ext4: calculate and verify block bitmap checksum
Compute and verify the checksum of the block bitmap; this checksum is
stored in the block group descriptor.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 4bbd07a..0a64e4d 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -174,6 +174,8 @@
ext4_free_inodes_set(sb, gdp, 0);
ext4_itable_unused_set(sb, gdp, 0);
memset(bh->b_data, 0xff, sb->s_blocksize);
+ ext4_block_bitmap_csum_set(sb, block_group, gdp, bh,
+ EXT4_BLOCKS_PER_GROUP(sb) / 8);
return;
}
memset(bh->b_data, 0, sb->s_blocksize);
@@ -210,6 +212,9 @@
*/
ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
sb->s_blocksize * 8, bh->b_data);
+ ext4_block_bitmap_csum_set(sb, block_group, gdp, bh,
+ EXT4_BLOCKS_PER_GROUP(sb) / 8);
+ gdp->bg_checksum = ext4_group_desc_csum(sbi, block_group, gdp);
}
/* Return the number of free blocks in a block group. It is used when
@@ -276,9 +281,9 @@
}
static int ext4_valid_block_bitmap(struct super_block *sb,
- struct ext4_group_desc *desc,
- unsigned int block_group,
- struct buffer_head *bh)
+ struct ext4_group_desc *desc,
+ unsigned int block_group,
+ struct buffer_head *bh)
{
ext4_grpblk_t offset;
ext4_grpblk_t next_zero_bit;
@@ -325,6 +330,23 @@
block_group, bitmap_blk);
return 0;
}
+
+void ext4_validate_block_bitmap(struct super_block *sb,
+ struct ext4_group_desc *desc,
+ unsigned int block_group,
+ struct buffer_head *bh)
+{
+ if (buffer_verified(bh))
+ return;
+
+ ext4_lock_group(sb, block_group);
+ if (ext4_valid_block_bitmap(sb, desc, block_group, bh) &&
+ ext4_block_bitmap_csum_verify(sb, block_group, desc, bh,
+ EXT4_BLOCKS_PER_GROUP(sb) / 8))
+ set_buffer_verified(bh);
+ ext4_unlock_group(sb, block_group);
+}
+
/**
* ext4_read_block_bitmap()
* @sb: super block
@@ -355,12 +377,12 @@
}
if (bitmap_uptodate(bh))
- return bh;
+ goto verify;
lock_buffer(bh);
if (bitmap_uptodate(bh)) {
unlock_buffer(bh);
- return bh;
+ goto verify;
}
ext4_lock_group(sb, block_group);
if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
@@ -379,7 +401,7 @@
*/
set_bitmap_uptodate(bh);
unlock_buffer(bh);
- return bh;
+ goto verify;
}
/*
* submit the buffer_head for reading
@@ -390,6 +412,9 @@
get_bh(bh);
submit_bh(READ, bh);
return bh;
+verify:
+ ext4_validate_block_bitmap(sb, desc, block_group, bh);
+ return bh;
}
/* Returns 0 on success, 1 on error */
@@ -412,7 +437,7 @@
}
clear_buffer_new(bh);
/* Panic or remount fs read-only if block bitmap is invalid */
- ext4_valid_block_bitmap(sb, desc, block_group, bh);
+ ext4_validate_block_bitmap(sb, desc, block_group, bh);
return 0;
}
diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
index 5813e7f..b319721 100644
--- a/fs/ext4/bitmap.c
+++ b/fs/ext4/bitmap.c
@@ -68,3 +68,47 @@
if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
}
+
+int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
+ struct ext4_group_desc *gdp,
+ struct buffer_head *bh, int sz)
+{
+ __u32 hi;
+ __u32 provided, calculated;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+ if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return 1;
+
+ provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
+ calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
+ if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
+ hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
+ provided |= (hi << 16);
+ } else
+ calculated &= 0xFFFF;
+
+ if (provided == calculated)
+ return 1;
+
+ ext4_error(sb, "Bad block bitmap checksum: block_group = %u", group);
+ return 0;
+}
+
+void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
+ struct ext4_group_desc *gdp,
+ struct buffer_head *bh, int sz)
+{
+ __u32 csum;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+ if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return;
+
+ csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
+ gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
+ if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
+ gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
+}
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 7f0ff88..7a4f160 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1857,8 +1857,18 @@
int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
struct ext4_group_desc *gdp,
struct buffer_head *bh, int sz);
+void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
+ struct ext4_group_desc *gdp,
+ struct buffer_head *bh, int sz);
+int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
+ struct ext4_group_desc *gdp,
+ struct buffer_head *bh, int sz);
/* balloc.c */
+extern void ext4_validate_block_bitmap(struct super_block *sb,
+ struct ext4_group_desc *desc,
+ unsigned int block_group,
+ struct buffer_head *bh);
extern unsigned int ext4_block_group(struct super_block *sb,
ext4_fsblk_t blocknr);
extern ext4_grpblk_t ext4_block_group_offset(struct super_block *sb,
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index fb897ec..a6383fc 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -753,6 +753,10 @@
gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
ext4_free_group_clusters_set(sb, gdp,
ext4_free_clusters_after_init(sb, group, gdp));
+ ext4_block_bitmap_csum_set(sb, group, gdp,
+ block_bitmap_bh,
+ EXT4_BLOCKS_PER_GROUP(sb) /
+ 8);
gdp->bg_checksum = ext4_group_desc_csum(sbi, group,
gdp);
}
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 99ab428..95a388f 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -788,7 +788,7 @@
int first_block;
struct super_block *sb;
struct buffer_head *bhs;
- struct buffer_head **bh;
+ struct buffer_head **bh = NULL;
struct inode *inode;
char *data;
char *bitmap;
@@ -2797,6 +2797,8 @@
}
len = ext4_free_group_clusters(sb, gdp) - ac->ac_b_ex.fe_len;
ext4_free_group_clusters_set(sb, gdp, len);
+ ext4_block_bitmap_csum_set(sb, ac->ac_b_ex.fe_group, gdp, bitmap_bh,
+ EXT4_BLOCKS_PER_GROUP(sb) / 8);
gdp->bg_checksum = ext4_group_desc_csum(sbi, ac->ac_b_ex.fe_group, gdp);
ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
@@ -4659,6 +4661,8 @@
ret = ext4_free_group_clusters(sb, gdp) + count_clusters;
ext4_free_group_clusters_set(sb, gdp, ret);
+ ext4_block_bitmap_csum_set(sb, block_group, gdp, bitmap_bh,
+ EXT4_BLOCKS_PER_GROUP(sb) / 8);
gdp->bg_checksum = ext4_group_desc_csum(sbi, block_group, gdp);
ext4_unlock_group(sb, block_group);
percpu_counter_add(&sbi->s_freeclusters_counter, count_clusters);
@@ -4803,6 +4807,8 @@
mb_free_blocks(NULL, &e4b, bit, count);
blk_free_count = blocks_freed + ext4_free_group_clusters(sb, desc);
ext4_free_group_clusters_set(sb, desc, blk_free_count);
+ ext4_block_bitmap_csum_set(sb, block_group, desc, bitmap_bh,
+ EXT4_BLOCKS_PER_GROUP(sb) / 8);
desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
ext4_unlock_group(sb, block_group);
percpu_counter_add(&sbi->s_freeclusters_counter,
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 7810cac..dc597e0 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1107,6 +1107,13 @@
EXT4_INODES_PER_GROUP(sb) / 8);
brelse(bh);
+ bh = ext4_get_bitmap(sb, group_data->block_bitmap);
+ if (!bh)
+ return -EIO;
+ ext4_block_bitmap_csum_set(sb, group, gdp, bh,
+ EXT4_BLOCKS_PER_GROUP(sb) / 8);
+ brelse(bh);
+
return 0;
}
