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mnt: Delay removal from the mount hash.

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commit 411a938b5a upstream.

- 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.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric W. Biederman
2014-12-22 19:12:07 -06:00
committed by Greg Kroah-Hartman
parent 7052e71b2d
commit 7a9742a65c
2 changed files with 8 additions and 6 deletions
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 *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry)
{ {
struct mount *p, *res; struct mount *p, *res = NULL;
res = p = __lookup_mnt(mnt, dentry); p = __lookup_mnt(mnt, dentry);
if (!p) if (!p)
goto out; goto out;
if (!(p->mnt.mnt_flags & MNT_UMOUNT))
res = p;
hlist_for_each_entry_continue(p, mnt_hash) { hlist_for_each_entry_continue(p, mnt_hash) {
if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry) if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry)
break; break;
res = p; if (!(p->mnt.mnt_flags & MNT_UMOUNT))
res = p;
} }
out: out:
return res; return res;
@@ -1338,9 +1341,8 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
list_move(&p->mnt_list, &tmp_list); 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) { list_for_each_entry(p, &tmp_list, mnt_list) {
hlist_del_init_rcu(&p->mnt_hash);
list_del_init(&p->mnt_child); list_del_init(&p->mnt_child);
} }
@@ -1367,6 +1369,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
p->mnt_mountpoint = p->mnt.mnt_root; p->mnt_mountpoint = p->mnt.mnt_root;
p->mnt_parent = p; p->mnt_parent = p;
p->mnt_mp = NULL; p->mnt_mp = NULL;
hlist_del_init_rcu(&p->mnt_hash);
} }
change_mnt_propagation(p, MS_PRIVATE); 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)) { if (child && list_empty(&child->mnt_mounts)) {
list_del_init(&child->mnt_child); list_del_init(&child->mnt_child);
hlist_del_init_rcu(&child->mnt_hash);
child->mnt.mnt_flags |= MNT_UMOUNT; child->mnt.mnt_flags |= MNT_UMOUNT;
list_move_tail(&child->mnt_list, &mnt->mnt_list); list_move_tail(&child->mnt_list, &mnt->mnt_list);
} }