From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
For now we still write/read at most PAGE_CACHE_SIZE bytes a time.
This implementation doesn't cover address spaces with backing store.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
mm/filemap.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index bcb679c..3296f5c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1161,6 +1161,16 @@ find_page:
if (unlikely(page == NULL))
goto no_cached_page;
}
+ if (PageTransCompound(page)) {
+ struct page *head = compound_trans_head(page);
+ /*
+ * We don't yet support huge pages in page cache
+ * for filesystems with backing device, so pages
+ * should always be up-to-date.
+ */
+ BUG_ON(PageReadahead(head) || !PageUptodate(head));
+ goto page_ok;
+ }
if (PageReadahead(page)) {
page_cache_async_readahead(mapping,
ra, filp, page,
@@ -2439,8 +2449,13 @@ again:
if (mapping_writably_mapped(mapping))
flush_dcache_page(page);
+ if (PageTransHuge(page))
+ offset = pos & ~HPAGE_PMD_MASK;
+
pagefault_disable();
- copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
+ copied = iov_iter_copy_from_user_atomic(
+ page + (offset >> PAGE_CACHE_SHIFT),
+ i, offset & ~PAGE_CACHE_MASK, bytes);
pagefault_enable();
flush_dcache_page(page);
@@ -2463,6 +2478,7 @@ again:
* because not all segments in the iov can be copied at
* once without a pagefault.
*/
+ offset = pos & ~PAGE_CACHE_MASK;
bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
iov_iter_single_seg_count(i));
goto again;
--
1.7.10.4
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