/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License, Version 1.0 only

 * (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 2005 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

#ifndef	_SYS_DBUF_H

#define	_SYS_DBUF_H

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include <sys/dmu.h>

#include <sys/spa.h>

#include <sys/txg.h>

#include <sys/zio.h>

#include <sys/arc.h>

#include <sys/zfs_context.h>

#include <sys/refcount.h>

#ifdef	__cplusplus

extern "C" {

#endif

#define	DB_BONUS_BLKID (-1ULL)

#define	IN_DMU_SYNC ((blkptr_t *)-1)

/*

 * define flags for dbuf_read and friends

 */

#define	DB_RF_MUST_SUCCEED	0

#define	DB_RF_CANFAIL		(1 << 1)

#define	DB_RF_HAVESTRUCT	(1 << 2)

#define	DB_RF_NOPREFETCH	(1 << 3)

/*

 * The state transition diagram for dbufs looks like:

 *

 *		+----> READ ----+

 *		|		|

 *		|		V

 *   (alloc)-->UNCACHED	     CACHED-->(free)

 *		|		^

 *		|		|

 *		+----> FILL ----+

 */

typedef enum dbuf_states {

	DB_UNCACHED,

	DB_FILL,

	DB_READ,

	DB_CACHED

} dbuf_states_t;

struct objset_impl;

struct dnode;

struct dmu_tx;

/*

 * level = 0 means the user data

 * level = 1 means the single indirect block

 * etc.

 */

#define	LIST_LINK_INACTIVE(link) \

	((link)->list_next == NULL && (link)->list_prev == NULL)

typedef struct dmu_buf_impl {

	/*

	 * The following members are immutable, with the exception of

	 * db.db_data, which is protected by db_mtx.

	 */

	/* the publicly visible structure */

	dmu_buf_t db;

	/* the objset we belong to */

	struct objset_impl *db_objset;

	/*

	 * the dnode we belong to (NULL when evicted)

	 */

	struct dnode *db_dnode;

	/*

	 * our parent buffer; if the dnode points to us directly,

	 * db_parent == db_dnode->dn_dbuf

	 * only accessed by sync thread ???

	 * (NULL when evicted)

	 */

	struct dmu_buf_impl *db_parent;

	/*

	 * link for hash table of all dmu_buf_impl_t's

	 */

	struct dmu_buf_impl *db_hash_next;

	/* our block number */

	uint64_t db_blkid;

	/*

	 * Pointer to the blkptr_t which points to us. May be NULL if we

	 * don't have one yet. (NULL when evicted)

	 */

	blkptr_t *db_blkptr;

	/*

	 * Our indirection level.  Data buffers have db_level==0.

	 * Indirect buffers which point to data buffers have

	 * db_level==1. etc.  Buffers which contain dnodes have

	 * db_level==0, since the dnodes are stored in a file.

	 */

	uint8_t db_level;

	/* db_mtx protects the members below */

	kmutex_t db_mtx;

	/*

	 * Current state of the buffer

	 */

	dbuf_states_t db_state;

	/*

	 * Refcount accessed by dmu_buf_{hold,rele}.

	 * If nonzero, the buffer can't be destroyed.

	 * Protected by db_mtx.

	 */

	refcount_t db_holds;

	/* buffer holding our data */

	arc_buf_t *db_buf;

	kcondvar_t db_changed;

	arc_buf_t *db_data_pending;

	/*

	 * Last time (transaction group) this buffer was dirtied.

	 */

	uint64_t db_dirtied;

	/*

	 * If dd_dnode != NULL, our link on the owner dnodes's dn_dbufs list.

	 * Protected by its dn_mtx.

	 */

	list_node_t db_link;

	/* Our link on dn_dirty_dbufs[txg] */

	list_node_t db_dirty_node[TXG_SIZE];

	uint8_t db_dirtycnt;

	/*

	 * Data which is unique to data (leaf) blocks:

	 */

	struct {

		/* stuff we store for the user (see dmu_buf_set_user) */

		void *db_user_ptr;

		void **db_user_data_ptr_ptr;

		dmu_buf_evict_func_t *db_evict_func;

		uint8_t db_immediate_evict;

		uint8_t db_freed_in_flight;

		/*

		 * db_data_old[txg&TXG_MASK] is set when we

		 * dirty the buffer, so that we can retain the

		 * pointer even if it gets COW'd in a subsequent

		 * transaction group.

		 *

		 * If the buffer is dirty in any txg, it can't

		 * be destroyed.

		 */

		/*

		 * XXX Protected by db_mtx and dn_dirty_mtx.

		 * db_mtx must be held to read db_dirty[], and

		 * both db_mtx and dn_dirty_mtx must be held to

		 * modify (dirty or clean). db_mtx must be held

		 * before dn_dirty_mtx.

		 */

		arc_buf_t *db_data_old[TXG_SIZE];

		blkptr_t *db_overridden_by[TXG_SIZE];

	} db_d;

} dmu_buf_impl_t;

/* Note: the dbuf hash table is exposed only for the mdb module */

#define	DBUF_MUTEXES 256

#define	DBUF_HASH_MUTEX(h, idx) (&(h)->hash_mutexes[(idx) & (DBUF_MUTEXES-1)])

typedef struct dbuf_hash_table {

	uint64_t hash_table_mask;

	dmu_buf_impl_t **hash_table;

	kmutex_t hash_mutexes[DBUF_MUTEXES];

} dbuf_hash_table_t;

uint64_t dbuf_whichblock(struct dnode *di, uint64_t offset);

dmu_buf_impl_t *dbuf_create_tlib(struct dnode *dn, char *data);

dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid);

dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,

    void *tag);

dmu_buf_impl_t *dbuf_hold_bonus(struct dnode *dn, void *tag);

int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid, int create,

    void *tag, dmu_buf_impl_t **dbp);

void dbuf_prefetch(struct dnode *dn, uint64_t blkid);

void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);

void dbuf_remove_ref(dmu_buf_impl_t *db, void *tag);

uint64_t dbuf_refcount(dmu_buf_impl_t *db);

void dbuf_rele(dmu_buf_impl_t *db);

dmu_buf_impl_t *dbuf_find(struct dnode *dn, uint8_t level, uint64_t blkid);

void dbuf_read(dmu_buf_impl_t *db);

int dbuf_read_canfail(dmu_buf_impl_t *db);

void dbuf_read_havestruct(dmu_buf_impl_t *db);

void dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);

void dbuf_will_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);

void dbuf_will_fill(dmu_buf_impl_t *db, dmu_tx_t *tx);

void dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx);

void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);

void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);

void dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);

void dbuf_evict(dmu_buf_impl_t *db);

void dbuf_setdirty(dmu_buf_impl_t *db, dmu_tx_t *tx);

void dbuf_sync(dmu_buf_impl_t *db, zio_t *zio, dmu_tx_t *tx);

void dbuf_unoverride(dmu_buf_impl_t *db, uint64_t txg);

void dbuf_free_range(struct dnode *dn, uint64_t blkid, uint64_t nblks,

    struct dmu_tx *);

void dbuf_downgrade(dmu_buf_impl_t *db, int evicting);

void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);

void dbuf_init(void);

void dbuf_fini(void);

#ifdef ZFS_DEBUG

/*

 * There should be a ## between the string literal and fmt, to make it

 */

#define	dprintf_dbuf(dbuf, fmt, ...) do { \

	if (zfs_flags & ZFS_DEBUG_DPRINTF) { \

	char __db_buf[32]; \

	uint64_t __db_obj = (dbuf)->db.db_object; \

	if (__db_obj == DMU_META_DNODE_OBJECT) \

		(void) strcpy(__db_buf, "mdn"); \

	else \

		(void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \

		    (u_longlong_t)__db_obj); \

	dprintf_ds((dbuf)->db_objset->os_dsl_dataset, \

	    "obj=%s lvl=%u blkid=%lld " fmt, \

	    __db_buf, (dbuf)->db_level, \

	    (u_longlong_t)(dbuf)->db_blkid, __VA_ARGS__); \

	} \

_NOTE(CONSTCOND) } while (0)

#define	dprintf_dbuf_bp(db, bp, fmt, ...) do {			\

	dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);	\

	} \

_NOTE(CONSTCOND) } while (0)

#define	DBUF_VERIFY(db)	dbuf_verify(db)

#else

#define	dprintf_dbuf(db, fmt, ...)

#define	dprintf_dbuf_bp(db, bp, fmt, ...)

#define	DBUF_VERIFY(db)

#endif

#ifdef	__cplusplus

}

#endif

#endif /* _SYS_DBUF_H */