block: merge struct block_device and struct hd_struct
Instead of having two structures that represent each block device with
different life time rules, merge them into a single one. This also
greatly simplifies the reference counting rules, as we can use the inode
reference count as the main reference count for the new struct
block_device, with the device model reference front ending it for device
model interaction.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: switch disk_part_iter_* to use a struct block_device
Switch the partition iter infrastructure to iterate over block_device
references instead of hd_struct ones mostly used to get at the
block_device.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: pass a block_device to invalidate_partition
Pass the block_device actually needed instead of looking it up using
bdget_disk.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass the block_device actually needed instead of the hd_struct.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: remove the partno field from struct hd_struct
Just use the bd_partno field in struct block_device everywhere.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: allocate struct hd_struct as part of struct bdev_inode
Allocate hd_struct together with struct block_device to pre-load
the lifetime rule changes in preparation of merging the two structures.
Note that part0 was previously embedded into struct gendisk, but is
a separate allocation now, and already points to the block_device instead
of the hd_struct. The lifetime of struct gendisk is still controlled by
the struct device embedded in the part0 hd_struct.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: move the policy field to struct block_device
Move the policy field to struct block_device and rename it to the
more descriptive bd_read_only. Also turn the field into a bool as it
is used as such.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the make_it_fail flag to struct block_device an turn it into a bool
in preparation of killing struct hd_struct.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the holder_dir field to struct block_device in preparation for
kill struct hd_struct.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: move the partition_meta_info to struct block_device
Move the partition_meta_info to struct block_device in preparation for
killing struct hd_struct.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: move the start_sect field to struct block_device
Move the start_sect field to struct block_device in preparation
of killing struct hd_struct.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: move disk stat accounting to struct block_device
Move the dkstats and stamp field to struct block_device in preparation
of killing struct hd_struct.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: remove the nr_sects field in struct hd_struct
Now that the hd_struct always has a block device attached to it, there is
no need for having two size field that just get out of sync.
Additionally the field in hd_struct did not use proper serialization,
possibly allowing for torn writes. By only using the block_device field
this problem also gets fixed.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Coly Li <colyli@suse.de> [bcache] Acked-by: Chao Yu <yuchao0@huawei.com> [f2fs] Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: initialize struct block_device in bdev_alloc
Don't play tricks with slab constructors as bdev structures tends to not
get reused very much, and this makes the code a lot less error prone.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that struct hd_struct has a block_device pointer use that to
find the disk.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that each hd_struct has a reference to the corresponding
block_device, there is no need for the bd_contains pointer. Add
a bdev_whole() helper to look up the whole device block_device
struture instead.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
To simplify block device lookup and a few other upcoming areas, make sure
that we always have a struct block_device available for each disk and
each partition, and only find existing block devices in bdget. The only
downside of this is that each device and partition uses a little more
memory. The upside will be that a lot of code can be simplified.
With that all we need to look up the block device is to lookup the inode
and do a few sanity checks on the gendisk, instead of the separate lookup
for the gendisk. For blk-cgroup which wants to access a gendisk without
opening it, a new blkdev_{get,put}_no_open low-level interface is added
to replace the previous get_gendisk use.
Note that the change to look up block device directly instead of the two
step lookup using struct gendisk causes a subtile change in behavior:
accessing a non-existing partition on an existing block device can now
cause a call to request_module. That call is harmless, and in practice
no recent system will access these nodes as they aren't created by udev
and static /dev/ setups are unusual.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Switch the block device lookup interfaces to directly work with a dev_t
so that struct block_device references are only acquired by the
blkdev_get variants (and the blk-cgroup special case). This means that
we now don't need an extra reference in the inode and can generally
simplify handling of struct block_device to keep the lookups contained
in the core block layer code.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Coly Li <colyli@suse.de> [bcache] Signed-off-by: Jens Axboe <axboe@kernel.dk>
Just call devcgroup_check_permission to avoid various superflous checks
and a double conversion of the access flags.
Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: move bdput() to the callers of __blkdev_get
This will allow for a more symmetric calling convention going forward.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move more code that is only run on the outer open but not the open of
the underlying whole device when opening a partition into blkdev_get,
which leads to a much easier to follow structure.
This allows to simplify the disk and module refcounting so that one
reference is held for each open, similar to what we do with normal
file operations.
Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Split each case into a self-contained helper, and move the block
dependent code entirely under the pre-existing #ifdef CONFIG_BLOCK.
This allows to remove the blk_lookup_devt stub in genhd.h.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
All of the current callers already have a reference, but to prepare for
additional users ensure bdgrab returns NULL if the block device is being
freed.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: change the hash used for looking up block devices
Adding the minor to the major creates tons of pointless conflicts. Just
use the dev_t itself, which is 32-bits and thus is guaranteed to fit
into ino_t.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: remove a superflous check in blkpg_do_ioctl
sector_t is now always a u64, so this check is not needed.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
dm: remove the block_device reference in struct mapped_device
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> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
dm: simplify flush_bio initialization in __send_empty_flush
We don't really need the struct block_device to initialize a bio. So
switch from using bio_set_dev to manually setting up bi_disk (bi_partno
will always be zero and has been cleared by bio_init already).
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
set_blocksize is used by file systems to use their preferred buffer cache
block size. Block drivers should not set it.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
mtip32xx: remove the call to fsync_bdev on removal
del_gendisk already calls fsync_bdev for every partition, no need
to do this twice.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
fs: remove get_super_thawed and get_super_exclusive_thawed
Just open code the wait in the only caller of both functions.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
filemap: consistently use ->f_mapping over ->i_mapping
Use file->f_mapping in all remaining places that have a struct file
available to properly handle the case where inode->i_mapping !=
file_inode(file)->i_mapping.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
virtio-blk: remove a spurious call to revalidate_disk_size
revalidate_disk_size just updates the block device size from the disk
size. Thus calling it from virtblk_update_cache_mode doesn't actually
do anything.
Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
nvme: use set_capacity_and_notify in nvme_set_queue_dying
Use the block layer helper to update both the disk and block device
sizes. Contrary to the name no notification is sent in this case,
as a size 0 is special cased.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Updating the block device size from irq context can lead to torn
writes of the 64-bit value, and prevents us from using normal
process context locking primitives to serialize access to the 64-bit
nr_sectors value. Defer the set_capacity to the already existing
workqueue handler, where it can be merged with the update of the
block device size by using set_capacity_and_notify. As an extra
bonus this also adds proper uevent notifications for the resize.
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Use set_capacity_and_notify to update the disk and block device sizes and
send a RESIZE uevent to userspace. Note that blktests relies on uevents
being sent also for updates that did not change the device size, so the
explicit kobject_uevent remains for that case.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Merge nbd_size_set and nbd_size_update into a single function that also
updates the nbd_config fields. This new function takes the device size
in bytes as the first argument, and the blocksize as the second argument,
simplifying the calculations required in most callers.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: remove the update_bdev parameter to set_capacity_revalidate_and_notify
The update_bdev argument is always set to true, so remove it. Also
rename the function to the slighly less verbose set_capacity_and_notify,
as propagating the disk size to the block device isn't really
revalidation.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Petr Vorel <pvorel@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
This avoids the extra call to revalidate_disk_size in sd_rescan and
is otherwise a no-op because the size did not change, or we are in
the probe path.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: remove the call to __invalidate_device in check_disk_size_change
__invalidate_device without the kill_dirty parameter just invalidates
various clean entries in caches, which doesn't really help us with
anything, but can cause all kinds of horrible lock orders due to how
it calls into the file system. The only reason this hasn't been a
major issue is because so many people use partitions, for which no
invalidation was performed anyway.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
z2ram: use separate gendisk for the different modes
Use separate gendisks (which share a tag_set) for the different operating
modes instead of redirecting the gendisk lookup using a probe callback.
This avoids potential problems with aliased block_device instances and
will eventually allow for removing the blk_register_region framework.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
ataflop: use a separate gendisk for each media format
The Atari floppy driver usually autodetects the media when used with the
ormal /dev/fd? devices, which also are the only nodes created by udev.
But it also supports various aliases that force a given media format.
That is currently supported using the blk_register_region framework
which finds the floppy gendisk even for a 'mismatched' dev_t. The
problem with this (besides the code complexity) is that it creates
multiple struct block_device instances for the whole device of a
single gendisk, which can lead to interesting issues in code not
aware of that fact.
To fix this just create a separate gendisk for each of the aliases
if they are accessed.
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
amiflop: use separate gendisks for Amiga vs MS-DOS mode
Use separate gendisks (which share a tag_set) for the native Amgiga vs
the MS-DOS mode instead of redirecting the gendisk lookup using a probe
callback. This avoids potential problems with aliased block_device
instances and will eventually allow for removing the blk_register_region
framework.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
floppy: use a separate gendisk for each media format
The floppy driver usually autodetects the media when used with the
normal /dev/fd? devices, which also are the only nodes created by udev.
But it also supports various aliases that force a given media format.
That is currently supported using the blk_register_region framework
which finds the floppy gendisk even for a 'mismatched' dev_t. The
problem with this (besides the code complexity) is that it creates
multiple struct block_device instances for the whole device of a
single gendisk, which can lead to interesting issues in code not
aware of that fact.
To fix this just create a separate gendisk for each of the aliases
if they are accessed.
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
ide: switch to __register_blkdev for command set probing
ide is the last user of the blk_register_region framework except for the
tracking of allocated gendisk. Switch to __register_blkdev, even if that
doesn't allow us to trivially find out which command set to probe for.
That means we now always request all modules when a user tries to access
an unclaimed ide device node, but except for a few potentially loaded
modules for a fringe use case of a deprecated and soon to be removed
driver that doesn't make a difference.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
md: use __register_blkdev to allocate devices on demand
Use the simpler mechanism attached to major_name to allocate a md device
when a currently unregistered minor is accessed.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Song Liu <song@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
sd: use __register_blkdev to avoid a modprobe for an unregistered dev_t
Switch from using blk_register_region to the probe callback passed to
__register_blkdev to disable the request_module call for an unclaimed
dev_t in the SD majors.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
The swim driver (unlike various other floppy drivers) doesn't have
magic device nodes for certain modes, and already registers a gendisk
for each of the floppies supported by a device. Thus the region
registered is a no-op and can be removed.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: add an optional probe callback to major_names
Add a callback to the major_names array that allows a driver to override
how to probe for dev_t that doesn't currently have a gendisk registered.
This will help separating the lookup of the gendisk by dev_t vs probe
action for a not currently registered dev_t.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: rework requesting modules for unclaimed devices
Instead of reusing the ranges in bdev_map, add a new helper that is
called if no ranges was found. This is a first step to unpeel and
eventually remove the complex ranges structure.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new method to allow for driver-specific processing when setting or
clearing the block device read-only state. This allows to replace the
cumbersome and error-prone override of the whole ioctl implementation.
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
BLKFLSBUF is not supposed to actually send a flush command to the device,
but to tear down buffer cache structures. Remove the mtd_blkdevs
implementation and just use the default semantics instead.
Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Richard Weinberger <richard@nod.at> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Linus Torvalds [Sun, 15 Nov 2020 21:07:36 +0000 (13:07 -0800)]
Merge tag 'drm-fixes-2020-11-16' of git://anongit.freedesktop.org/drm/drm
Pull drm fixes from Dave Airlie:
"Nouveau fixes:
- atomic modesetting regression fix
- ttm pre-nv50 fix
- connector NULL ptr deref fix"
* tag 'drm-fixes-2020-11-16' of git://anongit.freedesktop.org/drm/drm:
drm/nouveau/kms/nv50-: Use atomic encoder callbacks everywhere
drm/nouveau/ttm: avoid using nouveau_drm.ttm.type_vram prior to nv50
drm/nouveau/kms: Fix NULL pointer dereference in nouveau_connector_detect_depth