linux-kernel - Re: [f2fs-dev] [PATCH 6/6] f2fs: set I_LINKABLE early to avoid wrong access by vfs

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Date:   Tue, 10 Dec 2019 14:37:49 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH 6/6] f2fs: set I_LINKABLE early to avoid wrong
 access by vfs

On 2019/12/10 6:23, Jaegeuk Kim wrote:
> This patch moves setting I_LINKABLE early in rename2(whiteout) to avoid the
> below warning.
> 
> [ 3189.163385] WARNING: CPU: 3 PID: 59523 at fs/inode.c:358 inc_nlink+0x32/0x40
> [ 3189.246979] Call Trace:
> [ 3189.248707]  f2fs_init_inode_metadata+0x2d6/0x440 [f2fs]
> [ 3189.251399]  f2fs_add_inline_entry+0x162/0x8c0 [f2fs]
> [ 3189.254010]  f2fs_add_dentry+0x69/0xe0 [f2fs]
> [ 3189.256353]  f2fs_do_add_link+0xc5/0x100 [f2fs]
> [ 3189.258774]  f2fs_rename2+0xabf/0x1010 [f2fs]
> [ 3189.261079]  vfs_rename+0x3f8/0xaa0
> [ 3189.263056]  ? tomoyo_path_rename+0x44/0x60
> [ 3189.265283]  ? do_renameat2+0x49b/0x550
> [ 3189.267324]  do_renameat2+0x49b/0x550
> [ 3189.269316]  __x64_sys_renameat2+0x20/0x30
> [ 3189.271441]  do_syscall_64+0x5a/0x230
> [ 3189.273410]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> [ 3189.275848] RIP: 0033:0x7f270b4d9a49
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
>  fs/f2fs/namei.c | 27 +++++++++++++--------------
>  1 file changed, 13 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> index a1c507b0b4ac..5d9584281935 100644
> --- a/fs/f2fs/namei.c
> +++ b/fs/f2fs/namei.c
> @@ -797,6 +797,7 @@ static int __f2fs_tmpfile(struct inode *dir, struct dentry *dentry,
>  
>  	if (whiteout) {
>  		f2fs_i_links_write(inode, false);
> +		inode->i_state |= I_LINKABLE;
>  		*whiteout = inode;
>  	} else {
>  		d_tmpfile(dentry, inode);
> @@ -867,6 +868,12 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>  			F2FS_I(old_dentry->d_inode)->i_projid)))
>  		return -EXDEV;
>  
> +	if (flags & RENAME_WHITEOUT) {
> +		err = f2fs_create_whiteout(old_dir, &whiteout);
> +		if (err)
> +			return err;
> +	}

To record quota info correctly, we need to create whiteout inode after
dquot_initialize(old_dir)?

> +
>  	err = dquot_initialize(old_dir);
>  	if (err)
>  		goto out;
> @@ -898,17 +905,11 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>  		}
>  	}
>  
> -	if (flags & RENAME_WHITEOUT) {
> -		err = f2fs_create_whiteout(old_dir, &whiteout);
> -		if (err)
> -			goto out_dir;
> -	}
> -
>  	if (new_inode) {
>  
>  		err = -ENOTEMPTY;
>  		if (old_dir_entry && !f2fs_empty_dir(new_inode))
> -			goto out_whiteout;
> +			goto out_dir;
>  
>  		err = -ENOENT;
>  		new_entry = f2fs_find_entry(new_dir, &new_dentry->d_name,
> @@ -916,7 +917,7 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>  		if (!new_entry) {
>  			if (IS_ERR(new_page))
>  				err = PTR_ERR(new_page);
> -			goto out_whiteout;
> +			goto out_dir;
>  		}
>  
>  		f2fs_balance_fs(sbi, true);
> @@ -948,7 +949,7 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>  		err = f2fs_add_link(new_dentry, old_inode);
>  		if (err) {
>  			f2fs_unlock_op(sbi);
> -			goto out_whiteout;
> +			goto out_dir;
>  		}
>  
>  		if (old_dir_entry)
> @@ -972,7 +973,7 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>  				if (IS_ERR(old_page))
>  					err = PTR_ERR(old_page);
>  				f2fs_unlock_op(sbi);
> -				goto out_whiteout;
> +				goto out_dir;
>  			}
>  		}
>  	}
> @@ -991,7 +992,6 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>  	f2fs_delete_entry(old_entry, old_page, old_dir, NULL);
>  
>  	if (whiteout) {
> -		whiteout->i_state |= I_LINKABLE;
>  		set_inode_flag(whiteout, FI_INC_LINK);
>  		err = f2fs_add_link(old_dentry, whiteout);

[ 3189.256353]  f2fs_do_add_link+0xc5/0x100 [f2fs]
[ 3189.258774]  f2fs_rename2+0xabf/0x1010 [f2fs]

Does the call stack point here? if so, we have set I_LINKABLE before
f2fs_add_link(), why the warning still be triggered?

Thanks,

>  		if (err)
> @@ -1027,15 +1027,14 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>  	f2fs_unlock_op(sbi);
>  	if (new_page)
>  		f2fs_put_page(new_page, 0);
> -out_whiteout:
> -	if (whiteout)
> -		iput(whiteout);
>  out_dir:
>  	if (old_dir_entry)
>  		f2fs_put_page(old_dir_page, 0);
>  out_old:
>  	f2fs_put_page(old_page, 0);
>  out:
> +	if (whiteout)
> +		iput(whiteout);
>  	return err;
>  }
>  
>