Re: [PATCH v2 0/9] nfs: prepare for VFS locking changes.

[Anna Schumaker]

On Mon, Sep 28, 2026, at 10:21 PM, NeilBrown wrote:
> sashiko reported some problem with the previous posting.  A lot
> were false positives as it used the wrong base.  However:
> 3/9 had inverted the return code from nfs_neg_need_reval() - it returns
>     1 for "must revalidate" unlike d_revalidate which returns 0.
> 8/9 didn't handle and error from nfs_lookup() correctly - it
>     should be fatal rather than triggering a retry.
>
> Original intro below.
> Thanks,
> NeilBrown
>
> I am working on changes to directory locking.  The medium term goal is
> to lift d_alloc_parallel() locking above i_rwsem, so d_alloc_paralle()
> can be run unlocked, and consequently cannot be called when ->i_rwsem is
> held.
>
> The requires:
>  1/ the d_alloc_parallel() not be called while i_rwsem is held.  NFS does
>     this in a few places. New interfaces d_alloc_trylock() and d_duplicate()
>     are now available and can be used instead.
>
>  2/ a dentry must not be d_drop()ed while an operation is ongoing, as an
>     unlocked d_alloc_parallel() would then be able to create a new
>     dentry with the same name.  In particular d_rehash() must be phased
>     out as it won't be safe.  Various techiniques are used to avoid the
>     need for d_drop(), particularly that d_splice_alias() is now able to
>     splice a hashed alias.
>
> Further, the first two patches here fixes bugs that I found while
> developing and reviewing these changes.
>
> The patches depend on patches recently added to the vfs tree.  I would
> prefer these land in that tree too with an Acked-by or similar from NFS
> maintainers.

These look okay to me:

Acked-by: Anna Schumaker <anna.schumaker@xxxxxxxxxxxxxxx>

>
> Thanks,
> NeilBrown
>
>  [PATCH v2 1/9] nfs: fix open-blocking with d_fsdata
>  [PATCH v2 2/9] nfs: fix nfs_call_unlink()
>  [PATCH v2 3/9] nfs: remove d_drop()/d_alloc_parallel() from
>  [PATCH v2 4/9] nfs: use d_splice_alias() in nfs_link()
>  [PATCH v2 5/9] nfs: don't d_drop() before d_splice_alias()
>  [PATCH v2 6/9] nfs: don't d_drop() before d_splice_alias() in
>  [PATCH v2 7/9] nfs: Use d_alloc_trylock() in nfs_prime_dcache()
>  [PATCH v2 8/9] nfs: use d_alloc_trylock() in silly-rename
>  [PATCH v2 9/9] nfs: use d_duplicate()