linux-stable.git/drivers/md/dm.c, branch linux-5.8.y

dm: fix bio splitting and its bio completion order for regular IO

2020-10-01T15:36:35+00:00

commit ee1dfad5325ff1cfb2239e564cd411b3bfe8667a upstream.

dm_queue_split() is removed because __split_and_process_bio() _must_
handle splitting bios to ensure proper bio submission and completion
ordering as a bio is split.

Otherwise, multiple recursive calls to ->submit_bio will cause multiple
split bios to be allocated from the same ->bio_split mempool at the same
time. This would result in deadlock in low memory conditions because no
progress could be made (only one bio is available in ->bio_split
mempool).

This fix has been verified to still fix the loss of performance, due
to excess splitting, that commit 120c9257f5f1 provided.

Fixes: 120c9257f5f1 ("Revert "dm: always call blk_queue_split() in dm_process_bio()"")
Cc: stable@vger.kernel.org # 5.0+, requires custom backport due to 5.9 changes
Reported-by: Ming Lei 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

dm/dax: Fix table reference counts

2020-09-23T11:00:02+00:00

commit 02186d8897d49b0afd3c80b6cf23437d91024065 upstream.

A recent fix to the dm_dax_supported() flow uncovered a latent bug. When
dm_get_live_table() fails it is still required to drop the
srcu_read_lock(). Without this change the lvm2 test-suite triggers this
warning:

    # lvm2-testsuite --only pvmove-abort-all.sh

    WARNING: lock held when returning to user space!
    5.9.0-rc5+ #251 Tainted: G           OE
    ------------------------------------------------
    lvm/1318 is leaving the kernel with locks still held!
    1 lock held by lvm/1318:
     #0: ffff9372abb5a340 (&md->io_barrier){....}-{0:0}, at: dm_get_live_table+0x5/0xb0 [dm_mod]

...and later on this hang signature:

    INFO: task lvm:1344 blocked for more than 122 seconds.
          Tainted: G           OE     5.9.0-rc5+ #251
    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
    task:lvm             state:D stack:    0 pid: 1344 ppid:     1 flags:0x00004000
    Call Trace:
     __schedule+0x45f/0xa80
     ? finish_task_switch+0x249/0x2c0
     ? wait_for_completion+0x86/0x110
     schedule+0x5f/0xd0
     schedule_timeout+0x212/0x2a0
     ? __schedule+0x467/0xa80
     ? wait_for_completion+0x86/0x110
     wait_for_completion+0xb0/0x110
     __synchronize_srcu+0xd1/0x160
     ? __bpf_trace_rcu_utilization+0x10/0x10
     __dm_suspend+0x6d/0x210 [dm_mod]
     dm_suspend+0xf6/0x140 [dm_mod]

Fixes: 7bf7eac8d648 ("dax: Arrange for dax_supported check to span multiple devices")
Cc: 
Cc: Jan Kara 
Cc: Alasdair Kergon 
Cc: Mike Snitzer 
Reported-by: Adrian Huang 
Reviewed-by: Ira Weiny 
Tested-by: Adrian Huang 
Link: https://lore.kernel.org/r/160045867590.25663.7548541079217827340.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

dm: don't call report zones for more than the user requested

2020-08-21T11:15:01+00:00

commit a9cb9f4148ef6bb8fabbdaa85c42b2171fbd5a0d upstream.

Don't call report zones for more zones than the user actually requested,
otherwise this can lead to out-of-bounds accesses in the callback
functions.

Such a situation can happen if the target's ->report_zones() callback
function returns 0 because we've reached the end of the target and then
restart the report zones on the second target.

We're again calling into ->report_zones() and ultimately into the user
supplied callback function but when we're not subtracting the number of
zones already processed this may lead to out-of-bounds accesses in the
user callbacks.

Signed-off-by: Johannes Thumshirn 
Reviewed-by: Damien Le Moal 
Fixes: d41003513e61 ("block: rework zone reporting")
Cc: stable@vger.kernel.org # v5.5+
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

dm integrity: fix integrity recalculation that is improperly skipped

2020-07-23T18:39:37+00:00

Commit adc0daad366b62ca1bce3e2958a40b0b71a8b8b3 ("dm: report suspended
device during destroy") broke integrity recalculation.

The problem is dm_suspended() returns true not only during suspend,
but also during resume. So this race condition could occur:
1. dm_integrity_resume calls queue_work(ic->recalc_wq, &ic->recalc_work)
2. integrity_recalc (&ic->recalc_work) preempts the current thread
3. integrity_recalc calls if (unlikely(dm_suspended(ic->ti))) goto unlock_ret;
4. integrity_recalc exits and no recalculating is done.

To fix this race condition, add a function dm_post_suspending that is
only true during the postsuspend phase and use it instead of
dm_suspended().

Signed-off-by: Mikulas Patocka 
Fixes: adc0daad366b ("dm: report suspended device during destroy")
Cc: stable vger kernel org # v4.18+
Signed-off-by: Mike Snitzer

dm: use noio when sending kobject event

2020-07-08T16:50:51+00:00

kobject_uevent may allocate memory and it may be called while there are dm
devices suspended. The allocation may recurse into a suspended device,
causing a deadlock. We must set the noio flag when sending a uevent.

The observed deadlock was reported here:
https://www.redhat.com/archives/dm-devel/2020-March/msg00025.html

Reported-by: Khazhismel Kumykov 
Reported-by: Tahsin Erdogan 
Reported-by: Gabriel Krisman Bertazi 
Signed-off-by: Mikulas Patocka 
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer

dm: use bio_uninit instead of bio_disassociate_blkg

2020-07-08T15:02:05+00:00

bio_uninit is the proper API to clean up a BIO that has been allocated
on stack or inside a structure that doesn't come from the BIO allocator.
Switch dm to use that instead of bio_disassociate_blkg, which really is
an implementation detail.  Note that the bio_uninit calls are also moved
to the two callers of __send_empty_flush, so that they better pair with
the bio_init calls used to initialize them.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Johannes Thumshirn 
Signed-off-by: Mike Snitzer

dm: do not use waitqueue for request-based DM

2020-07-07T16:00:01+00:00

Given request-based DM now uses blk-mq's blk_mq_queue_inflight() to
determine if outstanding IO has completed (and DM has no control over
the blk-mq state machine used to track outstanding IO) it is unsafe to
wakeup waiter (dm_wait_for_completion) before blk-mq has cleared a
request's state bits (e.g. MQ_RQ_IN_FLIGHT or MQ_RQ_COMPLETE).  As
such dm_wait_for_completion() could be left to wait indefinitely if no
other requests complete.

Fix this by eliminating request-based DM's use of waitqueue to wait
for blk-mq requests to complete in dm_wait_for_completion.

Signed-off-by: Ming Lei 
Depends-on: 3c94d83cb3526 ("blk-mq: change blk_mq_queue_busy() to blk_mq_queue_inflight()")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer

dm: update original bio sector on Zone Append

2020-06-19T16:25:58+00:00

Naohiro reported that issuing zone-append bios to a zoned block device
underneath a dm-linear device does not work as expected.

This because we forgot to reverse-map the sector the device wrote to the
original bio.

For zone-append bios, get the offset in the zone of the written sector
from the clone bio and add that to the original bio's sector position.

Fixes: 0512a75b98f8 ("block: Introduce REQ_OP_ZONE_APPEND")
Cc: stable@vger.kernel.org
Reported-by: Naohiro Aota 
Signed-off-by: Johannes Thumshirn 
Reviewed-by: Damien Le Moal 
Signed-off-by: Mike Snitzer

Merge tag 'for-5.8/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

2020-06-05T22:45:03+00:00

Pull device mapper updates from Mike Snitzer:

- The largest change for this cycle is the DM zoned target's metadata
version 2 feature that adds support for pairing regular block devices
with a zoned device to ease the performance impact associated with
finite random zones of zoned device.

The changes came in three batches: the first prepared for and then
added the ability to pair a single regular block device, the second
was a batch of fixes to improve zoned's reclaim heuristic, and the
third removed the limitation of only adding a single additional
regular block device to allow many devices.

Testing has shown linear scaling as more devices are added.

- Add new emulated block size (ebs) target that emulates a smaller
logical_block_size than a block device supports

The primary use-case is to emulate "512e" devices that have 512 byte
logical_block_size and 4KB physical_block_size. This is useful to
some legacy applications that otherwise wouldn't be able to be used
on 4K devices because they depend on issuing IO in 512 byte
granularity.

- Add discard interfaces to DM bufio. First consumer of the interface
is the dm-ebs target that makes heavy use of dm-bufio.

- Fix DM crypt's block queue_limits stacking to not truncate
logic_block_size.

- Add Documentation for DM integrity's status line.

- Switch DMDEBUG from a compile time config option to instead use
dynamic debug via pr_debug.

- Fix DM multipath target's hueristic for how it manages
"queue_if_no_path" state internally.

DM multipath now avoids disabling "queue_if_no_path" unless it is
actually needed (e.g. in response to configure timeout or explicit
"fail_if_no_path" message).

This fixes reports of spurious -EIO being reported back to userspace
application during fault tolerance testing with an NVMe backend.
Added various dynamic DMDEBUG messages to assist with debugging
queue_if_no_path in the future.

- Add a new DM multipath "Historical Service Time" Path Selector.

- Fix DM multipath's dm_blk_ioctl() to switch paths on IO error.

- Improve DM writecache target performance by using explicit cache
flushing for target's single-threaded usecase and a small cleanup to
remove unnecessary test in persistent_memory_claim.

- Other small cleanups in DM core, dm-persistent-data, and DM
integrity.

* tag 'for-5.8/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (62 commits)
dm crypt: avoid truncating the logical block size
dm mpath: add DM device name to Failing/Reinstating path log messages
dm mpath: enhance queue_if_no_path debugging
dm mpath: restrict queue_if_no_path state machine
dm mpath: simplify __must_push_back
dm zoned: check superblock location
dm zoned: prefer full zones for reclaim
dm zoned: select reclaim zone based on device index
dm zoned: allocate zone by device index
dm zoned: support arbitrary number of devices
dm zoned: move random and sequential zones into struct dmz_dev
dm zoned: per-device reclaim
dm zoned: add metadata pointer to struct dmz_dev
dm zoned: add device pointer to struct dm_zone
dm zoned: allocate temporary superblock for tertiary devices
dm zoned: convert to xarray
dm zoned: add a 'reserved' zone flag
dm zoned: improve logging messages for reclaim
dm zoned: avoid unnecessary device recalulation for secondary superblock
dm zoned: add debugging message for reading superblocks
...

dm: use bio_{start,end}_io_acct

2020-05-27T11:21:23+00:00

Switch dm to use the nicer bio accounting helpers.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Konstantin Khlebnikov 
Signed-off-by: Jens Axboe