From: Ted Ts'o <tytso@mit.edu>
To: Yongqiang Yang <xiaoqiangnk@gmail.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: [PATCH 4/5] ext4: flush journal when switching from journal data mode
Date: Wed, 28 Dec 2011 13:56:43 -0500 [thread overview]
Message-ID: <20111228185643.GD12370@thunk.org> (raw)
In-Reply-To: <1321344474-14707-4-git-send-email-xiaoqiangnk@gmail.com>
On Tue, Nov 15, 2011 at 04:07:53PM +0800, Yongqiang Yang wrote:
> When switching from journal data mode, the data blocks
> in journal will have no revoke record. Thus, data could be
> corrupted during replay. However, there is no such problem in
> switching to journal data mode. So we flush journal only in
> the case that swithes from journal data mode.
>
> Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Applied, with a slightly different (and more explanatory commit
message):
ext4: flush journal when switching from data=journal mode
From: Yongqiang Yang <xiaoqiangnk@gmail.com>
It's necessary to flush the journal when switching away from
data=journal mode. This is because there are no revoke records when
we are data blocks are journalled, which are required in the other
journal modes.
However, it is not necessary to flush the journal when switching into
data=journal mode, and flushing the journal is expensive. So let's
avoid it in that case.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
- Ted
next prev parent reply other threads:[~2011-12-28 18:56 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-15 8:07 [PATCH 1/5] ext4: allocate delalloc blocks before changing journal mode Yongqiang Yang
2011-11-15 8:07 ` [PATCH 2/5] ext4: let ext4 journal deletion of data blocks Yongqiang Yang
2011-12-28 17:23 ` Ted Ts'o
2011-12-30 14:59 ` Yongqiang Yang
2011-12-30 15:05 ` Ted Ts'o
2011-11-15 8:07 ` [PATCH 3/5] ext4: let ext4_free_blocks handle multiblock correctly Yongqiang Yang
2011-12-28 17:23 ` Ted Ts'o
2011-11-15 8:07 ` [PATCH 4/5] ext4: flush journal when switching from journal data mode Yongqiang Yang
2011-12-28 18:56 ` Ted Ts'o [this message]
2011-12-29 21:01 ` Darrick J. Wong
2011-12-30 14:43 ` Yongqiang Yang
2011-12-30 14:57 ` Ted Ts'o
2011-11-15 8:07 ` [PATCH 5/5] jbd2: clear revoked flag on buffers before a new transaction started Yongqiang Yang
2011-12-28 23:25 ` Ted Ts'o
2011-12-09 3:31 ` [PATCH 1/5] ext4: allocate delalloc blocks before changing journal mode Toshiyuki Okajima
2011-12-28 17:14 ` Ted Ts'o
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