From: Josef Bacik <josef@toxicpanda.com>
Date: Thu, 11 Oct 2018 15:54:03 -0400
Subject: btrfs: reset max_extent_size properly
Git-commit: 21a94f7acf0f748599ea552af5d9ee7d7e41c72f
Patch-mainline: v4.20-rc1
References: bsc##1165949

If we use up our block group before allocating a new one we'll easily
get a max_extent_size that's set really really low, which will result in
a lot of fragmentation.  We need to make sure we're resetting the
max_extent_size when we add a new chunk or add new space.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/extent-tree.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4688,8 +4688,10 @@ again:
 		goto out;
 	if (ret)
 		space_info->full = 1;
-	else
+	else {
 		ret = 1;
+		space_info->max_extent_size = 0;
+	}
 
 	space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
 out:
@@ -6629,6 +6631,7 @@ static int btrfs_free_reserved_bytes(str
 		space_info->bytes_readonly += num_bytes;
 	cache->reserved -= num_bytes;
 	space_info->bytes_reserved -= num_bytes;
+	space_info->max_extent_size = 0;
 
 	if (delalloc)
 		cache->delalloc_bytes -= num_bytes;