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 Public
   9  * License.
  10  * %End-Header%
  11  */
  12
  13 #include <stdio.h>
  14 #include <string.h>
  15 #include <time.h>
  16 #include "ext2_fs.h"
  17 #include "ext2fs.h"
  18
  19 /*
  20  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
  21  * ext3 filesystem.  The counters should be initialized to 1, 5, and 7 before
  22  * calling this for the first time.  In a sparse filesystem it will be the
  23  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
  24  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
  25  */
  26 static unsigned int list_backups(ext2_filsys fs, unsigned int *three,
  27                                  unsigned int *five, unsigned int *seven)
  28 {
  29         unsigned int *min = three;
  30         int mult = 3;
  31         unsigned int ret;
  32
  33         if (!(fs->super->s_feature_ro_compat &
  34               EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
  35                 ret = *min;
  36                 *min += 1;
  37                 return ret;
  38         }
  39
  40         if (*five < *min) {
  41                 min = five;
  42                 mult = 5;
  43         }
  44         if (*seven < *min) {
  45                 min = seven;
  46                 mult = 7;
  47         }
  48
  49         ret = *min;
  50         *min *= mult;
  51
  52         return ret;
  53 }
  54
  55 /*
  56  * This code assumes that the reserved blocks have already been marked in-use
  57  * during ext2fs_initialize(), so that they are not allocated for other
  58  * uses before we can add them to the resize inode (which has to come
  59  * after the creation of the inode table).
  60  */
  61 errcode_t ext2fs_create_resize_inode(ext2_filsys fs)
  62 {
  63         errcode_t               retval, retval2;
  64         struct ext2_super_block *sb;
  65         struct ext2_inode       inode;
  66         __u32                   *dindir_buf, *gdt_buf;
  67         int                     rsv_add;
  68         unsigned long long      apb, inode_size;
  69         blk_t                   dindir_blk, rsv_off, gdt_off, gdt_blk;
  70         int                     dindir_dirty = 0, inode_dirty = 0;
  71
  72         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  73
  74         sb = fs->super;
  75
  76         retval = ext2fs_get_mem(2 * fs->blocksize, &dindir_buf);
  77         if (retval)
  78                 goto out_free;
  79         gdt_buf = (__u32 *)((char *)dindir_buf + fs->blocksize);
  80
  81         retval = ext2fs_read_inode(fs, EXT2_RESIZE_INO, &inode);
  82         if (retval)
  83                 goto out_free;
  84
  85         /* Maximum possible file size (we donly use the dindirect blocks) */
  86         apb = EXT2_ADDR_PER_BLOCK(sb);
  87         rsv_add = fs->blocksize / 512;
  88         if ((dindir_blk = inode.i_block[EXT2_DIND_BLOCK])) {
  89 #ifdef RES_GDT_DEBUG
  90                 printf("reading GDT dindir %u\n", dindir_blk);
  91 #endif
  92                 retval = ext2fs_read_ind_block(fs, dindir_blk, dindir_buf);
  93                 if (retval)
  94                         goto out_inode;
  95         } else {
  96                 blk_t goal = 3 + sb->s_reserved_gdt_blocks +
  97                         fs->desc_blocks + fs->inode_blocks_per_group;
  98
  99                 retval = ext2fs_alloc_block(fs, goal, 0, &dindir_blk);
 100                 if (retval)
 101                         goto out_free;
 102                 inode.i_mode = LINUX_S_IFREG | 0600;
 103                 inode.i_links_count = 1;
 104                 inode.i_block[EXT2_DIND_BLOCK] = dindir_blk;
 105                 inode.i_blocks = rsv_add;
 106                 memset(dindir_buf, 0, fs->blocksize);
 107 #ifdef RES_GDT_DEBUG
 108                 printf("allocated GDT dindir %u\n", dindir_blk);
 109 #endif
 110                 dindir_dirty = inode_dirty = 1;
 111                 inode_size = apb*apb + apb + EXT2_NDIR_BLOCKS;
 112                 inode_size *= fs->blocksize;
 113                 inode.i_size = inode_size & 0xFFFFFFFF;
 114                 inode.i_size_high = (inode_size >> 32) & 0xFFFFFFFF;
 115                 if(inode.i_size_high) {
 116                         sb->s_feature_ro_compat |=
 117                                 EXT2_FEATURE_RO_COMPAT_LARGE_FILE;
 118                 }
 119                 inode.i_ctime = fs->now ? fs->now : time(0);
 120         }
 121
 122         for (rsv_off = 0, gdt_off = fs->desc_blocks,
 123              gdt_blk = sb->s_first_data_block + 1 + fs->desc_blocks;
 124              rsv_off < sb->s_reserved_gdt_blocks;
 125              rsv_off++, gdt_off++, gdt_blk++) {
 126                 unsigned int three = 1, five = 5, seven = 7;
 127                 unsigned int grp, last = 0;
 128                 int gdt_dirty = 0;
 129
 130                 gdt_off %= apb;
 131                 if (!dindir_buf[gdt_off]) {
 132                         /* FIXME XXX XXX
 133                         blk_t new_blk;
 134
 135                         retval = ext2fs_new_block(fs, gdt_blk, 0, &new_blk);
 136                         if (retval)
 137                                 goto out_free;
 138                         if (new_blk != gdt_blk) {
 139                                 // XXX free block
 140                                 retval = -1; // XXX
 141                         }
 142                         */
 143                         gdt_dirty = dindir_dirty = inode_dirty = 1;
 144                         memset(gdt_buf, 0, fs->blocksize);
 145                         dindir_buf[gdt_off] = gdt_blk;
 146                         inode.i_blocks += rsv_add;
 147 #ifdef RES_GDT_DEBUG
 148                         printf("added primary GDT block %u at %u[%u]\n",
 149                                gdt_blk, dindir_blk, gdt_off);
 150 #endif
 151                 } else if (dindir_buf[gdt_off] == gdt_blk) {
 152 #ifdef RES_GDT_DEBUG
 153                         printf("reading primary GDT block %u\n", gdt_blk);
 154 #endif
 155                         retval = ext2fs_read_ind_block(fs, gdt_blk, gdt_buf);
 156                         if (retval)
 157                                 goto out_dindir;
 158                 } else {
 159 #ifdef RES_GDT_DEBUG
 160                         printf("bad primary GDT %u != %u at %u[%u]\n",
 161                                dindir_buf[gdt_off], gdt_blk,dindir_blk,gdt_off);
 162 #endif
 163                         retval = EXT2_ET_RESIZE_INODE_CORRUPT;
 164                         goto out_dindir;
 165                 }
 166
 167                 while ((grp = list_backups(fs, &three, &five, &seven)) <
 168                        fs->group_desc_count) {
 169                         blk_t expect = gdt_blk + grp * sb->s_blocks_per_group;
 170
 171                         if (!gdt_buf[last]) {
 172 #ifdef RES_GDT_DEBUG
 173                                 printf("added backup GDT %u grp %u@%u[%u]\n",
 174                                        expect, grp, gdt_blk, last);
 175 #endif
 176                                 gdt_buf[last] = expect;
 177                                 inode.i_blocks += rsv_add;
 178                                 gdt_dirty = inode_dirty = 1;
 179                         } else if (gdt_buf[last] != expect) {
 180 #ifdef RES_GDT_DEBUG
 181                                 printf("bad backup GDT %u != %u at %u[%u]\n",
 182                                        gdt_buf[last], expect, gdt_blk, last);
 183 #endif
 184                                 retval = EXT2_ET_RESIZE_INODE_CORRUPT;
 185                                 goto out_dindir;
 186                         }
 187                         last++;
 188                 }
 189                 if (gdt_dirty) {
 190 #ifdef RES_GDT_DEBUG
 191                         printf("writing primary GDT block %u\n", gdt_blk);
 192 #endif
 193                         retval = ext2fs_write_ind_block(fs, gdt_blk, gdt_buf);
 194                         if (retval)
 195                                 goto out_dindir;
 196                 }
 197         }
 198
 199 out_dindir:
 200         if (dindir_dirty) {
 201                 retval2 = ext2fs_write_ind_block(fs, dindir_blk, dindir_buf);
 202                 if (!retval)
 203                         retval = retval2;
 204         }
 205 out_inode:
 206 #ifdef RES_GDT_DEBUG
 207         printf("inode.i_blocks = %u, i_size = %u\n", inode.i_blocks,
 208                inode.i_size);
 209 #endif
 210         if (inode_dirty) {
 211                 inode.i_atime = inode.i_mtime = fs->now ? fs->now : time(0);
 212                 retval2 = ext2fs_write_inode(fs, EXT2_RESIZE_INO, &inode);
 213                 if (!retval)
 214                         retval = retval2;
 215         }
 216 out_free:
 217         ext2fs_free_mem(&dindir_buf);
 218         return retval;
 219 }
 220