From efceab1d563153a2b1a6e7d35376241a48126989 Mon Sep 17 00:00:00 2001
From: Dave Chinner <dchinner@redhat.com>
Date: Tue, 24 Aug 2010 11:44:56 +1000
Subject: xfs: handle negative wbc->nr_to_write during sync writeback
During data integrity (WB_SYNC_ALL) writeback, wbc->nr_to_write will
go negative on inodes with more than 1024 dirty pages due to
implementation details of write_cache_pages(). Currently XFS will
abort page clustering in writeback once nr_to_write drops below
zero, and so for data integrity writeback we will do very
inefficient page at a time allocation and IO submission for inodes
with large numbers of dirty pages.
Fix this by only aborting the page clustering code when
wbc->nr_to_write is negative and the sync mode is WB_SYNC_NONE.
Cc: <stable@kernel.org>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/linux-2.6/xfs_aops.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
(limited to 'fs')
diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index 15412fe15c3a..528be1ba1402 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -852,8 +852,8 @@ xfs_convert_page(
SetPageUptodate(page);
if (count) {
- wbc->nr_to_write--;
- if (wbc->nr_to_write <= 0)
+ if (--wbc->nr_to_write <= 0 &&
+ wbc->sync_mode == WB_SYNC_NONE)
done = 1;
}
xfs_start_page_writeback(page, !page_dirty, count);
--
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