From: Theodore Ts'o <tytso@mit.edu>
To: sunqiuyang <sunqiuyang@huawei.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-ext4@vger.kernel.org
Subject: Re: [PATCH 1/1] ext4: remove redundant assignment in ext4_iomap_begin()
Date: Thu, 21 Dec 2017 11:47:50 -0500 [thread overview]
Message-ID: <20171221164750.GD27177@thunk.org> (raw)
In-Reply-To: <20171127092127.26193-1-sunqiuyang@huawei.com>
On Mon, Nov 27, 2017 at 05:21:27PM +0800, sunqiuyang wrote:
> From: Qiuyang Sun <sunqiuyang@huawei.com>
>
> This line will not change the value of map.m_lblk in any case.
I don't see that it is absolutely guaranteed. And if you are
depending on ext4_es_find_delayed_extent() returns, then (a) the
following line which adjusts map.m_len could also be dropped, and (b)
we should add a WARN_ON to make the code robust against future changes
to the above function.
- Ted
>
> Signed-off-by: Qiuyang Sun <sunqiuyang@huawei.com>
> ---
> fs/ext4/inode.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 9f836e2..d4a42b1 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3443,7 +3443,6 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
>
> if (es.es_lblk < map.m_lblk)
> offs = map.m_lblk - es.es_lblk;
> - map.m_lblk = es.es_lblk + offs;
> map.m_len = es.es_len - offs;
> delalloc = true;
> }
> --
> 2.5.0
>
prev parent reply other threads:[~2017-12-21 16:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-27 9:21 [PATCH 1/1] ext4: remove redundant assignment in ext4_iomap_begin() sunqiuyang
2017-12-21 16:47 ` Theodore Ts'o [this message]
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