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 <[e-mail]>

fs/gfs2/glops.c

···
 	struct gfs2_trans tr;
 
 	memset(&tr, 0, sizeof(tr));
+	INIT_LIST_HEAD(&tr.tr_buf);
+	INIT_LIST_HEAD(&tr.tr_databuf);
 	tr.tr_revokes = atomic_read(&gl->gl_ail_count);
 
 	if (!tr.tr_revokes)

fs/gfs2/incore.h

···
  */
 
 struct gfs2_log_operations {
-	void (*lo_before_commit) (struct gfs2_sbd *sdp);
+	void (*lo_before_commit) (struct gfs2_sbd *sdp, struct gfs2_trans *tr);
 	void (*lo_after_commit) (struct gfs2_sbd *sdp, struct gfs2_trans *tr);
 	void (*lo_before_scan) (struct gfs2_jdesc *jd,
 				struct gfs2_log_header_host *head, int pass);
···
 	unsigned int tr_num_revoke_rm;
 
 	struct list_head tr_list;
+	struct list_head tr_databuf;
+	struct list_head tr_buf;
 
 	unsigned int tr_first;
 	struct list_head tr_ail1_list;
···
 	unsigned int sd_log_num_rg;
 	unsigned int sd_log_num_databuf;
 
-	struct list_head sd_log_le_buf;
 	struct list_head sd_log_le_revoke;
-	struct list_head sd_log_le_databuf;
 	struct list_head sd_log_le_ordered;
 	spinlock_t sd_ordered_lock;
 

fs/gfs2/log.c

···
 		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) {
···
 	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;
···
 			     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;

fs/gfs2/lops.c

···
 	gfs2_log_unlock(sdp);
 }
 
-static void buf_lo_before_commit(struct gfs2_sbd *sdp)
+static void buf_lo_before_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
 	unsigned int limit = buf_limit(sdp); /* 503 for 4k blocks */
-
-	gfs2_before_commit(sdp, limit, sdp->sd_log_num_buf,
-			   &sdp->sd_log_le_buf, 0);
+	if (tr == NULL)
+		return;
+	gfs2_before_commit(sdp, limit, sdp->sd_log_num_buf, &tr->tr_buf, 0);
 }
 
 static void buf_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
-	struct list_head *head = &sdp->sd_log_le_buf;
+	struct list_head *head;
 	struct gfs2_bufdata *bd;
 
-	if (tr == NULL) {
-		gfs2_assert(sdp, list_empty(head));
+	if (tr == NULL)
 		return;
-	}
 
+	head = &tr->tr_buf;
 	while (!list_empty(head)) {
 		bd = list_entry(head->next, struct gfs2_bufdata, bd_list);
 		list_del_init(&bd->bd_list);
···
 	        jd->jd_jid, sdp->sd_replayed_blocks, sdp->sd_found_blocks);
 }
 
-static void revoke_lo_before_commit(struct gfs2_sbd *sdp)
+static void revoke_lo_before_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
 	struct gfs2_meta_header *mh;
 	unsigned int offset;
···
  *
  */
 
-static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
+static void databuf_lo_before_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
 	unsigned int limit = buf_limit(sdp) / 2;
-
-	gfs2_before_commit(sdp, limit, sdp->sd_log_num_databuf,
-			   &sdp->sd_log_le_databuf, 1);
+	if (tr == NULL)
+		return;
+	gfs2_before_commit(sdp, limit, sdp->sd_log_num_databuf, &tr->tr_databuf, 1);
 }
 
 static int databuf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
···
 
 static void databuf_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
-	struct list_head *head = &sdp->sd_log_le_databuf;
+	struct list_head *head;
 	struct gfs2_bufdata *bd;
 
-	if (tr == NULL) {
-		gfs2_assert(sdp, list_empty(head));
+	if (tr == NULL)
 		return;
-	}
 
+	head = &tr->tr_databuf;
 	while (!list_empty(head)) {
 		bd = list_entry(head->next, struct gfs2_bufdata, bd_list);
 		list_del_init(&bd->bd_list);

fs/gfs2/lops.h

···
 	return limit;
 }
 
-static inline void lops_before_commit(struct gfs2_sbd *sdp)
+static inline void lops_before_commit(struct gfs2_sbd *sdp,
+				      struct gfs2_trans *tr)
 {
 	int x;
 	for (x = 0; gfs2_log_ops[x]; x++)
 		if (gfs2_log_ops[x]->lo_before_commit)
-			gfs2_log_ops[x]->lo_before_commit(sdp);
+			gfs2_log_ops[x]->lo_before_commit(sdp, tr);
 }
 
 static inline void lops_after_commit(struct gfs2_sbd *sdp,

fs/gfs2/ops_fstype.c

···
 
 	spin_lock_init(&sdp->sd_log_lock);
 	atomic_set(&sdp->sd_log_pinned, 0);
-	INIT_LIST_HEAD(&sdp->sd_log_le_buf);
 	INIT_LIST_HEAD(&sdp->sd_log_le_revoke);
-	INIT_LIST_HEAD(&sdp->sd_log_le_databuf);
 	INIT_LIST_HEAD(&sdp->sd_log_le_ordered);
 	spin_lock_init(&sdp->sd_ordered_lock);
 

fs/gfs2/trans.c

···
 	if (revokes)
 		tr->tr_reserved += gfs2_struct2blk(sdp, revokes,
 						   sizeof(u64));
+	INIT_LIST_HEAD(&tr->tr_databuf);
+	INIT_LIST_HEAD(&tr->tr_buf);
+
 	sb_start_intwrite(sdp->sd_vfs);
 	gfs2_holder_init(sdp->sd_trans_gl, LM_ST_SHARED, 0, &tr->tr_t_gh);
 
···
 		gfs2_pin(sdp, bd->bd_bh);
 		tr->tr_num_databuf_new++;
 		sdp->sd_log_num_databuf++;
-		list_add_tail(&bd->bd_list, &sdp->sd_log_le_databuf);
+		list_add_tail(&bd->bd_list, &tr->tr_databuf);
 	}
 	gfs2_log_unlock(sdp);
 	unlock_buffer(bh);
···
 	mh->__pad0 = cpu_to_be64(0);
 	mh->mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
 	sdp->sd_log_num_buf++;
-	list_add(&bd->bd_list, &sdp->sd_log_le_buf);
+	list_add(&bd->bd_list, &tr->tr_buf);
 	tr->tr_num_buf_new++;
 }