>>> On 18.08.11 at 11:35, Li Dongyang <lidongyang@xxxxxxxxxx> wrote:
> JBeulich@xxxxxxxxxx
> Subject: [PATCH V2 2/3] xen-blkfront: teach blkfront driver handle trim
> request
> Date: Thu, 18 Aug 2011 17:34:30 +0800
> Message-Id: <1313660071-25230-3-git-send-email-lidongyang@xxxxxxxxxx>
> X-Mailer: git-send-email 1.7.6
> In-Reply-To: <1313660071-25230-1-git-send-email-lidongyang@xxxxxxxxxx>
> References: <1313660071-25230-1-git-send-email-lidongyang@xxxxxxxxxx>
>
> The blkfront driver now will read feature-trim from xenstore,
> and set up the request queue with trim params, then we can forward the
> discard requests to backend driver.
>
> Signed-off-by: Li Dongyang <lidongyang@xxxxxxxxxx>
> ---
> drivers/block/xen-blkfront.c | 96
> ++++++++++++++++++++++++++++++++----------
> 1 files changed, 73 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index b536a9c..c22fb07 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -98,6 +98,9 @@ struct blkfront_info
> unsigned long shadow_free;
> unsigned int feature_flush;
> unsigned int flush_op;
> + unsigned int feature_trim;
> + unsigned int discard_granularity;
> + unsigned int discard_alignment;
> int is_ready;
> };
>
> @@ -302,29 +305,36 @@ static int blkif_queue_request(struct request *req)
> ring_req->operation = info->flush_op;
> }
>
> - ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
> - BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
> + if (unlikely(req->cmd_flags & REQ_DISCARD)) {
> + /* id, sector_number and handle are set above. */
> + ring_req->operation = BLKIF_OP_TRIM;
> + ring_req->nr_segments = 0;
> + ring_req->u.trim.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);
>
> - for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
> - buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
> - fsect = sg->offset >> 9;
> - lsect = fsect + (sg->length >> 9) - 1;
> - /* install a grant reference. */
> - ref = gnttab_claim_grant_reference(&gref_head);
> - BUG_ON(ref == -ENOSPC);
> + for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
> + buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
> + fsect = sg->offset >> 9;
> + lsect = fsect + (sg->length >> 9) - 1;
> + /* install a grant reference. */
> + ref = gnttab_claim_grant_reference(&gref_head);
> + BUG_ON(ref == -ENOSPC);
>
> - gnttab_grant_foreign_access_ref(
> - ref,
> - info->xbdev->otherend_id,
> - buffer_mfn,
> - rq_data_dir(req) );
> -
> - info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
> - ring_req->u.rw.seg[i] =
> - (struct blkif_request_segment) {
> - .gref = ref,
> - .first_sect = fsect,
> - .last_sect = lsect };
> + gnttab_grant_foreign_access_ref(
> + ref,
> + info->xbdev->otherend_id,
> + buffer_mfn,
> + rq_data_dir(req));
> +
> + info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
> + ring_req->u.rw.seg[i] =
> + (struct blkif_request_segment) {
> + .gref = ref,
> + .first_sect = fsect,
> + .last_sect = lsect };
> + }
> }
>
> info->ring.req_prod_pvt++;
> @@ -399,6 +409,7 @@ wait:
> 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_trim) {
> + 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_TRIM:
> + if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
> + struct request_queue *rq = info->rq;
> + printk(KERN_WARNING "blkfront: %s: trim op
> failed\n",
> + info->gd->disk_name);
> + error = -EOPNOTSUPP;
> + info->feature_trim = 0;
> + spin_lock_irq(rq->queue_lock);
> + queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
> + spin_unlock_irq(rq->queue_lock);
Are you sure you want to re-enable interrupts here unconditionally?
> + }
> + __blk_end_request_all(req, error);
> + break;
> case BLKIF_OP_FLUSH_DISKCACHE:
> case BLKIF_OP_WRITE_BARRIER:
> if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
> @@ -1108,7 +1139,9 @@ static void blkfront_connect(struct blkfront_info
> *info)
> unsigned long sector_size;
> unsigned int binfo;
> int err;
> - int barrier, flush;
> + unsigned int discard_granularity;
> + unsigned int discard_alignment;
> + int barrier, flush, trim;
>
> switch (info->connected) {
> case BLKIF_STATE_CONNECTED:
> @@ -1178,7 +1211,24 @@ static void blkfront_connect(struct blkfront_info
> *info)
> info->feature_flush = REQ_FLUSH;
> info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
> }
> -
> +
> + err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
> + "feature-trim", "%d", &trim,
> + NULL);
So you switched this to use "trim", but ...
> +
> + if (!err && trim) {
> + info->feature_trim = 1;
> + err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
> + "discard_granularity", "%u", &discard_granularity,
> + "discard_alignment", "%u", &discard_alignment,
... you kept these using "discard" - quite inconsistent.
Also, I think (but I may be wrong) that dashes are preferred over
underscores in xenstore node names.
> + NULL);
> + if (!err) {
> + info->discard_granularity = discard_granularity;
> + info->discard_alignment = discard_alignment;
I think you should set info->feature_trim only here (and then you can
eliminate the local variables).
Jan
> + }
> + } else
> + info->feature_trim = 0;
> +
> err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
> if (err) {
> xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
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