[PATCH 09/45] dm: remove the block_device reference in struct mapped_device

Christoph Hellwig
2020-11-28T22:09:01Z

Get rid of the long-lasting struct block_device reference in
struct mapped_device. The only remaining user is the freeze code,
where we can trivially look up the block device at freeze time
and release the reference at thaw time.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Mike Snitzer <snitzer@redhat.com>
---
drivers/md/dm-core.h | 2 --
drivers/md/dm.c | 25 ++++++++++++++-----------
2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index aace147effcacb..086d293c2b036c 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -102,8 +102,6 @@ struct mapped_device {
/* kobject and completion */
struct dm_kobject_holder kobj_holder;

- struct block_device *bdev;
-
struct dm_stats stats;

/* for blk-mq request-based DM support */
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index ab0a8335f098d9..48051db006f30c 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1744,11 +1744,6 @@ static void cleanup_mapped_device(struct mapped_device *md)

cleanup_srcu_struct(&md->io_barrier);

- if (md->bdev) {
- bdput(md->bdev);
- md->bdev = NULL;
- }
-
mutex_destroy(&md->suspend_lock);
mutex_destroy(&md->type_lock);
mutex_destroy(&md->table_devices_lock);
@@ -1840,10 +1835,6 @@ static struct mapped_device *alloc_dev(int minor)
if (!md->wq)
goto bad;

- md->bdev = bdget_disk(md->disk, 0);
- if (!md->bdev)
- goto bad;
-
dm_stats_init(&md->stats);

/* Populate the mapping, nobody knows we exist yet */
@@ -2384,11 +2375,16 @@ struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
*/
static int lock_fs(struct mapped_device *md)
{
+ struct block_device *bdev;
int r;

WARN_ON(test_bit(DMF_FROZEN, &md->flags));

- r = freeze_bdev(md->bdev);
+ bdev = bdget_disk(md->disk, 0);
+ if (!bdev)
+ return -ENOMEM;
+ r = freeze_bdev(bdev);
+ bdput(bdev);
if (!r)
set_bit(DMF_FROZEN, &md->flags);
return r;
@@ -2396,9 +2392,16 @@ static int lock_fs(struct mapped_device *md)

static void unlock_fs(struct mapped_device *md)
{
+ struct block_device *bdev;
+
if (!test_bit(DMF_FROZEN, &md->flags))
return;
- thaw_bdev(md->bdev);
+
+ bdev = bdget_disk(md->disk, 0);
+ if (!bdev)
+ return;
+ thaw_bdev(bdev);
+ bdput(bdev);
clear_bit(DMF_FROZEN, &md->flags);
}

--
2.29.2