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-rw-r--r--toys/mke2fs.c38
1 files changed, 26 insertions, 12 deletions
diff --git a/toys/mke2fs.c b/toys/mke2fs.c
index 464b8b50..0c71da87 100644
--- 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);