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Commit 7f069653 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
Browse files

dm kcopyd: add dm_kcopyd_zero to zero an area 



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: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent fbdc86f3

drivers/md/dm-kcopyd.c

+26 −5
Original line number Diff line number Diff line
@@ -66,6 +66,8 @@ struct dm_kcopyd_client { 
	struct list_head pages_jobs;

};



static struct page_list zero_page_list;



static void wake(struct dm_kcopyd_client *kc)

{

	queue_work(kc->kcopyd_wq, &kc->kcopyd_work);
@@ -254,6 +256,9 @@ int __init dm_kcopyd_init(void) 
	if (!_job_cache)

		return -ENOMEM;



	zero_page_list.next = &zero_page_list;

	zero_page_list.page = ZERO_PAGE(0);



	return 0;

}
@@ -322,7 +327,7 @@ static int run_complete_job(struct kcopyd_job *job) 
	dm_kcopyd_notify_fn fn = job->fn;

	struct dm_kcopyd_client *kc = job->kc;



	if (job->pages)

	if (job->pages && job->pages != &zero_page_list)

		kcopyd_put_pages(kc, job->pages);

	/*

	 * If this is the master job, the sub jobs have already
@@ -484,6 +489,8 @@ static void dispatch_job(struct kcopyd_job *job) 
	atomic_inc(&kc->nr_jobs);

	if (unlikely(!job->source.count))

		push(&kc->complete_jobs, job);

	else if (job->pages == &zero_page_list)

		push(&kc->io_jobs, job);

	else

		push(&kc->pages_jobs, job);

	wake(kc);
@@ -592,14 +599,20 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from, 
	job->flags = flags;

	job->read_err = 0;

	job->write_err = 0;

	job->rw = READ;



	job->source = *from;



	job->num_dests = num_dests;

	memcpy(&job->dests, dests, sizeof(*dests) * num_dests);



	if (from) {

		job->source = *from;

		job->pages = NULL;

		job->rw = READ;

	} else {

		memset(&job->source, 0, sizeof job->source);

		job->source.count = job->dests[0].count;

		job->pages = &zero_page_list;

		job->rw = WRITE;

	}



	job->fn = fn;

	job->context = context;
@@ -617,6 +630,14 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from, 
}

EXPORT_SYMBOL(dm_kcopyd_copy);



int dm_kcopyd_zero(struct dm_kcopyd_client *kc,

		   unsigned num_dests, struct dm_io_region *dests,

		   unsigned flags, dm_kcopyd_notify_fn fn, void *context)

{

	return dm_kcopyd_copy(kc, NULL, num_dests, dests, flags, fn, context);

}

EXPORT_SYMBOL(dm_kcopyd_zero);



void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,

				 dm_kcopyd_notify_fn fn, void *context)

{

include/linux/dm-kcopyd.h

+4 −0
Original line number Diff line number Diff line
@@ -57,5 +57,9 @@ void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc, 
				 dm_kcopyd_notify_fn fn, void *context);

void dm_kcopyd_do_callback(void *job, int read_err, unsigned long write_err);



int dm_kcopyd_zero(struct dm_kcopyd_client *kc,

		   unsigned num_dests, struct dm_io_region *dests,

		   unsigned flags, dm_kcopyd_notify_fn fn, void *context);



#endif	/* __KERNEL__ */

#endif	/* _LINUX_DM_KCOPYD_H */