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authorMike Snitzer <snitzer@redhat.com>2012-12-21 20:23:37 +0000
committerAlasdair G Kergon <agk@redhat.com>2012-12-21 20:23:37 +0000
commit70d6c400acc386ea910c77318688541fc32e7ce8 (patch)
tree6ab32a9b9699656c8d9147b38a776f615c1c737a
parent4f0b70b0479101522b8645ddc1f5ee7137821db3 (diff)
downloadvexpress-lsk-70d6c400acc386ea910c77318688541fc32e7ce8.tar.gz
dm kcopyd: add WRITE SAME support to dm_kcopyd_zero
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 <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--drivers/md/dm-io.c23
-rw-r--r--drivers/md/dm-kcopyd.c18
-rw-r--r--drivers/md/dm-thin.c2
3 files changed, 33 insertions, 10 deletions
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 1c46f97d666..ea49834377c 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -287,7 +287,8 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
unsigned num_bvecs;
sector_t remaining = where->count;
struct request_queue *q = bdev_get_queue(where->bdev);
- sector_t discard_sectors;
+ unsigned short logical_block_size = queue_logical_block_size(q);
+ sector_t num_sectors;
/*
* where->count may be zero if rw holds a flush and we need to
@@ -297,7 +298,7 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
/*
* Allocate a suitably sized-bio.
*/
- if (rw & REQ_DISCARD)
+ if ((rw & REQ_DISCARD) || (rw & REQ_WRITE_SAME))
num_bvecs = 1;
else
num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev),
@@ -310,9 +311,21 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
store_io_and_region_in_bio(bio, io, region);
if (rw & REQ_DISCARD) {
- discard_sectors = min_t(sector_t, q->limits.max_discard_sectors, remaining);
- bio->bi_size = discard_sectors << SECTOR_SHIFT;
- remaining -= discard_sectors;
+ num_sectors = min_t(sector_t, q->limits.max_discard_sectors, remaining);
+ bio->bi_size = num_sectors << SECTOR_SHIFT;
+ remaining -= num_sectors;
+ } else if (rw & REQ_WRITE_SAME) {
+ /*
+ * WRITE SAME only uses a single page.
+ */
+ dp->get_page(dp, &page, &len, &offset);
+ bio_add_page(bio, page, logical_block_size, offset);
+ num_sectors = min_t(sector_t, q->limits.max_write_same_sectors, remaining);
+ bio->bi_size = num_sectors << SECTOR_SHIFT;
+
+ offset = 0;
+ remaining -= num_sectors;
+ dp->next_page(dp);
} else while (remaining) {
/*
* Try and add as many pages as possible.
diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index bed444c93d8..68c02673263 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -349,7 +349,7 @@ static void complete_io(unsigned long error, void *context)
struct dm_kcopyd_client *kc = job->kc;
if (error) {
- if (job->rw == WRITE)
+ if (job->rw & WRITE)
job->write_err |= error;
else
job->read_err = 1;
@@ -361,7 +361,7 @@ static void complete_io(unsigned long error, void *context)
}
}
- if (job->rw == WRITE)
+ if (job->rw & WRITE)
push(&kc->complete_jobs, job);
else {
@@ -432,7 +432,7 @@ static int process_jobs(struct list_head *jobs, struct dm_kcopyd_client *kc,
if (r < 0) {
/* error this rogue job */
- if (job->rw == WRITE)
+ if (job->rw & WRITE)
job->write_err = (unsigned long) -1L;
else
job->read_err = 1;
@@ -585,6 +585,7 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
unsigned int flags, dm_kcopyd_notify_fn fn, void *context)
{
struct kcopyd_job *job;
+ int i;
/*
* Allocate an array of jobs consisting of one master job
@@ -611,7 +612,16 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
memset(&job->source, 0, sizeof job->source);
job->source.count = job->dests[0].count;
job->pages = &zero_page_list;
- job->rw = WRITE;
+
+ /*
+ * Use WRITE SAME to optimize zeroing if all dests support it.
+ */
+ job->rw = WRITE | REQ_WRITE_SAME;
+ for (i = 0; i < job->num_dests; i++)
+ if (!bdev_write_same(job->dests[i].bdev)) {
+ job->rw = WRITE;
+ break;
+ }
}
job->fn = fn;
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index fba378f234a..4b940745ba9 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2779,7 +2779,7 @@ static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits)
static struct target_type thin_target = {
.name = "thin",
- .version = {1, 5, 0},
+ .version = {1, 6, 0},
.module = THIS_MODULE,
.ctr = thin_ctr,
.dtr = thin_dtr,