[PATCH] ramfs: Fix nommu mmap with gaps in the page cache

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

From: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>

ramfs needs to check that pages are both physically contiguous and
contiguous in the file.  If the page cache happens to have, eg, page A
for index 0 of the file, no page for index 1, and page A+1 for index 2,
then an mmap of the first two pages of the file will succeed when it
should fail.

Fixes: 642fb4d1f1dd ("[PATCH] NOMMU: Provide shared-writable mmap support on ramfs")
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>

diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
index 414695454956..355523f4a4bf 100644
--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -224,7 +224,7 @@ static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
 	if (!pages)
 		goto out_free;
 
-	nr = find_get_pages(inode->i_mapping, &pgoff, lpages, pages);
+	nr = find_get_pages_contig(inode->i_mapping, pgoff, lpages, pages);
 	if (nr != lpages)
 		goto out_free_pages; /* leave if some pages were missing */