[linux-block.git] / include / linux / uio.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 *	Berkeley style UIO structures	-	Alan Cox 1994.
 */
#ifndef __LINUX_UIO_H
#define __LINUX_UIO_H

#include <linux/kernel.h>
#include <linux/thread_info.h>
#include <linux/mm_types.h>
#include <uapi/linux/uio.h>

struct page;
struct pipe_inode_info;

typedef unsigned int __bitwise iov_iter_extraction_t;

struct kvec {
	void *iov_base; /* and that should *never* hold a userland pointer */
	size_t iov_len;
};

enum iter_type {
	/* iter types */
	ITER_IOVEC,
	ITER_KVEC,
	ITER_BVEC,
	ITER_PIPE,
	ITER_XARRAY,
	ITER_DISCARD,
	ITER_UBUF,
};

#define ITER_SOURCE	1	// == WRITE
#define ITER_DEST	0	// == READ

struct iov_iter_state {
	size_t iov_offset;
	size_t count;
	unsigned long nr_segs;
};

struct iov_iter {
	u8 iter_type;
	bool copy_mc;
	bool nofault;
	bool data_source;
	bool user_backed;
	union {
		size_t iov_offset;
		int last_offset;
	};
	/*
	 * Hack alert: overlay ubuf_iovec with iovec + count, so
	 * that the members resolve correctly regardless of the type
	 * of iterator used. This means that you can use:
	 *
	 * &iter->__ubuf_iovec or iter->__iov
	 *
	 * interchangably for the user_backed cases, hence simplifying
	 * some of the cases that need to deal with both.
	 */
	union {
		/*
		 * This really should be a const, but we cannot do that without
		 * also modifying any of the zero-filling iter init functions.
		 * Leave it non-const for now, but it should be treated as such.
		 */
		struct iovec __ubuf_iovec;
		struct {
			union {
				/* use iter_iov() to get the current vec */
				const struct iovec *__iov;
				const struct kvec *kvec;
				const struct bio_vec *bvec;
				struct xarray *xarray;
				struct pipe_inode_info *pipe;
				void __user *ubuf;
			};
			size_t count;
		};
	};
	union {
		unsigned long nr_segs;
		struct {
			unsigned int head;
			unsigned int start_head;
		};
		loff_t xarray_start;
	};
};

static inline const struct iovec *iter_iov(const struct iov_iter *iter)
{
	if (iter->iter_type == ITER_UBUF)
		return (const struct iovec *) &iter->__ubuf_iovec;
	return iter->__iov;
}

#define iter_iov_addr(iter)	(iter_iov(iter)->iov_base + (iter)->iov_offset)
#define iter_iov_len(iter)	(iter_iov(iter)->iov_len - (iter)->iov_offset)

static inline enum iter_type iov_iter_type(const struct iov_iter *i)
{
	return i->iter_type;
}

static inline void iov_iter_save_state(struct iov_iter *iter,
				       struct iov_iter_state *state)
{
	state->iov_offset = iter->iov_offset;
	state->count = iter->count;
	state->nr_segs = iter->nr_segs;
}

static inline bool iter_is_ubuf(const struct iov_iter *i)
{
	return iov_iter_type(i) == ITER_UBUF;
}

static inline bool iter_is_iovec(const struct iov_iter *i)
{
	return iov_iter_type(i) == ITER_IOVEC;
}

static inline bool iov_iter_is_kvec(const struct iov_iter *i)
{
	return iov_iter_type(i) == ITER_KVEC;
}

static inline bool iov_iter_is_bvec(const struct iov_iter *i)
{
	return iov_iter_type(i) == ITER_BVEC;
}

static inline bool iov_iter_is_pipe(const struct iov_iter *i)
{
	return iov_iter_type(i) == ITER_PIPE;
}

static inline bool iov_iter_is_discard(const struct iov_iter *i)
{
	return iov_iter_type(i) == ITER_DISCARD;
}

static inline bool iov_iter_is_xarray(const struct iov_iter *i)
{
	return iov_iter_type(i) == ITER_XARRAY;
}

static inline unsigned char iov_iter_rw(const struct iov_iter *i)
{
	return i->data_source ? WRITE : READ;
}

static inline bool user_backed_iter(const struct iov_iter *i)
{
	return i->user_backed;
}

/*
 * Total number of bytes covered by an iovec.
 *
 * NOTE that it is not safe to use this function until all the iovec's
 * segment lengths have been validated.  Because the individual lengths can
 * overflow a size_t when added together.
 */
static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
{
	unsigned long seg;
	size_t ret = 0;

	for (seg = 0; seg < nr_segs; seg++)
		ret += iov[seg].iov_len;
	return ret;
}

size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
				  size_t bytes, struct iov_iter *i);
void iov_iter_advance(struct iov_iter *i, size_t bytes);
void iov_iter_revert(struct iov_iter *i, size_t bytes);
size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
size_t iov_iter_single_seg_count(const struct iov_iter *i);
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
			 struct iov_iter *i);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
			 struct iov_iter *i);

size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);

static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
		size_t bytes, struct iov_iter *i)
{
	return copy_page_to_iter(&folio->page, offset, bytes, i);
}
size_t copy_page_to_iter_nofault(struct page *page, unsigned offset,
				 size_t bytes, struct iov_iter *i);

static __always_inline __must_check
size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
{
	if (check_copy_size(addr, bytes, true))
		return _copy_to_iter(addr, bytes, i);
	return 0;
}

static __always_inline __must_check
size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
{
	if (check_copy_size(addr, bytes, false))
		return _copy_from_iter(addr, bytes, i);
	return 0;
}

static __always_inline __must_check
bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
{
	size_t copied = copy_from_iter(addr, bytes, i);
	if (likely(copied == bytes))
		return true;
	iov_iter_revert(i, copied);
	return false;
}

static __always_inline __must_check
size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
{
	if (check_copy_size(addr, bytes, false))
		return _copy_from_iter_nocache(addr, bytes, i);
	return 0;
}

static __always_inline __must_check
bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
{
	size_t copied = copy_from_iter_nocache(addr, bytes, i);
	if (likely(copied == bytes))
		return true;
	iov_iter_revert(i, copied);
	return false;
}

#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
/*
 * Note, users like pmem that depend on the stricter semantics of
 * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
 * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
 * destination is flushed from the cache on return.
 */
size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
#else
#define _copy_from_iter_flushcache _copy_from_iter_nocache
#endif

#ifdef CONFIG_ARCH_HAS_COPY_MC
size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
static inline void iov_iter_set_copy_mc(struct iov_iter *i)
{
	i->copy_mc = true;
}

static inline bool iov_iter_is_copy_mc(const struct iov_iter *i)
{
	return i->copy_mc;
}
#else
#define _copy_mc_to_iter _copy_to_iter
static inline void iov_iter_set_copy_mc(struct iov_iter *i) { }
static inline bool iov_iter_is_copy_mc(const struct iov_iter *i)
{
	return false;
}
#endif

size_t iov_iter_zero(size_t bytes, struct iov_iter *);
bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
			unsigned len_mask);
unsigned long iov_iter_alignment(const struct iov_iter *i);
unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
			unsigned long nr_segs, size_t count);
void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
			unsigned long nr_segs, size_t count);
void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
			unsigned long nr_segs, size_t count);
void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
			size_t count);
void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
		     loff_t start, size_t count);
ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
		size_t maxsize, unsigned maxpages, size_t *start,
		iov_iter_extraction_t extraction_flags);
ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
			size_t maxsize, unsigned maxpages, size_t *start);
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
		struct page ***pages, size_t maxsize, size_t *start,
		iov_iter_extraction_t extraction_flags);
ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
			size_t maxsize, size_t *start);
int iov_iter_npages(const struct iov_iter *i, int maxpages);
void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);

const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);

static inline size_t iov_iter_count(const struct iov_iter *i)
{
	return i->count;
}

/*
 * Cap the iov_iter by given limit; note that the second argument is
 * *not* the new size - it's upper limit for such.  Passing it a value
 * greater than the amount of data in iov_iter is fine - it'll just do
 * nothing in that case.
 */
static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
{
	/*
	 * count doesn't have to fit in size_t - comparison extends both
	 * operands to u64 here and any value that would be truncated by
	 * conversion in assignement is by definition greater than all
	 * values of size_t, including old i->count.
	 */
	if (i->count > count)
		i->count = count;
}

/*
 * reexpand a previously truncated iterator; count must be no more than how much
 * we had shrunk it.
 */
static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
{
	i->count = count;
}

static inline int
iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
{
	size_t shorted = 0;
	int npages;

	if (iov_iter_count(i) > max_bytes) {
		shorted = iov_iter_count(i) - max_bytes;
		iov_iter_truncate(i, max_bytes);
	}
	npages = iov_iter_npages(i, maxpages);
	if (shorted)
		iov_iter_reexpand(i, iov_iter_count(i) + shorted);

	return npages;
}

struct csum_state {
	__wsum csum;
	size_t off;
};

size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);

static __always_inline __must_check
bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
				  __wsum *csum, struct iov_iter *i)
{
	size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
	if (likely(copied == bytes))
		return true;
	iov_iter_revert(i, copied);
	return false;
}
size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
		struct iov_iter *i);

struct iovec *iovec_from_user(const struct iovec __user *uvector,
		unsigned long nr_segs, unsigned long fast_segs,
		struct iovec *fast_iov, bool compat);
ssize_t import_iovec(int type, const struct iovec __user *uvec,
		 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
		 struct iov_iter *i);
ssize_t __import_iovec(int type, const struct iovec __user *uvec,
		 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
		 struct iov_iter *i, bool compat);
int import_single_range(int type, void __user *buf, size_t len,
		 struct iovec *iov, struct iov_iter *i);
int import_ubuf(int type, void __user *buf, size_t len, struct iov_iter *i);

static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
			void __user *buf, size_t count)
{
	WARN_ON(direction & ~(READ | WRITE));
	*i = (struct iov_iter) {
		.iter_type = ITER_UBUF,
		.copy_mc = false,
		.user_backed = true,
		.data_source = direction,
		.ubuf = buf,
		.count = count,
		.nr_segs = 1
	};
}
/* Flags for iov_iter_get/extract_pages*() */
/* Allow P2PDMA on the extracted pages */
#define ITER_ALLOW_P2PDMA	((__force iov_iter_extraction_t)0x01)

ssize_t iov_iter_extract_pages(struct iov_iter *i, struct page ***pages,
			       size_t maxsize, unsigned int maxpages,
			       iov_iter_extraction_t extraction_flags,
			       size_t *offset0);

/**
 * iov_iter_extract_will_pin - Indicate how pages from the iterator will be retained
 * @iter: The iterator
 *
 * Examine the iterator and indicate by returning true or false as to how, if
 * at all, pages extracted from the iterator will be retained by the extraction
 * function.
 *
 * %true indicates that the pages will have a pin placed in them that the
 * caller must unpin.  This is must be done for DMA/async DIO to force fork()
 * to forcibly copy a page for the child (the parent must retain the original
 * page).
 *
 * %false indicates that no measures are taken and that it's up to the caller
 * to retain the pages.
 */
static inline bool iov_iter_extract_will_pin(const struct iov_iter *iter)
{
	return user_backed_iter(iter);
}

#endif
Commit	Line	Data
2874c5fd	1	/* SPDX-License-Identifier: GPL-2.0-or-later */
1da177e4 LT	2	/*
1da177e4 LT	3	* Berkeley style UIO structures - Alan Cox 1994.
1da177e4	4	*/
607ca46e DH	5	#ifndef __LINUX_UIO_H
607ca46e DH	6	#define __LINUX_UIO_H
1da177e4	7
92236878	8	#include <linux/kernel.h>
aa28de27	9	#include <linux/thread_info.h>
d9c19d32	10	#include <linux/mm_types.h>
607ca46e	11	#include <uapi/linux/uio.h>
1da177e4	12
92236878	13	struct page;
241699cd	14	struct pipe_inode_info;
812ed032	15
f62e52d1 DH	16	typedef unsigned int __bitwise iov_iter_extraction_t;
f62e52d1 DH	17
812ed032 JS	18	struct kvec {
	19	void iov_base; / and that should never hold a userland pointer */
	20	size_t iov_len;
	21	};
	22
00e23707	23	enum iter_type {
875f1d07	24	/* iter types */
8cd54c1c AV	25	ITER_IOVEC,
	26	ITER_KVEC,
	27	ITER_BVEC,
	28	ITER_PIPE,
	29	ITER_XARRAY,
	30	ITER_DISCARD,
fcb14cb1	31	ITER_UBUF,
62a8067a AV	32	};
62a8067a AV	33
de4eda9d AV	34	#define ITER_SOURCE 1 // == WRITE
	35	#define ITER_DEST 0 // == READ
	36
8fb0f47a JA	37	struct iov_iter_state {
	38	size_t iov_offset;
	39	size_t count;
	40	unsigned long nr_segs;
	41	};
	42
92236878	43	struct iov_iter {
8cd54c1c	44	u8 iter_type;
245f0922	45	bool copy_mc;
3337ab08	46	bool nofault;
8cd54c1c	47	bool data_source;
fcb14cb1	48	bool user_backed;
10f525a8 AV	49	union {
	50	size_t iov_offset;
	51	int last_offset;
	52	};
747b1f65 JA	53	/*
	54	* Hack alert: overlay ubuf_iovec with iovec + count, so
	55	* that the members resolve correctly regardless of the type
	56	* of iterator used. This means that you can use:
	57	*
	58	* &iter->__ubuf_iovec or iter->__iov
	59	*
	60	* interchangably for the user_backed cases, hence simplifying
	61	* some of the cases that need to deal with both.
	62	*/
62a8067a	63	union {
747b1f65 JA	64	/*
	65	* This really should be a const, but we cannot do that without
	66	* also modifying any of the zero-filling iter init functions.
	67	* Leave it non-const for now, but it should be treated as such.
	68	*/
	69	struct iovec __ubuf_iovec;
	70	struct {
	71	union {
	72	/* use iter_iov() to get the current vec */
	73	const struct iovec *__iov;
	74	const struct kvec *kvec;
	75	const struct bio_vec *bvec;
	76	struct xarray *xarray;
	77	struct pipe_inode_info *pipe;
	78	void __user *ubuf;
	79	};
	80	size_t count;
	81	};
241699cd AV	82	};
	83	union {
	84	unsigned long nr_segs;
27c0e374	85	struct {
8cefc107 DH	86	unsigned int head;
8cefc107 DH	87	unsigned int start_head;
27c0e374	88	};
7ff50620	89	loff_t xarray_start;
62a8067a	90	};
92236878 KO	91	};
92236878 KO	92
747b1f65 JA	93	static inline const struct iovec iter_iov(const struct iov_iter iter)
	94	{
	95	if (iter->iter_type == ITER_UBUF)
	96	return (const struct iovec *) &iter->__ubuf_iovec;
	97	return iter->__iov;
	98	}
	99
95e49cf8 JA	100	#define iter_iov_addr(iter) (iter_iov(iter)->iov_base + (iter)->iov_offset)
95e49cf8 JA	101	#define iter_iov_len(iter) (iter_iov(iter)->iov_len - (iter)->iov_offset)
de4f5fed	102
00e23707 DH	103	static inline enum iter_type iov_iter_type(const struct iov_iter *i)
00e23707 DH	104	{
8cd54c1c	105	return i->iter_type;
00e23707 DH	106	}
00e23707 DH	107
8fb0f47a JA	108	static inline void iov_iter_save_state(struct iov_iter *iter,
	109	struct iov_iter_state *state)
	110	{
	111	state->iov_offset = iter->iov_offset;
	112	state->count = iter->count;
	113	state->nr_segs = iter->nr_segs;
	114	}
	115
fcb14cb1 AV	116	static inline bool iter_is_ubuf(const struct iov_iter *i)
	117	{
	118	return iov_iter_type(i) == ITER_UBUF;
	119	}
	120
00e23707 DH	121	static inline bool iter_is_iovec(const struct iov_iter *i)
	122	{
	123	return iov_iter_type(i) == ITER_IOVEC;
	124	}
	125
	126	static inline bool iov_iter_is_kvec(const struct iov_iter *i)
	127	{
	128	return iov_iter_type(i) == ITER_KVEC;
	129	}
	130
	131	static inline bool iov_iter_is_bvec(const struct iov_iter *i)
	132	{
	133	return iov_iter_type(i) == ITER_BVEC;
	134	}
	135
	136	static inline bool iov_iter_is_pipe(const struct iov_iter *i)
	137	{
	138	return iov_iter_type(i) == ITER_PIPE;
	139	}
	140
9ea9ce04 DH	141	static inline bool iov_iter_is_discard(const struct iov_iter *i)
	142	{
	143	return iov_iter_type(i) == ITER_DISCARD;
	144	}
	145
7ff50620 DH	146	static inline bool iov_iter_is_xarray(const struct iov_iter *i)
	147	{
	148	return iov_iter_type(i) == ITER_XARRAY;
	149	}
	150
00e23707 DH	151	static inline unsigned char iov_iter_rw(const struct iov_iter *i)
00e23707 DH	152	{
8cd54c1c	153	return i->data_source ? WRITE : READ;
00e23707 DH	154	}
00e23707 DH	155
fcb14cb1 AV	156	static inline bool user_backed_iter(const struct iov_iter *i)
	157	{
	158	return i->user_backed;
	159	}
	160
1da177e4 LT	161	/*
	162	* Total number of bytes covered by an iovec.
	163	*
	164	* NOTE that it is not safe to use this function until all the iovec's
	165	* segment lengths have been validated. Because the individual lengths can
	166	* overflow a size_t when added together.
	167	*/
	168	static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
	169	{
	170	unsigned long seg;
	171	size_t ret = 0;
	172
	173	for (seg = 0; seg < nr_segs; seg++)
	174	ret += iov[seg].iov_len;
	175	return ret;
	176	}
	177
f0b65f39 AV	178	size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
f0b65f39 AV	179	size_t bytes, struct iov_iter *i);
92236878	180	void iov_iter_advance(struct iov_iter *i, size_t bytes);
27c0e374	181	void iov_iter_revert(struct iov_iter *i, size_t bytes);
a6294593	182	size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
cdd591fc	183	size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
92236878	184	size_t iov_iter_single_seg_count(const struct iov_iter *i);
6e58e79d AV	185	size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
6e58e79d AV	186	struct iov_iter *i);
f0d1bec9 AV	187	size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
f0d1bec9 AV	188	struct iov_iter *i);
aa28de27 AV	189
	190	size_t _copy_to_iter(const void addr, size_t bytes, struct iov_iter i);
	191	size_t _copy_from_iter(void addr, size_t bytes, struct iov_iter i);
aa28de27	192	size_t _copy_from_iter_nocache(void addr, size_t bytes, struct iov_iter i);
aa28de27	193
d9c19d32 MWO	194	static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
	195	size_t bytes, struct iov_iter *i)
	196	{
	197	return copy_page_to_iter(&folio->page, offset, bytes, i);
	198	}
4f80818b LS	199	size_t copy_page_to_iter_nofault(struct page *page, unsigned offset,
4f80818b LS	200	size_t bytes, struct iov_iter *i);
d9c19d32	201
aa28de27 AV	202	static __always_inline __must_check
	203	size_t copy_to_iter(const void addr, size_t bytes, struct iov_iter i)
	204	{
0e3c3b90	205	if (check_copy_size(addr, bytes, true))
aa28de27	206	return _copy_to_iter(addr, bytes, i);
0e3c3b90	207	return 0;
aa28de27 AV	208	}
	209
	210	static __always_inline __must_check
	211	size_t copy_from_iter(void addr, size_t bytes, struct iov_iter i)
	212	{
0e3c3b90	213	if (check_copy_size(addr, bytes, false))
aa28de27	214	return _copy_from_iter(addr, bytes, i);
0e3c3b90	215	return 0;
aa28de27 AV	216	}
	217
	218	static __always_inline __must_check
	219	bool copy_from_iter_full(void addr, size_t bytes, struct iov_iter i)
	220	{
4b6c132b AV	221	size_t copied = copy_from_iter(addr, bytes, i);
	222	if (likely(copied == bytes))
	223	return true;
	224	iov_iter_revert(i, copied);
	225	return false;
aa28de27 AV	226	}
	227
	228	static __always_inline __must_check
	229	size_t copy_from_iter_nocache(void addr, size_t bytes, struct iov_iter i)
	230	{
0e3c3b90	231	if (check_copy_size(addr, bytes, false))
aa28de27	232	return _copy_from_iter_nocache(addr, bytes, i);
0e3c3b90	233	return 0;
aa28de27 AV	234	}
	235
	236	static __always_inline __must_check
	237	bool copy_from_iter_full_nocache(void addr, size_t bytes, struct iov_iter i)
	238	{
4b6c132b AV	239	size_t copied = copy_from_iter_nocache(addr, bytes, i);
	240	if (likely(copied == bytes))
	241	return true;
	242	iov_iter_revert(i, copied);
	243	return false;
aa28de27 AV	244	}
aa28de27 AV	245
0aed55af DW	246	#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
	247	/*
	248	* Note, users like pmem that depend on the stricter semantics of
e17f7a0b	249	* _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
0aed55af DW	250	* IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
	251	* destination is flushed from the cache on return.
	252	*/
6a37e940	253	size_t _copy_from_iter_flushcache(void addr, size_t bytes, struct iov_iter i);
0aed55af	254	#else
6a37e940 LT	255	#define _copy_from_iter_flushcache _copy_from_iter_nocache
	256	#endif
	257
ec6347bb DW	258	#ifdef CONFIG_ARCH_HAS_COPY_MC
ec6347bb DW	259	size_t _copy_mc_to_iter(const void addr, size_t bytes, struct iov_iter i);
245f0922 KW	260	static inline void iov_iter_set_copy_mc(struct iov_iter *i)
	261	{
	262	i->copy_mc = true;
	263	}
	264
	265	static inline bool iov_iter_is_copy_mc(const struct iov_iter *i)
	266	{
	267	return i->copy_mc;
	268	}
8780356e	269	#else
ec6347bb	270	#define _copy_mc_to_iter _copy_to_iter
245f0922 KW	271	static inline void iov_iter_set_copy_mc(struct iov_iter *i) { }
	272	static inline bool iov_iter_is_copy_mc(const struct iov_iter *i)
	273	{
	274	return false;
	275	}
8780356e DW	276	#endif
8780356e DW	277
c35e0248	278	size_t iov_iter_zero(size_t bytes, struct iov_iter *);
cfa320f7 KB	279	bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
cfa320f7 KB	280	unsigned len_mask);
886a3911	281	unsigned long iov_iter_alignment(const struct iov_iter *i);
357f435d	282	unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
aa563d7b	283	void iov_iter_init(struct iov_iter i, unsigned int direction, const struct iovec iov,
71d8e532	284	unsigned long nr_segs, size_t count);
aa563d7b	285	void iov_iter_kvec(struct iov_iter i, unsigned int direction, const struct kvec kvec,
05afcb77	286	unsigned long nr_segs, size_t count);
aa563d7b	287	void iov_iter_bvec(struct iov_iter i, unsigned int direction, const struct bio_vec bvec,
abb78f87	288	unsigned long nr_segs, size_t count);
aa563d7b	289	void iov_iter_pipe(struct iov_iter i, unsigned int direction, struct pipe_inode_info pipe,
241699cd	290	size_t count);
9ea9ce04	291	void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
7ff50620 DH	292	void iov_iter_xarray(struct iov_iter i, unsigned int direction, struct xarray xarray,
7ff50620 DH	293	loff_t start, size_t count);
d8207640 LG	294	ssize_t iov_iter_get_pages(struct iov_iter i, struct page *pages,
d8207640 LG	295	size_t maxsize, unsigned maxpages, size_t *start,
f62e52d1	296	iov_iter_extraction_t extraction_flags);
eba2d3d7	297	ssize_t iov_iter_get_pages2(struct iov_iter i, struct page *pages,
2c80929c	298	size_t maxsize, unsigned maxpages, size_t *start);
d8207640 LG	299	ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
d8207640 LG	300	struct page **pages, size_t maxsize, size_t start,
f62e52d1	301	iov_iter_extraction_t extraction_flags);
eba2d3d7	302	ssize_t iov_iter_get_pages_alloc2(struct iov_iter i, struct page **pages,
91f79c43	303	size_t maxsize, size_t *start);
f67da30c	304	int iov_iter_npages(const struct iov_iter *i, int maxpages);
8fb0f47a	305	void iov_iter_restore(struct iov_iter i, struct iov_iter_state state);
92236878	306
4b8164b9 AV	307	const void dup_iter(struct iov_iter new, struct iov_iter *old, gfp_t flags);
4b8164b9 AV	308
b57332b4	309	static inline size_t iov_iter_count(const struct iov_iter *i)
92236878 KO	310	{
	311	return i->count;
	312	}
	313
0b86dbf6 AV	314	/*
	315	* Cap the iov_iter by given limit; note that the second argument is
	316	* not the new size - it's upper limit for such. Passing it a value
	317	* greater than the amount of data in iov_iter is fine - it'll just do
	318	* nothing in that case.
	319	*/
	320	static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
0c949334	321	{
0b86dbf6 AV	322	/*
	323	* count doesn't have to fit in size_t - comparison extends both
	324	* operands to u64 here and any value that would be truncated by
	325	* conversion in assignement is by definition greater than all
	326	* values of size_t, including old i->count.
	327	*/
7dedd3e1	328	if (i->count > count)
0c949334 AV	329	i->count = count;
	330	}
	331
b42b15fd AV	332	/*
	333	* reexpand a previously truncated iterator; count must be no more than how much
	334	* we had shrunk it.
	335	*/
	336	static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
	337	{
	338	i->count = count;
	339	}
52cbd23a	340
b93235e6 JK	341	static inline int
	342	iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
	343	{
	344	size_t shorted = 0;
	345	int npages;
	346
	347	if (iov_iter_count(i) > max_bytes) {
	348	shorted = iov_iter_count(i) - max_bytes;
	349	iov_iter_truncate(i, max_bytes);
	350	}
7187440d	351	npages = iov_iter_npages(i, maxpages);
b93235e6 JK	352	if (shorted)
	353	iov_iter_reexpand(i, iov_iter_count(i) + shorted);
	354
	355	return npages;
	356	}
	357
52cbd23a WB	358	struct csum_state {
	359	__wsum csum;
	360	size_t off;
	361	};
	362
	363	size_t csum_and_copy_to_iter(const void addr, size_t bytes, void csstate, struct iov_iter *i);
a604ec7e	364	size_t csum_and_copy_from_iter(void addr, size_t bytes, __wsum csum, struct iov_iter *i);
4b6c132b AV	365
	366	static __always_inline __must_check
	367	bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
	368	__wsum csum, struct iov_iter i)
	369	{
	370	size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
	371	if (likely(copied == bytes))
	372	return true;
	373	iov_iter_revert(i, copied);
	374	return false;
	375	}
d05f4435 SG	376	size_t hash_and_copy_to_iter(const void addr, size_t bytes, void hashp,
d05f4435 SG	377	struct iov_iter *i);
b42b15fd	378
bfdc5970 CH	379	struct iovec iovec_from_user(const struct iovec __user uvector,
	380	unsigned long nr_segs, unsigned long fast_segs,
	381	struct iovec *fast_iov, bool compat);
	382	ssize_t import_iovec(int type, const struct iovec __user *uvec,
	383	unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
	384	struct iov_iter *i);
	385	ssize_t __import_iovec(int type, const struct iovec __user *uvec,
	386	unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
	387	struct iov_iter *i, bool compat);
bc917be8 AV	388	int import_single_range(int type, void __user *buf, size_t len,
bc917be8 AV	389	struct iovec iov, struct iov_iter i);
2ad9bd83	390	int import_ubuf(int type, void __user buf, size_t len, struct iov_iter i);
bc917be8	391
fcb14cb1 AV	392	static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
	393	void __user *buf, size_t count)
	394	{
	395	WARN_ON(direction & ~(READ \| WRITE));
	396	*i = (struct iov_iter) {
	397	.iter_type = ITER_UBUF,
245f0922	398	.copy_mc = false,
fcb14cb1 AV	399	.user_backed = true,
	400	.data_source = direction,
	401	.ubuf = buf,
cd0bd57a JA	402	.count = count,
cd0bd57a JA	403	.nr_segs = 1
fcb14cb1 AV	404	};
fcb14cb1 AV	405	}
f62e52d1 DH	406	/* Flags for iov_iter_get/extract_pages() /
	407	/* Allow P2PDMA on the extracted pages */
	408	#define ITER_ALLOW_P2PDMA ((__force iov_iter_extraction_t)0x01)
	409
7d58fe73 DH	410	ssize_t iov_iter_extract_pages(struct iov_iter i, struct page **pages,
	411	size_t maxsize, unsigned int maxpages,
	412	iov_iter_extraction_t extraction_flags,
	413	size_t *offset0);
	414
	415	/**
	416	* iov_iter_extract_will_pin - Indicate how pages from the iterator will be retained
	417	* @iter: The iterator
	418	*
	419	* Examine the iterator and indicate by returning true or false as to how, if
	420	* at all, pages extracted from the iterator will be retained by the extraction
	421	* function.
	422	*
	423	* %true indicates that the pages will have a pin placed in them that the
	424	* caller must unpin. This is must be done for DMA/async DIO to force fork()
	425	* to forcibly copy a page for the child (the parent must retain the original
	426	* page).
	427	*
	428	* %false indicates that no measures are taken and that it's up to the caller
	429	* to retain the pages.
	430	*/
	431	static inline bool iov_iter_extract_will_pin(const struct iov_iter *iter)
	432	{
	433	return user_backed_iter(iter);
	434	}
fcb14cb1	435
812ed032	436	#endif