Commit a20ffa7d authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

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.

For developers, it might be useful to construct btrees of various
heights by crafting a filesystem with a certain number of records and
then using repair+knobs to rebuild the index with a certain shape.
Practically speaking, you'd only ever do that for extreme stress
testing of the runtime code or the btree generator.

Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 26de6462

fs/xfs/scrub/newbt.c

+8 −3
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
 * btree bulk loading code calculates for us.  However, there are some

 * exceptions to this rule:

 *

 * (0) If someone turned one of the debug knobs.

 * (1) If this is a per-AG btree and the AG has less than 10% space free.

 * (2) If this is an inode btree and the FS has less than 10% space free.
@@ -47,9 +48,13 @@ xrep_newbt_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;

fs/xfs/xfs_globals.c

+12 −0
Original line number Diff line number Diff line
@@ -44,4 +44,16 @@ struct xfs_globals xfs_globals = { 
	.pwork_threads		=	-1,	/* automatic thread detection */

	.larp			=	false,	/* log attribute replay */

#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,

};

fs/xfs/xfs_sysctl.h

+2 −0
Original line number Diff line number Diff line
@@ -85,6 +85,8 @@ struct xfs_globals { 
	int	pwork_threads;		/* parallel workqueue threads */

	bool	larp;			/* log attribute replay */

#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 */

fs/xfs/xfs_sysfs.c

+54 −0
Original line number Diff line number Diff line
@@ -262,6 +262,58 @@ larp_show( 
XFS_SYSFS_ATTR_RW(larp);

#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),
@@ -271,6 +323,8 @@ static struct attribute *xfs_dbg_attrs[] = { 
	ATTR_LIST(pwork_threads),

	ATTR_LIST(larp),

#endif

	ATTR_LIST(bload_leaf_slack),

	ATTR_LIST(bload_node_slack),

	NULL,

};

ATTRIBUTE_GROUPS(xfs_dbg);