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dm: fix potential for q->make_request_fn NULL pointer

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Move blk_queue_make_request() to dm.c:alloc_dev() so that
q->make_request_fn is never NULL during the lifetime of a DM device
(even one that is created without a DM table).

Otherwise generic_make_request() will crash simply by doing:
  dmsetup create -n test
  mount /dev/dm-N /mnt

While at it, move ->congested_data initialization out of
dm.c:alloc_dev() and into the bio-based specific init method.

Reported-by: Stefan Bader <stefan.bader@canonical.com>
BugLink: https://bugs.launchpad.net/bugs/1860231
Fixes: ff36ab3458 ("dm: remove request-based logic from make_request_fn wrapper")
Depends-on: c12c9a3c38 ("dm: various cleanups to md->queue initialization code")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mike Snitzer 2020-01-27 14:07:23 -05:00
parent dcd195071f
commit 47ace7e012
1 changed files with 7 additions and 2 deletions
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9
drivers/md/dm.c
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@ -1859,6 +1859,7 @@ static void dm_init_normal_md_queue(struct mapped_device *md)
/*
* Initialize aspects of queue that aren't relevant for blk-mq
*/
md->queue->backing_dev_info->congested_data = md;
md->queue->backing_dev_info->congested_fn = dm_any_congested;
}
@ -1949,7 +1950,12 @@ static struct mapped_device *alloc_dev(int minor)
if (!md->queue)
goto bad;
md->queue->queuedata = md;
md->queue->backing_dev_info->congested_data = md;
/*
* default to bio-based required ->make_request_fn until DM
* table is loaded and md->type established. If request-based
* table is loaded: blk-mq will override accordingly.
*/
blk_queue_make_request(md->queue, dm_make_request);
md->disk = alloc_disk_node(1, md->numa_node_id);
if (!md->disk)
@ -2264,7 +2270,6 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
case DM_TYPE_DAX_BIO_BASED:
case DM_TYPE_NVME_BIO_BASED:
dm_init_normal_md_queue(md);
blk_queue_make_request(md->queue, dm_make_request);
break;
case DM_TYPE_NONE:
WARN_ON_ONCE(true);