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-rw-r--r--drivers/md/dm-kcopyd.c54
1 files changed, 51 insertions, 3 deletions
diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index 5ad9231c8700..dad32f8bce7d 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -37,6 +37,13 @@ struct dm_kcopyd_client {
unsigned int nr_pages;
unsigned int nr_free_pages;
+ /*
+ * Block devices to unplug.
+ * Non-NULL pointer means that a block device has some pending requests
+ * and needs to be unplugged.
+ */
+ struct block_device *unplug[2];
+
struct dm_io_client *io_client;
wait_queue_head_t destroyq;
@@ -308,6 +315,31 @@ static int run_complete_job(struct kcopyd_job *job)
return 0;
}
+/*
+ * Unplug the block device at the specified index.
+ */
+static void unplug(struct dm_kcopyd_client *kc, int rw)
+{
+ if (kc->unplug[rw] != NULL) {
+ blk_unplug(bdev_get_queue(kc->unplug[rw]));
+ kc->unplug[rw] = NULL;
+ }
+}
+
+/*
+ * Prepare block device unplug. If there's another device
+ * to be unplugged at the same array index, we unplug that
+ * device first.
+ */
+static void prepare_unplug(struct dm_kcopyd_client *kc, int rw,
+ struct block_device *bdev)
+{
+ if (likely(kc->unplug[rw] == bdev))
+ return;
+ unplug(kc, rw);
+ kc->unplug[rw] = bdev;
+}
+
static void complete_io(unsigned long error, void *context)
{
struct kcopyd_job *job = (struct kcopyd_job *) context;
@@ -345,7 +377,7 @@ static int run_io_job(struct kcopyd_job *job)
{
int r;
struct dm_io_request io_req = {
- .bi_rw = job->rw | REQ_UNPLUG,
+ .bi_rw = job->rw,
.mem.type = DM_IO_PAGE_LIST,
.mem.ptr.pl = job->pages,
.mem.offset = job->offset,
@@ -354,10 +386,16 @@ static int run_io_job(struct kcopyd_job *job)
.client = job->kc->io_client,
};
- if (job->rw == READ)
+ if (job->rw == READ) {
r = dm_io(&io_req, 1, &job->source, NULL);
- else
+ prepare_unplug(job->kc, READ, job->source.bdev);
+ } else {
+ if (job->num_dests > 1)
+ io_req.bi_rw |= REQ_UNPLUG;
r = dm_io(&io_req, job->num_dests, job->dests, NULL);
+ if (!(io_req.bi_rw & REQ_UNPLUG))
+ prepare_unplug(job->kc, WRITE, job->dests[0].bdev);
+ }
return r;
}
@@ -435,10 +473,18 @@ static void do_work(struct work_struct *work)
* Pages jobs when successful will jump onto the io jobs
* list. io jobs call wake when they complete and it all
* starts again.
+ *
+ * Note that io_jobs add block devices to the unplug array,
+ * this array is cleared with "unplug" calls. It is thus
+ * forbidden to run complete_jobs after io_jobs and before
+ * unplug because the block device could be destroyed in
+ * job completion callback.
*/
process_jobs(&kc->complete_jobs, kc, run_complete_job);
process_jobs(&kc->pages_jobs, kc, run_pages_job);
process_jobs(&kc->io_jobs, kc, run_io_job);
+ unplug(kc, READ);
+ unplug(kc, WRITE);
}
/*
@@ -619,6 +665,8 @@ int dm_kcopyd_client_create(unsigned int nr_pages,
INIT_LIST_HEAD(&kc->io_jobs);
INIT_LIST_HEAD(&kc->pages_jobs);
+ memset(kc->unplug, 0, sizeof(kc->unplug));
+
kc->job_pool = mempool_create_slab_pool(MIN_JOBS, _job_cache);
if (!kc->job_pool)
goto bad_slab;