[LTP] [PATCH v4] vfs: fix readahead(2) on block devices

[Reuben Hawkins]

Readahead was factored to call generic_fadvise.  That refactor added an
S_ISREG restriction which broke readahead on block devices.

In addition to S_ISREG, this change checks S_ISBLK to fix block device
readahead.  There is no change in behavior with any file type besides block
devices in this change.

Fixes: 3d8f7615319b ("vfs: implement readahead(2) using POSIX_FADV_WILLNEED")
Signed-off-by: Reuben Hawkins <reubenhwk@gmail.com>
---
 mm/readahead.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/readahead.c b/mm/readahead.c
index e815c114de21..6925e6959fd3 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -735,7 +735,8 @@ ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
 	 */
 	ret = -EINVAL;
 	if (!f.file->f_mapping || !f.file->f_mapping->a_ops ||
-	    !S_ISREG(file_inode(f.file)->i_mode))
+	    (!S_ISREG(file_inode(f.file)->i_mode) &&
+	    !S_ISBLK(file_inode(f.file)->i_mode)))
 		goto out;
 
 	ret = vfs_fadvise(f.file, offset, count, POSIX_FADV_WILLNEED);
-- 
2.34.1