linux-toradex.git/drivers/md/dm-snap.c, branch v3.4.2

dm snapshot: skip reading origin when overwriting complete chunk

2011-08-02T11:32:04+00:00

If we write a full chunk in the snapshot, skip reading the origin device
because the whole chunk will be overwritten anyway.

This patch changes the snapshot write logic when a full chunk is written.
In this case:
  1. allocate the exception
  2. dispatch the bio (but don't report the bio completion to device mapper)
  3. write the exception record
  4. report bio completed

Callbacks must be done through the kcopyd thread, because callbacks must not
race with each other.  So we create two new functions:

  dm_kcopyd_prepare_callback: allocate a job structure and prepare the callback.
  (This function must not be called from interrupt context.)

  dm_kcopyd_do_callback: submit callback.
  (This function may be called from interrupt context.)

Performance test (on snapshots with 4k chunk size):
  without the patch:
    non-direct-io sequential write (dd):    17.7MB/s
    direct-io sequential write (dd):        20.9MB/s
    non-direct-io random write (mkfs.ext2): 0.44s

  with the patch:
    non-direct-io sequential write (dd):    26.5MB/s
    direct-io sequential write (dd):        33.2MB/s
    non-direct-io random write (mkfs.ext2): 0.27s

Signed-off-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm snapshot: style cleanups

2011-08-02T11:32:03+00:00

Coding style cleanups.

Signed-off-by: Alasdair G Kergon 
Signed-off-by: Jonathan Brassow

dm snapshot: remove unused definitions

2011-08-02T11:32:03+00:00

Remove a couple of unused #defines.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm kcopyd: return client directly and not through a pointer

2011-05-29T12:03:13+00:00

Return client directly from dm_kcopyd_client_create, not through a
parameter, making it consistent with dm_io_client_create.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm kcopyd: reserve fewer pages

2011-05-29T12:03:11+00:00

Reserve just the minimum of pages needed to process one job.

Because we allocate pages from page allocator, we don't need to reserve
a large number of pages.  The maximum job size is SUB_JOB_SIZE and we
calculate the number of reserved pages based on this.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm: fix opening log and cow devices for read only tables

2011-03-24T13:52:14+00:00

If a table is read-only, also open any log and cow devices it uses read-only.

Previously, even read-only devices were opened read-write internally.
After patch 75f1dc0d076d1c1168f2115f1941ea627d38bd5a
  block: check bdev_read_only() from blkdev_get()
was applied, loading such tables began to fail.  The patch
was reverted by e51900f7d38cbcfb481d84567fd92540e7e1d23a
  block: revert block_dev read-only check
but this patch fixes this part of the code to work with the original patch.

Signed-off-by: Milan Broz 
Signed-off-by: Alasdair G Kergon

dm snapshot: avoid storing private suspended state

2011-01-13T19:59:59+00:00

Use dm_suspended() rather than having each snapshot target maintain a
private 'suspended' flag in struct dm_snapshot.

Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm snapshot: remove unused dm_snapshot queued_bios_work

2011-01-13T19:59:56+00:00

dm_snapshot->queued_bios_work isn't used.  Remove ->queued_bios[_work]
from dm_snapshot structure, the flush_queued_bios work function and
ksnapd workqueue.

The DM snapshot changes that were going to use the ksnapd workqueue were
either superseded (fix for origin write races) or never completed
(deallocation of invalid snapshot's memory via workqueue).

Signed-off-by: Tejun Heo 
Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

Merge branch 'for-2.6.37/barrier' of git://git.kernel.dk/linux-2.6-block

2010-10-23T00:07:18+00:00

* 'for-2.6.37/barrier' of git://git.kernel.dk/linux-2.6-block: (46 commits)
  xen-blkfront: disable barrier/flush write support
  Added blk-lib.c and blk-barrier.c was renamed to blk-flush.c
  block: remove BLKDEV_IFL_WAIT
  aic7xxx_old: removed unused 'req' variable
  block: remove the BH_Eopnotsupp flag
  block: remove the BLKDEV_IFL_BARRIER flag
  block: remove the WRITE_BARRIER flag
  swap: do not send discards as barriers
  fat: do not send discards as barriers
  ext4: do not send discards as barriers
  jbd2: replace barriers with explicit flush / FUA usage
  jbd2: Modify ASYNC_COMMIT code to not rely on queue draining on barrier
  jbd: replace barriers with explicit flush / FUA usage
  nilfs2: replace barriers with explicit flush / FUA usage
  reiserfs: replace barriers with explicit flush / FUA usage
  gfs2: replace barriers with explicit flush / FUA usage
  btrfs: replace barriers with explicit flush / FUA usage
  xfs: replace barriers with explicit flush / FUA usage
  block: pass gfp_mask and flags to sb_issue_discard
  dm: convey that all flushes are processed as empty
  ...

Consolidate min_not_zero

2010-09-10T18:07:38+00:00

We have several users of min_not_zero, each of them using their own
definition.  Move the define to kernel.h.

Signed-off-by: Martin K. Petersen 
Signed-off-by: Jens Axboe