[PATCH] md: expose device slot information via sysfs
This the role that a device has in an array can be viewed and set.
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>
diff --git a/Documentation/md.txt b/Documentation/md.txt
index 69f742d..d525fff 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -236,6 +236,14 @@
providing an ongoing count for arrays with metadata managed by
userspace.
+ slot
+ This gives the role that the device has in the array. It will
+ either be 'none' if the device is not active in the array
+ (i.e. is a spare or has failed) or an integer less than the
+ 'raid_disks' number for the array indicating which possition
+ it currently fills. This can only be set while assembling an
+ array. A device for which this is set is assumed to be working.
+
An active md device will also contain and entry for each active device
in the array. These are named
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 27a9871..a816956 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1630,10 +1630,45 @@
static struct rdev_sysfs_entry rdev_errors =
__ATTR(errors, 0644, errors_show, errors_store);
+static ssize_t
+slot_show(mdk_rdev_t *rdev, char *page)
+{
+ if (rdev->raid_disk < 0)
+ return sprintf(page, "none\n");
+ else
+ return sprintf(page, "%d\n", rdev->raid_disk);
+}
+
+static ssize_t
+slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
+{
+ char *e;
+ int slot = simple_strtoul(buf, &e, 10);
+ if (strncmp(buf, "none", 4)==0)
+ slot = -1;
+ else if (e==buf || (*e && *e!= '\n'))
+ return -EINVAL;
+ if (rdev->mddev->pers)
+ /* Cannot set slot in active array (yet) */
+ return -EBUSY;
+ if (slot >= rdev->mddev->raid_disks)
+ return -ENOSPC;
+ rdev->raid_disk = slot;
+ /* assume it is working */
+ rdev->flags = 0;
+ set_bit(In_sync, &rdev->flags);
+ return len;
+}
+
+
+static struct rdev_sysfs_entry rdev_slot =
+__ATTR(slot, 0644, slot_show, slot_store);
+
static struct attribute *rdev_default_attrs[] = {
&rdev_state.attr,
&rdev_super.attr,
&rdev_errors.attr,
+ &rdev_slot.attr,
NULL,
};
static ssize_t
