diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index f5dfc1694679e900c4e40ace90071608f140b601..057e05da83d179b960a6e65b887a58e7833990b1 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -78,6 +78,7 @@ struct blk_shadow {
struct grant **grants_used;
struct grant **indirect_grants;
struct scatterlist *sg;
+ unsigned int num_sg;
};
struct split_bio {
@@ -106,8 +107,12 @@ static unsigned int xen_blkif_max_ring_order;
module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO);
MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
-#define BLK_RING_SIZE(info) __CONST_RING_SIZE(blkif, PAGE_SIZE * (info)->nr_ring_pages)
-#define BLK_MAX_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE * XENBUS_MAX_RING_PAGES)
+#define BLK_RING_SIZE(info) \
+ __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
+
+#define BLK_MAX_RING_SIZE \
+ __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_PAGES)
+
/*
* ring-ref%i i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
* characters are enough. Define to 20 to keep consist with backend.
@@ -146,6 +151,7 @@ struct blkfront_info
unsigned int discard_granularity;
unsigned int discard_alignment;
unsigned int feature_persistent:1;
+ /* Number of 4KB segments handled */
unsigned int max_indirect_segments;
int is_ready;
struct blk_mq_tag_set tag_set;
@@ -174,10 +180,23 @@ static DEFINE_SPINLOCK(minor_lock);
#define DEV_NAME "xvd" /* name in /dev */
-#define SEGS_PER_INDIRECT_FRAME \
- (PAGE_SIZE/sizeof(struct blkif_request_segment))
-#define INDIRECT_GREFS(_segs) \
- ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
+/*
+ * Grants are always the same size as a Xen page (i.e 4KB).
+ * A physical segment is always the same size as a Linux page.
+ * Number of grants per physical segment
+ */
+#define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
+
+#define GRANTS_PER_INDIRECT_FRAME \
+ (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
+
+#define PSEGS_PER_INDIRECT_FRAME \
+ (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS)
+
+#define INDIRECT_GREFS(_grants) \
+ DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
+
+#define GREFS(_psegs) ((_psegs) * GRANTS_PER_PSEG)
static int blkfront_setup_indirect(struct blkfront_info *info);
static int blkfront_gather_backend_features(struct blkfront_info *info);
@@ -465,14 +484,100 @@ static int blkif_queue_discard_req(struct request *req)
return 0;
}
+struct setup_rw_req {
+ unsigned int grant_idx;
+ struct blkif_request_segment *segments;
+ struct blkfront_info *info;
+ struct blkif_request *ring_req;
+ grant_ref_t gref_head;
+ unsigned int id;
+ /* Only used when persistent grant is used and it's a read request */
+ bool need_copy;
+ unsigned int bvec_off;
+ char *bvec_data;
+};
+
+static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
+ unsigned int len, void *data)
+{
+ struct setup_rw_req *setup = data;
+ int n, ref;
+ struct grant *gnt_list_entry;
+ unsigned int fsect, lsect;
+ /* Convenient aliases */
+ unsigned int grant_idx = setup->grant_idx;
+ struct blkif_request *ring_req = setup->ring_req;
+ struct blkfront_info *info = setup->info;
+ struct blk_shadow *shadow = &info->shadow[setup->id];
+
+ if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
+ (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
+ if (setup->segments)
+ kunmap_atomic(setup->segments);
+
+ n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
+ gnt_list_entry = get_indirect_grant(&setup->gref_head, info);
+ shadow->indirect_grants[n] = gnt_list_entry;
+ setup->segments = kmap_atomic(gnt_list_entry->page);
+ ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
+ }
+
+ gnt_list_entry = get_grant(&setup->gref_head, gfn, info);
+ ref = gnt_list_entry->gref;
+ shadow->grants_used[grant_idx] = gnt_list_entry;
+
+ if (setup->need_copy) {
+ void *shared_data;
+
+ shared_data = kmap_atomic(gnt_list_entry->page);
+ /*
+ * 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 + offset,
+ setup->bvec_data + setup->bvec_off,
+ len);
+
+ kunmap_atomic(shared_data);
+ setup->bvec_off += len;
+ }
+
+ fsect = offset >> 9;
+ lsect = fsect + (len >> 9) - 1;
+ if (ring_req->operation != BLKIF_OP_INDIRECT) {
+ ring_req->u.rw.seg[grant_idx] =
+ (struct blkif_request_segment) {
+ .gref = ref,
+ .first_sect = fsect,
+ .last_sect = lsect };
+ } else {
+ setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
+ (struct blkif_request_segment) {
+ .gref = ref,
+ .first_sect = fsect,
+ .last_sect = lsect };
+ }
+
+ (setup->grant_idx)++;
+}
+
static int blkif_queue_rw_req(struct request *req)
{
struct blkfront_info *info = req->rq_disk->private_data;
struct blkif_request *ring_req;
unsigned long id;
- unsigned int fsect, lsect;
- int i, ref, n;
- struct blkif_request_segment *segments = NULL;
+ int i;
+ struct setup_rw_req setup = {
+ .grant_idx = 0,
+ .segments = NULL,
+ .info = info,
+ .need_copy = rq_data_dir(req) && info->feature_persistent,
+ };
/*
* Used to store if we are able to queue the request by just using
@@ -480,25 +585,23 @@ static int blkif_queue_rw_req(struct request *req)
* as there are not sufficiently many free.
*/
bool new_persistent_gnts;
- grant_ref_t gref_head;
- struct grant *gnt_list_entry = NULL;
struct scatterlist *sg;
- int nseg, max_grefs;
+ int num_sg, max_grefs, num_grant;
- max_grefs = req->nr_phys_segments;
+ max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
/*
* If we are using indirect segments we need to account
* for the indirect grefs used in the request.
*/
- max_grefs += INDIRECT_GREFS(req->nr_phys_segments);
+ max_grefs += INDIRECT_GREFS(max_grefs);
/* Check if we have enough grants to allocate a requests */
if (info->persistent_gnts_c < max_grefs) {
new_persistent_gnts = 1;
if (gnttab_alloc_grant_references(
max_grefs - info->persistent_gnts_c,
- &gref_head) < 0) {
+ &setup.gref_head) < 0) {
gnttab_request_free_callback(
&info->callback,
blkif_restart_queue_callback,
@@ -515,12 +618,19 @@ static int blkif_queue_rw_req(struct request *req)
info->shadow[id].request = req;
BUG_ON(info->max_indirect_segments == 0 &&
- req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
+ GREFS(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);
+ GREFS(req->nr_phys_segments) > info->max_indirect_segments);
+
+ num_sg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
+ num_grant = 0;
+ /* Calculate the number of grant used */
+ for_each_sg(info->shadow[id].sg, sg, num_sg, i)
+ num_grant += gnttab_count_grant(sg->offset, sg->length);
+
ring_req->u.rw.id = id;
- if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
+ info->shadow[id].num_sg = num_sg;
+ if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
/*
* The indirect operation can only be a BLKIF_OP_READ or
* BLKIF_OP_WRITE
@@ -531,7 +641,7 @@ static int blkif_queue_rw_req(struct request *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;
+ ring_req->u.indirect.nr_segments = num_grant;
} else {
ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
ring_req->u.rw.handle = info->handle;
@@ -559,73 +669,30 @@ static int blkif_queue_rw_req(struct request *req)
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;
-
- if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
- (i % SEGS_PER_INDIRECT_FRAME == 0)) {
- if (segments)
- kunmap_atomic(segments);
-
- n = i / SEGS_PER_INDIRECT_FRAME;
- gnt_list_entry = get_indirect_grant(&gref_head, info);
- info->shadow[id].indirect_grants[n] = gnt_list_entry;
- segments = kmap_atomic(gnt_list_entry->page);
- ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
- }
-
- gnt_list_entry = get_grant(&gref_head,
- xen_page_to_gfn(sg_page(sg)),
- info);
- ref = gnt_list_entry->gref;
-
- info->shadow[id].grants_used[i] = gnt_list_entry;
-
- if (rq_data_dir(req) && info->feature_persistent) {
- char *bvec_data;
- void *shared_data;
+ ring_req->u.rw.nr_segments = num_grant;
+ }
- BUG_ON(sg->offset + sg->length > PAGE_SIZE);
+ setup.ring_req = ring_req;
+ setup.id = id;
+ for_each_sg(info->shadow[id].sg, sg, num_sg, i) {
+ BUG_ON(sg->offset + sg->length > PAGE_SIZE);
- shared_data = kmap_atomic(gnt_list_entry->page);
- bvec_data = kmap_atomic(sg_page(sg));
+ if (setup.need_copy) {
+ setup.bvec_off = sg->offset;
+ setup.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);
+ gnttab_foreach_grant_in_range(sg_page(sg),
+ sg->offset,
+ sg->length,
+ blkif_setup_rw_req_grant,
+ &setup);
- 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] =
- (struct blkif_request_segment) {
- .gref = ref,
- .first_sect = fsect,
- .last_sect = lsect };
- }
+ if (setup.need_copy)
+ kunmap_atomic(setup.bvec_data);
}
- if (segments)
- kunmap_atomic(segments);
+ if (setup.segments)
+ kunmap_atomic(setup.segments);
info->ring.req_prod_pvt++;
@@ -633,7 +700,7 @@ static int blkif_queue_rw_req(struct request *req)
info->shadow[id].req = *ring_req;
if (new_persistent_gnts)
- gnttab_free_grant_references(gref_head);
+ gnttab_free_grant_references(setup.gref_head);
return 0;
}
@@ -750,14 +817,14 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
/* Hard sector size and max sectors impersonate the equiv. hardware. */
blk_queue_logical_block_size(rq, sector_size);
blk_queue_physical_block_size(rq, physical_sector_size);
- blk_queue_max_hw_sectors(rq, (segments * PAGE_SIZE) / 512);
+ blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
/* Each segment in a request is up to an aligned page in size. */
blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
blk_queue_max_segment_size(rq, PAGE_SIZE);
/* Ensure a merged request will fit in a single I/O ring slot. */
- blk_queue_max_segments(rq, segments);
+ blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
/* Make sure buffer addresses are sector-aligned. */
blk_queue_dma_alignment(rq, 511);
@@ -1116,32 +1183,65 @@ static void blkif_free(struct blkfront_info *info, int suspend)
}
+struct copy_from_grant {
+ const struct blk_shadow *s;
+ unsigned int grant_idx;
+ unsigned int bvec_offset;
+ char *bvec_data;
+};
+
+static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
+ unsigned int len, void *data)
+{
+ struct copy_from_grant *info = data;
+ char *shared_data;
+ /* Convenient aliases */
+ const struct blk_shadow *s = info->s;
+
+ shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
+
+ memcpy(info->bvec_data + info->bvec_offset,
+ shared_data + offset, len);
+
+ info->bvec_offset += len;
+ info->grant_idx++;
+
+ kunmap_atomic(shared_data);
+}
+
static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
struct blkif_response *bret)
{
int i = 0;
struct scatterlist *sg;
- char *bvec_data;
- void *shared_data;
- int nseg;
+ int num_sg, num_grant;
+ struct copy_from_grant data = {
+ .s = s,
+ .grant_idx = 0,
+ };
- nseg = s->req.operation == BLKIF_OP_INDIRECT ?
+ num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
+ num_sg = s->num_sg;
if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
- for_each_sg(s->sg, sg, nseg, i) {
+ for_each_sg(s->sg, sg, num_sg, i) {
BUG_ON(sg->offset + sg->length > PAGE_SIZE);
- shared_data = kmap_atomic(s->grants_used[i]->page);
- bvec_data = kmap_atomic(sg_page(sg));
- memcpy(bvec_data + sg->offset,
- shared_data + sg->offset,
- sg->length);
- kunmap_atomic(bvec_data);
- kunmap_atomic(shared_data);
+
+ data.bvec_offset = sg->offset;
+ data.bvec_data = kmap_atomic(sg_page(sg));
+
+ gnttab_foreach_grant_in_range(sg_page(sg),
+ sg->offset,
+ sg->length,
+ blkif_copy_from_grant,
+ &data);
+
+ kunmap_atomic(data.bvec_data);
}
}
/* Add the persistent grant into the list of free grants */
- for (i = 0; i < nseg; i++) {
+ for (i = 0; i < num_grant; i++) {
if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
/*
* If the grant is still mapped by the backend (the
@@ -1167,7 +1267,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
}
}
if (s->req.operation == BLKIF_OP_INDIRECT) {
- for (i = 0; i < INDIRECT_GREFS(nseg); i++) {
+ for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
if (!info->feature_persistent)
pr_alert_ratelimited("backed has not unmapped grant: %u\n",
@@ -1312,7 +1412,7 @@ static int setup_blkring(struct xenbus_device *dev,
{
struct blkif_sring *sring;
int err, i;
- unsigned long ring_size = info->nr_ring_pages * PAGE_SIZE;
+ unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
grant_ref_t gref[XENBUS_MAX_RING_PAGES];
for (i = 0; i < info->nr_ring_pages; i++)
@@ -1641,8 +1741,8 @@ static int blkif_recover(struct blkfront_info *info)
atomic_set(&split_bio->pending, pending);
split_bio->bio = bio;
for (i = 0; i < pending; i++) {
- offset = (i * segs * PAGE_SIZE) >> 9;
- size = min((unsigned int)(segs * PAGE_SIZE) >> 9,
+ offset = (i * segs * XEN_PAGE_SIZE) >> 9;
+ size = min((unsigned int)(segs * XEN_PAGE_SIZE) >> 9,
(unsigned int)bio_sectors(bio) - offset);
cloned_bio = bio_clone(bio, GFP_NOIO);
BUG_ON(cloned_bio == NULL);
@@ -1753,15 +1853,17 @@ static void blkfront_setup_discard(struct blkfront_info *info)
static int blkfront_setup_indirect(struct blkfront_info *info)
{
- unsigned int segs;
+ unsigned int psegs, grants;
int err, i;
if (info->max_indirect_segments == 0)
- segs = BLKIF_MAX_SEGMENTS_PER_REQUEST;
+ grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
else
- segs = info->max_indirect_segments;
+ grants = info->max_indirect_segments;
+ psegs = grants / GRANTS_PER_PSEG;
- err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE(info));
+ err = fill_grant_buffer(info,
+ (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
if (err)
goto out_of_memory;
@@ -1771,7 +1873,7 @@ static int blkfront_setup_indirect(struct blkfront_info *info)
* grants, we need to allocate a set of pages that can be
* used for mapping indirect grefs
*/
- int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE(info);
+ int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
BUG_ON(!list_empty(&info->indirect_pages));
for (i = 0; i < num; i++) {
@@ -1784,20 +1886,20 @@ static int blkfront_setup_indirect(struct blkfront_info *info)
for (i = 0; i < BLK_RING_SIZE(info); i++) {
info->shadow[i].grants_used = kzalloc(
- sizeof(info->shadow[i].grants_used[0]) * segs,
+ sizeof(info->shadow[i].grants_used[0]) * grants,
GFP_NOIO);
- info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO);
+ info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * psegs, GFP_NOIO);
if (info->max_indirect_segments)
info->shadow[i].indirect_grants = kzalloc(
sizeof(info->shadow[i].indirect_grants[0]) *
- INDIRECT_GREFS(segs),
+ INDIRECT_GREFS(grants),
GFP_NOIO);
if ((info->shadow[i].grants_used == NULL) ||
(info->shadow[i].sg == NULL) ||
(info->max_indirect_segments &&
(info->shadow[i].indirect_grants == NULL)))
goto out_of_memory;
- sg_init_table(info->shadow[i].sg, segs);
+ sg_init_table(info->shadow[i].sg, psegs);
}