From f5dcccd647da513a89f3b6ca392b0c1eb050b9fc Mon Sep 17 00:00:00 2001
From: Chuck Lever <chuck.lever@oracle.com>
Date: Sat, 14 Nov 2020 13:45:35 -0500
Subject: NFSD: Update the NFSv2 READDIR entry encoder to use struct xdr_stream

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/nfsxdr.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 77 insertions(+), 4 deletions(-)

(limited to 'fs/nfsd/nfsxdr.c')

diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 9522e5c5f49d..1102d40ded03 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -576,12 +576,13 @@ nfssvc_encode_readdirres(struct svc_rqst *rqstp, __be32 *p)
 {
 	struct xdr_stream *xdr = &rqstp->rq_res_stream;
 	struct nfsd_readdirres *resp = rqstp->rq_resp;
+	struct xdr_buf *dirlist = &resp->dirlist;
 
 	if (!svcxdr_encode_stat(xdr, resp->status))
 		return 0;
 	switch (resp->status) {
 	case nfs_ok:
-		xdr_write_pages(xdr, &resp->page, 0, resp->count << 2);
+		xdr_write_pages(xdr, dirlist->pages, 0, dirlist->len);
 		/* no more entries */
 		if (xdr_stream_encode_item_absent(xdr) < 0)
 			return 0;
@@ -623,14 +624,86 @@ nfssvc_encode_statfsres(struct svc_rqst *rqstp, __be32 *p)
  * @resp: readdir result context
  * @offset: offset cookie to encode
  *
+ * The buffer space for the offset cookie has already been reserved
+ * by svcxdr_encode_entry_common().
  */
 void nfssvc_encode_nfscookie(struct nfsd_readdirres *resp, u32 offset)
 {
-	if (!resp->offset)
+	__be32 cookie = cpu_to_be32(offset);
+
+	if (!resp->cookie_offset)
 		return;
 
-	*resp->offset = cpu_to_be32(offset);
-	resp->offset = NULL;
+	write_bytes_to_xdr_buf(&resp->dirlist, resp->cookie_offset, &cookie,
+			       sizeof(cookie));
+	resp->cookie_offset = 0;
+}
+
+static bool
+svcxdr_encode_entry_common(struct nfsd_readdirres *resp, const char *name,
+			   int namlen, loff_t offset, u64 ino)
+{
+	struct xdr_buf *dirlist = &resp->dirlist;
+	struct xdr_stream *xdr = &resp->xdr;
+
+	if (xdr_stream_encode_item_present(xdr) < 0)
+		return false;
+	/* fileid */
+	if (xdr_stream_encode_u32(xdr, (u32)ino) < 0)
+		return false;
+	/* name */
+	if (xdr_stream_encode_opaque(xdr, name, min(namlen, NFS2_MAXNAMLEN)) < 0)
+		return false;
+	/* cookie */
+	resp->cookie_offset = dirlist->len;
+	if (xdr_stream_encode_u32(xdr, ~0U) < 0)
+		return false;
+
+	return true;
+}
+
+/**
+ * nfs2svc_encode_entry - encode one NFSv2 READDIR entry
+ * @data: directory context
+ * @name: name of the object to be encoded
+ * @namlen: length of that name, in bytes
+ * @offset: the offset of the previous entry
+ * @ino: the fileid of this entry
+ * @d_type: unused
+ *
+ * Return values:
+ *   %0: Entry was successfully encoded.
+ *   %-EINVAL: An encoding problem occured, secondary status code in resp->common.err
+ *
+ * On exit, the following fields are updated:
+ *   - resp->xdr
+ *   - resp->common.err
+ *   - resp->cookie_offset
+ */
+int nfs2svc_encode_entry(void *data, const char *name, int namlen,
+			 loff_t offset, u64 ino, unsigned int d_type)
+{
+	struct readdir_cd *ccd = data;
+	struct nfsd_readdirres *resp = container_of(ccd,
+						    struct nfsd_readdirres,
+						    common);
+	unsigned int starting_length = resp->dirlist.len;
+
+	/* The offset cookie for the previous entry */
+	nfssvc_encode_nfscookie(resp, offset);
+
+	if (!svcxdr_encode_entry_common(resp, name, namlen, offset, ino))
+		goto out_toosmall;
+
+	xdr_commit_encode(&resp->xdr);
+	resp->common.err = nfs_ok;
+	return 0;
+
+out_toosmall:
+	resp->cookie_offset = 0;
+	resp->common.err = nfserr_toosmall;
+	resp->dirlist.len = starting_length;
+	return -EINVAL;
 }
 
 int
-- 
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