linux-kernel - Re: [PATCH 4/6] fuse: return correct dentry for ->mkdir

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Message-ID: <20250222042402.GN1977892@ZenIV>
Date: Sat, 22 Feb 2025 04:24:02 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: NeilBrown <neilb@...e.de>
Cc: Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
	Miklos Szeredi <miklos@...redi.hu>, Xiubo Li <xiubli@...hat.com>,
	Ilya Dryomov <idryomov@...il.com>,
	Richard Weinberger <richard@....at>,
	Anton Ivanov <anton.ivanov@...bridgegreys.com>,
	Johannes Berg <johannes@...solutions.net>,
	Trond Myklebust <trondmy@...nel.org>,
	Anna Schumaker <anna@...nel.org>,
	Chuck Lever <chuck.lever@...cle.com>,
	Jeff Layton <jlayton@...nel.org>,
	Olga Kornievskaia <okorniev@...hat.com>,
	Dai Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-cifs@...r.kernel.org, linux-nfs@...r.kernel.org,
	linux-um@...ts.infradead.org, ceph-devel@...r.kernel.org,
	netfs@...ts.linux.dev
Subject: Re: [PATCH 4/6] fuse: return correct dentry for ->mkdir

On Fri, Feb 21, 2025 at 10:36:33AM +1100, NeilBrown wrote:

> @@ -871,7 +870,12 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
>  	args.in_args[0].value = &inarg;
>  	args.in_args[1].size = entry->d_name.len + 1;
>  	args.in_args[1].value = entry->d_name.name;
> -	return create_new_entry(idmap, fm, &args, dir, entry, mode);
> +	de = create_new_entry(idmap, fm, &args, dir, entry, mode);
> +	if (IS_ERR(de))
> +		return PTR_ERR(de);
> +	if (de)
> +		dput(de);
> +	return 0;

Can that really happen?

> @@ -934,7 +939,12 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
>  	args.in_args[1].value = entry->d_name.name;
>  	args.in_args[2].size = len;
>  	args.in_args[2].value = link;
> -	return create_new_entry(idmap, fm, &args, dir, entry, S_IFLNK);
> +	de = create_new_entry(idmap, fm, &args, dir, entry, S_IFLNK);
> +	if (IS_ERR(de))
> +		return PTR_ERR(de);
> +	if (de)
> +		dput(de);
> +	return 0;

Same question.

> +	de = create_new_entry(&invalid_mnt_idmap, fm, &args, newdir, newent, inode->i_mode);
> +	if (!IS_ERR(de)) {
> +		if (de)
> +			dput(de);
> +		de = NULL;

Whoa...  Details, please.  What's going on here?