linux-kernel - [PATCH RFC v2 05/28] vfs: allow rmdir to wait for delegation break on parent

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Message-Id: <20250602-dir-deleg-v2-5-a7919700de86@kernel.org>
Date: Mon, 02 Jun 2025 10:01:48 -0400
From: Jeff Layton <jlayton@...nel.org>
To: 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.com>, 
 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>
Cc: 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, 
 Jeff Layton <jlayton@...nel.org>
Subject: [PATCH RFC v2 05/28] vfs: allow rmdir to wait for delegation break
 on parent

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_rmdir as __vfs_rmdir, make it static and add a new
delegated_inode parameter. Add a vfs_rmdir wrapper that passes in a NULL
pointer for it. Add the necessary try_break_deleg calls to
__vfs_rmdir(). Convert do_rmdir to use __vfs_rmdir and wait for the
delegation break to complete before proceeding.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
 fs/namei.c | 51 ++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 34 insertions(+), 17 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 7c9e237ed1b1a535934ffe5e523424bb035e7ae0..2211ed9f427cc97391d068b1a33ce388266a3e02 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4438,22 +4438,8 @@ SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
 	return do_mkdirat(AT_FDCWD, getname(pathname), mode);
 }
 
-/**
- * vfs_rmdir - remove directory
- * @idmap:	idmap of the mount the inode was found from
- * @dir:	inode of the parent directory
- * @dentry:	dentry of the child directory
- *
- * Remove a directory.
- *
- * 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_rmdir(struct mnt_idmap *idmap, struct inode *dir,
-		     struct dentry *dentry)
+static int __vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
+		       struct dentry *dentry, struct inode **delegated_inode)
 {
 	int error = may_delete(idmap, dir, dentry, 1);
 
@@ -4475,6 +4461,10 @@ int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
 	if (error)
 		goto out;
 
+	error = try_break_deleg(dir, delegated_inode);
+	if (error)
+		goto out;
+
 	error = dir->i_op->rmdir(dir, dentry);
 	if (error)
 		goto out;
@@ -4491,6 +4481,26 @@ int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
 		d_delete_notify(dir, dentry);
 	return error;
 }
+
+/**
+ * vfs_rmdir - remove directory
+ * @idmap:	idmap of the mount the inode was found from
+ * @dir:	inode of the parent directory
+ * @dentry:	dentry of the child directory
+ *
+ * Remove a directory.
+ *
+ * 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_rmdir(struct mnt_idmap *idmap, struct inode *dir,
+		     struct dentry *dentry)
+{
+	return __vfs_rmdir(idmap, dir, dentry, NULL);
+}
 EXPORT_SYMBOL(vfs_rmdir);
 
 int do_rmdir(int dfd, struct filename *name)
@@ -4501,6 +4511,7 @@ int do_rmdir(int dfd, struct filename *name)
 	struct qstr last;
 	int type;
 	unsigned int lookup_flags = 0;
+	struct inode *delegated_inode = NULL;
 retry:
 	error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
 	if (error)
@@ -4530,7 +4541,8 @@ int do_rmdir(int dfd, struct filename *name)
 	error = security_path_rmdir(&path, dentry);
 	if (error)
 		goto exit4;
-	error = vfs_rmdir(mnt_idmap(path.mnt), path.dentry->d_inode, dentry);
+	error = __vfs_rmdir(mnt_idmap(path.mnt), path.dentry->d_inode,
+			    dentry, &delegated_inode);
 exit4:
 	dput(dentry);
 exit3:
@@ -4538,6 +4550,11 @@ int do_rmdir(int dfd, struct filename *name)
 	mnt_drop_write(path.mnt);
 exit2:
 	path_put(&path);
+	if (delegated_inode) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry;
+	}
 	if (retry_estale(error, lookup_flags)) {
 		lookup_flags |= LOOKUP_REVAL;
 		goto retry;

-- 
2.49.0