Add basic uio support

This code originates in OpenSolaris and was modified by KQ Infotech
to be compatible with Linux.  While supporting uios in the short
term is useful to get something working this is not an abstraction
we want to keep.  This code is expected to be short lived and
removed as soon as all the remaining uio based APIs and updated.

2 files changed, 256 insertions, 0 deletions

diff --git a/module/zcommon/Makefile.in b/module/zcommon/Makefile.in
index ee4864ffc..e564b77b4 100644
--- a/module/zcommon/Makefile.in
+++ b/module/zcommon/Makefile.in
@@ -13,4 +13,5 @@ $(MODULE)-objs += @top_srcdir@/module/zcommon/zprop_common.o
 $(MODULE)-objs += @top_srcdir@/module/zcommon/zfs_namecheck.o
 $(MODULE)-objs += @top_srcdir@/module/zcommon/zfs_comutil.o
 $(MODULE)-objs += @top_srcdir@/module/zcommon/zfs_fletcher.o
+$(MODULE)-objs += @top_srcdir@/module/zcommon/zfs_uio.o
 $(MODULE)-objs += @top_srcdir@/module/zcommon/zpool_prop.o
diff --git a/module/zcommon/zfs_uio.c b/module/zcommon/zfs_uio.c
new file mode 100644
index 000000000..990464594
--- /dev/null
+++ b/module/zcommon/zfs_uio.c
@@ -0,0 +1,255 @@
+/*
+ * 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.
+ */
+
+/*
+ * 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>
+
+/*
+ * 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.
+ */
+int
+uiomove(void *p, size_t n, enum uio_rw rw, struct uio *uio)
+{
+	struct iovec *iov;
+	ulong_t cnt;
+
+	while (n && uio->uio_resid) {
+		iov = uio->uio_iov;
+		cnt = MIN(iov->iov_len, n);
+		if (cnt == 0l) {
+			uio->uio_iov++;
+			uio->uio_iovcnt--;
+			continue;
+		}
+		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, p, cnt))
+					return EFAULT;
+				/* error = xcopyout_nta(p, iov->iov_base, cnt,
+				 * (uio->uio_extflg & UIO_COPY_CACHED)); */
+			} else {
+				/* error = xcopyin_nta(iov->iov_base, p, cnt,
+				 * (uio->uio_extflg & UIO_COPY_CACHED)); */
+				if (copy_from_user(p, iov->iov_base, cnt))
+					return EFAULT;
+			}
+			break;
+		case UIO_SYSSPACE:
+			if (rw == UIO_READ)
+				bcopy(p, iov->iov_base, cnt);
+			else
+				bcopy(iov->iov_base, p, cnt);
+			break;
+		}
+		iov->iov_base += cnt;
+		iov->iov_len -= cnt;
+		uio->uio_resid -= cnt;
+		uio->uio_loffset += cnt;
+		p = (caddr_t)p + cnt;
+		n -= cnt;
+	}
+	return (0);
+}
+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)
+{
+	struct iovec *iov;
+	ulong_t cnt, incr;
+	caddr_t p;
+	uint8_t tmp;
+	int iovcnt;
+
+	iov = uio->uio_iov;
+	iovcnt = uio->uio_iovcnt;
+
+	while ((n > 0) && (iovcnt > 0)) {
+		cnt = MIN(iov->iov_len, n);
+		if (cnt == 0) {
+			/* empty iov entry */
+			iov++;
+			iovcnt--;
+			continue;
+		}
+		n -= cnt;
+		/*
+		 * touch each page in this segment.
+		 */
+		p = iov->iov_base;
+		while (cnt) {
+			switch (uio->uio_segflg) {
+			case UIO_USERSPACE:
+			case UIO_USERISPACE:
+				if (fuword8((uint8_t *) p, &tmp))
+					return;
+				break;
+			case UIO_SYSSPACE:
+				bcopy(p, &tmp, 1);
+				break;
+			}
+			incr = MIN(cnt, PAGESIZE);
+			p += incr;
+			cnt -= incr;
+		}
+		/*
+		 * touch the last byte in case it straddles a page.
+		 */
+		p--;
+		switch (uio->uio_segflg) {
+		case UIO_USERSPACE:
+		case UIO_USERISPACE:
+			if (fuword8((uint8_t *) p, &tmp))
+				return;
+			break;
+		case UIO_SYSSPACE:
+			bcopy(p, &tmp, 1);
+			break;
+		}
+		iov++;
+		iovcnt--;
+	}
+}
+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 iovec *iov;
+	ulong_t cnt;
+	int iovcnt;
+
+	iovcnt = uio->uio_iovcnt;
+	*cbytes = 0;
+
+	for (iov = uio->uio_iov; n && iovcnt; iov++, iovcnt--) {
+		cnt = MIN(iov->iov_len, n);
+		if (cnt == 0)
+			continue;
+
+		switch (uio->uio_segflg) {
+
+		case UIO_USERSPACE:
+		case UIO_USERISPACE:
+			/* p = kernel data pointer
+			 * iov->iov_base = user data pointer */
+
+			if (rw == UIO_READ) {
+				/* * UIO_READ = copy data from kernel to user * */
+				if (copy_to_user(iov->iov_base, p, cnt))
+					return EFAULT;
+				/* error = xcopyout_nta(p, iov->iov_base, cnt,
+				 * (uio->uio_extflg & UIO_COPY_CACHED)); */
+			} else {
+				/* * UIO_WRITE = copy data from user to kernel * */
+				/* error = xcopyin_nta(iov->iov_base, p, cnt,
+				 * (uio->uio_extflg & UIO_COPY_CACHED)); */
+				if (copy_from_user(p, iov->iov_base, cnt))
+					return EFAULT;
+			}
+			break;
+
+		case UIO_SYSSPACE:
+			if (rw == UIO_READ)
+				bcopy(p, iov->iov_base, cnt);
+			else
+				bcopy(iov->iov_base, p, cnt);
+			break;
+		}
+		p = (caddr_t)p + cnt;
+		n -= cnt;
+		*cbytes += cnt;
+	}
+	return (0);
+}
+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;
+	while (n != 0) {
+		iovec_t	*iovp = uiop->uio_iov;
+		size_t		niovb = MIN(iovp->iov_len, n);
+
+		if (niovb == 0) {
+			uiop->uio_iov++;
+			uiop->uio_iovcnt--;
+			continue;
+		}
+		iovp->iov_base += niovb;
+		uiop->uio_loffset += niovb;
+		iovp->iov_len -= niovb;
+		uiop->uio_resid -= niovb;
+		n -= niovb;
+	}
+}
+EXPORT_SYMBOL(uioskip);
+#endif /* _KERNEL */