[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.
 
        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
 
 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 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,
 static struct attribute *rdev_default_attrs[] = {
        &rdev_state.attr,
        &rdev_super.attr,
        &rdev_errors.attr,

+       &rdev_slot.attr,

        NULL,
 };
 static ssize_t
        NULL,
 };
 static ssize_t