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ocfs2: better group descriptor consistency checks
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Try to catch corrupted group descriptors with some stronger checks placed in
a couple of strategic locations. Detect a failed resizefs and refuse to
allocate past what bitmap i_clusters allows.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
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Mark Fasheh committed Aug 7, 2006
1 parent 101ebf2 commit 7bf72ed
Showing 1 changed file with 94 additions and 20 deletions.
114 changes: 94 additions & 20 deletions fs/ocfs2/suballoc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -85,11 +85,6 @@ static int ocfs2_claim_suballoc_bits(struct ocfs2_super *osb,
u64 *bg_blkno);
static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
int nr);
static int ocfs2_block_group_find_clear_bits(struct ocfs2_super *osb,
struct buffer_head *bg_bh,
unsigned int bits_wanted,
u16 *bit_off,
u16 *bits_found);
static inline int ocfs2_block_group_set_bits(struct ocfs2_journal_handle *handle,
struct inode *alloc_inode,
struct ocfs2_group_desc *bg,
Expand Down Expand Up @@ -143,6 +138,64 @@ static u32 ocfs2_bits_per_group(struct ocfs2_chain_list *cl)
return (u32)le16_to_cpu(cl->cl_cpg) * (u32)le16_to_cpu(cl->cl_bpc);
}

/* somewhat more expensive than our other checks, so use sparingly. */
static int ocfs2_check_group_descriptor(struct super_block *sb,
struct ocfs2_dinode *di,
struct ocfs2_group_desc *gd)
{
unsigned int max_bits;

if (!OCFS2_IS_VALID_GROUP_DESC(gd)) {
OCFS2_RO_ON_INVALID_GROUP_DESC(sb, gd);
return -EIO;
}

if (di->i_blkno != gd->bg_parent_dinode) {
ocfs2_error(sb, "Group descriptor # %llu has bad parent "
"pointer (%llu, expected %llu)",
(unsigned long long)le64_to_cpu(gd->bg_blkno),
(unsigned long long)le64_to_cpu(gd->bg_parent_dinode),
(unsigned long long)le64_to_cpu(di->i_blkno));
return -EIO;
}

max_bits = le16_to_cpu(di->id2.i_chain.cl_cpg) * le16_to_cpu(di->id2.i_chain.cl_bpc);
if (le16_to_cpu(gd->bg_bits) > max_bits) {
ocfs2_error(sb, "Group descriptor # %llu has bit count of %u",
(unsigned long long)le64_to_cpu(gd->bg_blkno),
le16_to_cpu(gd->bg_bits));
return -EIO;
}

if (le16_to_cpu(gd->bg_chain) >=
le16_to_cpu(di->id2.i_chain.cl_next_free_rec)) {
ocfs2_error(sb, "Group descriptor # %llu has bad chain %u",
(unsigned long long)le64_to_cpu(gd->bg_blkno),
le16_to_cpu(gd->bg_chain));
return -EIO;
}

if (le16_to_cpu(gd->bg_free_bits_count) > le16_to_cpu(gd->bg_bits)) {
ocfs2_error(sb, "Group descriptor # %llu has bit count %u but "
"claims that %u are free",
(unsigned long long)le64_to_cpu(gd->bg_blkno),
le16_to_cpu(gd->bg_bits),
le16_to_cpu(gd->bg_free_bits_count));
return -EIO;
}

if (le16_to_cpu(gd->bg_bits) > (8 * le16_to_cpu(gd->bg_size))) {
ocfs2_error(sb, "Group descriptor # %llu has bit count %u but "
"max bitmap bits of %u",
(unsigned long long)le64_to_cpu(gd->bg_blkno),
le16_to_cpu(gd->bg_bits),
8 * le16_to_cpu(gd->bg_size));
return -EIO;
}

return 0;
}

static int ocfs2_block_group_fill(struct ocfs2_journal_handle *handle,
struct inode *alloc_inode,
struct buffer_head *bg_bh,
Expand Down Expand Up @@ -663,6 +716,7 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
static int ocfs2_block_group_find_clear_bits(struct ocfs2_super *osb,
struct buffer_head *bg_bh,
unsigned int bits_wanted,
unsigned int total_bits,
u16 *bit_off,
u16 *bits_found)
{
Expand All @@ -679,10 +733,8 @@ static int ocfs2_block_group_find_clear_bits(struct ocfs2_super *osb,
found = start = best_offset = best_size = 0;
bitmap = bg->bg_bitmap;

while((offset = ocfs2_find_next_zero_bit(bitmap,
le16_to_cpu(bg->bg_bits),
start)) != -1) {
if (offset == le16_to_cpu(bg->bg_bits))
while((offset = ocfs2_find_next_zero_bit(bitmap, total_bits, start)) != -1) {
if (offset == total_bits)
break;

if (!ocfs2_test_bg_bit_allocatable(bg_bh, offset)) {
Expand Down Expand Up @@ -911,14 +963,35 @@ static int ocfs2_cluster_group_search(struct inode *inode,
{
int search = -ENOSPC;
int ret;
struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) group_bh->b_data;
struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *) group_bh->b_data;
u16 tmp_off, tmp_found;
unsigned int max_bits, gd_cluster_off;

BUG_ON(!ocfs2_is_cluster_bitmap(inode));

if (bg->bg_free_bits_count) {
if (gd->bg_free_bits_count) {
max_bits = le16_to_cpu(gd->bg_bits);

/* Tail groups in cluster bitmaps which aren't cpg
* aligned are prone to partial extention by a failed
* fs resize. If the file system resize never got to
* update the dinode cluster count, then we don't want
* to trust any clusters past it, regardless of what
* the group descriptor says. */
gd_cluster_off = ocfs2_blocks_to_clusters(inode->i_sb,
le64_to_cpu(gd->bg_blkno));
if ((gd_cluster_off + max_bits) >
OCFS2_I(inode)->ip_clusters) {
max_bits = OCFS2_I(inode)->ip_clusters - gd_cluster_off;
mlog(0, "Desc %llu, bg_bits %u, clusters %u, use %u\n",
(unsigned long long)le64_to_cpu(gd->bg_blkno),
le16_to_cpu(gd->bg_bits),
OCFS2_I(inode)->ip_clusters, max_bits);
}

ret = ocfs2_block_group_find_clear_bits(OCFS2_SB(inode->i_sb),
group_bh, bits_wanted,
max_bits,
&tmp_off, &tmp_found);
if (ret)
return ret;
Expand Down Expand Up @@ -951,6 +1024,7 @@ static int ocfs2_block_group_search(struct inode *inode,
if (bg->bg_free_bits_count)
ret = ocfs2_block_group_find_clear_bits(OCFS2_SB(inode->i_sb),
group_bh, bits_wanted,
le16_to_cpu(bg->bg_bits),
bit_off, bits_found);

return ret;
Expand Down Expand Up @@ -988,9 +1062,9 @@ static int ocfs2_search_chain(struct ocfs2_alloc_context *ac,
goto bail;
}
bg = (struct ocfs2_group_desc *) group_bh->b_data;
if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, bg);
status = -EIO;
status = ocfs2_check_group_descriptor(alloc_inode->i_sb, fe, bg);
if (status) {
mlog_errno(status);
goto bail;
}

Expand Down Expand Up @@ -1018,9 +1092,9 @@ static int ocfs2_search_chain(struct ocfs2_alloc_context *ac,
goto bail;
}
bg = (struct ocfs2_group_desc *) group_bh->b_data;
if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, bg);
status = -EIO;
status = ocfs2_check_group_descriptor(alloc_inode->i_sb, fe, bg);
if (status) {
mlog_errno(status);
goto bail;
}
}
Expand Down Expand Up @@ -1494,9 +1568,9 @@ static int ocfs2_free_suballoc_bits(struct ocfs2_journal_handle *handle,
}

group = (struct ocfs2_group_desc *) group_bh->b_data;
if (!OCFS2_IS_VALID_GROUP_DESC(group)) {
OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, group);
status = -EIO;
status = ocfs2_check_group_descriptor(alloc_inode->i_sb, fe, group);
if (status) {
mlog_errno(status);
goto bail;
}
BUG_ON((count + start_bit) > le16_to_cpu(group->bg_bits));
Expand Down

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