Akinobu Mita [Sun, 26 Feb 2023 12:42:54 +0000 (21:42 +0900)]
nvme-tcp: don't access released socket during error recovery
While the error recovery work is temporarily failing reconnect attempts,
running the 'nvme list' command causes a kernel NULL pointer dereference
by calling getsockname() with a released socket.
During error recovery work, the nvme tcp socket is released and a new one
created, so it is not safe to access the socket without proper check.
Signed-off-by: Akinobu Mita <[email protected]> Fixes: 02c57a82c008 ("nvme-tcp: print actual source IP address through sysfs "address" attr") Reviewed-by: Martin Belanger <[email protected]> Reviewed-by: Hannes Reinecke <[email protected]> Signed-off-by: Christoph Hellwig <[email protected]>
Dan Carpenter [Thu, 16 Feb 2023 12:14:49 +0000 (15:14 +0300)]
nvme-auth: fix an error code in nvme_auth_process_dhchap_challenge()
This function was transitioned from returning NVMe status codes to
returning traditional kernel error codes. However, this particular
return now accidentally returns positive error codes like ENOMEM instead
of negative -ENOMEM.
Fixes: b0ef1b11d390 ("nvme-auth: don't use NVMe status codes") Signed-off-by: Dan Carpenter <[email protected]> Signed-off-by: Christoph Hellwig <[email protected]>
nvme: bring back auto-removal of deleted namespaces during sequential scan
Bring back the check of the Identify Namespace return value for the
legacy NVMe 1.0-style sequential scanning. While NVMe 1.0 does not
support namespace management, there are "modern" cloud solutions like
Google Cloud Platform that claim the obsolete 1.0 compliance for no
good reason while supporting proprietary sideband namespace management.
which is due to bio->bi_bdev being NULL. This can happen if we have two
tasks doing polled IO, and task B ends up completing IO from task A if
they are sharing a poll queue. If task B completes the IO and puts the
bio into our cache, then it can allocate that bio again before task A
is done polling for it. As that would necessitate a preempt between the
two tasks, it's enough to just be a bit more careful in checking for
whether or not bio->bi_bdev is NULL.
Jens Axboe [Fri, 24 Feb 2023 16:59:44 +0000 (09:59 -0700)]
block: clear bio->bi_bdev when putting a bio back in the cache
This isn't strictly needed in terms of correctness, but it does allow
polling to know if the bio has been put already by a different task
and hence avoid polling something that we don't need to.
Zhong Jinghua [Tue, 21 Feb 2023 09:50:27 +0000 (17:50 +0800)]
loop: loop_set_status_from_info() check before assignment
In loop_set_status_from_info(), lo->lo_offset and lo->lo_sizelimit should
be checked before reassignment, because if an overflow error occurs, the
original correct value will be changed to the wrong value, and it will not
be changed back.
More, the original patch did not solve the problem, the value was set and
ioctl returned an error, but the subsequent io used the value in the loop
driver, which still caused an alarm:
Group some variables based on their sizes to reduce hole and avoid padding.
On x86_64, this shrinks the size of 'struct blk_mq_tag_set'
from 304 to 296 bytes.
Yu Kuai [Fri, 17 Feb 2023 02:22:00 +0000 (10:22 +0800)]
block: fix scan partition for exclusively open device again
As explained in commit 36369f46e917 ("block: Do not reread partition table
on exclusively open device"), reread partition on the device that is
exclusively opened by someone else is problematic.
This patch will make sure partition scan will only be proceed if current
thread open the device exclusively, or the device is not opened
exclusively, and in the later case, other scanners and exclusive openers
will be blocked temporarily until partition scan is done.
This patch can't fix the problem in a corner case that device can be
opened exclusively after the checking and before blkdev_get_by_dev().
We'll use a new solution to fix the problem in the next patch, and
the new solution doesn't need to change apis.
Luca Boccassi [Fri, 10 Feb 2023 01:06:12 +0000 (01:06 +0000)]
sed-opal: add support flag for SUM in status ioctl
Not every OPAL drive supports SUM (Single User Mode), so report this
information to userspace via the get-status ioctl so that we can adjust
the formatting options accordingly.
Tested on a kingston drive (which supports it) and a samsung one
(which does not).
Use radix_tree_maybe_preload() which does preload only if
gfpflags_allow_blocking() is true but also takes the lock. Therefore,
unconditionally calling radix_tree_preload_end() should not create any
issues and the message disappears.
block: bio-integrity: Copy flags when bio_integrity_payload is cloned
Make sure to copy the flags when a bio_integrity_payload is cloned.
Otherwise per-I/O properties such as IP checksum flag will not be
passed down to the HBA driver. Since the integrity buffer is owned by
the original bio, the BIP_BLOCK_INTEGRITY flag needs to be masked off
to avoid a double free in the completion path.
Jinke Han [Thu, 16 Feb 2023 03:22:50 +0000 (11:22 +0800)]
block: Fix io statistics for cgroup in throttle path
In the current code, io statistics are missing for cgroup when bio
was throttled by blk-throttle. Fix it by moving the unreaching code
to submit_bio_noacct_nocheck.
Jens Axboe [Wed, 15 Feb 2023 23:43:47 +0000 (16:43 -0700)]
brd: mark as nowait compatible
By default, non-mq drivers do not support nowait. This causes io_uring
to use a slower path as the driver cannot be trust not to block. brd
can safely set the nowait flag, as worst case all it does is a NOIO
allocation.
For io_uring, this makes a substantial difference. Before:
Jens Axboe [Thu, 16 Feb 2023 15:01:08 +0000 (08:01 -0700)]
brd: check for REQ_NOWAIT and set correct page allocation mask
If REQ_NOWAIT is set, then do a non-blocking allocation if the operation
is a write and we need to insert a new page. Currently REQ_NOWAIT cannot
be set as the queue isn't marked as supporting nowait, this change is in
preparation for allowing that.
radix_tree_preload() warns on attempting to call it with an allocation
mask that doesn't allow blocking. While that warning could arguably
be removed, we need to handle radix insertion failures anyway as they
are more likely if we cannot block to get memory.
Remove legacy BUG_ON()'s and turn them into proper errors instead, one
for the allocation failure and one for finding a page that doesn't
match the correct index.
Ming Lei [Thu, 9 Feb 2023 12:55:27 +0000 (20:55 +0800)]
block: sync mixed merged request's failfast with 1st bio's
We support mixed merge for requests/bios with different fastfail
settings. When request fails, each time we only handle the portion
with same failfast setting, then bios with failfast can be failed
immediately, and bios without failfast can be retried.
The idea is pretty good, but the current implementation has several
defects:
1) initially RA bio doesn't set failfast, however bio merge code
doesn't consider this point, and just check its failfast setting for
deciding if mixed merge is required. Fix this issue by adding helper
of bio_failfast().
2) when merging bio to request front, if this request is mixed
merged, we have to sync request's faifast setting with 1st bio's
failfast. Fix it by calling blk_update_mixed_merge().
3) when merging bio to request back, if this request is mixed
merged, we have to mark the bio as failfast, because blk_update_request
simply updates request failfast with 1st bio's failfast. Fix
it by calling blk_update_mixed_merge().
Fixes one normal EXT4 READ IO failure issue, because it is observed
that the normal READ IO is merged with RA IO, and the mixed merged
request has different failfast setting with 1st bio's, so finally
the normal READ IO doesn't get retried.
Keith Busch [Fri, 10 Feb 2023 18:03:46 +0000 (10:03 -0800)]
nvme-pci: fix freeing single sgl
There may only be a single DMA mapped entry from multiple physical
segments, which means we don't allocate a separte SGL list. Check the
number of allocations prior to know if we need to free something.
Freeing a single list allocation is the same for both PRP and SGL
usages, so we don't need to check the use_sgl flag anymore.
Liu Xiaodong [Fri, 10 Feb 2023 14:13:56 +0000 (09:13 -0500)]
block: ublk: check IO buffer based on flag need_get_data
Currently, uring_cmd with UBLK_IO_FETCH_REQ or
UBLK_IO_COMMIT_AND_FETCH_REQ is always checked whether
userspace server has provided IO buffer even flag
UBLK_F_NEED_GET_DATA is configured.
This is a excessive check. If UBLK_F_NEED_GET_DATA is
configured, FETCH_RQ doesn't need to provide IO buffer;
COMMIT_AND_FETCH_REQ also doesn't need to do that if
the IO type is not READ.
Check ub_cmd->addr together with ublk_need_get_data()
and IO type in ublk_ch_uring_cmd().
With this fix, userspace server doesn't need to preserve
buffers for every ublk_io when flag UBLK_F_NEED_GET_DATA
is configured, in order to save memory.
Qiheng Lin [Fri, 10 Feb 2023 00:02:53 +0000 (01:02 +0100)]
s390/dasd: Fix potential memleak in dasd_eckd_init()
`dasd_reserve_req` is allocated before `dasd_vol_info_req`, and it
also needs to be freed before the error returns, just like the other
cases in this function.
Xiao Ni [Thu, 9 Feb 2023 03:19:30 +0000 (11:19 +0800)]
block: Merge bio before checking ->cached_rq
It checks if plug->cached_rq is empty before merging bio. But the merge action
doesn't have relationship with plug->cached_rq, it trys to merge bio with
requests within plug->mq_list. Now it checks if ->cached_rq is empty before
merging bio. If it's empty, it will miss the merge chances. So move the merge
function before checking ->cached_rq.
blk-cgroup: delay calling blkcg_exit_disk until disk_release
While del_gendisk ensures there is no outstanding I/O on the queue,
it can't prevent block layer users from building new I/O.
This leads to a NULL ->root_blkg reference in bio_associate_blkg when
allocating a new bio on a shut down file system. Delay freeing the
blk-cgroup subsystems from del_gendisk until disk_release to make
sure the blkg and throttle information is still avaÑ–lable for bio
submitters, even if those bios will immediately fail.
This now can cause a case where disk_release is called on a disk
that hasn't been added. That's mostly harmless, except for a case
in blk_throttl_exit that now needs to check for a NULL ->td pointer.
Xiao Ni [Fri, 3 Feb 2023 05:13:44 +0000 (13:13 +0800)]
md: account io_acct_set usage with active_io
io_acct_set was enabled for raid0/raid5 io accounting. bios that contain
md_io_acct are allocated in the i/o path. There isn't a good method to
monitor if these bios are all finished and freed. In the takeover process,
io_acct_set (which is used for bios with md_io_acct) need to be freed.
However, if some bios finish after io_acct_set is freed, it may trigger
the following panic:
Fix this by increasing and decreasing active_io for each bio with
md_io_acct so that mddev_suspend() will wait until all bios from
io_acct_set finish before freeing io_acct_set.
Ming Lei [Tue, 7 Feb 2023 15:07:00 +0000 (23:07 +0800)]
block: ublk: improve handling device deletion
Inside ublk_ctrl_del_dev(), when the device is removed, we wait
until the device number is freed with holding global lock of
ublk_ctl_mutex, this way isn't friendly from user viewpoint:
1) if device is in-use, the current delete command hangs in
ublk_ctrl_del_dev(), and user can't break from the handling
because wait_event() is used
2) global lock is held, so any new device can't be added and
other old devices can't be removed.
Improve the deleting handling by the following way, suggested by
Nadav:
1) wait without holding the global lock
2) replace wait_event() with wait_event_interruptible()
Yu Kuai [Thu, 2 Feb 2023 13:49:13 +0000 (21:49 +0800)]
block, bfq: cleanup 'bfqg->online'
After commit dfd6200a0954 ("blk-cgroup: support to track if policy is
online"), there is no need to do this again in bfq.
However, 'pd->online' is not protected by 'bfqd->lock', in order to make
sure bfq won't see that 'pd->online' is still set after bfq_pd_offline(),
clear it before bfq_pd_offline() is called. This is fine because other
polices doesn't use 'pd->online' and bfq_pd_offline() will move active
bfqq to root cgroup anyway.
Jens Axboe [Tue, 7 Feb 2023 14:22:58 +0000 (07:22 -0700)]
Merge tag 'nvme-6.3-2023-02-07' of git://git.infradead.org/nvme into for-6.3/block
Pull NVMe updates from Christoph:
"nvme updates for Linux 6.3
- small improvements to the logging functionality (Amit Engel)
- authentication cleanups (Hannes Reinecke)
- cleanup and optimize the DMA mapping cod in the PCIe driver
(Keith Busch)
- work around the command effects for Format NVM (Keith Busch)
- misc cleanups (Keith Busch, Christoph Hellwig)"
* tag 'nvme-6.3-2023-02-07' of git://git.infradead.org/nvme:
nvme: mask CSE effects for security receive
nvme: always initialize known command effects
nvmet: for nvme admin set_features cmd, call nvmet_check_data_len_lte()
nvme-tcp: add additional info for nvme_tcp_timeout log
nvme: add nvme_opcode_str function for all nvme cmd types
nvme: remove nvme_execute_passthru_rq
nvme-pci: place descriptor addresses in iod
nvme-pci: use mapped entries for sgl decision
nvme-pci: remove SGL segment descriptors
nvme-auth: don't use NVMe status codes
nvme-fabrics: clarify AUTHREQ result handling
Ziyang Zhang [Tue, 7 Feb 2023 07:08:39 +0000 (15:08 +0800)]
ublk: pass NULL to blk_mq_alloc_disk() as queuedata
queuedata is not referenced in ublk_drv and we can use driver_data
instead. Pass NULL to blk_mq_alloc_disk() as queuedata while allocating
ublk's gendisk.
trace/blktrace: fix memory leak with using debugfs_lookup()
When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time. To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.
Kemeng Shi [Wed, 18 Jan 2023 09:37:26 +0000 (17:37 +0800)]
blk-mq: correct stale comment of .get_budget
Commit 88022d7201e96 ("blk-mq: don't handle failure in .get_budget")
remove BLK_STS_RESOURCE return value and we only check if we can get
the budget from .get_budget() now.
Correct stale comment that ".get_budget() returns BLK_STS_NO_RESOURCE"
to ".get_budget() fails to get the budget".
Fixes: 88022d7201e9 ("blk-mq: don't handle failure in .get_budget") Signed-off-by: Kemeng Shi <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
Kemeng Shi [Wed, 18 Jan 2023 09:37:24 +0000 (17:37 +0800)]
blk-mq: remove set of bd->last when get driver tag for next request fails
Commit 113285b473824 ("blk-mq: ensure that bd->last is always set
correctly") will set last if we failed to get driver tag for next
request to avoid flush miss as we break the list walk and will not
send the last request in the list which will be sent with last set
normally.
This code seems stale now becase the flush introduced is always
redundant as:
For case tag is really out, we will send a extra flush if we find
list is not empty after list walk.
For case some tag is freed before retry in blk_mq_prep_dispatch_rq for
next, then we can get a tag for next request in retry and flush notified
already is not necessary.
Kemeng Shi [Wed, 18 Jan 2023 09:37:23 +0000 (17:37 +0800)]
blk-mq: remove unnecessary error count and check in blk_mq_dispatch_rq_list
blk_mq_dispatch_rq_list will notify if hctx is busy in return bool. It will
return true if we are not busy and can handle more and return false on the
opposite. Inside blk_mq_dispatch_rq_list, errors is only used if list is
empty and we will return true if list is empty and (errors + queued) != 0.
There are three types of status returned from request:
-busy error BLK_STS*_RESOURCE: the failed request will be added back
to list and list will not be empty.
-BLK_STS_OK: We count queued for BLK_STS_OK
-rest error: We count errors for rest error
If list is empty, there is no request gets busy error then (errors +
queued) will be total requests in the list which is checked not empty at
beginning of blk_mq_dispatch_rq_list. So (errors + queued) != 0 is always
met if list is empty. Then the (errors + queued) != 0 check and errors
number count is not needed.
Kemeng Shi [Wed, 18 Jan 2023 09:37:22 +0000 (17:37 +0800)]
blk-mq: simplify flush check in blk_mq_dispatch_rq_list
1. Remove check of needs_resource and ret == BLK_STS_DEV_RESOURCE.
For busy error BLK_STS*_RESOURCE, request will always be added
back to list, so need_resource will not be true and ret will
not be == BLK_STS_DEV_RESOURCE if list is empty. We could remove
these dead check.
2. Check ret of last request instead of errors
If list is empty, we only need to explicitly commit_rqs
if error happens at last request which is stored in ret. So check
ret of last request instead of errors to remove unnecessary
commit_rqs triggered by errors returned from previous request.
Kemeng Shi [Wed, 18 Jan 2023 09:37:21 +0000 (17:37 +0800)]
blk-mq: use blk_mq_commit_rqs helper in blk_mq_try_issue_list_directly
Call blk_mq_commit_rqs instead of access ->commit_rqs directly. As you
can see in comment of blk_mq_commit_rqs, we only need explicitly call
this in two cases:
-did not queue everything initially scheduled to queue
-the last attempt to queue a request failed
Both cases can be checked with ret of last request which breaks list
walk. Then we can remove unnecessary error count and unnecessary
commit triggered by error besides cases described above.
Kemeng Shi [Wed, 18 Jan 2023 09:37:20 +0000 (17:37 +0800)]
blk-mq: remove unncessary error count and commit in blk_mq_plug_issue_direct
We need only to explicitly commit in two error cases:
-did not queue everything initially scheduled to queue
-the last attempt to queue a request failed
(see comment of blk_mq_commit_rqs for more details).
Both cases can be checked with ret of last request which breaks list walk.
Remove unnecessary error count and unnecessary commit triggered by error
which is not covered by cases described above.
Kemeng Shi [Wed, 18 Jan 2023 09:37:19 +0000 (17:37 +0800)]
blk-mq: make blk_mq_commit_rqs a general function for all commits
1. move blk_mq_commit_rqs forward before functions need commits.
2. add queued check and only commits request if any request was queued
in blk_mq_commit_rqs to keep commit behavior consistent and remove
unnecessary commit.
3. split the queued clearing from blk_mq_plug_commit_rqs as it is
not wanted general.
4. sync current caller of blk_mq_commit_rqs with new general
blk_mq_commit_rqs.
5. document rule for unusual cases which need explicit commit_rqs.
Kemeng Shi [Wed, 18 Jan 2023 09:37:18 +0000 (17:37 +0800)]
blk-mq: remove unncessary from_schedule parameter in blk_mq_plug_issue_direct
Function blk_mq_plug_issue_direct tries to issue batch requests in plug
list to driver directly. We will only issue plug request to driver if we
are not from scheduler, so from_scheduler parameter of
blk_mq_plug_issue_direct is always false.
Remove unncessary from_scheduler of blk_mq_plug_issue_direct.
Kemeng Shi [Wed, 18 Jan 2023 09:37:17 +0000 (17:37 +0800)]
blk-mq: remove unnecessary list_empty check in blk_mq_try_issue_list_directly
We only break the list walk if we get 'BLK_STS_*RESOURCE'. We also
count errors for 'BLK_STS_*RESOURCE' error. If list is not empty,
errors will always be non-zero. So we can remove unnecessary list_empty
check. This will remove redundant list_empty check for case that
error happened at sending last request in list.
Kemeng Shi [Wed, 18 Jan 2023 09:37:16 +0000 (17:37 +0800)]
blk-mq: Fix potential io hung for shared sbitmap per tagset
Commit f906a6a0f4268 ("blk-mq: improve tag waiting setup for non-shared
tags") mark restart for unshared tags for improvement. At that time,
tags is only shared betweens queues and we can check if tags is shared
by test BLK_MQ_F_TAG_SHARED.
Afterwards, commit 32bc15afed04b ("blk-mq: Facilitate a shared sbitmap per
tagset") enabled tags share betweens hctxs inside a queue. We only
mark restart for shared hctxs inside a queue and may cause io hung if
there is no tag currently allocated by hctxs going to be marked restart.
Wait on sbitmap_queue instead of mark restart for shared hctxs case to
fix this.
Fixes: 32bc15afed04 ("blk-mq: Facilitate a shared sbitmap per tagset") Signed-off-by: Kemeng Shi <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
Kemeng Shi [Wed, 18 Jan 2023 09:37:15 +0000 (17:37 +0800)]
blk-mq: wait on correct sbitmap_queue in blk_mq_mark_tag_wait
For shared queues case, we will only wait on bitmap_tags if we fail to get
driver tag. However, rq could be from breserved_tags, then two problems
will occur:
1. io hung if no tag is currently allocated from bitmap_tags.
2. unnecessary wakeup when tag is freed to bitmap_tags while no tag is
freed to breserved_tags.
Wait on the bitmap which rq from to fix this.
Fixes: f906a6a0f426 ("blk-mq: improve tag waiting setup for non-shared tags") Reviewed-by: Christoph Hellwig <[email protected]> Signed-off-by: Kemeng Shi <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
Kemeng Shi [Wed, 18 Jan 2023 09:37:14 +0000 (17:37 +0800)]
blk-mq: remove stale comment for blk_mq_sched_mark_restart_hctx
Commit 97889f9ac24f8 ("blk-mq: remove synchronize_rcu() from
blk_mq_del_queue_tag_set()") remove handle of TAG_SHARED in restart,
then shared_hctx_restart counted for how many hardware queues are marked
for restart is removed too.
Remove the stale comment that we still count hardware queues need restart.
Fixes: 97889f9ac24f ("blk-mq: remove synchronize_rcu() from blk_mq_del_queue_tag_set()") Reviewed-by: Christoph Hellwig <[email protected]> Signed-off-by: Kemeng Shi <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
Kemeng Shi [Wed, 18 Jan 2023 09:37:13 +0000 (17:37 +0800)]
blk-mq: avoid sleep in blk_mq_alloc_request_hctx
Commit 1f5bd336b9150 ("blk-mq: add blk_mq_alloc_request_hctx") add
blk_mq_alloc_request_hctx to send commands to a specific queue. If
BLK_MQ_REQ_NOWAIT is not set in tag allocation, we may change to different
hctx after sleep and get tag from unexpected hctx. So BLK_MQ_REQ_NOWAIT
must be set in flags for blk_mq_alloc_request_hctx.
After commit 600c3b0cea784 ("blk-mq: open code __blk_mq_alloc_request in
blk_mq_alloc_request_hctx"), blk_mq_alloc_request_hctx return -EINVAL
if both BLK_MQ_REQ_NOWAIT and BLK_MQ_REQ_RESERVED are not set instead of
if BLK_MQ_REQ_NOWAIT is not set. So if BLK_MQ_REQ_NOWAIT is not set and
BLK_MQ_REQ_RESERVED is set, blk_mq_alloc_request_hctx could alloc tag
from unexpected hctx. I guess what we need here is that return -EINVAL
if either BLK_MQ_REQ_NOWAIT or BLK_MQ_REQ_RESERVED is not set.
Currently both BLK_MQ_REQ_NOWAIT and BLK_MQ_REQ_RESERVED will be set if
specific hctx is needed in nvme_auth_submit, nvmf_connect_io_queue
and nvmf_connect_admin_queue. Fix the potential BLK_MQ_REQ_NOWAIT missed
case in future.
Fixes: 600c3b0cea78 ("blk-mq: open code __blk_mq_alloc_request in blk_mq_alloc_request_hctx") Reviewed-by: Christoph Hellwig <[email protected]> Signed-off-by: Kemeng Shi <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
block: stub out and deprecated the capability attribute on the gendisk
The capability attribute was added in 2017 to expose the kernel internal
GENHD_FL_MEDIA_CHANGE_NOTIFY to userspace without ever adding a value to
an UAPI header, and without ever setting it in any driver until it was
finally removed in Linux 5.7.
Deprecate the file and always return 0 instead of exposing the other
internal and frequently renumbered other gendisk flags.
A smaller wrapper around bvec_set_page that takes a folio instead.
There are only two potential users for this in the tree, but the number
will grow in the future.
blk-cgroup: move the cgroup information to struct gendisk
cgroup information only makes sense on a live gendisk that allows
file system I/O (which includes the raw block device). So move over
the cgroup related members.
blk-wbt: open code wbt_queue_depth_changed in wbt_init
wbt_queue_depth_changed just updates a field and calls another function.
Open code it in wbt_init, so that the local queue variable can be used
instead of the one stored in the rq_qos. This will allow delaying that
rq_qos->queue assignment in a subsequent patch.
Currently each blkcg_gq holds a request_queue reference, which is what
is used in the policies. But a lot of these interfaces will move over to
use a gendisk, so store a disk in struct blkcg_gq and hold a reference to
it.
projects / linux.git / log