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authorJuergen Gross <jgross@suse.com>2020-12-07 10:31:22 +0300
committerJuergen Gross <jgross@suse.com>2020-12-09 12:31:37 +0300
commitca33479cc7be2c9b5f8be078c8bf3ac26b7d6186 (patch)
tree8877168fff59f8955f29ddaf37a0ac6a0cb3d9fd /drivers/xen/grant-table.c
parenta68a0262abdaa251e12c53715f48e698a18ef402 (diff)
downloadlinux-ca33479cc7be2c9b5f8be078c8bf3ac26b7d6186.tar.xz
xen: add helpers for caching grant mapping pages
Instead of having similar helpers in multiple backend drivers use common helpers for caching pages allocated via gnttab_alloc_pages(). Make use of those helpers in blkback and scsiback. Cc: <stable@vger.kernel.org> # 5.9 Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovksy@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'drivers/xen/grant-table.c')
-rw-r--r--drivers/xen/grant-table.c72
1 files changed, 72 insertions, 0 deletions
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 523dcdf39cc9..e2e42912f241 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -813,6 +813,78 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages)
}
EXPORT_SYMBOL_GPL(gnttab_alloc_pages);
+void gnttab_page_cache_init(struct gnttab_page_cache *cache)
+{
+ spin_lock_init(&cache->lock);
+ INIT_LIST_HEAD(&cache->pages);
+ cache->num_pages = 0;
+}
+EXPORT_SYMBOL_GPL(gnttab_page_cache_init);
+
+int gnttab_page_cache_get(struct gnttab_page_cache *cache, struct page **page)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&cache->lock, flags);
+
+ if (list_empty(&cache->pages)) {
+ spin_unlock_irqrestore(&cache->lock, flags);
+ return gnttab_alloc_pages(1, page);
+ }
+
+ page[0] = list_first_entry(&cache->pages, struct page, lru);
+ list_del(&page[0]->lru);
+ cache->num_pages--;
+
+ spin_unlock_irqrestore(&cache->lock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(gnttab_page_cache_get);
+
+void gnttab_page_cache_put(struct gnttab_page_cache *cache, struct page **page,
+ unsigned int num)
+{
+ unsigned long flags;
+ unsigned int i;
+
+ spin_lock_irqsave(&cache->lock, flags);
+
+ for (i = 0; i < num; i++)
+ list_add(&page[i]->lru, &cache->pages);
+ cache->num_pages += num;
+
+ spin_unlock_irqrestore(&cache->lock, flags);
+}
+EXPORT_SYMBOL_GPL(gnttab_page_cache_put);
+
+void gnttab_page_cache_shrink(struct gnttab_page_cache *cache, unsigned int num)
+{
+ struct page *page[10];
+ unsigned int i = 0;
+ unsigned long flags;
+
+ spin_lock_irqsave(&cache->lock, flags);
+
+ while (cache->num_pages > num) {
+ page[i] = list_first_entry(&cache->pages, struct page, lru);
+ list_del(&page[i]->lru);
+ cache->num_pages--;
+ if (++i == ARRAY_SIZE(page)) {
+ spin_unlock_irqrestore(&cache->lock, flags);
+ gnttab_free_pages(i, page);
+ i = 0;
+ spin_lock_irqsave(&cache->lock, flags);
+ }
+ }
+
+ spin_unlock_irqrestore(&cache->lock, flags);
+
+ if (i != 0)
+ gnttab_free_pages(i, page);
+}
+EXPORT_SYMBOL_GPL(gnttab_page_cache_shrink);
+
void gnttab_pages_clear_private(int nr_pages, struct page **pages)
{
int i;