xfs: check for more work before sleeping in xfssyncd

xfssyncd processes a queue of work by detaching the queue and
then iterating over all the work items. It then sleeps for a
time period or until new work comes in. If new work is queued
while xfssyncd is actively processing the detached work queue,
it will not process that new work until after a sleep timeout
or the next work event queued wakes it.

Fix this by checking the work queue again before going to sleep.

Signed-off-by: Dave Chinner <david@fromorbit.com>
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_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index f9fc154d9f727c43435b5be19c63961ca80eb790..05cd85317f6f53b6e0fe77bf0426c890f927b07a 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -607,7 +607,8 @@ xfssyncd(
        set_freezable();
        timeleft = xfs_syncd_centisecs * msecs_to_jiffies(10);
        for (;;) {
-               timeleft = schedule_timeout_interruptible(timeleft);
+               if (list_empty(&mp->m_sync_list))
+                       timeleft = schedule_timeout_interruptible(timeleft);
                /* swsusp */
                try_to_freeze();
                if (kthread_should_stop() && list_empty(&mp->m_sync_list))
@@ -627,8 +628,7 @@ xfssyncd(
                        list_add_tail(&mp->m_sync_work.w_list,
                                        &mp->m_sync_list);
                }
-               list_for_each_entry_safe(work, n, &mp->m_sync_list, w_list)
-                       list_move(&work->w_list, &tmp);
+               list_splice_init(&mp->m_sync_list, &tmp);
                spin_unlock(&mp->m_sync_lock);
 
                list_for_each_entry_safe(work, n, &tmp, w_list) {