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fix old umount_tree() breakage

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Expiry-related code calls umount_tree() several times with
the same list to collect vfsmounts to.  Which is fine, except
that umount_tree() implicitly assumed that the list would
be empty on each call - it moves the victims over there and
then iterates through the list kicking them out.  It's *almost*
idempotent, so everything nearly worked.  However, mnt->ghosts
handling (and thus expirability checks) had been broken - that
part was not idempotent...

The fix is trivial - use local temporary list, splice it to
the the collector list when we are through.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2011-01-15 20:08:44 -05:00
parent b650c858c2
commit 7b8a53fd81
1 changed files with 5 additions and 3 deletions
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8
fs/namespace.c
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@ -1226,15 +1226,16 @@ void release_mounts(struct list_head *head)
*/
void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
{
LIST_HEAD(tmp_list);
struct vfsmount *p;
for (p = mnt; p; p = next_mnt(p, mnt))
list_move(&p->mnt_hash, kill);
list_move(&p->mnt_hash, &tmp_list);
if (propagate)
propagate_umount(kill);
propagate_umount(&tmp_list);
list_for_each_entry(p, kill, mnt_hash) {
list_for_each_entry(p, &tmp_list, mnt_hash) {
list_del_init(&p->mnt_expire);
list_del_init(&p->mnt_list);
__touch_mnt_namespace(p->mnt_ns);
@ -1246,6 +1247,7 @@ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
}
change_mnt_propagation(p, MS_PRIVATE);
}
list_splice(&tmp_list, kill);
}
static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts);