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authorJan Kara <jack@suse.cz>2010-08-09 17:20:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-09 20:45:03 -0700
commit7624ee72aa09334af072853457a5d46d9901c3f8 (patch)
tree046321fdf7f46c38a6e6d686c1cd962e70149c94 /fs/fs-writeback.c
parentd9f8984c2c23b91e202a764fe4b15041a29a201a (diff)
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mm: avoid resetting wb_start after each writeback round
WB_SYNC_NONE writeback is done in rounds of 1024 pages so that we don't write out some huge inode for too long while starving writeout of other inodes. To avoid livelocks, we record time we started writeback in wbc->wb_start and do not write out inodes which were dirtied after this time. But currently, writeback_inodes_wb() resets wb_start each time it is called thus effectively invalidating this logic and making any WB_SYNC_NONE writeback prone to livelocks. This patch makes sure wb_start is set only once when we start writeback. Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Christoph Hellwig <hch@lst.de> Acked-by: Jens Axboe <jaxboe@fusionio.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fs-writeback.c')
-rw-r--r--fs/fs-writeback.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index d5be1693ac9..30ac305e829 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -530,7 +530,8 @@ void writeback_inodes_wb(struct bdi_writeback *wb,
{
int ret = 0;
- wbc->wb_start = jiffies; /* livelock avoidance */
+ if (!wbc->wb_start)
+ wbc->wb_start = jiffies; /* livelock avoidance */
spin_lock(&inode_lock);
if (!wbc->for_kupdate || list_empty(&wb->b_io))
queue_io(wb, wbc->older_than_this);
@@ -559,7 +560,6 @@ static void __writeback_inodes_sb(struct super_block *sb,
{
WARN_ON(!rwsem_is_locked(&sb->s_umount));
- wbc->wb_start = jiffies; /* livelock avoidance */
spin_lock(&inode_lock);
if (!wbc->for_kupdate || list_empty(&wb->b_io))
queue_io(wb, wbc->older_than_this);
@@ -625,6 +625,7 @@ static long wb_writeback(struct bdi_writeback *wb,
wbc.range_end = LLONG_MAX;
}
+ wbc.wb_start = jiffies; /* livelock avoidance */
for (;;) {
/*
* Stop writeback when nr_pages has been consumed