@@ -36,20 +36,43 @@ static struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs
return page;
}
+static struct fb_deferred_io_pageref *fb_deferred_io_pageref_lookup(struct fb_info *info,
+ unsigned long offset,
+ struct page *page)
+{
+ unsigned long pgoff = offset >> PAGE_SHIFT;
+ struct fb_deferred_io_pageref *pageref;
+
+ if (fb_WARN_ON_ONCE(info, pgoff >= info->npagerefs))
+ return NULL; /* incorrect allocation size */
+
+ /* 1:1 mapping between pageref and page offset */
+ pageref = &info->pagerefs[pgoff];
+
+ if (pageref->page)
+ goto out;
+
+ pageref->page = page;
+ pageref->offset = pgoff << PAGE_SHIFT;
+ INIT_LIST_HEAD(&pageref->list);
+
+out:
+ if (fb_WARN_ON_ONCE(info, pageref->page != page))
+ return NULL; /* inconsistent state */
+ return pageref;
+}
+
static struct fb_deferred_io_pageref *fb_deferred_io_pageref_get(struct fb_info *info,
unsigned long offset,
struct page *page)
{
struct fb_deferred_io *fbdefio = info->fbdefio;
struct list_head *pos = &fbdefio->pagereflist;
- unsigned long pgoff = offset >> PAGE_SHIFT;
struct fb_deferred_io_pageref *pageref, *cur;
- if (WARN_ON_ONCE(pgoff >= info->npagerefs))
- return NULL; /* incorrect allocation size */
-
- /* 1:1 mapping between pageref and page offset */
- pageref = &info->pagerefs[pgoff];
+ pageref = fb_deferred_io_pageref_lookup(info, offset, page);
+ if (!pageref)
+ return NULL;
/*
* This check is to catch the case where a new process could start
@@ -60,9 +83,6 @@ static struct fb_deferred_io_pageref *fb_deferred_io_pageref_get(struct fb_info
if (!list_empty(&pageref->list))
goto pageref_already_added;
- pageref->page = page;
- pageref->offset = pgoff << PAGE_SHIFT;
-
if (unlikely(fbdefio->sort_pagereflist)) {
/*
* We loop through the list of pagerefs before adding in
@@ -264,7 +284,7 @@ int fb_deferred_io_init(struct fb_info *info)
{
struct fb_deferred_io *fbdefio = info->fbdefio;
struct fb_deferred_io_pageref *pagerefs;
- unsigned long npagerefs, i;
+ unsigned long npagerefs;
int ret;
BUG_ON(!fbdefio);
@@ -286,8 +306,6 @@ int fb_deferred_io_init(struct fb_info *info)
ret = -ENOMEM;
goto err;
}
- for (i = 0; i < npagerefs; ++i)
- INIT_LIST_HEAD(&pagerefs[i].list);
info->npagerefs = npagerefs;
info->pagerefs = pagerefs;