Patch "NFSD: Add helper to set up the pages where the dirlist is encoded" 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: Add helper to set up the pages where the dirlist is encoded

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-add-helper-to-set-up-the-pages-where-the-dirlis.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 b5e3c3916966826285520325854a877eff6679cf
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date:   Fri Nov 13 17:03:49 2020 -0500

    NFSD: Add helper to set up the pages where the dirlist is encoded
    
    [ Upstream commit 788cd46ecf83ee2d561cb4e754e276dc8089b787 ]
    
    Add a helper similar to nfsd3_init_dirlist_pages().
    
    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 6352da0168e04..a628ea4d66ead 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -553,6 +553,20 @@ nfsd_proc_rmdir(struct svc_rqst *rqstp)
 	return rpc_success;
 }
 
+static void nfsd_init_dirlist_pages(struct svc_rqst *rqstp,
+				    struct nfsd_readdirres *resp,
+				    int count)
+{
+	count = min_t(u32, count, PAGE_SIZE);
+
+	/* Convert byte count to number of words (i.e. >> 2),
+	 * and reserve room for the NULL ptr & eof flag (-2 words) */
+	resp->buflen = (count >> 2) - 2;
+
+	resp->buffer = page_address(*rqstp->rq_next_page);
+	rqstp->rq_next_page++;
+}
+
 /*
  * Read a portion of a directory.
  */
@@ -561,31 +575,24 @@ nfsd_proc_readdir(struct svc_rqst *rqstp)
 {
 	struct nfsd_readdirargs *argp = rqstp->rq_argp;
 	struct nfsd_readdirres *resp = rqstp->rq_resp;
-	int		count;
 	loff_t		offset;
+	__be32		*buffer;
 
 	dprintk("nfsd: READDIR  %s %d bytes at %d\n",
 		SVCFH_fmt(&argp->fh),		
 		argp->count, argp->cookie);
 
-	/* Shrink to the client read size */
-	count = (argp->count >> 2) - 2;
-
-	/* Make sure we've room for the NULL ptr & eof flag */
-	count -= 2;
-	if (count < 0)
-		count = 0;
+	nfsd_init_dirlist_pages(rqstp, resp, argp->count);
+	buffer = resp->buffer;
 
-	resp->buffer = argp->buffer;
 	resp->offset = NULL;
-	resp->buflen = count;
 	resp->common.err = nfs_ok;
 	/* Read directory and encode entries on the fly */
 	offset = argp->cookie;
 	resp->status = nfsd_readdir(rqstp, &argp->fh, &offset,
 				    &resp->common, nfssvc_encode_entry);
 
-	resp->count = resp->buffer - argp->buffer;
+	resp->count = resp->buffer - buffer;
 	if (resp->offset)
 		*resp->offset = htonl(offset);
 
diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 02dd9888d93b2..3d72334e16733 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -388,8 +388,6 @@ nfssvc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p)
 		return 0;
 	args->cookie = ntohl(*p++);
 	args->count  = ntohl(*p++);
-	args->count  = min_t(u32, args->count, PAGE_SIZE);
-	args->buffer = page_address(*(rqstp->rq_next_page++));
 
 	return xdr_argsize_check(rqstp, p);
 }
diff --git a/fs/nfsd/xdr.h b/fs/nfsd/xdr.h
index 1338551de828e..ff68643504c3c 100644
--- a/fs/nfsd/xdr.h
+++ b/fs/nfsd/xdr.h
@@ -73,7 +73,6 @@ struct nfsd_readdirargs {
 	struct svc_fh		fh;
 	__u32			cookie;
 	__u32			count;
-	__be32 *		buffer;
 };
 
 struct nfsd_stat {