Re: [PATCH 1/4] vfs: introduce try_to_writeback_inodes_sb(_nr)

[Miao Xie <miaoxie1984@gmail.com>]

=E4=BA=8E 2012=E5=B9=B404=E6=9C=8826=E6=97=A5 23:12, Josef Bacik =E5=86=
=99=E9=81=93:

> On Thu, Apr 26, 2012 at 03:55:52PM +0800, Xie Miao wrote:
>> On Thu, Apr 26, 2012 at 11:11 AM, Dave Chinner <david@fromorbit.com>=
 wrote:
>>>> writeback_inodes_sb(_nr) grabs s_umount lock when it want to start
>>>> writeback,
>>>> it may bring us deadlock problem when doing umount. So we introduc=
e new
>>>> functions -- try_to_writeback_inodes_sb(_nr) -- which use
>>>> down_read_trylock()
>>>> instead of down_read() to avoid that deadlock problem.
>>>>
>>>> This idea came from Christoph Hellwig.
>>>> Some code is from the patch of Kamal Mostafa.
>>>
>>> This just re-implements writeback_inodes_[nr]_sb_if_idle() with a
>>> trylock instead of a blocking lock.
>>>
>>> Just replace the blocking lock in writeback_inodes_[nr]_sb_if_idle(=
)
>>> with a trylock and use that.
>>
>> The change of these two functions is relative to three modules,  so =
I think
>> the patch set now is easy to be reviewed by the developers of each m=
odule.
>>
>=20
> I agree with David, there's no sense in making something completely s=
eperate,
> this function was introduced soley to kick off background writeout if=
 we could
> with no garuntees, if the other users suddenly don't like the behavio=
r they can
> creating something different for themselves.  Thanks,


OK, I'll make them together.

Thanks
Miao
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