On Sun, 2024-07-28 at 23:41 +0300, Sagi Grimberg wrote:
> In order to support write delegations with O_WRONLY opens, we need to
> allow the clients to read using the write delegation stateid (Per RFC
> 8881 section 9.1.2. Use of the Stateid and Locking).
>
> Hence, we check for NFS4_SHARE_ACCESS_WRITE set in open request, and
> in case the share access flag does not set NFS4_SHARE_ACCESS_READ as
> well, we'll open the file locally with O_RDWR in order to allow the
> client to use the write delegation stateid when issuing a read in case
> it may choose to.
>
> Plus, find_rw_file singular call-site is now removed, remove it altogether.
>
> Note: reads using special stateids that conflict with pending write
> delegations are undetected, and will be covered in a follow on patch.
>
> Signed-off-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
> ---
> fs/nfsd/nfs4proc.c | 18 +++++++++++++++++-
> fs/nfsd/nfs4state.c | 42 ++++++++++++++++++++----------------------
> fs/nfsd/xdr4.h | 2 ++
> 3 files changed, 39 insertions(+), 23 deletions(-)
>
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 7b70309ad8fb..041bcc3ab5d7 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -979,8 +979,22 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> /* check stateid */
> status = nfs4_preprocess_stateid_op(rqstp, cstate, &cstate->current_fh,
> &read->rd_stateid, RD_STATE,
> - &read->rd_nf, NULL);
> + &read->rd_nf, &read->rd_wd_stid);
>
> + /*
> + * rd_wd_stid is needed for nfsd4_encode_read to allow write
> + * delegation stateid used for read. Its refcount is decremented
> + * by nfsd4_read_release when read is done.
> + */
> + if (!status) {
> + if (read->rd_wd_stid &&
> + (read->rd_wd_stid->sc_type != SC_TYPE_DELEG ||
> + delegstateid(read->rd_wd_stid)->dl_type !=
> + NFS4_OPEN_DELEGATE_WRITE)) {
> + nfs4_put_stid(read->rd_wd_stid);
> + read->rd_wd_stid = NULL;
> + }
> + }
> read->rd_rqstp = rqstp;
> read->rd_fhp = &cstate->current_fh;
> return status;
> @@ -990,6 +1004,8 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> static void
> nfsd4_read_release(union nfsd4_op_u *u)
> {
> + if (u->read.rd_wd_stid)
> + nfs4_put_stid(u->read.rd_wd_stid);
> if (u->read.rd_nf)
> nfsd_file_put(u->read.rd_nf);
> trace_nfsd_read_done(u->read.rd_rqstp, u->read.rd_fhp,
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 0645fccbf122..538b6e1127a2 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -639,18 +639,6 @@ find_readable_file(struct nfs4_file *f)
> return ret;
> }
>
> -static struct nfsd_file *
> -find_rw_file(struct nfs4_file *f)
> -{
> - struct nfsd_file *ret;
> -
> - spin_lock(&f->fi_lock);
> - ret = nfsd_file_get(f->fi_fds[O_RDWR]);
> - spin_unlock(&f->fi_lock);
> -
> - return ret;
> -}
> -
> struct nfsd_file *
> find_any_file(struct nfs4_file *f)
> {
> @@ -5784,15 +5772,11 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
> * "An OPEN_DELEGATE_WRITE delegation allows the client to handle,
> * on its own, all opens."
> *
> - * Furthermore the client can use a write delegation for most READ
> - * operations as well, so we require a O_RDWR file here.
> - *
> - * Offer a write delegation in the case of a BOTH open, and ensure
> - * we get the O_RDWR descriptor.
> + * Offer a write delegation for WRITE or BOTH access
> */
> - if ((open->op_share_access & NFS4_SHARE_ACCESS_BOTH) == NFS4_SHARE_ACCESS_BOTH) {
> - nf = find_rw_file(fp);
> + if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE) {
> dl_type = NFS4_OPEN_DELEGATE_WRITE;
> + nf = find_writeable_file(fp);
> }
>
> /*
> @@ -5934,8 +5918,8 @@ static void nfsd4_open_deleg_none_ext(struct nfsd4_open *open, int status)
> * open or lock state.
> */
> static void
> -nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
> - struct svc_fh *currentfh)
> +nfs4_open_delegation(struct svc_rqst *rqstp, struct nfsd4_open *open,
> + struct nfs4_ol_stateid *stp, struct svc_fh *currentfh)
> {
> struct nfs4_delegation *dp;
> struct nfs4_openowner *oo = openowner(stp->st_stateowner);
> @@ -5994,6 +5978,20 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
> dp->dl_cb_fattr.ncf_cur_fsize = stat.size;
> dp->dl_cb_fattr.ncf_initial_cinfo =
> nfsd4_change_attribute(&stat, d_inode(currentfh->fh_dentry));
> + if ((open->op_share_access & NFS4_SHARE_ACCESS_BOTH) != NFS4_SHARE_ACCESS_BOTH) {
More comments on this part:
nit: You've already tested for NFS4_SHARE_ACCESS_WRITE here, and this
seems easier to read:
if (!(open->op_share_access & NFS4_SHARE_ACCESS_READ))
> + struct nfsd_file *nf = NULL;
> +
> + /* make sure the file is opened locally for O_RDWR */
> + status = nfsd_file_acquire_opened(rqstp, currentfh,
> + nfs4_access_to_access(NFS4_SHARE_ACCESS_BOTH),
> + open->op_filp, &nf);
> + if (status) {
> + nfs4_put_stid(&dp->dl_stid);
> + destroy_delegation(dp);
> + goto out_no_deleg;
> + }
> + stp->st_stid.sc_file->fi_fds[O_RDWR] = nf;
How do you know that this fd isn't already set? Also, this field is
protected by the sc_file->fi_lock and that's not held here.
> + }
> } else {
> open->op_delegate_type = NFS4_OPEN_DELEGATE_READ;
> trace_nfsd_deleg_read(&dp->dl_stid.sc_stateid);
> @@ -6123,7 +6121,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
> * Attempt to hand out a delegation. No error return, because the
> * OPEN succeeds even if we fail.
> */
> - nfs4_open_delegation(open, stp, &resp->cstate.current_fh);
> + nfs4_open_delegation(rqstp, open, stp, &resp->cstate.current_fh);
> nodeleg:
> status = nfs_ok;
> trace_nfsd_open(&stp->st_stid.sc_stateid);
> diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
> index fbdd42cde1fa..434973a6a8b1 100644
> --- a/fs/nfsd/xdr4.h
> +++ b/fs/nfsd/xdr4.h
> @@ -426,6 +426,8 @@ struct nfsd4_read {
> struct svc_rqst *rd_rqstp; /* response */
> struct svc_fh *rd_fhp; /* response */
> u32 rd_eof; /* response */
> +
> + struct nfs4_stid *rd_wd_stid; /* internal */
> };
>
> struct nfsd4_readdir {
--
Jeff Layton <jlayton@xxxxxxxxxx>
