md: allow devices to be shared between md arrays
Currently, a given device is "claimed" by a particular array so that it cannot
be used by other arrays.
This is not ideal for DDF and other metadata schemes which have their own
partitioning concept.
So for externally managed metadata, just claim the device for md in general,
require that "offset" and "size" are set properly for each device, and make
sure that if a device is included in different arrays then the active sections
do not overlap.
This involves adding another flag to the rdev which makes it awkward to set
"->flags = 0" to clear certain flags. So now clear flags explicitly by name
when we want to clear things.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 78fe3e9..7c9a87b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -774,7 +774,11 @@
__u64 ev1 = md_event(sb);
rdev->raid_disk = -1;
- rdev->flags = 0;
+ clear_bit(Faulty, &rdev->flags);
+ clear_bit(In_sync, &rdev->flags);
+ clear_bit(WriteMostly, &rdev->flags);
+ clear_bit(BarriersNotsupp, &rdev->flags);
+
if (mddev->raid_disks == 0) {
mddev->major_version = 0;
mddev->minor_version = sb->minor_version;
@@ -1154,7 +1158,11 @@
__u64 ev1 = le64_to_cpu(sb->events);
rdev->raid_disk = -1;
- rdev->flags = 0;
+ clear_bit(Faulty, &rdev->flags);
+ clear_bit(In_sync, &rdev->flags);
+ clear_bit(WriteMostly, &rdev->flags);
+ clear_bit(BarriersNotsupp, &rdev->flags);
+
if (mddev->raid_disks == 0) {
mddev->major_version = 1;
mddev->patch_version = 0;
@@ -1402,7 +1410,7 @@
goto fail;
}
list_add(&rdev->same_set, &mddev->disks);
- bd_claim_by_disk(rdev->bdev, rdev, mddev->gendisk);
+ bd_claim_by_disk(rdev->bdev, rdev->bdev->bd_holder, mddev->gendisk);
return 0;
fail:
@@ -1442,7 +1450,7 @@
* otherwise reused by a RAID array (or any other kernel
* subsystem), by bd_claiming the device.
*/
-static int lock_rdev(mdk_rdev_t *rdev, dev_t dev)
+static int lock_rdev(mdk_rdev_t *rdev, dev_t dev, int shared)
{
int err = 0;
struct block_device *bdev;
@@ -1454,13 +1462,15 @@
__bdevname(dev, b));
return PTR_ERR(bdev);
}
- err = bd_claim(bdev, rdev);
+ err = bd_claim(bdev, shared ? (mdk_rdev_t *)lock_rdev : rdev);
if (err) {
printk(KERN_ERR "md: could not bd_claim %s.\n",
bdevname(bdev, b));
blkdev_put(bdev);
return err;
}
+ if (!shared)
+ set_bit(AllReserved, &rdev->flags);
rdev->bdev = bdev;
return err;
}
@@ -1925,7 +1935,8 @@
return -ENOSPC;
rdev->raid_disk = slot;
/* assume it is working */
- rdev->flags = 0;
+ clear_bit(Faulty, &rdev->flags);
+ clear_bit(WriteMostly, &rdev->flags);
set_bit(In_sync, &rdev->flags);
}
return len;
@@ -1950,6 +1961,10 @@
return -EINVAL;
if (rdev->mddev->pers)
return -EBUSY;
+ if (rdev->size && rdev->mddev->external)
+ /* Must set offset before size, so overlap checks
+ * can be sane */
+ return -EBUSY;
rdev->data_offset = offset;
return len;
}
@@ -1963,16 +1978,69 @@
return sprintf(page, "%llu\n", (unsigned long long)rdev->size);
}
+static int overlaps(sector_t s1, sector_t l1, sector_t s2, sector_t l2)
+{
+ /* check if two start/length pairs overlap */
+ if (s1+l1 <= s2)
+ return 0;
+ if (s2+l2 <= s1)
+ return 0;
+ return 1;
+}
+
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);
+ unsigned long long oldsize = rdev->size;
if (e==buf || (*e && *e != '\n'))
return -EINVAL;
if (rdev->mddev->pers)
return -EBUSY;
rdev->size = size;
+ if (size > oldsize && rdev->mddev->external) {
+ /* need to check that all other rdevs with the same ->bdev
+ * do not overlap. We need to unlock the mddev to avoid
+ * a deadlock. We have already changed rdev->size, and if
+ * we have to change it back, we will have the lock again.
+ */
+ mddev_t *mddev;
+ int overlap = 0;
+ struct list_head *tmp, *tmp2;
+
+ mddev_unlock(rdev->mddev);
+ ITERATE_MDDEV(mddev, tmp) {
+ mdk_rdev_t *rdev2;
+
+ mddev_lock(mddev);
+ ITERATE_RDEV(mddev, rdev2, tmp2)
+ if (test_bit(AllReserved, &rdev2->flags) ||
+ (rdev->bdev == rdev2->bdev &&
+ rdev != rdev2 &&
+ overlaps(rdev->data_offset, rdev->size,
+ rdev2->data_offset, rdev2->size))) {
+ overlap = 1;
+ break;
+ }
+ mddev_unlock(mddev);
+ if (overlap) {
+ mddev_put(mddev);
+ break;
+ }
+ }
+ mddev_lock(rdev->mddev);
+ if (overlap) {
+ /* Someone else could have slipped in a size
+ * change here, but doing so is just silly.
+ * We put oldsize back because we *know* it is
+ * safe, and trust userspace not to race with
+ * itself
+ */
+ rdev->size = oldsize;
+ return -EBUSY;
+ }
+ }
if (size < rdev->mddev->size || rdev->mddev->size == 0)
rdev->mddev->size = size;
return len;
@@ -2056,7 +2124,7 @@
if ((err = alloc_disk_sb(rdev)))
goto abort_free;
- err = lock_rdev(rdev, newdev);
+ err = lock_rdev(rdev, newdev, super_format == -2);
if (err)
goto abort_free;
@@ -2609,7 +2677,9 @@
if (err < 0)
goto out;
}
- } else
+ } else if (mddev->external)
+ rdev = md_import_device(dev, -2, -1);
+ else
rdev = md_import_device(dev, -1, -1);
if (IS_ERR(rdev))
@@ -4019,8 +4089,6 @@
else
rdev->raid_disk = -1;
- rdev->flags = 0;
-
if (rdev->raid_disk < mddev->raid_disks)
if (info->state & (1<<MD_DISK_SYNC))
set_bit(In_sync, &rdev->flags);