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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, clusters;
  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                 clusters = ocfs2_rec_clusters(el, rec);
  60
  61                 rec_end = rec_start + clusters;
  62
  63                 if (v_cluster >= rec_start && v_cluster < rec_end) {
  64                         ret = i;
  65                         break;
  66                 }
  67         }
  68
  69         return ret;
  70 }
  71
  72 int ocfs2_get_clusters(struct inode *inode, u32 v_cluster,
  73                        u32 *p_cluster, u32 *num_clusters)
  74 {
  75         int ret, i;
  76         struct buffer_head *di_bh = NULL;
  77         struct buffer_head *eb_bh = NULL;
  78         struct ocfs2_dinode *di;
  79         struct ocfs2_extent_block *eb;
  80         struct ocfs2_extent_list *el;
  81         struct ocfs2_extent_rec *rec;
  82         u32 coff;
  83
  84         ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), OCFS2_I(inode)->ip_blkno,
  85                                &di_bh, OCFS2_BH_CACHED, inode);
  86         if (ret) {
  87                 mlog_errno(ret);
  88                 goto out;
  89         }
  90
  91         di = (struct ocfs2_dinode *) di_bh->b_data;
  92         el = &di->id2.i_list;
  93
  94         if (el->l_tree_depth) {
  95                 ret = ocfs2_find_leaf(inode, el, v_cluster, &eb_bh);
  96                 if (ret) {
  97                         mlog_errno(ret);
  98                         goto out;
  99                 }
 100
 101                 eb = (struct ocfs2_extent_block *) eb_bh->b_data;
 102                 el = &eb->h_list;
 103
 104                 if (el->l_tree_depth) {
 105                         ocfs2_error(inode->i_sb,
 106                                     "Inode %lu has non zero tree depth in "
 107                                     "leaf block %llu\n", inode->i_ino,
 108                                     (unsigned long long)eb_bh->b_blocknr);
 109                         ret = -EROFS;
 110                         goto out;
 111                 }
 112         }
 113
 114         i = ocfs2_search_extent_list(el, v_cluster);
 115         if (i == -1) {
 116                 /*
 117                  * A hole was found. Return some canned values that
 118                  * callers can key on.
 119                  */
 120                 *p_cluster = 0;
 121                 if (num_clusters)
 122                         *num_clusters = 1;
 123         } else {
 124                 rec = &el->l_recs[i];
 125
 126                 BUG_ON(v_cluster < le32_to_cpu(rec->e_cpos));
 127
 128                 if (!rec->e_blkno) {
 129                         ocfs2_error(inode->i_sb, "Inode %lu has bad extent "
 130                                     "record (%u, %u, 0)", inode->i_ino,
 131                                     le32_to_cpu(rec->e_cpos),
 132                                     ocfs2_rec_clusters(el, rec));
 133                         ret = -EROFS;
 134                         goto out;
 135                 }
 136
 137                 coff = v_cluster - le32_to_cpu(rec->e_cpos);
 138
 139                 *p_cluster = ocfs2_blocks_to_clusters(inode->i_sb,
 140                                                     le64_to_cpu(rec->e_blkno));
 141                 *p_cluster = *p_cluster + coff;
 142
 143                 if (num_clusters)
 144                         *num_clusters = ocfs2_rec_clusters(el, rec) - coff;
 145         }
 146
 147 out:
 148         brelse(di_bh);
 149         brelse(eb_bh);
 150         return ret;
 151 }
 152
 153 /*
 154  * This expects alloc_sem to be held. The allocation cannot change at
 155  * all while the map is in the process of being updated.
 156  */
 157 int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno,
 158                                 int *ret_count)
 159 {
 160         int ret;
 161         int bpc = ocfs2_clusters_to_blocks(inode->i_sb, 1);
 162         u32 cpos, num_clusters, p_cluster;
 163         u64 boff = 0;
 164
 165         cpos = ocfs2_blocks_to_clusters(inode->i_sb, v_blkno);
 166
 167         ret = ocfs2_get_clusters(inode, cpos, &p_cluster, &num_clusters);
 168         if (ret) {
 169                 mlog_errno(ret);
 170                 goto out;
 171         }
 172
 173         /*
 174          * p_cluster == 0 indicates a hole.
 175          */
 176         if (p_cluster) {
 177                 boff = ocfs2_clusters_to_blocks(inode->i_sb, p_cluster);
 178                 boff += (v_blkno & (u64)(bpc - 1));
 179         }
 180
 181         *p_blkno = boff;
 182
 183         if (ret_count) {
 184                 *ret_count = ocfs2_clusters_to_blocks(inode->i_sb, num_clusters);
 185                 *ret_count -= v_blkno & (u64)(bpc - 1);
 186         }
 187
 188 out:
 189         return ret;
 190 }