[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,
};

#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,
		unsigned gup_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,
		unsigned gup_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);

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
de4eda9d AV	32	#define ITER_SOURCE 1 // == WRITE
	33	#define ITER_DEST 0 // == READ
	34
8fb0f47a JA	35	struct iov_iter_state {
	36	size_t iov_offset;
	37	size_t count;
	38	unsigned long nr_segs;
	39	};
	40
92236878	41	struct iov_iter {
8cd54c1c	42	u8 iter_type;
3337ab08	43	bool nofault;
8cd54c1c	44	bool data_source;
fcb14cb1	45	bool user_backed;
10f525a8 AV	46	union {
	47	size_t iov_offset;
	48	int last_offset;
	49	};
92236878	50	size_t count;
62a8067a AV	51	union {
62a8067a AV	52	const struct iovec *iov;
a280455f	53	const struct kvec *kvec;
62a8067a	54	const struct bio_vec *bvec;
7ff50620	55	struct xarray *xarray;
241699cd	56	struct pipe_inode_info *pipe;
fcb14cb1	57	void __user *ubuf;
241699cd AV	58	};
	59	union {
	60	unsigned long nr_segs;
27c0e374	61	struct {
8cefc107 DH	62	unsigned int head;
8cefc107 DH	63	unsigned int start_head;
27c0e374	64	};
7ff50620	65	loff_t xarray_start;
62a8067a	66	};
92236878 KO	67	};
92236878 KO	68
00e23707 DH	69	static inline enum iter_type iov_iter_type(const struct iov_iter *i)
00e23707 DH	70	{
8cd54c1c	71	return i->iter_type;
00e23707 DH	72	}
00e23707 DH	73
8fb0f47a JA	74	static inline void iov_iter_save_state(struct iov_iter *iter,
	75	struct iov_iter_state *state)
	76	{
	77	state->iov_offset = iter->iov_offset;
	78	state->count = iter->count;
	79	state->nr_segs = iter->nr_segs;
	80	}
	81
fcb14cb1 AV	82	static inline bool iter_is_ubuf(const struct iov_iter *i)
	83	{
	84	return iov_iter_type(i) == ITER_UBUF;
	85	}
	86
00e23707 DH	87	static inline bool iter_is_iovec(const struct iov_iter *i)
	88	{
	89	return iov_iter_type(i) == ITER_IOVEC;
	90	}
	91
	92	static inline bool iov_iter_is_kvec(const struct iov_iter *i)
	93	{
	94	return iov_iter_type(i) == ITER_KVEC;
	95	}
	96
	97	static inline bool iov_iter_is_bvec(const struct iov_iter *i)
	98	{
	99	return iov_iter_type(i) == ITER_BVEC;
	100	}
	101
	102	static inline bool iov_iter_is_pipe(const struct iov_iter *i)
	103	{
	104	return iov_iter_type(i) == ITER_PIPE;
	105	}
	106
9ea9ce04 DH	107	static inline bool iov_iter_is_discard(const struct iov_iter *i)
	108	{
	109	return iov_iter_type(i) == ITER_DISCARD;
	110	}
	111
7ff50620 DH	112	static inline bool iov_iter_is_xarray(const struct iov_iter *i)
	113	{
	114	return iov_iter_type(i) == ITER_XARRAY;
	115	}
	116
00e23707 DH	117	static inline unsigned char iov_iter_rw(const struct iov_iter *i)
00e23707 DH	118	{
8cd54c1c	119	return i->data_source ? WRITE : READ;
00e23707 DH	120	}
00e23707 DH	121
fcb14cb1 AV	122	static inline bool user_backed_iter(const struct iov_iter *i)
	123	{
	124	return i->user_backed;
	125	}
	126
1da177e4 LT	127	/*
	128	* Total number of bytes covered by an iovec.
	129	*
	130	* NOTE that it is not safe to use this function until all the iovec's
	131	* segment lengths have been validated. Because the individual lengths can
	132	* overflow a size_t when added together.
	133	*/
	134	static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
	135	{
	136	unsigned long seg;
	137	size_t ret = 0;
	138
	139	for (seg = 0; seg < nr_segs; seg++)
	140	ret += iov[seg].iov_len;
	141	return ret;
	142	}
	143
92236878 KO	144	static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
	145	{
	146	return (struct iovec) {
	147	.iov_base = iter->iov->iov_base + iter->iov_offset,
	148	.iov_len = min(iter->count,
	149	iter->iov->iov_len - iter->iov_offset),
	150	};
	151	}
	152
f0b65f39 AV	153	size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
f0b65f39 AV	154	size_t bytes, struct iov_iter *i);
92236878	155	void iov_iter_advance(struct iov_iter *i, size_t bytes);
27c0e374	156	void iov_iter_revert(struct iov_iter *i, size_t bytes);
a6294593	157	size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
cdd591fc	158	size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
92236878	159	size_t iov_iter_single_seg_count(const struct iov_iter *i);
6e58e79d AV	160	size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
6e58e79d AV	161	struct iov_iter *i);
f0d1bec9 AV	162	size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
f0d1bec9 AV	163	struct iov_iter *i);
aa28de27 AV	164
	165	size_t _copy_to_iter(const void addr, size_t bytes, struct iov_iter i);
	166	size_t _copy_from_iter(void addr, size_t bytes, struct iov_iter i);
aa28de27	167	size_t _copy_from_iter_nocache(void addr, size_t bytes, struct iov_iter i);
aa28de27	168
d9c19d32 MWO	169	static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
	170	size_t bytes, struct iov_iter *i)
	171	{
	172	return copy_page_to_iter(&folio->page, offset, bytes, i);
	173	}
	174
aa28de27 AV	175	static __always_inline __must_check
	176	size_t copy_to_iter(const void addr, size_t bytes, struct iov_iter i)
	177	{
0e3c3b90	178	if (check_copy_size(addr, bytes, true))
aa28de27	179	return _copy_to_iter(addr, bytes, i);
0e3c3b90	180	return 0;
aa28de27 AV	181	}
	182
	183	static __always_inline __must_check
	184	size_t copy_from_iter(void addr, size_t bytes, struct iov_iter i)
	185	{
0e3c3b90	186	if (check_copy_size(addr, bytes, false))
aa28de27	187	return _copy_from_iter(addr, bytes, i);
0e3c3b90	188	return 0;
aa28de27 AV	189	}
	190
	191	static __always_inline __must_check
	192	bool copy_from_iter_full(void addr, size_t bytes, struct iov_iter i)
	193	{
4b6c132b AV	194	size_t copied = copy_from_iter(addr, bytes, i);
	195	if (likely(copied == bytes))
	196	return true;
	197	iov_iter_revert(i, copied);
	198	return false;
aa28de27 AV	199	}
	200
	201	static __always_inline __must_check
	202	size_t copy_from_iter_nocache(void addr, size_t bytes, struct iov_iter i)
	203	{
0e3c3b90	204	if (check_copy_size(addr, bytes, false))
aa28de27	205	return _copy_from_iter_nocache(addr, bytes, i);
0e3c3b90	206	return 0;
aa28de27 AV	207	}
	208
	209	static __always_inline __must_check
	210	bool copy_from_iter_full_nocache(void addr, size_t bytes, struct iov_iter i)
	211	{
4b6c132b AV	212	size_t copied = copy_from_iter_nocache(addr, bytes, i);
	213	if (likely(copied == bytes))
	214	return true;
	215	iov_iter_revert(i, copied);
	216	return false;
aa28de27 AV	217	}
aa28de27 AV	218
0aed55af DW	219	#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
	220	/*
	221	* Note, users like pmem that depend on the stricter semantics of
e17f7a0b	222	* _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
0aed55af DW	223	* IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
	224	* destination is flushed from the cache on return.
	225	*/
6a37e940	226	size_t _copy_from_iter_flushcache(void addr, size_t bytes, struct iov_iter i);
0aed55af	227	#else
6a37e940 LT	228	#define _copy_from_iter_flushcache _copy_from_iter_nocache
	229	#endif
	230
ec6347bb DW	231	#ifdef CONFIG_ARCH_HAS_COPY_MC
ec6347bb DW	232	size_t _copy_mc_to_iter(const void addr, size_t bytes, struct iov_iter i);
8780356e	233	#else
ec6347bb	234	#define _copy_mc_to_iter _copy_to_iter
8780356e DW	235	#endif
8780356e DW	236
c35e0248	237	size_t iov_iter_zero(size_t bytes, struct iov_iter *);
cfa320f7 KB	238	bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
cfa320f7 KB	239	unsigned len_mask);
886a3911	240	unsigned long iov_iter_alignment(const struct iov_iter *i);
357f435d	241	unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
aa563d7b	242	void iov_iter_init(struct iov_iter i, unsigned int direction, const struct iovec iov,
71d8e532	243	unsigned long nr_segs, size_t count);
aa563d7b	244	void iov_iter_kvec(struct iov_iter i, unsigned int direction, const struct kvec kvec,
05afcb77	245	unsigned long nr_segs, size_t count);
aa563d7b	246	void iov_iter_bvec(struct iov_iter i, unsigned int direction, const struct bio_vec bvec,
abb78f87	247	unsigned long nr_segs, size_t count);
aa563d7b	248	void iov_iter_pipe(struct iov_iter i, unsigned int direction, struct pipe_inode_info pipe,
241699cd	249	size_t count);
9ea9ce04	250	void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
7ff50620 DH	251	void iov_iter_xarray(struct iov_iter i, unsigned int direction, struct xarray xarray,
7ff50620 DH	252	loff_t start, size_t count);
d8207640 LG	253	ssize_t iov_iter_get_pages(struct iov_iter i, struct page *pages,
	254	size_t maxsize, unsigned maxpages, size_t *start,
	255	unsigned gup_flags);
eba2d3d7	256	ssize_t iov_iter_get_pages2(struct iov_iter i, struct page *pages,
2c80929c	257	size_t maxsize, unsigned maxpages, size_t *start);
d8207640 LG	258	ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
	259	struct page **pages, size_t maxsize, size_t start,
	260	unsigned gup_flags);
eba2d3d7	261	ssize_t iov_iter_get_pages_alloc2(struct iov_iter i, struct page **pages,
91f79c43	262	size_t maxsize, size_t *start);
f67da30c	263	int iov_iter_npages(const struct iov_iter *i, int maxpages);
8fb0f47a	264	void iov_iter_restore(struct iov_iter i, struct iov_iter_state state);
92236878	265
4b8164b9 AV	266	const void dup_iter(struct iov_iter new, struct iov_iter *old, gfp_t flags);
4b8164b9 AV	267
b57332b4	268	static inline size_t iov_iter_count(const struct iov_iter *i)
92236878 KO	269	{
	270	return i->count;
	271	}
	272
0b86dbf6 AV	273	/*
	274	* Cap the iov_iter by given limit; note that the second argument is
	275	* not the new size - it's upper limit for such. Passing it a value
	276	* greater than the amount of data in iov_iter is fine - it'll just do
	277	* nothing in that case.
	278	*/
	279	static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
0c949334	280	{
0b86dbf6 AV	281	/*
	282	* count doesn't have to fit in size_t - comparison extends both
	283	* operands to u64 here and any value that would be truncated by
	284	* conversion in assignement is by definition greater than all
	285	* values of size_t, including old i->count.
	286	*/
7dedd3e1	287	if (i->count > count)
0c949334 AV	288	i->count = count;
	289	}
	290
b42b15fd AV	291	/*
	292	* reexpand a previously truncated iterator; count must be no more than how much
	293	* we had shrunk it.
	294	*/
	295	static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
	296	{
	297	i->count = count;
	298	}
52cbd23a	299
b93235e6 JK	300	static inline int
	301	iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
	302	{
	303	size_t shorted = 0;
	304	int npages;
	305
	306	if (iov_iter_count(i) > max_bytes) {
	307	shorted = iov_iter_count(i) - max_bytes;
	308	iov_iter_truncate(i, max_bytes);
	309	}
7187440d	310	npages = iov_iter_npages(i, maxpages);
b93235e6 JK	311	if (shorted)
	312	iov_iter_reexpand(i, iov_iter_count(i) + shorted);
	313
	314	return npages;
	315	}
	316
52cbd23a WB	317	struct csum_state {
	318	__wsum csum;
	319	size_t off;
	320	};
	321
	322	size_t csum_and_copy_to_iter(const void addr, size_t bytes, void csstate, struct iov_iter *i);
a604ec7e	323	size_t csum_and_copy_from_iter(void addr, size_t bytes, __wsum csum, struct iov_iter *i);
4b6c132b AV	324
	325	static __always_inline __must_check
	326	bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
	327	__wsum csum, struct iov_iter i)
	328	{
	329	size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
	330	if (likely(copied == bytes))
	331	return true;
	332	iov_iter_revert(i, copied);
	333	return false;
	334	}
d05f4435 SG	335	size_t hash_and_copy_to_iter(const void addr, size_t bytes, void hashp,
d05f4435 SG	336	struct iov_iter *i);
b42b15fd	337
bfdc5970 CH	338	struct iovec iovec_from_user(const struct iovec __user uvector,
	339	unsigned long nr_segs, unsigned long fast_segs,
	340	struct iovec *fast_iov, bool compat);
	341	ssize_t import_iovec(int type, const struct iovec __user *uvec,
	342	unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
	343	struct iov_iter *i);
	344	ssize_t __import_iovec(int type, const struct iovec __user *uvec,
	345	unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
	346	struct iov_iter *i, bool compat);
bc917be8 AV	347	int import_single_range(int type, void __user *buf, size_t len,
	348	struct iovec iov, struct iov_iter i);
	349
fcb14cb1 AV	350	static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
	351	void __user *buf, size_t count)
	352	{
	353	WARN_ON(direction & ~(READ \| WRITE));
	354	*i = (struct iov_iter) {
	355	.iter_type = ITER_UBUF,
	356	.user_backed = true,
	357	.data_source = direction,
	358	.ubuf = buf,
	359	.count = count
	360	};
	361	}
	362
812ed032	363	#endif