linux-kernel - Re: [PATCH] f2fs: compress: fix to cover f2fs_disable_compressed_file() w/ i

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Date: Mon, 22 Jan 2024 10:25:50 +0800
From: Chao Yu <chao@...nel.org>
To: Jaegeuk Kim <jaegeuk@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: compress: fix to cover
 f2fs_disable_compressed_file() w/ i_sem

On 2024/1/17 2:29, Jaegeuk Kim wrote:
> On 01/11, Chao Yu wrote:
>> - f2fs_disable_compressed_file
>>    - check inode_has_data
>> 					- f2fs_file_mmap
>> 					- mkwrite
>> 					 - f2fs_get_block_locked
>> 					 : update metadata in compressed
>> 					   inode's disk layout
>>    - fi->i_flags &= ~F2FS_COMPR_FL
>>    - clear_inode_flag(inode, FI_COMPRESSED_FILE);
>>
>> we should use i_sem lock to prevent above race case.
>>
>> Meanwhile, this patch adds i_size check to restrict compress inode
>> conversion condition.
> 
> Sorry, what was the reason to check i_size?

Oh, I don't see any race condition, let's remove it in v2.

Thanks,

> 
>>
>> Fixes: 4c8ff7095bef ("f2fs: support data compression")
>> Signed-off-by: Chao Yu <chao@...nel.org>
>> ---
>>   fs/f2fs/f2fs.h | 18 ++++++++++++++++--
>>   fs/f2fs/file.c |  5 ++---
>>   2 files changed, 18 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 74729db0b381..e2e0ca45f881 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -4406,19 +4406,33 @@ 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))
>> +	f2fs_down_write(&F2FS_I(inode)->i_sem);
>> +
>> +	if (!f2fs_compressed_file(inode)) {
>> +		f2fs_up_write(&F2FS_I(inode)->i_sem);
>>   		return true;
>> -	if (S_ISREG(inode->i_mode) && F2FS_HAS_BLOCKS(inode))
>> +	}
>> +	if (f2fs_is_mmap_file(inode) || inode_has_data(inode)) {
>> +		f2fs_up_write(&F2FS_I(inode)->i_sem);
>>   		return false;
>> +	}
>>   
>>   	fi->i_flags &= ~F2FS_COMPR_FL;
>>   	stat_dec_compr_inode(inode);
>>   	clear_inode_flag(inode, FI_COMPRESSED_FILE);
>>   	f2fs_mark_inode_dirty_sync(inode, true);
>> +
>> +	f2fs_up_write(&F2FS_I(inode)->i_sem);
>>   	return true;
>>   }
>>   
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 0e4c871d6aed..5e5df234eb92 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -1926,8 +1926,7 @@ 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;
>>   			}
>> @@ -4011,7 +4010,7 @@ 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