Patch "NFSD: Update the NFSv2 READLINK result encoder to use struct xdr_stream" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    NFSD: Update the NFSv2 READLINK result encoder to use struct xdr_stream

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfsd-update-the-nfsv2-readlink-result-encoder-to-use.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 0b802e113c456bc1dad9bad1b048b33912b6d7e3
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date:   Fri Oct 23 15:41:09 2020 -0400

    NFSD: Update the NFSv2 READLINK result encoder to use struct xdr_stream
    
    [ Upstream commit d9014b0f8fae11f22a3d356553844e06ddcdce4a ]
    
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index 2a30b27c9d9be..fa9a18897bc29 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -151,13 +151,14 @@ nfsd_proc_readlink(struct svc_rqst *rqstp)
 {
 	struct nfsd_fhandle *argp = rqstp->rq_argp;
 	struct nfsd_readlinkres *resp = rqstp->rq_resp;
-	char *buffer = page_address(*(rqstp->rq_next_page++));
 
 	dprintk("nfsd: READLINK %s\n", SVCFH_fmt(&argp->fh));
 
 	/* Read the symlink. */
 	resp->len = NFS_MAXPATHLEN;
-	resp->status = nfsd_readlink(rqstp, &argp->fh, buffer, &resp->len);
+	resp->page = *(rqstp->rq_next_page++);
+	resp->status = nfsd_readlink(rqstp, &argp->fh,
+				     page_address(resp->page), &resp->len);
 
 	fh_put(&argp->fh);
 	return rpc_success;
diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 989144b0d5be2..74d9d11949c6c 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -527,24 +527,22 @@ nfssvc_encode_diropres(struct svc_rqst *rqstp, __be32 *p)
 int
 nfssvc_encode_readlinkres(struct svc_rqst *rqstp, __be32 *p)
 {
+	struct xdr_stream *xdr = &rqstp->rq_res_stream;
 	struct nfsd_readlinkres *resp = rqstp->rq_resp;
 	struct kvec *head = rqstp->rq_res.head;
 
-	*p++ = resp->status;
-	if (resp->status != nfs_ok)
-		return xdr_ressize_check(rqstp, p);
-
-	*p++ = htonl(resp->len);
-	xdr_ressize_check(rqstp, p);
-	rqstp->rq_res.page_len = resp->len;
-	if (resp->len & 3) {
-		/* need to pad the tail */
-		rqstp->rq_res.tail[0].iov_base = p;
-		*p = 0;
-		rqstp->rq_res.tail[0].iov_len = 4 - (resp->len&3);
-	}
-	if (svc_encode_result_payload(rqstp, head->iov_len, resp->len))
+	if (!svcxdr_encode_stat(xdr, resp->status))
 		return 0;
+	switch (resp->status) {
+	case nfs_ok:
+		if (xdr_stream_encode_u32(xdr, resp->len) < 0)
+			return 0;
+		xdr_write_pages(xdr, &resp->page, 0, resp->len);
+		if (svc_encode_result_payload(rqstp, head->iov_len, resp->len) < 0)
+			return 0;
+		break;
+	}
+
 	return 1;
 }
 
diff --git a/fs/nfsd/xdr.h b/fs/nfsd/xdr.h
index 45aa6b75a5f87..b17fd72c69a6a 100644
--- a/fs/nfsd/xdr.h
+++ b/fs/nfsd/xdr.h
@@ -94,6 +94,7 @@ struct nfsd_diropres  {
 struct nfsd_readlinkres {
 	__be32			status;
 	int			len;
+	struct page		*page;
 };
 
 struct nfsd_readres {