From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-f65.google.com ([209.85.128.65]:38644 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727074AbfEaQrS (ORCPT ); Fri, 31 May 2019 12:47:18 -0400 From: Amir Goldstein Subject: [PATCH v4 4/9] vfs: remove redundant checks from generic_remap_checks() Date: Fri, 31 May 2019 19:46:56 +0300 Message-Id: <20190531164701.15112-5-amir73il@gmail.com> In-Reply-To: <20190531164701.15112-1-amir73il@gmail.com> References: <20190531164701.15112-1-amir73il@gmail.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: "Darrick J . Wong" Cc: Dave Chinner , Christoph Hellwig , linux-xfs@vger.kernel.org, Olga Kornievskaia , Luis Henriques , Al Viro , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, ceph-devel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org The access limit checks on input file range in generic_remap_checks() are redundant because the input file size is guaranteed 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. With that call removed, we can fold generic_access_check_limits() into generic_write_check_limits(). Signed-off-by: Amir Goldstein Reviewed-by: Darrick J. Wong --- mm/filemap.c | 33 ++++++++++++--------------------- 1 file changed, 12 insertions(+), 21 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index a38619a4a6af..44361928bbb0 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2895,24 +2895,11 @@ EXPORT_SYMBOL(read_cache_page_gfp); * LFS limits. If pos is under the limit it becomes a short access. If it * exceeds the limit we return -EFBIG. */ -static int generic_access_check_limits(struct file *file, loff_t pos, - loff_t *count) -{ - struct inode *inode = file->f_mapping->host; - loff_t max_size = inode->i_sb->s_maxbytes; - - if (!(file->f_flags & O_LARGEFILE)) - max_size = MAX_NON_LFS; - - if (unlikely(pos >= max_size)) - return -EFBIG; - *count = min(*count, max_size - pos); - return 0; -} - static int generic_write_check_limits(struct file *file, loff_t pos, loff_t *count) { + struct inode *inode = file->f_mapping->host; + loff_t max_size = inode->i_sb->s_maxbytes; loff_t limit = rlimit(RLIMIT_FSIZE); if (limit != RLIM_INFINITY) { @@ -2923,7 +2910,15 @@ static int generic_write_check_limits(struct file *file, loff_t pos, *count = min(*count, limit - pos); } - return generic_access_check_limits(file, pos, count); + if (!(file->f_flags & O_LARGEFILE)) + max_size = MAX_NON_LFS; + + if (unlikely(pos >= max_size)) + return -EFBIG; + + *count = min(*count, max_size - pos); + + return 0; } /* @@ -2963,7 +2958,7 @@ EXPORT_SYMBOL(generic_write_checks); /* * Performs necessary checks before doing a clone. * - * Can adjust amount of bytes to clone. + * Can adjust amount of bytes to clone via @req_count argument. * Returns appropriate error code that caller should return or * zero in case the clone should be allowed. */ @@ -3001,10 +2996,6 @@ 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