Btrfs: setup a nofs context for memory allocation at __btrfs_set_acl
We are holding a transaction handle when setting an acl, therefore we can
not allocate the xattr value buffer using GFP_KERNEL, as we could deadlock
if reclaim is triggered by the allocation, therefore setup a nofs context.
Fixes: 39a27ec1004e8 ("btrfs: use GFP_KERNEL for xattr and acl allocations")
CC: stable@vger.kernel.org # 4.9+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index 3b66c95..5810463 100644
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -9,6 +9,7 @@
#include <linux/posix_acl_xattr.h>
#include <linux/posix_acl.h>
#include <linux/sched.h>
+#include <linux/sched/mm.h>
#include <linux/slab.h>
#include "ctree.h"
@@ -72,8 +73,16 @@ static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
}
if (acl) {
+ unsigned int nofs_flag;
+
size = posix_acl_xattr_size(acl->a_count);
+ /*
+ * We're holding a transaction handle, so use a NOFS memory
+ * allocation context to avoid deadlock if reclaim happens.
+ */
+ nofs_flag = memalloc_nofs_save();
value = kmalloc(size, GFP_KERNEL);
+ memalloc_nofs_restore(nofs_flag);
if (!value) {
ret = -ENOMEM;
goto out;