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path: root/drivers/block/xen-blkfront.c
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Diffstat (limited to 'drivers/block/xen-blkfront.c')
-rw-r--r--drivers/block/xen-blkfront.c88
1 files changed, 59 insertions, 29 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 7552ca8f8ffe..f5dfc1694679 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -244,34 +244,77 @@ out_of_memory:
return -ENOMEM;
}
-static struct grant *get_grant(grant_ref_t *gref_head,
- struct page *page,
- struct blkfront_info *info)
+static struct grant *get_free_grant(struct blkfront_info *info)
{
struct grant *gnt_list_entry;
- unsigned long buffer_gfn;
BUG_ON(list_empty(&info->grants));
gnt_list_entry = list_first_entry(&info->grants, struct grant,
- node);
+ node);
list_del(&gnt_list_entry->node);
- if (gnt_list_entry->gref != GRANT_INVALID_REF) {
+ if (gnt_list_entry->gref != GRANT_INVALID_REF)
info->persistent_gnts_c--;
+
+ return gnt_list_entry;
+}
+
+static inline void grant_foreign_access(const struct grant *gnt_list_entry,
+ const struct blkfront_info *info)
+{
+ gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
+ info->xbdev->otherend_id,
+ gnt_list_entry->page,
+ 0);
+}
+
+static struct grant *get_grant(grant_ref_t *gref_head,
+ unsigned long gfn,
+ struct blkfront_info *info)
+{
+ struct grant *gnt_list_entry = get_free_grant(info);
+
+ if (gnt_list_entry->gref != GRANT_INVALID_REF)
return gnt_list_entry;
+
+ /* 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)
+ grant_foreign_access(gnt_list_entry, info);
+ else {
+ /* Grant access to the GFN passed by the caller */
+ gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
+ info->xbdev->otherend_id,
+ gfn, 0);
}
+ return gnt_list_entry;
+}
+
+static struct grant *get_indirect_grant(grant_ref_t *gref_head,
+ struct blkfront_info *info)
+{
+ struct grant *gnt_list_entry = get_free_grant(info);
+
+ if (gnt_list_entry->gref != GRANT_INVALID_REF)
+ return gnt_list_entry;
+
/* 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(!page);
- gnt_list_entry->page = page;
+ 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);
+ gnt_list_entry->page = indirect_page;
}
- buffer_gfn = xen_page_to_gfn(gnt_list_entry->page);
- gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
- info->xbdev->otherend_id,
- buffer_gfn, 0);
+ grant_foreign_access(gnt_list_entry, info);
+
return gnt_list_entry;
}
@@ -524,32 +567,19 @@ static int blkif_queue_rw_req(struct request *req)
if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
(i % SEGS_PER_INDIRECT_FRAME == 0)) {
- struct page *uninitialized_var(page);
-
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);
- page = indirect_page;
- }
- gnt_list_entry = get_grant(&gref_head, page, info);
+ 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, sg_page(sg), info);
+ 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;