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Message-ID: <ke7z7ptll7svm4ygbtbmv7ezv7rox75ct6mv5sn73lrnqp6g2r@ju2aolr2n5n7>
Date: Fri, 26 Sep 2025 17:32:59 +0200
From: Jan Kara <jack@...e.cz>
To: Jeff Layton <jlayton@...nel.org>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 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>,
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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>,
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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,
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Subject: Re: [PATCH v3 08/38] vfs: make vfs_mknod break delegations on parent
directory
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>
Honza
> ---
> 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
>
--
Jan Kara <jack@...e.com>
SUSE Labs, CR
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