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authorDarrick J. Wong <djwong@us.ibm.com>2012-04-29 18:33:10 -0400
committerTheodore Ts'o <tytso@mit.edu>2012-04-29 18:33:10 -0400
commit41a246d1ff75a95d2be3191ca6e6db139dc0f430 (patch)
tree0b5150f476dd69726ffe7ea1ba83832c42b441be /fs/ext4/bitmap.c
parent814525f4df50a196464ce2c7abe91f693203060f (diff)
downloadlinux-41a246d1ff75a95d2be3191ca6e6db139dc0f430.tar.bz2
ext4: calculate and verify checksums for inode bitmaps
Compute and verify the checksum of the inode bitmap; the checkum 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.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
index fa3af81ac565..5813e7f2e2c6 100644
--- a/fs/ext4/bitmap.c
+++ b/fs/ext4/bitmap.c
@@ -29,3 +29,42 @@ unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars)
#endif /* EXT4FS_DEBUG */
+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)
+{
+ __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_inode_bitmap_csum_lo);
+ calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
+ if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
+ hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
+ provided |= (hi << 16);
+ } else
+ calculated &= 0xFFFF;
+
+ return provided == calculated;
+}
+
+void ext4_inode_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_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
+ if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
+ gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
+}