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 (file)
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -174,6 +174,8 @@ void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
                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 @@ void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
         */
        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 @@ struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 }
 
 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 @@ err_out:
                        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 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
        }
 
        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 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
                 */
                set_bitmap_uptodate(bh);
                unlock_buffer(bh);
-               return bh;
+               goto verify;
        }
        /*
         * submit the buffer_head for reading
@@ -390,6 +412,9 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
        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 @@ int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
        }
        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 (file)
--- 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);
+}

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 7f0ff88..7a4f160 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1857,8 +1857,18 @@ void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
 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 (file)
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -753,6 +753,10 @@ got:
                        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 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -788,7 +788,7 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
        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 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
        }
        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 @@ do_more:
 
        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 @@ int ext4_group_add_blocks(handle_t *handle, struct super_block *sb,
        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 (file)
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1107,6 +1107,13 @@ static int ext4_set_bitmap_checksums(struct super_block *sb,
                                   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;
 }