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From:   Anna Schumaker <anna@kernel.org>
To:     linux-nfs@vger.kernel.org, trond.myklebust@hammerspace.com
Cc:     anna@kernel.org
Subject: [PATCH 2/2] NFSv4.2: Fix READ_PLUS size calculations
Date:   Wed, 31 May 2023 17:04:24 -0400
Message-Id: <20230531210424.360948-2-anna@kernel.org>
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From: Anna Schumaker <Anna.Schumaker@Netapp.com>

I bump the decode_read_plus_maxsz to account for hole segments, but I
need to subtract out this increase when calling
rpc_prepare_reply_pages() so the common case of single data segment
replies can be directly placed into the xdr pages without needing to be
shifted around.

Reported-by: Chuck Lever <chuck.lever@oracle.com>
Fixes: d3b00a802c845 ("NFS: Replace the READ_PLUS decoding code")
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
 fs/nfs/nfs42xdr.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/nfs42xdr.c b/fs/nfs/nfs42xdr.c
index ef3b150970ff..75765382cc0e 100644
--- a/fs/nfs/nfs42xdr.c
+++ b/fs/nfs/nfs42xdr.c
@@ -51,10 +51,16 @@
 					(1 /* data_content4 */ + \
 					 2 /* data_info4.di_offset */ + \
 					 1 /* data_info4.di_length */)
+#define NFS42_READ_PLUS_HOLE_SEGMENT_SIZE \
+					(1 /* data_content4 */ + \
+					 2 /* data_info4.di_offset */ + \
+					 2 /* data_info4.di_length */)
+#define READ_PLUS_SEGMENT_SIZE_DIFF	(NFS42_READ_PLUS_HOLE_SEGMENT_SIZE - \
+					 NFS42_READ_PLUS_DATA_SEGMENT_SIZE)
 #define decode_read_plus_maxsz		(op_decode_hdr_maxsz + \
 					 1 /* rpr_eof */ + \
 					 1 /* rpr_contents count */ + \
-					 NFS42_READ_PLUS_DATA_SEGMENT_SIZE)
+					 NFS42_READ_PLUS_HOLE_SEGMENT_SIZE)
 #define encode_seek_maxsz		(op_encode_hdr_maxsz + \
 					 encode_stateid_maxsz + \
 					 2 /* offset */ + \
@@ -781,8 +787,8 @@ static void nfs4_xdr_enc_read_plus(struct rpc_rqst *req,
 	encode_putfh(xdr, args->fh, &hdr);
 	encode_read_plus(xdr, args, &hdr);
 
-	rpc_prepare_reply_pages(req, args->pages, args->pgbase,
-				args->count, hdr.replen);
+	rpc_prepare_reply_pages(req, args->pages, args->pgbase, args->count,
+				hdr.replen - READ_PLUS_SEGMENT_SIZE_DIFF);
 	encode_nops(&hdr);
 }
 
-- 
2.40.1