[GFS2] Small fixes to logging code

This reverts part of an earlier patch which tried to reclaim
gfs2_bufdata structures too early and resulted in a "use after free"
case (this bit from me). Also a change to not write out log headers
unless we really need to (in the case of flushing nothing we don't need
a header) from Bob.

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

1 files changed, 14 insertions, 5 deletions

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 8fcfb784f906..f49a12e24086 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -237,10 +237,7 @@ static void gfs2_ail2_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
                 list_del(&bd->bd_ail_st_list);
                 list_del(&bd->bd_ail_gl_list);
                 atomic_dec(&bd->bd_gl->gl_ail_count);
-                if (bd->bd_bh)
-                        brelse(bd->bd_bh);
-                else
-                        kmem_cache_free(gfs2_bufdata_cachep, bd);
+                brelse(bd->bd_bh);
         }
 }
 
@@ -583,6 +580,7 @@ static void log_flush_commit(struct gfs2_sbd *sdp)
         struct list_head *head = &sdp->sd_log_flush_list;
         struct gfs2_log_buf *lb;
         struct buffer_head *bh;
+        int flushcount = 0;
 
         while (!list_empty(head)) {
                 lb = list_entry(head->next, struct gfs2_log_buf, lb_list);
@@ -599,9 +597,20 @@ static void log_flush_commit(struct gfs2_sbd *sdp)
                 } else
                         brelse(bh);
                 kfree(lb);
+                flushcount++;
         }
 
-        log_write_header(sdp, 0, 0);
+        /* If nothing was journaled, the header is unplanned and unwanted. */
+        if (flushcount) {
+                log_write_header(sdp, 0, 0);
+        } else {
+                unsigned int tail;
+                tail = current_tail(sdp);
+
+                gfs2_ail1_empty(sdp, 0);
+                if (sdp->sd_log_tail != tail)
+                        log_pull_tail(sdp, tail);
+        }
 }
 
 /**