xfs: add debug knobs to control btree bulk load slack factors

Add some debug knobs so that we can control the leaf and node block
slack when rebuilding btrees.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

4 files changed, 75 insertions, 3 deletions

diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index d967c704b507..669c33460d31 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -654,9 +654,13 @@ xrep_bload_estimate_slack(
 	uint64_t		free;
 	uint64_t		sz;
 
-	/* Let the btree code compute the default slack values. */
-	bload->leaf_slack = -1;
-	bload->node_slack = -1;
+	/*
+	 * The xfs_globals values are set to -1 (i.e. take the bload defaults)
+	 * unless someone has set them otherwise, so we just pull the values
+	 * here.
+	 */
+	bload->leaf_slack = xfs_globals.bload_leaf_slack;
+	bload->node_slack = xfs_globals.bload_node_slack;
 
 	if (sc->ops->type == ST_PERAG) {
 		free = sc->sa.pag->pagf_freeblks;
diff --git a/fs/xfs/xfs_globals.c b/fs/xfs/xfs_globals.c
index fa55ab8b8d80..4e747384ad26 100644
--- a/fs/xfs/xfs_globals.c
+++ b/fs/xfs/xfs_globals.c
@@ -43,4 +43,16 @@ struct xfs_globals xfs_globals = {
 #ifdef DEBUG
 	.pwork_threads		=	-1,	/* automatic thread detection */
 #endif
+
+	/*
+	 * Leave this many record slots empty when bulk loading btrees.  By
+	 * default we load new btree leaf blocks 75% full.
+	 */
+	.bload_leaf_slack	=	-1,
+
+	/*
+	 * Leave this many key/ptr slots empty when bulk loading btrees.  By
+	 * default we load new btree node blocks 75% full.
+	 */
+	.bload_node_slack	=	-1,
 };
diff --git a/fs/xfs/xfs_sysctl.h b/fs/xfs/xfs_sysctl.h
index 8abf4640f1d5..aecccceee4ca 100644
--- a/fs/xfs/xfs_sysctl.h
+++ b/fs/xfs/xfs_sysctl.h
@@ -85,6 +85,8 @@ struct xfs_globals {
 #ifdef DEBUG
 	int	pwork_threads;		/* parallel workqueue threads */
 #endif
+	int	bload_leaf_slack;	/* btree bulk load leaf slack */
+	int	bload_node_slack;	/* btree bulk load node slack */
 	int	log_recovery_delay;	/* log recovery delay (secs) */
 	int	mount_delay;		/* mount setup delay (secs) */
 	bool	bug_on_assert;		/* BUG() the kernel on assert failure */
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index f1bc88f4367c..673ad21a9585 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -228,6 +228,58 @@ pwork_threads_show(
 XFS_SYSFS_ATTR_RW(pwork_threads);
 #endif /* DEBUG */
 
+STATIC ssize_t
+bload_leaf_slack_store(
+	struct kobject	*kobject,
+	const char	*buf,
+	size_t		count)
+{
+	int		ret;
+	int		val;
+
+	ret = kstrtoint(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	xfs_globals.bload_leaf_slack = val;
+	return count;
+}
+
+STATIC ssize_t
+bload_leaf_slack_show(
+	struct kobject	*kobject,
+	char		*buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", xfs_globals.bload_leaf_slack);
+}
+XFS_SYSFS_ATTR_RW(bload_leaf_slack);
+
+STATIC ssize_t
+bload_node_slack_store(
+	struct kobject	*kobject,
+	const char	*buf,
+	size_t		count)
+{
+	int		ret;
+	int		val;
+
+	ret = kstrtoint(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	xfs_globals.bload_node_slack = val;
+	return count;
+}
+
+STATIC ssize_t
+bload_node_slack_show(
+	struct kobject	*kobject,
+	char		*buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", xfs_globals.bload_node_slack);
+}
+XFS_SYSFS_ATTR_RW(bload_node_slack);
+
 static struct attribute *xfs_dbg_attrs[] = {
 	ATTR_LIST(bug_on_assert),
 	ATTR_LIST(log_recovery_delay),
@@ -236,6 +288,8 @@ static struct attribute *xfs_dbg_attrs[] = {
 #ifdef DEBUG
 	ATTR_LIST(pwork_threads),
 #endif
+	ATTR_LIST(bload_leaf_slack),
+	ATTR_LIST(bload_node_slack),
 	NULL,
 };