diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 1cb694c96500..25df5b03b591 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1885,7 +1885,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
 	ssize_t err;
 	loff_t pos;
-	size_t count = iov_iter_count(from);
+	size_t count;
 	loff_t oldsize;
 	int clean_page = 0;
 
@@ -1906,6 +1906,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	}
 
 	pos = iocb->ki_pos;
+	count = iov_iter_count(from);
 	if (iocb->ki_flags & IOCB_NOWAIT) {
 		/*
 		 * We will allocate space in case nodatacow is not set,