From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
This isn't just a random struct page, it's known to be a head page,
and calling it head makes the function better self-documenting.
The pgoff_t is less confusing if it's named index instead of offset.
Also add a couple of comments to explain why we're doing various things.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
include/linux/pagemap.h | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index b4ea3a5d00e5..68db0ed8535d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -333,14 +333,19 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
mapping_gfp_mask(mapping));
}
-static inline struct page *find_subpage(struct page *page, pgoff_t offset)
+/*
+ * Given the page we found in the page cache, return the page corresponding
+ * to this index in the file
+ */
+static inline struct page *find_subpage(struct page *head, pgoff_t index)
{
- if (PageHuge(page))
- return page;
+ /* HugeTLBfs wants the head page regardless */
+ if (PageHuge(head))
+ return head;
- VM_BUG_ON_PAGE(PageTail(page), page);
+ VM_BUG_ON_PAGE(PageTail(head), head);
- return page + (offset & (compound_nr(page) - 1));
+ return head + (index & (compound_nr(head) - 1));
}
struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
--
2.25.1
