The current API requires a pointer to an inode pointer. It's easy for
callers to get this wrong. Add a new delegated_inode structure and use
that to pass back any inode that needs to be waited on.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/attr.c                |  2 +-
 fs/namei.c               | 18 +++++++++---------
 fs/open.c                |  8 ++++----
 fs/posix_acl.c           |  8 ++++----
 fs/utimes.c              |  4 ++--
 fs/xattr.c               | 12 ++++++------
 include/linux/filelock.h | 36 +++++++++++++++++++++++++++---------
 include/linux/fs.h       |  9 +++++----
 include/linux/xattr.h    |  4 ++--
 9 files changed, 60 insertions(+), 41 deletions(-)

diff --git a/fs/attr.c b/fs/attr.c
index 795f231d00e8eaaadf5b62f241655cb4b69cb507..b9ec6b47bab2fc2b561677b639633bd32994022f 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -415,7 +415,7 @@ EXPORT_SYMBOL(may_setattr);
  * performed on the raw inode simply pass @nop_mnt_idmap.
  */
 int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
-		  struct iattr *attr, struct inode **delegated_inode)
+		  struct iattr *attr, struct delegated_inode *delegated_inode)
 {
 	struct inode *inode = dentry->d_inode;
 	umode_t mode = inode->i_mode;
diff --git a/fs/namei.c b/fs/namei.c
index 7377020a2cba02501483020e0fc93c279fb38d3e..bf42f146f847a5330fc581595c7256af28d9db90 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4648,7 +4648,7 @@ SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
  * raw inode simply pass @nop_mnt_idmap.
  */
 int vfs_unlink(struct mnt_idmap *idmap, struct inode *dir,
-	       struct dentry *dentry, struct inode **delegated_inode)
+	       struct dentry *dentry, struct delegated_inode *delegated_inode)
 {
 	struct inode *target = dentry->d_inode;
 	int error = may_delete(idmap, dir, dentry, 0);
@@ -4706,7 +4706,7 @@ int do_unlinkat(int dfd, struct filename *name)
 	struct qstr last;
 	int type;
 	struct inode *inode = NULL;
-	struct inode *delegated_inode = NULL;
+	struct delegated_inode delegated_inode = { };
 	unsigned int lookup_flags = 0;
 retry:
 	error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
@@ -4743,7 +4743,7 @@ int do_unlinkat(int dfd, struct filename *name)
 	if (inode)
 		iput(inode);	/* truncate the inode here */
 	inode = NULL;
-	if (delegated_inode) {
+	if (is_delegated(&delegated_inode)) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)
 			goto retry_deleg;
@@ -4892,7 +4892,7 @@ SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newn
  */
 int vfs_link(struct dentry *old_dentry, struct mnt_idmap *idmap,
 	     struct inode *dir, struct dentry *new_dentry,
-	     struct inode **delegated_inode)
+	     struct delegated_inode *delegated_inode)
 {
 	struct inode *inode = old_dentry->d_inode;
 	unsigned max_links = dir->i_sb->s_max_links;
@@ -4968,7 +4968,7 @@ int do_linkat(int olddfd, struct filename *old, int newdfd,
 	struct mnt_idmap *idmap;
 	struct dentry *new_dentry;
 	struct path old_path, new_path;
-	struct inode *delegated_inode = NULL;
+	struct delegated_inode delegated_inode = { };
 	int how = 0;
 	int error;
 
@@ -5012,7 +5012,7 @@ int do_linkat(int olddfd, struct filename *old, int newdfd,
 			 new_dentry, &delegated_inode);
 out_dput:
 	end_creating_path(&new_path, new_dentry);
-	if (delegated_inode) {
+	if (is_delegated(&delegated_inode)) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error) {
 			path_put(&old_path);
@@ -5098,7 +5098,7 @@ int vfs_rename(struct renamedata *rd)
 	struct inode *new_dir = d_inode(rd->new_parent);
 	struct dentry *old_dentry = rd->old_dentry;
 	struct dentry *new_dentry = rd->new_dentry;
-	struct inode **delegated_inode = rd->delegated_inode;
+	struct delegated_inode *delegated_inode = rd->delegated_inode;
 	unsigned int flags = rd->flags;
 	bool is_dir = d_is_dir(old_dentry);
 	struct inode *source = old_dentry->d_inode;
@@ -5261,7 +5261,7 @@ int do_renameat2(int olddfd, struct filename *from, int newdfd,
 	struct path old_path, new_path;
 	struct qstr old_last, new_last;
 	int old_type, new_type;
-	struct inode *delegated_inode = NULL;
+	struct delegated_inode delegated_inode = { };
 	unsigned int lookup_flags = 0, target_flags =
 		LOOKUP_RENAME_TARGET | LOOKUP_CREATE;
 	bool should_retry = false;
@@ -5369,7 +5369,7 @@ int do_renameat2(int olddfd, struct filename *from, int newdfd,
 exit3:
 	unlock_rename(new_path.dentry, old_path.dentry);
 exit_lock_rename:
-	if (delegated_inode) {
+	if (is_delegated(&delegated_inode)) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)
 			goto retry_deleg;
diff --git a/fs/open.c b/fs/open.c
index 3d64372ecc675e4795eb0a0deda10f8f67b95640..fdaa6f08f6f4cac5c2fefd3eafa5e430e51f3979 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -631,7 +631,7 @@ SYSCALL_DEFINE1(chroot, const char __user *, filename)
 int chmod_common(const struct path *path, umode_t mode)
 {
 	struct inode *inode = path->dentry->d_inode;
-	struct inode *delegated_inode = NULL;
+	struct delegated_inode delegated_inode = { };
 	struct iattr newattrs;
 	int error;
 
@@ -651,7 +651,7 @@ int chmod_common(const struct path *path, umode_t mode)
 			      &newattrs, &delegated_inode);
 out_unlock:
 	inode_unlock(inode);
-	if (delegated_inode) {
+	if (is_delegated(&delegated_inode)) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)
 			goto retry_deleg;
@@ -756,7 +756,7 @@ int chown_common(const struct path *path, uid_t user, gid_t group)
 	struct mnt_idmap *idmap;
 	struct user_namespace *fs_userns;
 	struct inode *inode = path->dentry->d_inode;
-	struct inode *delegated_inode = NULL;
+	struct delegated_inode delegated_inode = { };
 	int error;
 	struct iattr newattrs;
 	kuid_t uid;
@@ -791,7 +791,7 @@ int chown_common(const struct path *path, uid_t user, gid_t group)
 		error = notify_change(idmap, path->dentry, &newattrs,
 				      &delegated_inode);
 	inode_unlock(inode);
-	if (delegated_inode) {
+	if (is_delegated(&delegated_inode)) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)
 			goto retry_deleg;
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 4050942ab52f95741da2df13d191ade5c5ca12a2..768f027c142811ea907fe8545155ba7abd016305 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -1091,7 +1091,7 @@ int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 	int acl_type;
 	int error;
 	struct inode *inode = d_inode(dentry);
-	struct inode *delegated_inode = NULL;
+	struct delegated_inode delegated_inode = { };
 
 	acl_type = posix_acl_type(acl_name);
 	if (acl_type < 0)
@@ -1141,7 +1141,7 @@ int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 out_inode_unlock:
 	inode_unlock(inode);
 
-	if (delegated_inode) {
+	if (is_delegated(&delegated_inode)) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)
 			goto retry_deleg;
@@ -1212,7 +1212,7 @@ int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 	int acl_type;
 	int error;
 	struct inode *inode = d_inode(dentry);
-	struct inode *delegated_inode = NULL;
+	struct delegated_inode delegated_inode = { };
 
 	acl_type = posix_acl_type(acl_name);
 	if (acl_type < 0)
@@ -1249,7 +1249,7 @@ int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 out_inode_unlock:
 	inode_unlock(inode);
 
-	if (delegated_inode) {
+	if (is_delegated(&delegated_inode)) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)
 			goto retry_deleg;
diff --git a/fs/utimes.c b/fs/utimes.c
index c7c7958e57b22f91646ca9f76d18781b64d371a3..bf9f45bdef54947de7ac55c9f873ae9d0336dafa 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -22,7 +22,7 @@ int vfs_utimes(const struct path *path, struct timespec64 *times)
 	int error;
 	struct iattr newattrs;
 	struct inode *inode = path->dentry->d_inode;
-	struct inode *delegated_inode = NULL;
+	struct delegated_inode delegated_inode = { };
 
 	if (times) {
 		if (!nsec_valid(times[0].tv_nsec) ||
@@ -66,7 +66,7 @@ int vfs_utimes(const struct path *path, struct timespec64 *times)
 	error = notify_change(mnt_idmap(path->mnt), path->dentry, &newattrs,
 			      &delegated_inode);
 	inode_unlock(inode);
-	if (delegated_inode) {
+	if (is_delegated(&delegated_inode)) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)
 			goto retry_deleg;
diff --git a/fs/xattr.c b/fs/xattr.c
index 8851a5ef34f5ab34383975dd4cef537de3f6391e..32d445fb60aaf2aaf4b16b62934dc99bad378067 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -274,7 +274,7 @@ int __vfs_setxattr_noperm(struct mnt_idmap *idmap,
 int
 __vfs_setxattr_locked(struct mnt_idmap *idmap, struct dentry *dentry,
 		      const char *name, const void *value, size_t size,
-		      int flags, struct inode **delegated_inode)
+		      int flags, struct delegated_inode *delegated_inode)
 {
 	struct inode *inode = dentry->d_inode;
 	int error;
@@ -305,7 +305,7 @@ vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	     const char *name, const void *value, size_t size, int flags)
 {
 	struct inode *inode = dentry->d_inode;
-	struct inode *delegated_inode = NULL;
+	struct delegated_inode delegated_inode = { };
 	const void  *orig_value = value;
 	int error;
 
@@ -322,7 +322,7 @@ vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 				      flags, &delegated_inode);
 	inode_unlock(inode);
 
-	if (delegated_inode) {
+	if (is_delegated(&delegated_inode)) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)
 			goto retry_deleg;
@@ -533,7 +533,7 @@ EXPORT_SYMBOL(__vfs_removexattr);
 int
 __vfs_removexattr_locked(struct mnt_idmap *idmap,
 			 struct dentry *dentry, const char *name,
-			 struct inode **delegated_inode)
+			 struct delegated_inode *delegated_inode)
 {
 	struct inode *inode = dentry->d_inode;
 	int error;
@@ -567,7 +567,7 @@ vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		const char *name)
 {
 	struct inode *inode = dentry->d_inode;
-	struct inode *delegated_inode = NULL;
+	struct delegated_inode delegated_inode = { };
 	int error;
 
 retry_deleg:
@@ -576,7 +576,7 @@ vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
 					 name, &delegated_inode);
 	inode_unlock(inode);
 
-	if (delegated_inode) {
+	if (is_delegated(&delegated_inode)) {
 		error = break_deleg_wait(&delegated_inode);
 		if (!error)
 			goto retry_deleg;
diff --git a/include/linux/filelock.h b/include/linux/filelock.h
index 47da6aa28d8dc9122618d02c6608deda0f3c4d3e..208d108df2d73a9df65e5dc9968d074af385f881 100644
--- a/include/linux/filelock.h
+++ b/include/linux/filelock.h
@@ -486,25 +486,35 @@ static inline int break_deleg(struct inode *inode, unsigned int flags)
 	return 0;
 }
 
-static inline int try_break_deleg(struct inode *inode, struct inode **delegated_inode)
+struct delegated_inode {
+	struct inode *di_inode;
+};
+
+static inline bool is_delegated(struct delegated_inode *di)
+{
+	return di->di_inode;
+}
+
+static inline int try_break_deleg(struct inode *inode,
+				  struct delegated_inode *di)
 {
 	int ret;
 
 	ret = break_deleg(inode, LEASE_BREAK_NONBLOCK);
-	if (ret == -EWOULDBLOCK && delegated_inode) {
-		*delegated_inode = inode;
+	if (ret == -EWOULDBLOCK && di) {
+		di->di_inode = inode;
 		ihold(inode);
 	}
 	return ret;
 }
 
-static inline int break_deleg_wait(struct inode **delegated_inode)
+static inline int break_deleg_wait(struct delegated_inode *di)
 {
 	int ret;
 
-	ret = break_deleg(*delegated_inode, 0);
-	iput(*delegated_inode);
-	*delegated_inode = NULL;
+	ret = break_deleg(di->di_inode, 0);
+	iput(di->di_inode);
+	di->di_inode = NULL;
 	return ret;
 }
 
@@ -523,6 +533,13 @@ static inline int break_layout(struct inode *inode, bool wait)
 }
 
 #else /* !CONFIG_FILE_LOCKING */
+struct delegated_inode { };
+
+static inline bool is_delegated(struct delegated_inode *di)
+{
+	return false;
+}
+
 static inline int break_lease(struct inode *inode, bool wait)
 {
 	return 0;
@@ -533,12 +550,13 @@ static inline int break_deleg(struct inode *inode, unsigned int flags)
 	return 0;
 }
 
-static inline int try_break_deleg(struct inode *inode, struct inode **delegated_inode)
+static inline int try_break_deleg(struct inode *inode,
+				  struct delegated_inode *delegated_inode)
 {
 	return 0;
 }
 
-static inline int break_deleg_wait(struct inode **delegated_inode)
+static inline int break_deleg_wait(struct delegated_inode *delegated_inode)
 {
 	BUG();
 	return 0;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c895146c1444be36e0a779df55622cc38c9419ff..909a88e3979d4f1ba3104f3d05145e1096ed44d5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -80,6 +80,7 @@ struct fs_context;
 struct fs_parameter_spec;
 struct file_kattr;
 struct iomap_ops;
+struct delegated_inode;
 
 extern void __init inode_init(void);
 extern void __init inode_init_early(void);
@@ -2119,10 +2120,10 @@ int vfs_mknod(struct mnt_idmap *, struct inode *, struct dentry *,
 int vfs_symlink(struct mnt_idmap *, struct inode *,
 		struct dentry *, const char *);
 int vfs_link(struct dentry *, struct mnt_idmap *, struct inode *,
-	     struct dentry *, struct inode **);
+	     struct dentry *, struct delegated_inode *);
 int vfs_rmdir(struct mnt_idmap *, struct inode *, struct dentry *);
 int vfs_unlink(struct mnt_idmap *, struct inode *, struct dentry *,
-	       struct inode **);
+	       struct delegated_inode *);
 
 /**
  * struct renamedata - contains all information required for renaming
@@ -2140,7 +2141,7 @@ struct renamedata {
 	struct dentry *old_dentry;
 	struct dentry *new_parent;
 	struct dentry *new_dentry;
-	struct inode **delegated_inode;
+	struct delegated_inode *delegated_inode;
 	unsigned int flags;
 } __randomize_layout;
 
@@ -3071,7 +3072,7 @@ static inline int bmap(struct inode *inode,  sector_t *block)
 #endif
 
 int notify_change(struct mnt_idmap *, struct dentry *,
-		  struct iattr *, struct inode **);
+		  struct iattr *, struct delegated_inode *);
 int inode_permission(struct mnt_idmap *, struct inode *, int);
 int generic_permission(struct mnt_idmap *, struct inode *, int);
 static inline int file_permission(struct file *file, int mask)
diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index 86b0d47984a16d935dd1c45ca80a3b8bb5b7295b..64e9afe7d647dc38f686a4b5c6f765e061cde54c 100644
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -85,12 +85,12 @@ int __vfs_setxattr_noperm(struct mnt_idmap *, struct dentry *,
 			  const char *, const void *, size_t, int);
 int __vfs_setxattr_locked(struct mnt_idmap *, struct dentry *,
 			  const char *, const void *, size_t, int,
-			  struct inode **);
+			  struct delegated_inode *);
 int vfs_setxattr(struct mnt_idmap *, struct dentry *, const char *,
 		 const void *, size_t, int);
 int __vfs_removexattr(struct mnt_idmap *, struct dentry *, const char *);
 int __vfs_removexattr_locked(struct mnt_idmap *, struct dentry *,
-			     const char *, struct inode **);
+			     const char *, struct delegated_inode *);
 int vfs_removexattr(struct mnt_idmap *, struct dentry *, const char *);
 
 ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size);

-- 
2.51.1