mkfs_ext2: fixes for small image generation. images up to ~8M are ok now

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

util-linux/mkfs_ext2.c

@@ -256,8 +256,9 @@ int mkfs_ext2_main(int argc UNUSED_PARAM, char **argv)
 	if (nblocks != kilobytes)
 		bb_error_msg_and_die("block count doesn't fit in 32 bits");
 #define kilobytes kilobytes_unused_after_this
-	if (blocksize < PAGE_SIZE)
-		nblocks &= ~((PAGE_SIZE >> blocksize_log2)-1);
+//compat problem
+//	if (blocksize < PAGE_SIZE)
+//		nblocks &= ~((PAGE_SIZE >> blocksize_log2)-1);
 	// Experimentally, standard mke2fs won't work on images smaller than 60k
 	if (nblocks < 60)
 		bb_error_msg_and_die("need >= 60 blocks");
@@ -307,7 +308,7 @@ int mkfs_ext2_main(int argc UNUSED_PARAM, char **argv)
 	{
 		// N.B. e2fsprogs does as follows!
 		// ninodes is the total number of inodes (files) in the file system
-		uint32_t ninodes = nblocks_full / (blocksize >= 4096 ? 1 : 4096 / blocksize);
+		uint32_t ninodes = ((uint64_t) nblocks_full * blocksize) / bytes_per_inode;
 		uint32_t overhead, remainder;
 		if (ninodes < EXT2_GOOD_OLD_FIRST_INO+1)
 			ninodes = EXT2_GOOD_OLD_FIRST_INO+1;

util-linux/mkfs_ext2_test.sh

@@ -1,9 +1,15 @@
 #!/bin/sh
 
-run_test() { # params: mke2fs_invocation image_name
+system_mke2fs='/sbin/mke2fs'
+bbox_mke2fs='./busybox mke2fs'
+
+gen_image() { # params: mke2fs_invocation image_name
     >$2
     dd seek=$((kilobytes-1)) bs=1K count=1 </dev/zero of=$2 >/dev/null 2>&1 || exit 1
     $1 -F $2 $kilobytes >$2.raw_out 2>&1 || return 1
+
+#off    | sed 's/inodes, [0-9]* blocks/inodes, N blocks/' \
+
     cat $2.raw_out \
     | grep -v '^mke2fs [0-9]*\.[0-9]*\.[0-9]* ' \
     | grep -v '^Maximum filesystem' \
@@ -11,7 +17,6 @@ run_test() { # params: mke2fs_invocation image_name
     | grep -v '^Writing superblocks and filesystem accounting information' \
     | grep -v '^This filesystem will be automatically checked every' \
     | grep -v '^180 days, whichever comes first' \
-    | sed 's/inodes, [0-9]* blocks/inodes, N blocks/' \
     | sed 's/blocks* unused./blocks unused/' \
     | sed 's/block groups*/block groups/' \
     | sed 's/ *$//' \
@@ -23,32 +28,52 @@ run_test() { # params: mke2fs_invocation image_name
 test_mke2fs() {
     echo Testing $kilobytes
 
-    run_test '/sbin/mke2fs' image_std || return 1
-    run_test './busybox mke2fs' image_bb || return 1
+    gen_image "$system_mke2fs" image_std || return 1
+    gen_image "$bbox_mke2fs"   image_bb  || return 1
 
     diff -ua image_bb.out image_std.out >image.out.diff || {
 	cat image.out.diff
 	return 1
     }
 
-    e2fsck -f -n image_bb >/dev/null 2>&1 || {
+    e2fsck -f -n image_bb >image_bb_e2fsck.out 2>&1 || {
 	echo "e2fsck error on image_bb"
-	e2fsck -f -n image_bb
+	cat image_bb_e2fsck.out
 	exit 1
     }
 }
 
-# kilobytes=60 is the minimal allowed size
+# -:bbox +:standard
+
+# kilobytes=60 is the minimal allowed size.
+#
+# kilobytes=8378 is the first value where we differ from std:
+# +warning: 185 blocks unused
+#  Filesystem label=
+#  OS type: Linux
+#  Block size=1024 (log=0)
+#  Fragment size=1024 (log=0)
+# -2096 inodes, 8378 blocks
+# +2096 inodes, 8193 blocks
+#  418 blocks reserved for the super user
+#  First data block=1
+# -2 block groups
+# +1 block groups
+#  8192 blocks per group, 8192 fragments per group
+# -1048 inodes per group
+# -Superblock backups stored on blocks:
+# -8193
+# +2096 inodes per group
+#
 kilobytes=60
 while true; do
-    test_mke2fs #|| exit 1
+    test_mke2fs || exit 1
     : $((kilobytes++))
-    test $kilobytes = 200 && break
+    test $kilobytes = 300000 && break
 done
 exit
 
 # Specific sizes with known differences:
-# -:bbox +:standard
 
 # -6240 inodes, 24908 blocks
 # +6240 inodes, 24577 blocks