Subject: + mm-readaheadc-fix-do_readahead-for-no-readpages.patch added to -mm tree
To: mark.rutland@xxxxxxx,kirill.shutemov@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 28 Jan 2014 13:10:46 -0800
The patch titled
Subject: mm/readahead.c: fix do_readahead() for no readpage(s)
has been added to the -mm tree. Its filename is
mm-readaheadc-fix-do_readahead-for-no-readpages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-readaheadc-fix-do_readahead-for-no-readpages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-readaheadc-fix-do_readahead-for-no-readpages.patch
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From: Mark Rutland <mark.rutland@xxxxxxx>
Subject: mm/readahead.c: fix do_readahead() for no readpage(s)
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>
---
mm/readahead.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
diff -puN mm/readahead.c~mm-readaheadc-fix-do_readahead-for-no-readpages mm/readahead.c
--- a/mm/readahead.c~mm-readaheadc-fix-do_readahead-for-no-readpages
+++ a/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 -mm which might be from mark.rutland@xxxxxxx are
origin.patch
mm-readaheadc-fix-do_readahead-for-no-readpages.patch
linux-next.patch
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