[PATCH] md: allow chunk_size to be settable through sysfs

... only before array is started of course.

Signed-off-by: Neil Brown <neilb@suse.de>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 0b3081aa4d63..9e57e97bd530 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1795,6 +1795,31 @@ raid_disks_show(mddev_t *mddev, char *page)
 static struct md_sysfs_entry md_raid_disks = __ATTR_RO(raid_disks);
 
 static ssize_t
+chunk_size_show(mddev_t *mddev, char *page)
+{
+        return sprintf(page, "%d\n", mddev->chunk_size);
+}
+
+static ssize_t
+chunk_size_store(mddev_t *mddev, const char *buf, size_t len)
+{
+        /* can only set chunk_size if array is not yet active */
+        char *e;
+        unsigned long n = simple_strtoul(buf, &e, 10);
+
+        if (mddev->pers)
+                return -EBUSY;
+        if (!*buf || (*e && *e != '\n'))
+                return -EINVAL;
+
+        mddev->chunk_size = n;
+        return len;
+}
+static struct md_sysfs_entry md_chunk_size =
+__ATTR(chunk_size, 0644, chunk_size_show, chunk_size_store);
+
+
+static ssize_t
 action_show(mddev_t *mddev, char *page)
 {
         char *type = "idle";
@@ -1861,6 +1886,7 @@ md_mismatches = __ATTR_RO(mismatch_cnt);
 static struct attribute *md_default_attrs[] = {
         &md_level.attr,
         &md_raid_disks.attr,
+        &md_chunk_size.attr,
         NULL,
 };