From: Zheng Liu <gnehzuil.liu@gmail.com>
To: Eric Sandeen <sandeen@redhat.com>
Cc: ext4 development <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH] ext4: remove unreachable code in ext4_can_extents_be_merged()
Date: Fri, 1 Nov 2013 11:05:25 +0800 [thread overview]
Message-ID: <20131101030525.GA7314@gmail.com> (raw)
In-Reply-To: <5272C4E3.5040206@redhat.com>
On Thu, Oct 31, 2013 at 04:00:19PM -0500, Eric Sandeen wrote:
> commit
> ec22ba8e ext4: disable merging of uninitialized extents
>
> ensured that if either extent under consideration is uninit,
> we decline to merge, and immediately return.
>
> But right after that test, we test again for an uninit
> extent; we can never hit this. So just remove the impossible
> test and associated variable.
>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Looks good to me.
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Thanks,
- Zheng
> ---
>
> Disclosure: compile-tested only.
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 54d52af..de6d467 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -1666,7 +1666,7 @@ int
> ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
> struct ext4_extent *ex2)
> {
> - unsigned short ext1_ee_len, ext2_ee_len, max_len;
> + unsigned short ext1_ee_len, ext2_ee_len;
>
> /*
> * Make sure that both extents are initialized. We don't merge
> @@ -1677,11 +1677,6 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
> if (ext4_ext_is_uninitialized(ex1) || ext4_ext_is_uninitialized(ex2))
> return 0;
>
> - if (ext4_ext_is_uninitialized(ex1))
> - max_len = EXT_UNINIT_MAX_LEN;
> - else
> - max_len = EXT_INIT_MAX_LEN;
> -
> ext1_ee_len = ext4_ext_get_actual_len(ex1);
> ext2_ee_len = ext4_ext_get_actual_len(ex2);
>
> @@ -1694,7 +1689,7 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
> * as an RO_COMPAT feature, refuse to merge to extents if
> * this can result in the top bit of ee_len being set.
> */
> - if (ext1_ee_len + ext2_ee_len > max_len)
> + if (ext1_ee_len + ext2_ee_len > EXT_INIT_MAX_LEN)
> return 0;
> #ifdef AGGRESSIVE_TEST
> if (ext1_ee_len >= 4)
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2013-11-01 3:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-31 21:00 [PATCH] ext4: remove unreachable code in ext4_can_extents_be_merged() Eric Sandeen
2013-10-31 21:18 ` [PATCH] ext4: remove unreachable code after ext4_can_extents_be_merged() Eric Sandeen
2013-11-01 3:09 ` Zheng Liu
2013-11-08 3:26 ` Theodore Ts'o
2013-11-01 3:05 ` Zheng Liu [this message]
2013-11-08 3:26 ` [PATCH] ext4: remove unreachable code in ext4_can_extents_be_merged() Theodore Ts'o
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