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Subject: Re: [RFC PATCH 2/2] f2fs: introduce F2FS_IOC_RELEASE_COMPRESS_BLOCKS
To:     Jaegeuk Kim <jaegeuk@kernel.org>
CC:     <linux-f2fs-devel@lists.sourceforge.net>,
        <linux-kernel@vger.kernel.org>, <chao@kernel.org>
References: <20200221100922.16781-1-yuchao0@huawei.com>
 <20200221100922.16781-2-yuchao0@huawei.com>
 <20200224214605.GA77839@google.com>
 <db505852-345d-05d0-4555-437093d2af14@huawei.com>
 <20200226221608.GA224608@google.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <4c877b2c-177c-a76a-ced4-1d3e087d8530@huawei.com>
Date:   Thu, 27 Feb 2020 10:02:45 +0800
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On 2020/2/27 6:16, Jaegeuk Kim wrote:
> On 02/25, Chao Yu wrote:
>> On 2020/2/25 5:46, Jaegeuk Kim wrote:
>>> On 02/21, Chao Yu wrote:
>>>> There are still reserved blocks on compressed inode, this patch
>>>> introduce a new ioctl to help release reserved blocks back to
>>>> filesystem, so that userspace can reuse those freed space.
>>>
>>> I thought we can add compressed_blocks into free space, after converting
>>> the file to immutable one. Otherwise, this patch is able to corrupt the
>>
>> Yes, I remember that.
>>
>> So any suggestion on this patch? we can:
>> - check immutable flag before releasing space, or
>> - we can add immutable flag on compressed inode in this ioctl interface?
> 
> Can we add a flag in ioctl for both?
> Default is checking immutable, but add a flag to force enabling it.

Okay, let me update the patch.

Thanks,

> 
>>
>> Thanks,
>>
>>> filesystem very easily.
>>>
>>>>
>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>> ---
>>>>  fs/f2fs/f2fs.h |   6 +++
>>>>  fs/f2fs/file.c | 129 ++++++++++++++++++++++++++++++++++++++++++++++++-
>>>>  2 files changed, 134 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>> index 15199df5d40a..468f807fd917 100644
>>>> --- a/fs/f2fs/f2fs.h
>>>> +++ b/fs/f2fs/f2fs.h
>>>> @@ -427,6 +427,8 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
>>>>  #define F2FS_IOC_PRECACHE_EXTENTS	_IO(F2FS_IOCTL_MAGIC, 15)
>>>>  #define F2FS_IOC_RESIZE_FS		_IOW(F2FS_IOCTL_MAGIC, 16, __u64)
>>>>  #define F2FS_IOC_GET_COMPRESS_BLOCKS	_IOR(F2FS_IOCTL_MAGIC, 17, __u64)
>>>> +#define F2FS_IOC_RELEASE_COMPRESS_BLOCKS				\
>>>> +					_IOR(F2FS_IOCTL_MAGIC, 18, __u64)
>>>>  
>>>>  #define F2FS_IOC_GET_VOLUME_NAME	FS_IOC_GETFSLABEL
>>>>  #define F2FS_IOC_SET_VOLUME_NAME	FS_IOC_SETFSLABEL
>>>> @@ -3957,6 +3959,10 @@ static inline void f2fs_i_compr_blocks_update(struct inode *inode,
>>>>  {
>>>>  	int diff = F2FS_I(inode)->i_cluster_size - blocks;
>>>>  
>>>> +	/* don't update i_compr_blocks if saved blocks were released */
>>>> +	if (!add && !F2FS_I(inode)->i_compr_blocks)
>>>> +		return;
>>>> +
>>>>  	if (add) {
>>>>  		F2FS_I(inode)->i_compr_blocks += diff;
>>>>  		stat_add_compr_blocks(inode, diff);
>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>> index 235708c892af..613f87151d90 100644
>>>> --- a/fs/f2fs/file.c
>>>> +++ b/fs/f2fs/file.c
>>>> @@ -557,6 +557,7 @@ void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count)
>>>>  	bool compressed_cluster = false;
>>>>  	int cluster_index = 0, valid_blocks = 0;
>>>>  	int cluster_size = F2FS_I(dn->inode)->i_cluster_size;
>>>> +	bool released = !F2FS_I(dn->inode)->i_compr_blocks;
>>>>  
>>>>  	if (IS_INODE(dn->node_page) && f2fs_has_extra_attr(dn->inode))
>>>>  		base = get_extra_isize(dn->inode);
>>>> @@ -595,7 +596,9 @@ void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count)
>>>>  			clear_inode_flag(dn->inode, FI_FIRST_BLOCK_WRITTEN);
>>>>  
>>>>  		f2fs_invalidate_blocks(sbi, blkaddr);
>>>> -		nr_free++;
>>>> +
>>>> +		if (released && blkaddr != COMPRESS_ADDR)
>>>> +			nr_free++;
>>>>  	}
>>>>  
>>>>  	if (compressed_cluster)
>>>> @@ -3416,6 +3419,127 @@ static int f2fs_get_compress_blocks(struct file *filp, unsigned long arg)
>>>>  	return put_user(blocks, (u64 __user *)arg);
>>>>  }
>>>>  
>>>> +static int release_compress_blocks(struct dnode_of_data *dn, pgoff_t count)
>>>> +{
>>>> +	struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
>>>> +	unsigned int released_blocks = 0;
>>>> +	int cluster_size = F2FS_I(dn->inode)->i_cluster_size;
>>>> +
>>>> +	while (count) {
>>>> +		int compr_blocks = 0;
>>>> +		block_t blkaddr = f2fs_data_blkaddr(dn);
>>>> +		int i;
>>>> +
>>>> +		if (blkaddr != COMPRESS_ADDR) {
>>>> +			dn->ofs_in_node += cluster_size;
>>>> +			goto next;
>>>> +		}
>>>> +
>>>> +		for (i = 0; i < cluster_size; i++, dn->ofs_in_node++) {
>>>> +			blkaddr = f2fs_data_blkaddr(dn);
>>>> +
>>>> +			if (__is_valid_data_blkaddr(blkaddr)) {
>>>> +				compr_blocks++;
>>>> +				if (unlikely(!f2fs_is_valid_blkaddr(sbi, blkaddr,
>>>> +							DATA_GENERIC_ENHANCE)))
>>>> +					return -EFSCORRUPTED;
>>>> +			}
>>>> +
>>>> +			if (blkaddr != NEW_ADDR)
>>>> +				continue;
>>>> +
>>>> +			dn->data_blkaddr = NULL_ADDR;
>>>> +			f2fs_set_data_blkaddr(dn);
>>>> +		}
>>>> +
>>>> +		f2fs_i_compr_blocks_update(dn->inode, compr_blocks, false);
>>>> +		dec_valid_block_count(sbi, dn->inode,
>>>> +					cluster_size - compr_blocks);
>>>> +
>>>> +		released_blocks += cluster_size - compr_blocks;
>>>> +next:
>>>> +		count -= cluster_size;
>>>> +	}
>>>> +
>>>> +	return released_blocks;
>>>> +}
>>>> +
>>>> +static int f2fs_release_compress_blocks(struct file *filp, unsigned long arg)
>>>> +{
>>>> +	struct inode *inode = file_inode(filp);
>>>> +	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>>> +	pgoff_t page_idx = 0, last_idx;
>>>> +	unsigned int released_blocks = 0;
>>>> +	int ret;
>>>> +
>>>> +	if (!f2fs_sb_has_compression(F2FS_I_SB(inode)))
>>>> +		return -EOPNOTSUPP;
>>>> +
>>>> +	if (!f2fs_compressed_file(inode))
>>>> +		return -EINVAL;
>>>> +
>>>> +	if (f2fs_readonly(sbi->sb))
>>>> +		return -EROFS;
>>>> +
>>>> +	ret = mnt_want_write_file(filp);
>>>> +	if (ret)
>>>> +		return ret;
>>>> +
>>>> +	if (!F2FS_I(inode)->i_compr_blocks)
>>>> +		goto out;
>>>> +
>>>> +	f2fs_balance_fs(F2FS_I_SB(inode), true);
>>>> +
>>>> +	inode_lock(inode);
>>>> +
>>>> +	down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
>>>> +	down_write(&F2FS_I(inode)->i_mmap_sem);
>>>> +
>>>> +	last_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
>>>> +
>>>> +	while (page_idx < last_idx) {
>>>> +		struct dnode_of_data dn;
>>>> +		pgoff_t end_offset, count;
>>>> +
>>>> +		set_new_dnode(&dn, inode, NULL, NULL, 0);
>>>> +		ret = f2fs_get_dnode_of_data(&dn, page_idx, LOOKUP_NODE);
>>>> +		if (ret) {
>>>> +			if (ret == -ENOENT) {
>>>> +				page_idx = f2fs_get_next_page_offset(&dn,
>>>> +								page_idx);
>>>> +				ret = 0;
>>>> +				continue;
>>>> +			}
>>>> +			break;
>>>> +		}
>>>> +
>>>> +		end_offset = ADDRS_PER_PAGE(dn.node_page, inode);
>>>> +		count = min(end_offset - dn.ofs_in_node, last_idx - page_idx);
>>>> +
>>>> +		ret = release_compress_blocks(&dn, count);
>>>> +
>>>> +		f2fs_put_dnode(&dn);
>>>> +
>>>> +		if (ret < 0)
>>>> +			break;
>>>> +
>>>> +		page_idx += count;
>>>> +		released_blocks += ret;
>>>> +	}
>>>> +
>>>> +	up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
>>>> +	up_write(&F2FS_I(inode)->i_mmap_sem);
>>>> +
>>>> +	inode_unlock(inode);
>>>> +out:
>>>> +	mnt_drop_write_file(filp);
>>>> +
>>>> +	if (!ret)
>>>> +		ret = put_user(released_blocks, (u64 __user *)arg);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>>  long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>>>  {
>>>>  	if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(filp)))))
>>>> @@ -3496,6 +3620,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>>>  		return f2fs_set_volume_name(filp, arg);
>>>>  	case F2FS_IOC_GET_COMPRESS_BLOCKS:
>>>>  		return f2fs_get_compress_blocks(filp, arg);
>>>> +	case F2FS_IOC_RELEASE_COMPRESS_BLOCKS:
>>>> +		return f2fs_release_compress_blocks(filp, arg);
>>>>  	default:
>>>>  		return -ENOTTY;
>>>>  	}
>>>> @@ -3654,6 +3780,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>>>>  	case F2FS_IOC_GET_VOLUME_NAME:
>>>>  	case F2FS_IOC_SET_VOLUME_NAME:
>>>>  	case F2FS_IOC_GET_COMPRESS_BLOCKS:
>>>> +	case F2FS_IOC_RELEASE_COMPRESS_BLOCKS:
>>>>  		break;
>>>>  	default:
>>>>  		return -ENOIOCTLCMD;
>>>> -- 
>>>> 2.18.0.rc1
>>> .
>>>
> .
>