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  1. 18 12月, 2014 3 次提交
    • M
      dm thin: fix crash by initializing thin device's refcount and completion earlier · 2b94e896
      由 Marc Dionne 提交于 
      Commit 80e96c54 ("dm thin: do not allow thin device activation
while pool is suspended") delayed the initialization of a new thin
device's refcount and completion until after this new thin was added
to the pool's active_thins list and the pool lock is released.  This
opens a race with a worker thread that walks the list and calls
thin_get/put, noticing that the refcount goes to 0 and calling
complete, freezing up the system and giving the oops below:

 kernel: BUG: unable to handle kernel NULL pointer dereference at           (null)
 kernel: IP: [<ffffffff810d360b>] __wake_up_common+0x2b/0x90

 kernel: Call Trace:
 kernel: [<ffffffff810d3683>] __wake_up_locked+0x13/0x20
 kernel: [<ffffffff810d3dc7>] complete+0x37/0x50
 kernel: [<ffffffffa0595c50>] thin_put+0x20/0x30 [dm_thin_pool]
 kernel: [<ffffffffa059aab7>] do_worker+0x667/0x870 [dm_thin_pool]
 kernel: [<ffffffff816a8a4c>] ? __schedule+0x3ac/0x9a0
 kernel: [<ffffffff810b1aef>] process_one_work+0x14f/0x400
 kernel: [<ffffffff810b206b>] worker_thread+0x6b/0x490
 kernel: [<ffffffff810b2000>] ? rescuer_thread+0x260/0x260
 kernel: [<ffffffff810b6a7b>] kthread+0xdb/0x100
 kernel: [<ffffffff810b69a0>] ? kthread_create_on_node+0x170/0x170
 kernel: [<ffffffff816ad7ec>] ret_from_fork+0x7c/0xb0
 kernel: [<ffffffff810b69a0>] ? kthread_create_on_node+0x170/0x170

Set the thin device's initial refcount and initialize the completion
before adding it to the pool's active_thins list in thin_ctr().
Signed-off-by: NMarc Dionne <marc.dionne@your-file-system.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      2b94e896
    • J
      dm thin: fix missing out-of-data-space to write mode transition if blocks are released · 2c43fd26
      由 Joe Thornber 提交于 
      Discard bios and thin device deletion have the potential to release data
blocks.  If the thin-pool is in out-of-data-space mode, and blocks were
released, transition the thin-pool back to full write mode.

The correct time to do this is just after the thin-pool metadata commit.
It cannot be done before the commit because the space maps will not
allow immediate reuse of the data blocks in case there's a rollback
following power failure.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
      2c43fd26
    • J
      dm thin: fix inability to discard blocks when in out-of-data-space mode · 45ec9bd0
      由 Joe Thornber 提交于 
      When the pool was in PM_OUT_OF_SPACE mode its process_prepared_discard
function pointer was incorrectly being set to
process_prepared_discard_passdown rather than process_prepared_discard.

This incorrect function pointer meant the discard was being passed down,
but not effecting the mapping.  As such any discard that was issued, in
an attempt to reclaim blocks, would not successfully free data space.
Reported-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
      45ec9bd0
  3. 22 11月, 2014 1 次提交
    • M
      dm thin: fix pool_io_hints to avoid looking at max_hw_sectors · d200c30e
      由 Mike Snitzer 提交于 
      Simplify the pool_io_hints code that works to establish a max_sectors
value that is a power-of-2 factor of the thin-pool's blocksize.  The
biggest associated improvement is that the DM thin-pool is no longer
concerning itself with the data device's max_hw_sectors when adjusting
max_sectors.

This fixes the relative fragility of the original "dm thin: adjust
max_sectors_kb based on thinp blocksize" commit that only became
apparent when testing was performed using a DM thin-pool ontop of a
virtio_blk device.  One proposed upstream patch detailed the problems
inherent in virtio_blk: https://lkml.org/lkml/2014/11/20/611

So even though virtio_blk incorrectly set its max_hw_sectors it actually
helped make it clear that we need DM thinp to be tolerant of any future
Linux driver that incorrectly sets max_hw_sectors.

We only need to be concerned with modifying the thin-pool device's
max_sectors limit if it is smaller than the thin-pool's blocksize.  In
this case the value of max_sectors does become a limiting factor when
upper layers (e.g. filesystems) construct their bios.  But if the
hardware can support IOs larger than the thin-pool's blocksize the user
is encouraged to adjust the thin-pool's data device's max_sectors
accordingly -- doing so will enable the thin-pool to inherit the
established user-defined max_sectors.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      d200c30e
  5. 20 11月, 2014 2 次提交
  7. 13 11月, 2014 2 次提交
  9. 11 11月, 2014 14 次提交
  11. 05 11月, 2014 1 次提交
  13. 02 8月, 2014 3 次提交
  15. 12 6月, 2014 1 次提交
    • L
      dm thin: update discard_granularity to reflect the thin-pool blocksize · 09869de5
      由 Lukas Czerner 提交于 
      DM thinp already checks whether the discard_granularity of the data
device is a factor of the thin-pool block size.  But when using the
dm-thin-pool's discard passdown support, DM thinp was not selecting the
max of the underlying data device's discard_granularity and the
thin-pool's block size.

Update set_discard_limits() to set discard_granularity to the max of
these values.  This enables blkdev_issue_discard() to properly align the
discards that are sent to the DM thin device on a full block boundary.
As such each discard will now cover an entire DM thin-pool block and the
block will be reclaimed.
Reported-by: NZdenek Kabelac <zkabelac@redhat.com>
Signed-off-by: NLukas Czerner <lczerner@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
      09869de5
  17. 04 6月, 2014 2 次提交
  19. 21 5月, 2014 1 次提交
    • M
      dm thin: add 'no_space_timeout' dm-thin-pool module param · 80c57893
      由 Mike Snitzer 提交于 
      Commit 85ad643b ("dm thin: add timeout to stop out-of-data-space mode
holding IO forever") introduced a fixed 60 second timeout.  Users may
want to either disable or modify this timeout.

Allow the out-of-data-space timeout to be configured using the
'no_space_timeout' dm-thin-pool module param.  Setting it to 0 will
disable the timeout, resulting in IO being queued until more data space
is added to the thin-pool.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.14+
      80c57893
  21. 15 5月, 2014 2 次提交
  23. 29 4月, 2014 1 次提交
  25. 08 4月, 2014 2 次提交
    • J
      dm thin: fix rcu_read_lock being held in code that can sleep · b10ebd34
      由 Joe Thornber 提交于 
      Commit c140e1c4 ("dm thin: use per thin device deferred bio lists")
introduced the use of an rculist for all active thin devices.  The use
of rcu_read_lock() in process_deferred_bios() can result in a BUG if a
dm_bio_prison_cell must be allocated as a side-effect of bio_detain():

 BUG: sleeping function called from invalid context at mm/mempool.c:203
 in_atomic(): 1, irqs_disabled(): 0, pid: 6, name: kworker/u8:0
 3 locks held by kworker/u8:0/6:
   #0:  ("dm-" "thin"){.+.+..}, at: [<ffffffff8106be42>] process_one_work+0x192/0x550
   #1:  ((&pool->worker)){+.+...}, at: [<ffffffff8106be42>] process_one_work+0x192/0x550
   #2:  (rcu_read_lock){.+.+..}, at: [<ffffffff816360b5>] do_worker+0x5/0x4d0

We can't process deferred bios with the rcu lock held, since
dm_bio_prison_cell allocation may block if the bio-prison's cell mempool
is exhausted.

To fix:

- Introduce a refcount and completion field to each thin_c

- Add thin_get/put methods for adjusting the refcount.  If the refcount
  hits zero then the completion is triggered.

- Initialise refcount to 1 when creating thin_c

- When iterating the active_thins list we thin_get() whilst the rcu
  lock is held.

- After the rcu lock is dropped we process the deferred bios for that
  thin.

- When destroying a thin_c we thin_put() and then wait for the
  completion -- to avoid a race between the worker thread iterating
  from that thin_c and destroying the thin_c.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      b10ebd34
    • J
      dm thin: irqsave must always be used with the pool->lock spinlock · 5e3283e2
      由 Joe Thornber 提交于 
      Commit c140e1c4 ("dm thin: use per thin device deferred bio lists")
incorrectly stopped disabling irqs when taking the pool's spinlock.

Irqs must be disabled when taking the pool's spinlock otherwise a thread
could spin_lock(), then get interrupted to service thin_endio() in
interrupt context, which would then deadlock in spin_lock_irqsave().
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      5e3283e2
  27. 05 4月, 2014 1 次提交
    • M
      dm thin: sort the per thin deferred bios using an rb_tree · 67324ea1
      由 Mike Snitzer 提交于 
      A thin-pool will allocate blocks using FIFO order for all thin devices
which share the thin-pool.  Because of this simplistic allocation the
thin-pool's space can become fragmented quite easily; especially when
multiple threads are requesting blocks in parallel.

Sort each thin device's deferred_bio_list based on logical sector to
help reduce fragmentation of the thin-pool's ondisk layout.

The following tables illustrate the realized gains/potential offered by
sorting each thin device's deferred_bio_list.  An "io size"-sized random
read of the device would result in "seeks/io" fragments being read, with
an average "distance/seek" between each fragment.

Data was written to a single thin device using multiple threads via
iozone (8 threads, 64K for both the block_size and io_size).

unsorted:

     io size   seeks/io distance/seek
  --------------------------------------
          4k    0.000   0b
         16k    0.013   11m
         64k    0.065   11m
        256k    0.274   10m
          1m    1.109   10m
          4m    4.411   10m
         16m    17.097  11m
         64m    60.055  13m
        256m    148.798 25m
          1g    809.929 21m

sorted:

     io size   seeks/io distance/seek
  --------------------------------------
          4k    0.000   0b
         16k    0.000   1g
         64k    0.001   1g
        256k    0.003   1g
          1m    0.011   1g
          4m    0.045   1g
         16m    0.181   1g
         64m    0.747   1011m
        256m    3.299   1g
          1g    14.373  1g
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Acked-by: NJoe Thornber <ejt@redhat.com>
      67324ea1
  29. 01 4月, 2014 1 次提交
    • M
      dm thin: use per thin device deferred bio lists · c140e1c4
      由 Mike Snitzer 提交于 
      The thin-pool previously only had a single deferred_bios list that would
collect bios for all thin devices in the pool.  Split this per-pool
deferred_bios list out to per-thin deferred_bios_list -- doing so
enables increased parallelism when processing deferred bios.  And now
that each thin device has it's own deferred_bios_list we can sort all
bios in the list using logical sector.  The requeue code in error
handling path is also cleaner as a side-effect.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Acked-by: NJoe Thornber <ejt@redhat.com>
      c140e1c4
  31. 31 3月, 2014 1 次提交
  33. 29 3月, 2014 1 次提交
  35. 06 3月, 2014 1 次提交
    • J
      dm thin: fix noflush suspend IO queueing · 738211f7
      由 Joe Thornber 提交于 
      i) by the time DM core calls the postsuspend hook the dm_noflush flag
has been cleared.  So the old thin_postsuspend did nothing.  We need to
use the presuspend hook instead.

ii) There was a race between bios leaving DM core and arriving in the
deferred queue.

thin_presuspend now sets a 'requeue' flag causing all bios destined for
that thin to be requeued back to DM core.  Then it requeues all held IO,
and all IO on the deferred queue (destined for that thin).  Finally
postsuspend clears the 'requeue' flag.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      738211f7