Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2413 insertions, 0 deletions

diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
new file mode 100644
index 0000000000..62e07c330a
--- /dev/null
+++ b/net/sunrpc/xdr.c
@@ -0,0 +1,2413 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/net/sunrpc/xdr.c
+ *
+ * Generic XDR support.
+ *
+ * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/pagemap.h>
+#include <linux/errno.h>
+#include <linux/sunrpc/xdr.h>
+#include <linux/sunrpc/msg_prot.h>
+#include <linux/bvec.h>
+#include <trace/events/sunrpc.h>
+
+static void _copy_to_pages(struct page **, size_t, const char *, size_t);
+
+
+/*
+ * XDR functions for basic NFS types
+ */
+__be32 *
+xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
+{
+	unsigned int	quadlen = XDR_QUADLEN(obj->len);
+
+	p[quadlen] = 0;		/* zero trailing bytes */
+	*p++ = cpu_to_be32(obj->len);
+	memcpy(p, obj->data, obj->len);
+	return p + XDR_QUADLEN(obj->len);
+}
+EXPORT_SYMBOL_GPL(xdr_encode_netobj);
+
+__be32 *
+xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
+{
+	unsigned int	len;
+
+	if ((len = be32_to_cpu(*p++)) > XDR_MAX_NETOBJ)
+		return NULL;
+	obj->len  = len;
+	obj->data = (u8 *) p;
+	return p + XDR_QUADLEN(len);
+}
+EXPORT_SYMBOL_GPL(xdr_decode_netobj);
+
+/**
+ * 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.
+ *
+ * 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
+ * with zero bytes (see RFC1832).
+ * Note: if ptr is NULL, only the padding is performed.
+ *
+ * Returns the updated current XDR buffer position
+ *
+ */
+__be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
+{
+	if (likely(nbytes != 0)) {
+		unsigned int quadlen = XDR_QUADLEN(nbytes);
+		unsigned int padding = (quadlen << 2) - nbytes;
+
+		if (ptr != NULL)
+			memcpy(p, ptr, nbytes);
+		if (padding != 0)
+			memset((char *)p + nbytes, 0, padding);
+		p += quadlen;
+	}
+	return p;
+}
+EXPORT_SYMBOL_GPL(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.
+ *
+ * Returns the updated current XDR buffer position
+ */
+__be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
+{
+	*p++ = cpu_to_be32(nbytes);
+	return xdr_encode_opaque_fixed(p, ptr, nbytes);
+}
+EXPORT_SYMBOL_GPL(xdr_encode_opaque);
+
+__be32 *
+xdr_encode_string(__be32 *p, const char *string)
+{
+	return xdr_encode_array(p, string, strlen(string));
+}
+EXPORT_SYMBOL_GPL(xdr_encode_string);
+
+__be32 *
+xdr_decode_string_inplace(__be32 *p, char **sp,
+			  unsigned int *lenp, unsigned int maxlen)
+{
+	u32 len;
+
+	len = be32_to_cpu(*p++);
+	if (len > maxlen)
+		return NULL;
+	*lenp = len;
+	*sp = (char *) p;
+	return p + XDR_QUADLEN(len);
+}
+EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);
+
+/**
+ * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
+ * @buf: XDR buffer where string resides
+ * @len: length of string, in bytes
+ *
+ */
+void xdr_terminate_string(const struct xdr_buf *buf, const u32 len)
+{
+	char *kaddr;
+
+	kaddr = kmap_atomic(buf->pages[0]);
+	kaddr[buf->page_base + len] = '\0';
+	kunmap_atomic(kaddr);
+}
+EXPORT_SYMBOL_GPL(xdr_terminate_string);
+
+size_t xdr_buf_pagecount(const struct xdr_buf *buf)
+{
+	if (!buf->page_len)
+		return 0;
+	return (buf->page_base + buf->page_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+}
+
+int
+xdr_alloc_bvec(struct xdr_buf *buf, gfp_t gfp)
+{
+	size_t i, n = xdr_buf_pagecount(buf);
+
+	if (n != 0 && buf->bvec == NULL) {
+		buf->bvec = kmalloc_array(n, sizeof(buf->bvec[0]), gfp);
+		if (!buf->bvec)
+			return -ENOMEM;
+		for (i = 0; i < n; i++) {
+			bvec_set_page(&buf->bvec[i], buf->pages[i], PAGE_SIZE,
+				      0);
+		}
+	}
+	return 0;
+}
+
+void
+xdr_free_bvec(struct xdr_buf *buf)
+{
+	kfree(buf->bvec);
+	buf->bvec = NULL;
+}
+
+/**
+ * xdr_buf_to_bvec - Copy components of an xdr_buf into a bio_vec array
+ * @bvec: bio_vec array to populate
+ * @bvec_size: element count of @bio_vec
+ * @xdr: xdr_buf to be copied
+ *
+ * Returns the number of entries consumed in @bvec.
+ */
+unsigned int xdr_buf_to_bvec(struct bio_vec *bvec, unsigned int bvec_size,
+			     const struct xdr_buf *xdr)
+{
+	const struct kvec *head = xdr->head;
+	const struct kvec *tail = xdr->tail;
+	unsigned int count = 0;
+
+	if (head->iov_len) {
+		bvec_set_virt(bvec++, head->iov_base, head->iov_len);
+		++count;
+	}
+
+	if (xdr->page_len) {
+		unsigned int offset, len, remaining;
+		struct page **pages = xdr->pages;
+
+		offset = offset_in_page(xdr->page_base);
+		remaining = xdr->page_len;
+		while (remaining > 0) {
+			len = min_t(unsigned int, remaining,
+				    PAGE_SIZE - offset);
+			bvec_set_page(bvec++, *pages++, len, offset);
+			remaining -= len;
+			offset = 0;
+			if (unlikely(++count > bvec_size))
+				goto bvec_overflow;
+		}
+	}
+
+	if (tail->iov_len) {
+		bvec_set_virt(bvec, tail->iov_base, tail->iov_len);
+		if (unlikely(++count > bvec_size))
+			goto bvec_overflow;
+	}
+
+	return count;
+
+bvec_overflow:
+	pr_warn_once("%s: bio_vec array overflow\n", __func__);
+	return count - 1;
+}
+
+/**
+ * xdr_inline_pages - Prepare receive buffer for a large reply
+ * @xdr: xdr_buf into which reply will be placed
+ * @offset: expected offset where data payload will start, in bytes
+ * @pages: vector of struct page pointers
+ * @base: offset in first page where receive should start, in bytes
+ * @len: expected size of the upper layer data payload, in bytes
+ *
+ */
+void
+xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
+		 struct page **pages, unsigned int base, unsigned int len)
+{
+	struct kvec *head = xdr->head;
+	struct kvec *tail = xdr->tail;
+	char *buf = (char *)head->iov_base;
+	unsigned int buflen = head->iov_len;
+
+	head->iov_len  = offset;
+
+	xdr->pages = pages;
+	xdr->page_base = base;
+	xdr->page_len = len;
+
+	tail->iov_base = buf + offset;
+	tail->iov_len = buflen - offset;
+	xdr->buflen += len;
+}
+EXPORT_SYMBOL_GPL(xdr_inline_pages);
+
+/*
+ * Helper routines for doing 'memmove' like operations on a struct xdr_buf
+ */
+
+/**
+ * _shift_data_left_pages
+ * @pages: vector of pages containing both the source and dest memory area.
+ * @pgto_base: page vector address of destination
+ * @pgfrom_base: page vector address of source
+ * @len: number of bytes to copy
+ *
+ * Note: the addresses pgto_base and pgfrom_base are both calculated in
+ *       the same way:
+ *            if a memory area starts at byte 'base' in page 'pages[i]',
+ *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
+ * Alse note: pgto_base must be < pgfrom_base, but the memory areas
+ * 	they point to may overlap.
+ */
+static void
+_shift_data_left_pages(struct page **pages, size_t pgto_base,
+			size_t pgfrom_base, size_t len)
+{
+	struct page **pgfrom, **pgto;
+	char *vfrom, *vto;
+	size_t copy;
+
+	BUG_ON(pgfrom_base <= pgto_base);
+
+	if (!len)
+		return;
+
+	pgto = pages + (pgto_base >> PAGE_SHIFT);
+	pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
+
+	pgto_base &= ~PAGE_MASK;
+	pgfrom_base &= ~PAGE_MASK;
+
+	do {
+		if (pgto_base >= PAGE_SIZE) {
+			pgto_base = 0;
+			pgto++;
+		}
+		if (pgfrom_base >= PAGE_SIZE){
+			pgfrom_base = 0;
+			pgfrom++;
+		}
+
+		copy = len;
+		if (copy > (PAGE_SIZE - pgto_base))
+			copy = PAGE_SIZE - pgto_base;
+		if (copy > (PAGE_SIZE - pgfrom_base))
+			copy = PAGE_SIZE - pgfrom_base;
+
+		vto = kmap_atomic(*pgto);
+		if (*pgto != *pgfrom) {
+			vfrom = kmap_atomic(*pgfrom);
+			memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
+			kunmap_atomic(vfrom);
+		} else
+			memmove(vto + pgto_base, vto + pgfrom_base, copy);
+		flush_dcache_page(*pgto);
+		kunmap_atomic(vto);
+
+		pgto_base += copy;
+		pgfrom_base += copy;
+
+	} while ((len -= copy) != 0);
+}
+
+/**
+ * _shift_data_right_pages
+ * @pages: vector of pages containing both the source and dest memory area.
+ * @pgto_base: page vector address of destination
+ * @pgfrom_base: page vector address of source
+ * @len: number of bytes to copy
+ *
+ * Note: the addresses pgto_base and pgfrom_base are both calculated in
+ *       the same way:
+ *            if a memory area starts at byte 'base' in page 'pages[i]',
+ *            then its address is given as (i << PAGE_SHIFT) + base
+ * Also note: pgfrom_base must be < pgto_base, but the memory areas
+ * 	they point to may overlap.
+ */
+static void
+_shift_data_right_pages(struct page **pages, size_t pgto_base,
+		size_t pgfrom_base, size_t len)
+{
+	struct page **pgfrom, **pgto;
+	char *vfrom, *vto;
+	size_t copy;
+
+	BUG_ON(pgto_base <= pgfrom_base);
+
+	if (!len)
+		return;
+
+	pgto_base += len;
+	pgfrom_base += len;
+
+	pgto = pages + (pgto_base >> PAGE_SHIFT);
+	pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
+
+	pgto_base &= ~PAGE_MASK;
+	pgfrom_base &= ~PAGE_MASK;
+
+	do {
+		/* Are any pointers crossing a page boundary? */
+		if (pgto_base == 0) {
+			pgto_base = PAGE_SIZE;
+			pgto--;
+		}
+		if (pgfrom_base == 0) {
+			pgfrom_base = PAGE_SIZE;
+			pgfrom--;
+		}
+
+		copy = len;
+		if (copy > pgto_base)
+			copy = pgto_base;
+		if (copy > pgfrom_base)
+			copy = pgfrom_base;
+		pgto_base -= copy;
+		pgfrom_base -= copy;
+
+		vto = kmap_atomic(*pgto);
+		if (*pgto != *pgfrom) {
+			vfrom = kmap_atomic(*pgfrom);
+			memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
+			kunmap_atomic(vfrom);
+		} else
+			memmove(vto + pgto_base, vto + pgfrom_base, copy);
+		flush_dcache_page(*pgto);
+		kunmap_atomic(vto);
+
+	} while ((len -= copy) != 0);
+}
+
+/**
+ * _copy_to_pages
+ * @pages: array of pages
+ * @pgbase: page vector address of destination
+ * @p: pointer to source data
+ * @len: length
+ *
+ * Copies data from an arbitrary memory location into an array of pages
+ * The copy is assumed to be non-overlapping.
+ */
+static void
+_copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
+{
+	struct page **pgto;
+	char *vto;
+	size_t copy;
+
+	if (!len)
+		return;
+
+	pgto = pages + (pgbase >> PAGE_SHIFT);
+	pgbase &= ~PAGE_MASK;
+
+	for (;;) {
+		copy = PAGE_SIZE - pgbase;
+		if (copy > len)
+			copy = len;
+
+		vto = kmap_atomic(*pgto);
+		memcpy(vto + pgbase, p, copy);
+		kunmap_atomic(vto);
+
+		len -= copy;
+		if (len == 0)
+			break;
+
+		pgbase += copy;
+		if (pgbase == PAGE_SIZE) {
+			flush_dcache_page(*pgto);
+			pgbase = 0;
+			pgto++;
+		}
+		p += copy;
+	}
+	flush_dcache_page(*pgto);
+}
+
+/**
+ * _copy_from_pages
+ * @p: pointer to destination
+ * @pages: array of pages
+ * @pgbase: offset of source data
+ * @len: length
+ *
+ * Copies data into an arbitrary memory location from an array of pages
+ * The copy is assumed to be non-overlapping.
+ */
+void
+_copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
+{
+	struct page **pgfrom;
+	char *vfrom;
+	size_t copy;
+
+	if (!len)
+		return;
+
+	pgfrom = pages + (pgbase >> PAGE_SHIFT);
+	pgbase &= ~PAGE_MASK;
+
+	do {
+		copy = PAGE_SIZE - pgbase;
+		if (copy > len)
+			copy = len;
+
+		vfrom = kmap_atomic(*pgfrom);
+		memcpy(p, vfrom + pgbase, copy);
+		kunmap_atomic(vfrom);
+
+		pgbase += copy;
+		if (pgbase == PAGE_SIZE) {
+			pgbase = 0;
+			pgfrom++;
+		}
+		p += copy;
+
+	} while ((len -= copy) != 0);
+}
+EXPORT_SYMBOL_GPL(_copy_from_pages);
+
+static void xdr_buf_iov_zero(const struct kvec *iov, unsigned int base,
+			     unsigned int len)
+{
+	if (base >= iov->iov_len)
+		return;
+	if (len > iov->iov_len - base)
+		len = iov->iov_len - base;
+	memset(iov->iov_base + base, 0, len);
+}
+
+/**
+ * xdr_buf_pages_zero
+ * @buf: xdr_buf
+ * @pgbase: beginning offset
+ * @len: length
+ */
+static void xdr_buf_pages_zero(const struct xdr_buf *buf, unsigned int pgbase,
+			       unsigned int len)
+{
+	struct page **pages = buf->pages;
+	struct page **page;
+	char *vpage;
+	unsigned int zero;
+
+	if (!len)
+		return;
+	if (pgbase >= buf->page_len) {
+		xdr_buf_iov_zero(buf->tail, pgbase - buf->page_len, len);
+		return;
+	}
+	if (pgbase + len > buf->page_len) {
+		xdr_buf_iov_zero(buf->tail, 0, pgbase + len - buf->page_len);
+		len = buf->page_len - pgbase;
+	}
+
+	pgbase += buf->page_base;
+
+	page = pages + (pgbase >> PAGE_SHIFT);
+	pgbase &= ~PAGE_MASK;
+
+	do {
+		zero = PAGE_SIZE - pgbase;
+		if (zero > len)
+			zero = len;
+
+		vpage = kmap_atomic(*page);
+		memset(vpage + pgbase, 0, zero);
+		kunmap_atomic(vpage);
+
+		flush_dcache_page(*page);
+		pgbase = 0;
+		page++;
+
+	} while ((len -= zero) != 0);
+}
+
+static unsigned int xdr_buf_pages_fill_sparse(const struct xdr_buf *buf,
+					      unsigned int buflen, gfp_t gfp)
+{
+	unsigned int i, npages, pagelen;
+
+	if (!(buf->flags & XDRBUF_SPARSE_PAGES))
+		return buflen;
+	if (buflen <= buf->head->iov_len)
+		return buflen;
+	pagelen = buflen - buf->head->iov_len;
+	if (pagelen > buf->page_len)
+		pagelen = buf->page_len;
+	npages = (pagelen + buf->page_base + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	for (i = 0; i < npages; i++) {
+		if (!buf->pages[i])
+			continue;
+		buf->pages[i] = alloc_page(gfp);
+		if (likely(buf->pages[i]))
+			continue;
+		buflen -= pagelen;
+		pagelen = i << PAGE_SHIFT;
+		if (pagelen > buf->page_base)
+			buflen += pagelen - buf->page_base;
+		break;
+	}
+	return buflen;
+}
+
+static void xdr_buf_try_expand(struct xdr_buf *buf, unsigned int len)
+{
+	struct kvec *head = buf->head;
+	struct kvec *tail = buf->tail;
+	unsigned int sum = head->iov_len + buf->page_len + tail->iov_len;
+	unsigned int free_space, newlen;
+
+	if (sum > buf->len) {
+		free_space = min_t(unsigned int, sum - buf->len, len);
+		newlen = xdr_buf_pages_fill_sparse(buf, buf->len + free_space,
+						   GFP_KERNEL);
+		free_space = newlen - buf->len;
+		buf->len = newlen;
+		len -= free_space;
+		if (!len)
+			return;
+	}
+
+	if (buf->buflen > sum) {
+		/* Expand the tail buffer */
+		free_space = min_t(unsigned int, buf->buflen - sum, len);
+		tail->iov_len += free_space;
+		buf->len += free_space;
+	}
+}
+
+static void xdr_buf_tail_copy_right(const struct xdr_buf *buf,
+				    unsigned int base, unsigned int len,
+				    unsigned int shift)
+{
+	const struct kvec *tail = buf->tail;
+	unsigned int to = base + shift;
+
+	if (to >= tail->iov_len)
+		return;
+	if (len + to > tail->iov_len)
+		len = tail->iov_len - to;
+	memmove(tail->iov_base + to, tail->iov_base + base, len);
+}
+
+static void xdr_buf_pages_copy_right(const struct xdr_buf *buf,
+				     unsigned int base, unsigned int len,
+				     unsigned int shift)
+{
+	const struct kvec *tail = buf->tail;
+	unsigned int to = base + shift;
+	unsigned int pglen = 0;
+	unsigned int talen = 0, tato = 0;
+
+	if (base >= buf->page_len)
+		return;
+	if (len > buf->page_len - base)
+		len = buf->page_len - base;
+	if (to >= buf->page_len) {
+		tato = to - buf->page_len;
+		if (tail->iov_len >= len + tato)
+			talen = len;
+		else if (tail->iov_len > tato)
+			talen = tail->iov_len - tato;
+	} else if (len + to >= buf->page_len) {
+		pglen = buf->page_len - to;
+		talen = len - pglen;
+		if (talen > tail->iov_len)
+			talen = tail->iov_len;
+	} else
+		pglen = len;
+
+	_copy_from_pages(tail->iov_base + tato, buf->pages,
+			 buf->page_base + base + pglen, talen);
+	_shift_data_right_pages(buf->pages, buf->page_base + to,
+				buf->page_base + base, pglen);
+}
+
+static void xdr_buf_head_copy_right(const struct xdr_buf *buf,
+				    unsigned int base, unsigned int len,
+				    unsigned int shift)
+{
+	const struct kvec *head = buf->head;
+	const struct kvec *tail = buf->tail;
+	unsigned int to = base + shift;
+	unsigned int pglen = 0, pgto = 0;
+	unsigned int talen = 0, tato = 0;
+
+	if (base >= head->iov_len)
+		return;
+	if (len > head->iov_len - base)
+		len = head->iov_len - base;
+	if (to >= buf->page_len + head->iov_len) {
+		tato = to - buf->page_len - head->iov_len;
+		talen = len;
+	} else if (to >= head->iov_len) {
+		pgto = to - head->iov_len;
+		pglen = len;
+		if (pgto + pglen > buf->page_len) {
+			talen = pgto + pglen - buf->page_len;
+			pglen -= talen;
+		}
+	} else {
+		pglen = len - to;
+		if (pglen > buf->page_len) {
+			talen = pglen - buf->page_len;
+			pglen = buf->page_len;
+		}
+	}
+
+	len -= talen;
+	base += len;
+	if (talen + tato > tail->iov_len)
+		talen = tail->iov_len > tato ? tail->iov_len - tato : 0;
+	memcpy(tail->iov_base + tato, head->iov_base + base, talen);
+
+	len -= pglen;
+	base -= pglen;
+	_copy_to_pages(buf->pages, buf->page_base + pgto, head->iov_base + base,
+		       pglen);
+
+	base -= len;
+	memmove(head->iov_base + to, head->iov_base + base, len);
+}
+
+static void xdr_buf_tail_shift_right(const struct xdr_buf *buf,
+				     unsigned int base, unsigned int len,
+				     unsigned int shift)
+{
+	const struct kvec *tail = buf->tail;
+
+	if (base >= tail->iov_len || !shift || !len)
+		return;
+	xdr_buf_tail_copy_right(buf, base, len, shift);
+}
+
+static void xdr_buf_pages_shift_right(const struct xdr_buf *buf,
+				      unsigned int base, unsigned int len,
+				      unsigned int shift)
+{
+	if (!shift || !len)
+		return;
+	if (base >= buf->page_len) {
+		xdr_buf_tail_shift_right(buf, base - buf->page_len, len, shift);
+		return;
+	}
+	if (base + len > buf->page_len)
+		xdr_buf_tail_shift_right(buf, 0, base + len - buf->page_len,
+					 shift);
+	xdr_buf_pages_copy_right(buf, base, len, shift);
+}
+
+static void xdr_buf_head_shift_right(const struct xdr_buf *buf,
+				     unsigned int base, unsigned int len,
+				     unsigned int shift)
+{
+	const struct kvec *head = buf->head;
+
+	if (!shift)
+		return;
+	if (base >= head->iov_len) {
+		xdr_buf_pages_shift_right(buf, head->iov_len - base, len,
+					  shift);
+		return;
+	}
+	if (base + len > head->iov_len)
+		xdr_buf_pages_shift_right(buf, 0, base + len - head->iov_len,
+					  shift);
+	xdr_buf_head_copy_right(buf, base, len, shift);
+}
+
+static void xdr_buf_tail_copy_left(const struct xdr_buf *buf, unsigned int base,
+				   unsigned int len, unsigned int shift)
+{
+	const struct kvec *tail = buf->tail;
+
+	if (base >= tail->iov_len)
+		return;
+	if (len > tail->iov_len - base)
+		len = tail->iov_len - base;
+	/* Shift data into head */
+	if (shift > buf->page_len + base) {
+		const struct kvec *head = buf->head;
+		unsigned int hdto =
+			head->iov_len + buf->page_len + base - shift;
+		unsigned int hdlen = len;
+
+		if (WARN_ONCE(shift > head->iov_len + buf->page_len + base,
+			      "SUNRPC: Misaligned data.\n"))
+			return;
+		if (hdto + hdlen > head->iov_len)
+			hdlen = head->iov_len - hdto;
+		memcpy(head->iov_base + hdto, tail->iov_base + base, hdlen);
+		base += hdlen;
+		len -= hdlen;
+		if (!len)
+			return;
+	}
+	/* Shift data into pages */
+	if (shift > base) {
+		unsigned int pgto = buf->page_len + base - shift;
+		unsigned int pglen = len;
+
+		if (pgto + pglen > buf->page_len)
+			pglen = buf->page_len - pgto;
+		_copy_to_pages(buf->pages, buf->page_base + pgto,
+			       tail->iov_base + base, pglen);
+		base += pglen;
+		len -= pglen;
+		if (!len)
+			return;
+	}
+	memmove(tail->iov_base + base - shift, tail->iov_base + base, len);
+}
+
+static void xdr_buf_pages_copy_left(const struct xdr_buf *buf,
+				    unsigned int base, unsigned int len,
+				    unsigned int shift)
+{
+	unsigned int pgto;
+
+	if (base >= buf->page_len)
+		return;
+	if (len > buf->page_len - base)
+		len = buf->page_len - base;
+	/* Shift data into head */
+	if (shift > base) {
+		const struct kvec *head = buf->head;
+		unsigned int hdto = head->iov_len + base - shift;
+		unsigned int hdlen = len;
+
+		if (WARN_ONCE(shift > head->iov_len + base,
+			      "SUNRPC: Misaligned data.\n"))
+			return;
+		if (hdto + hdlen > head->iov_len)
+			hdlen = head->iov_len - hdto;
+		_copy_from_pages(head->iov_base + hdto, buf->pages,
+				 buf->page_base + base, hdlen);
+		base += hdlen;
+		len -= hdlen;
+		if (!len)
+			return;
+	}
+	pgto = base - shift;
+	_shift_data_left_pages(buf->pages, buf->page_base + pgto,
+			       buf->page_base + base, len);
+}
+
+static void xdr_buf_tail_shift_left(const struct xdr_buf *buf,
+				    unsigned int base, unsigned int len,
+				    unsigned int shift)
+{
+	if (!shift || !len)
+		return;
+	xdr_buf_tail_copy_left(buf, base, len, shift);
+}
+
+static void xdr_buf_pages_shift_left(const struct xdr_buf *buf,
+				     unsigned int base, unsigned int len,
+				     unsigned int shift)
+{
+	if (!shift || !len)
+		return;
+	if (base >= buf->page_len) {
+		xdr_buf_tail_shift_left(buf, base - buf->page_len, len, shift);
+		return;
+	}
+	xdr_buf_pages_copy_left(buf, base, len, shift);
+	len += base;
+	if (len <= buf->page_len)
+		return;
+	xdr_buf_tail_copy_left(buf, 0, len - buf->page_len, shift);
+}
+
+static void xdr_buf_head_shift_left(const struct xdr_buf *buf,
+				    unsigned int base, unsigned int len,
+				    unsigned int shift)
+{
+	const struct kvec *head = buf->head;
+	unsigned int bytes;
+
+	if (!shift || !len)
+		return;
+
+	if (shift > base) {
+		bytes = (shift - base);
+		if (bytes >= len)
+			return;
+		base += bytes;
+		len -= bytes;
+	}
+
+	if (base < head->iov_len) {
+		bytes = min_t(unsigned int, len, head->iov_len - base);
+		memmove(head->iov_base + (base - shift),
+			head->iov_base + base, bytes);
+		base += bytes;
+		len -= bytes;
+	}
+	xdr_buf_pages_shift_left(buf, base - head->iov_len, len, shift);
+}
+
+/**
+ * xdr_shrink_bufhead
+ * @buf: xdr_buf
+ * @len: new length of buf->head[0]
+ *
+ * Shrinks XDR buffer's header kvec buf->head[0], setting it to
+ * 'len' bytes. The extra data is not lost, but is instead
+ * moved into the inlined pages and/or the tail.
+ */
+static unsigned int xdr_shrink_bufhead(struct xdr_buf *buf, unsigned int len)
+{
+	struct kvec *head = buf->head;
+	unsigned int shift, buflen = max(buf->len, len);
+
+	WARN_ON_ONCE(len > head->iov_len);
+	if (head->iov_len > buflen) {
+		buf->buflen -= head->iov_len - buflen;
+		head->iov_len = buflen;
+	}
+	if (len >= head->iov_len)
+		return 0;
+	shift = head->iov_len - len;
+	xdr_buf_try_expand(buf, shift);
+	xdr_buf_head_shift_right(buf, len, buflen - len, shift);
+	head->iov_len = len;
+	buf->buflen -= shift;
+	buf->len -= shift;
+	return shift;
+}
+
+/**
+ * xdr_shrink_pagelen - shrinks buf->pages to @len bytes
+ * @buf: xdr_buf
+ * @len: new page buffer length
+ *
+ * The extra data is not lost, but is instead moved into buf->tail.
+ * Returns the actual number of bytes moved.
+ */
+static unsigned int xdr_shrink_pagelen(struct xdr_buf *buf, unsigned int len)
+{
+	unsigned int shift, buflen = buf->len - buf->head->iov_len;
+
+	WARN_ON_ONCE(len > buf->page_len);
+	if (buf->head->iov_len >= buf->len || len > buflen)
+		buflen = len;
+	if (buf->page_len > buflen) {
+		buf->buflen -= buf->page_len - buflen;
+		buf->page_len = buflen;
+	}
+	if (len >= buf->page_len)
+		return 0;
+	shift = buf->page_len - len;
+	xdr_buf_try_expand(buf, shift);
+	xdr_buf_pages_shift_right(buf, len, buflen - len, shift);
+	buf->page_len = len;
+	buf->len -= shift;
+	buf->buflen -= shift;
+	return shift;
+}
+
+/**
+ * xdr_stream_pos - Return the current offset from the start of the xdr_stream
+ * @xdr: pointer to struct xdr_stream
+ */
+unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
+{
+	return (unsigned int)(XDR_QUADLEN(xdr->buf->len) - xdr->nwords) << 2;
+}
+EXPORT_SYMBOL_GPL(xdr_stream_pos);
+
+static void xdr_stream_set_pos(struct xdr_stream *xdr, unsigned int pos)
+{
+	unsigned int blen = xdr->buf->len;
+
+	xdr->nwords = blen > pos ? XDR_QUADLEN(blen) - XDR_QUADLEN(pos) : 0;
+}
+
+static void xdr_stream_page_set_pos(struct xdr_stream *xdr, unsigned int pos)
+{
+	xdr_stream_set_pos(xdr, pos + xdr->buf->head[0].iov_len);
+}
+
+/**
+ * xdr_page_pos - Return the current offset from the start of the xdr pages
+ * @xdr: pointer to struct xdr_stream
+ */
+unsigned int xdr_page_pos(const struct xdr_stream *xdr)
+{
+	unsigned int pos = xdr_stream_pos(xdr);
+
+	WARN_ON(pos < xdr->buf->head[0].iov_len);
+	return pos - xdr->buf->head[0].iov_len;
+}
+EXPORT_SYMBOL_GPL(xdr_page_pos);
+
+/**
+ * xdr_init_encode - Initialize a struct xdr_stream for sending data.
+ * @xdr: pointer to xdr_stream struct
+ * @buf: pointer to XDR buffer in which to encode data
+ * @p: current pointer inside XDR buffer
+ * @rqst: pointer to controlling rpc_rqst, for debugging
+ *
+ * Note: at the moment the RPC client only passes the length of our
+ *	 scratch buffer in the xdr_buf's header kvec. Previously this
+ *	 meant we needed to call xdr_adjust_iovec() after encoding the
+ *	 data. With the new scheme, the xdr_stream manages the details
+ *	 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, __be32 *p,
+		     struct rpc_rqst *rqst)
+{
+	struct kvec *iov = buf->head;
+	int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
+
+	xdr_reset_scratch_buffer(xdr);
+	BUG_ON(scratch_len < 0);
+	xdr->buf = buf;
+	xdr->iov = iov;
+	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;
+	}
+	xdr->rqst = rqst;
+}
+EXPORT_SYMBOL_GPL(xdr_init_encode);
+
+/**
+ * xdr_init_encode_pages - Initialize an xdr_stream for encoding into pages
+ * @xdr: pointer to xdr_stream struct
+ * @buf: pointer to XDR buffer into which to encode data
+ * @pages: list of pages to decode into
+ * @rqst: pointer to controlling rpc_rqst, for debugging
+ *
+ */
+void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
+			   struct page **pages, struct rpc_rqst *rqst)
+{
+	xdr_reset_scratch_buffer(xdr);
+
+	xdr->buf = buf;
+	xdr->page_ptr = pages;
+	xdr->iov = NULL;
+	xdr->p = page_address(*pages);
+	xdr->end = (void *)xdr->p + min_t(u32, buf->buflen, PAGE_SIZE);
+	xdr->rqst = rqst;
+}
+EXPORT_SYMBOL_GPL(xdr_init_encode_pages);
+
+/**
+ * __xdr_commit_encode - Ensure all data is written to buffer
+ * @xdr: pointer to xdr_stream
+ *
+ * We handle encoding across page boundaries by giving the caller a
+ * temporary location to write to, then later copying the data into
+ * place; xdr_commit_encode does that copying.
+ *
+ * Normally the caller doesn't need to call this directly, as the
+ * following xdr_reserve_space will do it.  But an explicit call may be
+ * required at the end of encoding, or any other time when the xdr_buf
+ * data might be read.
+ */
+void __xdr_commit_encode(struct xdr_stream *xdr)
+{
+	size_t shift = xdr->scratch.iov_len;
+	void *page;
+
+	page = page_address(*xdr->page_ptr);
+	memcpy(xdr->scratch.iov_base, page, shift);
+	memmove(page, page + shift, (void *)xdr->p - page);
+	xdr_reset_scratch_buffer(xdr);
+}
+EXPORT_SYMBOL_GPL(__xdr_commit_encode);
+
+/*
+ * The buffer space to be reserved crosses the boundary between
+ * xdr->buf->head and xdr->buf->pages, or between two pages
+ * in xdr->buf->pages.
+ */
+static noinline __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
+						   size_t nbytes)
+{
+	int space_left;
+	int frag1bytes, frag2bytes;
+	void *p;
+
+	if (nbytes > PAGE_SIZE)
+		goto out_overflow; /* Bigger buffers require special handling */
+	if (xdr->buf->len + nbytes > xdr->buf->buflen)
+		goto out_overflow; /* Sorry, we're totally out of space */
+	frag1bytes = (xdr->end - xdr->p) << 2;
+	frag2bytes = nbytes - frag1bytes;
+	if (xdr->iov)
+		xdr->iov->iov_len += frag1bytes;
+	else
+		xdr->buf->page_len += frag1bytes;
+	xdr->page_ptr++;
+	xdr->iov = NULL;
+
+	/*
+	 * If the last encode didn't end exactly on a page boundary, the
+	 * next one will straddle boundaries.  Encode into the next
+	 * page, then copy it back later in xdr_commit_encode.  We use
+	 * the "scratch" iov to track any temporarily unused fragment of
+	 * space at the end of the previous buffer:
+	 */
+	xdr_set_scratch_buffer(xdr, xdr->p, frag1bytes);
+
+	/*
+	 * xdr->p is where the next encode will start after
+	 * xdr_commit_encode() has shifted this one back:
+	 */
+	p = page_address(*xdr->page_ptr);
+	xdr->p = p + frag2bytes;
+	space_left = xdr->buf->buflen - xdr->buf->len;
+	if (space_left - frag1bytes >= PAGE_SIZE)
+		xdr->end = p + PAGE_SIZE;
+	else
+		xdr->end = p + space_left - frag1bytes;
+
+	xdr->buf->page_len += frag2bytes;
+	xdr->buf->len += nbytes;
+	return p;
+out_overflow:
+	trace_rpc_xdr_overflow(xdr, nbytes);
+	return NULL;
+}
+
+/**
+ * xdr_reserve_space - Reserve buffer space for sending
+ * @xdr: pointer to xdr_stream
+ * @nbytes: number of bytes to reserve
+ *
+ * Checks that we have enough buffer space to encode 'nbytes' more
+ * bytes of data. If so, update the total xdr_buf length, and
+ * adjust the length of the current kvec.
+ */
+__be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
+{
+	__be32 *p = xdr->p;
+	__be32 *q;
+
+	xdr_commit_encode(xdr);
+	/* align nbytes on the next 32-bit boundary */
+	nbytes += 3;
+	nbytes &= ~3;
+	q = p + (nbytes >> 2);
+	if (unlikely(q > xdr->end || q < p))
+		return xdr_get_next_encode_buffer(xdr, nbytes);
+	xdr->p = q;
+	if (xdr->iov)
+		xdr->iov->iov_len += nbytes;
+	else
+		xdr->buf->page_len += nbytes;
+	xdr->buf->len += nbytes;
+	return p;
+}
+EXPORT_SYMBOL_GPL(xdr_reserve_space);
+
+/**
+ * xdr_reserve_space_vec - Reserves a large amount of buffer space for sending
+ * @xdr: pointer to xdr_stream
+ * @nbytes: number of bytes to reserve
+ *
+ * The size argument passed to xdr_reserve_space() is determined based
+ * on the number of bytes remaining in the current page to avoid
+ * invalidating iov_base pointers when xdr_commit_encode() is called.
+ *
+ * Return values:
+ *   %0: success
+ *   %-EMSGSIZE: not enough space is available in @xdr
+ */
+int xdr_reserve_space_vec(struct xdr_stream *xdr, size_t nbytes)
+{
+	size_t thislen;
+	__be32 *p;
+
+	/*
+	 * svcrdma requires every READ payload to start somewhere
+	 * in xdr->pages.
+	 */
+	if (xdr->iov == xdr->buf->head) {
+		xdr->iov = NULL;
+		xdr->end = xdr->p;
+	}
+
+	/* XXX: Let's find a way to make this more efficient */
+	while (nbytes) {
+		thislen = xdr->buf->page_len % PAGE_SIZE;
+		thislen = min_t(size_t, nbytes, PAGE_SIZE - thislen);
+
+		p = xdr_reserve_space(xdr, thislen);
+		if (!p)
+			return -EMSGSIZE;
+
+		nbytes -= thislen;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xdr_reserve_space_vec);
+
+/**
+ * xdr_truncate_encode - truncate an encode buffer
+ * @xdr: pointer to xdr_stream
+ * @len: new length of buffer
+ *
+ * Truncates the xdr stream, so that xdr->buf->len == len,
+ * and xdr->p points at offset len from the start of the buffer, and
+ * head, tail, and page lengths are adjusted to correspond.
+ *
+ * If this means moving xdr->p to a different buffer, we assume that
+ * the end pointer should be set to the end of the current page,
+ * except in the case of the head buffer when we assume the head
+ * buffer's current length represents the end of the available buffer.
+ *
+ * This is *not* safe to use on a buffer that already has inlined page
+ * cache pages (as in a zero-copy server read reply), except for the
+ * simple case of truncating from one position in the tail to another.
+ *
+ */
+void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
+{
+	struct xdr_buf *buf = xdr->buf;
+	struct kvec *head = buf->head;
+	struct kvec *tail = buf->tail;
+	int fraglen;
+	int new;
+
+	if (len > buf->len) {
+		WARN_ON_ONCE(1);
+		return;
+	}
+	xdr_commit_encode(xdr);
+
+	fraglen = min_t(int, buf->len - len, tail->iov_len);
+	tail->iov_len -= fraglen;
+	buf->len -= fraglen;
+	if (tail->iov_len) {
+		xdr->p = tail->iov_base + tail->iov_len;
+		WARN_ON_ONCE(!xdr->end);
+		WARN_ON_ONCE(!xdr->iov);
+		return;
+	}
+	WARN_ON_ONCE(fraglen);
+	fraglen = min_t(int, buf->len - len, buf->page_len);
+	buf->page_len -= fraglen;
+	buf->len -= fraglen;
+
+	new = buf->page_base + buf->page_len;
+
+	xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
+
+	if (buf->page_len) {
+		xdr->p = page_address(*xdr->page_ptr);
+		xdr->end = (void *)xdr->p + PAGE_SIZE;
+		xdr->p = (void *)xdr->p + (new % PAGE_SIZE);
+		WARN_ON_ONCE(xdr->iov);
+		return;
+	}
+	if (fraglen)
+		xdr->end = head->iov_base + head->iov_len;
+	/* (otherwise assume xdr->end is already set) */
+	xdr->page_ptr--;
+	head->iov_len = len;
+	buf->len = len;
+	xdr->p = head->iov_base + head->iov_len;
+	xdr->iov = buf->head;
+}
+EXPORT_SYMBOL(xdr_truncate_encode);
+
+/**
+ * xdr_truncate_decode - Truncate a decoding stream
+ * @xdr: pointer to struct xdr_stream
+ * @len: Number of bytes to remove
+ *
+ */
+void xdr_truncate_decode(struct xdr_stream *xdr, size_t len)
+{
+	unsigned int nbytes = xdr_align_size(len);
+
+	xdr->buf->len -= nbytes;
+	xdr->nwords -= XDR_QUADLEN(nbytes);
+}
+EXPORT_SYMBOL_GPL(xdr_truncate_decode);
+
+/**
+ * xdr_restrict_buflen - decrease available buffer space
+ * @xdr: pointer to xdr_stream
+ * @newbuflen: new maximum number of bytes available
+ *
+ * Adjust our idea of how much space is available in the buffer.
+ * If we've already used too much space in the buffer, returns -1.
+ * If the available space is already smaller than newbuflen, returns 0
+ * and does nothing.  Otherwise, adjusts xdr->buf->buflen to newbuflen
+ * and ensures xdr->end is set at most offset newbuflen from the start
+ * of the buffer.
+ */
+int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen)
+{
+	struct xdr_buf *buf = xdr->buf;
+	int left_in_this_buf = (void *)xdr->end - (void *)xdr->p;
+	int end_offset = buf->len + left_in_this_buf;
+
+	if (newbuflen < 0 || newbuflen < buf->len)
+		return -1;
+	if (newbuflen > buf->buflen)
+		return 0;
+	if (newbuflen < end_offset)
+		xdr->end = (void *)xdr->end + newbuflen - end_offset;
+	buf->buflen = newbuflen;
+	return 0;
+}
+EXPORT_SYMBOL(xdr_restrict_buflen);
+
+/**
+ * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
+ * @xdr: pointer to xdr_stream
+ * @pages: array of pages to insert
+ * @base: starting offset of first data byte in @pages
+ * @len: number of data bytes in @pages to insert
+ *
+ * After the @pages are added, the tail iovec is instantiated pointing to
+ * end of the head buffer, and the stream is set up to encode subsequent
+ * items into the tail.
+ */
+void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
+		 unsigned int len)
+{
+	struct xdr_buf *buf = xdr->buf;
+	struct kvec *tail = buf->tail;
+
+	buf->pages = pages;
+	buf->page_base = base;
+	buf->page_len = len;
+
+	tail->iov_base = xdr->p;
+	tail->iov_len = 0;
+	xdr->iov = tail;
+
+	if (len & 3) {
+		unsigned int pad = 4 - (len & 3);
+
+		BUG_ON(xdr->p >= xdr->end);
+		tail->iov_base = (char *)xdr->p + (len & 3);
+		tail->iov_len += pad;
+		len += pad;
+		*xdr->p++ = 0;
+	}
+	buf->buflen += len;
+	buf->len += len;
+}
+EXPORT_SYMBOL_GPL(xdr_write_pages);
+
+static unsigned int xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
+				unsigned int base, unsigned int len)
+{
+	if (len > iov->iov_len)
+		len = iov->iov_len;
+	if (unlikely(base > len))
+		base = len;
+	xdr->p = (__be32*)(iov->iov_base + base);
+	xdr->end = (__be32*)(iov->iov_base + len);
+	xdr->iov = iov;
+	xdr->page_ptr = NULL;
+	return len - base;
+}
+
+static unsigned int xdr_set_tail_base(struct xdr_stream *xdr,
+				      unsigned int base, unsigned int len)
+{
+	struct xdr_buf *buf = xdr->buf;
+
+	xdr_stream_set_pos(xdr, base + buf->page_len + buf->head->iov_len);
+	return xdr_set_iov(xdr, buf->tail, base, len);
+}
+
+static void xdr_stream_unmap_current_page(struct xdr_stream *xdr)
+{
+	if (xdr->page_kaddr) {
+		kunmap_local(xdr->page_kaddr);
+		xdr->page_kaddr = NULL;
+	}
+}
+
+static unsigned int xdr_set_page_base(struct xdr_stream *xdr,
+				      unsigned int base, unsigned int len)
+{
+	unsigned int pgnr;
+	unsigned int maxlen;
+	unsigned int pgoff;
+	unsigned int pgend;
+	void *kaddr;
+
+	maxlen = xdr->buf->page_len;
+	if (base >= maxlen)
+		return 0;
+	else
+		maxlen -= base;
+	if (len > maxlen)
+		len = maxlen;
+
+	xdr_stream_unmap_current_page(xdr);
+	xdr_stream_page_set_pos(xdr, base);
+	base += xdr->buf->page_base;
+
+	pgnr = base >> PAGE_SHIFT;
+	xdr->page_ptr = &xdr->buf->pages[pgnr];
+
+	if (PageHighMem(*xdr->page_ptr)) {
+		xdr->page_kaddr = kmap_local_page(*xdr->page_ptr);
+		kaddr = xdr->page_kaddr;
+	} else
+		kaddr = page_address(*xdr->page_ptr);
+
+	pgoff = base & ~PAGE_MASK;
+	xdr->p = (__be32*)(kaddr + pgoff);
+
+	pgend = pgoff + len;
+	if (pgend > PAGE_SIZE)
+		pgend = PAGE_SIZE;
+	xdr->end = (__be32*)(kaddr + pgend);
+	xdr->iov = NULL;
+	return len;
+}
+
+static void xdr_set_page(struct xdr_stream *xdr, unsigned int base,
+			 unsigned int len)
+{
+	if (xdr_set_page_base(xdr, base, len) == 0) {
+		base -= xdr->buf->page_len;
+		xdr_set_tail_base(xdr, base, len);
+	}
+}
+
+static void xdr_set_next_page(struct xdr_stream *xdr)
+{
+	unsigned int newbase;
+
+	newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
+	newbase -= xdr->buf->page_base;
+	if (newbase < xdr->buf->page_len)
+		xdr_set_page_base(xdr, newbase, xdr_stream_remaining(xdr));
+	else
+		xdr_set_tail_base(xdr, 0, xdr_stream_remaining(xdr));
+}
+
+static bool xdr_set_next_buffer(struct xdr_stream *xdr)
+{
+	if (xdr->page_ptr != NULL)
+		xdr_set_next_page(xdr);
+	else if (xdr->iov == xdr->buf->head)
+		xdr_set_page(xdr, 0, xdr_stream_remaining(xdr));
+	return xdr->p != xdr->end;
+}
+
+/**
+ * xdr_init_decode - Initialize an xdr_stream for decoding data.
+ * @xdr: pointer to xdr_stream struct
+ * @buf: pointer to XDR buffer from which to decode data
+ * @p: current pointer inside XDR buffer
+ * @rqst: pointer to controlling rpc_rqst, for debugging
+ */
+void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
+		     struct rpc_rqst *rqst)
+{
+	xdr->buf = buf;
+	xdr->page_kaddr = NULL;
+	xdr_reset_scratch_buffer(xdr);
+	xdr->nwords = XDR_QUADLEN(buf->len);
+	if (xdr_set_iov(xdr, buf->head, 0, buf->len) == 0 &&
+	    xdr_set_page_base(xdr, 0, buf->len) == 0)
+		xdr_set_iov(xdr, buf->tail, 0, buf->len);
+	if (p != NULL && p > xdr->p && xdr->end >= p) {
+		xdr->nwords -= p - xdr->p;
+		xdr->p = p;
+	}
+	xdr->rqst = rqst;
+}
+EXPORT_SYMBOL_GPL(xdr_init_decode);
+
+/**
+ * xdr_init_decode_pages - Initialize an xdr_stream for decoding into pages
+ * @xdr: pointer to xdr_stream struct
+ * @buf: pointer to XDR buffer from which to decode data
+ * @pages: list of pages to decode into
+ * @len: length in bytes of buffer in pages
+ */
+void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
+			   struct page **pages, unsigned int len)
+{
+	memset(buf, 0, sizeof(*buf));
+	buf->pages =  pages;
+	buf->page_len =  len;
+	buf->buflen =  len;
+	buf->len = len;
+	xdr_init_decode(xdr, buf, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
+
+/**
+ * xdr_finish_decode - Clean up the xdr_stream after decoding data.
+ * @xdr: pointer to xdr_stream struct
+ */
+void xdr_finish_decode(struct xdr_stream *xdr)
+{
+	xdr_stream_unmap_current_page(xdr);
+}
+EXPORT_SYMBOL(xdr_finish_decode);
+
+static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
+{
+	unsigned int nwords = XDR_QUADLEN(nbytes);
+	__be32 *p = xdr->p;
+	__be32 *q = p + nwords;
+
+	if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
+		return NULL;
+	xdr->p = q;
+	xdr->nwords -= nwords;
+	return p;
+}
+
+static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
+{
+	__be32 *p;
+	char *cpdest = xdr->scratch.iov_base;
+	size_t cplen = (char *)xdr->end - (char *)xdr->p;
+
+	if (nbytes > xdr->scratch.iov_len)
+		goto out_overflow;
+	p = __xdr_inline_decode(xdr, cplen);
+	if (p == NULL)
+		return NULL;
+	memcpy(cpdest, p, cplen);
+	if (!xdr_set_next_buffer(xdr))
+		goto out_overflow;
+	cpdest += cplen;
+	nbytes -= cplen;
+	p = __xdr_inline_decode(xdr, nbytes);
+	if (p == NULL)
+		return NULL;
+	memcpy(cpdest, p, nbytes);
+	return xdr->scratch.iov_base;
+out_overflow:
+	trace_rpc_xdr_overflow(xdr, nbytes);
+	return NULL;
+}
+
+/**
+ * xdr_inline_decode - Retrieve XDR data to decode
+ * @xdr: pointer to xdr_stream struct
+ * @nbytes: number of bytes of data to decode
+ *
+ * Check if the input buffer is long enough to enable us to decode
+ * 'nbytes' more bytes of data starting at the current position.
+ * If so return the current pointer, then update the current
+ * pointer position.
+ */
+__be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
+{
+	__be32 *p;
+
+	if (unlikely(nbytes == 0))
+		return xdr->p;
+	if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
+		goto out_overflow;
+	p = __xdr_inline_decode(xdr, nbytes);
+	if (p != NULL)
+		return p;
+	return xdr_copy_to_scratch(xdr, nbytes);
+out_overflow:
+	trace_rpc_xdr_overflow(xdr, nbytes);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(xdr_inline_decode);
+
+static void xdr_realign_pages(struct xdr_stream *xdr)
+{
+	struct xdr_buf *buf = xdr->buf;
+	struct kvec *iov = buf->head;
+	unsigned int cur = xdr_stream_pos(xdr);
+	unsigned int copied;
+
+	/* Realign pages to current pointer position */
+	if (iov->iov_len > cur) {
+		copied = xdr_shrink_bufhead(buf, cur);
+		trace_rpc_xdr_alignment(xdr, cur, copied);
+		xdr_set_page(xdr, 0, buf->page_len);
+	}
+}
+
+static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
+{
+	struct xdr_buf *buf = xdr->buf;
+	unsigned int nwords = XDR_QUADLEN(len);
+	unsigned int copied;
+
+	if (xdr->nwords == 0)
+		return 0;
+
+	xdr_realign_pages(xdr);
+	if (nwords > xdr->nwords) {
+		nwords = xdr->nwords;
+		len = nwords << 2;
+	}
+	if (buf->page_len <= len)
+		len = buf->page_len;
+	else if (nwords < xdr->nwords) {
+		/* Truncate page data and move it into the tail */
+		copied = xdr_shrink_pagelen(buf, len);
+		trace_rpc_xdr_alignment(xdr, len, copied);
+	}
+	return len;
+}
+
+/**
+ * xdr_read_pages - align page-based XDR data to current pointer position
+ * @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 xdr_stream current position is
+ * then advanced past that data to align to the next XDR object in the tail.
+ *
+ * Returns the number of XDR encoded bytes now contained in the pages
+ */
+unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
+{
+	unsigned int nwords = XDR_QUADLEN(len);
+	unsigned int base, end, pglen;
+
+	pglen = xdr_align_pages(xdr, nwords << 2);
+	if (pglen == 0)
+		return 0;
+
+	base = (nwords << 2) - pglen;
+	end = xdr_stream_remaining(xdr) - pglen;
+
+	xdr_set_tail_base(xdr, base, end);
+	return len <= pglen ? len : pglen;
+}
+EXPORT_SYMBOL_GPL(xdr_read_pages);
+
+/**
+ * xdr_set_pagelen - Sets the length of the XDR pages
+ * @xdr: pointer to xdr_stream struct
+ * @len: new length of the XDR page data
+ *
+ * Either grows or shrinks the length of the xdr pages by setting pagelen to
+ * @len bytes. When shrinking, any extra data is moved into buf->tail, whereas
+ * when growing any data beyond the current pointer is moved into the tail.
+ *
+ * Returns True if the operation was successful, and False otherwise.
+ */
+void xdr_set_pagelen(struct xdr_stream *xdr, unsigned int len)
+{
+	struct xdr_buf *buf = xdr->buf;
+	size_t remaining = xdr_stream_remaining(xdr);
+	size_t base = 0;
+
+	if (len < buf->page_len) {
+		base = buf->page_len - len;
+		xdr_shrink_pagelen(buf, len);
+	} else {
+		xdr_buf_head_shift_right(buf, xdr_stream_pos(xdr),
+					 buf->page_len, remaining);
+		if (len > buf->page_len)
+			xdr_buf_try_expand(buf, len - buf->page_len);
+	}
+	xdr_set_tail_base(xdr, base, remaining);
+}
+EXPORT_SYMBOL_GPL(xdr_set_pagelen);
+
+/**
+ * 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)
+{
+	len = xdr_align_pages(xdr, len);
+	/*
+	 * Position current pointer at beginning of tail, and
+	 * set remaining message length.
+	 */
+	if (len != 0)
+		xdr_set_page_base(xdr, 0, len);
+}
+EXPORT_SYMBOL_GPL(xdr_enter_page);
+
+static const struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
+
+void xdr_buf_from_iov(const struct kvec *iov, struct xdr_buf *buf)
+{
+	buf->head[0] = *iov;
+	buf->tail[0] = empty_iov;
+	buf->page_len = 0;
+	buf->buflen = buf->len = iov->iov_len;
+}
+EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
+
+/**
+ * xdr_buf_subsegment - set subbuf to a portion of buf
+ * @buf: an xdr buffer
+ * @subbuf: the result buffer
+ * @base: beginning of range in bytes
+ * @len: length of range in bytes
+ *
+ * sets @subbuf to an xdr buffer representing the portion of @buf of
+ * length @len starting at offset @base.
+ *
+ * @buf and @subbuf may be pointers to the same struct xdr_buf.
+ *
+ * Returns -1 if base or length are out of bounds.
+ */
+int xdr_buf_subsegment(const struct xdr_buf *buf, struct xdr_buf *subbuf,
+		       unsigned int base, unsigned int len)
+{
+	subbuf->buflen = subbuf->len = 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 {
+		base -= buf->head[0].iov_len;
+		subbuf->head[0].iov_base = buf->head[0].iov_base;
+		subbuf->head[0].iov_len = 0;
+	}
+
+	if (base < buf->page_len) {
+		subbuf->page_len = min(buf->page_len - base, len);
+		base += buf->page_base;
+		subbuf->page_base = base & ~PAGE_MASK;
+		subbuf->pages = &buf->pages[base >> PAGE_SHIFT];
+		len -= subbuf->page_len;
+		base = 0;
+	} else {
+		base -= buf->page_len;
+		subbuf->pages = buf->pages;
+		subbuf->page_base = 0;
+		subbuf->page_len = 0;
+	}
+
+	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 {
+		base -= buf->tail[0].iov_len;
+		subbuf->tail[0].iov_base = buf->tail[0].iov_base;
+		subbuf->tail[0].iov_len = 0;
+	}
+
+	if (base || len)
+		return -1;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
+
+/**
+ * xdr_stream_subsegment - set @subbuf to a portion of @xdr
+ * @xdr: an xdr_stream set up for decoding
+ * @subbuf: the result buffer
+ * @nbytes: length of @xdr to extract, in bytes
+ *
+ * Sets up @subbuf to represent a portion of @xdr. The portion
+ * starts at the current offset in @xdr, and extends for a length
+ * of @nbytes. If this is successful, @xdr is advanced to the next
+ * XDR data item following that portion.
+ *
+ * Return values:
+ *   %true: @subbuf has been initialized, and @xdr has been advanced.
+ *   %false: a bounds error has occurred
+ */
+bool xdr_stream_subsegment(struct xdr_stream *xdr, struct xdr_buf *subbuf,
+			   unsigned int nbytes)
+{
+	unsigned int start = xdr_stream_pos(xdr);
+	unsigned int remaining, len;
+
+	/* Extract @subbuf and bounds-check the fn arguments */
+	if (xdr_buf_subsegment(xdr->buf, subbuf, start, nbytes))
+		return false;
+
+	/* Advance @xdr by @nbytes */
+	for (remaining = nbytes; remaining;) {
+		if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
+			return false;
+
+		len = (char *)xdr->end - (char *)xdr->p;
+		if (remaining <= len) {
+			xdr->p = (__be32 *)((char *)xdr->p +
+					(remaining + xdr_pad_size(nbytes)));
+			break;
+		}
+
+		xdr->p = (__be32 *)((char *)xdr->p + len);
+		xdr->end = xdr->p;
+		remaining -= len;
+	}
+
+	xdr_stream_set_pos(xdr, start + nbytes);
+	return true;
+}
+EXPORT_SYMBOL_GPL(xdr_stream_subsegment);
+
+/**
+ * xdr_stream_move_subsegment - Move part of a stream to another position
+ * @xdr: the source xdr_stream
+ * @offset: the source offset of the segment
+ * @target: the target offset of the segment
+ * @length: the number of bytes to move
+ *
+ * Moves @length bytes from @offset to @target in the xdr_stream, overwriting
+ * anything in its space. Returns the number of bytes in the segment.
+ */
+unsigned int xdr_stream_move_subsegment(struct xdr_stream *xdr, unsigned int offset,
+					unsigned int target, unsigned int length)
+{
+	struct xdr_buf buf;
+	unsigned int shift;
+
+	if (offset < target) {
+		shift = target - offset;
+		if (xdr_buf_subsegment(xdr->buf, &buf, offset, shift + length) < 0)
+			return 0;
+		xdr_buf_head_shift_right(&buf, 0, length, shift);
+	} else if (offset > target) {
+		shift = offset - target;
+		if (xdr_buf_subsegment(xdr->buf, &buf, target, shift + length) < 0)
+			return 0;
+		xdr_buf_head_shift_left(&buf, shift, length, shift);
+	}
+	return length;
+}
+EXPORT_SYMBOL_GPL(xdr_stream_move_subsegment);
+
+/**
+ * xdr_stream_zero - zero out a portion of an xdr_stream
+ * @xdr: an xdr_stream to zero out
+ * @offset: the starting point in the stream
+ * @length: the number of bytes to zero
+ */
+unsigned int xdr_stream_zero(struct xdr_stream *xdr, unsigned int offset,
+			     unsigned int length)
+{
+	struct xdr_buf buf;
+
+	if (xdr_buf_subsegment(xdr->buf, &buf, offset, length) < 0)
+		return 0;
+	if (buf.head[0].iov_len)
+		xdr_buf_iov_zero(buf.head, 0, buf.head[0].iov_len);
+	if (buf.page_len > 0)
+		xdr_buf_pages_zero(&buf, 0, buf.page_len);
+	if (buf.tail[0].iov_len)
+		xdr_buf_iov_zero(buf.tail, 0, buf.tail[0].iov_len);
+	return length;
+}
+EXPORT_SYMBOL_GPL(xdr_stream_zero);
+
+/**
+ * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
+ * @buf: buf to be trimmed
+ * @len: number of bytes to reduce "buf" by
+ *
+ * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
+ * that it's possible that we'll trim less than that amount if the xdr_buf is
+ * too small, or if (for instance) it's all in the head and the parser has
+ * already read too far into it.
+ */
+void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
+{
+	size_t cur;
+	unsigned int trim = len;
+
+	if (buf->tail[0].iov_len) {
+		cur = min_t(size_t, buf->tail[0].iov_len, trim);
+		buf->tail[0].iov_len -= cur;
+		trim -= cur;
+		if (!trim)
+			goto fix_len;
+	}
+
+	if (buf->page_len) {
+		cur = min_t(unsigned int, buf->page_len, trim);
+		buf->page_len -= cur;
+		trim -= cur;
+		if (!trim)
+			goto fix_len;
+	}
+
+	if (buf->head[0].iov_len) {
+		cur = min_t(size_t, buf->head[0].iov_len, trim);
+		buf->head[0].iov_len -= cur;
+		trim -= cur;
+	}
+fix_len:
+	buf->len -= (len - trim);
+}
+EXPORT_SYMBOL_GPL(xdr_buf_trim);
+
+static void __read_bytes_from_xdr_buf(const 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);
+	_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(const 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;
+	__read_bytes_from_xdr_buf(&subbuf, obj, len);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
+
+static void __write_bytes_to_xdr_buf(const 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_t(unsigned int, len, subbuf->page_len);
+	_copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
+	len -= this_len;
+	obj += this_len;
+	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
+	memcpy(subbuf->tail[0].iov_base, obj, this_len);
+}
+
+/* obj is assumed to point to allocated memory of size at least len: */
+int write_bytes_to_xdr_buf(const 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;
+}
+EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
+
+int xdr_decode_word(const struct xdr_buf *buf, unsigned int base, u32 *obj)
+{
+	__be32	raw;
+	int	status;
+
+	status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
+	if (status)
+		return status;
+	*obj = be32_to_cpu(raw);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xdr_decode_word);
+
+int xdr_encode_word(const struct xdr_buf *buf, unsigned int base, u32 obj)
+{
+	__be32	raw = cpu_to_be32(obj);
+
+	return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
+}
+EXPORT_SYMBOL_GPL(xdr_encode_word);
+
+/* Returns 0 on success, or else a negative error code. */
+static int xdr_xcode_array2(const 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_SHIFT);
+		base &= ~PAGE_MASK;
+		avail_page = min_t(unsigned int, PAGE_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_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_decode_array2(const struct xdr_buf *buf, unsigned int base,
+		      struct xdr_array2_desc *desc)
+{
+	if (base >= buf->len)
+		return -EINVAL;
+
+	return xdr_xcode_array2(buf, base, desc, 0);
+}
+EXPORT_SYMBOL_GPL(xdr_decode_array2);
+
+int xdr_encode_array2(const 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);
+}
+EXPORT_SYMBOL_GPL(xdr_encode_array2);
+
+int xdr_process_buf(const struct xdr_buf *buf, unsigned int offset,
+		    unsigned int len,
+		    int (*actor)(struct scatterlist *, void *), void *data)
+{
+	int i, ret = 0;
+	unsigned int page_len, thislen, page_offset;
+	struct scatterlist      sg[1];
+
+	sg_init_table(sg, 1);
+
+	if (offset >= buf->head[0].iov_len) {
+		offset -= buf->head[0].iov_len;
+	} else {
+		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_SIZE - 1);
+		i = (offset + buf->page_base) >> PAGE_SHIFT;
+		thislen = PAGE_SIZE - page_offset;
+		do {
+			if (thislen > page_len)
+				thislen = page_len;
+			sg_set_page(sg, buf->pages[i], thislen, page_offset);
+			ret = actor(sg, data);
+			if (ret)
+				goto out;
+			page_len -= thislen;
+			i++;
+			page_offset = 0;
+			thislen = PAGE_SIZE;
+		} while (page_len != 0);
+		offset = 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 ret;
+}
+EXPORT_SYMBOL_GPL(xdr_process_buf);
+
+/**
+ * xdr_stream_decode_opaque - Decode variable length opaque
+ * @xdr: pointer to xdr_stream
+ * @ptr: location to store opaque data
+ * @size: size of storage buffer @ptr
+ *
+ * Return values:
+ *   On success, returns size of object stored in *@ptr
+ *   %-EBADMSG on XDR buffer overflow
+ *   %-EMSGSIZE on overflow of storage buffer @ptr
+ */
+ssize_t xdr_stream_decode_opaque(struct xdr_stream *xdr, void *ptr, size_t size)
+{
+	ssize_t ret;
+	void *p;
+
+	ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
+	if (ret <= 0)
+		return ret;
+	memcpy(ptr, p, ret);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque);
+
+/**
+ * xdr_stream_decode_opaque_dup - Decode and duplicate variable length opaque
+ * @xdr: pointer to xdr_stream
+ * @ptr: location to store pointer to opaque data
+ * @maxlen: maximum acceptable object size
+ * @gfp_flags: GFP mask to use
+ *
+ * Return values:
+ *   On success, returns size of object stored in *@ptr
+ *   %-EBADMSG on XDR buffer overflow
+ *   %-EMSGSIZE if the size of the object would exceed @maxlen
+ *   %-ENOMEM on memory allocation failure
+ */
+ssize_t xdr_stream_decode_opaque_dup(struct xdr_stream *xdr, void **ptr,
+		size_t maxlen, gfp_t gfp_flags)
+{
+	ssize_t ret;
+	void *p;
+
+	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
+	if (ret > 0) {
+		*ptr = kmemdup(p, ret, gfp_flags);
+		if (*ptr != NULL)
+			return ret;
+		ret = -ENOMEM;
+	}
+	*ptr = NULL;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque_dup);
+
+/**
+ * xdr_stream_decode_string - Decode variable length string
+ * @xdr: pointer to xdr_stream
+ * @str: location to store string
+ * @size: size of storage buffer @str
+ *
+ * Return values:
+ *   On success, returns length of NUL-terminated string stored in *@str
+ *   %-EBADMSG on XDR buffer overflow
+ *   %-EMSGSIZE on overflow of storage buffer @str
+ */
+ssize_t xdr_stream_decode_string(struct xdr_stream *xdr, char *str, size_t size)
+{
+	ssize_t ret;
+	void *p;
+
+	ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
+	if (ret > 0) {
+		memcpy(str, p, ret);
+		str[ret] = '\0';
+		return strlen(str);
+	}
+	*str = '\0';
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xdr_stream_decode_string);
+
+/**
+ * xdr_stream_decode_string_dup - Decode and duplicate variable length string
+ * @xdr: pointer to xdr_stream
+ * @str: location to store pointer to string
+ * @maxlen: maximum acceptable string length
+ * @gfp_flags: GFP mask to use
+ *
+ * Return values:
+ *   On success, returns length of NUL-terminated string stored in *@ptr
+ *   %-EBADMSG on XDR buffer overflow
+ *   %-EMSGSIZE if the size of the string would exceed @maxlen
+ *   %-ENOMEM on memory allocation failure
+ */
+ssize_t xdr_stream_decode_string_dup(struct xdr_stream *xdr, char **str,
+		size_t maxlen, gfp_t gfp_flags)
+{
+	void *p;
+	ssize_t ret;
+
+	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
+	if (ret > 0) {
+		char *s = kmemdup_nul(p, ret, gfp_flags);
+		if (s != NULL) {
+			*str = s;
+			return strlen(s);
+		}
+		ret = -ENOMEM;
+	}
+	*str = NULL;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xdr_stream_decode_string_dup);
+
+/**
+ * xdr_stream_decode_opaque_auth - Decode struct opaque_auth (RFC5531 S8.2)
+ * @xdr: pointer to xdr_stream
+ * @flavor: location to store decoded flavor
+ * @body: location to store decode body
+ * @body_len: location to store length of decoded body
+ *
+ * Return values:
+ *   On success, returns the number of buffer bytes consumed
+ *   %-EBADMSG on XDR buffer overflow
+ *   %-EMSGSIZE if the decoded size of the body field exceeds 400 octets
+ */
+ssize_t xdr_stream_decode_opaque_auth(struct xdr_stream *xdr, u32 *flavor,
+				      void **body, unsigned int *body_len)
+{
+	ssize_t ret, len;
+
+	len = xdr_stream_decode_u32(xdr, flavor);
+	if (unlikely(len < 0))
+		return len;
+	ret = xdr_stream_decode_opaque_inline(xdr, body, RPC_MAX_AUTH_SIZE);
+	if (unlikely(ret < 0))
+		return ret;
+	*body_len = ret;
+	return len + ret;
+}
+EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque_auth);
+
+/**
+ * xdr_stream_encode_opaque_auth - Encode struct opaque_auth (RFC5531 S8.2)
+ * @xdr: pointer to xdr_stream
+ * @flavor: verifier flavor to encode
+ * @body: content of body to encode
+ * @body_len: length of body to encode
+ *
+ * Return values:
+ *   On success, returns length in bytes of XDR buffer consumed
+ *   %-EBADMSG on XDR buffer overflow
+ *   %-EMSGSIZE if the size of @body exceeds 400 octets
+ */
+ssize_t xdr_stream_encode_opaque_auth(struct xdr_stream *xdr, u32 flavor,
+				      void *body, unsigned int body_len)
+{
+	ssize_t ret, len;
+
+	if (unlikely(body_len > RPC_MAX_AUTH_SIZE))
+		return -EMSGSIZE;
+	len = xdr_stream_encode_u32(xdr, flavor);
+	if (unlikely(len < 0))
+		return len;
+	ret = xdr_stream_encode_opaque(xdr, body, body_len);
+	if (unlikely(ret < 0))
+		return ret;
+	return len + ret;
+}
+EXPORT_SYMBOL_GPL(xdr_stream_encode_opaque_auth);