loop: implement REQ_OP_WRITE_ZEROES

It's identical to discard as hole punches will always leave us with
zeroes on reads.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index cc981f34e0177022c31be6711de53b25742076c2..3bb04c1a4ba16d3acc612ae4547485df75e6b864 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -528,6 +528,7 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
        case REQ_OP_FLUSH:
                return lo_req_flush(lo, rq);
        case REQ_OP_DISCARD:
+       case REQ_OP_WRITE_ZEROES:
                return lo_discard(lo, rq, pos);
        case REQ_OP_WRITE:
                if (lo->transfer)
@@ -826,6 +827,7 @@ static void loop_config_discard(struct loop_device *lo)
                q->limits.discard_granularity = 0;
                q->limits.discard_alignment = 0;
                blk_queue_max_discard_sectors(q, 0);
+               blk_queue_max_write_zeroes_sectors(q, 0);
                q->limits.discard_zeroes_data = 0;
                queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
                return;
@@ -834,6 +836,7 @@ static void loop_config_discard(struct loop_device *lo)
        q->limits.discard_granularity = inode->i_sb->s_blocksize;
        q->limits.discard_alignment = 0;
        blk_queue_max_discard_sectors(q, UINT_MAX >> 9);
+       blk_queue_max_write_zeroes_sectors(q, UINT_MAX >> 9);
        q->limits.discard_zeroes_data = 1;
        queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
 }
@@ -1660,6 +1663,7 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
        switch (req_op(cmd->rq)) {
        case REQ_OP_FLUSH:
        case REQ_OP_DISCARD:
+       case REQ_OP_WRITE_ZEROES:
                cmd->use_aio = false;
                break;
        default: