[Ocfs2-tools-devel] [PATCH] o2image: return error if pread64 failed in ocfs2_image_load_bitmap()

[piaojun]

On 2016-12-26 9:55, Joseph Qi wrote:
> 
> 
> On 16/12/24 17:30, piaojun wrote:
>> Hi Joseph,
>>
>> On 2016-12-23 17:38, Joseph Qi wrote:
>>> Hi Jun,
>>>
>>>
>>> On 16/12/21 17:33, piaojun wrote:
>>>> In ocfs2_image_load_bitmap(), if pread64 failed, we need catch the
>>>> errno and return errno to upper callers. otherwise we may get the
>>>> incorrect 'arr_map' but 'o2image -I' execute successfully.
>>>>
>>>> Signed-off-by: Jun Piao <piaojun at huawei.com>
>>>> ---
>>>>    libocfs2/image.c | 15 ++++++++++-----
>>>>    1 file changed, 10 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/libocfs2/image.c b/libocfs2/image.c
>>>> index fe95530..460616d 100644
>>>> --- a/libocfs2/image.c
>>>> +++ b/libocfs2/image.c
>>>> @@ -163,7 +163,7 @@ errcode_t ocfs2_image_load_bitmap(ocfs2_filesys *ofs)
>>>>        struct ocfs2_image_state *ost;
>>>>        struct ocfs2_image_hdr *hdr;
>>>>        uint64_t blk_off, bits_set;
>>>> -    int count, i, j, fd;
>>>> +    int count = 0, tmp, i, j, fd;
>>>>        errcode_t ret;
>>>>        char *blk;
>>>>    @@ -216,10 +216,15 @@ errcode_t ocfs2_image_load_bitmap(ocfs2_filesys *ofs)
>>>>             * we don't use io_read_block as ocfs2 image bitmap block size
>>>>             * could be different from filesystem block size
>>>>             */
>>>> -        count = pread64(fd, ost->ost_bmparr[i].arr_map,
>>>> -                ost->ost_bmpblksz, blk_off);
>>>> -        if (count < ost->ost_bmpblksz)
>>>> -            goto out;
>>>> +        while (count < ost->ost_bmpblksz) {
>>>> +            tmp = pread64(fd, ost->ost_bmparr[i].arr_map + count,
>>>> +                ost->ost_bmpblksz - count, blk_off + count);
>>>> +            if (tmp <= 0) {
>>>> +                ret = OCFS2_ET_IO;
>>>> +                goto out;
>>>> +            }
>>>> +            count += tmp;
>>>> +        }
>>> In which case we need loop read?
>>> Or shall we just set the error code if read fails?
>>>
>>> Thanks,
>>> Joseph
>> The usage of pread64 refers to unix_io_read_block() in unix_io.c.
>> I have not catch the case we need loop read but I think it is safer by
>> loop reading in case of incomplete data.
>>
>> Thanks,
>> Jun
> If no real case, I'd prefer to keep it as simple as possible.
> 
> Thanks,
> Joseph
Thanks for suggestion, I will fix this in [PATCH v2].
>>>>              /* add bits set in this bitmap */
>>>>            for (j = 0; j < (ost->ost_bmpblksz * 8); j++)
>>>
>>>
> 
> 
> .
>