locks: restore a warn for leaked locks on close

When locks.c moved to using file_lock_context, the check for any locks that
were not released was moved from the __fput() to destroy_inode() path in
commit 8634b51f ("locks: convert lease handling to file_lock_context").
This warning has been quite useful for catching bugs, particularly in NFS
where lock handling still sees some churn.

Let's bring back the warning for leaked locks on __fput, as this warning is
much more likely to be seen and reported by users.
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>

fs/locks.c

@@ -271,6 +271,22 @@ locks_check_ctx_lists(struct inode *inode)
 	}
 }
 
+static void
+locks_check_ctx_file_list(struct file *filp, struct list_head *list,
+				char *list_type)
+{
+	struct file_lock *fl;
+	struct inode *inode = locks_inode(filp);
+
+	list_for_each_entry(fl, list, fl_list)
+		if (fl->fl_file == filp)
+			pr_warn("Leaked %s lock on dev=0x%x:0x%x ino=0x%lx "
+				" fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n",
+				list_type, MAJOR(inode->i_sb->s_dev),
+				MINOR(inode->i_sb->s_dev), inode->i_ino,
+				fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid);
+}
+
 void
 locks_free_lock_context(struct inode *inode)
 {
@@ -2549,6 +2565,12 @@ void locks_remove_file(struct file *filp)
 
 	/* remove any leases */
 	locks_remove_lease(filp, ctx);
+
+	spin_lock(&ctx->flc_lock);
+	locks_check_ctx_file_list(filp, &ctx->flc_posix, "POSIX");
+	locks_check_ctx_file_list(filp, &ctx->flc_flock, "FLOCK");
+	locks_check_ctx_file_list(filp, &ctx->flc_lease, "LEASE");
+	spin_unlock(&ctx->flc_lock);
 }
 
 /**