vfs: allow mkdir 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.

Add a new delegated_inode parameter to vfs_mkdir. All of the existing
callers set that to NULL for now, except for do_mkdirat which will
properly block until the lease is gone.

Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-6-52f3feebb2f2@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

drivers/base/devtmpfs.c

@@ -180,7 +180,7 @@ static int dev_mkdir(const char *name, umode_t mode)
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 
-	dentry = vfs_mkdir(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode);
+	dentry = vfs_mkdir(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode, NULL);
 	if (!IS_ERR(dentry))
 		/* mark as kernel-created inode */
 		d_inode(dentry)->i_private = &thread;

fs/cachefiles/namei.c

@@ -130,7 +130,7 @@ retry:
 			goto mkdir_error;
 		ret = cachefiles_inject_write_error();
 		if (ret == 0)
-			subdir = vfs_mkdir(&nop_mnt_idmap, d_inode(dir), subdir, 0700);
+			subdir = vfs_mkdir(&nop_mnt_idmap, d_inode(dir), subdir, 0700, NULL);
 		else
 			subdir = ERR_PTR(ret);
 		if (IS_ERR(subdir)) {

fs/ecryptfs/inode.c

@@ -508,7 +508,7 @@ static struct dentry *ecryptfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 		goto out;
 
 	lower_dentry = vfs_mkdir(&nop_mnt_idmap, lower_dir,
-				 lower_dentry, mode);
+				 lower_dentry, mode, NULL);
 	rc = PTR_ERR(lower_dentry);
 	if (IS_ERR(lower_dentry))
 		goto out;

fs/init.c

@@ -233,7 +233,7 @@ int __init init_mkdir(const char *pathname, umode_t mode)
 	error = security_path_mkdir(&path, dentry, mode);
 	if (!error) {
 		dentry = vfs_mkdir(mnt_idmap(path.mnt), path.dentry->d_inode,
-				  dentry, mode);
+				  dentry, mode, NULL);
 		if (IS_ERR(dentry))
 			error = PTR_ERR(dentry);
 	}

fs/namei.c

@@ -4407,10 +4407,11 @@ SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, d
 
 /**
  * vfs_mkdir - create directory returning correct dentry if possible
- * @idmap:	idmap of the mount the inode was found from
- * @dir:	inode of the parent directory
- * @dentry:	dentry of the child directory
- * @mode:	mode of the child directory
+ * @idmap:		idmap of the mount the inode was found from
+ * @dir:		inode of the parent directory
+ * @dentry:		dentry of the child directory
+ * @mode:		mode of the child directory
+ * @delegated_inode:	returns parent inode, if the inode is delegated.
  *
  * Create a directory.
  *
@@ -4427,7 +4428,8 @@ SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, d
  * In case of an error the dentry is dput() and an ERR_PTR() is returned.
  */
 struct dentry *vfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
-			 struct dentry *dentry, umode_t mode)
+			 struct dentry *dentry, umode_t mode,
+			 struct delegated_inode *delegated_inode)
 {
 	int error;
 	unsigned max_links = dir->i_sb->s_max_links;
@@ -4450,6 +4452,10 @@ struct dentry *vfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 	if (max_links && dir->i_nlink >= max_links)
 		goto err;
 
+	error = try_break_deleg(dir, delegated_inode);
+	if (error)
+		goto err;
+
 	de = dir->i_op->mkdir(idmap, dir, dentry, mode);
 	error = PTR_ERR(de);
 	if (IS_ERR(de))
@@ -4473,6 +4479,7 @@ int do_mkdirat(int dfd, struct filename *name, umode_t mode)
 	struct path path;
 	int error;
 	unsigned int lookup_flags = LOOKUP_DIRECTORY;
+	struct delegated_inode delegated_inode = { };
 
 retry:
 	dentry = filename_create(dfd, name, &path, lookup_flags);
@@ -4484,11 +4491,16 @@ retry:
 			mode_strip_umask(path.dentry->d_inode, mode));
 	if (!error) {
 		dentry = vfs_mkdir(mnt_idmap(path.mnt), path.dentry->d_inode,
-				  dentry, mode);
+				   dentry, mode, &delegated_inode);
 		if (IS_ERR(dentry))
 			error = PTR_ERR(dentry);
 	}
 	end_creating_path(&path, dentry);
+	if (is_delegated(&delegated_inode)) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry;
+	}
 	if (retry_estale(error, lookup_flags)) {
 		lookup_flags |= LOOKUP_REVAL;
 		goto retry;

fs/nfsd/nfs4recover.c

@@ -213,7 +213,7 @@ nfsd4_create_clid_dir(struct nfs4_client *clp)
 		 * as well be forgiving and just succeed silently.
 		 */
 		goto out_put;
-	dentry = vfs_mkdir(&nop_mnt_idmap, d_inode(dir), dentry, S_IRWXU);
+	dentry = vfs_mkdir(&nop_mnt_idmap, d_inode(dir), dentry, 0700, NULL);
 	if (IS_ERR(dentry))
 		status = PTR_ERR(dentry);
 out_put:

fs/nfsd/vfs.c

@@ -1558,7 +1558,7 @@ nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
 			nfsd_check_ignore_resizing(iap);
 		break;
 	case S_IFDIR:
-		dchild = vfs_mkdir(&nop_mnt_idmap, dirp, dchild, iap->ia_mode);
+		dchild = vfs_mkdir(&nop_mnt_idmap, dirp, dchild, iap->ia_mode, NULL);
 		if (IS_ERR(dchild)) {
 			host_err = PTR_ERR(dchild);
 		} else if (d_is_negative(dchild)) {

fs/overlayfs/overlayfs.h

@@ -248,7 +248,7 @@ static inline struct dentry *ovl_do_mkdir(struct ovl_fs *ofs,
 {
 	struct dentry *ret;
 
-	ret = vfs_mkdir(ovl_upper_mnt_idmap(ofs), dir, dentry, mode);
+	ret = vfs_mkdir(ovl_upper_mnt_idmap(ofs), dir, dentry, mode, NULL);
 	pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, PTR_ERR_OR_ZERO(ret));
 	return ret;
 }

fs/smb/server/vfs.c

@@ -230,7 +230,7 @@ int ksmbd_vfs_mkdir(struct ksmbd_work *work, const char *name, umode_t mode)
 	idmap = mnt_idmap(path.mnt);
 	mode |= S_IFDIR;
 	d = dentry;
-	dentry = vfs_mkdir(idmap, d_inode(path.dentry), dentry, mode);
+	dentry = vfs_mkdir(idmap, d_inode(path.dentry), dentry, mode, NULL);
 	if (IS_ERR(dentry))
 		err = PTR_ERR(dentry);
 	else if (d_is_negative(dentry))

fs/xfs/scrub/orphanage.c

@@ -167,7 +167,7 @@ xrep_orphanage_create(
 	 */
 	if (d_really_is_negative(orphanage_dentry)) {
 		orphanage_dentry = vfs_mkdir(&nop_mnt_idmap, root_inode,
-					     orphanage_dentry, 0750);
+					     orphanage_dentry, 0750, NULL);
 		error = PTR_ERR(orphanage_dentry);
 		if (IS_ERR(orphanage_dentry))
 			goto out_unlock_root;

include/linux/fs.h

@@ -2114,7 +2114,7 @@ bool inode_owner_or_capable(struct mnt_idmap *idmap,
 int vfs_create(struct mnt_idmap *, struct inode *,
 	       struct dentry *, umode_t, bool);
 struct dentry *vfs_mkdir(struct mnt_idmap *, struct inode *,
-			 struct dentry *, umode_t);
+			 struct dentry *, umode_t, struct delegated_inode *);
 int vfs_mknod(struct mnt_idmap *, struct inode *, struct dentry *,
               umode_t, dev_t);
 int vfs_symlink(struct mnt_idmap *, struct inode *,