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block/xen-blkfront: Split blkif_queue_request in 2
Currently, blkif_queue_request has 2 distinct execution path:
- Send a discard request
- Send a read/write request
The function is also allocating grants to use for generating the
request. Although, this is only used for read/write request.
Rather than having a function with 2 distinct execution path, separate
the function in 2. This will also remove one level of tabulation.
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
This commit is contained in:
Julien Grall
David Vrabel
parent
3922f32c1e
commit
33204663ef
@ -394,13 +394,35 @@ static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
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return 0;
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}
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/*
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* Generate a Xen blkfront IO request from a blk layer request. Reads
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* and writes are handled as expected.
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*
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* @req: a request struct
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*/
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static int blkif_queue_request(struct request *req)
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static int blkif_queue_discard_req(struct request *req)
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{
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struct blkfront_info *info = req->rq_disk->private_data;
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struct blkif_request *ring_req;
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unsigned long id;
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/* Fill out a communications ring structure. */
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ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
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id = get_id_from_freelist(info);
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info->shadow[id].request = req;
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ring_req->operation = BLKIF_OP_DISCARD;
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ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
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ring_req->u.discard.id = id;
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ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
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if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
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ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
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else
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ring_req->u.discard.flag = 0;
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info->ring.req_prod_pvt++;
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/* Keep a private copy so we can reissue requests when recovering. */
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info->shadow[id].req = *ring_req;
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return 0;
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}
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static int blkif_queue_rw_req(struct request *req)
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{
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struct blkfront_info *info = req->rq_disk->private_data;
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struct blkif_request *ring_req;
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@ -420,9 +442,6 @@ static int blkif_queue_request(struct request *req)
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struct scatterlist *sg;
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int nseg, max_grefs;
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if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
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return 1;
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max_grefs = req->nr_phys_segments;
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if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
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/*
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@ -452,139 +471,131 @@ static int blkif_queue_request(struct request *req)
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id = get_id_from_freelist(info);
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info->shadow[id].request = req;
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if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) {
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ring_req->operation = BLKIF_OP_DISCARD;
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ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
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ring_req->u.discard.id = id;
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ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
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if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
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ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
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else
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ring_req->u.discard.flag = 0;
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BUG_ON(info->max_indirect_segments == 0 &&
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req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
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BUG_ON(info->max_indirect_segments &&
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req->nr_phys_segments > info->max_indirect_segments);
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nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
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ring_req->u.rw.id = id;
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if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
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/*
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* The indirect operation can only be a BLKIF_OP_READ or
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* BLKIF_OP_WRITE
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*/
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BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
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ring_req->operation = BLKIF_OP_INDIRECT;
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ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
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BLKIF_OP_WRITE : BLKIF_OP_READ;
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ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
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ring_req->u.indirect.handle = info->handle;
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ring_req->u.indirect.nr_segments = nseg;
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} else {
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BUG_ON(info->max_indirect_segments == 0 &&
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req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
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BUG_ON(info->max_indirect_segments &&
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req->nr_phys_segments > info->max_indirect_segments);
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nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
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ring_req->u.rw.id = id;
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if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
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ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
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ring_req->u.rw.handle = info->handle;
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ring_req->operation = rq_data_dir(req) ?
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BLKIF_OP_WRITE : BLKIF_OP_READ;
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if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
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/*
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* The indirect operation can only be a BLKIF_OP_READ or
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* BLKIF_OP_WRITE
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* Ideally we can do an unordered flush-to-disk.
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* In case the backend onlysupports barriers, use that.
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* A barrier request a superset of FUA, so we can
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* implement it the same way. (It's also a FLUSH+FUA,
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* since it is guaranteed ordered WRT previous writes.)
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*/
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BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
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ring_req->operation = BLKIF_OP_INDIRECT;
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ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
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BLKIF_OP_WRITE : BLKIF_OP_READ;
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ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
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ring_req->u.indirect.handle = info->handle;
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ring_req->u.indirect.nr_segments = nseg;
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} else {
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ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
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ring_req->u.rw.handle = info->handle;
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ring_req->operation = rq_data_dir(req) ?
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BLKIF_OP_WRITE : BLKIF_OP_READ;
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if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
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/*
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* Ideally we can do an unordered flush-to-disk. In case the
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* backend onlysupports barriers, use that. A barrier request
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* a superset of FUA, so we can implement it the same
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* way. (It's also a FLUSH+FUA, since it is
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* guaranteed ordered WRT previous writes.)
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*/
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switch (info->feature_flush &
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((REQ_FLUSH|REQ_FUA))) {
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case REQ_FLUSH|REQ_FUA:
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ring_req->operation =
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BLKIF_OP_WRITE_BARRIER;
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break;
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case REQ_FLUSH:
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ring_req->operation =
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BLKIF_OP_FLUSH_DISKCACHE;
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break;
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default:
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ring_req->operation = 0;
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}
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}
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ring_req->u.rw.nr_segments = nseg;
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}
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for_each_sg(info->shadow[id].sg, sg, nseg, i) {
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fsect = sg->offset >> 9;
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lsect = fsect + (sg->length >> 9) - 1;
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if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
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(i % SEGS_PER_INDIRECT_FRAME == 0)) {
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unsigned long uninitialized_var(pfn);
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if (segments)
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kunmap_atomic(segments);
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n = i / SEGS_PER_INDIRECT_FRAME;
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if (!info->feature_persistent) {
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struct page *indirect_page;
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/* Fetch a pre-allocated page to use for indirect grefs */
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BUG_ON(list_empty(&info->indirect_pages));
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indirect_page = list_first_entry(&info->indirect_pages,
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struct page, lru);
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list_del(&indirect_page->lru);
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pfn = page_to_pfn(indirect_page);
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}
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gnt_list_entry = get_grant(&gref_head, pfn, info);
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info->shadow[id].indirect_grants[n] = gnt_list_entry;
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segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
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ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
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}
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gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info);
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ref = gnt_list_entry->gref;
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info->shadow[id].grants_used[i] = gnt_list_entry;
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if (rq_data_dir(req) && info->feature_persistent) {
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char *bvec_data;
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void *shared_data;
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BUG_ON(sg->offset + sg->length > PAGE_SIZE);
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shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
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bvec_data = kmap_atomic(sg_page(sg));
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/*
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* this does not wipe data stored outside the
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* range sg->offset..sg->offset+sg->length.
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* Therefore, blkback *could* see data from
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* previous requests. This is OK as long as
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* persistent grants are shared with just one
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* domain. It may need refactoring if this
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* changes
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*/
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memcpy(shared_data + sg->offset,
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bvec_data + sg->offset,
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sg->length);
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kunmap_atomic(bvec_data);
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kunmap_atomic(shared_data);
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}
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if (ring_req->operation != BLKIF_OP_INDIRECT) {
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ring_req->u.rw.seg[i] =
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(struct blkif_request_segment) {
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.gref = ref,
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.first_sect = fsect,
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.last_sect = lsect };
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} else {
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n = i % SEGS_PER_INDIRECT_FRAME;
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segments[n] =
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(struct blkif_request_segment) {
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.gref = ref,
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.first_sect = fsect,
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.last_sect = lsect };
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switch (info->feature_flush &
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((REQ_FLUSH|REQ_FUA))) {
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case REQ_FLUSH|REQ_FUA:
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ring_req->operation =
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BLKIF_OP_WRITE_BARRIER;
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break;
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case REQ_FLUSH:
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ring_req->operation =
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BLKIF_OP_FLUSH_DISKCACHE;
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break;
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default:
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ring_req->operation = 0;
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}
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}
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if (segments)
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kunmap_atomic(segments);
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ring_req->u.rw.nr_segments = nseg;
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}
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for_each_sg(info->shadow[id].sg, sg, nseg, i) {
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fsect = sg->offset >> 9;
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lsect = fsect + (sg->length >> 9) - 1;
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if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
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(i % SEGS_PER_INDIRECT_FRAME == 0)) {
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unsigned long uninitialized_var(pfn);
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if (segments)
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kunmap_atomic(segments);
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n = i / SEGS_PER_INDIRECT_FRAME;
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if (!info->feature_persistent) {
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struct page *indirect_page;
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/*
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* Fetch a pre-allocated page to use for
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* indirect grefs
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*/
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BUG_ON(list_empty(&info->indirect_pages));
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indirect_page = list_first_entry(&info->indirect_pages,
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struct page, lru);
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list_del(&indirect_page->lru);
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pfn = page_to_pfn(indirect_page);
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}
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gnt_list_entry = get_grant(&gref_head, pfn, info);
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info->shadow[id].indirect_grants[n] = gnt_list_entry;
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segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
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ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
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}
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gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info);
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ref = gnt_list_entry->gref;
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info->shadow[id].grants_used[i] = gnt_list_entry;
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if (rq_data_dir(req) && info->feature_persistent) {
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char *bvec_data;
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void *shared_data;
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BUG_ON(sg->offset + sg->length > PAGE_SIZE);
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shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
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bvec_data = kmap_atomic(sg_page(sg));
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/*
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* this does not wipe data stored outside the
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* range sg->offset..sg->offset+sg->length.
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* Therefore, blkback *could* see data from
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* previous requests. This is OK as long as
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* persistent grants are shared with just one
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* domain. It may need refactoring if this
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* changes
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*/
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memcpy(shared_data + sg->offset,
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bvec_data + sg->offset,
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sg->length);
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kunmap_atomic(bvec_data);
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kunmap_atomic(shared_data);
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}
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if (ring_req->operation != BLKIF_OP_INDIRECT) {
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ring_req->u.rw.seg[i] =
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(struct blkif_request_segment) {
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.gref = ref,
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.first_sect = fsect,
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.last_sect = lsect };
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} else {
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n = i % SEGS_PER_INDIRECT_FRAME;
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segments[n] =
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(struct blkif_request_segment) {
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.gref = ref,
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.first_sect = fsect,
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.last_sect = lsect };
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}
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}
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if (segments)
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kunmap_atomic(segments);
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info->ring.req_prod_pvt++;
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@ -597,6 +608,24 @@ static int blkif_queue_request(struct request *req)
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return 0;
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}
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/*
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* Generate a Xen blkfront IO request from a blk layer request. Reads
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* and writes are handled as expected.
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*
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* @req: a request struct
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*/
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static int blkif_queue_request(struct request *req)
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{
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struct blkfront_info *info = req->rq_disk->private_data;
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if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
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return 1;
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if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE)))
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return blkif_queue_discard_req(req);
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else
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return blkif_queue_rw_req(req);
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}
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static inline void flush_requests(struct blkfront_info *info)
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{
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Block a user