diff --git a/lib/Makefile b/lib/Makefile
index 87eb3bf..58f74d2 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -24,7 +24,7 @@ obj-y	+= lockref.o
 
 obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
 	 bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \
-	 gcd.o lcm.o list_sort.o uuid.o flex_array.o clz_ctz.o \
+	 gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \
 	 bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o \
 	 percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o
 obj-y += string_helpers.o
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
new file mode 100644
index 0000000..9d96e283
--- /dev/null
+++ b/lib/iov_iter.c
@@ -0,0 +1,768 @@
+#include <linux/export.h>
+#include <linux/uio.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <net/checksum.h>
+
+#define iterate_iovec(i, n, __v, __p, skip, STEP) {	\
+	size_t left;					\
+	size_t wanted = n;				\
+	__p = i->iov;					\
+	__v.iov_len = min(n, __p->iov_len - skip);	\
+	if (likely(__v.iov_len)) {			\
+		__v.iov_base = __p->iov_base + skip;	\
+		left = (STEP);				\
+		__v.iov_len -= left;			\
+		skip += __v.iov_len;			\
+		n -= __v.iov_len;			\
+	} else {					\
+		left = 0;				\
+	}						\
+	while (unlikely(!left && n)) {			\
+		__p++;					\
+		__v.iov_len = min(n, __p->iov_len);	\
+		if (unlikely(!__v.iov_len))		\
+			continue;			\
+		__v.iov_base = __p->iov_base;		\
+		left = (STEP);				\
+		__v.iov_len -= left;			\
+		skip = __v.iov_len;			\
+		n -= __v.iov_len;			\
+	}						\
+	n = wanted - n;					\
+}
+
+#define iterate_kvec(i, n, __v, __p, skip, STEP) {	\
+	size_t wanted = n;				\
+	__p = i->kvec;					\
+	__v.iov_len = min(n, __p->iov_len - skip);	\
+	if (likely(__v.iov_len)) {			\
+		__v.iov_base = __p->iov_base + skip;	\
+		(void)(STEP);				\
+		skip += __v.iov_len;			\
+		n -= __v.iov_len;			\
+	}						\
+	while (unlikely(n)) {				\
+		__p++;					\
+		__v.iov_len = min(n, __p->iov_len);	\
+		if (unlikely(!__v.iov_len))		\
+			continue;			\
+		__v.iov_base = __p->iov_base;		\
+		(void)(STEP);				\
+		skip = __v.iov_len;			\
+		n -= __v.iov_len;			\
+	}						\
+	n = wanted;					\
+}
+
+#define iterate_bvec(i, n, __v, __p, skip, STEP) {	\
+	size_t wanted = n;				\
+	__p = i->bvec;					\
+	__v.bv_len = min_t(size_t, n, __p->bv_len - skip);	\
+	if (likely(__v.bv_len)) {			\
+		__v.bv_page = __p->bv_page;		\
+		__v.bv_offset = __p->bv_offset + skip; 	\
+		(void)(STEP);				\
+		skip += __v.bv_len;			\
+		n -= __v.bv_len;			\
+	}						\
+	while (unlikely(n)) {				\
+		__p++;					\
+		__v.bv_len = min_t(size_t, n, __p->bv_len);	\
+		if (unlikely(!__v.bv_len))		\
+			continue;			\
+		__v.bv_page = __p->bv_page;		\
+		__v.bv_offset = __p->bv_offset;		\
+		(void)(STEP);				\
+		skip = __v.bv_len;			\
+		n -= __v.bv_len;			\
+	}						\
+	n = wanted;					\
+}
+
+#define iterate_all_kinds(i, n, v, I, B, K) {			\
+	size_t skip = i->iov_offset;				\
+	if (unlikely(i->type & ITER_BVEC)) {			\
+		const struct bio_vec *bvec;			\
+		struct bio_vec v;				\
+		iterate_bvec(i, n, v, bvec, skip, (B))		\
+	} else if (unlikely(i->type & ITER_KVEC)) {		\
+		const struct kvec *kvec;			\
+		struct kvec v;					\
+		iterate_kvec(i, n, v, kvec, skip, (K))		\
+	} else {						\
+		const struct iovec *iov;			\
+		struct iovec v;					\
+		iterate_iovec(i, n, v, iov, skip, (I))		\
+	}							\
+}
+
+#define iterate_and_advance(i, n, v, I, B, K) {			\
+	size_t skip = i->iov_offset;				\
+	if (unlikely(i->type & ITER_BVEC)) {			\
+		const struct bio_vec *bvec;			\
+		struct bio_vec v;				\
+		iterate_bvec(i, n, v, bvec, skip, (B))		\
+		if (skip == bvec->bv_len) {			\
+			bvec++;					\
+			skip = 0;				\
+		}						\
+		i->nr_segs -= bvec - i->bvec;			\
+		i->bvec = bvec;					\
+	} else if (unlikely(i->type & ITER_KVEC)) {		\
+		const struct kvec *kvec;			\
+		struct kvec v;					\
+		iterate_kvec(i, n, v, kvec, skip, (K))		\
+		if (skip == kvec->iov_len) {			\
+			kvec++;					\
+			skip = 0;				\
+		}						\
+		i->nr_segs -= kvec - i->kvec;			\
+		i->kvec = kvec;					\
+	} else {						\
+		const struct iovec *iov;			\
+		struct iovec v;					\
+		iterate_iovec(i, n, v, iov, skip, (I))		\
+		if (skip == iov->iov_len) {			\
+			iov++;					\
+			skip = 0;				\
+		}						\
+		i->nr_segs -= iov - i->iov;			\
+		i->iov = iov;					\
+	}							\
+	i->count -= n;						\
+	i->iov_offset = skip;					\
+}
+
+static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i)
+{
+	size_t skip, copy, left, wanted;
+	const struct iovec *iov;
+	char __user *buf;
+	void *kaddr, *from;
+
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	wanted = bytes;
+	iov = i->iov;
+	skip = i->iov_offset;
+	buf = iov->iov_base + skip;
+	copy = min(bytes, iov->iov_len - skip);
+
+	if (!fault_in_pages_writeable(buf, copy)) {
+		kaddr = kmap_atomic(page);
+		from = kaddr + offset;
+
+		/* first chunk, usually the only one */
+		left = __copy_to_user_inatomic(buf, from, copy);
+		copy -= left;
+		skip += copy;
+		from += copy;
+		bytes -= copy;
+
+		while (unlikely(!left && bytes)) {
+			iov++;
+			buf = iov->iov_base;
+			copy = min(bytes, iov->iov_len);
+			left = __copy_to_user_inatomic(buf, from, copy);
+			copy -= left;
+			skip = copy;
+			from += copy;
+			bytes -= copy;
+		}
+		if (likely(!bytes)) {
+			kunmap_atomic(kaddr);
+			goto done;
+		}
+		offset = from - kaddr;
+		buf += copy;
+		kunmap_atomic(kaddr);
+		copy = min(bytes, iov->iov_len - skip);
+	}
+	/* Too bad - revert to non-atomic kmap */
+	kaddr = kmap(page);
+	from = kaddr + offset;
+	left = __copy_to_user(buf, from, copy);
+	copy -= left;
+	skip += copy;
+	from += copy;
+	bytes -= copy;
+	while (unlikely(!left && bytes)) {
+		iov++;
+		buf = iov->iov_base;
+		copy = min(bytes, iov->iov_len);
+		left = __copy_to_user(buf, from, copy);
+		copy -= left;
+		skip = copy;
+		from += copy;
+		bytes -= copy;
+	}
+	kunmap(page);
+done:
+	if (skip == iov->iov_len) {
+		iov++;
+		skip = 0;
+	}
+	i->count -= wanted - bytes;
+	i->nr_segs -= iov - i->iov;
+	i->iov = iov;
+	i->iov_offset = skip;
+	return wanted - bytes;
+}
+
+static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i)
+{
+	size_t skip, copy, left, wanted;
+	const struct iovec *iov;
+	char __user *buf;
+	void *kaddr, *to;
+
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	wanted = bytes;
+	iov = i->iov;
+	skip = i->iov_offset;
+	buf = iov->iov_base + skip;
+	copy = min(bytes, iov->iov_len - skip);
+
+	if (!fault_in_pages_readable(buf, copy)) {
+		kaddr = kmap_atomic(page);
+		to = kaddr + offset;
+
+		/* first chunk, usually the only one */
+		left = __copy_from_user_inatomic(to, buf, copy);
+		copy -= left;
+		skip += copy;
+		to += copy;
+		bytes -= copy;
+
+		while (unlikely(!left && bytes)) {
+			iov++;
+			buf = iov->iov_base;
+			copy = min(bytes, iov->iov_len);
+			left = __copy_from_user_inatomic(to, buf, copy);
+			copy -= left;
+			skip = copy;
+			to += copy;
+			bytes -= copy;
+		}
+		if (likely(!bytes)) {
+			kunmap_atomic(kaddr);
+			goto done;
+		}
+		offset = to - kaddr;
+		buf += copy;
+		kunmap_atomic(kaddr);
+		copy = min(bytes, iov->iov_len - skip);
+	}
+	/* Too bad - revert to non-atomic kmap */
+	kaddr = kmap(page);
+	to = kaddr + offset;
+	left = __copy_from_user(to, buf, copy);
+	copy -= left;
+	skip += copy;
+	to += copy;
+	bytes -= copy;
+	while (unlikely(!left && bytes)) {
+		iov++;
+		buf = iov->iov_base;
+		copy = min(bytes, iov->iov_len);
+		left = __copy_from_user(to, buf, copy);
+		copy -= left;
+		skip = copy;
+		to += copy;
+		bytes -= copy;
+	}
+	kunmap(page);
+done:
+	if (skip == iov->iov_len) {
+		iov++;
+		skip = 0;
+	}
+	i->count -= wanted - bytes;
+	i->nr_segs -= iov - i->iov;
+	i->iov = iov;
+	i->iov_offset = skip;
+	return wanted - bytes;
+}
+
+/*
+ * Fault in the first iovec of the given iov_iter, to a maximum length
+ * of bytes. Returns 0 on success, or non-zero if the memory could not be
+ * accessed (ie. because it is an invalid address).
+ *
+ * writev-intensive code may want this to prefault several iovecs -- that
+ * would be possible (callers must not rely on the fact that _only_ the
+ * first iovec will be faulted with the current implementation).
+ */
+int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
+{
+	if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
+		char __user *buf = i->iov->iov_base + i->iov_offset;
+		bytes = min(bytes, i->iov->iov_len - i->iov_offset);
+		return fault_in_pages_readable(buf, bytes);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(iov_iter_fault_in_readable);
+
+void iov_iter_init(struct iov_iter *i, int direction,
+			const struct iovec *iov, unsigned long nr_segs,
+			size_t count)
+{
+	/* It will get better.  Eventually... */
+	if (segment_eq(get_fs(), KERNEL_DS)) {
+		direction |= ITER_KVEC;
+		i->type = direction;
+		i->kvec = (struct kvec *)iov;
+	} else {
+		i->type = direction;
+		i->iov = iov;
+	}
+	i->nr_segs = nr_segs;
+	i->iov_offset = 0;
+	i->count = count;
+}
+EXPORT_SYMBOL(iov_iter_init);
+
+static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
+{
+	char *from = kmap_atomic(page);
+	memcpy(to, from + offset, len);
+	kunmap_atomic(from);
+}
+
+static void memcpy_to_page(struct page *page, size_t offset, char *from, size_t len)
+{
+	char *to = kmap_atomic(page);
+	memcpy(to + offset, from, len);
+	kunmap_atomic(to);
+}
+
+static void memzero_page(struct page *page, size_t offset, size_t len)
+{
+	char *addr = kmap_atomic(page);
+	memset(addr + offset, 0, len);
+	kunmap_atomic(addr);
+}
+
+size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i)
+{
+	char *from = addr;
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	iterate_and_advance(i, bytes, v,
+		__copy_to_user(v.iov_base, (from += v.iov_len) - v.iov_len,
+			       v.iov_len),
+		memcpy_to_page(v.bv_page, v.bv_offset,
+			       (from += v.bv_len) - v.bv_len, v.bv_len),
+		memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
+	)
+
+	return bytes;
+}
+EXPORT_SYMBOL(copy_to_iter);
+
+size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
+{
+	char *to = addr;
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	iterate_and_advance(i, bytes, v,
+		__copy_from_user((to += v.iov_len) - v.iov_len, v.iov_base,
+				 v.iov_len),
+		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+				 v.bv_offset, v.bv_len),
+		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+	)
+
+	return bytes;
+}
+EXPORT_SYMBOL(copy_from_iter);
+
+size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
+{
+	char *to = addr;
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	iterate_and_advance(i, bytes, v,
+		__copy_from_user_nocache((to += v.iov_len) - v.iov_len,
+					 v.iov_base, v.iov_len),
+		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+				 v.bv_offset, v.bv_len),
+		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+	)
+
+	return bytes;
+}
+EXPORT_SYMBOL(copy_from_iter_nocache);
+
+size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i)
+{
+	if (i->type & (ITER_BVEC|ITER_KVEC)) {
+		void *kaddr = kmap_atomic(page);
+		size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
+		kunmap_atomic(kaddr);
+		return wanted;
+	} else
+		return copy_page_to_iter_iovec(page, offset, bytes, i);
+}
+EXPORT_SYMBOL(copy_page_to_iter);
+
+size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i)
+{
+	if (i->type & (ITER_BVEC|ITER_KVEC)) {
+		void *kaddr = kmap_atomic(page);
+		size_t wanted = copy_from_iter(kaddr + offset, bytes, i);
+		kunmap_atomic(kaddr);
+		return wanted;
+	} else
+		return copy_page_from_iter_iovec(page, offset, bytes, i);
+}
+EXPORT_SYMBOL(copy_page_from_iter);
+
+size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
+{
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	iterate_and_advance(i, bytes, v,
+		__clear_user(v.iov_base, v.iov_len),
+		memzero_page(v.bv_page, v.bv_offset, v.bv_len),
+		memset(v.iov_base, 0, v.iov_len)
+	)
+
+	return bytes;
+}
+EXPORT_SYMBOL(iov_iter_zero);
+
+size_t iov_iter_copy_from_user_atomic(struct page *page,
+		struct iov_iter *i, unsigned long offset, size_t bytes)
+{
+	char *kaddr = kmap_atomic(page), *p = kaddr + offset;
+	iterate_all_kinds(i, bytes, v,
+		__copy_from_user_inatomic((p += v.iov_len) - v.iov_len,
+					  v.iov_base, v.iov_len),
+		memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
+				 v.bv_offset, v.bv_len),
+		memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+	)
+	kunmap_atomic(kaddr);
+	return bytes;
+}
+EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
+
+void iov_iter_advance(struct iov_iter *i, size_t size)
+{
+	iterate_and_advance(i, size, v, 0, 0, 0)
+}
+EXPORT_SYMBOL(iov_iter_advance);
+
+/*
+ * Return the count of just the current iov_iter segment.
+ */
+size_t iov_iter_single_seg_count(const struct iov_iter *i)
+{
+	if (i->nr_segs == 1)
+		return i->count;
+	else if (i->type & ITER_BVEC)
+		return min(i->count, i->bvec->bv_len - i->iov_offset);
+	else
+		return min(i->count, i->iov->iov_len - i->iov_offset);
+}
+EXPORT_SYMBOL(iov_iter_single_seg_count);
+
+void iov_iter_kvec(struct iov_iter *i, int direction,
+			const struct kvec *kvec, unsigned long nr_segs,
+			size_t count)
+{
+	BUG_ON(!(direction & ITER_KVEC));
+	i->type = direction;
+	i->kvec = kvec;
+	i->nr_segs = nr_segs;
+	i->iov_offset = 0;
+	i->count = count;
+}
+EXPORT_SYMBOL(iov_iter_kvec);
+
+void iov_iter_bvec(struct iov_iter *i, int direction,
+			const struct bio_vec *bvec, unsigned long nr_segs,
+			size_t count)
+{
+	BUG_ON(!(direction & ITER_BVEC));
+	i->type = direction;
+	i->bvec = bvec;
+	i->nr_segs = nr_segs;
+	i->iov_offset = 0;
+	i->count = count;
+}
+EXPORT_SYMBOL(iov_iter_bvec);
+
+unsigned long iov_iter_alignment(const struct iov_iter *i)
+{
+	unsigned long res = 0;
+	size_t size = i->count;
+
+	if (!size)
+		return 0;
+
+	iterate_all_kinds(i, size, v,
+		(res |= (unsigned long)v.iov_base | v.iov_len, 0),
+		res |= v.bv_offset | v.bv_len,
+		res |= (unsigned long)v.iov_base | v.iov_len
+	)
+	return res;
+}
+EXPORT_SYMBOL(iov_iter_alignment);
+
+ssize_t iov_iter_get_pages(struct iov_iter *i,
+		   struct page **pages, size_t maxsize, unsigned maxpages,
+		   size_t *start)
+{
+	if (maxsize > i->count)
+		maxsize = i->count;
+
+	if (!maxsize)
+		return 0;
+
+	iterate_all_kinds(i, maxsize, v, ({
+		unsigned long addr = (unsigned long)v.iov_base;
+		size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
+		int n;
+		int res;
+
+		if (len > maxpages * PAGE_SIZE)
+			len = maxpages * PAGE_SIZE;
+		addr &= ~(PAGE_SIZE - 1);
+		n = DIV_ROUND_UP(len, PAGE_SIZE);
+		res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages);
+		if (unlikely(res < 0))
+			return res;
+		return (res == n ? len : res * PAGE_SIZE) - *start;
+	0;}),({
+		/* can't be more than PAGE_SIZE */
+		*start = v.bv_offset;
+		get_page(*pages = v.bv_page);
+		return v.bv_len;
+	}),({
+		return -EFAULT;
+	})
+	)
+	return 0;
+}
+EXPORT_SYMBOL(iov_iter_get_pages);
+
+static struct page **get_pages_array(size_t n)
+{
+	struct page **p = kmalloc(n * sizeof(struct page *), GFP_KERNEL);
+	if (!p)
+		p = vmalloc(n * sizeof(struct page *));
+	return p;
+}
+
+ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
+		   struct page ***pages, size_t maxsize,
+		   size_t *start)
+{
+	struct page **p;
+
+	if (maxsize > i->count)
+		maxsize = i->count;
+
+	if (!maxsize)
+		return 0;
+
+	iterate_all_kinds(i, maxsize, v, ({
+		unsigned long addr = (unsigned long)v.iov_base;
+		size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
+		int n;
+		int res;
+
+		addr &= ~(PAGE_SIZE - 1);
+		n = DIV_ROUND_UP(len, PAGE_SIZE);
+		p = get_pages_array(n);
+		if (!p)
+			return -ENOMEM;
+		res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
+		if (unlikely(res < 0)) {
+			kvfree(p);
+			return res;
+		}
+		*pages = p;
+		return (res == n ? len : res * PAGE_SIZE) - *start;
+	0;}),({
+		/* can't be more than PAGE_SIZE */
+		*start = v.bv_offset;
+		*pages = p = get_pages_array(1);
+		if (!p)
+			return -ENOMEM;
+		get_page(*p = v.bv_page);
+		return v.bv_len;
+	}),({
+		return -EFAULT;
+	})
+	)
+	return 0;
+}
+EXPORT_SYMBOL(iov_iter_get_pages_alloc);
+
+size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
+			       struct iov_iter *i)
+{
+	char *to = addr;
+	__wsum sum, next;
+	size_t off = 0;
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	sum = *csum;
+	iterate_and_advance(i, bytes, v, ({
+		int err = 0;
+		next = csum_and_copy_from_user(v.iov_base, 
+					       (to += v.iov_len) - v.iov_len,
+					       v.iov_len, 0, &err);
+		if (!err) {
+			sum = csum_block_add(sum, next, off);
+			off += v.iov_len;
+		}
+		err ? v.iov_len : 0;
+	}), ({
+		char *p = kmap_atomic(v.bv_page);
+		next = csum_partial_copy_nocheck(p + v.bv_offset,
+						 (to += v.bv_len) - v.bv_len,
+						 v.bv_len, 0);
+		kunmap_atomic(p);
+		sum = csum_block_add(sum, next, off);
+		off += v.bv_len;
+	}),({
+		next = csum_partial_copy_nocheck(v.iov_base,
+						 (to += v.iov_len) - v.iov_len,
+						 v.iov_len, 0);
+		sum = csum_block_add(sum, next, off);
+		off += v.iov_len;
+	})
+	)
+	*csum = sum;
+	return bytes;
+}
+EXPORT_SYMBOL(csum_and_copy_from_iter);
+
+size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum,
+			     struct iov_iter *i)
+{
+	char *from = addr;
+	__wsum sum, next;
+	size_t off = 0;
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	sum = *csum;
+	iterate_and_advance(i, bytes, v, ({
+		int err = 0;
+		next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
+					     v.iov_base, 
+					     v.iov_len, 0, &err);
+		if (!err) {
+			sum = csum_block_add(sum, next, off);
+			off += v.iov_len;
+		}
+		err ? v.iov_len : 0;
+	}), ({
+		char *p = kmap_atomic(v.bv_page);
+		next = csum_partial_copy_nocheck((from += v.bv_len) - v.bv_len,
+						 p + v.bv_offset,
+						 v.bv_len, 0);
+		kunmap_atomic(p);
+		sum = csum_block_add(sum, next, off);
+		off += v.bv_len;
+	}),({
+		next = csum_partial_copy_nocheck((from += v.iov_len) - v.iov_len,
+						 v.iov_base,
+						 v.iov_len, 0);
+		sum = csum_block_add(sum, next, off);
+		off += v.iov_len;
+	})
+	)
+	*csum = sum;
+	return bytes;
+}
+EXPORT_SYMBOL(csum_and_copy_to_iter);
+
+int iov_iter_npages(const struct iov_iter *i, int maxpages)
+{
+	size_t size = i->count;
+	int npages = 0;
+
+	if (!size)
+		return 0;
+
+	iterate_all_kinds(i, size, v, ({
+		unsigned long p = (unsigned long)v.iov_base;
+		npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
+			- p / PAGE_SIZE;
+		if (npages >= maxpages)
+			return maxpages;
+	0;}),({
+		npages++;
+		if (npages >= maxpages)
+			return maxpages;
+	}),({
+		unsigned long p = (unsigned long)v.iov_base;
+		npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
+			- p / PAGE_SIZE;
+		if (npages >= maxpages)
+			return maxpages;
+	})
+	)
+	return npages;
+}
+EXPORT_SYMBOL(iov_iter_npages);
+
+const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
+{
+	*new = *old;
+	if (new->type & ITER_BVEC)
+		return new->bvec = kmemdup(new->bvec,
+				    new->nr_segs * sizeof(struct bio_vec),
+				    flags);
+	else
+		/* iovec and kvec have identical layout */
+		return new->iov = kmemdup(new->iov,
+				   new->nr_segs * sizeof(struct iovec),
+				   flags);
+}
+EXPORT_SYMBOL(dup_iter);
diff --git a/mm/Makefile b/mm/Makefile
index 3c1caa2..15dbe99 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -21,7 +21,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o \
 			   mm_init.o mmu_context.o percpu.o slab_common.o \
 			   compaction.o vmacache.o \
 			   interval_tree.o list_lru.o workingset.o \
-			   iov_iter.o debug.o $(mmu-y)
+			   debug.o $(mmu-y)
 
 obj-y += init-mm.o
 
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
deleted file mode 100644
index 9d96e283..0000000
--- a/mm/iov_iter.c
+++ /dev/null
@@ -1,768 +0,0 @@
-#include <linux/export.h>
-#include <linux/uio.h>
-#include <linux/pagemap.h>
-#include <linux/slab.h>
-#include <linux/vmalloc.h>
-#include <net/checksum.h>
-
-#define iterate_iovec(i, n, __v, __p, skip, STEP) {	\
-	size_t left;					\
-	size_t wanted = n;				\
-	__p = i->iov;					\
-	__v.iov_len = min(n, __p->iov_len - skip);	\
-	if (likely(__v.iov_len)) {			\
-		__v.iov_base = __p->iov_base + skip;	\
-		left = (STEP);				\
-		__v.iov_len -= left;			\
-		skip += __v.iov_len;			\
-		n -= __v.iov_len;			\
-	} else {					\
-		left = 0;				\
-	}						\
-	while (unlikely(!left && n)) {			\
-		__p++;					\
-		__v.iov_len = min(n, __p->iov_len);	\
-		if (unlikely(!__v.iov_len))		\
-			continue;			\
-		__v.iov_base = __p->iov_base;		\
-		left = (STEP);				\
-		__v.iov_len -= left;			\
-		skip = __v.iov_len;			\
-		n -= __v.iov_len;			\
-	}						\
-	n = wanted - n;					\
-}
-
-#define iterate_kvec(i, n, __v, __p, skip, STEP) {	\
-	size_t wanted = n;				\
-	__p = i->kvec;					\
-	__v.iov_len = min(n, __p->iov_len - skip);	\
-	if (likely(__v.iov_len)) {			\
-		__v.iov_base = __p->iov_base + skip;	\
-		(void)(STEP);				\
-		skip += __v.iov_len;			\
-		n -= __v.iov_len;			\
-	}						\
-	while (unlikely(n)) {				\
-		__p++;					\
-		__v.iov_len = min(n, __p->iov_len);	\
-		if (unlikely(!__v.iov_len))		\
-			continue;			\
-		__v.iov_base = __p->iov_base;		\
-		(void)(STEP);				\
-		skip = __v.iov_len;			\
-		n -= __v.iov_len;			\
-	}						\
-	n = wanted;					\
-}
-
-#define iterate_bvec(i, n, __v, __p, skip, STEP) {	\
-	size_t wanted = n;				\
-	__p = i->bvec;					\
-	__v.bv_len = min_t(size_t, n, __p->bv_len - skip);	\
-	if (likely(__v.bv_len)) {			\
-		__v.bv_page = __p->bv_page;		\
-		__v.bv_offset = __p->bv_offset + skip; 	\
-		(void)(STEP);				\
-		skip += __v.bv_len;			\
-		n -= __v.bv_len;			\
-	}						\
-	while (unlikely(n)) {				\
-		__p++;					\
-		__v.bv_len = min_t(size_t, n, __p->bv_len);	\
-		if (unlikely(!__v.bv_len))		\
-			continue;			\
-		__v.bv_page = __p->bv_page;		\
-		__v.bv_offset = __p->bv_offset;		\
-		(void)(STEP);				\
-		skip = __v.bv_len;			\
-		n -= __v.bv_len;			\
-	}						\
-	n = wanted;					\
-}
-
-#define iterate_all_kinds(i, n, v, I, B, K) {			\
-	size_t skip = i->iov_offset;				\
-	if (unlikely(i->type & ITER_BVEC)) {			\
-		const struct bio_vec *bvec;			\
-		struct bio_vec v;				\
-		iterate_bvec(i, n, v, bvec, skip, (B))		\
-	} else if (unlikely(i->type & ITER_KVEC)) {		\
-		const struct kvec *kvec;			\
-		struct kvec v;					\
-		iterate_kvec(i, n, v, kvec, skip, (K))		\
-	} else {						\
-		const struct iovec *iov;			\
-		struct iovec v;					\
-		iterate_iovec(i, n, v, iov, skip, (I))		\
-	}							\
-}
-
-#define iterate_and_advance(i, n, v, I, B, K) {			\
-	size_t skip = i->iov_offset;				\
-	if (unlikely(i->type & ITER_BVEC)) {			\
-		const struct bio_vec *bvec;			\
-		struct bio_vec v;				\
-		iterate_bvec(i, n, v, bvec, skip, (B))		\
-		if (skip == bvec->bv_len) {			\
-			bvec++;					\
-			skip = 0;				\
-		}						\
-		i->nr_segs -= bvec - i->bvec;			\
-		i->bvec = bvec;					\
-	} else if (unlikely(i->type & ITER_KVEC)) {		\
-		const struct kvec *kvec;			\
-		struct kvec v;					\
-		iterate_kvec(i, n, v, kvec, skip, (K))		\
-		if (skip == kvec->iov_len) {			\
-			kvec++;					\
-			skip = 0;				\
-		}						\
-		i->nr_segs -= kvec - i->kvec;			\
-		i->kvec = kvec;					\
-	} else {						\
-		const struct iovec *iov;			\
-		struct iovec v;					\
-		iterate_iovec(i, n, v, iov, skip, (I))		\
-		if (skip == iov->iov_len) {			\
-			iov++;					\
-			skip = 0;				\
-		}						\
-		i->nr_segs -= iov - i->iov;			\
-		i->iov = iov;					\
-	}							\
-	i->count -= n;						\
-	i->iov_offset = skip;					\
-}
-
-static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
-			 struct iov_iter *i)
-{
-	size_t skip, copy, left, wanted;
-	const struct iovec *iov;
-	char __user *buf;
-	void *kaddr, *from;
-
-	if (unlikely(bytes > i->count))
-		bytes = i->count;
-
-	if (unlikely(!bytes))
-		return 0;
-
-	wanted = bytes;
-	iov = i->iov;
-	skip = i->iov_offset;
-	buf = iov->iov_base + skip;
-	copy = min(bytes, iov->iov_len - skip);
-
-	if (!fault_in_pages_writeable(buf, copy)) {
-		kaddr = kmap_atomic(page);
-		from = kaddr + offset;
-
-		/* first chunk, usually the only one */
-		left = __copy_to_user_inatomic(buf, from, copy);
-		copy -= left;
-		skip += copy;
-		from += copy;
-		bytes -= copy;
-
-		while (unlikely(!left && bytes)) {
-			iov++;
-			buf = iov->iov_base;
-			copy = min(bytes, iov->iov_len);
-			left = __copy_to_user_inatomic(buf, from, copy);
-			copy -= left;
-			skip = copy;
-			from += copy;
-			bytes -= copy;
-		}
-		if (likely(!bytes)) {
-			kunmap_atomic(kaddr);
-			goto done;
-		}
-		offset = from - kaddr;
-		buf += copy;
-		kunmap_atomic(kaddr);
-		copy = min(bytes, iov->iov_len - skip);
-	}
-	/* Too bad - revert to non-atomic kmap */
-	kaddr = kmap(page);
-	from = kaddr + offset;
-	left = __copy_to_user(buf, from, copy);
-	copy -= left;
-	skip += copy;
-	from += copy;
-	bytes -= copy;
-	while (unlikely(!left && bytes)) {
-		iov++;
-		buf = iov->iov_base;
-		copy = min(bytes, iov->iov_len);
-		left = __copy_to_user(buf, from, copy);
-		copy -= left;
-		skip = copy;
-		from += copy;
-		bytes -= copy;
-	}
-	kunmap(page);
-done:
-	if (skip == iov->iov_len) {
-		iov++;
-		skip = 0;
-	}
-	i->count -= wanted - bytes;
-	i->nr_segs -= iov - i->iov;
-	i->iov = iov;
-	i->iov_offset = skip;
-	return wanted - bytes;
-}
-
-static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
-			 struct iov_iter *i)
-{
-	size_t skip, copy, left, wanted;
-	const struct iovec *iov;
-	char __user *buf;
-	void *kaddr, *to;
-
-	if (unlikely(bytes > i->count))
-		bytes = i->count;
-
-	if (unlikely(!bytes))
-		return 0;
-
-	wanted = bytes;
-	iov = i->iov;
-	skip = i->iov_offset;
-	buf = iov->iov_base + skip;
-	copy = min(bytes, iov->iov_len - skip);
-
-	if (!fault_in_pages_readable(buf, copy)) {
-		kaddr = kmap_atomic(page);
-		to = kaddr + offset;
-
-		/* first chunk, usually the only one */
-		left = __copy_from_user_inatomic(to, buf, copy);
-		copy -= left;
-		skip += copy;
-		to += copy;
-		bytes -= copy;
-
-		while (unlikely(!left && bytes)) {
-			iov++;
-			buf = iov->iov_base;
-			copy = min(bytes, iov->iov_len);
-			left = __copy_from_user_inatomic(to, buf, copy);
-			copy -= left;
-			skip = copy;
-			to += copy;
-			bytes -= copy;
-		}
-		if (likely(!bytes)) {
-			kunmap_atomic(kaddr);
-			goto done;
-		}
-		offset = to - kaddr;
-		buf += copy;
-		kunmap_atomic(kaddr);
-		copy = min(bytes, iov->iov_len - skip);
-	}
-	/* Too bad - revert to non-atomic kmap */
-	kaddr = kmap(page);
-	to = kaddr + offset;
-	left = __copy_from_user(to, buf, copy);
-	copy -= left;
-	skip += copy;
-	to += copy;
-	bytes -= copy;
-	while (unlikely(!left && bytes)) {
-		iov++;
-		buf = iov->iov_base;
-		copy = min(bytes, iov->iov_len);
-		left = __copy_from_user(to, buf, copy);
-		copy -= left;
-		skip = copy;
-		to += copy;
-		bytes -= copy;
-	}
-	kunmap(page);
-done:
-	if (skip == iov->iov_len) {
-		iov++;
-		skip = 0;
-	}
-	i->count -= wanted - bytes;
-	i->nr_segs -= iov - i->iov;
-	i->iov = iov;
-	i->iov_offset = skip;
-	return wanted - bytes;
-}
-
-/*
- * Fault in the first iovec of the given iov_iter, to a maximum length
- * of bytes. Returns 0 on success, or non-zero if the memory could not be
- * accessed (ie. because it is an invalid address).
- *
- * writev-intensive code may want this to prefault several iovecs -- that
- * would be possible (callers must not rely on the fact that _only_ the
- * first iovec will be faulted with the current implementation).
- */
-int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
-{
-	if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
-		char __user *buf = i->iov->iov_base + i->iov_offset;
-		bytes = min(bytes, i->iov->iov_len - i->iov_offset);
-		return fault_in_pages_readable(buf, bytes);
-	}
-	return 0;
-}
-EXPORT_SYMBOL(iov_iter_fault_in_readable);
-
-void iov_iter_init(struct iov_iter *i, int direction,
-			const struct iovec *iov, unsigned long nr_segs,
-			size_t count)
-{
-	/* It will get better.  Eventually... */
-	if (segment_eq(get_fs(), KERNEL_DS)) {
-		direction |= ITER_KVEC;
-		i->type = direction;
-		i->kvec = (struct kvec *)iov;
-	} else {
-		i->type = direction;
-		i->iov = iov;
-	}
-	i->nr_segs = nr_segs;
-	i->iov_offset = 0;
-	i->count = count;
-}
-EXPORT_SYMBOL(iov_iter_init);
-
-static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
-{
-	char *from = kmap_atomic(page);
-	memcpy(to, from + offset, len);
-	kunmap_atomic(from);
-}
-
-static void memcpy_to_page(struct page *page, size_t offset, char *from, size_t len)
-{
-	char *to = kmap_atomic(page);
-	memcpy(to + offset, from, len);
-	kunmap_atomic(to);
-}
-
-static void memzero_page(struct page *page, size_t offset, size_t len)
-{
-	char *addr = kmap_atomic(page);
-	memset(addr + offset, 0, len);
-	kunmap_atomic(addr);
-}
-
-size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i)
-{
-	char *from = addr;
-	if (unlikely(bytes > i->count))
-		bytes = i->count;
-
-	if (unlikely(!bytes))
-		return 0;
-
-	iterate_and_advance(i, bytes, v,
-		__copy_to_user(v.iov_base, (from += v.iov_len) - v.iov_len,
-			       v.iov_len),
-		memcpy_to_page(v.bv_page, v.bv_offset,
-			       (from += v.bv_len) - v.bv_len, v.bv_len),
-		memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
-	)
-
-	return bytes;
-}
-EXPORT_SYMBOL(copy_to_iter);
-
-size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
-{
-	char *to = addr;
-	if (unlikely(bytes > i->count))
-		bytes = i->count;
-
-	if (unlikely(!bytes))
-		return 0;
-
-	iterate_and_advance(i, bytes, v,
-		__copy_from_user((to += v.iov_len) - v.iov_len, v.iov_base,
-				 v.iov_len),
-		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
-				 v.bv_offset, v.bv_len),
-		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
-	)
-
-	return bytes;
-}
-EXPORT_SYMBOL(copy_from_iter);
-
-size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
-{
-	char *to = addr;
-	if (unlikely(bytes > i->count))
-		bytes = i->count;
-
-	if (unlikely(!bytes))
-		return 0;
-
-	iterate_and_advance(i, bytes, v,
-		__copy_from_user_nocache((to += v.iov_len) - v.iov_len,
-					 v.iov_base, v.iov_len),
-		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
-				 v.bv_offset, v.bv_len),
-		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
-	)
-
-	return bytes;
-}
-EXPORT_SYMBOL(copy_from_iter_nocache);
-
-size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
-			 struct iov_iter *i)
-{
-	if (i->type & (ITER_BVEC|ITER_KVEC)) {
-		void *kaddr = kmap_atomic(page);
-		size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
-		kunmap_atomic(kaddr);
-		return wanted;
-	} else
-		return copy_page_to_iter_iovec(page, offset, bytes, i);
-}
-EXPORT_SYMBOL(copy_page_to_iter);
-
-size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
-			 struct iov_iter *i)
-{
-	if (i->type & (ITER_BVEC|ITER_KVEC)) {
-		void *kaddr = kmap_atomic(page);
-		size_t wanted = copy_from_iter(kaddr + offset, bytes, i);
-		kunmap_atomic(kaddr);
-		return wanted;
-	} else
-		return copy_page_from_iter_iovec(page, offset, bytes, i);
-}
-EXPORT_SYMBOL(copy_page_from_iter);
-
-size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
-{
-	if (unlikely(bytes > i->count))
-		bytes = i->count;
-
-	if (unlikely(!bytes))
-		return 0;
-
-	iterate_and_advance(i, bytes, v,
-		__clear_user(v.iov_base, v.iov_len),
-		memzero_page(v.bv_page, v.bv_offset, v.bv_len),
-		memset(v.iov_base, 0, v.iov_len)
-	)
-
-	return bytes;
-}
-EXPORT_SYMBOL(iov_iter_zero);
-
-size_t iov_iter_copy_from_user_atomic(struct page *page,
-		struct iov_iter *i, unsigned long offset, size_t bytes)
-{
-	char *kaddr = kmap_atomic(page), *p = kaddr + offset;
-	iterate_all_kinds(i, bytes, v,
-		__copy_from_user_inatomic((p += v.iov_len) - v.iov_len,
-					  v.iov_base, v.iov_len),
-		memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
-				 v.bv_offset, v.bv_len),
-		memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
-	)
-	kunmap_atomic(kaddr);
-	return bytes;
-}
-EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
-
-void iov_iter_advance(struct iov_iter *i, size_t size)
-{
-	iterate_and_advance(i, size, v, 0, 0, 0)
-}
-EXPORT_SYMBOL(iov_iter_advance);
-
-/*
- * Return the count of just the current iov_iter segment.
- */
-size_t iov_iter_single_seg_count(const struct iov_iter *i)
-{
-	if (i->nr_segs == 1)
-		return i->count;
-	else if (i->type & ITER_BVEC)
-		return min(i->count, i->bvec->bv_len - i->iov_offset);
-	else
-		return min(i->count, i->iov->iov_len - i->iov_offset);
-}
-EXPORT_SYMBOL(iov_iter_single_seg_count);
-
-void iov_iter_kvec(struct iov_iter *i, int direction,
-			const struct kvec *kvec, unsigned long nr_segs,
-			size_t count)
-{
-	BUG_ON(!(direction & ITER_KVEC));
-	i->type = direction;
-	i->kvec = kvec;
-	i->nr_segs = nr_segs;
-	i->iov_offset = 0;
-	i->count = count;
-}
-EXPORT_SYMBOL(iov_iter_kvec);
-
-void iov_iter_bvec(struct iov_iter *i, int direction,
-			const struct bio_vec *bvec, unsigned long nr_segs,
-			size_t count)
-{
-	BUG_ON(!(direction & ITER_BVEC));
-	i->type = direction;
-	i->bvec = bvec;
-	i->nr_segs = nr_segs;
-	i->iov_offset = 0;
-	i->count = count;
-}
-EXPORT_SYMBOL(iov_iter_bvec);
-
-unsigned long iov_iter_alignment(const struct iov_iter *i)
-{
-	unsigned long res = 0;
-	size_t size = i->count;
-
-	if (!size)
-		return 0;
-
-	iterate_all_kinds(i, size, v,
-		(res |= (unsigned long)v.iov_base | v.iov_len, 0),
-		res |= v.bv_offset | v.bv_len,
-		res |= (unsigned long)v.iov_base | v.iov_len
-	)
-	return res;
-}
-EXPORT_SYMBOL(iov_iter_alignment);
-
-ssize_t iov_iter_get_pages(struct iov_iter *i,
-		   struct page **pages, size_t maxsize, unsigned maxpages,
-		   size_t *start)
-{
-	if (maxsize > i->count)
-		maxsize = i->count;
-
-	if (!maxsize)
-		return 0;
-
-	iterate_all_kinds(i, maxsize, v, ({
-		unsigned long addr = (unsigned long)v.iov_base;
-		size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
-		int n;
-		int res;
-
-		if (len > maxpages * PAGE_SIZE)
-			len = maxpages * PAGE_SIZE;
-		addr &= ~(PAGE_SIZE - 1);
-		n = DIV_ROUND_UP(len, PAGE_SIZE);
-		res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages);
-		if (unlikely(res < 0))
-			return res;
-		return (res == n ? len : res * PAGE_SIZE) - *start;
-	0;}),({
-		/* can't be more than PAGE_SIZE */
-		*start = v.bv_offset;
-		get_page(*pages = v.bv_page);
-		return v.bv_len;
-	}),({
-		return -EFAULT;
-	})
-	)
-	return 0;
-}
-EXPORT_SYMBOL(iov_iter_get_pages);
-
-static struct page **get_pages_array(size_t n)
-{
-	struct page **p = kmalloc(n * sizeof(struct page *), GFP_KERNEL);
-	if (!p)
-		p = vmalloc(n * sizeof(struct page *));
-	return p;
-}
-
-ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
-		   struct page ***pages, size_t maxsize,
-		   size_t *start)
-{
-	struct page **p;
-
-	if (maxsize > i->count)
-		maxsize = i->count;
-
-	if (!maxsize)
-		return 0;
-
-	iterate_all_kinds(i, maxsize, v, ({
-		unsigned long addr = (unsigned long)v.iov_base;
-		size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
-		int n;
-		int res;
-
-		addr &= ~(PAGE_SIZE - 1);
-		n = DIV_ROUND_UP(len, PAGE_SIZE);
-		p = get_pages_array(n);
-		if (!p)
-			return -ENOMEM;
-		res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
-		if (unlikely(res < 0)) {
-			kvfree(p);
-			return res;
-		}
-		*pages = p;
-		return (res == n ? len : res * PAGE_SIZE) - *start;
-	0;}),({
-		/* can't be more than PAGE_SIZE */
-		*start = v.bv_offset;
-		*pages = p = get_pages_array(1);
-		if (!p)
-			return -ENOMEM;
-		get_page(*p = v.bv_page);
-		return v.bv_len;
-	}),({
-		return -EFAULT;
-	})
-	)
-	return 0;
-}
-EXPORT_SYMBOL(iov_iter_get_pages_alloc);
-
-size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
-			       struct iov_iter *i)
-{
-	char *to = addr;
-	__wsum sum, next;
-	size_t off = 0;
-	if (unlikely(bytes > i->count))
-		bytes = i->count;
-
-	if (unlikely(!bytes))
-		return 0;
-
-	sum = *csum;
-	iterate_and_advance(i, bytes, v, ({
-		int err = 0;
-		next = csum_and_copy_from_user(v.iov_base, 
-					       (to += v.iov_len) - v.iov_len,
-					       v.iov_len, 0, &err);
-		if (!err) {
-			sum = csum_block_add(sum, next, off);
-			off += v.iov_len;
-		}
-		err ? v.iov_len : 0;
-	}), ({
-		char *p = kmap_atomic(v.bv_page);
-		next = csum_partial_copy_nocheck(p + v.bv_offset,
-						 (to += v.bv_len) - v.bv_len,
-						 v.bv_len, 0);
-		kunmap_atomic(p);
-		sum = csum_block_add(sum, next, off);
-		off += v.bv_len;
-	}),({
-		next = csum_partial_copy_nocheck(v.iov_base,
-						 (to += v.iov_len) - v.iov_len,
-						 v.iov_len, 0);
-		sum = csum_block_add(sum, next, off);
-		off += v.iov_len;
-	})
-	)
-	*csum = sum;
-	return bytes;
-}
-EXPORT_SYMBOL(csum_and_copy_from_iter);
-
-size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum,
-			     struct iov_iter *i)
-{
-	char *from = addr;
-	__wsum sum, next;
-	size_t off = 0;
-	if (unlikely(bytes > i->count))
-		bytes = i->count;
-
-	if (unlikely(!bytes))
-		return 0;
-
-	sum = *csum;
-	iterate_and_advance(i, bytes, v, ({
-		int err = 0;
-		next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
-					     v.iov_base, 
-					     v.iov_len, 0, &err);
-		if (!err) {
-			sum = csum_block_add(sum, next, off);
-			off += v.iov_len;
-		}
-		err ? v.iov_len : 0;
-	}), ({
-		char *p = kmap_atomic(v.bv_page);
-		next = csum_partial_copy_nocheck((from += v.bv_len) - v.bv_len,
-						 p + v.bv_offset,
-						 v.bv_len, 0);
-		kunmap_atomic(p);
-		sum = csum_block_add(sum, next, off);
-		off += v.bv_len;
-	}),({
-		next = csum_partial_copy_nocheck((from += v.iov_len) - v.iov_len,
-						 v.iov_base,
-						 v.iov_len, 0);
-		sum = csum_block_add(sum, next, off);
-		off += v.iov_len;
-	})
-	)
-	*csum = sum;
-	return bytes;
-}
-EXPORT_SYMBOL(csum_and_copy_to_iter);
-
-int iov_iter_npages(const struct iov_iter *i, int maxpages)
-{
-	size_t size = i->count;
-	int npages = 0;
-
-	if (!size)
-		return 0;
-
-	iterate_all_kinds(i, size, v, ({
-		unsigned long p = (unsigned long)v.iov_base;
-		npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
-			- p / PAGE_SIZE;
-		if (npages >= maxpages)
-			return maxpages;
-	0;}),({
-		npages++;
-		if (npages >= maxpages)
-			return maxpages;
-	}),({
-		unsigned long p = (unsigned long)v.iov_base;
-		npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
-			- p / PAGE_SIZE;
-		if (npages >= maxpages)
-			return maxpages;
-	})
-	)
-	return npages;
-}
-EXPORT_SYMBOL(iov_iter_npages);
-
-const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
-{
-	*new = *old;
-	if (new->type & ITER_BVEC)
-		return new->bvec = kmemdup(new->bvec,
-				    new->nr_segs * sizeof(struct bio_vec),
-				    flags);
-	else
-		/* iovec and kvec have identical layout */
-		return new->iov = kmemdup(new->iov,
-				   new->nr_segs * sizeof(struct iovec),
-				   flags);
-}
-EXPORT_SYMBOL(dup_iter);
