From: Jonathan Brassow <jbrassow@xxxxxxxxxx>
Allow the metadata to be on a separate device from the
data.
This doesn't mean the data and metadata will by on separate
physical devices - it simply gives device-mapper and userspace
tools more flexibility.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
drivers/md/bitmap.c | 6 +++++-
drivers/md/md.c | 10 ++++++----
drivers/md/md.h | 6 ++++++
3 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 1977765..6cf5871 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -264,14 +264,18 @@ static mdk_rdev_t *next_active_rdev(mdk_rdev_t *rdev, mddev_t *mddev)
static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
{
mdk_rdev_t *rdev = NULL;
+ struct block_device *bdev;
mddev_t *mddev = bitmap->mddev;
while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {
int size = PAGE_SIZE;
loff_t offset = mddev->bitmap_info.offset;
+
+ bdev = (rdev->meta_bdev) ? rdev->meta_bdev : rdev->bdev;
+
if (page->index == bitmap->file_pages-1)
size = roundup(bitmap->last_page_size,
- bdev_logical_block_size(rdev->bdev));
+ bdev_logical_block_size(bdev));
/* Just make sure we aren't corrupting data or
* metadata
*/
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 0bc10cc..b98a85f 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -765,7 +765,7 @@ void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
*/
struct bio *bio = bio_alloc_mddev(GFP_NOIO, 1, mddev);
- bio->bi_bdev = rdev->bdev;
+ bio->bi_bdev = rdev->meta_bdev ? rdev->meta_bdev : rdev->bdev;
bio->bi_sector = sector;
bio_add_page(bio, page, size, 0);
bio->bi_private = rdev;
@@ -803,7 +803,8 @@ int sync_page_io(mdk_rdev_t *rdev, sector_t sector, int size,
rw |= REQ_SYNC | REQ_UNPLUG;
- bio->bi_bdev = rdev->bdev;
+ bio->bi_bdev = (metadata_op && rdev->meta_bdev) ?
+ rdev->meta_bdev : rdev->bdev;
if (metadata_op)
bio->bi_sector = sector + rdev->sb_start;
else
@@ -4435,7 +4436,9 @@ int md_run(mddev_t *mddev)
* We don't want the data to overlap the metadata,
* Internal Bitmap issues have been handled elsewhere.
*/
- if (rdev->data_offset < rdev->sb_start) {
+ if (rdev->meta_bdev) {
+ /* Nothing to check */;
+ } else if (rdev->data_offset < rdev->sb_start) {
if (mddev->dev_sectors &&
rdev->data_offset + mddev->dev_sectors
> rdev->sb_start) {
@@ -5532,7 +5535,6 @@ static int update_size(mddev_t *mddev, sector_t num_sectors)
* sb_start or, if that is <data_offset, it must fit before the size
* of each device. If num_sectors is zero, we find the largest size
* that fits.
-
*/
if (mddev->sync_thread)
return -EBUSY;
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 7e4f358..eec517c 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -60,6 +60,12 @@ struct mdk_rdev_s
mddev_t *mddev; /* RAID array if running */
int last_events; /* IO event timestamp */
+ /*
+ * If meta_bdev is non-NULL, it means that a separate device is
+ * being used to store the metadata (superblock/bitmap) which
+ * would otherwise be contained on the same device as the data (bdev).
+ */
+ struct block_device *meta_bdev;
struct block_device *bdev; /* block device handle */
struct page *sb_page;
--
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