Date:   Sun, 29 Jul 2018 10:10:16 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <yuchao0@...wei.com>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] f2fs: fix to avoid broken of dnode block list

On 2018/7/29 9:33, Jaegeuk Kim wrote:
> On 07/28, Chao Yu wrote:
>> 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.
>>
>> Sheng Yong helps to do the test with this patch:
>>
>> Target:/data (f2fs, -)
>> 64MB / 32768KB / 4KB / 8
>>
>> 1 / PERSIST / Index
>>
>> Base:
>> 	SEQ-RD(MB/s)	SEQ-WR(MB/s)	RND-RD(IOPS)	RND-WR(IOPS)	Insert(TPS)	Update(TPS)	Delete(TPS)
>> 1	867.82		204.15		41440.03	41370.54	680.8		1025.94		1031.08
>> 2	871.87		205.87		41370.3		40275.2		791.14		1065.84		1101.7
>> 3	866.52		205.69		41795.67	40596.16	694.69		1037.16		1031.48
>> Avg	868.7366667	205.2366667	41535.33333	40747.3		722.21		1042.98		1054.753333
>>
>> After:
>> 	SEQ-RD(MB/s)	SEQ-WR(MB/s)	RND-RD(IOPS)	RND-WR(IOPS)	Insert(TPS)	Update(TPS)	Delete(TPS)
>> 1	798.81		202.5		41143		40613.87	602.71		838.08		913.83
>> 2	805.79		206.47		40297.2		41291.46	604.44		840.75		924.27
>> 3	814.83		206.17		41209.57	40453.62	602.85		834.66		927.91
>> Avg	806.4766667	205.0466667	40883.25667	40786.31667	603.3333333	837.83		922.0033333
>>
>> Patched/Original:
>> 	0.928332713	0.999074239	0.984300676	1.000957528	0.835398753	0.803303994	0.874141189
> 
> I expect Sheng will provide more test results tho, at least it seems SEQ-RD
> in Base shows better than two After results, even if it doesn't matter with
> the issue. Please confirm it first in order for anybody to say there is no
> regression.

Agreed.

Thanks,

> 
>>
>> It looks like atomic write will suffer performance regression.
>>
>> I suspect that the criminal is that we forcing to wait all dnode being in
>> storage cache before we issue PREFLUSH+FUA.
>>
>> BTW, will commit ("f2fs: don't need to wait for node writes for atomic write")
>> cause the problem: we will lose data of last transaction after SPO, even if
>> atomic write return no error:
>>
>> - atomic_open();
>> - write() P1, P2, P3;
>> - atomic_commit();
>>  - writeback data: P1, P2, P3;
>>  - writeback node: N1, N2, N3;  <--- If N1, N2 is not writebacked, N3 with fsync_mark is
>> writebacked, In SPOR, we won't find N3 since node chain is broken, turns out that losing
>> last transaction.
>>  - preflush + fua;
>> - power-cut
>>
>> If we don't wait dnode writeback for atomic_write:
>>
>> 	SEQ-RD(MB/s)	SEQ-WR(MB/s)	RND-RD(IOPS)	RND-WR(IOPS)	Insert(TPS)	Update(TPS)	Delete(TPS)
>> 1	779.91		206.03		41621.5		40333.16	716.9		1038.21		1034.85
>> 2	848.51		204.35		40082.44	39486.17	791.83		1119.96		1083.77
>> 3	772.12		206.27		41335.25	41599.65	723.29		1055.07		971.92
>> Avg	800.18		205.55		41013.06333	40472.99333	744.0066667	1071.08		1030.18
>>
>> Patched/Original:
>> 	0.92108464	1.001526693	0.987425886	0.993268102	1.030180511	1.026942031	0.976702294
>>
>> SQLite's performance recovers.
>>
>> Jaegeuk:
>> "Practically, I don't see db corruption becase of this. We can excuse to lose
>> the last transaction."
>>
>> Finally, we decide to keep original implementation of atomic write interface
>> sematics that we don't wait all dnode writeback before preflush+fua submission.
>>
>> Tested-by: Sheng Yong <shengyong1@...wei.com>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>> v5:
>> - add missing Tested-by.
>> - fix f2fs_reset_fsync_node_info() to reset sbi->fsync_seg_id correctly.
>>  fs/f2fs/checkpoint.c |   2 +
>>  fs/f2fs/data.c       |   2 +
>>  fs/f2fs/f2fs.h       |  21 ++++++-
>>  fs/f2fs/file.c       |   5 +-
>>  fs/f2fs/node.c       | 144 +++++++++++++++++++++++++++++++++++--------
>>  fs/f2fs/super.c      |   4 ++
>>  6 files changed, 150 insertions(+), 28 deletions(-)
>>
>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>> index 581710760ba6..2136430f9f0d 100644
>> --- a/fs/f2fs/checkpoint.c
>> +++ b/fs/f2fs/checkpoint.c
>> @@ -1410,6 +1410,8 @@ 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);
>> +
>>  	clear_sbi_flag(sbi, SBI_IS_DIRTY);
>>  	clear_sbi_flag(sbi, SBI_NEED_CP);
>>  	__set_cp_next_pack(sbi);
>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>> index 6b8ca5011bfd..572c91e43337 100644
>> --- a/fs/f2fs/data.c
>> +++ b/fs/f2fs/data.c
>> @@ -177,6 +177,8 @@ static void f2fs_write_end_io(struct bio *bio)
>>  					page->index != nid_of_node(page));
>>  
>>  		dec_page_count(sbi, type);
>> +		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 0374f069520c..6627fef9ae38 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 */
>> @@ -1156,6 +1162,11 @@ 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 */
>>  
>> @@ -2822,6 +2833,10 @@ 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);
>> @@ -2831,7 +2846,8 @@ 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);
>> @@ -2840,7 +2856,8 @@ 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 8f9ab66858ca..7bd2412a8c37 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;
>> @@ -301,7 +302,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
>>  	 * given fsync mark.
>>  	 */
>>  	if (!atomic) {
>> -		ret = f2fs_wait_on_node_pages_writeback(sbi, ino);
>> +		ret = f2fs_wait_on_node_pages_writeback(sbi, seq_id);
>>  		if (ret)
>>  			goto out;
>>  	}
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index 9d9f4c9750c4..e109c671cd84 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.
>> @@ -264,6 +265,72 @@ 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_seg_id = 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);
>> @@ -1384,7 +1451,7 @@ 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;
>> @@ -1401,6 +1468,7 @@ 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);
>>  
>> @@ -1442,6 +1510,13 @@ 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));
>> @@ -1489,7 +1564,7 @@ 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 {
>> @@ -1506,11 +1581,13 @@ 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;
>> @@ -1591,7 +1668,7 @@ 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);
>> @@ -1708,7 +1785,7 @@ 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)
>> @@ -1739,35 +1816,46 @@ 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;
>> +	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 ret2, ret = 0;
>> -	int nr_pages;
>>  
>> -	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;
>>  }
>>  
>> @@ -2982,8 +3070,15 @@ 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:
>> @@ -2994,6 +3089,7 @@ 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 0eff4637fe55..cb1ba9f18353 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -1030,6 +1030,8 @@ 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);
>>  
>> @@ -2923,6 +2925,8 @@ 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) {
>> -- 
>> 2.18.0.rc1

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