[PATCH] count ghost references to vfsmounts

make propagate_mount_busy() exclude references from the vfsmounts
that had been isolated by umount_tree() and are just waiting for
release_mounts() to dispose of their ->mnt_parent/->mnt_mountpoint.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2008-03-21 23:59:49 -04:00
parent 1a39068954
commit 7c4b93d826
3 changed files with 6 additions and 2 deletions

View File

@ -548,6 +548,7 @@ void release_mounts(struct list_head *head)
m = mnt->mnt_parent;
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
m->mnt_ghosts--;
spin_unlock(&vfsmount_lock);
dput(dentry);
mntput(m);
@ -572,8 +573,10 @@ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
__touch_mnt_namespace(p->mnt_ns);
p->mnt_ns = NULL;
list_del_init(&p->mnt_child);
if (p->mnt_parent != p)
if (p->mnt_parent != p) {
p->mnt_parent->mnt_ghosts++;
p->mnt_mountpoint->d_mounted--;
}
change_mnt_propagation(p, MS_PRIVATE);
}
}

View File

@ -225,7 +225,7 @@ out:
*/
static inline int do_refcount_check(struct vfsmount *mnt, int count)
{
int mycount = atomic_read(&mnt->mnt_count);
int mycount = atomic_read(&mnt->mnt_count) - mnt->mnt_ghosts;
return (mycount > count);
}

View File

@ -61,6 +61,7 @@ struct vfsmount {
atomic_t mnt_count;
int mnt_expiry_mark; /* true if marked for expiry */
int mnt_pinned;
int mnt_ghosts;
};
static inline struct vfsmount *mntget(struct vfsmount *mnt)