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>
diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index ed9c3db3..44ac7a0 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -1049,16 +1049,15 @@
/*
* 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;
/*
