fedora core 6 1.2949 + vserver 2.2.0
[linux-2.6.git] / net / sunrpc / xdr.c
index 4484931..a0af250 100644 (file)
@@ -6,23 +6,20 @@
  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
  */
 
+#include <linux/module.h>
 #include <linux/types.h>
-#include <linux/socket.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
 #include <linux/pagemap.h>
 #include <linux/errno.h>
-#include <linux/in.h>
-#include <linux/net.h>
-#include <net/sock.h>
 #include <linux/sunrpc/xdr.h>
 #include <linux/sunrpc/msg_prot.h>
 
 /*
  * XDR functions for basic NFS types
  */
-u32 *
-xdr_encode_netobj(u32 *p, const struct xdr_netobj *obj)
+__be32 *
+xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
 {
        unsigned int    quadlen = XDR_QUADLEN(obj->len);
 
@@ -32,8 +29,8 @@ xdr_encode_netobj(u32 *p, const struct xdr_netobj *obj)
        return p + XDR_QUADLEN(obj->len);
 }
 
-u32 *
-xdr_decode_netobj(u32 *p, struct xdr_netobj *obj)
+__be32 *
+xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
 {
        unsigned int    len;
 
@@ -46,9 +43,9 @@ xdr_decode_netobj(u32 *p, struct xdr_netobj *obj)
 
 /**
  * xdr_encode_opaque_fixed - Encode fixed length opaque data
- * @p - pointer to current position in XDR buffer.
- * @ptr - pointer to data to encode (or NULL)
- * @nbytes - size of data.
+ * @p: pointer to current position in XDR buffer.
+ * @ptr: pointer to data to encode (or NULL)
+ * @nbytes: size of data.
  *
  * Copy the array of data of length nbytes at ptr to the XDR buffer
  * at position p, then align to the next 32-bit boundary by padding
@@ -58,7 +55,7 @@ xdr_decode_netobj(u32 *p, struct xdr_netobj *obj)
  * Returns the updated current XDR buffer position
  *
  */
-u32 *xdr_encode_opaque_fixed(u32 *p, const void *ptr, unsigned int nbytes)
+__be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
 {
        if (likely(nbytes != 0)) {
                unsigned int quadlen = XDR_QUADLEN(nbytes);
@@ -76,48 +73,27 @@ EXPORT_SYMBOL(xdr_encode_opaque_fixed);
 
 /**
  * xdr_encode_opaque - Encode variable length opaque data
- * @p - pointer to current position in XDR buffer.
- * @ptr - pointer to data to encode (or NULL)
- * @nbytes - size of data.
+ * @p: pointer to current position in XDR buffer.
+ * @ptr: pointer to data to encode (or NULL)
+ * @nbytes: size of data.
  *
  * Returns the updated current XDR buffer position
  */
-u32 *xdr_encode_opaque(u32 *p, const void *ptr, unsigned int nbytes)
+__be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
 {
        *p++ = htonl(nbytes);
        return xdr_encode_opaque_fixed(p, ptr, nbytes);
 }
 EXPORT_SYMBOL(xdr_encode_opaque);
 
-u32 *
-xdr_encode_string(u32 *p, const char *string)
+__be32 *
+xdr_encode_string(__be32 *p, const char *string)
 {
        return xdr_encode_array(p, string, strlen(string));
 }
 
-u32 *
-xdr_decode_string(u32 *p, char **sp, int *lenp, int maxlen)
-{
-       unsigned int    len;
-       char            *string;
-
-       if ((len = ntohl(*p++)) > maxlen)
-               return NULL;
-       if (lenp)
-               *lenp = len;
-       if ((len % 4) != 0) {
-               string = (char *) p;
-       } else {
-               string = (char *) (p - 1);
-               memmove(string, p, len);
-       }
-       string[len] = '\0';
-       *sp = string;
-       return p + XDR_QUADLEN(len);
-}
-
-u32 *
-xdr_decode_string_inplace(u32 *p, char **sp, int *lenp, int maxlen)
+__be32 *
+xdr_decode_string_inplace(__be32 *p, char **sp, int *lenp, int maxlen)
 {
        unsigned int    len;
 
@@ -176,162 +152,6 @@ xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
        xdr->buflen += len;
 }
 
-void
-xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base,
-                         skb_reader_t *desc,
-                         skb_read_actor_t copy_actor)
-{
-       struct page     **ppage = xdr->pages;
-       unsigned int    len, pglen = xdr->page_len;
-       int             ret;
-
-       len = xdr->head[0].iov_len;
-       if (base < len) {
-               len -= base;
-               ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
-               if (ret != len || !desc->count)
-                       return;
-               base = 0;
-       } else
-               base -= len;
-
-       if (pglen == 0)
-               goto copy_tail;
-       if (base >= pglen) {
-               base -= pglen;
-               goto copy_tail;
-       }
-       if (base || xdr->page_base) {
-               pglen -= base;
-               base  += xdr->page_base;
-               ppage += base >> PAGE_CACHE_SHIFT;
-               base &= ~PAGE_CACHE_MASK;
-       }
-       do {
-               char *kaddr;
-
-               len = PAGE_CACHE_SIZE;
-               kaddr = kmap_atomic(*ppage, KM_SKB_SUNRPC_DATA);
-               if (base) {
-                       len -= base;
-                       if (pglen < len)
-                               len = pglen;
-                       ret = copy_actor(desc, kaddr + base, len);
-                       base = 0;
-               } else {
-                       if (pglen < len)
-                               len = pglen;
-                       ret = copy_actor(desc, kaddr, len);
-               }
-               flush_dcache_page(*ppage);
-               kunmap_atomic(kaddr, KM_SKB_SUNRPC_DATA);
-               if (ret != len || !desc->count)
-                       return;
-               ppage++;
-       } while ((pglen -= len) != 0);
-copy_tail:
-       len = xdr->tail[0].iov_len;
-       if (base < len)
-               copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
-}
-
-
-int
-xdr_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen,
-               struct xdr_buf *xdr, unsigned int base, int msgflags)
-{
-       struct page **ppage = xdr->pages;
-       unsigned int len, pglen = xdr->page_len;
-       int err, ret = 0;
-       ssize_t (*sendpage)(struct socket *, struct page *, int, size_t, int);
-
-       len = xdr->head[0].iov_len;
-       if (base < len || (addr != NULL && base == 0)) {
-               struct kvec iov = {
-                       .iov_base = xdr->head[0].iov_base + base,
-                       .iov_len  = len - base,
-               };
-               struct msghdr msg = {
-                       .msg_name    = addr,
-                       .msg_namelen = addrlen,
-                       .msg_flags   = msgflags,
-               };
-               if (xdr->len > len)
-                       msg.msg_flags |= MSG_MORE;
-
-               if (iov.iov_len != 0)
-                       err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
-               else
-                       err = kernel_sendmsg(sock, &msg, NULL, 0, 0);
-               if (ret == 0)
-                       ret = err;
-               else if (err > 0)
-                       ret += err;
-               if (err != iov.iov_len)
-                       goto out;
-               base = 0;
-       } else
-               base -= len;
-
-       if (pglen == 0)
-               goto copy_tail;
-       if (base >= pglen) {
-               base -= pglen;
-               goto copy_tail;
-       }
-       if (base || xdr->page_base) {
-               pglen -= base;
-               base  += xdr->page_base;
-               ppage += base >> PAGE_CACHE_SHIFT;
-               base &= ~PAGE_CACHE_MASK;
-       }
-
-       sendpage = sock->ops->sendpage ? : sock_no_sendpage;
-       do {
-               int flags = msgflags;
-
-               len = PAGE_CACHE_SIZE;
-               if (base)
-                       len -= base;
-               if (pglen < len)
-                       len = pglen;
-
-               if (pglen != len || xdr->tail[0].iov_len != 0)
-                       flags |= MSG_MORE;
-
-               /* Hmm... We might be dealing with highmem pages */
-               if (PageHighMem(*ppage))
-                       sendpage = sock_no_sendpage;
-               err = sendpage(sock, *ppage, base, len, flags);
-               if (ret == 0)
-                       ret = err;
-               else if (err > 0)
-                       ret += err;
-               if (err != len)
-                       goto out;
-               base = 0;
-               ppage++;
-       } while ((pglen -= len) != 0);
-copy_tail:
-       len = xdr->tail[0].iov_len;
-       if (base < len) {
-               struct kvec iov = {
-                       .iov_base = xdr->tail[0].iov_base + base,
-                       .iov_len  = len - base,
-               };
-               struct msghdr msg = {
-                       .msg_flags   = msgflags,
-               };
-               err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
-               if (ret == 0)
-                       ret = err;
-               else if (err > 0)
-                       ret += err;
-       }
-out:
-       return ret;
-}
-
 
 /*
  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
@@ -371,7 +191,6 @@ _shift_data_right_pages(struct page **pages, size_t pgto_base,
        do {
                /* Are any pointers crossing a page boundary? */
                if (pgto_base == 0) {
-                       flush_dcache_page(*pgto);
                        pgto_base = PAGE_CACHE_SIZE;
                        pgto--;
                }
@@ -391,11 +210,11 @@ _shift_data_right_pages(struct page **pages, size_t pgto_base,
                vto = kmap_atomic(*pgto, KM_USER0);
                vfrom = kmap_atomic(*pgfrom, KM_USER1);
                memmove(vto + pgto_base, vfrom + pgfrom_base, copy);
+               flush_dcache_page(*pgto);
                kunmap_atomic(vfrom, KM_USER1);
                kunmap_atomic(vto, KM_USER0);
 
        } while ((len -= copy) != 0);
-       flush_dcache_page(*pgto);
 }
 
 /*
@@ -613,15 +432,27 @@ xdr_shift_buf(struct xdr_buf *buf, size_t len)
  *      of the buffer length, and takes care of adjusting the kvec
  *      length for us.
  */
-void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, uint32_t *p)
+void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
 {
        struct kvec *iov = buf->head;
+       int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
 
+       BUG_ON(scratch_len < 0);
        xdr->buf = buf;
        xdr->iov = iov;
-       xdr->end = (uint32_t *)((char *)iov->iov_base + iov->iov_len);
-       buf->len = iov->iov_len = (char *)p - (char *)iov->iov_base;
-       xdr->p = p;
+       xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
+       xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
+       BUG_ON(iov->iov_len > scratch_len);
+
+       if (p != xdr->p && p != NULL) {
+               size_t len;
+
+               BUG_ON(p < xdr->p || p > xdr->end);
+               len = (char *)p - (char *)xdr->p;
+               xdr->p = p;
+               buf->len += len;
+               iov->iov_len += len;
+       }
 }
 EXPORT_SYMBOL(xdr_init_encode);
 
@@ -634,10 +465,10 @@ EXPORT_SYMBOL(xdr_init_encode);
  * bytes of data. If so, update the total xdr_buf length, and
  * adjust the length of the current kvec.
  */
-uint32_t * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
+__be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
 {
-       uint32_t *p = xdr->p;
-       uint32_t *q;
+       __be32 *p = xdr->p;
+       __be32 *q;
 
        /* align nbytes on the next 32-bit boundary */
        nbytes += 3;
@@ -693,7 +524,7 @@ EXPORT_SYMBOL(xdr_write_pages);
  * @buf: pointer to XDR buffer from which to decode data
  * @p: current pointer inside XDR buffer
  */
-void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, uint32_t *p)
+void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
 {
        struct kvec *iov = buf->head;
        unsigned int len = iov->iov_len;
@@ -703,7 +534,7 @@ void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, uint32_t *p)
        xdr->buf = buf;
        xdr->iov = iov;
        xdr->p = p;
-       xdr->end = (uint32_t *)((char *)iov->iov_base + len);
+       xdr->end = (__be32 *)((char *)iov->iov_base + len);
 }
 EXPORT_SYMBOL(xdr_init_decode);
 
@@ -717,10 +548,10 @@ EXPORT_SYMBOL(xdr_init_decode);
  * If so return the current pointer, then update the current
  * pointer position.
  */
-uint32_t * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
+__be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
 {
-       uint32_t *p = xdr->p;
-       uint32_t *q = p + XDR_QUADLEN(nbytes);
+       __be32 *p = xdr->p;
+       __be32 *q = p + XDR_QUADLEN(nbytes);
 
        if (unlikely(q > xdr->end || q < p))
                return NULL;
@@ -736,8 +567,7 @@ EXPORT_SYMBOL(xdr_inline_decode);
  *
  * Moves data beyond the current pointer position from the XDR head[] buffer
  * into the page list. Any data that lies beyond current position + "len"
- * bytes is moved into the XDR tail[]. The current pointer is then
- * repositioned at the beginning of the XDR tail.
+ * bytes is moved into the XDR tail[].
  */
 void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
 {
@@ -769,11 +599,36 @@ void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
         * Position current pointer at beginning of tail, and
         * set remaining message length.
         */
-       xdr->p = (uint32_t *)((char *)iov->iov_base + padding);
-       xdr->end = (uint32_t *)((char *)iov->iov_base + end);
+       xdr->p = (__be32 *)((char *)iov->iov_base + padding);
+       xdr->end = (__be32 *)((char *)iov->iov_base + end);
 }
 EXPORT_SYMBOL(xdr_read_pages);
 
+/**
+ * xdr_enter_page - decode data from the XDR page
+ * @xdr: pointer to xdr_stream struct
+ * @len: number of bytes of page data
+ *
+ * Moves data beyond the current pointer position from the XDR head[] buffer
+ * into the page list. Any data that lies beyond current position + "len"
+ * bytes is moved into the XDR tail[]. The current pointer is then
+ * repositioned at the beginning of the first XDR page.
+ */
+void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
+{
+       char * kaddr = page_address(xdr->buf->pages[0]);
+       xdr_read_pages(xdr, len);
+       /*
+        * Position current pointer at beginning of tail, and
+        * set remaining message length.
+        */
+       if (len > PAGE_CACHE_SIZE - xdr->buf->page_base)
+               len = PAGE_CACHE_SIZE - xdr->buf->page_base;
+       xdr->p = (__be32 *)(kaddr + xdr->buf->page_base);
+       xdr->end = (__be32 *)((char *)xdr->p + len);
+}
+EXPORT_SYMBOL(xdr_enter_page);
+
 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
 
 void
@@ -785,41 +640,30 @@ xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
        buf->buflen = buf->len = iov->iov_len;
 }
 
-/* Sets subiov to the intersection of iov with the buffer of length len
- * starting base bytes after iov.  Indicates empty intersection by setting
- * length of subiov to zero.  Decrements len by length of subiov, sets base
- * to zero (or decrements it by length of iov if subiov is empty). */
-static void
-iov_subsegment(struct kvec *iov, struct kvec *subiov, int *base, int *len)
-{
-       if (*base > iov->iov_len) {
-               subiov->iov_base = NULL;
-               subiov->iov_len = 0;
-               *base -= iov->iov_len;
-       } else {
-               subiov->iov_base = iov->iov_base + *base;
-               subiov->iov_len = min(*len, (int)iov->iov_len - *base);
-               *base = 0;
-       }
-       *len -= subiov->iov_len; 
-}
-
 /* Sets subbuf to the portion of buf of length len beginning base bytes
  * from the start of buf. Returns -1 if base of length are out of bounds. */
 int
 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
-                       int base, int len)
+                       unsigned int base, unsigned int len)
 {
-       int i;
-
        subbuf->buflen = subbuf->len = len;
-       iov_subsegment(buf->head, subbuf->head, &base, &len);
+       if (base < buf->head[0].iov_len) {
+               subbuf->head[0].iov_base = buf->head[0].iov_base + base;
+               subbuf->head[0].iov_len = min_t(unsigned int, len,
+                                               buf->head[0].iov_len - base);
+               len -= subbuf->head[0].iov_len;
+               base = 0;
+       } else {
+               subbuf->head[0].iov_base = NULL;
+               subbuf->head[0].iov_len = 0;
+               base -= buf->head[0].iov_len;
+       }
 
        if (base < buf->page_len) {
-               i = (base + buf->page_base) >> PAGE_CACHE_SHIFT;
-               subbuf->pages = &buf->pages[i];
-               subbuf->page_base = (base + buf->page_base) & ~PAGE_CACHE_MASK;
-               subbuf->page_len = min((int)buf->page_len - base, len);
+               subbuf->page_len = min(buf->page_len - base, len);
+               base += buf->page_base;
+               subbuf->page_base = base & ~PAGE_CACHE_MASK;
+               subbuf->pages = &buf->pages[base >> PAGE_CACHE_SHIFT];
                len -= subbuf->page_len;
                base = 0;
        } else {
@@ -827,42 +671,87 @@ xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
                subbuf->page_len = 0;
        }
 
-       iov_subsegment(buf->tail, subbuf->tail, &base, &len);
+       if (base < buf->tail[0].iov_len) {
+               subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
+               subbuf->tail[0].iov_len = min_t(unsigned int, len,
+                                               buf->tail[0].iov_len - base);
+               len -= subbuf->tail[0].iov_len;
+               base = 0;
+       } else {
+               subbuf->tail[0].iov_base = NULL;
+               subbuf->tail[0].iov_len = 0;
+               base -= buf->tail[0].iov_len;
+       }
+
        if (base || len)
                return -1;
        return 0;
 }
 
+static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
+{
+       unsigned int this_len;
+
+       this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
+       memcpy(obj, subbuf->head[0].iov_base, this_len);
+       len -= this_len;
+       obj += this_len;
+       this_len = min_t(unsigned int, len, subbuf->page_len);
+       if (this_len)
+               _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
+       len -= this_len;
+       obj += this_len;
+       this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
+       memcpy(obj, subbuf->tail[0].iov_base, this_len);
+}
+
 /* obj is assumed to point to allocated memory of size at least len: */
-int
-read_bytes_from_xdr_buf(struct xdr_buf *buf, int base, void *obj, int len)
+int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
 {
        struct xdr_buf subbuf;
-       int this_len;
        int status;
 
        status = xdr_buf_subsegment(buf, &subbuf, base, len);
-       if (status)
-               goto out;
-       this_len = min(len, (int)subbuf.head[0].iov_len);
-       memcpy(obj, subbuf.head[0].iov_base, this_len);
+       if (status != 0)
+               return status;
+       __read_bytes_from_xdr_buf(&subbuf, obj, len);
+       return 0;
+}
+
+static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
+{
+       unsigned int this_len;
+
+       this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
+       memcpy(subbuf->head[0].iov_base, obj, this_len);
        len -= this_len;
        obj += this_len;
-       this_len = min(len, (int)subbuf.page_len);
+       this_len = min_t(unsigned int, len, subbuf->page_len);
        if (this_len)
-               _copy_from_pages(obj, subbuf.pages, subbuf.page_base, this_len);
+               _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
        len -= this_len;
        obj += this_len;
-       this_len = min(len, (int)subbuf.tail[0].iov_len);
-       memcpy(obj, subbuf.tail[0].iov_base, this_len);
-out:
-       return status;
+       this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
+       memcpy(subbuf->tail[0].iov_base, obj, this_len);
 }
 
-static int
-read_u32_from_xdr_buf(struct xdr_buf *buf, int base, u32 *obj)
+/* obj is assumed to point to allocated memory of size at least len: */
+int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
+{
+       struct xdr_buf subbuf;
+       int status;
+
+       status = xdr_buf_subsegment(buf, &subbuf, base, len);
+       if (status != 0)
+               return status;
+       __write_bytes_to_xdr_buf(&subbuf, obj, len);
+       return 0;
+}
+
+int
+xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
 {
-       u32     raw;
+       __be32  raw;
        int     status;
 
        status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
@@ -872,46 +761,331 @@ read_u32_from_xdr_buf(struct xdr_buf *buf, int base, u32 *obj)
        return 0;
 }
 
+int
+xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
+{
+       __be32  raw = htonl(obj);
+
+       return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
+}
+
 /* If the netobj starting offset bytes from the start of xdr_buf is contained
  * entirely in the head or the tail, set object to point to it; otherwise
  * try to find space for it at the end of the tail, copy it there, and
  * set obj to point to it. */
+int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
+{
+       struct xdr_buf subbuf;
+
+       if (xdr_decode_word(buf, offset, &obj->len))
+               return -EFAULT;
+       if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
+               return -EFAULT;
+
+       /* Is the obj contained entirely in the head? */
+       obj->data = subbuf.head[0].iov_base;
+       if (subbuf.head[0].iov_len == obj->len)
+               return 0;
+       /* ..or is the obj contained entirely in the tail? */
+       obj->data = subbuf.tail[0].iov_base;
+       if (subbuf.tail[0].iov_len == obj->len)
+               return 0;
+
+       /* use end of tail as storage for obj:
+        * (We don't copy to the beginning because then we'd have
+        * to worry about doing a potentially overlapping copy.
+        * This assumes the object is at most half the length of the
+        * tail.) */
+       if (obj->len > buf->buflen - buf->len)
+               return -ENOMEM;
+       if (buf->tail[0].iov_len != 0)
+               obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
+       else
+               obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
+       __read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
+       return 0;
+}
+
+/* Returns 0 on success, or else a negative error code. */
+static int
+xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
+                struct xdr_array2_desc *desc, int encode)
+{
+       char *elem = NULL, *c;
+       unsigned int copied = 0, todo, avail_here;
+       struct page **ppages = NULL;
+       int err;
+
+       if (encode) {
+               if (xdr_encode_word(buf, base, desc->array_len) != 0)
+                       return -EINVAL;
+       } else {
+               if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
+                   desc->array_len > desc->array_maxlen ||
+                   (unsigned long) base + 4 + desc->array_len *
+                                   desc->elem_size > buf->len)
+                       return -EINVAL;
+       }
+       base += 4;
+
+       if (!desc->xcode)
+               return 0;
+
+       todo = desc->array_len * desc->elem_size;
+
+       /* process head */
+       if (todo && base < buf->head->iov_len) {
+               c = buf->head->iov_base + base;
+               avail_here = min_t(unsigned int, todo,
+                                  buf->head->iov_len - base);
+               todo -= avail_here;
+
+               while (avail_here >= desc->elem_size) {
+                       err = desc->xcode(desc, c);
+                       if (err)
+                               goto out;
+                       c += desc->elem_size;
+                       avail_here -= desc->elem_size;
+               }
+               if (avail_here) {
+                       if (!elem) {
+                               elem = kmalloc(desc->elem_size, GFP_KERNEL);
+                               err = -ENOMEM;
+                               if (!elem)
+                                       goto out;
+                       }
+                       if (encode) {
+                               err = desc->xcode(desc, elem);
+                               if (err)
+                                       goto out;
+                               memcpy(c, elem, avail_here);
+                       } else
+                               memcpy(elem, c, avail_here);
+                       copied = avail_here;
+               }
+               base = buf->head->iov_len;  /* align to start of pages */
+       }
+
+       /* process pages array */
+       base -= buf->head->iov_len;
+       if (todo && base < buf->page_len) {
+               unsigned int avail_page;
+
+               avail_here = min(todo, buf->page_len - base);
+               todo -= avail_here;
+
+               base += buf->page_base;
+               ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
+               base &= ~PAGE_CACHE_MASK;
+               avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
+                                       avail_here);
+               c = kmap(*ppages) + base;
+
+               while (avail_here) {
+                       avail_here -= avail_page;
+                       if (copied || avail_page < desc->elem_size) {
+                               unsigned int l = min(avail_page,
+                                       desc->elem_size - copied);
+                               if (!elem) {
+                                       elem = kmalloc(desc->elem_size,
+                                                      GFP_KERNEL);
+                                       err = -ENOMEM;
+                                       if (!elem)
+                                               goto out;
+                               }
+                               if (encode) {
+                                       if (!copied) {
+                                               err = desc->xcode(desc, elem);
+                                               if (err)
+                                                       goto out;
+                                       }
+                                       memcpy(c, elem + copied, l);
+                                       copied += l;
+                                       if (copied == desc->elem_size)
+                                               copied = 0;
+                               } else {
+                                       memcpy(elem + copied, c, l);
+                                       copied += l;
+                                       if (copied == desc->elem_size) {
+                                               err = desc->xcode(desc, elem);
+                                               if (err)
+                                                       goto out;
+                                               copied = 0;
+                                       }
+                               }
+                               avail_page -= l;
+                               c += l;
+                       }
+                       while (avail_page >= desc->elem_size) {
+                               err = desc->xcode(desc, c);
+                               if (err)
+                                       goto out;
+                               c += desc->elem_size;
+                               avail_page -= desc->elem_size;
+                       }
+                       if (avail_page) {
+                               unsigned int l = min(avail_page,
+                                           desc->elem_size - copied);
+                               if (!elem) {
+                                       elem = kmalloc(desc->elem_size,
+                                                      GFP_KERNEL);
+                                       err = -ENOMEM;
+                                       if (!elem)
+                                               goto out;
+                               }
+                               if (encode) {
+                                       if (!copied) {
+                                               err = desc->xcode(desc, elem);
+                                               if (err)
+                                                       goto out;
+                                       }
+                                       memcpy(c, elem + copied, l);
+                                       copied += l;
+                                       if (copied == desc->elem_size)
+                                               copied = 0;
+                               } else {
+                                       memcpy(elem + copied, c, l);
+                                       copied += l;
+                                       if (copied == desc->elem_size) {
+                                               err = desc->xcode(desc, elem);
+                                               if (err)
+                                                       goto out;
+                                               copied = 0;
+                                       }
+                               }
+                       }
+                       if (avail_here) {
+                               kunmap(*ppages);
+                               ppages++;
+                               c = kmap(*ppages);
+                       }
+
+                       avail_page = min(avail_here,
+                                (unsigned int) PAGE_CACHE_SIZE);
+               }
+               base = buf->page_len;  /* align to start of tail */
+       }
+
+       /* process tail */
+       base -= buf->page_len;
+       if (todo) {
+               c = buf->tail->iov_base + base;
+               if (copied) {
+                       unsigned int l = desc->elem_size - copied;
+
+                       if (encode)
+                               memcpy(c, elem + copied, l);
+                       else {
+                               memcpy(elem + copied, c, l);
+                               err = desc->xcode(desc, elem);
+                               if (err)
+                                       goto out;
+                       }
+                       todo -= l;
+                       c += l;
+               }
+               while (todo) {
+                       err = desc->xcode(desc, c);
+                       if (err)
+                               goto out;
+                       c += desc->elem_size;
+                       todo -= desc->elem_size;
+               }
+       }
+       err = 0;
+
+out:
+       kfree(elem);
+       if (ppages)
+               kunmap(*ppages);
+       return err;
+}
+
 int
-xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, int offset)
+xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
+                 struct xdr_array2_desc *desc)
 {
-       u32     tail_offset = buf->head[0].iov_len + buf->page_len;
-       u32     obj_end_offset;
+       if (base >= buf->len)
+               return -EINVAL;
 
-       if (read_u32_from_xdr_buf(buf, offset, &obj->len))
-               goto out;
-       obj_end_offset = offset + 4 + obj->len;
-
-       if (obj_end_offset <= buf->head[0].iov_len) {
-               /* The obj is contained entirely in the head: */
-               obj->data = buf->head[0].iov_base + offset + 4;
-       } else if (offset + 4 >= tail_offset) {
-               if (obj_end_offset - tail_offset
-                               > buf->tail[0].iov_len)
-                       goto out;
-               /* The obj is contained entirely in the tail: */
-               obj->data = buf->tail[0].iov_base
-                       + offset - tail_offset + 4;
+       return xdr_xcode_array2(buf, base, desc, 0);
+}
+
+int
+xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
+                 struct xdr_array2_desc *desc)
+{
+       if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
+           buf->head->iov_len + buf->page_len + buf->tail->iov_len)
+               return -EINVAL;
+
+       return xdr_xcode_array2(buf, base, desc, 1);
+}
+
+int
+xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
+                int (*actor)(struct scatterlist *, void *), void *data)
+{
+       int i, ret = 0;
+       unsigned page_len, thislen, page_offset;
+       struct scatterlist      sg[1];
+
+       if (offset >= buf->head[0].iov_len) {
+               offset -= buf->head[0].iov_len;
        } else {
-               /* use end of tail as storage for obj:
-                * (We don't copy to the beginning because then we'd have
-                * to worry about doing a potentially overlapping copy.
-                * This assumes the object is at most half the length of the
-                * tail.) */
-               if (obj->len > buf->tail[0].iov_len)
-                       goto out;
-               obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len - 
-                               obj->len;
-               if (read_bytes_from_xdr_buf(buf, offset + 4,
-                                       obj->data, obj->len))
+               thislen = buf->head[0].iov_len - offset;
+               if (thislen > len)
+                       thislen = len;
+               sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
+               ret = actor(sg, data);
+               if (ret)
                        goto out;
+               offset = 0;
+               len -= thislen;
+       }
+       if (len == 0)
+               goto out;
 
+       if (offset >= buf->page_len) {
+               offset -= buf->page_len;
+       } else {
+               page_len = buf->page_len - offset;
+               if (page_len > len)
+                       page_len = len;
+               len -= page_len;
+               page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
+               i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
+               thislen = PAGE_CACHE_SIZE - page_offset;
+               do {
+                       if (thislen > page_len)
+                               thislen = page_len;
+                       sg->page = buf->pages[i];
+                       sg->offset = page_offset;
+                       sg->length = thislen;
+                       ret = actor(sg, data);
+                       if (ret)
+                               goto out;
+                       page_len -= thislen;
+                       i++;
+                       page_offset = 0;
+                       thislen = PAGE_CACHE_SIZE;
+               } while (page_len != 0);
+               offset = 0;
        }
-       return 0;
+       if (len == 0)
+               goto out;
+       if (offset < buf->tail[0].iov_len) {
+               thislen = buf->tail[0].iov_len - offset;
+               if (thislen > len)
+                       thislen = len;
+               sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
+               ret = actor(sg, data);
+               len -= thislen;
+       }
+       if (len != 0)
+               ret = -EINVAL;
 out:
-       return -1;
+       return ret;
 }
+EXPORT_SYMBOL(xdr_process_buf);
+