GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-19 13:11:14 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

mnt: On an unmount propagate clearing of MNT_LOCKED

Browse source 
A prerequisite of calling umount_tree is that the point where the tree
is mounted at is valid to unmount.

If we are propagating the effect of the unmount clear MNT_LOCKED in
every instance where the same filesystem is mounted on the same
mountpoint in the mount tree, as we know (by virtue of the fact
that umount_tree was called) that it is safe to reveal what
is at that mountpoint.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2015-01-03 05:39:35 -06:00
parent 411a938b5a
commit 5d88457eb5
3 changed files with 24 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

20
fs/pnode.c
View file

@ -361,6 +361,26 @@ int propagate_mount_busy(struct mount *mnt, int refcnt)
return ret;
}
/*
* Clear MNT_LOCKED when it can be shown to be safe.
*
* mount_lock lock must be held for write
*/
void propagate_mount_unlock(struct mount *mnt)
{
struct mount *parent = mnt->mnt_parent;
struct mount *m, *child;
BUG_ON(parent == mnt);
for (m = propagation_next(parent, parent); m;
m = propagation_next(m, parent)) {
child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint);
if (child)
child->mnt.mnt_flags &= ~MNT_LOCKED;
}
}
/*
* NOTE: unmounting 'mnt' naturally propagates to all other mounts its
* parent propagates to.