On Thu, Jan 24, 2019 at 06:23:22PM +0100, Stefano Garzarella wrote:
> @@ -584,6 +603,56 @@ static int virtio_blk_handle_request(VirtIOBlockReq
> *req, MultiReqBuffer *mrb)
> virtio_blk_free_request(req);
> break;
> }
> + /*
> + * VIRTIO_BLK_T_DISCARD and VIRTIO_BLK_T_WRITE_ZEROES are defined with
> + * VIRTIO_BLK_T_OUT flag set. We masked this flag in the switch
> statement,
> + * so we must mask it for these requests, then we will check the type.
> + */
> + case VIRTIO_BLK_T_DISCARD & ~VIRTIO_BLK_T_OUT:
> + case VIRTIO_BLK_T_WRITE_ZEROES & ~VIRTIO_BLK_T_OUT:
> + {
> + struct virtio_blk_discard_write_zeroes dwz_hdr;
> + uint64_t sector;
> + int bytes;
> +
> + if (unlikely(iov_to_buf(out_iov, out_num, 0, &dwz_hdr,
> + sizeof(dwz_hdr)) != sizeof(dwz_hdr))) {
"The data used for discard or write zeroes command is described by one
or more virtio_blk_discard_write_zeroes structs."
This needs to be a loop so that multiple dwz structs can be processed up
to the length of virtio_blk_req->data[].
> + virtio_error(vdev, "virtio-blk discard/wzeroes header too
> short");
> + return -1;
> + }
> +
> + sector = virtio_ldq_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.sector);
> + bytes = virtio_ldl_p(VIRTIO_DEVICE(req->dev),
> + &dwz_hdr.num_sectors) << BDRV_SECTOR_BITS;
Please handle num_sectors << BDRV_SECTOR_BITS overflow so that we don't
need to worry about what happens with an overflowed value later on.
> +
> + if (!virtio_blk_sect_range_ok(req->dev, sector, bytes)) {
> + virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
> + virtio_blk_free_request(req);
> + return 0;
> + }
> +
> + if ((type & ~(VIRTIO_BLK_T_BARRIER)) == VIRTIO_BLK_T_DISCARD) {
Missing device requirement: "the device MUST set the status byte to
VIRTIO_BLK_S_UNSUPP for discard commands if the unmap flag is set."
> + blk_aio_pdiscard(req->dev->blk, sector << BDRV_SECTOR_BITS,
> bytes,
> + virtio_blk_discard_wzeroes_complete, req);
> + } else if ((type & ~(VIRTIO_BLK_T_BARRIER)) ==
> + VIRTIO_BLK_T_WRITE_ZEROES) {
> + int flags = 0;
> +
> + if (virtio_ldl_p(VIRTIO_DEVICE(req->dev), &dwz_hdr.flags) &
> + VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) {
> + flags |= BDRV_REQ_MAY_UNMAP;
> + }
> +
> + blk_aio_pwrite_zeroes(req->dev->blk, sector << BDRV_SECTOR_BITS,
> + bytes, flags,
> + virtio_blk_discard_wzeroes_complete, req);
Please add block_acct_start(), this is treated as a write.
> + } else { /* Unsupported if VIRTIO_BLK_T_OUT is not set */
> + virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
> + virtio_blk_free_request(req);
> + }
> +
> + break;
> + }
> default:
> virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
> virtio_blk_free_request(req);
> @@ -763,6 +832,14 @@ static void virtio_blk_update_config(VirtIODevice *vdev,
> uint8_t *config)
> blkcfg.alignment_offset = 0;
> blkcfg.wce = blk_enable_write_cache(s->blk);
> virtio_stw_p(vdev, &blkcfg.num_queues, s->conf.num_queues);
> + virtio_stl_p(vdev, &blkcfg.max_discard_sectors,
> BDRV_REQUEST_MAX_SECTORS);
> + virtio_stl_p(vdev, &blkcfg.max_discard_seg, 1);
> + virtio_stl_p(vdev, &blkcfg.discard_sector_alignment,
> + blk_size >> BDRV_SECTOR_BITS);
> + virtio_stl_p(vdev, &blkcfg.max_write_zeroes_sectors,
> + BDRV_REQUEST_MAX_SECTORS);
> + virtio_stl_p(vdev, &blkcfg.max_write_zeroes_seg, 1);
> + blkcfg.write_zeroes_may_unmap = 1;
Please check hw/scsi/scsi-disk.c for an example of how to initialize
these limits. It should be possible to set some of them via s->conf so
I'm surprised so many fields are hardcoded in this patch.
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