From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422647AbWF0WSK (ORCPT ); Tue, 27 Jun 2006 18:18:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422648AbWF0WPQ (ORCPT ); Tue, 27 Jun 2006 18:15:16 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:53418 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S1030472AbWF0WPB (ORCPT ); Tue, 27 Jun 2006 18:15:01 -0400 Subject: [PATCH 19/20] elevate writer count for custom 'struct file' To: akpm@osdl.org Cc: linux-kernel@vger.kernel.org, herbert@13thfloor.at, viro@ftp.linux.org.uk, serue@us.ibm.com, Dave Hansen From: Dave Hansen Date: Tue, 27 Jun 2006 15:14:56 -0700 References: <20060627221436.77CCB048@localhost.localdomain> In-Reply-To: <20060627221436.77CCB048@localhost.localdomain> Message-Id: <20060627221456.F6AD6304@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Some filesystems forego the vfs and may_open() and create their own 'struct file's. Any of these users which set the write flag on the file will cause an extra mnt_drop_write() on __fput(), thus dropping the reference count too low. These users tend to have artifical in-kernel vfsmounts which aren't really exposed to userspace and can't be remounted, but this patch is included for completeness and so that the warnings don't trip over these cases. Signed-off-by: Dave Hansen --- lxc-dave/fs/hugetlbfs/inode.c | 2 ++ lxc-dave/mm/shmem.c | 2 ++ lxc-dave/mm/tiny-shmem.c | 2 ++ lxc-dave/net/socket.c | 3 +++ 4 files changed, 9 insertions(+) diff -puN fs/hugetlbfs/inode.c~fix-__fput-rev2 fs/hugetlbfs/inode.c --- lxc/fs/hugetlbfs/inode.c~fix-__fput-rev2 2006-06-27 10:40:35.000000000 -0700 +++ lxc-dave/fs/hugetlbfs/inode.c 2006-06-27 10:40:35.000000000 -0700 @@ -790,6 +790,8 @@ struct file *hugetlb_zero_setup(size_t s file->f_mapping = inode->i_mapping; file->f_op = &hugetlbfs_file_operations; file->f_mode = FMODE_WRITE | FMODE_READ; + error = mnt_want_write(hugetlbfs_vfsmount); + WARN_ON(error); return file; out_inode: diff -puN mm/shmem.c~fix-__fput-rev2 mm/shmem.c --- lxc/mm/shmem.c~fix-__fput-rev2 2006-06-27 10:40:35.000000000 -0700 +++ lxc-dave/mm/shmem.c 2006-06-27 10:40:35.000000000 -0700 @@ -2326,6 +2326,8 @@ struct file *shmem_file_setup(char *name file->f_mapping = inode->i_mapping; file->f_op = &shmem_file_operations; file->f_mode = FMODE_WRITE | FMODE_READ; + error = mnt_want_write(shm_mnt); + WARN_ON(error); return file; close_file: diff -puN mm/tiny-shmem.c~fix-__fput-rev2 mm/tiny-shmem.c --- lxc/mm/tiny-shmem.c~fix-__fput-rev2 2006-06-27 10:40:35.000000000 -0700 +++ lxc-dave/mm/tiny-shmem.c 2006-06-27 10:40:35.000000000 -0700 @@ -88,6 +88,8 @@ struct file *shmem_file_setup(char *name file->f_mapping = inode->i_mapping; file->f_op = &ramfs_file_operations; file->f_mode = FMODE_WRITE | FMODE_READ; + error = mnt_want_write(shm_mnt); + WARN_ON(error); /* notify everyone as to the change of file size */ error = do_truncate(dentry, size, 0, file); diff -puN net/socket.c~fix-__fput-rev2 net/socket.c --- lxc/net/socket.c~fix-__fput-rev2 2006-06-27 10:40:35.000000000 -0700 +++ lxc-dave/net/socket.c 2006-06-27 10:40:35.000000000 -0700 @@ -396,6 +396,7 @@ static int sock_attach_fd(struct socket { struct qstr this; char name[32]; + int error; this.len = sprintf(name, "[%lu]", SOCK_INODE(sock)->i_ino); this.name = name; @@ -416,6 +417,8 @@ static int sock_attach_fd(struct socket file->f_flags = O_RDWR; file->f_pos = 0; file->private_data = sock; + error = mnt_want_write(sock_mnt); + WARN_ON(error); return 0; } _