On Thu, Nov 29, 2012 at 08:53:34PM +0000, Al Viro wrote: > On Thu, Nov 29, 2012 at 08:06:12PM +0000, Al Viro wrote: > > On Tue, Sep 25, 2012 at 04:29:58AM -0700, Eric W. Biederman wrote: > > > Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxx> writes: > > > > > > >> Could you try the following patch? This should report what directories > > > >> cannot be renamed because one of them is a mount point and it gives some > > > >> real insight into what is going on. > > > > > > > > ls / > > > > __d_unalias: /dev -> /dev > > > > __d_unalias: /proc -> /proc > > > > __d_unalias: /sys -> /sys > > > > > > Ok. That is what I thought was going on. For some reason nfs is > > > attempting to recreate an existing dentry. > > > > > > Does this fix the nfs problem for you? > > > > > > Eric > > > > > > diff --git a/fs/dcache.c b/fs/dcache.c > > > index 8086636..6390f0f 100644 > > > --- a/fs/dcache.c > > > +++ b/fs/dcache.c > > > @@ -2404,6 +2404,9 @@ out_unalias: > > > if (likely(!d_mountpoint(alias))) { > > > __d_move(alias, dentry); > > > ret = alias; > > > + } else if ((alias->d_parent == dentry->d_parent) && > > > + !dentry_cmp(alias, dentry->d_name.name, dentry->d_name.len)) > > > + ret = alias; > > > } > > > > The interesting question is why the hell had it decided that preexisting > > dentry was not good enough for it? Note that we have arrived to nfs_lookup() > > after we'd decided *not* to use the damn alias. The trace posted upthread > > went __lookup_hash() -> lookup_real(). It means that lookup_dcache() > > has not produced this one. And no, even if ->d_revalidate() decided it > > was no good, the logics in d_invalidate() would've said "busy" and we'd > > gone with that dentry anyway. So it means that d_lookup() has not > > found it at all. > > > > IOW, something out there is blindly unhashing mountpoint dentries; that's > > where the real root of the problem seems to be. Could you slap > > WARN_ON(d_mountpoint(dentry)) in __d_drop() and see what it catches? > > Ho-hum... nfs_prime_dcache() seems to be the likely suspect. What happens > if we get nfs_same_file() failing for some reason for a mountpoint there? > Or for a busy directory, for that matter... > > Guys, could somebody with reproducer see if we step into the else side of > if (nfs_same_file(dentry, entry)) { > nfs_refresh_inode(dentry->d_inode, entry->fattr); > goto out; > } else { > d_drop(dentry); > dput(dentry); > } > in nfs_prime_dcache() with dentry being a mountpoint? If nothing else, > I would suggest replacing that d_drop(dentry) with > if (d_invalidate(dentry) != 0) > goto out; > in there. Guys, could you test the following and see if it fixes the breakage? If so, we need to figure out what's making nfs_same_file() spew apparent false negatives... diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index ce8cb92..55436f5 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -450,7 +450,10 @@ void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry) nfs_refresh_inode(dentry->d_inode, entry->fattr); goto out; } else { - d_drop(dentry); + if (d_invalidate(dentry) != 0) { + WARN_ON(1); + goto out; + } dput(dentry); } } h/openrisc/kernel/signal.c | 6 ++---- arch/score/kernel/signal.c | 7 ++----- arch/sh/kernel/signal_64.c | 6 ++---- arch/um/kernel/exec.c | 3 ++- 5 files changed, 9 insertions(+), 15 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html