Re: [PATCH v5 03/17] filelock: add struct delegated_inode

On Wed 05-11-25 11:53:49, Jeff Layton wrote:
> 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 <[email protected]>

I didn't find anything particularly problematic with struct inode ** but I
agree this seems a tad bit cleaner and harder to get wrong. So feel free to
add:

Reviewed-by: Jan Kara <[email protected]>

								Honza

> ---
>  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
> 
-- 
Jan Kara <[email protected]>
SUSE Labs, CR