Filling out most of the ext2 superblock correctly now.

diff --git a/toys/mke2fs.c b/toys/mke2fs.c
index 464b8b5..0c71da8 100644 (file)
--- a/toys/mke2fs.c
+++ b/toys/mke2fs.c
@@ -85,17 +85,11 @@ int mke2fs_main(void)
        else error_exit("bad blocksize");
        sb->log_block_size = sb->log_frag_size = SWAP_LE32(temp);
 
-       // Fill out blocks_count, inodes_count, r_blocks_count
+       // Fill out blocks_count and r_blocks_count
 
        if (!TT.blocks) TT.blocks = length/TT.blocksize;
        sb->blocks_count = SWAP_LE32(TT.blocks);
 
-       if (!TT.inodes) {
-               if (!TT.bytes_per_inode) TT.bytes_per_inode = 8192;
-               TT.inodes = (TT.blocks * (uint64_t)TT.blocksize) / TT.bytes_per_inode;
-       }
-       sb->inodes_count = SWAP_LE32(TT.inodes);
-
        if (!TT.reserved_percent) TT.reserved_percent = 5;
        temp = (TT.blocks * (uint64_t)TT.reserved_percent) /100;
        sb->r_blocks_count = SWAP_LE32(temp);
@@ -106,14 +100,34 @@ int mke2fs_main(void)
        temp = TT.blocksize*8;
        sb->blocks_per_group = sb->frags_per_group = SWAP_LE32(temp);
 
-       // Set inodes_per_group
+       // How many block groups do we need?  (Round up avoiding integer overflow.)
 
        TT.groups = (TT.blocks)/temp;
-       if (TT.blocks & (temp-1)) TT.groups++;  // Round up without int overflow.
-       temp = TT.inodes/TT.groups;
-       if (TT.blocks & (TT.groups-1)) TT.blocks++;
-       sb->inodes_per_group = SWAP_LE32(temp);
+       if (TT.blocks & (temp-1)) TT.groups++;
+
+       // Figure out how many inodes we need.
+
+       if (!TT.inodes) {
+               if (!TT.bytes_per_inode) TT.bytes_per_inode = 8192;
+               TT.inodes = (TT.blocks * (uint64_t)TT.blocksize) / TT.bytes_per_inode;
+       }
+
+       // Figure out inodes per group, rounded up to block size.
+
+       // How many blocks of inodes total, rounded up
+       temp = TT.inodes / (TT.blocksize/sizeof(struct ext2_inode));
+       if (TT.inodes & (TT.blocksize-1)) temp++;
+       // How many blocks of inodes per group, again rounded up
+       TT.inodes = temp / TT.groups;
+       if (temp & (TT.groups-1)) TT.inodes++;
+       // How many inodes per group is that?
+       TT.inodes *=  (TT.blocksize/sizeof(struct ext2_inode));
+
+       // Set inodes_per_group and total inodes_count
+       sb->inodes_per_group = SWAP_LE32(TT.inodes);
+       sb->inodes_count = SWAP_LE32(TT.inodes *= TT.groups);
 
+       // Fill out the rest of the superblock.
        sb->max_mnt_count=0xFFFF;
        sb->wtime = sb->lastcheck = sb->mkfs_time = SWAP_LE32(time(NULL));
        sb->magic = SWAP_LE32(0xEF53);