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Commit 83114060 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 



commit 943eb3bf25f4a7b745dd799e031be276aa104d82 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: 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 avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent aceca7b1

fs/btrfs/inode.c

+4 −6
Original line number Diff line number Diff line
@@ -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 @@ 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));