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xprtrdma: Fix Read chunk padding

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When pad optimization is disabled, rpcrdma_convert_iovs still
does not add explicit XDR round-up padding to a Read chunk.

Commit 677eb17e94 ("xprtrdma: Fix XDR tail buffer marshalling")
incorrectly short-circuited the test for whether round-up padding
is needed that appears later in rpcrdma_convert_iovs.

However, if this is indeed a regular Read chunk (and not a
Position-Zero Read chunk), the tail iovec _always_ contains the
chunk's padding, and never anything else.

So, it's easy to just skip the tail when padding optimization is
enabled, and add the tail in a subsequent Read chunk segment, if
disabled.

Fixes: 677eb17e94 ("xprtrdma: Fix XDR tail buffer marshalling")
Cc: stable@vger.kernel.org # v4.9+
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2017-02-08 16:59:46 -05:00 committed by Anna Schumaker
parent 26ae102f2c
commit 24abdf1be1
1 changed files with 4 additions and 6 deletions
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10
net/sunrpc/xprtrdma/rpc_rdma.c
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@ -226,8 +226,10 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
if (len && n == RPCRDMA_MAX_SEGS)
goto out_overflow;
/* When encoding the read list, the tail is always sent inline */
if (type == rpcrdma_readch)
/* When encoding a Read chunk, the tail iovec contains an
* XDR pad and may be omitted.
*/
if (type == rpcrdma_readch && xprt_rdma_pad_optimize)
return n;
/* When encoding the Write list, some servers need to see an extra
@ -238,10 +240,6 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
return n;
if (xdrbuf->tail[0].iov_len) {
/* the rpcrdma protocol allows us to omit any trailing
* xdr pad bytes, saving the server an RDMA operation. */
if (xdrbuf->tail[0].iov_len < 4 && xprt_rdma_pad_optimize)
return n;
n = rpcrdma_convert_kvec(&xdrbuf->tail[0], seg, n);
if (n == RPCRDMA_MAX_SEGS)
goto out_overflow;