This is a note to let you know that I've just added the patch titled
mm/readahead.c: fix do_readahead() for no readpage(s)
to the 3.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-readahead.c-fix-do_readahead-for-no-readpage-s.patch
and it can be found in the queue-3.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 58d5640ebdb273cc817b0d0cda7bcf2efbbc2ff7 Mon Sep 17 00:00:00 2001
From: Mark Rutland <mark.rutland@xxxxxxx>
Date: Wed, 29 Jan 2014 14:05:51 -0800
Subject: mm/readahead.c: fix do_readahead() for no readpage(s)
From: Mark Rutland <mark.rutland@xxxxxxx>
commit 58d5640ebdb273cc817b0d0cda7bcf2efbbc2ff7 upstream.
Commit 63d0f0a3c7e1 ("mm/readahead.c:do_readhead(): don't check for
->readpage") unintentionally made do_readahead return 0 for all valid
files regardless of whether readahead was supported, rather than the
expected -EINVAL. This gets forwarded on to userspace, and results in
sys_readahead appearing to succeed in cases that don't make sense (e.g.
when called on pipes or sockets). This issue is detected by the LTP
readahead01 testcase.
As the exact return value of force_page_cache_readahead is currently
never used, we can simplify it to return only 0 or -EINVAL (when
readpage or readpages is missing). With that in place we can simply
forward on the return value of force_page_cache_readahead in
do_readahead.
This patch performs said change, restoring the expected semantics.
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/readahead.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -211,8 +211,6 @@ out:
int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
pgoff_t offset, unsigned long nr_to_read)
{
- int ret = 0;
-
if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages))
return -EINVAL;
@@ -226,15 +224,13 @@ int force_page_cache_readahead(struct ad
this_chunk = nr_to_read;
err = __do_page_cache_readahead(mapping, filp,
offset, this_chunk, 0);
- if (err < 0) {
- ret = err;
- break;
- }
- ret += err;
+ if (err < 0)
+ return err;
+
offset += this_chunk;
nr_to_read -= this_chunk;
}
- return ret;
+ return 0;
}
/*
@@ -576,8 +572,7 @@ do_readahead(struct address_space *mappi
if (!mapping || !mapping->a_ops)
return -EINVAL;
- force_page_cache_readahead(mapping, filp, index, nr);
- return 0;
+ return force_page_cache_readahead(mapping, filp, index, nr);
}
SYSCALL_DEFINE3(readahead, int, fd, loff_t, offset, size_t, count)
Patches currently in stable-queue which might be from mark.rutland@xxxxxxx are
queue-3.13/mm-readahead.c-fix-do_readahead-for-no-readpage-s.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html