btrfs: don't double lock the subvol_sem
diff mbox series

Message ID 20191119185920.3031-1-josef@toxicpanda.com
State New
Headers show
Series
  • btrfs: don't double lock the subvol_sem
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Commit Message

Josef Bacik Nov. 19, 2019, 6:59 p.m. UTC
If we're rename exchanging two subvols we'll try to lock this lock
twice, which is bad.  Just lock once if either of the ino's are subvols.

cc: stable@vger.kernel.org
Fixes: cdd1fedf8261 ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/btrfs/inode.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

Comments

David Sterba Nov. 25, 2019, 3:08 p.m. UTC | #1
On Tue, Nov 19, 2019 at 01:59:20PM -0500, Josef Bacik wrote:
> If we're rename exchanging two subvols we'll try to lock this lock
> twice, which is bad.  Just lock once if either of the ino's are subvols.
> 
> cc: stable@vger.kernel.org
> Fixes: cdd1fedf8261 ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>

Added to misc-next, thanks.

Patch
diff mbox series

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index b13c212b1bed..8db7455fee38 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9563,9 +9563,8 @@  static int btrfs_rename_exchange(struct inode *old_dir,
 	btrfs_init_log_ctx(&ctx_dest, new_inode);
 
 	/* close the race window with snapshot create/destroy ioctl */
-	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
-		down_read(&fs_info->subvol_sem);
-	if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID ||
+	    new_ino == BTRFS_FIRST_FREE_OBJECTID)
 		down_read(&fs_info->subvol_sem);
 
 	/*
@@ -9799,9 +9798,8 @@  static int btrfs_rename_exchange(struct inode *old_dir,
 		ret = ret ? ret : ret2;
 	}
 out_notrans:
-	if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
-		up_read(&fs_info->subvol_sem);
-	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID ||
+	    old_ino == BTRFS_FIRST_FREE_OBJECTID)
 		up_read(&fs_info->subvol_sem);
 
 	ASSERT(list_empty(&ctx_root.list));