FreeBSD/Linux Kernel Cross Reference
sys/sys/blist.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1998 Matthew Dillon.  All Rights Reserved.
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
     * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
     * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
     * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    /*
     * Implements bitmap resource lists.
     *
     *      Usage:
     *              blist = blist_create(blocks, flags)
     *              (void)  blist_destroy(blist)
     *              blkno = blist_alloc(blist, &count, maxcount)
     *              (void)  blist_free(blist, blkno, count)
     *              nblks = blist_fill(blist, blkno, count)
     *              (void)  blist_resize(&blist, count, freeextra, flags)
     *              
     *
     *      Notes:
     *              on creation, the entire list is marked reserved.  You should
     *              first blist_free() the sections you want to make available
     *              for allocation before doing general blist_alloc()/free()
     *              ops.
     *
     *              SWAPBLK_NONE is returned on failure.  This module is typically
     *              capable of managing up to (2^63) blocks per blist, though
     *              the memory utilization would be insane if you actually did
     *              that.  Managing something like 512MB worth of 4K blocks 
     *              eats around 32 KBytes of memory. 
     *
     * $FreeBSD$
    
     */
    
    #ifndef _SYS_BLIST_H_
    #define _SYS_BLIST_H_
    
    typedef uint64_t        u_daddr_t;      /* unsigned disk address */
    
    /*
     * note: currently use SWAPBLK_NONE as an absolute value rather then 
     * a flag bit.
     */
    
    #define SWAPBLK_MASK    ((daddr_t)((u_daddr_t)-1 >> 1))         /* mask */
    #define SWAPBLK_NONE    ((daddr_t)((u_daddr_t)SWAPBLK_MASK + 1))/* flag */
    
    /*
     * Both blmeta and bm_bitmap MUST be a power of 2 in size.
     */
    
    typedef struct blmeta {
            u_daddr_t       bm_bitmap;      /* marking unfilled block sets  */
            daddr_t         bm_bighint;     /* biggest contiguous block hint*/
    } blmeta_t;
    
    typedef struct blist {
            daddr_t         bl_blocks;      /* area of coverage             */
            daddr_t         bl_avail;       /* # available blocks           */
            u_daddr_t       bl_radix;       /* coverage radix               */
            daddr_t         bl_cursor;      /* next-fit search starts at    */
            blmeta_t        bl_root[1];     /* root of radix tree           */
    } *blist_t;
    
    #define BLIST_RADIX             (sizeof(u_daddr_t) * 8)
    
    #define BLIST_MAX_ALLOC         BLIST_RADIX
    
    struct sbuf;
    
    daddr_t blist_alloc(blist_t blist, int *count, int maxcount);
    daddr_t blist_avail(blist_t blist);
    blist_t blist_create(daddr_t blocks, int flags);
    void    blist_destroy(blist_t blist);
    daddr_t blist_fill(blist_t bl, daddr_t blkno, daddr_t count);
    void    blist_free(blist_t blist, daddr_t blkno, daddr_t count);
   void    blist_print(blist_t blist);
   void    blist_resize(blist_t *pblist, daddr_t count, int freenew, int flags);
   void    blist_stats(blist_t blist, struct sbuf *s);
   
   #endif  /* _SYS_BLIST_H_ */

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