[PATCH AUTOSEL 5.7 121/274] bcache: remove a duplicate ->make_request_fn assignment

[PATCH AUTOSEL 5.7 121/274] bcache: remove a duplicate ->make_request_fn assignment

[Sasha Levin]

From: Christoph Hellwig <hch@lst.de>

[ Upstream commit a91b2014fc31dc6eaa02ca33aa3b4d1b6e4a0207 ]

The make_request_fn pointer should only be assigned by blk_alloc_queue.
Fix a left over manual initialization.

Fixes: ff27668ce809 ("bcache: pass the make_request methods to blk_queue_make_request")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/bcache/request.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 71a90fbec314..77d1a2697517 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -1372,7 +1372,6 @@ void bch_flash_dev_request_init(struct bcache_device *d)
 {
 	struct gendisk *g = d->disk;
 
-	g->queue->make_request_fn		= flash_dev_make_request;
 	g->queue->backing_dev_info->congested_fn = flash_dev_congested;
 	d->cache_miss				= flash_dev_cache_miss;
 	d->ioctl				= flash_dev_ioctl;
-- 
2.25.1

[PATCH AUTOSEL 5.7 121/274] bcache: remove a duplicate ->make_request_fn assignment

[Sasha Levin]

From: Christoph Hellwig <hch@lst.de>

[ Upstream commit a91b2014fc31dc6eaa02ca33aa3b4d1b6e4a0207 ]

The make_request_fn pointer should only be assigned by blk_alloc_queue.
Fix a left over manual initialization.

Fixes: ff27668ce809 ("bcache: pass the make_request methods to blk_queue_make_request")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/bcache/request.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 71a90fbec314..77d1a2697517 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -1372,7 +1372,6 @@ void bch_flash_dev_request_init(struct bcache_device *d)
 {
 	struct gendisk *g = d->disk;
 
-	g->queue->make_request_fn		= flash_dev_make_request;
 	g->queue->backing_dev_info->congested_fn = flash_dev_congested;
 	d->cache_miss				= flash_dev_cache_miss;
 	d->ioctl				= flash_dev_ioctl;
-- 
2.25.1

[PATCH AUTOSEL 5.7 241/274] bcache: fix refcount underflow in bcache_device_free()

[Sasha Levin]

From: Coly Li <colyli@suse.de>

[ Upstream commit 86da9f736740eba602389908574dfbb0f517baa5 ]

The problematic code piece in bcache_device_free() is,

 785 static void bcache_device_free(struct bcache_device *d)
 786 {
 787     struct gendisk *disk = d->disk;
 [snipped]
 799     if (disk) {
 800             if (disk->flags & GENHD_FL_UP)
 801                     del_gendisk(disk);
 802
 803             if (disk->queue)
 804                     blk_cleanup_queue(disk->queue);
 805
 806             ida_simple_remove(&bcache_device_idx,
 807                               first_minor_to_idx(disk->first_minor));
 808             put_disk(disk);
 809         }
 [snipped]
 816 }

At line 808, put_disk(disk) may encounter kobject refcount of 'disk'
being underflow.

Here is how to reproduce the issue,
- Attche the backing device to a cache device and do random write to
  make the cache being dirty.
- Stop the bcache device while the cache device has dirty data of the
  backing device.
- Only register the backing device back, NOT register cache device.
- The bcache device node /dev/bcache0 won't show up, because backing
  device waits for the cache device shows up for the missing dirty
  data.
- Now echo 1 into /sys/fs/bcache/pendings_cleanup, to stop the pending
  backing device.
- After the pending backing device stopped, use 'dmesg' to check kernel
  message, a use-after-free warning from KASA reported the refcount of
  kobject linked to the 'disk' is underflow.

The dropping refcount at line 808 in the above code piece is added by
add_disk(d->disk) in bch_cached_dev_run(). But in the above condition
the cache device is not registered, bch_cached_dev_run() has no chance
to be called and the refcount is not added. The put_disk() for a non-
added refcount of gendisk kobject triggers a underflow warning.

This patch checks whether GENHD_FL_UP is set in disk->flags, if it is
not set then the bcache device was not added, don't call put_disk()
and the the underflow issue can be avoided.

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/bcache/super.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index d98354fa28e3..4d8bf731b118 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -797,7 +797,9 @@ static void bcache_device_free(struct bcache_device *d)
 		bcache_device_detach(d);
 
 	if (disk) {
-		if (disk->flags & GENHD_FL_UP)
+		bool disk_added = (disk->flags & GENHD_FL_UP) != 0;
+
+		if (disk_added)
 			del_gendisk(disk);
 
 		if (disk->queue)
@@ -805,7 +807,8 @@ static void bcache_device_free(struct bcache_device *d)
 
 		ida_simple_remove(&bcache_device_idx,
 				  first_minor_to_idx(disk->first_minor));
-		put_disk(disk);
+		if (disk_added)
+			put_disk(disk);
 	}
 
 	bioset_exit(&d->bio_split);
-- 
2.25.1