xfs: allow writeback from kswapd

We only need disable I/O from direct or memcg reclaim.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index ed9c3db376c3..44ac7a0e2926 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -1049,16 +1049,15 @@ xfs_vm_writepage(
         /*
          * Refuse to write the page out if we are called from reclaim context.
          *
-         * This is primarily to avoid stack overflows when called from deep
-         * used stacks in random callers for direct reclaim, but disabling
-         * reclaim for kswap is a nice side-effect as kswapd causes rather
-         * suboptimal I/O patters, too.
+         * This avoids stack overflows when called from deeply used stacks in
+         * random callers for direct reclaim or memcg reclaim.  We explicitly
+         * allow reclaim from kswapd as the stack usage there is relatively low.
          *
          * This should really be done by the core VM, but until that happens
          * filesystems like XFS, btrfs and ext4 have to take care of this
          * by themselves.
          */
-        if (current->flags & PF_MEMALLOC)
+        if ((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == PF_MEMALLOC)
                 goto out_fail;
 
         /*