On Wed, Aug 03, 2011 at 01:10:31PM +0200, Johannes Weiner wrote:

On Thu, Jul 21, 2011 at 05:28:46PM +0100, Mel Gorman wrote:

quoted

Direct reclaim should never writeback pages. Warn if an attempt is
made. By rights, btrfs should be allowing writepage from kswapd if
it is failing to reclaim pages by any other means but it's outside
the scope of this patch.

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 fs/btrfs/disk-io.c |    2 ++
 fs/btrfs/inode.c   |    2 ++
 2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1ac8db5d..cc9c9cf 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c

@@ -829,6 +829,8 @@ static int btree_writepage(struct page *page, struct writeback_control *wbc)
 
 	tree = &BTRFS_I(page->mapping->host)->io_tree;
 	if (!(current->flags & PF_MEMALLOC)) {
+		WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
+								PF_MEMALLOC);

Since it is branch for PF_MEMALLOC being set, why not just
WARN_ON_ONCE(!(current->flags & PF_KSWAPD)) instead?

Minor nitpick, though, and I can understand if you just want to have
the conditionals be the same in every fs.

It was just copying the conditionals for the other FS although I admit
your version would look nicer.

-- 
Mel Gorman
SUSE Labs

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