nfsd: Handle EOPENSTALE correctly in the filecache

The nfsd_open code handles EOPENSTALE correctly, by retrying the call to
fh_verify() and __nfsd_open(). However the filecache just drops the
error on the floor, and immediately returns nfserr_stale to the caller.

This patch ensures that we propagate the EOPENSTALE code back to
nfsd_file_do_acquire, and that we handle it correctly.

Fixes: 65294c1f ("nfsd: add a new struct file caching facility to nfsd")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Message-Id: <20230911183027.11372-1-trond.myklebust@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/filecache.c

@@ -989,22 +989,21 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	unsigned char need = may_flags & NFSD_FILE_MAY_MASK;
 	struct net *net = SVC_NET(rqstp);
 	struct nfsd_file *new, *nf;
-	const struct cred *cred;
+	bool stale_retry = true;
 	bool open_retry = true;
 	struct inode *inode;
 	__be32 status;
 	int ret;
 
+retry:
 	status = fh_verify(rqstp, fhp, S_IFREG,
 				may_flags|NFSD_MAY_OWNER_OVERRIDE);
 	if (status != nfs_ok)
 		return status;
 	inode = d_inode(fhp->fh_dentry);
-	cred = get_current_cred();
 
-retry:
 	rcu_read_lock();
-	nf = nfsd_file_lookup_locked(net, cred, inode, need, want_gc);
+	nf = nfsd_file_lookup_locked(net, current_cred(), inode, need, want_gc);
 	rcu_read_unlock();
 
 	if (nf) {
@@ -1026,7 +1025,7 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 
 	rcu_read_lock();
 	spin_lock(&inode->i_lock);
-	nf = nfsd_file_lookup_locked(net, cred, inode, need, want_gc);
+	nf = nfsd_file_lookup_locked(net, current_cred(), inode, need, want_gc);
 	if (unlikely(nf)) {
 		spin_unlock(&inode->i_lock);
 		rcu_read_unlock();
@@ -1058,6 +1057,7 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 			goto construction_err;
 		}
 		open_retry = false;
+		fh_put(fhp);
 		goto retry;
 	}
 	this_cpu_inc(nfsd_file_cache_hits);
@@ -1074,7 +1074,6 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		nfsd_file_check_write_error(nf);
 		*pnf = nf;
 	}
-	put_cred(cred);
 	trace_nfsd_file_acquire(rqstp, inode, may_flags, nf, status);
 	return status;
 
@@ -1088,8 +1087,20 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 			status = nfs_ok;
 			trace_nfsd_file_opened(nf, status);
 		} else {
-			status = nfsd_open_verified(rqstp, fhp, may_flags,
-						    &nf->nf_file);
+			ret = nfsd_open_verified(rqstp, fhp, may_flags,
+						 &nf->nf_file);
+			if (ret == -EOPENSTALE && stale_retry) {
+				stale_retry = false;
+				nfsd_file_unhash(nf);
+				clear_and_wake_up_bit(NFSD_FILE_PENDING,
+						      &nf->nf_flags);
+				if (refcount_dec_and_test(&nf->nf_ref))
+					nfsd_file_free(nf);
+				nf = NULL;
+				fh_put(fhp);
+				goto retry;
+			}
+			status = nfserrno(ret);
 			trace_nfsd_file_open(nf, status);
 		}
 	} else

fs/nfsd/vfs.c

@@ -823,7 +823,7 @@ int nfsd_open_break_lease(struct inode *inode, int access)
  * and additional flags.
  * N.B. After this call fhp needs an fh_put
  */
-static __be32
+static int
 __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 			int may_flags, struct file **filp)
 {
@@ -831,14 +831,12 @@ __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 	struct inode	*inode;
 	struct file	*file;
 	int		flags = O_RDONLY|O_LARGEFILE;
-	__be32		err;
-	int		host_err = 0;
+	int		host_err = -EPERM;
 
 	path.mnt = fhp->fh_export->ex_path.mnt;
 	path.dentry = fhp->fh_dentry;
 	inode = d_inode(path.dentry);
 
-	err = nfserr_perm;
 	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
 		goto out;
 
@@ -847,7 +845,7 @@ __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 
 	host_err = nfsd_open_break_lease(inode, may_flags);
 	if (host_err) /* NOMEM or WOULDBLOCK */
-		goto out_nfserr;
+		goto out;
 
 	if (may_flags & NFSD_MAY_WRITE) {
 		if (may_flags & NFSD_MAY_READ)
@@ -859,13 +857,13 @@ __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 	file = dentry_open(&path, flags, current_cred());
 	if (IS_ERR(file)) {
 		host_err = PTR_ERR(file);
-		goto out_nfserr;
+		goto out;
 	}
 
 	host_err = ima_file_check(file, may_flags);
 	if (host_err) {
 		fput(file);
-		goto out_nfserr;
+		goto out;
 	}
 
 	if (may_flags & NFSD_MAY_64BIT_COOKIE)
@@ -874,10 +872,8 @@ __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 		file->f_mode |= FMODE_32BITHASH;
 
 	*filp = file;
-out_nfserr:
-	err = nfserrno(host_err);
 out:
-	return err;
+	return host_err;
 }
 
 __be32
@@ -885,6 +881,7 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 		int may_flags, struct file **filp)
 {
 	__be32 err;
+	int host_err;
 	bool retried = false;
 
 	validate_process_creds();
@@ -904,12 +901,13 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 retry:
 	err = fh_verify(rqstp, fhp, type, may_flags);
 	if (!err) {
-		err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
-		if (err == nfserr_stale && !retried) {
+		host_err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
+		if (host_err == -EOPENSTALE && !retried) {
 			retried = true;
 			fh_put(fhp);
 			goto retry;
 		}
+		err = nfserrno(host_err);
 	}
 	validate_process_creds();
 	return err;
@@ -922,13 +920,13 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
  * @may_flags: internal permission flags
  * @filp: OUT: open "struct file *"
  *
- * Returns an nfsstat value in network byte order.
+ * Returns zero on success, or a negative errno value.
  */
-__be32
+int
 nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, int may_flags,
 		   struct file **filp)
 {
-	__be32 err;
+	int err;
 
 	validate_process_creds();
 	err = __nfsd_open(rqstp, fhp, S_IFREG, may_flags, filp);

fs/nfsd/vfs.h

@@ -104,8 +104,8 @@ __be32		nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
 int 		nfsd_open_break_lease(struct inode *, int);
 __be32		nfsd_open(struct svc_rqst *, struct svc_fh *, umode_t,
 				int, struct file **);
-__be32		nfsd_open_verified(struct svc_rqst *, struct svc_fh *,
-				int, struct file **);
+int		nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp,
+				   int may_flags, struct file **filp);
 __be32		nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
 				struct file *file, loff_t offset,
 				unsigned long *count,