backports: bluetooth: Support 4.9 kernels

Signed-off-by: Dominik Sliwa <dominik.sliwa@toradex.com>

9 files changed, 1703 insertions, 1 deletions

diff --git a/compat/Kconfig b/compat/Kconfig
index f28b24c..1660136 100644
--- a/compat/Kconfig
+++ b/compat/Kconfig
@@ -113,6 +113,12 @@ config BPAUTO_CRYPTO_SKCIPHER
 	#c-file crypto/skcipher.c
 	#module-name skcipher
 
+config BPAUTO_CRYPTO_KPP2
+    tristate
+    depends on m
+    depends on KERNEL_4_7
+    default y if BACKPORTED_BT
+
 config BPAUTO_WANT_DEV_COREDUMP
 	bool
 
@@ -175,6 +181,12 @@ config BPAUTO_REFCOUNT
 	#h-file linux/refcount.h
 	#c-file lib/refcount.c
 
+config BPAUTO_IOV_ITER
+	bool
+	default y
+	depends on !KERNEL_4_6
+	#c-file lib/iov_iter.c
+
 config BPAUTO_SYSTEM_DATA_VERIFICATION
 	bool
 
diff --git a/compat/Makefile b/compat/Makefile
index cabfcdc..d198c2c 100644
--- a/compat/Makefile
+++ b/compat/Makefile
@@ -60,6 +60,8 @@ compat-$(CPTCFG_BPAUTO_BUILD_SYSTEM_DATA_VERIFICATION) += verification/oid.o
 compat-$(CPTCFG_BPAUTO_BUILD_SYSTEM_DATA_VERIFICATION) += verification/asn1parse.o
 compat-$(CPTCFG_BPAUTO_BUILD_SYSTEM_DATA_VERIFICATION) += verification/rsapubkey.asn1.o
 
+kpp-objs += crypto-kpp.o
+obj-$(CPTCFG_BPAUTO_CRYPTO_KPP2) += kpp.o
 $(obj)/lib-oid_registry.o: $(obj)/oid_registry_data.c
 
 $(obj)/oid_registry_data.c: $(src)/../include/linux/backport-oid_registry.h \
@@ -76,6 +78,7 @@ compat-$(CPTCFG_BPAUTO_BUILD_WANT_DEV_COREDUMP) += drivers-base-devcoredump.o
 compat-$(CPTCFG_BPAUTO_RHASHTABLE) += lib-rhashtable.o
 cordic-objs += lib-cordic.o
 obj-$(CPTCFG_BPAUTO_BUILD_CORDIC) += cordic.o
+compat-$(CPTCFG_BPAUTO_IOV_ITER) += lib-iov_iter.o
 compat-$(CPTCFG_BPAUTO_PUBLIC_KEY) += 
 compat-$(CPTCFG_BPAUTO_BUCKET_LOCKS) += lib-bucket_locks.o
 compat-$(CPTCFG_BPAUTO_PKCS7) += 
diff --git a/compat/backport-4.0.c b/compat/backport-4.0.c
index eb95082..7f86c69 100644
--- a/compat/backport-4.0.c
+++ b/compat/backport-4.0.c
@@ -17,6 +17,7 @@
 #include <linux/trace_seq.h>
 #include <linux/ftrace_event.h>
 #include <asm/unaligned.h>
+#include <linux/slab.h>
 
 static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 						struct mm_struct *mm,
@@ -375,3 +376,35 @@ ftrace_print_array_seq(struct trace_seq *p, const void *buf, int buf_len,
 	return ret;
 }
 EXPORT_SYMBOL(ftrace_print_array_seq);
+
+/**
+ * kfree_const - conditionally free memory
+ * @x: pointer to the memory
+ *
+ * Function calls kfree only if @x is not in .rodata section.
+ */
+void kfree_const(const void *x)
+{
+	/* if (!is_kernel_rodata((unsigned long)x)) */
+		kfree(x);
+}
+EXPORT_SYMBOL(kfree_const);
+
+/*
+* kstrdup_const - conditionally duplicate an existing const string
+* @s: the string to duplicate
+* @gfp: the GFP mask used in the kmalloc() call when allocating memory
+*
+* Function returns source string if it is in .rodata section otherwise it
+* fallbacks to kstrdup.
+* Strings allocated by kstrdup_const should be freed by kfree_const.
+*/
+
+const char *kstrdup_const(const char *s, gfp_t gfp)
+{
+/*       if (is_kernel_rodata((unsigned long)s))
+ *             return s;
+ */
+       return kstrdup(s, gfp);
+}
+EXPORT_SYMBOL(kstrdup_const);
diff --git a/compat/backport-4.10.c b/compat/backport-4.10.c
index 44e02dd..97d152b 100644
--- a/compat/backport-4.10.c
+++ b/compat/backport-4.10.c
@@ -251,4 +251,41 @@ int mii_ethtool_get_link_ksettings(struct mii_if_info *mii,
 	return 0;
 }
 EXPORT_SYMBOL(mii_ethtool_get_link_ksettings);
+
+void *kvmalloc_node(size_t size, gfp_t flags, int node)
+{
+	gfp_t kmalloc_flags = flags;
+	void *ret;
+
+	/*
+	 * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
+	 * so the given set of flags has to be compatible.
+	 */
+	WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL);
+
+	/*
+	 * We want to attempt a large physically contiguous block first because
+	 * it is less likely to fragment multiple larger blocks and therefore
+	 * contribute to a long term fragmentation less than vmalloc fallback.
+	 * However make sure that larger requests are not too disruptive - no
+	 * OOM killer and no allocation failure warnings as we have a fallback.
+	 */
+	if (size > PAGE_SIZE) {
+		kmalloc_flags |= __GFP_NOWARN;
+		kmalloc_flags |= __GFP_NORETRY;
+	}
+
+	ret = kmalloc_node(size, kmalloc_flags, node);
+
+	/*
+	 * It doesn't really make sense to fallback to vmalloc for sub page
+	 * requests
+	 */
+	if (ret || size <= PAGE_SIZE)
+		return ret;
+
+	return vmalloc(size);
+}
+EXPORT_SYMBOL(kvmalloc_node);
+
 #endif /* LINUX_VERSION_IS_GEQ(4,6,0) */
diff --git a/compat/backport-4.12.c b/compat/backport-4.12.c
index 2c0053f..8f3e5ab 100644
--- a/compat/backport-4.12.c
+++ b/compat/backport-4.12.c
@@ -3,6 +3,9 @@
  */
 #include <net/genetlink.h>
 #include <net/sock.h>
+#ifdef CONFIG_OF
+#include <linux/of_device.h>
+#endif
 
 enum nlmsgerr_attrs {
 	NLMSGERR_ATTR_UNUSED,
@@ -275,3 +278,22 @@ int bp_extack_genl_unregister_family(struct genl_family *family)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(bp_extack_genl_unregister_family);
+
+#ifdef CONFIG_OF
+/**
+ * of_device_modalias - Fill buffer with newline terminated modalias string
+ */
+ssize_t bp_of_device_modalias(struct device *dev, char *str, ssize_t len)
+{
+	ssize_t sl = of_device_get_modalias(dev, str, len - 2);
+	if (sl < 0)
+		return sl;
+	if (sl > len - 2)
+		return -ENOMEM;
+
+	str[sl++] = '\n';
+	str[sl] = 0;
+	return sl;
+}
+EXPORT_SYMBOL_GPL(bp_of_device_modalias);
+#endif
diff --git a/compat/backport-4.4.c b/compat/backport-4.4.c
index 1c11a20..660d50b 100644
--- a/compat/backport-4.4.c
+++ b/compat/backport-4.4.c
@@ -152,3 +152,14 @@ void tso_start(struct sk_buff *skb, struct tso_t *tso)
 	}
 }
 EXPORT_SYMBOL(tso_start);
+
+const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list ap)
+{
+	if (!strchr(fmt, '%'))
+		return kstrdup_const(fmt, gfp);
+	if (!strcmp(fmt, "%s"))
+		return kstrdup_const(va_arg(ap, const char*), gfp);
+	return kvasprintf(gfp, fmt, ap);
+}
+EXPORT_SYMBOL(kvasprintf_const);
+
diff --git a/compat/crypto-kpp.c b/compat/crypto-kpp.c
new file mode 100644
index 0000000..ae11fa8
--- /dev/null
+++ b/compat/crypto-kpp.c
@@ -0,0 +1,128 @@
+/*
+ * Key-agreement Protocol Primitives (KPP)
+ *
+ * Copyright (c) 2016, Intel Corporation
+ * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/crypto.h>
+#include <crypto/algapi.h>
+#include <linux/cryptouser.h>
+#include <linux/compiler.h>
+#include <net/netlink.h>
+#include <crypto/backport-kpp.h>
+#include <crypto/internal/backport-kpp.h>
+
+extern unsigned int crypto_alg_extsize(struct crypto_alg *alg);
+void *crypto_alloc_tfm(const char *alg_name,
+                        const struct crypto_type *frontend, u32 type, u32 mask);
+
+#define CRYPTOCFGA_REPORT_KPP __CRYPTOCFGA_MAX
+#ifdef CONFIG_NET
+static int crypto_kpp_report(struct sk_buff *skb, struct crypto_alg *alg)
+{
+	struct crypto_report_kpp rkpp;
+
+	strncpy(rkpp.type, "kpp", sizeof(rkpp.type));
+
+	if (nla_put(skb, CRYPTOCFGA_REPORT_KPP,
+		    sizeof(struct crypto_report_kpp), &rkpp))
+		goto nla_put_failure;
+	return 0;
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+#else
+static int crypto_kpp_report(struct sk_buff *skb, struct crypto_alg *alg)
+{
+	return -ENOSYS;
+}
+#endif
+
+static void crypto_kpp_show(struct seq_file *m, struct crypto_alg *alg)
+	__maybe_unused;
+
+static void crypto_kpp_show(struct seq_file *m, struct crypto_alg *alg)
+{
+	seq_puts(m, "type         : kpp\n");
+}
+
+static void crypto_kpp_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_kpp *kpp = __crypto_kpp_tfm(tfm);
+	struct kpp_alg *alg = crypto_kpp_alg(kpp);
+
+	alg->exit(kpp);
+}
+
+static int crypto_kpp_init_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_kpp *kpp = __crypto_kpp_tfm(tfm);
+	struct kpp_alg *alg = crypto_kpp_alg(kpp);
+
+	if (alg->exit)
+		kpp->base.exit = crypto_kpp_exit_tfm;
+
+	if (alg->init)
+		return alg->init(kpp);
+
+	return 0;
+}
+
+static const struct crypto_type crypto_kpp_type = {
+	.extsize = crypto_alg_extsize,
+	.init_tfm = crypto_kpp_init_tfm,
+#ifdef CONFIG_PROC_FS
+	.show = crypto_kpp_show,
+#endif
+	.report = crypto_kpp_report,
+	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
+	.maskset = CRYPTO_ALG_TYPE_MASK,
+	.type = CRYPTO_ALG_TYPE_KPP,
+	.tfmsize = offsetof(struct crypto_kpp, base),
+};
+
+struct crypto_kpp *crypto_alloc_kpp(const char *alg_name, u32 type, u32 mask)
+{
+	return crypto_alloc_tfm(alg_name, &crypto_kpp_type, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_kpp);
+
+static void kpp_prepare_alg(struct kpp_alg *alg)
+{
+	struct crypto_alg *base = &alg->base;
+
+	base->cra_type = &crypto_kpp_type;
+	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
+	base->cra_flags |= CRYPTO_ALG_TYPE_KPP;
+}
+
+int crypto_register_kpp(struct kpp_alg *alg)
+{
+	struct crypto_alg *base = &alg->base;
+
+	kpp_prepare_alg(alg);
+	return crypto_register_alg(base);
+}
+EXPORT_SYMBOL_GPL(crypto_register_kpp);
+
+void crypto_unregister_kpp(struct kpp_alg *alg)
+{
+	crypto_unregister_alg(&alg->base);
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_kpp);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Key-agreement Protocol Primitives");
diff --git a/compat/crypto-skcipher.c b/compat/crypto-skcipher.c
index 9c5fe5c..def0294 100644
--- a/compat/crypto-skcipher.c
+++ b/compat/crypto-skcipher.c
@@ -48,7 +48,7 @@ static inline u32 skcipher_request_flags(struct skcipher_request *req)
 {
 	return req->base.flags;
 }
-
+#if LINUX_VERSION_IS_GEQ(4,8,0)
 enum {
 	SKCIPHER_WALK_PHYS = 1 << 0,
 	SKCIPHER_WALK_SLOW = 1 << 1,
@@ -594,6 +594,35 @@ int skcipher_walk_aead_decrypt(struct skcipher_walk *walk,
 }
 EXPORT_SYMBOL_GPL(skcipher_walk_aead_decrypt);
 
+#endif /* LINUX_VERSION_IS_GEQ(4,8,0) */
+
+#if LINUX_VERSION_IS_LESS(4,2,0)
+
+unsigned int crypto_alg_extsize(struct crypto_alg *alg)
+{
+	return alg->cra_ctxsize +
+	       (alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1));
+}
+EXPORT_SYMBOL_GPL(crypto_alg_extsize);
+
+int crypto_type_has_alg(const char *name, const struct crypto_type *frontend,
+			u32 type, u32 mask)
+{
+#if 0
+	int ret = 0;
+	struct crypto_alg *alg = crypto_find_alg(name, frontend, type, mask);
+
+	if (!IS_ERR(alg)) {
+		crypto_mod_put(alg);
+		ret = 1;
+	}
+#endif
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(crypto_type_has_alg);
+
+#endif
+
 static unsigned int crypto_skcipher_extsize(struct crypto_alg *alg)
 {
 	if (alg->cra_type == &crypto_blkcipher_type)
@@ -945,7 +974,9 @@ static int crypto_skcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
 static const struct crypto_type crypto_skcipher_type2 = {
 	.extsize = crypto_skcipher_extsize,
 	.init_tfm = crypto_skcipher_init_tfm,
+#if LINUX_VERSION_IS_GEQ(4,3,0)
 	.free = crypto_skcipher_free_instance,
+#endif
 #ifdef CONFIG_PROC_FS
 	.show = crypto_skcipher_show,
 #endif
@@ -959,8 +990,10 @@ static const struct crypto_type crypto_skcipher_type2 = {
 int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn,
 			  const char *name, u32 type, u32 mask)
 {
+#if 0
 	spawn->base.frontend = &crypto_skcipher_type2;
 	return crypto_grab_spawn(&spawn->base, name, type, mask);
+#endif
 }
 EXPORT_SYMBOL_GPL(crypto_grab_skcipher);
 
diff --git a/compat/lib-iov_iter.c b/compat/lib-iov_iter.c
new file mode 100644
index 0000000..929963d
--- /dev/null
+++ b/compat/lib-iov_iter.c
@@ -0,0 +1,1423 @@
+#include <linux/export.h>
+#include <linux/bvec.h>
+#include <linux/uio.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/splice.h>
+#include <net/checksum.h>
+
+#define PIPE_PARANOIA /* for now */
+
+#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, __bi, skip, STEP) {	\
+	struct bvec_iter __start;			\
+	__start.bi_size = n;				\
+	__start.bi_bvec_done = skip;			\
+	__start.bi_idx = 0;				\
+	for_each_bvec(__v, i->bvec, __bi, __start) {	\
+		if (!__v.bv_len)			\
+			continue;			\
+		(void)(STEP);				\
+	}						\
+}
+
+#define iterate_all_kinds(i, n, v, I, B, K) {			\
+	if (likely(n)) {					\
+		size_t skip = i->iov_offset;			\
+		if (unlikely(i->type & ITER_BVEC)) {		\
+			struct bio_vec v;			\
+			struct bvec_iter __bi;			\
+			iterate_bvec(i, n, v, __bi, 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) {			\
+	if (unlikely(i->count < n))				\
+		n = i->count;					\
+	if (i->count) {						\
+		size_t skip = i->iov_offset;			\
+		if (unlikely(i->type & ITER_BVEC)) {		\
+			const struct bio_vec *bvec = i->bvec;	\
+			struct bio_vec v;			\
+			struct bvec_iter __bi;			\
+			iterate_bvec(i, n, v, __bi, skip, (B))	\
+			i->bvec = __bvec_iter_bvec(i->bvec, __bi);	\
+			i->nr_segs -= i->bvec - bvec;		\
+			skip = __bi.bi_bvec_done;		\
+		} 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;
+
+	might_fault();
+	wanted = bytes;
+	iov = i->iov;
+	skip = i->iov_offset;
+	buf = iov->iov_base + skip;
+	copy = min(bytes, iov->iov_len - skip);
+
+	if (IS_ENABLED(CONFIG_HIGHMEM) && !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;
+
+	might_fault();
+	wanted = bytes;
+	iov = i->iov;
+	skip = i->iov_offset;
+	buf = iov->iov_base + skip;
+	copy = min(bytes, iov->iov_len - skip);
+
+	if (IS_ENABLED(CONFIG_HIGHMEM) && !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;
+}
+
+#ifdef PIPE_PARANOIA
+static bool sanity(const struct iov_iter *i)
+{
+	struct pipe_inode_info *pipe = i->pipe;
+	int idx = i->idx;
+	int next = pipe->curbuf + pipe->nrbufs;
+	if (i->iov_offset) {
+		struct pipe_buffer *p;
+		if (unlikely(!pipe->nrbufs))
+			goto Bad;	// pipe must be non-empty
+		if (unlikely(idx != ((next - 1) & (pipe->buffers - 1))))
+			goto Bad;	// must be at the last buffer...
+
+		p = &pipe->bufs[idx];
+		if (unlikely(p->offset + p->len != i->iov_offset))
+			goto Bad;	// ... at the end of segment
+	} else {
+		if (idx != (next & (pipe->buffers - 1)))
+			goto Bad;	// must be right after the last buffer
+	}
+	return true;
+Bad:
+	printk(KERN_ERR "idx = %d, offset = %zd\n", i->idx, i->iov_offset);
+	printk(KERN_ERR "curbuf = %d, nrbufs = %d, buffers = %d\n",
+			pipe->curbuf, pipe->nrbufs, pipe->buffers);
+	for (idx = 0; idx < pipe->buffers; idx++)
+		printk(KERN_ERR "[%p %p %d %d]\n",
+			pipe->bufs[idx].ops,
+			pipe->bufs[idx].page,
+			pipe->bufs[idx].offset,
+			pipe->bufs[idx].len);
+	WARN_ON(1);
+	return false;
+}
+#else
+#define sanity(i) true
+#endif
+
+static inline int next_idx(int idx, struct pipe_inode_info *pipe)
+{
+	return (idx + 1) & (pipe->buffers - 1);
+}
+
+static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i)
+{
+	struct pipe_inode_info *pipe = i->pipe;
+	struct pipe_buffer *buf;
+	size_t off;
+	int idx;
+
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	if (!sanity(i))
+		return 0;
+
+	off = i->iov_offset;
+	idx = i->idx;
+	buf = &pipe->bufs[idx];
+	if (off) {
+		if (offset == off && buf->page == page) {
+			/* merge with the last one */
+			buf->len += bytes;
+			i->iov_offset += bytes;
+			goto out;
+		}
+		idx = next_idx(idx, pipe);
+		buf = &pipe->bufs[idx];
+	}
+	if (idx == pipe->curbuf && pipe->nrbufs)
+		return 0;
+	pipe->nrbufs++;
+	buf->ops = &page_cache_pipe_buf_ops;
+	get_page(buf->page = page);
+	buf->offset = offset;
+	buf->len = bytes;
+	i->iov_offset = offset + bytes;
+	i->idx = idx;
+out:
+	i->count -= bytes;
+	return bytes;
+}
+
+#if LINUX_VERSION_IS_LESS(4,7,0)
+/*
+ * Fault in one or more iovecs of the given iov_iter, to a maximum length of
+ * bytes.  For each iovec, fault in each page that constitutes the iovec.
+ *
+ * Return 0 on success, or non-zero if the memory could not be accessed (i.e.
+ * because it is an invalid address).
+ */
+int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
+{
+	size_t skip = i->iov_offset;
+	const struct iovec *iov;
+	int err;
+	struct iovec v;
+
+	if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
+		iterate_iovec(i, bytes, v, iov, skip, ({
+			err = fault_in_pages_readable(v.iov_base, v.iov_len);
+			if (unlikely(err))
+			return err;
+		0;}))
+	}
+	return 0;
+}
+EXPORT_SYMBOL(iov_iter_fault_in_readable);
+
+#define uaccess_kernel() segment_eq(get_fs(), KERNEL_DS)
+
+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 (uaccess_kernel()) {
+		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);
+#endif
+
+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, const 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);
+}
+
+#if 0
+static inline bool allocated(struct pipe_buffer *buf)
+{
+	return buf->ops == &default_pipe_buf_ops;
+}
+
+static inline void data_start(const struct iov_iter *i, int *idxp, size_t *offp)
+{
+	size_t off = i->iov_offset;
+	int idx = i->idx;
+	if (off && (!allocated(&i->pipe->bufs[idx]) || off == PAGE_SIZE)) {
+		idx = next_idx(idx, i->pipe);
+		off = 0;
+	}
+	*idxp = idx;
+	*offp = off;
+}
+
+static size_t push_pipe(struct iov_iter *i, size_t size,
+			int *idxp, size_t *offp)
+{
+	struct pipe_inode_info *pipe = i->pipe;
+	size_t off;
+	int idx;
+	ssize_t left;
+
+	if (unlikely(size > i->count))
+		size = i->count;
+	if (unlikely(!size))
+		return 0;
+
+	left = size;
+	data_start(i, &idx, &off);
+	*idxp = idx;
+	*offp = off;
+	if (off) {
+		left -= PAGE_SIZE - off;
+		if (left <= 0) {
+			pipe->bufs[idx].len += size;
+			return size;
+		}
+		pipe->bufs[idx].len = PAGE_SIZE;
+		idx = next_idx(idx, pipe);
+	}
+	while (idx != pipe->curbuf || !pipe->nrbufs) {
+		struct page *page = alloc_page(GFP_USER);
+		if (!page)
+			break;
+		pipe->nrbufs++;
+		pipe->bufs[idx].ops = &default_pipe_buf_ops;
+		pipe->bufs[idx].page = page;
+		pipe->bufs[idx].offset = 0;
+		if (left <= PAGE_SIZE) {
+			pipe->bufs[idx].len = left;
+			return size;
+		}
+		pipe->bufs[idx].len = PAGE_SIZE;
+		left -= PAGE_SIZE;
+		idx = next_idx(idx, pipe);
+	}
+	return size - left;
+}
+
+static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
+				struct iov_iter *i)
+{
+	struct pipe_inode_info *pipe = i->pipe;
+	size_t n, off;
+	int idx;
+
+	if (!sanity(i))
+		return 0;
+
+	bytes = n = push_pipe(i, bytes, &idx, &off);
+	if (unlikely(!n))
+		return 0;
+	for ( ; n; idx = next_idx(idx, pipe), off = 0) {
+		size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
+		memcpy_to_page(pipe->bufs[idx].page, off, addr, chunk);
+		i->idx = idx;
+		i->iov_offset = off + chunk;
+		n -= chunk;
+		addr += chunk;
+	}
+	i->count -= bytes;
+	return bytes;
+}
+#endif
+
+size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
+{
+	const char *from = addr;
+#if 0
+	if (unlikely(i->type & ITER_PIPE))
+		return copy_pipe_to_iter(addr, bytes, i);
+#endif
+	if (iter_is_iovec(i))
+		might_fault();
+	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(i->type & ITER_PIPE)) {
+		WARN_ON(1);
+		return 0;
+	}
+	if (iter_is_iovec(i))
+		might_fault();
+	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);
+
+bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
+{
+	char *to = addr;
+	if (unlikely(i->type & ITER_PIPE)) {
+		WARN_ON(1);
+		return false;
+	}
+	if (unlikely(i->count < bytes))
+		return false;
+
+	if (iter_is_iovec(i))
+		might_fault();
+	iterate_all_kinds(i, bytes, v, ({
+		if (__copy_from_user((to += v.iov_len) - v.iov_len,
+				      v.iov_base, v.iov_len))
+			return false;
+		0;}),
+		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)
+	)
+
+	iov_iter_advance(i, bytes);
+	return true;
+}
+EXPORT_SYMBOL(_copy_from_iter_full);
+
+size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
+{
+	char *to = addr;
+	if (unlikely(i->type & ITER_PIPE)) {
+		WARN_ON(1);
+		return 0;
+	}
+	iterate_and_advance(i, bytes, v,
+		__copy_from_user_inatomic_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);
+
+#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
+size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
+{
+	char *to = addr;
+	if (unlikely(i->type & ITER_PIPE)) {
+		WARN_ON(1);
+		return 0;
+	}
+	iterate_and_advance(i, bytes, v,
+		__copy_from_user_flushcache((to += v.iov_len) - v.iov_len,
+					 v.iov_base, v.iov_len),
+		memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
+				 v.bv_offset, v.bv_len),
+		memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
+			v.iov_len)
+	)
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
+#endif
+
+bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
+{
+	char *to = addr;
+	if (unlikely(i->type & ITER_PIPE)) {
+		WARN_ON(1);
+		return false;
+	}
+	if (unlikely(i->count < bytes))
+		return false;
+	iterate_all_kinds(i, bytes, v, ({
+		if (__copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
+					     v.iov_base, v.iov_len))
+			return false;
+		0;}),
+		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)
+	)
+
+	iov_iter_advance(i, bytes);
+	return true;
+}
+EXPORT_SYMBOL(_copy_from_iter_full_nocache);
+
+static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
+{
+	struct page *head = compound_head(page);
+	size_t v = n + offset + page_address(page) - page_address(head);
+
+	if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head))))
+		return true;
+	WARN_ON(1);
+	return false;
+}
+
+#if LINUX_VERSION_IS_LESS(4,7,0)
+size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i)
+{
+	if (unlikely(!page_copy_sane(page, offset, bytes)))
+		return 0;
+	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 if (likely(!(i->type & ITER_PIPE)))
+		return copy_page_to_iter_iovec(page, offset, bytes, i);
+	else
+		return copy_page_to_iter_pipe(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 (unlikely(!page_copy_sane(page, offset, bytes)))
+		return 0;
+	if (unlikely(i->type & ITER_PIPE)) {
+		WARN_ON(1);
+		return 0;
+	}
+	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);
+#endif
+
+#if 0
+static size_t pipe_zero(size_t bytes, struct iov_iter *i)
+{
+	struct pipe_inode_info *pipe = i->pipe;
+	size_t n, off;
+	int idx;
+
+	if (!sanity(i))
+		return 0;
+
+	bytes = n = push_pipe(i, bytes, &idx, &off);
+	if (unlikely(!n))
+		return 0;
+
+	for ( ; n; idx = next_idx(idx, pipe), off = 0) {
+		size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
+		memzero_page(pipe->bufs[idx].page, off, chunk);
+		i->idx = idx;
+		i->iov_offset = off + chunk;
+		n -= chunk;
+	}
+	i->count -= bytes;
+	return bytes;
+}
+#endif
+
+#if LINUX_VERSION_IS_LESS(4,7,0)
+size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
+{
+	if (unlikely(i->type & ITER_PIPE))
+		return pipe_zero(bytes, i);
+	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;
+	if (unlikely(!page_copy_sane(page, offset, bytes))) {
+		kunmap_atomic(kaddr);
+		return 0;
+	}
+	if (unlikely(i->type & ITER_PIPE)) {
+		kunmap_atomic(kaddr);
+		WARN_ON(1);
+		return 0;
+	}
+	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);
+#endif
+
+static inline void pipe_truncate(struct iov_iter *i)
+{
+	struct pipe_inode_info *pipe = i->pipe;
+	if (pipe->nrbufs) {
+		size_t off = i->iov_offset;
+		int idx = i->idx;
+		int nrbufs = (idx - pipe->curbuf) & (pipe->buffers - 1);
+		if (off) {
+			pipe->bufs[idx].len = off - pipe->bufs[idx].offset;
+			idx = next_idx(idx, pipe);
+			nrbufs++;
+		}
+		while (pipe->nrbufs > nrbufs) {
+			pipe_buf_release(pipe, &pipe->bufs[idx]);
+			idx = next_idx(idx, pipe);
+			pipe->nrbufs--;
+		}
+	}
+}
+
+static void pipe_advance(struct iov_iter *i, size_t size)
+{
+	struct pipe_inode_info *pipe = i->pipe;
+	if (unlikely(i->count < size))
+		size = i->count;
+	if (size) {
+		struct pipe_buffer *buf;
+		size_t off = i->iov_offset, left = size;
+		int idx = i->idx;
+		if (off) /* make it relative to the beginning of buffer */
+			left += off - pipe->bufs[idx].offset;
+		while (1) {
+			buf = &pipe->bufs[idx];
+			if (left <= buf->len)
+				break;
+			left -= buf->len;
+			idx = next_idx(idx, pipe);
+		}
+		i->idx = idx;
+		i->iov_offset = buf->offset + left;
+	}
+	i->count -= size;
+	/* ... and discard everything past that point */
+	pipe_truncate(i);
+}
+
+#if LINUX_VERSION_IS_LESS(4,7,0)
+void iov_iter_advance(struct iov_iter *i, size_t size)
+{
+	if (unlikely(i->type & ITER_PIPE)) {
+		pipe_advance(i, size);
+		return;
+	}
+	iterate_and_advance(i, size, v, 0, 0, 0)
+}
+EXPORT_SYMBOL(iov_iter_advance);
+
+void iov_iter_revert(struct iov_iter *i, size_t unroll)
+{
+	if (!unroll)
+		return;
+	if (WARN_ON(unroll > MAX_RW_COUNT))
+		return;
+	i->count += unroll;
+	if (unlikely(i->type & ITER_PIPE)) {
+		struct pipe_inode_info *pipe = i->pipe;
+		int idx = i->idx;
+		size_t off = i->iov_offset;
+		while (1) {
+			size_t n = off - pipe->bufs[idx].offset;
+			if (unroll < n) {
+				off -= unroll;
+				break;
+			}
+			unroll -= n;
+			if (!unroll && idx == i->start_idx) {
+				off = 0;
+				break;
+			}
+			if (!idx--)
+				idx = pipe->buffers - 1;
+			off = pipe->bufs[idx].offset + pipe->bufs[idx].len;
+		}
+		i->iov_offset = off;
+		i->idx = idx;
+		pipe_truncate(i);
+		return;
+	}
+	if (unroll <= i->iov_offset) {
+		i->iov_offset -= unroll;
+		return;
+	}
+	unroll -= i->iov_offset;
+	if (i->type & ITER_BVEC) {
+		const struct bio_vec *bvec = i->bvec;
+		while (1) {
+			size_t n = (--bvec)->bv_len;
+			i->nr_segs++;
+			if (unroll <= n) {
+				i->bvec = bvec;
+				i->iov_offset = n - unroll;
+				return;
+			}
+			unroll -= n;
+		}
+	} else { /* same logics for iovec and kvec */
+		const struct iovec *iov = i->iov;
+		while (1) {
+			size_t n = (--iov)->iov_len;
+			i->nr_segs++;
+			if (unroll <= n) {
+				i->iov = iov;
+				i->iov_offset = n - unroll;
+				return;
+			}
+			unroll -= n;
+		}
+	}
+}
+EXPORT_SYMBOL(iov_iter_revert);
+
+/*
+ * Return the count of just the current iov_iter segment.
+ */
+size_t iov_iter_single_seg_count(const struct iov_iter *i)
+{
+	if (unlikely(i->type & ITER_PIPE))
+		return i->count;	// it is a silly place, anyway
+	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);
+
+void iov_iter_pipe(struct iov_iter *i, int direction,
+			struct pipe_inode_info *pipe,
+			size_t count)
+{
+	BUG_ON(direction != ITER_PIPE);
+	WARN_ON(pipe->nrbufs == pipe->buffers);
+	i->type = direction;
+	i->pipe = pipe;
+	i->idx = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
+	i->iov_offset = 0;
+	i->count = count;
+	i->start_idx = i->idx;
+}
+EXPORT_SYMBOL(iov_iter_pipe);
+
+unsigned long iov_iter_alignment(const struct iov_iter *i)
+{
+	unsigned long res = 0;
+	size_t size = i->count;
+
+	if (unlikely(i->type & ITER_PIPE)) {
+		if (size && i->iov_offset && allocated(&i->pipe->bufs[i->idx]))
+			return size | i->iov_offset;
+		return size;
+	}
+	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);
+
+unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
+{
+	unsigned long res = 0;
+	size_t size = i->count;
+
+	if (unlikely(i->type & ITER_PIPE)) {
+		WARN_ON(1);
+		return ~0U;
+	}
+
+	iterate_all_kinds(i, size, v,
+		(res |= (!res ? 0 : (unsigned long)v.iov_base) |
+			(size != v.iov_len ? size : 0), 0),
+		(res |= (!res ? 0 : (unsigned long)v.bv_offset) |
+			(size != v.bv_len ? size : 0)),
+		(res |= (!res ? 0 : (unsigned long)v.iov_base) |
+			(size != v.iov_len ? size : 0))
+		);
+	return res;
+}
+EXPORT_SYMBOL(iov_iter_gap_alignment);
+#endif
+
+#if 0
+static inline size_t __pipe_get_pages(struct iov_iter *i,
+				size_t maxsize,
+				struct page **pages,
+				int idx,
+				size_t *start)
+{
+	struct pipe_inode_info *pipe = i->pipe;
+	ssize_t n = push_pipe(i, maxsize, &idx, start);
+	if (!n)
+		return -EFAULT;
+
+	maxsize = n;
+	n += *start;
+	while (n > 0) {
+		get_page(*pages++ = pipe->bufs[idx].page);
+		idx = next_idx(idx, pipe);
+		n -= PAGE_SIZE;
+	}
+
+	return maxsize;
+}
+
+static ssize_t pipe_get_pages(struct iov_iter *i,
+		   struct page **pages, size_t maxsize, unsigned maxpages,
+		   size_t *start)
+{
+	unsigned npages;
+	size_t capacity;
+	int idx;
+
+	if (!maxsize)
+		return 0;
+
+	if (!sanity(i))
+		return -EFAULT;
+
+	data_start(i, &idx, start);
+	/* some of this one + all after this one */
+	npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
+	capacity = min(npages,maxpages) * PAGE_SIZE - *start;
+
+	return __pipe_get_pages(i, min(maxsize, capacity), pages, idx, start);
+}
+#endif
+#if LINUX_VERSION_IS_LESS(4,7,0)
+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 (unlikely(i->type & ITER_PIPE))
+		return pipe_get_pages(i, pages, maxsize, maxpages, start);
+	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);
+#endif
+
+static struct page **get_pages_array(size_t n)
+{
+	return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
+}
+
+#if LINUX_VERSION_IS_LESS(4,7,0)
+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 (unlikely(i->type & ITER_PIPE))
+		return pipe_get_pages_alloc(i, pages, maxsize, start);
+	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;
+	sum = *csum;
+	if (unlikely(i->type & ITER_PIPE)) {
+		WARN_ON(1);
+		return 0;
+	}
+	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);
+#endif
+
+bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum,
+			       struct iov_iter *i)
+{
+	char *to = addr;
+	__wsum sum, next;
+	size_t off = 0;
+	sum = *csum;
+	if (unlikely(i->type & ITER_PIPE)) {
+		WARN_ON(1);
+		return false;
+	}
+	if (unlikely(i->count < bytes))
+		return false;
+	iterate_all_kinds(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)
+			return false;
+		sum = csum_block_add(sum, next, off);
+		off += 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;
+	iov_iter_advance(i, bytes);
+	return true;
+}
+EXPORT_SYMBOL(csum_and_copy_from_iter_full);
+
+#if LINUX_VERSION_IS_LESS(4,7,0)
+size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum,
+			     struct iov_iter *i)
+{
+	const char *from = addr;
+	__wsum sum, next;
+	size_t off = 0;
+	sum = *csum;
+	if (unlikely(i->type & ITER_PIPE)) {
+		WARN_ON(1);	/* for now */
+		return 0;
+	}
+	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;
+
+	if (unlikely(i->type & ITER_PIPE)) {
+		struct pipe_inode_info *pipe = i->pipe;
+		size_t off;
+		int idx;
+
+		if (!sanity(i))
+			return 0;
+
+		data_start(i, &idx, &off);
+		/* some of this one + all after this one */
+		npages = ((pipe->curbuf - idx - 1) & (pipe->buffers - 1)) + 1;
+		if (npages >= maxpages)
+			return maxpages;
+	} else 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 (unlikely(new->type & ITER_PIPE)) {
+		WARN_ON(1);
+		return NULL;
+	}
+	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);
+
+/**
+ * import_iovec() - Copy an array of &struct iovec from userspace
+ *     into the kernel, check that it is valid, and initialize a new
+ *     &struct iov_iter iterator to access it.
+ *
+ * @type: One of %READ or %WRITE.
+ * @uvector: Pointer to the userspace array.
+ * @nr_segs: Number of elements in userspace array.
+ * @fast_segs: Number of elements in @iov.
+ * @iov: (input and output parameter) Pointer to pointer to (usually small
+ *     on-stack) kernel array.
+ * @i: Pointer to iterator that will be initialized on success.
+ *
+ * If the array pointed to by *@iov is large enough to hold all @nr_segs,
+ * then this function places %NULL in *@iov on return. Otherwise, a new
+ * array will be allocated and the result placed in *@iov. This means that
+ * the caller may call kfree() on *@iov regardless of whether the small
+ * on-stack array was used or not (and regardless of whether this function
+ * returns an error or not).
+ *
+ * Return: 0 on success or negative error code on error.
+ */
+int import_iovec(int type, const struct iovec __user * uvector,
+		 unsigned nr_segs, unsigned fast_segs,
+		 struct iovec **iov, struct iov_iter *i)
+{
+	ssize_t n;
+	struct iovec *p;
+	n = rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
+				  *iov, &p);
+	if (n < 0) {
+		if (p != *iov)
+			kfree(p);
+		*iov = NULL;
+		return n;
+	}
+	iov_iter_init(i, type, p, nr_segs, n);
+	*iov = p == *iov ? NULL : p;
+	return 0;
+}
+EXPORT_SYMBOL(import_iovec);
+#endif
+
+#ifdef CONFIG_COMPAT
+#include <linux/compat.h>
+
+int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
+		 unsigned nr_segs, unsigned fast_segs,
+		 struct iovec **iov, struct iov_iter *i)
+{
+	ssize_t n;
+	struct iovec *p;
+	n = compat_rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
+				  *iov, &p);
+	if (n < 0) {
+		if (p != *iov)
+			kfree(p);
+		*iov = NULL;
+		return n;
+	}
+	iov_iter_init(i, type, p, nr_segs, n);
+	*iov = p == *iov ? NULL : p;
+	return 0;
+}
+#endif
+
+#if LINUX_VERSION_IS_LESS(4,7,0)
+int import_single_range(int rw, void __user *buf, size_t len,
+		 struct iovec *iov, struct iov_iter *i)
+{
+	if (len > MAX_RW_COUNT)
+		len = MAX_RW_COUNT;
+	if (unlikely(!access_ok(!rw, buf, len)))
+		return -EFAULT;
+
+	iov->iov_base = buf;
+	iov->iov_len = len;
+	iov_iter_init(i, rw, iov, 1, len);
+	return 0;
+}
+EXPORT_SYMBOL(import_single_range);
+#endif