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[PATCH 3/3] [PATCH] xfs: check for more work before sleeping in xfssyncd

To: stable@xxxxxxxxxx
Subject: [PATCH 3/3] [PATCH] xfs: check for more work before sleeping in xfssyncd
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 13 Apr 2010 16:27:32 +1000
Cc: xfs@xxxxxxxxxxx
In-reply-to: <1271140052-15365-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1271140052-15365-1-git-send-email-david@xxxxxxxxxxxxx>
>From 20f6b2c785cf187445f126321638ab8ba7aa7494 Thu, 4 Mar 2010 01:46:23 +0000

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@xxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Alex Elder <aelder@xxxxxxx>
---
 fs/xfs/linux-2.6/xfs_sync.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index 687e9fc..6b6b394 100644
--- 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) {
-- 
1.6.5

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