Re: [f2fs-dev] [RFC PATHC 2/2] f2fs: apply write hints to select the type of segment for direct write

[Chao Yu <chao@kernel.org>]

On 2017/11/9 13:51, Hyunchul Lee wrote:
> From: Hyunchul Lee <cheol.lee@lge.com>
> 
> Select the type of the segment using write hints, when blocks are
> allocated for direct write.
> 
> There are unhandled corner cases. Hints are not applied in
> in-place update.  And if the blocks of a file is not pre-allocated
> because of the invalid user buffer, CURSEG_WARM_DATA segment will
> be selected.
> 
> Signed-off-by: Hyunchul Lee <cheol.lee@lge.com>
> ---
>  fs/f2fs/data.c | 101 ++++++++++++++++++++++++++++++++++-----------------------
>  fs/f2fs/f2fs.h |   1 +
>  2 files changed, 61 insertions(+), 41 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 36b5352..d06048a 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -783,7 +783,7 @@ struct page *get_new_data_page(struct inode *inode,
>  	return page;
>  }
>  
> -static int __allocate_data_block(struct dnode_of_data *dn)
> +static int __allocate_data_block(struct dnode_of_data *dn, int seg_type)
>  {
>  	struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
>  	struct f2fs_summary sum;
> @@ -808,7 +808,7 @@ static int __allocate_data_block(struct dnode_of_data *dn)
>  	set_summary(&sum, dn->nid, dn->ofs_in_node, ni.version);
>  
>  	allocate_data_block(sbi, NULL, dn->data_blkaddr, &dn->data_blkaddr,
> -					&sum, CURSEG_WARM_DATA, NULL, false);
> +					&sum, seg_type, NULL, false);
>  	set_data_blkaddr(dn);
>  
>  	/* update i_size */
> @@ -827,42 +827,6 @@ static inline bool __force_buffered_io(struct inode *inode, int rw)
>  			F2FS_I_SB(inode)->s_ndevs);
>  }
>  
> -int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from)
> -{
> -	struct inode *inode = file_inode(iocb->ki_filp);
> -	struct f2fs_map_blocks map;
> -	int err = 0;
> -
> -	if (is_inode_flag_set(inode, FI_NO_PREALLOC))
> -		return 0;
> -
> -	map.m_lblk = F2FS_BLK_ALIGN(iocb->ki_pos);
> -	map.m_len = F2FS_BYTES_TO_BLK(iocb->ki_pos + iov_iter_count(from));
> -	if (map.m_len > map.m_lblk)
> -		map.m_len -= map.m_lblk;
> -	else
> -		map.m_len = 0;
> -
> -	map.m_next_pgofs = NULL;
> -
> -	if (iocb->ki_flags & IOCB_DIRECT) {
> -		err = f2fs_convert_inline_inode(inode);
> -		if (err)
> -			return err;
> -		return f2fs_map_blocks(inode, &map, 1,
> -			__force_buffered_io(inode, WRITE) ?
> -				F2FS_GET_BLOCK_PRE_AIO :
> -				F2FS_GET_BLOCK_PRE_DIO);
> -	}
> -	if (iocb->ki_pos + iov_iter_count(from) > MAX_INLINE_DATA(inode)) {
> -		err = f2fs_convert_inline_inode(inode);
> -		if (err)
> -			return err;
> -	}
> -	if (!f2fs_has_inline_data(inode))
> -		return f2fs_map_blocks(inode, &map, 1, F2FS_GET_BLOCK_PRE_AIO);
> -	return err;
> -}
>  
>  static inline void __do_map_lock(struct f2fs_sb_info *sbi, int flag, bool lock)
>  {
> @@ -888,8 +852,8 @@ static inline void __do_map_lock(struct f2fs_sb_info *sbi, int flag, bool lock)
>   *     b. do not use extent cache for better performance
>   *     c. give the block addresses to blockdev
>   */
> -int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
> -						int create, int flag)
> +static int __f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
> +				int create, int flag, int seg_type)
>  {
>  	unsigned int maxblocks = map->m_len;
>  	struct dnode_of_data dn;
> @@ -957,7 +921,12 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>  					last_ofs_in_node = dn.ofs_in_node;
>  				}
>  			} else {
> -				err = __allocate_data_block(&dn);
> +				/* if this inode is marked with FI_NO_PREALLOC,
> +				 * @seg_type is NO_CHECK_TYPE
> +				 */
> +				if (seg_type == NO_CHECK_TYPE)
> +					seg_type = CURSEG_WARM_DATA;
> +				err = __allocate_data_block(&dn, seg_type);

We need to use inode.i_write_hint instead of ki_hint passed from file.f_write_hint?

Thanks,

>  				if (!err)
>  					set_inode_flag(inode, FI_APPEND_WRITE);
>  			}
> @@ -1048,6 +1017,51 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>  	return err;
>  }
>  
> +int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
> +						int create, int flag)
> +{
> +	return __f2fs_map_blocks(inode, map, create, flag, NO_CHECK_TYPE);
> +}
> +
> +int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from)
> +{
> +	struct inode *inode = file_inode(iocb->ki_filp);
> +	struct f2fs_map_blocks map;
> +	int err = 0;
> +
> +	if (is_inode_flag_set(inode, FI_NO_PREALLOC))
> +		return 0;
> +
> +	map.m_lblk = F2FS_BLK_ALIGN(iocb->ki_pos);
> +	map.m_len = F2FS_BYTES_TO_BLK(iocb->ki_pos + iov_iter_count(from));
> +	if (map.m_len > map.m_lblk)
> +		map.m_len -= map.m_lblk;
> +	else
> +		map.m_len = 0;
> +
> +	map.m_next_pgofs = NULL;
> +
> +	if (iocb->ki_flags & IOCB_DIRECT) {
> +		err = f2fs_convert_inline_inode(inode);
> +		if (err)
> +			return err;
> +		return __f2fs_map_blocks(inode, &map, 1,
> +			__force_buffered_io(inode, WRITE) ?
> +				F2FS_GET_BLOCK_PRE_AIO :
> +				F2FS_GET_BLOCK_PRE_DIO,
> +				rw_hint_to_seg_type(iocb->ki_hint));
> +	}
> +	if (iocb->ki_pos + iov_iter_count(from) > MAX_INLINE_DATA(inode)) {
> +		err = f2fs_convert_inline_inode(inode);
> +		if (err)
> +			return err;
> +	}
> +	if (!f2fs_has_inline_data(inode))
> +		return f2fs_map_blocks(inode, &map, 1, F2FS_GET_BLOCK_PRE_AIO);
> +
> +	return err;
> +}
> +
>  static int __get_data_block(struct inode *inode, sector_t iblock,
>  			struct buffer_head *bh, int create, int flag,
>  			pgoff_t *next_pgofs)
> @@ -2082,6 +2096,11 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
>  
>  	trace_f2fs_direct_IO_enter(inode, offset, count, rw);
>  
> +	/* This is for avoiding the situation that the data of a segment is
> +	 * passed down to devices with different hints
> +	 */
> +	iocb->ki_hint = WRITE_LIFE_NOT_SET;
> +
>  	down_read(&F2FS_I(inode)->dio_rwsem[rw]);
>  	err = blockdev_direct_IO(iocb, inode, iter, get_data_block_dio);
>  	up_read(&F2FS_I(inode)->dio_rwsem[rw]);
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 4b4a72f..9be5658 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -2562,6 +2562,7 @@ int lookup_journal_in_cursum(struct f2fs_journal *journal, int type,
>  void destroy_segment_manager(struct f2fs_sb_info *sbi);
>  int __init create_segment_manager_caches(void);
>  void destroy_segment_manager_caches(void);
> +int rw_hint_to_seg_type(enum rw_hint hint);
>  
>  /*
>   * checkpoint.c
>