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Commit 85562d8a authored by Josef Bacik's avatar Josef Bacik Committed by Greg Kroah-Hartman
Browse files

btrfs: don't double lock the subvol_sem for rename exchange 



[ Upstream commit 943eb3bf25f4a7b745dd799e031be276aa104d82 ]

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.

Fixes: cdd1fedf ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: default avatarJosef Bacik <josef@toxicpanda.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 795b4ef8

fs/btrfs/inode.c

+4 −6
Original line number Diff line number Diff line
@@ -9597,9 +9597,8 @@ static int btrfs_rename_exchange(struct inode *old_dir, 
		return -EXDEV;



	/* close the race window with snapshot create/destroy ioctl */

	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)

		down_read(&root->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(&dest->fs_info->subvol_sem);



	/*
@@ -9785,9 +9784,8 @@ static int btrfs_rename_exchange(struct inode *old_dir, 
	ret2 = btrfs_end_transaction(trans, root);

	ret = ret ? ret : ret2;

out_notrans:

	if (new_ino == BTRFS_FIRST_FREE_OBJECTID)

		up_read(&dest->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(&root->fs_info->subvol_sem);



	return ret;