summaryrefslogtreecommitdiff
path: root/drivers/md/dm.c
AgeCommit message (Collapse)Author
2019-01-22dm: add missing trace_block_split() to __split_and_process_bio()Mike Snitzer
Provides useful context about bio splits in blktrace. Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-01-22dm: fix dm_wq_work() to only use __split_and_process_bio() if appropriateMike Snitzer
Otherwise targets that don't support/expect IO splitting could resubmit bios using code paths with unnecessary IO splitting complexity. Depends-on: 24113d487843 ("dm: avoid indirect call in __dm_make_request") Fixes: 978e51ba38e00 ("dm: optimize bio-based NVMe IO submission") Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-01-21dm: fix redundant IO accounting for bios that need splittingMike Snitzer
The risk of redundant IO accounting was not taken into consideration when commit 18a25da84354 ("dm: ensure bio submission follows a depth-first tree walk") introduced IO splitting in terms of recursion via generic_make_request(). Fix this by subtracting the split bio's payload from the IO stats that were already accounted for by start_io_acct() upon dm_make_request() entry. This repeat oscillation of the IO accounting, up then down, isn't ideal but refactoring DM core's IO splitting to pre-split bios _before_ they are accounted turned out to be an excessive amount of change that will need a full development cycle to refine and verify. Before this fix: /dev/mapper/stripe_dev is a 4-way stripe using a 32k chunksize, so bios are split on 32k boundaries. # fio --name=16M --filename=/dev/mapper/stripe_dev --rw=write --bs=64k --size=16M \ --iodepth=1 --ioengine=libaio --direct=1 --refill_buffers with debugging added: [103898.310264] device-mapper: core: start_io_acct: dm-2 WRITE bio->bi_iter.bi_sector=0 len=128 [103898.318704] device-mapper: core: __split_and_process_bio: recursing for following split bio: [103898.329136] device-mapper: core: start_io_acct: dm-2 WRITE bio->bi_iter.bi_sector=64 len=64 ... 16M written yet 136M (278528 * 512b) accounted: # cat /sys/block/dm-2/stat | awk '{ print $7 }' 278528 After this fix: 16M written and 16M (32768 * 512b) accounted: # cat /sys/block/dm-2/stat | awk '{ print $7 }' 32768 Fixes: 18a25da84354 ("dm: ensure bio submission follows a depth-first tree walk") Cc: stable@vger.kernel.org # 4.16+ Reported-by: Bryan Gurney <bgurney@redhat.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-01-21dm: fix clone_bio() to trigger blk_recount_segments()Mike Snitzer
DM's clone_bio() now benefits from using bio_trim() by fixing the fact that clone_bio() wasn't clearing BIO_SEG_VALID like bio_trim() does; which triggers blk_recount_segments() via bio_phys_segments(). Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-12-28Merge tag 'for-4.21/dm-changes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper updates from Mike Snitzer: - Eliminate a couple indirect calls from bio-based DM core. - Fix DM to allow reads that exceed readahead limits by setting io_pages in the backing_dev_info. - A couple code cleanups in request-based DM. - Fix various DM targets to check for device sector overflow if CONFIG_LBDAF is not set. - Use u64 instead of sector_t to store iv_offset in DM crypt; sector_t isn't large enough on 32bit when CONFIG_LBDAF is not set. - Performance fixes to DM's kcopyd and the snapshot target focused on limiting memory use and workqueue stalls. - Fix typos in the integrity and writecache targets. - Log which algorithm is used for dm-crypt's encryption and dm-integrity's hashing. - Fix false -EBUSY errors in DM raid target's handling of check/repair messages. - Fix DM flakey target's corrupt_bio_byte feature to reliably corrupt the Nth byte in a bio's payload. * tag 'for-4.21/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm: do not allow readahead to limit IO size dm raid: fix false -EBUSY when handling check/repair message dm rq: cleanup leftover code from recently removed q->mq_ops branching dm verity: log the hash algorithm implementation dm crypt: log the encryption algorithm implementation dm integrity: fix spelling mistake in workqueue name dm flakey: Properly corrupt multi-page bios. dm: Check for device sector overflow if CONFIG_LBDAF is not set dm crypt: use u64 instead of sector_t to store iv_offset dm kcopyd: Fix bug causing workqueue stalls dm snapshot: Fix excessive memory usage and workqueue stalls dm bufio: update comment in dm-bufio.c dm writecache: fix typo in error msg for creating writecache_flush_thread dm: remove indirect calls from __send_changing_extent_only() dm mpath: only flush workqueue when needed dm rq: remove unused arguments from rq_completed() dm: avoid indirect call in __dm_make_request
2018-12-28Merge tag 'for-4.21/block-20181221' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull block updates from Jens Axboe: "This is the main pull request for block/storage for 4.21. Larger than usual, it was a busy round with lots of goodies queued up. Most notable is the removal of the old IO stack, which has been a long time coming. No new features for a while, everything coming in this week has all been fixes for things that were previously merged. This contains: - Use atomic counters instead of semaphores for mtip32xx (Arnd) - Cleanup of the mtip32xx request setup (Christoph) - Fix for circular locking dependency in loop (Jan, Tetsuo) - bcache (Coly, Guoju, Shenghui) * Optimizations for writeback caching * Various fixes and improvements - nvme (Chaitanya, Christoph, Sagi, Jay, me, Keith) * host and target support for NVMe over TCP * Error log page support * Support for separate read/write/poll queues * Much improved polling * discard OOM fallback * Tracepoint improvements - lightnvm (Hans, Hua, Igor, Matias, Javier) * Igor added packed metadata to pblk. Now drives without metadata per LBA can be used as well. * Fix from Geert on uninitialized value on chunk metadata reads. * Fixes from Hans and Javier to pblk recovery and write path. * Fix from Hua Su to fix a race condition in the pblk recovery code. * Scan optimization added to pblk recovery from Zhoujie. * Small geometry cleanup from me. - Conversion of the last few drivers that used the legacy path to blk-mq (me) - Removal of legacy IO path in SCSI (me, Christoph) - Removal of legacy IO stack and schedulers (me) - Support for much better polling, now without interrupts at all. blk-mq adds support for multiple queue maps, which enables us to have a map per type. This in turn enables nvme to have separate completion queues for polling, which can then be interrupt-less. Also means we're ready for async polled IO, which is hopefully coming in the next release. - Killing of (now) unused block exports (Christoph) - Unification of the blk-rq-qos and blk-wbt wait handling (Josef) - Support for zoned testing with null_blk (Masato) - sx8 conversion to per-host tag sets (Christoph) - IO priority improvements (Damien) - mq-deadline zoned fix (Damien) - Ref count blkcg series (Dennis) - Lots of blk-mq improvements and speedups (me) - sbitmap scalability improvements (me) - Make core inflight IO accounting per-cpu (Mikulas) - Export timeout setting in sysfs (Weiping) - Cleanup the direct issue path (Jianchao) - Export blk-wbt internals in block debugfs for easier debugging (Ming) - Lots of other fixes and improvements" * tag 'for-4.21/block-20181221' of git://git.kernel.dk/linux-block: (364 commits) kyber: use sbitmap add_wait_queue/list_del wait helpers sbitmap: add helpers for add/del wait queue handling block: save irq state in blkg_lookup_create() dm: don't reuse bio for flushes nvme-pci: trace SQ status on completions nvme-rdma: implement polling queue map nvme-fabrics: allow user to pass in nr_poll_queues nvme-fabrics: allow nvmf_connect_io_queue to poll nvme-core: optionally poll sync commands block: make request_to_qc_t public nvme-tcp: fix spelling mistake "attepmpt" -> "attempt" nvme-tcp: fix endianess annotations nvmet-tcp: fix endianess annotations nvme-pci: refactor nvme_poll_irqdisable to make sparse happy nvme-pci: only set nr_maps to 2 if poll queues are supported nvmet: use a macro for default error location nvmet: fix comparison of a u16 with -1 blk-mq: enable IO poll if .nr_queues of type poll > 0 blk-mq: change blk_mq_queue_busy() to blk_mq_queue_inflight() blk-mq: skip zero-queue maps in blk_mq_map_swqueue ...
2018-12-19dm: don't reuse bio for flushesJens Axboe
DM currently has a statically allocated bio that it uses to issue empty flushes. It doesn't submit this bio, it just uses it for maintaining state while setting up clones. Multiple users can access this bio at the same time. This wasn't previously an issue, even if it was a bit iffy, but with the blkg associations it can become one. We setup the blkg association, then clone bio's and submit, then remove the blkg assocation again. But since we can have multiple tasks doing this at the same time, against multiple blkg's, then we can either lose references to a blkg, or put it twice. The latter causes complaints on the percpu ref being <= 0 when released, and can cause use-after-free as well. Ming reports that xfstest generic/475 triggers this: ------------[ cut here ]------------ percpu ref (blkg_release) <= 0 (0) after switching to atomic WARNING: CPU: 13 PID: 0 at lib/percpu-refcount.c:155 percpu_ref_switch_to_atomic_rcu+0x2c9/0x4a0 Switch to just using an on-stack bio for this, and get rid of the embedded bio. Fixes: 5cdf2e3fea5e ("blkcg: associate blkg when associating a device") Reported-by: Ming Lei <ming.lei@redhat.com> Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-18dm: remove indirect calls from __send_changing_extent_only()Mike Snitzer
No need to be so fancy. Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-12-18dm: avoid indirect call in __dm_make_requestMikulas Patocka
Indirect calls are inefficient because of retpolines that are used for spectre workaround. This patch replaces an indirect call with a condition (that can be predicted by the branch predictor). Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-12-17blk-mq: change blk_mq_queue_busy() to blk_mq_queue_inflight()Jens Axboe
There's a single user of this function, dm, and dm just wants to check if IO is inflight, not that it's just allocated. This fixes a hang with srp/002 in blktests with dm, where it tries to suspend but waits for inflight IO to finish first. As it checks for just allocated requests, this fails. Tested-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-11dm: fix request-based dm's use of dm_wait_for_completionMike Snitzer
The md->wait waitqueue is used by both bio-based and request-based DM. Commit dbd3bbd291 ("dm rq: leverage blk_mq_queue_busy() to check for outstanding IO") lost sight of the requirement that dm_wait_for_completion() must work with all types of DM devices. Fix md_in_flight() to call the blk-mq or bio-based method accordingly. Fixes: dbd3bbd291 ("dm rq: leverage blk_mq_queue_busy() to check for outstanding IO") Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-10dm: fix inflight IO checkJens Axboe
After switching to percpu inflight counters, the inflight check is totally buggy. It's perfectly valid for some counters to be non-zero while having a total inflight IO count of 0, that's how these kinds of counters work (inc on one CPU, dec on another). Fix the md_in_flight() check to sum all counters before returning a false positive, potentially. While at it, remove the inflight read for IO completion. We don't need it, just wake anyone that's waiting for the IO count to drop to zero. The caller needs to re-check that value anyway when woken, which it does. Fixes: 6f75723190d8 ("dm: remove the pending IO accounting") Acked-by: Mike Snitzer <snitzer@redhat.com> Reported-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-10dm: remove the pending IO accountingMikulas Patocka
Remove the "pending" atomic counters, that duplicate block-core's in_flight counters, and update md_in_flight() to look at percpu in_flight counters. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-10dm: dont rewrite dm_disk(md)->part0.in_flightMikulas Patocka
generic_start_io_acct and generic_end_io_acct already update the variable in_flight using atomic operations, so we don't have to overwrite them again. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-07dm: set the static flush bio device on demandDennis Zhou
The next patch changes the macro bio_set_dev() to associate a bio with a blkg based on the device set. However, dm creates a static bio to be used as the basis for cloning empty flush bios on creation. The bio_set_dev() call in alloc_dev() will cause problems with the next patch adding association to bio_set_dev() because the call is before the bdev is associated with a gendisk (bd_disk is %NULL). To get around this, set the device on the static bio every time and use that to clone to the other bios. Signed-off-by: Dennis Zhou <dennis@kernel.org> Acked-by: Mike Snitzer <snitzer@redhat.com> Cc: Alasdair Kergon <agk@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-07dm: call blk_queue_split() to impose device limits on biosMike Snitzer
Otherwise the incoming bios, of various types, won't be shaped based on the DM device's advertised limits. Depends-on: af67c31fba ("blk: remove bio_set arg from blk_queue_split()") Fixes: 744889b7cb ("block: don't deal with discard limit in blkdev_issue_discard()") Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-11-15block: remove the lock argument to blk_alloc_queue_nodeChristoph Hellwig
With the legacy request path gone there is no real need to override the queue_lock. Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-26Merge tag 'for-4.20/dm-changes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper updates from Mike Snitzer: - The biggest change this cycle is to remove support for the legacy IO path (.request_fn) from request-based DM. Jens has already started preparing for complete removal of the legacy IO path in 4.21 but this earlier removal of support from DM has been coordinated with Jens (as evidenced by the commit being attributed to him). Making request-based DM exclussively blk-mq only cleans up that portion of DM core quite nicely. - Convert the thinp and zoned targets over to using refcount_t where applicable. - A couple fixes to the DM zoned target for refcounting and other races buried in the implementation of metadata block creation and use. - Small cleanups to remove redundant unlikely() around a couple WARN_ON_ONCE(). - Simplify how dm-ioctl copies from userspace, eliminating some potential for a malicious user trying to change the executed ioctl after its processing has begun. - Tweaked DM crypt target to use the DM device name when naming the various workqueues created for a particular DM crypt device (makes the N workqueues for a DM crypt device more easily understood and enhances user's accounting capabilities at a glance via "ps") - Small fixup to remove dead branch in DM writecache's memory_entry(). * tag 'for-4.20/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm writecache: remove disabled code in memory_entry() dm zoned: fix various dmz_get_mblock() issues dm zoned: fix metadata block ref counting dm raid: avoid bitmap with raid4/5/6 journal device dm crypt: make workqueue names device-specific dm: add dm_table_device_name() dm ioctl: harden copy_params()'s copy_from_user() from malicious users dm: remove unnecessary unlikely() around WARN_ON_ONCE() dm zoned: target: use refcount_t for dm zoned reference counters dm thin: use refcount_t for thin_c reference counting dm table: require that request-based DM be layered on blk-mq devices dm: rename DM_TYPE_MQ_REQUEST_BASED to DM_TYPE_REQUEST_BASED dm: remove legacy request-based IO path
2018-10-25block: add a report_zones methodChristoph Hellwig
Dispatching a report zones command through the request queue is a major pain due to the command reply payload rewriting necessary. Given that blkdev_report_zones() is executing everything synchronously, implement report zones as a block device file operation instead, allowing major simplification of the code in many places. sd, null-blk, dm-linear and dm-flakey being the only block device drivers supporting exposing zoned block devices, these drivers are modified to provide the device side implementation of the report_zones() block device file operation. For device mappers, a new report_zones() target type operation is defined so that the upper block layer calls blkdev_report_zones() can be propagated down to the underlying devices of the dm targets. Implementation for this new operation is added to the dm-linear and dm-flakey targets. Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> [Damien] * Changed method block_device argument to gendisk * Various bug fixes and improvements * Added support for null_blk, dm-linear and dm-flakey. Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-16dm: remove unnecessary unlikely() around WARN_ON_ONCE()Igor Stoppa
WARN_ON() already contains an unlikely(), so it's not necessary to wrap it into another. Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-10-11dm: rename DM_TYPE_MQ_REQUEST_BASED to DM_TYPE_REQUEST_BASEDMike Snitzer
Now that request-based DM is only using blk-mq, there is no need to differentiate between legacy "rq" and new "mq". We're back to a single request-based DM -- and there was much rejoicing! Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-10-11dm: remove legacy request-based IO pathJens Axboe
dm supports both, and since we're killing off the legacy path in general, get rid of it in dm. Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-10-09dm: fix report zone remapping to account for partition offsetDamien Le Moal
If dm-linear or dm-flakey are layered on top of a partition of a zoned block device, remapping of the start sector and write pointer position of the zones reported by a report zones BIO must be modified to account for the target table entry mapping (start offset within the device and entry mapping with the dm device). If the target's backing device is a partition of a whole disk, the start sector on the physical device of the partition must also be accounted for when modifying the zone information. However, dm_remap_zone_report() was not considering this last case, resulting in incorrect zone information remapping with targets using disk partitions. Fix this by calculating the target backing device start sector using the position of the completed report zones BIO and the unchanged position and size of the original report zone BIO. With this value calculated, the start sector and write pointer position of the target zones can be correctly remapped. Fixes: 10999307c14e ("dm: introduce dm_remap_zone_report()") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-07-18block: Add and use op_stat_group() for indexing disk_stat fields.Michael Callahan
Add and use a new op_stat_group() function for indexing partition stat fields rather than indexing them by rq_data_dir() or bio_data_dir(). This function works similarly to op_is_sync() in that it takes the request::cmd_flags or bio::bi_opf flags and determines which stats should et updated. In addition, the second parameter to generic_start_io_acct() and generic_end_io_acct() is now a REQ_OP rather than simply a read or write bit and it uses op_stat_group() on the parameter to determine the stat group. Note that the partition in_flight counts are not part of the per-cpu statistics and as such are not indexed via this function. It's now indexed by op_is_write(). tj: Refreshed on top of v4.17. Updated to pass around REQ_OP. Signed-off-by: Michael Callahan <michaelcallahan@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Joshua Morris <josh.h.morris@us.ibm.com> Cc: Philipp Reisner <philipp.reisner@linbit.com> Cc: Matias Bjorling <mb@lightnvm.io> Cc: Kent Overstreet <kent.overstreet@gmail.com> Cc: Alasdair Kergon <agk@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-28dm: prevent DAX mounts if not supportedRoss Zwisler
Currently device_supports_dax() just checks to see if the QUEUE_FLAG_DAX flag is set on the device's request queue to decide whether or not the device supports filesystem DAX. Really we should be using bdev_dax_supported() like filesystems do at mount time. This performs other tests like checking to make sure the dax_direct_access() path works. We also explicitly clear QUEUE_FLAG_DAX on the DM device's request queue if any of the underlying devices do not support DAX. This makes the handling of QUEUE_FLAG_DAX consistent with the setting/clearing of most other flags in dm_table_set_restrictions(). Now that bdev_dax_supported() explicitly checks for QUEUE_FLAG_DAX, this will ensure that filesystems built upon DM devices will only be able to mount with DAX if all underlying devices also support DAX. Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Fixes: commit 545ed20e6df6 ("dm: add infrastructure for DAX support") Cc: stable@vger.kernel.org Acked-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Toshi Kani <toshi.kani@hpe.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-06-22dm: use bio_split() when splitting out the already processed bioMike Snitzer
Use of bio_clone_bioset() is inefficient if there is no need to clone the original bio's bio_vec array. Best to use the bio_clone_fast() variant. Also, just using bio_advance() is only part of what is needed to properly setup the clone -- it doesn't account for the various bio_integrity() related work that also needs to be performed (see bio_split). Address both of these issues by switching from bio_clone_bioset() to bio_split(). Fixes: 18a25da8 ("dm: ensure bio submission follows a depth-first tree walk") Cc: stable@vger.kernel.org # 4.15+, requires removal of '&' before md->queue->bio_split Reported-by: Christoph Hellwig <hch@lst.de> Reviewed-by: NeilBrown <neilb@suse.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-06-08Merge tag 'libnvdimm-for-4.18' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm Pull libnvdimm updates from Dan Williams: "This adds a user for the new 'bytes-remaining' updates to memcpy_mcsafe() that you already received through Ingo via the x86-dax- for-linus pull. Not included here, but still targeting this cycle, is support for handling memory media errors (poison) consumed via userspace dax mappings. Summary: - DAX broke a fundamental assumption of truncate of file mapped pages. The truncate path assumed that it is safe to disconnect a pinned page from a file and let the filesystem reclaim the physical block. With DAX the page is equivalent to the filesystem block. Introduce dax_layout_busy_page() to enable filesystems to wait for pinned DAX pages to be released. Without this wait a filesystem could allocate blocks under active device-DMA to a new file. - DAX arranges for the block layer to be bypassed and uses dax_direct_access() + copy_to_iter() to satisfy read(2) calls. However, the memcpy_mcsafe() facility is available through the pmem block driver. In order to safely handle media errors, via the DAX block-layer bypass, introduce copy_to_iter_mcsafe(). - Fix cache management policy relative to the ACPI NFIT Platform Capabilities Structure to properly elide cache flushes when they are not necessary. The table indicates whether CPU caches are power-fail protected. Clarify that a deep flush is always performed on REQ_{FUA,PREFLUSH} requests" * tag 'libnvdimm-for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (21 commits) dax: Use dax_write_cache* helpers libnvdimm, pmem: Do not flush power-fail protected CPU caches libnvdimm, pmem: Unconditionally deep flush on *sync libnvdimm, pmem: Complete REQ_FLUSH => REQ_PREFLUSH acpi, nfit: Remove ecc_unit_size dax: dax_insert_mapping_entry always succeeds libnvdimm, e820: Register all pmem resources libnvdimm: Debug probe times linvdimm, pmem: Preserve read-only setting for pmem devices x86, nfit_test: Add unit test for memcpy_mcsafe() pmem: Switch to copy_to_iter_mcsafe() dax: Report bytes remaining in dax_iomap_actor() dax: Introduce a ->copy_to_iter dax operation uio, lib: Fix CONFIG_ARCH_HAS_UACCESS_MCSAFE compilation xfs, dax: introduce xfs_break_dax_layouts() xfs: prepare xfs_break_layouts() for another layout type xfs: prepare xfs_break_layouts() to be called with XFS_MMAPLOCK_EXCL mm, fs, dax: handle layout changes to pinned dax mappings mm: fix __gup_device_huge vs unmap mm: introduce MEMORY_DEVICE_FS_DAX and CONFIG_DEV_PAGEMAP_OPS ...
2018-06-08dm: use bioset_init_from_src() to copy bio_setJens Axboe
We can't just copy and clear a bio_set, use the bio helper to setup a new bio_set with the settings from another one. Fixes: 6f1c819c219f ("dm: convert to bioset_init()/mempool_init()") Reported-by: Venkat R.B <vrbagal1@linux.vnet.ibm.com> Tested-by: Venkat R.B <vrbagal1@linux.vnet.ibm.com> Tested-by: Li Wang <liwang@redhat.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-04Merge tag 'for-4.18/block-20180603' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull block updates from Jens Axboe: - clean up how we pass around gfp_t and blk_mq_req_flags_t (Christoph) - prepare us to defer scheduler attach (Christoph) - clean up drivers handling of bounce buffers (Christoph) - fix timeout handling corner cases (Christoph/Bart/Keith) - bcache fixes (Coly) - prep work for bcachefs and some block layer optimizations (Kent). - convert users of bio_sets to using embedded structs (Kent). - fixes for the BFQ io scheduler (Paolo/Davide/Filippo) - lightnvm fixes and improvements (Matias, with contributions from Hans and Javier) - adding discard throttling to blk-wbt (me) - sbitmap blk-mq-tag handling (me/Omar/Ming). - remove the sparc jsflash block driver, acked by DaveM. - Kyber scheduler improvement from Jianchao, making it more friendly wrt merging. - conversion of symbolic proc permissions to octal, from Joe Perches. Previously the block parts were a mix of both. - nbd fixes (Josef and Kevin Vigor) - unify how we handle the various kinds of timestamps that the block core and utility code uses (Omar) - three NVMe pull requests from Keith and Christoph, bringing AEN to feature completeness, file backed namespaces, cq/sq lock split, and various fixes - various little fixes and improvements all over the map * tag 'for-4.18/block-20180603' of git://git.kernel.dk/linux-block: (196 commits) blk-mq: update nr_requests when switching to 'none' scheduler block: don't use blocking queue entered for recursive bio submits dm-crypt: fix warning in shutdown path lightnvm: pblk: take bitmap alloc. out of critical section lightnvm: pblk: kick writer on new flush points lightnvm: pblk: only try to recover lines with written smeta lightnvm: pblk: remove unnecessary bio_get/put lightnvm: pblk: add possibility to set write buffer size manually lightnvm: fix partial read error path lightnvm: proper error handling for pblk_bio_add_pages lightnvm: pblk: fix smeta write error path lightnvm: pblk: garbage collect lines with failed writes lightnvm: pblk: rework write error recovery path lightnvm: pblk: remove dead function lightnvm: pass flag on graceful teardown to targets lightnvm: pblk: check for chunk size before allocating it lightnvm: pblk: remove unnecessary argument lightnvm: pblk: remove unnecessary indirection lightnvm: pblk: return NVM_ error on failed submission lightnvm: pblk: warn in case of corrupted write buffer ...
2018-05-30dm: convert to bioset_init()/mempool_init()Kent Overstreet
Convert dm to embedded bio sets. Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-30block: convert bounce, q->bio_split to bioset_init()/mempool_init()Kent Overstreet
Convert the core block functionality to embedded bio sets. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-22dax: Introduce a ->copy_to_iter dax operationDan Williams
Similar to the ->copy_from_iter() operation, a platform may want to deploy an architecture or device specific routine for handling reads from a dax_device like /dev/pmemX. On x86 this routine will point to a machine check safe version of copy_to_iter(). For now, add the plumbing to device-mapper and the dax core. Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-04-30dm: fix some sparse warnings and whitespace in dax methodsMike Snitzer
Eliminate these sparse warnings: drivers/md/dm.c:1062:9: warning: context imbalance in 'dm_dax_direct_access' - unexpected unlock drivers/md/dm.c:1086:9: warning: context imbalance in 'dm_dax_copy_from_iter' - unexpected unlock Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-10Merge tag 'libnvdimm-for-4.17' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm Pull libnvdimm updates from Dan Williams: "This cycle was was not something I ever want to repeat as there were several late changes that have only now just settled. Half of the branch up to commit d2c997c0f145 ("fs, dax: use page->mapping to warn...") have been in -next for several releases. The of_pmem driver and the address range scrub rework were late arrivals, and the dax work was scaled back at the last moment. The of_pmem driver missed a previous merge window due to an oversight. A sense of obligation to rectify that miss is why it is included for 4.17. It has acks from PowerPC folks. Stephen reported a build failure that only occurs when merging it with your latest tree, for now I have fixed that up by disabling modular builds of of_pmem. A test merge with your tree has received a build success report from the 0day robot over 156 configs. An initial version of the ARS rework was submitted before the merge window. It is self contained to libnvdimm, a net code reduction, and passing all unit tests. The filesystem-dax changes are based on the wait_var_event() functionality from tip/sched/core. However, late review feedback showed that those changes regressed truncate performance to a large degree. The branch was rewound to drop the truncate behavior change and now only includes preparation patches and cleanups (with full acks and reviews). The finalization of this dax-dma-vs-trnucate work will need to wait for 4.18. Summary: - A rework of the filesytem-dax implementation provides for detection of unmap operations (truncate / hole punch) colliding with in-progress device-DMA. A fix for these collisions remains a work-in-progress pending resolution of truncate latency and starvation regressions. - The of_pmem driver expands the users of libnvdimm outside of x86 and ACPI to describe an implementation of persistent memory on PowerPC with Open Firmware / Device tree. - Address Range Scrub (ARS) handling is completely rewritten to account for the fact that ARS may run for 100s of seconds and there is no platform defined way to cancel it. ARS will now no longer block namespace initialization. - The NVDIMM Namespace Label implementation is updated to handle label areas as small as 1K, down from 128K. - Miscellaneous cleanups and updates to unit test infrastructure" * tag 'libnvdimm-for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (39 commits) libnvdimm, of_pmem: workaround OF_NUMA=n build error nfit, address-range-scrub: add module option to skip initial ars nfit, address-range-scrub: rework and simplify ARS state machine nfit, address-range-scrub: determine one platform max_ars value powerpc/powernv: Create platform devs for nvdimm buses doc/devicetree: Persistent memory region bindings libnvdimm: Add device-tree based driver libnvdimm: Add of_node to region and bus descriptors libnvdimm, region: quiet region probe libnvdimm, namespace: use a safe lookup for dimm device name libnvdimm, dimm: fix dpa reservation vs uninitialized label area libnvdimm, testing: update the default smart ctrl_temperature libnvdimm, testing: Add emulation for smart injection commands nfit, address-range-scrub: introduce nfit_spa->ars_state libnvdimm: add an api to cast a 'struct nd_region' to its 'struct device' nfit, address-range-scrub: fix scrub in-progress reporting dax, dm: allow device-mapper to operate without dax support dax: introduce CONFIG_DAX_DRIVER fs, dax: use page->mapping to warn if truncate collides with a busy page ext2, dax: introduce ext2_dax_aops ...
2018-04-09Merge branch 'for-4.17/dax' into libnvdimm-for-nextDan Williams
2018-04-06Merge tag 'for-4.17/dm-changes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper updates from Mike Snitzer: - DM core passthrough ioctl fix to retain reference to DM table, and that table's block devices, while issuing the ioctl to one of those block devices. - DM core passthrough ioctl fix to _not_ override the fmode_t used to issue the ioctl. Overriding by using the fmode_t that the block device was originally open with during DM table load is a liability. - Add DM core support for secure erase forwarding and update the DM linear and DM striped targets to support them. - A DM core 4.16 stable fix to allow abnormal IO (e.g. discard, write same, write zeroes) for targets that make use of the non-splitting IO variant (as is done for multipath or thinp when layered directly on NVMe). - Allow DM targets to return a payload in response to a DM message that they are sent. This is useful for DM targets that would like to provide statistics data in response to DM messages. - Update DM bufio to support non-power-of-2 block sizes. Numerous other related changes prepare the DM bufio code for this support. - Fix DM crypt to use a bounded amount of memory across the entire system. This is to avoid OOM that can otherwise occur in response to certain pathological IO workloads (e.g. discarding a large DM crypt device). - Add a 'check_at_most_once' feature to the DM verity target to allow verity to be used on mobile devices that have very limited resources. - Fix the DM integrity target to fail early if a keyed algorithm (e.g. HMAC) is to be used but the key isn't set. - Add non-power-of-2 support to the DM unstripe target. - Eliminate the use of a Variable Length Array in the DM stripe target. - Update the DM log-writes target to record metadata (REQ_META flag). - DM raid fixes for its nosync status and some variable range issues. * tag 'for-4.17/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (28 commits) dm: remove fmode_t argument from .prepare_ioctl hook dm: hold DM table for duration of ioctl rather than use blkdev_get dm raid: fix parse_raid_params() variable range issue dm verity: make verity_for_io_block static dm verity: add 'check_at_most_once' option to only validate hashes once dm bufio: don't embed a bio in the dm_buffer structure dm bufio: support non-power-of-two block sizes dm bufio: use slab cache for dm_buffer structure allocations dm bufio: reorder fields in dm_buffer structure dm bufio: relax alignment constraint on slab cache dm bufio: remove code that merges slab caches dm bufio: get rid of slab cache name allocations dm bufio: move dm-bufio.h to include/linux/ dm bufio: delete outdated comment dm: add support for secure erase forwarding dm: backfill abnormal IO support to non-splitting IO submission dm raid: fix nosync status dm mpath: use DM_MAPIO_SUBMITTED instead of magic number 0 in process_queued_bios() dm stripe: get rid of a Variable Length Array (VLA) dm log writes: record metadata flag for better flags record ...
2018-04-05Merge tag 'for-4.17/block-20180402' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull block layer updates from Jens Axboe: "It's a pretty quiet round this time, which is nice. This contains: - series from Bart, cleaning up the way we set/test/clear atomic queue flags. - series from Bart, fixing races between gendisk and queue registration and removal. - set of bcache fixes and improvements from various folks, by way of Michael Lyle. - set of lightnvm updates from Matias, most of it being the 1.2 to 2.0 transition. - removal of unused DIO flags from Nikolay. - blk-mq/sbitmap memory ordering fixes from Omar. - divide-by-zero fix for BFQ from Paolo. - minor documentation patches from Randy. - timeout fix from Tejun. - Alpha "can't write a char atomically" fix from Mikulas. - set of NVMe fixes by way of Keith. - bsg and bsg-lib improvements from Christoph. - a few sed-opal fixes from Jonas. - cdrom check-disk-change deadlock fix from Maurizio. - various little fixes, comment fixes, etc from various folks" * tag 'for-4.17/block-20180402' of git://git.kernel.dk/linux-block: (139 commits) blk-mq: Directly schedule q->timeout_work when aborting a request blktrace: fix comment in blktrace_api.h lightnvm: remove function name in strings lightnvm: pblk: remove some unnecessary NULL checks lightnvm: pblk: don't recover unwritten lines lightnvm: pblk: implement 2.0 support lightnvm: pblk: implement get log report chunk lightnvm: pblk: rename ppaf* to addrf* lightnvm: pblk: check for supported version lightnvm: implement get log report chunk helpers lightnvm: make address conversions depend on generic device lightnvm: add support for 2.0 address format lightnvm: normalize geometry nomenclature lightnvm: complete geo structure with maxoc* lightnvm: add shorten OCSSD version in geo lightnvm: add minor version to generic geometry lightnvm: simplify geometry structure lightnvm: pblk: refactor init/exit sequences lightnvm: Avoid validation of default op value lightnvm: centralize permission check for lightnvm ioctl ...
2018-04-04dm: remove fmode_t argument from .prepare_ioctl hookMike Snitzer
Use the fmode_t that is passed to dm_blk_ioctl() rather than inconsistently (varies across targets) drop it on the floor by overriding it with the fmode_t stored in 'struct dm_dev'. All the persistent reservation functions weren't using the fmode_t they got back from .prepare_ioctl so remove them. Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-04dm: hold DM table for duration of ioctl rather than use blkdev_getMike Snitzer
Commit 519049afead ("dm: use blkdev_get rather than bdgrab when issuing pass-through ioctl") inadvertantly introduced a regression relative to users of device cgroups that issue ioctls (e.g. libvirt). Using blkdev_get() in DM's passthrough ioctl support implicitly introduced a cgroup permissions check that would fail unless care were taken to add all devices in the IO stack to the device cgroup. E.g. rather than just adding the top-level DM multipath device to the cgroup all the underlying devices would need to be allowed. Fix this, to no longer require allowing all underlying devices, by simply holding the live DM table (which includes the table's original blkdev_get() reference on the blockdevice that the ioctl will be issued to) for the duration of the ioctl. Also, bump the DM ioctl version so a user can know that their device cgroup allow workaround is no longer needed. Reported-by: Michal Privoznik <mprivozn@redhat.com> Suggested-by: Mikulas Patocka <mpatocka@redhat.com> Fixes: 519049afead ("dm: use blkdev_get rather than bdgrab when issuing pass-through ioctl") Cc: stable@vger.kernel.org # 4.16 Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm: add support for secure erase forwardingDenis Semakin
Set QUEUE_FLAG_SECERASE in DM device's queue_flags if a DM table's data devices support secure erase. Also, add support for secure erase to both the linear and striped targets. Signed-off-by: Denis Semakin <d.semakin@omprussia.ru> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm: backfill abnormal IO support to non-splitting IO submissionMike Snitzer
Otherwise, these abnormal IOs would be sent to the DM target regardless of whether the target advertised support for them. Factor out __process_abnormal_io() from __split_and_process_non_flush() so that discards, write same, etc may be conditionally processed. Fixes: 978e51ba3 ("dm: optimize bio-based NVMe IO submission") Cc: stable@vger.kernel.org # 4.16 Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dax, dm: allow device-mapper to operate without dax supportDan Williams
Change device-mapper's DAX dependency to require the presence of at least one DAX_DRIVER. This allows device-mapper to be built without bringing the DAX core along which is especially wasteful when there are no DAX drivers, like BLK_DEV_PMEM, configured. Cc: Alasdair Kergon <agk@redhat.com> Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com> Reported-by: kbuild test robot <lkp@intel.com> Reported-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-03-29dm: fix dropped return code from dm_get_bdev_for_ioctlMike Snitzer
dm_get_bdev_for_ioctl()'s return of 0 or 1 must be the result from prepare_ioctl (1 means the ioctl was issued to a partition, 0 means it wasn't). Unfortunately commit 519049afea ("dm: use blkdev_get rather than bdgrab when issuing pass-through ioctl") reused the variable 'r' to store the return from blkdev_get() that follows prepare_ioctl() -- whereby dropping prepare_ioctl()'s result on the floor. This can lead to an ioctl or persistent reservation being issued to a partition going unnoticed, which implies the extra permission check for CAP_SYS_RAWIO is skipped. Fix this by using a different variable to store blkdev_get()'s return. Fixes: 519049afea ("dm: use blkdev_get rather than bdgrab when issuing pass-through ioctl") Reported-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-03-06dm: use blkdev_get rather than bdgrab when issuing pass-through ioctlMike Snitzer
Otherwise an underlying device's teardown (e.g. SCSI) may race with the DM ioctl or persistent reservation and result in dereferencing driver memory that gets freed when the underlying device's final blkdev_put() occurs. bdgrab() only increases the refcount for the block_device's inode to ensure the block_device struct itself will not be freed, but does not guarantee the block_device will remain associated with the gendisk or its storage. Cc: stable@vger.kernel.org # 4.8+ Reported-by: David Jeffery <djeffery@redhat.com> Suggested-by: David Jeffery <djeffery@redhat.com> Reviewed-by: Ben Marzinski <bmarzins@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-02-28block: Add 'lock' as third argument to blk_alloc_queue_node()Bart Van Assche
This patch does not change any functionality. Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Philipp Reisner <philipp.reisner@linbit.com> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-02-16dm: correctly handle chained bios in dec_pending()NeilBrown
dec_pending() is given an error status (possibly 0) to be recorded against a bio. It can be called several times on the one 'struct dm_io', and it is careful to only assign a non-zero error to io->status. However when it then assigned io->status to bio->bi_status, it is not careful and could overwrite a genuine error status with 0. This can happen when chained bios are in use. If a bio is chained beneath the bio that this dm_io is handling, the child bio might complete and set bio->bi_status before the dm_io completes. This has been possible since chained bios were introduced in 3.14, and has become a lot easier to trigger with commit 18a25da84354 ("dm: ensure bio submission follows a depth-first tree walk") as that commit caused dm to start using chained bios itself. A particular failure mode is that if a bio spans an 'error' target and a working target, the 'error' fragment will complete instantly and set the ->bi_status, and the other fragment will normally complete a little later, and will clear ->bi_status. The fix is simply to only assign io_error to bio->bi_status when io_error is not zero. Reported-and-tested-by: Milan Broz <gmazyland@gmail.com> Cc: stable@vger.kernel.org (v3.14+) Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-01-31Merge tag 'for-4.16/dm-changes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper updates from Mike Snitzer: - DM core fixes to ensure that bio submission follows a depth-first tree walk; this is critical to allow forward progress without the need to use the bioset's BIOSET_NEED_RESCUER. - Remove DM core's BIOSET_NEED_RESCUER based dm_offload infrastructure. - DM core cleanups and improvements to make bio-based DM more efficient (e.g. reduced memory footprint as well leveraging per-bio-data more). - Introduce new bio-based mode (DM_TYPE_NVME_BIO_BASED) that leverages the more direct IO submission path in the block layer; this mode is used by DM multipath and also optimizes targets like DM thin-pool that stack directly on NVMe data device. - DM multipath improvements to factor out legacy SCSI-only (e.g. scsi_dh) code paths to allow for more optimized support for NVMe multipath. - A fix for DM multipath path selectors (service-time and queue-length) to select paths in a more balanced way; largely academic but doesn't hurt. - Numerous DM raid target fixes and improvements. - Add a new DM "unstriped" target that enables Intel to workaround firmware limitations in some NVMe drives that are striped internally (this target also works when stacked above the DM "striped" target). - Various Documentation fixes and improvements. - Misc cleanups and fixes across various DM infrastructure and targets (e.g. bufio, flakey, log-writes, snapshot). * tag 'for-4.16/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (69 commits) dm cache: Documentation: update default migration_throttling value dm mpath selector: more evenly distribute ties dm unstripe: fix target length versus number of stripes size check dm thin: fix trailing semicolon in __remap_and_issue_shared_cell dm table: fix NVMe bio-based dm_table_determine_type() validation dm: various cleanups to md->queue initialization code dm mpath: delay the retry of a request if the target responded as busy dm mpath: return DM_MAPIO_DELAY_REQUEUE if QUEUE_IO or PG_INIT_REQUIRED dm mpath: return DM_MAPIO_REQUEUE on blk-mq rq allocation failure dm log writes: fix max length used for kstrndup dm: backfill missing calls to mutex_destroy() dm snapshot: use mutex instead of rw_semaphore dm flakey: check for null arg_name in parse_features() dm thin: extend thinpool status format string with omitted fields dm thin: fixes in thin-provisioning.txt dm thin: document representation of <highest mapped sector> when there is none dm thin: fix documentation relative to low water mark threshold dm cache: be consistent in specifying sectors and SI units in cache.txt dm cache: delete obsoleted paragraph in cache.txt dm cache: fix grammar in cache-policies.txt ...
2018-01-29dm: various cleanups to md->queue initialization codeMike Snitzer
Also, add dm_sysfs_init() error handling to dm_create(). Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-01-17dm: backfill missing calls to mutex_destroy()Mike Snitzer
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-01-15dm: fix incomplete request_queue initializationMike Snitzer
DM is no longer prone to having its request_queue be improperly initialized. Summary of changes: - defer DM's blk_register_queue() from add_disk()-time until dm_setup_md_queue() by using add_disk_no_queue_reg() in alloc_dev(). - dm_setup_md_queue() is updated to fully initialize DM's request_queue (_after_ all table loads have occurred and the request_queue's type, features and limits are known). A very welcome side-effect of these changes is DM no longer needs to: 1) backfill the "mq" sysfs entry (because historically DM didn't initialize the request_queue to use blk-mq until _after_ blk_register_queue() was called via add_disk()). 2) call elv_register_queue() to get .request_fn request-based DM device's "iosched" exposed in syfs. In addition, blk-mq debugfs support is now made available because request-based DM's blk-mq request_queue is now properly initialized before dm_setup_md_queue() calls blk_register_queue(). These changes also stave off the need to introduce new DM-specific workarounds in block core, e.g. this proposal: https://patchwork.kernel.org/patch/10067961/ In the end DM devices should be less unicorn in nature (relative to initialization and availability of block core infrastructure provided by the request_queue). Signed-off-by: Mike Snitzer <snitzer@redhat.com> Tested-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>