summaryrefslogtreecommitdiff
path: root/drivers/block/xen-blkfront.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/block/xen-blkfront.c')
-rw-r--r--drivers/block/xen-blkfront.c212
1 files changed, 132 insertions, 80 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index a4660bbee8a6..432db1b59b00 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -121,7 +121,8 @@ struct blkfront_info
struct work_struct work;
struct gnttab_free_callback callback;
struct blk_shadow shadow[BLK_RING_SIZE];
- struct list_head persistent_gnts;
+ struct list_head grants;
+ struct list_head indirect_pages;
unsigned int persistent_gnts_c;
unsigned long shadow_free;
unsigned int feature_flush;
@@ -200,15 +201,17 @@ static int fill_grant_buffer(struct blkfront_info *info, int num)
if (!gnt_list_entry)
goto out_of_memory;
- granted_page = alloc_page(GFP_NOIO);
- if (!granted_page) {
- kfree(gnt_list_entry);
- goto out_of_memory;
+ if (info->feature_persistent) {
+ granted_page = alloc_page(GFP_NOIO);
+ if (!granted_page) {
+ kfree(gnt_list_entry);
+ goto out_of_memory;
+ }
+ gnt_list_entry->pfn = page_to_pfn(granted_page);
}
- gnt_list_entry->pfn = page_to_pfn(granted_page);
gnt_list_entry->gref = GRANT_INVALID_REF;
- list_add(&gnt_list_entry->node, &info->persistent_gnts);
+ list_add(&gnt_list_entry->node, &info->grants);
i++;
}
@@ -216,9 +219,10 @@ static int fill_grant_buffer(struct blkfront_info *info, int num)
out_of_memory:
list_for_each_entry_safe(gnt_list_entry, n,
- &info->persistent_gnts, node) {
+ &info->grants, node) {
list_del(&gnt_list_entry->node);
- __free_page(pfn_to_page(gnt_list_entry->pfn));
+ if (info->feature_persistent)
+ __free_page(pfn_to_page(gnt_list_entry->pfn));
kfree(gnt_list_entry);
i--;
}
@@ -227,13 +231,14 @@ out_of_memory:
}
static struct grant *get_grant(grant_ref_t *gref_head,
+ unsigned long pfn,
struct blkfront_info *info)
{
struct grant *gnt_list_entry;
unsigned long buffer_mfn;
- BUG_ON(list_empty(&info->persistent_gnts));
- gnt_list_entry = list_first_entry(&info->persistent_gnts, struct grant,
+ BUG_ON(list_empty(&info->grants));
+ gnt_list_entry = list_first_entry(&info->grants, struct grant,
node);
list_del(&gnt_list_entry->node);
@@ -245,6 +250,10 @@ static struct grant *get_grant(grant_ref_t *gref_head,
/* Assign a gref to this page */
gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
BUG_ON(gnt_list_entry->gref == -ENOSPC);
+ if (!info->feature_persistent) {
+ BUG_ON(!pfn);
+ gnt_list_entry->pfn = pfn;
+ }
buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn);
gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
info->xbdev->otherend_id,
@@ -400,10 +409,13 @@ static int blkif_queue_request(struct request *req)
if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
return 1;
- max_grefs = info->max_indirect_segments ?
- info->max_indirect_segments +
- INDIRECT_GREFS(info->max_indirect_segments) :
- BLKIF_MAX_SEGMENTS_PER_REQUEST;
+ max_grefs = req->nr_phys_segments;
+ 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);
/* Check if we have enough grants to allocate a requests */
if (info->persistent_gnts_c < max_grefs) {
@@ -477,22 +489,34 @@ static int blkif_queue_request(struct request *req)
if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
(i % SEGS_PER_INDIRECT_FRAME == 0)) {
+ unsigned long pfn;
+
if (segments)
kunmap_atomic(segments);
n = i / SEGS_PER_INDIRECT_FRAME;
- gnt_list_entry = get_grant(&gref_head, info);
+ 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, info);
+ 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;
- if (rq_data_dir(req)) {
+ if (rq_data_dir(req) && info->feature_persistent) {
char *bvec_data;
void *shared_data;
@@ -904,21 +928,36 @@ static void blkif_free(struct blkfront_info *info, int suspend)
blk_stop_queue(info->rq);
/* Remove all persistent grants */
- if (!list_empty(&info->persistent_gnts)) {
+ if (!list_empty(&info->grants)) {
list_for_each_entry_safe(persistent_gnt, n,
- &info->persistent_gnts, node) {
+ &info->grants, node) {
list_del(&persistent_gnt->node);
if (persistent_gnt->gref != GRANT_INVALID_REF) {
gnttab_end_foreign_access(persistent_gnt->gref,
0, 0UL);
info->persistent_gnts_c--;
}
- __free_page(pfn_to_page(persistent_gnt->pfn));
+ if (info->feature_persistent)
+ __free_page(pfn_to_page(persistent_gnt->pfn));
kfree(persistent_gnt);
}
}
BUG_ON(info->persistent_gnts_c != 0);
+ /*
+ * Remove indirect pages, this only happens when using indirect
+ * descriptors but not persistent grants
+ */
+ if (!list_empty(&info->indirect_pages)) {
+ struct page *indirect_page, *n;
+
+ BUG_ON(info->feature_persistent);
+ list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
+ list_del(&indirect_page->lru);
+ __free_page(indirect_page);
+ }
+ }
+
for (i = 0; i < BLK_RING_SIZE; i++) {
/*
* Clear persistent grants present in requests already
@@ -933,7 +972,8 @@ static void blkif_free(struct blkfront_info *info, int suspend)
for (j = 0; j < segs; j++) {
persistent_gnt = info->shadow[i].grants_used[j];
gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
- __free_page(pfn_to_page(persistent_gnt->pfn));
+ if (info->feature_persistent)
+ __free_page(pfn_to_page(persistent_gnt->pfn));
kfree(persistent_gnt);
}
@@ -992,7 +1032,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
nseg = s->req.operation == BLKIF_OP_INDIRECT ?
s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
- if (bret->operation == BLKIF_OP_READ) {
+ if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
/*
* Copy the data received from the backend into the bvec.
* Since bv_offset can be different than 0, and bv_len different
@@ -1013,13 +1053,51 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
}
/* Add the persistent grant into the list of free grants */
for (i = 0; i < nseg; i++) {
- list_add(&s->grants_used[i]->node, &info->persistent_gnts);
- info->persistent_gnts_c++;
+ if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
+ /*
+ * If the grant is still mapped by the backend (the
+ * backend has chosen to make this grant persistent)
+ * we add it at the head of the list, so it will be
+ * reused first.
+ */
+ if (!info->feature_persistent)
+ pr_alert_ratelimited("backed has not unmapped grant: %u\n",
+ s->grants_used[i]->gref);
+ list_add(&s->grants_used[i]->node, &info->grants);
+ info->persistent_gnts_c++;
+ } else {
+ /*
+ * If the grant is not mapped by the backend we end the
+ * foreign access and add it to the tail of the list,
+ * so it will not be picked again unless we run out of
+ * persistent grants.
+ */
+ gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
+ s->grants_used[i]->gref = GRANT_INVALID_REF;
+ list_add_tail(&s->grants_used[i]->node, &info->grants);
+ }
}
if (s->req.operation == BLKIF_OP_INDIRECT) {
for (i = 0; i < INDIRECT_GREFS(nseg); i++) {
- list_add(&s->indirect_grants[i]->node, &info->persistent_gnts);
- info->persistent_gnts_c++;
+ if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
+ if (!info->feature_persistent)
+ pr_alert_ratelimited("backed has not unmapped grant: %u\n",
+ s->indirect_grants[i]->gref);
+ list_add(&s->indirect_grants[i]->node, &info->grants);
+ info->persistent_gnts_c++;
+ } else {
+ struct page *indirect_page;
+
+ gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
+ /*
+ * Add the used indirect page back to the list of
+ * available pages for indirect grefs.
+ */
+ indirect_page = pfn_to_page(s->indirect_grants[i]->pfn);
+ list_add(&indirect_page->lru, &info->indirect_pages);
+ s->indirect_grants[i]->gref = GRANT_INVALID_REF;
+ list_add_tail(&s->indirect_grants[i]->node, &info->grants);
+ }
}
}
}
@@ -1313,7 +1391,8 @@ static int blkfront_probe(struct xenbus_device *dev,
spin_lock_init(&info->io_lock);
info->xbdev = dev;
info->vdevice = vdevice;
- INIT_LIST_HEAD(&info->persistent_gnts);
+ INIT_LIST_HEAD(&info->grants);
+ INIT_LIST_HEAD(&info->indirect_pages);
info->persistent_gnts_c = 0;
info->connected = BLKIF_STATE_DISCONNECTED;
INIT_WORK(&info->work, blkif_restart_queue);
@@ -1336,57 +1415,6 @@ static int blkfront_probe(struct xenbus_device *dev,
return 0;
}
-/*
- * This is a clone of md_trim_bio, used to split a bio into smaller ones
- */
-static void trim_bio(struct bio *bio, int offset, int size)
-{
- /* 'bio' is a cloned bio which we need to trim to match
- * the given offset and size.
- * This requires adjusting bi_sector, bi_size, and bi_io_vec
- */
- int i;
- struct bio_vec *bvec;
- int sofar = 0;
-
- size <<= 9;
- if (offset == 0 && size == bio->bi_size)
- return;
-
- bio->bi_sector += offset;
- bio->bi_size = size;
- offset <<= 9;
- clear_bit(BIO_SEG_VALID, &bio->bi_flags);
-
- while (bio->bi_idx < bio->bi_vcnt &&
- bio->bi_io_vec[bio->bi_idx].bv_len <= offset) {
- /* remove this whole bio_vec */
- offset -= bio->bi_io_vec[bio->bi_idx].bv_len;
- bio->bi_idx++;
- }
- if (bio->bi_idx < bio->bi_vcnt) {
- bio->bi_io_vec[bio->bi_idx].bv_offset += offset;
- bio->bi_io_vec[bio->bi_idx].bv_len -= offset;
- }
- /* avoid any complications with bi_idx being non-zero*/
- if (bio->bi_idx) {
- memmove(bio->bi_io_vec, bio->bi_io_vec+bio->bi_idx,
- (bio->bi_vcnt - bio->bi_idx) * sizeof(struct bio_vec));
- bio->bi_vcnt -= bio->bi_idx;
- bio->bi_idx = 0;
- }
- /* Make sure vcnt and last bv are not too big */
- bio_for_each_segment(bvec, bio, i) {
- if (sofar + bvec->bv_len > size)
- bvec->bv_len = size - sofar;
- if (bvec->bv_len == 0) {
- bio->bi_vcnt = i;
- break;
- }
- sofar += bvec->bv_len;
- }
-}
-
static void split_bio_end(struct bio *bio, int error)
{
struct split_bio *split_bio = bio->bi_private;
@@ -1522,7 +1550,7 @@ static int blkif_recover(struct blkfront_info *info)
(unsigned int)(bio->bi_size >> 9) - offset);
cloned_bio = bio_clone(bio, GFP_NOIO);
BUG_ON(cloned_bio == NULL);
- trim_bio(cloned_bio, offset, size);
+ bio_trim(cloned_bio, offset, size);
cloned_bio->bi_private = split_bio;
cloned_bio->bi_end_io = split_bio_end;
submit_bio(cloned_bio->bi_rw, cloned_bio);
@@ -1660,6 +1688,23 @@ static int blkfront_setup_indirect(struct blkfront_info *info)
if (err)
goto out_of_memory;
+ if (!info->feature_persistent && info->max_indirect_segments) {
+ /*
+ * We are using indirect descriptors but not persistent
+ * 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;
+
+ BUG_ON(!list_empty(&info->indirect_pages));
+ for (i = 0; i < num; i++) {
+ struct page *indirect_page = alloc_page(GFP_NOIO);
+ if (!indirect_page)
+ goto out_of_memory;
+ list_add(&indirect_page->lru, &info->indirect_pages);
+ }
+ }
+
for (i = 0; i < BLK_RING_SIZE; i++) {
info->shadow[i].grants_used = kzalloc(
sizeof(info->shadow[i].grants_used[0]) * segs,
@@ -1690,6 +1735,13 @@ out_of_memory:
kfree(info->shadow[i].indirect_grants);
info->shadow[i].indirect_grants = NULL;
}
+ if (!list_empty(&info->indirect_pages)) {
+ struct page *indirect_page, *n;
+ list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
+ list_del(&indirect_page->lru);
+ __free_page(indirect_page);
+ }
+ }
return -ENOMEM;
}