Re: [PATCH 5/6] f2fs: fix to restrict condition of compress inode conversion

[Chao Yu <chao@kernel.org>]

On 2023/12/12 6:11, Jaegeuk Kim wrote:
> On 12/10, Chao Yu wrote:
>> This patch adds i_size check during compress inode conversion in order
>> to avoid .page_mkwrite races w/ conversion.
> 
> Which race condition do you see?

Something like:

- f2fs_setflags_common
  - check S_ISREG && F2FS_HAS_BLOCKS
					- mkwrite
					 - f2fs_get_block_locked
					  : update metadata in old inode's disk layout
  - set_compress_context

Thanks,

> 
>>
>> Fixes: 4c8ff7095bef ("f2fs: support data compression")
>> Signed-off-by: Chao Yu <chao@kernel.org>
>> ---
>>   fs/f2fs/f2fs.h | 8 +++++++-
>>   fs/f2fs/file.c | 5 ++---
>>   2 files changed, 9 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 65294e3b0bef..c9b8a1953913 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -4397,13 +4397,19 @@ static inline int set_compress_context(struct inode *inode)
>>   #endif
>>   }
>>   
>> +static inline bool inode_has_data(struct inode *inode)
>> +{
>> +	return (S_ISREG(inode->i_mode) &&
>> +		(F2FS_HAS_BLOCKS(inode) || i_size_read(inode)));
>> +}
>> +
>>   static inline bool f2fs_disable_compressed_file(struct inode *inode)
>>   {
>>   	struct f2fs_inode_info *fi = F2FS_I(inode);
>>   
>>   	if (!f2fs_compressed_file(inode))
>>   		return true;
>> -	if (S_ISREG(inode->i_mode) && F2FS_HAS_BLOCKS(inode))
>> +	if (inode_has_data(inode))
>>   		return false;
>>   
>>   	fi->i_flags &= ~F2FS_COMPR_FL;
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 1a3c29a9a6a0..8af4b29c3e1a 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -1922,8 +1922,7 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
>>   
>>   			f2fs_down_write(&F2FS_I(inode)->i_sem);
>>   			if (!f2fs_may_compress(inode) ||
>> -					(S_ISREG(inode->i_mode) &&
>> -					F2FS_HAS_BLOCKS(inode))) {
>> +					inode_has_data(inode)) {
>>   				f2fs_up_write(&F2FS_I(inode)->i_sem);
>>   				return -EINVAL;
>>   			}
>> @@ -3996,7 +3995,7 @@ static int f2fs_ioc_set_compress_option(struct file *filp, unsigned long arg)
>>   		goto out;
>>   	}
>>   
>> -	if (F2FS_HAS_BLOCKS(inode)) {
>> +	if (inode_has_data(inode)) {
>>   		ret = -EFBIG;
>>   		goto out;
>>   	}
>> -- 
>> 2.40.1