FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/include/sys/zap_leaf.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 https://opensource.org/licenses/CDDL-1.0.
     * 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) 2014 Spectra Logic Corporation, All rights reserved.
     */
    
    #ifndef _SYS_ZAP_LEAF_H
    #define _SYS_ZAP_LEAF_H
    
    #include <sys/zap.h>
    
    #ifdef  __cplusplus
    extern "C" {
    #endif
    
    struct zap;
    struct zap_name;
    struct zap_stats;
    
    #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_BS(bs) \
            (((1<<(bs)) - 2*ZAP_LEAF_HASH_NUMENTRIES_BS(bs)) / \
            ZAP_LEAF_CHUNKSIZE - 2)
    
    #define ZAP_LEAF_NUMCHUNKS(l) (ZAP_LEAF_NUMCHUNKS_BS(((l)->l_bs)))
    
    #define ZAP_LEAF_NUMCHUNKS_DEF \
            (ZAP_LEAF_NUMCHUNKS_BS(fzap_default_block_shift))
    
    /*
     * 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)
    
    #define ZAP_LEAF_ARRAY_NCHUNKS(bytes) \
            (((bytes)+ZAP_LEAF_ARRAY_BYTES-1)/ZAP_LEAF_ARRAY_BYTES)
    
    /*
     * Low water mark:  when there are only this many chunks free, start
     * growing the ptrtbl.  Ideally, this should be larger than a
     * "reasonably-sized" entry.  20 chunks is more than enough for the
     * largest directory entry (MAXNAMELEN (256) byte name, 8-byte value),
     * while still being only around 3% for 16k blocks.
     */
    #define ZAP_LEAF_LOW_WATER (20)
    
    /*
     * 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_BS(bs) ((bs) - 5)
    #define ZAP_LEAF_HASH_NUMENTRIES_BS(bs) (1 << ZAP_LEAF_HASH_SHIFT_BS(bs))
    #define ZAP_LEAF_HASH_SHIFT(l) (ZAP_LEAF_HASH_SHIFT_BS(((l)->l_bs)))
    #define ZAP_LEAF_HASH_NUMENTRIES(l) (ZAP_LEAF_HASH_NUMENTRIES_BS(((l)->l_bs)))
    
    /*
     * 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 *) \
            (zap_leaf_phys(l)->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;
   
   #define ZLF_ENTRIES_CDSORTED (1<<0)
   
   /*
    * TAKE NOTE:
    * If zap_leaf_phys_t is modified, zap_leaf_byteswap() must be modified.
    */
   typedef struct zap_leaf_phys {
           struct zap_leaf_header {
                   /* Public to ZAP */
                   uint64_t lh_block_type;         /* ZBT_LEAF */
                   uint64_t lh_pad1;
                   uint64_t lh_prefix;             /* hash prefix of this leaf */
                   uint32_t lh_magic;              /* ZAP_LEAF_MAGIC */
                   uint16_t lh_nfree;              /* number free chunks */
                   uint16_t lh_nentries;           /* number of entries */
                   uint16_t lh_prefix_len;         /* num bits used to id this */
   
                   /* Private to zap_leaf */
                   uint16_t lh_freelist;           /* chunk head of free list */
                   uint8_t lh_flags;               /* ZLF_* flags */
                   uint8_t lh_pad2[11];
           } 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_value_intlen;        /* size of value's ints */
                   uint16_t le_next;               /* next entry in hash chain */
                   uint16_t le_name_chunk;         /* first chunk of the name */
                   uint16_t le_name_numints;       /* ints in name (incl null) */
                   uint16_t le_value_chunk;        /* first chunk of the value */
                   uint16_t le_value_numints;      /* 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 {
           dmu_buf_user_t l_dbu;
           krwlock_t l_rwlock;
           uint64_t l_blkid;               /* 1<<ZAP_BLOCK_SHIFT byte block off */
           int l_bs;                       /* block size shift */
           dmu_buf_t *l_dbuf;
   } zap_leaf_t;
   
   static inline zap_leaf_phys_t *
   zap_leaf_phys(zap_leaf_t *l)
   {
           return (l->l_dbuf->db_data);
   }
   
   typedef struct zap_entry_handle {
           /* Set by zap_leaf and public to ZAP */
           uint64_t zeh_num_integers;
           uint64_t zeh_hash;
           uint32_t zeh_cd;
           uint8_t zeh_integer_size;
   
           /* Private to zap_leaf */
           uint16_t zeh_fakechunk;
           uint16_t *zeh_chunkp;
           zap_leaf_t *zeh_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,
       struct zap_name *zn, 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(struct zap *zap, const zap_entry_handle_t *zeh,
       uint16_t buflen, char *buf);
   
   /*
    * Replace the value of an existing entry.
    *
    * 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, struct zap_name *zn, uint32_t cd,
       uint8_t integer_size, uint64_t num_integers, const void *buf,
       zap_entry_handle_t *zeh);
   
   /* Determine whether there is another entry with the same normalized form. */
   extern boolean_t zap_entry_normalization_conflict(zap_entry_handle_t *zeh,
       struct zap_name *zn, const char *name, struct zap *zap);
   
   /*
    * Other stuff.
    */
   
   extern void zap_leaf_init(zap_leaf_t *l, boolean_t sort);
   extern void zap_leaf_byteswap(zap_leaf_phys_t *buf, int len);
   extern void zap_leaf_split(zap_leaf_t *l, zap_leaf_t *nl, boolean_t sort);
   extern void zap_leaf_stats(struct zap *zap, zap_leaf_t *l,
       struct zap_stats *zs);
   
   #ifdef  __cplusplus
   }
   #endif
   
   #endif /* _SYS_ZAP_LEAF_H */

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