Merge tag 'v6.4/vfs.acl' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull acl updates from Christian Brauner:
 "After finishing the introduction of the new posix acl api last cycle
  the generic POSIX ACL xattr handlers are still around in the
  filesystems xattr handlers for two reasons:

   (1) Because a few filesystems rely on the ->list() method of the
       generic POSIX ACL xattr handlers in their ->listxattr() inode
       operation.

   (2) POSIX ACLs are only available if IOP_XATTR is raised. The
       IOP_XATTR flag is raised in inode_init_always() based on whether
       the sb->s_xattr pointer is non-NULL. IOW, the registered xattr
       handlers of the filesystem are used to raise IOP_XATTR. Removing
       the generic POSIX ACL xattr handlers from all filesystems would
       risk regressing filesystems that only implement POSIX ACL support
       and no other xattrs (nfs3 comes to mind).

  This contains the work to decouple POSIX ACLs from the IOP_XATTR flag
  as they don't depend on xattr handlers anymore. So it's now possible
  to remove the generic POSIX ACL xattr handlers from the sb->s_xattr
  list of all filesystems. This is a crucial step as the generic POSIX
  ACL xattr handlers aren't used for POSIX ACLs anymore and POSIX ACLs
  don't depend on the xattr infrastructure anymore.

  Adressing problem (1) will require more long-term work. It would be
  best to get rid of the ->list() method of xattr handlers completely at
  some point.

  For erofs, ext{2,4}, f2fs, jffs2, ocfs2, and reiserfs the nop POSIX
  ACL xattr handler is kept around so they can continue to use
  array-based xattr handler indexing.

  This update does simplify the ->listxattr() implementation of all
  these filesystems however"

* tag 'v6.4/vfs.acl' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  acl: don't depend on IOP_XATTR
  ovl: check for ->listxattr() support
  reiserfs: rework priv inode handling
  fs: rename generic posix acl handlers
  reiserfs: rework ->listxattr() implementation
  fs: simplify ->listxattr() implementation
  fs: drop unused posix acl handlers
  xattr: remove unused argument
  xattr: add listxattr helper
  xattr: simplify listxattr helpers

3 files changed, 28 insertions, 3 deletions

diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h
index 21cc29b8a9e8..0e65b3d634d9 100644
--- a/include/linux/posix_acl.h
+++ b/include/linux/posix_acl.h
@@ -106,6 +106,8 @@ struct posix_acl *vfs_get_acl(struct mnt_idmap *idmap,
 			      struct dentry *dentry, const char *acl_name);
 int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		   const char *acl_name);
+int posix_acl_listxattr(struct inode *inode, char **buffer,
+			ssize_t *remaining_size);
 #else
 static inline int posix_acl_chmod(struct mnt_idmap *idmap,
 				  struct dentry *dentry, umode_t mode)
@@ -153,6 +155,11 @@ static inline int vfs_remove_acl(struct mnt_idmap *idmap,
 {
 	return -EOPNOTSUPP;
 }
+static inline int posix_acl_listxattr(struct inode *inode, char **buffer,
+				      ssize_t *remaining_size)
+{
+	return 0;
+}
 #endif /* CONFIG_FS_POSIX_ACL */
 
 struct posix_acl *get_inode_acl(struct inode *inode, int type);
diff --git a/include/linux/posix_acl_xattr.h b/include/linux/posix_acl_xattr.h
index 54cd7a14330d..e86f3b731da2 100644
--- a/include/linux/posix_acl_xattr.h
+++ b/include/linux/posix_acl_xattr.h
@@ -68,7 +68,8 @@ static inline int posix_acl_type(const char *name)
 	return -1;
 }
 
-extern const struct xattr_handler posix_acl_access_xattr_handler;
-extern const struct xattr_handler posix_acl_default_xattr_handler;
+/* These are legacy handlers. Don't use them for new code. */
+extern const struct xattr_handler nop_posix_acl_access;
+extern const struct xattr_handler nop_posix_acl_default;
 
 #endif	/* _POSIX_ACL_XATTR_H */
diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index 6af72461397d..d591ef59aa98 100644
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -47,6 +47,22 @@ struct xattr_handler {
 		   size_t size, int flags);
 };
 
+/**
+ * xattr_handler_can_list - check whether xattr can be listed
+ * @handler: handler for this type of xattr
+ * @dentry: dentry whose inode xattr to list
+ *
+ * Determine whether the xattr associated with @dentry can be listed given
+ * @handler.
+ *
+ * Return: true if xattr can be listed, false if not.
+ */
+static inline bool xattr_handler_can_list(const struct xattr_handler *handler,
+					  struct dentry *dentry)
+{
+	return handler && (!handler->list || handler->list(dentry));
+}
+
 const char *xattr_full_name(const struct xattr_handler *, const char *);
 
 struct xattr {
@@ -78,7 +94,7 @@ int vfs_getxattr_alloc(struct mnt_idmap *idmap,
 		       struct dentry *dentry, const char *name,
 		       char **xattr_value, size_t size, gfp_t flags);
 
-int xattr_supported_namespace(struct inode *inode, const char *prefix);
+int xattr_supports_user_prefix(struct inode *inode);
 
 static inline const char *xattr_prefix(const struct xattr_handler *handler)
 {
@@ -109,5 +125,6 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 			  char *buffer, size_t size);
 void simple_xattr_add(struct simple_xattrs *xattrs,
 		      struct simple_xattr *new_xattr);
+int xattr_list_one(char **buffer, ssize_t *remaining_size, const char *name);
 
 #endif	/* _LINUX_XATTR_H */