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mnt: Delay removal from the mount hash. 

- Modify __lookup_mnt_hash_last to ignore mounts that have MNT_UMOUNTED set.
- Don't remove mounts from the mount hash table in propogate_umount
- Don't remove mounts from the mount hash table in umount_tree before
  the entire list of mounts to be umounted is selected.
- Remove mounts from the mount hash table as the last thing that
  happens in the case where a mount has a parent in umount_tree.
  Mounts without parents are not hashed (by definition).

This paves the way for delaying removal from the mount hash table even
farther and fixing the MNT_LOCKED vs MNT_DETACH issue.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2014-12-22 19:12:07 -06:00
parent 590ce4bcbf
commit 411a938b5a
2 changed files with 8 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
fs/namespace.c
View File

@ -632,14 +632,17 @@ struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
*/
struct mount *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry)
{
struct mount *p, *res;
res = p = __lookup_mnt(mnt, dentry);
struct mount *p, *res = NULL;
p = __lookup_mnt(mnt, dentry);
if (!p)
goto out;
if (!(p->mnt.mnt_flags & MNT_UMOUNT))
res = p;
hlist_for_each_entry_continue(p, mnt_hash) {
if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry)
break;
res = p;
if (!(p->mnt.mnt_flags & MNT_UMOUNT))
res = p;
}
out:
return res;
@ -1336,9 +1339,8 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
list_move(&p->mnt_list, &tmp_list);
}
/* Hide the mounts from lookup_mnt and mnt_mounts */
/* Hide the mounts from mnt_mounts */
list_for_each_entry(p, &tmp_list, mnt_list) {
hlist_del_init_rcu(&p->mnt_hash);
list_del_init(&p->mnt_child);
}
@ -1365,6 +1367,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
p->mnt_mountpoint = p->mnt.mnt_root;
p->mnt_parent = p;
p->mnt_mp = NULL;
hlist_del_init_rcu(&p->mnt_hash);
}
change_mnt_propagation(p, MS_PRIVATE);
}

1
fs/pnode.c
View File

@ -383,7 +383,6 @@ static void __propagate_umount(struct mount *mnt)
*/
if (child && list_empty(&child->mnt_mounts)) {
list_del_init(&child->mnt_child);
hlist_del_init_rcu(&child->mnt_hash);
child->mnt.mnt_flags |= MNT_UMOUNT;
list_move_tail(&child->mnt_list, &mnt->mnt_list);
}