[mirror_zfs-debian.git] / module / zcommon / zfs_uio.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved	*/

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */
/*
 * Copyright (c) 2015 by Chunwei Chen. All rights reserved.
 */

/*
 * The uio support from OpenSolaris has been added as a short term
 * work around.  The hope is to adopt native Linux type and drop the
 * use of uio's entirely.  Under Linux they only add overhead and
 * when possible we want to use native APIs for the ZPL layer.
 */
#ifdef _KERNEL

#include <sys/types.h>
#include <sys/uio_impl.h>
#include <linux/kmap_compat.h>

/*
 * Move "n" bytes at byte address "p"; "rw" indicates the direction
 * of the move, and the I/O parameters are provided in "uio", which is
 * update to reflect the data which was moved.  Returns 0 on success or
 * a non-zero errno on failure.
 */
static int
uiomove_iov(void *p, size_t n, enum uio_rw rw, struct uio *uio)
{
	const struct iovec *iov = uio->uio_iov;
	size_t skip = uio->uio_skip;
	ulong_t cnt;

	while (n && uio->uio_resid) {
		cnt = MIN(iov->iov_len - skip, n);
		switch (uio->uio_segflg) {
		case UIO_USERSPACE:
		case UIO_USERISPACE:
			/*
			 * p = kernel data pointer
			 * iov->iov_base = user data pointer
			 */
			if (rw == UIO_READ) {
				if (copy_to_user(iov->iov_base+skip, p, cnt))
					return (EFAULT);
			} else {
				if (copy_from_user(p, iov->iov_base+skip, cnt))
					return (EFAULT);
			}
			break;
		case UIO_SYSSPACE:
			if (rw == UIO_READ)
				bcopy(p, iov->iov_base + skip, cnt);
			else
				bcopy(iov->iov_base + skip, p, cnt);
			break;
		default:
			ASSERT(0);
		}
		skip += cnt;
		if (skip == iov->iov_len) {
			skip = 0;
			uio->uio_iov = (++iov);
			uio->uio_iovcnt--;
		}
		uio->uio_skip = skip;
		uio->uio_resid -= cnt;
		uio->uio_loffset += cnt;
		p = (caddr_t)p + cnt;
		n -= cnt;
	}
	return (0);
}

static int
uiomove_bvec(void *p, size_t n, enum uio_rw rw, struct uio *uio)
{
	const struct bio_vec *bv = uio->uio_bvec;
	size_t skip = uio->uio_skip;
	ulong_t cnt;

	while (n && uio->uio_resid) {
		void *paddr;
		cnt = MIN(bv->bv_len - skip, n);

		paddr = zfs_kmap_atomic(bv->bv_page, KM_USER1);
		if (rw == UIO_READ)
			bcopy(p, paddr + bv->bv_offset + skip, cnt);
		else
			bcopy(paddr + bv->bv_offset + skip, p, cnt);
		zfs_kunmap_atomic(paddr, KM_USER1);

		skip += cnt;
		if (skip == bv->bv_len) {
			skip = 0;
			uio->uio_bvec = (++bv);
			uio->uio_iovcnt--;
		}
		uio->uio_skip = skip;
		uio->uio_resid -= cnt;
		uio->uio_loffset += cnt;
		p = (caddr_t)p + cnt;
		n -= cnt;
	}
	return (0);
}

int
uiomove(void *p, size_t n, enum uio_rw rw, struct uio *uio)
{
	if (uio->uio_segflg != UIO_BVEC)
		return (uiomove_iov(p, n, rw, uio));
	else
		return (uiomove_bvec(p, n, rw, uio));
}
EXPORT_SYMBOL(uiomove);

#define	fuword8(uptr, vptr)	get_user((*vptr), (uptr))

/*
 * Fault in the pages of the first n bytes specified by the uio structure.
 * 1 byte in each page is touched and the uio struct is unmodified. Any
 * error will terminate the process as this is only a best attempt to get
 * the pages resident.
 */
void
uio_prefaultpages(ssize_t n, struct uio *uio)
{
	const struct iovec *iov;
	ulong_t cnt, incr;
	caddr_t p;
	uint8_t tmp;
	int iovcnt;
	size_t skip;

	/* no need to fault in kernel pages */
	switch (uio->uio_segflg) {
		case UIO_SYSSPACE:
		case UIO_BVEC:
			return;
		case UIO_USERSPACE:
		case UIO_USERISPACE:
			break;
		default:
			ASSERT(0);
	}

	iov = uio->uio_iov;
	iovcnt = uio->uio_iovcnt;
	skip = uio->uio_skip;

	for (; n > 0 && iovcnt > 0; iov++, iovcnt--, skip = 0) {
		cnt = MIN(iov->iov_len - skip, n);
		/* empty iov */
		if (cnt == 0)
			continue;
		n -= cnt;
		/*
		 * touch each page in this segment.
		 */
		p = iov->iov_base + skip;
		while (cnt) {
			if (fuword8((uint8_t *)p, &tmp))
				return;
			incr = MIN(cnt, PAGESIZE);
			p += incr;
			cnt -= incr;
		}
		/*
		 * touch the last byte in case it straddles a page.
		 */
		p--;
		if (fuword8((uint8_t *)p, &tmp))
			return;
	}
}
EXPORT_SYMBOL(uio_prefaultpages);

/*
 * same as uiomove() but doesn't modify uio structure.
 * return in cbytes how many bytes were copied.
 */
int
uiocopy(void *p, size_t n, enum uio_rw rw, struct uio *uio, size_t *cbytes)
{
	struct uio uio_copy;
	int ret;

	bcopy(uio, &uio_copy, sizeof (struct uio));
	ret = uiomove(p, n, rw, &uio_copy);
	*cbytes = uio->uio_resid - uio_copy.uio_resid;
	return (ret);
}
EXPORT_SYMBOL(uiocopy);

/*
 * Drop the next n chars out of *uiop.
 */
void
uioskip(uio_t *uiop, size_t n)
{
	if (n > uiop->uio_resid)
		return;

	uiop->uio_skip += n;
	if (uiop->uio_segflg != UIO_BVEC) {
		while (uiop->uio_iovcnt &&
		    uiop->uio_skip >= uiop->uio_iov->iov_len) {
			uiop->uio_skip -= uiop->uio_iov->iov_len;
			uiop->uio_iov++;
			uiop->uio_iovcnt--;
		}
	} else {
		while (uiop->uio_iovcnt &&
		    uiop->uio_skip >= uiop->uio_bvec->bv_len) {
			uiop->uio_skip -= uiop->uio_bvec->bv_len;
			uiop->uio_bvec++;
			uiop->uio_iovcnt--;
		}
	}
	uiop->uio_loffset += n;
	uiop->uio_resid -= n;
}
EXPORT_SYMBOL(uioskip);
#endif /* _KERNEL */
Commit	Line	Data
590329b5 BB	1	/*
	2	* CDDL HEADER START
	3	*
	4	* The contents of this file are subject to the terms of the
	5	* Common Development and Distribution License (the "License").
	6	* You may not use this file except in compliance with the License.
	7	*
	8	* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
	9	* or http://www.opensolaris.org/os/licensing.
	10	* See the License for the specific language governing permissions
	11	* and limitations under the License.
	12	*
	13	* When distributing Covered Code, include this CDDL HEADER in each
	14	* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
	15	* If applicable, add the following below this CDDL HEADER, with the
	16	* fields enclosed by brackets "[]" replaced with your own identifying
	17	* information: Portions Copyright [yyyy] [name of copyright owner]
	18	*
	19	* CDDL HEADER END
	20	*/
	21	/*
	22	* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
	23	* Use is subject to license terms.
	24	*/
	25
	26	/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
	27	/* All Rights Reserved */
	28
	29	/*
	30	* University Copyright- Copyright (c) 1982, 1986, 1988
	31	* The Regents of the University of California
	32	* All Rights Reserved
	33	*
	34	* University Acknowledgment- Portions of this document are derived from
	35	* software developed by the University of California, Berkeley, and its
	36	* contributors.
	37	*/
e10b0808 AX	38	/*
	39	* Copyright (c) 2015 by Chunwei Chen. All rights reserved.
	40	*/
590329b5 BB	41
	42	/*
	43	* The uio support from OpenSolaris has been added as a short term
	44	* work around. The hope is to adopt native Linux type and drop the
	45	* use of uio's entirely. Under Linux they only add overhead and
	46	* when possible we want to use native APIs for the ZPL layer.
	47	*/
	48	#ifdef _KERNEL
	49
	50	#include <sys/types.h>
	51	#include <sys/uio_impl.h>
e10b0808	52	#include <linux/kmap_compat.h>
590329b5 BB	53
	54	/*
	55	* Move "n" bytes at byte address "p"; "rw" indicates the direction
	56	* of the move, and the I/O parameters are provided in "uio", which is
	57	* update to reflect the data which was moved. Returns 0 on success or
	58	* a non-zero errno on failure.
	59	*/
e10b0808 AX	60	static int
e10b0808 AX	61	uiomove_iov(void p, size_t n, enum uio_rw rw, struct uio uio)
590329b5	62	{
e10b0808 AX	63	const struct iovec *iov = uio->uio_iov;
e10b0808 AX	64	size_t skip = uio->uio_skip;
590329b5 BB	65	ulong_t cnt;
	66
	67	while (n && uio->uio_resid) {
e10b0808	68	cnt = MIN(iov->iov_len - skip, n);
590329b5 BB	69	switch (uio->uio_segflg) {
	70	case UIO_USERSPACE:
	71	case UIO_USERISPACE:
a08ee875 LG	72	/*
	73	* p = kernel data pointer
	74	* iov->iov_base = user data pointer
	75	*/
590329b5	76	if (rw == UIO_READ) {
e10b0808	77	if (copy_to_user(iov->iov_base+skip, p, cnt))
a08ee875	78	return (EFAULT);
590329b5	79	} else {
e10b0808	80	if (copy_from_user(p, iov->iov_base+skip, cnt))
a08ee875	81	return (EFAULT);
590329b5 BB	82	}
	83	break;
	84	case UIO_SYSSPACE:
	85	if (rw == UIO_READ)
e10b0808	86	bcopy(p, iov->iov_base + skip, cnt);
590329b5	87	else
e10b0808	88	bcopy(iov->iov_base + skip, p, cnt);
590329b5	89	break;
e10b0808 AX	90	default:
	91	ASSERT(0);
	92	}
	93	skip += cnt;
	94	if (skip == iov->iov_len) {
	95	skip = 0;
	96	uio->uio_iov = (++iov);
	97	uio->uio_iovcnt--;
	98	}
	99	uio->uio_skip = skip;
	100	uio->uio_resid -= cnt;
	101	uio->uio_loffset += cnt;
	102	p = (caddr_t)p + cnt;
	103	n -= cnt;
	104	}
	105	return (0);
	106	}
	107
	108	static int
	109	uiomove_bvec(void p, size_t n, enum uio_rw rw, struct uio uio)
	110	{
	111	const struct bio_vec *bv = uio->uio_bvec;
	112	size_t skip = uio->uio_skip;
	113	ulong_t cnt;
	114
	115	while (n && uio->uio_resid) {
	116	void *paddr;
	117	cnt = MIN(bv->bv_len - skip, n);
	118
	119	paddr = zfs_kmap_atomic(bv->bv_page, KM_USER1);
	120	if (rw == UIO_READ)
	121	bcopy(p, paddr + bv->bv_offset + skip, cnt);
	122	else
	123	bcopy(paddr + bv->bv_offset + skip, p, cnt);
	124	zfs_kunmap_atomic(paddr, KM_USER1);
	125
	126	skip += cnt;
	127	if (skip == bv->bv_len) {
	128	skip = 0;
	129	uio->uio_bvec = (++bv);
	130	uio->uio_iovcnt--;
590329b5	131	}
e10b0808	132	uio->uio_skip = skip;
590329b5 BB	133	uio->uio_resid -= cnt;
	134	uio->uio_loffset += cnt;
	135	p = (caddr_t)p + cnt;
	136	n -= cnt;
	137	}
	138	return (0);
	139	}
e10b0808 AX	140
	141	int
	142	uiomove(void p, size_t n, enum uio_rw rw, struct uio uio)
	143	{
	144	if (uio->uio_segflg != UIO_BVEC)
	145	return (uiomove_iov(p, n, rw, uio));
	146	else
	147	return (uiomove_bvec(p, n, rw, uio));
	148	}
590329b5 BB	149	EXPORT_SYMBOL(uiomove);
590329b5 BB	150
a08ee875	151	#define fuword8(uptr, vptr) get_user((*vptr), (uptr))
590329b5 BB	152
	153	/*
	154	* Fault in the pages of the first n bytes specified by the uio structure.
	155	* 1 byte in each page is touched and the uio struct is unmodified. Any
	156	* error will terminate the process as this is only a best attempt to get
	157	* the pages resident.
	158	*/
	159	void
	160	uio_prefaultpages(ssize_t n, struct uio *uio)
	161	{
e10b0808	162	const struct iovec *iov;
590329b5 BB	163	ulong_t cnt, incr;
	164	caddr_t p;
	165	uint8_t tmp;
	166	int iovcnt;
cae5b340	167	size_t skip;
e10b0808 AX	168
	169	/* no need to fault in kernel pages */
	170	switch (uio->uio_segflg) {
	171	case UIO_SYSSPACE:
	172	case UIO_BVEC:
	173	return;
	174	case UIO_USERSPACE:
	175	case UIO_USERISPACE:
	176	break;
	177	default:
	178	ASSERT(0);
	179	}
590329b5 BB	180
	181	iov = uio->uio_iov;
	182	iovcnt = uio->uio_iovcnt;
cae5b340	183	skip = uio->uio_skip;
590329b5	184
cae5b340	185	for (; n > 0 && iovcnt > 0; iov++, iovcnt--, skip = 0) {
e10b0808	186	cnt = MIN(iov->iov_len - skip, n);
cae5b340 AX	187	/* empty iov */
	188	if (cnt == 0)
	189	continue;
590329b5 BB	190	n -= cnt;
	191	/*
	192	* touch each page in this segment.
	193	*/
e10b0808	194	p = iov->iov_base + skip;
590329b5	195	while (cnt) {
cae5b340	196	if (fuword8((uint8_t *)p, &tmp))
e10b0808	197	return;
590329b5 BB	198	incr = MIN(cnt, PAGESIZE);
	199	p += incr;
	200	cnt -= incr;
	201	}
	202	/*
	203	* touch the last byte in case it straddles a page.
	204	*/
	205	p--;
cae5b340	206	if (fuword8((uint8_t *)p, &tmp))
e10b0808	207	return;
590329b5 BB	208	}
	209	}
	210	EXPORT_SYMBOL(uio_prefaultpages);
	211
	212	/*
	213	* same as uiomove() but doesn't modify uio structure.
	214	* return in cbytes how many bytes were copied.
	215	*/
	216	int
	217	uiocopy(void p, size_t n, enum uio_rw rw, struct uio uio, size_t *cbytes)
	218	{
e10b0808 AX	219	struct uio uio_copy;
e10b0808 AX	220	int ret;
590329b5	221
e10b0808 AX	222	bcopy(uio, &uio_copy, sizeof (struct uio));
	223	ret = uiomove(p, n, rw, &uio_copy);
	224	*cbytes = uio->uio_resid - uio_copy.uio_resid;
	225	return (ret);
590329b5 BB	226	}
	227	EXPORT_SYMBOL(uiocopy);
	228
	229	/*
	230	* Drop the next n chars out of *uiop.
	231	*/
	232	void
	233	uioskip(uio_t *uiop, size_t n)
	234	{
	235	if (n > uiop->uio_resid)
	236	return;
590329b5	237
e10b0808 AX	238	uiop->uio_skip += n;
	239	if (uiop->uio_segflg != UIO_BVEC) {
	240	while (uiop->uio_iovcnt &&
	241	uiop->uio_skip >= uiop->uio_iov->iov_len) {
	242	uiop->uio_skip -= uiop->uio_iov->iov_len;
590329b5 BB	243	uiop->uio_iov++;
590329b5 BB	244	uiop->uio_iovcnt--;
590329b5	245	}
e10b0808 AX	246	} else {
	247	while (uiop->uio_iovcnt &&
	248	uiop->uio_skip >= uiop->uio_bvec->bv_len) {
	249	uiop->uio_skip -= uiop->uio_bvec->bv_len;
	250	uiop->uio_bvec++;
	251	uiop->uio_iovcnt--;
	252	}
590329b5	253	}
e10b0808 AX	254	uiop->uio_loffset += n;
e10b0808 AX	255	uiop->uio_resid -= n;
590329b5 BB	256	}
	257	EXPORT_SYMBOL(uioskip);
	258	#endif /* _KERNEL */