The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/fs/ext2fs/ext2_extents.c

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    1 /*-
    2  * Copyright (c) 2010 Zheng Liu <lz@freebsd.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * $FreeBSD: releng/10.4/sys/fs/ext2fs/ext2_extents.c 317532 2017-04-27 23:14:01Z pfg $
   27  */
   28 
   29 #include <sys/param.h>
   30 #include <sys/systm.h>
   31 #include <sys/types.h>
   32 #include <sys/kernel.h>
   33 #include <sys/malloc.h>
   34 #include <sys/vnode.h>
   35 #include <sys/bio.h>
   36 #include <sys/buf.h>
   37 #include <sys/conf.h>
   38 
   39 #include <fs/ext2fs/ext2_mount.h>
   40 #include <fs/ext2fs/fs.h>
   41 #include <fs/ext2fs/inode.h>
   42 #include <fs/ext2fs/ext2fs.h>
   43 #include <fs/ext2fs/ext2_extents.h>
   44 #include <fs/ext2fs/ext2_extern.h>
   45 
   46 static void ext4_ext_binsearch_index(struct inode *ip, struct ext4_extent_path
   47                 *path, daddr_t lbn)
   48 {
   49         struct ext4_extent_header *ehp = path->ep_header;
   50         struct ext4_extent_index *l, *r, *m;
   51 
   52         l = (struct ext4_extent_index *)(char *)(ehp + 1);
   53         r = (struct ext4_extent_index *)(char *)(ehp + 1) + ehp->eh_ecount - 1;
   54         while (l <= r) {
   55                 m = l + (r - l) / 2;
   56                 if (lbn < m->ei_blk)
   57                         r = m - 1;
   58                 else
   59                         l = m + 1;
   60         }
   61 
   62         path->ep_index = l - 1;
   63 }
   64 
   65 static void
   66 ext4_ext_binsearch(struct inode *ip, struct ext4_extent_path *path, daddr_t lbn)
   67 {
   68         struct ext4_extent_header *ehp = path->ep_header;
   69         struct ext4_extent *l, *r, *m;
   70 
   71         if (ehp->eh_ecount == 0)
   72                 return;
   73 
   74         l = (struct ext4_extent *)(char *)(ehp + 1);
   75         r = (struct ext4_extent *)(char *)(ehp + 1) + ehp->eh_ecount - 1;
   76         while (l <= r) {
   77                 m = l + (r - l) / 2;
   78                 if (lbn < m->e_blk)
   79                         r = m - 1;
   80                 else
   81                         l = m + 1;
   82         }
   83 
   84         path->ep_ext = l - 1;
   85 }
   86 
   87 /*
   88  * Find a block in ext4 extent cache.
   89  */
   90 int
   91 ext4_ext_in_cache(struct inode *ip, daddr_t lbn, struct ext4_extent *ep)
   92 {
   93         struct ext4_extent_cache *ecp;
   94         int ret = EXT4_EXT_CACHE_NO;
   95 
   96         ecp = &ip->i_ext_cache;
   97 
   98         /* cache is invalid */
   99         if (ecp->ec_type == EXT4_EXT_CACHE_NO)
  100                 return (ret);
  101 
  102         if (lbn >= ecp->ec_blk && lbn < ecp->ec_blk + ecp->ec_len) {
  103                 ep->e_blk = ecp->ec_blk;
  104                 ep->e_start_lo = ecp->ec_start & 0xffffffff;
  105                 ep->e_start_hi = ecp->ec_start >> 32 & 0xffff;
  106                 ep->e_len = ecp->ec_len;
  107                 ret = ecp->ec_type;
  108         }
  109         return (ret);
  110 }
  111 
  112 /*
  113  * Put an ext4_extent structure in ext4 cache.
  114  */
  115 void
  116 ext4_ext_put_cache(struct inode *ip, struct ext4_extent *ep, int type)
  117 {
  118         struct ext4_extent_cache *ecp;
  119 
  120         ecp = &ip->i_ext_cache;
  121         ecp->ec_type = type;
  122         ecp->ec_blk = ep->e_blk;
  123         ecp->ec_len = ep->e_len;
  124         ecp->ec_start = (daddr_t)ep->e_start_hi << 32 | ep->e_start_lo;
  125 }
  126 
  127 /*
  128  * Find an extent.
  129  */
  130 struct ext4_extent_path *
  131 ext4_ext_find_extent(struct m_ext2fs *fs, struct inode *ip,
  132     daddr_t lbn, struct ext4_extent_path *path)
  133 {
  134         struct ext4_extent_header *ehp;
  135         uint16_t i;
  136         int error, size;
  137         daddr_t nblk;
  138 
  139         ehp = (struct ext4_extent_header *)(char *)ip->i_db;
  140 
  141         if (ehp->eh_magic != EXT4_EXT_MAGIC)
  142                 return (NULL);
  143 
  144         path->ep_header = ehp;
  145 
  146         for (i = ehp->eh_depth; i != 0; --i) {
  147                 ext4_ext_binsearch_index(ip, path, lbn);
  148                 path->ep_depth = 0;
  149                 path->ep_ext = NULL;
  150 
  151                 nblk = (daddr_t)path->ep_index->ei_leaf_hi << 32 |
  152                     path->ep_index->ei_leaf_lo;
  153                 size = blksize(fs, ip, nblk);
  154                 if (path->ep_bp != NULL) {
  155                         brelse(path->ep_bp);
  156                         path->ep_bp = NULL;
  157                 }
  158                 error = bread(ip->i_devvp, fsbtodb(fs, nblk), size, NOCRED,
  159                     &path->ep_bp);
  160                 if (error) {
  161                         brelse(path->ep_bp);
  162                         path->ep_bp = NULL;
  163                         return (NULL);
  164                 }
  165                 ehp = (struct ext4_extent_header *)path->ep_bp->b_data;
  166                 path->ep_header = ehp;
  167         }
  168 
  169         path->ep_depth = i;
  170         path->ep_ext = NULL;
  171         path->ep_index = NULL;
  172 
  173         ext4_ext_binsearch(ip, path, lbn);
  174         return (path);
  175 }

Cache object: efdc779279031b6c8101cbbe907a2514


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