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reorganize do_make_slave() 

Make sure that clone_mnt() never returns a mount with MNT_SHARED in
flags, but without a valid ->mnt_group_id.  That allows to demystify
do_make_slave() quite a bit, among other things.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-11-20 19:33:09 -05:00
parent 066715d3fd
commit 5235d448c4
2 changed files with 39 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/namespace.c
View File

@ -1030,6 +1030,8 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
if (IS_MNT_SLAVE(old)) if (IS_MNT_SLAVE(old))
list_add(&mnt->mnt_slave, &old->mnt_slave); list_add(&mnt->mnt_slave, &old->mnt_slave);
mnt->mnt_master = old->mnt_master; mnt->mnt_master = old->mnt_master;
} else {
CLEAR_MNT_SHARED(mnt);
} }
if (flag & CL_MAKE_SHARED) if (flag & CL_MAKE_SHARED)
set_mnt_shared(mnt); set_mnt_shared(mnt);

62
fs/pnode.c
View File

@ -67,39 +67,15 @@ int get_dominating_id(struct mount *mnt, const struct path *root)
static int do_make_slave(struct mount *mnt) static int do_make_slave(struct mount *mnt)
{ {
struct mount *peer_mnt = mnt, *master = mnt->mnt_master; struct mount *master, *slave_mnt;
struct mount *slave_mnt;
/* if (list_empty(&mnt->mnt_share)) {
* slave 'mnt' to a peer mount that has the if (IS_MNT_SHARED(mnt)) {
* same root dentry. If none is available then
* slave it to anything that is available.
*/
while ((peer_mnt = next_peer(peer_mnt)) != mnt &&
peer_mnt->mnt.mnt_root != mnt->mnt.mnt_root) ;
if (peer_mnt == mnt) {
peer_mnt = next_peer(mnt);
if (peer_mnt == mnt)
peer_mnt = NULL;
}
if (mnt->mnt_group_id && IS_MNT_SHARED(mnt) &&
list_empty(&mnt->mnt_share))
mnt_release_group_id(mnt); mnt_release_group_id(mnt);
CLEAR_MNT_SHARED(mnt);
list_del_init(&mnt->mnt_share); }
mnt->mnt_group_id = 0; master = mnt->mnt_master;
if (!master) {
if (peer_mnt)
master = peer_mnt;
if (master) {
list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave)
slave_mnt->mnt_master = master;
list_move(&mnt->mnt_slave, &master->mnt_slave_list);
list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev);
INIT_LIST_HEAD(&mnt->mnt_slave_list);
} else {
struct list_head *p = &mnt->mnt_slave_list; struct list_head *p = &mnt->mnt_slave_list;
while (!list_empty(p)) { while (!list_empty(p)) {
slave_mnt = list_first_entry(p, slave_mnt = list_first_entry(p,
@ -107,9 +83,31 @@ static int do_make_slave(struct mount *mnt)
list_del_init(&slave_mnt->mnt_slave); list_del_init(&slave_mnt->mnt_slave);
slave_mnt->mnt_master = NULL; slave_mnt->mnt_master = NULL;
} }
return 0;
} }
mnt->mnt_master = master; } else {
struct mount *m;
/*
* slave 'mnt' to a peer mount that has the
* same root dentry. If none is available then
* slave it to anything that is available.
*/
for (m = master = next_peer(mnt); m != mnt; m = next_peer(m)) {
if (m->mnt.mnt_root == mnt->mnt.mnt_root) {
master = m;
break;
}
}
list_del_init(&mnt->mnt_share);
mnt->mnt_group_id = 0;
CLEAR_MNT_SHARED(mnt); CLEAR_MNT_SHARED(mnt);
}
list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave)
slave_mnt->mnt_master = master;
list_move(&mnt->mnt_slave, &master->mnt_slave_list);
list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev);
INIT_LIST_HEAD(&mnt->mnt_slave_list);
mnt->mnt_master = master;
return 0; return 0;
} }