linux-toradex.git/drivers/md/dm-snap.c, branch v3.7

dm thin: commit before gathering status

2012-07-27T14:08:16+00:00

Commit outstanding metadata before returning the status for a dm thin
pool so that the numbers reported are as up-to-date as possible.

The commit is not performed if the device is suspended or if
the DM_NOFLUSH_FLAG is supplied by userspace and passed to the target
through a new 'status_flags' parameter in the target's dm_status_fn.

The userspace dmsetup tool will support the --noflush flag with the
'dmsetup status' and 'dmsetup wait' commands from version 1.02.76
onwards.

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

dm: support non power of two target max_io_len

2012-07-27T14:08:00+00:00

Remove the restriction that limits a target's specified maximum incoming
I/O size to be a power of 2.

Rename this setting from 'split_io' to the less-ambiguous 'max_io_len'.
Change it from sector_t to uint32_t, which is plenty big enough, and
introduce a wrapper function dm_set_target_max_io_len() to set it.
Use sector_div() to process it now that it is not necessarily a power of 2.

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

dm snapshot: remove redundant assignment in merge fn

2012-07-27T14:07:59+00:00

Remove redundant bvm->bi_sector self-assignment in dm snapshot's
origin_merge().

Signed-off-by: Alasdair G Kergon

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