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Message-ID: <211c28eb-789e-e6e6-5daf-8040ac5ddd93@kernel.org>
Date:   Fri, 4 Feb 2022 08:20:39 +0800
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Subject: Re: [f2fs-dev] [PATCH v2] f2fs: add a way to limit roll forward
 recovery time
Content-Language: en-US
To:     Jaegeuk Kim <jaegeuk@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net
References: <20220127214102.2040254-1-jaegeuk@kernel.org>
 <YfsjEb2ii3eyPzng@google.com>
 <142d2cc9-73f2-f9fa-2543-6426c62e77a6@kernel.org>
 <YfwT/6bSqUqUF/B3@google.com>
From:   Chao Yu <chao@kernel.org>
In-Reply-To: <YfwT/6bSqUqUF/B3@google.com>
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On 2022/2/4 1:42, Jaegeuk Kim wrote:
> On 02/03, Chao Yu wrote:
>> On 2022/2/3 8:34, Jaegeuk Kim wrote:
>>> This adds a sysfs entry to call checkpoint during fsync() in order to avoid
>>> long elapsed time to run roll-forward recovery when booting the device.
>>> Default value doesn't enforce the limitation which is same as before.
>>>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>>> ---
>>> v2 from v1:
>>>    - make the default w/o enforcement
>>>
>>>    Documentation/ABI/testing/sysfs-fs-f2fs | 6 ++++++
>>>    fs/f2fs/checkpoint.c                    | 1 +
>>>    fs/f2fs/f2fs.h                          | 3 +++
>>>    fs/f2fs/node.c                          | 2 ++
>>>    fs/f2fs/node.h                          | 3 +++
>>>    fs/f2fs/recovery.c                      | 4 ++++
>>>    fs/f2fs/sysfs.c                         | 2 ++
>>>    7 files changed, 21 insertions(+)
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
>>> index 87d3884c90ea..ce8103f522cb 100644
>>> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
>>> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
>>> @@ -567,3 +567,9 @@ Contact:	"Daeho Jeong" <daehojeong@google.com>
>>>    Description:	You can set the trial count limit for GC urgent high mode with this value.
>>>    		If GC thread gets to the limit, the mode will turn back to GC normal mode.
>>>    		By default, the value is zero, which means there is no limit like before.
>>> +
>>> +What:		/sys/fs/f2fs/<disk>/max_roll_forward_node_blocks
>>> +Date:		January 2022
>>> +Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>
>>> +Description:	Controls max # of node block writes to be used for roll forward
>>> +		recovery. This can limit the roll forward recovery time.
>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>>> index deeda95688f0..57a2d9164bee 100644
>>> --- a/fs/f2fs/checkpoint.c
>>> +++ b/fs/f2fs/checkpoint.c
>>> @@ -1543,6 +1543,7 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>>>    	/* update user_block_counts */
>>>    	sbi->last_valid_block_count = sbi->total_valid_block_count;
>>>    	percpu_counter_set(&sbi->alloc_valid_block_count, 0);
>>> +	percpu_counter_set(&sbi->rf_node_block_count, 0);
>>>    	/* Here, we have one bio having CP pack except cp pack 2 page */
>>>    	f2fs_sync_meta_pages(sbi, META, LONG_MAX, FS_CP_META_IO);
>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>> index 63c90416364b..6ddb98ff0b7c 100644
>>> --- a/fs/f2fs/f2fs.h
>>> +++ b/fs/f2fs/f2fs.h
>>> @@ -913,6 +913,7 @@ struct f2fs_nm_info {
>>>    	nid_t max_nid;			/* maximum possible node ids */
>>>    	nid_t available_nids;		/* # of available node ids */
>>>    	nid_t next_scan_nid;		/* the next nid to be scanned */
>>> +	nid_t max_rf_node_blocks;	/* max # of nodes for recovery */
>>>    	unsigned int ram_thresh;	/* control the memory footprint */
>>>    	unsigned int ra_nid_pages;	/* # of nid pages to be readaheaded */
>>>    	unsigned int dirty_nats_ratio;	/* control dirty nats ratio threshold */
>>> @@ -1684,6 +1685,8 @@ struct f2fs_sb_info {
>>>    	atomic_t nr_pages[NR_COUNT_TYPE];
>>>    	/* # of allocated blocks */
>>>    	struct percpu_counter alloc_valid_block_count;
>>> +	/* # of node block writes as roll forward recovery */
>>> +	struct percpu_counter rf_node_block_count;
>>>    	/* writeback control */
>>>    	atomic_t wb_sync_req[META];	/* count # of WB_SYNC threads */
>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>>> index 93512f8859d5..0d9883457579 100644
>>> --- a/fs/f2fs/node.c
>>> +++ b/fs/f2fs/node.c
>>> @@ -1782,6 +1782,7 @@ int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
>>>    			if (!atomic || page == last_page) {
>>>    				set_fsync_mark(page, 1);
>>> +				percpu_counter_inc(&sbi->rf_node_block_count);
>>
>> if (NM_I(sbi)->max_rf_node_blocks)
>> 	percpu_counter_inc(&sbi->rf_node_block_count);
> 
> I think we can just count this and adjust right away once sysfs is changed.

Since this long recovery latency issue is a corner case, I guess we can avoid this
to save cpu time...

BTW, shouldn't we account all warn dnode blocks? as we will traverse all blocks there
in warn node list.

Thanks,

> 
>>
>> Thanks,
>>
>>>    				if (IS_INODE(page)) {
>>>    					if (is_inode_flag_set(inode,
>>>    								FI_DIRTY_INODE))
>>> @@ -3218,6 +3219,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
>>>    	nm_i->ram_thresh = DEF_RAM_THRESHOLD;
>>>    	nm_i->ra_nid_pages = DEF_RA_NID_PAGES;
>>>    	nm_i->dirty_nats_ratio = DEF_DIRTY_NAT_RATIO_THRESHOLD;
>>> +	nm_i->max_rf_node_blocks = DEF_RF_NODE_BLOCKS;
>>>    	INIT_RADIX_TREE(&nm_i->free_nid_root, GFP_ATOMIC);
>>>    	INIT_LIST_HEAD(&nm_i->free_nid_list);
>>> diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
>>> index 18b98cf0465b..4c1d34bfea78 100644
>>> --- a/fs/f2fs/node.h
>>> +++ b/fs/f2fs/node.h
>>> @@ -31,6 +31,9 @@
>>>    /* control total # of nats */
>>>    #define DEF_NAT_CACHE_THRESHOLD			100000
>>> +/* control total # of node writes used for roll-fowrad recovery */
>>> +#define DEF_RF_NODE_BLOCKS			0
>>> +
>>>    /* vector size for gang look-up from nat cache that consists of radix tree */
>>>    #define NATVEC_SIZE	64
>>>    #define SETVEC_SIZE	32
>>> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
>>> index 10d152cfa58d..1c8041fd854e 100644
>>> --- a/fs/f2fs/recovery.c
>>> +++ b/fs/f2fs/recovery.c
>>> @@ -53,9 +53,13 @@ extern struct kmem_cache *f2fs_cf_name_slab;
>>>    bool f2fs_space_for_roll_forward(struct f2fs_sb_info *sbi)
>>>    {
>>>    	s64 nalloc = percpu_counter_sum_positive(&sbi->alloc_valid_block_count);
>>> +	u32 rf_node = percpu_counter_sum_positive(&sbi->rf_node_block_count);
>>>    	if (sbi->last_valid_block_count + nalloc > sbi->user_block_count)
>>>    		return false;
>>> +	if (NM_I(sbi)->max_rf_node_blocks &&
>>> +			rf_node >= NM_I(sbi)->max_rf_node_blocks)
>>> +		return false;
>>>    	return true;
>>>    }
>>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
>>> index 281bc0133ee6..47efcf233afd 100644
>>> --- a/fs/f2fs/sysfs.c
>>> +++ b/fs/f2fs/sysfs.c
>>> @@ -732,6 +732,7 @@ F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_ssr_sections, min_ssr_sections);
>>>    F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, ram_thresh, ram_thresh);
>>>    F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, ra_nid_pages, ra_nid_pages);
>>>    F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, dirty_nats_ratio, dirty_nats_ratio);
>>> +F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, max_roll_forward_node_blocks, max_rf_node_blocks);
>>>    F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, max_victim_search, max_victim_search);
>>>    F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, migration_granularity, migration_granularity);
>>>    F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, dir_level, dir_level);
>>> @@ -855,6 +856,7 @@ static struct attribute *f2fs_attrs[] = {
>>>    	ATTR_LIST(ram_thresh),
>>>    	ATTR_LIST(ra_nid_pages),
>>>    	ATTR_LIST(dirty_nats_ratio),
>>> +	ATTR_LIST(max_roll_forward_node_blocks),
>>>    	ATTR_LIST(cp_interval),
>>>    	ATTR_LIST(idle_interval),
>>>    	ATTR_LIST(discard_idle_interval),