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  1. 25 3月, 2015 1 次提交
  3. 21 3月, 2015 3 次提交
  5. 04 3月, 2015 2 次提交
  7. 25 2月, 2015 1 次提交
  9. 23 2月, 2015 23 次提交
  11. 18 2月, 2015 3 次提交
    • M
      dm snapshot: fix a possible invalid memory access on unload · 22aa66a3
      由 Mikulas Patocka 提交于 
      When the snapshot target is unloaded, snapshot_dtr() waits until
pending_exceptions_count drops to zero.  Then, it destroys the snapshot.
Therefore, the function that decrements pending_exceptions_count
should not touch the snapshot structure after the decrement.

pending_complete() calls free_pending_exception(), which decrements
pending_exceptions_count, and then it performs up_write(&s->lock) and it
calls retry_origin_bios() which dereferences  s->origin.  These two
memory accesses to the fields of the snapshot may touch the dm_snapshot
struture after it is freed.

This patch moves the call to free_pending_exception() to the end of
pending_complete(), so that the snapshot will not be destroyed while
pending_complete() is in progress.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
      22aa66a3
    • M
      dm: fix a race condition in dm_get_md · 2bec1f4a
      由 Mikulas Patocka 提交于 
      The function dm_get_md finds a device mapper device with a given dev_t,
increases the reference count and returns the pointer.

dm_get_md calls dm_find_md, dm_find_md takes _minor_lock, finds the
device, tests that the device doesn't have DMF_DELETING or DMF_FREEING
flag, drops _minor_lock and returns pointer to the device. dm_get_md then
calls dm_get. dm_get calls BUG if the device has the DMF_FREEING flag,
otherwise it increments the reference count.

There is a possible race condition - after dm_find_md exits and before
dm_get is called, there are no locks held, so the device may disappear or
DMF_FREEING flag may be set, which results in BUG.

To fix this bug, we need to call dm_get while we hold _minor_lock. This
patch renames dm_find_md to dm_get_md and changes it so that it calls
dm_get while holding the lock.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
      2bec1f4a
    • N
      md/raid5: Fix livelock when array is both resyncing and degraded. · 26ac1073
      由 NeilBrown 提交于 
      Commit a7854487:
  md: When RAID5 is dirty, force reconstruct-write instead of read-modify-write.

Causes an RCW cycle to be forced even when the array is degraded.
A degraded array cannot support RCW as that requires reading all data
blocks, and one may be missing.

Forcing an RCW when it is not possible causes a live-lock and the code
spins, repeatedly deciding to do something that cannot succeed.

So change the condition to only force RCW on non-degraded arrays.
Reported-by: NManibalan P <pmanibalan@amiindia.co.in>
Bisected-by: NJes Sorensen <Jes.Sorensen@redhat.com>
Tested-by: NJes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NNeilBrown <neilb@suse.de>
Fixes: a7854487
Cc: stable@vger.kernel.org (v3.7+)
      26ac1073
  13. 17 2月, 2015 7 次提交
    • M
      dm crypt: sort writes · b3c5fd30
      由 Mikulas Patocka 提交于 
      Write requests are sorted in a red-black tree structure and are
submitted in the sorted order.

In theory the sorting should be performed by the underlying disk
scheduler, however, in practice the disk scheduler only accepts and
sorts a finite number of requests.  To allow the sorting of all
requests, dm-crypt needs to implement its own sorting.

The overhead associated with rbtree-based sorting is considered
negligible so it is not used conditionally.  Even on SSD sorting can be
beneficial since in-order request dispatch promotes lower latency IO
completion to the upper layers.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      b3c5fd30
    • M
      dm crypt: add 'submit_from_crypt_cpus' option · 0f5d8e6e
      由 Mikulas Patocka 提交于 
      Make it possible to disable offloading writes by setting the optional
'submit_from_crypt_cpus' table argument.

There are some situations where offloading write bios from the
encryption threads to a single thread degrades performance
significantly.

The default is to offload write bios to the same thread because it
benefits CFQ to have writes submitted using the same IO context.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      0f5d8e6e
    • M
      dm crypt: offload writes to thread · dc267621
      由 Mikulas Patocka 提交于 
      Submitting write bios directly in the encryption thread caused serious
performance degradation.  On a multiprocessor machine, encryption requests
finish in a different order than they were submitted.  Consequently, write
requests would be submitted in a different order and it could cause severe
performance degradation.

Move the submission of write requests to a separate thread so that the
requests can be sorted before submitting.  But this commit improves
dm-crypt performance even without having dm-crypt perform request
sorting (in particular it enables IO schedulers like CFQ to sort more
effectively).

Note: it is required that a previous commit ("dm crypt: don't allocate
pages for a partial request") be applied before applying this patch.
Otherwise, this commit could introduce a crash.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      dc267621
    • M
      dm crypt: remove unused io_pool and _crypt_io_pool · 94f5e024
      由 Mikulas Patocka 提交于 
      The previous commit ("dm crypt: don't allocate pages for a partial
request") stopped using the io_pool slab mempool and backing
_crypt_io_pool kmem cache.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      94f5e024
    • M
      dm crypt: avoid deadlock in mempools · 7145c241
      由 Mikulas Patocka 提交于 
      Fix a theoretical deadlock introduced in the previous commit ("dm crypt:
don't allocate pages for a partial request").

The function crypt_alloc_buffer may be called concurrently.  If we allocate
from the mempool concurrently, there is a possibility of deadlock.  For
example, if we have mempool of 256 pages, two processes, each wanting
256, pages allocate from the mempool concurrently, it may deadlock in a
situation where both processes have allocated 128 pages and the mempool
is exhausted.

To avoid such a scenario we allocate the pages under a mutex.  In order
to not degrade performance with excessive locking, we try non-blocking
allocations without a mutex first and if that fails, we fallback to a
blocking allocations with a mutex.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      7145c241
    • M
      dm crypt: don't allocate pages for a partial request · cf2f1abf
      由 Mikulas Patocka 提交于 
      Change crypt_alloc_buffer so that it only ever allocates pages for a
full request.  This is a prerequisite for the commit "dm crypt: offload
writes to thread".

This change simplifies the dm-crypt code at the expense of reduced
throughput in low memory conditions (where allocation for a partial
request is most useful).

Note: the next commit ("dm crypt: avoid deadlock in mempools") is needed
to fix a theoretical deadlock.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      cf2f1abf
    • M
      dm crypt: use unbound workqueue for request processing · f3396c58
      由 Mikulas Patocka 提交于 
      Use unbound workqueue by default so that work is automatically balanced
between available CPUs.  The original behavior of encrypting using the
same cpu that IO was submitted on can still be enabled by setting the
optional 'same_cpu_crypt' table argument.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      f3396c58