[PATCH] md: allow available size of component devices to be set 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 866a1a8..7b3d471 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -250,6 +250,13 @@
the device before this offset us not touched, unless it is
used for storing metadata (Formats 1.1 and 1.2).
+ size
+ The amount of the device, after the offset, that can be used
+ for storage of data. This will normally be the same as the
+ component_size. This can be written while assembling an
+ array. If a value less than the current component_size is
+ written, component_size will be reduced to this value.
+
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 27db100..40ac7fb 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1686,12 +1686,37 @@
static struct rdev_sysfs_entry rdev_offset =
__ATTR(offset, 0644, offset_show, offset_store);
+static ssize_t
+rdev_size_show(mdk_rdev_t *rdev, char *page)
+{
+ return sprintf(page, "%llu\n", (unsigned long long)rdev->size);
+}
+
+static ssize_t
+rdev_size_store(mdk_rdev_t *rdev, const char *buf, size_t len)
+{
+ char *e;
+ unsigned long long size = simple_strtoull(buf, &e, 10);
+ if (e==buf || (*e && *e != '\n'))
+ return -EINVAL;
+ if (rdev->mddev->pers)
+ return -EBUSY;
+ rdev->size = size;
+ if (size < rdev->mddev->size || rdev->mddev->size == 0)
+ rdev->mddev->size = size;
+ return len;
+}
+
+static struct rdev_sysfs_entry rdev_size =
+__ATTR(size, 0644, rdev_size_show, rdev_size_store);
+
static struct attribute *rdev_default_attrs[] = {
&rdev_state.attr,
&rdev_super.attr,
&rdev_errors.attr,
&rdev_slot.attr,
&rdev_offset.attr,
+ &rdev_size.attr,
NULL,
};
static ssize_t
