Commit d4dbd025 authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: Allow raid 'layout' to be read and set via sysfs

Signed-off-by: default avatarNeil Brown <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 45dc2de1
......@@ -200,6 +200,11 @@ All md devices contain:
This can be written only while the array is being assembled, not
after it is started.
The "layout" for the array for the particular level. This is
simply a number that is interpretted differently by different
levels. It can be written while assembling an array.
This file can be written but not read. The value written should
be a block device number as major:minor. e.g. 8:0
......@@ -2155,6 +2155,32 @@ level_store(mddev_t *mddev, const char *buf, size_t len)
static struct md_sysfs_entry md_level =
__ATTR(level, 0644, level_show, level_store);
static ssize_t
layout_show(mddev_t *mddev, char *page)
/* just a number, not meaningful for all levels */
return sprintf(page, "%d\n", mddev->layout);
static ssize_t
layout_store(mddev_t *mddev, const char *buf, size_t len)
char *e;
unsigned long n = simple_strtoul(buf, &e, 10);
if (mddev->pers)
return -EBUSY;
if (!*buf || (*e && *e != '\n'))
return -EINVAL;
mddev->layout = n;
return len;
static struct md_sysfs_entry md_layout =
__ATTR(layout, 0655, layout_show, layout_store);
static ssize_t
raid_disks_show(mddev_t *mddev, char *page)
......@@ -2741,6 +2767,7 @@ __ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);
static struct attribute *md_default_attrs[] = {
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