[PATCH 09/35] btrfs: protect space cache inode alloc with nofs

Josef Bacik
2018-08-30T21:46:00Z

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.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/btrfs/free-space-cache.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index c3888c113d81..db93a5f035a0 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -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 +70,9 @@ static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
btrfs_disk_key_to_cpu(&location, &disk_key);
btrfs_release_path(path);

+ 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;

--
2.14.3