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Date: Sat, 13 Jan 2024 10:33:54 +0800
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Subject: Re: [PATCH v4 2/6] f2fs: compress: fix to cover normal cluster write
 with cp_rwsem
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To: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
References: <20240111064208.2969599-1-chao@kernel.org>
 <20240111064208.2969599-2-chao@kernel.org> <ZaHp4to18RtGShWS@google.com>
From: Chao Yu <chao@kernel.org>
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In-Reply-To: <ZaHp4to18RtGShWS@google.com>
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Thanks, let me resend v5 w/ blow cleanups.

On 2024/1/13 9:39, Jaegeuk Kim wrote:
> Cleaned up a bit:
> 
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -1443,13 +1443,14 @@ void f2fs_compress_write_end_io(struct bio *bio, struct page *page)
>   }
> 
>   static int f2fs_write_raw_pages(struct compress_ctx *cc,
> -                                       int *submitted,
> +                                       int *submitted_p,
>                                          struct writeback_control *wbc,
>                                          enum iostat_type io_type)
>   {
>          struct address_space *mapping = cc->inode->i_mapping;
>          struct f2fs_sb_info *sbi = F2FS_M_SB(mapping);
> -       int _submitted, compr_blocks, ret = 0, i;
> +       int submitted, compr_blocks, i;
> +       int ret = 0;
> 
>          compr_blocks = f2fs_compressed_blocks(cc);
> 
> @@ -1492,7 +1493,7 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
>                  if (!clear_page_dirty_for_io(cc->rpages[i]))
>                          goto continue_unlock;
> 
> -               ret = f2fs_write_single_data_page(cc->rpages[i], &_submitted,
> +               ret = f2fs_write_single_data_page(cc->rpages[i], &submitted,
>                                                  NULL, NULL, wbc, io_type,
>                                                  compr_blocks, false);
>                  if (ret) {
> @@ -1514,7 +1515,7 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
>                          goto out;
>                  }
> 
> -               *submitted += _submitted;
> +               *submitted_p += submitted;
>          }
> 
>   out:
> 
> On 01/11, Chao Yu wrote:
>> When we overwrite compressed cluster w/ normal cluster, we should
>> not unlock cp_rwsem during f2fs_write_raw_pages(), otherwise data
>> will be corrupted if partial blocks were persisted before CP & SPOR,
>> due to cluster metadata wasn't updated atomically.
>>
>> Fixes: 4c8ff7095bef ("f2fs: support data compression")
>> Signed-off-by: Chao Yu <chao@kernel.org>
>> ---
>>   fs/f2fs/compress.c | 20 ++++++++++++++------
>>   fs/f2fs/data.c     |  3 ++-
>>   2 files changed, 16 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
>> index 9940b7886e5d..bf4cfab67aec 100644
>> --- a/fs/f2fs/compress.c
>> +++ b/fs/f2fs/compress.c
>> @@ -1448,7 +1448,8 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
>>   					enum iostat_type io_type)
>>   {
>>   	struct address_space *mapping = cc->inode->i_mapping;
>> -	int _submitted, compr_blocks, ret, i;
>> +	struct f2fs_sb_info *sbi = F2FS_M_SB(mapping);
>> +	int _submitted, compr_blocks, ret = 0, i;
>>   
>>   	compr_blocks = f2fs_compressed_blocks(cc);
>>   
>> @@ -1463,6 +1464,10 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
>>   	if (compr_blocks < 0)
>>   		return compr_blocks;
>>   
>> +	/* overwrite compressed cluster w/ normal cluster */
>> +	if (compr_blocks > 0)
>> +		f2fs_lock_op(sbi);
>> +
>>   	for (i = 0; i < cc->cluster_size; i++) {
>>   		if (!cc->rpages[i])
>>   			continue;
>> @@ -1495,26 +1500,29 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
>>   				unlock_page(cc->rpages[i]);
>>   				ret = 0;
>>   			} else if (ret == -EAGAIN) {
>> +				ret = 0;
>>   				/*
>>   				 * for quota file, just redirty left pages to
>>   				 * avoid deadlock caused by cluster update race
>>   				 * from foreground operation.
>>   				 */
>>   				if (IS_NOQUOTA(cc->inode))
>> -					return 0;
>> -				ret = 0;
>> +					goto out;
>>   				f2fs_io_schedule_timeout(DEFAULT_IO_TIMEOUT);
>>   				goto retry_write;
>>   			}
>> -			return ret;
>> +			goto out;
>>   		}
>>   
>>   		*submitted += _submitted;
>>   	}
>>   
>> -	f2fs_balance_fs(F2FS_M_SB(mapping), true);
>> +out:
>> +	if (compr_blocks > 0)
>> +		f2fs_unlock_op(sbi);
>>   
>> -	return 0;
>> +	f2fs_balance_fs(sbi, true);
>> +	return ret;
>>   }
>>   
>>   int f2fs_write_multi_pages(struct compress_ctx *cc,
>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>> index 81f9e2cc49e2..b171a9980f6a 100644
>> --- a/fs/f2fs/data.c
>> +++ b/fs/f2fs/data.c
>> @@ -2839,7 +2839,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
>>   		.encrypted_page = NULL,
>>   		.submitted = 0,
>>   		.compr_blocks = compr_blocks,
>> -		.need_lock = LOCK_RETRY,
>> +		.need_lock = compr_blocks ? LOCK_DONE : LOCK_RETRY,
>>   		.post_read = f2fs_post_read_required(inode) ? 1 : 0,
>>   		.io_type = io_type,
>>   		.io_wbc = wbc,
>> @@ -2920,6 +2920,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
>>   	if (err == -EAGAIN) {
>>   		err = f2fs_do_write_data_page(&fio);
>>   		if (err == -EAGAIN) {
>> +			f2fs_bug_on(sbi, compr_blocks);
>>   			fio.need_lock = LOCK_REQ;
>>   			err = f2fs_do_write_data_page(&fio);
>>   		}
>> -- 
>> 2.40.1