Commit Graph

5773 Commits

Author SHA1 Message Date
Linus Torvalds 311f71281f - Improve DM snapshot target's scalability by using finer grained
locking.  Requires some list_bl interface improvements.
 
 - Add ability for DM integrity to use a bitmap mode, that tracks regions
   where data and metadata are out of sync, instead of using a journal.
 
 - Improve DM thin provisioning target to not write metadata changes to
   disk if the thin-pool and associated thin devices are merely
   activated but not used.  This avoids metadata corruption due to
   concurrent activation of thin devices across different OS instances
   (e.g. split brain scenarios, which ultimately would be avoided if
   proper device filters were used -- but not having proper filtering has
   proven a very common configuration mistake)
 
 - Fix missing call to path selector type->end_io in DM multipath.  This
   fixes reported performance problems due to inaccurate path selector IO
   accounting causing an imbalance of IO (e.g. avoiding issuing IO to
   particular path due to it seemingly being heavily used).
 
 - Fix bug in DM cache metadata's loading of its discard bitset that
   could lead to all cache blocks being discarded if the very first cache
   block was discarded (thankfully in practice the first cache block is
   generally in use; be it FS superblock, partition table, disk label,
   etc).
 
 - Add testing-only DM dust target which simulates a device that has
   failing sectors and/or read failures.
 
 - Fix a DM init error path reference count hang that caused boot hangs
   if user supplied malformed input on kernel commandline.
 
 - Fix a couple issues with DM crypt target's logging being overly
   verbose or lacking context.
 
 - Various other small fixes to DM init, DM multipath, DM zoned, and DM
   crypt.
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Merge tag 'for-5.2/dm-changes-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - Improve DM snapshot target's scalability by using finer grained
   locking. Requires some list_bl interface improvements.

 - Add ability for DM integrity to use a bitmap mode, that tracks
   regions where data and metadata are out of sync, instead of using a
   journal.

 - Improve DM thin provisioning target to not write metadata changes to
   disk if the thin-pool and associated thin devices are merely
   activated but not used. This avoids metadata corruption due to
   concurrent activation of thin devices across different OS instances
   (e.g. split brain scenarios, which ultimately would be avoided if
   proper device filters were used -- but not having proper filtering
   has proven a very common configuration mistake)

 - Fix missing call to path selector type->end_io in DM multipath. This
   fixes reported performance problems due to inaccurate path selector
   IO accounting causing an imbalance of IO (e.g. avoiding issuing IO to
   particular path due to it seemingly being heavily used).

 - Fix bug in DM cache metadata's loading of its discard bitset that
   could lead to all cache blocks being discarded if the very first
   cache block was discarded (thankfully in practice the first cache
   block is generally in use; be it FS superblock, partition table, disk
   label, etc).

 - Add testing-only DM dust target which simulates a device that has
   failing sectors and/or read failures.

 - Fix a DM init error path reference count hang that caused boot hangs
   if user supplied malformed input on kernel commandline.

 - Fix a couple issues with DM crypt target's logging being overly
   verbose or lacking context.

 - Various other small fixes to DM init, DM multipath, DM zoned, and DM
   crypt.

* tag 'for-5.2/dm-changes-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (42 commits)
  dm: fix a couple brace coding style issues
  dm crypt: print device name in integrity error message
  dm crypt: move detailed message into debug level
  dm ioctl: fix hang in early create error condition
  dm integrity: whitespace, coding style and dead code cleanup
  dm integrity: implement synchronous mode for reboot handling
  dm integrity: handle machine reboot in bitmap mode
  dm integrity: add a bitmap mode
  dm integrity: introduce a function add_new_range_and_wait()
  dm integrity: allow large ranges to be described
  dm ingerity: pass size to dm_integrity_alloc_page_list()
  dm integrity: introduce rw_journal_sectors()
  dm integrity: update documentation
  dm integrity: don't report unused options
  dm integrity: don't check null pointer before kvfree and vfree
  dm integrity: correctly calculate the size of metadata area
  dm dust: Make dm_dust_init and dm_dust_exit static
  dm dust: remove redundant unsigned comparison to less than zero
  dm mpath: always free attached_handler_name in parse_path()
  dm init: fix max devices/targets checks
  ...
2019-05-16 15:55:48 -07:00
Sheetal Singala 8454fca4f5 dm: fix a couple brace coding style issues
Signed-off-by: Sheetal Singala <2396sheetal@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-16 10:09:21 -04:00
Milan Broz f710126cfc dm crypt: print device name in integrity error message
This message should better identify the DM device with the integrity
failure.

Signed-off-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-16 10:09:20 -04:00
Milan Broz 7a1cd7238f dm crypt: move detailed message into debug level
The information about tag size should not be printed without debug info
set. Also print device major:minor in the error message to identify the
device instance.

Also use rate limiting and debug level for info about used crypto API
implementaton.  This is important because during online reencryption
the existing message saturates syslog (because we are moving hotzone
across the whole device).

Cc: stable@vger.kernel.org
Signed-off-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-16 10:09:20 -04:00
Helen Koike 0f41fcf788 dm ioctl: fix hang in early create error condition
The dm_early_create() function (which deals with "dm-mod.create=" kernel
command line option) calls dm_hash_insert() who gets an extra reference
to the md object.

In case of failure, this reference wasn't being released, causing
dm_destroy() to hang, thus hanging the whole boot process.

Fix this by calling __hash_remove() in the error path.

Fixes: 6bbc923dfc ("dm: add support to directly boot to a mapped device")
Cc: stable@vger.kernel.org
Signed-off-by: Helen Koike <helen.koike@collabora.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-16 09:52:06 -04:00
Mike Snitzer 05d6909ea9 dm integrity: whitespace, coding style and dead code cleanup
Just some things that stood out like a sore thumb.
Also, converted some printk(KERN_CRIT, ...) to DMCRIT(...)

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-09 16:00:31 -04:00
Mikulas Patocka 482714932e dm integrity: implement synchronous mode for reboot handling
Unfortunatelly, there may be bios coming even after the reboot notifier
was called.  We don't want these bios to make the bitmap dirty again.

To address this, implement a synchronous mode - when a bio is about to
be terminated, we clean the bitmap and terminate the bio after the clean
operation succeeds.  This obviously slows down bio processing, but it
makes sure that when all bios are finished, the bitmap will be clean.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-08 13:41:59 -04:00
Mikulas Patocka 1f5a77591b dm integrity: handle machine reboot in bitmap mode
When in bitmap mode the bitmap must be cleared when rebooting.  This
commit adds the reboot hook.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-08 13:41:58 -04:00
Mikulas Patocka 468dfca38b dm integrity: add a bitmap mode
Introduce an alternate mode of operation where dm-integrity uses a
bitmap instead of a journal. If a bit in the bitmap is 1, the
corresponding region's data and integrity tags are not synchronized - if
the machine crashes, the unsynchronized regions will be recalculated.
The bitmap mode is faster than the journal mode, because we don't have
to write the data twice, but it is also less reliable, because if data
corruption happens when the machine crashes, it may not be detected.

Benchmark results for an SSD connected to a SATA300 port, when doing
large linear writes with dd:

buffered I/O:
        raw device throughput - 245MB/s
        dm-integrity with journaling - 120MB/s
        dm-integrity with bitmap - 238MB/s

direct I/O with 1MB block size:
        raw device throughput - 248MB/s
        dm-integrity with journaling - 123MB/s
        dm-integrity with bitmap - 223MB/s

For more info see dm-integrity in Documentation/device-mapper/

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-08 13:41:58 -04:00
Mikulas Patocka 8b3bbd490d dm integrity: introduce a function add_new_range_and_wait()
Introduce a function add_new_range_and_wait() in order to avoid
repetitive code.  It will be used in the following commit.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-08 13:40:28 -04:00
Linus Torvalds 67a2422239 for-5.2/block-20190507
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Merge tag 'for-5.2/block-20190507' of git://git.kernel.dk/linux-block

Pull block updates from Jens Axboe:
 "Nothing major in this series, just fixes and improvements all over the
  map. This contains:

   - Series of fixes for sed-opal (David, Jonas)

   - Fixes and performance tweaks for BFQ (via Paolo)

   - Set of fixes for bcache (via Coly)

   - Set of fixes for md (via Song)

   - Enabling multi-page for passthrough requests (Ming)

   - Queue release fix series (Ming)

   - Device notification improvements (Martin)

   - Propagate underlying device rotational status in loop (Holger)

   - Removal of mtip32xx trim support, which has been disabled for years
     (Christoph)

   - Improvement and cleanup of nvme command handling (Christoph)

   - Add block SPDX tags (Christoph)

   - Cleanup/hardening of bio/bvec iteration (Christoph)

   - A few NVMe pull requests (Christoph)

   - Removal of CONFIG_LBDAF (Christoph)

   - Various little fixes here and there"

* tag 'for-5.2/block-20190507' of git://git.kernel.dk/linux-block: (164 commits)
  block: fix mismerge in bvec_advance
  block: don't drain in-progress dispatch in blk_cleanup_queue()
  blk-mq: move cancel of hctx->run_work into blk_mq_hw_sysfs_release
  blk-mq: always free hctx after request queue is freed
  blk-mq: split blk_mq_alloc_and_init_hctx into two parts
  blk-mq: free hw queue's resource in hctx's release handler
  blk-mq: move cancel of requeue_work into blk_mq_release
  blk-mq: grab .q_usage_counter when queuing request from plug code path
  block: fix function name in comment
  nvmet: protect discovery change log event list iteration
  nvme: mark nvme_core_init and nvme_core_exit static
  nvme: move command size checks to the core
  nvme-fabrics: check more command sizes
  nvme-pci: check more command sizes
  nvme-pci: remove an unneeded variable initialization
  nvme-pci: unquiesce admin queue on shutdown
  nvme-pci: shutdown on timeout during deletion
  nvme-pci: fix psdt field for single segment sgls
  nvme-multipath: don't print ANA group state by default
  nvme-multipath: split bios with the ns_head bio_set before submitting
  ...
2019-05-07 18:14:36 -07:00
Mikulas Patocka 4f43446ddf dm integrity: allow large ranges to be described
Change n_sectors data type from unsigned to sector_t.  Following commits
will need to lock large ranges.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-07 16:05:12 -04:00
Mikulas Patocka d5027e0345 dm ingerity: pass size to dm_integrity_alloc_page_list()
Pass size to dm_integrity_alloc_page_list().  This is needed so
following commits can pass a size that is different from
ic->journal_pages.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-07 16:05:12 -04:00
Mikulas Patocka 981e8a980d dm integrity: introduce rw_journal_sectors()
Introduce a function rw_journal_sectors() that takes sector and length
as its arguments instead of a section and the number of sections.

This functions will be used in further patches.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-07 16:05:11 -04:00
Mikulas Patocka 88ad5d1eb1 dm integrity: update documentation
Update documentation with the "meta_device" parameter and flags.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-07 16:05:10 -04:00
Mikulas Patocka 893e3c395b dm integrity: don't report unused options
If we are not journaling, don't report journaling options in the table
status.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-07 16:05:09 -04:00
Mikulas Patocka 97abfde17a dm integrity: don't check null pointer before kvfree and vfree
The functions kfree, vfree and kvfree do nothing if we pass a NULL
pointer to them.  So we don't need to test the pointer for NULL.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-07 16:05:08 -04:00
Mikulas Patocka 30bba430dd dm integrity: correctly calculate the size of metadata area
When we use separate devices for data and metadata, dm-integrity would
incorrectly calculate the size of the metadata device as if it had
512-byte block size - and it would refuse activation with larger block
size and smaller metadata device.

Fix this so that it takes actual block size into account, which fixes
the following reported issue:
https://gitlab.com/cryptsetup/cryptsetup/issues/450

Fixes: 356d9d52e1 ("dm integrity: allow separate metadata device")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-07 16:05:08 -04:00
YueHaibing 9ccce5a0fb dm dust: Make dm_dust_init and dm_dust_exit static
Fix sparse warnings:

drivers/md/dm-dust.c:495:12: warning: symbol 'dm_dust_init' was not declared. Should it be static?
drivers/md/dm-dust.c:505:13: warning: symbol 'dm_dust_exit' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-07 16:05:07 -04:00
Colin Ian King cacddeab56 dm dust: remove redundant unsigned comparison to less than zero
Variable block is an unsigned long long hence the less than zero
comparison is always false, hence it is redundant and can be removed.

Addresses-Coverity: ("Unsigned compared against 0")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Bryan Gurney <bgurney@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-05-07 16:05:06 -04:00
Linus Torvalds 81ff5d2cba Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
Pull crypto update from Herbert Xu:
 "API:
   - Add support for AEAD in simd
   - Add fuzz testing to testmgr
   - Add panic_on_fail module parameter to testmgr
   - Use per-CPU struct instead multiple variables in scompress
   - Change verify API for akcipher

  Algorithms:
   - Convert x86 AEAD algorithms over to simd
   - Forbid 2-key 3DES in FIPS mode
   - Add EC-RDSA (GOST 34.10) algorithm

  Drivers:
   - Set output IV with ctr-aes in crypto4xx
   - Set output IV in rockchip
   - Fix potential length overflow with hashing in sun4i-ss
   - Fix computation error with ctr in vmx
   - Add SM4 protected keys support in ccree
   - Remove long-broken mxc-scc driver
   - Add rfc4106(gcm(aes)) cipher support in cavium/nitrox"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (179 commits)
  crypto: ccree - use a proper le32 type for le32 val
  crypto: ccree - remove set but not used variable 'du_size'
  crypto: ccree - Make cc_sec_disable static
  crypto: ccree - fix spelling mistake "protedcted" -> "protected"
  crypto: caam/qi2 - generate hash keys in-place
  crypto: caam/qi2 - fix DMA mapping of stack memory
  crypto: caam/qi2 - fix zero-length buffer DMA mapping
  crypto: stm32/cryp - update to return iv_out
  crypto: stm32/cryp - remove request mutex protection
  crypto: stm32/cryp - add weak key check for DES
  crypto: atmel - remove set but not used variable 'alg_name'
  crypto: picoxcell - Use dev_get_drvdata()
  crypto: crypto4xx - get rid of redundant using_sd variable
  crypto: crypto4xx - use sync skcipher for fallback
  crypto: crypto4xx - fix cfb and ofb "overran dst buffer" issues
  crypto: crypto4xx - fix ctr-aes missing output IV
  crypto: ecrdsa - select ASN1 and OID_REGISTRY for EC-RDSA
  crypto: ux500 - use ccflags-y instead of CFLAGS_<basename>.o
  crypto: ccree - handle tee fips error during power management resume
  crypto: ccree - add function to handle cryptocell tee fips error
  ...
2019-05-06 20:15:06 -07:00
Jens Axboe 2d5abb9a1e bcache: make is_discard_enabled() static
It's not used outside this file.

Fixes: 631207314d ("bcache: fix failure in journal relplay")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-05-01 06:34:09 -06:00
Martin Wilck 940bc47178 dm mpath: always free attached_handler_name in parse_path()
Commit b592211c33 ("dm mpath: fix attached_handler_name leak and
dangling hw_handler_name pointer") fixed a memory leak for the case
where setup_scsi_dh() returns failure. But setup_scsi_dh may return
success and not "use" attached_handler_name if the
retain_attached_hwhandler flag is not set on the map. As setup_scsi_sh
properly "steals" the pointer by nullifying it, freeing it
unconditionally in parse_path() is safe.

Fixes: b592211c33 ("dm mpath: fix attached_handler_name leak and dangling hw_handler_name pointer")
Cc: stable@vger.kernel.org
Reported-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Martin Wilck <mwilck@suse.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-30 16:51:30 -04:00
Helen Koike 8e890c1ab1 dm init: fix max devices/targets checks
dm-init should allow up to DM_MAX_{DEVICES,TARGETS} for devices/targets,
and not DM_MAX_{DEVICES,TARGETS} - 1.

Fix the checks and also fix the error message when the number of devices
is surpassed.

Fixes: 6bbc923dfc ("dm: add support to directly boot to a mapped device")
Cc: stable@vger.kernel.org
Signed-off-by: Helen Koike <helen.koike@collabora.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-30 16:51:23 -04:00
Bryan Gurney e4f3fabd67 dm: add dust target
Add the dm-dust target, which simulates the behavior of bad sectors
at arbitrary locations, and the ability to enable the emulation of
the read failures at an arbitrary time.

This target behaves similarly to a linear target.  At a given time,
the user can send a message to the target to start failing read
requests on specific blocks.  When the failure behavior is enabled,
reads of blocks configured "bad" will fail with EIO.

Writes of blocks configured "bad" will result in the following:

1. Remove the block from the "bad block list".
2. Successfully complete the write.

After this point, the block will successfully contain the written
data, and will service reads and writes normally.  This emulates the
behavior of a "remapped sector" on a hard disk drive.

dm-dust provides logging of which blocks have been added or removed
to the "bad block list", as well as logging when a block has been
removed from the bad block list.  These messages can be used
alongside the messages from the driver using a dm-dust device to
analyze the driver's behavior when a read fails at a given time.

(This logging can be reduced via a "quiet" mode, if desired.)

NOTE: If the block size is larger than 512 bytes, only the first sector
of each "dust block" is detected.  Placing a limiting layer above a dust
target, to limit the minimum I/O size to the dust block size, will
ensure proper emulation of the given large block size.

Signed-off-by: Bryan Gurney <bgurney@redhat.com>
Co-developed-by: Joe Shimkus <jshimkus@redhat.com>
Co-developed-by: John Dorminy <jdorminy@redhat.com>
Co-developed-by: John Pittman <jpittman@redhat.com>
Co-developed-by: Thomas Jaskiewicz <tjaskiew@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-30 16:37:19 -04:00
Christoph Hellwig 2b070cfe58 block: remove the i argument to bio_for_each_segment_all
We only have two callers that need the integer loop iterator, and they
can easily maintain it themselves.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Acked-by: David Sterba <dsterba@suse.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Acked-by: Coly Li <colyli@suse.de>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-30 09:26:13 -06:00
Christoph Hellwig f936b06ae5 bcache: clean up do_btree_node_write a bit
Use a variable containing the buffer address instead of the to be
removed integer iterator from bio_for_each_segment_all.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Acked-by: Coly Li <colyli@suse.de>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-30 09:26:11 -06:00
Coly Li cdca22bcbc bcache: remove redundant LIST_HEAD(journal) from run_cache_set()
Commit 95f18c9d13 ("bcache: avoid potential memleak of list of
journal_replay(s) in the CACHE_SYNC branch of run_cache_set") forgets
to remove the original define of LIST_HEAD(journal), which makes
the change no take effect. This patch removes redundant variable
LIST_HEAD(journal) from run_cache_set(), to make Shenghui's fix
working.

Fixes: 95f18c9d13 ("bcache: avoid potential memleak of list of journal_replay(s) in the CACHE_SYNC branch of run_cache_set")
Reported-by: Juha Aatrokoski <juha.aatrokoski@aalto.fi>
Cc: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-30 08:20:46 -06:00
Thomas Gleixner be9c52ed84 dm persistent data: Simplify stack trace handling
Replace the indirection through struct stack_trace with an invocation of
the storage array based interface. This results in less storage space and
indirection.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: dm-devel@redhat.com
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
Cc: David Rientjes <rientjes@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: kasan-dev@googlegroups.com
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: linux-btrfs@vger.kernel.org
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: linux-arch@vger.kernel.org
Link: https://lkml.kernel.org/r/20190425094802.533968922@linutronix.de
2019-04-29 12:37:52 +02:00
Thomas Gleixner 741b58f3e2 dm bufio: Simplify stack trace retrieval
Replace the indirection through struct stack_trace with an invocation of
the storage array based interface.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: dm-devel@redhat.com
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
Cc: David Rientjes <rientjes@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: kasan-dev@googlegroups.com
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: linux-btrfs@vger.kernel.org
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: linux-arch@vger.kernel.org
Link: https://lkml.kernel.org/r/20190425094802.446326191@linutronix.de
2019-04-29 12:37:52 +02:00
Mikulas Patocka f8011d3344 dm writecache: avoid unnecessary lookups in writecache_find_entry()
This is a small optimization in writecache_find_entry().

If we go past the condition "if (unlikely(!node))", we can be certain that
there is no entry in the tree that has the block equal to the "block"
variable.

Consequently, we can return the next entry directly, we don't need to go
to the second part of the function that finds the entry with lowest or
highest seq number that matches the "block" variable.

Also, add some whitespace and cleanup needless braces.

Suggested-by: Huaisheng Ye <yehs1@lenovo.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-26 11:48:03 -04:00
Huaisheng Ye 08a8e80462 dm writecache: remove unused member page_offset in writeback_struct
The stucture member page_offset in writeback_struct never has been
used actually. Remove it.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-26 11:32:50 -04:00
Mikulas Patocka 81bc6d150a dm delay: fix a crash when invalid device is specified
When the target line contains an invalid device, delay_ctr() will call
delay_dtr() with NULL workqueue.  Attempting to destroy the NULL
workqueue causes a crash.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-26 11:29:32 -04:00
Peng Wang 514cf4f881 dm: only initialize md->dax_dev if CONFIG_DAX_DRIVER is enabled
md->dax_dev defaults to NULL and there is no need to initialize it
if CONFIG_DAX_DRIVER is disabled.

Signed-off-by: Peng Wang <rocking@whu.edu.cn>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-26 11:28:17 -04:00
Yufen Yu 5de719e3d0 dm mpath: fix missing call of path selector type->end_io
After commit 396eaf21ee ("blk-mq: improve DM's blk-mq IO merging via
blk_insert_cloned_request feedback"), map_request() will requeue the tio
when issued clone request return BLK_STS_RESOURCE or BLK_STS_DEV_RESOURCE.

Thus, if device driver status is error, a tio may be requeued multiple
times until the return value is not DM_MAPIO_REQUEUE.  That means
type->start_io may be called multiple times, while type->end_io is only
called when IO complete.

In fact, even without commit 396eaf21ee, setup_clone() failure can
also cause tio requeue and associated missed call to type->end_io.

The service-time path selector selects path based on in_flight_size,
which is increased by st_start_io() and decreased by st_end_io().
Missed calls to st_end_io() can lead to in_flight_size count error and
will cause the selector to make the wrong choice.  In addition,
queue-length path selector will also be affected.

To fix the problem, call type->end_io in ->release_clone_rq before tio
requeue.  map_info is passed to ->release_clone_rq() for map_request()
error path that result in requeue.

Fixes: 396eaf21ee ("blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback")
Cc: stable@vger.kernl.org
Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-25 15:38:52 -04:00
Eric Biggers 877b5691f2 crypto: shash - remove shash_desc::flags
The flags field in 'struct shash_desc' never actually does anything.
The only ostensibly supported flag is CRYPTO_TFM_REQ_MAY_SLEEP.
However, no shash algorithm ever sleeps, making this flag a no-op.

With this being the case, inevitably some users who can't sleep wrongly
pass MAY_SLEEP.  These would all need to be fixed if any shash algorithm
actually started sleeping.  For example, the shash_ahash_*() functions,
which wrap a shash algorithm with the ahash API, pass through MAY_SLEEP
from the ahash API to the shash API.  However, the shash functions are
called under kmap_atomic(), so actually they're assumed to never sleep.

Even if it turns out that some users do need preemption points while
hashing large buffers, we could easily provide a helper function
crypto_shash_update_large() which divides the data into smaller chunks
and calls crypto_shash_update() and cond_resched() for each chunk.  It's
not necessary to have a flag in 'struct shash_desc', nor is it necessary
to make individual shash algorithms aware of this at all.

Therefore, remove shash_desc::flags, and document that the
crypto_shash_*() functions can be called from any context.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2019-04-25 15:38:12 +08:00
Shenghui Wang 95f18c9d13 bcache: avoid potential memleak of list of journal_replay(s) in the CACHE_SYNC branch of run_cache_set
In the CACHE_SYNC branch of run_cache_set(), LIST_HEAD(journal) is used
to collect journal_replay(s) and filled by bch_journal_read().

If all goes well, bch_journal_replay() will release the list of
jounal_replay(s) at the end of the branch.

If something goes wrong, code flow will jump to the label "err:" and leave
the list unreleased.

This patch will release the list of journal_replay(s) in the case of
error detected.

v1 -> v2:
* Move the release code to the location after label 'err:' to
  simply the change.

Signed-off-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:29 -06:00
Shenghui Wang f16277ca20 bcache: fix wrong usage use-after-freed on keylist in out_nocoalesce branch of btree_gc_coalesce
Elements of keylist should be accessed before the list is freed.
Move bch_keylist_free() calling after the while loop to avoid wrong
content accessed.

Signed-off-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:29 -06:00
Tang Junhui 631207314d bcache: fix failure in journal relplay
journal replay failed with messages:
Sep 10 19:10:43 ceph kernel: bcache: error on
bb379a64-e44e-4812-b91d-a5599871a3b1: bcache: journal entries
2057493-2057567 missing! (replaying 2057493-2076601), disabling
caching

The reason is in journal_reclaim(), when discard is enabled, we send
discard command and reclaim those journal buckets whose seq is old
than the last_seq_now, but before we write a journal with last_seq_now,
the machine is restarted, so the journal with the last_seq_now is not
written to the journal bucket, and the last_seq_wrote in the newest
journal is old than last_seq_now which we expect to be, so when we doing
replay, journals from last_seq_wrote to last_seq_now are missing.

It's hard to write a journal immediately after journal_reclaim(),
and it harmless if those missed journal are caused by discarding
since those journals are already wrote to btree node. So, if miss
seqs are started from the beginning journal, we treat it as normal,
and only print a message to show the miss journal, and point out
it maybe caused by discarding.

Patch v2 add a judgement condition to ignore the missed journal
only when discard enabled as Coly suggested.

(Coly Li: rebase the patch with other changes in bch_journal_replay())

Signed-off-by: Tang Junhui <tang.junhui.linux@gmail.com>
Tested-by: Dennis Schridde <devurandom@gmx.net>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:28 -06:00
Coly Li eb8cbb6df3 bcache: improve bcache_reboot()
This patch tries to release mutex bch_register_lock early, to give
chance to stop cache set and bcache device early.

This patch also expends time out of stopping all bcache device from
2 seconds to 10 seconds, because stopping writeback rate update worker
may delay for 5 seconds, 2 seconds is not enough.

After this patch applied, stopping bcache devices during system reboot
or shutdown is very hard to be observed any more.

Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:28 -06:00
Coly Li 63d63b51d7 bcache: add comments for closure_fn to be called in closure_queue()
Add code comments to explain which call back function might be called
for the closure_queue(). This is an effort to make code to be more
understandable for readers.

Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:28 -06:00
Coly Li bb6d355c2a bcache: Add comments for blkdev_put() in registration code path
Add comments to explain why in register_bcache() blkdev_put() won't
be called in two location. Add comments to explain why blkdev_put()
must be called in register_cache() when cache_alloc() failed.

Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:28 -06:00
Coly Li 88c12d42d2 bcache: add error check for calling register_bdev()
This patch adds return value to register_bdev(). Then if failure happens
inside register_bdev(), its caller register_bcache() may detect and
handle the failure more properly.

Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:28 -06:00
Coly Li 68d10e6979 bcache: return error immediately in bch_journal_replay()
When failure happens inside bch_journal_replay(), calling
cache_set_err_on() and handling the failure in async way is not a good
idea. Because after bch_journal_replay() returns, registering code will
continue to execute following steps, and unregistering code triggered
by cache_set_err_on() is running in same time. First it is unnecessary
to handle failure and unregister cache set in an async way, second there
might be potential race condition to run register and unregister code
for same cache set.

So in this patch, if failure happens in bch_journal_replay(), we don't
call cache_set_err_on(), and just print out the same error message to
kernel message buffer, then return -EIO immediately caller. Then caller
can detect such failure and handle it in synchrnozied way.

Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:28 -06:00
Coly Li 2d17456eb1 bcache: add comments for kobj release callback routine
Bcache has several routines to release resources in implicit way, they
are called when the associated kobj released. This patch adds code
comments to notice when and which release callback will be called,
- When dc->disk.kobj released:
  void bch_cached_dev_release(struct kobject *kobj)
- When d->kobj released:
  void bch_flash_dev_release(struct kobject *kobj)
- When c->kobj released:
  void bch_cache_set_release(struct kobject *kobj)
- When ca->kobj released
  void bch_cache_release(struct kobject *kobj)

Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:28 -06:00
Coly Li ce3e4cfb59 bcache: add failure check to run_cache_set() for journal replay
Currently run_cache_set() has no return value, if there is failure in
bch_journal_replay(), the caller of run_cache_set() has no idea about
such failure and just continue to execute following code after
run_cache_set().  The internal failure is triggered inside
bch_journal_replay() and being handled in async way. This behavior is
inefficient, while failure handling inside bch_journal_replay(), cache
register code is still running to start the cache set. Registering and
unregistering code running as same time may introduce some rare race
condition, and make the code to be more hard to be understood.

This patch adds return value to run_cache_set(), and returns -EIO if
bch_journal_rreplay() fails. Then caller of run_cache_set() may detect
such failure and stop registering code flow immedidately inside
register_cache_set().

If journal replay fails, run_cache_set() can report error immediately
to register_cache_set(). This patch makes the failure handling for
bch_journal_replay() be in synchronized way, easier to understand and
debug, and avoid poetential race condition for register-and-unregister
in same time.

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:28 -06:00
Coly Li 1bee2addc0 bcache: never set KEY_PTRS of journal key to 0 in journal_reclaim()
In journal_reclaim() ja->cur_idx of each cache will be update to
reclaim available journal buckets. Variable 'int n' is used to count how
many cache is successfully reclaimed, then n is set to c->journal.key
by SET_KEY_PTRS(). Later in journal_write_unlocked(), a for_each_cache()
loop will write the jset data onto each cache.

The problem is, if all jouranl buckets on each cache is full, the
following code in journal_reclaim(),

529 for_each_cache(ca, c, iter) {
530       struct journal_device *ja = &ca->journal;
531       unsigned int next = (ja->cur_idx + 1) % ca->sb.njournal_buckets;
532
533       /* No space available on this device */
534       if (next == ja->discard_idx)
535               continue;
536
537       ja->cur_idx = next;
538       k->ptr[n++] = MAKE_PTR(0,
539                         bucket_to_sector(c, ca->sb.d[ja->cur_idx]),
540                         ca->sb.nr_this_dev);
541 }
542
543 bkey_init(k);
544 SET_KEY_PTRS(k, n);

If there is no available bucket to reclaim, the if() condition at line
534 will always true, and n remains 0. Then at line 544, SET_KEY_PTRS()
will set KEY_PTRS field of c->journal.key to 0.

Setting KEY_PTRS field of c->journal.key to 0 is wrong. Because in
journal_write_unlocked() the journal data is written in following loop,

649	for (i = 0; i < KEY_PTRS(k); i++) {
650-671		submit journal data to cache device
672	}

If KEY_PTRS field is set to 0 in jouranl_reclaim(), the journal data
won't be written to cache device here. If system crahed or rebooted
before bkeys of the lost journal entries written into btree nodes, data
corruption will be reported during bcache reload after rebooting the
system.

Indeed there is only one cache in a cache set, there is no need to set
KEY_PTRS field in journal_reclaim() at all. But in order to keep the
for_each_cache() logic consistent for now, this patch fixes the above
problem by not setting 0 KEY_PTRS of journal key, if there is no bucket
available to reclaim.

Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:27 -06:00
Coly Li 14215ee01f bcache: move definition of 'int ret' out of macro read_bucket()
'int ret' is defined as a local variable inside macro read_bucket().
Since this macro is called multiple times, and following patches will
use a 'int ret' variable in bch_journal_read(), this patch moves
definition of 'int ret' from macro read_bucket() to range of function
bch_journal_read().

Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:27 -06:00
Liang Chen a4b732a248 bcache: fix a race between cache register and cacheset unregister
There is a race between cache device register and cache set unregister.
For an already registered cache device, register_bcache will call
bch_is_open to iterate through all cachesets and check every cache
there. The race occurs if cache_set_free executes at the same time and
clears the caches right before ca is dereferenced in bch_is_open_cache.
To close the race, let's make sure the clean up work is protected by
the bch_register_lock as well.

This issue can be reproduced as follows,
while true; do echo /dev/XXX> /sys/fs/bcache/register ; done&
while true; do echo 1> /sys/block/XXX/bcache/set/unregister ; done &

and results in the following oops,

[  +0.000053] BUG: unable to handle kernel NULL pointer dereference at 0000000000000998
[  +0.000457] #PF error: [normal kernel read fault]
[  +0.000464] PGD 800000003ca9d067 P4D 800000003ca9d067 PUD 3ca9c067 PMD 0
[  +0.000388] Oops: 0000 [#1] SMP PTI
[  +0.000269] CPU: 1 PID: 3266 Comm: bash Not tainted 5.0.0+ #6
[  +0.000346] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.fc28 04/01/2014
[  +0.000472] RIP: 0010:register_bcache+0x1829/0x1990 [bcache]
[  +0.000344] Code: b0 48 83 e8 50 48 81 fa e0 e1 10 c0 0f 84 a9 00 00 00 48 89 c6 48 89 ca 0f b7 ba 54 04 00 00 4c 8b 82 60 0c 00 00 85 ff 74 2f <49> 3b a8 98 09 00 00 74 4e 44 8d 47 ff 31 ff 49 c1 e0 03 eb 0d
[  +0.000839] RSP: 0018:ffff92ee804cbd88 EFLAGS: 00010202
[  +0.000328] RAX: ffffffffc010e190 RBX: ffff918b5c6b5000 RCX: ffff918b7d8e0000
[  +0.000399] RDX: ffff918b7d8e0000 RSI: ffffffffc010e190 RDI: 0000000000000001
[  +0.000398] RBP: ffff918b7d318340 R08: 0000000000000000 R09: ffffffffb9bd2d7a
[  +0.000385] R10: ffff918b7eb253c0 R11: ffffb95980f51200 R12: ffffffffc010e1a0
[  +0.000411] R13: fffffffffffffff2 R14: 000000000000000b R15: ffff918b7e232620
[  +0.000384] FS:  00007f955bec2740(0000) GS:ffff918b7eb00000(0000) knlGS:0000000000000000
[  +0.000420] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  +0.000801] CR2: 0000000000000998 CR3: 000000003cad6000 CR4: 00000000001406e0
[  +0.000837] Call Trace:
[  +0.000682]  ? _cond_resched+0x10/0x20
[  +0.000691]  ? __kmalloc+0x131/0x1b0
[  +0.000710]  kernfs_fop_write+0xfa/0x170
[  +0.000733]  __vfs_write+0x2e/0x190
[  +0.000688]  ? inode_security+0x10/0x30
[  +0.000698]  ? selinux_file_permission+0xd2/0x120
[  +0.000752]  ? security_file_permission+0x2b/0x100
[  +0.000753]  vfs_write+0xa8/0x1a0
[  +0.000676]  ksys_write+0x4d/0xb0
[  +0.000699]  do_syscall_64+0x3a/0xf0
[  +0.000692]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:27 -06:00
George Spelvin 3a3947271c bcache: Clean up bch_get_congested()
There are a few nits in this function.  They could in theory all
be separate patches, but that's probably taking small commits
too far.

1) I added a brief comment saying what it does.

2) I like to declare pointer parameters "const" where possible
   for documentation reasons.

3) It uses bitmap_weight(&rand, BITS_PER_LONG) to compute the Hamming
weight of a 32-bit random number (giving a random integer with
mean 16 and variance 8).  Passing by reference in a 64-bit variable
is silly; just use hweight32().

4) Its helper function fract_exp_two is unnecessarily tangled.
Gcc can optimize the multiply by (1 << x) to a shift, but it can
be written in a much more straightforward way at the cost of one
more bit of internal precision.  Some analysis reveals that this
bit is always available.

This shrinks the object code for fract_exp_two(x, 6) from 23 bytes:

0000000000000000 <foo1>:
   0:   89 f9                   mov    %edi,%ecx
   2:   c1 e9 06                shr    $0x6,%ecx
   5:   b8 01 00 00 00          mov    $0x1,%eax
   a:   d3 e0                   shl    %cl,%eax
   c:   83 e7 3f                and    $0x3f,%edi
   f:   d3 e7                   shl    %cl,%edi
  11:   c1 ef 06                shr    $0x6,%edi
  14:   01 f8                   add    %edi,%eax
  16:   c3                      retq

To 19:

0000000000000017 <foo2>:
  17:   89 f8                   mov    %edi,%eax
  19:   83 e0 3f                and    $0x3f,%eax
  1c:   83 c0 40                add    $0x40,%eax
  1f:   89 f9                   mov    %edi,%ecx
  21:   c1 e9 06                shr    $0x6,%ecx
  24:   d3 e0                   shl    %cl,%eax
  26:   c1 e8 06                shr    $0x6,%eax
  29:   c3                      retq

(Verified with 0 <= frac_bits <= 8, 0 <= x < 16<<frac_bits;
both versions produce the same output.)

5) And finally, the call to bch_get_congested() in check_should_bypass()
is separated from the use of the value by multiple tests which
could moot the need to compute it.  Move the computation down to
where it's needed.  This also saves a local register to hold the
computed value.

Signed-off-by: George Spelvin <lkml@sdf.org>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-24 10:56:27 -06:00