Recent change to use bio_copy_data() in raid1 when repairing
an array is faulty.

The underlying may have changed the bio in various ways using
bio_advance and these need to be undone not just for the 'sbio' which
is being copied to, but also the 'pbio' (primary) which is being
copied from.

So perform the reset on all bios that were read from and do it early.

This also ensure that the sbio->bi_io_vec[j].bv_len passed to
memcmp is correct.

This fixes a crash during a 'check' of a RAID1 array.  The crash was
introduced in 3.10 so this is suitable for 3.10-stable.

Cc: stable@vger.kernel.org (3.10)
Reported-by: Joe Lawrence <joe.lawrence@stratus.com>
Signed-off-by: NeilBrown <neilb@suse.de>

commit 7ceb17e87bde79d285a8b988cfed9eaeebe60b86
    md: Allow devices to be re-added to a read-only array.

allowed a bit more than just that.  It also allows devices to be added
to a read-write array and to end up skipping recovery.

This patch removes the offending piece of code pending a rewrite for a
subsequent release.

More specifically:
 If the array has a bitmap, then the device will still need a bitmap
 based resync ('saved_raid_disk' is set under different conditions
 is a bitmap is present).
 If the array doesn't have a bitmap, then this is correct as long as
 nothing has been written to the array since the metadata was checked
 by ->validate_super.  However there is no locking to ensure that there
 was no write.

Bug was introduced in 3.10 and causes data corruption so
patch is suitable for 3.10-stable.

Cc: stable@vger.kernel.org (3.10)
Reported-by: Joe Lawrence <joe.lawrence@stratus.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1/ When an different between blocks is found, data is copied from
   one bio to the other.  However bv_len is used as the length to
   copy and this could be zero.  So use r10_bio->sectors to calculate
   length instead.
   Using bv_len was probably always a bit dubious, but the introduction
   of bio_advance made it much more likely to be a problem.

2/ When preparing some blocks for sync, we don't set BIO_UPTODATE
   except on bios that we schedule for a read.  This ensures that
   missing/failed devices don't confuse the loop at the top of
   sync_request write.
   Commit 8be185f2c9d54d6 "raid10: Use bio_reset()"
   removed a loop which set BIO_UPTDATE on all appropriate bios.
   So we need to re-add that flag.

These bugs were introduced in 3.10, so this patch is suitable for
3.10-stable, and can remove a potential for data corruption.

Cc: stable@vger.kernel.org (3.10)
Reported-by: Brassow Jonathan <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Pull device-mapper changes from Alasdair G Kergon:
 "Add a device-mapper target called dm-switch to provide a multipath
  framework for storage arrays that dynamically reconfigure their
  preferred paths for different device regions.

  Fix a bug in the verity target that prevented its use with some
  specific sizes of devices.

  Improve some locking mechanisms in the device-mapper core and bufio.

  Add Mike Snitzer as a device-mapper maintainer.

  A few more clean-ups and fixes"

* tag 'dm-3.11-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm:
  dm: add switch target
  dm: update maintainers
  dm: optimize reorder structure
  dm: optimize use SRCU and RCU
  dm bufio: submit writes outside lock
  dm cache: fix arm link errors with inline
  dm verity: use __ffs and __fls
  dm flakey: correct ctr alloc failure mesg
  dm verity: remove pointless comparison
  dm: use __GFP_HIGHMEM in __vmalloc
  dm verity: fix inability to use a few specific devices sizes
  dm ioctl: set noio flag to avoid __vmalloc deadlock
  dm mpath: fix ioctl deadlock when no paths

dm-switch is a new target that maps IO to underlying block devices
efficiently when there is a large number of fixed-sized address regions
but there is no simple pattern to allow for a compact mapping
representation such as dm-stripe.

Though we have developed this target for a specific storage device, Dell
EqualLogic, we have made an effort to keep it as general purpose as
possible in the hope that others may benefit.

Originally developed by Jim Ramsay. Simplified by Mikulas Patocka.

Signed-off-by: Jim Ramsay <jim_ramsay@dell.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

This reorder actually improves performance by 20% (from 39.1s to 32.8s)
on x86-64 quad core Opteron.

I have no explanation for this, possibly it makes some other entries are
better cache-aligned.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

This patch removes "io_lock" and "map_lock" in struct mapped_device and
"holders" in struct dm_table and replaces these mechanisms with
sleepable-rcu.

Previously, the code would call "dm_get_live_table" and "dm_table_put" to
get and release table. Now, the code is changed to call "dm_get_live_table"
and "dm_put_live_table". dm_get_live_table locks sleepable-rcu and
dm_put_live_table unlocks it.

dm_get_live_table_fast/dm_put_live_table_fast can be used instead of
dm_get_live_table/dm_put_live_table. These *_fast functions use
non-sleepable RCU, so the caller must not block between them.

If the code changes active or inactive dm table, it must call
dm_sync_table before destroying the old table.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

This patch changes dm-bufio so that it submits write I/Os outside of the
lock. If the number of submitted buffers is greater than the number of
requests on the target queue, submit_bio blocks. We want to block outside
of the lock to improve latency of other threads that may need the lock.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

Use __always_inline to avoid a link failure with gcc 4.6 on ARM.
gcc 4.7 is OK.

It creates a function block_div.part.8, it references __udivdi3 and
__umoddi3 and it is never called. The references to __udivdi3 and
__umoddi3 cause a link failure.

Reported-by: Rob Herring <robherring2@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

This patch changes ffs() to __ffs() and fls() to __fls() which don't add
one to the result.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>