dm: fix potential for q->make_request_fn NULL pointer
commit 47ace7e012b9f7ad71d43ac9063d335ea3d6820b upstream.
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: ff36ab34583a ("dm: remove request-based logic from make_request_fn wrapper")
Depends-on: c12c9a3c3860c ("dm: various cleanups to md->queue initialization code")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
[smb: adjusted for context and dm_init_md_queue() exitsting in older
kernels, and congested_data embedded in backing_dev_info]
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 36e6221..dd15402 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1457,7 +1457,6 @@
* - must do so here (in alloc_dev callchain) before queue is used
*/
md->queue->queuedata = md;
- md->queue->backing_dev_info.congested_data = md;
}
void dm_init_normal_md_queue(struct mapped_device *md)
@@ -1468,6 +1467,7 @@
/*
* 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;
blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
}
@@ -1555,6 +1555,12 @@
goto bad;
dm_init_md_queue(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, numa_node_id);
if (!md->disk)
@@ -1853,7 +1859,6 @@
case DM_TYPE_BIO_BASED:
case DM_TYPE_DAX_BIO_BASED:
dm_init_normal_md_queue(md);
- blk_queue_make_request(md->queue, dm_make_request);
/*
* DM handles splitting bios as needed. Free the bio_split bioset
* since it won't be used (saves 1 process per bio-based DM device).