Change dm kcopyd so that it calls blkdev_issue_copy with an asynchronous
callback. There can be large number of pending kcopyd requests and holding
a process context for each of them may put too much load on the workqueue
subsystem.
This patch changes it so that blkdev_issue_copy returns after it submitted
the requests and copy_offload_callback is called when the copy operation
finishes.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
drivers/md/dm-kcopyd.c | 33 ++++++++++++++-------------------
1 file changed, 14 insertions(+), 19 deletions(-)
Index: linux-3.16-rc5/drivers/md/dm-kcopyd.c
===================================================================
--- linux-3.16-rc5.orig/drivers/md/dm-kcopyd.c 2014-07-15 19:24:20.000000000 +0200
+++ linux-3.16-rc5/drivers/md/dm-kcopyd.c 2014-07-15 19:24:54.000000000 +0200
@@ -361,8 +361,6 @@ struct kcopyd_job {
sector_t progress;
struct kcopyd_job *master_job;
-
- struct work_struct copy_work;
};
static struct kmem_cache *_job_cache;
@@ -628,8 +626,9 @@ static void segment_complete(int read_er
struct kcopyd_job *sub_job = (struct kcopyd_job *) context;
struct kcopyd_job *job = sub_job->master_job;
struct dm_kcopyd_client *kc = job->kc;
+ unsigned long flags;
- spin_lock(&job->lock);
+ spin_lock_irqsave(&job->lock, flags);
/* update the error */
if (read_err)
@@ -653,7 +652,7 @@ static void segment_complete(int read_er
job->progress += count;
}
}
- spin_unlock(&job->lock);
+ spin_unlock_irqrestore(&job->lock, flags);
if (count) {
int i;
@@ -714,29 +713,25 @@ static void submit_job(struct kcopyd_job
}
}
-static void copy_offload_work(struct work_struct *work)
+static void copy_offload_callback(void *ptr, int error)
{
- struct kcopyd_job *job = container_of(work, struct kcopyd_job, copy_work);
- sector_t copied;
+ struct kcopyd_job *job = ptr;
- blkdev_issue_copy(job->source.bdev, job->source.sector,
- job->dests[0].bdev, job->dests[0].sector,
- job->source.count,
- GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN,
- NULL, NULL, &copied);
-
- job->source.sector += copied;
- job->source.count -= copied;
- job->dests[0].sector += copied;
- job->dests[0].count -= copied;
+ job->source.sector += job->progress;
+ job->source.count -= job->progress;
+ job->dests[0].sector += job->progress;
+ job->dests[0].count -= job->progress;
submit_job(job);
}
static void try_copy_offload(struct kcopyd_job *job)
{
- INIT_WORK(&job->copy_work, copy_offload_work);
- queue_work(job->kc->kcopyd_wq, &job->copy_work);
+ blkdev_issue_copy(job->source.bdev, job->source.sector,
+ job->dests[0].bdev, job->dests[0].sector,
+ job->source.count,
+ GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN,
+ copy_offload_callback, job, &job->progress);
}
int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
--
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