These helper functions will be used to calculate and verify the block and inode
bitmap checksums.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
fs/ext4/bitmap.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
fs/ext4/ext4.h | 6 ++++++
2 files changed, 50 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
index fa3af81..5421152 100644
--- a/fs/ext4/bitmap.c
+++ b/fs/ext4/bitmap.c
@@ -9,6 +9,7 @@
#include <linux/buffer_head.h>
#include <linux/jbd2.h>
+#include <linux/crc32c.h>
#include "ext4.h"
#ifdef EXT4FS_DEBUG
@@ -29,3 +30,46 @@ unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars)
#endif /* EXT4FS_DEBUG */
+__le32 ext4_bitmap_csum(struct super_block *sb, ext4_group_t group,
+ struct buffer_head *bh, int sz)
+{
+ __le32 crc;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+ if (sbi->s_desc_size < EXT4_MIN_DESC_SIZE_64BIT)
+ return 0;
+ if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return 0;
+
+ group = cpu_to_le32(group);
+ crc = crc32c_le(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid));
+ crc = crc32c_le(crc, (__u8 *)&group, sizeof(group));
+ crc = crc32c_le(crc, (__u8 *)bh->b_data, sz);
+
+ return cpu_to_le32(crc);
+}
+
+int ext4_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
+ __le32 provided, struct buffer_head *bh, int sz)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+ if (sbi->s_desc_size >= EXT4_MIN_DESC_SIZE_64BIT &&
+ EXT4_HAS_RO_COMPAT_FEATURE(sb,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
+ (provided != ext4_bitmap_csum(sb, group, bh, sz)))
+ return 0;
+ return 1;
+}
+
+void ext4_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
+ __le32 *csum, struct buffer_head *bh, int sz)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+ if (sbi->s_desc_size >= EXT4_MIN_DESC_SIZE_64BIT &&
+ EXT4_HAS_RO_COMPAT_FEATURE(sb,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ *csum = ext4_bitmap_csum(sb, group, bh, sz);
+}
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index e2361cc..bc7ace1 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1722,6 +1722,12 @@ struct mmpd_data {
/* bitmap.c */
extern unsigned int ext4_count_free(struct buffer_head *, unsigned);
+__le32 ext4_bitmap_csum(struct super_block *sb, ext4_group_t group,
+ struct buffer_head *bh, int sz);
+int ext4_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
+ __le32 provided, struct buffer_head *bh, int sz);
+void ext4_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
+ __le32 *csum, struct buffer_head *bh, int sz);
/* balloc.c */
extern unsigned int ext4_block_group(struct super_block *sb,
--
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