From: NeilBrown Signed-off-by: Neil Brown Signed-off-by: Andrew Morton --- Documentation/md.txt | 5 +++++ drivers/md/md.c | 27 +++++++++++++++++++++++++++ 2 files changed, 32 insertions(+) diff -puN Documentation/md.txt~md-allow-raid-layout-to-be-read-and-set-via-sysfs Documentation/md.txt --- devel/Documentation/md.txt~md-allow-raid-layout-to-be-read-and-set-via-sysfs 2006-05-31 22:28:21.000000000 -0700 +++ devel-akpm/Documentation/md.txt 2006-05-31 22:28:21.000000000 -0700 @@ -200,6 +200,11 @@ All md devices contain: This can be written only while the array is being assembled, not after it is started. + layout + 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. + new_dev This file can be written but not read. The value written should be a block device number as major:minor. e.g. 8:0 diff -puN drivers/md/md.c~md-allow-raid-layout-to-be-read-and-set-via-sysfs drivers/md/md.c --- devel/drivers/md/md.c~md-allow-raid-layout-to-be-read-and-set-via-sysfs 2006-05-31 22:28:21.000000000 -0700 +++ devel-akpm/drivers/md/md.c 2006-05-31 22:28:21.000000000 -0700 @@ -2155,6 +2155,32 @@ level_store(mddev_t *mddev, const char * 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, susp static struct attribute *md_default_attrs[] = { &md_level.attr, + &md_layout.attr, &md_raid_disks.attr, &md_chunk_size.attr, &md_size.attr, _