netdev - Re: [PATCH RFC 06/24] vfs: break parent dir delegations in open(..., O

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Message-ID: <20240317001942.GJ538574@ZenIV>
Date: Sun, 17 Mar 2024 00:19:42 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: Jeff Layton <jlayton@...nel.org>
Cc: Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
	Chuck Lever <chuck.lever@...cle.com>,
	Alexander Aring <alex.aring@...il.com>,
	Trond Myklebust <trond.myklebust@...merspace.com>,
	Anna Schumaker <anna@...nel.org>, Steve French <sfrench@...ba.org>,
	Paulo Alcantara <pc@...guebit.com>,
	Ronnie Sahlberg <ronniesahlberg@...il.com>,
	Shyam Prasad N <sprasad@...rosoft.com>, Tom Talpey <tom@...pey.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	David Howells <dhowells@...hat.com>, Tyler Hicks <code@...icks.com>,
	Neil Brown <neilb@...e.de>, Olga Kornievskaia <kolga@...app.com>,
	Dai Ngo <Dai.Ngo@...cle.com>, Miklos Szeredi <miklos@...redi.hu>,
	Amir Goldstein <amir73il@...il.com>,
	Namjae Jeon <linkinjeon@...nel.org>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-nfs@...r.kernel.org, linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org, netfs@...ts.linux.dev,
	ecryptfs@...r.kernel.org, linux-unionfs@...r.kernel.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH RFC 06/24] vfs: break parent dir delegations in open(...,
 O_CREAT) codepath

On Fri, Mar 15, 2024 at 12:52:57PM -0400, Jeff Layton wrote:
> In order to add directory delegation support, we need to break
> delegations on the parent whenever there is going to be a change in the
> directory.
> 
> Add a delegated_inode parameter to lookup_open and have it break the
> delegation. Then, open_last_lookups can wait for the delegation break
> and retry the call to lookup_open once it's done.

> @@ -3490,6 +3490,11 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file,

Wait a sec - are you going to do anything to the atomic_open side of things?
 
>  	/* Negative dentry, just create the file */
>  	if (!dentry->d_inode && (open_flag & O_CREAT)) {
> +		/* but break the directory lease first! */
> +		error = try_break_deleg(dir_inode, delegated_inode);
> +		if (error)
> +			goto out_dput;