releases/4.19.31/btrfs-setup-a-nofs-context-for-memory-allocation-at-__btrfs_set_acl.patch

   1 From a0873490660246db587849a9e172f2b7b21fa88a Mon Sep 17 00:00:00 2001
   2 From: Filipe Manana <fdmanana@suse.com>
   3 Date: Thu, 13 Dec 2018 21:16:56 +0000
   4 Subject: Btrfs: setup a nofs context for memory allocation at __btrfs_set_acl
   5
   6 From: Filipe Manana <fdmanana@suse.com>
   7
   8 commit a0873490660246db587849a9e172f2b7b21fa88a upstream.
   9
  10 We are holding a transaction handle when setting an acl, therefore we can
  11 not allocate the xattr value buffer using GFP_KERNEL, as we could deadlock
  12 if reclaim is triggered by the allocation, therefore setup a nofs context.
  13
  14 Fixes: 39a27ec1004e8 ("btrfs: use GFP_KERNEL for xattr and acl allocations")
  15 CC: stable@vger.kernel.org # 4.9+
  16 Reviewed-by: Nikolay Borisov <nborisov@suse.com>
  17 Signed-off-by: Filipe Manana <fdmanana@suse.com>
  18 Reviewed-by: David Sterba <dsterba@suse.com>
  19 Signed-off-by: David Sterba <dsterba@suse.com>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21
  22 ---
  23  fs/btrfs/acl.c |    9 +++++++++
  24  1 file changed, 9 insertions(+)
  25
  26 --- a/fs/btrfs/acl.c
  27 +++ b/fs/btrfs/acl.c
  28 @@ -9,6 +9,7 @@
  29  #include <linux/posix_acl_xattr.h>
  30  #include <linux/posix_acl.h>
  31  #include <linux/sched.h>
  32 +#include <linux/sched/mm.h>
  33  #include <linux/slab.h>
  34
  35  #include "ctree.h"
  36 @@ -72,8 +73,16 @@ static int __btrfs_set_acl(struct btrfs_
  37         }
  38
  39         if (acl) {
  40 +               unsigned int nofs_flag;
  41 +
  42                 size = posix_acl_xattr_size(acl->a_count);
  43 +               /*
  44 +                * We're holding a transaction handle, so use a NOFS memory
  45 +                * allocation context to avoid deadlock if reclaim happens.
  46 +                */
  47 +               nofs_flag = memalloc_nofs_save();
  48                 value = kmalloc(size, GFP_KERNEL);
  49 +               memalloc_nofs_restore(nofs_flag);
  50                 if (!value) {
  51                         ret = -ENOMEM;
  52                         goto out;