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authorChuck Lever <chuck.lever@oracle.com>2020-03-02 14:45:53 -0500
committerChuck Lever <chuck.lever@oracle.com>2020-03-16 12:04:31 -0400
commit412055398b9e67e07347a936fc4a6adddabe9cf4 (patch)
treebca44ea1ec83e6a384660eeaf45b3fa8416a76ff /fs/nfsd
parent057a2274357786c637093866c6668d5ff048436f (diff)
nfsd: Fix NFSv4 READ on RDMA when using readv
svcrdma expects that the payload falls precisely into the xdr_buf page vector. This does not seem to be the case for nfsd4_encode_readv(). This code is called only when fops->splice_read is missing or when RQ_SPLICE_OK is clear, so it's not a noticeable problem in many common cases. Add new transport method: ->xpo_read_payload so that when a READ payload does not fit exactly in rq_res's page vector, the XDR encoder can inform the RPC transport exactly where that payload is, without the payload's XDR pad. That way, when a Write chunk is present, the transport knows what byte range in the Reply message is supposed to be matched with the chunk. Note that the Linux NFS server implementation of NFS/RDMA can currently handle only one Write chunk per RPC-over-RDMA message. This simplifies the implementation of this fix. Fixes: b04209806384 ("nfsd4: allow exotic read compounds") Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=198053 Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'fs/nfsd')
-rw-r--r--fs/nfsd/nfs4xdr.c20
1 files changed, 11 insertions, 9 deletions
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index ad38aed6f5c2..eedb62c411a5 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3594,17 +3594,17 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp,
u32 zzz = 0;
int pad;
+ /*
+ * svcrdma requires every READ payload to start somewhere
+ * in xdr->pages.
+ */
+ if (xdr->iov == xdr->buf->head) {
+ xdr->iov = NULL;
+ xdr->end = xdr->p;
+ }
+
len = maxcount;
v = 0;
-
- thislen = min_t(long, len, ((void *)xdr->end - (void *)xdr->p));
- p = xdr_reserve_space(xdr, (thislen+3)&~3);
- WARN_ON_ONCE(!p);
- resp->rqstp->rq_vec[v].iov_base = p;
- resp->rqstp->rq_vec[v].iov_len = thislen;
- v++;
- len -= thislen;
-
while (len) {
thislen = min_t(long, len, PAGE_SIZE);
p = xdr_reserve_space(xdr, (thislen+3)&~3);
@@ -3623,6 +3623,8 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp,
read->rd_length = maxcount;
if (nfserr)
return nfserr;
+ if (svc_encode_read_payload(resp->rqstp, starting_len + 8, maxcount))
+ return nfserr_io;
xdr_truncate_encode(xdr, starting_len + 8 + ((maxcount+3)&~3));
tmp = htonl(eof);