Correctly calculate tot_used_blocks on ext4 with uninit_bg
The calculated number of blocks to encrypt is too high on ext4
filesystems that have the uninit_bg feature. This is because the
calculation assumes that all blocks not counted in bg_free_blocks_count
need to encrypted. But actually, uninitialized block groups have inode
blocks which vold doesn't encrypt since they are uninitialized, but they
are "allocated" and thus reduce bg_free_blocks_count.
Therefore, add a helper function num_base_meta_blocks_in_group() which
returns the number of blocks to encrypt in an uninitialized block group.
Use it both for the encryption and for calculating 'tot_used_blocks'.
Also compute 'tot_used_blocks' additively rather than subtractively, as
this is easier to understand.
Test: see I08fc8465f7962abd698904b5466f3ed080d53953
Change-Id: I4d2cb40291da67dd1bafd61289ccb9e6343bfda3
diff --git a/EncryptInplace.cpp b/EncryptInplace.cpp
index eb7d4c3..471daef 100644
--- a/EncryptInplace.cpp
+++ b/EncryptInplace.cpp
@@ -155,6 +155,22 @@
return 0;
}
+static uint64_t first_block_in_group(uint32_t group) {
+ return aux_info.first_data_block + (group * (uint64_t)info.blocks_per_group);
+}
+
+static uint32_t num_blocks_in_group(uint32_t group) {
+ uint64_t remaining = aux_info.len_blocks - first_block_in_group(group);
+ return std::min<uint64_t>(info.blocks_per_group, remaining);
+}
+
+// In block groups with an uninitialized block bitmap, we only need to encrypt
+// the backup superblock and the block group descriptors (if they are present).
+static uint32_t num_base_meta_blocks_in_group(uint64_t group) {
+ if (!ext4_bg_has_super_block(group)) return 0;
+ return 1 + aux_info.bg_desc_blocks;
+}
+
static int encrypt_groups(struct encryptGroupsData* data) {
unsigned int i;
u8* block_bitmap = 0;
@@ -177,8 +193,7 @@
for (i = 0; i < aux_info.groups; ++i) {
LOG(INFO) << "Encrypting group " << i;
- u32 first_block = aux_info.first_data_block + i * info.blocks_per_group;
- u32 block_count = std::min(info.blocks_per_group, (u32)(aux_info.len_blocks - first_block));
+ u32 block_count = num_blocks_in_group(i);
off64_t offset = (u64)info.block_size * aux_info.bg_desc[i].bg_block_bitmap;
@@ -188,20 +203,17 @@
goto errout;
}
- offset = (u64)info.block_size * first_block;
+ offset = (u64)info.block_size * first_block_in_group(i);
data->count = 0;
for (block = 0; block < block_count; block++) {
int used;
- if (aux_info.bg_desc[i].bg_flags & EXT4_BG_BLOCK_UNINIT) {
- // In block groups with an uninitialized block bitmap, we only
- // need to encrypt the backup superblock (if one is present).
- used = (ext4_bg_has_super_block(i) && block < 1 + aux_info.bg_desc_blocks);
- } else {
+ if (aux_info.bg_desc[i].bg_flags & EXT4_BG_BLOCK_UNINIT)
+ used = (block < num_base_meta_blocks_in_group(i));
+ else
used = bitmap_get_bit(block_bitmap, block);
- }
update_progress(data, used);
if (used) {
@@ -282,9 +294,13 @@
LOG(INFO) << "Encrypting ext4 filesystem in place...";
- data.tot_used_blocks = size / CRYPT_SECTORS_PER_BUFSIZE;
+ data.tot_used_blocks = 0;
for (i = 0; i < aux_info.groups; ++i) {
- data.tot_used_blocks -= aux_info.bg_desc[i].bg_free_blocks_count;
+ if (aux_info.bg_desc[i].bg_flags & EXT4_BG_BLOCK_UNINIT)
+ data.tot_used_blocks += num_base_meta_blocks_in_group(i);
+ else
+ data.tot_used_blocks +=
+ (num_blocks_in_group(i) - aux_info.bg_desc[i].bg_free_blocks_count);
}
data.one_pct = data.tot_used_blocks / 100;