GFS2: Move log buffer lists into transaction

Over time, we hope to be able to improve the concurrency available
in the log code. This is one small step towards that, by moving
the buffer lists from the super block, and into the transaction
structure, so that each transaction builds its own buffer lists.

At transaction commit time, the buffer lists are merged into
the currently accumulating transaction. That transaction then
is passed into the before and after commit functions at journal
flush time. Thus there should be no change in overall behaviour
yet.

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

1 files changed, 25 insertions, 3 deletions

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 1e1bda0de43d..975712c6660b 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -712,7 +712,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
                 tr->tr_first = sdp->sd_log_flush_head;
 
         gfs2_ordered_write(sdp);
-        lops_before_commit(sdp);
+        lops_before_commit(sdp, tr);
         gfs2_log_flush_bio(sdp, WRITE);
 
         if (sdp->sd_log_head != sdp->sd_log_flush_head) {
@@ -744,6 +744,27 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
         kfree(tr);
 }
 
+/**
+ * gfs2_merge_trans - Merge a new transaction into a cached transaction
+ * @old: Original transaction to be expanded
+ * @new: New transaction to be merged
+ */
+
+static void gfs2_merge_trans(struct gfs2_trans *old, struct gfs2_trans *new)
+{
+        WARN_ON_ONCE(old->tr_attached != 1);
+
+        old->tr_num_buf_new     += new->tr_num_buf_new;
+        old->tr_num_databuf_new += new->tr_num_databuf_new;
+        old->tr_num_buf_rm      += new->tr_num_buf_rm;
+        old->tr_num_databuf_rm  += new->tr_num_databuf_rm;
+        old->tr_num_revoke      += new->tr_num_revoke;
+        old->tr_num_revoke_rm   += new->tr_num_revoke_rm;
+
+        list_splice_tail_init(&new->tr_databuf, &old->tr_databuf);
+        list_splice_tail_init(&new->tr_buf, &old->tr_buf);
+}
+
 static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
         unsigned int reserved;
@@ -766,8 +787,9 @@ static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
                              sdp->sd_jdesc->jd_blocks);
         sdp->sd_log_blks_reserved = reserved;
 
-        if (sdp->sd_log_tr == NULL &&
-            (tr->tr_num_buf_new || tr->tr_num_databuf_new)) {
+        if (sdp->sd_log_tr) {
+                gfs2_merge_trans(sdp->sd_log_tr, tr);
+        } else if (tr->tr_num_buf_new || tr->tr_num_databuf_new) {
                 gfs2_assert_withdraw(sdp, tr->tr_t_gh.gh_gl);
                 sdp->sd_log_tr = tr;
                 tr->tr_attached = 1;