From: Theodore Ts'o <tytso@mit.edu>
To: 宋柏翰 <solarispika@gmail.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: Question on delalloc
Date: Tue, 4 Jun 2013 01:22:03 -0400 [thread overview]
Message-ID: <20130604052203.GA29587@thunk.org> (raw)
In-Reply-To: <CAJ1XODTmBmdOu+EL8OZy8ZRU4DbT7F179U7BrNDrQJQGtYQuWw@mail.gmail.com>
On Tue, Jun 04, 2013 at 03:00:29AM +0800, 宋柏翰 wrote:
> Also after I traced into filemap_write_and_wait_range, I found it
> eventually calls ext4_writepage to do the most part of work, which in
> its comment says "We don't do any block allocation in this function."
>
> So, can anyone kindly shed any light on my question, or point out my mistakes?
There are three possible address_space_operations structures that can
be used for ext4 files. They are ext4_aops, ext4_journalled_aops, and
ext4_da_aops. It is the last one which is used for delayed allocation
files, and in that case filemap_write_and_wait_range will use
ext4_da_writepages().
These days, if there is an writepages function, the writepage function
is not used at all. It used to be used for direct reclaim, but that's
been replaced by I/O-less reclaim.
- Ted
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next prev parent reply other threads:[~2013-06-04 5:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-03 19:00 Question on delalloc 宋柏翰
2013-06-04 5:22 ` Theodore Ts'o [this message]
2013-06-04 14:26 ` Eric Sandeen
2013-06-04 17:30 ` 宋柏翰
2013-06-04 19:01 ` Theodore Ts'o
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