Patch "NFSD: Update the NFSv2 READ 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 READ 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-read-result-encoder-to-use-str.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 ce02c08f7cbd07dcb20f05f5940584f818f63cd3
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date:   Fri Oct 23 16:40:11 2020 -0400

    NFSD: Update the NFSv2 READ result encoder to use struct xdr_stream
    
    [ Upstream commit a6f8d9dc9e44b51303d9abde4643460137d19b28 ]
    
    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 fa9a18897bc29..1fd91e00b97ba 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -185,6 +185,7 @@ nfsd_proc_read(struct svc_rqst *rqstp)
 
 	v = 0;
 	len = argp->count;
+	resp->pages = rqstp->rq_next_page;
 	while (len > 0) {
 		struct page *page = *(rqstp->rq_next_page++);
 
diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 74d9d11949c6c..d6d7d07dbb1b2 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -549,27 +549,25 @@ nfssvc_encode_readlinkres(struct svc_rqst *rqstp, __be32 *p)
 int
 nfssvc_encode_readres(struct svc_rqst *rqstp, __be32 *p)
 {
+	struct xdr_stream *xdr = &rqstp->rq_res_stream;
 	struct nfsd_readres *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 = encode_fattr(rqstp, p, &resp->fh, &resp->stat);
-	*p++ = htonl(resp->count);
-	xdr_ressize_check(rqstp, p);
-
-	/* now update rqstp->rq_res to reflect data as well */
-	rqstp->rq_res.page_len = resp->count;
-	if (resp->count & 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->count&3);
-	}
-	if (svc_encode_result_payload(rqstp, head->iov_len, resp->count))
+	if (!svcxdr_encode_stat(xdr, resp->status))
 		return 0;
+	switch (resp->status) {
+	case nfs_ok:
+		if (!svcxdr_encode_fattr(rqstp, xdr, &resp->fh, &resp->stat))
+			return 0;
+		if (xdr_stream_encode_u32(xdr, resp->count) < 0)
+			return 0;
+		xdr_write_pages(xdr, resp->pages, rqstp->rq_res.page_base,
+				resp->count);
+		if (svc_encode_result_payload(rqstp, head->iov_len, resp->count) < 0)
+			return 0;
+		break;
+	}
+
 	return 1;
 }
 
diff --git a/fs/nfsd/xdr.h b/fs/nfsd/xdr.h
index b17fd72c69a6a..337c581e15b4c 100644
--- a/fs/nfsd/xdr.h
+++ b/fs/nfsd/xdr.h
@@ -102,6 +102,7 @@ struct nfsd_readres {
 	struct svc_fh		fh;
 	unsigned long		count;
 	struct kstat		stat;
+	struct page		**pages;
 };
 
 struct nfsd_readdirres {