xfs: split the CIL lock

The xc_cil_lock is used for two purposes - to protect the CIL
itself, and to protect the push/commit state and lists. These are
two logically separate structures and operations, so can have their
own locks. This means that pushing on the CIL and the commit wait
ordering won't contend for a lock with other transactions that are
completing concurrently. As the CIL insertion is the hottest path
throught eh CIL, this is a big win.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 21 insertions, 20 deletions

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index c1a3384406fd..cfe97973ba36 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -402,9 +402,9 @@ xlog_cil_committed(
 	xfs_extent_busy_clear(mp, &ctx->busy_extents,
 			     (mp->m_flags & XFS_MOUNT_DISCARD) && !abort);
 
-	spin_lock(&ctx->cil->xc_cil_lock);
+	spin_lock(&ctx->cil->xc_push_lock);
 	list_del(&ctx->committing);
-	spin_unlock(&ctx->cil->xc_cil_lock);
+	spin_unlock(&ctx->cil->xc_push_lock);
 
 	xlog_cil_free_logvec(ctx->lv_chain);
 
@@ -459,7 +459,7 @@ xlog_cil_push(
 	down_write(&cil->xc_ctx_lock);
 	ctx = cil->xc_ctx;
 
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	push_seq = cil->xc_push_seq;
 	ASSERT(push_seq <= ctx->sequence);
 
@@ -470,10 +470,10 @@ xlog_cil_push(
 	 */
 	if (list_empty(&cil->xc_cil)) {
 		cil->xc_push_seq = 0;
-		spin_unlock(&cil->xc_cil_lock);
+		spin_unlock(&cil->xc_push_lock);
 		goto out_skip;
 	}
-	spin_unlock(&cil->xc_cil_lock);
+	spin_unlock(&cil->xc_push_lock);
 
 
 	/* check for a previously pushed seqeunce */
@@ -541,9 +541,9 @@ xlog_cil_push(
 	 * that higher sequences will wait for us to write out a commit record
 	 * before they do.
 	 */
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	list_add(&ctx->committing, &cil->xc_committing);
-	spin_unlock(&cil->xc_cil_lock);
+	spin_unlock(&cil->xc_push_lock);
 	up_write(&cil->xc_ctx_lock);
 
 	/*
@@ -578,7 +578,7 @@ xlog_cil_push(
 	 * order the commit records so replay will get them in the right order.
 	 */
 restart:
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	list_for_each_entry(new_ctx, &cil->xc_committing, committing) {
 		/*
 		 * Higher sequences will wait for this one so skip them.
@@ -591,11 +591,11 @@ restart:
 			 * It is still being pushed! Wait for the push to
 			 * complete, then start again from the beginning.
 			 */
-			xlog_wait(&cil->xc_commit_wait, &cil->xc_cil_lock);
+			xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
 			goto restart;
 		}
 	}
-	spin_unlock(&cil->xc_cil_lock);
+	spin_unlock(&cil->xc_push_lock);
 
 	/* xfs_log_done always frees the ticket on error. */
 	commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, 0);
@@ -614,10 +614,10 @@ restart:
 	 * callbacks to the iclog we can assign the commit LSN to the context
 	 * and wake up anyone who is waiting for the commit to complete.
 	 */
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	ctx->commit_lsn = commit_lsn;
 	wake_up_all(&cil->xc_commit_wait);
-	spin_unlock(&cil->xc_cil_lock);
+	spin_unlock(&cil->xc_push_lock);
 
 	/* release the hounds! */
 	return xfs_log_release_iclog(log->l_mp, commit_iclog);
@@ -670,12 +670,12 @@ xlog_cil_push_background(
 	if (cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
 		return;
 
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	if (cil->xc_push_seq < cil->xc_current_sequence) {
 		cil->xc_push_seq = cil->xc_current_sequence;
 		queue_work(log->l_mp->m_cil_workqueue, &cil->xc_push_work);
 	}
-	spin_unlock(&cil->xc_cil_lock);
+	spin_unlock(&cil->xc_push_lock);
 
 }
 
@@ -698,14 +698,14 @@ xlog_cil_push_foreground(
 	 * If the CIL is empty or we've already pushed the sequence then
 	 * there's no work we need to do.
 	 */
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	if (list_empty(&cil->xc_cil) || push_seq <= cil->xc_push_seq) {
-		spin_unlock(&cil->xc_cil_lock);
+		spin_unlock(&cil->xc_push_lock);
 		return;
 	}
 
 	cil->xc_push_seq = push_seq;
-	spin_unlock(&cil->xc_cil_lock);
+	spin_unlock(&cil->xc_push_lock);
 
 	/* do the push now */
 	xlog_cil_push(log);
@@ -808,7 +808,7 @@ xlog_cil_force_lsn(
 	 * on commits for those as well.
 	 */
 restart:
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	list_for_each_entry(ctx, &cil->xc_committing, committing) {
 		if (ctx->sequence > sequence)
 			continue;
@@ -817,7 +817,7 @@ restart:
 			 * It is still being pushed! Wait for the push to
 			 * complete, then start again from the beginning.
 			 */
-			xlog_wait(&cil->xc_commit_wait, &cil->xc_cil_lock);
+			xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
 			goto restart;
 		}
 		if (ctx->sequence != sequence)
@@ -825,7 +825,7 @@ restart:
 		/* found it! */
 		commit_lsn = ctx->commit_lsn;
 	}
-	spin_unlock(&cil->xc_cil_lock);
+	spin_unlock(&cil->xc_push_lock);
 	return commit_lsn;
 }
 
@@ -883,6 +883,7 @@ xlog_cil_init(
 	INIT_LIST_HEAD(&cil->xc_cil);
 	INIT_LIST_HEAD(&cil->xc_committing);
 	spin_lock_init(&cil->xc_cil_lock);
+	spin_lock_init(&cil->xc_push_lock);
 	init_rwsem(&cil->xc_ctx_lock);
 	init_waitqueue_head(&cil->xc_commit_wait);