Commit 84de76a2 authored by Josef Bacik's avatar Josef Bacik Committed by David Sterba
Browse files

btrfs: protect space cache inode alloc with GFP_NOFS 



If we're allocating a new space cache inode it's likely going to be
under a transaction handle, so we need to use memalloc_nofs_save() in
order to avoid deadlocks, and more importantly lockdep messages that
make xfstests fail.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
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>
parent f45c752b

fs/btrfs/free-space-cache.c

+8 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/math64.h>

#include <linux/ratelimit.h>

#include <linux/error-injection.h>

#include <linux/sched/mm.h>

#include "ctree.h"

#include "free-space-cache.h"

#include "transaction.h"
@@ -47,6 +48,7 @@ static struct inode *__lookup_free_space_inode(struct btrfs_root *root, 
	struct btrfs_free_space_header *header;

	struct extent_buffer *leaf;

	struct inode *inode = NULL;

	unsigned nofs_flag;

	int ret;



	key.objectid = BTRFS_FREE_SPACE_OBJECTID;
@@ -68,7 +70,13 @@ static struct inode *__lookup_free_space_inode(struct btrfs_root *root, 
	btrfs_disk_key_to_cpu(&location, &disk_key);

	btrfs_release_path(path);



	/*

	 * We are often under a trans handle at this point, so we need to make

	 * sure NOFS is set to keep us from deadlocking.

	 */

	nofs_flag = memalloc_nofs_save();

	inode = btrfs_iget(fs_info->sb, &location, root, NULL);

	memalloc_nofs_restore(nofs_flag);

	if (IS_ERR(inode))

		return inode;