Overlayfs implements stacked file operations, but does not implement
stacked a_ops, so passing an overlayfs file to do_readahead() results
in an error.
Fix this by passing the real underlying file to do_readahead().
Fixes: d1d04ef8572b ("ovl: stack file ops")
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
mm/readahead.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/mm/readahead.c b/mm/readahead.c
index a59ea70527b9..dc9c64ce6094 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -602,11 +602,16 @@ ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
f = fdget(fd);
if (f.file) {
if (f.file->f_mode & FMODE_READ) {
- struct address_space *mapping = f.file->f_mapping;
+ /*
+ * XXX: We need to use file_real(), because overlayfs
+ * stacked file/inode do not implement page io.
+ */
+ struct file *file = file_real(f.file);
+ struct address_space *mapping = file->f_mapping;
pgoff_t start = offset >> PAGE_SHIFT;
pgoff_t end = (offset + count - 1) >> PAGE_SHIFT;
unsigned long len = end - start + 1;
- ret = do_readahead(mapping, f.file, start, len);
+ ret = do_readahead(mapping, file, start, len);
}
fdput(f);
}
--
2.7.4
