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Date:   Thu, 18 Jun 2020 22:49:22 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, chao@kernel.org
Subject: Re: [PATCH 1/5] f2fs: fix to wait page writeback before update
Message-ID: <20200619054922.GC227771@google.com>
References: <20200618063625.110273-1-yuchao0@huawei.com>
 <20200618235932.GA227771@google.com>
 <f5bbb14b-52a0-9697-a8fe-c3e39f78b0a5@huawei.com>
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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?

> 
> 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);
> >>  			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);
> >> +
> >>  	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
> > .
> >