linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: change the way of handling range.len in F2FS_IOC_SEC_TRIM

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Date:   Tue, 14 Jul 2020 20:36:31 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Daeho Jeong <daeho43@...il.com>
CC:     Daeho Jeong <daehojeong@...gle.com>, <kernel-team@...roid.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: change the way of handling range.len
 in F2FS_IOC_SEC_TRIM_FILE

On 2020/7/14 2:11, Jaegeuk Kim wrote:
> Hi Daeho,
> 
> Please take a look at this.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git/commit/?h=dev&id=35245180459aebf6d70fde88a538f0400a794aa6

I'm curious about what will happen if we call
sec_trim_file(F2FS_TRIM_FILE_ZEROOUT) on an encrypted file, will
it use zero bits covering encrypted data on disk?

Thanks,

> 
> Thanks,
> 
> On 07/13, Daeho Jeong wrote:
>> From: Daeho Jeong <daehojeong@...gle.com>
>>
>> Changed the way of handling range.len of F2FS_IOC_SEC_TRIM_FILE.
>>  1. Added -1 value support for range.len to secure trim the whole blocks
>>     starting from range.start regardless of i_size.
>>  2. If the end of the range passes over the end of file, it means until
>>     the end of file (i_size).
>>  3. ignored the case of that range.len is zero to prevent the function
>>     from making end_addr zero and triggering different behaviour of
>>     the function.
>>
>> Signed-off-by: Daeho Jeong <daehojeong@...gle.com>
>> ---
>> Changes in v2:
>>  - Changed -1 range.len option to mean the whole blocks starting from
>>    range.start regardless of i_size
>> ---
>>  fs/f2fs/file.c | 23 ++++++++++++-----------
>>  1 file changed, 12 insertions(+), 11 deletions(-)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 368c80f8e2a1..2485841e3b2d 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -3792,7 +3792,7 @@ static int f2fs_sec_trim_file(struct file *filp, unsigned long arg)
>>  	pgoff_t index, pg_end;
>>  	block_t prev_block = 0, len = 0;
>>  	loff_t end_addr;
>> -	bool to_end;
>> +	bool to_end = false;
>>  	int ret = 0;
>>  
>>  	if (!(filp->f_mode & FMODE_WRITE))
>> @@ -3813,23 +3813,23 @@ static int f2fs_sec_trim_file(struct file *filp, unsigned long arg)
>>  	file_start_write(filp);
>>  	inode_lock(inode);
>>  
>> -	if (f2fs_is_atomic_file(inode) || f2fs_compressed_file(inode)) {
>> +	if (f2fs_is_atomic_file(inode) || f2fs_compressed_file(inode) ||
>> +			range.start >= inode->i_size) {
>>  		ret = -EINVAL;
>>  		goto err;
>>  	}
>>  
>> -	if (range.start >= inode->i_size) {
>> -		ret = -EINVAL;
>> +	if (range.len == 0)
>>  		goto err;
>> -	}
>>  
>> -	if (inode->i_size - range.start < range.len) {
>> -		ret = -E2BIG;
>> -		goto err;
>> +	if (inode->i_size - range.start > range.len) {
>> +		end_addr = range.start + range.len;
>> +	} else {
>> +		end_addr = range.len == (u64)-1 ?
>> +			sbi->sb->s_maxbytes : inode->i_size;
>> +		to_end = true;
>>  	}
>> -	end_addr = range.start + range.len;
>>  
>> -	to_end = (end_addr == inode->i_size);
>>  	if (!IS_ALIGNED(range.start, F2FS_BLKSIZE) ||
>>  			(!to_end && !IS_ALIGNED(end_addr, F2FS_BLKSIZE))) {
>>  		ret = -EINVAL;
>> @@ -3846,7 +3846,8 @@ static int f2fs_sec_trim_file(struct file *filp, unsigned long arg)
>>  	down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
>>  	down_write(&F2FS_I(inode)->i_mmap_sem);
>>  
>> -	ret = filemap_write_and_wait_range(mapping, range.start, end_addr - 1);
>> +	ret = filemap_write_and_wait_range(mapping, range.start,
>> +			to_end ? LLONG_MAX : end_addr - 1);
>>  	if (ret)
>>  		goto out;
>>  
>> -- 
>> 2.27.0.383.g050319c2ae-goog
> 
> 
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