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Commit a280455f authored by Al Viro's avatar Al Viro
Browse files

iov_iter.c: handle ITER_KVEC directly 



... without bothering with copy_..._user()

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3d4d3e48

include/linux/uio.h

+1 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ struct iov_iter { 
	size_t count;

	union {

		const struct iovec *iov;

		const struct kvec *kvec;

		const struct bio_vec *bvec;

	};

	unsigned long nr_segs;

mm/iov_iter.c

+69 −13
Original line number Diff line number Diff line
@@ -32,6 +32,29 @@ 
	n = wanted - n;					\

}



#define iterate_kvec(i, n, __v, __p, skip, STEP) {	\

	size_t wanted = n;				\

	__p = i->kvec;					\

	__v.iov_len = min(n, __p->iov_len - skip);	\

	if (likely(__v.iov_len)) {			\

		__v.iov_base = __p->iov_base + skip;	\

		(void)(STEP);				\

		skip += __v.iov_len;			\

		n -= __v.iov_len;			\

	}						\

	while (unlikely(n)) {				\

		__p++;					\

		__v.iov_len = min(n, __p->iov_len);	\

		if (unlikely(!__v.iov_len))		\

			continue;			\

		__v.iov_base = __p->iov_base;		\

		(void)(STEP);				\

		skip = __v.iov_len;			\

		n -= __v.iov_len;			\

	}						\

	n = wanted;					\

}



#define iterate_bvec(i, n, __v, __p, skip, STEP) {	\

	size_t wanted = n;				\

	__p = i->bvec;					\
@@ -57,12 +80,16 @@ 
	n = wanted;					\

}



#define iterate_all_kinds(i, n, v, I, B) {			\

#define iterate_all_kinds(i, n, v, I, B, K) {			\

	size_t skip = i->iov_offset;				\

	if (unlikely(i->type & ITER_BVEC)) {			\

		const struct bio_vec *bvec;			\

		struct bio_vec v;				\

		iterate_bvec(i, n, v, bvec, skip, (B))		\

	} else if (unlikely(i->type & ITER_KVEC)) {		\

		const struct kvec *kvec;			\

		struct kvec v;					\

		iterate_kvec(i, n, v, kvec, skip, (K))		\

	} else {						\

		const struct iovec *iov;			\

		struct iovec v;					\
@@ -70,7 +97,7 @@ 
	}							\

}



#define iterate_and_advance(i, n, v, I, B) {			\

#define iterate_and_advance(i, n, v, I, B, K) {			\

	size_t skip = i->iov_offset;				\

	if (unlikely(i->type & ITER_BVEC)) {			\

		const struct bio_vec *bvec;			\
@@ -82,6 +109,16 @@ 
		}						\

		i->nr_segs -= bvec - i->bvec;			\

		i->bvec = bvec;					\

	} else if (unlikely(i->type & ITER_KVEC)) {		\

		const struct kvec *kvec;			\

		struct kvec v;					\

		iterate_kvec(i, n, v, kvec, skip, (K))		\

		if (skip == kvec->iov_len) {			\

			kvec++;					\

			skip = 0;				\

		}						\

		i->nr_segs -= kvec - i->kvec;			\

		i->kvec = kvec;					\

	} else {						\

		const struct iovec *iov;			\

		struct iovec v;					\
@@ -270,7 +307,7 @@ static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t 
 */

int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)

{

	if (!(i->type & ITER_BVEC)) {

	if (!(i->type & (ITER_BVEC|ITER_KVEC))) {

		char __user *buf = i->iov->iov_base + i->iov_offset;

		bytes = min(bytes, i->iov->iov_len - i->iov_offset);

		return fault_in_pages_readable(buf, bytes);
@@ -284,10 +321,14 @@ void iov_iter_init(struct iov_iter *i, int direction, 
			size_t count)

{

	/* It will get better.  Eventually... */

	if (segment_eq(get_fs(), KERNEL_DS))

	if (segment_eq(get_fs(), KERNEL_DS)) {

		direction |= ITER_KVEC;

		i->type = direction;

		i->kvec = (struct kvec *)iov;

	} else {

		i->type = direction;

		i->iov = iov;

	}

	i->nr_segs = nr_segs;

	i->iov_offset = 0;

	i->count = count;
@@ -328,7 +369,8 @@ size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i) 
		__copy_to_user(v.iov_base, (from += v.iov_len) - v.iov_len,

			       v.iov_len),

		memcpy_to_page(v.bv_page, v.bv_offset,

			       (from += v.bv_len) - v.bv_len, v.bv_len)

			       (from += v.bv_len) - v.bv_len, v.bv_len),

		memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)

	)



	return bytes;
@@ -348,7 +390,8 @@ size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) 
		__copy_from_user((to += v.iov_len) - v.iov_len, v.iov_base,

				 v.iov_len),

		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,

				 v.bv_offset, v.bv_len)

				 v.bv_offset, v.bv_len),

		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)

	)



	return bytes;
@@ -371,7 +414,7 @@ EXPORT_SYMBOL(copy_page_to_iter); 
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,

			 struct iov_iter *i)

{

	if (i->type & ITER_BVEC) {

	if (i->type & (ITER_BVEC|ITER_KVEC)) {

		void *kaddr = kmap_atomic(page);

		size_t wanted = copy_from_iter(kaddr + offset, bytes, i);

		kunmap_atomic(kaddr);
@@ -391,7 +434,8 @@ size_t iov_iter_zero(size_t bytes, struct iov_iter *i) 


	iterate_and_advance(i, bytes, v,

		__clear_user(v.iov_base, v.iov_len),

		memzero_page(v.bv_page, v.bv_offset, v.bv_len)

		memzero_page(v.bv_page, v.bv_offset, v.bv_len),

		memset(v.iov_base, 0, v.iov_len)

	)



	return bytes;
@@ -406,7 +450,8 @@ size_t iov_iter_copy_from_user_atomic(struct page *page, 
		__copy_from_user_inatomic((p += v.iov_len) - v.iov_len,

					  v.iov_base, v.iov_len),

		memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,

				 v.bv_offset, v.bv_len)

				 v.bv_offset, v.bv_len),

		memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)

	)

	kunmap_atomic(kaddr);

	return bytes;
@@ -415,7 +460,7 @@ EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); 


void iov_iter_advance(struct iov_iter *i, size_t size)

{

	iterate_and_advance(i, size, v, 0, 0)

	iterate_and_advance(i, size, v, 0, 0, 0)

}

EXPORT_SYMBOL(iov_iter_advance);
@@ -443,7 +488,8 @@ unsigned long iov_iter_alignment(const struct iov_iter *i) 


	iterate_all_kinds(i, size, v,

		(res |= (unsigned long)v.iov_base | v.iov_len, 0),

		res |= v.bv_offset | v.bv_len

		res |= v.bv_offset | v.bv_len,

		res |= (unsigned long)v.iov_base | v.iov_len

	)

	return res;

}
@@ -478,6 +524,8 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, 
		*start = v.bv_offset;

		get_page(*pages = v.bv_page);

		return v.bv_len;

	}),({

		return -EFAULT;

	})

	)

	return 0;
@@ -530,6 +578,8 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, 
			return -ENOMEM;

		get_page(*p = v.bv_page);

		return v.bv_len;

	}),({

		return -EFAULT;

	})

	)

	return 0;
@@ -554,6 +604,12 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages) 
		npages++;

		if (npages >= maxpages)

			return maxpages;

	}),({

		unsigned long p = (unsigned long)v.iov_base;

		npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)

			- p / PAGE_SIZE;

		if (npages >= maxpages)

			return maxpages;

	})

	)

	return npages;