On Tue, Jul 30, 2013 at 7:41 PM, majianpeng <majianpeng@xxxxxxxxx> wrote:
>>>
>>>>dd if=/dev/urandom bs=1M count=2 of=file_with_holes
>>>>dd if=/dev/urandom bs=1M count=2 seek=4 of=file_with_holes conv=notrunc
>>>>dd if=file_with_holes bs=8M >/dev/null
>>>>
>>> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
>>> index 2ddf061..22a98e5 100644
>>> --- a/fs/ceph/file.c
>>> +++ b/fs/ceph/file.c
>>> @@ -349,17 +349,17 @@ more:
>>> dout("striped_read %llu~%u (read %u) got %d%s%s\n", pos, left, read,
>>> ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : "");
>>>
>>> - if (ret > 0) {
>>> - int didpages = (page_align + ret) >> PAGE_CACHE_SHIFT;
>>> + if (ret >= 0) {
>>> + int didpages = (page_align + this_len) >> PAGE_CACHE_SHIFT;
>>>
>>> - if (read < pos - off) {
>>> - dout(" zero gap %llu to %llu\n", off + read, pos);
>>> - ceph_zero_page_vector_range(page_align + read,
>>> - pos - off - read, pages);
>>> + if (was_short) {
>>> + dout(" zero gap %llu to %llu\n", pos + ret, pos + this_len);
>>> + ceph_zero_page_vector_range(page_align + ret,
>>> + this_len - ret, pages);
>>> }
>>> - pos += ret;
>>> + pos += this_len;
>>> read = pos - off;
>>> - left -= ret;
>>> + left -= this_len;
>>> page_pos += didpages;
>>> pages_left -= didpages;
>>>
>>> This patch can do those case. It only add ret== 0 in judgement 'ret > 0".
>>
>>maybe we should add a i_size check. stop reading next strip object
>>when 'pos > i_size'
>>
> I think we can't do this because i_size may smaller than real size in ceph.
>
ceph_aio_read() calls ceph_do_getattr() when 'checkeof = true', it
handles the case.
We must do i_size check in striped_read(), otherwise user program always gets as
much data as it requests. For example
dd if=/dev/urandom bs=1M count=1 of=file_with_holes
dd if=file_with_holes bs=64M iflag=direct of=/dev/null
Regards
Yan, Zheng
>>> But i think i will add a parameter about hit_hole. It will make the code easy to understand.
>>>
>>
>> i think 'was_short' is equal to 'hit_hole'
>>
[snip]
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