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ext4-realloc-inodes/realloc-inodes.c

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/**
* An attempt to write a tool for ext4 that will allow to change inode count of a filesystem.
*
* In theory it shouldn't be that hard:
* 1) If shrinking:
* 1.1) mark the end of each inode table as reserved (to make sure the inode allocator won't allocate it)
* 1.2) if there were some inodes, move them away:
* 1.2.1) allocate a new place for each inode, copy it there
* 1.2.2) remember the old->new inode number mapping
* 1.3) mark some blocks that belonged to inode table as free
* 2) If growing:
* 2.1) check all extra blocks that will be occupied by the growing inode tables,
* mark them as occupied if there are free ()
* 2.2) move data away from 'extra blocks' that were occupied
* 3) Change all inode numbers in directory entries so that
* new_num = (old_num/old_inodes_per_group)*new_inodes_per_group + (old_num%inodes_per_group)
* also translate old->new inode numbers remembered at (1.2.2)
* 4) Change superblock: s_inodes_count, s_free_inodes_count, s_inodes_per_group
* 5) Change block group descriptors: bg_inode_table_(lo,hi), bg_free_inodes_count_(lo,hi),
* bg_inode_bitmap_csum_(lo,hi), bg_itable_unused_(lo,hi)
* 6) If flex_bg is enabled, move parts of old inode tables so they are consecutive again
*
* This is a destructive process involving metadata change so it would be good if
* we could first write a file containing all necessary changes, then backup all
* changed blocks, and then write new blocks to the disk. (maybe just use undo_io_manager?)
*/
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>
#include <errno.h>
#include <ext2fs/ext2_fs.h>
#include <ext2fs/ext2fs.h>
#define _(a) (a)
// "local data" for the inode reallocation process
typedef struct
{
ext2_filsys fs;
int fs_fd;
char *device_name, *io_options;
__u32 new_inode_count, new_inodes_per_group, new_inode_blocks_per_group;
// (old->new) inode number map
ext2_ino_t *inode_map;
__u32 inode_map_size, inode_map_alloc;
} realloc_data;
// Utility functions for (old -> new) inode number map
void realloc_add_inode_map(realloc_data *rd, ext2_ino_t old, ext2_ino_t new)
{
if (!old || !new)
{
return;
}
if (2*rd->inode_map_size >= rd->inode_map_alloc)
{
rd->inode_map_alloc += 1024;
rd->inode_map = realloc(rd->inode_map, sizeof(ext2_ino_t) * rd->inode_map_alloc);
}
rd->inode_map[rd->inode_map_size*2] = old;
rd->inode_map[rd->inode_map_size*2+1] = new;
rd->inode_map_size++;
}
int realloc_compare_inode_map_callback(const void *a, const void *b)
{
return *((ext2_ino_t*)a) - *((ext2_ino_t*)b);
}
void realloc_sort_inode_map(realloc_data *rd)
{
if (!rd->inode_map)
{
return;
}
qsort(rd->inode_map, rd->inode_map_size, sizeof(ext2_ino_t)*2, realloc_compare_inode_map_callback);
}
ext2_ino_t realloc_search_inode_map(realloc_data *rd, ext2_ino_t old)
{
__u32 start = 0, end = rd->inode_map_size, cur;
ext2_ino_t cur_ino;
if (!rd->inode_map)
{
return 0;
}
while (end-start > 1)
{
cur = (start+end)>>1;
cur_ino = rd->inode_map[cur<<1];
if (cur_ino < old)
{
start = cur+1;
}
else if (cur_ino > old)
{
end = cur;
}
else
{
return rd->inode_map[(cur<<1)+1];
}
}
return 0;
}
/**
* Move inodes from the end of each block group inode table
* so the tables can be shrinked
*/
int shrink_move_inodes(realloc_data *rd)
{
int retval = 0, inode_size = EXT2_INODE_SIZE(rd->fs->super);
__u32 group, i;
__u32 new_group;
ext2_ino_t ino, new_ino;
struct ext2_inode *inode = NULL;
ext2fs_read_inode_bitmap(rd->fs);
if (retval)
{
return retval;
}
retval = ext2fs_get_mem(inode_size, &inode);
if (retval)
{
return retval;
}
for (group = 0; group < rd->fs->group_desc_count; group++)
{
for (i = rd->new_inodes_per_group; i < EXT2_INODES_PER_GROUP(rd->fs->super); i++)
{
ino = 1 + group*EXT2_INODES_PER_GROUP(rd->fs->super) + i;
if (ext2fs_test_inode_bitmap2(rd->fs->inode_map, ino))
{
// Inode is occupied and should be moved
new_group = group;
do
{
retval = ext2fs_find_first_zero_inode_bitmap2(rd->fs->inode_map,
1 + new_group*EXT2_INODES_PER_GROUP(rd->fs->super),
1 + new_group*EXT2_INODES_PER_GROUP(rd->fs->super)+rd->new_inodes_per_group, &new_ino);
if (!retval)
{
break;
}
new_group = (new_group+1) % rd->fs->group_desc_count;
} while (new_group != group);
if (retval)
{
// No space to move this inode
goto out;
}
// Copy inode to the new place
retval = ext2fs_read_inode_full(rd->fs, ino, inode, inode_size);
if (retval)
{
goto out;
}
retval = ext2fs_write_inode_full(rd->fs, new_ino, inode, inode_size);
if (retval)
{
goto out;
}
retval = ext2fs_mark_inode_bitmap2(rd->fs->inode_map, new_ino);
if (retval)
{
goto out;
}
ext2fs_mark_ib_dirty(rd->fs);
// Remember mapping
realloc_add_inode_map(rd, ino, new_ino);
}
}
}
out:
if (inode)
{
ext2fs_free_mem(&inode);
}
return retval;
}
/**
* Move data blocks from after the end of each block group inode table
* so the tables can be grown
*/
int extend_move_blocks(realloc_data *rd)
{
return ENOSYS;
}
static int change_inode_numbers_callback(ext2_ino_t dir, int entry,
struct ext2_dir_entry *dirent, int offset,
int blocksize, char *buf, void *priv_data)
{
realloc_data *rd = priv_data;
ext2_ino_t new_ino = realloc_search_inode_map(rd, dirent->inode);
if (!new_ino)
{
new_ino = dirent->inode;
}
new_ino = 1 + (new_ino-1)/EXT2_INODES_PER_GROUP(rd->fs->super)*rd->new_inodes_per_group +
(new_ino-1)%EXT2_INODES_PER_GROUP(rd->fs->super);
if (new_ino != dirent->inode)
{
dirent->inode = new_ino;
return DIRENT_CHANGED;
}
return 0;
}
/**
* Change inode numbers in all directory entries
*/
int change_inode_numbers(realloc_data *rd)
{
ext2_ino_t ino;
realloc_sort_inode_map(rd);
for (ino = 1; ino <= rd->fs->super->s_inodes_count; ino++)
{
ext2fs_dir_iterate2(rd->fs, ino, 0, 0, change_inode_numbers_callback, rd);
}
return 0;
}
/**
* 1) Move inode tables so they are consecutive again if flex_bg is enabled
* 2) Mark/unmark extra inode table blocks
* 3) Adjust superblock and block group descriptors
*/
int change_super_and_bgd(realloc_data *rd)
{
blk64_t it_start, blk;
dgrp_t grp, n_flex, n_grp;
__u32 unus;
int i_per_g_diff = 0;
int flexbg_size = 0, i, retval = 0;
void *buf = NULL;
ext2fs_flush(rd->fs);
ext2fs_read_block_bitmap(rd->fs);
if (rd->new_inode_blocks_per_group != rd->fs->inode_blocks_per_group)
{
// Move inode tables if flex_bg is active
if (EXT2_HAS_INCOMPAT_FEATURE(rd->fs->super, EXT4_FEATURE_INCOMPAT_FLEX_BG)
&& rd->fs->super->s_log_groups_per_flex)
{
flexbg_size = 1 << rd->fs->super->s_log_groups_per_flex;
retval = ext2fs_get_mem(EXT2_BLOCK_SIZE(rd->fs->super) * rd->new_inode_blocks_per_group * flexbg_size, &buf);
if (retval)
{
goto out;
}
i_per_g_diff = rd->new_inodes_per_group - EXT2_INODES_PER_GROUP(rd->fs->super);
for (n_flex = 0; n_flex < rd->fs->group_desc_count/flexbg_size; n_flex++)
{
n_grp = flexbg_size;
if (n_flex*flexbg_size+n_grp > rd->fs->group_desc_count)
{
n_grp = rd->fs->group_desc_count-n_flex*flexbg_size;
}
// Read inode tables
for (grp = n_flex*flexbg_size, i = 0; i < n_grp; grp++, i++)
{
if (!ext2fs_bg_flags_test(rd->fs, grp, EXT2_BG_INODE_UNINIT))
{
blk = ext2fs_inode_table_loc(rd->fs, grp);
retval = io_channel_read_blk64(rd->fs->io, blk, rd->new_inode_blocks_per_group,
buf + i*rd->new_inode_blocks_per_group*EXT2_BLOCK_SIZE(rd->fs->super));
if (retval)
{
goto out;
}
}
}
// Write inode table to the new place
it_start = ext2fs_inode_table_loc(rd->fs, n_flex*flexbg_size);
blk = rd->new_inode_blocks_per_group * n_grp;
retval = io_channel_write_blk64(rd->fs->io, it_start, blk, buf);
if (retval)
{
// The FS is badly corrupted now :-(
printf("Error moving inode tables for %u groups, starting from %u\n", n_grp, n_flex*flexbg_size);
goto out;
}
// Mark/unmark extra inode table blocks
if (rd->new_inode_blocks_per_group < rd->fs->inode_blocks_per_group)
{
ext2fs_unmark_block_bitmap_range2(rd->fs->block_map, it_start+blk,
(rd->fs->inode_blocks_per_group-rd->new_inode_blocks_per_group)*n_grp);
}
else
{
ext2fs_mark_block_bitmap_range2(rd->fs->block_map, it_start+blk,
(rd->new_inode_blocks_per_group-rd->fs->inode_blocks_per_group)*n_grp);
}
if (!ext2fs_bg_flags_test(rd->fs, n_flex*flexbg_size, EXT2_BG_INODE_UNINIT))
{
ext2fs_bg_free_blocks_count_set(rd->fs, n_flex*flexbg_size,
ext2fs_bg_free_blocks_count(rd->fs, n_flex*flexbg_size) -
(rd->new_inode_blocks_per_group - rd->fs->inode_blocks_per_group)*flexbg_size);
}
// Change inode table locations and free inode counts
for (grp = n_flex*flexbg_size, i = 0; i < n_grp; grp++, i++)
{
blk = it_start + rd->new_inode_blocks_per_group*i;
ext2fs_inode_table_loc_set(rd->fs, grp, blk);
ext2fs_bg_free_inodes_count_set(rd->fs, grp,
ext2fs_bg_free_inodes_count(rd->fs, grp) + i_per_g_diff);
unus = ext2fs_bg_itable_unused(rd->fs, grp);
unus = unus < i_per_g_diff ? 0 : unus - i_per_g_diff;
ext2fs_bg_itable_unused_set(rd->fs, grp, unus);
ext2fs_group_desc_csum_set(rd->fs, grp);
}
}
}
else
{
// Mark/unmark extra inode table blocks (without flex_bg)
for (grp = 0; grp < rd->fs->group_desc_count; grp++)
{
it_start = ext2fs_inode_table_loc(rd->fs, grp);
if (rd->new_inode_blocks_per_group < rd->fs->inode_blocks_per_group)
{
ext2fs_unmark_block_bitmap_range2(rd->fs->block_map, it_start,
rd->fs->inode_blocks_per_group-rd->new_inode_blocks_per_group);
}
else
{
ext2fs_mark_block_bitmap_range2(rd->fs->block_map, it_start,
rd->new_inode_blocks_per_group-rd->fs->inode_blocks_per_group);
}
ext2fs_bg_free_blocks_count_set(rd->fs, grp, ext2fs_bg_free_blocks_count(rd->fs, grp) -
rd->new_inode_blocks_per_group + rd->fs->inode_blocks_per_group);
ext2fs_bg_free_inodes_count_set(rd->fs, grp, ext2fs_bg_free_inodes_count(rd->fs, grp) +
rd->new_inodes_per_group - EXT2_INODES_PER_GROUP(rd->fs->super));
unus = ext2fs_bg_itable_unused(rd->fs, grp);
unus = unus < i_per_g_diff ? 0 : unus - i_per_g_diff;
ext2fs_bg_itable_unused_set(rd->fs, grp, unus);
ext2fs_group_desc_csum_set(rd->fs, grp);
}
}
}
ext2fs_mark_bb_dirty(rd->fs);
retval = rd->fs->write_bitmaps(rd->fs);
if (retval)
{
goto out;
}
rd->fs->write_bitmaps = NULL;
ext2fs_free_blocks_count_add(rd->fs->super, rd->fs->group_desc_count * (rd->fs->inode_blocks_per_group - rd->new_inode_blocks_per_group));
rd->fs->super->s_free_inodes_count += rd->fs->group_desc_count * (rd->new_inodes_per_group - EXT2_INODES_PER_GROUP(rd->fs->super));
rd->fs->super->s_inodes_per_group = rd->new_inodes_per_group;
rd->fs->super->s_inodes_count = rd->fs->group_desc_count * rd->new_inodes_per_group;
ext2fs_mark_super_dirty(rd->fs);
out:
if (buf)
{
ext2fs_free_mem(&buf);
}
return retval;
}
/**
* Main function: change inode number of a filesystem!
*/
int do_realloc(realloc_data *rd)
{
int retval;
rd->new_inodes_per_group = rd->new_inode_count / rd->fs->group_desc_count;
rd->new_inodes_per_group &= ~7;
if (rd->new_inodes_per_group < 16)
{
printf("Too small number of inodes requested (%u), min inodes per group = 16\n", rd->new_inodes_per_group);
return ENOENT;
}
rd->new_inode_blocks_per_group =
(rd->new_inodes_per_group * EXT2_INODE_SIZE(rd->fs->super) +
EXT2_BLOCK_SIZE(rd->fs->super) - 1) / EXT2_BLOCK_SIZE(rd->fs->super);
rd->new_inode_count = rd->new_inodes_per_group * rd->fs->group_desc_count;
if (rd->new_inodes_per_group < EXT2_INODES_PER_GROUP(rd->fs->super))
{
if (rd->new_inode_count < rd->fs->super->s_inodes_count - rd->fs->super->s_free_inodes_count)
{
printf("Too small number of inodes requested, existing inodes (%u) won't fit\n",
rd->fs->super->s_inodes_count - rd->fs->super->s_free_inodes_count);
return ENOENT;
}
printf("Phase 1: Moving inodes out of the way\n");
retval = shrink_move_inodes(rd);
if (retval)
{
return retval;
}
}
else if (rd->new_inodes_per_group > EXT2_INODES_PER_GROUP(rd->fs->super))
{
blk64_t required_blocks = (rd->new_inode_blocks_per_group - rd->fs->inode_blocks_per_group) * rd->fs->group_desc_count;
if (required_blocks > ext2fs_free_blocks_count(rd->fs->super))
{
printf("Requested number of inodes is too big, it requires %llu free blocks, "
"and there are only %llu free blocks available\n",
required_blocks, ext2fs_free_blocks_count(rd->fs->super));
return ENOENT;
}
printf("Phase 1: Moving data blocks out of the way\n");
retval = extend_move_blocks(rd);
if (retval)
{
return retval;
}
}
else
{
printf("The requested number of inodes is equal to current\n");
return 0;
}
printf("Phase 2: Changing all inode numbers\n");
retval = change_inode_numbers(rd);
if (retval)
{
return retval;
}
printf("Phase 3: Adjusting superblock and block group descriptors\n");
retval = change_super_and_bgd(rd);
if (retval)
{
return retval;
}
return 0;
}
__u32 atou(char *s)
{
__u32 x = 0;
if (s[0] == '0')
{
if (s[1] == 'x' || s[1] == 'X')
{
sscanf(s+2, "%x", &x);
}
else
{
sscanf(s+1, "%o", &x);
}
}
else
{
sscanf(s, "%u", &x);
}
return x;
}
const char *program_name = "realloc-inodes";
int main(int narg, char **args)
{
realloc_data rd = { 0 };
int optind, retval, io_flags = 0, force = 0;
ext2fs_struct_stat st_buf;
if (narg < 3)
{
printf("USAGE: ./realloc-inodes <device> <new_inode_count>\n");
return 0;
}
optind = 1;
rd.device_name = args[optind++];
rd.new_inode_count = atou(args[optind++]);
add_error_table(&et_ext2_error_table);
// Open FS
rd.fs_fd = ext2fs_open_file(rd.device_name, O_RDWR, 0);
if (rd.fs_fd < 0)
{
com_err("open", errno, _("while opening %s"), rd.device_name);
exit(1);
}
retval = ext2fs_fstat(rd.fs_fd, &st_buf);
if (retval < 0)
{
com_err("open", errno, _("while getting stat information for %s"), rd.device_name);
exit(1);
}
if (!S_ISREG(st_buf.st_mode))
{
close(rd.fs_fd);
rd.fs_fd = -1;
}
rd.io_options = strchr(rd.device_name, '?');
if (rd.io_options)
{
*rd.io_options++ = 0;
}
io_flags = EXT2_FLAG_64BITS | EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE;
retval = ext2fs_open2(rd.device_name, rd.io_options, io_flags, 0, 0, unix_io_manager, &rd.fs);
if (retval)
{
com_err(program_name, retval, _("while trying to open %s"), rd.device_name);
printf(_("Couldn't find valid filesystem superblock.\n"));
goto close_fd;
}
if (!force && ((rd.fs->super->s_state & EXT2_ERROR_FS) || ((rd.fs->super->s_state & EXT2_VALID_FS) == 0)))
{
fprintf(stderr, _("Please run 'e2fsck -f %s' first.\n\n"), rd.device_name);
goto close_fs;
}
// Call main realloc function
retval = do_realloc(&rd);
if (retval)
{
com_err(program_name, retval, _("while resizing inode count"));
goto close_fs;
}
close_fs:
ext2fs_close(rd.fs);
close_fd:
if (rd.fs_fd > 0)
{
close(rd.fs_fd);
}
return retval;
}
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