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Commit ed30bf31 authored by Li Dongyang's avatar Li Dongyang Committed by Konrad Rzeszutek Wilk
Browse files

xen-blkfront: Handle discard requests. 



If the backend advertises 'feature-discard', then interrogate
the backend for alignment and granularity. Setup the request
queue with the appropiate values and send the discard operation
as required.

Signed-off-by: default avatarLi Dongyang <lidongyang@novell.com>
[v1: Amended commit description]
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent b3cb0d6a

drivers/block/xen-blkfront.c

+88 −23
Original line number Diff line number Diff line
@@ -98,6 +98,9 @@ struct blkfront_info 
	unsigned long shadow_free;

	unsigned int feature_flush;

	unsigned int flush_op;

	unsigned int feature_discard;

	unsigned int discard_granularity;

	unsigned int discard_alignment;

	int is_ready;

};
@@ -302,6 +305,12 @@ static int blkif_queue_request(struct request *req) 
		ring_req->operation = info->flush_op;

	}



	if (unlikely(req->cmd_flags & REQ_DISCARD)) {

		/* id, sector_number and handle are set above. */

		ring_req->operation = BLKIF_OP_DISCARD;

		ring_req->nr_segments = 0;

		ring_req->u.discard.nr_sectors = blk_rq_sectors(req);

	} else {

		ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);

		BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
@@ -326,6 +335,7 @@ static int blkif_queue_request(struct request *req) 
						.first_sect = fsect,

						.last_sect  = lsect };

		}

	}



	info->ring.req_prod_pvt++;
@@ -399,6 +409,7 @@ static void do_blkif_request(struct request_queue *rq) 
static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)

{

	struct request_queue *rq;

	struct blkfront_info *info = gd->private_data;



	rq = blk_init_queue(do_blkif_request, &blkif_io_lock);

	if (rq == NULL)
@@ -406,6 +417,13 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size) 


	queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);



	if (info->feature_discard) {

		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);

		blk_queue_max_discard_sectors(rq, get_capacity(gd));

		rq->limits.discard_granularity = info->discard_granularity;

		rq->limits.discard_alignment = info->discard_alignment;

	}



	/* Hard sector size and max sectors impersonate the equiv. hardware. */

	blk_queue_logical_block_size(rq, sector_size);

	blk_queue_max_hw_sectors(rq, 512);
@@ -722,6 +740,19 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) 


		error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;

		switch (bret->operation) {

		case BLKIF_OP_DISCARD:

			if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {

				struct request_queue *rq = info->rq;

				printk(KERN_WARNING "blkfront: %s: discard op failed\n",

					   info->gd->disk_name);

				error = -EOPNOTSUPP;

				info->feature_discard = 0;

				spin_lock(rq->queue_lock);

				queue_flag_clear(QUEUE_FLAG_DISCARD, rq);

				spin_unlock(rq->queue_lock);

			}

			__blk_end_request_all(req, error);

			break;

		case BLKIF_OP_FLUSH_DISKCACHE:

		case BLKIF_OP_WRITE_BARRIER:

			if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
@@ -1098,6 +1129,33 @@ blkfront_closing(struct blkfront_info *info) 
	bdput(bdev);

}



static void blkfront_setup_discard(struct blkfront_info *info)

{

	int err;

	char *type;

	unsigned int discard_granularity;

	unsigned int discard_alignment;



	type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);

	if (IS_ERR(type))

		return;



	if (strncmp(type, "phy", 3) == 0) {

		err = xenbus_gather(XBT_NIL, info->xbdev->otherend,

			"discard-granularity", "%u", &discard_granularity,

			"discard-alignment", "%u", &discard_alignment,

			NULL);

		if (!err) {

			info->feature_discard = 1;

			info->discard_granularity = discard_granularity;

			info->discard_alignment = discard_alignment;

		}

	} else if (strncmp(type, "file", 4) == 0)

		info->feature_discard = 1;



	kfree(type);

}



/*

 * Invoked when the backend is finally 'ready' (and has told produced

 * the details about the physical device - #sectors, size, etc).
@@ -1108,7 +1166,7 @@ static void blkfront_connect(struct blkfront_info *info) 
	unsigned long sector_size;

	unsigned int binfo;

	int err;

	int barrier, flush;

	int barrier, flush, discard;



	switch (info->connected) {

	case BLKIF_STATE_CONNECTED:
@@ -1179,6 +1237,13 @@ static void blkfront_connect(struct blkfront_info *info) 
		info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;

	}



	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,

			    "feature-discard", "%d", &discard,

			    NULL);



	if (!err && discard)

		blkfront_setup_discard(info);



	err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);

	if (err) {

		xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",