On Mon, 19 Aug 2013 13:35:03 -0700 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Fri, 26 Jul 2013 06:23:25 -0400 Jeff Layton <jlayton@xxxxxxxxxx> wrote: > > > Christopher reported a regression where he was unable to unmount a NFS > > filesystem where the root had gone stale. The problem is that > > d_revalidate handles the root of the filesystem differently from other > > dentries, but d_weak_revalidate does not. We could simply fix this by > > making d_weak_revalidate return success on IS_ROOT dentries, but there > > are cases where we do want to revalidate the root of the fs. > > > > A umount is really a special case. We generally aren't interested in > > anything but the dentry and vfsmount that's attached at that point. If > > the inode turns out to be stale we just don't care since the intent is > > to stop using it anyway. > > > > Try to handle this situation better by treating umount as a special > > case in the lookup code. Have it resolve the parent using normal > > means, and then do a lookup of the final dentry without revalidating > > it. In most cases, the final lookup will come out of the dcache, but > > the case where there's a trailing symlink or !LAST_NORM entry on the > > end complicates things a bit. > > > > In which kernel version did the regression occur? The patch *applies* > to 3.8 and perhaps earlier, but we don't know which kernel versions > actually need it. v3.9 introduced the regression that I'm aware of (in commit ecf3d1f1aa), but there have been problems with unmounting of stale mountpoints for longer than that. -- Jeff Layton <jlayton@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
