On 13.12.18 г. 23:16 ч., fdmanana@xxxxxxxxxx wrote:
> From: Filipe Manana <fdmanana@xxxxxxxx>
>
> 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")
> Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
> fs/btrfs/acl.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
> index 3b66c957ea6f..5810463dc6d2 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;
>
