[PATCH] shared mounts handling: move
Implement handling of mount --move in presense of shared mounts (see Documentation/sharedsubtree.txt in the end of patch series for detailed description). Signed-off-by: Ram Pai <linuxram@us.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>wifi-calibration
Ram Pai
Linus Torvalds
parent
b90fa9ae8f
commit
2144440327
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@ -660,7 +660,10 @@ Enomem:
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/*
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* @source_mnt : mount tree to be attached
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* @nd : place the mount tree @source_mnt is attached
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* @nd : place the mount tree @source_mnt is attached
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* @parent_nd : if non-null, detach the source_mnt from its parent and
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* store the parent mount and mountpoint dentry.
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* (done when source_mnt is moved)
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*
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* NOTE: in the table below explains the semantics when a source mount
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* of a given type is attached to a destination mount of a given type.
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@ -685,6 +688,21 @@ Enomem:
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* (+) the cloned mount is created under the destination mount and is marked
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* as shared. The cloned mount is added to the peer group of the source
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* mount.
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* ---------------------------------------------
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* | MOVE MOUNT OPERATION |
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* |********************************************
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* | source-->| shared | private |
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* | dest | | |
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* | | | | |
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* | v | | |
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* |********************************************
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* | shared | shared (+) | shared (+) |
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* | | | |
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* |non-shared| shared (+*) | private |
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* *********************************************
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* (+) the mount is moved to the destination. And is then propagated to all
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* the mounts in the propagation tree of the destination mount.
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* (+*) the mount is moved to the destination.
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*
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* if the source mount is a tree, the operations explained above is
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* applied to each mount in the tree.
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@ -692,7 +710,7 @@ Enomem:
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* in allocations.
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*/
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static int attach_recursive_mnt(struct vfsmount *source_mnt,
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struct nameidata *nd)
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struct nameidata *nd, struct nameidata *parent_nd)
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{
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LIST_HEAD(tree_list);
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struct vfsmount *dest_mnt = nd->mnt;
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@ -708,8 +726,14 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt,
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}
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spin_lock(&vfsmount_lock);
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mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
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commit_tree(source_mnt);
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if (parent_nd) {
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detach_mnt(source_mnt, parent_nd);
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attach_mnt(source_mnt, nd);
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touch_namespace(current->namespace);
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} else {
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mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
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commit_tree(source_mnt);
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}
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list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
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list_del_init(&child->mnt_hash);
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@ -740,7 +764,7 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
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err = -ENOENT;
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if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry))
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err = attach_recursive_mnt(mnt, nd);
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err = attach_recursive_mnt(mnt, nd, NULL);
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out_unlock:
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up(&nd->dentry->d_inode->i_sem);
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if (!err)
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@ -869,35 +893,36 @@ static int do_move_mount(struct nameidata *nd, char *old_name)
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if (IS_DEADDIR(nd->dentry->d_inode))
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goto out1;
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spin_lock(&vfsmount_lock);
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if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry))
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goto out2;
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goto out1;
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err = -EINVAL;
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if (old_nd.dentry != old_nd.mnt->mnt_root)
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goto out2;
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goto out1;
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if (old_nd.mnt == old_nd.mnt->mnt_parent)
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goto out2;
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goto out1;
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if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
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S_ISDIR(old_nd.dentry->d_inode->i_mode))
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goto out2;
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goto out1;
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/*
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* Don't move a mount residing in a shared parent.
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*/
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if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent))
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goto out1;
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err = -ELOOP;
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for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent)
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if (p == old_nd.mnt)
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goto out2;
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err = 0;
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goto out1;
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detach_mnt(old_nd.mnt, &parent_nd);
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attach_mnt(old_nd.mnt, nd);
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touch_namespace(current->namespace);
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if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd)))
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goto out1;
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spin_lock(&vfsmount_lock);
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/* if the mount is moved, it should no longer be expire
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* automatically */
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list_del_init(&old_nd.mnt->mnt_expire);
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out2:
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spin_unlock(&vfsmount_lock);
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out1:
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up(&nd->dentry->d_inode->i_sem);
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@ -1467,6 +1492,10 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
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down_write(&namespace_sem);
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down(&old_nd.dentry->d_inode->i_sem);
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error = -EINVAL;
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if (IS_MNT_SHARED(old_nd.mnt) ||
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IS_MNT_SHARED(new_nd.mnt->mnt_parent) ||
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IS_MNT_SHARED(user_nd.mnt->mnt_parent))
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goto out2;
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if (!check_mnt(user_nd.mnt))
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goto out2;
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error = -ENOENT;
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