From 33204663ef85d9ce79009b2246afe6a2fef8eb1b Mon Sep 17 00:00:00 2001 From: Julien Grall Date: Mon, 29 Jun 2015 17:35:24 +0100 Subject: block/xen-blkfront: Split blkif_queue_request in 2 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Roger Pau Monné Signed-off-by: David Vrabel --- drivers/block/xen-blkfront.c | 277 ++++++++++++++++++++++++------------------- 1 file changed, 153 insertions(+), 124 deletions(-) (limited to 'drivers/block/xen-blkfront.c') diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 611170896b8c..bf9ccfe03f45 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -394,13 +394,35 @@ static int blkif_ioctl(struct block_device *bdev, fmode_t mode, return 0; } -/* - * Generate a Xen blkfront IO request from a blk layer request. Reads - * and writes are handled as expected. - * - * @req: a request struct - */ -static int blkif_queue_request(struct request *req) +static int blkif_queue_discard_req(struct request *req) +{ + struct blkfront_info *info = req->rq_disk->private_data; + struct blkif_request *ring_req; + unsigned long id; + + /* Fill out a communications ring structure. */ + ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); + id = get_id_from_freelist(info); + info->shadow[id].request = req; + + ring_req->operation = BLKIF_OP_DISCARD; + ring_req->u.discard.nr_sectors = blk_rq_sectors(req); + ring_req->u.discard.id = id; + ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); + if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard) + ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; + else + ring_req->u.discard.flag = 0; + + info->ring.req_prod_pvt++; + + /* Keep a private copy so we can reissue requests when recovering. */ + info->shadow[id].req = *ring_req; + + return 0; +} + +static int blkif_queue_rw_req(struct request *req) { struct blkfront_info *info = req->rq_disk->private_data; struct blkif_request *ring_req; @@ -420,9 +442,6 @@ static int blkif_queue_request(struct request *req) struct scatterlist *sg; int nseg, max_grefs; - if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) - return 1; - max_grefs = req->nr_phys_segments; if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) /* @@ -452,139 +471,131 @@ static int blkif_queue_request(struct request *req) id = get_id_from_freelist(info); info->shadow[id].request = req; - if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) { - ring_req->operation = BLKIF_OP_DISCARD; - ring_req->u.discard.nr_sectors = blk_rq_sectors(req); - ring_req->u.discard.id = id; - ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); - if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard) - ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; - else - ring_req->u.discard.flag = 0; + BUG_ON(info->max_indirect_segments == 0 && + req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST); + BUG_ON(info->max_indirect_segments && + req->nr_phys_segments > info->max_indirect_segments); + nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg); + ring_req->u.rw.id = id; + if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) { + /* + * The indirect operation can only be a BLKIF_OP_READ or + * BLKIF_OP_WRITE + */ + BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA)); + ring_req->operation = BLKIF_OP_INDIRECT; + ring_req->u.indirect.indirect_op = rq_data_dir(req) ? + BLKIF_OP_WRITE : BLKIF_OP_READ; + ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); + ring_req->u.indirect.handle = info->handle; + ring_req->u.indirect.nr_segments = nseg; } else { - BUG_ON(info->max_indirect_segments == 0 && - req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST); - BUG_ON(info->max_indirect_segments && - req->nr_phys_segments > info->max_indirect_segments); - nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg); - ring_req->u.rw.id = id; - if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) { + ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); + ring_req->u.rw.handle = info->handle; + ring_req->operation = rq_data_dir(req) ? + BLKIF_OP_WRITE : BLKIF_OP_READ; + if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { /* - * The indirect operation can only be a BLKIF_OP_READ or - * BLKIF_OP_WRITE + * Ideally we can do an unordered flush-to-disk. + * In case the backend onlysupports barriers, use that. + * A barrier request a superset of FUA, so we can + * implement it the same way. (It's also a FLUSH+FUA, + * since it is guaranteed ordered WRT previous writes.) */ - BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA)); - ring_req->operation = BLKIF_OP_INDIRECT; - ring_req->u.indirect.indirect_op = rq_data_dir(req) ? - BLKIF_OP_WRITE : BLKIF_OP_READ; - ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); - ring_req->u.indirect.handle = info->handle; - ring_req->u.indirect.nr_segments = nseg; - } else { - ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); - ring_req->u.rw.handle = info->handle; - ring_req->operation = rq_data_dir(req) ? - BLKIF_OP_WRITE : BLKIF_OP_READ; - if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { - /* - * Ideally we can do an unordered flush-to-disk. In case the - * backend onlysupports barriers, use that. A barrier request - * a superset of FUA, so we can implement it the same - * way. (It's also a FLUSH+FUA, since it is - * guaranteed ordered WRT previous writes.) - */ - switch (info->feature_flush & - ((REQ_FLUSH|REQ_FUA))) { - case REQ_FLUSH|REQ_FUA: - ring_req->operation = - BLKIF_OP_WRITE_BARRIER; - break; - case REQ_FLUSH: - ring_req->operation = - BLKIF_OP_FLUSH_DISKCACHE; - break; - default: - ring_req->operation = 0; - } + switch (info->feature_flush & + ((REQ_FLUSH|REQ_FUA))) { + case REQ_FLUSH|REQ_FUA: + ring_req->operation = + BLKIF_OP_WRITE_BARRIER; + break; + case REQ_FLUSH: + ring_req->operation = + BLKIF_OP_FLUSH_DISKCACHE; + break; + default: + ring_req->operation = 0; } - ring_req->u.rw.nr_segments = nseg; } - for_each_sg(info->shadow[id].sg, sg, nseg, i) { - fsect = sg->offset >> 9; - lsect = fsect + (sg->length >> 9) - 1; + ring_req->u.rw.nr_segments = nseg; + } + for_each_sg(info->shadow[id].sg, sg, nseg, i) { + fsect = sg->offset >> 9; + lsect = fsect + (sg->length >> 9) - 1; - if ((ring_req->operation == BLKIF_OP_INDIRECT) && - (i % SEGS_PER_INDIRECT_FRAME == 0)) { - unsigned long uninitialized_var(pfn); + if ((ring_req->operation == BLKIF_OP_INDIRECT) && + (i % SEGS_PER_INDIRECT_FRAME == 0)) { + unsigned long uninitialized_var(pfn); - if (segments) - kunmap_atomic(segments); + if (segments) + kunmap_atomic(segments); - n = i / SEGS_PER_INDIRECT_FRAME; - if (!info->feature_persistent) { - struct page *indirect_page; - - /* Fetch a pre-allocated page to use for indirect grefs */ - BUG_ON(list_empty(&info->indirect_pages)); - indirect_page = list_first_entry(&info->indirect_pages, - struct page, lru); - list_del(&indirect_page->lru); - pfn = page_to_pfn(indirect_page); - } - gnt_list_entry = get_grant(&gref_head, pfn, info); - info->shadow[id].indirect_grants[n] = gnt_list_entry; - segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); - ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; + n = i / SEGS_PER_INDIRECT_FRAME; + if (!info->feature_persistent) { + struct page *indirect_page; + + /* + * Fetch a pre-allocated page to use for + * indirect grefs + */ + BUG_ON(list_empty(&info->indirect_pages)); + indirect_page = list_first_entry(&info->indirect_pages, + struct page, lru); + list_del(&indirect_page->lru); + pfn = page_to_pfn(indirect_page); } + gnt_list_entry = get_grant(&gref_head, pfn, info); + info->shadow[id].indirect_grants[n] = gnt_list_entry; + segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); + ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; + } - gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info); - ref = gnt_list_entry->gref; + gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info); + ref = gnt_list_entry->gref; - info->shadow[id].grants_used[i] = gnt_list_entry; + info->shadow[id].grants_used[i] = gnt_list_entry; - if (rq_data_dir(req) && info->feature_persistent) { - char *bvec_data; - void *shared_data; + if (rq_data_dir(req) && info->feature_persistent) { + char *bvec_data; + void *shared_data; - BUG_ON(sg->offset + sg->length > PAGE_SIZE); + BUG_ON(sg->offset + sg->length > PAGE_SIZE); - shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); - bvec_data = kmap_atomic(sg_page(sg)); + shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); + bvec_data = kmap_atomic(sg_page(sg)); - /* - * this does not wipe data stored outside the - * range sg->offset..sg->offset+sg->length. - * Therefore, blkback *could* see data from - * previous requests. This is OK as long as - * persistent grants are shared with just one - * domain. It may need refactoring if this - * changes - */ - memcpy(shared_data + sg->offset, - bvec_data + sg->offset, - sg->length); + /* + * this does not wipe data stored outside the + * range sg->offset..sg->offset+sg->length. + * Therefore, blkback *could* see data from + * previous requests. This is OK as long as + * persistent grants are shared with just one + * domain. It may need refactoring if this + * changes + */ + memcpy(shared_data + sg->offset, + bvec_data + sg->offset, + sg->length); - kunmap_atomic(bvec_data); - kunmap_atomic(shared_data); - } - if (ring_req->operation != BLKIF_OP_INDIRECT) { - ring_req->u.rw.seg[i] = - (struct blkif_request_segment) { - .gref = ref, - .first_sect = fsect, - .last_sect = lsect }; - } else { - n = i % SEGS_PER_INDIRECT_FRAME; - segments[n] = + kunmap_atomic(bvec_data); + kunmap_atomic(shared_data); + } + if (ring_req->operation != BLKIF_OP_INDIRECT) { + ring_req->u.rw.seg[i] = (struct blkif_request_segment) { - .gref = ref, - .first_sect = fsect, - .last_sect = lsect }; - } + .gref = ref, + .first_sect = fsect, + .last_sect = lsect }; + } else { + n = i % SEGS_PER_INDIRECT_FRAME; + segments[n] = + (struct blkif_request_segment) { + .gref = ref, + .first_sect = fsect, + .last_sect = lsect }; } - if (segments) - kunmap_atomic(segments); } + if (segments) + kunmap_atomic(segments); info->ring.req_prod_pvt++; @@ -597,6 +608,24 @@ static int blkif_queue_request(struct request *req) return 0; } +/* + * Generate a Xen blkfront IO request from a blk layer request. Reads + * and writes are handled as expected. + * + * @req: a request struct + */ +static int blkif_queue_request(struct request *req) +{ + struct blkfront_info *info = req->rq_disk->private_data; + + if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) + return 1; + + if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) + return blkif_queue_discard_req(req); + else + return blkif_queue_rw_req(req); +} static inline void flush_requests(struct blkfront_info *info) { -- cgit v1.2.3