NFSD: De-duplicate the svc_fill_write_vector() call sites

All three call sites do the same thing.

I'm struggling with this a bit, however. struct xdr_buf is an XDR
layer object and unmarshaling a WRITE payload is clearly a task
intended to be done by the proc and xdr functions, not by VFS. This
feels vaguely like a layering violation.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 40 insertions, 12 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 7cfd26dec5a8..43ecc5ae0c3f 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1143,11 +1143,27 @@ static int wait_for_concurrent_writes(struct file *file)
 	return err;
 }
 
+/**
+ * nfsd_vfs_write - write data to an already-open file
+ * @rqstp: RPC execution context
+ * @fhp: File handle of file to write into
+ * @nf: An open file matching @fhp
+ * @offset: Byte offset of start
+ * @payload: xdr_buf containing the write payload
+ * @cnt: IN: number of bytes to write, OUT: number of bytes actually written
+ * @stable: An NFS stable_how value
+ * @verf: NFS WRITE verifier
+ *
+ * Upon return, caller must invoke fh_put on @fhp.
+ *
+ * Return values:
+ *   An nfsstat value in network byte order.
+ */
 __be32
-nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
-				loff_t offset, struct kvec *vec, int vlen,
-				unsigned long *cnt, int stable,
-				__be32 *verf)
+nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
+	       struct nfsd_file *nf, loff_t offset,
+	       const struct xdr_buf *payload, unsigned long *cnt,
+	       int stable, __be32 *verf)
 {
 	struct nfsd_net		*nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
 	struct file		*file = nf->nf_file;
@@ -1162,6 +1178,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
 	unsigned int		pflags = current->flags;
 	rwf_t			flags = 0;
 	bool			restore_flags = false;
+	unsigned int		nvecs;
 
 	trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
 
@@ -1189,7 +1206,8 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
 	if (stable && !fhp->fh_use_wgather)
 		flags |= RWF_SYNC;
 
-	iov_iter_kvec(&iter, ITER_SOURCE, vec, vlen, *cnt);
+	nvecs = svc_fill_write_vector(rqstp, payload);
+	iov_iter_kvec(&iter, ITER_SOURCE, rqstp->rq_vec, nvecs, *cnt);
 	since = READ_ONCE(file->f_wb_err);
 	if (verf)
 		nfsd_copy_write_verifier(verf, nn);
@@ -1289,14 +1307,24 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	return err;
 }
 
-/*
- * Write data to a file.
- * The stable flag requests synchronous writes.
- * N.B. After this call fhp needs an fh_put
+/**
+ * nfsd_write - open a file and write data to it
+ * @rqstp: RPC execution context
+ * @fhp: File handle of file to write into; nfsd_write() may modify it
+ * @offset: Byte offset of start
+ * @payload: xdr_buf containing the write payload
+ * @cnt: IN: number of bytes to write, OUT: number of bytes actually written
+ * @stable: An NFS stable_how value
+ * @verf: NFS WRITE verifier
+ *
+ * Upon return, caller must invoke fh_put on @fhp.
+ *
+ * Return values:
+ *   An nfsstat value in network byte order.
  */
 __be32
 nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
-	   struct kvec *vec, int vlen, unsigned long *cnt, int stable,
+	   const struct xdr_buf *payload, unsigned long *cnt, int stable,
 	   __be32 *verf)
 {
 	struct nfsd_file *nf;
@@ -1308,8 +1336,8 @@ nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
 	if (err)
 		goto out;
 
-	err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
-			vlen, cnt, stable, verf);
+	err = nfsd_vfs_write(rqstp, fhp, nf, offset, payload, cnt,
+			     stable, verf);
 	nfsd_file_put(nf);
 out:
 	trace_nfsd_write_done(rqstp, fhp, offset, *cnt);