fsw_ext4_readlink,
};
+
+static inline int test_root(fsw_u32 a, int b)
+{
+ int num = b;
+
+ while (a > num)
+ num *= b;
+ return num == a;
+}
+
+static int fsw_ext4_group_sparse(fsw_u32 group)
+{
+ if (group <= 1)
+ return 1;
+ if (!(group & 1))
+ return 0;
+ return (test_root(group, 7) || test_root(group, 5) ||
+ test_root(group, 3));
+}
+
+/* calculate the first block number of the group */
+static inline fsw_u32
+fsw_ext4_group_first_block_no(struct ext4_super_block *sb, fsw_u32 group_no)
+{
+ return group_no * (fsw_u32)EXT4_BLOCKS_PER_GROUP(sb) +
+ sb->s_first_data_block;
+}
+
/**
* Mount an ext4 volume. Reads the superblock and constructs the
* root directory dnode.
fsw_status_t status;
void *buffer;
fsw_u32 blocksize;
- fsw_u32 groupcnt, groupno, gdesc_per_block, gdesc_bno, gdesc_index;
+ fsw_u32 groupcnt, groupno, gdesc_per_block, gdesc_bno, gdesc_index, metabg_of_gdesc;
struct ext4_group_desc *gdesc;
int i;
struct fsw_string s;
if (vol->sb->s_rev_level == EXT4_DYNAMIC_REV &&
(vol->sb->s_feature_incompat & ~(EXT4_FEATURE_INCOMPAT_FILETYPE | EXT4_FEATURE_INCOMPAT_RECOVER |
- EXT4_FEATURE_INCOMPAT_EXTENTS | EXT4_FEATURE_INCOMPAT_FLEX_BG)))
+ EXT4_FEATURE_INCOMPAT_EXTENTS | EXT4_FEATURE_INCOMPAT_FLEX_BG |
+ EXT4_FEATURE_INCOMPAT_META_BG)))
return FSW_UNSUPPORTED;
// size of group descriptor depends on feature....
if (!(vol->sb->s_feature_incompat & EXT4_FEATURE_INCOMPAT_64BIT)) {
- // Default minimal group descriptor size...
+ // Default minimal group descriptor size... (this might not be set in old ext2 filesystems, therefor set it!)
vol->sb->s_desc_size = EXT4_MIN_DESC_SIZE;
}
// Calculate group descriptor count the way the kernel does it...
groupcnt = (vol->sb->s_blocks_count_lo - vol->sb->s_first_data_block +
vol->sb->s_blocks_per_group - 1) / vol->sb->s_blocks_per_group;
- // Descriptors in one block... s_desc_size needs to be set!
+
+ // Descriptors in one block... s_desc_size needs to be set! (Usually 128 since normal block
+ // descriptors are 32 byte and block size is 4096)
gdesc_per_block = EXT4_DESC_PER_BLOCK(vol->sb);
// Read the group descriptors to get inode table offsets
status = fsw_alloc(sizeof(fsw_u32) * groupcnt, &vol->inotab_bno);
if (status)
return status;
+
+ // Loop through all block group descriptors in order to get inode table locations
for (groupno = 0; groupno < groupcnt; groupno++) {
- // get the block group descriptor
- gdesc_bno = (vol->sb->s_first_data_block + 1) + groupno / gdesc_per_block;
+
+ // Calculate the block number which contains the block group descriptor we look for
+ if(vol->sb->s_feature_incompat & EXT4_FEATURE_INCOMPAT_META_BG && groupno >= vol->sb->s_first_meta_bg)
+ {
+ // If option meta_bg is set, the block group descriptor is in meta block group...
+ metabg_of_gdesc = (fsw_u32)(groupno / gdesc_per_block) * gdesc_per_block;
+ gdesc_bno = fsw_ext4_group_first_block_no(vol->sb, metabg_of_gdesc);
+ // We need to know if the block group in questition has a super block, if yes, the
+ // block group descriptors are in the next block number
+ if(!(vol->sb->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) || fsw_ext4_group_sparse(metabg_of_gdesc))
+ gdesc_bno += 1;
+ }
+ else
+ {
+ // All group descriptors follow the super block (+1)
+ gdesc_bno = (vol->sb->s_first_data_block + 1) + groupno / gdesc_per_block;
+ }
gdesc_index = groupno % gdesc_per_block;
+
+ // Get block if necessary...
status = fsw_block_get(vol, gdesc_bno, 1, (void **)&buffer);
if (status)
return status;
+
+ // Get group descriptor table and block number of inode table...
gdesc = (struct ext4_group_desc *)(buffer + gdesc_index * vol->sb->s_desc_size);
vol->inotab_bno[groupno] = gdesc->bg_inode_table_lo;
+
fsw_block_release(vol, gdesc_bno, buffer);
}
struct fsw_extent *extent)
{
fsw_status_t status;
- fsw_u32 bno, release_bno, buf_bcnt, buf_offset, file_bcnt;
+ fsw_u32 bno, release_bno, buf_offset, file_bcnt;
int ext_cnt;
- int ext_depth;
void *buffer;
struct ext4_extent_header *ext4_extent_header;
// First buffer is the i_block field from inode...
buffer = (void *)dno->raw->i_block;
- buf_bcnt = EXT4_NDIR_BLOCKS;
buf_offset = 0;
while(1) {
ext4_extent_header = (struct ext4_extent_header *)buffer + buf_offset;
ext4_extent_header->eh_depth));
ext4_extent_idx = (struct ext4_extent_idx *)(buffer + buf_offset);
buf_offset += sizeof(struct ext4_extent_idx);
-
+
FSW_MSG_DEBUG((FSW_MSGSTR("fsw_ext4_get_by_extent: index node covers block %d...\n"),
ext4_extent_idx->ei_block));
if(bno >= ext4_extent_idx->ei_block)
}
}
}
-
+
return FSW_NOT_FOUND;
}