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[PATCH] shared mount handling: bind and rbind

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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
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81
fs/pnode.c
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@@ -20,9 +20,88 @@ static inline struct vfsmount *next_peer(struct vfsmount *p)
void change_mnt_propagation(struct vfsmount *mnt, int type)
{
if (type == MS_SHARED) {
mnt->mnt_flags |= MNT_SHARED;
set_mnt_shared(mnt);
} else {
list_del_init(&mnt->mnt_share);
mnt->mnt_flags &= ~MNT_PNODE_MASK;
}
}
/*
* get the next mount in the propagation tree.
* @m: the mount seen last
* @origin: the original mount from where the tree walk initiated
*/
static struct vfsmount *propagation_next(struct vfsmount *m,
struct vfsmount *origin)
{
m = next_peer(m);
if (m == origin)
return NULL;
return m;
}
/*
* mount 'source_mnt' under the destination 'dest_mnt' at
* dentry 'dest_dentry'. And propagate that mount to
* all the peer and slave mounts of 'dest_mnt'.
* Link all the new mounts into a propagation tree headed at
* source_mnt. Also link all the new mounts using ->mnt_list
* headed at source_mnt's ->mnt_list
*
* @dest_mnt: destination mount.
* @dest_dentry: destination dentry.
* @source_mnt: source mount.
* @tree_list : list of heads of trees to be attached.
*/
int propagate_mnt(struct vfsmount *dest_mnt, struct dentry *dest_dentry,
struct vfsmount *source_mnt, struct list_head *tree_list)
{
struct vfsmount *m, *child;
int ret = 0;
struct vfsmount *prev_dest_mnt = dest_mnt;
struct vfsmount *prev_src_mnt = source_mnt;
LIST_HEAD(tmp_list);
LIST_HEAD(umount_list);
for (m = propagation_next(dest_mnt, dest_mnt); m;
m = propagation_next(m, dest_mnt)) {
int type = CL_PROPAGATION;
if (IS_MNT_NEW(m))
continue;
if (IS_MNT_SHARED(m))
type |= CL_MAKE_SHARED;
if (!(child = copy_tree(source_mnt, source_mnt->mnt_root,
type))) {
ret = -ENOMEM;
list_splice(tree_list, tmp_list.prev);
goto out;
}
if (is_subdir(dest_dentry, m->mnt_root)) {
mnt_set_mountpoint(m, dest_dentry, child);
list_add_tail(&child->mnt_hash, tree_list);
} else {
/*
* This can happen if the parent mount was bind mounted
* on some subdirectory of a shared/slave mount.
*/
list_add_tail(&child->mnt_hash, &tmp_list);
}
prev_dest_mnt = m;
prev_src_mnt = child;
}
out:
spin_lock(&vfsmount_lock);
while (!list_empty(&tmp_list)) {
child = list_entry(tmp_list.next, struct vfsmount, mnt_hash);
list_del_init(&child->mnt_hash);
umount_tree(child, &umount_list);
}
spin_unlock(&vfsmount_lock);
release_mounts(&umount_list);
return ret;
}