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Subject[PATCH 15/28] ext4: Calculate and verify block bitmap checksum
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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>
---
fs/ext4/balloc.c | 40 +++++++++++++++++++++------
fs/ext4/bitmap.c | 40 +++++++++++++++++++++++++++
fs/ext4/ext4.h | 10 +++++++
fs/ext4/ialloc.c | 4 +++
fs/ext4/mballoc.c | 78 +++++++++++++++++++++++++++++++++++++++++++++--------
5 files changed, 151 insertions(+), 21 deletions(-)

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index f8224ad..dd96a7d 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -105,6 +105,9 @@ unsigned 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 0;
}
memset(bh->b_data, 0, sb->s_blocksize);
@@ -175,6 +178,10 @@ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
*/
ext4_mark_bitmap_end(group_blocks, 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 free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp);
}
@@ -232,10 +239,10 @@ struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
return desc;
}

-static int ext4_valid_block_bitmap(struct super_block *sb,
- struct ext4_group_desc *desc,
- unsigned int block_group,
- struct buffer_head *bh)
+int ext4_valid_block_bitmap(struct super_block *sb,
+ struct ext4_group_desc *desc,
+ unsigned int block_group,
+ struct buffer_head *bh)
{
ext4_grpblk_t offset;
ext4_grpblk_t next_zero_bit;
@@ -312,12 +319,12 @@ ext4_read_block_bitmap(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)) {
@@ -336,7 +343,7 @@ ext4_read_block_bitmap(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 read. We can
@@ -353,11 +360,26 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
block_group, bitmap_blk);
return NULL;
}
- ext4_valid_block_bitmap(sb, desc, block_group, bh);
+
+verify:
+ if (buffer_verified(bh))
+ return bh;
/*
* file system mounted not to panic on error,
- * continue with corrupt bitmap
+ * -EIO with corrupt bitmap
*/
+ 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)) {
+ ext4_unlock_group(sb, block_group);
+ put_bh(bh);
+ ext4_error(sb, "Corrupt block bitmap - block_group = %u, "
+ "block_bitmap = %llu", block_group, bitmap_blk);
+ return NULL;
+ }
+ ext4_unlock_group(sb, block_group);
+ set_buffer_verified(bh);
return bh;
}

diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
index e9342f6..00ebc7a 100644
--- a/fs/ext4/bitmap.c
+++ b/fs/ext4/bitmap.c
@@ -81,3 +81,43 @@ 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_LOCATION)
gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(crc >> 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_bitmap_csum(sb, group, bh, sz);
+ if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION) {
+ hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
+ provided |= (hi << 16);
+ } else
+ calculated &= 0xFFFF;
+
+ return provided == calculated;
+}
+
+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 crc;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+ if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return;
+
+ crc = ext4_bitmap_csum(sb, group, bh, sz);
+ gdp->bg_block_bitmap_csum_lo = cpu_to_le16(crc & 0xFFFF);
+ if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
+ gdp->bg_block_bitmap_csum_hi = cpu_to_le16(crc >> 16);
+}
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index c98bc9f..7cd3541 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1776,8 +1776,18 @@ 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 int ext4_valid_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 6fb00e7..77ae3df 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -981,6 +981,10 @@ got:
free = ext4_free_blocks_after_init(sb, group, gdp);
gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
ext4_free_blks_set(sb, gdp, free);
+ 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 17a5a57..3d6300a 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -753,6 +753,44 @@ void ext4_mb_generate_buddy(struct super_block *sb,
spin_unlock(&EXT4_SB(sb)->s_bal_lock);
}

+struct ext4_csum_data {
+ struct super_block *cd_sb;
+ ext4_group_t cd_group;
+};
+
+static void ext4_end_buffer_read_sync(struct buffer_head *bh, int uptodate)
+{
+ struct ext4_group_desc *desc;
+ struct super_block *sb =
+ ((struct ext4_csum_data *)bh->b_private)->cd_sb;
+ ext4_group_t group = ((struct ext4_csum_data *)bh->b_private)->cd_group;
+
+ if (!uptodate)
+ goto out;
+
+ desc = ext4_get_group_desc(sb, group, NULL);
+ if (!desc)
+ goto out;
+
+ if (buffer_verified(bh))
+ goto out;
+
+ ext4_lock_group(sb, group);
+ if (!ext4_valid_block_bitmap(sb, desc, group, bh) ||
+ !ext4_block_bitmap_csum_verify(sb, group, desc, bh,
+ EXT4_BLOCKS_PER_GROUP(sb) / 8)) {
+ ext4_unlock_group(sb, group);
+ ext4_error(sb, "Corrupt block bitmap, group = %u", group);
+ goto out;
+ }
+ ext4_unlock_group(sb, group);
+ set_buffer_verified(bh);
+
+out:
+ bh->b_private = NULL;
+ end_buffer_read_sync(bh, uptodate);
+}
+
/* The buddy information is attached the buddy cache inode
* for convenience. The information regarding each group
* is loaded via ext4_mb_load_buddy. The information involve
@@ -785,11 +823,12 @@ 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;
struct ext4_group_info *grinfo;
+ struct ext4_csum_data *csd;

mb_debug(1, "init page %lu\n", page->index);

@@ -803,6 +842,11 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
if (groups_per_page == 0)
groups_per_page = 1;

+ csd = kzalloc(sizeof(struct ext4_csum_data) * groups_per_page,
+ GFP_NOFS);
+ if (csd == NULL)
+ goto out;
+
/* allocate buffer_heads to read bitmaps */
if (groups_per_page > 1) {
err = -ENOMEM;
@@ -880,22 +924,25 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
* get set with buffer lock held.
*/
set_bitmap_uptodate(bh[i]);
- bh[i]->b_end_io = end_buffer_read_sync;
+ csd[i].cd_sb = sb;
+ csd[i].cd_group = first_group + i;
+ bh[i]->b_private = csd + i;
+ bh[i]->b_end_io = ext4_end_buffer_read_sync;
submit_bh(READ, bh[i]);
mb_debug(1, "read bitmap for group %u\n", first_group + i);
}

- /* wait for I/O completion */
- for (i = 0; i < groups_per_page; i++)
- if (bh[i])
- wait_on_buffer(bh[i]);
-
- err = -EIO;
- for (i = 0; i < groups_per_page; i++)
- if (bh[i] && !buffer_uptodate(bh[i]))
- goto out;
-
+ /* Wait for I/O completion and checksum verification */
err = 0;
+ for (i = 0; i < groups_per_page; i++) {
+ if (bh[i] == NULL)
+ continue;
+ wait_on_buffer(bh[i]);
+ if (!buffer_uptodate(bh[i]) ||
+ !buffer_verified(bh[i]))
+ err = -EIO;
+ }
+
first_block = page->index * blocks_per_page;
for (i = 0; i < blocks_per_page; i++) {
int group;
@@ -972,6 +1019,7 @@ out:
if (bh != &bhs)
kfree(bh);
}
+ kfree(csd);
return err;
}

@@ -2829,6 +2877,8 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
}
len = ext4_free_blks_count(sb, gdp) - ac->ac_b_ex.fe_len;
ext4_free_blks_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);
@@ -4638,6 +4688,8 @@ do_more:

ret = ext4_free_blks_count(sb, gdp) + count;
ext4_free_blks_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_freeblocks_counter, count);
@@ -4780,6 +4832,8 @@ 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_blks_count(sb, desc);
ext4_free_blks_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_freeblocks_counter, blocks_freed);


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