[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;
	};
	size_t count;
	union {
		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;
	};
};

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;
}

static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
{
	return (struct iovec) {
		.iov_base = iter->iov->iov_base + iter->iov_offset,
		.iov_len = min(iter->count,
			       iter->iov->iov_len - iter->iov_offset),
	};
}

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 AV	53	union {
62a8067a AV	54	const struct iovec *iov;
a280455f	55	const struct kvec *kvec;
62a8067a	56	const struct bio_vec *bvec;
7ff50620	57	struct xarray *xarray;
241699cd	58	struct pipe_inode_info *pipe;
fcb14cb1	59	void __user *ubuf;
241699cd AV	60	};
	61	union {
	62	unsigned long nr_segs;
27c0e374	63	struct {
8cefc107 DH	64	unsigned int head;
8cefc107 DH	65	unsigned int start_head;
27c0e374	66	};
7ff50620	67	loff_t xarray_start;
62a8067a	68	};
92236878 KO	69	};
92236878 KO	70
00e23707 DH	71	static inline enum iter_type iov_iter_type(const struct iov_iter *i)
00e23707 DH	72	{
8cd54c1c	73	return i->iter_type;
00e23707 DH	74	}
00e23707 DH	75
8fb0f47a JA	76	static inline void iov_iter_save_state(struct iov_iter *iter,
	77	struct iov_iter_state *state)
	78	{
	79	state->iov_offset = iter->iov_offset;
	80	state->count = iter->count;
	81	state->nr_segs = iter->nr_segs;
	82	}
	83
fcb14cb1 AV	84	static inline bool iter_is_ubuf(const struct iov_iter *i)
	85	{
	86	return iov_iter_type(i) == ITER_UBUF;
	87	}
	88
00e23707 DH	89	static inline bool iter_is_iovec(const struct iov_iter *i)
	90	{
	91	return iov_iter_type(i) == ITER_IOVEC;
	92	}
	93
	94	static inline bool iov_iter_is_kvec(const struct iov_iter *i)
	95	{
	96	return iov_iter_type(i) == ITER_KVEC;
	97	}
	98
	99	static inline bool iov_iter_is_bvec(const struct iov_iter *i)
	100	{
	101	return iov_iter_type(i) == ITER_BVEC;
	102	}
	103
	104	static inline bool iov_iter_is_pipe(const struct iov_iter *i)
	105	{
	106	return iov_iter_type(i) == ITER_PIPE;
	107	}
	108
9ea9ce04 DH	109	static inline bool iov_iter_is_discard(const struct iov_iter *i)
	110	{
	111	return iov_iter_type(i) == ITER_DISCARD;
	112	}
	113
7ff50620 DH	114	static inline bool iov_iter_is_xarray(const struct iov_iter *i)
	115	{
	116	return iov_iter_type(i) == ITER_XARRAY;
	117	}
	118
00e23707 DH	119	static inline unsigned char iov_iter_rw(const struct iov_iter *i)
00e23707 DH	120	{
8cd54c1c	121	return i->data_source ? WRITE : READ;
00e23707 DH	122	}
00e23707 DH	123
fcb14cb1 AV	124	static inline bool user_backed_iter(const struct iov_iter *i)
	125	{
	126	return i->user_backed;
	127	}
	128
1da177e4 LT	129	/*
	130	* Total number of bytes covered by an iovec.
	131	*
	132	* NOTE that it is not safe to use this function until all the iovec's
	133	* segment lengths have been validated. Because the individual lengths can
	134	* overflow a size_t when added together.
	135	*/
	136	static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
	137	{
	138	unsigned long seg;
	139	size_t ret = 0;
	140
	141	for (seg = 0; seg < nr_segs; seg++)
	142	ret += iov[seg].iov_len;
	143	return ret;
	144	}
	145
92236878 KO	146	static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
	147	{
	148	return (struct iovec) {
	149	.iov_base = iter->iov->iov_base + iter->iov_offset,
	150	.iov_len = min(iter->count,
	151	iter->iov->iov_len - iter->iov_offset),
	152	};
	153	}
	154
f0b65f39 AV	155	size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
f0b65f39 AV	156	size_t bytes, struct iov_iter *i);
92236878	157	void iov_iter_advance(struct iov_iter *i, size_t bytes);
27c0e374	158	void iov_iter_revert(struct iov_iter *i, size_t bytes);
a6294593	159	size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
cdd591fc	160	size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
92236878	161	size_t iov_iter_single_seg_count(const struct iov_iter *i);
6e58e79d AV	162	size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
6e58e79d AV	163	struct iov_iter *i);
f0d1bec9 AV	164	size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
f0d1bec9 AV	165	struct iov_iter *i);
aa28de27 AV	166
	167	size_t _copy_to_iter(const void addr, size_t bytes, struct iov_iter i);
	168	size_t _copy_from_iter(void addr, size_t bytes, struct iov_iter i);
aa28de27	169	size_t _copy_from_iter_nocache(void addr, size_t bytes, struct iov_iter i);
aa28de27	170
d9c19d32 MWO	171	static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
	172	size_t bytes, struct iov_iter *i)
	173	{
	174	return copy_page_to_iter(&folio->page, offset, bytes, i);
	175	}
	176
aa28de27 AV	177	static __always_inline __must_check
	178	size_t copy_to_iter(const void addr, size_t bytes, struct iov_iter i)
	179	{
0e3c3b90	180	if (check_copy_size(addr, bytes, true))
aa28de27	181	return _copy_to_iter(addr, bytes, i);
0e3c3b90	182	return 0;
aa28de27 AV	183	}
	184
	185	static __always_inline __must_check
	186	size_t copy_from_iter(void addr, size_t bytes, struct iov_iter i)
	187	{
0e3c3b90	188	if (check_copy_size(addr, bytes, false))
aa28de27	189	return _copy_from_iter(addr, bytes, i);
0e3c3b90	190	return 0;
aa28de27 AV	191	}
	192
	193	static __always_inline __must_check
	194	bool copy_from_iter_full(void addr, size_t bytes, struct iov_iter i)
	195	{
4b6c132b AV	196	size_t copied = copy_from_iter(addr, bytes, i);
	197	if (likely(copied == bytes))
	198	return true;
	199	iov_iter_revert(i, copied);
	200	return false;
aa28de27 AV	201	}
	202
	203	static __always_inline __must_check
	204	size_t copy_from_iter_nocache(void addr, size_t bytes, struct iov_iter i)
	205	{
0e3c3b90	206	if (check_copy_size(addr, bytes, false))
aa28de27	207	return _copy_from_iter_nocache(addr, bytes, i);
0e3c3b90	208	return 0;
aa28de27 AV	209	}
	210
	211	static __always_inline __must_check
	212	bool copy_from_iter_full_nocache(void addr, size_t bytes, struct iov_iter i)
	213	{
4b6c132b AV	214	size_t copied = copy_from_iter_nocache(addr, bytes, i);
	215	if (likely(copied == bytes))
	216	return true;
	217	iov_iter_revert(i, copied);
	218	return false;
aa28de27 AV	219	}
aa28de27 AV	220
0aed55af DW	221	#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
	222	/*
	223	* Note, users like pmem that depend on the stricter semantics of
e17f7a0b	224	* _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
0aed55af DW	225	* IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
	226	* destination is flushed from the cache on return.
	227	*/
6a37e940	228	size_t _copy_from_iter_flushcache(void addr, size_t bytes, struct iov_iter i);
0aed55af	229	#else
6a37e940 LT	230	#define _copy_from_iter_flushcache _copy_from_iter_nocache
	231	#endif
	232
ec6347bb DW	233	#ifdef CONFIG_ARCH_HAS_COPY_MC
ec6347bb DW	234	size_t _copy_mc_to_iter(const void addr, size_t bytes, struct iov_iter i);
8780356e	235	#else
ec6347bb	236	#define _copy_mc_to_iter _copy_to_iter
8780356e DW	237	#endif
8780356e DW	238
c35e0248	239	size_t iov_iter_zero(size_t bytes, struct iov_iter *);
cfa320f7 KB	240	bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
cfa320f7 KB	241	unsigned len_mask);
886a3911	242	unsigned long iov_iter_alignment(const struct iov_iter *i);
357f435d	243	unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
aa563d7b	244	void iov_iter_init(struct iov_iter i, unsigned int direction, const struct iovec iov,
71d8e532	245	unsigned long nr_segs, size_t count);
aa563d7b	246	void iov_iter_kvec(struct iov_iter i, unsigned int direction, const struct kvec kvec,
05afcb77	247	unsigned long nr_segs, size_t count);
aa563d7b	248	void iov_iter_bvec(struct iov_iter i, unsigned int direction, const struct bio_vec bvec,
abb78f87	249	unsigned long nr_segs, size_t count);
aa563d7b	250	void iov_iter_pipe(struct iov_iter i, unsigned int direction, struct pipe_inode_info pipe,
241699cd	251	size_t count);
9ea9ce04	252	void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
7ff50620 DH	253	void iov_iter_xarray(struct iov_iter i, unsigned int direction, struct xarray xarray,
7ff50620 DH	254	loff_t start, size_t count);
d8207640 LG	255	ssize_t iov_iter_get_pages(struct iov_iter i, struct page *pages,
d8207640 LG	256	size_t maxsize, unsigned maxpages, size_t *start,
f62e52d1	257	iov_iter_extraction_t extraction_flags);
eba2d3d7	258	ssize_t iov_iter_get_pages2(struct iov_iter i, struct page *pages,
2c80929c	259	size_t maxsize, unsigned maxpages, size_t *start);
d8207640 LG	260	ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
d8207640 LG	261	struct page **pages, size_t maxsize, size_t start,
f62e52d1	262	iov_iter_extraction_t extraction_flags);
eba2d3d7	263	ssize_t iov_iter_get_pages_alloc2(struct iov_iter i, struct page **pages,
91f79c43	264	size_t maxsize, size_t *start);
f67da30c	265	int iov_iter_npages(const struct iov_iter *i, int maxpages);
8fb0f47a	266	void iov_iter_restore(struct iov_iter i, struct iov_iter_state state);
92236878	267
4b8164b9 AV	268	const void dup_iter(struct iov_iter new, struct iov_iter *old, gfp_t flags);
4b8164b9 AV	269
b57332b4	270	static inline size_t iov_iter_count(const struct iov_iter *i)
92236878 KO	271	{
	272	return i->count;
	273	}
	274
0b86dbf6 AV	275	/*
	276	* Cap the iov_iter by given limit; note that the second argument is
	277	* not the new size - it's upper limit for such. Passing it a value
	278	* greater than the amount of data in iov_iter is fine - it'll just do
	279	* nothing in that case.
	280	*/
	281	static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
0c949334	282	{
0b86dbf6 AV	283	/*
	284	* count doesn't have to fit in size_t - comparison extends both
	285	* operands to u64 here and any value that would be truncated by
	286	* conversion in assignement is by definition greater than all
	287	* values of size_t, including old i->count.
	288	*/
7dedd3e1	289	if (i->count > count)
0c949334 AV	290	i->count = count;
	291	}
	292
b42b15fd AV	293	/*
	294	* reexpand a previously truncated iterator; count must be no more than how much
	295	* we had shrunk it.
	296	*/
	297	static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
	298	{
	299	i->count = count;
	300	}
52cbd23a	301
b93235e6 JK	302	static inline int
	303	iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
	304	{
	305	size_t shorted = 0;
	306	int npages;
	307
	308	if (iov_iter_count(i) > max_bytes) {
	309	shorted = iov_iter_count(i) - max_bytes;
	310	iov_iter_truncate(i, max_bytes);
	311	}
7187440d	312	npages = iov_iter_npages(i, maxpages);
b93235e6 JK	313	if (shorted)
	314	iov_iter_reexpand(i, iov_iter_count(i) + shorted);
	315
	316	return npages;
	317	}
	318
52cbd23a WB	319	struct csum_state {
	320	__wsum csum;
	321	size_t off;
	322	};
	323
	324	size_t csum_and_copy_to_iter(const void addr, size_t bytes, void csstate, struct iov_iter *i);
a604ec7e	325	size_t csum_and_copy_from_iter(void addr, size_t bytes, __wsum csum, struct iov_iter *i);
4b6c132b AV	326
	327	static __always_inline __must_check
	328	bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
	329	__wsum csum, struct iov_iter i)
	330	{
	331	size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
	332	if (likely(copied == bytes))
	333	return true;
	334	iov_iter_revert(i, copied);
	335	return false;
	336	}
d05f4435 SG	337	size_t hash_and_copy_to_iter(const void addr, size_t bytes, void hashp,
d05f4435 SG	338	struct iov_iter *i);
b42b15fd	339
bfdc5970 CH	340	struct iovec iovec_from_user(const struct iovec __user uvector,
	341	unsigned long nr_segs, unsigned long fast_segs,
	342	struct iovec *fast_iov, bool compat);
	343	ssize_t import_iovec(int type, const struct iovec __user *uvec,
	344	unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
	345	struct iov_iter *i);
	346	ssize_t __import_iovec(int type, const struct iovec __user *uvec,
	347	unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
	348	struct iov_iter *i, bool compat);
bc917be8 AV	349	int import_single_range(int type, void __user *buf, size_t len,
bc917be8 AV	350	struct iovec iov, struct iov_iter i);
2ad9bd83	351	int import_ubuf(int type, void __user buf, size_t len, struct iov_iter i);
bc917be8	352
fcb14cb1 AV	353	static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
	354	void __user *buf, size_t count)
	355	{
	356	WARN_ON(direction & ~(READ \| WRITE));
	357	*i = (struct iov_iter) {
	358	.iter_type = ITER_UBUF,
	359	.user_backed = true,
	360	.data_source = direction,
	361	.ubuf = buf,
	362	.count = count
	363	};
	364	}
f62e52d1 DH	365	/* Flags for iov_iter_get/extract_pages() /
	366	/* Allow P2PDMA on the extracted pages */
	367	#define ITER_ALLOW_P2PDMA ((__force iov_iter_extraction_t)0x01)
	368
7d58fe73 DH	369	ssize_t iov_iter_extract_pages(struct iov_iter i, struct page **pages,
	370	size_t maxsize, unsigned int maxpages,
	371	iov_iter_extraction_t extraction_flags,
	372	size_t *offset0);
	373
	374	/**
	375	* iov_iter_extract_will_pin - Indicate how pages from the iterator will be retained
	376	* @iter: The iterator
	377	*
	378	* Examine the iterator and indicate by returning true or false as to how, if
	379	* at all, pages extracted from the iterator will be retained by the extraction
	380	* function.
	381	*
	382	* %true indicates that the pages will have a pin placed in them that the
	383	* caller must unpin. This is must be done for DMA/async DIO to force fork()
	384	* to forcibly copy a page for the child (the parent must retain the original
	385	* page).
	386	*
	387	* %false indicates that no measures are taken and that it's up to the caller
	388	* to retain the pages.
	389	*/
	390	static inline bool iov_iter_extract_will_pin(const struct iov_iter *iter)
	391	{
	392	return user_backed_iter(iter);
	393	}
fcb14cb1	394
812ed032	395	#endif