[PATCH] md: export rdev->data_offset via sysfs

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 d525fff..866a1a8 100644 (file)
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -244,6 +244,12 @@ Each directory contains:
        it currently fills.  This can only be set while assembling an
        array.  A device for which this is set is assumed to be working.
 
+      offset
+        This gives the location in the device (in sectors from the
+        start) where data from the array will be stored.  Any part of
+        the device before this offset us not touched, unless it is
+        used for storing metadata (Formats 1.1 and 1.2).
+
 
 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 a816956..742a82a 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1664,11 +1664,34 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
 static struct rdev_sysfs_entry rdev_slot =
 __ATTR(slot, 0644, slot_show, slot_store);
 
+static ssize_t
+offset_show(mdk_rdev_t *rdev, char *page)
+{
+       return sprintf(page, "%llu\n", rdev->data_offset);
+}
+
+static ssize_t
+offset_store(mdk_rdev_t *rdev, const char *buf, size_t len)
+{
+       char *e;
+       unsigned long long offset = simple_strtoull(buf, &e, 10);
+       if (e==buf || (*e && *e != '\n'))
+               return -EINVAL;
+       if (rdev->mddev->pers)
+               return -EBUSY;
+       rdev->data_offset = offset;
+       return len;
+}
+
+static struct rdev_sysfs_entry rdev_offset =
+__ATTR(offset, 0644, offset_show, offset_store);
+
 static struct attribute *rdev_default_attrs[] = {
        &rdev_state.attr,
        &rdev_super.attr,
        &rdev_errors.attr,
        &rdev_slot.attr,
+       &rdev_offset.attr,
        NULL,
 };
 static ssize_t