Re: [f2fs-dev] [PATCH] f2fs: compress: don't redirty sparse cluster during {, de}compress

["Yeongjin Gil" <youngjin.gil@samsung.com>]

Thanks for your review. I will send patch v2.

>On 2024/8/13 14:11, Yeongjin Gil wrote:
>> In f2fs_do_write_data_page, when the data block is NULL_ADDR, it skips
>> writepage considering that it has been already truncated.
>> This results in an infinite loop as the PAGECACHE_TAG_TOWRITE tag is
>> not cleared during the writeback process for a compressed file
>> including NULL_ADDR in compress_mode=user.
>>
>> This is the reproduction process:
>>
>> 1. dd if=/dev/zero bs=4096 count=1024 seek=1024 of=testfile 2. f2fs_io
>> compress testfile 3. dd if=/dev/zero bs=4096 count=1 conv=notrunc
>> of=testfile 4. f2fs_io decompress testfile
>
>Good catch!
>
>>
>> To prevent the problem, let's check whether the cluster is fully
>> allocated before redirty its pages.
>>
>> Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
>> Reviewed-by: Sunmin Jeong <s_min.jeong@samsung.com>
>> Tested-by: Jaewook Kim <jw5454.kim@samsung.com>
>> Signed-off-by: Yeongjin Gil <youngjin.gil@samsung.com>
>
>Need a fixes line?
>
>> ---
>>   fs/f2fs/compress.c | 34 ++++++++++++++++++++++++++--------
>>   fs/f2fs/f2fs.h     | 12 ++++++++++++
>>   fs/f2fs/file.c     | 39 +++++++++++++++++++++------------------
>>   3 files changed, 59 insertions(+), 26 deletions(-)
>>
>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c index
>> 990b93689b46..09b91d725807 100644
>> --- a/fs/f2fs/compress.c
>> +++ b/fs/f2fs/compress.c
>> @@ -945,7 +945,7 @@ static int __f2fs_get_cluster_blocks(struct inode
>*inode,
>>   	unsigned int cluster_size = F2FS_I(inode)->i_cluster_size;
>>   	int count, i;
>>
>> -	for (i = 1, count = 1; i < cluster_size; i++) {
>> +	for (i = 0, count = 0; i < cluster_size; i++) {
>>   		block_t blkaddr = data_blkaddr(dn->inode, dn->node_page,
>>   							dn->ofs_in_node + i);
>>
>> @@ -956,8 +956,8 @@ static int __f2fs_get_cluster_blocks(struct inode
>*inode,
>>   	return count;
>>   }
>>
>> -static int __f2fs_cluster_blocks(struct inode *inode,
>> -				unsigned int cluster_idx, bool compr_blks)
>> +static int __f2fs_cluster_blocks(struct inode *inode, unsigned int
>cluster_idx,
>> +				enum cluster_check_type type)
>>   {
>>   	struct dnode_of_data dn;
>>   	unsigned int start_idx = cluster_idx << @@ -978,10 +978,12 @@
>> static int __f2fs_cluster_blocks(struct inode *inode,
>>   	}
>>
>>   	if (dn.data_blkaddr == COMPRESS_ADDR) {
>> -		if (compr_blks)
>> -			ret = __f2fs_get_cluster_blocks(inode, &dn);
>> -		else
>> +		if (type == COMPR_BLKS)
>> +			ret = 1 + __f2fs_get_cluster_blocks(inode, &dn);
>> +		else if (type == COMPR_CLUSTER)
>>   			ret = 1;
>> +	} else if (type == DECOMPR_BLKS) {
>> +		ret = __f2fs_get_cluster_blocks(inode, &dn);
>>   	}
>>   fail:
>>   	f2fs_put_dnode(&dn);
>> @@ -991,7 +993,14 @@ static int __f2fs_cluster_blocks(struct inode *inode,
>>   /* return # of compressed blocks in compressed cluster */
>>   static int f2fs_compressed_blocks(struct compress_ctx *cc)
>>   {
>> -	return __f2fs_cluster_blocks(cc->inode, cc->cluster_idx, true);
>> +	return __f2fs_cluster_blocks(cc->inode, cc->cluster_idx,
>> +COMPR_BLKS); }
>> +
>> +/* return # of raw blocks in non-compressed cluster */ static int
>> +f2fs_decompressed_blocks(struct inode *inode,
>> +				unsigned int cluster_idx)
>> +{
>> +	return __f2fs_cluster_blocks(inode, cluster_idx, DECOMPR_BLKS);
>>   }
>>
>>   /* return whether cluster is compressed one or not */ @@ -999,7
>> +1008,16 @@ int f2fs_is_compressed_cluster(struct inode *inode, pgoff_t
>index)
>>   {
>>   	return __f2fs_cluster_blocks(inode,
>>   		index >> F2FS_I(inode)->i_log_cluster_size,
>> -		false);
>> +		COMPR_CLUSTER);
>> +}
>> +
>> +/* return whether the cluster is filled with raw blocks */ bool
>> +f2fs_is_non_sparse_cluster(struct inode *inode, pgoff_t index)
>
>f2fs_is_sparse_cluster()?
>
>> +{
>> +	unsigned int cluster_idx = index >>
>> +F2FS_I(inode)->i_log_cluster_size;
>> +
>> +	return f2fs_decompressed_blocks(inode, cluster_idx) ==
>> +		F2FS_I(inode)->i_cluster_size;
>>   }
>>
>>   static bool cluster_may_compress(struct compress_ctx *cc) diff --git
>> a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 51fd5063a69c..6f26c8cb8857
>> 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -4302,6 +4302,11 @@ static inline bool
>f2fs_meta_inode_gc_required(struct inode *inode)
>>    * compress.c
>>    */
>>   #ifdef CONFIG_F2FS_FS_COMPRESSION
>> +enum cluster_check_type {
>> +	COMPR_CLUSTER,
>> +	COMPR_BLKS,
>> +	DECOMPR_BLKS
>
>How about?
>
>CLUSTER_IS_COMPR,
>CLUSTER_COMPR_BLKS,
>CLUSTER_RAW_BLKS
>
>> +};
>
>Can you please add some comments for these enums?
>
>>   bool f2fs_is_compressed_page(struct page *page);
>>   struct page *f2fs_compress_control_page(struct page *page);
>>   int f2fs_prepare_compress_overwrite(struct inode *inode, @@ -4328,6
>> +4333,7 @@ int f2fs_write_multi_pages(struct compress_ctx *cc,
>>   						struct writeback_control *wbc,
>>   						enum iostat_type io_type);
>>   int f2fs_is_compressed_cluster(struct inode *inode, pgoff_t index);
>> +bool f2fs_is_non_sparse_cluster(struct inode *inode, pgoff_t index);
>>   void f2fs_update_read_extent_tree_range_compressed(struct inode *inode,
>>   				pgoff_t fofs, block_t blkaddr,
>>   				unsigned int llen, unsigned int c_len); @@ -
>4414,6 +4420,12 @@
>> static inline bool f2fs_load_compressed_page(struct f2fs_sb_info *sbi,
>>   static inline void f2fs_invalidate_compress_pages(struct f2fs_sb_info
>*sbi,
>>   							nid_t ino) { }
>>   #define inc_compr_inode_stat(inode)		do { } while (0)
>> +static inline int f2fs_is_compressed_cluster(
>> +				struct inode *inode,
>> +				pgoff_t index) { return 0; }
>> +static inline bool f2fs_is_non_sparse_cluster(
>> +				struct inode *inode,
>> +				pgoff_t index) { return false; }
>>   static inline void f2fs_update_read_extent_tree_range_compressed(
>>   				struct inode *inode,
>>   				pgoff_t fofs, block_t blkaddr,
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index
>> 270c32e3385f..fba8b5f216f9 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -4220,9 +4220,8 @@ static int f2fs_ioc_decompress_file(struct file
>*filp)
>>   	struct inode *inode = file_inode(filp);
>>   	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>   	struct f2fs_inode_info *fi = F2FS_I(inode);
>> -	pgoff_t page_idx = 0, last_idx;
>> -	int cluster_size = fi->i_cluster_size;
>> -	int count, ret;
>> +	pgoff_t page_idx = 0, last_idx, cluster_idx;
>> +	int ret;
>>
>>   	if (!f2fs_sb_has_compression(sbi) ||
>>   			F2FS_OPTION(sbi).compress_mode != COMPR_MODE_USER) @@ -
>4257,10
>> +4256,15 @@ static int f2fs_ioc_decompress_file(struct file *filp)
>>   		goto out;
>>
>>   	last_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
>> +	last_idx >>= fi->i_log_cluster_size;
>> +
>> +	for (cluster_idx = 0; cluster_idx < last_idx; cluster_idx++) {
>> +		page_idx = cluster_idx << fi->i_log_cluster_size;
>> +
>> +		if (!f2fs_is_compressed_cluster(inode, page_idx))
>> +			continue;
>>
>> -	count = last_idx - page_idx;
>> -	while (count && count >= cluster_size) {
>> -		ret = redirty_blocks(inode, page_idx, cluster_size);
>> +		ret = redirty_blocks(inode, page_idx, fi->i_cluster_size);
>>   		if (ret < 0)
>>   			break;
>>
>> @@ -4270,9 +4274,6 @@ static int f2fs_ioc_decompress_file(struct file
>*filp)
>>   				break;
>>   		}
>>
>> -		count -= cluster_size;
>> -		page_idx += cluster_size;
>> -
>>   		cond_resched();
>>   		if (fatal_signal_pending(current)) {
>>   			ret = -EINTR;
>> @@ -4299,9 +4300,9 @@ static int f2fs_ioc_compress_file(struct file *filp)
>>   {
>>   	struct inode *inode = file_inode(filp);
>>   	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>> -	pgoff_t page_idx = 0, last_idx;
>> -	int cluster_size = F2FS_I(inode)->i_cluster_size;
>> -	int count, ret;
>> +	struct f2fs_inode_info *fi = F2FS_I(inode);
>> +	pgoff_t page_idx = 0, last_idx, cluster_idx;
>> +	int ret;
>>
>>   	if (!f2fs_sb_has_compression(sbi) ||
>>   			F2FS_OPTION(sbi).compress_mode != COMPR_MODE_USER) @@ -
>4335,10
>> +4336,15 @@ static int f2fs_ioc_compress_file(struct file *filp)
>>   	set_inode_flag(inode, FI_ENABLE_COMPRESS);
>>
>>   	last_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
>> +	last_idx >>= fi->i_log_cluster_size;
>>
>> -	count = last_idx - page_idx;
>> -	while (count && count >= cluster_size) {
>> -		ret = redirty_blocks(inode, page_idx, cluster_size);
>> +	for (cluster_idx = 0; cluster_idx < last_idx; cluster_idx++) {
>> +		page_idx = cluster_idx << fi->i_log_cluster_size;
>> +
>> +		if (!f2fs_is_non_sparse_cluster(inode, page_idx))
>
>if (f2fs_is_sparse_cluster())
>	continue;
>
>Thanks,
>
>> +			continue;
>> +
>> +		ret = redirty_blocks(inode, page_idx, fi->i_cluster_size);
>>   		if (ret < 0)
>>   			break;
>>
>> @@ -4348,9 +4354,6 @@ static int f2fs_ioc_compress_file(struct file *filp)
>>   				break;
>>   		}
>>
>> -		count -= cluster_size;
>> -		page_idx += cluster_size;
>> -
>>   		cond_resched();
>>   		if (fatal_signal_pending(current)) {
>>   			ret = -EINTR;




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