Patch "NFSD: Count bytes instead of pages in the NFSv3 READDIR encoder" 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: Count bytes instead of pages in the NFSv3 READDIR encoder

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-count-bytes-instead-of-pages-in-the-nfsv3-readd.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 de10563cde72e8c01bf459b39f5ce9c2255d8cfa
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date:   Mon Nov 9 13:13:21 2020 -0500

    NFSD: Count bytes instead of pages in the NFSv3 READDIR encoder
    
    [ Upstream commit a1409e2de4f11034c8eb30775cc3e37039a4ef13 ]
    
    Clean up: Counting the bytes used by each returned directory entry
    seems less brittle to me than trying to measure consumed pages after
    the fact.
    
    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 acb0a2d37dcbb..7dcc7abb1f346 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -467,10 +467,7 @@ nfsd3_proc_readdir(struct svc_rqst *rqstp)
 {
 	struct nfsd3_readdirargs *argp = rqstp->rq_argp;
 	struct nfsd3_readdirres  *resp = rqstp->rq_resp;
-	int		count = 0;
 	loff_t		offset;
-	struct page	**p;
-	caddr_t		page_addr = NULL;
 
 	dprintk("nfsd: READDIR(3)  %s %d bytes at %d\n",
 				SVCFH_fmt(&argp->fh),
@@ -481,6 +478,7 @@ nfsd3_proc_readdir(struct svc_rqst *rqstp)
 	/* Read directory and encode entries on the fly */
 	fh_copy(&resp->fh, &argp->fh);
 
+	resp->count = 0;
 	resp->common.err = nfs_ok;
 	resp->rqstp = rqstp;
 	offset = argp->cookie;
@@ -488,18 +486,6 @@ nfsd3_proc_readdir(struct svc_rqst *rqstp)
 	resp->status = nfsd_readdir(rqstp, &resp->fh, &offset,
 				    &resp->common, nfs3svc_encode_entry);
 	memcpy(resp->verf, argp->verf, 8);
-	count = 0;
-	for (p = rqstp->rq_respages + 1; p < rqstp->rq_next_page; p++) {
-		page_addr = page_address(*p);
-
-		if (((caddr_t)resp->buffer >= page_addr) &&
-		    ((caddr_t)resp->buffer < page_addr + PAGE_SIZE)) {
-			count += (caddr_t)resp->buffer - page_addr;
-			break;
-		}
-		count += PAGE_SIZE;
-	}
-	resp->count = count >> 2;
 	nfs3svc_encode_cookie3(resp, offset);
 
 	return rpc_success;
@@ -514,10 +500,7 @@ nfsd3_proc_readdirplus(struct svc_rqst *rqstp)
 {
 	struct nfsd3_readdirargs *argp = rqstp->rq_argp;
 	struct nfsd3_readdirres  *resp = rqstp->rq_resp;
-	int	count = 0;
 	loff_t	offset;
-	struct page **p;
-	caddr_t	page_addr = NULL;
 
 	dprintk("nfsd: READDIR+(3) %s %d bytes at %d\n",
 				SVCFH_fmt(&argp->fh),
@@ -528,6 +511,7 @@ nfsd3_proc_readdirplus(struct svc_rqst *rqstp)
 	/* Read directory and encode entries on the fly */
 	fh_copy(&resp->fh, &argp->fh);
 
+	resp->count = 0;
 	resp->common.err = nfs_ok;
 	resp->rqstp = rqstp;
 	offset = argp->cookie;
@@ -544,17 +528,6 @@ nfsd3_proc_readdirplus(struct svc_rqst *rqstp)
 	resp->status = nfsd_readdir(rqstp, &resp->fh, &offset,
 				    &resp->common, nfs3svc_encode_entry_plus);
 	memcpy(resp->verf, argp->verf, 8);
-	for (p = rqstp->rq_respages + 1; p < rqstp->rq_next_page; p++) {
-		page_addr = page_address(*p);
-
-		if (((caddr_t)resp->buffer >= page_addr) &&
-		    ((caddr_t)resp->buffer < page_addr + PAGE_SIZE)) {
-			count += (caddr_t)resp->buffer - page_addr;
-			break;
-		}
-		count += PAGE_SIZE;
-	}
-	resp->count = count >> 2;
 	nfs3svc_encode_cookie3(resp, offset);
 
 out:
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index e334a1454edbb..523b2dca04944 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -1364,6 +1364,7 @@ encode_entry(struct readdir_cd *ccd, const char *name, int namlen,
 		return -EINVAL;
 	}
 
+	cd->count += num_entry_words;
 	cd->buflen -= num_entry_words;
 	cd->buffer = p;
 	cd->common.err = nfs_ok;