zfs/sys/dbuf.h

	dbuf.h revision 3b2aab18808792cbd248a12f1edf139b89833c13
/*
 * 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) 2012 by Delphix. All rights reserved.
 */

#ifndef _SYS_DBUF_H
#define _SYS_DBUF_H

#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>
#include <sys/zrlock.h>

#ifdef  __cplusplus
extern "C" {
#endif

#define IN_DMU_SYNC 2

/*
 * define flags for dbuf_read
 */

#define DB_RF_MUST_SUCCEED  (1 << 0)
#define DB_RF_CANFAIL       (1 << 1)
#define DB_RF_HAVESTRUCT    (1 << 2)
#define DB_RF_NOPREFETCH    (1 << 3)
#define DB_RF_NEVERWAIT     (1 << 4)
#define DB_RF_CACHED        (1 << 5)

/*
 * The simplified state transition diagram for dbufs looks like:
 *
 *      +----> READ ----+
 *      |       |
 *      |       V
 *  (alloc)-->UNCACHED       CACHED-->EVICTING-->(free)
 *      |       ^    ^
 *      |       |    |
 *      +----> FILL ----+    |
 *      |            |
 *      |            |
 *      +--------> NOFILL -------+
 */
typedef enum dbuf_states {
    DB_UNCACHED,
    DB_FILL,
    DB_NOFILL,
    DB_READ,
    DB_CACHED,
    DB_EVICTING
} dbuf_states_t;

struct dnode;
struct dmu_tx;

/*
 * level = 0 means the user data
 * level = 1 means the single indirect block
 * etc.
 */

struct dmu_buf_impl;

typedef enum override_states {
    DR_NOT_OVERRIDDEN,
    DR_IN_DMU_SYNC,
    DR_OVERRIDDEN
} override_states_t;

typedef struct dbuf_dirty_record {
    /* link on our parents dirty list */
    list_node_t dr_dirty_node;

    /* transaction group this data will sync in */
    uint64_t dr_txg;

    /* zio of outstanding write IO */
    zio_t *dr_zio;

    /* pointer back to our dbuf */
    struct dmu_buf_impl *dr_dbuf;

    /* pointer to next dirty record */
    struct dbuf_dirty_record *dr_next;

    /* pointer to parent dirty record */
    struct dbuf_dirty_record *dr_parent;

    union dirty_types {
        struct dirty_indirect {

            /* protect access to list */
            kmutex_t dr_mtx;

            /* Our list of dirty children */
            list_t dr_children;
        } di;
        struct dirty_leaf {

            /*
             * dr_data 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.
             */
            arc_buf_t *dr_data;
            blkptr_t dr_overridden_by;
            override_states_t dr_override_state;
            uint8_t dr_copies;
            boolean_t dr_nopwrite;
        } dl;
    } dt;
} dbuf_dirty_record_t;

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 *db_objset;

    /*
     * handle to safely access the dnode we belong to (NULL when evicted)
     */
    struct dnode_handle *db_dnode_handle;

    /*
     * our parent buffer; if the dnode points to us directly,
     * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
     * only accessed by sync thread ???
     * (NULL when evicted)
     * May change from NULL to non-NULL under the protection of db_mtx
     * (see dbuf_check_blkptr())
     */
    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;
    dbuf_dirty_record_t *db_data_pending;

    /* pointer to most recent dirty record for this buffer */
    dbuf_dirty_record_t *db_last_dirty;

    /*
     * Our link on the owner dnodes's dn_dbufs list.
     * Protected by its dn_dbufs_mtx.
     */
    list_node_t db_link;

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

    /* 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;

    uint8_t db_dirtycnt;
} 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);
void dbuf_create_bonus(struct dnode *dn);
int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
void dbuf_spill_hold(struct dnode *dn, dmu_buf_impl_t **dbp, void *tag);

void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);

dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
    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);
uint64_t dbuf_refcount(dmu_buf_impl_t *db);

void dbuf_rele(dmu_buf_impl_t *db, void *tag);
void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag);

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

int dbuf_read(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_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx);
void dmu_buf_will_not_fill(dmu_buf_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_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);

void dbuf_clear(dmu_buf_impl_t *db);
void dbuf_evict(dmu_buf_impl_t *db);

void dbuf_setdirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
void dbuf_unoverride(dbuf_dirty_record_t *dr);
void dbuf_sync_list(list_t *list, dmu_tx_t *tx);
void dbuf_release_bp(dmu_buf_impl_t *db);

void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
    struct dmu_tx *);

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

#define DB_DNODE(_db)       ((_db)->db_dnode_handle->dnh_dnode)
#define DB_DNODE_LOCK(_db)  ((_db)->db_dnode_handle->dnh_zrlock)
#define DB_DNODE_ENTER(_db) (zrl_add(&DB_DNODE_LOCK(_db)))
#define DB_DNODE_EXIT(_db)  (zrl_remove(&DB_DNODE_LOCK(_db)))
#define DB_DNODE_HELD(_db)  (!zrl_is_zero(&DB_DNODE_LOCK(_db)))
#define DB_GET_SPA(_spa_p, _db) {       \
    dnode_t *__dn;              \
    DB_DNODE_ENTER(_db);            \
    __dn = DB_DNODE(_db);           \
    *(_spa_p) = __dn->dn_objset->os_spa;    \
    DB_DNODE_EXIT(_db);         \
}
#define DB_GET_OBJSET(_os_p, _db) {     \
    dnode_t *__dn;              \
    DB_DNODE_ENTER(_db);            \
    __dn = DB_DNODE(_db);           \
    *(_os_p) = __dn->dn_objset;     \
    DB_DNODE_EXIT(_db);         \
}

void dbuf_init(void);
void dbuf_fini(void);

boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);

#define DBUF_GET_BUFC_TYPE(_db) \
    (dbuf_is_metadata(_db) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)

#define DBUF_IS_CACHEABLE(_db)                      \
    ((_db)->db_objset->os_primary_cache == ZFS_CACHE_ALL ||     \
    (dbuf_is_metadata(_db) &&                   \
    ((_db)->db_objset->os_primary_cache == ZFS_CACHE_METADATA)))

#define DBUF_IS_L2CACHEABLE(_db)                    \
    ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_ALL ||   \
    (dbuf_is_metadata(_db) &&                   \
    ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_METADATA)))

#ifdef ZFS_DEBUG

/*
 * There should be a ## between the string literal and fmt, to make it
 * clear that we're joining two strings together, but gcc does not
 * support that preprocessor token.
 */
#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 {          \
    if (zfs_flags & ZFS_DEBUG_DPRINTF) {            \
    char *__blkbuf = kmem_alloc(BP_SPRINTF_LEN, KM_SLEEP);  \
    sprintf_blkptr(__blkbuf, bp);               \
    dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);   \
    kmem_free(__blkbuf, BP_SPRINTF_LEN);            \
    }                           \
_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 */