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Commit de01dfad authored by NeilBrown's avatar NeilBrown
Browse files

md: Ensure an md array never has too many devices. 



Each different metadata format supported by md supports a
different maximum number of devices.
We really should be enforcing this maximum in the kernel, but
we aren't quite doing that properly.

We currently only enforce it at the 'hot_add' point, which is an
older interface which is not used by current userspace.

We need to also enforce it at 'add_new_disk' time for active arrays
and at 'do_md_run' time when starting a new array.

So move the test from 'hot_add' into 'bind_rdev_to_array' which is
called from both 'hot_add' and 'add_new_disk, and add a new
test in 'analyse_sbs' which is called from 'do_md_run'.

This bug (or missing feature) has been around "forever" and so
the patch is suitable for any -stable that is currently maintained.

Cc: stable@kernel.org

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 852c8bf4

drivers/md/md.c

+14 −10
Original line number Diff line number Diff line
@@ -1481,6 +1481,11 @@ static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev) 
		if (find_rdev_nr(mddev, rdev->desc_nr))

			return -EBUSY;

	}

	if (mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {

		printk(KERN_WARNING "md: %s: array is limited to %d devices\n",

		       mdname(mddev), mddev->max_disks);

		return -EBUSY;

	}

	bdevname(rdev->bdev,b);

	while ( (s=strchr(b, '/')) != NULL)

		*s = '!';
@@ -2441,6 +2446,15 @@ static void analyze_sbs(mddev_t * mddev) 


	i = 0;

	rdev_for_each(rdev, tmp, mddev) {

		if (rdev->desc_nr >= mddev->max_disks ||

		    i > mddev->max_disks) {

			printk(KERN_WARNING

			       "md: %s: %s: only %d devices permitted\n",

			       mdname(mddev), bdevname(rdev->bdev, b),

			       mddev->max_disks);

			kick_rdev_from_array(rdev);

			continue;

		}

		if (rdev != freshest)

			if (super_types[mddev->major_version].

			    validate_super(mddev, rdev)) {
@@ -4614,13 +4628,6 @@ static int hot_add_disk(mddev_t * mddev, dev_t dev) 
	 * noticed in interrupt contexts ...

	 */



	if (rdev->desc_nr == mddev->max_disks) {

		printk(KERN_WARNING "%s: can not hot-add to full array!\n",

			mdname(mddev));

		err = -EBUSY;

		goto abort_unbind_export;

	}



	rdev->raid_disk = -1;



	md_update_sb(mddev, 1);
@@ -4634,9 +4641,6 @@ static int hot_add_disk(mddev_t * mddev, dev_t dev) 
	md_new_event(mddev);

	return 0;



abort_unbind_export:

	unbind_rdev_from_array(rdev);



abort_export:

	export_rdev(rdev);

	return err;