On Thu, 9 Jun 2011, Joe Thornber wrote:
> On Wed, Jun 08, 2011 at 05:55:37PM -0400, Mikulas Patocka wrote:
> > Hi
> >
> > This patch introduces an option to kcopyd to zero requested area instead
> > of copying. I think Joe may need something like this in his snapshot
> > store.
>
> Could we have another function please, rather than overloading the
> existing entry point?
>
> i.e.,
>
> 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);
>
> Thanks,
>
> - Joe
>
Here it is ... but it duplicates some code in dm_kcopyd_copy..
Mikulas
---
dm-kcopyd: optionally zero an area instead of copying
This patch introduces new function "dm_kcopyd_zero" that zeroes a
requested.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
drivers/md/dm-kcopyd.c | 53 +++++++++++++++++++++++++++++++++++++++++++++-
include/linux/dm-kcopyd.h | 4 +++
2 files changed, 56 insertions(+), 1 deletion(-)
Index: linux-2.6.39-fast/drivers/md/dm-kcopyd.c
===================================================================
--- linux-2.6.39-fast.orig/drivers/md/dm-kcopyd.c 2011-06-09 17:15:34.000000000 +0200
+++ linux-2.6.39-fast/drivers/md/dm-kcopyd.c 2011-06-09 17:20:30.000000000 +0200
@@ -69,6 +69,8 @@ struct dm_kcopyd_client {
struct list_head pages_jobs;
};
+static struct page_list zero_page_list;
+
static DEFINE_SPINLOCK(throttle_spinlock);
/*
@@ -339,6 +341,9 @@ 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;
}
@@ -407,7 +412,7 @@ static int run_complete_job(struct kcopy
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);
/* Do not free sub-jobs */
if (context != job)
@@ -570,6 +575,8 @@ static void dispatch_job(struct kcopyd_j
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);
@@ -704,6 +711,50 @@ int dm_kcopyd_copy(struct dm_kcopyd_clie
}
EXPORT_SYMBOL(dm_kcopyd_copy);
+int dm_kcopyd_zero(struct dm_kcopyd_client *kc,
+ unsigned int num_dests, struct dm_io_region *dests,
+ unsigned int flags, dm_kcopyd_notify_fn fn, void *context)
+{
+ struct kcopyd_job *job;
+
+ /*
+ * Allocate a new job.
+ */
+ job = mempool_alloc(kc->job_pool, GFP_NOIO);
+
+ /*
+ * set up for the write.
+ */
+ job->kc = kc;
+ job->flags = flags;
+ job->read_err = 0;
+ job->write_err = 0;
+ job->rw = WRITE;
+
+ memset(&job->source, 0, sizeof job->source);
+ job->source.count = dests[0].count;
+
+ job->num_dests = num_dests;
+ memcpy(&job->dests, dests, sizeof(*dests) * num_dests);
+
+ job->pages = &zero_page_list;
+
+ job->fn = fn;
+ job->context = context;
+
+ if (job->source.count <= SUB_JOB_SIZE)
+ dispatch_job(job);
+
+ else {
+ mutex_init(&job->lock);
+ job->progress = 0;
+ split_job(job);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL(dm_kcopyd_zero);
+
/*
* Cancels a kcopyd job, eg. someone might be deactivating a
* mirror.
Index: linux-2.6.39-fast/include/linux/dm-kcopyd.h
===================================================================
--- linux-2.6.39-fast.orig/include/linux/dm-kcopyd.h 2011-06-09 17:20:47.000000000 +0200
+++ linux-2.6.39-fast/include/linux/dm-kcopyd.h 2011-06-09 17:21:01.000000000 +0200
@@ -55,5 +55,9 @@ int dm_kcopyd_copy(struct dm_kcopyd_clie
unsigned num_dests, struct dm_io_region *dests,
unsigned flags, dm_kcopyd_notify_fn fn, void *context);
+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 */
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