FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/include/sys/space_map.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 2009 Sun Microsystems, Inc.  All rights reserved.
     * Use is subject to license terms.
     */
    
    /*
     * Copyright (c) 2012, 2019 by Delphix. All rights reserved.
     */
    
    #ifndef _SYS_SPACE_MAP_H
    #define _SYS_SPACE_MAP_H
    
    #include <sys/avl.h>
    #include <sys/range_tree.h>
    #include <sys/dmu.h>
    
    #ifdef  __cplusplus
    extern "C" {
    #endif
    
    /*
     * The size of the space map object has increased to include a histogram.
     * The SPACE_MAP_SIZE_V0 designates the original size and is used to
     * maintain backward compatibility.
     */
    #define SPACE_MAP_SIZE_V0       (3 * sizeof (uint64_t))
    #define SPACE_MAP_HISTOGRAM_SIZE        32
    
    /*
     * The space_map_phys is the on-disk representation of the space map.
     * Consumers of space maps should never reference any of the members of this
     * structure directly. These members may only be updated in syncing context.
     *
     * Note the smp_object is no longer used but remains in the structure
     * for backward compatibility.
     */
    typedef struct space_map_phys {
            /* object number: not needed but kept for backwards compatibility */
            uint64_t        smp_object;
    
            /* length of the object in bytes */
            uint64_t        smp_length;
    
            /* space allocated from the map */
            int64_t         smp_alloc;
    
            /* reserved */
            uint64_t        smp_pad[5];
    
            /*
             * The smp_histogram maintains a histogram of free regions. Each
             * bucket, smp_histogram[i], contains the number of free regions
             * whose size is:
             * 2^(i+sm_shift) <= size of free region in bytes < 2^(i+sm_shift+1)
             *
             * Note that, if log space map feature is enabled, histograms of
             * space maps that belong to metaslabs will take into account any
             * unflushed changes for their metaslabs, even though the actual
             * space map doesn't have entries for these changes.
             */
            uint64_t        smp_histogram[SPACE_MAP_HISTOGRAM_SIZE];
    } space_map_phys_t;
    
    /*
     * The space map object defines a region of space, its size, how much is
     * allocated, and the on-disk object that stores this information.
     * Consumers of space maps may only access the members of this structure.
     *
     * Note: the space_map may not be accessed concurrently; consumers
     * must provide external locking if required.
     */
    typedef struct space_map {
            uint64_t        sm_start;       /* start of map */
            uint64_t        sm_size;        /* size of map */
            uint8_t         sm_shift;       /* unit shift */
            objset_t        *sm_os;         /* objset for this map */
            uint64_t        sm_object;      /* object id for this map */
            uint32_t        sm_blksz;       /* block size for space map */
            dmu_buf_t       *sm_dbuf;       /* space_map_phys_t dbuf */
           space_map_phys_t *sm_phys;      /* on-disk space map */
   } space_map_t;
   
   /*
    * debug entry
    *
    *     2     2        10                     50
    *  +-----+-----+------------+----------------------------------+
    *  | 1 0 | act |  syncpass  |        txg (lower bits)          |
    *  +-----+-----+------------+----------------------------------+
    *   63 62 61 60 59        50 49                                0
    *
    *
    * one-word entry
    *
    *    1               47                   1           15
    *  +-----------------------------------------------------------+
    *  | 0 |   offset (sm_shift units)    | type |       run       |
    *  +-----------------------------------------------------------+
    *   63  62                          16   15   14               0
    *
    *
    * two-word entry
    *
    *     2     2               36                      24
    *  +-----+-----+---------------------------+-------------------+
    *  | 1 1 | pad |            run            |       vdev        |
    *  +-----+-----+---------------------------+-------------------+
    *   63 62 61 60 59                       24 23                 0
    *
    *     1                            63
    *  +------+----------------------------------------------------+
    *  | type |                      offset                        |
    *  +------+----------------------------------------------------+
    *     63   62                                                  0
    *
    * Note that a two-word entry will not straddle a block boundary.
    * If necessary, the last word of a block will be padded with a
    * debug entry (with act = syncpass = txg = 0).
    */
   
   typedef enum {
           SM_ALLOC,
           SM_FREE
   } maptype_t;
   
   typedef struct space_map_entry {
           maptype_t sme_type;
           uint32_t sme_vdev;      /* max is 2^24-1; SM_NO_VDEVID if not present */
           uint64_t sme_offset;    /* max is 2^63-1; units of sm_shift */
           uint64_t sme_run;       /* max is 2^36; units of sm_shift */
   
           /*
            * The following fields are not part of the actual space map entry
            * on-disk and they are populated with the values from the debug
            * entry most recently visited starting from the beginning to the
            * end of the space map.
            */
           uint64_t sme_txg;
           uint64_t sme_sync_pass;
   } space_map_entry_t;
   
   #define SM_NO_VDEVID    (1 << SPA_VDEVBITS)
   
   /* one-word entry constants */
   #define SM_DEBUG_PREFIX 2
   #define SM_OFFSET_BITS  47
   #define SM_RUN_BITS     15
   
   /* two-word entry constants */
   #define SM2_PREFIX      3
   #define SM2_OFFSET_BITS 63
   #define SM2_RUN_BITS    36
   
   #define SM_PREFIX_DECODE(x)     BF64_DECODE(x, 62, 2)
   #define SM_PREFIX_ENCODE(x)     BF64_ENCODE(x, 62, 2)
   
   #define SM_DEBUG_ACTION_DECODE(x)       BF64_DECODE(x, 60, 2)
   #define SM_DEBUG_ACTION_ENCODE(x)       BF64_ENCODE(x, 60, 2)
   #define SM_DEBUG_SYNCPASS_DECODE(x)     BF64_DECODE(x, 50, 10)
   #define SM_DEBUG_SYNCPASS_ENCODE(x)     BF64_ENCODE(x, 50, 10)
   #define SM_DEBUG_TXG_DECODE(x)          BF64_DECODE(x, 0, 50)
   #define SM_DEBUG_TXG_ENCODE(x)          BF64_ENCODE(x, 0, 50)
   
   #define SM_OFFSET_DECODE(x)     BF64_DECODE(x, 16, SM_OFFSET_BITS)
   #define SM_OFFSET_ENCODE(x)     BF64_ENCODE(x, 16, SM_OFFSET_BITS)
   #define SM_TYPE_DECODE(x)       BF64_DECODE(x, 15, 1)
   #define SM_TYPE_ENCODE(x)       BF64_ENCODE(x, 15, 1)
   #define SM_RUN_DECODE(x)        (BF64_DECODE(x, 0, SM_RUN_BITS) + 1)
   #define SM_RUN_ENCODE(x)        BF64_ENCODE((x) - 1, 0, SM_RUN_BITS)
   #define SM_RUN_MAX              SM_RUN_DECODE(~0ULL)
   #define SM_OFFSET_MAX           SM_OFFSET_DECODE(~0ULL)
   
   #define SM2_RUN_DECODE(x)       (BF64_DECODE(x, SPA_VDEVBITS, SM2_RUN_BITS) + 1)
   #define SM2_RUN_ENCODE(x)       BF64_ENCODE((x) - 1, SPA_VDEVBITS, SM2_RUN_BITS)
   #define SM2_VDEV_DECODE(x)      BF64_DECODE(x, 0, SPA_VDEVBITS)
   #define SM2_VDEV_ENCODE(x)      BF64_ENCODE(x, 0, SPA_VDEVBITS)
   #define SM2_TYPE_DECODE(x)      BF64_DECODE(x, SM2_OFFSET_BITS, 1)
   #define SM2_TYPE_ENCODE(x)      BF64_ENCODE(x, SM2_OFFSET_BITS, 1)
   #define SM2_OFFSET_DECODE(x)    BF64_DECODE(x, 0, SM2_OFFSET_BITS)
   #define SM2_OFFSET_ENCODE(x)    BF64_ENCODE(x, 0, SM2_OFFSET_BITS)
   #define SM2_RUN_MAX             SM2_RUN_DECODE(~0ULL)
   #define SM2_OFFSET_MAX          SM2_OFFSET_DECODE(~0ULL)
   
   boolean_t sm_entry_is_debug(uint64_t e);
   boolean_t sm_entry_is_single_word(uint64_t e);
   boolean_t sm_entry_is_double_word(uint64_t e);
   
   typedef int (*sm_cb_t)(space_map_entry_t *sme, void *arg);
   
   int space_map_load(space_map_t *sm, range_tree_t *rt, maptype_t maptype);
   int space_map_load_length(space_map_t *sm, range_tree_t *rt, maptype_t maptype,
       uint64_t length);
   int space_map_iterate(space_map_t *sm, uint64_t length,
       sm_cb_t callback, void *arg);
   int space_map_incremental_destroy(space_map_t *sm, sm_cb_t callback, void *arg,
       dmu_tx_t *tx);
   
   boolean_t space_map_histogram_verify(space_map_t *sm, range_tree_t *rt);
   void space_map_histogram_clear(space_map_t *sm);
   void space_map_histogram_add(space_map_t *sm, range_tree_t *rt,
       dmu_tx_t *tx);
   
   uint64_t space_map_object(space_map_t *sm);
   int64_t space_map_allocated(space_map_t *sm);
   uint64_t space_map_length(space_map_t *sm);
   uint64_t space_map_entries(space_map_t *sm, range_tree_t *rt);
   uint64_t space_map_nblocks(space_map_t *sm);
   
   void space_map_write(space_map_t *sm, range_tree_t *rt, maptype_t maptype,
       uint64_t vdev_id, dmu_tx_t *tx);
   uint64_t space_map_estimate_optimal_size(space_map_t *sm, range_tree_t *rt,
       uint64_t vdev_id);
   void space_map_truncate(space_map_t *sm, int blocksize, dmu_tx_t *tx);
   uint64_t space_map_alloc(objset_t *os, int blocksize, dmu_tx_t *tx);
   void space_map_free(space_map_t *sm, dmu_tx_t *tx);
   void space_map_free_obj(objset_t *os, uint64_t smobj, dmu_tx_t *tx);
   
   int space_map_open(space_map_t **smp, objset_t *os, uint64_t object,
       uint64_t start, uint64_t size, uint8_t shift);
   void space_map_close(space_map_t *sm);
   
   #ifdef  __cplusplus
   }
   #endif
   
   #endif  /* _SYS_SPACE_MAP_H */

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