On Fri, 2014-02-28 at 08:29 -0500, Alexander Viro wrote: > On Fri, Feb 28, 2014 at 01:12:58PM +0100, Donald Buczek wrote: > > > Obviously, "cleared mounted on dentry" is missing. > > > > It looks like we enter put_mountpoint() but don't get to > > dentry->d_flags &= ~DCACHE_MOUNTED; > > > > mp->m_count is not zero probably. > > > > What does it mean? The mount is still locked but not in the mount hash? > > No, it means that something else is mounted on the same dentry (in another > part of mount tree, obviously). > > If you mount the same fs on two different mountpoints, e.g. > mount /dev/sda1 /mnt > mount /dev/sda1 /tmp/foo > you will have the same dentries seen in two places. Now, > mount /dev/sdb11 /mnt/a > mount /dev/sdc5 /tmp/foo/a > > and you've got two different filesystems mounted on two different places > (/mnt/a and /tmp/foo/a). These two places have different vfsmounts, > but the same dentry. struct mountpoint is associated with dentry, so > it's also the same for both. And it serves as a mountpoint for two > vfsmounts - one for fs from sdb11, another for fs from sdc5. > > Now umount /mnt/a; one of those two vfsmounts is gone now. struct mountpoint > survives, of course, and dentry is *still* a mountpoint. sdc5 is still > mounted on /tmp/foo/a, after all... Ahh, right ... I'll need to think about my use (misuse) of d_mountpoint(). Thanks Al. -- To unsubscribe from this list: send the line "unsubscribe autofs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
