Commit 33204663 authored by Julien Grall's avatar Julien Grall Committed by David Vrabel

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: default avatarJulien Grall <julien.grall@citrix.com>
Reviewed-by: default avatarRoger Pau Monné <roger.pau@citrix.com>
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
parent 3922f32c
......@@ -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)
{
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment