btrfs: remove dead assignment in prepare_one_folio()

In prepare_one_folio(), ret is initialized to 0 at declaration,
and in an error path we assign ret = 0 before jumping to the
again label to retry the operation. However, ret is immediately
overwritten by ret = set_folio_extent_mapped(folio) after the
again label.

Both assignments are never observed by any code path,
therefore they can be safely removed.

Signed-off-by: Massimiliano Pellizzer <mpellizzer.dev@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: m-pellizzer

fs/btrfs/file.c

@@ -859,7 +859,7 @@ static noinline int prepare_one_folio(struct inode *inode, struct folio **folio_
 	fgf_t fgp_flags = (nowait ? FGP_WRITEBEGIN | FGP_NOWAIT : FGP_WRITEBEGIN) |
 			  fgf_set_order(write_bytes);
 	struct folio *folio;
-	int ret = 0;
+	int ret;
 
 again:
 	folio = __filemap_get_folio(inode->i_mapping, index, fgp_flags, mask);
@@ -876,10 +876,8 @@ static noinline int prepare_one_folio(struct inode *inode, struct folio **folio_
 	if (ret) {
 		/* The folio is already unlocked. */
 		folio_put(folio);
-		if (!nowait && ret == -EAGAIN) {
-			ret = 0;
+		if (!nowait && ret == -EAGAIN)
 			goto again;
-		}
 		return ret;
 	}
 	*folio_ret = folio;