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[PATCH] handling of slave mounts

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This makes bind, rbind, move, clone namespace and umount operations
aware of the semantics of slave mount (see Documentation/sharedsubtree.txt
in the last patch of the 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 17:21:01 -05:00
committed by Linus Torvalds
parent a58b0eb8e6
commit 5afe002213
2 changed files with 121 additions and 37 deletions
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81
fs/pnode.c
View File

@@ -17,6 +17,16 @@ static inline struct vfsmount *next_peer(struct vfsmount *p)
return list_entry(p->mnt_share.next, struct vfsmount, mnt_share);
}
static inline struct vfsmount *first_slave(struct vfsmount *p)
{
return list_entry(p->mnt_slave_list.next, struct vfsmount, mnt_slave);
}
static inline struct vfsmount *next_slave(struct vfsmount *p)
{
return list_entry(p->mnt_slave.next, struct vfsmount, mnt_slave);
}
static int do_make_slave(struct vfsmount *mnt)
{
struct vfsmount *peer_mnt = mnt, *master = mnt->mnt_master;
@@ -83,10 +93,64 @@ void change_mnt_propagation(struct vfsmount *mnt, int type)
static struct vfsmount *propagation_next(struct vfsmount *m,
struct vfsmount *origin)
{
m = next_peer(m);
if (m == origin)
return NULL;
return m;
/* are there any slaves of this mount? */
if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
return first_slave(m);
while (1) {
struct vfsmount *next;
struct vfsmount *master = m->mnt_master;
if ( master == origin->mnt_master ) {
next = next_peer(m);
return ((next == origin) ? NULL : next);
} else if (m->mnt_slave.next != &master->mnt_slave_list)
return next_slave(m);
/* back at master */
m = master;
}
}
/*
* return the source mount to be used for cloning
*
* @dest the current destination mount
* @last_dest the last seen destination mount
* @last_src the last seen source mount
* @type return CL_SLAVE if the new mount has to be
* cloned as a slave.
*/
static struct vfsmount *get_source(struct vfsmount *dest,
struct vfsmount *last_dest,
struct vfsmount *last_src,
int *type)
{
struct vfsmount *p_last_src = NULL;
struct vfsmount *p_last_dest = NULL;
*type = CL_PROPAGATION;;
if (IS_MNT_SHARED(dest))
*type |= CL_MAKE_SHARED;
while (last_dest != dest->mnt_master) {
p_last_dest = last_dest;
p_last_src = last_src;
last_dest = last_dest->mnt_master;
last_src = last_src->mnt_master;
}
if (p_last_dest) {
do {
p_last_dest = next_peer(p_last_dest);
} while (IS_MNT_NEW(p_last_dest));
}
if (dest != p_last_dest) {
*type |= CL_SLAVE;
return last_src;
} else
return p_last_src;
}
/*
@@ -114,16 +178,15 @@ int propagate_mnt(struct vfsmount *dest_mnt, struct dentry *dest_dentry,
for (m = propagation_next(dest_mnt, dest_mnt); m;
m = propagation_next(m, dest_mnt)) {
int type = CL_PROPAGATION;
int type;
struct vfsmount *source;
if (IS_MNT_NEW(m))
continue;
if (IS_MNT_SHARED(m))
type |= CL_MAKE_SHARED;
source = get_source(m, prev_dest_mnt, prev_src_mnt, &type);
if (!(child = copy_tree(source_mnt, source_mnt->mnt_root,
type))) {
if (!(child = copy_tree(source, source->mnt_root, type))) {
ret = -ENOMEM;
list_splice(tree_list, tmp_list.prev);
goto out;