linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: fix to update user block counts in block

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Message-Id: 
 <172105443231.17443.11007255777614226894.git-patchwork-notify@kernel.org>
Date: Mon, 15 Jul 2024 14:40:32 +0000
From: patchwork-bot+f2fs@...nel.org
To: Chao Yu <chao@...nel.org>
Cc: jaegeuk@...nel.org, linux-kernel@...r.kernel.org,
 linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: fix to update user block counts in
 block_operations()

Hello:

This patch was applied to jaegeuk/f2fs.git (dev)
by Jaegeuk Kim <jaegeuk@...nel.org>:

On Tue, 25 Jun 2024 10:32:39 +0800 you 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
> 
> [...]

Here is the summary with links:
  - [f2fs-dev,v2] f2fs: fix to update user block counts in block_operations()
    https://git.kernel.org/jaegeuk/f2fs/c/f06c0f82e38b

You are awesome, thank you!
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