[PATCH RFC] f2fs: fix to avoid selecting full segment w/ {AT,}SSR allocator

[PATCH RFC] f2fs: fix to avoid selecting full segment w/ {AT,}SSR allocator

[Chao Yu]

In cp disabling mode, there could be a condition
- target segment has 128 ckpt valid blocks
- GC migrates 128 valid blocks to other segment (segment is still in
dirty list)
- GC migrates 384 blocks to target segment (segment has 128 cp_vblocks
and 384 vblocks)
- If GC selects target segment via {AT,}SSR allocator, however there is
no free space in targe segment.

Fixes: 4354994f097d ("f2fs: checkpoint disabling")
Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
 fs/f2fs/f2fs.h    |  1 +
 fs/f2fs/gc.c      | 17 +++++++++++++----
 fs/f2fs/segment.c | 20 ++++++++++++++++++++
 3 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index ed7807103c8e..9c753eff0814 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3376,6 +3376,7 @@ block_t f2fs_get_unusable_blocks(struct f2fs_sb_info *sbi);
 int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable);
 void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
 int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
+bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
 void f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
 void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
 void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 86ba8ed0b8a7..a1d8062cdace 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -392,10 +392,6 @@ static void add_victim_entry(struct f2fs_sb_info *sbi,
 		if (p->gc_mode == GC_AT &&
 			get_valid_blocks(sbi, segno, true) == 0)
 			return;
-
-		if (p->alloc_mode == AT_SSR &&
-			get_seg_entry(sbi, segno)->ckpt_valid_blocks == 0)
-			return;
 	}
 
 	for (i = 0; i < sbi->segs_per_sec; i++)
@@ -736,6 +732,19 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
 		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
 			goto next;
 
+		if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
+			/*
+			 * to avoid selecting candidate which has below valid
+			 * block distribution:
+			 * partial blocks are valid and all left ones are valid
+			 * in previous checkpoint.
+			 */
+			if (p.alloc_mode == SSR || p.alloc_mode == AT_SSR) {
+				if (!segment_has_free_slot(sbi, segno))
+					goto next;
+			}
+		}
+
 		if (is_atgc) {
 			add_victim_entry(sbi, &p, segno);
 			goto next;
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 2d5a82c4ca15..deaf57e13125 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2650,6 +2650,26 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
 		seg->next_blkoff++;
 }
 
+bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
+{
+	struct sit_info *sit = SIT_I(sbi);
+	struct seg_entry *se = get_seg_entry(sbi, segno);
+	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
+	unsigned long *target_map = SIT_I(sbi)->tmp_map;
+	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
+	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
+	int i, pos;
+
+	down_write(&sit->sentry_lock);
+	for (i = 0; i < entries; i++)
+		target_map[i] = ckpt_map[i] | cur_map[i];
+
+	pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, 0);
+	up_write(&sit->sentry_lock);
+
+	return pos < sbi->blocks_per_seg;
+}
+
 /*
  * This function always allocates a used segment(from dirty seglist) by SSR
  * manner, so it should recover the existing segment information of valid blocks
-- 
2.29.2

Re: [PATCH RFC] f2fs: fix to avoid selecting full segment w/ {AT,}SSR allocator

[Chao Yu]

Ping,

On 2021/2/20 17:40, Chao Yu wrote:
> In cp disabling mode, there could be a condition
> - target segment has 128 ckpt valid blocks
> - GC migrates 128 valid blocks to other segment (segment is still in
> dirty list)
> - GC migrates 384 blocks to target segment (segment has 128 cp_vblocks
> and 384 vblocks)
> - If GC selects target segment via {AT,}SSR allocator, however there is
> no free space in targe segment.
> 
> Fixes: 4354994f097d ("f2fs: checkpoint disabling")
> Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection")
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
>   fs/f2fs/f2fs.h    |  1 +
>   fs/f2fs/gc.c      | 17 +++++++++++++----
>   fs/f2fs/segment.c | 20 ++++++++++++++++++++
>   3 files changed, 34 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index ed7807103c8e..9c753eff0814 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -3376,6 +3376,7 @@ block_t f2fs_get_unusable_blocks(struct f2fs_sb_info *sbi);
>   int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable);
>   void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
>   int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
> +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
>   void f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
>   void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
>   void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 86ba8ed0b8a7..a1d8062cdace 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -392,10 +392,6 @@ static void add_victim_entry(struct f2fs_sb_info *sbi,
>   		if (p->gc_mode == GC_AT &&
>   			get_valid_blocks(sbi, segno, true) == 0)
>   			return;
> -
> -		if (p->alloc_mode == AT_SSR &&
> -			get_seg_entry(sbi, segno)->ckpt_valid_blocks == 0)
> -			return;
>   	}
>   
>   	for (i = 0; i < sbi->segs_per_sec; i++)
> @@ -736,6 +732,19 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>   		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>   			goto next;
>   
> +		if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
> +			/*
> +			 * to avoid selecting candidate which has below valid
> +			 * block distribution:
> +			 * partial blocks are valid and all left ones are valid
> +			 * in previous checkpoint.
> +			 */
> +			if (p.alloc_mode == SSR || p.alloc_mode == AT_SSR) {
> +				if (!segment_has_free_slot(sbi, segno))
> +					goto next;
> +			}
> +		}
> +
>   		if (is_atgc) {
>   			add_victim_entry(sbi, &p, segno);
>   			goto next;
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 2d5a82c4ca15..deaf57e13125 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2650,6 +2650,26 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
>   		seg->next_blkoff++;
>   }
>   
> +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
> +{
> +	struct sit_info *sit = SIT_I(sbi);
> +	struct seg_entry *se = get_seg_entry(sbi, segno);
> +	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
> +	unsigned long *target_map = SIT_I(sbi)->tmp_map;
> +	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
> +	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
> +	int i, pos;
> +
> +	down_write(&sit->sentry_lock);
> +	for (i = 0; i < entries; i++)
> +		target_map[i] = ckpt_map[i] | cur_map[i];
> +
> +	pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, 0);
> +	up_write(&sit->sentry_lock);
> +
> +	return pos < sbi->blocks_per_seg;
> +}
> +
>   /*
>    * This function always allocates a used segment(from dirty seglist) by SSR
>    * manner, so it should recover the existing segment information of valid blocks
> 

Re: [PATCH RFC] f2fs: fix to avoid selecting full segment w/ {AT,}SSR allocator

[Chao Yu]

Jaegeuk,

Could you please help to review this patch? since I doubt that this
issue can happen in real world... :(

Thanks,

On 2021/2/22 21:43, Chao Yu wrote:
> Ping,
> 
> On 2021/2/20 17:40, Chao Yu wrote:
>> In cp disabling mode, there could be a condition
>> - target segment has 128 ckpt valid blocks
>> - GC migrates 128 valid blocks to other segment (segment is still in
>> dirty list)
>> - GC migrates 384 blocks to target segment (segment has 128 cp_vblocks
>> and 384 vblocks)
>> - If GC selects target segment via {AT,}SSR allocator, however there is
>> no free space in targe segment.
>>
>> Fixes: 4354994f097d ("f2fs: checkpoint disabling")
>> Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection")
>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>> ---
>>    fs/f2fs/f2fs.h    |  1 +
>>    fs/f2fs/gc.c      | 17 +++++++++++++----
>>    fs/f2fs/segment.c | 20 ++++++++++++++++++++
>>    3 files changed, 34 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index ed7807103c8e..9c753eff0814 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -3376,6 +3376,7 @@ block_t f2fs_get_unusable_blocks(struct f2fs_sb_info *sbi);
>>    int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable);
>>    void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
>>    int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
>> +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
>>    void f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
>>    void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
>>    void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index 86ba8ed0b8a7..a1d8062cdace 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -392,10 +392,6 @@ static void add_victim_entry(struct f2fs_sb_info *sbi,
>>    		if (p->gc_mode == GC_AT &&
>>    			get_valid_blocks(sbi, segno, true) == 0)
>>    			return;
>> -
>> -		if (p->alloc_mode == AT_SSR &&
>> -			get_seg_entry(sbi, segno)->ckpt_valid_blocks == 0)
>> -			return;
>>    	}
>>    
>>    	for (i = 0; i < sbi->segs_per_sec; i++)
>> @@ -736,6 +732,19 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>    		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>>    			goto next;
>>    
>> +		if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
>> +			/*
>> +			 * to avoid selecting candidate which has below valid
>> +			 * block distribution:
>> +			 * partial blocks are valid and all left ones are valid
>> +			 * in previous checkpoint.
>> +			 */
>> +			if (p.alloc_mode == SSR || p.alloc_mode == AT_SSR) {
>> +				if (!segment_has_free_slot(sbi, segno))
>> +					goto next;
>> +			}
>> +		}
>> +
>>    		if (is_atgc) {
>>    			add_victim_entry(sbi, &p, segno);
>>    			goto next;
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 2d5a82c4ca15..deaf57e13125 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -2650,6 +2650,26 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
>>    		seg->next_blkoff++;
>>    }
>>    
>> +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
>> +{
>> +	struct sit_info *sit = SIT_I(sbi);
>> +	struct seg_entry *se = get_seg_entry(sbi, segno);
>> +	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
>> +	unsigned long *target_map = SIT_I(sbi)->tmp_map;
>> +	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
>> +	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
>> +	int i, pos;
>> +
>> +	down_write(&sit->sentry_lock);
>> +	for (i = 0; i < entries; i++)
>> +		target_map[i] = ckpt_map[i] | cur_map[i];
>> +
>> +	pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, 0);
>> +	up_write(&sit->sentry_lock);
>> +
>> +	return pos < sbi->blocks_per_seg;
>> +}
>> +
>>    /*
>>     * This function always allocates a used segment(from dirty seglist) by SSR
>>     * manner, so it should recover the existing segment information of valid blocks
>>
> .
> 

Re: [PATCH RFC] f2fs: fix to avoid selecting full segment w/ {AT,}SSR allocator

[Jaegeuk Kim]

On 02/23, Chao Yu wrote:
> Jaegeuk,
> 
> Could you please help to review this patch? since I doubt that this
> issue can happen in real world... :(

Let me take a look as soon as I have some time. Sorry for the delay.

> 
> Thanks,
> 
> On 2021/2/22 21:43, Chao Yu wrote:
> > Ping,
> > 
> > On 2021/2/20 17:40, Chao Yu wrote:
> > > In cp disabling mode, there could be a condition
> > > - target segment has 128 ckpt valid blocks
> > > - GC migrates 128 valid blocks to other segment (segment is still in
> > > dirty list)
> > > - GC migrates 384 blocks to target segment (segment has 128 cp_vblocks
> > > and 384 vblocks)
> > > - If GC selects target segment via {AT,}SSR allocator, however there is
> > > no free space in targe segment.
> > > 
> > > Fixes: 4354994f097d ("f2fs: checkpoint disabling")
> > > Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection")
> > > Signed-off-by: Chao Yu <yuchao0@huawei.com>
> > > ---
> > >    fs/f2fs/f2fs.h    |  1 +
> > >    fs/f2fs/gc.c      | 17 +++++++++++++----
> > >    fs/f2fs/segment.c | 20 ++++++++++++++++++++
> > >    3 files changed, 34 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > > index ed7807103c8e..9c753eff0814 100644
> > > --- a/fs/f2fs/f2fs.h
> > > +++ b/fs/f2fs/f2fs.h
> > > @@ -3376,6 +3376,7 @@ block_t f2fs_get_unusable_blocks(struct f2fs_sb_info *sbi);
> > >    int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable);
> > >    void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
> > >    int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
> > > +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
> > >    void f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
> > >    void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
> > >    void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
> > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > > index 86ba8ed0b8a7..a1d8062cdace 100644
> > > --- a/fs/f2fs/gc.c
> > > +++ b/fs/f2fs/gc.c
> > > @@ -392,10 +392,6 @@ static void add_victim_entry(struct f2fs_sb_info *sbi,
> > >    		if (p->gc_mode == GC_AT &&
> > >    			get_valid_blocks(sbi, segno, true) == 0)
> > >    			return;
> > > -
> > > -		if (p->alloc_mode == AT_SSR &&
> > > -			get_seg_entry(sbi, segno)->ckpt_valid_blocks == 0)
> > > -			return;
> > >    	}
> > >    	for (i = 0; i < sbi->segs_per_sec; i++)
> > > @@ -736,6 +732,19 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> > >    		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
> > >    			goto next;
> > > +		if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
> > > +			/*
> > > +			 * to avoid selecting candidate which has below valid
> > > +			 * block distribution:
> > > +			 * partial blocks are valid and all left ones are valid
> > > +			 * in previous checkpoint.
> > > +			 */
> > > +			if (p.alloc_mode == SSR || p.alloc_mode == AT_SSR) {
> > > +				if (!segment_has_free_slot(sbi, segno))
> > > +					goto next;
> > > +			}
> > > +		}
> > > +
> > >    		if (is_atgc) {
> > >    			add_victim_entry(sbi, &p, segno);
> > >    			goto next;
> > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > > index 2d5a82c4ca15..deaf57e13125 100644
> > > --- a/fs/f2fs/segment.c
> > > +++ b/fs/f2fs/segment.c
> > > @@ -2650,6 +2650,26 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
> > >    		seg->next_blkoff++;
> > >    }
> > > +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
> > > +{
> > > +	struct sit_info *sit = SIT_I(sbi);
> > > +	struct seg_entry *se = get_seg_entry(sbi, segno);
> > > +	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
> > > +	unsigned long *target_map = SIT_I(sbi)->tmp_map;
> > > +	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
> > > +	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
> > > +	int i, pos;
> > > +
> > > +	down_write(&sit->sentry_lock);
> > > +	for (i = 0; i < entries; i++)
> > > +		target_map[i] = ckpt_map[i] | cur_map[i];
> > > +
> > > +	pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, 0);
> > > +	up_write(&sit->sentry_lock);
> > > +
> > > +	return pos < sbi->blocks_per_seg;
> > > +}
> > > +
> > >    /*
> > >     * This function always allocates a used segment(from dirty seglist) by SSR
> > >     * manner, so it should recover the existing segment information of valid blocks
> > > 
> > .
> > 

Re: [PATCH RFC] f2fs: fix to avoid selecting full segment w/ {AT,}SSR allocator

[Jaegeuk Kim]

On 02/20, Chao Yu wrote:
> In cp disabling mode, there could be a condition
> - target segment has 128 ckpt valid blocks
> - GC migrates 128 valid blocks to other segment (segment is still in
> dirty list)
> - GC migrates 384 blocks to target segment (segment has 128 cp_vblocks
> and 384 vblocks)
> - If GC selects target segment via {AT,}SSR allocator, however there is
> no free space in targe segment.
> 
> Fixes: 4354994f097d ("f2fs: checkpoint disabling")
> Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection")
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
>  fs/f2fs/f2fs.h    |  1 +
>  fs/f2fs/gc.c      | 17 +++++++++++++----
>  fs/f2fs/segment.c | 20 ++++++++++++++++++++
>  3 files changed, 34 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index ed7807103c8e..9c753eff0814 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -3376,6 +3376,7 @@ block_t f2fs_get_unusable_blocks(struct f2fs_sb_info *sbi);
>  int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable);
>  void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
>  int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
> +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
>  void f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
>  void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
>  void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 86ba8ed0b8a7..a1d8062cdace 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -392,10 +392,6 @@ static void add_victim_entry(struct f2fs_sb_info *sbi,
>  		if (p->gc_mode == GC_AT &&
>  			get_valid_blocks(sbi, segno, true) == 0)
>  			return;
> -
> -		if (p->alloc_mode == AT_SSR &&
> -			get_seg_entry(sbi, segno)->ckpt_valid_blocks == 0)
> -			return;
>  	}
>  
>  	for (i = 0; i < sbi->segs_per_sec; i++)
> @@ -736,6 +732,19 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>  		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>  			goto next;
>  
> +		if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
> +			/*
> +			 * to avoid selecting candidate which has below valid
> +			 * block distribution:
> +			 * partial blocks are valid and all left ones are valid
> +			 * in previous checkpoint.
> +			 */
> +			if (p.alloc_mode == SSR || p.alloc_mode == AT_SSR) {
> +				if (!segment_has_free_slot(sbi, segno))
> +					goto next;

Do we need to change this to check free_slot instead of get_ckpt_valid_blocks()?

 732                 if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
 733                                         get_ckpt_valid_blocks(sbi, segno) &&
 734                                         p.alloc_mode == LFS))


> +			}
> +		}
> +
>  		if (is_atgc) {
>  			add_victim_entry(sbi, &p, segno);
>  			goto next;
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 2d5a82c4ca15..deaf57e13125 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2650,6 +2650,26 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
>  		seg->next_blkoff++;
>  }
>  
> +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
> +{
> +	struct sit_info *sit = SIT_I(sbi);
> +	struct seg_entry *se = get_seg_entry(sbi, segno);
> +	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
> +	unsigned long *target_map = SIT_I(sbi)->tmp_map;
> +	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
> +	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
> +	int i, pos;
> +
> +	down_write(&sit->sentry_lock);
> +	for (i = 0; i < entries; i++)
> +		target_map[i] = ckpt_map[i] | cur_map[i];
> +
> +	pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, 0);
> +	up_write(&sit->sentry_lock);
> +
> +	return pos < sbi->blocks_per_seg;
> +}
> +
>  /*
>   * This function always allocates a used segment(from dirty seglist) by SSR
>   * manner, so it should recover the existing segment information of valid blocks
> -- 
> 2.29.2

Re: [PATCH RFC] f2fs: fix to avoid selecting full segment w/ {AT,}SSR allocator

[Chao Yu]

On 2021/3/19 1:17, Jaegeuk Kim wrote:
> On 02/20, Chao Yu wrote:
>> In cp disabling mode, there could be a condition
>> - target segment has 128 ckpt valid blocks
>> - GC migrates 128 valid blocks to other segment (segment is still in
>> dirty list)
>> - GC migrates 384 blocks to target segment (segment has 128 cp_vblocks
>> and 384 vblocks)
>> - If GC selects target segment via {AT,}SSR allocator, however there is
>> no free space in targe segment.
>>
>> Fixes: 4354994f097d ("f2fs: checkpoint disabling")
>> Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection")
>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>> ---
>>   fs/f2fs/f2fs.h    |  1 +
>>   fs/f2fs/gc.c      | 17 +++++++++++++----
>>   fs/f2fs/segment.c | 20 ++++++++++++++++++++
>>   3 files changed, 34 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index ed7807103c8e..9c753eff0814 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -3376,6 +3376,7 @@ block_t f2fs_get_unusable_blocks(struct f2fs_sb_info *sbi);
>>   int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable);
>>   void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
>>   int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
>> +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
>>   void f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
>>   void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
>>   void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index 86ba8ed0b8a7..a1d8062cdace 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -392,10 +392,6 @@ static void add_victim_entry(struct f2fs_sb_info *sbi,
>>   		if (p->gc_mode == GC_AT &&
>>   			get_valid_blocks(sbi, segno, true) == 0)
>>   			return;
>> -
>> -		if (p->alloc_mode == AT_SSR &&
>> -			get_seg_entry(sbi, segno)->ckpt_valid_blocks == 0)
>> -			return;
>>   	}
>>   
>>   	for (i = 0; i < sbi->segs_per_sec; i++)
>> @@ -736,6 +732,19 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>   		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>>   			goto next;
>>   
>> +		if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
>> +			/*
>> +			 * to avoid selecting candidate which has below valid
>> +			 * block distribution:
>> +			 * partial blocks are valid and all left ones are valid
>> +			 * in previous checkpoint.
>> +			 */
>> +			if (p.alloc_mode == SSR || p.alloc_mode == AT_SSR) {
>> +				if (!segment_has_free_slot(sbi, segno))
>> +					goto next;
> 
> Do we need to change this to check free_slot instead of get_ckpt_valid_blocks()?

Jaegeuk,

LFS was assigned only for GC case, in this case we are trying to select source
section, rather than target segment for SSR/AT_SSR case, so we don't need to
check free_slot.

- f2fs_gc
  - __get_victim
   - get_victim(sbi, victim, gc_type, NO_CHECK_TYPE, LFS, 0);

> 
>   732                 if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
>   733                                         get_ckpt_valid_blocks(sbi, segno) &&
>   734                                         p.alloc_mode == LFS))

BTW, in LFS mode, GC wants to find source section rather than segment, so we
should change to check valid ckpt blocks in every segment of targe section here?

Thanks,

> 
> 
>> +			}
>> +		}
>> +
>>   		if (is_atgc) {
>>   			add_victim_entry(sbi, &p, segno);
>>   			goto next;
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 2d5a82c4ca15..deaf57e13125 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -2650,6 +2650,26 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
>>   		seg->next_blkoff++;
>>   }
>>   
>> +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
>> +{
>> +	struct sit_info *sit = SIT_I(sbi);
>> +	struct seg_entry *se = get_seg_entry(sbi, segno);
>> +	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
>> +	unsigned long *target_map = SIT_I(sbi)->tmp_map;
>> +	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
>> +	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
>> +	int i, pos;
>> +
>> +	down_write(&sit->sentry_lock);
>> +	for (i = 0; i < entries; i++)
>> +		target_map[i] = ckpt_map[i] | cur_map[i];
>> +
>> +	pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, 0);
>> +	up_write(&sit->sentry_lock);
>> +
>> +	return pos < sbi->blocks_per_seg;
>> +}
>> +
>>   /*
>>    * This function always allocates a used segment(from dirty seglist) by SSR
>>    * manner, so it should recover the existing segment information of valid blocks
>> -- 
>> 2.29.2
> .
> 

Re: [PATCH RFC] f2fs: fix to avoid selecting full segment w/ {AT,}SSR allocator

[Jaegeuk Kim]

On 03/19, Chao Yu wrote:
> On 2021/3/19 1:17, Jaegeuk Kim wrote:
> > On 02/20, Chao Yu wrote:
> > > In cp disabling mode, there could be a condition
> > > - target segment has 128 ckpt valid blocks
> > > - GC migrates 128 valid blocks to other segment (segment is still in
> > > dirty list)
> > > - GC migrates 384 blocks to target segment (segment has 128 cp_vblocks
> > > and 384 vblocks)
> > > - If GC selects target segment via {AT,}SSR allocator, however there is
> > > no free space in targe segment.
> > > 
> > > Fixes: 4354994f097d ("f2fs: checkpoint disabling")
> > > Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection")
> > > Signed-off-by: Chao Yu <yuchao0@huawei.com>
> > > ---
> > >   fs/f2fs/f2fs.h    |  1 +
> > >   fs/f2fs/gc.c      | 17 +++++++++++++----
> > >   fs/f2fs/segment.c | 20 ++++++++++++++++++++
> > >   3 files changed, 34 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > > index ed7807103c8e..9c753eff0814 100644
> > > --- a/fs/f2fs/f2fs.h
> > > +++ b/fs/f2fs/f2fs.h
> > > @@ -3376,6 +3376,7 @@ block_t f2fs_get_unusable_blocks(struct f2fs_sb_info *sbi);
> > >   int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable);
> > >   void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
> > >   int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
> > > +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
> > >   void f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
> > >   void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
> > >   void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
> > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > > index 86ba8ed0b8a7..a1d8062cdace 100644
> > > --- a/fs/f2fs/gc.c
> > > +++ b/fs/f2fs/gc.c
> > > @@ -392,10 +392,6 @@ static void add_victim_entry(struct f2fs_sb_info *sbi,
> > >   		if (p->gc_mode == GC_AT &&
> > >   			get_valid_blocks(sbi, segno, true) == 0)
> > >   			return;
> > > -
> > > -		if (p->alloc_mode == AT_SSR &&
> > > -			get_seg_entry(sbi, segno)->ckpt_valid_blocks == 0)
> > > -			return;
> > >   	}
> > >   	for (i = 0; i < sbi->segs_per_sec; i++)
> > > @@ -736,6 +732,19 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> > >   		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
> > >   			goto next;
> > > +		if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
> > > +			/*
> > > +			 * to avoid selecting candidate which has below valid
> > > +			 * block distribution:
> > > +			 * partial blocks are valid and all left ones are valid
> > > +			 * in previous checkpoint.
> > > +			 */
> > > +			if (p.alloc_mode == SSR || p.alloc_mode == AT_SSR) {
> > > +				if (!segment_has_free_slot(sbi, segno))
> > > +					goto next;
> > 
> > Do we need to change this to check free_slot instead of get_ckpt_valid_blocks()?
> 
> Jaegeuk,
> 
> LFS was assigned only for GC case, in this case we are trying to select source
> section, rather than target segment for SSR/AT_SSR case, so we don't need to
> check free_slot.
> 
> - f2fs_gc
>  - __get_victim
>   - get_victim(sbi, victim, gc_type, NO_CHECK_TYPE, LFS, 0);
> 
> > 
> >   732                 if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
> >   733                                         get_ckpt_valid_blocks(sbi, segno) &&
> >   734                                         p.alloc_mode == LFS))
> 
> BTW, in LFS mode, GC wants to find source section rather than segment, so we
> should change to check valid ckpt blocks in every segment of targe section here?

Alright. I refactored a bit on this patch with new one. Could you please take a look?

https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git/commit/?h=dev&id=00152bd7cabd69b4615ebead823ff23887b0e0f7

Thanks,

> 
> Thanks,
> 
> > 
> > 
> > > +			}
> > > +		}
> > > +
> > >   		if (is_atgc) {
> > >   			add_victim_entry(sbi, &p, segno);
> > >   			goto next;
> > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > > index 2d5a82c4ca15..deaf57e13125 100644
> > > --- a/fs/f2fs/segment.c
> > > +++ b/fs/f2fs/segment.c
> > > @@ -2650,6 +2650,26 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
> > >   		seg->next_blkoff++;
> > >   }
> > > +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
> > > +{
> > > +	struct sit_info *sit = SIT_I(sbi);
> > > +	struct seg_entry *se = get_seg_entry(sbi, segno);
> > > +	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
> > > +	unsigned long *target_map = SIT_I(sbi)->tmp_map;
> > > +	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
> > > +	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
> > > +	int i, pos;
> > > +
> > > +	down_write(&sit->sentry_lock);
> > > +	for (i = 0; i < entries; i++)
> > > +		target_map[i] = ckpt_map[i] | cur_map[i];
> > > +
> > > +	pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, 0);
> > > +	up_write(&sit->sentry_lock);
> > > +
> > > +	return pos < sbi->blocks_per_seg;
> > > +}
> > > +
> > >   /*
> > >    * This function always allocates a used segment(from dirty seglist) by SSR
> > >    * manner, so it should recover the existing segment information of valid blocks
> > > -- 
> > > 2.29.2
> > .
> > 

Re: [PATCH RFC] f2fs: fix to avoid selecting full segment w/ {AT,}SSR allocator

[Chao Yu]

On 2021/3/24 6:59, Jaegeuk Kim wrote:
> On 03/19, Chao Yu wrote:
>> On 2021/3/19 1:17, Jaegeuk Kim wrote:
>>> On 02/20, Chao Yu wrote:
>>>> In cp disabling mode, there could be a condition
>>>> - target segment has 128 ckpt valid blocks
>>>> - GC migrates 128 valid blocks to other segment (segment is still in
>>>> dirty list)
>>>> - GC migrates 384 blocks to target segment (segment has 128 cp_vblocks
>>>> and 384 vblocks)
>>>> - If GC selects target segment via {AT,}SSR allocator, however there is
>>>> no free space in targe segment.
>>>>
>>>> Fixes: 4354994f097d ("f2fs: checkpoint disabling")
>>>> Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection")
>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>> ---
>>>>    fs/f2fs/f2fs.h    |  1 +
>>>>    fs/f2fs/gc.c      | 17 +++++++++++++----
>>>>    fs/f2fs/segment.c | 20 ++++++++++++++++++++
>>>>    3 files changed, 34 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>> index ed7807103c8e..9c753eff0814 100644
>>>> --- a/fs/f2fs/f2fs.h
>>>> +++ b/fs/f2fs/f2fs.h
>>>> @@ -3376,6 +3376,7 @@ block_t f2fs_get_unusable_blocks(struct f2fs_sb_info *sbi);
>>>>    int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable);
>>>>    void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
>>>>    int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
>>>> +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
>>>>    void f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
>>>>    void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
>>>>    void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>>> index 86ba8ed0b8a7..a1d8062cdace 100644
>>>> --- a/fs/f2fs/gc.c
>>>> +++ b/fs/f2fs/gc.c
>>>> @@ -392,10 +392,6 @@ static void add_victim_entry(struct f2fs_sb_info *sbi,
>>>>    		if (p->gc_mode == GC_AT &&
>>>>    			get_valid_blocks(sbi, segno, true) == 0)
>>>>    			return;
>>>> -
>>>> -		if (p->alloc_mode == AT_SSR &&
>>>> -			get_seg_entry(sbi, segno)->ckpt_valid_blocks == 0)
>>>> -			return;
>>>>    	}
>>>>    	for (i = 0; i < sbi->segs_per_sec; i++)
>>>> @@ -736,6 +732,19 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>>>    		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>>>>    			goto next;
>>>> +		if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
>>>> +			/*
>>>> +			 * to avoid selecting candidate which has below valid
>>>> +			 * block distribution:
>>>> +			 * partial blocks are valid and all left ones are valid
>>>> +			 * in previous checkpoint.
>>>> +			 */
>>>> +			if (p.alloc_mode == SSR || p.alloc_mode == AT_SSR) {
>>>> +				if (!segment_has_free_slot(sbi, segno))
>>>> +					goto next;
>>>
>>> Do we need to change this to check free_slot instead of get_ckpt_valid_blocks()?
>>
>> Jaegeuk,
>>
>> LFS was assigned only for GC case, in this case we are trying to select source
>> section, rather than target segment for SSR/AT_SSR case, so we don't need to
>> check free_slot.
>>
>> - f2fs_gc
>>   - __get_victim
>>    - get_victim(sbi, victim, gc_type, NO_CHECK_TYPE, LFS, 0);
>>
>>>
>>>    732                 if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
>>>    733                                         get_ckpt_valid_blocks(sbi, segno) &&
>>>    734                                         p.alloc_mode == LFS))
>>
>> BTW, in LFS mode, GC wants to find source section rather than segment, so we
>> should change to check valid ckpt blocks in every segment of targe section here?
> 
> Alright. I refactored a bit on this patch with new one. Could you please take a look?
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git/commit/?h=dev&id=00152bd7cabd69b4615ebead823ff23887b0e0f7

I see, newly added comment looks good to me.

One more concern is commit title and commit message is out-of-update,
I've revised it in v2:

https://lore.kernel.org/linux-f2fs-devel/20210324031828.67133-1-yuchao0@huawei.com/T/#u

Thanks,

> 
> Thanks,
> 
>>
>> Thanks,
>>
>>>
>>>
>>>> +			}
>>>> +		}
>>>> +
>>>>    		if (is_atgc) {
>>>>    			add_victim_entry(sbi, &p, segno);
>>>>    			goto next;
>>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>>> index 2d5a82c4ca15..deaf57e13125 100644
>>>> --- a/fs/f2fs/segment.c
>>>> +++ b/fs/f2fs/segment.c
>>>> @@ -2650,6 +2650,26 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
>>>>    		seg->next_blkoff++;
>>>>    }
>>>> +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
>>>> +{
>>>> +	struct sit_info *sit = SIT_I(sbi);
>>>> +	struct seg_entry *se = get_seg_entry(sbi, segno);
>>>> +	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
>>>> +	unsigned long *target_map = SIT_I(sbi)->tmp_map;
>>>> +	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
>>>> +	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
>>>> +	int i, pos;
>>>> +
>>>> +	down_write(&sit->sentry_lock);
>>>> +	for (i = 0; i < entries; i++)
>>>> +		target_map[i] = ckpt_map[i] | cur_map[i];
>>>> +
>>>> +	pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, 0);
>>>> +	up_write(&sit->sentry_lock);
>>>> +
>>>> +	return pos < sbi->blocks_per_seg;
>>>> +}
>>>> +
>>>>    /*
>>>>     * This function always allocates a used segment(from dirty seglist) by SSR
>>>>     * manner, so it should recover the existing segment information of valid blocks
>>>> -- 
>>>> 2.29.2
>>> .
>>>
> .
>