Share zfs_fsync, zfs_read, zfs_write, et al between Linux and FreeBSD

The zfs_fsync, zfs_read, and zfs_write function are almost identical
between Linux and FreeBSD.  With a little refactoring they can be
moved to the common code which is what is done by this commit.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #11078

include/os/freebsd/zfs/sys/Makefile.am

@@ -8,7 +8,7 @@ KERNEL_H = \
 	zfs_dir.h \
 	zfs_ioctl_compat.h \
 	zfs_vfsops_os.h \
-	zfs_vnops.h \
+	zfs_vnops_os.h \
 	zfs_znode_impl.h \
 	zpl.h
 

include/os/freebsd/zfs/sys/zfs_context_os.h

@@ -42,6 +42,7 @@
 #include <linux/types.h>
 
 #define	cond_resched()		kern_yield(PRI_USER)
+#define	uio_prefaultpages(size, uio) (0)
 
 #define	taskq_create_sysdc(a, b, d, e, p, dc, f) \
 	    (taskq_create(a, b, maxclsyspri, d, e, f))

include/os/freebsd/zfs/sys/zfs_vnops_os.h

@@ -26,8 +26,9 @@
  * $FreeBSD$
  */
 
-#ifndef _SYS_ZFS_VNOPS_H_
-#define	_SYS_ZFS_VNOPS_H_
+#ifndef	_SYS_FS_ZFS_VNOPS_OS_H
+#define	_SYS_FS_ZFS_VNOPS_OS_H
+
 int dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset,
     uint64_t size, struct vm_page **ppa, dmu_tx_t *tx);
 int dmu_read_pages(objset_t *os, uint64_t object, vm_page_t *ma, int count,

include/os/freebsd/zfs/sys/zfs_znode_impl.h

@@ -39,6 +39,7 @@
 #include <sys/zfs_acl.h>
 #include <sys/zil.h>
 #include <sys/zfs_project.h>
+#include <vm/vm_object.h>
 
 #ifdef	__cplusplus
 extern "C" {
@@ -113,7 +114,10 @@ extern minor_t zfsdev_minor_alloc(void);
 #define	Z_ISBLK(type) ((type) == VBLK)
 #define	Z_ISCHR(type) ((type) == VCHR)
 #define	Z_ISLNK(type) ((type) == VLNK)
+#define	Z_ISDIR(type) ((type) == VDIR)
 
+#define	zn_has_cached_data(zp)	vn_has_cached_data(ZTOV(zp))
+#define	zn_rlimit_fsize(zp, uio, td)	vn_rlimit_fsize(ZTOV(zp), (uio), (td))
 
 /* Called on entry to each ZFS vnode and vfs operation  */
 #define	ZFS_ENTER(zfsvfs) \
@@ -175,7 +179,7 @@ extern int zfsfstype;
 
 extern int zfs_znode_parent_and_name(struct znode *zp, struct znode **dzpp,
     char *buf);
-
+extern void	zfs_inode_update(struct znode *);
 #ifdef	__cplusplus
 }
 #endif