I agree with this plan, I will also test this patch also.
Thanks
-----邮件原件-----
发件人: Chao Yu <yuch...@huawei.com>
发送时间: 2021年5月12日 9:52
收件人: Jaegeuk Kim <jaeg...@kernel.org>; changfeng...@vivo.com
抄送: linux-f2fs-devel@lists.sourceforge.net
主题: Re: [f2fs-dev] 答复: [PATCH v4] f2fs: compress: avoid unnecessary check in
f2fs_prepare_compress_overwrite
On 2021/5/12 5:50, Jaegeuk Kim wrote:
> On 05/11, changfeng...@vivo.com wrote:
>> Hi Jaegeuk:
>>
>> If there're existing clusters beyond i_size, may cause data
>> corruption, but will this happen in normal? maybe some error can
>> cause this, if i_size is error the data beyond size still can't
>> handle properly. Is there normal case can casue existing clusters beyond
>> i_size?
>
> We don't have a rule to sync between i_size and i_blocks.
I can't image a case that compressed cluster may cross filesize, it looks it's
a bug if that happened, but I'm not sure I have considered all cases. So, I
prefer to add a check condition as below, then testing w/ xfstest/por_fsstress
for a while.
Subject: [PATCH] f2fs: compress: compressed cluster should not cross i_size
---
fs/f2fs/data.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 06d1e58d3882..9acca358d578
100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3325,6 +3325,8 @@ static int f2fs_write_begin(struct file *file, struct
address_space *mapping,
err = ret;
goto fail;
} else if (ret) {
+ f2fs_bug_on(sbi, index >=
+ DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
return 0;
}
}
--
2.29.2
>
>>
>> Thanks.
>>
>> -----邮件原件-----
>> 发件人: Jaegeuk Kim <jaeg...@kernel.org>
>> 发送时间: 2021年5月10日 23:44
>> 收件人: Fengnan Chang <changfeng...@vivo.com>
>> 抄送: c...@kernel.org; linux-f2fs-devel@lists.sourceforge.net
>> 主题: Re: [PATCH v4] f2fs: compress: avoid unnecessary check in
>> f2fs_prepare_compress_overwrite
>>
>> On 05/07, Fengnan Chang wrote:
>>> when write compressed file with O_TRUNC, there will be a lot of
>>> unnecessary check valid blocks in f2fs_prepare_compress_overwrite,
>>> especially when written in page size, remove it.
>>>
>>> This patch will not bring significant performance improvements, I test
>>> this on mobile phone, use androbench, the sequential write test case
>>> was open file with O_TRUNC, set write size to 4KB, performance
>>> improved about 2%-3%. If write size set to 32MB, performance improved
>> about 0.5%.
>>>
>>> Signed-off-by: Fengnan Chang <changfeng...@vivo.com>
>>> ---
>>> fs/f2fs/data.c | 8 ++++++++
>>> 1 file changed, 8 insertions(+)
>>>
>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index
>>> cf935474ffba..b9ec7b182f45 100644
>>> --- a/fs/f2fs/data.c
>>> +++ b/fs/f2fs/data.c
>>> @@ -3303,9 +3303,17 @@ static int f2fs_write_begin(struct file *file,
>>> struct address_space *mapping, #ifdef CONFIG_F2FS_FS_COMPRESSION
>>> if (f2fs_compressed_file(inode)) {
>>> int ret;
>>> + pgoff_t end = (i_size_read(inode) + PAGE_SIZE - 1) >>
>> PAGE_SHIFT;
>>>
>>> *fsdata = NULL;
>>>
>>> + /*
>>> + * when write pos is bigger than inode size
>> ,f2fs_prepare_compress_overwrite
>>> + * always return 0, so check pos first to avoid this.
>>> + */
>>> + if (index >= end)
>>> + goto repeat;
>>
>> What if there're existing clusters beyond i_size? Given performance impacts,
>> do we really need this?
>>
>>> +
>>> ret = f2fs_prepare_compress_overwrite(inode, pagep,
>>> index, fsdata);
>>> if (ret < 0) {
>>> --
>>> 2.29.0
>>
>
>
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