xfs: check for more work before sleeping in xfssyncd

commit 20f6b2c785cf187445f126321638ab8ba7aa7494 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index 687e9fc582ca771774c65d5793347fdd98731181..6b6b39416ad30cb71c8331c7b892291af09fcf35 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -613,7 +613,8 @@ 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))
@@ -633,8 +634,7 @@ 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) {