1. 19 Mar, 2018 7 commits
    • Tang Junhui's avatar
      bcache: fix incorrect sysfs output value of strip size · 688892b3
      Tang Junhui authored
      Stripe size is shown as zero when no strip in back end device:
      [root@ceph132 ~]# cat /sys/block/sdd/bcache/stripe_size
      0.0k
      
      Actually it should be 1T Bytes (1 << 31 sectors), but in sysfs
      interface, stripe_size was changed from sectors to bytes, and move
      9 bits left, so the 32 bits variable overflows.
      
      This patch change the variable to a 64 bits type before moving bits.
      Signed-off-by: default avatarTang Junhui <tang.junhui@zte.com.cn>
      Reviewed-by: default avatarMichael Lyle <mlyle@lyle.org>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      688892b3
    • Tang Junhui's avatar
      bcache: fix inaccurate io state for detached bcache devices · bc082a55
      Tang Junhui authored
      When we run IO in a detached device,  and run iostat to shows IO status,
      normally it will show like bellow (Omitted some fields):
      Device: ... avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
      sdd        ... 15.89     0.53    1.82    0.20    2.23   1.81  52.30
      bcache0    ... 15.89   115.42    0.00    0.00    0.00   2.40  69.60
      but after IO stopped, there are still very big avgqu-sz and %util
      values as bellow:
      Device: ... avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
      bcache0   ...      0   5326.32    0.00    0.00    0.00   0.00 100.10
      
      The reason for this issue is that, only generic_start_io_acct() called
      and no generic_end_io_acct() called for detached device in
      cached_dev_make_request(). See the code:
      //start generic_start_io_acct()
      generic_start_io_acct(q, rw, bio_sectors(bio), &d->disk->part0);
      if (cached_dev_get(dc)) {
      	//will callback generic_end_io_acct()
      }
      else {
      	//will not call generic_end_io_acct()
      }
      
      This patch calls generic_end_io_acct() in the end of IO for detached
      devices, so we can show IO state correctly.
      
      (Modified to use GFP_NOIO in kzalloc() by Coly Li)
      
      Changelog:
      v2: fix typo.
      v1: the initial version.
      Signed-off-by: default avatarTang Junhui <tang.junhui@zte.com.cn>
      Reviewed-by: default avatarColy Li <colyli@suse.de>
      Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
      Reviewed-by: default avatarMichael Lyle <mlyle@lyle.org>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      bc082a55
    • Coly Li's avatar
      bcache: add stop_when_cache_set_failed option to backing device · 7e027ca4
      Coly Li authored
      When there are too many I/O errors on cache device, current bcache code
      will retire the whole cache set, and detach all bcache devices. But the
      detached bcache devices are not stopped, which is problematic when bcache
      is in writeback mode.
      
      If the retired cache set has dirty data of backing devices, continue
      writing to bcache device will write to backing device directly. If the
      LBA of write request has a dirty version cached on cache device, next time
      when the cache device is re-registered and backing device re-attached to
      it again, the stale dirty data on cache device will be written to backing
      device, and overwrite latest directly written data. This situation causes
      a quite data corruption.
      
      But we cannot simply stop all attached bcache devices when the cache set is
      broken or disconnected. For example, use bcache to accelerate performance
      of an email service. In such workload, if cache device is broken but no
      dirty data lost, keep the bcache device alive and permit email service
      continue to access user data might be a better solution for the cache
      device failure.
      
      Nix <nix@esperi.org.uk> points out the issue and provides the above example
      to explain why it might be necessary to not stop bcache device for broken
      cache device. Pavel Goran <via-bcache@pvgoran.name> provides a brilliant
      suggestion to provide "always" and "auto" options to per-cached device
      sysfs file stop_when_cache_set_failed. If cache set is retiring and the
      backing device has no dirty data on cache, it should be safe to keep the
      bcache device alive. In this case, if stop_when_cache_set_failed is set to
      "auto", the device failure handling code will not stop this bcache device
      and permit application to access the backing device with a unattached
      bcache device.
      
      Changelog:
      [mlyle: edited to not break string constants across lines]
      v3: fix typos pointed out by Nix.
      v2: change option values of stop_when_cache_set_failed from 1/0 to
          "auto"/"always".
      v1: initial version, stop_when_cache_set_failed can be 0 (not stop) or 1
          (always stop).
      Signed-off-by: default avatarColy Li <colyli@suse.de>
      Reviewed-by: default avatarMichael Lyle <mlyle@lyle.org>
      Signed-off-by: default avatarMichael Lyle <mlyle@lyle.org>
      Cc: Nix <nix@esperi.org.uk>
      Cc: Pavel Goran <via-bcache@pvgoran.name>
      Cc: Junhui Tang <tang.junhui@zte.com.cn>
      Cc: Hannes Reinecke <hare@suse.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      7e027ca4
    • Coly Li's avatar
      bcache: add CACHE_SET_IO_DISABLE to struct cache_set flags · 771f393e
      Coly Li authored
      When too many I/Os failed on cache device, bch_cache_set_error() is called
      in the error handling code path to retire whole problematic cache set. If
      new I/O requests continue to come and take refcount dc->count, the cache
      set won't be retired immediately, this is a problem.
      
      Further more, there are several kernel thread and self-armed kernel work
      may still running after bch_cache_set_error() is called. It needs to wait
      quite a while for them to stop, or they won't stop at all. They also
      prevent the cache set from being retired.
      
      The solution in this patch is, to add per cache set flag to disable I/O
      request on this cache and all attached backing devices. Then new coming I/O
      requests can be rejected in *_make_request() before taking refcount, kernel
      threads and self-armed kernel worker can stop very fast when flags bit
      CACHE_SET_IO_DISABLE is set.
      
      Because bcache also do internal I/Os for writeback, garbage collection,
      bucket allocation, journaling, this kind of I/O should be disabled after
      bch_cache_set_error() is called. So closure_bio_submit() is modified to
      check whether CACHE_SET_IO_DISABLE is set on cache_set->flags. If set,
      closure_bio_submit() will set bio->bi_status to BLK_STS_IOERR and
      return, generic_make_request() won't be called.
      
      A sysfs interface is also added to set or clear CACHE_SET_IO_DISABLE bit
      from cache_set->flags, to disable or enable cache set I/O for debugging. It
      is helpful to trigger more corner case issues for failed cache device.
      
      Changelog
      v4, add wait_for_kthread_stop(), and call it before exits writeback and gc
          kernel threads.
      v3, change CACHE_SET_IO_DISABLE from 4 to 3, since it is bit index.
          remove "bcache: " prefix when printing out kernel message.
      v2, more changes by previous review,
      - Use CACHE_SET_IO_DISABLE of cache_set->flags, suggested by Junhui.
      - Check CACHE_SET_IO_DISABLE in bch_btree_gc() to stop a while-loop, this
        is reported and inspired from origal patch of Pavel Vazharov.
      v1, initial version.
      Signed-off-by: default avatarColy Li <colyli@suse.de>
      Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
      Reviewed-by: default avatarMichael Lyle <mlyle@lyle.org>
      Cc: Junhui Tang <tang.junhui@zte.com.cn>
      Cc: Michael Lyle <mlyle@lyle.org>
      Cc: Pavel Vazharov <freakpv@gmail.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      771f393e
    • Coly Li's avatar
      bcache: stop dc->writeback_rate_update properly · 3fd47bfe
      Coly Li authored
      struct delayed_work writeback_rate_update in struct cache_dev is a delayed
      worker to call function update_writeback_rate() in period (the interval is
      defined by dc->writeback_rate_update_seconds).
      
      When a metadate I/O error happens on cache device, bcache error handling
      routine bch_cache_set_error() will call bch_cache_set_unregister() to
      retire whole cache set. On the unregister code path, this delayed work is
      stopped by calling cancel_delayed_work_sync(&dc->writeback_rate_update).
      
      dc->writeback_rate_update is a special delayed work from others in bcache.
      In its routine update_writeback_rate(), this delayed work is re-armed
      itself. That means when cancel_delayed_work_sync() returns, this delayed
      work can still be executed after several seconds defined by
      dc->writeback_rate_update_seconds.
      
      The problem is, after cancel_delayed_work_sync() returns, the cache set
      unregister code path will continue and release memory of struct cache set.
      Then the delayed work is scheduled to run, __update_writeback_rate()
      will reference the already released cache_set memory, and trigger a NULL
      pointer deference fault.
      
      This patch introduces two more bcache device flags,
      - BCACHE_DEV_WB_RUNNING
        bit set:  bcache device is in writeback mode and running, it is OK for
                  dc->writeback_rate_update to re-arm itself.
        bit clear:bcache device is trying to stop dc->writeback_rate_update,
                  this delayed work should not re-arm itself and quit.
      - BCACHE_DEV_RATE_DW_RUNNING
        bit set:  routine update_writeback_rate() is executing.
        bit clear: routine update_writeback_rate() quits.
      
      This patch also adds a function cancel_writeback_rate_update_dwork() to
      wait for dc->writeback_rate_update quits before cancel it by calling
      cancel_delayed_work_sync(). In order to avoid a deadlock by unexpected
      quit dc->writeback_rate_update, after time_out seconds this function will
      give up and continue to call cancel_delayed_work_sync().
      
      And here I explain how this patch stops self re-armed delayed work properly
      with the above stuffs.
      
      update_writeback_rate() sets BCACHE_DEV_RATE_DW_RUNNING at its beginning
      and clears BCACHE_DEV_RATE_DW_RUNNING at its end. Before calling
      cancel_writeback_rate_update_dwork() clear flag BCACHE_DEV_WB_RUNNING.
      
      Before calling cancel_delayed_work_sync() wait utill flag
      BCACHE_DEV_RATE_DW_RUNNING is clear. So when calling
      cancel_delayed_work_sync(), dc->writeback_rate_update must be already re-
      armed, or quite by seeing BCACHE_DEV_WB_RUNNING cleared. In both cases
      delayed work routine update_writeback_rate() won't be executed after
      cancel_delayed_work_sync() returns.
      
      Inside update_writeback_rate() before calling schedule_delayed_work(), flag
      BCACHE_DEV_WB_RUNNING is checked before. If this flag is cleared, it means
      someone is about to stop the delayed work. Because flag
      BCACHE_DEV_RATE_DW_RUNNING is set already and cancel_delayed_work_sync()
      has to wait for this flag to be cleared, we don't need to worry about race
      condition here.
      
      If update_writeback_rate() is scheduled to run after checking
      BCACHE_DEV_RATE_DW_RUNNING and before calling cancel_delayed_work_sync()
      in cancel_writeback_rate_update_dwork(), it is also safe. Because at this
      moment BCACHE_DEV_WB_RUNNING is cleared with memory barrier. As I mentioned
      previously, update_writeback_rate() will see BCACHE_DEV_WB_RUNNING is clear
      and quit immediately.
      
      Because there are more dependences inside update_writeback_rate() to struct
      cache_set memory, dc->writeback_rate_update is not a simple self re-arm
      delayed work. After trying many different methods (e.g. hold dc->count, or
      use locks), this is the only way I can find which works to properly stop
      dc->writeback_rate_update delayed work.
      
      Changelog:
      v3: change values of BCACHE_DEV_WB_RUNNING and BCACHE_DEV_RATE_DW_RUNNING
          to bit index, for test_bit().
      v2: Try to fix the race issue which is pointed out by Junhui.
      v1: The initial version for review
      Signed-off-by: default avatarColy Li <colyli@suse.de>
      Reviewed-by: default avatarJunhui Tang <tang.junhui@zte.com.cn>
      Reviewed-by: default avatarMichael Lyle <mlyle@lyle.org>
      Cc: Michael Lyle <mlyle@lyle.org>
      Cc: Hannes Reinecke <hare@suse.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      3fd47bfe
    • Coly Li's avatar
      bcache: quit dc->writeback_thread when BCACHE_DEV_DETACHING is set · fadd94e0
      Coly Li authored
      In patch "bcache: fix cached_dev->count usage for bch_cache_set_error()",
      cached_dev_get() is called when creating dc->writeback_thread, and
      cached_dev_put() is called when exiting dc->writeback_thread. This
      modification works well unless people detach the bcache device manually by
          'echo 1 > /sys/block/bcache<N>/bcache/detach'
      Because this sysfs interface only calls bch_cached_dev_detach() which wakes
      up dc->writeback_thread but does not stop it. The reason is, before patch
      "bcache: fix cached_dev->count usage for bch_cache_set_error()", inside
      bch_writeback_thread(), if cache is not dirty after writeback,
      cached_dev_put() will be called here. And in cached_dev_make_request() when
      a new write request makes cache from clean to dirty, cached_dev_get() will
      be called there. Since we don't operate dc->count in these locations,
      refcount d->count cannot be dropped after cache becomes clean, and
      cached_dev_detach_finish() won't be called to detach bcache device.
      
      This patch fixes the issue by checking whether BCACHE_DEV_DETACHING is
      set inside bch_writeback_thread(). If this bit is set and cache is clean
      (no existing writeback_keys), break the while-loop, call cached_dev_put()
      and quit the writeback thread.
      
      Please note if cache is still dirty, even BCACHE_DEV_DETACHING is set the
      writeback thread should continue to perform writeback, this is the original
      design of manually detach.
      
      It is safe to do the following check without locking, let me explain why,
      +	if (!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) &&
      +	    (!atomic_read(&dc->has_dirty) || !dc->writeback_running)) {
      
      If the kenrel thread does not sleep and continue to run due to conditions
      are not updated in time on the running CPU core, it just consumes more CPU
      cycles and has no hurt. This should-sleep-but-run is safe here. We just
      focus on the should-run-but-sleep condition, which means the writeback
      thread goes to sleep in mistake while it should continue to run.
      1, First of all, no matter the writeback thread is hung or not,
         kthread_stop() from cached_dev_detach_finish() will wake up it and
         terminate by making kthread_should_stop() return true. And in normal
         run time, bit on index BCACHE_DEV_DETACHING is always cleared, the
         condition
      	!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)
         is always true and can be ignored as constant value.
      2, If one of the following conditions is true, the writeback thread should
         go to sleep,
         "!atomic_read(&dc->has_dirty)" or "!dc->writeback_running)"
         each of them independently controls the writeback thread should sleep or
         not, let's analyse them one by one.
      2.1 condition "!atomic_read(&dc->has_dirty)"
         If dc->has_dirty is set from 0 to 1 on another CPU core, bcache will
         call bch_writeback_queue() immediately or call bch_writeback_add() which
         indirectly calls bch_writeback_queue() too. In bch_writeback_queue(),
         wake_up_process(dc->writeback_thread) is called. It sets writeback
         thread's task state to TASK_RUNNING and following an implicit memory
         barrier, then tries to wake up the writeback thread.
         In writeback thread, its task state is set to TASK_INTERRUPTIBLE before
         doing the condition check. If other CPU core sets the TASK_RUNNING state
         after writeback thread setting TASK_INTERRUPTIBLE, the writeback thread
         will be scheduled to run very soon because its state is not
         TASK_INTERRUPTIBLE. If other CPU core sets the TASK_RUNNING state before
         writeback thread setting TASK_INTERRUPTIBLE, the implict memory barrier
         of wake_up_process() will make sure modification of dc->has_dirty on
         other CPU core is updated and observed on the CPU core of writeback
         thread. Therefore the condition check will correctly be false, and
         continue writeback code without sleeping.
      2.2 condition "!dc->writeback_running)"
         dc->writeback_running can be changed via sysfs file, every time it is
         modified, a following bch_writeback_queue() is alwasy called. So the
         change is always observed on the CPU core of writeback thread. If
         dc->writeback_running is changed from 0 to 1 on other CPU core, this
         condition check will observe the modification and allow writeback
         thread to continue to run without sleeping.
      Now we can see, even without a locking protection, multiple conditions
      check is safe here, no deadlock or process hang up will happen.
      
      I compose a separte patch because that patch "bcache: fix cached_dev->count
      usage for bch_cache_set_error()" already gets a "Reviewed-by:" from Hannes
      Reinecke. Also this fix is not trivial and good for a separate patch.
      Signed-off-by: default avatarColy Li <colyli@suse.de>
      Reviewed-by: default avatarMichael Lyle <mlyle@lyle.org>
      Cc: Hannes Reinecke <hare@suse.com>
      Cc: Huijun Tang <tang.junhui@zte.com.cn>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      fadd94e0
    • Coly Li's avatar
      bcache: fix cached_dev->count usage for bch_cache_set_error() · 804f3c69
      Coly Li authored
      When bcache metadata I/O fails, bcache will call bch_cache_set_error()
      to retire the whole cache set. The expected behavior to retire a cache
      set is to unregister the cache set, and unregister all backing device
      attached to this cache set, then remove sysfs entries of the cache set
      and all attached backing devices, finally release memory of structs
      cache_set, cache, cached_dev and bcache_device.
      
      In my testing when journal I/O failure triggered by disconnected cache
      device, sometimes the cache set cannot be retired, and its sysfs
      entry /sys/fs/bcache/<uuid> still exits and the backing device also
      references it. This is not expected behavior.
      
      When metadata I/O failes, the call senquence to retire whole cache set is,
              bch_cache_set_error()
              bch_cache_set_unregister()
              bch_cache_set_stop()
              __cache_set_unregister()     <- called as callback by calling
                                              clousre_queue(&c->caching)
              cache_set_flush()            <- called as a callback when refcount
                                              of cache_set->caching is 0
              cache_set_free()             <- called as a callback when refcount
                                              of catch_set->cl is 0
              bch_cache_set_release()      <- called as a callback when refcount
                                              of catch_set->kobj is 0
      
      I find if kernel thread bch_writeback_thread() quits while-loop when
      kthread_should_stop() is true and searched_full_index is false, clousre
      callback cache_set_flush() set by continue_at() will never be called. The
      result is, bcache fails to retire whole cache set.
      
      cache_set_flush() will be called when refcount of closure c->caching is 0,
      and in function bcache_device_detach() refcount of closure c->caching is
      released to 0 by clousre_put(). In metadata error code path, function
      bcache_device_detach() is called by cached_dev_detach_finish(). This is a
      callback routine being called when cached_dev->count is 0. This refcount
      is decreased by cached_dev_put().
      
      The above dependence indicates, cache_set_flush() will be called when
      refcount of cache_set->cl is 0, and refcount of cache_set->cl to be 0
      when refcount of cache_dev->count is 0.
      
      The reason why sometimes cache_dev->count is not 0 (when metadata I/O fails
      and bch_cache_set_error() called) is, in bch_writeback_thread(), refcount
      of cache_dev is not decreased properly.
      
      In bch_writeback_thread(), cached_dev_put() is called only when
      searched_full_index is true and cached_dev->writeback_keys is empty, a.k.a
      there is no dirty data on cache. In most of run time it is correct, but
      when bch_writeback_thread() quits the while-loop while cache is still
      dirty, current code forget to call cached_dev_put() before this kernel
      thread exits. This is why sometimes cache_set_flush() is not executed and
      cache set fails to be retired.
      
      The reason to call cached_dev_put() in bch_writeback_rate() is, when the
      cache device changes from clean to dirty, cached_dev_get() is called, to
      make sure during writeback operatiions both backing and cache devices
      won't be released.
      
      Adding following code in bch_writeback_thread() does not work,
         static int bch_writeback_thread(void *arg)
              }
      
      +       if (atomic_read(&dc->has_dirty))
      +               cached_dev_put()
      +
              return 0;
       }
      because writeback kernel thread can be waken up and start via sysfs entry:
              echo 1 > /sys/block/bcache<N>/bcache/writeback_running
      It is difficult to check whether backing device is dirty without race and
      extra lock. So the above modification will introduce potential refcount
      underflow in some conditions.
      
      The correct fix is, to take cached dev refcount when creating the kernel
      thread, and put it before the kernel thread exits. Then bcache does not
      need to take a cached dev refcount when cache turns from clean to dirty,
      or to put a cached dev refcount when cache turns from ditry to clean. The
      writeback kernel thread is alwasy safe to reference data structure from
      cache set, cache and cached device (because a refcount of cache device is
      taken for it already), and no matter the kernel thread is stopped by I/O
      errors or system reboot, cached_dev->count can always be used correctly.
      
      The patch is simple, but understanding how it works is quite complicated.
      
      Changelog:
      v2: set dc->writeback_thread to NULL in this patch, as suggested by Hannes.
      v1: initial version for review.
      Signed-off-by: default avatarColy Li <colyli@suse.de>
      Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
      Reviewed-by: default avatarMichael Lyle <mlyle@lyle.org>
      Cc: Michael Lyle <mlyle@lyle.org>
      Cc: Junhui Tang <tang.junhui@zte.com.cn>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      804f3c69
  2. 17 Mar, 2018 3 commits
  3. 16 Mar, 2018 2 commits
    • Joseph Qi's avatar
      blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir() · 4c699480
      Joseph Qi authored
      We've triggered a WARNING in blk_throtl_bio() when throttling writeback
      io, which complains blkg->refcnt is already 0 when calling blkg_get(),
      and then kernel crashes with invalid page request.
      After investigating this issue, we've found it is caused by a race
      between blkcg_bio_issue_check() and cgroup_rmdir(), which is described
      below:
      
      writeback kworker               cgroup_rmdir
                                        cgroup_destroy_locked
                                          kill_css
                                            css_killed_ref_fn
                                              css_killed_work_fn
                                                offline_css
                                                  blkcg_css_offline
        blkcg_bio_issue_check
          rcu_read_lock
          blkg_lookup
                                                    spin_trylock(q->queue_lock)
                                                    blkg_destroy
                                                    spin_unlock(q->queue_lock)
          blk_throtl_bio
          spin_lock_irq(q->queue_lock)
          ...
          spin_unlock_irq(q->queue_lock)
        rcu_read_unlock
      
      Since rcu can only prevent blkg from releasing when it is being used,
      the blkg->refcnt can be decreased to 0 during blkg_destroy() and schedule
      blkg release.
      Then trying to blkg_get() in blk_throtl_bio() will complains the WARNING.
      And then the corresponding blkg_put() will schedule blkg release again,
      which result in double free.
      This race is introduced by commit ae118896 ("blkcg: consolidate blkg
      creation in blkcg_bio_issue_check()"). Before this commit, it will
      lookup first and then try to lookup/create again with queue_lock. Since
      revive this logic is a bit drastic, so fix it by only offlining pd during
      blkcg_css_offline(), and move the rest destruction (especially
      blkg_put()) into blkcg_css_free(), which should be the right way as
      discussed.
      
      Fixes: ae118896 ("blkcg: consolidate blkg creation in blkcg_bio_issue_check()")
      Reported-by: default avatarJiufei Xue <jiufei.xue@linux.alibaba.com>
      Signed-off-by: default avatarJoseph Qi <joseph.qi@linux.alibaba.com>
      Acked-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      4c699480
    • Jonas Rabenstein's avatar
      block: sed-opal: fix u64 short atom length · 5f990d31
      Jonas Rabenstein authored
      The length must be given as bytes and not as 4 bit tuples.
      Reviewed-by: default avatarScott Bauer <scott.bauer@intel.com>
      Signed-off-by: default avatarJonas Rabenstein <jonas.rabenstein@studium.uni-erlangen.de>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      5f990d31
  4. 13 Mar, 2018 3 commits
  5. 12 Mar, 2018 2 commits
  6. 09 Mar, 2018 5 commits
    • Ross Zwisler's avatar
      MAINTAINERS: add coverage for drivers/block · fc9de9a5
      Ross Zwisler authored
      To help folks like me that use scripts/get_maintainer.pl.
      Signed-off-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      fc9de9a5
    • Bart Van Assche's avatar
      block: Suppress kernel-doc warnings triggered by blk-zoned.c · 56c4bddb
      Bart Van Assche authored
      Avoid that building with W=1 causes the kernel-doc tool to complain
      about undocumented function arguments for the blk-zoned.c source file.
      Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
      Cc: Christoph Hellwig <hch@lst.de>
      Cc: Damien Le Moal <damien.lemoal@wdc.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      56c4bddb
    • Maurizio Lombardi's avatar
      cdrom: do not call check_disk_change() inside cdrom_open() · 2bbea6e1
      Maurizio Lombardi authored
      when mounting an ISO filesystem sometimes (very rarely)
      the system hangs because of a race condition between two tasks.
      
      PID: 6766   TASK: ffff88007b2a6dd0  CPU: 0   COMMAND: "mount"
       #0 [ffff880078447ae0] __schedule at ffffffff8168d605
       #1 [ffff880078447b48] schedule_preempt_disabled at ffffffff8168ed49
       #2 [ffff880078447b58] __mutex_lock_slowpath at ffffffff8168c995
       #3 [ffff880078447bb8] mutex_lock at ffffffff8168bdef
       #4 [ffff880078447bd0] sr_block_ioctl at ffffffffa00b6818 [sr_mod]
       #5 [ffff880078447c10] blkdev_ioctl at ffffffff812fea50
       #6 [ffff880078447c70] ioctl_by_bdev at ffffffff8123a8b3
       #7 [ffff880078447c90] isofs_fill_super at ffffffffa04fb1e1 [isofs]
       #8 [ffff880078447da8] mount_bdev at ffffffff81202570
       #9 [ffff880078447e18] isofs_mount at ffffffffa04f9828 [isofs]
      #10 [ffff880078447e28] mount_fs at ffffffff81202d09
      #11 [ffff880078447e70] vfs_kern_mount at ffffffff8121ea8f
      #12 [ffff880078447ea8] do_mount at ffffffff81220fee
      #13 [ffff880078447f28] sys_mount at ffffffff812218d6
      #14 [ffff880078447f80] system_call_fastpath at ffffffff81698c49
          RIP: 00007fd9ea914e9a  RSP: 00007ffd5d9bf648  RFLAGS: 00010246
          RAX: 00000000000000a5  RBX: ffffffff81698c49  RCX: 0000000000000010
          RDX: 00007fd9ec2bc210  RSI: 00007fd9ec2bc290  RDI: 00007fd9ec2bcf30
          RBP: 0000000000000000   R8: 0000000000000000   R9: 0000000000000010
          R10: 00000000c0ed0001  R11: 0000000000000206  R12: 00007fd9ec2bc040
          R13: 00007fd9eb6b2380  R14: 00007fd9ec2bc210  R15: 00007fd9ec2bcf30
          ORIG_RAX: 00000000000000a5  CS: 0033  SS: 002b
      
      This task was trying to mount the cdrom.  It allocated and configured a
      super_block struct and owned the write-lock for the super_block->s_umount
      rwsem. While exclusively owning the s_umount lock, it called
      sr_block_ioctl and waited to acquire the global sr_mutex lock.
      
      PID: 6785   TASK: ffff880078720fb0  CPU: 0   COMMAND: "systemd-udevd"
       #0 [ffff880078417898] __schedule at ffffffff8168d605
       #1 [ffff880078417900] schedule at ffffffff8168dc59
       #2 [ffff880078417910] rwsem_down_read_failed at ffffffff8168f605
       #3 [ffff880078417980] call_rwsem_down_read_failed at ffffffff81328838
       #4 [ffff8800784179d0] down_read at ffffffff8168cde0
       #5 [ffff8800784179e8] get_super at ffffffff81201cc7
       #6 [ffff880078417a10] __invalidate_device at ffffffff8123a8de
       #7 [ffff880078417a40] flush_disk at ffffffff8123a94b
       #8 [ffff880078417a88] check_disk_change at ffffffff8123ab50
       #9 [ffff880078417ab0] cdrom_open at ffffffffa00a29e1 [cdrom]
      #10 [ffff880078417b68] sr_block_open at ffffffffa00b6f9b [sr_mod]
      #11 [ffff880078417b98] __blkdev_get at ffffffff8123ba86
      #12 [ffff880078417bf0] blkdev_get at ffffffff8123bd65
      #13 [ffff880078417c78] blkdev_open at ffffffff8123bf9b
      #14 [ffff880078417c90] do_dentry_open at ffffffff811fc7f7
      #15 [ffff880078417cd8] vfs_open at ffffffff811fc9cf
      #16 [ffff880078417d00] do_last at ffffffff8120d53d
      #17 [ffff880078417db0] path_openat at ffffffff8120e6b2
      #18 [ffff880078417e48] do_filp_open at ffffffff8121082b
      #19 [ffff880078417f18] do_sys_open at ffffffff811fdd33
      #20 [ffff880078417f70] sys_open at ffffffff811fde4e
      #21 [ffff880078417f80] system_call_fastpath at ffffffff81698c49
          RIP: 00007f29438b0c20  RSP: 00007ffc76624b78  RFLAGS: 00010246
          RAX: 0000000000000002  RBX: ffffffff81698c49  RCX: 0000000000000000
          RDX: 00007f2944a5fa70  RSI: 00000000000a0800  RDI: 00007f2944a5fa70
          RBP: 00007f2944a5f540   R8: 0000000000000000   R9: 0000000000000020
          R10: 00007f2943614c40  R11: 0000000000000246  R12: ffffffff811fde4e
          R13: ffff880078417f78  R14: 000000000000000c  R15: 00007f2944a4b010
          ORIG_RAX: 0000000000000002  CS: 0033  SS: 002b
      
      This task tried to open the cdrom device, the sr_block_open function
      acquired the global sr_mutex lock. The call to check_disk_change()
      then saw an event flag indicating a possible media change and tried
      to flush any cached data for the device.
      As part of the flush, it tried to acquire the super_block->s_umount
      lock associated with the cdrom device.
      This was the same super_block as created and locked by the previous task.
      
      The first task acquires the s_umount lock and then the sr_mutex_lock;
      the second task acquires the sr_mutex_lock and then the s_umount lock.
      
      This patch fixes the issue by moving check_disk_change() out of
      cdrom_open() and let the caller take care of it.
      Signed-off-by: default avatarMaurizio Lombardi <mlombard@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      2bbea6e1
    • Randy Dunlap's avatar
      Documentation/cdrom: fix German sharp s in LaTex · da5ff37c
      Randy Dunlap authored
      Apparently the LaTex abbreviation for the German "sharp s" (ß)
      (Unicode U+00DF) has changed from {\sz} to {\ss}.  With {\sz},
      I get this error at line 1016 (line number after another patch):
      
      ! Undefined control sequence.
      l.1016 ...nel~2.0.  Further thanks to Heiko Ei{\sz
                                                        }feldt,
      
      This is fixed by changing the {\sz} to {\ss}.
      Signed-off-by: default avatarRandy Dunlap <rdunlap@infradead.org>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      da5ff37c
    • Randy Dunlap's avatar
      Documentation/cdrom: update cdrom-standard.tex for kernel changes · 0a703c1f
      Randy Dunlap authored
      Documentation updates for Documentation/cdrom/cdrom-standard.tex:
      
      cdrom_device_ops:
      - add check_events() and generic_packet()
      
      cdrom_device_info:
      - add one 'const' modifier
      - correct some field descriptions
      - add some missing fields
      - drop 'kdev_t dev;' field
      
      Also drop <n_discs> sentence from documentation because it is not
      referenced anywhere in the kernel header or C files.
      Signed-off-by: default avatarRandy Dunlap <rdunlap@infradead.org>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      0a703c1f
  7. 08 Mar, 2018 11 commits
  8. 07 Mar, 2018 1 commit
  9. 06 Mar, 2018 1 commit
  10. 01 Mar, 2018 2 commits
    • Arnd Bergmann's avatar
      staging: rts5208: rename SG_END macro · b5d013bc
      Arnd Bergmann authored
      A change to the generic scatterlist code caused a conflict with
      the rtsx card reader driver:
      
      In file included from drivers/staging/rts5208/rtsx.h:180,
                       from drivers/staging/rts5208/rtsx.c:28:
      drivers/staging/rts5208/rtsx_chip.h:343: error: "SG_END" redefined [-Werror]
      
      This changes one instance of the driver to prefix SG_END and
      related constants.
      
      Fixes: 723fbf56 ("lib/scatterlist: Add SG_CHAIN and SG_END macros for LSB encodings")
      Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
      Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      b5d013bc
    • Arnd Bergmann's avatar
      misc: rtsx: rename SG_END macro · f16ee7c7
      Arnd Bergmann authored
      A change to the generic scatterlist code caused a conflict with
      the rtsx card reader driver:
      
      In file included from drivers/misc/cardreader/rtsx_pcr.c:32:
      include/linux/rtsx_pci.h:40: error: "SG_END" redefined [-Werror]
      
      This changes one instance of the driver to prefix SG_END and
      related constants.
      
      Fixes: 723fbf56 ("lib/scatterlist: Add SG_CHAIN and SG_END macros for LSB encodings")
      Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      f16ee7c7
  11. 28 Feb, 2018 3 commits
    • Bart Van Assche's avatar
      block: Fix a race between request queue removal and the block cgroup controller · a063057d
      Bart Van Assche authored
      Avoid that the following race can occur:
      
      blk_cleanup_queue()               blkcg_print_blkgs()
        spin_lock_irq(lock) (1)           spin_lock_irq(blkg->q->queue_lock) (2,5)
          q->queue_lock = &q->__queue_lock (3)
        spin_unlock_irq(lock) (4)
                                          spin_unlock_irq(blkg->q->queue_lock) (6)
      
      (1) take driver lock;
      (2) busy loop for driver lock;
      (3) override driver lock with internal lock;
      (4) unlock driver lock;
      (5) can take driver lock now;
      (6) but unlock internal lock.
      
      This change is safe because only the SCSI core and the NVME core keep
      a reference on a request queue after having called blk_cleanup_queue().
      Neither driver accesses any of the removed data structures between its
      blk_cleanup_queue() and blk_put_queue() calls.
      Reported-by: default avatarJoseph Qi <joseph.qi@linux.alibaba.com>
      Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
      Reviewed-by: default avatarJoseph Qi <joseph.qi@linux.alibaba.com>
      Cc: Jan Kara <jack@suse.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      a063057d
    • Bart Van Assche's avatar
      block: Fix a race between the cgroup code and request queue initialization · 498f6650
      Bart Van Assche authored
      Initialize the request queue lock earlier such that the following
      race can no longer occur:
      
      blk_init_queue_node()             blkcg_print_blkgs()
        blk_alloc_queue_node (1)
          q->queue_lock = &q->__queue_lock (2)
          blkcg_init_queue(q) (3)
                                          spin_lock_irq(blkg->q->queue_lock) (4)
        q->queue_lock = lock (5)
                                          spin_unlock_irq(blkg->q->queue_lock) (6)
      
      (1) allocate an uninitialized queue;
      (2) initialize queue_lock to its default internal lock;
      (3) initialize blkcg part of request queue, which will create blkg and
          then insert it to blkg_list;
      (4) traverse blkg_list and find the created blkg, and then take its
          queue lock, here it is the default *internal lock*;
      (5) *race window*, now queue_lock is overridden with *driver specified
          lock*;
      (6) now unlock *driver specified lock*, not the locked *internal lock*,
          unlock balance breaks.
      
      The changes in this patch are as follows:
      - Move the .queue_lock initialization from blk_init_queue_node() into
        blk_alloc_queue_node().
      - Only override the .queue_lock pointer for legacy queues because it
        is not useful for blk-mq queues to override this pointer.
      - For all all block drivers that initialize .queue_lock explicitly,
        change the blk_alloc_queue() call in the driver into a
        blk_alloc_queue_node() call and remove the explicit .queue_lock
        initialization. Additionally, initialize the spin lock that will
        be used as queue lock earlier if necessary.
      Reported-by: default avatarJoseph Qi <joseph.qi@linux.alibaba.com>
      Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
      Reviewed-by: default avatarJoseph 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: default avatarJens Axboe <axboe@kernel.dk>
      498f6650
    • Bart Van Assche's avatar
      block: Add 'lock' as third argument to blk_alloc_queue_node() · 5ee0524b
      Bart Van Assche authored
      This patch does not change any functionality.
      Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
      Reviewed-by: default avatarJoseph 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: default avatarJens Axboe <axboe@kernel.dk>
      5ee0524b