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>
This commit is contained in:
Christoph Hellwig 2010-06-28 10:34:44 -04:00 committed by Alex Elder
parent 651701d71d
commit d4f7a5cbd5

View file

@ -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;
/*