lwn.git/drivers/md/dm-kcopyd.c, branch v3.14.75

dm: stop using WQ_NON_REENTRANT

2013-08-23T13:02:13+00:00

dbf2576e37 ("workqueue: make all workqueues non-reentrant") made WQ_NON_REENTRANT no-op and the flag is going away. Remove its usages. This patch doesn't introduce any behavior changes. Signed-off-by: Tejun Heo Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon Acked-by: Joe Thornber

dm kcopyd: introduce configurable throttling

2013-03-01T22:45:49+00:00

This patch allows the administrator to reduce the rate at which kcopyd issues I/O. Each module that uses kcopyd acquires a throttle parameter that can be set in /sys/module/*/parameters. We maintain a history of kcopyd usage by each module in the variables io_period and total_period in struct dm_kcopyd_throttle. The actual kcopyd activity is calculated as a percentage of time equal to "(100 * io_period / total_period)". This is compared with the user-defined throttle percentage threshold and if it is exceeded, we sleep. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon

dm kcopyd: add WRITE SAME support to dm_kcopyd_zero

2012-12-21T20:23:37+00:00

Add WRITE SAME support to dm-io and make it accessible to dm_kcopyd_zero(). dm_kcopyd_zero() provides an asynchronous interface whereas the blkdev_issue_write_same() interface is synchronous. WRITE SAME is a SCSI command that can be leveraged for more efficient zeroing of a specified logical extent of a device which supports it. Only a single zeroed logical block is transfered to the target for each WRITE SAME and the target then writes that same block across the specified extent. The dm thin target uses this. Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm kcopyd: add dm_kcopyd_zero to zero an area

2011-10-31T20:18:58+00:00

This patch introduces dm_kcopyd_zero() to make it easy to use kcopyd to write zeros into the requested areas instead instead of copying. It is implemented by passing a NULL copying source to dm_kcopyd_copy(). The forthcoming thin provisioning target uses this. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon

dm kcopyd: fix job_pool leak

2011-10-23T19:55:17+00:00

Fix memory leak introduced by commit a6e50b409d3f9e0833e69c3c9cca822e8fa4adbb (dm snapshot: skip reading origin when overwriting complete chunk). When allocating a set of jobs from kc->job_pool, job->master_job must be set (to point to itself) so that the mempool item gets freed when the master_job completes. master_job was introduced by commit c6ea41fbbe08f270a8edef99dc369faf809d1bd6 (dm kcopyd: preallocate sub jobs to avoid deadlock) Reported-by: Michael Leun Cc: Mikulas Patocka 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 kcopyd: remove nr_pages field from job structure

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

The nr_pages field in struct kcopyd_job is only used temporarily in run_pages_job() to count the number of required pages. We can use a local variable instead. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon

dm kcopyd: remove offset field from job structure

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

The offset field in struct kcopyd_job is always zero so remove it. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon

atomic: use

2011-07-26T23:49:47+00:00

This allows us to move duplicated code in (atomic_inc_not_zero() for now) to Signed-off-by: Arun Sharma Reviewed-by: Eric Dumazet Cc: Ingo Molnar Cc: David Miller Cc: Eric Dumazet Acked-by: Mike Frysinger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

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