On Tue, 2005-09-20 at 00:17, Al Viro wrote:
> On Fri, Sep 16, 2005 at 11:26:19AM -0700, Ram wrote:
>
> This patch needs to be split *AND* accompanied by locking rules. It's
> pretty much the core of the entire thing; if it's possible to offload
> chunks elsewhere, life would become easier. Locking rules are badly
> needed, along with the comments re "why can't that mntput()/dput()
> block under a spinlock", etc.
Yes will do.
Also I realized that vfspnode_lock just added more complexity because
all it protected was already protected by vfsmount_lock. So I am
cleaning up that lock.
>
> BTW, how are you dealing with MS_MOVE?
In the patch #6 MS_MOVE and pivot_root are handled.
>
> > +void do_detach_prepare_mnt(struct vfsmount *mnt)
> > +{
> > + mnt->mnt_mountpoint->d_mounted--;
> > + mntput(mnt->mnt_parent);
> > + dput(mnt->mnt_mountpoint);
> > + mnt->mnt_parent = mnt;
> > +}
>
> General note: mntput() should go _after_ dput() when we deal with pairs.
> Doesn't cost anything, trivially safe.
ok
>
> > if (res) {
> > spin_lock(&vfsmount_lock);
> > + clean_propagation_reference(res);
>
> Uh-oh... What makes that safe? We do mntput() here; are we guaranteed
> that these pointers won't be the last references?
Yes it is safe and it is not releasing the last reference to the mount.
Will put in a comment there.
It is releasing a reference to source mount of the bind operation.
static void inline clean_propagation_reference(struct vfsmount *mnt)
+{
+ struct vfsmount *p;
+ for (p = mnt; p; p = next_mnt(p, mnt))
+ if (p->mnt_master)
+ mntput(p->mnt_master);
+}
+
> > + spin_lock(&vfspnode_lock);
> > + propagate_abort_mount(m);
>
> Calls do_detach_prepare() -> dput(), mntput(). At the very least such
> cases need comments...
>
ok will add a comment.
but propagate_abort_mount() is not holding vfsmount_lock,
it is holding vfspnode_lock. So there should be a problem. But as
mentioned earlier, even the need for vfspnode_lock is not needed.
> > +static void __do_make_private(struct vfsmount *mnt)
> > +{
> > + __do_make_slave(mnt);
> > + list_del_init(&mnt->mnt_slave);
> > + mnt->mnt_master = NULL;
> > + set_mnt_private(mnt);
> > +}
> > +
> > int do_make_private(struct vfsmount *mnt)
> > {
> > /*
> > * a private mount is nothing but a
> > * slave mount with no incoming
> > * propagations.
> > */
> > spin_lock(&vfspnode_lock);
> > - __do_make_slave(mnt);
> > - list_del_init(&mnt->mnt_slave);
> > + __do_make_private(mnt);
> > spin_unlock(&vfspnode_lock);
> > - mnt->mnt_master = NULL;
> > - set_mnt_private(mnt);
> > return 0;
> > }
>
> Why not do that from the very beginning, BTW?
can be done. will do.
>
> > /*
> > - * a unclonable mount is nothing but a
> > + * a unclonable mount is a
> > * private mount which is unclonnable.
> > */
> > spin_lock(&vfspnode_lock);
> > - __do_make_slave(mnt);
> > - list_del_init(&mnt->mnt_slave);
> > + __do_make_private(mnt);
> > spin_unlock(&vfspnode_lock);
> > - mnt->mnt_master = NULL;
> > set_mnt_unclonable(mnt);
> > return 0;
> > }
> -
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
| |
 |