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

De-duplicate some code that is used by both READDIR and READDIRPLUS
to build the dirlist in the Reply. Because this code is not related
to decoding READ arguments, it is moved to a more appropriate spot.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 19 insertions, 10 deletions

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 7ea2fb127f6f..8675851199f8 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -435,6 +435,23 @@ nfsd3_proc_link(struct svc_rqst *rqstp)
 	return rpc_success;
 }
 
+static void nfsd3_init_dirlist_pages(struct svc_rqst *rqstp,
+				     struct nfsd3_readdirres *resp,
+				     int count)
+{
+	count = min_t(u32, count, svc_max_payload(rqstp));
+
+	/* 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);
+	while (count > 0) {
+		rqstp->rq_next_page++;
+		count -= PAGE_SIZE;
+	}
+}
+
 /*
  * Read a portion of a directory.
  */
@@ -452,16 +469,12 @@ nfsd3_proc_readdir(struct svc_rqst *rqstp)
 				SVCFH_fmt(&argp->fh),
 				argp->count, (u32) argp->cookie);
 
-	/* Make sure we've room for the NULL ptr & eof flag, and shrink to
-	 * client read size */
-	count = (argp->count >> 2) - 2;
+	nfsd3_init_dirlist_pages(rqstp, resp, argp->count);
 
 	/* Read directory and encode entries on the fly */
 	fh_copy(&resp->fh, &argp->fh);
 
-	resp->buflen = count;
 	resp->common.err = nfs_ok;
-	resp->buffer = argp->buffer;
 	resp->rqstp = rqstp;
 	offset = argp->cookie;
 
@@ -513,16 +526,12 @@ nfsd3_proc_readdirplus(struct svc_rqst *rqstp)
 				SVCFH_fmt(&argp->fh),
 				argp->count, (u32) argp->cookie);
 
-	/* Convert byte count to number of words (i.e. >> 2),
-	 * and reserve room for the NULL ptr & eof flag (-2 words) */
-	resp->count = (argp->count >> 2) - 2;
+	nfsd3_init_dirlist_pages(rqstp, resp, argp->count);
 
 	/* Read directory and encode entries on the fly */
 	fh_copy(&resp->fh, &argp->fh);
 
 	resp->common.err = nfs_ok;
-	resp->buffer = argp->buffer;
-	resp->buflen = resp->count;
 	resp->rqstp = rqstp;
 	offset = argp->cookie;