Date:   Sun, 15 Jul 2018 09:30:45 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Chao Yu <yuchao0@...wei.com>
Subject: Re: [PATCH v3 1/2] f2fs: fix to avoid broken of dnode block list

On 2018/7/14 13:44, Jaegeuk Kim wrote:
> On 07/08, Chao Yu wrote:
>> From: Chao Yu <yuchao0@...wei.com>
>>
>> f2fs recovery flow is relying on dnode block link list, it means fsynced
>> file recovery depends on previous dnode's persistence in the list, so
>> during fsync() we should wait on all regular inode's dnode writebacked
>> before issuing flush.
>>
>> By this way, we can avoid dnode block list being broken by out-of-order
>> IO submission due to IO scheduler or driver.
> 
> Hi Chao,
> 
> Just in case, can we measure some performance numbers with this?

Hi Jaegeuk,

OK, let me do some tests on this.

Thanks,

> 
> Thanks,
> 
>>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>> v3:
>> - add a list to link all writebacked dnodes, let fsync() only wait on
>> necessary dnode.
>>  fs/f2fs/checkpoint.c |   2 +
>>  fs/f2fs/data.c       |   2 +
>>  fs/f2fs/f2fs.h       |  21 +++++++-
>>  fs/f2fs/file.c       |  20 +++----
>>  fs/f2fs/node.c       | 148 +++++++++++++++++++++++++++++++++++++++++----------
>>  fs/f2fs/super.c      |   4 ++
>>  6 files changed, 153 insertions(+), 44 deletions(-)
>>
>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>> index 8b698bd54490..d5e60d76362e 100644
>> --- a/fs/f2fs/checkpoint.c
>> +++ b/fs/f2fs/checkpoint.c
>> @@ -1379,6 +1379,8 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>>  
>>  	f2fs_release_ino_entry(sbi, false);
>>  
>> +	f2fs_reset_fsync_node_info(sbi);
>> +
>>  	if (unlikely(f2fs_cp_error(sbi)))
>>  		return -EIO;
>>  
>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>> index 70813a4dda3e..afe76d87575c 100644
>> --- a/fs/f2fs/data.c
>> +++ b/fs/f2fs/data.c
>> @@ -176,6 +176,8 @@ static void f2fs_write_end_io(struct bio *bio)
>>  					page->index != nid_of_node(page));
>>  
>>  		dec_page_count(sbi, WB_DATA_TYPE(page));
>> +		if (f2fs_in_warm_node_list(sbi, page))
>> +			f2fs_del_fsync_node_entry(sbi, page);
>>  		clear_cold_data(page);
>>  		end_page_writeback(page);
>>  	}
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index c8c865fa8450..bf5f7a336ace 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -228,6 +228,12 @@ struct inode_entry {
>>  	struct inode *inode;	/* vfs inode pointer */
>>  };
>>  
>> +struct fsync_node_entry {
>> +	struct list_head list;	/* list head */
>> +	struct page *page;	/* warm node page pointer */
>> +	unsigned int seq_id;	/* sequence id */
>> +};
>> +
>>  /* for the bitmap indicate blocks to be discarded */
>>  struct discard_entry {
>>  	struct list_head list;	/* list head */
>> @@ -1152,6 +1158,11 @@ struct f2fs_sb_info {
>>  
>>  	struct inode_management im[MAX_INO_ENTRY];      /* manage inode cache */
>>  
>> +	spinlock_t fsync_node_lock;		/* for node entry lock */
>> +	struct list_head fsync_node_list;	/* node list head */
>> +	unsigned int fsync_seg_id;		/* sequence id */
>> +	unsigned int fsync_node_num;		/* number of node entries */
>> +
>>  	/* for orphan inode, use 0'th array */
>>  	unsigned int max_orphans;		/* max orphan inodes */
>>  
>> @@ -2816,6 +2827,10 @@ struct node_info;
>>  
>>  int f2fs_check_nid_range(struct f2fs_sb_info *sbi, nid_t nid);
>>  bool f2fs_available_free_memory(struct f2fs_sb_info *sbi, int type);
>> +bool f2fs_in_warm_node_list(struct f2fs_sb_info *sbi, struct page *page);
>> +void f2fs_init_fsync_node_info(struct f2fs_sb_info *sbi);
>> +void f2fs_del_fsync_node_entry(struct f2fs_sb_info *sbi, struct page *page);
>> +void f2fs_reset_fsync_node_info(struct f2fs_sb_info *sbi);
>>  int f2fs_need_dentry_mark(struct f2fs_sb_info *sbi, nid_t nid);
>>  bool f2fs_is_checkpointed_node(struct f2fs_sb_info *sbi, nid_t nid);
>>  bool f2fs_need_inode_block_update(struct f2fs_sb_info *sbi, nid_t ino);
>> @@ -2825,7 +2840,8 @@ pgoff_t f2fs_get_next_page_offset(struct dnode_of_data *dn, pgoff_t pgofs);
>>  int f2fs_get_dnode_of_data(struct dnode_of_data *dn, pgoff_t index, int mode);
>>  int f2fs_truncate_inode_blocks(struct inode *inode, pgoff_t from);
>>  int f2fs_truncate_xattr_node(struct inode *inode);
>> -int f2fs_wait_on_node_pages_writeback(struct f2fs_sb_info *sbi, nid_t ino);
>> +int f2fs_wait_on_node_pages_writeback(struct f2fs_sb_info *sbi,
>> +					unsigned int seq_id);
>>  int f2fs_remove_inode_page(struct inode *inode);
>>  struct page *f2fs_new_inode_page(struct inode *inode);
>>  struct page *f2fs_new_node_page(struct dnode_of_data *dn, unsigned int ofs);
>> @@ -2834,7 +2850,8 @@ struct page *f2fs_get_node_page(struct f2fs_sb_info *sbi, pgoff_t nid);
>>  struct page *f2fs_get_node_page_ra(struct page *parent, int start);
>>  void f2fs_move_node_page(struct page *node_page, int gc_type);
>>  int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
>> -			struct writeback_control *wbc, bool atomic);
>> +			struct writeback_control *wbc, bool atomic,
>> +			unsigned int *seq_id);
>>  int f2fs_sync_node_pages(struct f2fs_sb_info *sbi,
>>  			struct writeback_control *wbc,
>>  			bool do_balance, enum iostat_type io_type);
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 5e29d4053748..ddea2bfd4042 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -213,6 +213,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
>>  		.nr_to_write = LONG_MAX,
>>  		.for_reclaim = 0,
>>  	};
>> +	unsigned int seq_id = 0;
>>  
>>  	if (unlikely(f2fs_readonly(inode->i_sb)))
>>  		return 0;
>> @@ -275,7 +276,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
>>  	}
>>  sync_nodes:
>>  	atomic_inc(&sbi->wb_sync_req[NODE]);
>> -	ret = f2fs_fsync_node_pages(sbi, inode, &wbc, atomic);
>> +	ret = f2fs_fsync_node_pages(sbi, inode, &wbc, atomic, &seq_id);
>>  	atomic_dec(&sbi->wb_sync_req[NODE]);
>>  	if (ret)
>>  		goto out;
>> @@ -292,19 +293,10 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
>>  		goto sync_nodes;
>>  	}
>>  
>> -	/*
>> -	 * If it's atomic_write, it's just fine to keep write ordering. So
>> -	 * here we don't need to wait for node write completion, since we use
>> -	 * node chain which serializes node blocks. If one of node writes are
>> -	 * reordered, we can see simply broken chain, resulting in stopping
>> -	 * roll-forward recovery. It means we'll recover all or none node blocks
>> -	 * given fsync mark.
>> -	 */
>> -	if (!atomic) {
>> -		ret = f2fs_wait_on_node_pages_writeback(sbi, ino);
>> -		if (ret)
>> -			goto out;
>> -	}
>> +
>> +	ret = f2fs_wait_on_node_pages_writeback(sbi, seq_id);
>> +	if (ret)
>> +		goto out;
>>  
>>  	/* once recovery info is written, don't need to tack this */
>>  	f2fs_remove_ino_entry(sbi, ino, APPEND_INO);
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index 1e30bc305243..31dc372c56a0 100644
>> --- a/fs/f2fs/node.c
>> +++ b/fs/f2fs/node.c
>> @@ -28,6 +28,7 @@
>>  static struct kmem_cache *nat_entry_slab;
>>  static struct kmem_cache *free_nid_slab;
>>  static struct kmem_cache *nat_entry_set_slab;
>> +static struct kmem_cache *fsync_node_entry_slab;
>>  
>>  /*
>>   * Check whether the given nid is within node id range.
>> @@ -267,6 +268,72 @@ static unsigned int __gang_lookup_nat_set(struct f2fs_nm_info *nm_i,
>>  							start, nr);
>>  }
>>  
>> +bool f2fs_in_warm_node_list(struct f2fs_sb_info *sbi, struct page *page)
>> +{
>> +	return NODE_MAPPING(sbi) == page->mapping &&
>> +			IS_DNODE(page) && is_cold_node(page);
>> +}
>> +
>> +void f2fs_init_fsync_node_info(struct f2fs_sb_info *sbi)
>> +{
>> +	spin_lock_init(&sbi->fsync_node_lock);
>> +	INIT_LIST_HEAD(&sbi->fsync_node_list);
>> +	sbi->fsync_seg_id = 0;
>> +	sbi->fsync_node_num = 0;
>> +}
>> +
>> +static unsigned int f2fs_add_fsync_node_entry(struct f2fs_sb_info *sbi,
>> +							struct page *page)
>> +{
>> +	struct fsync_node_entry *fn;
>> +	unsigned long flags;
>> +	unsigned int seq_id;
>> +
>> +	fn = f2fs_kmem_cache_alloc(fsync_node_entry_slab, GFP_NOFS);
>> +
>> +	get_page(page);
>> +	fn->page = page;
>> +	INIT_LIST_HEAD(&fn->list);
>> +
>> +	spin_lock_irqsave(&sbi->fsync_node_lock, flags);
>> +	list_add_tail(&fn->list, &sbi->fsync_node_list);
>> +	fn->seq_id = sbi->fsync_seg_id++;
>> +	seq_id = fn->seq_id;
>> +	sbi->fsync_node_num++;
>> +	spin_unlock_irqrestore(&sbi->fsync_node_lock, flags);
>> +
>> +	return seq_id;
>> +}
>> +
>> +void f2fs_del_fsync_node_entry(struct f2fs_sb_info *sbi, struct page *page)
>> +{
>> +	struct fsync_node_entry *fn;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&sbi->fsync_node_lock, flags);
>> +	list_for_each_entry(fn, &sbi->fsync_node_list, list) {
>> +		if (fn->page == page) {
>> +			list_del(&fn->list);
>> +			sbi->fsync_node_num--;
>> +			spin_unlock_irqrestore(&sbi->fsync_node_lock, flags);
>> +			kmem_cache_free(fsync_node_entry_slab, fn);
>> +			put_page(page);
>> +			return;
>> +		}
>> +	}
>> +	spin_unlock_irqrestore(&sbi->fsync_node_lock, flags);
>> +	f2fs_bug_on(sbi, 1);
>> +}
>> +
>> +void f2fs_reset_fsync_node_info(struct f2fs_sb_info *sbi)
>> +{
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&sbi->fsync_node_lock, flags);
>> +	sbi->fsync_node_num = 0;
>> +	spin_unlock_irqrestore(&sbi->fsync_node_lock, flags);
>> +}
>> +
>>  int f2fs_need_dentry_mark(struct f2fs_sb_info *sbi, nid_t nid)
>>  {
>>  	struct f2fs_nm_info *nm_i = NM_I(sbi);
>> @@ -1353,7 +1420,7 @@ static struct page *last_fsync_dnode(struct f2fs_sb_info *sbi, nid_t ino)
>>  
>>  static int __write_node_page(struct page *page, bool atomic, bool *submitted,
>>  				struct writeback_control *wbc, bool do_balance,
>> -				enum iostat_type io_type)
>> +				enum iostat_type io_type, unsigned int *seq_id)
>>  {
>>  	struct f2fs_sb_info *sbi = F2FS_P_SB(page);
>>  	nid_t nid;
>> @@ -1370,6 +1437,7 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
>>  		.io_type = io_type,
>>  		.io_wbc = wbc,
>>  	};
>> +	unsigned int seq;
>>  
>>  	trace_f2fs_writepage(page, NODE);
>>  
>> @@ -1416,6 +1484,13 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
>>  
>>  	set_page_writeback(page);
>>  	ClearPageError(page);
>> +
>> +	if (f2fs_in_warm_node_list(sbi, page)) {
>> +		seq = f2fs_add_fsync_node_entry(sbi, page);
>> +		if (seq_id)
>> +			*seq_id = seq;
>> +	}
>> +
>>  	fio.old_blkaddr = ni.blk_addr;
>>  	f2fs_do_write_node_page(nid, &fio);
>>  	set_node_addr(sbi, &ni, fio.new_blkaddr, is_fsync_dnode(page));
>> @@ -1463,7 +1538,7 @@ void f2fs_move_node_page(struct page *node_page, int gc_type)
>>  			goto out_page;
>>  
>>  		if (__write_node_page(node_page, false, NULL,
>> -					&wbc, false, FS_GC_NODE_IO))
>> +					&wbc, false, FS_GC_NODE_IO, NULL))
>>  			unlock_page(node_page);
>>  		goto release_page;
>>  	} else {
>> @@ -1480,11 +1555,13 @@ void f2fs_move_node_page(struct page *node_page, int gc_type)
>>  static int f2fs_write_node_page(struct page *page,
>>  				struct writeback_control *wbc)
>>  {
>> -	return __write_node_page(page, false, NULL, wbc, false, FS_NODE_IO);
>> +	return __write_node_page(page, false, NULL, wbc, false,
>> +						FS_NODE_IO, NULL);
>>  }
>>  
>>  int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
>> -			struct writeback_control *wbc, bool atomic)
>> +			struct writeback_control *wbc, bool atomic,
>> +			unsigned int *seq_id)
>>  {
>>  	pgoff_t index;
>>  	pgoff_t last_idx = ULONG_MAX;
>> @@ -1565,7 +1642,7 @@ int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
>>  			ret = __write_node_page(page, atomic &&
>>  						page == last_page,
>>  						&submitted, wbc, true,
>> -						FS_NODE_IO);
>> +						FS_NODE_IO, seq_id);
>>  			if (ret) {
>>  				unlock_page(page);
>>  				f2fs_put_page(last_page, 0);
>> @@ -1682,7 +1759,7 @@ int f2fs_sync_node_pages(struct f2fs_sb_info *sbi,
>>  			set_dentry_mark(page, 0);
>>  
>>  			ret = __write_node_page(page, false, &submitted,
>> -						wbc, do_balance, io_type);
>> +						wbc, do_balance, io_type, NULL);
>>  			if (ret)
>>  				unlock_page(page);
>>  			else if (submitted)
>> @@ -1713,35 +1790,42 @@ int f2fs_sync_node_pages(struct f2fs_sb_info *sbi,
>>  	return ret;
>>  }
>>  
>> -int f2fs_wait_on_node_pages_writeback(struct f2fs_sb_info *sbi, nid_t ino)
>> +int f2fs_wait_on_node_pages_writeback(struct f2fs_sb_info *sbi,
>> +						unsigned int seq_id)
>>  {
>> -	pgoff_t index = 0;
>> -	struct pagevec pvec;
>> -	int ret2, ret = 0;
>> -	int nr_pages;
>> +	struct fsync_node_entry *fn;
>> +	struct page *page;
>> +	struct list_head *head = &sbi->fsync_node_list;
>> +	unsigned long flags;
>> +	unsigned int cur_seq_id = 0;
>> +	int ret = 0;
>>  
>> -	pagevec_init(&pvec);
>> +	while (seq_id && cur_seq_id < seq_id) {
>> +		spin_lock_irqsave(&sbi->fsync_node_lock, flags);
>> +		if (list_empty(head)) {
>> +			spin_unlock_irqrestore(&sbi->fsync_node_lock, flags);
>> +			break;
>> +		}
>> +		fn = list_first_entry(head, struct fsync_node_entry, list);
>> +		if (fn->seq_id > seq_id) {
>> +			spin_unlock_irqrestore(&sbi->fsync_node_lock, flags);
>> +			break;
>> +		}
>> +		cur_seq_id = fn->seq_id;
>> +		page = fn->page;
>> +		get_page(page);
>> +		spin_unlock_irqrestore(&sbi->fsync_node_lock, flags);
>>  
>> -	while ((nr_pages = pagevec_lookup_tag(&pvec, NODE_MAPPING(sbi), &index,
>> -				PAGECACHE_TAG_WRITEBACK))) {
>> -		int i;
>> +		f2fs_wait_on_page_writeback(page, NODE, true);
>> +		if (TestClearPageError(page))
>> +			ret = -EIO;
>>  
>> -		for (i = 0; i < nr_pages; i++) {
>> -			struct page *page = pvec.pages[i];
>> +		put_page(page);
>>  
>> -			if (ino && ino_of_node(page) == ino) {
>> -				f2fs_wait_on_page_writeback(page, NODE, true);
>> -				if (TestClearPageError(page))
>> -					ret = -EIO;
>> -			}
>> -		}
>> -		pagevec_release(&pvec);
>> -		cond_resched();
>> +		if (ret)
>> +			break;
>>  	}
>>  
>> -	ret2 = filemap_check_errors(NODE_MAPPING(sbi));
>> -	if (!ret)
>> -		ret = ret2;
>>  	return ret;
>>  }
>>  
>> @@ -2939,8 +3023,15 @@ int __init f2fs_create_node_manager_caches(void)
>>  			sizeof(struct nat_entry_set));
>>  	if (!nat_entry_set_slab)
>>  		goto destroy_free_nid;
>> +
>> +	fsync_node_entry_slab = f2fs_kmem_cache_create("fsync_node_entry",
>> +			sizeof(struct fsync_node_entry));
>> +	if (!fsync_node_entry_slab)
>> +		goto destroy_nat_entry_set;
>>  	return 0;
>>  
>> +destroy_nat_entry_set:
>> +	kmem_cache_destroy(nat_entry_set_slab);
>>  destroy_free_nid:
>>  	kmem_cache_destroy(free_nid_slab);
>>  destroy_nat_entry:
>> @@ -2951,6 +3042,7 @@ int __init f2fs_create_node_manager_caches(void)
>>  
>>  void f2fs_destroy_node_manager_caches(void)
>>  {
>> +	kmem_cache_destroy(fsync_node_entry_slab);
>>  	kmem_cache_destroy(nat_entry_set_slab);
>>  	kmem_cache_destroy(free_nid_slab);
>>  	kmem_cache_destroy(nat_entry_slab);
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index 143ed321076e..34321932754d 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -1023,6 +1023,8 @@ static void f2fs_put_super(struct super_block *sb)
>>  	 */
>>  	f2fs_release_ino_entry(sbi, true);
>>  
>> +	f2fs_bug_on(sbi, sbi->fsync_node_num);
>> +
>>  	f2fs_leave_shrinker(sbi);
>>  	mutex_unlock(&sbi->umount_mutex);
>>  
>> @@ -2903,6 +2905,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>>  
>>  	f2fs_init_ino_entry_info(sbi);
>>  
>> +	f2fs_init_fsync_node_info(sbi);
>> +
>>  	/* setup f2fs internal modules */
>>  	err = f2fs_build_segment_manager(sbi);
>>  	if (err) {
>> -- 
>> 2.16.2.17.g38e79b1fd

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