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authorMike Snitzer <snitzer@redhat.com>2016-01-31 17:33:32 -0500
committerMike Snitzer <snitzer@redhat.com>2016-02-22 11:06:22 -0500
commitc91852ff081561d8793d2927e55f5c5deaea6bff (patch)
tree84a5ba9004d9ff5fef7116231766f157d0acbe4f
parent16f122661dbb3dfefc60788b528b54ad702005aa (diff)
downloadop-kernel-dev-c91852ff081561d8793d2927e55f5c5deaea6bff.zip
op-kernel-dev-c91852ff081561d8793d2927e55f5c5deaea6bff.tar.gz
dm: optimize dm_request_fn()
DM multipath is the only request-based DM target -- which only supports tables with a single target that is immutable. Leverage this fact in dm_request_fn(). Signed-off-by: Mike Snitzer <snitzer@redhat.com>
-rw-r--r--drivers/md/dm.c47
1 files changed, 17 insertions, 30 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 35ca9d0..6214502 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2071,12 +2071,18 @@ static bool dm_request_peeked_before_merge_deadline(struct mapped_device *md)
static void dm_request_fn(struct request_queue *q)
{
struct mapped_device *md = q->queuedata;
- int srcu_idx;
- struct dm_table *map = dm_get_live_table(md, &srcu_idx);
- struct dm_target *ti;
+ struct dm_target *ti = md->immutable_target;
struct request *rq;
struct dm_rq_target_io *tio;
- sector_t pos;
+ sector_t pos = 0;
+
+ if (unlikely(!ti)) {
+ int srcu_idx;
+ struct dm_table *map = dm_get_live_table(md, &srcu_idx);
+
+ ti = dm_table_find_target(map, pos);
+ dm_put_live_table(md, srcu_idx);
+ }
/*
* For suspend, check blk_queue_stopped() and increment
@@ -2087,33 +2093,21 @@ static void dm_request_fn(struct request_queue *q)
while (!blk_queue_stopped(q)) {
rq = blk_peek_request(q);
if (!rq)
- goto out;
+ return;
/* always use block 0 to find the target for flushes for now */
pos = 0;
if (!(rq->cmd_flags & REQ_FLUSH))
pos = blk_rq_pos(rq);
- ti = dm_table_find_target(map, pos);
- if (!dm_target_is_valid(ti)) {
- /*
- * Must perform setup, that rq_completed() requires,
- * before calling dm_kill_unmapped_request
- */
- DMERR_LIMIT("request attempted access beyond the end of device");
- dm_start_request(md, rq);
- dm_kill_unmapped_request(rq, -EIO);
- continue;
+ if ((dm_request_peeked_before_merge_deadline(md) &&
+ md_in_flight(md) && rq->bio && rq->bio->bi_vcnt == 1 &&
+ md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) ||
+ (ti->type->busy && ti->type->busy(ti))) {
+ blk_delay_queue(q, HZ / 100);
+ return;
}
- if (dm_request_peeked_before_merge_deadline(md) &&
- md_in_flight(md) && rq->bio && rq->bio->bi_vcnt == 1 &&
- md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq))
- goto delay_and_out;
-
- if (ti->type->busy && ti->type->busy(ti))
- goto delay_and_out;
-
dm_start_request(md, rq);
tio = tio_from_request(rq);
@@ -2122,13 +2116,6 @@ static void dm_request_fn(struct request_queue *q)
queue_kthread_work(&md->kworker, &tio->work);
BUG_ON(!irqs_disabled());
}
-
- goto out;
-
-delay_and_out:
- blk_delay_queue(q, HZ / 100);
-out:
- dm_put_live_table(md, srcu_idx);
}
static int dm_any_congested(void *congested_data, int bdi_bits)
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