xfs: improve the iclog space assert in xlog_write_iovec

We need enough space for the length we copy into the iclog, not just
some space, so tighten up the check a bit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 7c75166..8b8fdef 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1889,7 +1889,7 @@ xlog_write_iovec(
 	void			*buf,
 	uint32_t		buf_len)
 {
-	ASSERT(xlog_write_space_left(data) > 0);
+	ASSERT(xlog_write_space_left(data) >= buf_len);
 	ASSERT(data->log_offset % sizeof(int32_t) == 0);
 	ASSERT(buf_len % sizeof(int32_t) == 0);