GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-26 08:31:13 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

[PATCH] shared mount handling: bind and rbind

Browse source 
Implement handling of MS_BIND 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>
This commit is contained in:
Ram Pai 2005-11-07 17:19:50 -05:00 • committed by Linus Torvalds
parent 03e06e68ff
commit b90fa9ae8f
4 changed files with 204 additions and 22 deletions
Download patch file Download diff file Expand all files Collapse all files

126
fs/namespace.c
View file

@ -28,8 +28,6 @@
extern int __init init_rootfs(void);
#define CL_EXPIRE 0x01
#ifdef CONFIG_SYSFS
extern int __init sysfs_init(void);
#else
@ -145,13 +143,43 @@ static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd)
old_nd->dentry->d_mounted--;
}
void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
struct vfsmount *child_mnt)
{
child_mnt->mnt_parent = mntget(mnt);
child_mnt->mnt_mountpoint = dget(dentry);
dentry->d_mounted++;
}
static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd)
{
mnt->mnt_parent = mntget(nd->mnt);
mnt->mnt_mountpoint = dget(nd->dentry);
list_add(&mnt->mnt_hash, mount_hashtable + hash(nd->mnt, nd->dentry));
mnt_set_mountpoint(nd->mnt, nd->dentry, mnt);
list_add_tail(&mnt->mnt_hash, mount_hashtable +
hash(nd->mnt, nd->dentry));
list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts);
nd->dentry->d_mounted++;
}
/*
* the caller must hold vfsmount_lock
*/
static void commit_tree(struct vfsmount *mnt)
{
struct vfsmount *parent = mnt->mnt_parent;
struct vfsmount *m;
LIST_HEAD(head);
struct namespace *n = parent->mnt_namespace;
BUG_ON(parent == mnt);
list_add_tail(&head, &mnt->mnt_list);
list_for_each_entry(m, &head, mnt_list)
m->mnt_namespace = n;
list_splice(&head, n->list.prev);
list_add_tail(&mnt->mnt_hash, mount_hashtable +
hash(parent, mnt->mnt_mountpoint));
list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
touch_namespace(n);
}
static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root)
@ -183,7 +211,11 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
mnt->mnt_root = dget(root);
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
mnt->mnt_namespace = current->namespace;
if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))
list_add(&mnt->mnt_share, &old->mnt_share);
if (flag & CL_MAKE_SHARED)
set_mnt_shared(mnt);
/* stick the duplicate mount on the same expiry list
* as the original if that was on one */
@ -379,7 +411,7 @@ int may_umount(struct vfsmount *mnt)
EXPORT_SYMBOL(may_umount);
static void release_mounts(struct list_head *head)
void release_mounts(struct list_head *head)
{
struct vfsmount *mnt;
while(!list_empty(head)) {
@ -401,7 +433,7 @@ static void release_mounts(struct list_head *head)
}
}
static void umount_tree(struct vfsmount *mnt, struct list_head *kill)
void umount_tree(struct vfsmount *mnt, struct list_head *kill)
{
struct vfsmount *p;
@ -581,7 +613,7 @@ static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry)
}
}
static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
int flag)
{
struct vfsmount *res, *p, *q, *r, *s;
@ -626,6 +658,67 @@ Enomem:
return NULL;
}
/*
* @source_mnt : mount tree to be attached
* @nd : place the mount tree @source_mnt is attached
*
* NOTE: in the table below explains the semantics when a source mount
* of a given type is attached to a destination mount of a given type.
* ---------------------------------------------
* | BIND MOUNT OPERATION |
* |********************************************
* | source-->| shared | private |
* | dest | | |
* | | | | |
* | v | | |
* |********************************************
* | shared | shared (++) | shared (+) |
* | | | |
* |non-shared| shared (+) | private |
* *********************************************
* A bind operation clones the source mount and mounts the clone on the
* destination mount.
*
* (++) the cloned mount is propagated to all the mounts in the propagation
* tree of the destination mount and the cloned mount is added to
* the peer group of the source mount.
* (+) the cloned mount is created under the destination mount and is marked
* as shared. The cloned mount is added to the peer group of the source
* mount.
*
* if the source mount is a tree, the operations explained above is
* applied to each mount in the tree.
* Must be called without spinlocks held, since this function can sleep
* in allocations.
*/
static int attach_recursive_mnt(struct vfsmount *source_mnt,
struct nameidata *nd)
{
LIST_HEAD(tree_list);
struct vfsmount *dest_mnt = nd->mnt;
struct dentry *dest_dentry = nd->dentry;
struct vfsmount *child, *p;
if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list))
return -EINVAL;
if (IS_MNT_SHARED(dest_mnt)) {
for (p = source_mnt; p; p = next_mnt(p, source_mnt))
set_mnt_shared(p);
}
spin_lock(&vfsmount_lock);
mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
commit_tree(source_mnt);
list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
list_del_init(&child->mnt_hash);
commit_tree(child);
}
spin_unlock(&vfsmount_lock);
return 0;
}
static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
{
int err;
@ -646,17 +739,8 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
goto out_unlock;
err = -ENOENT;
spin_lock(&vfsmount_lock);
if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) {
struct list_head head;
attach_mnt(mnt, nd);
list_add_tail(&head, &mnt->mnt_list);
list_splice(&head, current->namespace->list.prev);
err = 0;
touch_namespace(current->namespace);
}
spin_unlock(&vfsmount_lock);
if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry))
err = attach_recursive_mnt(mnt, nd);
out_unlock:
up(&nd->dentry->d_inode->i_sem);
if (!err)