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b90fa9ae8f
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>
107 lines
2.7 KiB
C
107 lines
2.7 KiB
C
/*
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* linux/fs/pnode.c
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*
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* (C) Copyright IBM Corporation 2005.
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* Released under GPL v2.
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* Author : Ram Pai (linuxram@us.ibm.com)
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*
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*/
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#include <linux/namespace.h>
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#include <linux/mount.h>
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#include <linux/fs.h>
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#include "pnode.h"
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/* return the next shared peer mount of @p */
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static inline struct vfsmount *next_peer(struct vfsmount *p)
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{
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return list_entry(p->mnt_share.next, struct vfsmount, mnt_share);
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}
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void change_mnt_propagation(struct vfsmount *mnt, int type)
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{
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if (type == MS_SHARED) {
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set_mnt_shared(mnt);
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} else {
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list_del_init(&mnt->mnt_share);
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mnt->mnt_flags &= ~MNT_PNODE_MASK;
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}
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}
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/*
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* get the next mount in the propagation tree.
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* @m: the mount seen last
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* @origin: the original mount from where the tree walk initiated
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*/
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static struct vfsmount *propagation_next(struct vfsmount *m,
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struct vfsmount *origin)
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{
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m = next_peer(m);
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if (m == origin)
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return NULL;
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return m;
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}
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/*
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* mount 'source_mnt' under the destination 'dest_mnt' at
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* dentry 'dest_dentry'. And propagate that mount to
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* all the peer and slave mounts of 'dest_mnt'.
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* Link all the new mounts into a propagation tree headed at
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* source_mnt. Also link all the new mounts using ->mnt_list
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* headed at source_mnt's ->mnt_list
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*
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* @dest_mnt: destination mount.
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* @dest_dentry: destination dentry.
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* @source_mnt: source mount.
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* @tree_list : list of heads of trees to be attached.
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*/
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int propagate_mnt(struct vfsmount *dest_mnt, struct dentry *dest_dentry,
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struct vfsmount *source_mnt, struct list_head *tree_list)
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{
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struct vfsmount *m, *child;
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int ret = 0;
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struct vfsmount *prev_dest_mnt = dest_mnt;
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struct vfsmount *prev_src_mnt = source_mnt;
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LIST_HEAD(tmp_list);
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LIST_HEAD(umount_list);
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for (m = propagation_next(dest_mnt, dest_mnt); m;
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m = propagation_next(m, dest_mnt)) {
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int type = CL_PROPAGATION;
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if (IS_MNT_NEW(m))
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continue;
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if (IS_MNT_SHARED(m))
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type |= CL_MAKE_SHARED;
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if (!(child = copy_tree(source_mnt, source_mnt->mnt_root,
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type))) {
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ret = -ENOMEM;
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list_splice(tree_list, tmp_list.prev);
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goto out;
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}
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if (is_subdir(dest_dentry, m->mnt_root)) {
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mnt_set_mountpoint(m, dest_dentry, child);
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list_add_tail(&child->mnt_hash, tree_list);
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} else {
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/*
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* This can happen if the parent mount was bind mounted
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* on some subdirectory of a shared/slave mount.
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*/
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list_add_tail(&child->mnt_hash, &tmp_list);
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}
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prev_dest_mnt = m;
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prev_src_mnt = child;
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}
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out:
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spin_lock(&vfsmount_lock);
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while (!list_empty(&tmp_list)) {
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child = list_entry(tmp_list.next, struct vfsmount, mnt_hash);
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list_del_init(&child->mnt_hash);
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umount_tree(child, &umount_list);
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}
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spin_unlock(&vfsmount_lock);
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release_mounts(&umount_list);
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return ret;
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}
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