Patch "NFSD: Update the NFSv3 READLINK3res 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 NFSv3 READLINK3res 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-nfsv3-readlink3res-encoder-to-use-st.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 d7618630e606083ed7fd3d4d545dbe56506f7f2f
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date:   Thu Oct 22 15:18:40 2020 -0400

    NFSD: Update the NFSv3 READLINK3res encoder to use struct xdr_stream
    
    [ Upstream commit 9a9c8923b3efd593d0e6a405efef9d58c6e6804b ]
    
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 60e8c25be7571..e8d772f2c7769 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -126,14 +126,15 @@ nfsd3_proc_readlink(struct svc_rqst *rqstp)
 {
 	struct nfsd_fhandle *argp = rqstp->rq_argp;
 	struct nfsd3_readlinkres *resp = rqstp->rq_resp;
-	char *buffer = page_address(*(rqstp->rq_next_page++));
 
 	dprintk("nfsd: READLINK(3) %s\n", SVCFH_fmt(&argp->fh));
 
 	/* Read the symlink. */
 	fh_copy(&resp->fh, &argp->fh);
 	resp->len = NFS3_MAXPATHLEN;
-	resp->status = nfsd_readlink(rqstp, &resp->fh, buffer, &resp->len);
+	resp->pages = rqstp->rq_next_page++;
+	resp->status = nfsd_readlink(rqstp, &resp->fh,
+				     page_address(*resp->pages), &resp->len);
 	return rpc_success;
 }
 
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 29b923a497f48..352691c3e246a 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -977,26 +977,28 @@ nfs3svc_encode_accessres(struct svc_rqst *rqstp, __be32 *p)
 int
 nfs3svc_encode_readlinkres(struct svc_rqst *rqstp, __be32 *p)
 {
+	struct xdr_stream *xdr = &rqstp->rq_res_stream;
 	struct nfsd3_readlinkres *resp = rqstp->rq_resp;
 	struct kvec *head = rqstp->rq_res.head;
 
-	*p++ = resp->status;
-	p = encode_post_op_attr(rqstp, p, &resp->fh);
-	if (resp->status == 0) {
-		*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_nfsstat3(xdr, resp->status))
+		return 0;
+	switch (resp->status) {
+	case nfs_ok:
+		if (!svcxdr_encode_post_op_attr(rqstp, xdr, &resp->fh))
 			return 0;
-		return 1;
-	} else
-		return xdr_ressize_check(rqstp, p);
+		if (xdr_stream_encode_u32(xdr, resp->len) < 0)
+			return 0;
+		xdr_write_pages(xdr, resp->pages, 0, resp->len);
+		if (svc_encode_result_payload(rqstp, head->iov_len, resp->len) < 0)
+			return 0;
+		break;
+	default:
+		if (!svcxdr_encode_post_op_attr(rqstp, xdr, &resp->fh))
+			return 0;
+	}
+
+	return 1;
 }
 
 /* READ */
diff --git a/fs/nfsd/xdr3.h b/fs/nfsd/xdr3.h
index 7db4ee17aa209..1d633c5d5fa28 100644
--- a/fs/nfsd/xdr3.h
+++ b/fs/nfsd/xdr3.h
@@ -137,6 +137,7 @@ struct nfsd3_readlinkres {
 	__be32			status;
 	struct svc_fh		fh;
 	__u32			len;
+	struct page		**pages;
 };
 
 struct nfsd3_readres {