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Subject: Re: [PATCH 1/5] f2fs: fix to wait page writeback before update
To:     Jaegeuk Kim <jaegeuk@kernel.org>
CC:     <linux-f2fs-devel@lists.sourceforge.net>,
        <linux-kernel@vger.kernel.org>, <chao@kernel.org>
References: <20200618063625.110273-1-yuchao0@huawei.com>
 <20200618235932.GA227771@google.com>
 <f5bbb14b-52a0-9697-a8fe-c3e39f78b0a5@huawei.com>
 <20200619054922.GC227771@google.com>
 <3634ef79-5903-449d-0d52-3d5566481863@huawei.com>
 <20200619224755.GA60059@google.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <3f49539a-7be1-be90-d13a-2f66a8483458@huawei.com>
Date:   Sat, 20 Jun 2020 08:52:09 +0800
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On 2020/6/20 6:47, Jaegeuk Kim wrote:
> On 06/19, Chao Yu wrote:
>> On 2020/6/19 13:49, Jaegeuk Kim wrote:
>>> On 06/19, Chao Yu wrote:
>>>> Hi Jaegeuk,
>>>>
>>>> On 2020/6/19 7:59, Jaegeuk Kim wrote:
>>>>> Hi Chao,
>>>>>
>>>>> On 06/18, Chao Yu wrote:
>>>>>> to make page content stable for special device like raid.
>>>>>
>>>>> Could you elaborate the problem a bit?
>>>>
>>>> Some devices like raid5 wants page content to be stable, because
>>>> it will calculate parity info based page content, if page is not
>>>> stable, parity info could be corrupted, result in data inconsistency
>>>> in stripe.
>>>
>>> I don't get the point, since those pages are brand new pages which were not
>>> modified before. If it's on writeback, we should not modify them regardless
>>> of whatever raid configuration. For example, f2fs_new_node_page() waits for
>>> writeback. Am I missing something?
>>
>> I think we should use f2fs_bug_on(, PageWriteback()) rather than
>> f2fs_wait_on_page_writeback() for brand new page which is allocated just now.
>> For other paths, we can keep rule that waiting for writeback before updating.
>>
>> How do you think?
>>
>> Thanks,
>>
>>>
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>>>
>>>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>>>> ---
>>>>>>  fs/f2fs/dir.c          |  2 ++
>>>>>>  fs/f2fs/extent_cache.c | 18 +++++++++---------
>>>>>>  fs/f2fs/f2fs.h         |  2 +-
>>>>>>  fs/f2fs/file.c         |  1 +
>>>>>>  fs/f2fs/inline.c       |  2 ++
>>>>>>  fs/f2fs/inode.c        |  3 +--
>>>>>>  6 files changed, 16 insertions(+), 12 deletions(-)
>>>>>>
>>>>>> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
>>>>>> index d35976785e8c..91e86747a604 100644
>>>>>> --- a/fs/f2fs/dir.c
>>>>>> +++ b/fs/f2fs/dir.c
>>>>>> @@ -495,6 +495,8 @@ static int make_empty_dir(struct inode *inode,
>>>>>>  	if (IS_ERR(dentry_page))
>>>>>>  		return PTR_ERR(dentry_page);
>>>>>>  
>>>>>> +	f2fs_bug_on(F2FS_I_SB(inode), PageWriteback(dentry_page));
>>>>>> +
>>>>>>  	dentry_blk = page_address(dentry_page);
>>>>>>  
>>>>>>  	make_dentry_ptr_block(NULL, &d, dentry_blk);
>>>>>> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
>>>>>> index e60078460ad1..686c68b98610 100644
>>>>>> --- a/fs/f2fs/extent_cache.c
>>>>>> +++ b/fs/f2fs/extent_cache.c
>>>>>> @@ -325,9 +325,10 @@ static void __drop_largest_extent(struct extent_tree *et,
>>>>>>  }
>>>>>>  
>>>>>>  /* return true, if inode page is changed */
>>>>>> -static bool __f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
>>>>>> +static void __f2fs_init_extent_tree(struct inode *inode, struct page *ipage)
>>>>>>  {
>>>>>>  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>>>>> +	struct f2fs_extent *i_ext = ipage ? &F2FS_INODE(ipage)->i_ext : NULL;
>>>>>>  	struct extent_tree *et;
>>>>>>  	struct extent_node *en;
>>>>>>  	struct extent_info ei;
>>>>>> @@ -335,16 +336,18 @@ static bool __f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_e
>>>>>>  	if (!f2fs_may_extent_tree(inode)) {
>>>>>>  		/* drop largest extent */
>>>>>>  		if (i_ext && i_ext->len) {
>>>>>> +			f2fs_wait_on_page_writeback(ipage, NODE, true, true);
>>>>>>  			i_ext->len = 0;
>>>>>> -			return true;
>>>>>> +			set_page_dirty(ipage);
>>>>>> +			return;
>>>>>>  		}
>>>>>> -		return false;
>>>>>> +		return;
>>>>>>  	}
>>>>>>  
>>>>>>  	et = __grab_extent_tree(inode);
>>>>>>  
>>>>>>  	if (!i_ext || !i_ext->len)
>>>>>> -		return false;
>>>>>> +		return;
>>>>>>  
>>>>>>  	get_extent_info(&ei, i_ext);
>>>>>>  
>>>>>> @@ -360,17 +363,14 @@ static bool __f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_e
>>>>>>  	}
>>>>>>  out:
>>>>>>  	write_unlock(&et->lock);
>>>>>> -	return false;
>>>>>>  }
>>>>>>  
>>>>>> -bool f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
>>>>>> +void f2fs_init_extent_tree(struct inode *inode, struct page *ipage)
>>>>>>  {
>>>>>> -	bool ret =  __f2fs_init_extent_tree(inode, i_ext);
>>>>>> +	__f2fs_init_extent_tree(inode, ipage);
>>>>>>  
>>>>>>  	if (!F2FS_I(inode)->extent_tree)
>>>>>>  		set_inode_flag(inode, FI_NO_EXTENT);
>>>>>> -
>>>>>> -	return ret;
>>>>>>  }
>>>>>>  
>>>>>>  static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
>>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>>>> index b35a50f4953c..326c12fa0da5 100644
>>>>>> --- a/fs/f2fs/f2fs.h
>>>>>> +++ b/fs/f2fs/f2fs.h
>>>>>> @@ -3795,7 +3795,7 @@ struct rb_entry *f2fs_lookup_rb_tree_ret(struct rb_root_cached *root,
>>>>>>  bool f2fs_check_rb_tree_consistence(struct f2fs_sb_info *sbi,
>>>>>>  						struct rb_root_cached *root);
>>>>>>  unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink);
>>>>>> -bool f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext);
>>>>>> +void f2fs_init_extent_tree(struct inode *inode, struct page *ipage);
>>>>>>  void f2fs_drop_extent_tree(struct inode *inode);
>>>>>>  unsigned int f2fs_destroy_extent_node(struct inode *inode);
>>>>>>  void f2fs_destroy_extent_tree(struct inode *inode);
>>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>>>> index 3268f8dd59bb..1862073b96d2 100644
>>>>>> --- a/fs/f2fs/file.c
>>>>>> +++ b/fs/f2fs/file.c
>>>>>> @@ -1250,6 +1250,7 @@ static int __clone_blkaddrs(struct inode *src_inode, struct inode *dst_inode,
>>>>>>  				f2fs_put_page(psrc, 1);
>>>>>>  				return PTR_ERR(pdst);
>>>>>>  			}
>>>>>> +			f2fs_wait_on_page_writeback(pdst, DATA, true, true);
> 
> Do you mean pdst can be under writeback?

Use f2fs_bug_on(, dirty || writeback) here?

> 
>>>>>>  			f2fs_copy_page(psrc, pdst);
>>>>>>  			set_page_dirty(pdst);
>>>>>>  			f2fs_put_page(pdst, 1);
>>>>>> diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
>>>>>> index dbade310dc79..4bcbc486c9e2 100644
>>>>>> --- a/fs/f2fs/inline.c
>>>>>> +++ b/fs/f2fs/inline.c
>>>>>> @@ -340,6 +340,8 @@ int f2fs_make_empty_inline_dir(struct inode *inode, struct inode *parent,
>>>>>>  	struct f2fs_dentry_ptr d;
>>>>>>  	void *inline_dentry;
>>>>>>  
>>>>>> +	f2fs_wait_on_page_writeback(ipage, NODE, true, true);

f2fs_bug_on(, writeback)?

Thanks,

>>>>>> +
>>>>>>  	inline_dentry = inline_data_addr(inode, ipage);
>>>>>>  
>>>>>>  	make_dentry_ptr_inline(inode, &d, inline_dentry);
>>>>>> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
>>>>>> index 44582a4db513..7c156eb26dd7 100644
>>>>>> --- a/fs/f2fs/inode.c
>>>>>> +++ b/fs/f2fs/inode.c
>>>>>> @@ -367,8 +367,7 @@ static int do_read_inode(struct inode *inode)
>>>>>>  	fi->i_pino = le32_to_cpu(ri->i_pino);
>>>>>>  	fi->i_dir_level = ri->i_dir_level;
>>>>>>  
>>>>>> -	if (f2fs_init_extent_tree(inode, &ri->i_ext))
>>>>>> -		set_page_dirty(node_page);
>>>>>> +	f2fs_init_extent_tree(inode, node_page);
>>>>>>  
>>>>>>  	get_inline_info(inode, ri);
>>>>>>  
>>>>>> -- 
>>>>>> 2.18.0.rc1
>>>>> .
>>>>>
>>> .
>>>
> .
>