[PATCH 65/78] dm: remove the block_device reference in struct mapped_device

Christoph Hellwig
2020-11-16T15:13:15Z

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>
---
drivers/md/dm-core.h | 2 --
drivers/md/dm.c | 22 +++++++++++-----------
2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index d522093cb39dda..b1b400ed76fe90 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -107,8 +107,6 @@ 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 6d7eb72d41f9ea..c789ffea2badde 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 */
@@ -2384,12 +2375,17 @@ 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(md->frozen_sb);

- md->frozen_sb = freeze_bdev(md->bdev);
+ bdev = bdget_disk(md->disk, 0);
+ if (!bdev)
+ return -ENOMEM;
+ md->frozen_sb = freeze_bdev(bdev);
if (IS_ERR(md->frozen_sb)) {
+ bdput(bdev);
r = PTR_ERR(md->frozen_sb);
md->frozen_sb = NULL;
return r;
@@ -2402,10 +2398,14 @@ 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, md->frozen_sb);
+ bdev = md->frozen_sb->s_bdev;
+ thaw_bdev(bdev, md->frozen_sb);
+ bdput(bdev);
md->frozen_sb = NULL;
clear_bit(DMF_FROZEN, &md->flags);