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Commit fa77dcfa authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Theodore Ts'o
Browse files

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: default avatarDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 41a246d1

fs/ext4/balloc.c

+32 −7
Original line number Diff line number Diff line
@@ -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
@@ -325,6 +330,23 @@ static int ext4_valid_block_bitmap(struct super_block *sb, 
			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;

}

fs/ext4/bitmap.c

+44 −0
Original line number Diff line number Diff line
@@ -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);

}

fs/ext4/ext4.h

+10 −0
Original line number Diff line number Diff line
@@ -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,

fs/ext4/ialloc.c

+4 −0
Original line number Diff line number Diff line
@@ -753,6 +753,10 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode *dir, umode_t mode, 
			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);

		}

fs/ext4/mballoc.c

+7 −1
Original line number Diff line number Diff line
@@ -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 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode, 


	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,