On Thu, Jun 23, 2011 at 10:57 PM, Eric Sandeen <sandeen@xxxxxxxxxx> wrote:
> On 6/23/11 3:47 AM, Robin Dong wrote:
>> If eh_entries is equal to (or greater than) eh_max, the operation of
>> inserting new extent_idx will make number of entries overflow.
>> So check eh_entries before inserting the new extent_idx.
>
> Do you have any testcase you can share which shows this bug?
I am not sure if Robin has any test case.
According to code, I think there is no bug case. Because this
function is called by ext4_ext_split() and ext4_ext_split() is called
only if the index block has free space.
I think the right logic should be as this patch shows, that is, we
should lookup the capacity before insertion.
Yongqiang.
>
> Thanks,
> -Eric
>
>> Signed-off-by: Robin Dong <sanbai@xxxxxxxxxx>
>> ---
>> fs/ext4/extents.c | 18 ++++++++++--------
>> 1 files changed, 10 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
>> index eb63c7b..792e77e 100644
>> --- a/fs/ext4/extents.c
>> +++ b/fs/ext4/extents.c
>> @@ -776,6 +776,16 @@ static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
>> logical, le32_to_cpu(curp->p_idx->ei_block));
>> return -EIO;
>> }
>> +
>> + if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
>> + >= le16_to_cpu(curp->p_hdr->eh_max))) {
>> + EXT4_ERROR_INODE(inode,
>> + "eh_entries %d >= eh_max %d!",
>> + le16_to_cpu(curp->p_hdr->eh_entries),
>> + le16_to_cpu(curp->p_hdr->eh_max));
>> + return -EIO;
>> + }
>> +
>> len = EXT_MAX_INDEX(curp->p_hdr) - curp->p_idx;
>> if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
>> /* insert after */
>> @@ -805,14 +815,6 @@ static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
>> ext4_idx_store_pblock(ix, ptr);
>> le16_add_cpu(&curp->p_hdr->eh_entries, 1);
>>
>> - if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
>> - > le16_to_cpu(curp->p_hdr->eh_max))) {
>> - EXT4_ERROR_INODE(inode,
>> - "eh_entries %d > eh_max %d!",
>> - le16_to_cpu(curp->p_hdr->eh_entries),
>> - le16_to_cpu(curp->p_hdr->eh_max));
>> - return -EIO;
>> - }
>> if (unlikely(ix > EXT_LAST_INDEX(curp->p_hdr))) {
>> EXT4_ERROR_INODE(inode, "ix > EXT_LAST_INDEX!");
>> return -EIO;
>
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--
Best Wishes
Yongqiang Yang
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