[linux-2.6-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;
	};
	size_t count;
	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;
	};
	union {
		unsigned long nr_segs;
		struct {
			unsigned int head;
			unsigned int start_head;
		};
		loff_t xarray_start;
	};
};

#define iter_iov(iter)	(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);
}

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
	};
}
/* 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	};
92236878	52	size_t count;
62a8067a	53	union {
de4f5fed JA	54	/* use iter_iov() to get the current vec */
de4f5fed JA	55	const struct iovec *__iov;
a280455f	56	const struct kvec *kvec;
62a8067a	57	const struct bio_vec *bvec;
7ff50620	58	struct xarray *xarray;
241699cd	59	struct pipe_inode_info *pipe;
fcb14cb1	60	void __user *ubuf;
241699cd AV	61	};
	62	union {
	63	unsigned long nr_segs;
27c0e374	64	struct {
8cefc107 DH	65	unsigned int head;
8cefc107 DH	66	unsigned int start_head;
27c0e374	67	};
7ff50620	68	loff_t xarray_start;
62a8067a	69	};
92236878 KO	70	};
92236878 KO	71
de4f5fed	72	#define iter_iov(iter) (iter)->__iov
95e49cf8 JA	73	#define iter_iov_addr(iter) (iter_iov(iter)->iov_base + (iter)->iov_offset)
95e49cf8 JA	74	#define iter_iov_len(iter) (iter_iov(iter)->iov_len - (iter)->iov_offset)
de4f5fed	75
00e23707 DH	76	static inline enum iter_type iov_iter_type(const struct iov_iter *i)
00e23707 DH	77	{
8cd54c1c	78	return i->iter_type;
00e23707 DH	79	}
00e23707 DH	80
8fb0f47a JA	81	static inline void iov_iter_save_state(struct iov_iter *iter,
	82	struct iov_iter_state *state)
	83	{
	84	state->iov_offset = iter->iov_offset;
	85	state->count = iter->count;
	86	state->nr_segs = iter->nr_segs;
	87	}
	88
fcb14cb1 AV	89	static inline bool iter_is_ubuf(const struct iov_iter *i)
	90	{
	91	return iov_iter_type(i) == ITER_UBUF;
	92	}
	93
00e23707 DH	94	static inline bool iter_is_iovec(const struct iov_iter *i)
	95	{
	96	return iov_iter_type(i) == ITER_IOVEC;
	97	}
	98
	99	static inline bool iov_iter_is_kvec(const struct iov_iter *i)
	100	{
	101	return iov_iter_type(i) == ITER_KVEC;
	102	}
	103
	104	static inline bool iov_iter_is_bvec(const struct iov_iter *i)
	105	{
	106	return iov_iter_type(i) == ITER_BVEC;
	107	}
	108
	109	static inline bool iov_iter_is_pipe(const struct iov_iter *i)
	110	{
	111	return iov_iter_type(i) == ITER_PIPE;
	112	}
	113
9ea9ce04 DH	114	static inline bool iov_iter_is_discard(const struct iov_iter *i)
	115	{
	116	return iov_iter_type(i) == ITER_DISCARD;
	117	}
	118
7ff50620 DH	119	static inline bool iov_iter_is_xarray(const struct iov_iter *i)
	120	{
	121	return iov_iter_type(i) == ITER_XARRAY;
	122	}
	123
00e23707 DH	124	static inline unsigned char iov_iter_rw(const struct iov_iter *i)
00e23707 DH	125	{
8cd54c1c	126	return i->data_source ? WRITE : READ;
00e23707 DH	127	}
00e23707 DH	128
fcb14cb1 AV	129	static inline bool user_backed_iter(const struct iov_iter *i)
	130	{
	131	return i->user_backed;
	132	}
	133
1da177e4 LT	134	/*
	135	* Total number of bytes covered by an iovec.
	136	*
	137	* NOTE that it is not safe to use this function until all the iovec's
	138	* segment lengths have been validated. Because the individual lengths can
	139	* overflow a size_t when added together.
	140	*/
	141	static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
	142	{
	143	unsigned long seg;
	144	size_t ret = 0;
	145
	146	for (seg = 0; seg < nr_segs; seg++)
	147	ret += iov[seg].iov_len;
	148	return ret;
	149	}
	150
f0b65f39 AV	151	size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
f0b65f39 AV	152	size_t bytes, struct iov_iter *i);
92236878	153	void iov_iter_advance(struct iov_iter *i, size_t bytes);
27c0e374	154	void iov_iter_revert(struct iov_iter *i, size_t bytes);
a6294593	155	size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
cdd591fc	156	size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
92236878	157	size_t iov_iter_single_seg_count(const struct iov_iter *i);
6e58e79d AV	158	size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
6e58e79d AV	159	struct iov_iter *i);
f0d1bec9 AV	160	size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
f0d1bec9 AV	161	struct iov_iter *i);
aa28de27 AV	162
	163	size_t _copy_to_iter(const void addr, size_t bytes, struct iov_iter i);
	164	size_t _copy_from_iter(void addr, size_t bytes, struct iov_iter i);
aa28de27	165	size_t _copy_from_iter_nocache(void addr, size_t bytes, struct iov_iter i);
aa28de27	166
d9c19d32 MWO	167	static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
	168	size_t bytes, struct iov_iter *i)
	169	{
	170	return copy_page_to_iter(&folio->page, offset, bytes, i);
	171	}
	172
aa28de27 AV	173	static __always_inline __must_check
	174	size_t copy_to_iter(const void addr, size_t bytes, struct iov_iter i)
	175	{
0e3c3b90	176	if (check_copy_size(addr, bytes, true))
aa28de27	177	return _copy_to_iter(addr, bytes, i);
0e3c3b90	178	return 0;
aa28de27 AV	179	}
	180
	181	static __always_inline __must_check
	182	size_t copy_from_iter(void addr, size_t bytes, struct iov_iter i)
	183	{
0e3c3b90	184	if (check_copy_size(addr, bytes, false))
aa28de27	185	return _copy_from_iter(addr, bytes, i);
0e3c3b90	186	return 0;
aa28de27 AV	187	}
	188
	189	static __always_inline __must_check
	190	bool copy_from_iter_full(void addr, size_t bytes, struct iov_iter i)
	191	{
4b6c132b AV	192	size_t copied = copy_from_iter(addr, bytes, i);
	193	if (likely(copied == bytes))
	194	return true;
	195	iov_iter_revert(i, copied);
	196	return false;
aa28de27 AV	197	}
	198
	199	static __always_inline __must_check
	200	size_t copy_from_iter_nocache(void addr, size_t bytes, struct iov_iter i)
	201	{
0e3c3b90	202	if (check_copy_size(addr, bytes, false))
aa28de27	203	return _copy_from_iter_nocache(addr, bytes, i);
0e3c3b90	204	return 0;
aa28de27 AV	205	}
	206
	207	static __always_inline __must_check
	208	bool copy_from_iter_full_nocache(void addr, size_t bytes, struct iov_iter i)
	209	{
4b6c132b AV	210	size_t copied = copy_from_iter_nocache(addr, bytes, i);
	211	if (likely(copied == bytes))
	212	return true;
	213	iov_iter_revert(i, copied);
	214	return false;
aa28de27 AV	215	}
aa28de27 AV	216
0aed55af DW	217	#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
	218	/*
	219	* Note, users like pmem that depend on the stricter semantics of
e17f7a0b	220	* _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
0aed55af DW	221	* IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
	222	* destination is flushed from the cache on return.
	223	*/
6a37e940	224	size_t _copy_from_iter_flushcache(void addr, size_t bytes, struct iov_iter i);
0aed55af	225	#else
6a37e940 LT	226	#define _copy_from_iter_flushcache _copy_from_iter_nocache
	227	#endif
	228
ec6347bb DW	229	#ifdef CONFIG_ARCH_HAS_COPY_MC
ec6347bb DW	230	size_t _copy_mc_to_iter(const void addr, size_t bytes, struct iov_iter i);
8780356e	231	#else
ec6347bb	232	#define _copy_mc_to_iter _copy_to_iter
8780356e DW	233	#endif
8780356e DW	234
c35e0248	235	size_t iov_iter_zero(size_t bytes, struct iov_iter *);
cfa320f7 KB	236	bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
cfa320f7 KB	237	unsigned len_mask);
886a3911	238	unsigned long iov_iter_alignment(const struct iov_iter *i);
357f435d	239	unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
aa563d7b	240	void iov_iter_init(struct iov_iter i, unsigned int direction, const struct iovec iov,
71d8e532	241	unsigned long nr_segs, size_t count);
aa563d7b	242	void iov_iter_kvec(struct iov_iter i, unsigned int direction, const struct kvec kvec,
05afcb77	243	unsigned long nr_segs, size_t count);
aa563d7b	244	void iov_iter_bvec(struct iov_iter i, unsigned int direction, const struct bio_vec bvec,
abb78f87	245	unsigned long nr_segs, size_t count);
aa563d7b	246	void iov_iter_pipe(struct iov_iter i, unsigned int direction, struct pipe_inode_info pipe,
241699cd	247	size_t count);
9ea9ce04	248	void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
7ff50620 DH	249	void iov_iter_xarray(struct iov_iter i, unsigned int direction, struct xarray xarray,
7ff50620 DH	250	loff_t start, size_t count);
d8207640 LG	251	ssize_t iov_iter_get_pages(struct iov_iter i, struct page *pages,
d8207640 LG	252	size_t maxsize, unsigned maxpages, size_t *start,
f62e52d1	253	iov_iter_extraction_t extraction_flags);
eba2d3d7	254	ssize_t iov_iter_get_pages2(struct iov_iter i, struct page *pages,
2c80929c	255	size_t maxsize, unsigned maxpages, size_t *start);
d8207640 LG	256	ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
d8207640 LG	257	struct page **pages, size_t maxsize, size_t start,
f62e52d1	258	iov_iter_extraction_t extraction_flags);
eba2d3d7	259	ssize_t iov_iter_get_pages_alloc2(struct iov_iter i, struct page **pages,
91f79c43	260	size_t maxsize, size_t *start);
f67da30c	261	int iov_iter_npages(const struct iov_iter *i, int maxpages);
8fb0f47a	262	void iov_iter_restore(struct iov_iter i, struct iov_iter_state state);
92236878	263
4b8164b9 AV	264	const void dup_iter(struct iov_iter new, struct iov_iter *old, gfp_t flags);
4b8164b9 AV	265
b57332b4	266	static inline size_t iov_iter_count(const struct iov_iter *i)
92236878 KO	267	{
	268	return i->count;
	269	}
	270
0b86dbf6 AV	271	/*
	272	* Cap the iov_iter by given limit; note that the second argument is
	273	* not the new size - it's upper limit for such. Passing it a value
	274	* greater than the amount of data in iov_iter is fine - it'll just do
	275	* nothing in that case.
	276	*/
	277	static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
0c949334	278	{
0b86dbf6 AV	279	/*
	280	* count doesn't have to fit in size_t - comparison extends both
	281	* operands to u64 here and any value that would be truncated by
	282	* conversion in assignement is by definition greater than all
	283	* values of size_t, including old i->count.
	284	*/
7dedd3e1	285	if (i->count > count)
0c949334 AV	286	i->count = count;
	287	}
	288
b42b15fd AV	289	/*
	290	* reexpand a previously truncated iterator; count must be no more than how much
	291	* we had shrunk it.
	292	*/
	293	static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
	294	{
	295	i->count = count;
	296	}
52cbd23a	297
b93235e6 JK	298	static inline int
	299	iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
	300	{
	301	size_t shorted = 0;
	302	int npages;
	303
	304	if (iov_iter_count(i) > max_bytes) {
	305	shorted = iov_iter_count(i) - max_bytes;
	306	iov_iter_truncate(i, max_bytes);
	307	}
7187440d	308	npages = iov_iter_npages(i, maxpages);
b93235e6 JK	309	if (shorted)
	310	iov_iter_reexpand(i, iov_iter_count(i) + shorted);
	311
	312	return npages;
	313	}
	314
52cbd23a WB	315	struct csum_state {
	316	__wsum csum;
	317	size_t off;
	318	};
	319
	320	size_t csum_and_copy_to_iter(const void addr, size_t bytes, void csstate, struct iov_iter *i);
a604ec7e	321	size_t csum_and_copy_from_iter(void addr, size_t bytes, __wsum csum, struct iov_iter *i);
4b6c132b AV	322
	323	static __always_inline __must_check
	324	bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
	325	__wsum csum, struct iov_iter i)
	326	{
	327	size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
	328	if (likely(copied == bytes))
	329	return true;
	330	iov_iter_revert(i, copied);
	331	return false;
	332	}
d05f4435 SG	333	size_t hash_and_copy_to_iter(const void addr, size_t bytes, void hashp,
d05f4435 SG	334	struct iov_iter *i);
b42b15fd	335
bfdc5970 CH	336	struct iovec iovec_from_user(const struct iovec __user uvector,
	337	unsigned long nr_segs, unsigned long fast_segs,
	338	struct iovec *fast_iov, bool compat);
	339	ssize_t import_iovec(int type, const struct iovec __user *uvec,
	340	unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
	341	struct iov_iter *i);
	342	ssize_t __import_iovec(int type, const struct iovec __user *uvec,
	343	unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
	344	struct iov_iter *i, bool compat);
bc917be8 AV	345	int import_single_range(int type, void __user *buf, size_t len,
bc917be8 AV	346	struct iovec iov, struct iov_iter i);
2ad9bd83	347	int import_ubuf(int type, void __user buf, size_t len, struct iov_iter i);
bc917be8	348
fcb14cb1 AV	349	static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
	350	void __user *buf, size_t count)
	351	{
	352	WARN_ON(direction & ~(READ \| WRITE));
	353	*i = (struct iov_iter) {
	354	.iter_type = ITER_UBUF,
	355	.user_backed = true,
	356	.data_source = direction,
	357	.ubuf = buf,
	358	.count = count
	359	};
	360	}
f62e52d1 DH	361	/* Flags for iov_iter_get/extract_pages() /
	362	/* Allow P2PDMA on the extracted pages */
	363	#define ITER_ALLOW_P2PDMA ((__force iov_iter_extraction_t)0x01)
	364
7d58fe73 DH	365	ssize_t iov_iter_extract_pages(struct iov_iter i, struct page **pages,
	366	size_t maxsize, unsigned int maxpages,
	367	iov_iter_extraction_t extraction_flags,
	368	size_t *offset0);
	369
	370	/**
	371	* iov_iter_extract_will_pin - Indicate how pages from the iterator will be retained
	372	* @iter: The iterator
	373	*
	374	* Examine the iterator and indicate by returning true or false as to how, if
	375	* at all, pages extracted from the iterator will be retained by the extraction
	376	* function.
	377	*
	378	* %true indicates that the pages will have a pin placed in them that the
	379	* caller must unpin. This is must be done for DMA/async DIO to force fork()
	380	* to forcibly copy a page for the child (the parent must retain the original
	381	* page).
	382	*
	383	* %false indicates that no measures are taken and that it's up to the caller
	384	* to retain the pages.
	385	*/
	386	static inline bool iov_iter_extract_will_pin(const struct iov_iter *iter)
	387	{
	388	return user_backed_iter(iter);
	389	}
fcb14cb1	390
812ed032	391	#endif