1 /* vi: set sw=4 ts=4: */
3 * rw_bitmaps.c --- routines to read and write the inode and block bitmaps.
5 * Copyright (C) 1993, 1994, 1994, 1996 Theodore Ts'o.
8 * This file may be redistributed under the terms of the GNU Public
20 #ifdef HAVE_SYS_STAT_H
23 #ifdef HAVE_SYS_TYPES_H
24 #include <sys/types.h>
31 #if defined(__powerpc__) && BB_BIG_ENDIAN
33 * On the PowerPC, the big-endian variant of the ext2 filesystem
34 * has its bitmaps stored as 32-bit words with bit 0 as the LSB
35 * of each word. Thus a bitmap with only bit 0 set would be, as
36 * a string of bytes, 00 00 00 01 00 ...
37 * To cope with this, we byte-reverse each word of a bitmap if
38 * we have a big-endian filesystem, that is, if we are *not*
39 * byte-swapping other word-sized numbers.
41 #define EXT2_BIG_ENDIAN_BITMAPS
44 #ifdef EXT2_BIG_ENDIAN_BITMAPS
45 static void ext2fs_swap_bitmap(ext2_filsys fs
, char *bitmap
, int nbytes
)
47 __u32
*p
= (__u32
*) bitmap
;
50 for (n
= nbytes
/ sizeof(__u32
); n
> 0; --n
, ++p
)
51 *p
= ext2fs_swab32(*p
);
55 errcode_t
ext2fs_write_inode_bitmap(ext2_filsys fs
)
60 char * inode_bitmap
= fs
->inode_map
->bitmap
;
61 char * bitmap_block
= NULL
;
64 EXT2_CHECK_MAGIC(fs
, EXT2_ET_MAGIC_EXT2FS_FILSYS
);
66 if (!(fs
->flags
& EXT2_FLAG_RW
))
67 return EXT2_ET_RO_FILSYS
;
70 nbytes
= (size_t) ((EXT2_INODES_PER_GROUP(fs
->super
)+7) / 8);
72 retval
= ext2fs_get_mem(fs
->blocksize
, &bitmap_block
);
75 memset(bitmap_block
, 0xff, fs
->blocksize
);
76 for (i
= 0; i
< fs
->group_desc_count
; i
++) {
77 memcpy(bitmap_block
, inode_bitmap
, nbytes
);
78 blk
= fs
->group_desc
[i
].bg_inode_bitmap
;
80 #ifdef EXT2_BIG_ENDIAN_BITMAPS
81 if (!((fs
->flags
& EXT2_FLAG_SWAP_BYTES
) ||
82 (fs
->flags
& EXT2_FLAG_SWAP_BYTES_WRITE
)))
83 ext2fs_swap_bitmap(fs
, bitmap_block
, nbytes
);
85 retval
= io_channel_write_blk(fs
->io
, blk
, 1,
88 return EXT2_ET_INODE_BITMAP_WRITE
;
90 inode_bitmap
+= nbytes
;
92 fs
->flags
&= ~EXT2_FLAG_IB_DIRTY
;
93 ext2fs_free_mem(&bitmap_block
);
97 errcode_t
ext2fs_write_block_bitmap (ext2_filsys fs
)
104 char * block_bitmap
= fs
->block_map
->bitmap
;
105 char * bitmap_block
= NULL
;
108 EXT2_CHECK_MAGIC(fs
, EXT2_ET_MAGIC_EXT2FS_FILSYS
);
110 if (!(fs
->flags
& EXT2_FLAG_RW
))
111 return EXT2_ET_RO_FILSYS
;
114 nbytes
= EXT2_BLOCKS_PER_GROUP(fs
->super
) / 8;
115 retval
= ext2fs_get_mem(fs
->blocksize
, &bitmap_block
);
118 memset(bitmap_block
, 0xff, fs
->blocksize
);
119 for (i
= 0; i
< fs
->group_desc_count
; i
++) {
120 memcpy(bitmap_block
, block_bitmap
, nbytes
);
121 if (i
== fs
->group_desc_count
- 1) {
122 /* Force bitmap padding for the last group */
123 nbits
= ((fs
->super
->s_blocks_count
124 - fs
->super
->s_first_data_block
)
125 % EXT2_BLOCKS_PER_GROUP(fs
->super
));
127 for (j
= nbits
; j
< fs
->blocksize
* 8; j
++)
128 ext2fs_set_bit(j
, bitmap_block
);
130 blk
= fs
->group_desc
[i
].bg_block_bitmap
;
132 #ifdef EXT2_BIG_ENDIAN_BITMAPS
133 if (!((fs
->flags
& EXT2_FLAG_SWAP_BYTES
) ||
134 (fs
->flags
& EXT2_FLAG_SWAP_BYTES_WRITE
)))
135 ext2fs_swap_bitmap(fs
, bitmap_block
, nbytes
);
137 retval
= io_channel_write_blk(fs
->io
, blk
, 1,
140 return EXT2_ET_BLOCK_BITMAP_WRITE
;
142 block_bitmap
+= nbytes
;
144 fs
->flags
&= ~EXT2_FLAG_BB_DIRTY
;
145 ext2fs_free_mem(&bitmap_block
);
149 static errcode_t
read_bitmaps(ext2_filsys fs
, int do_inode
, int do_block
)
152 char *block_bitmap
= NULL
, *inode_bitmap
= NULL
;
155 int block_nbytes
= (int) EXT2_BLOCKS_PER_GROUP(fs
->super
) / 8;
156 int inode_nbytes
= (int) EXT2_INODES_PER_GROUP(fs
->super
) / 8;
159 EXT2_CHECK_MAGIC(fs
, EXT2_ET_MAGIC_EXT2FS_FILSYS
);
161 fs
->write_bitmaps
= ext2fs_write_bitmaps
;
163 retval
= ext2fs_get_mem(strlen(fs
->device_name
) + 80, &buf
);
167 ext2fs_free_block_bitmap(fs
->block_map
);
168 sprintf(buf
, "block bitmap for %s", fs
->device_name
);
169 retval
= ext2fs_allocate_block_bitmap(fs
, buf
, &fs
->block_map
);
172 block_bitmap
= fs
->block_map
->bitmap
;
175 ext2fs_free_inode_bitmap(fs
->inode_map
);
176 sprintf(buf
, "inode bitmap for %s", fs
->device_name
);
177 retval
= ext2fs_allocate_inode_bitmap(fs
, buf
, &fs
->inode_map
);
180 inode_bitmap
= fs
->inode_map
->bitmap
;
182 ext2fs_free_mem(&buf
);
184 if (fs
->flags
& EXT2_FLAG_IMAGE_FILE
) {
186 blk
= (fs
->image_header
->offset_inodemap
/
188 retval
= io_channel_read_blk(fs
->image_io
, blk
,
189 -(inode_nbytes
* fs
->group_desc_count
),
195 blk
= (fs
->image_header
->offset_blockmap
/
197 retval
= io_channel_read_blk(fs
->image_io
, blk
,
198 -(block_nbytes
* fs
->group_desc_count
),
206 for (i
= 0; i
< fs
->group_desc_count
; i
++) {
208 blk
= fs
->group_desc
[i
].bg_block_bitmap
;
210 retval
= io_channel_read_blk(fs
->io
, blk
,
211 -block_nbytes
, block_bitmap
);
213 retval
= EXT2_ET_BLOCK_BITMAP_READ
;
216 #ifdef EXT2_BIG_ENDIAN_BITMAPS
217 if (!((fs
->flags
& EXT2_FLAG_SWAP_BYTES
) ||
218 (fs
->flags
& EXT2_FLAG_SWAP_BYTES_READ
)))
219 ext2fs_swap_bitmap(fs
, block_bitmap
, block_nbytes
);
222 memset(block_bitmap
, 0, block_nbytes
);
223 block_bitmap
+= block_nbytes
;
226 blk
= fs
->group_desc
[i
].bg_inode_bitmap
;
228 retval
= io_channel_read_blk(fs
->io
, blk
,
229 -inode_nbytes
, inode_bitmap
);
231 retval
= EXT2_ET_INODE_BITMAP_READ
;
234 #ifdef EXT2_BIG_ENDIAN_BITMAPS
235 if (!((fs
->flags
& EXT2_FLAG_SWAP_BYTES
) ||
236 (fs
->flags
& EXT2_FLAG_SWAP_BYTES_READ
)))
237 ext2fs_swap_bitmap(fs
, inode_bitmap
, inode_nbytes
);
240 memset(inode_bitmap
, 0, inode_nbytes
);
241 inode_bitmap
+= inode_nbytes
;
248 ext2fs_free_mem(&fs
->block_map
);
251 ext2fs_free_mem(&fs
->inode_map
);
253 ext2fs_free_mem(&buf
);
257 errcode_t
ext2fs_read_inode_bitmap (ext2_filsys fs
)
259 return read_bitmaps(fs
, 1, 0);
262 errcode_t
ext2fs_read_block_bitmap(ext2_filsys fs
)
264 return read_bitmaps(fs
, 0, 1);
267 errcode_t
ext2fs_read_bitmaps(ext2_filsys fs
)
269 EXT2_CHECK_MAGIC(fs
, EXT2_ET_MAGIC_EXT2FS_FILSYS
);
271 if (fs
->inode_map
&& fs
->block_map
)
274 return read_bitmaps(fs
, !fs
->inode_map
, !fs
->block_map
);
277 errcode_t
ext2fs_write_bitmaps(ext2_filsys fs
)
281 EXT2_CHECK_MAGIC(fs
, EXT2_ET_MAGIC_EXT2FS_FILSYS
);
283 if (fs
->block_map
&& ext2fs_test_bb_dirty(fs
)) {
284 retval
= ext2fs_write_block_bitmap(fs
);
288 if (fs
->inode_map
&& ext2fs_test_ib_dirty(fs
)) {
289 retval
= ext2fs_write_inode_bitmap(fs
);