fsverity: optimize fsverity_cleanup_inode() on non-verity files

Make fsverity_cleanup_inode() an inline function that checks for
non-NULL ->i_verity_info, then (if needed) calls
__fsverity_cleanup_inode() to do the real work.  This reduces the
overhead on non-verity files.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20221214224304.145712-4-ebiggers@kernel.org

fs/verity/open.c

@@ -348,18 +348,12 @@ int __fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr)
 }
 EXPORT_SYMBOL_GPL(__fsverity_prepare_setattr);
 
-/**
- * fsverity_cleanup_inode() - free the inode's verity info, if present
- * @inode: an inode being evicted
- *
- * Filesystems must call this on inode eviction to free ->i_verity_info.
- */
-void fsverity_cleanup_inode(struct inode *inode)
+void __fsverity_cleanup_inode(struct inode *inode)
 {
 	fsverity_free_info(inode->i_verity_info);
 	inode->i_verity_info = NULL;
 }
-EXPORT_SYMBOL_GPL(fsverity_cleanup_inode);
+EXPORT_SYMBOL_GPL(__fsverity_cleanup_inode);
 
 int __init fsverity_init_info_cache(void)
 {

include/linux/fsverity.h

@@ -150,7 +150,19 @@ int fsverity_get_digest(struct inode *inode,
 
 int __fsverity_file_open(struct inode *inode, struct file *filp);
 int __fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr);
-void fsverity_cleanup_inode(struct inode *inode);
+void __fsverity_cleanup_inode(struct inode *inode);
+
+/**
+ * fsverity_cleanup_inode() - free the inode's verity info, if present
+ * @inode: an inode being evicted
+ *
+ * Filesystems must call this on inode eviction to free ->i_verity_info.
+ */
+static inline void fsverity_cleanup_inode(struct inode *inode)
+{
+	if (inode->i_verity_info)
+		__fsverity_cleanup_inode(inode);
+}
 
 /* read_metadata.c */