Also rename disable_passdown_if_not_supported to
disable_discard_passdown_if_not_supported.
And fold passdown_enabled() into only caller.
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Removes assumptions about what might follow the discard setup code
(previously the code would return early if discards not enabled).
Makes it possible to add more capabilites to the end of each .io_hints
method (which is the natural thing to do when adding new features).
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
The only overlap between the block open flags mapped into the fmode_t and
other uses of fmode_t are FMODE_READ and FMODE_WRITE. Define a new
blk_mode_t instead for use in blkdev_get_by_{dev,path}, ->open and
->ioctl and stop abusing fmode_t.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jack Wang <jinpu.wang@ionos.com> [rnbd]
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230608110258.189493-28-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Don't have bio_detain() BUG_ON if a dm_cell_key is beyond
BIO_PRISON_MAX_RANGE or spans a boundary.
Update dm-thin.c:build_key() to use dm_cell_key_has_valid_range() which
will do this checking without using BUG_ON. Also update
process_discard_bio() to check the discard bio that DM core passes in
(having first imposed max_discard_granularity based splitting).
dm_cell_key_has_valid_range() will merely WARN_ON_ONCE if it returns
false because if it does: it is programmer error that should be caught
with proper testing. So relax the BUG_ONs to be WARN_ON_ONCE.
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Split the bio prison into multiple regions, with a separate rbtree and
associated lock for each region.
To get fast bio prison locking and not damage the performance of
discards too much the bio-prison now stipulates that discards should
not cross a BIO_PRISON_MAX_RANGE boundary.
Because the range of a key (block_end - block_begin) must not exceed
BIO_PRISON_MAX_RANGE: break_up_discard_bio() now ensures the data
range reflected in PHYSICAL key doesn't exceed BIO_PRISON_MAX_RANGE.
And splitting the thin target's discards (handled with VIRTUAL key) is
achieved by updating dm-thin.c to set limits->max_discard_sectors in
terms of BIO_PRISON_MAX_RANGE _and_ setting the thin and thin-pool
targets' max_discard_granularity to true.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Reduce the time that a spinlock is held in cell_defer_no_holder().
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This is an already known issue that dm-thin volume cannot be used as
swap, otherwise a deadlock may happen when dm-thin internal memory
demand triggers swap I/O on the dm-thin volume itself.
But thanks to commit a666e5c05e7c ("dm: fix deadlock when swapping to
encrypted device"), the limit_swap_bios target flag can also be used
for dm-thin to avoid the recursive I/O when it is used as swap.
Fix is to simply set ti->limit_swap_bios to true in both pool_ctr()
and thin_ctr().
In my test, I create a dm-thin volume /dev/vg/swap and use it as swap
device. Then I run fio on another dm-thin volume /dev/vg/main and use
large --blocksize to trigger swap I/O onto /dev/vg/swap.
The following fio command line is used in my test,
fio --name recursive-swap-io --lockmem 1 --iodepth 128 \
--ioengine libaio --filename /dev/vg/main --rw randrw \
--blocksize 1M --numjobs 32 --time_based --runtime=12h
Without this fix, the whole system can be locked up within 15 seconds.
With this fix, there is no any deadlock or hung task observed after
2 hours of running fio.
Furthermore, if blocksize is changed from 1M to 128M, after around 30
seconds fio has no visible I/O, and the out-of-memory killer message
shows up in kernel message. After around 20 minutes all fio processes
are killed and the whole system is back to being alive.
This is exactly what is expected when recursive I/O happens on dm-thin
volume when it is used as swap.
Depends-on: a666e5c05e7c ("dm: fix deadlock when swapping to encrypted device")
Cc: stable@vger.kernel.org
Signed-off-by: Coly Li <colyli@suse.de>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
'GPL-2.0-only' is used instead of 'GPL-2.0' because SPDX has
deprecated its use.
Suggested-by: John Wiele <jwiele@redhat.com>
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
target destruction in DM targets: thin-pool, cache, integrity and
clone.
- Fix ABBA deadlocks in DM thin-pool and cache targets due to their
use of a bufio client (that has a shrinker whose locking can cause
the incorrect locking order).
- Fix DM cache target to set its needs_check flag after first aborting
the metadata (whereby using reset persistent-data objects to update
the superblock with, otherwise the superblock update could be
dropped due to aborting metadata). This was found with
code-inspection when comparing with the equivalent in DM thinp
code.
- Fix DM thin-pool's presume to continue resuming the device even if
the pool in is fail mode -- otherwise bios may never be failed up
the IO stack (which will prevent resetting the thin-pool target via
table reload)
- Fix DM thin-pool's metadata to use proper btree root (from previous
transaction) if metadata commit failed.
- Add 'waitfor' module param to DM module (dm_mod) to allow dm-init to
wait for the specified device before continuing with its DM target
initialization.
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Merge tag 'for-6.2/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper updates from Mike Snitzer:
- Fix use-after-free races due to missing resource cleanup during DM
target destruction in DM targets: thin-pool, cache, integrity and
clone.
- Fix ABBA deadlocks in DM thin-pool and cache targets due to their use
of a bufio client (that has a shrinker whose locking can cause the
incorrect locking order).
- Fix DM cache target to set its needs_check flag after first aborting
the metadata (whereby using reset persistent-data objects to update
the superblock with, otherwise the superblock update could be dropped
due to aborting metadata). This was found with code-inspection when
comparing with the equivalent in DM thinp code.
- Fix DM thin-pool's presume to continue resuming the device even if
the pool in is fail mode -- otherwise bios may never be failed up the
IO stack (which will prevent resetting the thin-pool target via table
reload)
- Fix DM thin-pool's metadata to use proper btree root (from previous
transaction) if metadata commit failed.
- Add 'waitfor' module param to DM module (dm_mod) to allow dm-init to
wait for the specified device before continuing with its DM target
initialization.
* tag 'for-6.2/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm thin: Use last transaction's pmd->root when commit failed
dm init: add dm-mod.waitfor to wait for asynchronously probed block devices
dm ioctl: fix a couple ioctl codes
dm ioctl: a small code cleanup in list_version_get_info
dm thin: resume even if in FAIL mode
dm cache: set needs_check flag after aborting metadata
dm cache: Fix ABBA deadlock between shrink_slab and dm_cache_metadata_abort
dm thin: Fix ABBA deadlock between shrink_slab and dm_pool_abort_metadata
dm integrity: Fix UAF in dm_integrity_dtr()
dm cache: Fix UAF in destroy()
dm clone: Fix UAF in clone_dtr()
dm thin: Fix UAF in run_timer_softirq()
This macro is obsolete, so replace the last few uses with open coded
bi_opf assignments.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Coly Li <colyli@suse.de <mailto:colyli@suse.de>>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20221206144057.720846-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If a thinpool set fail_io while suspending, resume will fail with:
device-mapper: resume ioctl on vg-thinpool failed: Invalid argument
The thin-pool also can't be removed if an in-flight bio is in the
deferred list.
This can be easily reproduced using:
echo "offline" > /sys/block/sda/device/state
dd if=/dev/zero of=/dev/mapper/thin bs=4K count=1
dmsetup suspend /dev/mapper/pool
mkfs.ext4 /dev/mapper/thin
dmsetup resume /dev/mapper/pool
The root cause is maybe_resize_data_dev() will check fail_io and return
error before called dm_resume.
Fix this by adding FAIL mode check at the end of pool_preresume().
Cc: stable@vger.kernel.org
Fixes: da105ed5fd7e ("dm thin metadata: introduce dm_pool_abort_metadata")
Signed-off-by: Luo Meng <luomeng12@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
When dm_resume() and dm_destroy() are concurrent, it will
lead to UAF, as follows:
BUG: KASAN: use-after-free in __run_timers+0x173/0x710
Write of size 8 at addr ffff88816d9490f0 by task swapper/0/0
<snip>
Call Trace:
<IRQ>
dump_stack_lvl+0x73/0x9f
print_report.cold+0x132/0xaa2
_raw_spin_lock_irqsave+0xcd/0x160
__run_timers+0x173/0x710
kasan_report+0xad/0x110
__run_timers+0x173/0x710
__asan_store8+0x9c/0x140
__run_timers+0x173/0x710
call_timer_fn+0x310/0x310
pvclock_clocksource_read+0xfa/0x250
kvm_clock_read+0x2c/0x70
kvm_clock_get_cycles+0xd/0x20
ktime_get+0x5c/0x110
lapic_next_event+0x38/0x50
clockevents_program_event+0xf1/0x1e0
run_timer_softirq+0x49/0x90
__do_softirq+0x16e/0x62c
__irq_exit_rcu+0x1fa/0x270
irq_exit_rcu+0x12/0x20
sysvec_apic_timer_interrupt+0x8e/0xc0
One of the concurrency UAF can be shown as below:
use free
do_resume |
__find_device_hash_cell |
dm_get |
atomic_inc(&md->holders) |
| dm_destroy
| __dm_destroy
| if (!dm_suspended_md(md))
| atomic_read(&md->holders)
| msleep(1)
dm_resume |
__dm_resume |
dm_table_resume_targets |
pool_resume |
do_waker #add delay work |
dm_put |
atomic_dec(&md->holders) |
| dm_table_destroy
| pool_dtr
| __pool_dec
| __pool_destroy
| destroy_workqueue
| kfree(pool) # free pool
time out
__do_softirq
run_timer_softirq # pool has already been freed
This can be easily reproduced using:
1. create thin-pool
2. dmsetup suspend pool
3. dmsetup resume pool
4. dmsetup remove_all # Concurrent with 3
The root cause of this UAF bug is that dm_resume() adds timer after
dm_destroy() skips cancelling the timer because of suspend status.
After timeout, it will call run_timer_softirq(), however pool has
already been freed. The concurrency UAF bug will happen.
Therefore, cancelling timer again in __pool_destroy().
Cc: stable@vger.kernel.org
Fixes: 991d9fa02da0d ("dm: add thin provisioning target")
Signed-off-by: Luo Meng <luomeng12@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Fault inject on pool metadata device reports:
BUG: KASAN: use-after-free in dm_pool_register_metadata_threshold+0x40/0x80
Read of size 8 at addr ffff8881b9d50068 by task dmsetup/950
CPU: 7 PID: 950 Comm: dmsetup Tainted: G W 5.19.0-rc6 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x34/0x44
print_address_description.constprop.0.cold+0xeb/0x3f4
kasan_report.cold+0xe6/0x147
dm_pool_register_metadata_threshold+0x40/0x80
pool_ctr+0xa0a/0x1150
dm_table_add_target+0x2c8/0x640
table_load+0x1fd/0x430
ctl_ioctl+0x2c4/0x5a0
dm_ctl_ioctl+0xa/0x10
__x64_sys_ioctl+0xb3/0xd0
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
This can be easily reproduced using:
echo offline > /sys/block/sda/device/state
dd if=/dev/zero of=/dev/mapper/thin bs=4k count=10
dmsetup load pool --table "0 20971520 thin-pool /dev/sda /dev/sdb 128 0 0"
If a metadata commit fails, the transaction will be aborted and the
metadata space maps will be destroyed. If a DM table reload then
happens for this failed thin-pool, a use-after-free will occur in
dm_sm_register_threshold_callback (called from
dm_pool_register_metadata_threshold).
Fix this by in dm_pool_register_metadata_threshold() by returning the
-EINVAL error if the thin-pool is in fail mode. Also fail pool_ctr()
with a new error message: "Error registering metadata threshold".
Fixes: ac8c3f3df65e4 ("dm thin: generate event when metadata threshold passed")
Cc: stable@vger.kernel.org
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Luo Meng <luomeng12@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Secure erase is a very different operation from discard in that it is
a data integrity operation vs hint. Fully split the limits and helper
infrastructure to make the separation more clear.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> [drbd]
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> [nifs2]
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org> [f2fs]
Acked-by: Coly Li <colyli@suse.de> [bcache]
Acked-by: David Sterba <dsterba@suse.com> [btrfs]
Acked-by: Chao Yu <chao@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220415045258.199825-27-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Just use a non-zero max_discard_sectors as an indicator for discard
support, similar to what is done for write zeroes.
The only places where needs special attention is the RAID5 driver,
which must clear discard support for security reasons by default,
even if the default stacking rules would allow for it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> [drbd]
Acked-by: Jan Höppner <hoeppner@linux.ibm.com> [s390]
Acked-by: Coly Li <colyli@suse.de> [bcache]
Acked-by: David Sterba <dsterba@suse.com> [btrfs]
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220415045258.199825-25-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove the from_wq argument from dm_sumbit_bio_remap(). Eliminates the
need for dm_sumbit_bio_remap() callers to know whether they are
calling for a workqueue or from the original dm_submit_bio().
Add map_task to dm_io struct, record the map_task in alloc_io and
clear it after all target ->map() calls have completed. Update
dm_sumbit_bio_remap to check if 'current' matches io->map_task rather
than rely on passed 'from_rq' argument.
This change really simplifies the chore of porting each DM target to
using dm_sumbit_bio_remap() because there is no longer the risk of
programming error by not completely knowing all the different contexts
a particular method that calls dm_sumbit_bio_remap() might be used in.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Just use the %pg format specifier instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Use time_is_before_jiffies() to improve code readability.
Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Pass the block_device and operation that we plan to use this bio for to
bio_alloc to optimize the assignment. NULL/0 can be passed, both for the
passthrough case on a raw request_queue and to temporarily avoid
refactoring some nasty code.
Also move the gfp_mask argument after the nr_vecs argument for a much
more logical calling convention matching what most of the kernel does.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220124091107.642561-18-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Use blkdev_issue_flush, which uses an on-stack bio instead of an
opencoded version with a bio embedded into struct pool.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220124091107.642561-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove handling of NULL returns from sleeping bio_alloc calls given that
those can't fail.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220124091107.642561-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Use the proper helpers to read the block device size.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20211018101130.1838532-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For device mapper targets to take advantage of IMA's measurement
capabilities, the status functions for the individual targets need to be
updated to handle the status_type_t case for value STATUSTYPE_IMA.
Update status functions for the following target types, to log their
respective attributes to be measured using IMA.
01. cache
02. crypt
03. integrity
04. linear
05. mirror
06. multipath
07. raid
08. snapshot
09. striped
10. verity
For rest of the targets, handle the STATUSTYPE_IMA case by setting the
measurement buffer to NULL.
For IMA to measure the data on a given system, the IMA policy on the
system needs to be updated to have the following line, and the system
needs to be restarted for the measurements to take effect.
/etc/ima/ima-policy
measure func=CRITICAL_DATA label=device-mapper template=ima-buf
The measurements will be reflected in the IMA logs, which are located at:
/sys/kernel/security/integrity/ima/ascii_runtime_measurements
/sys/kernel/security/integrity/ima/binary_runtime_measurements
These IMA logs can later be consumed by various attestation clients
running on the system, and send them to external services for attesting
the system.
The DM target data measured by IMA subsystem can alternatively
be queried from userspace by setting DM_IMA_MEASUREMENT_FLAG with
DM_TABLE_STATUS_CMD.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Since commit ff9ea323816d ("block, bdi: an active gendisk always has a
request_queue associated with it") the request_queue pointer returned
from bdev_get_queue() shall never be NULL.
Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Except for pktdvd, the only places setting congested bits are file
systems that allocate their own backing_dev_info structures. And
pktdvd is a deprecated driver that isn't useful in stack setup
either. So remove the dead congested_fn stacking infrastructure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Song Liu <song@kernel.org>
Acked-by: David Sterba <dsterba@suse.com>
[axboe: fixup unused variables in bcache/request.c]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
generic_make_request has always been very confusingly misnamed, so rename
it to submit_bio_noacct to make it clear that it is submit_bio minus
accounting and a few checks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With commit fe64369163c5 ("dm thin: don't allow changing data device
during thin-pool load") it is now possible to re-parent the data
device's flush_bio from the pool_c to pool structure. Doing so offers
improved lifetime guarantees for the flush_bio so that the call to
dm_pool_register_pre_commit_callback can now be done safely from
pool_ctr().
Depends-on: fe64369163c5 ("dm thin: don't allow changing data device during thin-pool load")
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The existing code allows changing the data device when the thin-pool
target is reloaded.
This capability is not required and only complicates device lifetime
guarantees. This can cause crashes like the one reported here:
https://bugzilla.redhat.com/show_bug.cgi?id=1788596
where the kernel tries to issue a flush bio located in a structure that
was already freed.
Take the first step to simplifying the thin-pool's data device lifetime
by disallowing changing it. Like the thin-pool's metadata device, the
data device is now set in pool_create() and it cannot be changed for a
given thin-pool.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
dm-thin uses struct pool to hold the state of the pool. There may be
multiple pool_c's pointing to a given pool, each pool_c represents a
loaded target. pool_c's may be created and destroyed arbitrarily and the
pool contains a reference count of pool_c's pointing to it.
Since commit 694cfe7f31db3 ("dm thin: Flush data device before
committing metadata") a pointer to pool_c is passed to
dm_pool_register_pre_commit_callback and this function stores it in
pmd->pre_commit_context. If this pool_c is freed, but pool is not
(because there is another pool_c referencing it), we end up in a
situation where pmd->pre_commit_context structure points to freed
pool_c. It causes a crash in metadata_pre_commit_callback.
Fix this by moving the dm_pool_register_pre_commit_callback() from
pool_ctr() to pool_preresume(). This way the in-core thin-pool metadata
is only ever armed with callback data whose lifetime matches the
active thin-pool target.
In should be noted that this fix preserves the ability to load a
thin-pool table that uses a different data block device (that contains
the same data) -- though it is unclear if that capability is still
useful and/or needed.
Fixes: 694cfe7f31db3 ("dm thin: Flush data device before committing metadata")
Cc: stable@vger.kernel.org
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The thin provisioning target maintains per thin device mappings that map
virtual blocks to data blocks in the data device.
When we write to a shared block, in case of internal snapshots, or
provision a new block, in case of external snapshots, we copy the shared
block to a new data block (COW), update the mapping for the relevant
virtual block and then issue the write to the new data block.
Suppose the data device has a volatile write-back cache and the
following sequence of events occur:
1. We write to a shared block
2. A new data block is allocated
3. We copy the shared block to the new data block using kcopyd (COW)
4. We insert the new mapping for the virtual block in the btree for that
thin device.
5. The commit timeout expires and we commit the metadata, that now
includes the new mapping from step (4).
6. The system crashes and the data device's cache has not been flushed,
meaning that the COWed data are lost.
The next time we read that virtual block of the thin device we read it
from the data block allocated in step (2), since the metadata have been
successfully committed. The data are lost due to the crash, so we read
garbage instead of the old, shared data.
This has the following implications:
1. In case of writes to shared blocks, with size smaller than the pool's
block size (which means we first copy the whole block and then issue
the smaller write), we corrupt data that the user never touched.
2. In case of writes to shared blocks, with size equal to the device's
logical block size, we fail to provide atomic sector writes. When the
system recovers the user will read garbage from that sector instead
of the old data or the new data.
3. Even for writes to shared blocks, with size equal to the pool's block
size (overwrites), after the system recovers, the written sectors
will contain garbage instead of a random mix of sectors containing
either old data or new data, thus we fail again to provide atomic
sectors writes.
4. Even when the user flushes the thin device, because we first commit
the metadata and then pass down the flush, the same risk for
corruption exists (if the system crashes after the metadata have been
committed but before the flush is passed down to the data device.)
The only case which is unaffected is that of writes with size equal to
the pool's block size and with the FUA flag set. But, because FUA writes
trigger metadata commits, this case can trigger the corruption
indirectly.
Moreover, apart from internal and external snapshots, the same issue
exists for newly provisioned blocks, when block zeroing is enabled.
After the system recovers the provisioned blocks might contain garbage
instead of zeroes.
To solve this and avoid the potential data corruption we flush the
pool's data device **before** committing its metadata.
This ensures that the data blocks of any newly inserted mappings are
properly written to non-volatile storage and won't be lost in case of a
crash.
Cc: stable@vger.kernel.org
Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Single thread fio test (read, bs=4k, ioengine=libaio, iodepth=128,
numjobs=1) over dm-thin device has poor performance versus bare nvme
device.
Further investigation with perf indicates that queue_work_on() consumes
over 20% CPU time when doing IO over dm-thin device. The call stack is
as follows.
- 40.57% thin_map
+ 22.07% queue_work_on
+ 9.95% dm_thin_find_block
+ 2.80% cell_defer_no_holder
1.91% inc_all_io_entry.isra.33.part.34
+ 1.78% bio_detain.isra.35
In cell_defer_no_holder(), wakeup_worker() is always called, no matter
whether the tc->deferred_bio_list list is empty or not. In single thread
IO model, this list is most likely empty. So skip waking up worker thread
if tc->deferred_bio_list list is empty.
Single thread IO performance improves from 448 MiB/s to 646 MiB/s (+44%)
once the needless wake_worker() calls are properly skipped.
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
If we are in a place where it is known that interrupts are enabled,
functions spin_lock_irq/spin_unlock_irq should be used instead of
spin_lock_irqsave/spin_unlock_irqrestore.
spin_lock_irq and spin_unlock_irq are faster because they don't need to
push and pop the flags register.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Invoking dm_get_device() twice on the same device path with different
modes is dangerous. Because in that case, upgrade_mode() will alloc a
new 'dm_dev' and free the old one, which may be referenced by a previous
caller. Dereferencing the dangling pointer will trigger kernel NULL
pointer dereference.
The following two cases can reproduce this issue. Actually, they are
invalid setups that must be disallowed, e.g.:
1. Creating a thin-pool with read_only mode, and the same device as
both metadata and data.
dmsetup create thinp --table \
"0 41943040 thin-pool /dev/vdb /dev/vdb 128 0 1 read_only"
BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
...
Call Trace:
new_read+0xfb/0x110 [dm_bufio]
dm_bm_read_lock+0x43/0x190 [dm_persistent_data]
? kmem_cache_alloc_trace+0x15c/0x1e0
__create_persistent_data_objects+0x65/0x3e0 [dm_thin_pool]
dm_pool_metadata_open+0x8c/0xf0 [dm_thin_pool]
pool_ctr.cold.79+0x213/0x913 [dm_thin_pool]
? realloc_argv+0x50/0x70 [dm_mod]
dm_table_add_target+0x14e/0x330 [dm_mod]
table_load+0x122/0x2e0 [dm_mod]
? dev_status+0x40/0x40 [dm_mod]
ctl_ioctl+0x1aa/0x3e0 [dm_mod]
dm_ctl_ioctl+0xa/0x10 [dm_mod]
do_vfs_ioctl+0xa2/0x600
? handle_mm_fault+0xda/0x200
? __do_page_fault+0x26c/0x4f0
ksys_ioctl+0x60/0x90
__x64_sys_ioctl+0x16/0x20
do_syscall_64+0x55/0x150
entry_SYSCALL_64_after_hwframe+0x44/0xa9
2. Creating a external snapshot using the same thin-pool device.
dmsetup create thinp --table \
"0 41943040 thin-pool /dev/vdc /dev/vdb 128 0 2 ignore_discard"
dmsetup message /dev/mapper/thinp 0 "create_thin 0"
dmsetup create snap --table \
"0 204800 thin /dev/mapper/thinp 0 /dev/mapper/thinp"
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
...
Call Trace:
? __alloc_pages_nodemask+0x13c/0x2e0
retrieve_status+0xa5/0x1f0 [dm_mod]
? dm_get_live_or_inactive_table.isra.7+0x20/0x20 [dm_mod]
table_status+0x61/0xa0 [dm_mod]
ctl_ioctl+0x1aa/0x3e0 [dm_mod]
dm_ctl_ioctl+0xa/0x10 [dm_mod]
do_vfs_ioctl+0xa2/0x600
ksys_ioctl+0x60/0x90
? ksys_write+0x4f/0xb0
__x64_sys_ioctl+0x16/0x20
do_syscall_64+0x55/0x150
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Signed-off-by: Jason Cai (Xiang Feng) <jason.cai@linux.alibaba.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
There is no need to have DM core split discards on behalf of a DM target
now that blk_queue_split() handles splitting discards based on the
queue_limits. A DM target just needs to set max_discard_sectors,
discard_granularity, etc, in queue_limits.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
When provisioning a new data block for a virtual block, either because
the block was previously unallocated or because we are breaking sharing,
if the whole block of data is being overwritten the bio that triggered
the provisioning is issued immediately, skipping copying or zeroing of
the data block.
When this bio completes the new mapping is inserted in to the pool's
metadata by process_prepared_mapping(), where the bio completion is
signaled to the upper layers.
This completion is signaled without first committing the metadata. If
the bio in question has the REQ_FUA flag set and the system crashes
right after its completion and before the next metadata commit, then the
write is lost despite the REQ_FUA flag requiring that I/O completion for
this request must only be signaled after the data has been committed to
non-volatile storage.
Fix this by deferring the completion of overwrite bios, with the REQ_FUA
flag set, until after the metadata has been committed.
Cc: stable@vger.kernel.org
Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Commit 00a0ea33b495 ("dm thin: do not queue freed thin mapping for next
stage processing") changed process_prepared_discard_passdown_pt1() to
increment all the blocks being discarded until after the passdown had
completed to avoid them being prematurely reused.
IO issued to a thin device that breaks sharing with a snapshot, followed
by a discard issued to snapshot(s) that previously shared the block(s),
results in passdown_double_checking_shared_status() being called to
iterate through the blocks double checking their reference count is zero
and issuing the passdown if so. So a side effect of commit 00a0ea33b495
is passdown_double_checking_shared_status() was broken.
Fix this by checking if the block reference count is greater than 1.
Also, rename dm_pool_block_is_used() to dm_pool_block_is_shared().
Fixes: 00a0ea33b495 ("dm thin: do not queue freed thin mapping for next stage processing")
Cc: stable@vger.kernel.org # 4.9+
Reported-by: ryan.p.norwood@gmail.com
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Decoupled version bump from commit f6c367585d0 ("dm thin: send event
about thin-pool state change _after_ making it") because version bumps
just create conflicts when backporting to the stable trees.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Sending a DM event before a thin-pool state change is about to happen is
a bug. It wasn't realized until it became clear that userspace response
to the event raced with the actual state change that the event was
meant to notify about.
Fix this by first updating internal thin-pool state to reflect what the
DM event is being issued about. This fixes a long-standing racey/buggy
userspace device-mapper-test-suite 'resize_io' test that would get an
event but not find the state it was looking for -- so it would just go
on to hang because no other events caused the test to reevaluate the
thin-pool's state.
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The API surrounding refcount_t should be used in place of atomic_t
when variables are being used as reference counters. It can
potentially prevent reference counter overflows and use-after-free
conditions. In the dm thin layer, one such example is tc->refcount.
Change this from the atomic_t API to the refcount_t API to prevent
mentioned conditions.
Signed-off-by: John Pittman <jpittman@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Committing a transaction can consume some metadata of it's own, we now
reserve a small amount of metadata to cover this. Free metadata
reported by the kernel will not include this reserve.
If any of the reserve has been used after a commit we enter a new
internal state PM_OUT_OF_METADATA_SPACE. This is reported as
PM_READ_ONLY, so no userland changes are needed. If the metadata
device is resized the pool will move back to PM_WRITE.
These changes mean we never need to abort and rollback a transaction due
to running out of metadata space. This is particularly important
because there have been a handful of reports of data corruption against
DM thin-provisioning that can all be attributed to the thin-pool having
ran out of metadata space.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Now both check_for_space() and do_no_space_timeout() will read & write
pool->pf.error_if_no_space. If these functions run concurrently, as
shown in the following case, the default setting of "queue_if_no_space"
can get lost.
precondition:
* error_if_no_space = false (aka "queue_if_no_space")
* pool is in Out-of-Data-Space (OODS) mode
* no_space_timeout worker has been queued
CPU 0: CPU 1:
// delete a thin device
process_delete_mesg()
// check_for_space() invoked by commit()
set_pool_mode(pool, PM_WRITE)
pool->pf.error_if_no_space = \
pt->requested_pf.error_if_no_space
// timeout, pool is still in OODS mode
do_no_space_timeout
// "queue_if_no_space" config is lost
pool->pf.error_if_no_space = true
pool->pf.mode = new_mode
Fix it by stopping no_space_timeout worker when switching to write mode.
Fixes: bcc696fac11f ("dm thin: stay in out-of-data-space mode once no_space_timeout expires")
Cc: stable@vger.kernel.org
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
