gfs2: Per-revoke accounting in transactions

In the log, revokes are stored as a revoke descriptor (struct
gfs2_log_descriptor), followed by zero or more additional revoke blocks
(struct gfs2_meta_header).  On filesystems with a blocksize of 4k, the
revoke descriptor contains up to 503 revokes, and the metadata blocks
contain up to 509 revokes each.  We've so far been reserving space for
revokes in transactions in block granularity, so a lot more space than
necessary was being allocated and then released again.

This patch switches to assigning revokes to transactions individually
instead.  Initially, space for the revoke descriptor is reserved and
handed out to transactions.  When more revokes than that are reserved,
additional revoke blocks are added.  When the log is flushed, the space
for the additional revoke blocks is released, but we keep the space for
the revoke descriptor block allocated.

Transactions may still reserve more revokes than they will actually need
in the end, but now we won't overshoot the target as much, and by only
returning the space for excess revokes at log flush time, we further
reduce the amount of contention between processes.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 51656b053170..30f67c3c87b0 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -506,7 +506,6 @@ 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;
@@ -821,7 +820,6 @@ struct gfs2_sbd {
 
 	struct gfs2_trans *sd_log_tr;
 	unsigned int sd_log_blks_reserved;
-	int sd_log_committed_revoke;
 
 	atomic_t sd_log_pinned;
 	unsigned int sd_log_num_revoke;
@@ -834,6 +832,7 @@ struct gfs2_sbd {
 	atomic_t sd_log_thresh2;
 	atomic_t sd_log_blks_free;
 	atomic_t sd_log_blks_needed;
+	atomic_t sd_log_revokes_available;
 	wait_queue_head_t sd_log_waitq;
 	wait_queue_head_t sd_logd_waitq;