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   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * extent_map.c
   5  *
   6  * Block/Cluster mapping functions
   7  *
   8  * Copyright (C) 2004 Oracle.  All rights reserved.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public
  12  * License, version 2,  as published by the Free Software Foundation.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public
  20  * License along with this program; if not, write to the
  21  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  22  * Boston, MA 021110-1307, USA.
  23  */
  24
  25 #include <linux/fs.h>
  26 #include <linux/init.h>
  27 #include <linux/types.h>
  28
  29 #define MLOG_MASK_PREFIX ML_EXTENT_MAP
  30 #include <cluster/masklog.h>
  31
  32 #include "ocfs2.h"
  33
  34 #include "alloc.h"
  35 #include "extent_map.h"
  36 #include "inode.h"
  37 #include "super.h"
  38
  39 #include "buffer_head_io.h"
  40
  41 /*
  42  * Return the index of the extent record which contains cluster #v_cluster.
  43  * -1 is returned if it was not found.
  44  *
  45  * Should work fine on interior and exterior nodes.
  46  */
  47 static int ocfs2_search_extent_list(struct ocfs2_extent_list *el,
  48                                     u32 v_cluster)
  49 {
  50         int ret = -1;
  51         int i;
  52         struct ocfs2_extent_rec *rec;
  53         u32 rec_end, rec_start;
  54
  55         for(i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
  56                 rec = &el->l_recs[i];
  57
  58                 rec_start = le32_to_cpu(rec->e_cpos);
  59                 rec_end = rec_start + le32_to_cpu(rec->e_clusters);
  60
  61                 if (v_cluster >= rec_start && v_cluster < rec_end) {
  62                         ret = i;
  63                         break;
  64                 }
  65         }
  66
  67         return ret;
  68 }
  69
  70 static int ocfs2_get_clusters(struct inode *inode, u32 v_cluster,
  71                               u32 *p_cluster, u32 *num_clusters)
  72 {
  73         int ret, i;
  74         struct buffer_head *di_bh = NULL;
  75         struct buffer_head *eb_bh = NULL;
  76         struct ocfs2_dinode *di;
  77         struct ocfs2_extent_block *eb;
  78         struct ocfs2_extent_list *el;
  79         struct ocfs2_extent_rec *rec;
  80         u32 coff;
  81
  82         ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), OCFS2_I(inode)->ip_blkno,
  83                                &di_bh, OCFS2_BH_CACHED, inode);
  84         if (ret) {
  85                 mlog_errno(ret);
  86                 goto out;
  87         }
  88
  89         di = (struct ocfs2_dinode *) di_bh->b_data;
  90         el = &di->id2.i_list;
  91
  92         if (el->l_tree_depth) {
  93                 ret = ocfs2_find_leaf(inode, el, v_cluster, &eb_bh);
  94                 if (ret) {
  95                         mlog_errno(ret);
  96                         goto out;
  97                 }
  98
  99                 eb = (struct ocfs2_extent_block *) eb_bh->b_data;
 100                 el = &eb->h_list;
 101         }
 102
 103         i = ocfs2_search_extent_list(el, v_cluster);
 104         if (i == -1) {
 105                 /*
 106                  * A hole was found. Return some canned values that
 107                  * callers can key on.
 108                  */
 109                 *p_cluster = 0;
 110                 if (num_clusters)
 111                         *num_clusters = 1;
 112         } else {
 113                 rec = &el->l_recs[i];
 114
 115                 BUG_ON(v_cluster < le32_to_cpu(rec->e_cpos));
 116
 117                 if (!rec->e_blkno) {
 118                         ocfs2_error(inode->i_sb, "Inode %lu has bad extent "
 119                                     "record (%u, %u, 0)", inode->i_ino,
 120                                     le32_to_cpu(rec->e_cpos),
 121                                     le32_to_cpu(rec->e_clusters));
 122                         ret = -EROFS;
 123                         goto out;
 124                 }
 125
 126                 coff = v_cluster - le32_to_cpu(rec->e_cpos);
 127
 128                 *p_cluster = ocfs2_blocks_to_clusters(inode->i_sb,
 129                                                     le64_to_cpu(rec->e_blkno));
 130                 *p_cluster = *p_cluster + coff;
 131
 132                 if (num_clusters)
 133                         *num_clusters = le32_to_cpu(rec->e_clusters) - coff;
 134         }
 135
 136 out:
 137         brelse(di_bh);
 138         brelse(eb_bh);
 139         return ret;
 140 }
 141
 142 /*
 143  * This expects alloc_sem to be held. The allocation cannot change at
 144  * all while the map is in the process of being updated.
 145  */
 146 int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno,
 147                                 int *ret_count)
 148 {
 149         int ret;
 150         int bpc = ocfs2_clusters_to_blocks(inode->i_sb, 1);
 151         u32 cpos, num_clusters, p_cluster;
 152         u64 boff = 0;
 153
 154         cpos = ocfs2_blocks_to_clusters(inode->i_sb, v_blkno);
 155
 156         ret = ocfs2_get_clusters(inode, cpos, &p_cluster, &num_clusters);
 157         if (ret) {
 158                 mlog_errno(ret);
 159                 goto out;
 160         }
 161
 162         /*
 163          * p_cluster == 0 indicates a hole.
 164          */
 165         if (p_cluster) {
 166                 boff = ocfs2_clusters_to_blocks(inode->i_sb, p_cluster);
 167                 boff += (v_blkno & (u64)(bpc - 1));
 168         }
 169
 170         *p_blkno = boff;
 171
 172         if (ret_count) {
 173                 *ret_count = ocfs2_clusters_to_blocks(inode->i_sb, num_clusters);
 174                 *ret_count -= v_blkno & (u64)(bpc - 1);
 175         }
 176
 177 out:
 178         return ret;
 179 }