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-rw-r--r--Documentation/md.txt7
-rw-r--r--drivers/md/md.c25
2 files changed, 32 insertions, 0 deletions
diff --git a/Documentation/md.txt b/Documentation/md.txt
index 866a1a887547..7b3d471bb9f0 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -250,6 +250,13 @@ Each directory contains:
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 27db100d8b12..40ac7fbab61f 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1686,12 +1686,37 @@ offset_store(mdk_rdev_t *rdev, const char *buf, size_t len)
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