zfs/sys/zap_leaf.h

	zap_leaf.h revision f65e61c04bc28ffd6bda04619c84330b420450b5
/*
 * 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 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#ifndef _SYS_ZAP_LEAF_H
#define _SYS_ZAP_LEAF_H

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

#ifdef  __cplusplus
extern "C" {
#endif

struct zap;

#define ZAP_LEAF_MAGIC 0x2AB1EAF

/* chunk size = 24 bytes */
#define ZAP_LEAF_CHUNKSIZE 24

/*
 * The amount of space available for chunks is:
 * block size (1<<l->l_bs) - hash entry size (2) * number of hash
 * entries - header space (2*chunksize)
 */
#define ZAP_LEAF_NUMCHUNKS(l) \
    (((1<<(l)->l_bs) - 2*ZAP_LEAF_HASH_NUMENTRIES(l)) / \
    ZAP_LEAF_CHUNKSIZE - 2)

/*
 * The amount of space within the chunk available for the array is:
 * chunk size - space for type (1) - space for next pointer (2)
 */
#define ZAP_LEAF_ARRAY_BYTES (ZAP_LEAF_CHUNKSIZE - 3)

/*
 * The leaf hash table has block size / 2^5 (32) number of entries,
 * which should be more than enough for the maximum number of entries,
 * which is less than block size / CHUNKSIZE (24) / minimum number of
 * chunks per entry (3).
 */
#define ZAP_LEAF_HASH_SHIFT(l) ((l)->l_bs - 5)
#define ZAP_LEAF_HASH_NUMENTRIES(l) (1 << ZAP_LEAF_HASH_SHIFT(l))

/*
 * The chunks start immediately after the hash table.  The end of the
 * hash table is at l_hash + HASH_NUMENTRIES, which we simply cast to a
 * chunk_t.
 */
#define ZAP_LEAF_CHUNK(l, idx) \
    ((zap_leaf_chunk_t *) \
    ((l)->l_phys->l_hash + ZAP_LEAF_HASH_NUMENTRIES(l)))[idx]
#define ZAP_LEAF_ENTRY(l, idx) (&ZAP_LEAF_CHUNK(l, idx).l_entry)

typedef enum zap_chunk_type {
    ZAP_CHUNK_FREE = 253,
    ZAP_CHUNK_ENTRY = 252,
    ZAP_CHUNK_ARRAY = 251,
    ZAP_CHUNK_TYPE_MAX = 250
} zap_chunk_type_t;

/*
 * TAKE NOTE:
 * If zap_leaf_phys_t is modified, zap_leaf_byteswap() must be modified.
 */
typedef struct zap_leaf_phys {
    struct zap_leaf_header {
        uint64_t lhr_block_type;    /* ZBT_LEAF */
        uint64_t lhr_next;      /* next block in leaf chain */
        uint64_t lhr_prefix;
        uint32_t lhr_magic;     /* ZAP_LEAF_MAGIC */
        uint16_t lhr_nfree;     /* number free chunks */
        uint16_t lhr_nentries;      /* number of entries */
        uint16_t lhr_prefix_len;

#define lh_block_type   l_phys->l_hdr.lhr_block_type
#define lh_magic    l_phys->l_hdr.lhr_magic
#define lh_next     l_phys->l_hdr.lhr_next
#define lh_prefix   l_phys->l_hdr.lhr_prefix
#define lh_nfree    l_phys->l_hdr.lhr_nfree
#define lh_prefix_len   l_phys->l_hdr.lhr_prefix_len
#define lh_nentries     l_phys->l_hdr.lhr_nentries

/* above is accessable to zap, below is zap_leaf private */

        uint16_t lh_freelist;       /* chunk head of free list */
        uint8_t lh_pad2[12];
    } l_hdr; /* 2 24-byte chunks */

    /*
     * The header is followed by a hash table with
     * ZAP_LEAF_HASH_NUMENTRIES(zap) entries.  The hash table is
     * followed by an array of ZAP_LEAF_NUMCHUNKS(zap)
     * zap_leaf_chunk structures.  These structures are accessed
     * with the ZAP_LEAF_CHUNK() macro.
     */

    uint16_t l_hash[1];
} zap_leaf_phys_t;

typedef union zap_leaf_chunk {
    struct zap_leaf_entry {
        uint8_t le_type;        /* always ZAP_CHUNK_ENTRY */
        uint8_t le_int_size;        /* size of ints */
        uint16_t le_next;       /* next entry in hash chain */
        uint16_t le_name_chunk;     /* first chunk of the name */
        uint16_t le_name_length;    /* bytes in name, incl null */
        uint16_t le_value_chunk;    /* first chunk of the value */
        uint16_t le_value_length;   /* value length in ints */
        uint32_t le_cd;         /* collision differentiator */
        uint64_t le_hash;       /* hash value of the name */
    } l_entry;
    struct zap_leaf_array {
        uint8_t la_type;        /* always ZAP_CHUNK_ARRAY */
        uint8_t la_array[ZAP_LEAF_ARRAY_BYTES];
        uint16_t la_next;       /* next blk or CHAIN_END */
    } l_array;
    struct zap_leaf_free {
        uint8_t lf_type;        /* always ZAP_CHUNK_FREE */
        uint8_t lf_pad[ZAP_LEAF_ARRAY_BYTES];
        uint16_t lf_next;   /* next in free list, or CHAIN_END */
    } l_free;
} zap_leaf_chunk_t;

typedef struct zap_leaf {
    krwlock_t l_rwlock;         /* only used on head of chain */
    uint64_t l_blkid;       /* 1<<ZAP_BLOCK_SHIFT byte block off */
    int l_bs;           /* block size shift */
    struct zap_leaf *l_next;    /* next in chain */
    dmu_buf_t *l_dbuf;
    zap_leaf_phys_t *l_phys;
} zap_leaf_t;


typedef struct zap_entry_handle {
    /* below is set by zap_leaf.c and is public to zap.c */
    uint64_t zeh_num_integers;
    uint64_t zeh_hash;
    uint32_t zeh_cd;
    uint8_t zeh_integer_size;

    /* below is private to zap_leaf.c */
    uint16_t zeh_fakechunk;
    uint16_t *zeh_chunkp;
    zap_leaf_t *zeh_head_leaf;
    zap_leaf_t *zeh_found_leaf;
} zap_entry_handle_t;

/*
 * Return a handle to the named entry, or ENOENT if not found.  The hash
 * value must equal zap_hash(name).
 */
extern int zap_leaf_lookup(zap_leaf_t *l,
    const char *name, uint64_t h, zap_entry_handle_t *zeh);

/*
 * Return a handle to the entry with this hash+cd, or the entry with the
 * next closest hash+cd.
 */
extern int zap_leaf_lookup_closest(zap_leaf_t *l,
    uint64_t hash, uint32_t cd, zap_entry_handle_t *zeh);

/*
 * Read the first num_integers in the attribute.  Integer size
 * conversion will be done without sign extension.  Return EINVAL if
 * integer_size is too small.  Return EOVERFLOW if there are more than
 * num_integers in the attribute.
 */
extern int zap_entry_read(const zap_entry_handle_t *zeh,
    uint8_t integer_size, uint64_t num_integers, void *buf);

extern int zap_entry_read_name(const zap_entry_handle_t *zeh,
    uint16_t buflen, char *buf);

/*
 * Replace the value of an existing entry.
 *
 * zap_entry_update may fail if it runs out of space (ENOSPC).
 */
extern int zap_entry_update(zap_entry_handle_t *zeh,
    uint8_t integer_size, uint64_t num_integers, const void *buf);

/*
 * Remove an entry.
 */
extern void zap_entry_remove(zap_entry_handle_t *zeh);

/*
 * Create an entry. An equal entry must not exist, and this entry must
 * belong in this leaf (according to its hash value).  Fills in the
 * entry handle on success.  Returns 0 on success or ENOSPC on failure.
 */
extern int zap_entry_create(zap_leaf_t *l,
    const char *name, uint64_t h, uint32_t cd,
    uint8_t integer_size, uint64_t num_integers, const void *buf,
    zap_entry_handle_t *zeh);

/*
 * Other stuff.
 */

extern void zap_leaf_init(zap_leaf_t *l);
extern void zap_leaf_byteswap(zap_leaf_phys_t *buf, int len);

extern zap_leaf_t *zap_leaf_split(struct zap *zap, zap_leaf_t *l, dmu_tx_t *tx);

extern int zap_leaf_merge(zap_leaf_t *l, zap_leaf_t *sibling);

extern zap_leaf_t *zap_leaf_chainmore(zap_leaf_t *l, zap_leaf_t *nl);

extern int zap_leaf_advance(zap_leaf_t *l, zap_cursor_t *zc);

extern void zap_stats_leaf(zap_t *zap, zap_leaf_t *l, zap_stats_t *zs);

#ifdef  __cplusplus
}
#endif

#endif /* _SYS_ZAP_LEAF_H */