[Cluster-devel] [GFS2 PATCH 1/2 v3] Revert "gfs2: eliminate tr_num_revoke_rm"

[Bob Peterson <rpeterso@redhat.com>]

This reverts commit e955537e3262de8e56f070b13817f525f472fa00.

Before patch e955537e32, tr_num_revoke tracked the number of revokes
added to the transaction, and tr_num_revoke_rm tracked how many
revokes were removed. But since revokes are queued off the sdp
(superblock) pointer, some transactions could remove more revokes
than they added. (e.g. revokes added by a different process).
Commit e955537e32 eliminated transaction variable tr_num_revoke_rm,
but in order to do so, it changed the accounting to always use
tr_num_revoke for its math. Since you can remove more revokes than
you add, tr_num_revoke could now become a negative value.
This negative value broke the assert in function gfs2_trans_end:

	if (gfs2_assert_withdraw(sdp, (nbuf <= tr->tr_blocks) &&
			       (tr->tr_num_revoke <= tr->tr_revokes)))

One way to fix this is to simply remove the tr_num_revoke clause
from the assert and allow the value to become negative. Andreas
didn't like that idea, so instead, we decided to revert e955537e32.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/incore.h | 1 +
 fs/gfs2/log.c    | 3 ++-
 fs/gfs2/trans.c  | 6 +++---
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index b5d9c11f4901..a5d81a261f77 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -505,6 +505,7 @@ struct gfs2_trans {
 	unsigned int tr_num_buf_rm;
 	unsigned int tr_num_databuf_rm;
 	unsigned int tr_num_revoke;
+	unsigned int tr_num_revoke_rm;
 
 	struct list_head tr_list;
 	struct list_head tr_databuf;
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 66189ae62c1d..6e2728416b6b 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -895,6 +895,7 @@ static void gfs2_merge_trans(struct gfs2_trans *old, struct gfs2_trans *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);
@@ -916,7 +917,7 @@ static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 		set_bit(TR_ATTACHED, &tr->tr_flags);
 	}
 
-	sdp->sd_log_commited_revoke += tr->tr_num_revoke;
+	sdp->sd_log_commited_revoke += tr->tr_num_revoke - tr->tr_num_revoke_rm;
 	reserved = calc_reserved(sdp);
 	maxres = sdp->sd_log_blks_reserved + tr->tr_reserved;
 	gfs2_assert_withdraw(sdp, maxres >= reserved);
diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index 4d01fe19c125..a685637a5b55 100644
--- a/fs/gfs2/trans.c
+++ b/fs/gfs2/trans.c
@@ -76,10 +76,10 @@ static void gfs2_print_trans(struct gfs2_sbd *sdp, const struct gfs2_trans *tr)
 	fs_warn(sdp, "blocks=%u revokes=%u reserved=%u touched=%u\n",
 		tr->tr_blocks, tr->tr_revokes, tr->tr_reserved,
 		test_bit(TR_TOUCHED, &tr->tr_flags));
-	fs_warn(sdp, "Buf %u/%u Databuf %u/%u Revoke %u\n",
+	fs_warn(sdp, "Buf %u/%u Databuf %u/%u Revoke %u/%u\n",
 		tr->tr_num_buf_new, tr->tr_num_buf_rm,
 		tr->tr_num_databuf_new, tr->tr_num_databuf_rm,
-		tr->tr_num_revoke);
+		tr->tr_num_revoke, tr->tr_num_revoke_rm);
 }
 
 void gfs2_trans_end(struct gfs2_sbd *sdp)
@@ -264,7 +264,7 @@ void gfs2_trans_remove_revoke(struct gfs2_sbd *sdp, u64 blkno, unsigned int len)
 			if (bd->bd_gl)
 				gfs2_glock_remove_revoke(bd->bd_gl);
 			kmem_cache_free(gfs2_bufdata_cachep, bd);
-			tr->tr_num_revoke--;
+			tr->tr_num_revoke_rm++;
 			if (--n == 0)
 				break;
 		}
-- 
2.24.1