvalds 4491da177e4SLinus Torvalds /* If invalidate_buffers() will trash dirty buffers, it means some kind 4501da177e4SLinus Torvalds of fs corruption is going on. Trashing dirty data always imply losing 4511da177e4SLinus Torvalds information that was supposed to be just stored on the physical layer 4521da177e4SLinus Torvalds by the user. 4531da177e4SLinus Torvalds 4541da177e4SLinus Torvalds Thus invalidate_buffers in general usage is not allwowed to trash 4551da177e4SLinus Torvalds dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to 4561da177e4SLinus Torvalds be preserved. These buffers are simply skipped. 4571da177e4SLinus Torvalds 4581da177e4SLinus Torvalds We also skip buffers which are still in use. For example this can 4591da177e4SLinus Torvalds happen if a userspace program is reading the block device. 4601da177e4SLinus Torvalds 4611da177e4SLinus Torvalds NOTE: In the case where the user removed a removable-media-disk even if 4621da177e4SLinus Torvalds there's still dirty data not synced on disk (due a bug in the device driver 4631da177e4SLinus Torvalds or due an error of the user), by not destroying the dirty buffers we could 4641da177e4SLinus Torvalds generate corruption also on the next media inserted, thus a parameter is 4651da177e4SLinus Torvalds necessary to handle this case in the most safe way possible (trying 4661da177e4SLinus Torvalds to not corrupt also the new disk inserted with the data belonging to 4671da177e4SLinus Torvalds the old now corrupted disk). Also for the ramdisk the natural thing 4681da177e4SLinus Torvalds to do in order to release the ramdisk memory is to destroy dirty buffers. 4691da177e4SLinus Torvalds 4701da177e4SLinus Torvalds These are two special cases. Normal usage imply the device driver 4711da177e4SLinus Torvalds to issue a sync on the device (without waiting I/O completion) and 4721da177e4SLinus Torvalds then an invalidate_buffers call that doesn't trash dirty buffers. 4731da177e4SLinus Torvalds 4741da177e4SLinus Torvalds For handling cache coherency with the blkdev pagecache the 'update' case 4751da177e4SLinus Torvalds is been introduced. It is needed to re-read from disk any pinned 4761da177e4SLinus Torvalds buffer. NOTE: re-reading from disk is destructive so we can do it only 4771da177e4SLinus Torvalds when we assume nobody is changing the buffercache under our I/O and when 4781da177e4SLinus Torvalds we think the disk contains more recent information than the buffercache. 4791da177e4SLinus Torvalds The update == 1 pass marks the buffers we need to update, the update == 2 4801da177e4SLinus Torvalds pass does the actual I/O. */ 4811da177e4SLinus Torvalds void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers) 4821da177e4SLinus Torvalds { 4831da177e4SLinus Torvalds invalidate_bh_lrus(); 4841da177e4SLinus Torvalds /* 4851da177e4SLinus Torvalds * FIXME: what about destroy_dirty_buffers? 4861da177e4SLinus Torvalds * We really want to use invalidate_inode_pages2() for 4871da177e4SLinus Torvalds * that, but not until that's cleaned up. 4881da177e4SLinus Torvalds */ 4891da177e4SLinus Torvalds invalidate_inode_pages(bdev->bd_inode->i_mapping); 4901da177e4SLinus Torvalds } 4911da177e4SLinus Torvalds 4921da177e4SLinus Torvalds /* 4931da177e4SLinus Torvalds * Kick pdflush then try to free up some ZONE_NORMAL memory. 4941da177e4SLinus Torvalds */ 4951da177e4SLinus Torvalds static void free_more_memory(void) 4961da177e4SLinus Torvalds { 4971da177e4SLinus Torvalds struct zone **zones; 4981da177e4SLinus Torvalds pg_data_t *pgdat; 4991da177e4SLinus Torvalds 500*687a21ceSPekka J Enberg wakeup_pdflush(1024); 5011da177e4SLinus Torvalds yield(); 5021da177e4SLinus Torvalds 5031da177e4SLinus Torvalds for_each_pgdat(pgdat) { 5041da177e4SLinus Torvalds zones = pgdat->node_zonelists[GFP_NOFS&GFP_ZONEMASK].zones; 5051da177e4SLinus Torvalds if (*zones) 5061ad539b2SDarren Hart try_to_free_pages(zones, GFP_NOFS); 5071da177e4SLinus Torvalds } 5081da177e4SLinus Torvalds } 5091da177e4SLinus Torvalds 5101da177e4SLinus Torvalds /* 5111da177e4SLinus Torvalds * I/O completion handler for block_read_full_page() - pages 5121da177e4SLinus Torvalds * which come unlocked at the end of I/O. 5131da177e4SLinus Torvalds */ 5141da177e4SLinus Torvalds static void end_buffer_async_read(struct buffer_head *bh, int uptodate) 5151da177e4SLinus Torvalds { 5161da177e4SLinus Torvalds static DEFINE_SPINLOCK(page_uptodate_lock); 5171da177e4SLinus Torvalds unsigned long flags; 5181da177e4SLinus Torvalds struct buffer_head *tmp; 5191da177e4SLinus Torvalds struct page *page; 5201da177e4SLinus Torvalds int page_uptodate = 1; 5211da177e4SLinus Torvalds 5221da177e4SLinus Torvalds BUG_ON(!buffer_async_read(bh)); 5231da177e4SLinus Torvalds 5241da177e4SLinus Torvalds page = bh->b_page; 5251da177e4SLinus Torvalds if (uptodate) { 5261da177e4SLinus Torvalds set_buffer_uptodate(bh); 5271da177e4SLinus Torvalds } else { 5281da177e4SLinus Torvalds clear_buffer_uptodate(bh); 5291da177e4SLinus Torvalds if (printk_ratelimit()) 5301da177e4SLinus Torvalds buffer_io_error(bh); 5311da177e4SLinus Torvalds SetPageError(page); 5321da177e4SLinus Torvalds } 5331da177e4SLinus Torvalds 5341da177e4SLinus Torvalds /* 5351da177e4SLinus Torvalds * Be _very_ careful from here on. Bad things can happen if 5361da177e4SLinus Torvalds * two buffer heads end IO at almost the same time and both 5371da177e4SLinus Torvalds * decide that the page is now completely done. 5381da177e4SLinus Torvalds */ 5391da177e4SLinus Torvalds spin_lock_irqsave(&page_uptodate_lock, flags); 5401da177e4SLinus Torvalds clear_buffer_async_read(bh); 5411da177e4SLinus Torvalds unlock_buffer(bh); 5421da177e4SLinus Torvalds tmp = bh; 5431da177e4SLinus Torvalds do { 5441da177e4SLinus Torvalds if (!buffer_uptodate(tmp)) 5451da177e4SLinus Torvalds page_uptodate = 0; 5461da177e4SLinus Torvalds if (buffer_async_read(tmp)) { 5471da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 5481da177e4SLinus Torvalds goto still_busy; 5491da177e4SLinus Torvalds } 5501da177e4SLinus Torvalds tmp = tmp->b_this_page; 5511da177e4SLinus Torvalds } while (tmp != bh); 5521da177e4SLinus Torvalds spin_unlock_irqrestore(&page_uptodate_lock, flags); 5531da177e4SLinus Torvalds 5541da177e4SLinus Torvalds /* 5551da177e4SLinus Torvalds * If none of the buffers had errors and they are all 5561da177e4SLinus Torvalds * uptodate then we can set the page uptodate. 5571da177e4SLinus Torvalds */ 5581da177e4SLinus Torvalds if (page_uptodate && !PageError(page)) 5591da177e4SLinus Torvalds SetPageUptodate(page); 5601da177e4SLinus Torvalds unlock_page(page); 5611da177e4SLinus Torvalds return; 5621da177e4SLinus Torvalds 5631da177e4SLinus Torvalds still_busy: 5641da177e4SLinus Torvalds spin_unlock_irqrestore(&page_uptodate_lock, flags); 5651da177e4SLinus Torvalds return; 5661da177e4SLinus Torvalds } 5671da177e4SLinus Torvalds 5681da177e4SLinus Torvalds /* 5691da177e4SLinus Torvalds * Completion handler for block_write_full_page() - pages which are unlocked 5701da177e4SLinus Torvalds * during I/O, and which have PageWriteback cleared upon I/O completion. 5711da177e4SLinus Torvalds */ 5721da177e4SLinus Torvalds void end_buffer_async_write(struct buffer_head *bh, int uptodate) 5731da177e4SLinus Torvalds { 5741da177e4SLinus Torvalds char b[BDEVNAME_SIZE]; 5751da177e4SLinus Torvalds static DEFINE_SPINLOCK(page_uptodate_lock); 5761da177e4SLinus Torvalds unsigned long flags; 5771da177e4SLinus Torvalds struct buffer_head *tmp; 5781da177e4SLinus Torvalds struct page *page; 5791da177e4SLinus Torvalds 5801da177e4SLinus Torvalds BUG_ON(!buffer_async_write(bh)); 5811da177e4SLinus Torvalds 5821da177e4SLinus Torvalds page = bh->b_page; 5831da177e4SLinus Torvalds if (uptodate) { 5841da177e4SLinus Torvalds set_buffer_uptodate(bh); 5851da177e4SLinus Torvalds } else { 5861da177e4SLinus Torvalds if (printk_ratelimit()) { 5871da177e4SLinus Torvalds buffer_io_error(bh); 5881da177e4SLinus Torvalds printk(KERN_WARNING "lost page write due to " 5891da177e4SLinus Torvalds "I/O error on %s\n", 5901da177e4SLinus Torvalds bdevname(bh->b_bdev, b)); 5911da177e4SLinus Torvalds } 5921da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 5931da177e4SLinus Torvalds clear_buffer_uptodate(bh); 5941da177e4SLinus Torvalds SetPageError(page); 5951da177e4SLinus Torvalds } 5961da177e4SLinus Torvalds 5971da177e4SLinus Torvalds spin_lock_irqsave(&page_uptodate_lock, flags); 5981da177e4SLinus Torvalds clear_buffer_async_write(bh); 5991da177e4SLinus Torvalds unlock_buffer(bh); 6001da177e4SLinus Torvalds tmp = bh->b_this_page; 6011da177e4SLinus Torvalds while (tmp != bh) { 6021da177e4SLinus Torvalds if (buffer_async_write(tmp)) { 6031da177e4SLinus Torvalds BUG_ON(!buffer_locked(tmp)); 6041da177e4SLinus Torvalds goto still_busy; 6051da177e4SLinus Torvalds } 6061da177e4SLinus Torvalds tmp = tmp->b_this_page; 6071da177e4SLinus Torvalds } 6081da177e4SLinus Torvalds spin_unlock_irqrestore(&page_uptodate_lock, flags); 6091da177e4SLinus Torvalds end_page_writeback(page); 6101da177e4SLinus Torvalds return; 6111da177e4SLinus Torvalds 6121da177e4SLinus Torvalds still_busy: 6131da177e4SLinus Torvalds spin_unlock_irqrestore(&page_uptodate_lock, flags); 6141da177e4SLinus Torvalds return; 6151da177e4SLinus Torvalds } 6161da177e4SLinus Torvalds 6171da177e4SLinus Torvalds /* 6181da177e4SLinus Torvalds * If a page's buffers are under async readin (end_buffer_async_read 6191da177e4SLinus Torvalds * completion) then there is a possibility that another thread of 6201da177e4SLinus Torvalds * control could lock one of the buffers after it has completed 6211da177e4SLinus Torvalds * but while some of the other buffers have not completed. This 6221da177e4SLinus Torvalds * locked buffer would confuse end_buffer_async_read() into not unlocking 6231da177e4SLinus Torvalds * the page. So the absence of BH_Async_Read tells end_buffer_async_read() 6241da177e4SLinus Torvalds * that this buffer is not under async I/O. 6251da177e4SLinus Torvalds * 6261da177e4SLinus Torvalds * The page comes unlocked when it has no locked buffer_async buffers 6271da177e4SLinus Torvalds * left. 6281da177e4SLinus Torvalds * 6291da177e4SLinus Torvalds * PageLocked prevents anyone starting new async I/O reads any of 6301da177e4SLinus Torvalds * the buffers. 6311da177e4SLinus Torvalds * 6321da177e4SLinus Torvalds * PageWriteback is used to prevent simultaneous writeout of the same 6331da177e4SLinus Torvalds * page. 6341da177e4SLinus Torvalds * 6351da177e4SLinus Torvalds * PageLocked prevents anyone from starting writeback of a page which is 6361da177e4SLinus Torvalds * under read I/O (PageWriteback is only ever set against a locked page). 6371da177e4SLinus Torvalds */ 6381da177e4SLinus Torvalds static void mark_buffer_async_read(struct buffer_head *bh) 6391da177e4SLinus Torvalds { 6401da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_read; 6411da177e4SLinus Torvalds set_buffer_async_read(bh); 6421da177e4SLinus Torvalds } 6431da177e4SLinus Torvalds 6441da177e4SLinus Torvalds void mark_buffer_async_write(struct buffer_head *bh) 6451da177e4SLinus Torvalds { 6461da177e4SLinus Torvalds bh->b_end_io = end_buffer_async_write; 6471da177e4SLinus Torvalds set_buffer_async_write(bh); 6481da177e4SLinus Torvalds } 6491da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_async_write); 6501da177e4SLinus Torvalds 6511da177e4SLinus Torvalds 6521da177e4SLinus Torvalds /* 6531da177e4SLinus Torvalds * fs/buffer.c contains helper functions for buffer-backed address space's 6541da177e4SLinus Torvalds * fsync functions. A common requirement for buffer-based filesystems is 6551da177e4SLinus Torvalds * that certain data from the backing blockdev needs to be written out for 6561da177e4SLinus Torvalds * a successful fsync(). For example, ext2 indirect blocks need to be 6571da177e4SLinus Torvalds * written back and waited upon before fsync() returns. 6581da177e4SLinus Torvalds * 6591da177e4SLinus Torvalds * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), 6601da177e4SLinus Torvalds * inode_has_buffers() and invalidate_inode_buffers() are provided for the 6611da177e4SLinus Torvalds * management of a list of dependent buffers at ->i_mapping->private_list. 6621da177e4SLinus Torvalds * 6631da177e4SLinus Torvalds * Locking is a little subtle: try_to_free_buffers() will remove buffers 6641da177e4SLinus Torvalds * from their controlling inode's queue when they are being freed. But 6651da177e4SLinus Torvalds * try_to_free_buffers() will be operating against the *blockdev* mapping 6661da177e4SLinus Torvalds * at the time, not against the S_ISREG file which depends on those buffers. 6671da177e4SLinus Torvalds * So the locking for private_list is via the private_lock in the address_space 6681da177e4SLinus Torvalds * which backs the buffers. Which is different from the address_space 6691da177e4SLinus Torvalds * against which the buffers are listed. So for a particular address_space, 6701da177e4SLinus Torvalds * mapping->private_lock does *not* protect mapping->private_list! In fact, 6711da177e4SLinus Torvalds * mapping->private_list will always be protected by the backing blockdev's 6721da177e4SLinus Torvalds * ->private_lock. 6731da177e4SLinus Torvalds * 6741da177e4SLinus Torvalds * Which introduces a requirement: all buffers on an address_space's 6751da177e4SLinus Torvalds * ->private_list must be from the same address_space: the blockdev's. 6761da177e4SLinus Torvalds * 6771da177e4SLinus Torvalds * address_spaces which do not place buffers at ->private_list via these 6781da177e4SLinus Torvalds * utility functions are free to use private_lock and private_list for 6791da177e4SLinus Torvalds * whatever they want. The only requirement is that list_empty(private_list) 6801da177e4SLinus Torvalds * be true at clear_inode() time. 6811da177e4SLinus Torvalds * 6821da177e4SLinus Torvalds * FIXME: clear_inode should not call invalidate_inode_buffers(). The 6831da177e4SLinus Torvalds * filesystems should do that. invalidate_inode_buffers() should just go 6841da177e4SLinus Torvalds * BUG_ON(!list_empty). 6851da177e4SLinus Torvalds * 6861da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should 6871da177e4SLinus Torvalds * take an address_space, not an inode. And it should be called 6881da177e4SLinus Torvalds * mark_buffer_dirty_fsync() to clearly define why those buffers are being 6891da177e4SLinus Torvalds * queued up. 6901da177e4SLinus Torvalds * 6911da177e4SLinus Torvalds * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the 6921da177e4SLinus Torvalds * list if it is already on a list. Because if the buffer is on a list, 6931da177e4SLinus Torvalds * it *must* already be on the right one. If not, the filesystem is being 6941da177e4SLinus Torvalds * silly. This will save a ton of locking. But first we have to ensure 6951da177e4SLinus Torvalds * that buffers are taken *off* the old inode's list when they are freed 6961da177e4SLinus Torvalds * (presumably in truncate). That requires careful auditing of all 6971da177e4SLinus Torvalds * filesystems (do it inside bforget()). It could also be done by bringing 6981da177e4SLinus Torvalds * b_inode back. 6991da177e4SLinus Torvalds */ 7001da177e4SLinus Torvalds 7011da177e4SLinus Torvalds /* 7021da177e4SLinus Torvalds * The buffer's backing address_space's private_lock must be held 7031da177e4SLinus Torvalds */ 7041da177e4SLinus Torvalds static inline void __remove_assoc_queue(struct buffer_head *bh) 7051da177e4SLinus Torvalds { 7061da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 7071da177e4SLinus Torvalds } 7081da177e4SLinus Torvalds 7091da177e4SLinus Torvalds int inode_has_buffers(struct inode *inode) 7101da177e4SLinus Torvalds { 7111da177e4SLinus Torvalds return !list_empty(&inode->i_data.private_list); 7121da177e4SLinus Torvalds } 7131da177e4SLinus Torvalds 7141da177e4SLinus Torvalds /* 7151da177e4SLinus Torvalds * osync is designed to support O_SYNC io. It waits synchronously for 7161da177e4SLinus Torvalds * all already-submitted IO to complete, but does not queue any new 7171da177e4SLinus Torvalds * writes to the disk. 7181da177e4SLinus Torvalds * 7191da177e4SLinus Torvalds * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as 7201da177e4SLinus Torvalds * you dirty the buffers, and then use osync_inode_buffers to wait for 7211da177e4SLinus Torvalds * completion. Any other dirty buffers which are not yet queued for 7221da177e4SLinus Torvalds * write will not be flushed to disk by the osync. 7231da177e4SLinus Torvalds */ 7241da177e4SLinus Torvalds static int osync_buffers_list(spinlock_t *lock, struct list_head *list) 7251da177e4SLinus Torvalds { 7261da177e4SLinus Torvalds struct buffer_head *bh; 7271da177e4SLinus Torvalds struct list_head *p; 7281da177e4SLinus Torvalds int err = 0; 7291da177e4SLinus Torvalds 7301da177e4SLinus Torvalds spin_lock(lock); 7311da177e4SLinus Torvalds repeat: 7321da177e4SLinus Torvalds list_for_each_prev(p, list) { 7331da177e4SLinus Torvalds bh = BH_ENTRY(p); 7341da177e4SLinus Torvalds if (buffer_locked(bh)) { 7351da177e4SLinus Torvalds get_bh(bh); 7361da177e4SLinus Torvalds spin_unlock(lock); 7371da177e4SLinus Torvalds wait_on_buffer(bh); 7381da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 7391da177e4SLinus Torvalds err = -EIO; 7401da177e4SLinus Torvalds brelse(bh); 7411da177e4SLinus Torvalds spin_lock(lock); 7421da177e4SLinus Torvalds goto repeat; 7431da177e4SLinus Torvalds } 7441da177e4SLinus Torvalds } 7451da177e4SLinus Torvalds spin_unlock(lock); 7461da177e4SLinus Torvalds return err; 7471da177e4SLinus Torvalds } 7481da177e4SLinus Torvalds 7491da177e4SLinus Torvalds /** 7501da177e4SLinus Torvalds * sync_mapping_buffers - write out and wait upon a mapping's "associated" 7511da177e4SLinus Torvalds * buffers 75267be2dd1SMartin Waitz * @mapping: the mapping which wants those buffers written 7531da177e4SLinus Torvalds * 7541da177e4SLinus Torvalds * Starts I/O against the buffers at mapping->private_list, and waits upon 7551da177e4SLinus Torvalds * that I/O. 7561da177e4SLinus Torvalds * 75767be2dd1SMartin Waitz * Basically, this is a convenience function for fsync(). 75867be2dd1SMartin Waitz * @mapping is a file or directory which needs those buffers to be written for 75967be2dd1SMartin Waitz * a successful fsync(). 7601da177e4SLinus Torvalds */ 7611da177e4SLinus Torvalds int sync_mapping_buffers(struct address_space *mapping) 7621da177e4SLinus Torvalds { 7631da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 7641da177e4SLinus Torvalds 7651da177e4SLinus Torvalds if (buffer_mapping == NULL || list_empty(&mapping->private_list)) 7661da177e4SLinus Torvalds return 0; 7671da177e4SLinus Torvalds 7681da177e4SLinus Torvalds return fsync_buffers_list(&buffer_mapping->private_lock, 7691da177e4SLinus Torvalds &mapping->private_list); 7701da177e4SLinus Torvalds } 7711da177e4SLinus Torvalds EXPORT_SYMBOL(sync_mapping_buffers); 7721da177e4SLinus Torvalds 7731da177e4SLinus Torvalds /* 7741da177e4SLinus Torvalds * Called when we've recently written block `bblock', and it is known that 7751da177e4SLinus Torvalds * `bblock' was for a buffer_boundary() buffer. This means that the block at 7761da177e4SLinus Torvalds * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's 7771da177e4SLinus Torvalds * dirty, schedule it for IO. So that indirects merge nicely with their data. 7781da177e4SLinus Torvalds */ 7791da177e4SLinus Torvalds void write_boundary_block(struct block_device *bdev, 7801da177e4SLinus Torvalds sector_t bblock, unsigned blocksize) 7811da177e4SLinus Torvalds { 7821da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); 7831da177e4SLinus Torvalds if (bh) { 7841da177e4SLinus Torvalds if (buffer_dirty(bh)) 7851da177e4SLinus Torvalds ll_rw_block(WRITE, 1, &bh); 7861da177e4SLinus Torvalds put_bh(bh); 7871da177e4SLinus Torvalds } 7881da177e4SLinus Torvalds } 7891da177e4SLinus Torvalds 7901da177e4SLinus Torvalds void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) 7911da177e4SLinus Torvalds { 7921da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 7931da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 7941da177e4SLinus Torvalds 7951da177e4SLinus Torvalds mark_buffer_dirty(bh); 7961da177e4SLinus Torvalds if (!mapping->assoc_mapping) { 7971da177e4SLinus Torvalds mapping->assoc_mapping = buffer_mapping; 7981da177e4SLinus Torvalds } else { 7991da177e4SLinus Torvalds if (mapping->assoc_mapping != buffer_mapping) 8001da177e4SLinus Torvalds BUG(); 8011da177e4SLinus Torvalds } 8021da177e4SLinus Torvalds if (list_empty(&bh->b_assoc_buffers)) { 8031da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 8041da177e4SLinus Torvalds list_move_tail(&bh->b_assoc_buffers, 8051da177e4SLinus Torvalds &mapping->private_list); 8061da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 8071da177e4SLinus Torvalds } 8081da177e4SLinus Torvalds } 8091da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty_inode); 8101da177e4SLinus Torvalds 8111da177e4SLinus Torvalds /* 8121da177e4SLinus Torvalds * Add a page to the dirty page list. 8131da177e4SLinus Torvalds * 8141da177e4SLinus Torvalds * It is a sad fact of life that this function is called from several places 8151da177e4SLinus Torvalds * deeply under spinlocking. It may not sleep. 8161da177e4SLinus Torvalds * 8171da177e4SLinus Torvalds * If the page has buffers, the uptodate buffers are set dirty, to preserve 8181da177e4SLinus Torvalds * dirty-state coherency between the page and the buffers. It the page does 8191da177e4SLinus Torvalds * not have buffers then when they are later attached they will all be set 8201da177e4SLinus Torvalds * dirty. 8211da177e4SLinus Torvalds * 8221da177e4SLinus Torvalds * The buffers are dirtied before the page is dirtied. There's a small race 8231da177e4SLinus Torvalds * window in which a writepage caller may see the page cleanness but not the 8241da177e4SLinus Torvalds * buffer dirtiness. That's fine. If this code were to set the page dirty 8251da177e4SLinus Torvalds * before the buffers, a concurrent writepage caller could clear the page dirty 8261da177e4SLinus Torvalds * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean 8271da177e4SLinus Torvalds * page on the dirty page list. 8281da177e4SLinus Torvalds * 8291da177e4SLinus Torvalds * We use private_lock to lock against try_to_free_buffers while using the 8301da177e4SLinus Torvalds * page's buffer list. Also use this to protect against clean buffers being 8311da177e4SLinus Torvalds * added to the page after it was set dirty. 8321da177e4SLinus Torvalds * 8331da177e4SLinus Torvalds * FIXME: may need to call ->reservepage here as well. That's rather up to the 8341da177e4SLinus Torvalds * address_space though. 8351da177e4SLinus Torvalds */ 8361da177e4SLinus Torvalds int __set_page_dirty_buffers(struct page *page) 8371da177e4SLinus Torvalds { 8381da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 8391da177e4SLinus Torvalds 8401da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 8411da177e4SLinus Torvalds if (page_has_buffers(page)) { 8421da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 8431da177e4SLinus Torvalds struct buffer_head *bh = head; 8441da177e4SLinus Torvalds 8451da177e4SLinus Torvalds do { 8461da177e4SLinus Torvalds set_buffer_dirty(bh); 8471da177e4SLinus Torvalds bh = bh->b_this_page; 8481da177e4SLinus Torvalds } while (bh != head); 8491da177e4SLinus Torvalds } 8501da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 8511da177e4SLinus Torvalds 8521da177e4SLinus Torvalds if (!TestSetPageDirty(page)) { 8531da177e4SLinus Torvalds write_lock_irq(&mapping->tree_lock); 8541da177e4SLinus Torvalds if (page->mapping) { /* Race with truncate? */ 8551da177e4SLinus Torvalds if (mapping_cap_account_dirty(mapping)) 8561da177e4SLinus Torvalds inc_page_state(nr_dirty); 8571da177e4SLinus Torvalds radix_tree_tag_set(&mapping->page_tree, 8581da177e4SLinus Torvalds page_index(page), 8591da177e4SLinus Torvalds PAGECACHE_TAG_DIRTY); 8601da177e4SLinus Torvalds } 8611da177e4SLinus Torvalds write_unlock_irq(&mapping->tree_lock); 8621da177e4SLinus Torvalds __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 8631da177e4SLinus Torvalds } 8641da177e4SLinus Torvalds 8651da177e4SLinus Torvalds return 0; 8661da177e4SLinus Torvalds } 8671da177e4SLinus Torvalds EXPORT_SYMBOL(__set_page_dirty_buffers); 8681da177e4SLinus Torvalds 8691da177e4SLinus Torvalds /* 8701da177e4SLinus Torvalds * Write out and wait upon a list of buffers. 8711da177e4SLinus Torvalds * 8721da177e4SLinus Torvalds * We have conflicting pressures: we want to make sure that all 8731da177e4SLinus Torvalds * initially dirty buffers get waited on, but that any subsequently 8741da177e4SLinus Torvalds * dirtied buffers don't. After all, we don't want fsync to last 8751da177e4SLinus Torvalds * forever if somebody is actively writing to the file. 8761da177e4SLinus Torvalds * 8771da177e4SLinus Torvalds * Do this in two main stages: first we copy dirty buffers to a 8781da177e4SLinus Torvalds * temporary inode list, queueing the writes as we go. Then we clean 8791da177e4SLinus Torvalds * up, waiting for those writes to complete. 8801da177e4SLinus Torvalds * 8811da177e4SLinus Torvalds * During this second stage, any subsequent updates to the file may end 8821da177e4SLinus Torvalds * up refiling the buffer on the original inode's dirty list again, so 8831da177e4SLinus Torvalds * there is a chance we will end up with a buffer queued for write but 8841da177e4SLinus Torvalds * not yet completed on that list. So, as a final cleanup we go through 8851da177e4SLinus Torvalds * the osync code to catch these locked, dirty buffers without requeuing 8861da177e4SLinus Torvalds * any newly dirty buffers for write. 8871da177e4SLinus Torvalds */ 8881da177e4SLinus Torvalds static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 8891da177e4SLinus Torvalds { 8901da177e4SLinus Torvalds struct buffer_head *bh; 8911da177e4SLinus Torvalds struct list_head tmp; 8921da177e4SLinus Torvalds int err = 0, err2; 8931da177e4SLinus Torvalds 8941da177e4SLinus Torvalds INIT_LIST_HEAD(&tmp); 8951da177e4SLinus Torvalds 8961da177e4SLinus Torvalds spin_lock(lock); 8971da177e4SLinus Torvalds while (!list_empty(list)) { 8981da177e4SLinus Torvalds bh = BH_ENTRY(list->next); 8991da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 9001da177e4SLinus Torvalds if (buffer_dirty(bh) || buffer_locked(bh)) { 9011da177e4SLinus Torvalds list_add(&bh->b_assoc_buffers, &tmp); 9021da177e4SLinus Torvalds if (buffer_dirty(bh)) { 9031da177e4SLinus Torvalds get_bh(bh); 9041da177e4SLinus Torvalds spin_unlock(lock); 9051da177e4SLinus Torvalds /* 9061da177e4SLinus Torvalds * Ensure any pending I/O completes so that 9071da177e4SLinus Torvalds * ll_rw_block() actually writes the current 9081da177e4SLinus Torvalds * contents - it is a noop if I/O is still in 9091da177e4SLinus Torvalds * flight on potentially older contents. 9101da177e4SLinus Torvalds */ 9111da177e4SLinus Torvalds wait_on_buffer(bh); 9121da177e4SLinus Torvalds ll_rw_block(WRITE, 1, &bh); 9131da177e4SLinus Torvalds brelse(bh); 9141da177e4SLinus Torvalds spin_lock(lock); 9151da177e4SLinus Torvalds } 9161da177e4SLinus Torvalds } 9171da177e4SLinus Torvalds } 9181da177e4SLinus Torvalds 9191da177e4SLinus Torvalds while (!list_empty(&tmp)) { 9201da177e4SLinus Torvalds bh = BH_ENTRY(tmp.prev); 9211da177e4SLinus Torvalds __remove_assoc_queue(bh); 9221da177e4SLinus Torvalds get_bh(bh); 9231da177e4SLinus Torvalds spin_unlock(lock); 9241da177e4SLinus Torvalds wait_on_buffer(bh); 9251da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 9261da177e4SLinus Torvalds err = -EIO; 9271da177e4SLinus Torvalds brelse(bh); 9281da177e4SLinus Torvalds spin_lock(lock); 9291da177e4SLinus Torvalds } 9301da177e4SLinus Torvalds 9311da177e4SLinus Torvalds spin_unlock(lock); 9321da177e4SLinus Torvalds err2 = osync_buffers_list(lock, list); 9331da177e4SLinus Torvalds if (err) 9341da177e4SLinus Torvalds return err; 9351da177e4SLinus Torvalds else 9361da177e4SLinus Torvalds return err2; 9371da177e4SLinus Torvalds } 9381da177e4SLinus Torvalds 9391da177e4SLinus Torvalds /* 9401da177e4SLinus Torvalds * Invalidate any and all dirty buffers on a given inode. We are 9411da177e4SLinus Torvalds * probably unmounting the fs, but that doesn't mean we have already 9421da177e4SLinus Torvalds * done a sync(). Just drop the buffers from the inode list. 9431da177e4SLinus Torvalds * 9441da177e4SLinus Torvalds * NOTE: we take the inode's blockdev's mapping's private_lock. Which 9451da177e4SLinus Torvalds * assumes that all the buffers are against the blockdev. Not true 9461da177e4SLinus Torvalds * for reiserfs. 9471da177e4SLinus Torvalds */ 9481da177e4SLinus Torvalds void invalidate_inode_buffers(struct inode *inode) 9491da177e4SLinus Torvalds { 9501da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 9511da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 9521da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 9531da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 9541da177e4SLinus Torvalds 9551da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 9561da177e4SLinus Torvalds while (!list_empty(list)) 9571da177e4SLinus Torvalds __remove_assoc_queue(BH_ENTRY(list->next)); 9581da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 9591da177e4SLinus Torvalds } 9601da177e4SLinus Torvalds } 9611da177e4SLinus Torvalds 9621da177e4SLinus Torvalds /* 9631da177e4SLinus Torvalds * Remove any clean buffers from the inode's buffer list. This is called 9641da177e4SLinus Torvalds * when we're trying to free the inode itself. Those buffers can pin it. 9651da177e4SLinus Torvalds * 9661da177e4SLinus Torvalds * Returns true if all buffers were removed. 9671da177e4SLinus Torvalds */ 9681da177e4SLinus Torvalds int remove_inode_buffers(struct inode *inode) 9691da177e4SLinus Torvalds { 9701da177e4SLinus Torvalds int ret = 1; 9711da177e4SLinus Torvalds 9721da177e4SLinus Torvalds if (inode_has_buffers(inode)) { 9731da177e4SLinus Torvalds struct address_space *mapping = &inode->i_data; 9741da177e4SLinus Torvalds struct list_head *list = &mapping->private_list; 9751da177e4SLinus Torvalds struct address_space *buffer_mapping = mapping->assoc_mapping; 9761da177e4SLinus Torvalds 9771da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 9781da177e4SLinus Torvalds while (!list_empty(list)) { 9791da177e4SLinus Torvalds struct buffer_head *bh = BH_ENTRY(list->next); 9801da177e4SLinus Torvalds if (buffer_dirty(bh)) { 9811da177e4SLinus Torvalds ret = 0; 9821da177e4SLinus Torvalds break; 9831da177e4SLinus Torvalds } 9841da177e4SLinus Torvalds __remove_assoc_queue(bh); 9851da177e4SLinus Torvalds } 9861da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 9871da177e4SLinus Torvalds } 9881da177e4SLinus Torvalds return ret; 9891da177e4SLinus Torvalds } 9901da177e4SLinus Torvalds 9911da177e4SLinus Torvalds /* 9921da177e4SLinus Torvalds * Create the appropriate buffers when given a page for data area and 9931da177e4SLinus Torvalds * the size of each buffer.. Use the bh->b_this_page linked list to 9941da177e4SLinus Torvalds * follow the buffers created. Return NULL if unable to create more 9951da177e4SLinus Torvalds * buffers. 9961da177e4SLinus Torvalds * 9971da177e4SLinus Torvalds * The retry flag is used to differentiate async IO (paging, swapping) 9981da177e4SLinus Torvalds * which may not fail from ordinary buffer allocations. 9991da177e4SLinus Torvalds */ 10001da177e4SLinus Torvalds struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, 10011da177e4SLinus Torvalds int retry) 10021da177e4SLinus Torvalds { 10031da177e4SLinus Torvalds struct buffer_head *bh, *head; 10041da177e4SLinus Torvalds long offset; 10051da177e4SLinus Torvalds 10061da177e4SLinus Torvalds try_again: 10071da177e4SLinus Torvalds head = NULL; 10081da177e4SLinus Torvalds offset = PAGE_SIZE; 10091da177e4SLinus Torvalds while ((offset -= size) >= 0) { 10101da177e4SLinus Torvalds bh = alloc_buffer_head(GFP_NOFS); 10111da177e4SLinus Torvalds if (!bh) 10121da177e4SLinus Torvalds goto no_grow; 10131da177e4SLinus Torvalds 10141da177e4SLinus Torvalds bh->b_bdev = NULL; 10151da177e4SLinus Torvalds bh->b_this_page = head; 10161da177e4SLinus Torvalds bh->b_blocknr = -1; 10171da177e4SLinus Torvalds head = bh; 10181da177e4SLinus Torvalds 10191da177e4SLinus Torvalds bh->b_state = 0; 10201da177e4SLinus Torvalds atomic_set(&bh->b_count, 0); 10211da177e4SLinus Torvalds bh->b_size = size; 10221da177e4SLinus Torvalds 10231da177e4SLinus Torvalds /* Link the buffer to its page */ 10241da177e4SLinus Torvalds set_bh_page(bh, page, offset); 10251da177e4SLinus Torvalds 10261da177e4SLinus Torvalds bh->b_end_io = NULL; 10271da177e4SLinus Torvalds } 10281da177e4SLinus Torvalds return head; 10291da177e4SLinus Torvalds /* 10301da177e4SLinus Torvalds * In case anything failed, we just free everything we got. 10311da177e4SLinus Torvalds */ 10321da177e4SLinus Torvalds no_grow: 10331da177e4SLinus Torvalds if (head) { 10341da177e4SLinus Torvalds do { 10351da177e4SLinus Torvalds bh = head; 10361da177e4SLinus Torvalds head = head->b_this_page; 10371da177e4SLinus Torvalds free_buffer_head(bh); 10381da177e4SLinus Torvalds } while (head); 10391da177e4SLinus Torvalds } 10401da177e4SLinus Torvalds 10411da177e4SLinus Torvalds /* 10421da177e4SLinus Torvalds * Return failure for non-async IO requests. Async IO requests 10431da177e4SLinus Torvalds * are not allowed to fail, so we have to wait until buffer heads 10441da177e4SLinus Torvalds * become available. But we don't want tasks sleeping with 10451da177e4SLinus Torvalds * partially complete buffers, so all were released above. 10461da177e4SLinus Torvalds */ 10471da177e4SLinus Torvalds if (!retry) 10481da177e4SLinus Torvalds return NULL; 10491da177e4SLinus Torvalds 10501da177e4SLinus Torvalds /* We're _really_ low on memory. Now we just 10511da177e4SLinus Torvalds * wait for old buffer heads to become free due to 10521da177e4SLinus Torvalds * finishing IO. Since this is an async request and 10531da177e4SLinus Torvalds * the reserve list is empty, we're sure there are 10541da177e4SLinus Torvalds * async buffer heads in use. 10551da177e4SLinus Torvalds */ 10561da177e4SLinus Torvalds free_more_memory(); 10571da177e4SLinus Torvalds goto try_again; 10581da177e4SLinus Torvalds } 10591da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(alloc_page_buffers); 10601da177e4SLinus Torvalds 10611da177e4SLinus Torvalds static inline void 10621da177e4SLinus Torvalds link_dev_buffers(struct page *page, struct buffer_head *head) 10631da177e4SLinus Torvalds { 10641da177e4SLinus Torvalds struct buffer_head *bh, *tail; 10651da177e4SLinus Torvalds 10661da177e4SLinus Torvalds bh = head; 10671da177e4SLinus Torvalds do { 10681da177e4SLinus Torvalds tail = bh; 10691da177e4SLinus Torvalds bh = bh->b_this_page; 10701da177e4SLinus Torvalds } while (bh); 10711da177e4SLinus Torvalds tail->b_this_page = head; 10721da177e4SLinus Torvalds attach_page_buffers(page, head); 10731da177e4SLinus Torvalds } 10741da177e4SLinus Torvalds 10751da177e4SLinus Torvalds /* 10761da177e4SLinus Torvalds * Initialise the state of a blockdev page's buffers. 10771da177e4SLinus Torvalds */ 10781da177e4SLinus Torvalds static void 10791da177e4SLinus Torvalds init_page_buffers(struct page *page, struct block_device *bdev, 10801da177e4SLinus Torvalds sector_t block, int size) 10811da177e4SLinus Torvalds { 10821da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 10831da177e4SLinus Torvalds struct buffer_head *bh = head; 10841da177e4SLinus Torvalds int uptodate = PageUptodate(page); 10851da177e4SLinus Torvalds 10861da177e4SLinus Torvalds do { 10871da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 10881da177e4SLinus Torvalds init_buffer(bh, NULL, NULL); 10891da177e4SLinus Torvalds bh->b_bdev = bdev; 10901da177e4SLinus Torvalds bh->b_blocknr = block; 10911da177e4SLinus Torvalds if (uptodate) 10921da177e4SLinus Torvalds set_buffer_uptodate(bh); 10931da177e4SLinus Torvalds set_buffer_mapped(bh); 10941da177e4SLinus Torvalds } 10951da177e4SLinus Torvalds block++; 10961da177e4SLinus Torvalds bh = bh->b_this_page; 10971da177e4SLinus Torvalds } while (bh != head); 10981da177e4SLinus Torvalds } 10991da177e4SLinus Torvalds 11001da177e4SLinus Torvalds /* 11011da177e4SLinus Torvalds * Create the page-cache page that contains the requested block. 11021da177e4SLinus Torvalds * 11031da177e4SLinus Torvalds * This is user purely for blockdev mappings. 11041da177e4SLinus Torvalds */ 11051da177e4SLinus Torvalds static struct page * 11061da177e4SLinus Torvalds grow_dev_page(struct block_device *bdev, sector_t block, 11071da177e4SLinus Torvalds pgoff_t index, int size) 11081da177e4SLinus Torvalds { 11091da177e4SLinus Torvalds struct inode *inode = bdev->bd_inode; 11101da177e4SLinus Torvalds struct page *page; 11111da177e4SLinus Torvalds struct buffer_head *bh; 11121da177e4SLinus Torvalds 11131da177e4SLinus Torvalds page = find_or_create_page(inode->i_mapping, index, GFP_NOFS); 11141da177e4SLinus Torvalds if (!page) 11151da177e4SLinus Torvalds return NULL; 11161da177e4SLinus Torvalds 11171da177e4SLinus Torvalds if (!PageLocked(page)) 11181da177e4SLinus Torvalds BUG(); 11191da177e4SLinus Torvalds 11201da177e4SLinus Torvalds if (page_has_buffers(page)) { 11211da177e4SLinus Torvalds bh = page_buffers(page); 11221da177e4SLinus Torvalds if (bh->b_size == size) { 11231da177e4SLinus Torvalds init_page_buffers(page, bdev, block, size); 11241da177e4SLinus Torvalds return page; 11251da177e4SLinus Torvalds } 11261da177e4SLinus Torvalds if (!try_to_free_buffers(page)) 11271da177e4SLinus Torvalds goto failed; 11281da177e4SLinus Torvalds } 11291da177e4SLinus Torvalds 11301da177e4SLinus Torvalds /* 11311da177e4SLinus Torvalds * Allocate some buffers for this page 11321da177e4SLinus Torvalds */ 11331da177e4SLinus Torvalds bh = alloc_page_buffers(page, size, 0); 11341da177e4SLinus Torvalds if (!bh) 11351da177e4SLinus Torvalds goto failed; 11361da177e4SLinus Torvalds 11371da177e4SLinus Torvalds /* 11381da177e4SLinus Torvalds * Link the page to the buffers and initialise them. Take the 11391da177e4SLinus Torvalds * lock to be atomic wrt __find_get_block(), which does not 11401da177e4SLinus Torvalds * run under the page lock. 11411da177e4SLinus Torvalds */ 11421da177e4SLinus Torvalds spin_lock(&inode->i_mapping->private_lock); 11431da177e4SLinus Torvalds link_dev_buffers(page, bh); 11441da177e4SLinus Torvalds init_page_buffers(page, bdev, block, size); 11451da177e4SLinus Torvalds spin_unlock(&inode->i_mapping->private_lock); 11461da177e4SLinus Torvalds return page; 11471da177e4SLinus Torvalds 11481da177e4SLinus Torvalds failed: 11491da177e4SLinus Torvalds BUG(); 11501da177e4SLinus Torvalds unlock_page(page); 11511da177e4SLinus Torvalds page_cache_release(page); 11521da177e4SLinus Torvalds return NULL; 11531da177e4SLinus Torvalds } 11541da177e4SLinus Torvalds 11551da177e4SLinus Torvalds /* 11561da177e4SLinus Torvalds * Create buffers for the specified block device block's page. If 11571da177e4SLinus Torvalds * that page was dirty, the buffers are set dirty also. 11581da177e4SLinus Torvalds * 11591da177e4SLinus Torvalds * Except that's a bug. Attaching dirty buffers to a dirty 11601da177e4SLinus Torvalds * blockdev's page can result in filesystem corruption, because 11611da177e4SLinus Torvalds * some of those buffers may be aliases of filesystem data. 11621da177e4SLinus Torvalds * grow_dev_page() will go BUG() if this happens. 11631da177e4SLinus Torvalds */ 11641da177e4SLinus Torvalds static inline int 11651da177e4SLinus Torvalds grow_buffers(struct block_device *bdev, sector_t block, int size) 11661da177e4SLinus Torvalds { 11671da177e4SLinus Torvalds struct page *page; 11681da177e4SLinus Torvalds pgoff_t index; 11691da177e4SLinus Torvalds int sizebits; 11701da177e4SLinus Torvalds 11711da177e4SLinus Torvalds sizebits = -1; 11721da177e4SLinus Torvalds do { 11731da177e4SLinus Torvalds sizebits++; 11741da177e4SLinus Torvalds } while ((size << sizebits) < PAGE_SIZE); 11751da177e4SLinus Torvalds 11761da177e4SLinus Torvalds index = block >> sizebits; 11771da177e4SLinus Torvalds block = index << sizebits; 11781da177e4SLinus Torvalds 11791da177e4SLinus Torvalds /* Create a page with the proper size buffers.. */ 11801da177e4SLinus Torvalds page = grow_dev_page(bdev, block, index, size); 11811da177e4SLinus Torvalds if (!page) 11821da177e4SLinus Torvalds return 0; 11831da177e4SLinus Torvalds unlock_page(page); 11841da177e4SLinus Torvalds page_cache_release(page); 11851da177e4SLinus Torvalds return 1; 11861da177e4SLinus Torvalds } 11871da177e4SLinus Torvalds 118875c96f85SAdrian Bunk static struct buffer_head * 11891da177e4SLinus Torvalds __getblk_slow(struct block_device *bdev, sector_t block, int size) 11901da177e4SLinus Torvalds { 11911da177e4SLinus Torvalds /* Size must be multiple of hard sectorsize */ 11921da177e4SLinus Torvalds if (unlikely(size & (bdev_hardsect_size(bdev)-1) || 11931da177e4SLinus Torvalds (size < 512 || size > PAGE_SIZE))) { 11941da177e4SLinus Torvalds printk(KERN_ERR "getblk(): invalid block size %d requested\n", 11951da177e4SLinus Torvalds size); 11961da177e4SLinus Torvalds printk(KERN_ERR "hardsect size: %d\n", 11971da177e4SLinus Torvalds bdev_hardsect_size(bdev)); 11981da177e4SLinus Torvalds 11991da177e4SLinus Torvalds dump_stack(); 12001da177e4SLinus Torvalds return NULL; 12011da177e4SLinus Torvalds } 12021da177e4SLinus Torvalds 12031da177e4SLinus Torvalds for (;;) { 12041da177e4SLinus Torvalds struct buffer_head * bh; 12051da177e4SLinus Torvalds 12061da177e4SLinus Torvalds bh = __find_get_block(bdev, block, size); 12071da177e4SLinus Torvalds if (bh) 12081da177e4SLinus Torvalds return bh; 12091da177e4SLinus Torvalds 12101da177e4SLinus Torvalds if (!grow_buffers(bdev, block, size)) 12111da177e4SLinus Torvalds free_more_memory(); 12121da177e4SLinus Torvalds } 12131da177e4SLinus Torvalds } 12141da177e4SLinus Torvalds 12151da177e4SLinus Torvalds /* 12161da177e4SLinus Torvalds * The relationship between dirty buffers and dirty pages: 12171da177e4SLinus Torvalds * 12181da177e4SLinus Torvalds * Whenever a page has any dirty buffers, the page's dirty bit is set, and 12191da177e4SLinus Torvalds * the page is tagged dirty in its radix tree. 12201da177e4SLinus Torvalds * 12211da177e4SLinus Torvalds * At all times, the dirtiness of the buffers represents the dirtiness of 12221da177e4SLinus Torvalds * subsections of the page. If the page has buffers, the page dirty bit is 12231da177e4SLinus Torvalds * merely a hint about the true dirty state. 12241da177e4SLinus Torvalds * 12251da177e4SLinus Torvalds * When a page is set dirty in its entirety, all its buffers are marked dirty 12261da177e4SLinus Torvalds * (if the page has buffers). 12271da177e4SLinus Torvalds * 12281da177e4SLinus Torvalds * When a buffer is marked dirty, its page is dirtied, but the page's other 12291da177e4SLinus Torvalds * buffers are not. 12301da177e4SLinus Torvalds * 12311da177e4SLinus Torvalds * Also. When blockdev buffers are explicitly read with bread(), they 12321da177e4SLinus Torvalds * individually become uptodate. But their backing page remains not 12331da177e4SLinus Torvalds * uptodate - even if all of its buffers are uptodate. A subsequent 12341da177e4SLinus Torvalds * block_read_full_page() against that page will discover all the uptodate 12351da177e4SLinus Torvalds * buffers, will set the page uptodate and will perform no I/O. 12361da177e4SLinus Torvalds */ 12371da177e4SLinus Torvalds 12381da177e4SLinus Torvalds /** 12391da177e4SLinus Torvalds * mark_buffer_dirty - mark a buffer_head as needing writeout 124067be2dd1SMartin Waitz * @bh: the buffer_head to mark dirty 12411da177e4SLinus Torvalds * 12421da177e4SLinus Torvalds * mark_buffer_dirty() will set the dirty bit against the buffer, then set its 12431da177e4SLinus Torvalds * backing page dirty, then tag the page as dirty in its address_space's radix 12441da177e4SLinus Torvalds * tree and then attach the address_space's inode to its superblock's dirty 12451da177e4SLinus Torvalds * inode list. 12461da177e4SLinus Torvalds * 12471da177e4SLinus Torvalds * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, 12481da177e4SLinus Torvalds * mapping->tree_lock and the global inode_lock. 12491da177e4SLinus Torvalds */ 12501da177e4SLinus Torvalds void fastcall mark_buffer_dirty(struct buffer_head *bh) 12511da177e4SLinus Torvalds { 12521da177e4SLinus Torvalds if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh)) 12531da177e4SLinus Torvalds __set_page_dirty_nobuffers(bh->b_page); 12541da177e4SLinus Torvalds } 12551da177e4SLinus Torvalds 12561da177e4SLinus Torvalds /* 12571da177e4SLinus Torvalds * Decrement a buffer_head's reference count. If all buffers against a page 12581da177e4SLinus Torvalds * have zero reference count, are clean and unlocked, and if the page is clean 12591da177e4SLinus Torvalds * and unlocked then try_to_free_buffers() may strip the buffers from the page 12601da177e4SLinus Torvalds * in preparation for freeing it (sometimes, rarely, buffers are removed from 12611da177e4SLinus Torvalds * a page but it ends up not being freed, and buffers may later be reattached). 12621da177e4SLinus Torvalds */ 12631da177e4SLinus Torvalds void __brelse(struct buffer_head * buf) 12641da177e4SLinus Torvalds { 12651da177e4SLinus Torvalds if (atomic_read(&buf->b_count)) { 12661da177e4SLinus Torvalds put_bh(buf); 12671da177e4SLinus Torvalds return; 12681da177e4SLinus Torvalds } 12691da177e4SLinus Torvalds printk(KERN_ERR "VFS: brelse: Trying to free free buffer\n"); 12701da177e4SLinus Torvalds WARN_ON(1); 12711da177e4SLinus Torvalds } 12721da177e4SLinus Torvalds 12731da177e4SLinus Torvalds /* 12741da177e4SLinus Torvalds * bforget() is like brelse(), except it discards any 12751da177e4SLinus Torvalds * potentially dirty data. 12761da177e4SLinus Torvalds */ 12771da177e4SLinus Torvalds void __bforget(struct buffer_head *bh) 12781da177e4SLinus Torvalds { 12791da177e4SLinus Torvalds clear_buffer_dirty(bh); 12801da177e4SLinus Torvalds if (!list_empty(&bh->b_assoc_buffers)) { 12811da177e4SLinus Torvalds struct address_space *buffer_mapping = bh->b_page->mapping; 12821da177e4SLinus Torvalds 12831da177e4SLinus Torvalds spin_lock(&buffer_mapping->private_lock); 12841da177e4SLinus Torvalds list_del_init(&bh->b_assoc_buffers); 12851da177e4SLinus Torvalds spin_unlock(&buffer_mapping->private_lock); 12861da177e4SLinus Torvalds } 12871da177e4SLinus Torvalds __brelse(bh); 12881da177e4SLinus Torvalds } 12891da177e4SLinus Torvalds 12901da177e4SLinus Torvalds static struct buffer_head *__bread_slow(struct buffer_head *bh) 12911da177e4SLinus Torvalds { 12921da177e4SLinus Torvalds lock_buffer(bh); 12931da177e4SLinus Torvalds if (buffer_uptodate(bh)) { 12941da177e4SLinus Torvalds unlock_buffer(bh); 12951da177e4SLinus Torvalds return bh; 12961da177e4SLinus Torvalds } else { 12971da177e4SLinus Torvalds get_bh(bh); 12981da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_sync; 12991da177e4SLinus Torvalds submit_bh(READ, bh); 13001da177e4SLinus Torvalds wait_on_buffer(bh); 13011da177e4SLinus Torvalds if (buffer_uptodate(bh)) 13021da177e4SLinus Torvalds return bh; 13031da177e4SLinus Torvalds } 13041da177e4SLinus Torvalds brelse(bh); 13051da177e4SLinus Torvalds return NULL; 13061da177e4SLinus Torvalds } 13071da177e4SLinus Torvalds 13081da177e4SLinus Torvalds /* 13091da177e4SLinus Torvalds * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). 13101da177e4SLinus Torvalds * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their 13111da177e4SLinus Torvalds * refcount elevated by one when they're in an LRU. A buffer can only appear 13121da177e4SLinus Torvalds * once in a particular CPU's LRU. A single buffer can be present in multiple 13131da177e4SLinus Torvalds * CPU's LRUs at the same time. 13141da177e4SLinus Torvalds * 13151da177e4SLinus Torvalds * This is a transparent caching front-end to sb_bread(), sb_getblk() and 13161da177e4SLinus Torvalds * sb_find_get_block(). 13171da177e4SLinus Torvalds * 13181da177e4SLinus Torvalds * The LRUs themselves only need locking against invalidate_bh_lrus. We use 13191da177e4SLinus Torvalds * a local interrupt disable for that. 13201da177e4SLinus Torvalds */ 13211da177e4SLinus Torvalds 13221da177e4SLinus Torvalds #define BH_LRU_SIZE 8 13231da177e4SLinus Torvalds 13241da177e4SLinus Torvalds struct bh_lru { 13251da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 13261da177e4SLinus Torvalds }; 13271da177e4SLinus Torvalds 13281da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; 13291da177e4SLinus Torvalds 13301da177e4SLinus Torvalds #ifdef CONFIG_SMP 13311da177e4SLinus Torvalds #define bh_lru_lock() local_irq_disable() 13321da177e4SLinus Torvalds #define bh_lru_unlock() local_irq_enable() 13331da177e4SLinus Torvalds #else 13341da177e4SLinus Torvalds #define bh_lru_lock() preempt_disable() 13351da177e4SLinus Torvalds #define bh_lru_unlock() preempt_enable() 13361da177e4SLinus Torvalds #endif 13371da177e4SLinus Torvalds 13381da177e4SLinus Torvalds static inline void check_irqs_on(void) 13391da177e4SLinus Torvalds { 13401da177e4SLinus Torvalds #ifdef irqs_disabled 13411da177e4SLinus Torvalds BUG_ON(irqs_disabled()); 13421da177e4SLinus Torvalds #endif 13431da177e4SLinus Torvalds } 13441da177e4SLinus Torvalds 13451da177e4SLinus Torvalds /* 13461da177e4SLinus Torvalds * The LRU management algorithm is dopey-but-simple. Sorry. 13471da177e4SLinus Torvalds */ 13481da177e4SLinus Torvalds static void bh_lru_install(struct buffer_head *bh) 13491da177e4SLinus Torvalds { 13501da177e4SLinus Torvalds struct buffer_head *evictee = NULL; 13511da177e4SLinus Torvalds struct bh_lru *lru; 13521da177e4SLinus Torvalds 13531da177e4SLinus Torvalds check_irqs_on(); 13541da177e4SLinus Torvalds bh_lru_lock(); 13551da177e4SLinus Torvalds lru = &__get_cpu_var(bh_lrus); 13561da177e4SLinus Torvalds if (lru->bhs[0] != bh) { 13571da177e4SLinus Torvalds struct buffer_head *bhs[BH_LRU_SIZE]; 13581da177e4SLinus Torvalds int in; 13591da177e4SLinus Torvalds int out = 0; 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds get_bh(bh); 13621da177e4SLinus Torvalds bhs[out++] = bh; 13631da177e4SLinus Torvalds for (in = 0; in < BH_LRU_SIZE; in++) { 13641da177e4SLinus Torvalds struct buffer_head *bh2 = lru->bhs[in]; 13651da177e4SLinus Torvalds 13661da177e4SLinus Torvalds if (bh2 == bh) { 13671da177e4SLinus Torvalds __brelse(bh2); 13681da177e4SLinus Torvalds } else { 13691da177e4SLinus Torvalds if (out >= BH_LRU_SIZE) { 13701da177e4SLinus Torvalds BUG_ON(evictee != NULL); 13711da177e4SLinus Torvalds evictee = bh2; 13721da177e4SLinus Torvalds } else { 13731da177e4SLinus Torvalds bhs[out++] = bh2; 13741da177e4SLinus Torvalds } 13751da177e4SLinus Torvalds } 13761da177e4SLinus Torvalds } 13771da177e4SLinus Torvalds while (out < BH_LRU_SIZE) 13781da177e4SLinus Torvalds bhs[out++] = NULL; 13791da177e4SLinus Torvalds memcpy(lru->bhs, bhs, sizeof(bhs)); 13801da177e4SLinus Torvalds } 13811da177e4SLinus Torvalds bh_lru_unlock(); 13821da177e4SLinus Torvalds 13831da177e4SLinus Torvalds if (evictee) 13841da177e4SLinus Torvalds __brelse(evictee); 13851da177e4SLinus Torvalds } 13861da177e4SLinus Torvalds 13871da177e4SLinus Torvalds /* 13881da177e4SLinus Torvalds * Look up the bh in this cpu's LRU. If it's there, move it to the head. 13891da177e4SLinus Torvalds */ 13901da177e4SLinus Torvalds static inline struct buffer_head * 13911da177e4SLinus Torvalds lookup_bh_lru(struct block_device *bdev, sector_t block, int size) 13921da177e4SLinus Torvalds { 13931da177e4SLinus Torvalds struct buffer_head *ret = NULL; 13941da177e4SLinus Torvalds struct bh_lru *lru; 13951da177e4SLinus Torvalds int i; 13961da177e4SLinus Torvalds 13971da177e4SLinus Torvalds check_irqs_on(); 13981da177e4SLinus Torvalds bh_lru_lock(); 13991da177e4SLinus Torvalds lru = &__get_cpu_var(bh_lrus); 14001da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 14011da177e4SLinus Torvalds struct buffer_head *bh = lru->bhs[i]; 14021da177e4SLinus Torvalds 14031da177e4SLinus Torvalds if (bh && bh->b_bdev == bdev && 14041da177e4SLinus Torvalds bh->b_blocknr == block && bh->b_size == size) { 14051da177e4SLinus Torvalds if (i) { 14061da177e4SLinus Torvalds while (i) { 14071da177e4SLinus Torvalds lru->bhs[i] = lru->bhs[i - 1]; 14081da177e4SLinus Torvalds i--; 14091da177e4SLinus Torvalds } 14101da177e4SLinus Torvalds lru->bhs[0] = bh; 14111da177e4SLinus Torvalds } 14121da177e4SLinus Torvalds get_bh(bh); 14131da177e4SLinus Torvalds ret = bh; 14141da177e4SLinus Torvalds break; 14151da177e4SLinus Torvalds } 14161da177e4SLinus Torvalds } 14171da177e4SLinus Torvalds bh_lru_unlock(); 14181da177e4SLinus Torvalds return ret; 14191da177e4SLinus Torvalds } 14201da177e4SLinus Torvalds 14211da177e4SLinus Torvalds /* 14221da177e4SLinus Torvalds * Perform a pagecache lookup for the matching buffer. If it's there, refresh 14231da177e4SLinus Torvalds * it in the LRU and mark it as accessed. If it is not present then return 14241da177e4SLinus Torvalds * NULL 14251da177e4SLinus Torvalds */ 14261da177e4SLinus Torvalds struct buffer_head * 14271da177e4SLinus Torvalds __find_get_block(struct block_device *bdev, sector_t block, int size) 14281da177e4SLinus Torvalds { 14291da177e4SLinus Torvalds struct buffer_head *bh = lookup_bh_lru(bdev, block, size); 14301da177e4SLinus Torvalds 14311da177e4SLinus Torvalds if (bh == NULL) { 14321da177e4SLinus Torvalds bh = __find_get_block_slow(bdev, block, size); 14331da177e4SLinus Torvalds if (bh) 14341da177e4SLinus Torvalds bh_lru_install(bh); 14351da177e4SLinus Torvalds } 14361da177e4SLinus Torvalds if (bh) 14371da177e4SLinus Torvalds touch_buffer(bh); 14381da177e4SLinus Torvalds return bh; 14391da177e4SLinus Torvalds } 14401da177e4SLinus Torvalds EXPORT_SYMBOL(__find_get_block); 14411da177e4SLinus Torvalds 14421da177e4SLinus Torvalds /* 14431da177e4SLinus Torvalds * __getblk will locate (and, if necessary, create) the buffer_head 14441da177e4SLinus Torvalds * which corresponds to the passed block_device, block and size. The 14451da177e4SLinus Torvalds * returned buffer has its reference count incremented. 14461da177e4SLinus Torvalds * 14471da177e4SLinus Torvalds * __getblk() cannot fail - it just keeps trying. If you pass it an 14481da177e4SLinus Torvalds * illegal block number, __getblk() will happily return a buffer_head 14491da177e4SLinus Torvalds * which represents the non-existent block. Very weird. 14501da177e4SLinus Torvalds * 14511da177e4SLinus Torvalds * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() 14521da177e4SLinus Torvalds * attempt is failing. FIXME, perhaps? 14531da177e4SLinus Torvalds */ 14541da177e4SLinus Torvalds struct buffer_head * 14551da177e4SLinus Torvalds __getblk(struct block_device *bdev, sector_t block, int size) 14561da177e4SLinus Torvalds { 14571da177e4SLinus Torvalds struct buffer_head *bh = __find_get_block(bdev, block, size); 14581da177e4SLinus Torvalds 14591da177e4SLinus Torvalds might_sleep(); 14601da177e4SLinus Torvalds if (bh == NULL) 14611da177e4SLinus Torvalds bh = __getblk_slow(bdev, block, size); 14621da177e4SLinus Torvalds return bh; 14631da177e4SLinus Torvalds } 14641da177e4SLinus Torvalds EXPORT_SYMBOL(__getblk); 14651da177e4SLinus Torvalds 14661da177e4SLinus Torvalds /* 14671da177e4SLinus Torvalds * Do async read-ahead on a buffer.. 14681da177e4SLinus Torvalds */ 14691da177e4SLinus Torvalds void __breadahead(struct block_device *bdev, sector_t block, int size) 14701da177e4SLinus Torvalds { 14711da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 14721da177e4SLinus Torvalds ll_rw_block(READA, 1, &bh); 14731da177e4SLinus Torvalds brelse(bh); 14741da177e4SLinus Torvalds } 14751da177e4SLinus Torvalds EXPORT_SYMBOL(__breadahead); 14761da177e4SLinus Torvalds 14771da177e4SLinus Torvalds /** 14781da177e4SLinus Torvalds * __bread() - reads a specified block and returns the bh 147967be2dd1SMartin Waitz * @bdev: the block_device to read from 14801da177e4SLinus Torvalds * @block: number of block 14811da177e4SLinus Torvalds * @size: size (in bytes) to read 14821da177e4SLinus Torvalds * 14831da177e4SLinus Torvalds * Reads a specified block, and returns buffer head that contains it. 14841da177e4SLinus Torvalds * It returns NULL if the block was unreadable. 14851da177e4SLinus Torvalds */ 14861da177e4SLinus Torvalds struct buffer_head * 14871da177e4SLinus Torvalds __bread(struct block_device *bdev, sector_t block, int size) 14881da177e4SLinus Torvalds { 14891da177e4SLinus Torvalds struct buffer_head *bh = __getblk(bdev, block, size); 14901da177e4SLinus Torvalds 14911da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 14921da177e4SLinus Torvalds bh = __bread_slow(bh); 14931da177e4SLinus Torvalds return bh; 14941da177e4SLinus Torvalds } 14951da177e4SLinus Torvalds EXPORT_SYMBOL(__bread); 14961da177e4SLinus Torvalds 14971da177e4SLinus Torvalds /* 14981da177e4SLinus Torvalds * invalidate_bh_lrus() is called rarely - but not only at unmount. 14991da177e4SLinus Torvalds * This doesn't race because it runs in each cpu either in irq 15001da177e4SLinus Torvalds * or with preempt disabled. 15011da177e4SLinus Torvalds */ 15021da177e4SLinus Torvalds static void invalidate_bh_lru(void *arg) 15031da177e4SLinus Torvalds { 15041da177e4SLinus Torvalds struct bh_lru *b = &get_cpu_var(bh_lrus); 15051da177e4SLinus Torvalds int i; 15061da177e4SLinus Torvalds 15071da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 15081da177e4SLinus Torvalds brelse(b->bhs[i]); 15091da177e4SLinus Torvalds b->bhs[i] = NULL; 15101da177e4SLinus Torvalds } 15111da177e4SLinus Torvalds put_cpu_var(bh_lrus); 15121da177e4SLinus Torvalds } 15131da177e4SLinus Torvalds 15141da177e4SLinus Torvalds static void invalidate_bh_lrus(void) 15151da177e4SLinus Torvalds { 15161da177e4SLinus Torvalds on_each_cpu(invalidate_bh_lru, NULL, 1, 1); 15171da177e4SLinus Torvalds } 15181da177e4SLinus Torvalds 15191da177e4SLinus Torvalds void set_bh_page(struct buffer_head *bh, 15201da177e4SLinus Torvalds struct page *page, unsigned long offset) 15211da177e4SLinus Torvalds { 15221da177e4SLinus Torvalds bh->b_page = page; 15231da177e4SLinus Torvalds if (offset >= PAGE_SIZE) 15241da177e4SLinus Torvalds BUG(); 15251da177e4SLinus Torvalds if (PageHighMem(page)) 15261da177e4SLinus Torvalds /* 15271da177e4SLinus Torvalds * This catches illegal uses and preserves the offset: 15281da177e4SLinus Torvalds */ 15291da177e4SLinus Torvalds bh->b_data = (char *)(0 + offset); 15301da177e4SLinus Torvalds else 15311da177e4SLinus Torvalds bh->b_data = page_address(page) + offset; 15321da177e4SLinus Torvalds } 15331da177e4SLinus Torvalds EXPORT_SYMBOL(set_bh_page); 15341da177e4SLinus Torvalds 15351da177e4SLinus Torvalds /* 15361da177e4SLinus Torvalds * Called when truncating a buffer on a page completely. 15371da177e4SLinus Torvalds */ 15381da177e4SLinus Torvalds static inline void discard_buffer(struct buffer_head * bh) 15391da177e4SLinus Torvalds { 15401da177e4SLinus Torvalds lock_buffer(bh); 15411da177e4SLinus Torvalds clear_buffer_dirty(bh); 15421da177e4SLinus Torvalds bh->b_bdev = NULL; 15431da177e4SLinus Torvalds clear_buffer_mapped(bh); 15441da177e4SLinus Torvalds clear_buffer_req(bh); 15451da177e4SLinus Torvalds clear_buffer_new(bh); 15461da177e4SLinus Torvalds clear_buffer_delay(bh); 15471da177e4SLinus Torvalds unlock_buffer(bh); 15481da177e4SLinus Torvalds } 15491da177e4SLinus Torvalds 15501da177e4SLinus Torvalds /** 15511da177e4SLinus Torvalds * try_to_release_page() - release old fs-specific metadata on a page 15521da177e4SLinus Torvalds * 15531da177e4SLinus Torvalds * @page: the page which the kernel is trying to free 15541da177e4SLinus Torvalds * @gfp_mask: memory allocation flags (and I/O mode) 15551da177e4SLinus Torvalds * 15561da177e4SLinus Torvalds * The address_space is to try to release any data against the page 15571da177e4SLinus Torvalds * (presumably at page->private). If the release was successful, return `1'. 15581da177e4SLinus Torvalds * Otherwise return zero. 15591da177e4SLinus Torvalds * 15601da177e4SLinus Torvalds * The @gfp_mask argument specifies whether I/O may be performed to release 15611da177e4SLinus Torvalds * this page (__GFP_IO), and whether the call may block (__GFP_WAIT). 15621da177e4SLinus Torvalds * 15631da177e4SLinus Torvalds * NOTE: @gfp_mask may go away, and this function may become non-blocking. 15641da177e4SLinus Torvalds */ 15651da177e4SLinus Torvalds int try_to_release_page(struct page *page, int gfp_mask) 15661da177e4SLinus Torvalds { 15671da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 15681da177e4SLinus Torvalds 15691da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 15701da177e4SLinus Torvalds if (PageWriteback(page)) 15711da177e4SLinus Torvalds return 0; 15721da177e4SLinus Torvalds 15731da177e4SLinus Torvalds if (mapping && mapping->a_ops->releasepage) 15741da177e4SLinus Torvalds return mapping->a_ops->releasepage(page, gfp_mask); 15751da177e4SLinus Torvalds return try_to_free_buffers(page); 15761da177e4SLinus Torvalds } 15771da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_release_page); 15781da177e4SLinus Torvalds 15791da177e4SLinus Torvalds /** 15801da177e4SLinus Torvalds * block_invalidatepage - invalidate part of all of a buffer-backed page 15811da177e4SLinus Torvalds * 15821da177e4SLinus Torvalds * @page: the page which is affected 15831da177e4SLinus Torvalds * @offset: the index of the truncation point 15841da177e4SLinus Torvalds * 15851da177e4SLinus Torvalds * block_invalidatepage() is called when all or part of the page has become 15861da177e4SLinus Torvalds * invalidatedby a truncate operation. 15871da177e4SLinus Torvalds * 15881da177e4SLinus Torvalds * block_invalidatepage() does not have to release all buffers, but it must 15891da177e4SLinus Torvalds * ensure that no dirty buffer is left outside @offset and that no I/O 15901da177e4SLinus Torvalds * is underway against any of the blocks which are outside the truncation 15911da177e4SLinus Torvalds * point. Because the caller is about to free (and possibly reuse) those 15921da177e4SLinus Torvalds * blocks on-disk. 15931da177e4SLinus Torvalds */ 15941da177e4SLinus Torvalds int block_invalidatepage(struct page *page, unsigned long offset) 15951da177e4SLinus Torvalds { 15961da177e4SLinus Torvalds struct buffer_head *head, *bh, *next; 15971da177e4SLinus Torvalds unsigned int curr_off = 0; 15981da177e4SLinus Torvalds int ret = 1; 15991da177e4SLinus Torvalds 16001da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 16011da177e4SLinus Torvalds if (!page_has_buffers(page)) 16021da177e4SLinus Torvalds goto out; 16031da177e4SLinus Torvalds 16041da177e4SLinus Torvalds head = page_buffers(page); 16051da177e4SLinus Torvalds bh = head; 16061da177e4SLinus Torvalds do { 16071da177e4SLinus Torvalds unsigned int next_off = curr_off + bh->b_size; 16081da177e4SLinus Torvalds next = bh->b_this_page; 16091da177e4SLinus Torvalds 16101da177e4SLinus Torvalds /* 16111da177e4SLinus Torvalds * is this block fully invalidated? 16121da177e4SLinus Torvalds */ 16131da177e4SLinus Torvalds if (offset <= curr_off) 16141da177e4SLinus Torvalds discard_buffer(bh); 16151da177e4SLinus Torvalds curr_off = next_off; 16161da177e4SLinus Torvalds bh = next; 16171da177e4SLinus Torvalds } while (bh != head); 16181da177e4SLinus Torvalds 16191da177e4SLinus Torvalds /* 16201da177e4SLinus Torvalds * We release buffers only if the entire page is being invalidated. 16211da177e4SLinus Torvalds * The get_block cached value has been unconditionally invalidated, 16221da177e4SLinus Torvalds * so real IO is not possible anymore. 16231da177e4SLinus Torvalds */ 16241da177e4SLinus Torvalds if (offset == 0) 16251da177e4SLinus Torvalds ret = try_to_release_page(page, 0); 16261da177e4SLinus Torvalds out: 16271da177e4SLinus Torvalds return ret; 16281da177e4SLinus Torvalds } 16291da177e4SLinus Torvalds EXPORT_SYMBOL(block_invalidatepage); 16301da177e4SLinus Torvalds 16311da177e4SLinus Torvalds /* 16321da177e4SLinus Torvalds * We attach and possibly dirty the buffers atomically wrt 16331da177e4SLinus Torvalds * __set_page_dirty_buffers() via private_lock. try_to_free_buffers 16341da177e4SLinus Torvalds * is already excluded via the page lock. 16351da177e4SLinus Torvalds */ 16361da177e4SLinus Torvalds void create_empty_buffers(struct page *page, 16371da177e4SLinus Torvalds unsigned long blocksize, unsigned long b_state) 16381da177e4SLinus Torvalds { 16391da177e4SLinus Torvalds struct buffer_head *bh, *head, *tail; 16401da177e4SLinus Torvalds 16411da177e4SLinus Torvalds head = alloc_page_buffers(page, blocksize, 1); 16421da177e4SLinus Torvalds bh = head; 16431da177e4SLinus Torvalds do { 16441da177e4SLinus Torvalds bh->b_state |= b_state; 16451da177e4SLinus Torvalds tail = bh; 16461da177e4SLinus Torvalds bh = bh->b_this_page; 16471da177e4SLinus Torvalds } while (bh); 16481da177e4SLinus Torvalds tail->b_this_page = head; 16491da177e4SLinus Torvalds 16501da177e4SLinus Torvalds spin_lock(&page->mapping->private_lock); 16511da177e4SLinus Torvalds if (PageUptodate(page) || PageDirty(page)) { 16521da177e4SLinus Torvalds bh = head; 16531da177e4SLinus Torvalds do { 16541da177e4SLinus Torvalds if (PageDirty(page)) 16551da177e4SLinus Torvalds set_buffer_dirty(bh); 16561da177e4SLinus Torvalds if (PageUptodate(page)) 16571da177e4SLinus Torvalds set_buffer_uptodate(bh); 16581da177e4SLinus Torvalds bh = bh->b_this_page; 16591da177e4SLinus Torvalds } while (bh != head); 16601da177e4SLinus Torvalds } 16611da177e4SLinus Torvalds attach_page_buffers(page, head); 16621da177e4SLinus Torvalds spin_unlock(&page->mapping->private_lock); 16631da177e4SLinus Torvalds } 16641da177e4SLinus Torvalds EXPORT_SYMBOL(create_empty_buffers); 16651da177e4SLinus Torvalds 16661da177e4SLinus Torvalds /* 16671da177e4SLinus Torvalds * We are taking a block for data and we don't want any output from any 16681da177e4SLinus Torvalds * buffer-cache aliases starting from return from that function and 16691da177e4SLinus Torvalds * until the moment when something will explicitly mark the buffer 16701da177e4SLinus Torvalds * dirty (hopefully that will not happen until we will free that block ;-) 16711da177e4SLinus Torvalds * We don't even need to mark it not-uptodate - nobody can expect 16721da177e4SLinus Torvalds * anything from a newly allocated buffer anyway. We used to used 16731da177e4SLinus Torvalds * unmap_buffer() for such invalidation, but that was wrong. We definitely 16741da177e4SLinus Torvalds * don't want to mark the alias unmapped, for example - it would confuse 16751da177e4SLinus Torvalds * anyone who might pick it with bread() afterwards... 16761da177e4SLinus Torvalds * 16771da177e4SLinus Torvalds * Also.. Note that bforget() doesn't lock the buffer. So there can 16781da177e4SLinus Torvalds * be writeout I/O going on against recently-freed buffers. We don't 16791da177e4SLinus Torvalds * wait on that I/O in bforget() - it's more efficient to wait on the I/O 16801da177e4SLinus Torvalds * only if we really need to. That happens here. 16811da177e4SLinus Torvalds */ 16821da177e4SLinus Torvalds void unmap_underlying_metadata(struct block_device *bdev, sector_t block) 16831da177e4SLinus Torvalds { 16841da177e4SLinus Torvalds struct buffer_head *old_bh; 16851da177e4SLinus Torvalds 16861da177e4SLinus Torvalds might_sleep(); 16871da177e4SLinus Torvalds 16881da177e4SLinus Torvalds old_bh = __find_get_block_slow(bdev, block, 0); 16891da177e4SLinus Torvalds if (old_bh) { 16901da177e4SLinus Torvalds clear_buffer_dirty(old_bh); 16911da177e4SLinus Torvalds wait_on_buffer(old_bh); 16921da177e4SLinus Torvalds clear_buffer_req(old_bh); 16931da177e4SLinus Torvalds __brelse(old_bh); 16941da177e4SLinus Torvalds } 16951da177e4SLinus Torvalds } 16961da177e4SLinus Torvalds EXPORT_SYMBOL(unmap_underlying_metadata); 16971da177e4SLinus Torvalds 16981da177e4SLinus Torvalds /* 16991da177e4SLinus Torvalds * NOTE! All mapped/uptodate combinations are valid: 17001da177e4SLinus Torvalds * 17011da177e4SLinus Torvalds * Mapped Uptodate Meaning 17021da177e4SLinus Torvalds * 17031da177e4SLinus Torvalds * No No "unknown" - must do get_block() 17041da177e4SLinus Torvalds * No Yes "hole" - zero-filled 17051da177e4SLinus Torvalds * Yes No "allocated" - allocated on disk, not read in 17061da177e4SLinus Torvalds * Yes Yes "valid" - allocated and up-to-date in memory. 17071da177e4SLinus Torvalds * 17081da177e4SLinus Torvalds * "Dirty" is valid only with the last case (mapped+uptodate). 17091da177e4SLinus Torvalds */ 17101da177e4SLinus Torvalds 17111da177e4SLinus Torvalds /* 17121da177e4SLinus Torvalds * While block_write_full_page is writing back the dirty buffers under 17131da177e4SLinus Torvalds * the page lock, whoever dirtied the buffers may decide to clean them 17141da177e4SLinus Torvalds * again at any time. We handle that by only looking at the buffer 17151da177e4SLinus Torvalds * state inside lock_buffer(). 17161da177e4SLinus Torvalds * 17171da177e4SLinus Torvalds * If block_write_full_page() is called for regular writeback 17181da177e4SLinus Torvalds * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a 17191da177e4SLinus Torvalds * locked buffer. This only can happen if someone has written the buffer 17201da177e4SLinus Torvalds * directly, with submit_bh(). At the address_space level PageWriteback 17211da177e4SLinus Torvalds * prevents this contention from occurring. 17221da177e4SLinus Torvalds */ 17231da177e4SLinus Torvalds static int __block_write_full_page(struct inode *inode, struct page *page, 17241da177e4SLinus Torvalds get_block_t *get_block, struct writeback_control *wbc) 17251da177e4SLinus Torvalds { 17261da177e4SLinus Torvalds int err; 17271da177e4SLinus Torvalds sector_t block; 17281da177e4SLinus Torvalds sector_t last_block; 1729f0fbd5fcSAndrew Morton struct buffer_head *bh, *head; 17301da177e4SLinus Torvalds int nr_underway = 0; 17311da177e4SLinus Torvalds 17321da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 17331da177e4SLinus Torvalds 17341da177e4SLinus Torvalds last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; 17351da177e4SLinus Torvalds 17361da177e4SLinus Torvalds if (!page_has_buffers(page)) { 17371da177e4SLinus Torvalds create_empty_buffers(page, 1 << inode->i_blkbits, 17381da177e4SLinus Torvalds (1 << BH_Dirty)|(1 << BH_Uptodate)); 17391da177e4SLinus Torvalds } 17401da177e4SLinus Torvalds 17411da177e4SLinus Torvalds /* 17421da177e4SLinus Torvalds * Be very careful. We have no exclusion from __set_page_dirty_buffers 17431da177e4SLinus Torvalds * here, and the (potentially unmapped) buffers may become dirty at 17441da177e4SLinus Torvalds * any time. If a buffer becomes dirty here after we've inspected it 17451da177e4SLinus Torvalds * then we just miss that fact, and the page stays dirty. 17461da177e4SLinus Torvalds * 17471da177e4SLinus Torvalds * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; 17481da177e4SLinus Torvalds * handle that here by just cleaning them. 17491da177e4SLinus Torvalds */ 17501da177e4SLinus Torvalds 17511da177e4SLinus Torvalds block = page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 17521da177e4SLinus Torvalds head = page_buffers(page); 17531da177e4SLinus Torvalds bh = head; 17541da177e4SLinus Torvalds 17551da177e4SLinus Torvalds /* 17561da177e4SLinus Torvalds * Get all the dirty buffers mapped to disk addresses and 17571da177e4SLinus Torvalds * handle any aliases from the underlying blockdev's mapping. 17581da177e4SLinus Torvalds */ 17591da177e4SLinus Torvalds do { 17601da177e4SLinus Torvalds if (block > last_block) { 17611da177e4SLinus Torvalds /* 17621da177e4SLinus Torvalds * mapped buffers outside i_size will occur, because 17631da177e4SLinus Torvalds * this page can be outside i_size when there is a 17641da177e4SLinus Torvalds * truncate in progress. 17651da177e4SLinus Torvalds */ 17661da177e4SLinus Torvalds /* 17671da177e4SLinus Torvalds * The buffer was zeroed by block_write_full_page() 17681da177e4SLinus Torvalds */ 17691da177e4SLinus Torvalds clear_buffer_dirty(bh); 17701da177e4SLinus Torvalds set_buffer_uptodate(bh); 17711da177e4SLinus Torvalds } else if (!buffer_mapped(bh) && buffer_dirty(bh)) { 17721da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 17731da177e4SLinus Torvalds if (err) 17741da177e4SLinus Torvalds goto recover; 17751da177e4SLinus Torvalds if (buffer_new(bh)) { 17761da177e4SLinus Torvalds /* blockdev mappings never come here */ 17771da177e4SLinus Torvalds clear_buffer_new(bh); 17781da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 17791da177e4SLinus Torvalds bh->b_blocknr); 17801da177e4SLinus Torvalds } 17811da177e4SLinus Torvalds } 17821da177e4SLinus Torvalds bh = bh->b_this_page; 17831da177e4SLinus Torvalds block++; 17841da177e4SLinus Torvalds } while (bh != head); 17851da177e4SLinus Torvalds 17861da177e4SLinus Torvalds do { 17871da177e4SLinus Torvalds if (!buffer_mapped(bh)) 17881da177e4SLinus Torvalds continue; 17891da177e4SLinus Torvalds /* 17901da177e4SLinus Torvalds * If it's a fully non-blocking write attempt and we cannot 17911da177e4SLinus Torvalds * lock the buffer then redirty the page. Note that this can 17921da177e4SLinus Torvalds * potentially cause a busy-wait loop from pdflush and kswapd 17931da177e4SLinus Torvalds * activity, but those code paths have their own higher-level 17941da177e4SLinus Torvalds * throttling. 17951da177e4SLinus Torvalds */ 17961da177e4SLinus Torvalds if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { 17971da177e4SLinus Torvalds lock_buffer(bh); 17981da177e4SLinus Torvalds } else if (test_set_buffer_locked(bh)) { 17991da177e4SLinus Torvalds redirty_page_for_writepage(wbc, page); 18001da177e4SLinus Torvalds continue; 18011da177e4SLinus Torvalds } 18021da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 18031da177e4SLinus Torvalds mark_buffer_async_write(bh); 18041da177e4SLinus Torvalds } else { 18051da177e4SLinus Torvalds unlock_buffer(bh); 18061da177e4SLinus Torvalds } 18071da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 18081da177e4SLinus Torvalds 18091da177e4SLinus Torvalds /* 18101da177e4SLinus Torvalds * The page and its buffers are protected by PageWriteback(), so we can 18111da177e4SLinus Torvalds * drop the bh refcounts early. 18121da177e4SLinus Torvalds */ 18131da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 18141da177e4SLinus Torvalds set_page_writeback(page); 18151da177e4SLinus Torvalds 18161da177e4SLinus Torvalds do { 18171da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 18181da177e4SLinus Torvalds if (buffer_async_write(bh)) { 18191da177e4SLinus Torvalds submit_bh(WRITE, bh); 18201da177e4SLinus Torvalds nr_underway++; 1821ad576e63SNick Piggin } 18221da177e4SLinus Torvalds bh = next; 18231da177e4SLinus Torvalds } while (bh != head); 182405937baaSAndrew Morton unlock_page(page); 18251da177e4SLinus Torvalds 18261da177e4SLinus Torvalds err = 0; 18271da177e4SLinus Torvalds done: 18281da177e4SLinus Torvalds if (nr_underway == 0) { 18291da177e4SLinus Torvalds /* 18301da177e4SLinus Torvalds * The page was marked dirty, but the buffers were 18311da177e4SLinus Torvalds * clean. Someone wrote them back by hand with 18321da177e4SLinus Torvalds * ll_rw_block/submit_bh. A rare case. 18331da177e4SLinus Torvalds */ 18341da177e4SLinus Torvalds int uptodate = 1; 18351da177e4SLinus Torvalds do { 18361da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 18371da177e4SLinus Torvalds uptodate = 0; 18381da177e4SLinus Torvalds break; 18391da177e4SLinus Torvalds } 18401da177e4SLinus Torvalds bh = bh->b_this_page; 18411da177e4SLinus Torvalds } while (bh != head); 18421da177e4SLinus Torvalds if (uptodate) 18431da177e4SLinus Torvalds SetPageUptodate(page); 18441da177e4SLinus Torvalds end_page_writeback(page); 18451da177e4SLinus Torvalds /* 18461da177e4SLinus Torvalds * The page and buffer_heads can be released at any time from 18471da177e4SLinus Torvalds * here on. 18481da177e4SLinus Torvalds */ 18491da177e4SLinus Torvalds wbc->pages_skipped++; /* We didn't write this page */ 18501da177e4SLinus Torvalds } 18511da177e4SLinus Torvalds return err; 18521da177e4SLinus Torvalds 18531da177e4SLinus Torvalds recover: 18541da177e4SLinus Torvalds /* 18551da177e4SLinus Torvalds * ENOSPC, or some other error. We may already have added some 18561da177e4SLinus Torvalds * blocks to the file, so we need to write these out to avoid 18571da177e4SLinus Torvalds * exposing stale data. 18581da177e4SLinus Torvalds * The page is currently locked and not marked for writeback 18591da177e4SLinus Torvalds */ 18601da177e4SLinus Torvalds bh = head; 18611da177e4SLinus Torvalds /* Recovery: lock and submit the mapped buffers */ 18621da177e4SLinus Torvalds do { 18631da177e4SLinus Torvalds if (buffer_mapped(bh) && buffer_dirty(bh)) { 18641da177e4SLinus Torvalds lock_buffer(bh); 18651da177e4SLinus Torvalds mark_buffer_async_write(bh); 18661da177e4SLinus Torvalds } else { 18671da177e4SLinus Torvalds /* 18681da177e4SLinus Torvalds * The buffer may have been set dirty during 18691da177e4SLinus Torvalds * attachment to a dirty page. 18701da177e4SLinus Torvalds */ 18711da177e4SLinus Torvalds clear_buffer_dirty(bh); 18721da177e4SLinus Torvalds } 18731da177e4SLinus Torvalds } while ((bh = bh->b_this_page) != head); 18741da177e4SLinus Torvalds SetPageError(page); 18751da177e4SLinus Torvalds BUG_ON(PageWriteback(page)); 18761da177e4SLinus Torvalds set_page_writeback(page); 18771da177e4SLinus Torvalds unlock_page(page); 18781da177e4SLinus Torvalds do { 18791da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 18801da177e4SLinus Torvalds if (buffer_async_write(bh)) { 18811da177e4SLinus Torvalds clear_buffer_dirty(bh); 18821da177e4SLinus Torvalds submit_bh(WRITE, bh); 18831da177e4SLinus Torvalds nr_underway++; 1884ad576e63SNick Piggin } 18851da177e4SLinus Torvalds bh = next; 18861da177e4SLinus Torvalds } while (bh != head); 18871da177e4SLinus Torvalds goto done; 18881da177e4SLinus Torvalds } 18891da177e4SLinus Torvalds 18901da177e4SLinus Torvalds static int __block_prepare_write(struct inode *inode, struct page *page, 18911da177e4SLinus Torvalds unsigned from, unsigned to, get_block_t *get_block) 18921da177e4SLinus Torvalds { 18931da177e4SLinus Torvalds unsigned block_start, block_end; 18941da177e4SLinus Torvalds sector_t block; 18951da177e4SLinus Torvalds int err = 0; 18961da177e4SLinus Torvalds unsigned blocksize, bbits; 18971da177e4SLinus Torvalds struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; 18981da177e4SLinus Torvalds 18991da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 19001da177e4SLinus Torvalds BUG_ON(from > PAGE_CACHE_SIZE); 19011da177e4SLinus Torvalds BUG_ON(to > PAGE_CACHE_SIZE); 19021da177e4SLinus Torvalds BUG_ON(from > to); 19031da177e4SLinus Torvalds 19041da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 19051da177e4SLinus Torvalds if (!page_has_buffers(page)) 19061da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 19071da177e4SLinus Torvalds head = page_buffers(page); 19081da177e4SLinus Torvalds 19091da177e4SLinus Torvalds bbits = inode->i_blkbits; 19101da177e4SLinus Torvalds block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); 19111da177e4SLinus Torvalds 19121da177e4SLinus Torvalds for(bh = head, block_start = 0; bh != head || !block_start; 19131da177e4SLinus Torvalds block++, block_start=block_end, bh = bh->b_this_page) { 19141da177e4SLinus Torvalds block_end = block_start + blocksize; 19151da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 19161da177e4SLinus Torvalds if (PageUptodate(page)) { 19171da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19181da177e4SLinus Torvalds set_buffer_uptodate(bh); 19191da177e4SLinus Torvalds } 19201da177e4SLinus Torvalds continue; 19211da177e4SLinus Torvalds } 19221da177e4SLinus Torvalds if (buffer_new(bh)) 19231da177e4SLinus Torvalds clear_buffer_new(bh); 19241da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 19251da177e4SLinus Torvalds err = get_block(inode, block, bh, 1); 19261da177e4SLinus Torvalds if (err) 1927f3ddbdc6SNick Piggin break; 19281da177e4SLinus Torvalds if (buffer_new(bh)) { 19291da177e4SLinus Torvalds unmap_underlying_metadata(bh->b_bdev, 19301da177e4SLinus Torvalds bh->b_blocknr); 19311da177e4SLinus Torvalds if (PageUptodate(page)) { 19321da177e4SLinus Torvalds set_buffer_uptodate(bh); 19331da177e4SLinus Torvalds continue; 19341da177e4SLinus Torvalds } 19351da177e4SLinus Torvalds if (block_end > to || block_start < from) { 19361da177e4SLinus Torvalds void *kaddr; 19371da177e4SLinus Torvalds 19381da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 19391da177e4SLinus Torvalds if (block_end > to) 19401da177e4SLinus Torvalds memset(kaddr+to, 0, 19411da177e4SLinus Torvalds block_end-to); 19421da177e4SLinus Torvalds if (block_start < from) 19431da177e4SLinus Torvalds memset(kaddr+block_start, 19441da177e4SLinus Torvalds 0, from-block_start); 19451da177e4SLinus Torvalds flush_dcache_page(page); 19461da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 19471da177e4SLinus Torvalds } 19481da177e4SLinus Torvalds continue; 19491da177e4SLinus Torvalds } 19501da177e4SLinus Torvalds } 19511da177e4SLinus Torvalds if (PageUptodate(page)) { 19521da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 19531da177e4SLinus Torvalds set_buffer_uptodate(bh); 19541da177e4SLinus Torvalds continue; 19551da177e4SLinus Torvalds } 19561da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh) && 19571da177e4SLinus Torvalds (block_start < from || block_end > to)) { 19581da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 19591da177e4SLinus Torvalds *wait_bh++=bh; 19601da177e4SLinus Torvalds } 19611da177e4SLinus Torvalds } 19621da177e4SLinus Torvalds /* 19631da177e4SLinus Torvalds * If we issued read requests - let them complete. 19641da177e4SLinus Torvalds */ 19651da177e4SLinus Torvalds while(wait_bh > wait) { 19661da177e4SLinus Torvalds wait_on_buffer(*--wait_bh); 19671da177e4SLinus Torvalds if (!buffer_uptodate(*wait_bh)) 1968f3ddbdc6SNick Piggin err = -EIO; 19691da177e4SLinus Torvalds } 1970152becd2SAnton Altaparmakov if (!err) { 1971152becd2SAnton Altaparmakov bh = head; 1972152becd2SAnton Altaparmakov do { 1973152becd2SAnton Altaparmakov if (buffer_new(bh)) 1974152becd2SAnton Altaparmakov clear_buffer_new(bh); 1975152becd2SAnton Altaparmakov } while ((bh = bh->b_this_page) != head); 1976152becd2SAnton Altaparmakov return 0; 1977152becd2SAnton Altaparmakov } 1978f3ddbdc6SNick Piggin /* Error case: */ 19791da177e4SLinus Torvalds /* 19801da177e4SLinus Torvalds * Zero out any newly allocated blocks to avoid exposing stale 19811da177e4SLinus Torvalds * data. If BH_New is set, we know that the block was newly 19821da177e4SLinus Torvalds * allocated in the above loop. 19831da177e4SLinus Torvalds */ 19841da177e4SLinus Torvalds bh = head; 19851da177e4SLinus Torvalds block_start = 0; 19861da177e4SLinus Torvalds do { 19871da177e4SLinus Torvalds block_end = block_start+blocksize; 19881da177e4SLinus Torvalds if (block_end <= from) 19891da177e4SLinus Torvalds goto next_bh; 19901da177e4SLinus Torvalds if (block_start >= to) 19911da177e4SLinus Torvalds break; 19921da177e4SLinus Torvalds if (buffer_new(bh)) { 19931da177e4SLinus Torvalds void *kaddr; 19941da177e4SLinus Torvalds 19951da177e4SLinus Torvalds clear_buffer_new(bh); 19961da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 19971da177e4SLinus Torvalds memset(kaddr+block_start, 0, bh->b_size); 19981da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 19991da177e4SLinus Torvalds set_buffer_uptodate(bh); 20001da177e4SLinus Torvalds mark_buffer_dirty(bh); 20011da177e4SLinus Torvalds } 20021da177e4SLinus Torvalds next_bh: 20031da177e4SLinus Torvalds block_start = block_end; 20041da177e4SLinus Torvalds bh = bh->b_this_page; 20051da177e4SLinus Torvalds } while (bh != head); 20061da177e4SLinus Torvalds return err; 20071da177e4SLinus Torvalds } 20081da177e4SLinus Torvalds 20091da177e4SLinus Torvalds static int __block_commit_write(struct inode *inode, struct page *page, 20101da177e4SLinus Torvalds unsigned from, unsigned to) 20111da177e4SLinus Torvalds { 20121da177e4SLinus Torvalds unsigned block_start, block_end; 20131da177e4SLinus Torvalds int partial = 0; 20141da177e4SLinus Torvalds unsigned blocksize; 20151da177e4SLinus Torvalds struct buffer_head *bh, *head; 20161da177e4SLinus Torvalds 20171da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 20181da177e4SLinus Torvalds 20191da177e4SLinus Torvalds for(bh = head = page_buffers(page), block_start = 0; 20201da177e4SLinus Torvalds bh != head || !block_start; 20211da177e4SLinus Torvalds block_start=block_end, bh = bh->b_this_page) { 20221da177e4SLinus Torvalds block_end = block_start + blocksize; 20231da177e4SLinus Torvalds if (block_end <= from || block_start >= to) { 20241da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 20251da177e4SLinus Torvalds partial = 1; 20261da177e4SLinus Torvalds } else { 20271da177e4SLinus Torvalds set_buffer_uptodate(bh); 20281da177e4SLinus Torvalds mark_buffer_dirty(bh); 20291da177e4SLinus Torvalds } 20301da177e4SLinus Torvalds } 20311da177e4SLinus Torvalds 20321da177e4SLinus Torvalds /* 20331da177e4SLinus Torvalds * If this is a partial write which happened to make all buffers 20341da177e4SLinus Torvalds * uptodate then we can optimize away a bogus readpage() for 20351da177e4SLinus Torvalds * the next read(). Here we 'discover' whether the page went 20361da177e4SLinus Torvalds * uptodate as a result of this (potentially partial) write. 20371da177e4SLinus Torvalds */ 20381da177e4SLinus Torvalds if (!partial) 20391da177e4SLinus Torvalds SetPageUptodate(page); 20401da177e4SLinus Torvalds return 0; 20411da177e4SLinus Torvalds } 20421da177e4SLinus Torvalds 20431da177e4SLinus Torvalds /* 20441da177e4SLinus Torvalds * Generic "read page" function for block devices that have the normal 20451da177e4SLinus Torvalds * get_block functionality. This is most of the block device filesystems. 20461da177e4SLinus Torvalds * Reads the page asynchronously --- the unlock_buffer() and 20471da177e4SLinus Torvalds * set/clear_buffer_uptodate() functions propagate buffer state into the 20481da177e4SLinus Torvalds * page struct once IO has completed. 20491da177e4SLinus Torvalds */ 20501da177e4SLinus Torvalds int block_read_full_page(struct page *page, get_block_t *get_block) 20511da177e4SLinus Torvalds { 20521da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 20531da177e4SLinus Torvalds sector_t iblock, lblock; 20541da177e4SLinus Torvalds struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; 20551da177e4SLinus Torvalds unsigned int blocksize; 20561da177e4SLinus Torvalds int nr, i; 20571da177e4SLinus Torvalds int fully_mapped = 1; 20581da177e4SLinus Torvalds 2059cd7619d6SMatt Mackall BUG_ON(!PageLocked(page)); 20601da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 20611da177e4SLinus Torvalds if (!page_has_buffers(page)) 20621da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 20631da177e4SLinus Torvalds head = page_buffers(page); 20641da177e4SLinus Torvalds 20651da177e4SLinus Torvalds iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 20661da177e4SLinus Torvalds lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; 20671da177e4SLinus Torvalds bh = head; 20681da177e4SLinus Torvalds nr = 0; 20691da177e4SLinus Torvalds i = 0; 20701da177e4SLinus Torvalds 20711da177e4SLinus Torvalds do { 20721da177e4SLinus Torvalds if (buffer_uptodate(bh)) 20731da177e4SLinus Torvalds continue; 20741da177e4SLinus Torvalds 20751da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 2076c64610baSAndrew Morton int err = 0; 2077c64610baSAndrew Morton 20781da177e4SLinus Torvalds fully_mapped = 0; 20791da177e4SLinus Torvalds if (iblock < lblock) { 2080c64610baSAndrew Morton err = get_block(inode, iblock, bh, 0); 2081c64610baSAndrew Morton if (err) 20821da177e4SLinus Torvalds SetPageError(page); 20831da177e4SLinus Torvalds } 20841da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 20851da177e4SLinus Torvalds void *kaddr = kmap_atomic(page, KM_USER0); 20861da177e4SLinus Torvalds memset(kaddr + i * blocksize, 0, blocksize); 20871da177e4SLinus Torvalds flush_dcache_page(page); 20881da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2089c64610baSAndrew Morton if (!err) 20901da177e4SLinus Torvalds set_buffer_uptodate(bh); 20911da177e4SLinus Torvalds continue; 20921da177e4SLinus Torvalds } 20931da177e4SLinus Torvalds /* 20941da177e4SLinus Torvalds * get_block() might have updated the buffer 20951da177e4SLinus Torvalds * synchronously 20961da177e4SLinus Torvalds */ 20971da177e4SLinus Torvalds if (buffer_uptodate(bh)) 20981da177e4SLinus Torvalds continue; 20991da177e4SLinus Torvalds } 21001da177e4SLinus Torvalds arr[nr++] = bh; 21011da177e4SLinus Torvalds } while (i++, iblock++, (bh = bh->b_this_page) != head); 21021da177e4SLinus Torvalds 21031da177e4SLinus Torvalds if (fully_mapped) 21041da177e4SLinus Torvalds SetPageMappedToDisk(page); 21051da177e4SLinus Torvalds 21061da177e4SLinus Torvalds if (!nr) { 21071da177e4SLinus Torvalds /* 21081da177e4SLinus Torvalds * All buffers are uptodate - we can set the page uptodate 21091da177e4SLinus Torvalds * as well. But not if get_block() returned an error. 21101da177e4SLinus Torvalds */ 21111da177e4SLinus Torvalds if (!PageError(page)) 21121da177e4SLinus Torvalds SetPageUptodate(page); 21131da177e4SLinus Torvalds unlock_page(page); 21141da177e4SLinus Torvalds return 0; 21151da177e4SLinus Torvalds } 21161da177e4SLinus Torvalds 21171da177e4SLinus Torvalds /* Stage two: lock the buffers */ 21181da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 21191da177e4SLinus Torvalds bh = arr[i]; 21201da177e4SLinus Torvalds lock_buffer(bh); 21211da177e4SLinus Torvalds mark_buffer_async_read(bh); 21221da177e4SLinus Torvalds } 21231da177e4SLinus Torvalds 21241da177e4SLinus Torvalds /* 21251da177e4SLinus Torvalds * Stage 3: start the IO. Check for uptodateness 21261da177e4SLinus Torvalds * inside the buffer lock in case another process reading 21271da177e4SLinus Torvalds * the underlying blockdev brought it uptodate (the sct fix). 21281da177e4SLinus Torvalds */ 21291da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 21301da177e4SLinus Torvalds bh = arr[i]; 21311da177e4SLinus Torvalds if (buffer_uptodate(bh)) 21321da177e4SLinus Torvalds end_buffer_async_read(bh, 1); 21331da177e4SLinus Torvalds else 21341da177e4SLinus Torvalds submit_bh(READ, bh); 21351da177e4SLinus Torvalds } 21361da177e4SLinus Torvalds return 0; 21371da177e4SLinus Torvalds } 21381da177e4SLinus Torvalds 21391da177e4SLinus Torvalds /* utility function for filesystems that need to do work on expanding 21401da177e4SLinus Torvalds * truncates. Uses prepare/commit_write to allow the filesystem to 21411da177e4SLinus Torvalds * deal with the hole. 21421da177e4SLinus Torvalds */ 21431da177e4SLinus Torvalds int generic_cont_expand(struct inode *inode, loff_t size) 21441da177e4SLinus Torvalds { 21451da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 21461da177e4SLinus Torvalds struct page *page; 21471da177e4SLinus Torvalds unsigned long index, offset, limit; 21481da177e4SLinus Torvalds int err; 21491da177e4SLinus Torvalds 21501da177e4SLinus Torvalds err = -EFBIG; 21511da177e4SLinus Torvalds limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 21521da177e4SLinus Torvalds if (limit != RLIM_INFINITY && size > (loff_t)limit) { 21531da177e4SLinus Torvalds send_sig(SIGXFSZ, current, 0); 21541da177e4SLinus Torvalds goto out; 21551da177e4SLinus Torvalds } 21561da177e4SLinus Torvalds if (size > inode->i_sb->s_maxbytes) 21571da177e4SLinus Torvalds goto out; 21581da177e4SLinus Torvalds 21591da177e4SLinus Torvalds offset = (size & (PAGE_CACHE_SIZE-1)); /* Within page */ 21601da177e4SLinus Torvalds 21611da177e4SLinus Torvalds /* ugh. in prepare/commit_write, if from==to==start of block, we 21621da177e4SLinus Torvalds ** skip the prepare. make sure we never send an offset for the start 21631da177e4SLinus Torvalds ** of a block 21641da177e4SLinus Torvalds */ 21651da177e4SLinus Torvalds if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) { 21661da177e4SLinus Torvalds offset++; 21671da177e4SLinus Torvalds } 21681da177e4SLinus Torvalds index = size >> PAGE_CACHE_SHIFT; 21691da177e4SLinus Torvalds err = -ENOMEM; 21701da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 21711da177e4SLinus Torvalds if (!page) 21721da177e4SLinus Torvalds goto out; 21731da177e4SLinus Torvalds err = mapping->a_ops->prepare_write(NULL, page, offset, offset); 21741da177e4SLinus Torvalds if (!err) { 21751da177e4SLinus Torvalds err = mapping->a_ops->commit_write(NULL, page, offset, offset); 21761da177e4SLinus Torvalds } 21771da177e4SLinus Torvalds unlock_page(page); 21781da177e4SLinus Torvalds page_cache_release(page); 21791da177e4SLinus Torvalds if (err > 0) 21801da177e4SLinus Torvalds err = 0; 21811da177e4SLinus Torvalds out: 21821da177e4SLinus Torvalds return err; 21831da177e4SLinus Torvalds } 21841da177e4SLinus Torvalds 21851da177e4SLinus Torvalds /* 21861da177e4SLinus Torvalds * For moronic filesystems that do not allow holes in file. 21871da177e4SLinus Torvalds * We may have to extend the file. 21881da177e4SLinus Torvalds */ 21891da177e4SLinus Torvalds 21901da177e4SLinus Torvalds int cont_prepare_write(struct page *page, unsigned offset, 21911da177e4SLinus Torvalds unsigned to, get_block_t *get_block, loff_t *bytes) 21921da177e4SLinus Torvalds { 21931da177e4SLinus Torvalds struct address_space *mapping = page->mapping; 21941da177e4SLinus Torvalds struct inode *inode = mapping->host; 21951da177e4SLinus Torvalds struct page *new_page; 21961da177e4SLinus Torvalds pgoff_t pgpos; 21971da177e4SLinus Torvalds long status; 21981da177e4SLinus Torvalds unsigned zerofrom; 21991da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 22001da177e4SLinus Torvalds void *kaddr; 22011da177e4SLinus Torvalds 22021da177e4SLinus Torvalds while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) { 22031da177e4SLinus Torvalds status = -ENOMEM; 22041da177e4SLinus Torvalds new_page = grab_cache_page(mapping, pgpos); 22051da177e4SLinus Torvalds if (!new_page) 22061da177e4SLinus Torvalds goto out; 22071da177e4SLinus Torvalds /* we might sleep */ 22081da177e4SLinus Torvalds if (*bytes>>PAGE_CACHE_SHIFT != pgpos) { 22091da177e4SLinus Torvalds unlock_page(new_page); 22101da177e4SLinus Torvalds page_cache_release(new_page); 22111da177e4SLinus Torvalds continue; 22121da177e4SLinus Torvalds } 22131da177e4SLinus Torvalds zerofrom = *bytes & ~PAGE_CACHE_MASK; 22141da177e4SLinus Torvalds if (zerofrom & (blocksize-1)) { 22151da177e4SLinus Torvalds *bytes |= (blocksize-1); 22161da177e4SLinus Torvalds (*bytes)++; 22171da177e4SLinus Torvalds } 22181da177e4SLinus Torvalds status = __block_prepare_write(inode, new_page, zerofrom, 22191da177e4SLinus Torvalds PAGE_CACHE_SIZE, get_block); 22201da177e4SLinus Torvalds if (status) 22211da177e4SLinus Torvalds goto out_unmap; 22221da177e4SLinus Torvalds kaddr = kmap_atomic(new_page, KM_USER0); 22231da177e4SLinus Torvalds memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom); 22241da177e4SLinus Torvalds flush_dcache_page(new_page); 22251da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 22261da177e4SLinus Torvalds generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE); 22271da177e4SLinus Torvalds unlock_page(new_page); 22281da177e4SLinus Torvalds page_cache_release(new_page); 22291da177e4SLinus Torvalds } 22301da177e4SLinus Torvalds 22311da177e4SLinus Torvalds if (page->index < pgpos) { 22321da177e4SLinus Torvalds /* completely inside the area */ 22331da177e4SLinus Torvalds zerofrom = offset; 22341da177e4SLinus Torvalds } else { 22351da177e4SLinus Torvalds /* page covers the boundary, find the boundary offset */ 22361da177e4SLinus Torvalds zerofrom = *bytes & ~PAGE_CACHE_MASK; 22371da177e4SLinus Torvalds 22381da177e4SLinus Torvalds /* if we will expand the thing last block will be filled */ 22391da177e4SLinus Torvalds if (to > zerofrom && (zerofrom & (blocksize-1))) { 22401da177e4SLinus Torvalds *bytes |= (blocksize-1); 22411da177e4SLinus Torvalds (*bytes)++; 22421da177e4SLinus Torvalds } 22431da177e4SLinus Torvalds 22441da177e4SLinus Torvalds /* starting below the boundary? Nothing to zero out */ 22451da177e4SLinus Torvalds if (offset <= zerofrom) 22461da177e4SLinus Torvalds zerofrom = offset; 22471da177e4SLinus Torvalds } 22481da177e4SLinus Torvalds status = __block_prepare_write(inode, page, zerofrom, to, get_block); 22491da177e4SLinus Torvalds if (status) 22501da177e4SLinus Torvalds goto out1; 22511da177e4SLinus Torvalds if (zerofrom < offset) { 22521da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 22531da177e4SLinus Torvalds memset(kaddr+zerofrom, 0, offset-zerofrom); 22541da177e4SLinus Torvalds flush_dcache_page(page); 22551da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 22561da177e4SLinus Torvalds __block_commit_write(inode, page, zerofrom, offset); 22571da177e4SLinus Torvalds } 22581da177e4SLinus Torvalds return 0; 22591da177e4SLinus Torvalds out1: 22601da177e4SLinus Torvalds ClearPageUptodate(page); 22611da177e4SLinus Torvalds return status; 22621da177e4SLinus Torvalds 22631da177e4SLinus Torvalds out_unmap: 22641da177e4SLinus Torvalds ClearPageUptodate(new_page); 22651da177e4SLinus Torvalds unlock_page(new_page); 22661da177e4SLinus Torvalds page_cache_release(new_page); 22671da177e4SLinus Torvalds out: 22681da177e4SLinus Torvalds return status; 22691da177e4SLinus Torvalds } 22701da177e4SLinus Torvalds 22711da177e4SLinus Torvalds int block_prepare_write(struct page *page, unsigned from, unsigned to, 22721da177e4SLinus Torvalds get_block_t *get_block) 22731da177e4SLinus Torvalds { 22741da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 22751da177e4SLinus Torvalds int err = __block_prepare_write(inode, page, from, to, get_block); 22761da177e4SLinus Torvalds if (err) 22771da177e4SLinus Torvalds ClearPageUptodate(page); 22781da177e4SLinus Torvalds return err; 22791da177e4SLinus Torvalds } 22801da177e4SLinus Torvalds 22811da177e4SLinus Torvalds int block_commit_write(struct page *page, unsigned from, unsigned to) 22821da177e4SLinus Torvalds { 22831da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 22841da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 22851da177e4SLinus Torvalds return 0; 22861da177e4SLinus Torvalds } 22871da177e4SLinus Torvalds 22881da177e4SLinus Torvalds int generic_commit_write(struct file *file, struct page *page, 22891da177e4SLinus Torvalds unsigned from, unsigned to) 22901da177e4SLinus Torvalds { 22911da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 22921da177e4SLinus Torvalds loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; 22931da177e4SLinus Torvalds __block_commit_write(inode,page,from,to); 22941da177e4SLinus Torvalds /* 22951da177e4SLinus Torvalds * No need to use i_size_read() here, the i_size 22961da177e4SLinus Torvalds * cannot change under us because we hold i_sem. 22971da177e4SLinus Torvalds */ 22981da177e4SLinus Torvalds if (pos > inode->i_size) { 22991da177e4SLinus Torvalds i_size_write(inode, pos); 23001da177e4SLinus Torvalds mark_inode_dirty(inode); 23011da177e4SLinus Torvalds } 23021da177e4SLinus Torvalds return 0; 23031da177e4SLinus Torvalds } 23041da177e4SLinus Torvalds 23051da177e4SLinus Torvalds 23061da177e4SLinus Torvalds /* 23071da177e4SLinus Torvalds * nobh_prepare_write()'s prereads are special: the buffer_heads are freed 23081da177e4SLinus Torvalds * immediately, while under the page lock. So it needs a special end_io 23091da177e4SLinus Torvalds * handler which does not touch the bh after unlocking it. 23101da177e4SLinus Torvalds * 23111da177e4SLinus Torvalds * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but 23121da177e4SLinus Torvalds * a race there is benign: unlock_buffer() only use the bh's address for 23131da177e4SLinus Torvalds * hashing after unlocking the buffer, so it doesn't actually touch the bh 23141da177e4SLinus Torvalds * itself. 23151da177e4SLinus Torvalds */ 23161da177e4SLinus Torvalds static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) 23171da177e4SLinus Torvalds { 23181da177e4SLinus Torvalds if (uptodate) { 23191da177e4SLinus Torvalds set_buffer_uptodate(bh); 23201da177e4SLinus Torvalds } else { 23211da177e4SLinus Torvalds /* This happens, due to failed READA attempts. */ 23221da177e4SLinus Torvalds clear_buffer_uptodate(bh); 23231da177e4SLinus Torvalds } 23241da177e4SLinus Torvalds unlock_buffer(bh); 23251da177e4SLinus Torvalds } 23261da177e4SLinus Torvalds 23271da177e4SLinus Torvalds /* 23281da177e4SLinus Torvalds * On entry, the page is fully not uptodate. 23291da177e4SLinus Torvalds * On exit the page is fully uptodate in the areas outside (from,to) 23301da177e4SLinus Torvalds */ 23311da177e4SLinus Torvalds int nobh_prepare_write(struct page *page, unsigned from, unsigned to, 23321da177e4SLinus Torvalds get_block_t *get_block) 23331da177e4SLinus Torvalds { 23341da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 23351da177e4SLinus Torvalds const unsigned blkbits = inode->i_blkbits; 23361da177e4SLinus Torvalds const unsigned blocksize = 1 << blkbits; 23371da177e4SLinus Torvalds struct buffer_head map_bh; 23381da177e4SLinus Torvalds struct buffer_head *read_bh[MAX_BUF_PER_PAGE]; 23391da177e4SLinus Torvalds unsigned block_in_page; 23401da177e4SLinus Torvalds unsigned block_start; 23411da177e4SLinus Torvalds sector_t block_in_file; 23421da177e4SLinus Torvalds char *kaddr; 23431da177e4SLinus Torvalds int nr_reads = 0; 23441da177e4SLinus Torvalds int i; 23451da177e4SLinus Torvalds int ret = 0; 23461da177e4SLinus Torvalds int is_mapped_to_disk = 1; 23471da177e4SLinus Torvalds int dirtied_it = 0; 23481da177e4SLinus Torvalds 23491da177e4SLinus Torvalds if (PageMappedToDisk(page)) 23501da177e4SLinus Torvalds return 0; 23511da177e4SLinus Torvalds 23521da177e4SLinus Torvalds block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); 23531da177e4SLinus Torvalds map_bh.b_page = page; 23541da177e4SLinus Torvalds 23551da177e4SLinus Torvalds /* 23561da177e4SLinus Torvalds * We loop across all blocks in the page, whether or not they are 23571da177e4SLinus Torvalds * part of the affected region. This is so we can discover if the 23581da177e4SLinus Torvalds * page is fully mapped-to-disk. 23591da177e4SLinus Torvalds */ 23601da177e4SLinus Torvalds for (block_start = 0, block_in_page = 0; 23611da177e4SLinus Torvalds block_start < PAGE_CACHE_SIZE; 23621da177e4SLinus Torvalds block_in_page++, block_start += blocksize) { 23631da177e4SLinus Torvalds unsigned block_end = block_start + blocksize; 23641da177e4SLinus Torvalds int create; 23651da177e4SLinus Torvalds 23661da177e4SLinus Torvalds map_bh.b_state = 0; 23671da177e4SLinus Torvalds create = 1; 23681da177e4SLinus Torvalds if (block_start >= to) 23691da177e4SLinus Torvalds create = 0; 23701da177e4SLinus Torvalds ret = get_block(inode, block_in_file + block_in_page, 23711da177e4SLinus Torvalds &map_bh, create); 23721da177e4SLinus Torvalds if (ret) 23731da177e4SLinus Torvalds goto failed; 23741da177e4SLinus Torvalds if (!buffer_mapped(&map_bh)) 23751da177e4SLinus Torvalds is_mapped_to_disk = 0; 23761da177e4SLinus Torvalds if (buffer_new(&map_bh)) 23771da177e4SLinus Torvalds unmap_underlying_metadata(map_bh.b_bdev, 23781da177e4SLinus Torvalds map_bh.b_blocknr); 23791da177e4SLinus Torvalds if (PageUptodate(page)) 23801da177e4SLinus Torvalds continue; 23811da177e4SLinus Torvalds if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) { 23821da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 23831da177e4SLinus Torvalds if (block_start < from) { 23841da177e4SLinus Torvalds memset(kaddr+block_start, 0, from-block_start); 23851da177e4SLinus Torvalds dirtied_it = 1; 23861da177e4SLinus Torvalds } 23871da177e4SLinus Torvalds if (block_end > to) { 23881da177e4SLinus Torvalds memset(kaddr + to, 0, block_end - to); 23891da177e4SLinus Torvalds dirtied_it = 1; 23901da177e4SLinus Torvalds } 23911da177e4SLinus Torvalds flush_dcache_page(page); 23921da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 23931da177e4SLinus Torvalds continue; 23941da177e4SLinus Torvalds } 23951da177e4SLinus Torvalds if (buffer_uptodate(&map_bh)) 23961da177e4SLinus Torvalds continue; /* reiserfs does this */ 23971da177e4SLinus Torvalds if (block_start < from || block_end > to) { 23981da177e4SLinus Torvalds struct buffer_head *bh = alloc_buffer_head(GFP_NOFS); 23991da177e4SLinus Torvalds 24001da177e4SLinus Torvalds if (!bh) { 24011da177e4SLinus Torvalds ret = -ENOMEM; 24021da177e4SLinus Torvalds goto failed; 24031da177e4SLinus Torvalds } 24041da177e4SLinus Torvalds bh->b_state = map_bh.b_state; 24051da177e4SLinus Torvalds atomic_set(&bh->b_count, 0); 24061da177e4SLinus Torvalds bh->b_this_page = NULL; 24071da177e4SLinus Torvalds bh->b_page = page; 24081da177e4SLinus Torvalds bh->b_blocknr = map_bh.b_blocknr; 24091da177e4SLinus Torvalds bh->b_size = blocksize; 24101da177e4SLinus Torvalds bh->b_data = (char *)(long)block_start; 24111da177e4SLinus Torvalds bh->b_bdev = map_bh.b_bdev; 24121da177e4SLinus Torvalds bh->b_private = NULL; 24131da177e4SLinus Torvalds read_bh[nr_reads++] = bh; 24141da177e4SLinus Torvalds } 24151da177e4SLinus Torvalds } 24161da177e4SLinus Torvalds 24171da177e4SLinus Torvalds if (nr_reads) { 24181da177e4SLinus Torvalds struct buffer_head *bh; 24191da177e4SLinus Torvalds 24201da177e4SLinus Torvalds /* 24211da177e4SLinus Torvalds * The page is locked, so these buffers are protected from 24221da177e4SLinus Torvalds * any VM or truncate activity. Hence we don't need to care 24231da177e4SLinus Torvalds * for the buffer_head refcounts. 24241da177e4SLinus Torvalds */ 24251da177e4SLinus Torvalds for (i = 0; i < nr_reads; i++) { 24261da177e4SLinus Torvalds bh = read_bh[i]; 24271da177e4SLinus Torvalds lock_buffer(bh); 24281da177e4SLinus Torvalds bh->b_end_io = end_buffer_read_nobh; 24291da177e4SLinus Torvalds submit_bh(READ, bh); 24301da177e4SLinus Torvalds } 24311da177e4SLinus Torvalds for (i = 0; i < nr_reads; i++) { 24321da177e4SLinus Torvalds bh = read_bh[i]; 24331da177e4SLinus Torvalds wait_on_buffer(bh); 24341da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 24351da177e4SLinus Torvalds ret = -EIO; 24361da177e4SLinus Torvalds free_buffer_head(bh); 24371da177e4SLinus Torvalds read_bh[i] = NULL; 24381da177e4SLinus Torvalds } 24391da177e4SLinus Torvalds if (ret) 24401da177e4SLinus Torvalds goto failed; 24411da177e4SLinus Torvalds } 24421da177e4SLinus Torvalds 24431da177e4SLinus Torvalds if (is_mapped_to_disk) 24441da177e4SLinus Torvalds SetPageMappedToDisk(page); 24451da177e4SLinus Torvalds SetPageUptodate(page); 24461da177e4SLinus Torvalds 24471da177e4SLinus Torvalds /* 24481da177e4SLinus Torvalds * Setting the page dirty here isn't necessary for the prepare_write 24491da177e4SLinus Torvalds * function - commit_write will do that. But if/when this function is 24501da177e4SLinus Torvalds * used within the pagefault handler to ensure that all mmapped pages 24511da177e4SLinus Torvalds * have backing space in the filesystem, we will need to dirty the page 24521da177e4SLinus Torvalds * if its contents were altered. 24531da177e4SLinus Torvalds */ 24541da177e4SLinus Torvalds if (dirtied_it) 24551da177e4SLinus Torvalds set_page_dirty(page); 24561da177e4SLinus Torvalds 24571da177e4SLinus Torvalds return 0; 24581da177e4SLinus Torvalds 24591da177e4SLinus Torvalds failed: 24601da177e4SLinus Torvalds for (i = 0; i < nr_reads; i++) { 24611da177e4SLinus Torvalds if (read_bh[i]) 24621da177e4SLinus Torvalds free_buffer_head(read_bh[i]); 24631da177e4SLinus Torvalds } 24641da177e4SLinus Torvalds 24651da177e4SLinus Torvalds /* 24661da177e4SLinus Torvalds * Error recovery is pretty slack. Clear the page and mark it dirty 24671da177e4SLinus Torvalds * so we'll later zero out any blocks which _were_ allocated. 24681da177e4SLinus Torvalds */ 24691da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 24701da177e4SLinus Torvalds memset(kaddr, 0, PAGE_CACHE_SIZE); 24711da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 24721da177e4SLinus Torvalds SetPageUptodate(page); 24731da177e4SLinus Torvalds set_page_dirty(page); 24741da177e4SLinus Torvalds return ret; 24751da177e4SLinus Torvalds } 24761da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_prepare_write); 24771da177e4SLinus Torvalds 24781da177e4SLinus Torvalds int nobh_commit_write(struct file *file, struct page *page, 24791da177e4SLinus Torvalds unsigned from, unsigned to) 24801da177e4SLinus Torvalds { 24811da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 24821da177e4SLinus Torvalds loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; 24831da177e4SLinus Torvalds 24841da177e4SLinus Torvalds set_page_dirty(page); 24851da177e4SLinus Torvalds if (pos > inode->i_size) { 24861da177e4SLinus Torvalds i_size_write(inode, pos); 24871da177e4SLinus Torvalds mark_inode_dirty(inode); 24881da177e4SLinus Torvalds } 24891da177e4SLinus Torvalds return 0; 24901da177e4SLinus Torvalds } 24911da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_commit_write); 24921da177e4SLinus Torvalds 24931da177e4SLinus Torvalds /* 24941da177e4SLinus Torvalds * nobh_writepage() - based on block_full_write_page() except 24951da177e4SLinus Torvalds * that it tries to operate without attaching bufferheads to 24961da177e4SLinus Torvalds * the page. 24971da177e4SLinus Torvalds */ 24981da177e4SLinus Torvalds int nobh_writepage(struct page *page, get_block_t *get_block, 24991da177e4SLinus Torvalds struct writeback_control *wbc) 25001da177e4SLinus Torvalds { 25011da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 25021da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 25031da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 25041da177e4SLinus Torvalds unsigned offset; 25051da177e4SLinus Torvalds void *kaddr; 25061da177e4SLinus Torvalds int ret; 25071da177e4SLinus Torvalds 25081da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 25091da177e4SLinus Torvalds if (page->index < end_index) 25101da177e4SLinus Torvalds goto out; 25111da177e4SLinus Torvalds 25121da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 25131da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 25141da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 25151da177e4SLinus Torvalds /* 25161da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 25171da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 25181da177e4SLinus Torvalds * freeable here, so the page does not leak. 25191da177e4SLinus Torvalds */ 25201da177e4SLinus Torvalds #if 0 25211da177e4SLinus Torvalds /* Not really sure about this - do we need this ? */ 25221da177e4SLinus Torvalds if (page->mapping->a_ops->invalidatepage) 25231da177e4SLinus Torvalds page->mapping->a_ops->invalidatepage(page, offset); 25241da177e4SLinus Torvalds #endif 25251da177e4SLinus Torvalds unlock_page(page); 25261da177e4SLinus Torvalds return 0; /* don't care */ 25271da177e4SLinus Torvalds } 25281da177e4SLinus Torvalds 25291da177e4SLinus Torvalds /* 25301da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 25311da177e4SLinus Torvalds * writepage invocation because it may be mmapped. "A file is mapped 25321da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 25331da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 25341da177e4SLinus Torvalds * writes to that region are not written out to the file." 25351da177e4SLinus Torvalds */ 25361da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 25371da177e4SLinus Torvalds memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); 25381da177e4SLinus Torvalds flush_dcache_page(page); 25391da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 25401da177e4SLinus Torvalds out: 25411da177e4SLinus Torvalds ret = mpage_writepage(page, get_block, wbc); 25421da177e4SLinus Torvalds if (ret == -EAGAIN) 25431da177e4SLinus Torvalds ret = __block_write_full_page(inode, page, get_block, wbc); 25441da177e4SLinus Torvalds return ret; 25451da177e4SLinus Torvalds } 25461da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_writepage); 25471da177e4SLinus Torvalds 25481da177e4SLinus Torvalds /* 25491da177e4SLinus Torvalds * This function assumes that ->prepare_write() uses nobh_prepare_write(). 25501da177e4SLinus Torvalds */ 25511da177e4SLinus Torvalds int nobh_truncate_page(struct address_space *mapping, loff_t from) 25521da177e4SLinus Torvalds { 25531da177e4SLinus Torvalds struct inode *inode = mapping->host; 25541da177e4SLinus Torvalds unsigned blocksize = 1 << inode->i_blkbits; 25551da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 25561da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 25571da177e4SLinus Torvalds unsigned to; 25581da177e4SLinus Torvalds struct page *page; 25591da177e4SLinus Torvalds struct address_space_operations *a_ops = mapping->a_ops; 25601da177e4SLinus Torvalds char *kaddr; 25611da177e4SLinus Torvalds int ret = 0; 25621da177e4SLinus Torvalds 25631da177e4SLinus Torvalds if ((offset & (blocksize - 1)) == 0) 25641da177e4SLinus Torvalds goto out; 25651da177e4SLinus Torvalds 25661da177e4SLinus Torvalds ret = -ENOMEM; 25671da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 25681da177e4SLinus Torvalds if (!page) 25691da177e4SLinus Torvalds goto out; 25701da177e4SLinus Torvalds 25711da177e4SLinus Torvalds to = (offset + blocksize) & ~(blocksize - 1); 25721da177e4SLinus Torvalds ret = a_ops->prepare_write(NULL, page, offset, to); 25731da177e4SLinus Torvalds if (ret == 0) { 25741da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 25751da177e4SLinus Torvalds memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); 25761da177e4SLinus Torvalds flush_dcache_page(page); 25771da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 25781da177e4SLinus Torvalds set_page_dirty(page); 25791da177e4SLinus Torvalds } 25801da177e4SLinus Torvalds unlock_page(page); 25811da177e4SLinus Torvalds page_cache_release(page); 25821da177e4SLinus Torvalds out: 25831da177e4SLinus Torvalds return ret; 25841da177e4SLinus Torvalds } 25851da177e4SLinus Torvalds EXPORT_SYMBOL(nobh_truncate_page); 25861da177e4SLinus Torvalds 25871da177e4SLinus Torvalds int block_truncate_page(struct address_space *mapping, 25881da177e4SLinus Torvalds loff_t from, get_block_t *get_block) 25891da177e4SLinus Torvalds { 25901da177e4SLinus Torvalds pgoff_t index = from >> PAGE_CACHE_SHIFT; 25911da177e4SLinus Torvalds unsigned offset = from & (PAGE_CACHE_SIZE-1); 25921da177e4SLinus Torvalds unsigned blocksize; 25931da177e4SLinus Torvalds pgoff_t iblock; 25941da177e4SLinus Torvalds unsigned length, pos; 25951da177e4SLinus Torvalds struct inode *inode = mapping->host; 25961da177e4SLinus Torvalds struct page *page; 25971da177e4SLinus Torvalds struct buffer_head *bh; 25981da177e4SLinus Torvalds void *kaddr; 25991da177e4SLinus Torvalds int err; 26001da177e4SLinus Torvalds 26011da177e4SLinus Torvalds blocksize = 1 << inode->i_blkbits; 26021da177e4SLinus Torvalds length = offset & (blocksize - 1); 26031da177e4SLinus Torvalds 26041da177e4SLinus Torvalds /* Block boundary? Nothing to do */ 26051da177e4SLinus Torvalds if (!length) 26061da177e4SLinus Torvalds return 0; 26071da177e4SLinus Torvalds 26081da177e4SLinus Torvalds length = blocksize - length; 26091da177e4SLinus Torvalds iblock = index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 26101da177e4SLinus Torvalds 26111da177e4SLinus Torvalds page = grab_cache_page(mapping, index); 26121da177e4SLinus Torvalds err = -ENOMEM; 26131da177e4SLinus Torvalds if (!page) 26141da177e4SLinus Torvalds goto out; 26151da177e4SLinus Torvalds 26161da177e4SLinus Torvalds if (!page_has_buffers(page)) 26171da177e4SLinus Torvalds create_empty_buffers(page, blocksize, 0); 26181da177e4SLinus Torvalds 26191da177e4SLinus Torvalds /* Find the buffer that contains "offset" */ 26201da177e4SLinus Torvalds bh = page_buffers(page); 26211da177e4SLinus Torvalds pos = blocksize; 26221da177e4SLinus Torvalds while (offset >= pos) { 26231da177e4SLinus Torvalds bh = bh->b_this_page; 26241da177e4SLinus Torvalds iblock++; 26251da177e4SLinus Torvalds pos += blocksize; 26261da177e4SLinus Torvalds } 26271da177e4SLinus Torvalds 26281da177e4SLinus Torvalds err = 0; 26291da177e4SLinus Torvalds if (!buffer_mapped(bh)) { 26301da177e4SLinus Torvalds err = get_block(inode, iblock, bh, 0); 26311da177e4SLinus Torvalds if (err) 26321da177e4SLinus Torvalds goto unlock; 26331da177e4SLinus Torvalds /* unmapped? It's a hole - nothing to do */ 26341da177e4SLinus Torvalds if (!buffer_mapped(bh)) 26351da177e4SLinus Torvalds goto unlock; 26361da177e4SLinus Torvalds } 26371da177e4SLinus Torvalds 26381da177e4SLinus Torvalds /* Ok, it's mapped. Make sure it's up-to-date */ 26391da177e4SLinus Torvalds if (PageUptodate(page)) 26401da177e4SLinus Torvalds set_buffer_uptodate(bh); 26411da177e4SLinus Torvalds 26421da177e4SLinus Torvalds if (!buffer_uptodate(bh) && !buffer_delay(bh)) { 26431da177e4SLinus Torvalds err = -EIO; 26441da177e4SLinus Torvalds ll_rw_block(READ, 1, &bh); 26451da177e4SLinus Torvalds wait_on_buffer(bh); 26461da177e4SLinus Torvalds /* Uhhuh. Read error. Complain and punt. */ 26471da177e4SLinus Torvalds if (!buffer_uptodate(bh)) 26481da177e4SLinus Torvalds goto unlock; 26491da177e4SLinus Torvalds } 26501da177e4SLinus Torvalds 26511da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 26521da177e4SLinus Torvalds memset(kaddr + offset, 0, length); 26531da177e4SLinus Torvalds flush_dcache_page(page); 26541da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 26551da177e4SLinus Torvalds 26561da177e4SLinus Torvalds mark_buffer_dirty(bh); 26571da177e4SLinus Torvalds err = 0; 26581da177e4SLinus Torvalds 26591da177e4SLinus Torvalds unlock: 26601da177e4SLinus Torvalds unlock_page(page); 26611da177e4SLinus Torvalds page_cache_release(page); 26621da177e4SLinus Torvalds out: 26631da177e4SLinus Torvalds return err; 26641da177e4SLinus Torvalds } 26651da177e4SLinus Torvalds 26661da177e4SLinus Torvalds /* 26671da177e4SLinus Torvalds * The generic ->writepage function for buffer-backed address_spaces 26681da177e4SLinus Torvalds */ 26691da177e4SLinus Torvalds int block_write_full_page(struct page *page, get_block_t *get_block, 26701da177e4SLinus Torvalds struct writeback_control *wbc) 26711da177e4SLinus Torvalds { 26721da177e4SLinus Torvalds struct inode * const inode = page->mapping->host; 26731da177e4SLinus Torvalds loff_t i_size = i_size_read(inode); 26741da177e4SLinus Torvalds const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; 26751da177e4SLinus Torvalds unsigned offset; 26761da177e4SLinus Torvalds void *kaddr; 26771da177e4SLinus Torvalds 26781da177e4SLinus Torvalds /* Is the page fully inside i_size? */ 26791da177e4SLinus Torvalds if (page->index < end_index) 26801da177e4SLinus Torvalds return __block_write_full_page(inode, page, get_block, wbc); 26811da177e4SLinus Torvalds 26821da177e4SLinus Torvalds /* Is the page fully outside i_size? (truncate in progress) */ 26831da177e4SLinus Torvalds offset = i_size & (PAGE_CACHE_SIZE-1); 26841da177e4SLinus Torvalds if (page->index >= end_index+1 || !offset) { 26851da177e4SLinus Torvalds /* 26861da177e4SLinus Torvalds * The page may have dirty, unmapped buffers. For example, 26871da177e4SLinus Torvalds * they may have been added in ext3_writepage(). Make them 26881da177e4SLinus Torvalds * freeable here, so the page does not leak. 26891da177e4SLinus Torvalds */ 26901da177e4SLinus Torvalds block_invalidatepage(page, 0); 26911da177e4SLinus Torvalds unlock_page(page); 26921da177e4SLinus Torvalds return 0; /* don't care */ 26931da177e4SLinus Torvalds } 26941da177e4SLinus Torvalds 26951da177e4SLinus Torvalds /* 26961da177e4SLinus Torvalds * The page straddles i_size. It must be zeroed out on each and every 26971da177e4SLinus Torvalds * writepage invokation because it may be mmapped. "A file is mapped 26981da177e4SLinus Torvalds * in multiples of the page size. For a file that is not a multiple of 26991da177e4SLinus Torvalds * the page size, the remaining memory is zeroed when mapped, and 27001da177e4SLinus Torvalds * writes to that region are not written out to the file." 27011da177e4SLinus Torvalds */ 27021da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 27031da177e4SLinus Torvalds memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); 27041da177e4SLinus Torvalds flush_dcache_page(page); 27051da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 27061da177e4SLinus Torvalds return __block_write_full_page(inode, page, get_block, wbc); 27071da177e4SLinus Torvalds } 27081da177e4SLinus Torvalds 27091da177e4SLinus Torvalds sector_t generic_block_bmap(struct address_space *mapping, sector_t block, 27101da177e4SLinus Torvalds get_block_t *get_block) 27111da177e4SLinus Torvalds { 27121da177e4SLinus Torvalds struct buffer_head tmp; 27131da177e4SLinus Torvalds struct inode *inode = mapping->host; 27141da177e4SLinus Torvalds tmp.b_state = 0; 27151da177e4SLinus Torvalds tmp.b_blocknr = 0; 27161da177e4SLinus Torvalds get_block(inode, block, &tmp, 0); 27171da177e4SLinus Torvalds return tmp.b_blocknr; 27181da177e4SLinus Torvalds } 27191da177e4SLinus Torvalds 27201da177e4SLinus Torvalds static int end_bio_bh_io_sync(struct bio *bio, unsigned int bytes_done, int err) 27211da177e4SLinus Torvalds { 27221da177e4SLinus Torvalds struct buffer_head *bh = bio->bi_private; 27231da177e4SLinus Torvalds 27241da177e4SLinus Torvalds if (bio->bi_size) 27251da177e4SLinus Torvalds return 1; 27261da177e4SLinus Torvalds 27271da177e4SLinus Torvalds if (err == -EOPNOTSUPP) { 27281da177e4SLinus Torvalds set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); 27291da177e4SLinus Torvalds set_bit(BH_Eopnotsupp, &bh->b_state); 27301da177e4SLinus Torvalds } 27311da177e4SLinus Torvalds 27321da177e4SLinus Torvalds bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); 27331da177e4SLinus Torvalds bio_put(bio); 27341da177e4SLinus Torvalds return 0; 27351da177e4SLinus Torvalds } 27361da177e4SLinus Torvalds 27371da177e4SLinus Torvalds int submit_bh(int rw, struct buffer_head * bh) 27381da177e4SLinus Torvalds { 27391da177e4SLinus Torvalds struct bio *bio; 27401da177e4SLinus Torvalds int ret = 0; 27411da177e4SLinus Torvalds 27421da177e4SLinus Torvalds BUG_ON(!buffer_locked(bh)); 27431da177e4SLinus Torvalds BUG_ON(!buffer_mapped(bh)); 27441da177e4SLinus Torvalds BUG_ON(!bh->b_end_io); 27451da177e4SLinus Torvalds 27461da177e4SLinus Torvalds if (buffer_ordered(bh) && (rw == WRITE)) 27471da177e4SLinus Torvalds rw = WRITE_BARRIER; 27481da177e4SLinus Torvalds 27491da177e4SLinus Torvalds /* 27501da177e4SLinus Torvalds * Only clear out a write error when rewriting, should this 27511da177e4SLinus Torvalds * include WRITE_SYNC as well? 27521da177e4SLinus Torvalds */ 27531da177e4SLinus Torvalds if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER)) 27541da177e4SLinus Torvalds clear_buffer_write_io_error(bh); 27551da177e4SLinus Torvalds 27561da177e4SLinus Torvalds /* 27571da177e4SLinus Torvalds * from here on down, it's all bio -- do the initial mapping, 27581da177e4SLinus Torvalds * submit_bio -> generic_make_request may further map this bio around 27591da177e4SLinus Torvalds */ 27601da177e4SLinus Torvalds bio = bio_alloc(GFP_NOIO, 1); 27611da177e4SLinus Torvalds 27621da177e4SLinus Torvalds bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); 27631da177e4SLinus Torvalds bio->bi_bdev = bh->b_bdev; 27641da177e4SLinus Torvalds bio->bi_io_vec[0].bv_page = bh->b_page; 27651da177e4SLinus Torvalds bio->bi_io_vec[0].bv_len = bh->b_size; 27661da177e4SLinus Torvalds bio->bi_io_vec[0].bv_offset = bh_offset(bh); 27671da177e4SLinus Torvalds 27681da177e4SLinus Torvalds bio->bi_vcnt = 1; 27691da177e4SLinus Torvalds bio->bi_idx = 0; 27701da177e4SLinus Torvalds bio->bi_size = bh->b_size; 27711da177e4SLinus Torvalds 27721da177e4SLinus Torvalds bio->bi_end_io = end_bio_bh_io_sync; 27731da177e4SLinus Torvalds bio->bi_private = bh; 27741da177e4SLinus Torvalds 27751da177e4SLinus Torvalds bio_get(bio); 27761da177e4SLinus Torvalds submit_bio(rw, bio); 27771da177e4SLinus Torvalds 27781da177e4SLinus Torvalds if (bio_flagged(bio, BIO_EOPNOTSUPP)) 27791da177e4SLinus Torvalds ret = -EOPNOTSUPP; 27801da177e4SLinus Torvalds 27811da177e4SLinus Torvalds bio_put(bio); 27821da177e4SLinus Torvalds return ret; 27831da177e4SLinus Torvalds } 27841da177e4SLinus Torvalds 27851da177e4SLinus Torvalds /** 27861da177e4SLinus Torvalds * ll_rw_block: low-level access to block devices (DEPRECATED) 27871da177e4SLinus Torvalds * @rw: whether to %READ or %WRITE or maybe %READA (readahead) 27881da177e4SLinus Torvalds * @nr: number of &struct buffer_heads in the array 27891da177e4SLinus Torvalds * @bhs: array of pointers to &struct buffer_head 27901da177e4SLinus Torvalds * 27911da177e4SLinus Torvalds * ll_rw_block() takes an array of pointers to &struct buffer_heads, 27921da177e4SLinus Torvalds * and requests an I/O operation on them, either a %READ or a %WRITE. 27931da177e4SLinus Torvalds * The third %READA option is described in the documentation for 27941da177e4SLinus Torvalds * generic_make_request() which ll_rw_block() calls. 27951da177e4SLinus Torvalds * 27961da177e4SLinus Torvalds * This function drops any buffer that it cannot get a lock on (with the 27971da177e4SLinus Torvalds * BH_Lock state bit), any buffer that appears to be clean when doing a 27981da177e4SLinus Torvalds * write request, and any buffer that appears to be up-to-date when doing 27991da177e4SLinus Torvalds * read request. Further it marks as clean buffers that are processed for 28001da177e4SLinus Torvalds * writing (the buffer cache won't assume that they are actually clean until 28011da177e4SLinus Torvalds * the buffer gets unlocked). 28021da177e4SLinus Torvalds * 28031da177e4SLinus Torvalds * ll_rw_block sets b_end_io to simple completion handler that marks 28041da177e4SLinus Torvalds * the buffer up-to-date (if approriate), unlocks the buffer and wakes 28051da177e4SLinus Torvalds * any waiters. 28061da177e4SLinus Torvalds * 28071da177e4SLinus Torvalds * All of the buffers must be for the same device, and must also be a 28081da177e4SLinus Torvalds * multiple of the current approved size for the device. 28091da177e4SLinus Torvalds */ 28101da177e4SLinus Torvalds void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) 28111da177e4SLinus Torvalds { 28121da177e4SLinus Torvalds int i; 28131da177e4SLinus Torvalds 28141da177e4SLinus Torvalds for (i = 0; i < nr; i++) { 28151da177e4SLinus Torvalds struct buffer_head *bh = bhs[i]; 28161da177e4SLinus Torvalds 28171da177e4SLinus Torvalds if (test_set_buffer_locked(bh)) 28181da177e4SLinus Torvalds continue; 28191da177e4SLinus Torvalds 28201da177e4SLinus Torvalds get_bh(bh); 28211da177e4SLinus Torvalds if (rw == WRITE) { 28221da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 282376c3073aSakpm@osdl.org bh->b_end_io = end_buffer_write_sync; 28241da177e4SLinus Torvalds submit_bh(WRITE, bh); 28251da177e4SLinus Torvalds continue; 28261da177e4SLinus Torvalds } 28271da177e4SLinus Torvalds } else { 28281da177e4SLinus Torvalds if (!buffer_uptodate(bh)) { 282976c3073aSakpm@osdl.org bh->b_end_io = end_buffer_read_sync; 28301da177e4SLinus Torvalds submit_bh(rw, bh); 28311da177e4SLinus Torvalds continue; 28321da177e4SLinus Torvalds } 28331da177e4SLinus Torvalds } 28341da177e4SLinus Torvalds unlock_buffer(bh); 28351da177e4SLinus Torvalds put_bh(bh); 28361da177e4SLinus Torvalds } 28371da177e4SLinus Torvalds } 28381da177e4SLinus Torvalds 28391da177e4SLinus Torvalds /* 28401da177e4SLinus Torvalds * For a data-integrity writeout, we need to wait upon any in-progress I/O 28411da177e4SLinus Torvalds * and then start new I/O and then wait upon it. The caller must have a ref on 28421da177e4SLinus Torvalds * the buffer_head. 28431da177e4SLinus Torvalds */ 28441da177e4SLinus Torvalds int sync_dirty_buffer(struct buffer_head *bh) 28451da177e4SLinus Torvalds { 28461da177e4SLinus Torvalds int ret = 0; 28471da177e4SLinus Torvalds 28481da177e4SLinus Torvalds WARN_ON(atomic_read(&bh->b_count) < 1); 28491da177e4SLinus Torvalds lock_buffer(bh); 28501da177e4SLinus Torvalds if (test_clear_buffer_dirty(bh)) { 28511da177e4SLinus Torvalds get_bh(bh); 28521da177e4SLinus Torvalds bh->b_end_io = end_buffer_write_sync; 28531da177e4SLinus Torvalds ret = submit_bh(WRITE, bh); 28541da177e4SLinus Torvalds wait_on_buffer(bh); 28551da177e4SLinus Torvalds if (buffer_eopnotsupp(bh)) { 28561da177e4SLinus Torvalds clear_buffer_eopnotsupp(bh); 28571da177e4SLinus Torvalds ret = -EOPNOTSUPP; 28581da177e4SLinus Torvalds } 28591da177e4SLinus Torvalds if (!ret && !buffer_uptodate(bh)) 28601da177e4SLinus Torvalds ret = -EIO; 28611da177e4SLinus Torvalds } else { 28621da177e4SLinus Torvalds unlock_buffer(bh); 28631da177e4SLinus Torvalds } 28641da177e4SLinus Torvalds return ret; 28651da177e4SLinus Torvalds } 28661da177e4SLinus Torvalds 28671da177e4SLinus Torvalds /* 28681da177e4SLinus Torvalds * try_to_free_buffers() checks if all the buffers on this particular page 28691da177e4SLinus Torvalds * are unused, and releases them if so. 28701da177e4SLinus Torvalds * 28711da177e4SLinus Torvalds * Exclusion against try_to_free_buffers may be obtained by either 28721da177e4SLinus Torvalds * locking the page or by holding its mapping's private_lock. 28731da177e4SLinus Torvalds * 28741da177e4SLinus Torvalds * If the page is dirty but all the buffers are clean then we need to 28751da177e4SLinus Torvalds * be sure to mark the page clean as well. This is because the page 28761da177e4SLinus Torvalds * may be against a block device, and a later reattachment of buffers 28771da177e4SLinus Torvalds * to a dirty page will set *all* buffers dirty. Which would corrupt 28781da177e4SLinus Torvalds * filesystem data on the same device. 28791da177e4SLinus Torvalds * 28801da177e4SLinus Torvalds * The same applies to regular filesystem pages: if all the buffers are 28811da177e4SLinus Torvalds * clean then we set the page clean and proceed. To do that, we require 28821da177e4SLinus Torvalds * total exclusion from __set_page_dirty_buffers(). That is obtained with 28831da177e4SLinus Torvalds * private_lock. 28841da177e4SLinus Torvalds * 28851da177e4SLinus Torvalds * try_to_free_buffers() is non-blocking. 28861da177e4SLinus Torvalds */ 28871da177e4SLinus Torvalds static inline int buffer_busy(struct buffer_head *bh) 28881da177e4SLinus Torvalds { 28891da177e4SLinus Torvalds return atomic_read(&bh->b_count) | 28901da177e4SLinus Torvalds (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); 28911da177e4SLinus Torvalds } 28921da177e4SLinus Torvalds 28931da177e4SLinus Torvalds static int 28941da177e4SLinus Torvalds drop_buffers(struct page *page, struct buffer_head **buffers_to_free) 28951da177e4SLinus Torvalds { 28961da177e4SLinus Torvalds struct buffer_head *head = page_buffers(page); 28971da177e4SLinus Torvalds struct buffer_head *bh; 28981da177e4SLinus Torvalds 28991da177e4SLinus Torvalds bh = head; 29001da177e4SLinus Torvalds do { 2901de7d5a3bSakpm@osdl.org if (buffer_write_io_error(bh) && page->mapping) 29021da177e4SLinus Torvalds set_bit(AS_EIO, &page->mapping->flags); 29031da177e4SLinus Torvalds if (buffer_busy(bh)) 29041da177e4SLinus Torvalds goto failed; 29051da177e4SLinus Torvalds bh = bh->b_this_page; 29061da177e4SLinus Torvalds } while (bh != head); 29071da177e4SLinus Torvalds 29081da177e4SLinus Torvalds do { 29091da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 29101da177e4SLinus Torvalds 29111da177e4SLinus Torvalds if (!list_empty(&bh->b_assoc_buffers)) 29121da177e4SLinus Torvalds __remove_assoc_queue(bh); 29131da177e4SLinus Torvalds bh = next; 29141da177e4SLinus Torvalds } while (bh != head); 29151da177e4SLinus Torvalds *buffers_to_free = head; 29161da177e4SLinus Torvalds __clear_page_buffers(page); 29171da177e4SLinus Torvalds return 1; 29181da177e4SLinus Torvalds failed: 29191da177e4SLinus Torvalds return 0; 29201da177e4SLinus Torvalds } 29211da177e4SLinus Torvalds 29221da177e4SLinus Torvalds int try_to_free_buffers(struct page *page) 29231da177e4SLinus Torvalds { 29241da177e4SLinus Torvalds struct address_space * const mapping = page->mapping; 29251da177e4SLinus Torvalds struct buffer_head *buffers_to_free = NULL; 29261da177e4SLinus Torvalds int ret = 0; 29271da177e4SLinus Torvalds 29281da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 29291da177e4SLinus Torvalds if (PageWriteback(page)) 29301da177e4SLinus Torvalds return 0; 29311da177e4SLinus Torvalds 29321da177e4SLinus Torvalds if (mapping == NULL) { /* can this still happen? */ 29331da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 29341da177e4SLinus Torvalds goto out; 29351da177e4SLinus Torvalds } 29361da177e4SLinus Torvalds 29371da177e4SLinus Torvalds spin_lock(&mapping->private_lock); 29381da177e4SLinus Torvalds ret = drop_buffers(page, &buffers_to_free); 29391da177e4SLinus Torvalds if (ret) { 29401da177e4SLinus Torvalds /* 29411da177e4SLinus Torvalds * If the filesystem writes its buffers by hand (eg ext3) 29421da177e4SLinus Torvalds * then we can have clean buffers against a dirty page. We 29431da177e4SLinus Torvalds * clean the page here; otherwise later reattachment of buffers 29441da177e4SLinus Torvalds * could encounter a non-uptodate page, which is unresolvable. 29451da177e4SLinus Torvalds * This only applies in the rare case where try_to_free_buffers 29461da177e4SLinus Torvalds * succeeds but the page is not freed. 29471da177e4SLinus Torvalds */ 29481da177e4SLinus Torvalds clear_page_dirty(page); 29491da177e4SLinus Torvalds } 29501da177e4SLinus Torvalds spin_unlock(&mapping->private_lock); 29511da177e4SLinus Torvalds out: 29521da177e4SLinus Torvalds if (buffers_to_free) { 29531da177e4SLinus Torvalds struct buffer_head *bh = buffers_to_free; 29541da177e4SLinus Torvalds 29551da177e4SLinus Torvalds do { 29561da177e4SLinus Torvalds struct buffer_head *next = bh->b_this_page; 29571da177e4SLinus Torvalds free_buffer_head(bh); 29581da177e4SLinus Torvalds bh = next; 29591da177e4SLinus Torvalds } while (bh != buffers_to_free); 29601da177e4SLinus Torvalds } 29611da177e4SLinus Torvalds return ret; 29621da177e4SLinus Torvalds } 29631da177e4SLinus Torvalds EXPORT_SYMBOL(try_to_free_buffers); 29641da177e4SLinus Torvalds 29651da177e4SLinus Torvalds int block_sync_page(struct page *page) 29661da177e4SLinus Torvalds { 29671da177e4SLinus Torvalds struct address_space *mapping; 29681da177e4SLinus Torvalds 29691da177e4SLinus Torvalds smp_mb(); 29701da177e4SLinus Torvalds mapping = page_mapping(page); 29711da177e4SLinus Torvalds if (mapping) 29721da177e4SLinus Torvalds blk_run_backing_dev(mapping->backing_dev_info, page); 29731da177e4SLinus Torvalds return 0; 29741da177e4SLinus Torvalds } 29751da177e4SLinus Torvalds 29761da177e4SLinus Torvalds /* 29771da177e4SLinus Torvalds * There are no bdflush tunables left. But distributions are 29781da177e4SLinus Torvalds * still running obsolete flush daemons, so we terminate them here. 29791da177e4SLinus Torvalds * 29801da177e4SLinus Torvalds * Use of bdflush() is deprecated and will be removed in a future kernel. 29811da177e4SLinus Torvalds * The `pdflush' kernel threads fully replace bdflush daemons and this call. 29821da177e4SLinus Torvalds */ 29831da177e4SLinus Torvalds asmlinkage long sys_bdflush(int func, long data) 29841da177e4SLinus Torvalds { 29851da177e4SLinus Torvalds static int msg_count; 29861da177e4SLinus Torvalds 29871da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 29881da177e4SLinus Torvalds return -EPERM; 29891da177e4SLinus Torvalds 29901da177e4SLinus Torvalds if (msg_count < 5) { 29911da177e4SLinus Torvalds msg_count++; 29921da177e4SLinus Torvalds printk(KERN_INFO 29931da177e4SLinus Torvalds "warning: process `%s' used the obsolete bdflush" 29941da177e4SLinus Torvalds " system call\n", current->comm); 29951da177e4SLinus Torvalds printk(KERN_INFO "Fix your initscripts?\n"); 29961da177e4SLinus Torvalds } 29971da177e4SLinus Torvalds 29981da177e4SLinus Torvalds if (func == 1) 29991da177e4SLinus Torvalds do_exit(0); 30001da177e4SLinus Torvalds return 0; 30011da177e4SLinus Torvalds } 30021da177e4SLinus Torvalds 30031da177e4SLinus Torvalds /* 30041da177e4SLinus Torvalds * Buffer-head allocation 30051da177e4SLinus Torvalds */ 30061da177e4SLinus Torvalds static kmem_cache_t *bh_cachep; 30071da177e4SLinus Torvalds 30081da177e4SLinus Torvalds /* 30091da177e4SLinus Torvalds * Once the number of bh's in the machine exceeds this level, we start 30101da177e4SLinus Torvalds * stripping them in writeback. 30111da177e4SLinus Torvalds */ 30121da177e4SLinus Torvalds static int max_buffer_heads; 30131da177e4SLinus Torvalds 30141da177e4SLinus Torvalds int buffer_heads_over_limit; 30151da177e4SLinus Torvalds 30161da177e4SLinus Torvalds struct bh_accounting { 30171da177e4SLinus Torvalds int nr; /* Number of live bh's */ 30181da177e4SLinus Torvalds int ratelimit; /* Limit cacheline bouncing */ 30191da177e4SLinus Torvalds }; 30201da177e4SLinus Torvalds 30211da177e4SLinus Torvalds static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; 30221da177e4SLinus Torvalds 30231da177e4SLinus Torvalds static void recalc_bh_state(void) 30241da177e4SLinus Torvalds { 30251da177e4SLinus Torvalds int i; 30261da177e4SLinus Torvalds int tot = 0; 30271da177e4SLinus Torvalds 30281da177e4SLinus Torvalds if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) 30291da177e4SLinus Torvalds return; 30301da177e4SLinus Torvalds __get_cpu_var(bh_accounting).ratelimit = 0; 30311da177e4SLinus Torvalds for_each_cpu(i) 30321da177e4SLinus Torvalds tot += per_cpu(bh_accounting, i).nr; 30331da177e4SLinus Torvalds buffer_heads_over_limit = (tot > max_buffer_heads); 30341da177e4SLinus Torvalds } 30351da177e4SLinus Torvalds 30361da177e4SLinus Torvalds struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags) 30371da177e4SLinus Torvalds { 30381da177e4SLinus Torvalds struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags); 30391da177e4SLinus Torvalds if (ret) { 30401da177e4SLinus Torvalds preempt_disable(); 30411da177e4SLinus Torvalds __get_cpu_var(bh_accounting).nr++; 30421da177e4SLinus Torvalds recalc_bh_state(); 30431da177e4SLinus Torvalds preempt_enable(); 30441da177e4SLinus Torvalds } 30451da177e4SLinus Torvalds return ret; 30461da177e4SLinus Torvalds } 30471da177e4SLinus Torvalds EXPORT_SYMBOL(alloc_buffer_head); 30481da177e4SLinus Torvalds 30491da177e4SLinus Torvalds void free_buffer_head(struct buffer_head *bh) 30501da177e4SLinus Torvalds { 30511da177e4SLinus Torvalds BUG_ON(!list_empty(&bh->b_assoc_buffers)); 30521da177e4SLinus Torvalds kmem_cache_free(bh_cachep, bh); 30531da177e4SLinus Torvalds preempt_disable(); 30541da177e4SLinus Torvalds __get_cpu_var(bh_accounting).nr--; 30551da177e4SLinus Torvalds recalc_bh_state(); 30561da177e4SLinus Torvalds preempt_enable(); 30571da177e4SLinus Torvalds } 30581da177e4SLinus Torvalds EXPORT_SYMBOL(free_buffer_head); 30591da177e4SLinus Torvalds 30601da177e4SLinus Torvalds static void 30611da177e4SLinus Torvalds init_buffer_head(void *data, kmem_cache_t *cachep, unsigned long flags) 30621da177e4SLinus Torvalds { 30631da177e4SLinus Torvalds if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == 30641da177e4SLinus Torvalds SLAB_CTOR_CONSTRUCTOR) { 30651da177e4SLinus Torvalds struct buffer_head * bh = (struct buffer_head *)data; 30661da177e4SLinus Torvalds 30671da177e4SLinus Torvalds memset(bh, 0, sizeof(*bh)); 30681da177e4SLinus Torvalds INIT_LIST_HEAD(&bh->b_assoc_buffers); 30691da177e4SLinus Torvalds } 30701da177e4SLinus Torvalds } 30711da177e4SLinus Torvalds 30721da177e4SLinus Torvalds #ifdef CONFIG_HOTPLUG_CPU 30731da177e4SLinus Torvalds static void buffer_exit_cpu(int cpu) 30741da177e4SLinus Torvalds { 30751da177e4SLinus Torvalds int i; 30761da177e4SLinus Torvalds struct bh_lru *b = &per_cpu(bh_lrus, cpu); 30771da177e4SLinus Torvalds 30781da177e4SLinus Torvalds for (i = 0; i < BH_LRU_SIZE; i++) { 30791da177e4SLinus Torvalds brelse(b->bhs[i]); 30801da177e4SLinus Torvalds b->bhs[i] = NULL; 30811da177e4SLinus Torvalds } 30821da177e4SLinus Torvalds } 30831da177e4SLinus Torvalds 30841da177e4SLinus Torvalds static int buffer_cpu_notify(struct notifier_block *self, 30851da177e4SLinus Torvalds unsigned long action, void *hcpu) 30861da177e4SLinus Torvalds { 30871da177e4SLinus Torvalds if (action == CPU_DEAD) 30881da177e4SLinus Torvalds buffer_exit_cpu((unsigned long)hcpu); 30891da177e4SLinus Torvalds return NOTIFY_OK; 30901da177e4SLinus Torvalds } 30911da177e4SLinus Torvalds #endif /* CONFIG_HOTPLUG_CPU */ 30921da177e4SLinus Torvalds 30931da177e4SLinus Torvalds void __init buffer_init(void) 30941da177e4SLinus Torvalds { 30951da177e4SLinus Torvalds int nrpages; 30961da177e4SLinus Torvalds 30971da177e4SLinus Torvalds bh_cachep = kmem_cache_create("buffer_head", 30981da177e4SLinus Torvalds sizeof(struct buffer_head), 0, 3099e422fd2cSAndrea Arcangeli SLAB_RECLAIM_ACCOUNT|SLAB_PANIC, init_buffer_head, NULL); 31001da177e4SLinus Torvalds 31011da177e4SLinus Torvalds /* 31021da177e4SLinus Torvalds * Limit the bh occupancy to 10% of ZONE_NORMAL 31031da177e4SLinus Torvalds */ 31041da177e4SLinus Torvalds nrpages = (nr_free_buffer_pages() * 10) / 100; 31051da177e4SLinus Torvalds max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); 31061da177e4SLinus Torvalds hotcpu_notifier(buffer_cpu_notify, 0); 31071da177e4SLinus Torvalds } 31081da177e4SLinus Torvalds 31091da177e4SLinus Torvalds EXPORT_SYMBOL(__bforget); 31101da177e4SLinus Torvalds EXPORT_SYMBOL(__brelse); 31111da177e4SLinus Torvalds EXPORT_SYMBOL(__wait_on_buffer); 31121da177e4SLinus Torvalds EXPORT_SYMBOL(block_commit_write); 31131da177e4SLinus Torvalds EXPORT_SYMBOL(block_prepare_write); 31141da177e4SLinus Torvalds EXPORT_SYMBOL(block_read_full_page); 31151da177e4SLinus Torvalds EXPORT_SYMBOL(block_sync_page); 31161da177e4SLinus Torvalds EXPORT_SYMBOL(block_truncate_page); 31171da177e4SLinus Torvalds EXPORT_SYMBOL(block_write_full_page); 31181da177e4SLinus Torvalds EXPORT_SYMBOL(cont_prepare_write); 31191da177e4SLinus Torvalds EXPORT_SYMBOL(end_buffer_async_write); 31201da177e4SLinus Torvalds EXPORT_SYMBOL(end_buffer_read_sync); 31211da177e4SLinus Torvalds EXPORT_SYMBOL(end_buffer_write_sync); 31221da177e4SLinus Torvalds EXPORT_SYMBOL(file_fsync); 31231da177e4SLinus Torvalds EXPORT_SYMBOL(fsync_bdev); 31241da177e4SLinus Torvalds EXPORT_SYMBOL(generic_block_bmap); 31251da177e4SLinus Torvalds EXPORT_SYMBOL(generic_commit_write); 31261da177e4SLinus Torvalds EXPORT_SYMBOL(generic_cont_expand); 31271da177e4SLinus Torvalds EXPORT_SYMBOL(init_buffer); 31281da177e4SLinus Torvalds EXPORT_SYMBOL(invalidate_bdev); 31291da177e4SLinus Torvalds EXPORT_SYMBOL(ll_rw_block); 31301da177e4SLinus Torvalds EXPORT_SYMBOL(mark_buffer_dirty); 31311da177e4SLinus Torvalds EXPORT_SYMBOL(submit_bh); 31321da177e4SLinus Torvalds EXPORT_SYMBOL(sync_dirty_buffer); 31331da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_buffer); 3134