lib/ext2fs/res_gdt.c

   1 /*
   2  * res_gdt.c --- reserve blocks for growing the group descriptor table
   3  *               during online resizing.
   4  *
   5  * Copyright (C) 2002 Andreas Dilger
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Library
   9  * General Public License, version 2.
  10  * %End-Header%
  11  */
  12
  13 #include "config.h"
  14 #include <stdio.h>
  15 #include <string.h>
  16 #include <time.h>
  17 #include "ext2_fs.h"
  18 #include "ext2fs.h"
  19
  20 /*
  21  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
  22  * ext3 filesystem.  The counters should be initialized to 1, 5, and 7 before
  23  * calling this for the first time.  In a sparse filesystem it will be the
  24  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
  25  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
  26  */
  27 static unsigned int list_backups(ext2_filsys fs, unsigned int *three,
  28                                  unsigned int *five, unsigned int *seven)
  29 {
  30         unsigned int *min = three;
  31         int mult = 3;
  32         unsigned int ret;
  33
  34         if (fs->super->s_feature_compat & EXT4_FEATURE_COMPAT_SPARSE_SUPER2) {
  35                 if (*min == 1) {
  36                         *min += 1;
  37                         if (fs->super->s_backup_bgs[0])
  38                                 return fs->super->s_backup_bgs[0];
  39                 }
  40                 if (*min == 2) {
  41                         *min += 1;
  42                         if (fs->super->s_backup_bgs[1])
  43                                 return fs->super->s_backup_bgs[1];
  44                 }
  45                 return fs->group_desc_count;
  46         }
  47         if (!(fs->super->s_feature_ro_compat &
  48               EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
  49                 ret = *min;
  50                 *min += 1;
  51                 return ret;
  52         }
  53
  54         if (*five < *min) {
  55                 min = five;
  56                 mult = 5;
  57         }
  58         if (*seven < *min) {
  59                 min = seven;
  60                 mult = 7;
  61         }
  62
  63         ret = *min;
  64         *min *= mult;
  65
  66         return ret;
  67 }
  68
  69 /*
  70  * This code assumes that the reserved blocks have already been marked in-use
  71  * during ext2fs_initialize(), so that they are not allocated for other
  72  * uses before we can add them to the resize inode (which has to come
  73  * after the creation of the inode table).
  74  */
  75 errcode_t ext2fs_create_resize_inode(ext2_filsys fs)
  76 {
  77         errcode_t               retval, retval2;
  78         struct ext2_super_block *sb;
  79         struct ext2_inode       inode;
  80         __u32                   *dindir_buf, *gdt_buf;
  81         unsigned long long      apb, inode_size;
  82         /* FIXME-64 - can't deal with extents */
  83         blk_t                   dindir_blk, rsv_off, gdt_off, gdt_blk;
  84         int                     dindir_dirty = 0, inode_dirty = 0, sb_blk = 0;
  85
  86         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  87
  88         sb = fs->super;
  89
  90         retval = ext2fs_get_array(2, fs->blocksize, &dindir_buf);
  91         if (retval)
  92                 return retval;
  93         gdt_buf = (__u32 *)((char *)dindir_buf + fs->blocksize);
  94
  95         retval = ext2fs_read_inode(fs, EXT2_RESIZE_INO, &inode);
  96         if (retval)
  97                 goto out_free;
  98
  99         /*
 100          * File systems with a blocksize of 1024 and bigalloc have
 101          * sb->s_first_data_block of 0; yet the superblock is still at
 102          * block #1.  We compensate for it here.
 103          */
 104         sb_blk = sb->s_first_data_block;
 105         if (fs->blocksize == 1024 && sb_blk == 0)
 106                 sb_blk = 1;
 107
 108         /* Maximum possible file size (we donly use the dindirect blocks) */
 109         apb = EXT2_ADDR_PER_BLOCK(sb);
 110         if ((dindir_blk = inode.i_block[EXT2_DIND_BLOCK])) {
 111 #ifdef RES_GDT_DEBUG
 112                 printf("reading GDT dindir %u\n", dindir_blk);
 113 #endif
 114                 retval = ext2fs_read_ind_block(fs, dindir_blk, dindir_buf);
 115                 if (retval)
 116                         goto out_inode;
 117         } else {
 118                 blk_t goal = sb_blk + fs->desc_blocks +
 119                         sb->s_reserved_gdt_blocks + 2 +
 120                         fs->inode_blocks_per_group;
 121
 122                 retval = ext2fs_alloc_block(fs, goal, 0, &dindir_blk);
 123                 if (retval)
 124                         goto out_free;
 125                 inode.i_mode = LINUX_S_IFREG | 0600;
 126                 inode.i_links_count = 1;
 127                 inode.i_block[EXT2_DIND_BLOCK] = dindir_blk;
 128                 ext2fs_iblk_set(fs, &inode, 1);
 129                 memset(dindir_buf, 0, fs->blocksize);
 130 #ifdef RES_GDT_DEBUG
 131                 printf("allocated GDT dindir %u\n", dindir_blk);
 132 #endif
 133                 dindir_dirty = inode_dirty = 1;
 134                 inode_size = apb*apb + apb + EXT2_NDIR_BLOCKS;
 135                 inode_size *= fs->blocksize;
 136                 retval = ext2fs_inode_size_set(fs, &inode, inode_size);
 137                 if (retval)
 138                         goto out_free;
 139                 inode.i_ctime = fs->now ? fs->now : time(0);
 140         }
 141
 142         for (rsv_off = 0, gdt_off = fs->desc_blocks,
 143              gdt_blk = sb_blk + 1 + fs->desc_blocks;
 144              rsv_off < sb->s_reserved_gdt_blocks;
 145              rsv_off++, gdt_off++, gdt_blk++) {
 146                 unsigned int three = 1, five = 5, seven = 7;
 147                 unsigned int grp, last = 0;
 148                 int gdt_dirty = 0;
 149
 150                 gdt_off %= apb;
 151                 if (!dindir_buf[gdt_off]) {
 152                         /* FIXME XXX XXX
 153                         blk_t new_blk;
 154
 155                         retval = ext2fs_new_block(fs, gdt_blk, 0, &new_blk);
 156                         if (retval)
 157                                 goto out_free;
 158                         if (new_blk != gdt_blk) {
 159                                 // XXX free block
 160                                 retval = -1; // XXX
 161                         }
 162                         */
 163                         gdt_dirty = dindir_dirty = inode_dirty = 1;
 164                         memset(gdt_buf, 0, fs->blocksize);
 165                         dindir_buf[gdt_off] = gdt_blk;
 166                         ext2fs_iblk_add_blocks(fs, &inode, 1);
 167 #ifdef RES_GDT_DEBUG
 168                         printf("added primary GDT block %u at %u[%u]\n",
 169                                gdt_blk, dindir_blk, gdt_off);
 170 #endif
 171                 } else if (dindir_buf[gdt_off] == gdt_blk) {
 172 #ifdef RES_GDT_DEBUG
 173                         printf("reading primary GDT block %u\n", gdt_blk);
 174 #endif
 175                         retval = ext2fs_read_ind_block(fs, gdt_blk, gdt_buf);
 176                         if (retval)
 177                                 goto out_dindir;
 178                 } else {
 179 #ifdef RES_GDT_DEBUG
 180                         printf("bad primary GDT %u != %u at %u[%u]\n",
 181                                dindir_buf[gdt_off], gdt_blk,dindir_blk,gdt_off);
 182 #endif
 183                         retval = EXT2_ET_RESIZE_INODE_CORRUPT;
 184                         goto out_dindir;
 185                 }
 186
 187                 while ((grp = list_backups(fs, &three, &five, &seven)) <
 188                        fs->group_desc_count) {
 189                         blk_t expect = gdt_blk + grp * sb->s_blocks_per_group;
 190
 191                         if (!gdt_buf[last]) {
 192 #ifdef RES_GDT_DEBUG
 193                                 printf("added backup GDT %u grp %u@%u[%u]\n",
 194                                        expect, grp, gdt_blk, last);
 195 #endif
 196                                 gdt_buf[last] = expect;
 197                                 ext2fs_iblk_add_blocks(fs, &inode, 1);
 198                                 gdt_dirty = inode_dirty = 1;
 199                         } else if (gdt_buf[last] != expect) {
 200 #ifdef RES_GDT_DEBUG
 201                                 printf("bad backup GDT %u != %u at %u[%u]\n",
 202                                        gdt_buf[last], expect, gdt_blk, last);
 203 #endif
 204                                 retval = EXT2_ET_RESIZE_INODE_CORRUPT;
 205                                 goto out_dindir;
 206                         }
 207                         last++;
 208                 }
 209                 if (gdt_dirty) {
 210 #ifdef RES_GDT_DEBUG
 211                         printf("writing primary GDT block %u\n", gdt_blk);
 212 #endif
 213                         retval = ext2fs_write_ind_block(fs, gdt_blk, gdt_buf);
 214                         if (retval)
 215                                 goto out_dindir;
 216                 }
 217         }
 218
 219 out_dindir:
 220         if (dindir_dirty) {
 221                 retval2 = ext2fs_write_ind_block(fs, dindir_blk, dindir_buf);
 222                 if (!retval)
 223                         retval = retval2;
 224         }
 225 out_inode:
 226 #ifdef RES_GDT_DEBUG
 227         printf("inode.i_blocks = %u, i_size = %u\n", inode.i_blocks,
 228                inode.i_size);
 229 #endif
 230         if (inode_dirty) {
 231                 inode.i_atime = inode.i_mtime = fs->now ? fs->now : time(0);
 232                 retval2 = ext2fs_write_new_inode(fs, EXT2_RESIZE_INO, &inode);
 233                 if (!retval)
 234                         retval = retval2;
 235         }
 236 out_free:
 237         ext2fs_free_mem(&dindir_buf);
 238         return retval;
 239 }
 240