From: David Howells <dhowells@redhat.com>
To: viro@zeniv.linux.org.uk
Cc: torvalds@linux-foundation.org, dhowells@redhat.com,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 03/38] teach move_mount(2) to work with OPEN_TREE_CLONE [ver #10]
Date: Fri, 27 Jul 2018 18:31:43 +0100 [thread overview]
Message-ID: <153271270374.9458.14888440216312686324.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <153271267980.9458.7640156373438016898.stgit@warthog.procyon.org.uk>
From: Al Viro <viro@zeniv.linux.org.uk>
Allow a detached tree created by open_tree(..., OPEN_TREE_CLONE) to be
attached by move_mount(2).
If by the time of final fput() of OPEN_TREE_CLONE-opened file its tree is
not detached anymore, it won't be dissolved. move_mount(2) is adjusted
to handle detached source.
That gives us equivalents of mount --bind and mount --rbind.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
---
fs/namespace.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index e2934a4f342b..3981fd7b13f5 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1846,8 +1846,10 @@ void dissolve_on_fput(struct vfsmount *mnt)
{
namespace_lock();
lock_mount_hash();
- mntget(mnt);
- umount_tree(real_mount(mnt), UMOUNT_SYNC);
+ if (!real_mount(mnt)->mnt_ns) {
+ mntget(mnt);
+ umount_tree(real_mount(mnt), UMOUNT_SYNC);
+ }
unlock_mount_hash();
namespace_unlock();
}
@@ -2454,6 +2456,7 @@ static int do_move_mount(struct path *old_path, struct path *new_path)
struct mount *old;
struct mountpoint *mp;
int err;
+ bool attached;
mp = lock_mount(new_path);
err = PTR_ERR(mp);
@@ -2464,10 +2467,19 @@ static int do_move_mount(struct path *old_path, struct path *new_path)
p = real_mount(new_path->mnt);
err = -EINVAL;
- if (!check_mnt(p) || !check_mnt(old))
+ /* The mountpoint must be in our namespace. */
+ if (!check_mnt(p))
+ goto out1;
+ /* The thing moved should be either ours or completely unattached. */
+ if (old->mnt_ns && !check_mnt(old))
goto out1;
- if (!mnt_has_parent(old))
+ attached = mnt_has_parent(old);
+ /*
+ * We need to allow open_tree(OPEN_TREE_CLONE) followed by
+ * move_mount(), but mustn't allow "/" to be moved.
+ */
+ if (old->mnt_ns && !attached)
goto out1;
if (old->mnt.mnt_flags & MNT_LOCKED)
@@ -2482,7 +2494,7 @@ static int do_move_mount(struct path *old_path, struct path *new_path)
/*
* Don't move a mount residing in a shared parent.
*/
- if (IS_MNT_SHARED(old->mnt_parent))
+ if (attached && IS_MNT_SHARED(old->mnt_parent))
goto out1;
/*
* Don't move a mount tree containing unbindable mounts to a destination
@@ -2496,7 +2508,7 @@ static int do_move_mount(struct path *old_path, struct path *new_path)
goto out1;
err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp,
- &parent_path);
+ attached ? &parent_path : NULL);
if (err)
goto out1;
@@ -3182,6 +3194,8 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
/*
* Move a mount from one place to another.
+ * In combination with open_tree(OPEN_TREE_CLONE [| AT_RECURSIVE]) it can be
+ * used to copy a mount subtree.
*
* Note the flags value is a combination of MOVE_MOUNT_* flags.
*/
next prev parent reply other threads:[~2018-07-27 18:54 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-27 17:31 [PATCH 00/38] VFS: Introduce filesystem context [ver #10] David Howells
2018-07-27 17:31 ` [PATCH 01/38] vfs: syscall: Add open_tree(2) to reference or clone a mount " David Howells
2018-07-27 17:31 ` [PATCH 02/38] vfs: syscall: Add move_mount(2) to move mounts around " David Howells
2018-07-27 17:31 ` David Howells [this message]
2018-07-27 17:31 ` [PATCH 04/38] vfs: Suppress MS_* flag defs within the kernel unless explicitly enabled " David Howells
2018-07-27 17:31 ` [PATCH 05/38] vfs: Introduce the basic header for the new mount API's filesystem context " David Howells
2018-07-27 17:32 ` [PATCH 06/38] vfs: Introduce logging functions " David Howells
2018-07-27 17:32 ` [PATCH 07/38] vfs: Add configuration parser helpers " David Howells
2018-07-27 17:32 ` [PATCH 08/38] vfs: Add LSM hooks for the new mount API " David Howells
2018-07-27 17:32 ` [PATCH 09/38] selinux: Implement the new mount API LSM hooks " David Howells
2018-07-27 17:32 ` [PATCH 10/38] smack: Implement filesystem context security " David Howells
2018-07-27 17:32 ` [PATCH 11/38] apparmor: Implement security hooks for the new mount API " David Howells
2018-07-27 17:32 ` [PATCH 12/38] vfs: Pass key and value into LSM and FS and provide a helper parser " David Howells
2018-07-27 17:32 ` [PATCH 13/38] tomoyo: Implement security hooks for the new mount API " David Howells
2018-07-28 2:29 ` Tetsuo Handa
2018-07-30 10:49 ` David Howells
2018-07-27 17:32 ` [PATCH 14/38] vfs: Separate changing mount flags full remount " David Howells
2018-07-27 17:33 ` [PATCH 15/38] vfs: Implement a filesystem superblock creation/configuration context " David Howells
2018-07-27 17:33 ` [PATCH 16/38] vfs: Remove unused code after filesystem context changes " David Howells
2018-07-27 17:33 ` [PATCH 17/38] procfs: Move proc_fill_super() to fs/proc/root.c " David Howells
2018-07-27 17:33 ` [PATCH 18/38] proc: Add fs_context support to procfs " David Howells
2018-07-27 17:33 ` [PATCH 19/38] ipc: Convert mqueue fs to fs_context " David Howells
2018-07-27 17:33 ` [PATCH 20/38] cpuset: Use " David Howells
2018-07-27 17:33 ` [PATCH 21/38] kernfs, sysfs, cgroup, intel_rdt: Support " David Howells
2018-07-27 17:33 ` [PATCH 22/38] hugetlbfs: Convert to " David Howells
2018-07-27 17:33 ` [PATCH 23/38] vfs: Remove kern_mount_data() " David Howells
2018-07-27 17:34 ` [PATCH 24/38] vfs: Provide documentation for new mount API " David Howells
2018-07-27 17:34 ` [PATCH 25/38] Make anon_inodes unconditional " David Howells
2018-07-27 20:04 ` Randy Dunlap
2018-07-30 10:52 ` David Howells
2018-07-27 17:34 ` [PATCH 26/38] vfs: syscall: Add fsopen() to prepare for superblock creation " David Howells
2018-07-27 17:34 ` [PATCH 27/38] vfs: Implement logging through fs_context " David Howells
2018-07-27 17:34 ` [PATCH 28/38] vfs: Add some logging to the core users of the fs_context log " David Howells
2018-07-27 17:34 ` [PATCH 29/38] vfs: syscall: Add fsconfig() for configuring and managing a context " David Howells
2018-07-27 19:42 ` Andy Lutomirski
2018-07-27 21:51 ` David Howells
2018-07-27 21:57 ` Andy Lutomirski
2018-07-27 22:27 ` David Howells
2018-07-27 22:32 ` Jann Horn
2018-07-29 8:50 ` David Howells
2018-07-29 11:14 ` Jann Horn
2018-07-30 12:32 ` David Howells
2018-07-27 17:34 ` [PATCH 30/38] vfs: syscall: Add fsmount() to create a mount for a superblock " David Howells
2018-07-27 19:27 ` Andy Lutomirski
2018-07-27 19:43 ` Andy Lutomirski
2018-07-27 22:09 ` David Howells
2018-07-27 22:06 ` David Howells
2018-07-27 17:34 ` [PATCH 31/38] vfs: syscall: Add fspick() to select a superblock for reconfiguration " David Howells
2018-07-27 17:34 ` [PATCH 32/38] afs: Add fs_context support " David Howells
2018-07-27 17:35 ` [PATCH 33/38] afs: Use fs_context to pass parameters over automount " David Howells
2018-07-27 17:35 ` [PATCH 34/38] vfs: syscall: Add fsinfo() to query filesystem information " David Howells
2018-07-27 19:35 ` Andy Lutomirski
2018-07-27 22:12 ` David Howells
2018-07-27 23:14 ` Jann Horn
2018-07-27 23:49 ` David Howells
2018-07-28 0:14 ` Anton Altaparmakov
2018-07-27 23:51 ` David Howells
2018-07-27 23:58 ` Jann Horn
2018-07-28 0:08 ` David Howells
2018-07-30 14:48 ` David Howells
2018-07-31 4:16 ` Al Viro
2018-07-31 12:39 ` David Howells
2018-07-31 13:20 ` David Howells
2018-07-31 23:49 ` Darrick J. Wong
2018-08-01 1:07 ` David Howells
2018-07-27 17:35 ` [PATCH 35/38] afs: Add fsinfo support " David Howells
2018-07-27 17:35 ` [PATCH 36/38] vfs: Add a sample program for the new mount API " David Howells
2018-07-29 11:37 ` Pavel Machek
2018-07-30 12:23 ` David Howells
2018-07-30 14:31 ` Pavel Machek
2018-07-30 18:08 ` Matthew Wilcox
2018-07-30 18:16 ` Pavel Machek
2018-07-30 18:18 ` Linus Torvalds
2018-07-30 18:38 ` Matthew Wilcox
2018-07-30 18:59 ` Linus Torvalds
2018-07-30 19:49 ` Matthew Wilcox
2018-07-30 21:02 ` Theodore Y. Ts'o
2018-07-30 21:23 ` Pavel Machek
2018-07-30 23:58 ` Matthew Wilcox
2018-07-31 0:58 ` Theodore Y. Ts'o
2018-07-31 9:40 ` Pavel Machek
2018-07-31 10:11 ` David Howells
2018-07-31 11:34 ` Pavel Machek
2018-07-31 12:07 ` Matthew Wilcox
2018-07-31 12:28 ` Pavel Machek
2018-07-31 13:33 ` Al Viro
2018-07-31 13:00 ` David Howells
2018-07-31 19:39 ` Pavel Machek
2018-07-31 21:00 ` David Howells
2018-07-31 21:21 ` Linus Torvalds
2018-07-31 21:38 ` David Howells
2018-07-30 20:47 ` Pavel Machek
2018-07-30 15:33 ` David Howells
2018-07-30 17:30 ` Pavel Machek
2018-07-30 17:54 ` Linus Torvalds
2018-07-30 18:16 ` Pavel Machek
2018-07-27 17:35 ` [PATCH 37/38] vfs: Allow fsinfo() to query what's in an fs_context " David Howells
2018-07-27 17:35 ` [PATCH 38/38] vfs: Allow fsinfo() to be used to query an fs parameter description " David Howells
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