From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: [patch 20/21] vfs: no "(unreachable)" prefix for SYSVIPC maps in /proc/PID/maps Date: Fri, 18 Sep 2009 13:06:02 -0700 Message-ID: <200909182006.n8IK62Db019767@imap1.linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Cc: linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, mszeredi@suse.cz, Valdis.Kletnieks@vt.edu, agruen@suse.de, hch@lst.de, hugh.dickins@tiscali.co.uk, matthew@wil.cx To: viro@zeniv.linux.org.uk Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:56448 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757816AbZIRUMK (ORCPT ); Fri, 18 Sep 2009 16:12:10 -0400 Sender: linux-fsdevel-owner@vger.kernel.org List-ID: From: Miklos Szeredi The patch "vfs: fix d_path() for unreachable paths" generally changed d_path() to report unreachable paths with a special prefix. This has an effect on /proc/${PID}/maps as well for memory maps set up with shmem_file_setup() or hugetlb_file_setup(). These functions set up unlinked files under a kernel-private vfsmount. Since this vfsmount is unreachable from userspace, these maps will be reported with the "(unreachable)" prefix. This is undesirable, because it changes the kernel ABI and might break applications for no good reason. Signed-off-by: Miklos Szeredi Acked-by: Hugh Dickins Cc: Valdis Kletnieks Cc: Matthew Wilcox Cc: Andreas Gruenbacher Cc: Al Viro Cc: Christoph Hellwig Signed-off-by: Andrew Morton --- fs/hugetlbfs/inode.c | 17 +++++++++++++++++ mm/shmem.c | 17 +++++++++++++++++ 2 files changed, 34 insertions(+) diff -puN fs/hugetlbfs/inode.c~vfs-no-unreachable-prefix-for-sysvipc-maps-in-proc-pid-maps fs/hugetlbfs/inode.c --- a/fs/hugetlbfs/inode.c~vfs-no-unreachable-prefix-for-sysvipc-maps-in-proc-pid-maps +++ a/fs/hugetlbfs/inode.c @@ -906,6 +906,21 @@ static struct file_system_type hugetlbfs static struct vfsmount *hugetlbfs_vfsmount; +/* + * Do a special d_dname function so that these are not prefixed by + * "(unreachable)". + */ +static char *hugetlb_unlinked_d_dname(struct dentry *dentry, char *buf, + int buflen) +{ + return dynamic_dname(dentry, buf, buflen, "/%s (deleted)", + dentry->d_name.name); +} + +static struct dentry_operations hugetlb_unlinked_dentry_operations = { + .d_dname = hugetlb_unlinked_d_dname, +}; + static int can_do_hugetlb_shm(void) { return capable(CAP_IPC_LOCK) || in_group_p(sysctl_hugetlb_shm_group); @@ -943,6 +958,8 @@ struct file *hugetlb_file_setup(const ch if (!dentry) goto out_shm_unlock; + dentry->d_op = &hugetlb_unlinked_dentry_operations; + error = -ENOSPC; inode = hugetlbfs_get_inode(root->d_sb, current_fsuid(), current_fsgid(), S_IFREG | S_IRWXUGO, 0); diff -puN mm/shmem.c~vfs-no-unreachable-prefix-for-sysvipc-maps-in-proc-pid-maps mm/shmem.c --- a/mm/shmem.c~vfs-no-unreachable-prefix-for-sysvipc-maps-in-proc-pid-maps +++ a/mm/shmem.c @@ -2602,6 +2602,21 @@ int shmem_unuse(swp_entry_t entry, struc /* common code */ +/* + * Do a special d_dname function so that these are not prefixed by + * "(unreachable)". + */ +static char *shmem_unlinked_d_dname(struct dentry *dentry, char *buf, + int buflen) +{ + return dynamic_dname(dentry, buf, buflen, "/%s (deleted)", + dentry->d_name.name); +} + +static struct dentry_operations shmem_unlinked_dentry_operations = { + .d_dname = shmem_unlinked_d_dname, +}; + /** * shmem_file_setup - get an unlinked file living in tmpfs * @name: name for dentry (to be seen in /proc//maps @@ -2634,6 +2649,8 @@ struct file *shmem_file_setup(const char if (!dentry) goto put_memory; + dentry->d_op = &shmem_unlinked_dentry_operations; + error = -ENFILE; file = get_empty_filp(); if (!file) _