fs: add generic helper for filling statx attribute flags

The immutable and append-only properties on an inode are published on
the inode's i_flags and enforced by the VFS.

Create a helper to fill the corresponding STATX_ATTR_ flags in the kstat
structure from the inode's i_flags.

Only orange was converted to use this helper.
Other filesystems could use it in the future.

Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/orangefs/inode.c

@@ -882,12 +882,7 @@ int orangefs_getattr(struct user_namespace *mnt_userns, const struct path *path,
 		if (!(request_mask & STATX_SIZE))
 			stat->result_mask &= ~STATX_SIZE;
 
-		stat->attributes_mask = STATX_ATTR_IMMUTABLE |
-		    STATX_ATTR_APPEND;
-		if (inode->i_flags & S_IMMUTABLE)
-			stat->attributes |= STATX_ATTR_IMMUTABLE;
-		if (inode->i_flags & S_APPEND)
-			stat->attributes |= STATX_ATTR_APPEND;
+		generic_fill_statx_attr(inode, stat);
 	}
 	return ret;
 }

fs/stat.c

@@ -59,6 +59,24 @@ void generic_fillattr(struct user_namespace *mnt_userns, struct inode *inode,
 }
 EXPORT_SYMBOL(generic_fillattr);
 
+/**
+ * generic_fill_statx_attr - Fill in the statx attributes from the inode flags
+ * @inode:	Inode to use as the source
+ * @stat:	Where to fill in the attribute flags
+ *
+ * Fill in the STATX_ATTR_* flags in the kstat structure for properties of the
+ * inode that are published on i_flags and enforced by the VFS.
+ */
+void generic_fill_statx_attr(struct inode *inode, struct kstat *stat)
+{
+	if (inode->i_flags & S_IMMUTABLE)
+		stat->attributes |= STATX_ATTR_IMMUTABLE;
+	if (inode->i_flags & S_APPEND)
+		stat->attributes |= STATX_ATTR_APPEND;
+	stat->attributes_mask |= KSTAT_ATTR_VFS_FLAGS;
+}
+EXPORT_SYMBOL(generic_fill_statx_attr);
+
 /**
  * vfs_getattr_nosec - getattr without security checks
  * @path: file to get attributes from

include/linux/fs.h

@@ -3355,6 +3355,7 @@ extern int page_symlink(struct inode *inode, const char *symname, int len);
 extern const struct inode_operations page_symlink_inode_operations;
 extern void kfree_link(void *);
 void generic_fillattr(struct user_namespace *, struct inode *, struct kstat *);
+void generic_fill_statx_attr(struct inode *inode, struct kstat *stat);
 extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);
 extern int vfs_getattr(const struct path *, struct kstat *, u32, unsigned int);
 void __inode_add_bytes(struct inode *inode, loff_t bytes);

include/linux/stat.h

@@ -34,6 +34,10 @@ struct kstat {
 	 STATX_ATTR_ENCRYPTED |				\
 	 STATX_ATTR_VERITY				\
 	 )/* Attrs corresponding to FS_*_FL flags */
+#define KSTAT_ATTR_VFS_FLAGS				\
+	(STATX_ATTR_IMMUTABLE |				\
+	 STATX_ATTR_APPEND				\
+	 ) /* Attrs corresponding to S_* flags that are enforced by the VFS */
 	u64		ino;
 	dev_t		dev;
 	dev_t		rdev;