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>

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index ad38aed6f5c2dd82ec5308eca16878e2ad1e2fcc..eedb62c411a531f3ac1148a32136f0d1db6a6e69 100644 (file)
--- 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);

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 7f0a83451bc026f16d9d26848b87f2fc2649ae47..fd390894a5849aa5cff3e4ffb8dea8bb80cd515c 100644 (file)
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -517,6 +517,9 @@ void                   svc_wake_up(struct svc_serv *);
 void              svc_reserve(struct svc_rqst *rqstp, int space);
 struct svc_pool *  svc_pool_for_cpu(struct svc_serv *serv, int cpu);
 char *            svc_print_addr(struct svc_rqst *, char *, size_t);
+int               svc_encode_read_payload(struct svc_rqst *rqstp,
+                                          unsigned int offset,
+                                          unsigned int length);
 unsigned int      svc_fill_write_vector(struct svc_rqst *rqstp,
                                         struct page **pages,
                                         struct kvec *first, size_t total);

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index 40f65888dd3887ee0f9bc9c083cce61209acff2e..04e4a34d1c6ae721b8c0600e5da4dd168ea1004a 100644 (file)
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -137,6 +137,8 @@ struct svc_rdma_recv_ctxt {
        unsigned int            rc_page_count;
        unsigned int            rc_hdr_count;
        u32                     rc_inv_rkey;
+       unsigned int            rc_read_payload_offset;
+       unsigned int            rc_read_payload_length;
        struct page             *rc_pages[RPCSVC_MAXPAGES];
 };
 
@@ -170,7 +172,9 @@ extern int svc_rdma_recv_read_chunk(struct svcxprt_rdma *rdma,
                                    struct svc_rqst *rqstp,
                                    struct svc_rdma_recv_ctxt *head, __be32 *p);
 extern int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma,
-                                    __be32 *wr_ch, struct xdr_buf *xdr);
+                                    __be32 *wr_ch, struct xdr_buf *xdr,
+                                    unsigned int offset,
+                                    unsigned long length);
 extern int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma,
                                     __be32 *rp_ch, bool writelist,
                                     struct xdr_buf *xdr);
@@ -189,6 +193,8 @@ extern int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma,
                                  struct svc_rdma_send_ctxt *ctxt,
                                  struct xdr_buf *xdr, __be32 *wr_lst);
 extern int svc_rdma_sendto(struct svc_rqst *);
+extern int svc_rdma_read_payload(struct svc_rqst *rqstp, unsigned int offset,
+                                unsigned int length);
 
 /* svc_rdma_transport.c */
 extern int svc_rdma_create_listen(struct svc_serv *, int, struct sockaddr *);

diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index ea6f46be9cb74384c402ca20f957fb73cedb22ad..9e1e046de17614d985c652c7d2bd0ded3a64a6e1 100644 (file)
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -21,6 +21,8 @@ struct svc_xprt_ops {
        int             (*xpo_has_wspace)(struct svc_xprt *);
        int             (*xpo_recvfrom)(struct svc_rqst *);
        int             (*xpo_sendto)(struct svc_rqst *);
+       int             (*xpo_read_payload)(struct svc_rqst *, unsigned int,
+                                           unsigned int);
        void            (*xpo_release_rqst)(struct svc_rqst *);
        void            (*xpo_detach)(struct svc_xprt *);
        void            (*xpo_free)(struct svc_xprt *);

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 187dd4e73d6433766ace947cd2ecabc8f8228f26..18676d36f49097390c7ae712ac8bbf8b13edc0a9 100644 (file)
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1636,6 +1636,22 @@ u32 svc_max_payload(const struct svc_rqst *rqstp)
 }
 EXPORT_SYMBOL_GPL(svc_max_payload);
 
+/**
+ * svc_encode_read_payload - mark a range of bytes as a READ payload
+ * @rqstp: svc_rqst to operate on
+ * @offset: payload's byte offset in rqstp->rq_res
+ * @length: size of payload, in bytes
+ *
+ * Returns zero on success, or a negative errno if a permanent
+ * error occurred.
+ */
+int svc_encode_read_payload(struct svc_rqst *rqstp, unsigned int offset,
+                           unsigned int length)
+{
+       return rqstp->rq_xprt->xpt_ops->xpo_read_payload(rqstp, offset, length);
+}
+EXPORT_SYMBOL_GPL(svc_encode_read_payload);
+
 /**
  * svc_fill_write_vector - Construct data argument for VFS write call
  * @rqstp: svc_rqst to operate on

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 2934dd7117153f5c4ba87b17be0e3a42d0c8517b..758ab10690dec12210f91d0eda72f87bd9c53c6a 100644 (file)
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -279,6 +279,12 @@ out:
        return len;
 }
 
+static int svc_sock_read_payload(struct svc_rqst *rqstp, unsigned int offset,
+                                unsigned int length)
+{
+       return 0;
+}
+
 /*
  * Report socket names for nfsdfs
  */
@@ -653,6 +659,7 @@ static const struct svc_xprt_ops svc_udp_ops = {
        .xpo_create = svc_udp_create,
        .xpo_recvfrom = svc_udp_recvfrom,
        .xpo_sendto = svc_udp_sendto,
+       .xpo_read_payload = svc_sock_read_payload,
        .xpo_release_rqst = svc_release_udp_skb,
        .xpo_detach = svc_sock_detach,
        .xpo_free = svc_sock_free,
@@ -1171,6 +1178,7 @@ static const struct svc_xprt_ops svc_tcp_ops = {
        .xpo_create = svc_tcp_create,
        .xpo_recvfrom = svc_tcp_recvfrom,
        .xpo_sendto = svc_tcp_sendto,
+       .xpo_read_payload = svc_sock_read_payload,
        .xpo_release_rqst = svc_release_skb,
        .xpo_detach = svc_tcp_sock_detach,
        .xpo_free = svc_sock_free,

diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index 96bccd39846949c2f7a49643581192b948d278d0..71127d898562d12d3b3f2eb77b169f20977a7cc4 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -193,6 +193,7 @@ svc_rdma_recv_ctxt_get(struct svcxprt_rdma *rdma)
 
 out:
        ctxt->rc_page_count = 0;
+       ctxt->rc_read_payload_length = 0;
        return ctxt;
 
 out_empty:

diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c
index 003610ce00bc1212d2052533085ab25c8241f2a7..927f98995356da734edbd79b391a78e4dc7e57d2 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_rw.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c
@@ -482,18 +482,19 @@ static int svc_rdma_send_xdr_kvec(struct svc_rdma_write_info *info,
                                     vec->iov_len);
 }
 
-/* Send an xdr_buf's page list by itself. A Write chunk is
- * just the page list. a Reply chunk is the head, page list,
- * and tail. This function is shared between the two types
- * of chunk.
+/* Send an xdr_buf's page list by itself. A Write chunk is just
+ * the page list. A Reply chunk is @xdr's head, page list, and
+ * tail. This function is shared between the two types of chunk.
  */
 static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
-                                     struct xdr_buf *xdr)
+                                     struct xdr_buf *xdr,
+                                     unsigned int offset,
+                                     unsigned long length)
 {
        info->wi_xdr = xdr;
-       info->wi_next_off = 0;
+       info->wi_next_off = offset - xdr->head[0].iov_len;
        return svc_rdma_build_writes(info, svc_rdma_pagelist_to_sg,
-                                    xdr->page_len);
+                                    length);
 }
 
 /**
@@ -501,6 +502,8 @@ static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
  * @rdma: controlling RDMA transport
  * @wr_ch: Write chunk provided by client
  * @xdr: xdr_buf containing the data payload
+ * @offset: payload's byte offset in @xdr
+ * @length: size of payload, in bytes
  *
  * Returns a non-negative number of bytes the chunk consumed, or
  *     %-E2BIG if the payload was larger than the Write chunk,
@@ -510,19 +513,20 @@ static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
  *     %-EIO if rdma_rw initialization failed (DMA mapping, etc).
  */
 int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch,
-                             struct xdr_buf *xdr)
+                             struct xdr_buf *xdr,
+                             unsigned int offset, unsigned long length)
 {
        struct svc_rdma_write_info *info;
        int ret;
 
-       if (!xdr->page_len)
+       if (!length)
                return 0;
 
        info = svc_rdma_write_info_alloc(rdma, wr_ch);
        if (!info)
                return -ENOMEM;
 
-       ret = svc_rdma_send_xdr_pagelist(info, xdr);
+       ret = svc_rdma_send_xdr_pagelist(info, xdr, offset, length);
        if (ret < 0)
                goto out_err;
 
@@ -531,7 +535,7 @@ int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch,
                goto out_err;
 
        trace_svcrdma_encode_write(xdr->page_len);
-       return xdr->page_len;
+       return length;
 
 out_err:
        svc_rdma_write_info_free(info);
@@ -571,7 +575,9 @@ int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma, __be32 *rp_ch,
         * client did not provide Write chunks.
         */
        if (!writelist && xdr->page_len) {
-               ret = svc_rdma_send_xdr_pagelist(info, xdr);
+               ret = svc_rdma_send_xdr_pagelist(info, xdr,
+                                                xdr->head[0].iov_len,
+                                                xdr->page_len);
                if (ret < 0)
                        goto out_err;
                consumed += xdr->page_len;

diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index f3f108090aa45cf4073f6ee98c06853d923c10d7..a11983c2056f35a8d754977036bb87430a3e668b 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -858,7 +858,18 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
 
        if (wr_lst) {
                /* XXX: Presume the client sent only one Write chunk */
-               ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr);
+               unsigned long offset;
+               unsigned int length;
+
+               if (rctxt->rc_read_payload_length) {
+                       offset = rctxt->rc_read_payload_offset;
+                       length = rctxt->rc_read_payload_length;
+               } else {
+                       offset = xdr->head[0].iov_len;
+                       length = xdr->page_len;
+               }
+               ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr, offset,
+                                               length);
                if (ret < 0)
                        goto err2;
                svc_rdma_xdr_encode_write_list(rdma_resp, wr_lst, ret);
@@ -900,3 +911,30 @@ out:
        ret = -ENOTCONN;
        goto out;
 }
+
+/**
+ * svc_rdma_read_payload - special processing for a READ payload
+ * @rqstp: svc_rqst to operate on
+ * @offset: payload's byte offset in @xdr
+ * @length: size of payload, in bytes
+ *
+ * Returns zero on success.
+ *
+ * For the moment, just record the xdr_buf location of the READ
+ * payload. svc_rdma_sendto will use that location later when
+ * we actually send the payload.
+ */
+int svc_rdma_read_payload(struct svc_rqst *rqstp, unsigned int offset,
+                         unsigned int length)
+{
+       struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt;
+
+       /* XXX: Just one READ payload slot for now, since our
+        * transport implementation currently supports only one
+        * Write chunk.
+        */
+       rctxt->rc_read_payload_offset = offset;
+       rctxt->rc_read_payload_length = length;
+
+       return 0;
+}

diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 145a3615c319366fbcc9815f76d59f4e271dc6ff..f6aad2798063d83f50acb58eb1b806e3e5aab896 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -82,6 +82,7 @@ static const struct svc_xprt_ops svc_rdma_ops = {
        .xpo_create = svc_rdma_create,
        .xpo_recvfrom = svc_rdma_recvfrom,
        .xpo_sendto = svc_rdma_sendto,
+       .xpo_read_payload = svc_rdma_read_payload,
        .xpo_release_rqst = svc_rdma_release_rqst,
        .xpo_detach = svc_rdma_detach,
        .xpo_free = svc_rdma_free,