[PATCH v2 8/8] vfs: remove redundant checks from generic_remap_checks()

From: Amir Goldstein <amir73il@gmail.com>
To: "Darrick J . Wong" <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@lst.de>,
	Olga Kornievskaia <olga.kornievskaia@gmail.com>,
	Luis Henriques <lhenriques@suse.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org,
	ceph-devel@vger.kernel.org, linux-api@vger.kernel.org
Subject: [PATCH v2 8/8] vfs: remove redundant checks from generic_remap_checks()
Date: Sun, 26 May 2019 09:10:59 +0300	[thread overview]
Message-ID: <20190526061100.21761-9-amir73il@gmail.com> (raw)
In-Reply-To: <20190526061100.21761-1-amir73il@gmail.com>

The access limit checks on input file range in generic_remap_checks()
are redundant because the input file size is guarantied to be within
limits and pos+len are already checked to be within input file size.

Beyond the fact that the check cannot fail, if it would have failed,
it could return -EFBIG for input file range error. There is no precedent
for that. -EFBIG is returned in syscalls that would change file length.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 mm/filemap.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 1852fbf08eeb..7e1aa36d57a2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3000,10 +3000,6 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in,
 		return -EINVAL;
 	count = min(count, size_in - (uint64_t)pos_in);
 
-	ret = generic_access_check_limits(file_in, pos_in, &count);
-	if (ret)
-		return ret;
-
 	ret = generic_write_check_limits(file_out, pos_out, &count);
 	if (ret)
 		return ret;
-- 
2.17.1

