[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 (file)
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -236,6 +236,14 @@ Each directory contains:
        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 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1630,10 +1630,45 @@ errors_store(mdk_rdev_t *rdev, const char *buf, size_t len)
 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