Re: Re: [PATCH] ceph:Update the file time after mmap-write.

[majianpeng <majianpeng@gmail.com>]

>On Thu, Jul 11, 2013 at 3:53 PM, majianpeng <majianpeng@gmail.com> wrote:
>>>On Thu, Jul 11, 2013 at 9:17 AM, majianpeng <majianpeng@gmail.com> wrote:
>>>> Although, mmap-write of ceph update the time of file using
>>>> file_update_time.Because it don't mark the relative cap so the time
>>>> can't save.
>>>
>>>I think cephfs' mmap IO support is still broken. mmap IO does not respect
>>>ceph capabilities at all. It's possible that the kclient has no Fw cap when
>>>ceph_page_mkwrite is called.
>>>
>>>Yan, Zheng
>>>
>>>
>> Hi Yan,
>>         For the read of mmap, i think we also add cap-check.
>> And i think we can rewrite the filemap_fault ect ceph_filemap_fault.
>> In ceph_filemap_fault, most code from filemap_fault, we only add cap-check for read-operation.
>> How about this or can you suggest anthor method?
>>
>
>This doesn't work. if a file is opened by multiple clients, the MDS
>doesn't issue Fcb caps to the client.
>If we add cap check to filemap_fault and page_mkwrite, they can block
>forever. To make mmap IO work
>properly, I think the only solution is introducing a new cache
>coherence protocol for mmap IO
>
Thanks your suggestion.
Unless we get the Fcb cap, we can do the mmap-io.How about this?
Because the cap can change,so we can using Fx to lock the file, so cap can't change.

>
>> Thanks!
>> Jianpeng Ma