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[PATCH] f2fs: fix to update user block counts in block_operations()

Chao Yu posted 1 patch 1 year, 3 months ago
There is a newer version of this series
fs/f2fs/checkpoint.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
[PATCH] f2fs: fix to update user block counts in block_operations()
Posted by Chao Yu 1 year, 3 months ago 
Commit 59c9081bc86e ("f2fs: allow write page cache when writting cp")
allows write() to write data to page cache during checkpoint, so block
count fields like .total_valid_block_count, .alloc_valid_block_count
and .rf_node_block_count may encounter race condition as below:

CP				Thread A
- write_checkpoint
 - block_operations
  - f2fs_down_write(&sbi->node_change)
  - __prepare_cp_block
  : ckpt->valid_block_count = .total_valid_block_count
  - f2fs_up_write(&sbi->node_change)
				- write
				 - f2fs_preallocate_blocks
				  - f2fs_map_blocks(,F2FS_GET_BLOCK_PRE_AIO)
				   - f2fs_map_lock
				    - f2fs_down_read(&sbi->node_change)
				   - f2fs_reserve_new_blocks
				    - inc_valid_block_count
				    : percpu_counter_add(&sbi->alloc_valid_block_count, count)
				    : sbi->total_valid_block_count += count
				    - f2fs_up_read(&sbi->node_change)
 - do_checkpoint
 : 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)
				- fsync
				 - need_do_checkpoint
				  - f2fs_space_for_roll_forward
				  : alloc_valid_block_count was reset to zero,
				    so, it may missed last data during checkpoint

Let's change to update .total_valid_block_count, .alloc_valid_block_count
and .rf_node_block_count in block_operations(), then their access can be
protected by .node_change and .cp_rwsem lock, so that it can avoid above
race condition.

Fixes: 59c9081bc86e ("f2fs: allow write page cache when writting cp")
Cc: Yunlei He <heyunlei@oppo.com>
Signed-off-by: Chao Yu <chao@kernel.org>
---
 fs/f2fs/checkpoint.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 66eaad591b60..010bbd5af211 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1298,6 +1298,12 @@ static int block_operations(struct f2fs_sb_info *sbi)
 	 * dirty node blocks and some checkpoint values by block allocation.
 	 */
 	__prepare_cp_block(sbi);
+
+	/* 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);
+
 	f2fs_up_write(&sbi->node_change);
 	return err;
 }
@@ -1575,11 +1581,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 		start_blk += NR_CURSEG_NODE_TYPE;
 	}
 
-	/* 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);
 	/* Wait for all dirty meta pages to be submitted for IO */
-- 
2.40.1
Re: [PATCH] f2fs: fix to update user block counts in block_operations()
Posted by Jaegeuk Kim 1 year, 3 months ago 
On 06/06, Chao Yu wrote:
> Commit 59c9081bc86e ("f2fs: allow write page cache when writting cp")
> allows write() to write data to page cache during checkpoint, so block
> count fields like .total_valid_block_count, .alloc_valid_block_count
> and .rf_node_block_count may encounter race condition as below:
> 
> CP				Thread A
> - write_checkpoint
>  - block_operations
>   - f2fs_down_write(&sbi->node_change)
>   - __prepare_cp_block
>   : ckpt->valid_block_count = .total_valid_block_count
>   - f2fs_up_write(&sbi->node_change)
> 				- write
> 				 - f2fs_preallocate_blocks
> 				  - f2fs_map_blocks(,F2FS_GET_BLOCK_PRE_AIO)
> 				   - f2fs_map_lock
> 				    - f2fs_down_read(&sbi->node_change)
> 				   - f2fs_reserve_new_blocks
> 				    - inc_valid_block_count
> 				    : percpu_counter_add(&sbi->alloc_valid_block_count, count)
> 				    : sbi->total_valid_block_count += count
> 				    - f2fs_up_read(&sbi->node_change)
>  - do_checkpoint
>  : 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)
> 				- fsync
> 				 - need_do_checkpoint
> 				  - f2fs_space_for_roll_forward
> 				  : alloc_valid_block_count was reset to zero,
> 				    so, it may missed last data during checkpoint
> 
> Let's change to update .total_valid_block_count, .alloc_valid_block_count
> and .rf_node_block_count in block_operations(), then their access can be
> protected by .node_change and .cp_rwsem lock, so that it can avoid above
> race condition.
> 
> Fixes: 59c9081bc86e ("f2fs: allow write page cache when writting cp")
> Cc: Yunlei He <heyunlei@oppo.com>
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
>  fs/f2fs/checkpoint.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 66eaad591b60..010bbd5af211 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -1298,6 +1298,12 @@ static int block_operations(struct f2fs_sb_info *sbi)
>  	 * dirty node blocks and some checkpoint values by block allocation.
>  	 */
>  	__prepare_cp_block(sbi);
> +
> +	/* 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);

Need to add this in __prepare_cp_block()?

> +
>  	f2fs_up_write(&sbi->node_change);
>  	return err;
>  }
> @@ -1575,11 +1581,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  		start_blk += NR_CURSEG_NODE_TYPE;
>  	}
>  
> -	/* 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);
>  	/* Wait for all dirty meta pages to be submitted for IO */
> -- 
> 2.40.1
>
Re: [PATCH] f2fs: fix to update user block counts in block_operations()
Posted by Chao Yu 1 year, 3 months ago 
On 2024/6/25 1:53, Jaegeuk Kim wrote:
> On 06/06, Chao Yu wrote:
>> Commit 59c9081bc86e ("f2fs: allow write page cache when writting cp")
>> allows write() to write data to page cache during checkpoint, so block
>> count fields like .total_valid_block_count, .alloc_valid_block_count
>> and .rf_node_block_count may encounter race condition as below:
>>
>> CP				Thread A
>> - write_checkpoint
>>   - block_operations
>>    - f2fs_down_write(&sbi->node_change)
>>    - __prepare_cp_block
>>    : ckpt->valid_block_count = .total_valid_block_count
>>    - f2fs_up_write(&sbi->node_change)
>> 				- write
>> 				 - f2fs_preallocate_blocks
>> 				  - f2fs_map_blocks(,F2FS_GET_BLOCK_PRE_AIO)
>> 				   - f2fs_map_lock
>> 				    - f2fs_down_read(&sbi->node_change)
>> 				   - f2fs_reserve_new_blocks
>> 				    - inc_valid_block_count
>> 				    : percpu_counter_add(&sbi->alloc_valid_block_count, count)
>> 				    : sbi->total_valid_block_count += count
>> 				    - f2fs_up_read(&sbi->node_change)
>>   - do_checkpoint
>>   : 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)
>> 				- fsync
>> 				 - need_do_checkpoint
>> 				  - f2fs_space_for_roll_forward
>> 				  : alloc_valid_block_count was reset to zero,
>> 				    so, it may missed last data during checkpoint
>>
>> Let's change to update .total_valid_block_count, .alloc_valid_block_count
>> and .rf_node_block_count in block_operations(), then their access can be
>> protected by .node_change and .cp_rwsem lock, so that it can avoid above
>> race condition.
>>
>> Fixes: 59c9081bc86e ("f2fs: allow write page cache when writting cp")
>> Cc: Yunlei He <heyunlei@oppo.com>
>> Signed-off-by: Chao Yu <chao@kernel.org>
>> ---
>>   fs/f2fs/checkpoint.c | 11 ++++++-----
>>   1 file changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>> index 66eaad591b60..010bbd5af211 100644
>> --- a/fs/f2fs/checkpoint.c
>> +++ b/fs/f2fs/checkpoint.c
>> @@ -1298,6 +1298,12 @@ static int block_operations(struct f2fs_sb_info *sbi)
>>   	 * dirty node blocks and some checkpoint values by block allocation.
>>   	 */
>>   	__prepare_cp_block(sbi);
>> +
>> +	/* 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);
> 
> Need to add this in __prepare_cp_block()?

Fine to me, will update in v2.

Thanks,

> 
>> +
>>   	f2fs_up_write(&sbi->node_change);
>>   	return err;
>>   }
>> @@ -1575,11 +1581,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>>   		start_blk += NR_CURSEG_NODE_TYPE;
>>   	}
>>   
>> -	/* 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);
>>   	/* Wait for all dirty meta pages to be submitted for IO */
>> -- 
>> 2.40.1
>>

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