[PATCH] md: support adding new devices to md arrays via sysfs

Writing major:minor to md/new_dev will bind that device to the array.

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 7b3d471bb9f0f6c5a34f3b10035c366c03ff2adf..b8d172b254f74a29f2b3c54203955109748c0266 100644 (file)
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -200,6 +200,14 @@ All md devices contain:
      This can be written only while the array is being assembled, not
      after it is started.
 
+   new_dev
+     This file can be written but not read.  The value written should
+     be a block device number as major:minor.  e.g. 8:0
+     This will cause that device to be attached to the array, if it is
+     available.  It will then appear at md/dev-XXX (depending on the
+     name of the device) and further configuration is then possible.
+
+
 As component devices are added to an md array, they appear in the 'md'
 directory as new directories named
       dev-XXX

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 40ac7fbab61fd14c2e98e272a8f8ec6742e4cb10..825e235b791bf55f2cf610f43d50a0681b36f18f 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1987,6 +1987,65 @@ chunk_size_store(mddev_t *mddev, const char *buf, size_t len)
 static struct md_sysfs_entry md_chunk_size =
 __ATTR(chunk_size, 0644, chunk_size_show, chunk_size_store);
 
+static ssize_t
+null_show(mddev_t *mddev, char *page)
+{
+       return -EINVAL;
+}
+
+static ssize_t
+new_dev_store(mddev_t *mddev, const char *buf, size_t len)
+{
+       /* buf must be %d:%d\n? giving major and minor numbers */
+       /* The new device is added to the array.
+        * If the array has a persistent superblock, we read the
+        * superblock to initialise info and check validity.
+        * Otherwise, only checking done is that in bind_rdev_to_array,
+        * which mainly checks size.
+        */
+       char *e;
+       int major = simple_strtoul(buf, &e, 10);
+       int minor;
+       dev_t dev;
+       mdk_rdev_t *rdev;
+       int err;
+
+       if (!*buf || *e != ':' || !e[1] || e[1] == '\n')
+               return -EINVAL;
+       minor = simple_strtoul(e+1, &e, 10);
+       if (*e && *e != '\n')
+               return -EINVAL;
+       dev = MKDEV(major, minor);
+       if (major != MAJOR(dev) ||
+           minor != MINOR(dev))
+               return -EOVERFLOW;
+
+
+       if (mddev->persistent) {
+               rdev = md_import_device(dev, mddev->major_version,
+                                       mddev->minor_version);
+               if (!IS_ERR(rdev) && !list_empty(&mddev->disks)) {
+                       mdk_rdev_t *rdev0 = list_entry(mddev->disks.next,
+                                                      mdk_rdev_t, same_set);
+                       err = super_types[mddev->major_version]
+                               .load_super(rdev, rdev0, mddev->minor_version);
+                       if (err < 0)
+                               goto out;
+               }
+       } else
+               rdev = md_import_device(dev, -1, -1);
+
+       if (IS_ERR(rdev))
+               return PTR_ERR(rdev);
+       err = bind_rdev_to_array(rdev, mddev);
+ out:
+       if (err)
+               export_rdev(rdev);
+       return err ? err : len;
+}
+
+static struct md_sysfs_entry md_new_device =
+__ATTR(new_dev, 0200, null_show, new_dev_store);
 
 static ssize_t
 size_show(mddev_t *mddev, char *page)
@@ -2144,6 +2203,7 @@ static struct attribute *md_default_attrs[] = {
        &md_chunk_size.attr,
        &md_size.attr,
        &md_metadata.attr,
+       &md_new_device.attr,
        NULL,
 };