[PATCH AUTOSEL 5.4 026/330] dm table: do not allow request-based DM to stack on partitions

Sasha Levin
2020-09-18T03:14:28Z

From: Mike Snitzer <snitzer@redhat.com>

[ Upstream commit 6ba01df72b4b63a26b4977790f58d8f775d2992c ]

Partitioned request-based devices cannot be used as underlying devices
for request-based DM because no partition offsets are added to each
incoming request. As such, until now, stacking on partitioned devices
would _always_ result in data corruption (e.g. wiping the partition
table, writing to other partitions, etc). Fix this by disallowing
request-based stacking on partitions.

While at it, since all .request_fn support has been removed from block
core, remove legacy dm-table code that differentiated between blk-mq and
.request_fn request-based.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/dm-table.c | 27 ++++++++-------------------
1 file changed, 8 insertions(+), 19 deletions(-)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 52e049554f5cd..2ae0c19137667 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -918,21 +918,15 @@ bool dm_table_supports_dax(struct dm_table *t,

static bool dm_table_does_not_support_partial_completion(struct dm_table *t);

-struct verify_rq_based_data {
- unsigned sq_count;
- unsigned mq_count;
-};
-
-static int device_is_rq_based(struct dm_target *ti, struct dm_dev *dev,
- sector_t start, sector_t len, void *data)
+static int device_is_rq_stackable(struct dm_target *ti, struct dm_dev *dev,
+ sector_t start, sector_t len, void *data)
{
- struct request_queue *q = bdev_get_queue(dev->bdev);
- struct verify_rq_based_data *v = data;
+ struct block_device *bdev = dev->bdev;
+ struct request_queue *q = bdev_get_queue(bdev);

- if (queue_is_mq(q))
- v->mq_count++;
- else
- v->sq_count++;
+ /* request-based cannot stack on partitions! */
+ if (bdev != bdev->bd_contains)
+ return false;

return queue_is_mq(q);
}
@@ -941,7 +935,6 @@ static int dm_table_determine_type(struct dm_table *t)
{
unsigned i;
unsigned bio_based = 0, request_based = 0, hybrid = 0;
- struct verify_rq_based_data v = {.sq_count = 0, .mq_count = 0};
struct dm_target *tgt;
struct list_head *devices = dm_table_get_devices(t);
enum dm_queue_mode live_md_type = dm_get_md_type(t->md);
@@ -1045,14 +1038,10 @@ verify_rq_based:

/* Non-request-stackable devices can't be used for request-based dm */
if (!tgt->type->iterate_devices ||
- !tgt->type->iterate_devices(tgt, device_is_rq_based, &v)) {
+ !tgt->type->iterate_devices(tgt, device_is_rq_stackable, NULL)) {
DMERR("table load rejected: including non-request-stackable devices");
return -EINVAL;
}
- if (v.sq_count > 0) {
- DMERR("table load rejected: not all devices are blk-mq request-stackable");
- return -EINVAL;
- }

return 0;
}
--
2.25.1