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authorDavid Woodhouse <David.Woodhouse@intel.com>2008-08-09 16:42:20 +0100
committerJens Axboe <jens.axboe@oracle.com>2008-10-09 08:56:02 +0200
commite17fc0a1ccf88f6d4dcb363729f3141b0958c325 (patch)
tree0a7c2dc1c3159c2af14d87c67ca83e158b2c78b5 /block/elevator.c
parentd30a2605be9d5132d95944916e8f578fcfe4f976 (diff)
Allow elevators to sort/merge discard requests
But blkdev_issue_discard() still emits requests which are interpreted as soft barriers, because naïve callers might otherwise issue subsequent writes to those same sectors, which might cross on the queue (if they're reallocated quickly enough). Callers still _can_ issue non-barrier discard requests, but they have to take care of queue ordering for themselves. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/elevator.c')
-rw-r--r--block/elevator.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/block/elevator.c b/block/elevator.c
index ed6f8f32d27e..4f5127054e3f 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -75,6 +75,12 @@ int elv_rq_merge_ok(struct request *rq, struct bio *bio)
return 0;
/*
+ * Don't merge file system requests and discard requests
+ */
+ if (bio_discard(bio) != bio_discard(rq->bio))
+ return 0;
+
+ /*
* different data direction or already started, don't merge
*/
if (bio_data_dir(bio) != rq_data_dir(rq))
@@ -438,6 +444,8 @@ void elv_dispatch_sort(struct request_queue *q, struct request *rq)
list_for_each_prev(entry, &q->queue_head) {
struct request *pos = list_entry_rq(entry);
+ if (blk_discard_rq(rq) != blk_discard_rq(pos))
+ break;
if (rq_data_dir(rq) != rq_data_dir(pos))
break;
if (pos->cmd_flags & stop_flags)
@@ -607,7 +615,7 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
break;
case ELEVATOR_INSERT_SORT:
- BUG_ON(!blk_fs_request(rq));
+ BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq));
rq->cmd_flags |= REQ_SORTED;
q->nr_sorted++;
if (rq_mergeable(rq)) {
@@ -692,7 +700,7 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where,
* this request is scheduling boundary, update
* end_sector
*/
- if (blk_fs_request(rq)) {
+ if (blk_fs_request(rq) || blk_discard_rq(rq)) {
q->end_sector = rq_end_sector(rq);
q->boundary_rq = rq;
}