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authorDarrick J. Wong <djwong@us.ibm.com>2012-04-29 18:35:10 -0400
committerTheodore Ts'o <tytso@mit.edu>2012-04-29 18:35:10 -0400
commitfa77dcfafeaa6bc73293c646bfc3d5192dcf0be2 (patch)
tree66c4232c2e5c1f59666e05164b77539a9b1dd290 /fs/ext4/bitmap.c
parent41a246d1ff75a95d2be3191ca6e6db139dc0f430 (diff)
downloadblackbird-op-linux-fa77dcfafeaa6bc73293c646bfc3d5192dcf0be2.tar.gz
blackbird-op-linux-fa77dcfafeaa6bc73293c646bfc3d5192dcf0be2.zip
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>
Diffstat (limited to 'fs/ext4/bitmap.c')
-rw-r--r--fs/ext4/bitmap.c44
1 files changed, 44 insertions, 0 deletions
diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
index 5813e7f2e2c6..b319721da26a 100644
--- a/fs/ext4/bitmap.c
+++ b/fs/ext4/bitmap.c
@@ -68,3 +68,47 @@ void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
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);
+}
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