linux-kernel - Re: [PATCH v3] f2fs: add fast symlink support

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Message-ID: <20150318085851.GA2863@kernel>
Date:	Wed, 18 Mar 2015 16:58:52 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Jaegeuk Kim <jaegeuk@...nel.org>
Cc:	Changman Lee <cm224.lee@...sung.com>,
	Chao Yu <chao2.yu@...sung.com>,
	linux-f2fs-devel@...ts.sourceforge.net,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] f2fs: add fast symlink support

Hi Jaegeuk,
On Tue, Mar 17, 2015 at 10:21:27AM -0700, Jaegeuk Kim wrote:
>> -	err = page_symlink(inode, symname, symlen);
>> +
>> +	if (symlen > MAX_FAST_SYMLINK_SIZE) {
>> +		/* slow symlink */
>> +		inode->i_op = &f2fs_symlink_inode_operations;
>> +		inode->i_mapping->a_ops = &f2fs_dblock_aops;
>> +		err = page_symlink(inode, symname, symlen);
>> +	} else {
>> +		/* fast symlink */
>> +		struct page *node_page;
>> +
>> +		inode->i_op = &f2fs_fast_symlink_inode_operations;
>> +		node_page = get_node_page(sbi, inode->i_ino);
>> +		memcpy((char *)&F2FS_INODE(node_page)->i_addr, symname, symlen);
>
>This is mostly likewise the inline_data flow.
>As of now, I can't recommend using any i_addr region, since we need to handle
>many cases such as truncation, roll-forward recovery, and fsck/dump tools.
>
>It is more sensible to enable inline_data by default, isn't it?

Do you mean to replace the codes above by something like
f2fs_write_inline_data()?

Regards,
Wanpeng Li 

>
>Thanks,
>
>> +		set_page_dirty(node_page);
>> +		f2fs_put_page(node_page, 1);
>> +		inode->i_size = symlen-1;
>> +		set_inode_flag(F2FS_I(inode), FI_FAST_SYMLINK);
>> +		mark_inode_dirty(inode);
>> +	}
>>  	alloc_nid_done(sbi, inode->i_ino);
>>  
>>  	d_instantiate(dentry, inode);
>> @@ -743,6 +774,20 @@ const struct inode_operations f2fs_symlink_inode_operations = {
>>  #endif
>>  };
>>  
>> +const struct inode_operations f2fs_fast_symlink_inode_operations = {
>> +	.readlink       = generic_readlink,
>> +	.follow_link    = f2fs_follow_link,
>> +	.put_link       = page_put_link,
>> +	.getattr	= f2fs_getattr,
>> +	.setattr	= f2fs_setattr,
>> +#ifdef CONFIG_F2FS_FS_XATTR
>> +	.setxattr	= generic_setxattr,
>> +	.getxattr	= generic_getxattr,
>> +	.listxattr	= f2fs_listxattr,
>> +	.removexattr	= generic_removexattr,
>> +#endif
>> +};
>> +
>>  const struct inode_operations f2fs_special_inode_operations = {
>>  	.getattr	= f2fs_getattr,
>>  	.setattr        = f2fs_setattr,
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index 35a9117..efe28a2b 100644
>> --- a/fs/f2fs/node.c
>> +++ b/fs/f2fs/node.c
>> @@ -908,8 +908,9 @@ void remove_inode_page(struct inode *inode)
>>  	}
>>  
>>  	/* remove potential inline_data blocks */
>> -	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
>> -				S_ISLNK(inode->i_mode))
>> +	if ((S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
>> +				S_ISLNK(inode->i_mode)) &&
>> +				!f2fs_inode_is_fast_symlink(inode))
>>  		truncate_data_blocks_range(&dn, 1);
>>  
>>  	/* 0 is possible, after f2fs_new_inode() has failed */
>> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
>> index 502f28c..834880c 100644
>> --- a/include/linux/f2fs_fs.h
>> +++ b/include/linux/f2fs_fs.h
>> @@ -178,9 +178,11 @@ struct f2fs_extent {
>>  #define F2FS_INLINE_DATA	0x02	/* file inline data flag */
>>  #define F2FS_INLINE_DENTRY	0x04	/* file inline dentry flag */
>>  #define F2FS_DATA_EXIST		0x08	/* file inline data exist flag */
>> +#define F2FS_FAST_SYMLINK	0x10    /* file fast symlink flag */
>>  
>>  #define MAX_INLINE_DATA		(sizeof(__le32) * (DEF_ADDRS_PER_INODE - \
>>  						F2FS_INLINE_XATTR_ADDRS - 1))
>> +#define MAX_FAST_SYMLINK_SIZE (MAX_INLINE_DATA + 1)
>>  
>>  struct f2fs_inode {
>>  	__le16 i_mode;			/* file mode */
>> -- 
>> 1.9.1
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