Re: [PATCH] f2fs: fix to trigger a checkpoint in the end of foreground garbage collection

[Chao Yu <chao@kernel.org>]

On 2023/4/4 2:13, Jaegeuk Kim wrote:
> On 03/24, Chao Yu wrote:
>> In order to reclaim free blocks in prefree sections before latter use.
> 
> We were supposed to do checkpoint as is?

It seems commit 6f8d4455060d ("f2fs: avoid fi->i_gc_rwsem[WRITE] lock in f2fs_gc")
changed that logic? It caused that if has_not_enough_free_secs() returns false,
it missed to call f2fs_write_checkpoint() before exit f2fs_gc()?

@@ -1110,15 +1116,23 @@ gc_more:
  	if (gc_type == FG_GC)
  		sbi->cur_victim_sec = NULL_SEGNO;

-	if (!sync) {
-		if (has_not_enough_free_secs(sbi, sec_freed, 0)) {
-			if (skipped_round > MAX_SKIP_ATOMIC_COUNT &&
-				skipped_round * 2 >= round)
-				f2fs_drop_inmem_pages_all(sbi, true);
+	if (sync)
+		goto stop;
+
+	if (has_not_enough_free_secs(sbi, sec_freed, 0)) {
+		if (skipped_round <= MAX_SKIP_GC_COUNT ||
+					skipped_round * 2 < round) {
  			segno = NULL_SEGNO;
  			goto gc_more;
  		}

+		if (first_skipped < last_skipped &&
+				(last_skipped - first_skipped) >
+						sbi->skipped_gc_rwsem) {
+			f2fs_drop_inmem_pages_all(sbi, true);
+			segno = NULL_SEGNO;
+			goto gc_more;
+		}
  		if (gc_type == FG_GC)
  			ret = f2fs_write_checkpoint(sbi, &cpc);
  	}

> 
>>
>> Fixes: 6f8d4455060d ("f2fs: avoid fi->i_gc_rwsem[WRITE] lock in f2fs_gc")
>> Signed-off-by: Chao Yu <chao@kernel.org>
>> ---
>>   fs/f2fs/f2fs.h    | 1 +
>>   fs/f2fs/gc.c      | 8 ++++++++
>>   fs/f2fs/segment.c | 1 +
>>   3 files changed, 10 insertions(+)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 53a005b420cf..b1515375cb4c 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -1269,6 +1269,7 @@ struct f2fs_gc_control {
>>   	unsigned int victim_segno;	/* target victim segment number */
>>   	int init_gc_type;		/* FG_GC or BG_GC */
>>   	bool no_bg_gc;			/* check the space and stop bg_gc */
>> +	bool reclaim_space;		/* trigger checkpoint to reclaim space */
>>   	bool should_migrate_blocks;	/* should migrate blocks */
>>   	bool err_gc_skipped;		/* return EAGAIN if GC skipped */
>>   	unsigned int nr_free_secs;	/* # of free sections to do GC */
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index 2996d38aa89c..5a451d3d512d 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -132,6 +132,7 @@ static int gc_thread_func(void *data)
>>   
>>   		gc_control.init_gc_type = sync_mode ? FG_GC : BG_GC;
>>   		gc_control.no_bg_gc = foreground;
>> +		gc_control.reclaim_space = foreground;
>>   		gc_control.nr_free_secs = foreground ? 1 : 0;
>>   
>>   		/* if return value is not zero, no victim was selected */
>> @@ -1880,6 +1881,13 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control)
>>   				(gc_type == FG_GC) ? sec_freed : 0, 0)) {
>>   		if (gc_type == FG_GC && sec_freed < gc_control->nr_free_secs)
>>   			goto go_gc_more;
>> +
>> +		/*
>> +		 * trigger a checkpoint in the end of foreground garbage
>> +		 * collection.
>> +		 */
>> +		if (gc_control->reclaim_space)
>> +			ret = f2fs_write_checkpoint(sbi, &cpc);
>>   		goto stop;
>>   	}
>>   
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 6c11789da884..b62af2ae1685 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -421,6 +421,7 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
>>   				.victim_segno = NULL_SEGNO,
>>   				.init_gc_type = BG_GC,
>>   				.no_bg_gc = true,
>> +				.reclaim_space = true,
>>   				.should_migrate_blocks = false,
>>   				.err_gc_skipped = false,
>>   				.nr_free_secs = 1 };
>> -- 
>> 2.25.1