On 2019/5/30 下午8:02, David Sterba wrote:
> On Fri, May 03, 2019 at 08:30:54AM +0800, Qu Wenruo wrote:
>> Under certain condition, we could have strange file extent item in log
>> tree like:
>>
>> item 18 key (69599 108 397312) itemoff 15208 itemsize 53
>> extent data disk bytenr 0 nr 0
>> extent data offset 0 nr 18446744073709547520 ram 18446744073709547520
>>
>> The num_bytes and ram_bytes part overflow.
>>
>> For num_bytes part, we can detect such overflow along with file offset
>> (key->offset), as file_offset + num_bytes should never go beyond u64
>> max.
>>
>> For ram_bytes part, it's about the decompressed size of the extent, not
>> directly related to the size.
>> In theory is OK to have super large value, and put extra
>> limitation on ram bytes may cause unexpected false alert.
>>
>> So in tree-checker, we only check if the file offset and num bytes
>> overflow.
>>
>> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
>> ---
>> fs/btrfs/tree-checker.c | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>>
>> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
>> index 4f4f5af6345a..795eb6c18456 100644
>> --- a/fs/btrfs/tree-checker.c
>> +++ b/fs/btrfs/tree-checker.c
>> @@ -112,6 +112,7 @@ static int check_extent_data_item(struct extent_buffer *leaf,
>> struct btrfs_file_extent_item *fi;
>> u32 sectorsize = fs_info->sectorsize;
>> u32 item_size = btrfs_item_size_nr(leaf, slot);
>> + u64 extent_end;
>>
>> if (!IS_ALIGNED(key->offset, sectorsize)) {
>> file_extent_err(leaf, slot,
>> @@ -186,6 +187,14 @@ static int check_extent_data_item(struct extent_buffer *leaf,
>> CHECK_FE_ALIGNED(leaf, slot, fi, offset, sectorsize) ||
>> CHECK_FE_ALIGNED(leaf, slot, fi, num_bytes, sectorsize))
>> return -EUCLEAN;
>> + /* Catch extent end overflow case */
>> + if (check_add_overflow(btrfs_file_extent_num_bytes(leaf, fi),
>> + key->offset, &extent_end)) {
>> + file_extent_err(leaf, slot,
>> + "extent end overflow, have file offset %llu extent num bytes %llu",
>> + key->offset,
>> + btrfs_file_extent_num_bytes(leaf, fi));
>
> Isn't this missing
>
> return -EUCLEAN;
Oh, my bad.
Would you mind to fold that return line?
Thanks,
Qu
>
> ?
>
>> + }
>> return 0;
>> }
>>
>> --
>> 2.21.0
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