zfs_vnops: refactor + make zfs_get_data OS-independent

- include/sys/zfs_vnops.h contains declarations of vnop functions
  that implement the same behavior on every platform.
  Function definitions are in
    - module/zfs/zfs_vnops.c for OS-independent code
    - module/os/*/zfs_vnops.c for OS-specific code

  In order to share the zfs_symlink declaration, the FreeBSD variant had
  to lose it's constness on the `char*` parameters.

- As a PoC, move zfs_get_data to zfs_vnops.c
    - This required creating a compatible zfs_zrele_async for FreeBSD.

Signed-off-by: Christian Schwarz <me@cschwarz.com>

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

@@ -26,31 +26,12 @@
  * $FreeBSD$
  */
 
-#ifndef _SYS_ZFS_VNOPS_H_
-#define	_SYS_ZFS_VNOPS_H_
+#ifndef _SYS_ZFS_VNOPS_OS_H_
+#define	_SYS_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,
     int *rbehind, int *rahead, int last_size);
-extern int zfs_remove(znode_t *dzp, char *name, cred_t *cr, int flags);
-extern int zfs_mkdir(znode_t *dzp, char *dirname, vattr_t *vap,
-    znode_t **zpp, cred_t *cr, int flags, vsecattr_t *vsecp);
-extern int zfs_rmdir(znode_t *dzp, char *name, znode_t *cwd,
-    cred_t *cr, int flags);
-extern int zfs_setattr(znode_t *zp, vattr_t *vap, int flag, cred_t *cr);
-extern int zfs_rename(znode_t *sdzp, char *snm, znode_t *tdzp,
-    char *tnm, cred_t *cr, int flags);
-extern int zfs_symlink(znode_t *dzp, const char *name, vattr_t *vap,
-    const char *link, znode_t **zpp, cred_t *cr, int flags);
-extern int zfs_link(znode_t *tdzp, znode_t *sp,
-    char *name, cred_t *cr, int flags);
-extern int zfs_space(znode_t *zp, int cmd, struct flock *bfp, int flag,
-    offset_t offset, cred_t *cr);
-extern int zfs_create(znode_t *dzp, char *name, vattr_t *vap, int excl,
-    int mode, znode_t **zpp, cred_t *cr, int flag, vsecattr_t *vsecp);
-extern int zfs_setsecattr(znode_t *zp, vsecattr_t *vsecp, int flag,
-    cred_t *cr);
-extern int zfs_write_simple(znode_t *zp, const void *data, size_t len,
-    loff_t pos, size_t *resid);
 
 #endif

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

@@ -169,7 +169,6 @@ extern void	zfs_tstamp_update_setup_ext(struct znode *,
     uint_t, uint64_t [2], uint64_t [2], boolean_t have_tx);
 extern void zfs_znode_free(struct znode *);
 
-extern zil_get_data_t zfs_get_data;
 extern zil_replay_func_t *zfs_replay_vector[TX_MAX_TYPE];
 extern int zfsfstype;
 

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

@@ -21,7 +21,7 @@ KERNEL_H = \
 	zfs_ctldir.h \
 	zfs_dir.h \
 	zfs_vfsops_os.h \
-	zfs_vnops.h \
+	zfs_vnops_os.h \
 	zfs_znode_impl.h \
 	zpl.h
 

include/os/linux/zfs/sys/zfs_vnops.h → include/os/linux/zfs/sys/zfs_vnops_os.h

@@ -22,8 +22,8 @@
  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
  */
 
-#ifndef	_SYS_FS_ZFS_VNOPS_H
-#define	_SYS_FS_ZFS_VNOPS_H
+#ifndef	_SYS_FS_ZFS_VNOPS_OS_H_
+#define	_SYS_FS_ZFS_VNOPS_OS_H_
 
 #include <sys/vnode.h>
 #include <sys/xvattr.h>
@@ -42,50 +42,30 @@ extern int zfs_open(struct inode *ip, int mode, int flag, cred_t *cr);
 extern int zfs_close(struct inode *ip, int flag, cred_t *cr);
 extern int zfs_holey(struct inode *ip, int cmd, loff_t *off);
 extern int zfs_read(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr);
-extern int zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr);
-extern int zfs_write_simple(znode_t *zp, const void *data, size_t len,
-    loff_t pos, size_t *resid);
 extern int zfs_access(struct inode *ip, int mode, int flag, cred_t *cr);
 extern int zfs_lookup(znode_t *dzp, char *nm, znode_t **zpp,
     int flags, cred_t *cr, int *direntflags, pathname_t *realpnp);
-extern int zfs_create(znode_t *dzp, char *name, vattr_t *vap, int excl,
-    int mode, znode_t **zpp, cred_t *cr, int flag, vsecattr_t *vsecp);
 extern int zfs_tmpfile(struct inode *dip, vattr_t *vapzfs, int excl,
     int mode, struct inode **ipp, cred_t *cr, int flag, vsecattr_t *vsecp);
 extern int zfs_remove(znode_t *dzp, char *name, cred_t *cr, int flags);
-extern int zfs_mkdir(znode_t *dzp, char *dirname, vattr_t *vap,
-    znode_t **zpp, cred_t *cr, int flags, vsecattr_t *vsecp);
-extern int zfs_rmdir(znode_t *dzp, char *name, znode_t *cwd,
-    cred_t *cr, int flags);
 extern int zfs_readdir(struct inode *ip, zpl_dir_context_t *ctx, cred_t *cr);
 extern int zfs_fsync(znode_t *zp, int syncflag, cred_t *cr);
 extern int zfs_getattr_fast(struct inode *ip, struct kstat *sp);
-extern int zfs_setattr(znode_t *zp, vattr_t *vap, int flag, cred_t *cr);
-extern int zfs_rename(znode_t *sdzp, char *snm, znode_t *tdzp,
-    char *tnm, cred_t *cr, int flags);
-extern int zfs_symlink(znode_t *dzp, char *name, vattr_t *vap,
-    char *link, znode_t **zpp, cred_t *cr, int flags);
 extern int zfs_readlink(struct inode *ip, uio_t *uio, cred_t *cr);
-extern int zfs_link(znode_t *tdzp, znode_t *szp,
-    char *name, cred_t *cr, int flags);
 extern void zfs_inactive(struct inode *ip);
-extern int zfs_space(znode_t *zp, int cmd, flock64_t *bfp, int flag,
-    offset_t offset, cred_t *cr);
 extern int zfs_fid(struct inode *ip, fid_t *fidp);
 extern int zfs_getsecattr(struct inode *ip, vsecattr_t *vsecp, int flag,
     cred_t *cr);
-extern int zfs_setsecattr(znode_t *zp, vsecattr_t *vsecp, int flag,
-    cred_t *cr);
 extern int zfs_getpage(struct inode *ip, struct page *pl[], int nr_pages);
 extern int zfs_putpage(struct inode *ip, struct page *pp,
     struct writeback_control *wbc);
 extern int zfs_dirty_inode(struct inode *ip, int flags);
 extern int zfs_map(struct inode *ip, offset_t off, caddr_t *addrp,
     size_t len, unsigned long vm_flags);
-extern void zfs_zrele_async(znode_t *zp);
+extern int zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr);
 
 #ifdef	__cplusplus
 }
 #endif
 
-#endif	/* _SYS_FS_ZFS_VNOPS_H */
+#endif	/* _SYS_FS_ZFS_VNOPS_OS_H_ */

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

@@ -157,7 +157,6 @@ extern caddr_t zfs_map_page(page_t *, enum seg_rw);
 extern void zfs_unmap_page(page_t *, caddr_t);
 #endif /* HAVE_UIO_RW */
 
-extern zil_get_data_t zfs_get_data;
 extern zil_replay_func_t *zfs_replay_vector[TX_MAX_TYPE];
 extern int zfsfstype;
 

include/sys/Makefile.am

@@ -117,6 +117,7 @@ COMMON_H = \
 	zfs_stat.h \
 	zfs_sysfs.h \
 	zfs_vfsops.h \
+	zfs_vnops.h \
 	zfs_znode.h \
 	zil.h \
 	zil_impl.h \

include/sys/zfs_vnops.h

@@ -0,0 +1,48 @@
+#ifndef _SYS_ZFS_VNOPS_H_
+#define	_SYS_ZFS_VNOPS_H_
+
+#include <sys/zil.h>
+
+/*
+ * Functions declared in this file implement equivalent behavior on
+ * all platforms.
+ * OS-specific additions are in zfs_vnops_os.h.
+ */
+
+
+/*
+ * Platform code that asynchronously drops zp's inode / vnode_t.
+ *
+ * Asynchronous dropping ensures that the caller will never drop the
+ * last reference on an inode / vnode_t in the current context.
+ * Doing so while holding open a tx could result in a deadlock if
+ * the platform calls into filesystem again in the implementation
+ * of inode / vnode_t dropping (e.g. call from iput_final()).
+ */
+extern void zfs_zrele_async(znode_t *zp);
+
+extern zil_get_data_t zfs_get_data;
+
+extern int zfs_create(znode_t *dzp, char *name, vattr_t *vap, int excl,
+    int mode, znode_t **zpp, cred_t *cr, int flag, vsecattr_t *vsecp);
+
+extern int zfs_remove(znode_t *dzp, char *name, cred_t *cr, int flags);
+extern int zfs_mkdir(znode_t *dzp, char *dirname, vattr_t *vap,
+    znode_t **zpp, cred_t *cr, int flags, vsecattr_t *vsecp);
+extern int zfs_rmdir(znode_t *dzp, char *name, znode_t *cwd,
+    cred_t *cr, int flags);
+extern int zfs_setattr(znode_t *zp, vattr_t *vap, int flag, cred_t *cr);
+extern int zfs_rename(znode_t *sdzp, char *snm, znode_t *tdzp,
+    char *tnm, cred_t *cr, int flags);
+extern int zfs_symlink(znode_t *dzp, char *name, vattr_t *vap, char *link,
+    znode_t **zpp, cred_t *cr, int flags);
+extern int zfs_link(znode_t *tdzp, znode_t *sp,
+    char *name, cred_t *cr, int flags);
+extern int zfs_space(znode_t *zp, int cmd, struct flock *bfp, int flag,
+    offset_t offset, cred_t *cr);
+extern int zfs_setsecattr(znode_t *zp, vsecattr_t *vsecp, int flag,
+    cred_t *cr);
+extern int zfs_write_simple(znode_t *zp, const void *data, size_t len,
+    loff_t pos, size_t *resid);
+
+#endif

module/Makefile.bsd

@@ -150,7 +150,7 @@ SRCS+=	abd_os.c \
 	zfs_log.c \
 	zfs_replay.c \
 	zfs_vfsops.c \
-	zfs_vnops.c \
+	zfs_vnops_os.c \
 	zfs_znode.c \
 	zio_crypt.c \
 	zvol_os.c
@@ -286,6 +286,7 @@ SRCS+=	abd.c \
 	zfs_ratelimit.c \
 	zfs_rlock.c \
 	zfs_sa.c \
+	zfs_vnops.c \
 	zil.c \
 	zio.c \
 	zio_checksum.c \
@@ -323,7 +324,7 @@ CFLAGS.spl_vm.c= -Wno-cast-qual
 CFLAGS.spl_zlib.c= -Wno-cast-qual
 CFLAGS.abd.c= -Wno-cast-qual
 CFLAGS.zfs_log.c= -Wno-cast-qual
-CFLAGS.zfs_vnops.c= -Wno-pointer-arith
+CFLAGS.zfs_vnops_os.c= -Wno-pointer-arith
 CFLAGS.u8_textprep.c= -Wno-cast-qual
 CFLAGS.zfs_fletcher.c= -Wno-cast-qual -Wno-pointer-arith
 CFLAGS.zfs_fletcher_intel.c= -Wno-cast-qual -Wno-pointer-arith

module/os/freebsd/zfs/dmu_os.c

@@ -55,6 +55,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/vm.h>
 #include <sys/zfs_znode.h>
 #include <sys/zfs_vnops.h>
+#include <sys/zfs_vnops_os.h>
 
 #include <sys/ccompat.h>
 

module/os/freebsd/zfs/zfs_vfsops.c

@@ -42,6 +42,7 @@
 #include <sys/mount.h>
 #include <sys/cmn_err.h>
 #include <sys/zfs_znode.h>
+#include <sys/zfs_vnops.h>
 #include <sys/zfs_dir.h>
 #include <sys/zil.h>
 #include <sys/fs/zfs.h>