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

commit 943eb3bf25 upstream.

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: cdd1fedf82 ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Josef Bacik 2019-11-19 13:59:20 -05:00 committed by Greg Kroah-Hartman
parent aceca7b13f
commit 831140602a
1 changed files with 4 additions and 6 deletions
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10
fs/btrfs/inode.c
View File

@ -9535,9 +9535,8 @@ 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);
/*
@ -9771,9 +9770,8 @@ out_fail:
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));