xfs: add the xlog_grant_head structure

Add a new data structure to allow sharing code between the log grant and
regrant code.
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_log_priv.h

@@ -469,6 +469,16 @@ struct xfs_cil {
 #define XLOG_CIL_SPACE_LIMIT(log)	(log->l_logsize >> 3)
 #define XLOG_CIL_HARD_SPACE_LIMIT(log)	(3 * (log->l_logsize >> 4))
 
+/*
+ * ticket grant locks, queues and accounting have their own cachlines
+ * as these are quite hot and can be operated on concurrently.
+ */
+struct xlog_grant_head {
+	spinlock_t		lock ____cacheline_aligned_in_smp;
+	struct list_head	waiters;
+	atomic64_t		grant;
+};
+
 /*
  * The reservation head lsn is not made up of a cycle number and block number.
  * Instead, it uses a cycle number and byte number.  Logs don't expect to
@@ -520,17 +530,8 @@ typedef struct log {
 	/* lsn of 1st LR with unflushed * buffers */
 	atomic64_t		l_tail_lsn ____cacheline_aligned_in_smp;
 
-	/*
-	 * ticket grant locks, queues and accounting have their own cachlines
-	 * as these are quite hot and can be operated on concurrently.
-	 */
-	spinlock_t		l_grant_reserve_lock ____cacheline_aligned_in_smp;
-	struct list_head	l_reserveq;
-	atomic64_t		l_grant_reserve_head;
-
-	spinlock_t		l_grant_write_lock ____cacheline_aligned_in_smp;
-	struct list_head	l_writeq;
-	atomic64_t		l_grant_write_head;
+	struct xlog_grant_head	l_reserve_head;
+	struct xlog_grant_head	l_write_head;
 
 	/* The following field are used for debugging; need to hold icloglock */
 #ifdef DEBUG

fs/xfs/xfs_log_recover.c

@@ -965,9 +965,9 @@ xlog_find_tail(
 		log->l_curr_cycle++;
 	atomic64_set(&log->l_tail_lsn, be64_to_cpu(rhead->h_tail_lsn));
 	atomic64_set(&log->l_last_sync_lsn, be64_to_cpu(rhead->h_lsn));
-	xlog_assign_grant_head(&log->l_grant_reserve_head, log->l_curr_cycle,
+	xlog_assign_grant_head(&log->l_reserve_head.grant, log->l_curr_cycle,
 					BBTOB(log->l_curr_block));
-	xlog_assign_grant_head(&log->l_grant_write_head, log->l_curr_cycle,
+	xlog_assign_grant_head(&log->l_write_head.grant, log->l_curr_cycle,
 					BBTOB(log->l_curr_block));
 
 	/*

fs/xfs/xfs_trace.h

@@ -782,12 +782,12 @@ DECLARE_EVENT_CLASS(xfs_loggrant_class,
 		__entry->curr_res = tic->t_curr_res;
 		__entry->unit_res = tic->t_unit_res;
 		__entry->flags = tic->t_flags;
-		__entry->reserveq = list_empty(&log->l_reserveq);
-		__entry->writeq = list_empty(&log->l_writeq);
-		xlog_crack_grant_head(&log->l_grant_reserve_head,
+		__entry->reserveq = list_empty(&log->l_reserve_head.waiters);
+		__entry->writeq = list_empty(&log->l_write_head.waiters);
+		xlog_crack_grant_head(&log->l_reserve_head.grant,
 				&__entry->grant_reserve_cycle,
 				&__entry->grant_reserve_bytes);
-		xlog_crack_grant_head(&log->l_grant_write_head,
+		xlog_crack_grant_head(&log->l_write_head.grant,
 				&__entry->grant_write_cycle,
 				&__entry->grant_write_bytes);
 		__entry->curr_cycle = log->l_curr_cycle;