[Cluster-devel] [GFS2 PATCH 5/9] gfs2: Keep transactions on ail1 list until after issuing revokes

[Bob Peterson <rpeterso@redhat.com>]

Before this patch, function gfs2_write_revokes would call function
gfs2_ail1_empty, then run the ail1 list, issuing revokes. But
gfs2_ail1_empty can move transactions to the ail2 list, and thus,
their revokes were never issued. This patch adds a new parameter to
gfs2_ail1_empty that allows the transactions to remain on the ail1
list until it can issue revokes for them. Then, if they have no more
buffers, they're moved to the ail2 list after the revokes are added.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/log.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 81550038ace3..0d0dec3231c9 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -217,11 +217,12 @@ static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 /**
  * gfs2_ail1_empty - Try to empty the ail1 lists
  * @sdp: The superblock
+ * @move_empty_to_ail2: 1 if transaction to be moved to ail2 when empty
  *
  * Tries to empty the ail1 lists, starting with the oldest first
  */
 
-static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
+static int gfs2_ail1_empty(struct gfs2_sbd *sdp, bool move_empty_to_ail2)
 {
 	struct gfs2_trans *tr, *s;
 	int oldest_tr = 1;
@@ -230,10 +231,12 @@ static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
 	spin_lock(&sdp->sd_ail_lock);
 	list_for_each_entry_safe_reverse(tr, s, &sdp->sd_ail1_list, tr_list) {
 		gfs2_ail1_empty_one(sdp, tr);
-		if (list_empty(&tr->tr_ail1_list) && oldest_tr)
-			list_move(&tr->tr_list, &sdp->sd_ail2_list);
-		else
+		if (list_empty(&tr->tr_ail1_list) && oldest_tr) {
+			if (move_empty_to_ail2)
+				list_move(&tr->tr_list, &sdp->sd_ail2_list);
+		} else {
 			oldest_tr = 0;
+		}
 	}
 	ret = list_empty(&sdp->sd_ail1_list);
 	spin_unlock(&sdp->sd_ail_lock);
@@ -609,12 +612,12 @@ void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
 
 void gfs2_write_revokes(struct gfs2_sbd *sdp)
 {
-	struct gfs2_trans *tr;
+	struct gfs2_trans *tr, *s;
 	struct gfs2_bufdata *bd, *tmp;
 	int have_revokes = 0;
 	int max_revokes = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_log_descriptor)) / sizeof(u64);
 
-	gfs2_ail1_empty(sdp);
+	gfs2_ail1_empty(sdp, false);
 	spin_lock(&sdp->sd_ail_lock);
 	list_for_each_entry_reverse(tr, &sdp->sd_ail1_list, tr_list) {
 		list_for_each_entry(bd, &tr->tr_ail2_list, bd_ail_st_list) {
@@ -640,17 +643,20 @@ void gfs2_write_revokes(struct gfs2_sbd *sdp)
 	}
 	gfs2_log_lock(sdp);
 	spin_lock(&sdp->sd_ail_lock);
-	list_for_each_entry_reverse(tr, &sdp->sd_ail1_list, tr_list) {
+	list_for_each_entry_safe_reverse(tr, s, &sdp->sd_ail1_list, tr_list) {
 		list_for_each_entry_safe(bd, tmp, &tr->tr_ail2_list, bd_ail_st_list) {
 			if (max_revokes == 0)
-				goto out_of_blocks;
+				break;
 			if (!list_empty(&bd->bd_list))
 				continue;
 			gfs2_add_revoke(sdp, bd);
 			max_revokes--;
 		}
+		if (list_empty(&tr->tr_ail1_list))
+			list_move(&tr->tr_list, &sdp->sd_ail2_list);
+		if (max_revokes == 0)
+			break;
 	}
-out_of_blocks:
 	spin_unlock(&sdp->sd_ail_lock);
 	gfs2_log_unlock(sdp);
 
@@ -842,7 +848,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags)
 			for (;;) {
 				gfs2_ail1_start(sdp);
 				gfs2_ail1_wait(sdp);
-				if (gfs2_ail1_empty(sdp))
+				if (gfs2_ail1_empty(sdp, true))
 					break;
 			}
 			atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */
@@ -1008,7 +1014,7 @@ int gfs2_logd(void *data)
 
 		did_flush = false;
 		if (gfs2_jrnl_flush_reqd(sdp) || t == 0) {
-			gfs2_ail1_empty(sdp);
+			gfs2_ail1_empty(sdp, true);
 			if (test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
 				gfs2_log_flush(sdp, NULL,
 					       GFS2_LOG_HEAD_FLUSH_NORMAL |
@@ -1019,7 +1025,7 @@ int gfs2_logd(void *data)
 		if (gfs2_ail_flush_reqd(sdp)) {
 			gfs2_ail1_start(sdp);
 			gfs2_ail1_wait(sdp);
-			gfs2_ail1_empty(sdp);
+			gfs2_ail1_empty(sdp, true);
 			if (test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
 				gfs2_log_flush(sdp, NULL,
 					       GFS2_LOG_HEAD_FLUSH_NORMAL |
-- 
2.20.1