[PATCH v7 13/14] NFSD: Clean up direct write fall back error flow

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

Clean up: Use the usual error flow form:

	if (uncommon condition) {
		handle it;
		return;
	}
	do common thing;

in nfsd_direct_write(). Now there is a single place where the direct
write path falls back to a single cached write.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/vfs.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index b7f217aa4994..b0e4105e0075 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1373,10 +1373,6 @@ nfsd_issue_write_dio(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	ssize_t host_err;
 	size_t i;
 
-	if (!nfsd_setup_write_dio_iters(args, rqstp->rq_bvec, nvecs, *cnt))
-		return nfsd_iocb_write(file, rqstp->rq_bvec, nvecs,
-				       cnt, kiocb);
-
 	*cnt = 0;
 	segment = args->segment;
 	for (i = 0; i < ARRAY_SIZE(args->segment); i++) {
@@ -1388,7 +1384,6 @@ nfsd_issue_write_dio(struct svc_rqst *rqstp, struct svc_fh *fhp,
 						segment->len);
 		} else
 			kiocb->ki_flags &= ~IOCB_DIRECT;
-
 		host_err = vfs_iocb_iter_write(file, kiocb, &segment->iter);
 		if (host_err < 0)
 			return host_err;
@@ -1429,11 +1424,13 @@ nfsd_direct_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	kiocb->ki_flags |= IOCB_SYNC | IOCB_DSYNC;
 
 	args.nf = nf;
-	if (nfsd_is_write_dio_possible(&args, kiocb->ki_pos, *cnt))
-		return nfsd_issue_write_dio(rqstp, fhp, &args, kiocb,
-					    nvecs, cnt);
+	if (!nfsd_is_write_dio_possible(&args, kiocb->ki_pos, *cnt) ||
+	    !nfsd_setup_write_dio_iters(&args, rqstp->rq_bvec, nvecs, *cnt))
+		/* fall back to writing through the page cache */
+		return nfsd_iocb_write(file, rqstp->rq_bvec, nvecs,
+				       cnt, kiocb);
 
-	return nfsd_iocb_write(file, rqstp->rq_bvec, nvecs, cnt, kiocb);
+	return nfsd_issue_write_dio(rqstp, fhp, &args, kiocb, nvecs, cnt);
 }
 
 /**
-- 
2.51.0