From: Filipe Manana <fdmanana@suse.com>
Date: Thu, 13 Dec 2018 21:16:56 +0000
Git-commit: a0873490660246db587849a9e172f2b7b21fa88a
Patch-mainline: 5.1
References: bsc#1172127
Subject: [PATCH] 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>
---
fs/btrfs/acl.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index 1ba49ebe67da..1c42d9f1d6c8 100644
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -22,6 +22,7 @@
#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"
@@ -89,8 +90,16 @@ 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;
--
2.16.4