fs/zfs/dev.c

   1 /*
   2  *
   3  *      based on code of fs/reiserfs/dev.c by
   4  *
   5  *      (C) Copyright 2003 - 2004
   6  *      Sysgo AG, <www.elinos.com>, Pavel Bartusek <pba@sysgo.com>
   7  *
   8  *      This program is free software; you can redistribute it and/or modify
   9  *      it under the terms of the GNU General Public License as published by
  10  *      the Free Software Foundation; either version 2 of the License, or
  11  *      (at your option) any later version.
  12  *
  13  *      This program is distributed in the hope that it will be useful,
  14  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *      GNU General Public License for more details.
  17  *
  18  *      You should have received a copy of the GNU General Public License
  19  *      along with this program; if not, write to the Free Software
  20  *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21  */
  22
  23
  24 #include <common.h>
  25 #include <config.h>
  26 #include <zfs_common.h>
  27
  28 static block_dev_desc_t *zfs_block_dev_desc;
  29 static disk_partition_t *part_info;
  30
  31 void zfs_set_blk_dev(block_dev_desc_t *rbdd, disk_partition_t *info)
  32 {
  33         zfs_block_dev_desc = rbdd;
  34         part_info = info;
  35 }
  36
  37 /* err */
  38 int zfs_devread(int sector, int byte_offset, int byte_len, char *buf)
  39 {
  40         short sec_buffer[SECTOR_SIZE/sizeof(short)];
  41         char *sec_buf = (char *)sec_buffer;
  42         unsigned block_len;
  43
  44         /*
  45          *      Check partition boundaries
  46          */
  47         if ((sector < 0) ||
  48                 ((sector + ((byte_offset + byte_len - 1) >> SECTOR_BITS)) >=
  49                  part_info->size)) {
  50                 /*              errnum = ERR_OUTSIDE_PART; */
  51                 printf(" ** zfs_devread() read outside partition sector %d\n", sector);
  52                 return 1;
  53         }
  54
  55         /*
  56          *      Get the read to the beginning of a partition.
  57          */
  58         sector += byte_offset >> SECTOR_BITS;
  59         byte_offset &= SECTOR_SIZE - 1;
  60
  61         debug(" <%d, %d, %d>\n", sector, byte_offset, byte_len);
  62
  63         if (zfs_block_dev_desc == NULL) {
  64                 printf("** Invalid Block Device Descriptor (NULL)\n");
  65                 return 1;
  66         }
  67
  68         if (byte_offset != 0) {
  69                 /* read first part which isn't aligned with start of sector */
  70                 if (zfs_block_dev_desc->block_read(zfs_block_dev_desc->dev,
  71                         part_info->start + sector, 1,
  72                         (unsigned long *)sec_buf) != 1) {
  73                         printf(" ** zfs_devread() read error **\n");
  74                         return 1;
  75                 }
  76                 memcpy(buf, sec_buf + byte_offset,
  77                            min(SECTOR_SIZE - byte_offset, byte_len));
  78                 buf += min(SECTOR_SIZE - byte_offset, byte_len);
  79                 byte_len -= min(SECTOR_SIZE - byte_offset, byte_len);
  80                 sector++;
  81         }
  82
  83         if (byte_len == 0)
  84                 return 0;
  85
  86         /*      read sector aligned part */
  87         block_len = byte_len & ~(SECTOR_SIZE - 1);
  88
  89         if (block_len == 0) {
  90                 u8 p[SECTOR_SIZE];
  91
  92                 block_len = SECTOR_SIZE;
  93                 zfs_block_dev_desc->block_read(zfs_block_dev_desc->dev,
  94                         part_info->start + sector,
  95                         1, (unsigned long *)p);
  96                 memcpy(buf, p, byte_len);
  97                 return 0;
  98         }
  99
 100         if (zfs_block_dev_desc->block_read(zfs_block_dev_desc->dev,
 101                 part_info->start + sector, block_len / SECTOR_SIZE,
 102                 (unsigned long *) buf) != block_len / SECTOR_SIZE) {
 103                 printf(" ** zfs_devread() read error - block\n");
 104                 return 1;
 105         }
 106
 107         block_len = byte_len & ~(SECTOR_SIZE - 1);
 108         buf += block_len;
 109         byte_len -= block_len;
 110         sector += block_len / SECTOR_SIZE;
 111
 112         if (byte_len != 0) {
 113                 /* read rest of data which are not in whole sector */
 114                 if (zfs_block_dev_desc->
 115                         block_read(zfs_block_dev_desc->dev,
 116                                            part_info->start + sector, 1,
 117                                            (unsigned long *) sec_buf) != 1) {
 118                         printf(" ** zfs_devread() read error - last part\n");
 119                         return 1;
 120                 }
 121                 memcpy(buf, sec_buf, byte_len);
 122         }
 123         return 0;
 124 }