Re: [PATCH v2 1/4] f2fs: support F2FS_IOC_PRECACHE_EXTENTS

[Chao Yu <yuchao0@huawei.com>]

On 2018/1/11 13:16, Jaegeuk Kim wrote:
> On 01/11, Chao Yu wrote:
>> On 2018/1/11 3:24, Jaegeuk Kim wrote:
>>> On 01/10, Chao Yu wrote:
>>>> This patch introduces a new ioctl F2FS_IOC_PRECACHE_EXTENTS to precache
>>>> extent info like ext4, in order to gain better performance during
>>>> triggering AIO by eliminating synchronous waiting of mapping info.
>>>>
>>>> Referred commit: 7869a4a6c5ca ("ext4: add support for extent pre-caching")
>>>>
>>>> In addition, with newly added extent precache abilitiy, this patch add
>>>> to support FIEMAP_FLAG_CACHE in ->fiemap.
>>>>
>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>> ---
>>>> v2:
>>>> - integrate extent precache related patches into this one.
>>>>  fs/f2fs/data.c | 33 +++++++++++++++++++++++++++++++++
>>>>  fs/f2fs/f2fs.h |  3 +++
>>>>  fs/f2fs/file.c | 39 +++++++++++++++++++++++++++++++++++++++
>>>>  3 files changed, 75 insertions(+)
>>>>
>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>>> index 8c05e9a74427..d7d3b2b49907 100644
>>>> --- a/fs/f2fs/data.c
>>>> +++ b/fs/f2fs/data.c
>>>> @@ -927,6 +927,7 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>>>>  	blkcnt_t prealloc;
>>>>  	struct extent_info ei = {0,0,0};
>>>>  	block_t blkaddr;
>>>> +	unsigned int start_pgofs;
>>>>  
>>>>  	if (!maxblocks)
>>>>  		return 0;
>>>> @@ -942,6 +943,8 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>>>>  		map->m_pblk = ei.blk + pgofs - ei.fofs;
>>>>  		map->m_len = min((pgoff_t)maxblocks, ei.fofs + ei.len - pgofs);
>>>>  		map->m_flags = F2FS_MAP_MAPPED;
>>>> +		if (map->m_next_pgofs)
>>>> +			*map->m_next_pgofs = pgofs + map->m_len;
>>>>  		goto out;
>>>>  	}
>>>>  
>>>> @@ -964,6 +967,7 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>>>>  		goto unlock_out;
>>>>  	}
>>>>  
>>>> +	start_pgofs = pgofs;
>>>>  	prealloc = 0;
>>>>  	last_ofs_in_node = ofs_in_node = dn.ofs_in_node;
>>>>  	end_offset = ADDRS_PER_PAGE(dn.node_page, inode);
>>>> @@ -997,6 +1001,8 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>>>>  				map->m_pblk = 0;
>>>>  				goto sync_out;
>>>>  			}
>>>> +			if (flag == F2FS_GET_BLOCK_PRECACHE)
>>>> +				goto sync_out;
>>>>  			if (flag == F2FS_GET_BLOCK_FIEMAP &&
>>>>  						blkaddr == NULL_ADDR) {
>>>>  				if (map->m_next_pgofs)
>>>> @@ -1055,6 +1061,16 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>>>>  	else if (dn.ofs_in_node < end_offset)
>>>>  		goto next_block;
>>>>  
>>>> +	if (flag == F2FS_GET_BLOCK_PRECACHE) {
>>>> +		if (map->m_flags & F2FS_MAP_MAPPED) {
>>>> +			unsigned int ofs = start_pgofs - map->m_lblk;
>>>> +
>>>> +			f2fs_update_extent_cache_range(&dn,
>>>> +				start_pgofs, map->m_pblk + ofs,
>>>> +				map->m_len - ofs);
>>>> +		}
>>>> +	}
>>>> +
>>>>  	f2fs_put_dnode(&dn);
>>>>  
>>>>  	if (create) {
>>>> @@ -1064,6 +1080,17 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>>>>  	goto next_dnode;
>>>>  
>>>>  sync_out:
>>>> +	if (flag == F2FS_GET_BLOCK_PRECACHE) {
>>>> +		if (map->m_flags & F2FS_MAP_MAPPED) {
>>>> +			unsigned int ofs = start_pgofs - map->m_lblk;
>>>> +
>>>> +			f2fs_update_extent_cache_range(&dn,
>>>> +				start_pgofs, map->m_pblk + ofs,
>>>> +				map->m_len - ofs);
>>>> +		}
>>>> +		if (map->m_next_pgofs)
>>>> +			*map->m_next_pgofs = pgofs + 1;
>>>> +	}
>>>>  	f2fs_put_dnode(&dn);
>>>>  unlock_out:
>>>>  	if (create) {
>>>> @@ -1210,6 +1237,12 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
>>>>  
>>>>  	inode_lock(inode);
>>>>  
>>>> +	if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) {
>>>> +		ret = f2fs_precache_extents(inode);
>>>
>>> We need to do inode_lock() in f2fs_precache_extents() after uncovering here?
>>
>>> Uh? We don't need to cover fiemap_check_flags() by inode_lock().
>>
>> Hmm, how about just following generic_block_fiemap using inode lock to
>> cover whole block_fiemap including fiemap_check_flags, that can avoid
>> leaving a hole in f2fs_fiemap after we add f2fs_precache_extents before
>> fiemap_check_flags.
> 
> Do we really need inode_lock() for f2fs_precache_extents()? What about ioctl()
> then? I think we can precache extents like a salt to speed up actual fiemap, so
> we don't need inode_lock for that tho.

It looks leaving fiemap_check_flags and f2fs_precache_extents outside of
inode lock won't cause any issue so far, let me change it.

Thanks,

> 
>>
>> Thanks,
>>
>>>
>>>> +		if (ret)
>>>> +			goto out;
>>>> +	}
>>>> +
>>>>  	ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC | FIEMAP_FLAG_XATTR);
>>>>  	if (ret)
>>>>  		goto out;
>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>> index 3b3ddcdc98e9..73a751cdbac1 100644
>>>> --- a/fs/f2fs/f2fs.h
>>>> +++ b/fs/f2fs/f2fs.h
>>>> @@ -359,6 +359,7 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
>>>>  						struct f2fs_gc_range)
>>>>  #define F2FS_IOC_GET_FEATURES		_IOR(F2FS_IOCTL_MAGIC, 12, __u32)
>>>>  #define F2FS_IOC_SET_PIN_FILE		_IOW(F2FS_IOCTL_MAGIC, 13, __u32)
>>>> +#define F2FS_IOC_PRECACHE_EXTENTS	_IO(F2FS_IOCTL_MAGIC, 14)
>>>>  
>>>>  #define F2FS_IOC_SET_ENCRYPTION_POLICY	FS_IOC_SET_ENCRYPTION_POLICY
>>>>  #define F2FS_IOC_GET_ENCRYPTION_POLICY	FS_IOC_GET_ENCRYPTION_POLICY
>>>> @@ -564,6 +565,7 @@ enum {
>>>>  	F2FS_GET_BLOCK_BMAP,
>>>>  	F2FS_GET_BLOCK_PRE_DIO,
>>>>  	F2FS_GET_BLOCK_PRE_AIO,
>>>> +	F2FS_GET_BLOCK_PRECACHE,
>>>>  };
>>>>  
>>>>  /*
>>>> @@ -2567,6 +2569,7 @@ int f2fs_getattr(const struct path *path, struct kstat *stat,
>>>>  int f2fs_setattr(struct dentry *dentry, struct iattr *attr);
>>>>  int truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end);
>>>>  void truncate_data_blocks_range(struct dnode_of_data *dn, int count);
>>>> +int f2fs_precache_extents(struct inode *inode);
>>>>  long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
>>>>  long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
>>>>  int f2fs_pin_file_control(struct inode *inode, bool inc);
>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>> index e4078b32856c..6e30016f26ad 100644
>>>> --- a/fs/f2fs/file.c
>>>> +++ b/fs/f2fs/file.c
>>>> @@ -2734,6 +2734,42 @@ static int f2fs_ioc_set_pin_file(struct file *filp, unsigned long arg)
>>>>  	return ret;
>>>>  }
>>>>  
>>>> +int f2fs_precache_extents(struct inode *inode)
>>>> +{
>>>> +	struct f2fs_inode_info *fi = F2FS_I(inode);
>>>> +	struct f2fs_map_blocks map;
>>>> +	pgoff_t next_pgofs;
>>>> +	loff_t end;
>>>> +	int err;
>>>> +
>>>> +	if (is_inode_flag_set(inode, FI_NO_EXTENT))
>>>> +		return -EOPNOTSUPP;
>>>> +
>>>> +	map.m_lblk = 0;
>>>> +	map.m_next_pgofs = &next_pgofs;
>>>> +	map.m_seg_type = NO_CHECK_TYPE;
>>>> +	end = F2FS_I_SB(inode)->max_file_blocks;
>>>> +
>>>> +	while (map.m_lblk < end) {
>>>> +		map.m_len = end - map.m_lblk;
>>>> +
>>>> +		down_write(&fi->dio_rwsem[WRITE]);
>>>> +		err = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_PRECACHE);
>>>> +		up_write(&fi->dio_rwsem[WRITE]);
>>>> +		if (err)
>>>> +			return err;
>>>> +
>>>> +		map.m_lblk = next_pgofs;
>>>> +	}
>>>> +
>>>> +	return err;
>>>> +}
>>>> +
>>>> +static int f2fs_ioc_precache_extents(struct file *filp, unsigned long arg)
>>>> +{
>>>> +	return f2fs_precache_extents(file_inode(filp));
>>>> +}
>>>> +
>>>>  long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>>>  {
>>>>  	if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(filp)))))
>>>> @@ -2786,6 +2822,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>>>  		return f2fs_ioc_fssetxattr(filp, arg);
>>>>  	case F2FS_IOC_SET_PIN_FILE:
>>>>  		return f2fs_ioc_set_pin_file(filp, arg);
>>>> +	case F2FS_IOC_PRECACHE_EXTENTS:
>>>> +		return f2fs_ioc_precache_extents(filp, arg);
>>>>  	default:
>>>>  		return -ENOTTY;
>>>>  	}
>>>> @@ -2862,6 +2900,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>>>>  	case F2FS_IOC_FSGETXATTR:
>>>>  	case F2FS_IOC_FSSETXATTR:
>>>>  	case F2FS_IOC_SET_PIN_FILE:
>>>> +	case F2FS_IOC_PRECACHE_EXTENTS:
>>>>  		break;
>>>>  	default:
>>>>  		return -ENOIOCTLCMD;
>>>> -- 
>>>> 2.15.0.55.gc2ece9dc4de6
>>>
>>> .
>>>
> 
> .
>