[GFS2] Use list_for_each_entry_safe_reverse in gfs2_ail1_start()

This is an attempt to fix Red Hat bz 204364. I don't hit it all
the time, but with these changes, running postmark which used to
trigger it on a regular basis no longer appears to. So I'm not
saying that its 100% certain that its fixed, but it does look
promising at the moment.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 9 insertions, 10 deletions

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 08b80b263ad..6112d648b7e 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -62,8 +62,9 @@ void gfs2_ail1_start(struct gfs2_sbd *sdp, int flags)
 {
         struct list_head *head = &sdp->sd_ail1_list;
         u64 sync_gen;
-        struct list_head *first, *tmp;
-        struct gfs2_ail *first_ai, *ai;
+        struct list_head *first;
+        struct gfs2_ail *first_ai, *ai, *tmp;
+        int done = 0;
 
         gfs2_log_lock(sdp);
         if (list_empty(head)) {
@@ -75,27 +76,25 @@ void gfs2_ail1_start(struct gfs2_sbd *sdp, int flags)
         first = head->prev;
         first_ai = list_entry(first, struct gfs2_ail, ai_list);
         first_ai->ai_sync_gen = sync_gen;
-        gfs2_ail1_start_one(sdp, first_ai);
+        gfs2_ail1_start_one(sdp, first_ai); /* This may drop log lock */
 
         if (flags & DIO_ALL)
                 first = NULL;
 
-        for (;;) {
+        while(!done) {
                 if (first && (head->prev != first ||
                               gfs2_ail1_empty_one(sdp, first_ai, 0)))
                         break;
 
-                for (tmp = head->prev; tmp != head; tmp = tmp->prev) {
-                        ai = list_entry(tmp, struct gfs2_ail, ai_list);
+                done = 1;
+                list_for_each_entry_safe_reverse(ai, tmp, head, ai_list) {
                         if (ai->ai_sync_gen >= sync_gen)
                                 continue;
                         ai->ai_sync_gen = sync_gen;
-                        gfs2_ail1_start_one(sdp, ai);
+                        gfs2_ail1_start_one(sdp, ai); /* This may drop log lock */
+                        done = 0;
                         break;
                 }
-
-                if (tmp == head)
-                        break;
         }
 
         gfs2_log_unlock(sdp);