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