Combine OS-independent ABD Code into Common Source File

Reorganizing ABD code base so OS-independent ABD code has been placed
into a common abd.c file. OS-dependent ABD code has been left in each
OS's ABD source files, and these source files have been renamed to
abd_os.

The OS-independent ABD code is now under:
module/zfs/abd.c
With the OS-dependent code in:
module/os/linux/zfs/abd_os.c
module/os/freebsd/zfs/abd_os.c

Reviewed-by: Matthew Ahrens <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Brian Atkinson <[email protected]>
Closes #10293 

1 files changed, 126 insertions, 0 deletions

diff --git a/include/sys/abd_impl.h b/include/sys/abd_impl.h
new file mode 100644
index 000000000..6027678af
--- /dev/null
+++ b/include/sys/abd_impl.h
@@ -0,0 +1,126 @@
+/*
+ * 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 (c) 2014 by Chunwei Chen. All rights reserved.
+ * Copyright (c) 2016, 2019 by Delphix. All rights reserved.
+ */
+
+#ifndef _ABD_IMPL_H
+#define	_ABD_IMPL_H
+
+#include <sys/abd.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum abd_flags {
+	ABD_FLAG_LINEAR		= 1 << 0, /* is buffer linear (or scattered)? */
+	ABD_FLAG_OWNER		= 1 << 1, /* does it own its data buffers? */
+	ABD_FLAG_META		= 1 << 2, /* does this represent FS metadata? */
+	ABD_FLAG_MULTI_ZONE  	= 1 << 3, /* pages split over memory zones */
+	ABD_FLAG_MULTI_CHUNK 	= 1 << 4, /* pages split over multiple chunks */
+	ABD_FLAG_LINEAR_PAGE 	= 1 << 5, /* linear but allocd from page */
+} abd_flags_t;
+
+typedef enum abd_stats_op {
+	ABDSTAT_INCR, /* Increase abdstat values */
+	ABDSTAT_DECR  /* Decrease abdstat values */
+} abd_stats_op_t;
+
+struct abd {
+	abd_flags_t	abd_flags;
+	uint_t		abd_size;	/* excludes scattered abd_offset */
+	struct abd	*abd_parent;
+	zfs_refcount_t	abd_children;
+	union {
+		struct abd_scatter {
+			uint_t		abd_offset;
+#if defined(__FreeBSD__) && defined(_KERNEL)
+			uint_t  abd_chunk_size;
+			void    *abd_chunks[];
+#else
+			uint_t		abd_nents;
+			struct scatterlist *abd_sgl;
+#endif
+		} abd_scatter;
+		struct abd_linear {
+			void		*abd_buf;
+			struct scatterlist *abd_sgl; /* for LINEAR_PAGE */
+		} abd_linear;
+	} abd_u;
+};
+
+struct scatterlist; /* forward declaration */
+
+struct abd_iter {
+	/* public interface */
+	void		*iter_mapaddr;	/* addr corresponding to iter_pos */
+	size_t		iter_mapsize;	/* length of data valid at mapaddr */
+
+	/* private */
+	abd_t		*iter_abd;	/* ABD being iterated through */
+	size_t		iter_pos;
+	size_t		iter_offset;	/* offset in current sg/abd_buf, */
+					/* abd_offset included */
+	struct scatterlist *iter_sg;	/* current sg */
+};
+
+/*
+ * OS specific functions
+ */
+
+abd_t *abd_alloc_struct(size_t);
+abd_t *abd_get_offset_scatter(abd_t *, size_t);
+void abd_free_struct(abd_t *);
+void abd_alloc_chunks(abd_t *, size_t);
+void abd_free_chunks(abd_t *);
+boolean_t abd_size_alloc_linear(size_t);
+void abd_update_scatter_stats(abd_t *, abd_stats_op_t);
+void abd_update_linear_stats(abd_t *, abd_stats_op_t);
+void abd_verify_scatter(abd_t *);
+void abd_free_linear_page(abd_t *);
+void abd_enter_critical(unsigned long);
+void abd_exit_critical(unsigned long);
+/* OS specific abd_iter functions */
+void abd_iter_init(struct abd_iter  *, abd_t *);
+boolean_t abd_iter_at_end(struct abd_iter *);
+void abd_iter_advance(struct abd_iter *, size_t);
+void abd_iter_map(struct abd_iter *);
+void abd_iter_unmap(struct abd_iter *);
+
+/*
+ * Helper macros
+ */
+#define	ABDSTAT(stat)		(abd_stats.stat.value.ui64)
+#define	ABDSTAT_INCR(stat, val) \
+	atomic_add_64(&abd_stats.stat.value.ui64, (val))
+#define	ABDSTAT_BUMP(stat)	ABDSTAT_INCR(stat, 1)
+#define	ABDSTAT_BUMPDOWN(stat)	ABDSTAT_INCR(stat, -1)
+
+#define	ABD_SCATTER(abd)	(abd->abd_u.abd_scatter)
+#define	ABD_LINEAR_BUF(abd)	(abd->abd_u.abd_linear.abd_buf)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* _ABD_IMPL_H */