zfs/include/sys/arc_impl.h

/*
 * 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) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2013 by Delphix. All rights reserved.
 * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
 * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
 */

#ifndef _SYS_ARC_IMPL_H
#define	_SYS_ARC_IMPL_H

#include <sys/arc.h>

#ifdef __cplusplus
extern "C" {
#endif

/*
 * Note that buffers can be in one of 6 states:
 *	ARC_anon	- anonymous (discussed below)
 *	ARC_mru		- recently used, currently cached
 *	ARC_mru_ghost	- recentely used, no longer in cache
 *	ARC_mfu		- frequently used, currently cached
 *	ARC_mfu_ghost	- frequently used, no longer in cache
 *	ARC_l2c_only	- exists in L2ARC but not other states
 * When there are no active references to the buffer, they are
 * are linked onto a list in one of these arc states.  These are
 * the only buffers that can be evicted or deleted.  Within each
 * state there are multiple lists, one for meta-data and one for
 * non-meta-data.  Meta-data (indirect blocks, blocks of dnodes,
 * etc.) is tracked separately so that it can be managed more
 * explicitly: favored over data, limited explicitly.
 *
 * Anonymous buffers are buffers that are not associated with
 * a DVA.  These are buffers that hold dirty block copies
 * before they are written to stable storage.  By definition,
 * they are "ref'd" and are considered part of arc_mru
 * that cannot be freed.  Generally, they will aquire a DVA
 * as they are written and migrate onto the arc_mru list.
 *
 * The ARC_l2c_only state is for buffers that are in the second
 * level ARC but no longer in any of the ARC_m* lists.  The second
 * level ARC itself may also contain buffers that are in any of
 * the ARC_m* states - meaning that a buffer can exist in two
 * places.  The reason for the ARC_l2c_only state is to keep the
 * buffer header in the hash table, so that reads that hit the
 * second level ARC benefit from these fast lookups.
 */

typedef struct arc_state {
	list_t	arcs_list[ARC_BUFC_NUMTYPES];	/* list of evictable buffers */
	uint64_t arcs_lsize[ARC_BUFC_NUMTYPES];	/* amount of evictable data */
	uint64_t arcs_size;	/* total amount of data in this state */
	kmutex_t arcs_mtx;
	arc_state_type_t arcs_state;
} arc_state_t;

typedef struct l2arc_buf_hdr l2arc_buf_hdr_t;

typedef struct arc_callback arc_callback_t;

struct arc_callback {
	void			*acb_private;
	arc_done_func_t		*acb_done;
	arc_buf_t		*acb_buf;
	zio_t			*acb_zio_dummy;
	arc_callback_t		*acb_next;
};

typedef struct arc_write_callback arc_write_callback_t;

struct arc_write_callback {
	void		*awcb_private;
	arc_done_func_t	*awcb_ready;
	arc_done_func_t	*awcb_physdone;
	arc_done_func_t	*awcb_done;
	arc_buf_t	*awcb_buf;
};

struct arc_buf_hdr {
	/* protected by hash lock */
	dva_t			b_dva;
	uint64_t		b_birth;
	uint64_t		b_cksum0;

	kmutex_t		b_freeze_lock;
	zio_cksum_t		*b_freeze_cksum;

	arc_buf_hdr_t		*b_hash_next;
	arc_buf_t		*b_buf;
	arc_flags_t		b_flags;
	uint32_t		b_datacnt;

	arc_callback_t		*b_acb;
	kcondvar_t		b_cv;

	/* immutable */
	arc_buf_contents_t	b_type;
	uint64_t		b_size;
	uint64_t		b_spa;

	/* protected by arc state mutex */
	arc_state_t		*b_state;
	list_node_t		b_arc_node;

	/* updated atomically */
	clock_t			b_arc_access;
	uint32_t		b_mru_hits;
	uint32_t		b_mru_ghost_hits;
	uint32_t		b_mfu_hits;
	uint32_t		b_mfu_ghost_hits;
	uint32_t		b_l2_hits;

	/* self protecting */
	refcount_t		b_refcnt;

	l2arc_buf_hdr_t		*b_l2hdr;
	list_node_t		b_l2node;
};

typedef struct l2arc_dev {
	vdev_t			*l2ad_vdev;	/* vdev */
	spa_t			*l2ad_spa;	/* spa */
	uint64_t		l2ad_hand;	/* next write location */
	uint64_t		l2ad_start;	/* first addr on device */
	uint64_t		l2ad_end;	/* last addr on device */
	uint64_t		l2ad_evict;	/* last addr eviction reached */
	boolean_t		l2ad_first;	/* first sweep through */
	boolean_t		l2ad_writing;	/* currently writing */
	list_t			*l2ad_buflist;	/* buffer list */
	list_node_t		l2ad_node;	/* device list node */
} l2arc_dev_t;

typedef struct l2arc_write_callback {
	l2arc_dev_t	*l2wcb_dev;		/* device info */
	arc_buf_hdr_t	*l2wcb_head;		/* head of write buflist */
} l2arc_write_callback_t;

#ifdef __cplusplus
}
#endif

#endif /* _SYS_ARC_IMPL_H */