On Mon, 04 Feb 2013 21:04:21 +0530 Suresh Jayaraman <sjayaraman@xxxxxxxx> wrote: > Hi all, > > I have been looking at the $SUBJECT. And there is already a bug reported > in the samba.org bugzilla > > https://bugzilla.samba.org/show_bug.cgi?id=8950 > > cifs gets "Access denied" while trying to get the root inode. Suppose if > you are trying to mount /share/dir/subdir and if the user doesn't have > access to any of point along the path ie. /share or /dir, mount will fail. > > As noted by Jeff Layton in the bug report, this seems to be a known > problem since we started using the shared superblock model. Though we > can work around this problem by providing neccessary permissions for the > entire path, users consider this as a regression. I tend to agree with > them and think that may be we should have addressed this problem before > pushing the shared superblock changes. > > From the changelog it appears that this results in better performance > when we use SMB2.1 leases. How much better performance we are seeing? > Is that worth living with this regression? > > Does this affect the CIFS users who are not using SMB2.1 in anyway? > > > Thanks > Well, more than that, it's a cache coherency thing. If you have an inode that's reachable via 2 mounts, you want the caches to be coherent between the two. Note that superblock sharing was a requirement for the fscache patches NFS, so I was never clear why that wasn't the case for CIFS... In any case, yes this is a problem regardless of CIFS version in use. What we probably ought to do is come up with a way to instantiate the intermediate dentries with "dummy" inodes at mount time. Those will need to be revalidated (and rehashed) if they ever come to life suddenly though. -- Jeff Layton <jlayton@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
