Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992446AbbEOV13 (ORCPT ); Fri, 15 May 2015 17:27:29 -0400 Received: from mail-ig0-f174.google.com ([209.85.213.174]:35461 "EHLO mail-ig0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946156AbbEOVYA (ORCPT ); Fri, 15 May 2015 17:24:00 -0400 From: Zach Brown To: Sage Weil , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org Subject: [PATCH RFC v2 1/2] vfs: add generic nocmtime mount flag Date: Fri, 15 May 2015 14:23:47 -0700 Message-Id: <1431725028-24071-2-git-send-email-zab@zabbo.net> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1431725028-24071-1-git-send-email-zab@zabbo.net> References: <1431725028-24071-1-git-send-email-zab@zabbo.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3593 Lines: 98 Add the infrastructure to support a generic nocmtime mount flag. Like MS_NOATIME/MNT_NOATIME this can be used to support the mount option in file systems without having to touch each file system. This will be used to provide a priviledged indication that unpriviledged apps can safely use O_NOCMTIME to prevent cmtime updates without harm. Signed-off-by: Zach Brown --- fs/namespace.c | 2 ++ fs/proc_namespace.c | 1 + fs/statfs.c | 2 ++ include/linux/mount.h | 1 + include/linux/statfs.h | 1 + include/uapi/linux/fs.h | 1 + 6 files changed, 8 insertions(+) diff --git a/fs/namespace.c b/fs/namespace.c index 1b9e111..48be1f9 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2652,6 +2652,8 @@ long do_mount(const char *dev_name, const char __user *dir_name, mnt_flags |= MNT_NOEXEC; if (flags & MS_NOATIME) mnt_flags |= MNT_NOATIME; + if (flags & MS_NOCMTIME) + mnt_flags |= MNT_NOCMTIME; if (flags & MS_NODIRATIME) mnt_flags |= MNT_NODIRATIME; if (flags & MS_STRICTATIME) diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c index 8db932d..49d7839 100644 --- a/fs/proc_namespace.c +++ b/fs/proc_namespace.c @@ -64,6 +64,7 @@ static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) { MNT_NODEV, ",nodev" }, { MNT_NOEXEC, ",noexec" }, { MNT_NOATIME, ",noatime" }, + { MNT_NOCMTIME, ",nocmtime" }, { MNT_NODIRATIME, ",nodiratime" }, { MNT_RELATIME, ",relatime" }, { 0, NULL } diff --git a/fs/statfs.c b/fs/statfs.c index 083dc0a..43d3de2 100644 --- a/fs/statfs.c +++ b/fs/statfs.c @@ -23,6 +23,8 @@ static int flags_by_mnt(int mnt_flags) flags |= ST_NOEXEC; if (mnt_flags & MNT_NOATIME) flags |= ST_NOATIME; + if (mnt_flags & MNT_NOCMTIME) + flags |= ST_NOCMTIME; if (mnt_flags & MNT_NODIRATIME) flags |= ST_NODIRATIME; if (mnt_flags & MNT_RELATIME) diff --git a/include/linux/mount.h b/include/linux/mount.h index f822c3c..deb458f 100644 --- a/include/linux/mount.h +++ b/include/linux/mount.h @@ -28,6 +28,7 @@ struct mnt_namespace; #define MNT_NODIRATIME 0x10 #define MNT_RELATIME 0x20 #define MNT_READONLY 0x40 /* does the user want this to be r/o? */ +#define MNT_NOCMTIME 0x80 /* allow O_NOCMTIME to stop cmtime updates */ #define MNT_SHRINKABLE 0x100 #define MNT_WRITE_HOLD 0x200 diff --git a/include/linux/statfs.h b/include/linux/statfs.h index 0166d32..bde224e 100644 --- a/include/linux/statfs.h +++ b/include/linux/statfs.h @@ -39,5 +39,6 @@ struct kstatfs { #define ST_NOATIME 0x0400 /* do not update access times */ #define ST_NODIRATIME 0x0800 /* do not update directory access times */ #define ST_RELATIME 0x1000 /* update atime relative to mtime/ctime */ +#define ST_NOCMTIME 0x2000 /* allow O_NOCMTIME to stop cmtime updates */ #endif diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 9b964a5..af1131e 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -91,6 +91,7 @@ struct inodes_stat_t { #define MS_I_VERSION (1<<23) /* Update inode I_version field */ #define MS_STRICTATIME (1<<24) /* Always perform atime updates */ #define MS_LAZYTIME (1<<25) /* Update the on-disk [acm]times lazily */ +#define MS_NOCMTIME (1<<26) /* allow O_NOCMTIME to stop cmtime updates */ /* These sb flags are internal to the kernel */ #define MS_NOSEC (1<<28) -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/