Re: [PATCH RFC 14/24] nfsd: wire up GET_DIR_DELEGATION handling

Chuck Lever
2024-03-17T15:43:15Z

On Fri, Mar 15, 2024 at 12:53:05PM -0400, Jeff Layton wrote:
> Add a new routine for acquiring a read delegation on a directory. Since
> the same CB_RECALL/DELEGRETURN infrastrure is used for regular and
> directory delegations, we can just use a normal nfs4_delegation to
> represent it.
>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
> fs/nfsd/nfs4proc.c | 23 ++++++++++++++++--
> fs/nfsd/nfs4state.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
> fs/nfsd/state.h | 5 ++++
> 3 files changed, 94 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 7973fe17bf3c..1a2c90f4ea53 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -2179,9 +2179,28 @@ nfsd4_get_dir_delegation(struct svc_rqst *rqstp,
> union nfsd4_op_u *u)
> {
> struct nfsd4_get_dir_delegation *gdd = &u->get_dir_delegation;
> + struct nfs4_delegation *dd;
> + struct nfsd_file *nf;
> + __be32 status;
> +
> + status = nfsd_file_acquire_dir(rqstp, &cstate->current_fh, &nf);
> + if (status != nfs_ok)
> + return status;
> +
> + dd = nfsd_get_dir_deleg(cstate, gdd, nf);
> + if (IS_ERR(dd)) {
> + int err = PTR_ERR(dd);
> +
> + if (err != -EAGAIN)
> + return nfserrno(err);
> + gdd->nf_status = GDD4_UNAVAIL;
> + return nfs_ok;
> + }
>
> - /* FIXME: actually return a delegation */
> - gdd->nf_status = GDD4_UNAVAIL;
> + gdd->nf_status = GDD4_OK;
> + memcpy(&gdd->stateid, &dd->dl_stid.sc_stateid, sizeof(gdd->stateid));
> + memset(&gdd->cookieverf, '\0', sizeof(gdd->cookieverf));
> + nfs4_put_stid(&dd->dl_stid);
> return nfs_ok;
> }
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 778c1c6e3b54..36574aedc211 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -8874,7 +8874,7 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
> }
> break_lease:
> nfsd_stats_wdeleg_getattr_inc(nn);
> - dp = fl->fl_owner;
> + dp = fl->c.flc_owner;
> ncf = &dp->dl_cb_fattr;
> nfs4_cb_getattr(&dp->dl_cb_fattr);
> spin_unlock(&ctx->flc_lock);
> @@ -8912,3 +8912,70 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
> spin_unlock(&ctx->flc_lock);
> return 0;
> }
> +

I'll admit to not having examined the below function closely, but
since it is not a static function, can you add a kdoc comment and
a few salient points like, if there is something NFSD doesn't
implement (yet), or short cuts that would be good for readers to
know about?

> +struct nfs4_delegation *
> +nfsd_get_dir_deleg(struct nfsd4_compound_state *cstate,
> + struct nfsd4_get_dir_delegation *gdd,
> + struct nfsd_file *nf)
> +{
> + struct nfs4_client *clp = cstate->clp;
> + struct nfs4_delegation *dp;
> + struct file_lease *fl;
> + struct nfs4_file *fp;
> + int status = 0;
> +
> + fp = nfsd4_alloc_file();
> + if (!fp)
> + return ERR_PTR(-ENOMEM);
> +
> + nfsd4_file_init(&cstate->current_fh, fp);
> + fp->fi_deleg_file = nf;
> + fp->fi_delegees = 1;
> +
> + spin_lock(&state_lock);
> + spin_lock(&fp->fi_lock);
> + if (nfs4_delegation_exists(clp, fp))
> + status = -EAGAIN;
> + spin_unlock(&fp->fi_lock);
> + spin_unlock(&state_lock);
> +
> + if (status)
> + goto out_delegees;
> +
> + status = -ENOMEM;
> + dp = alloc_init_deleg(clp, fp, NULL, NFS4_OPEN_DELEGATE_READ);
> + if (!dp)
> + goto out_delegees;
> +
> + fl = nfs4_alloc_init_lease(dp, NFS4_OPEN_DELEGATE_READ);
> + if (!fl)
> + goto out_put_stid;
> +
> + status = kernel_setlease(nf->nf_file,
> + fl->c.flc_type, &fl, NULL);
> + if (fl)
> + locks_free_lease(fl);
> + if (status)
> + goto out_put_stid;
> +
> + spin_lock(&state_lock);
> + spin_lock(&clp->cl_lock);
> + spin_lock(&fp->fi_lock);
> + status = hash_delegation_locked(dp, fp);
> + spin_unlock(&fp->fi_lock);
> + spin_unlock(&clp->cl_lock);
> + spin_unlock(&state_lock);
> +
> + if (status)
> + goto out_unlock;
> +
> + return dp;
> +out_unlock:
> + kernel_setlease(fp->fi_deleg_file->nf_file, F_UNLCK, NULL, (void **)&dp);
> +out_put_stid:
> + nfs4_put_stid(&dp->dl_stid);
> +out_delegees:
> + put_deleg_file(fp);
> + return ERR_PTR(status);
> +}
> +
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index 01c6f3445646..20551483cc7b 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -782,4 +782,9 @@ static inline bool try_to_expire_client(struct nfs4_client *clp)
>
> extern __be32 nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp,
> struct inode *inode, bool *file_modified, u64 *size);
> +
> +struct nfsd4_get_dir_delegation;
> +struct nfs4_delegation *nfsd_get_dir_deleg(struct nfsd4_compound_state *cstate,
> + struct nfsd4_get_dir_delegation *gdd,
> + struct nfsd_file *nf);
> #endif /* NFSD4_STATE_H */
>
> --
> 2.44.0
>

--
Chuck Lever