linux-kernel - Re: [PATCH V2] f2fs: fix to adjust appropirate defragment pg

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Date: Wed, 27 Mar 2024 15:38:34 +0800
From: Chao Yu <chao@...nel.org>
To: Zhiguo Niu <niuzhiguo84@...il.com>
Cc: Zhiguo Niu <zhiguo.niu@...soc.com>, jaegeuk@...nel.org,
 linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
 ke.wang@...soc.com, hongyu.jin@...soc.com
Subject: Re: [PATCH V2] f2fs: fix to adjust appropirate defragment pg_end

On 2024/3/27 9:26, Zhiguo Niu wrote:
> On Tue, Mar 26, 2024 at 7:11 PM Chao Yu <chao@...nel.org> wrote:
>>
>> On 2024/3/25 13:56, Zhiguo Niu wrote:
>>> A length that exceeds the real size of the inode may be
>>> specified from user, although these out-of-range areas
>>> are not mapped, but they still need to be check in
>>> while loop, which is unnecessary.
>>>
>>> Signed-off-by: Zhiguo Niu <zhiguo.niu@...soc.com>
>>> ---
>>> v2: check i_size within inode lock according to Chao's suggestions
>>> ---
>>> ---
>>>    fs/f2fs/file.c | 11 +++++++----
>>>    1 file changed, 7 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>> index 128e53d..cf63db7 100644
>>> --- a/fs/f2fs/file.c
>>> +++ b/fs/f2fs/file.c
>>> @@ -2608,9 +2608,6 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
>>>        bool fragmented = false;
>>>        int err;
>>>
>>> -     pg_start = range->start >> PAGE_SHIFT;
>>> -     pg_end = (range->start + range->len) >> PAGE_SHIFT;
>>> -
>>>        f2fs_balance_fs(sbi, true);
>>>
>>>        inode_lock(inode);
>>> @@ -2629,10 +2626,16 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
>>
>> pg_start = range->start >> PAGE_SHIFT;
>> pg_end = min_t(pgoff_t, (range->start + range->len) >> PAGE_SHIFT,
>>                          DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
>>
>>>
>>>        /* writeback all dirty pages in the range */
>>>        err = filemap_write_and_wait_range(inode->i_mapping, range->start,
>>> -                                             range->start + range->len - 1);
>>> +                                             min_t(loff_t, range->start + range->len - 1,
>>> +                                             i_size_read(inode) - 1));
>>
>> , pg_start << PAGE_SHIFT - 1, pg_end << PAGE_SHIFT - 1); ?
> should be  pg_start << PAGE_SHIFT , pg_end << PAGE_SHIFT - 1)??

Oh, yes. :)

Thanks,

> if range.start=0, pg_start is also 0, lstart in
> filemap_write_and_wait_range is 0,
> but pg_start << PAGE_SHIFT - 1 will get lstart=-1?
> thanks！
>>
>> Thanks,
>>
>>>        if (err)
>>>                goto out;
>>>
>>> +     pg_start = range->start >> PAGE_SHIFT;
>>> +     pg_end = min_t(pgoff_t,
>>> +                             (range->start + range->len) >> PAGE_SHIFT,
>>> +                             DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
>>> +
>>>        /*
>>>         * lookup mapping info in extent cache, skip defragmenting if physical
>>>         * block addresses are continuous.