2023-06-30 21:00:09

by Anna Schumaker

[permalink] [raw]
Subject: [PATCH v4 2/4] NFSv4.2: Fix READ_PLUS size calculations

From: Anna Schumaker <[email protected]>

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 <[email protected]>
Fixes: d3b00a802c845 ("NFS: Replace the READ_PLUS decoding code")
Signed-off-by: Anna Schumaker <[email protected]>
---
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);
}

--
2.41.0