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From:   Anna Schumaker <anna@kernel.org>
To:     linux-nfs@vger.kernel.org, chuck.lever@oracle.com
Cc:     anna@kernel.org
Subject: [PATCH 0/1] NFSD: Simplify READ_PLUS
Date:   Thu,  1 Sep 2022 14:33:40 -0400
Message-Id: <20220901183341.1543827-1-anna@kernel.org>
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From: Anna Schumaker <Anna.Schumaker@Netapp.com>

When we left off with READ_PLUS, Chuck had suggested reverting the
server to reply with a single NFS4_CONTENT_DATA segment essentially
mimicing how the READ operation behaves. Then, a future sparse read
function can be added and the server modified to support it without
needing to rip out the old READ_PLUS code at the same time.

This patch takes that first step. I was even able to re-use the
nfsd4_encode_readv() function to remove some duplicate code.

Chuck, I tried to add in sparse read support by adding this extra
change. Unfortunately it leads to a bunch of new failing xfstests. Do
you have any thoughts about what might be going on? Is the patch okay
without the splice support?

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index adbff7737c14..e21e6cfd1c6d 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -4733,6 +4733,7 @@ static __be32
 nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp,
 			    struct nfsd4_read *read)
 {
+	bool splice_ok = test_bit(RQ_SPLICE_OK, &resp->rqstp->rq_flags);
 	unsigned long maxcount;
 	struct xdr_stream *xdr = resp->xdr;
 	struct file *file = read->rd_nf->nf_file;
@@ -4747,7 +4748,10 @@ nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp,
 	maxcount = min_t(unsigned long, read->rd_length,
 			 (xdr->buf->buflen - xdr->buf->len));
 
-	nfserr = nfsd4_encode_readv(resp, read, file, maxcount);
+	if (file->f_op->splice_read && splice_ok)
+		nfserr = nfsd4_encode_splice_read(resp, read, file, maxcount);
+	else
+		nfserr = nfsd4_encode_readv(resp, read, file, maxcount)
 	if (nfserr)
 		return nfserr;
 

Thanks,
Anna


Anna Schumaker (1):
  NFSD: Simplify READ_PLUS

 fs/nfsd/nfs4xdr.c | 122 ++++++++--------------------------------------
 1 file changed, 20 insertions(+), 102 deletions(-)

-- 
2.37.2