FAILED: patch "[PATCH] btrfs: Handle btrfs_set_extent_delalloc failure in fixup" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: Nikolay Borisov <[email protected]>
Date: Tue, 5 Dec 2017 09:29:19 +0200
Subject: [PATCH] btrfs: Handle btrfs_set_extent_delalloc failure in fixup
worker

This function was introduced by 247e743cbe6e ("Btrfs: Use async helpers to deal with pages that have been improperly dirtied") and it didn't do any error handling then. This function might very well fail in ENOMEM situation, yet it's not handled, this could lead to inconsistent state. So let's handle the failure by setting the mapping error bit.

index 034d7333b14d..9ad8c9321c8f 100644
@@ -2116,8 +2116,15 @@ static void btrfs_writepage_fixup_worker(struct btrfs_work *work)
 		goto out;
 	 }
 
-	btrfs_set_extent_delalloc(inode, page_start, page_end, 0, &cached_state,
-				  0);
+	ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0,
+					&cached_state, 0);
+	if (ret) {
+		mapping_set_error(page->mapping, ret);
+		end_extent_writepage(page, ret, page_start, page_end);
+		ClearPageChecked(page);
+		goto out;
+	}
+
 	ClearPageChecked(page);
 	set_page_dirty(page);
 	btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);