From 5cee5815d1564bbbd505fea86f4550f1efdb5cd0 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 27 Apr 2009 16:43:51 +0200 Subject: vfs: Make sys_sync() use fsync_super() (version 4) It is unnecessarily fragile to have two places (fsync_super() and do_sync()) doing data integrity sync of the filesystem. Alter __fsync_super() to accommodate needs of both callers and use it. So after this patch __fsync_super() is the only place where we gather all the calls needed to properly send all data on a filesystem to disk. Nice bonus is that we get a complete livelock avoidance and write_supers() is now only used for periodic writeback of superblocks. sync_blockdevs() introduced a couple of patches ago is gone now. [build fixes folded] Signed-off-by: Jan Kara Signed-off-by: Al Viro --- fs/super.c | 72 ++++++++++++++++++++------------------------------------------ 1 file changed, 23 insertions(+), 49 deletions(-) (limited to 'fs/super.c') diff --git a/fs/super.c b/fs/super.c index 8dbe1ead9dd..c8ce5ed0424 100644 --- a/fs/super.c +++ b/fs/super.c @@ -284,23 +284,23 @@ EXPORT_SYMBOL(lock_super); EXPORT_SYMBOL(unlock_super); /* - * Write out and wait upon all dirty data associated with this - * superblock. Filesystem data as well as the underlying block - * device. Takes the superblock lock. Requires a second blkdev - * flush by the caller to complete the operation. + * Do the filesystem syncing work. For simple filesystems sync_inodes_sb(sb, 0) + * just dirties buffers with inodes so we have to submit IO for these buffers + * via __sync_blockdev(). This also speeds up the wait == 1 case since in that + * case write_inode() functions do sync_dirty_buffer() and thus effectively + * write one block at a time. */ -static int __fsync_super(struct super_block *sb) +static int __fsync_super(struct super_block *sb, int wait) { - sync_inodes_sb(sb, 0); vfs_dq_sync(sb); - sync_inodes_sb(sb, 1); + sync_inodes_sb(sb, wait); lock_super(sb); if (sb->s_dirt && sb->s_op->write_super) sb->s_op->write_super(sb); unlock_super(sb); if (sb->s_op->sync_fs) - sb->s_op->sync_fs(sb, 1); - return sync_blockdev(sb->s_bdev); + sb->s_op->sync_fs(sb, wait); + return __sync_blockdev(sb->s_bdev, wait); } /* @@ -310,7 +310,12 @@ static int __fsync_super(struct super_block *sb) */ int fsync_super(struct super_block *sb) { - return __fsync_super(sb); + int ret; + + ret = __fsync_super(sb, 0); + if (ret < 0) + return ret; + return __fsync_super(sb, 1); } EXPORT_SYMBOL_GPL(fsync_super); @@ -469,20 +474,18 @@ restart: } /* - * Call the ->sync_fs super_op against all filesystems which are r/w and - * which implement it. + * Sync all the data for all the filesystems (called by sys_sync() and + * emergency sync) * * This operation is careful to avoid the livelock which could easily happen - * if two or more filesystems are being continuously dirtied. s_need_sync_fs + * if two or more filesystems are being continuously dirtied. s_need_sync * is used only here. We set it against all filesystems and then clear it as * we sync them. So redirtied filesystems are skipped. * * But if process A is currently running sync_filesystems and then process B - * calls sync_filesystems as well, process B will set all the s_need_sync_fs + * calls sync_filesystems as well, process B will set all the s_need_sync * flags again, which will cause process A to resync everything. Fix that with * a local mutex. - * - * (Fabian) Avoid sync_fs with clean fs & wait mode 0 */ void sync_filesystems(int wait) { @@ -492,25 +495,23 @@ void sync_filesystems(int wait) mutex_lock(&mutex); /* Could be down_interruptible */ spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { - if (!sb->s_op->sync_fs) - continue; if (sb->s_flags & MS_RDONLY) continue; - sb->s_need_sync_fs = 1; + sb->s_need_sync = 1; } restart: list_for_each_entry(sb, &super_blocks, s_list) { - if (!sb->s_need_sync_fs) + if (!sb->s_need_sync) continue; - sb->s_need_sync_fs = 0; + sb->s_need_sync = 0; if (sb->s_flags & MS_RDONLY) continue; /* hm. Was remounted r/o meanwhile */ sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); if (sb->s_root) - sb->s_op->sync_fs(sb, wait); + __fsync_super(sb, wait); up_read(&sb->s_umount); /* restart only when sb is no longer on the list */ spin_lock(&sb_lock); @@ -521,33 +522,6 @@ restart: mutex_unlock(&mutex); } -#ifdef CONFIG_BLOCK -/* - * Sync all block devices underlying some superblock - */ -void sync_blockdevs(void) -{ - struct super_block *sb; - - spin_lock(&sb_lock); -restart: - list_for_each_entry(sb, &super_blocks, s_list) { - if (!sb->s_bdev) - continue; - sb->s_count++; - spin_unlock(&sb_lock); - down_read(&sb->s_umount); - if (sb->s_root) - sync_blockdev(sb->s_bdev); - up_read(&sb->s_umount); - spin_lock(&sb_lock); - if (__put_super_and_need_restart(sb)) - goto restart; - } - spin_unlock(&sb_lock); -} -#endif - /** * get_super - get the superblock of a device * @bdev: device to get the superblock for -- cgit v1.2.3