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 (ext2fs_has_feature_sparse_super2(fs->super)) {
  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 (!ext2fs_has_feature_sparse_super(fs->super)) {
  48                 ret = *min;
  49                 *min += 1;
  50                 return ret;
  51         }
  52
  53         if (*five < *min) {
  54                 min = five;
  55                 mult = 5;
  56         }
  57         if (*seven < *min) {
  58                 min = seven;
  59                 mult = 7;
  60         }
  61
  62         ret = *min;
  63         *min *= mult;
  64
  65         return ret;
  66 }
  67
  68 /*
  69  * This code assumes that the reserved blocks have already been marked in-use
  70  * during ext2fs_initialize(), so that they are not allocated for other
  71  * uses before we can add them to the resize inode (which has to come
  72  * after the creation of the inode table).
  73  */
  74 errcode_t ext2fs_create_resize_inode(ext2_filsys fs)
  75 {
  76         errcode_t               retval, retval2;
  77         struct ext2_super_block *sb;
  78         struct ext2_inode       inode;
  79         __u32                   *dindir_buf, *gdt_buf;
  80         unsigned long long      apb, inode_size;
  81         /* FIXME-64 - can't deal with extents */
  82         blk_t                   dindir_blk, rsv_off, gdt_off, gdt_blk;
  83         int                     dindir_dirty = 0, inode_dirty = 0, sb_blk = 0;
  84
  85         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  86
  87         sb = fs->super;
  88
  89         retval = ext2fs_get_array(2, fs->blocksize, &dindir_buf);
  90         if (retval)
  91                 return retval;
  92         gdt_buf = (__u32 *)((char *)dindir_buf + fs->blocksize);
  93
  94         retval = ext2fs_read_inode(fs, EXT2_RESIZE_INO, &inode);
  95         if (retval)
  96                 goto out_free;
  97
  98         /*
  99          * File systems with a blocksize of 1024 and bigalloc have
 100          * sb->s_first_data_block of 0; yet the superblock is still at
 101          * block #1.  We compensate for it here.
 102          */
 103         sb_blk = sb->s_first_data_block;
 104         if (fs->blocksize == 1024 && sb_blk == 0)
 105                 sb_blk = 1;
 106
 107         /* Maximum possible file size (we only use double indirect blocks) */
 108         apb = EXT2_ADDR_PER_BLOCK(sb);
 109         if ((dindir_blk = inode.i_block[EXT2_DIND_BLOCK])) {
 110 #ifdef RES_GDT_DEBUG
 111                 printf("reading GDT dindir %u\n", dindir_blk);
 112 #endif
 113                 retval = ext2fs_read_ind_block(fs, dindir_blk, dindir_buf);
 114                 if (retval)
 115                         goto out_inode;
 116         } else {
 117                 blk_t goal = sb_blk + fs->desc_blocks +
 118                         sb->s_reserved_gdt_blocks + 2 +
 119                         fs->inode_blocks_per_group;
 120
 121                 retval = ext2fs_alloc_block(fs, goal, 0, &dindir_blk);
 122                 if (retval)
 123                         goto out_free;
 124                 inode.i_mode = LINUX_S_IFREG | 0600;
 125                 inode.i_links_count = 1;
 126                 inode.i_block[EXT2_DIND_BLOCK] = dindir_blk;
 127                 ext2fs_iblk_set(fs, &inode, 1);
 128                 memset(dindir_buf, 0, fs->blocksize);
 129 #ifdef RES_GDT_DEBUG
 130                 printf("allocated GDT dindir %u\n", dindir_blk);
 131 #endif
 132                 dindir_dirty = inode_dirty = 1;
 133                 inode_size = apb*apb + apb + EXT2_NDIR_BLOCKS;
 134                 inode_size *= fs->blocksize;
 135                 retval = ext2fs_inode_size_set(fs, &inode, inode_size);
 136                 if (retval)
 137                         goto out_free;
 138                 inode.i_ctime = fs->now ? fs->now : time(0);
 139         }
 140
 141         for (rsv_off = 0, gdt_off = fs->desc_blocks,
 142              gdt_blk = sb_blk + 1 + fs->desc_blocks;
 143              rsv_off < sb->s_reserved_gdt_blocks;
 144              rsv_off++, gdt_off++, gdt_blk++) {
 145                 unsigned int three = 1, five = 5, seven = 7;
 146                 unsigned int grp, last = 0;
 147                 int gdt_dirty = 0;
 148
 149                 gdt_off %= apb;
 150                 if (!dindir_buf[gdt_off]) {
 151                         /* FIXME XXX XXX
 152                         blk_t new_blk;
 153
 154                         retval = ext2fs_new_block(fs, gdt_blk, 0, &new_blk);
 155                         if (retval)
 156                                 goto out_free;
 157                         if (new_blk != gdt_blk) {
 158                                 // XXX free block
 159                                 retval = -1; // XXX
 160                         }
 161                         */
 162                         gdt_dirty = dindir_dirty = inode_dirty = 1;
 163                         memset(gdt_buf, 0, fs->blocksize);
 164                         dindir_buf[gdt_off] = gdt_blk;
 165                         ext2fs_iblk_add_blocks(fs, &inode, 1);
 166 #ifdef RES_GDT_DEBUG
 167                         printf("added primary GDT block %u at %u[%u]\n",
 168                                gdt_blk, dindir_blk, gdt_off);
 169 #endif
 170                 } else if (dindir_buf[gdt_off] == gdt_blk) {
 171 #ifdef RES_GDT_DEBUG
 172                         printf("reading primary GDT block %u\n", gdt_blk);
 173 #endif
 174                         retval = ext2fs_read_ind_block(fs, gdt_blk, gdt_buf);
 175                         if (retval)
 176                                 goto out_dindir;
 177                 } else {
 178 #ifdef RES_GDT_DEBUG
 179                         printf("bad primary GDT %u != %u at %u[%u]\n",
 180                                dindir_buf[gdt_off], gdt_blk,dindir_blk,gdt_off);
 181 #endif
 182                         retval = EXT2_ET_RESIZE_INODE_CORRUPT;
 183                         goto out_dindir;
 184                 }
 185
 186                 while ((grp = list_backups(fs, &three, &five, &seven)) <
 187                        fs->group_desc_count) {
 188                         blk_t expect = gdt_blk + grp * sb->s_blocks_per_group;
 189
 190                         if (!gdt_buf[last]) {
 191 #ifdef RES_GDT_DEBUG
 192                                 printf("added backup GDT %u grp %u@%u[%u]\n",
 193                                        expect, grp, gdt_blk, last);
 194 #endif
 195                                 gdt_buf[last] = expect;
 196                                 ext2fs_iblk_add_blocks(fs, &inode, 1);
 197                                 gdt_dirty = inode_dirty = 1;
 198                         } else if (gdt_buf[last] != expect) {
 199 #ifdef RES_GDT_DEBUG
 200                                 printf("bad backup GDT %u != %u at %u[%u]\n",
 201                                        gdt_buf[last], expect, gdt_blk, last);
 202 #endif
 203                                 retval = EXT2_ET_RESIZE_INODE_CORRUPT;
 204                                 goto out_dindir;
 205                         }
 206                         last++;
 207                 }
 208                 if (gdt_dirty) {
 209 #ifdef RES_GDT_DEBUG
 210                         printf("writing primary GDT block %u\n", gdt_blk);
 211 #endif
 212                         retval = ext2fs_write_ind_block(fs, gdt_blk, gdt_buf);
 213                         if (retval)
 214                                 goto out_dindir;
 215                 }
 216         }
 217
 218 out_dindir:
 219         if (dindir_dirty) {
 220                 retval2 = ext2fs_write_ind_block(fs, dindir_blk, dindir_buf);
 221                 if (!retval)
 222                         retval = retval2;
 223         }
 224 out_inode:
 225 #ifdef RES_GDT_DEBUG
 226         printf("inode.i_blocks = %u, i_size = %lu\n", inode.i_blocks,
 227                EXT2_I_SIZE(&inode));
 228 #endif
 229         if (inode_dirty) {
 230                 inode.i_atime = inode.i_mtime = fs->now ? fs->now : time(0);
 231                 retval2 = ext2fs_write_new_inode(fs, EXT2_RESIZE_INO, &inode);
 232                 if (!retval)
 233                         retval = retval2;
 234         }
 235 out_free:
 236         ext2fs_free_mem(&dindir_buf);
 237         return retval;
 238 }
 239