mmc_block: add discard support
Enable MMC to service discard requests. In the case of SD and MMC cards
that do not support trim, discards become erases. In the case of cards
(MMC) that only allow erases in multiples of erase group size, round to
the nearest completely discarded erase group.
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Madhusudhan Chikkature <madhu.cr@ti.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ben Gardiner <bengardiner@nanometrics.ca>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index c77eb49..3b15884 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -30,9 +30,9 @@
static int mmc_prep_request(struct request_queue *q, struct request *req)
{
/*
- * We only like normal block requests.
+ * We only like normal block requests and discards.
*/
- if (req->cmd_type != REQ_TYPE_FS) {
+ if (req->cmd_type != REQ_TYPE_FS && !(req->cmd_flags & REQ_DISCARD)) {
blk_dump_rq_flags(req, "MMC bad request");
return BLKPREP_KILL;
}
@@ -130,6 +130,18 @@
blk_queue_prep_rq(mq->queue, mmc_prep_request);
blk_queue_ordered(mq->queue, QUEUE_ORDERED_DRAIN);
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
+ if (mmc_can_erase(card)) {
+ queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mq->queue);
+ mq->queue->limits.max_discard_sectors = UINT_MAX;
+ if (card->erased_byte == 0)
+ mq->queue->limits.discard_zeroes_data = 1;
+ if (!mmc_can_trim(card) && is_power_of_2(card->erase_size)) {
+ mq->queue->limits.discard_granularity =
+ card->erase_size << 9;
+ mq->queue->limits.discard_alignment =
+ card->erase_size << 9;
+ }
+ }
#ifdef CONFIG_MMC_BLOCK_BOUNCE
if (host->max_hw_segs == 1) {