[PATCH AUTOSEL 4.9 6/7] vfs: make freeze_super abort when sync_filesystem returns error

[Sasha Levin <sashal@kernel.org>]

From: "Darrick J. Wong" <djwong@kernel.org>

[ Upstream commit 2719c7160dcfaae1f73a1c0c210ad3281c19022e ]

If we fail to synchronize the filesystem while preparing to freeze the
fs, abort the freeze.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/super.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/fs/super.c b/fs/super.c
index 377c439477b74..20e9cd2b6488d 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1298,11 +1298,9 @@ static void lockdep_sb_freeze_acquire(struct super_block *sb)
 		percpu_rwsem_acquire(sb->s_writers.rw_sem + level, 0, _THIS_IP_);
 }
 
-static void sb_freeze_unlock(struct super_block *sb)
+static void sb_freeze_unlock(struct super_block *sb, int level)
 {
-	int level;
-
-	for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--)
+	for (level--; level >= 0; level--)
 		percpu_up_write(sb->s_writers.rw_sem + level);
 }
 
@@ -1373,7 +1371,14 @@ int freeze_super(struct super_block *sb)
 	sb_wait_write(sb, SB_FREEZE_PAGEFAULT);
 
 	/* All writers are done so after syncing there won't be dirty data */
-	sync_filesystem(sb);
+	ret = sync_filesystem(sb);
+	if (ret) {
+		sb->s_writers.frozen = SB_UNFROZEN;
+		sb_freeze_unlock(sb, SB_FREEZE_PAGEFAULT);
+		wake_up(&sb->s_writers.wait_unfrozen);
+		deactivate_locked_super(sb);
+		return ret;
+	}
 
 	/* Now wait for internal filesystem counter */
 	sb->s_writers.frozen = SB_FREEZE_FS;
@@ -1385,7 +1390,7 @@ int freeze_super(struct super_block *sb)
 			printk(KERN_ERR
 				"VFS:Filesystem freeze failed\n");
 			sb->s_writers.frozen = SB_UNFROZEN;
-			sb_freeze_unlock(sb);
+			sb_freeze_unlock(sb, SB_FREEZE_FS);
 			wake_up(&sb->s_writers.wait_unfrozen);
 			deactivate_locked_super(sb);
 			return ret;
@@ -1437,7 +1442,7 @@ int thaw_super(struct super_block *sb)
 	}
 
 	sb->s_writers.frozen = SB_UNFROZEN;
-	sb_freeze_unlock(sb);
+	sb_freeze_unlock(sb, SB_FREEZE_FS);
 out:
 	wake_up(&sb->s_writers.wait_unfrozen);
 	deactivate_locked_super(sb);
-- 
2.34.1