Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760986AbYBMFpl (ORCPT ); Wed, 13 Feb 2008 00:45:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756102AbYBMFpb (ORCPT ); Wed, 13 Feb 2008 00:45:31 -0500 Received: from smtp-out.google.com ([216.239.33.17]:54583 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751789AbYBMFpa (ORCPT ); Wed, 13 Feb 2008 00:45:30 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:message-id:date:from:user-agent:mime-version:to:cc: subject:content-type:content-transfer-encoding; b=drTUj/oWFA/hmyqgaX9LIr/543c51ZbAgTsXBenfYFIFu+GcAcNGPCPSvcTF81Q6K jEeNXfkZ8PmOj9Y6hgSdg== Message-ID: <47B283EB.8070209@google.com> Date: Tue, 12 Feb 2008 21:45:15 -0800 From: Paul Menage User-Agent: Thunderbird 1.5.0.14pre (X11/20071022) MIME-Version: 1.0 To: Alexander Viro , Andrew Morton CC: linux-kernel@vger.kernel.org Subject: [PATCH] Add MS_BIND_FLAGS mount flag Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5010 Lines: 145 From: Paul Menage Add a new mount() flag, MS_BIND_FLAGS. MS_BIND_FLAGS indicates that a bind mount should take its per-mount flags from the arguments passed to mount() rather than from the source mountpoint. This flag allows you to create a bind mount with the desired per-mount flags in a single operation, rather than having to do a bind mount followed by a remount, which is fiddly and can block for non-trivial periods of time (on sb->s_umount?). For recursive bind mounts, only the root of the tree being bound inherits the per-mount flags from the mount() arguments; sub-mounts inherit their per-mount flags from the source tree as usual. Signed-off-by: Paul Menage --- fs/namespace.c | 36 +++++++++++++++++++++++++----------- include/linux/fs.h | 2 ++ 2 files changed, 27 insertions(+), 11 deletions(-) Index: 2.6.24-mm1-bindflags/fs/namespace.c =================================================================== --- 2.6.24-mm1-bindflags.orig/fs/namespace.c +++ 2.6.24-mm1-bindflags/fs/namespace.c @@ -512,13 +512,13 @@ static struct vfsmount *skip_mnt_tree(st } static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, - int flag) + int flag, int mnt_flags) { struct super_block *sb = old->mnt_sb; struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); if (mnt) { - mnt->mnt_flags = old->mnt_flags; + mnt->mnt_flags = mnt_flags; atomic_inc(&sb->s_active); mnt->mnt_sb = sb; mnt->mnt_root = dget(root); @@ -1095,8 +1095,9 @@ static int lives_below_in_same_fs(struct } } -struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, - int flag) +static struct vfsmount * +__copy_tree(struct vfsmount *mnt, struct dentry *dentry, + int flag, int mnt_flags) { struct vfsmount *res, *p, *q, *r, *s; struct nameidata nd; @@ -1104,7 +1105,7 @@ struct vfsmount *copy_tree(struct vfsmou if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) return NULL; - res = q = clone_mnt(mnt, dentry, flag); + res = q = clone_mnt(mnt, dentry, flag, mnt_flags); if (!q) goto Enomem; q->mnt_mountpoint = mnt->mnt_mountpoint; @@ -1126,7 +1127,7 @@ struct vfsmount *copy_tree(struct vfsmou p = s; nd.path.mnt = q; nd.path.dentry = p->mnt_mountpoint; - q = clone_mnt(p, p->mnt_root, flag); + q = clone_mnt(p, p->mnt_root, flag, p->mnt_flags); if (!q) goto Enomem; spin_lock(&vfsmount_lock); @@ -1146,6 +1147,11 @@ Enomem: } return NULL; } +struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, + int flag) +{ + return __copy_tree(mnt, dentry, flag, mnt->mnt_flags); +} struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry) { @@ -1320,7 +1326,8 @@ static int do_change_type(struct nameida /* * do loopback mount. */ -static int do_loopback(struct nameidata *nd, char *old_name, int recurse) +static int do_loopback(struct nameidata *nd, char *old_name, int flags, + int mnt_flags) { struct nameidata old_nd; struct vfsmount *mnt = NULL; @@ -1342,10 +1349,15 @@ static int do_loopback(struct nameidata goto out; err = -ENOMEM; - if (recurse) - mnt = copy_tree(old_nd.path.mnt, old_nd.path.dentry, 0); + /* Use the source mount flags unless the user passed MS_BIND_FLAGS */ + if (!(flags & MS_BIND_FLAGS)) + mnt_flags = old_nd.path.mnt->mnt_flags; + if (flags & MS_REC) + mnt = __copy_tree(old_nd.path.mnt, old_nd.path.dentry, 0, + mnt_flags); else - mnt = clone_mnt(old_nd.path.mnt, old_nd.path.dentry, 0); + mnt = clone_mnt(old_nd.path.mnt, old_nd.path.dentry, 0, + mnt_flags); if (!mnt) goto out; @@ -1874,7 +1886,9 @@ long do_mount(char *dev_name, char *dir_ retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, data_page); else if (flags & MS_BIND) - retval = do_loopback(&nd, dev_name, flags & MS_REC); + retval = do_loopback(&nd, dev_name, + flags & (MS_REC | MS_BIND_FLAGS), + mnt_flags); else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) retval = do_change_type(&nd, flags); else if (flags & MS_MOVE) Index: 2.6.24-mm1-bindflags/include/linux/fs.h =================================================================== --- 2.6.24-mm1-bindflags.orig/include/linux/fs.h +++ 2.6.24-mm1-bindflags/include/linux/fs.h @@ -125,6 +125,8 @@ extern int dir_notify_enable; #define MS_RELATIME (1<<21) /* Update atime relative to mtime/ctime. */ #define MS_KERNMOUNT (1<<22) /* this is a kern_mount call */ #define MS_I_VERSION (1<<23) /* Update inode I_version field */ +#define MS_BIND_FLAGS (1<<24) /* For MS_BIND, take mnt_flags from + * args, not from source mountpoint */ #define MS_ACTIVE (1<<30) #define MS_NOUSER (1<<31) -- 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/