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authorMark Rutland <mark.rutland@arm.com>2014-01-29 14:05:51 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-29 16:22:40 -0800
commit58d5640ebdb273cc817b0d0cda7bcf2efbbc2ff7 (patch)
tree9f4c83901b87b3c7d90d93c4b054c04ef4ef9700 /mm
parenta0132ac0f275434db32111b8cf7372d991899da3 (diff)
downloadlinux-58d5640ebdb273cc817b0d0cda7bcf2efbbc2ff7.tar.gz
mm/readahead.c: fix do_readahead() for no readpage(s)
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@arm.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/readahead.c15
1 files changed, 5 insertions, 10 deletions
diff --git a/mm/readahead.c b/mm/readahead.c
index 7cdbb44aa90..0de2360d65f 100644
--- 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 address_space *mapping, struct file *filp,
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 *mapping, struct file *filp,
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)