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Message-ID: <vuf6ypnlwgo6edemvtdhx3cpoufpr2iojbzqd4urocqjuoxj76@v7xwlpwnn77a>
Date: Mon, 20 Oct 2025 11:38:41 +0200
From: Jan Kara <jack@...e.cz>
To: Jeff Layton <jlayton@...nel.org>
Cc: Miklos Szeredi <miklos@...redi.hu>,
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>, Paulo Alcantara <pc@...guebit.org>,
Ronnie Sahlberg <ronniesahlberg@...il.com>, Shyam Prasad N <sprasad@...rosoft.com>,
Tom Talpey <tom@...pey.com>, Bharath SM <bharathsm@...rosoft.com>,
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>, NeilBrown <neil@...wn.name>,
Olga Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>,
Amir Goldstein <amir73il@...il.com>, Namjae Jeon <linkinjeon@...nel.org>,
Steve French <smfrench@...il.com>, Sergey Senozhatsky <senozhatsky@...omium.org>,
Carlos Maiolino <cem@...nel.org>, Kuniyuki Iwashima <kuniyu@...gle.com>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
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, linux-xfs@...r.kernel.org,
netdev@...r.kernel.org
Subject: Re: [PATCH 08/13] vfs: make vfs_mknod break delegations on parent
directory
On Mon 13-10-25 10:48:06, 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 new delegated_inode return pointer to vfs_mknod() and have the
> appropriate callers wait when there is an outstanding delegation. All
> other callers just set the pointer to NULL.
>
> Signed-off-by: Jeff Layton <jlayton@...nel.org>
Looks good. Feel free to add:
Reviewed-by: Jan Kara <jack@...e.cz>
Honza
> ---
> drivers/base/devtmpfs.c | 2 +-
> fs/ecryptfs/inode.c | 2 +-
> fs/init.c | 2 +-
> fs/namei.c | 25 +++++++++++++++++--------
> fs/nfsd/vfs.c | 2 +-
> fs/overlayfs/overlayfs.h | 2 +-
> include/linux/fs.h | 4 ++--
> net/unix/af_unix.c | 2 +-
> 8 files changed, 25 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
> index 104025104ef75381984fd94dfbd50feeaa8cdd22..2f576ecf18324f767cd5ac6cbd28adbf9f46b958 100644
> --- a/drivers/base/devtmpfs.c
> +++ b/drivers/base/devtmpfs.c
> @@ -231,7 +231,7 @@ static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
> return PTR_ERR(dentry);
>
> err = vfs_mknod(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode,
> - dev->devt);
> + dev->devt, NULL);
> if (!err) {
> struct iattr newattrs;
>
> diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
> index 88631291b32535f623a3fbe4ea9b6ed48a306ca0..acef6d921167268d4590c688894d4522016db0dd 100644
> --- a/fs/ecryptfs/inode.c
> +++ b/fs/ecryptfs/inode.c
> @@ -565,7 +565,7 @@ ecryptfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
> rc = lock_parent(dentry, &lower_dentry, &lower_dir);
> if (!rc)
> rc = vfs_mknod(&nop_mnt_idmap, lower_dir,
> - lower_dentry, mode, dev);
> + lower_dentry, mode, dev, NULL);
> if (rc || d_really_is_negative(lower_dentry))
> goto out;
> rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
> diff --git a/fs/init.c b/fs/init.c
> index 895f8a09a71acfd03e11164e3b441a7d4e2de146..4f02260dd65b0dfcbfbf5812d2ec6a33444a3b1f 100644
> --- a/fs/init.c
> +++ b/fs/init.c
> @@ -157,7 +157,7 @@ int __init init_mknod(const char *filename, umode_t mode, unsigned int dev)
> error = security_path_mknod(&path, dentry, mode, dev);
> if (!error)
> error = vfs_mknod(mnt_idmap(path.mnt), path.dentry->d_inode,
> - dentry, mode, new_decode_dev(dev));
> + dentry, mode, new_decode_dev(dev), NULL);
> end_creating_path(&path, dentry);
> return error;
> }
> diff --git a/fs/namei.c b/fs/namei.c
> index 1427c53e13978e70adefdc572b71247536985430..2e1e3f0068a28271e07aa0fa0c7e0b04582400fe 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -4302,13 +4302,15 @@ inline struct dentry *start_creating_user_path(
> }
> EXPORT_SYMBOL(start_creating_user_path);
>
> +
> /**
> * 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
> + * @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
> + * @delegated_inode: returns parent inode, if the inode is delegated.
> *
> * Create a device node or file.
> *
> @@ -4319,7 +4321,8 @@ EXPORT_SYMBOL(start_creating_user_path);
> * 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)
> + 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);
> @@ -4343,6 +4346,10 @@ 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);
> @@ -4402,11 +4409,13 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode,
> break;
> case S_IFCHR: case S_IFBLK:
> error = vfs_mknod(idmap, path.dentry->d_inode,
> - dentry, mode, new_decode_dev(dev));
> + 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);
> + dentry, mode, 0,
> + &delegated_inode);
> break;
> }
> out2:
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index 7d8cd2595f197be9741ee6320d43ed6651896647..858485c76b6524e965b7cbc92f67c1a4eb19e34e 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -1660,7 +1660,7 @@ nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
> case S_IFIFO:
> case S_IFSOCK:
> host_err = vfs_mknod(&nop_mnt_idmap, dirp, dchild,
> - iap->ia_mode, rdev);
> + iap->ia_mode, rdev, NULL);
> break;
> default:
> printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index d215d7349489686b66bb66e939b27046f7d836f6..8b8c99e9e1a518c365cfff952d391887ec18d453 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -257,7 +257,7 @@ static inline int ovl_do_mknod(struct ovl_fs *ofs,
> struct inode *dir, struct dentry *dentry,
> umode_t mode, dev_t dev)
> {
> - int err = vfs_mknod(ovl_upper_mnt_idmap(ofs), dir, dentry, mode, dev);
> + int err = vfs_mknod(ovl_upper_mnt_idmap(ofs), dir, dentry, mode, dev, NULL);
>
> pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
> return err;
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index d8bdaf7c87502ff17775602f5391d375738b4ed8..4ad49b39441b2c9088fd01a7e0e46a6511c26d2e 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2115,7 +2115,7 @@ int vfs_create(struct mnt_idmap *, struct inode *,
> struct dentry *vfs_mkdir(struct mnt_idmap *, struct inode *,
> struct dentry *, umode_t, struct inode **);
> int vfs_mknod(struct mnt_idmap *, struct inode *, struct dentry *,
> - umode_t, dev_t);
> + umode_t, dev_t, struct inode **);
> int vfs_symlink(struct mnt_idmap *, struct inode *,
> struct dentry *, const char *);
> int vfs_link(struct dentry *, struct mnt_idmap *, struct inode *,
> @@ -2151,7 +2151,7 @@ static inline int vfs_whiteout(struct mnt_idmap *idmap,
> struct inode *dir, struct dentry *dentry)
> {
> return vfs_mknod(idmap, dir, dentry, S_IFCHR | WHITEOUT_MODE,
> - WHITEOUT_DEV);
> + WHITEOUT_DEV, NULL);
> }
>
> struct file *kernel_tmpfile_open(struct mnt_idmap *idmap,
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 768098dec2310008632558ae928703b37c3cc8ef..db1fd8d6a84c2c7c0d45b43d9c5a936b3d491b7b 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -1399,7 +1399,7 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
> idmap = mnt_idmap(parent.mnt);
> err = security_path_mknod(&parent, dentry, mode, 0);
> if (!err)
> - err = vfs_mknod(idmap, d_inode(parent.dentry), dentry, mode, 0);
> + err = vfs_mknod(idmap, d_inode(parent.dentry), dentry, mode, 0, NULL);
> if (err)
> goto out_path;
> err = mutex_lock_interruptible(&u->bindlock);
>
> --
> 2.51.0
>
--
Jan Kara <jack@...e.com>
SUSE Labs, CR
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