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ext4: calculate and verify block bitmap checksum

Bladeren bron 
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>
This commit is contained in:
Darrick J. Wong
2012-04-29 18:35:10 -04:00
gecommit door Theodore Ts'o
bovenliggende 41a246d1ff
commit fa77dcfafe
6 gewijzigde bestanden met toevoegingen van 104 en 8 verwijderingen
Download Patch-bestand Download Diff-bestand Expand all files Collapse all files

39
fs/ext4/balloc.c
Bestand weergeven

@@ -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;
}