One more field, minor shrinking, and start on block groups.

2 files changed, 16 insertions, 5 deletions

diff --git a/toys/e2fs.h b/toys/e2fs.h
index b50a8817..49eb4c40 100644
--- a/toys/e2fs.h
+++ b/toys/e2fs.h
@@ -64,6 +64,17 @@ struct ext2_superblock {
 	uint32_t reserved[172];      // Padding to the end of the block
 };
 
+struct ext2_group
+{
+	uint32_t block_bitmap;       // Block number of block bitmap
+	uint32_t inode_bitmap;       // Block number of inode bitmap
+	uint32_t inode_table;        // Block number of inode table
+	uint16_t free_blocks_count;  // How many free blocks in this group?
+	uint16_t free_inodes_count;  // How many free inodes in this group?
+	uint16_t used_dirs_count;    // How many directories?
+	uint16_t reserved[7];        // pad to 256 bits.
+};
+
 struct ext2_dentry {
 	uint32_t inode;         // Inode number
     uint16_t rec_len;       // Directory entry length
diff --git a/toys/mke2fs.c b/toys/mke2fs.c
index 0c71da87..b50068a0 100644
--- a/toys/mke2fs.c
+++ b/toys/mke2fs.c
@@ -79,13 +79,11 @@ int mke2fs_main(void)
 	// Determine appropriate block size, set log_block_size and log_frag_size.
 
 	if (!TT.blocksize) TT.blocksize = (length && length < 1<<29) ? 1024 : 4096;
-	if (TT.blocksize == 1024) temp = 0;
-	else if (TT.blocksize == 2048) temp = 1;
-	else if (TT.blocksize == 4096) temp = 2;
-	else error_exit("bad blocksize");
+	for (temp = 0; temp < 7; temp++) if (TT.blocksize == 1024<<temp) break;
+	if (temp==7) error_exit("bad blocksize");
 	sb->log_block_size = sb->log_frag_size = SWAP_LE32(temp);
 
-	// Fill out blocks_count and r_blocks_count
+	// Fill out blocks_count, r_blocks_count, first_data_block
 
 	if (!TT.blocks) TT.blocks = length/TT.blocksize;
 	sb->blocks_count = SWAP_LE32(TT.blocks);
@@ -94,6 +92,8 @@ int mke2fs_main(void)
 	temp = (TT.blocks * (uint64_t)TT.reserved_percent) /100;
 	sb->r_blocks_count = SWAP_LE32(temp);
 
+	sb->first_data_block = TT.blocksize == 1024 ? 1 : 0;
+
 	// Set blocks_per_group and frags_per_group, which is the size of an
 	// allocation bitmap that fits in one block (I.E. how many bits per block)?