Hi AKPM and folks,
LTP test readahead syscall return value like this:
=====================
static void test_invalid_fd(void)
{
int fd[2];
tst_resm(TINFO, "test_invalid_fd pipe");
if (pipe(fd) < 0)
tst_resm(TBROK | TERRNO, "Failed to create pipe");
TEST(ltp_syscall(__NR_readahead, fd[0], 0, getpagesize()));
check_ret(-1);
check_errno(EINVAL);
close(fd[0]);
close(fd[1]);
tst_resm(TINFO, "test_invalid_fd socket");
fd[0] = socket(AF_INET, SOCK_STREAM, 0);
if (fd[0] < 0)
tst_resm(TBROK | TERRNO, "Failed to create socket");
TEST(ltp_syscall(__NR_readahead, fd[0], 0, getpagesize()));
check_ret(-1);
check_errno(EINVAL);
close(fd[0]);
}
====================================
FULL case code:
https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/readahead/readahead01.c
This case passed before the following kernel commit[1],
it means kernel will return -1 with errno=EINVAL. But after
this commit[1], kernel will return 0 here.
The different between before and after this commit[1] is that:
BEFORE:
=============
do_readahead():
if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
return EINVAL;
============
AFTER:
======================
do_readahead():
if (!mapping || !mapping->a_ops)
return EINVAL;
And followed with:
force_page_cache_readahead():
if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages))
return -EINVAL;
=====================
I think you must know which is right?
Thanks,
Wanlong Gao
[1]:
commit 63d0f0a3c7e1281fd79268a8d988167eff607fb6
Author: Andrew Morton <a...@linux-foundation.org>
Date: Tue Nov 12 15:07:09 2013 -0800
mm/readahead.c:do_readhead(): don't check for ->readpage
The callee force_page_cache_readahead() already does this and unlike
do_readahead(), force_page_cache_readahead() remembers to check for
->readpages() as well.
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
diff --git a/mm/readahead.c b/mm/readahead.c
index e4ed041..5024183 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -569,7 +569,7 @@ static ssize_t
do_readahead(struct address_space *mapping, struct file *filp,
pgoff_t index, unsigned long nr)
{
- if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
+ if (!mapping || !mapping->a_ops)
return -EINVAL;
force_page_cache_readahead(mapping, filp, index, nr);
--
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