linux-kernel - Re: [PATCH 3/9] udf_rename(): only access the child content on cross-directory rename

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Message-ID: <20231123092251.pjeqi2hyrpmn24wi@quack3>
Date:   Thu, 23 Nov 2023 10:22:51 +0100
From:   Jan Kara <jack@...e.cz>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     linux-fsdevel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mo Zou <lostzoumo@...il.com>, Jan Kara <jack@...e.cz>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/9] udf_rename(): only access the child content on
 cross-directory rename

On Wed 22-11-23 19:36:46, Al Viro wrote:
> We can't really afford locking the source on same-directory rename;
> currently vfs_rename() tries to do that, but it will have to be
> changed.  The logics in udf_rename() is lazy and goes looking for
> ".." in source even in same-directory case.  It's not hard to get
> rid of that, leaving that behaviour only for cross-directory case;
> that VFS can get locks safely (and will keep doing that after the
> coming changes).
> 
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/udf/namei.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/udf/namei.c b/fs/udf/namei.c
> index 3508ac484da3..fac806a7a8d4 100644
> --- a/fs/udf/namei.c
> +++ b/fs/udf/namei.c
> @@ -766,7 +766,7 @@ static int udf_rename(struct mnt_idmap *idmap, struct inode *old_dir,
>  	struct inode *old_inode = d_inode(old_dentry);
>  	struct inode *new_inode = d_inode(new_dentry);
>  	struct udf_fileident_iter oiter, niter, diriter;
> -	bool has_diriter = false;
> +	bool has_diriter = false, is_dir = false;
>  	int retval;
>  	struct kernel_lb_addr tloc;
>  
> @@ -789,6 +789,9 @@ static int udf_rename(struct mnt_idmap *idmap, struct inode *old_dir,
>  			if (!empty_dir(new_inode))
>  				goto out_oiter;
>  		}
> +		is_dir = true;
> +	}
> +	if (is_dir && old_dir != new_dir) {
>  		retval = udf_fiiter_find_entry(old_inode, &dotdot_name,
>  					       &diriter);
>  		if (retval == -ENOENT) {
> @@ -878,7 +881,9 @@ static int udf_rename(struct mnt_idmap *idmap, struct inode *old_dir,
>  			       udf_dir_entry_len(&diriter.fi));
>  		udf_fiiter_write_fi(&diriter, NULL);
>  		udf_fiiter_release(&diriter);
> +	}
>  
> +	if (is_dir) {
>  		inode_dec_link_count(old_dir);
>  		if (new_inode)
>  			inode_dec_link_count(new_inode);
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR