mkfs_ext2: further work by Vladimir
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/util-linux/mkfs_ext2.c b/util-linux/mkfs_ext2.c
index e840f78..da27dc7 100644
--- a/util-linux/mkfs_ext2.c
+++ b/util-linux/mkfs_ext2.c
@@ -173,9 +173,9 @@
unsigned i, pos, n;
unsigned bs, bpi;
unsigned blocksize, blocksize_log2;
- unsigned nreserved = 5;
+ unsigned reserved_percent = 5;
unsigned long long kilobytes;
- uint32_t nblocks, nblocks_full;
+ uint32_t nblocks, nblocks_full, nreserved;
uint32_t ngroups;
uint32_t bytes_per_inode;
uint32_t first_data_block;
@@ -194,13 +194,9 @@
opt_complementary = "-1:b+:m+:i+";
opts = getopt32(argv, "cl:b:f:i:I:J:G:N:m:o:g:L:M:O:r:E:T:U:jnqvFS",
NULL, &bs, NULL, &bpi, NULL, NULL, NULL, NULL,
- &nreserved, NULL, NULL, &label, NULL, NULL, NULL, NULL, NULL, NULL);
+ &reserved_percent, NULL, NULL, &label, NULL, NULL, NULL, NULL, NULL, NULL);
argv += optind; // argv[0] -- device
- // reserved blocks percentage
- if (nreserved > 50)
- bb_error_msg_and_die("-%c is bad", 'm');
-
// check the device is a block device
xmove_fd(xopen(argv[0], O_WRONLY), fd);
fstat(fd, &st);
@@ -228,14 +224,15 @@
if (opts & OPT_i)
bytes_per_inode = bpi;
+ // Determine block size
// block size is a multiple of 1024
blocksize = 1024;
if (kilobytes >= 512*1024) // mke2fs 1.41.9 compat
blocksize = 4096;
if (EXT2_MAX_BLOCK_SIZE > 4096) {
// kilobytes >> 22 == size in 4gigabyte chunks.
- // if it is >= 16k gigs, blocksize must be increased.
- // Try "mke2fs -F image_std $((16 * 1024*1024*1024))"
+ // if size >= 16k gigs, blocksize must be increased.
+ // Try "mke2fs -F image $((16 * 1024*1024*1024))"
while ((kilobytes >> 22) >= blocksize)
blocksize *= 2;
}
@@ -247,28 +244,38 @@
) {
bb_error_msg_and_die("blocksize %u is bad", blocksize);
}
+ // number of bits in one block, i.e. 8*blocksize
+#define blocks_per_group (8 * blocksize)
+ first_data_block = (EXT2_MIN_BLOCK_SIZE == blocksize);
blocksize_log2 = int_log2(blocksize);
+
+ // Determine number of blocks
kilobytes >>= (blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE);
- // nblocks: the total number of blocks in the filesystem
nblocks = kilobytes;
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)-1);
+ 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");
+
+ // How many reserved blocks?
+ if (reserved_percent > 50)
+ bb_error_msg_and_die("-%c is bad", 'm');
+ //nreserved = div_roundup((uint64_t) nblocks * reserved_percent, 100);
+ nreserved = (uint64_t)nblocks * reserved_percent / 100;
// N.B. killing e2fsprogs feature! Unused blocks don't account in calculations
nblocks_full = nblocks;
+
+ // If last block group is too small, nblocks may be decreased in order
+ // to discard it, and control returns here to recalculate some
+ // parameters.
+ // Note: blocksize and bytes_per_inode are never recalculated.
retry:
- if (nblocks < 8)
- bb_error_msg_and_die("need >= 8 blocks");
-
- // number of bits in one block, i.e. 8*blocksize
-#define blocks_per_group (8 * blocksize)
-
// N.B. a block group can have no more than blocks_per_group blocks
- first_data_block = (EXT2_MIN_BLOCK_SIZE == blocksize);
ngroups = div_roundup(nblocks - first_data_block, blocks_per_group);
if (0 == ngroups)
bb_error_msg_and_die("ngroups");
@@ -308,21 +315,21 @@
if (inodes_per_group < 16)
inodes_per_group = 16;
- // N.B. a block group can have no more than 8*blocksize inodes
+ // a block group can have no more than 8*blocksize inodes
if (inodes_per_group > blocks_per_group)
inodes_per_group = blocks_per_group;
// adjust inodes per group so they completely fill the inode table blocks in the descriptor
- inodes_per_group = (div_roundup(inodes_per_group * sizeof(*inode), blocksize) << blocksize_log2) / sizeof(*inode);
+ inodes_per_group = (div_roundup(inodes_per_group * sizeof(*inode), blocksize) * blocksize) / sizeof(*inode);
// make sure the number of inodes per group is a multiple of 8
inodes_per_group &= ~7;
itsz = div_roundup(inodes_per_group * sizeof(*inode), blocksize);
- // the last block needs more attention: doesn't it too small for possible overhead?
+ // the last group needs more attention: isn't it too small for possible overhead?
overhead = (has_super(ngroups - 1) ? (1/*sb*/ + gdtsz) : 0) + 1/*bbmp*/ + 1/*ibmp*/ + itsz;
remainder = (nblocks - first_data_block) % blocks_per_group;
if ((1 == ngroups) && remainder && (remainder < overhead))
bb_error_msg_and_die("way small device");
- if (remainder && (remainder < overhead + 50)) {
+ if (remainder && (remainder < overhead + 50/* e2fsprogs hardcoded */)) {
//bb_info_msg("CHOP[%u]", remainder);
nblocks -= remainder;
goto retry;
@@ -348,8 +355,7 @@
, blocksize, blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE
, blocksize, blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE
, inodes_per_group * ngroups, nblocks
- //, div_roundup((uint64_t) nblocks * nreserved, 100), nreserved
- , (unsigned)((uint64_t) nblocks_full * nreserved / 100), nreserved
+ , nreserved, reserved_percent
, first_data_block
, gdtsz * (blocksize / sizeof(*gd)) * blocks_per_group
, ngroups
@@ -399,7 +405,7 @@
// blocks
STORE_LE(sb->s_blocks_count, nblocks);
// reserve blocks for superuser
- STORE_LE(sb->s_r_blocks_count, (uint32_t)((uint64_t) nblocks_full * nreserved / 100));
+ STORE_LE(sb->s_r_blocks_count, nreserved);
// ninodes
STORE_LE(sb->s_inodes_per_group, inodes_per_group);
STORE_LE(sb->s_inodes_count, inodes_per_group * ngroups);
@@ -418,7 +424,7 @@
| (EXT2_FEATURE_COMPAT_RESIZE_INO * ENABLE_FEATURE_MKFS_EXT2_RESERVED_GDT)
| (EXT2_FEATURE_COMPAT_DIR_INDEX * ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX)
);
- // e2fsprogs-1.41.9 doesn't like EXT2_FEATURE_INCOMPAT_WHITEOUT
+ // e2fsck from 1.41.9 doesn't like EXT2_FEATURE_INCOMPAT_WHITEOUT
STORE_LE(sb->s_feature_incompat, EXT2_FEATURE_INCOMPAT_FILETYPE);// | EXT2_FEATURE_INCOMPAT_WHITEOUT;
STORE_LE(sb->s_feature_ro_compat, EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER);
STORE_LE(sb->s_flags, EXT2_FLAGS_SIGNED_HASH * ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX);
@@ -435,9 +441,8 @@
STORE_LE(sb->s_max_mnt_count, EXT2_DFL_MAX_MNT_COUNT
+ (sb->s_uuid[ARRAY_SIZE(sb->s_uuid)-1] % EXT2_DFL_MAX_MNT_COUNT));
- // write the label, if any
- if (label) //opts & OPT_L)
- safe_strncpy((char *)sb->s_volume_name, label, sizeof(sb->s_volume_name));
+ // write the label
+ safe_strncpy((char *)sb->s_volume_name, label, sizeof(sb->s_volume_name));
// fill group descriptors
gd = xzalloc(gdtsz * blocksize);
@@ -461,11 +466,6 @@
STORE_LE(gd[i].bg_used_dirs_count, 2);
gd[i].bg_free_inodes_count -= EXT2_GOOD_OLD_FIRST_INO;
}
-// // N.B. the following is pure heuristics!
-// // Likely to cope with 1024-byte blocks, when first block is for boot sectors
-// if (ngroups-1 == i) {
-// n -= first_data_block;
-// }
// mark preallocated blocks as allocated
fb = (n < blocks_per_group ? n : blocks_per_group) - overhead;
@@ -500,8 +500,8 @@
// dump superblock and group descriptors and their backups
if (has_super(i)) {
// N.B. 1024 byte blocks are special
- PUT(((uint64_t)pos << blocksize_log2) + ((0 == i && 0 == first_data_block) ? 1024 : 0), sb, 1024);//blocksize);
- PUT(((uint64_t)pos << blocksize_log2) + blocksize, gd, gdtsz * blocksize);
+ PUT(((uint64_t)pos * blocksize) + ((0 == i && 0 == first_data_block) ? 1024 : 0), sb, 1024);//blocksize);
+ PUT(((uint64_t)pos * blocksize) + blocksize, gd, gdtsz * blocksize);
}
}
@@ -526,12 +526,12 @@
// dump root dir inode
STORE_LE(inode->i_links_count, 3); // "/.", "/..", "/lost+found/.." point to this inode
STORE_LE(inode->i_block[0], FETCH_LE32(gd[0].bg_inode_table) + itsz);
- PUT(((uint64_t)FETCH_LE32(gd[0].bg_inode_table) << blocksize_log2) + (EXT2_ROOT_INO-1) * sizeof(*inode), buf, sizeof(*inode));
+ PUT(((uint64_t)FETCH_LE32(gd[0].bg_inode_table) * blocksize) + (EXT2_ROOT_INO-1) * sizeof(*inode), buf, sizeof(*inode));
// dump lost+found dir inode
STORE_LE(inode->i_links_count, 2); // both "/lost+found" and "/lost+found/." point to this inode
STORE_LE(inode->i_block[0], inode->i_block[0]+1); // use next block
- PUT(((uint64_t)FETCH_LE32(gd[0].bg_inode_table) << blocksize_log2) + (EXT2_GOOD_OLD_FIRST_INO-1) * sizeof(*inode), buf, sizeof(*inode));
+ PUT(((uint64_t)FETCH_LE32(gd[0].bg_inode_table) * blocksize) + (EXT2_GOOD_OLD_FIRST_INO-1) * sizeof(*inode), buf, sizeof(*inode));
// dump directories
memset(buf, 0, blocksize);
diff --git a/util-linux/mkfs_ext2_test.sh b/util-linux/mkfs_ext2_test.sh
index 9c20b3b..53f15d2 100755
--- a/util-linux/mkfs_ext2_test.sh
+++ b/util-linux/mkfs_ext2_test.sh
@@ -23,7 +23,7 @@
test_mke2fs() {
echo Testing $kilobytes
- run_test '/usr/bin/mke2fs' image_std || return 1
+ run_test '/sbin/mke2fs' image_std || return 1
run_test './busybox mke2fs' image_bb || return 1
diff -ua image_bb.out image_std.out >image.out.diff || {
@@ -31,9 +31,33 @@
return 1
}
- e2fsck -f -n image_bb >/dev/null 2>&1 || { echo "e2fsck error on image_bb"; exit 1; }
+ e2fsck -f -n image_bb >/dev/null 2>&1 || {
+ echo "e2fsck error on image_bb"
+ e2fsck -f -n image_bb
+ exit 1
+ }
}
+# Should start from kilobytes=60, but e2fsck complains on it:
+# e2fsck 1.41.4 (27-Jan-2009)
+# Pass 1: Checking inodes, blocks, and sizes
+# Pass 2: Checking directory structure
+# Pass 3: Checking directory connectivity
+# Pass 4: Checking reference counts
+# Pass 5: Checking group summary information
+# Inode bitmap differences: +(9--11)
+# Free inodes count wrong for group #0 (5, counted=8).
+# Directories count wrong for group #0 (2, counted=1).
+# Free inodes count wrong (5, counted=8).
+# image_bb: 11/16 files (0.0% non-contiguous), 9/60 blocks
+kilobytes=68
+while true; do
+ test_mke2fs #|| exit 1
+ : $((kilobytes++))
+done
+exit
+
+# Specific sizes with known differences:
# -:bbox +:standard
# -6240 inodes, 24908 blocks
@@ -58,14 +82,14 @@
# +2064 inodes per group
kilobytes=57696 test_mke2fs
-# This size results in "warning: 75 blocks unused"
-kilobytes=98380 test_mke2fs
-
# -warning: 239 blocks unused.
# +warning: 242 blocks unused.
kilobytes=49395 test_mke2fs
+## This size results in "warning: 75 blocks unused"
+#kilobytes=98380 test_mke2fs
+
while true; do
- kilobytes=$(( (RANDOM*RANDOM) % 1000000 + 2000))
+ kilobytes=$(( (RANDOM*RANDOM) % 1000000 + 60))
test_mke2fs || exit 1
done