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Message-ID: <e08f4e061a9bff08066c7a255d8f9277add272f6.camel@kernel.org>
Date: Fri, 26 Sep 2025 12:27:07 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Jan Kara <jack@...e.cz>
Cc: Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner
<brauner@...nel.org>, Chuck Lever <chuck.lever@...cle.com>, Alexander Aring
<alex.aring@...il.com>, Trond Myklebust <trondmy@...nel.org>, Anna
Schumaker <anna@...nel.org>, Steve French <sfrench@...ba.org>, Ronnie
Sahlberg <ronniesahlberg@...il.com>, Shyam Prasad N
<sprasad@...rosoft.com>, Tom Talpey <tom@...pey.com>, Bharath SM
<bharathsm@...rosoft.com>, NeilBrown <neil@...wn.name>, Olga Kornievskaia
<okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>, Jonathan Corbet
<corbet@....net>, Amir Goldstein <amir73il@...il.com>, Miklos Szeredi
<miklos@...redi.hu>, Paulo Alcantara <pc@...guebit.org>, Greg
Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki"
<rafael@...nel.org>, Danilo Krummrich <dakr@...nel.org>, David Howells
<dhowells@...hat.com>, Tyler Hicks <code@...icks.com>, Namjae Jeon
<linkinjeon@...nel.org>, Steve French <smfrench@...il.com>, Sergey
Senozhatsky <senozhatsky@...omium.org>, Carlos Maiolino <cem@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu
<mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Rick Macklem <rick.macklem@...il.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,
linux-doc@...r.kernel.org, netfs@...ts.linux.dev, ecryptfs@...r.kernel.org,
linux-unionfs@...r.kernel.org, linux-xfs@...r.kernel.org,
linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH v3 08/38] vfs: make vfs_mknod break delegations on
parent directory
On Fri, 2025-09-26 at 17:32 +0200, Jan Kara wrote:
> On Wed 24-09-25 14:05:54, 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.
> >
> > Rename vfs_mknod as __vfs_mknod, make it static, and add a new
> > delegated_inode parameter. Make do_mknodat call __vfs_mknod and wait
> > synchronously for delegation breaks to complete. Add a new exported
> > vfs_mknod wrapper that calls __vfs_mknod with a NULL delegated_inode
> > pointer.
> >
> > Signed-off-by: Jeff Layton <jlayton@...nel.org>
>
> Looks good. Feel free to add:
>
> Reviewed-by: Jan Kara <jack@...e.cz>
>
Thanks.
FYI, I've revised this and the rmdir patches to get rid of the wrapper,
and just have the callers pass in NULL directly. I think that's more
along the lines of what Christian preferred.
>
> > ---
> > fs/namei.c | 57 +++++++++++++++++++++++++++++++++++----------------------
> > 1 file changed, 35 insertions(+), 22 deletions(-)
> >
> > diff --git a/fs/namei.c b/fs/namei.c
> > index d4b8330a3eb97e205dc2e71766fed1e45503323b..7bcd898c84138061030f1f8b91273261cdf2a9b4 100644
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@ -4215,24 +4215,9 @@ inline struct dentry *user_path_create(int dfd, const char __user *pathname,
> > }
> > EXPORT_SYMBOL(user_path_create);
> >
> > -/**
> > - * vfs_mknod - create device node or file
> > - * @idmap: idmap of the mount the inode was found from
> > - * @dir: inode of the parent directory
> > - * @dentry: dentry of the child device node
> > - * @mode: mode of the child device node
> > - * @dev: device number of device to create
> > - *
> > - * Create a device node or file.
> > - *
> > - * If the inode has been found through an idmapped mount the idmap of
> > - * the vfsmount must be passed through @idmap. This function will then take
> > - * care to map the inode according to @idmap before checking permissions.
> > - * On non-idmapped mounts or if permission checking is to be performed on the
> > - * raw inode simply pass @nop_mnt_idmap.
> > - */
> > -int vfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
> > - struct dentry *dentry, umode_t mode, dev_t dev)
> > +static int __vfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
> > + struct dentry *dentry, umode_t mode, dev_t dev,
> > + struct inode **delegated_inode)
> > {
> > bool is_whiteout = S_ISCHR(mode) && dev == WHITEOUT_DEV;
> > int error = may_create(idmap, dir, dentry);
> > @@ -4256,11 +4241,37 @@ int vfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
> > if (error)
> > return error;
> >
> > + error = try_break_deleg(dir, delegated_inode);
> > + if (error)
> > + return error;
> > +
> > error = dir->i_op->mknod(idmap, dir, dentry, mode, dev);
> > if (!error)
> > fsnotify_create(dir, dentry);
> > return error;
> > }
> > +
> > +/**
> > + * vfs_mknod - create device node or file
> > + * @idmap: idmap of the mount the inode was found from
> > + * @dir: inode of the parent directory
> > + * @dentry: dentry of the child device node
> > + * @mode: mode of the child device node
> > + * @dev: device number of device to create
> > + *
> > + * Create a device node or file.
> > + *
> > + * If the inode has been found through an idmapped mount the idmap of
> > + * the vfsmount must be passed through @idmap. This function will then take
> > + * care to map the inode according to @idmap before checking permissions.
> > + * On non-idmapped mounts or if permission checking is to be performed on the
> > + * raw inode simply pass @nop_mnt_idmap.
> > + */
> > +int vfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
> > + struct dentry *dentry, umode_t mode, dev_t dev)
> > +{
> > + return __vfs_mknod(idmap, dir, dentry, mode, dev, NULL);
> > +}
> > EXPORT_SYMBOL(vfs_mknod);
> >
> > static int may_mknod(umode_t mode)
> > @@ -4314,12 +4325,14 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode,
> > security_path_post_mknod(idmap, dentry);
> > break;
> > case S_IFCHR: case S_IFBLK:
> > - error = vfs_mknod(idmap, path.dentry->d_inode,
> > - dentry, mode, new_decode_dev(dev));
> > + error = __vfs_mknod(idmap, path.dentry->d_inode,
> > + dentry, mode, new_decode_dev(dev),
> > + &delegated_inode);
> > break;
> > case S_IFIFO: case S_IFSOCK:
> > - error = vfs_mknod(idmap, path.dentry->d_inode,
> > - dentry, mode, 0);
> > + error = __vfs_mknod(idmap, path.dentry->d_inode,
> > + dentry, mode, 0,
> > + &delegated_inode);
> > break;
> > }
> > out2:
> >
> > --
> > 2.51.0
> >
--
Jeff Layton <jlayton@...nel.org>
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