[PATCH RFC 2/3] loop: Forward REQ_OP_ASSIGN_RANGE into fallocate(0)

[Kirill Tkhai <ktkhai@virtuozzo.com>]

Send fallocate(0) request into underlining filesystem
after upper filesystem sent REQ_OP_ASSIGN_RANGE request
to block device.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
 drivers/block/loop.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 739b372a5112..d99d9193de7a 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -609,6 +609,8 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
 				FALLOC_FL_PUNCH_HOLE);
 	case REQ_OP_DISCARD:
 		return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
+	case REQ_OP_ASSIGN_RANGE:
+		return lo_fallocate(lo, rq, pos, 0);
 	case REQ_OP_WRITE:
 		if (lo->transfer)
 			return lo_write_transfer(lo, rq, pos);
@@ -875,6 +877,7 @@ static void loop_config_discard(struct loop_device *lo)
 	    lo->lo_encrypt_key_size) {
 		q->limits.discard_granularity = 0;
 		q->limits.discard_alignment = 0;
+		q->limits.max_assign_range_sectors = 0;
 		blk_queue_max_discard_sectors(q, 0);
 		blk_queue_max_write_zeroes_sectors(q, 0);
 		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
@@ -883,6 +886,7 @@ static void loop_config_discard(struct loop_device *lo)
 
 	q->limits.discard_granularity = inode->i_sb->s_blocksize;
 	q->limits.discard_alignment = 0;
+	q->limits.max_assign_range_sectors = UINT_MAX >> 9;
 
 	blk_queue_max_discard_sectors(q, UINT_MAX >> 9);
 	blk_queue_max_write_zeroes_sectors(q, UINT_MAX >> 9);
@@ -1917,6 +1921,7 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
 	case REQ_OP_FLUSH:
 	case REQ_OP_DISCARD:
 	case REQ_OP_WRITE_ZEROES:
+	case REQ_OP_ASSIGN_RANGE:
 		cmd->use_aio = false;
 		break;
 	default: