[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;

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,
};

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_pages2(struct iov_iter *i, struct page **pages,
			size_t maxsize, unsigned maxpages, size_t *start);
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, INT_MAX);
	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);

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
	};
}

#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 JS	15
	16	struct kvec {
	17	void iov_base; / and that should never hold a userland pointer */
	18	size_t iov_len;
	19	};
	20
00e23707	21	enum iter_type {
875f1d07	22	/* iter types */
8cd54c1c AV	23	ITER_IOVEC,
	24	ITER_KVEC,
	25	ITER_BVEC,
	26	ITER_PIPE,
	27	ITER_XARRAY,
	28	ITER_DISCARD,
fcb14cb1	29	ITER_UBUF,
62a8067a AV	30	};
62a8067a AV	31
8fb0f47a JA	32	struct iov_iter_state {
	33	size_t iov_offset;
	34	size_t count;
	35	unsigned long nr_segs;
	36	};
	37
92236878	38	struct iov_iter {
8cd54c1c	39	u8 iter_type;
3337ab08	40	bool nofault;
8cd54c1c	41	bool data_source;
fcb14cb1	42	bool user_backed;
10f525a8 AV	43	union {
	44	size_t iov_offset;
	45	int last_offset;
	46	};
92236878	47	size_t count;
62a8067a AV	48	union {
62a8067a AV	49	const struct iovec *iov;
a280455f	50	const struct kvec *kvec;
62a8067a	51	const struct bio_vec *bvec;
7ff50620	52	struct xarray *xarray;
241699cd	53	struct pipe_inode_info *pipe;
fcb14cb1	54	void __user *ubuf;
241699cd AV	55	};
	56	union {
	57	unsigned long nr_segs;
27c0e374	58	struct {
8cefc107 DH	59	unsigned int head;
8cefc107 DH	60	unsigned int start_head;
27c0e374	61	};
7ff50620	62	loff_t xarray_start;
62a8067a	63	};
92236878 KO	64	};
92236878 KO	65
00e23707 DH	66	static inline enum iter_type iov_iter_type(const struct iov_iter *i)
00e23707 DH	67	{
8cd54c1c	68	return i->iter_type;
00e23707 DH	69	}
00e23707 DH	70
8fb0f47a JA	71	static inline void iov_iter_save_state(struct iov_iter *iter,
	72	struct iov_iter_state *state)
	73	{
	74	state->iov_offset = iter->iov_offset;
	75	state->count = iter->count;
	76	state->nr_segs = iter->nr_segs;
	77	}
	78
fcb14cb1 AV	79	static inline bool iter_is_ubuf(const struct iov_iter *i)
	80	{
	81	return iov_iter_type(i) == ITER_UBUF;
	82	}
	83
00e23707 DH	84	static inline bool iter_is_iovec(const struct iov_iter *i)
	85	{
	86	return iov_iter_type(i) == ITER_IOVEC;
	87	}
	88
	89	static inline bool iov_iter_is_kvec(const struct iov_iter *i)
	90	{
	91	return iov_iter_type(i) == ITER_KVEC;
	92	}
	93
	94	static inline bool iov_iter_is_bvec(const struct iov_iter *i)
	95	{
	96	return iov_iter_type(i) == ITER_BVEC;
	97	}
	98
	99	static inline bool iov_iter_is_pipe(const struct iov_iter *i)
	100	{
	101	return iov_iter_type(i) == ITER_PIPE;
	102	}
	103
9ea9ce04 DH	104	static inline bool iov_iter_is_discard(const struct iov_iter *i)
	105	{
	106	return iov_iter_type(i) == ITER_DISCARD;
	107	}
	108
7ff50620 DH	109	static inline bool iov_iter_is_xarray(const struct iov_iter *i)
	110	{
	111	return iov_iter_type(i) == ITER_XARRAY;
	112	}
	113
00e23707 DH	114	static inline unsigned char iov_iter_rw(const struct iov_iter *i)
00e23707 DH	115	{
8cd54c1c	116	return i->data_source ? WRITE : READ;
00e23707 DH	117	}
00e23707 DH	118
fcb14cb1 AV	119	static inline bool user_backed_iter(const struct iov_iter *i)
	120	{
	121	return i->user_backed;
	122	}
	123
1da177e4 LT	124	/*
	125	* Total number of bytes covered by an iovec.
	126	*
	127	* NOTE that it is not safe to use this function until all the iovec's
	128	* segment lengths have been validated. Because the individual lengths can
	129	* overflow a size_t when added together.
	130	*/
	131	static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
	132	{
	133	unsigned long seg;
	134	size_t ret = 0;
	135
	136	for (seg = 0; seg < nr_segs; seg++)
	137	ret += iov[seg].iov_len;
	138	return ret;
	139	}
	140
92236878 KO	141	static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
	142	{
	143	return (struct iovec) {
	144	.iov_base = iter->iov->iov_base + iter->iov_offset,
	145	.iov_len = min(iter->count,
	146	iter->iov->iov_len - iter->iov_offset),
	147	};
	148	}
	149
f0b65f39 AV	150	size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
f0b65f39 AV	151	size_t bytes, struct iov_iter *i);
92236878	152	void iov_iter_advance(struct iov_iter *i, size_t bytes);
27c0e374	153	void iov_iter_revert(struct iov_iter *i, size_t bytes);
a6294593	154	size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
cdd591fc	155	size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
92236878	156	size_t iov_iter_single_seg_count(const struct iov_iter *i);
6e58e79d AV	157	size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
6e58e79d AV	158	struct iov_iter *i);
f0d1bec9 AV	159	size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
f0d1bec9 AV	160	struct iov_iter *i);
aa28de27 AV	161
	162	size_t _copy_to_iter(const void addr, size_t bytes, struct iov_iter i);
	163	size_t _copy_from_iter(void addr, size_t bytes, struct iov_iter i);
aa28de27	164	size_t _copy_from_iter_nocache(void addr, size_t bytes, struct iov_iter i);
aa28de27	165
d9c19d32 MWO	166	static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
	167	size_t bytes, struct iov_iter *i)
	168	{
	169	return copy_page_to_iter(&folio->page, offset, bytes, i);
	170	}
	171
aa28de27 AV	172	static __always_inline __must_check
	173	size_t copy_to_iter(const void addr, size_t bytes, struct iov_iter i)
	174	{
0e3c3b90	175	if (check_copy_size(addr, bytes, true))
aa28de27	176	return _copy_to_iter(addr, bytes, i);
0e3c3b90	177	return 0;
aa28de27 AV	178	}
	179
	180	static __always_inline __must_check
	181	size_t copy_from_iter(void addr, size_t bytes, struct iov_iter i)
	182	{
0e3c3b90	183	if (check_copy_size(addr, bytes, false))
aa28de27	184	return _copy_from_iter(addr, bytes, i);
0e3c3b90	185	return 0;
aa28de27 AV	186	}
	187
	188	static __always_inline __must_check
	189	bool copy_from_iter_full(void addr, size_t bytes, struct iov_iter i)
	190	{
4b6c132b AV	191	size_t copied = copy_from_iter(addr, bytes, i);
	192	if (likely(copied == bytes))
	193	return true;
	194	iov_iter_revert(i, copied);
	195	return false;
aa28de27 AV	196	}
	197
	198	static __always_inline __must_check
	199	size_t copy_from_iter_nocache(void addr, size_t bytes, struct iov_iter i)
	200	{
0e3c3b90	201	if (check_copy_size(addr, bytes, false))
aa28de27	202	return _copy_from_iter_nocache(addr, bytes, i);
0e3c3b90	203	return 0;
aa28de27 AV	204	}
	205
	206	static __always_inline __must_check
	207	bool copy_from_iter_full_nocache(void addr, size_t bytes, struct iov_iter i)
	208	{
4b6c132b AV	209	size_t copied = copy_from_iter_nocache(addr, bytes, i);
	210	if (likely(copied == bytes))
	211	return true;
	212	iov_iter_revert(i, copied);
	213	return false;
aa28de27 AV	214	}
aa28de27 AV	215
0aed55af DW	216	#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
	217	/*
	218	* Note, users like pmem that depend on the stricter semantics of
e17f7a0b	219	* _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
0aed55af DW	220	* IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
	221	* destination is flushed from the cache on return.
	222	*/
6a37e940	223	size_t _copy_from_iter_flushcache(void addr, size_t bytes, struct iov_iter i);
0aed55af	224	#else
6a37e940 LT	225	#define _copy_from_iter_flushcache _copy_from_iter_nocache
	226	#endif
	227
ec6347bb DW	228	#ifdef CONFIG_ARCH_HAS_COPY_MC
ec6347bb DW	229	size_t _copy_mc_to_iter(const void addr, size_t bytes, struct iov_iter i);
8780356e	230	#else
ec6347bb	231	#define _copy_mc_to_iter _copy_to_iter
8780356e DW	232	#endif
8780356e DW	233
c35e0248	234	size_t iov_iter_zero(size_t bytes, struct iov_iter *);
cfa320f7 KB	235	bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
cfa320f7 KB	236	unsigned len_mask);
886a3911	237	unsigned long iov_iter_alignment(const struct iov_iter *i);
357f435d	238	unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
aa563d7b	239	void iov_iter_init(struct iov_iter i, unsigned int direction, const struct iovec iov,
71d8e532	240	unsigned long nr_segs, size_t count);
aa563d7b	241	void iov_iter_kvec(struct iov_iter i, unsigned int direction, const struct kvec kvec,
05afcb77	242	unsigned long nr_segs, size_t count);
aa563d7b	243	void iov_iter_bvec(struct iov_iter i, unsigned int direction, const struct bio_vec bvec,
abb78f87	244	unsigned long nr_segs, size_t count);
aa563d7b	245	void iov_iter_pipe(struct iov_iter i, unsigned int direction, struct pipe_inode_info pipe,
241699cd	246	size_t count);
9ea9ce04	247	void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
7ff50620 DH	248	void iov_iter_xarray(struct iov_iter i, unsigned int direction, struct xarray xarray,
7ff50620 DH	249	loff_t start, size_t count);
eba2d3d7	250	ssize_t iov_iter_get_pages2(struct iov_iter i, struct page *pages,
2c80929c	251	size_t maxsize, unsigned maxpages, size_t *start);
eba2d3d7	252	ssize_t iov_iter_get_pages_alloc2(struct iov_iter i, struct page **pages,
91f79c43	253	size_t maxsize, size_t *start);
f67da30c	254	int iov_iter_npages(const struct iov_iter *i, int maxpages);
8fb0f47a	255	void iov_iter_restore(struct iov_iter i, struct iov_iter_state state);
92236878	256
4b8164b9 AV	257	const void dup_iter(struct iov_iter new, struct iov_iter *old, gfp_t flags);
4b8164b9 AV	258
b57332b4	259	static inline size_t iov_iter_count(const struct iov_iter *i)
92236878 KO	260	{
	261	return i->count;
	262	}
	263
0b86dbf6 AV	264	/*
	265	* Cap the iov_iter by given limit; note that the second argument is
	266	* not the new size - it's upper limit for such. Passing it a value
	267	* greater than the amount of data in iov_iter is fine - it'll just do
	268	* nothing in that case.
	269	*/
	270	static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
0c949334	271	{
0b86dbf6 AV	272	/*
	273	* count doesn't have to fit in size_t - comparison extends both
	274	* operands to u64 here and any value that would be truncated by
	275	* conversion in assignement is by definition greater than all
	276	* values of size_t, including old i->count.
	277	*/
7dedd3e1	278	if (i->count > count)
0c949334 AV	279	i->count = count;
	280	}
	281
b42b15fd AV	282	/*
	283	* reexpand a previously truncated iterator; count must be no more than how much
	284	* we had shrunk it.
	285	*/
	286	static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
	287	{
	288	i->count = count;
	289	}
52cbd23a	290
b93235e6 JK	291	static inline int
	292	iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
	293	{
	294	size_t shorted = 0;
	295	int npages;
	296
	297	if (iov_iter_count(i) > max_bytes) {
	298	shorted = iov_iter_count(i) - max_bytes;
	299	iov_iter_truncate(i, max_bytes);
	300	}
	301	npages = iov_iter_npages(i, INT_MAX);
	302	if (shorted)
	303	iov_iter_reexpand(i, iov_iter_count(i) + shorted);
	304
	305	return npages;
	306	}
	307
52cbd23a WB	308	struct csum_state {
	309	__wsum csum;
	310	size_t off;
	311	};
	312
	313	size_t csum_and_copy_to_iter(const void addr, size_t bytes, void csstate, struct iov_iter *i);
a604ec7e	314	size_t csum_and_copy_from_iter(void addr, size_t bytes, __wsum csum, struct iov_iter *i);
4b6c132b AV	315
	316	static __always_inline __must_check
	317	bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
	318	__wsum csum, struct iov_iter i)
	319	{
	320	size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
	321	if (likely(copied == bytes))
	322	return true;
	323	iov_iter_revert(i, copied);
	324	return false;
	325	}
d05f4435 SG	326	size_t hash_and_copy_to_iter(const void addr, size_t bytes, void hashp,
d05f4435 SG	327	struct iov_iter *i);
b42b15fd	328
bfdc5970 CH	329	struct iovec iovec_from_user(const struct iovec __user uvector,
	330	unsigned long nr_segs, unsigned long fast_segs,
	331	struct iovec *fast_iov, bool compat);
	332	ssize_t import_iovec(int type, const struct iovec __user *uvec,
	333	unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
	334	struct iov_iter *i);
	335	ssize_t __import_iovec(int type, const struct iovec __user *uvec,
	336	unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
	337	struct iov_iter *i, bool compat);
bc917be8 AV	338	int import_single_range(int type, void __user *buf, size_t len,
	339	struct iovec iov, struct iov_iter i);
	340
fcb14cb1 AV	341	static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
	342	void __user *buf, size_t count)
	343	{
	344	WARN_ON(direction & ~(READ \| WRITE));
	345	*i = (struct iov_iter) {
	346	.iter_type = ITER_UBUF,
	347	.user_backed = true,
	348	.data_source = direction,
	349	.ubuf = buf,
	350	.count = count
	351	};
	352	}
	353
812ed032	354	#endif