btrfs: don't use ctl->free_space for max_extent_size

max_extent_size is supposed to be the largest contiguous range for the
space info, and ctl->free_space is the total free space in the block
group.  We need to keep track of these separately and _only_ use the
max_free_space if we don't have a max_extent_size, as that means our
original request was too large to search any of the block groups for and
therefore wouldn't have a max_extent_size set.

CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 87d6666cd8e3..85d1ceb90273 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -7257,6 +7257,7 @@ static noinline int find_free_extent(struct btrfs_fs_info *fs_info,
         struct btrfs_block_group_cache *block_group = NULL;
         u64 search_start = 0;
         u64 max_extent_size = 0;
+        u64 max_free_space = 0;
         u64 empty_cluster = 0;
         struct btrfs_space_info *space_info;
         int loop = 0;
@@ -7552,8 +7553,8 @@ unclustered_alloc:
                         spin_lock(&ctl->tree_lock);
                         if (ctl->free_space <
                             num_bytes + empty_cluster + empty_size) {
-                                if (ctl->free_space > max_extent_size)
-                                        max_extent_size = ctl->free_space;
+                                max_free_space = max(max_free_space,
+                                                     ctl->free_space);
                                 spin_unlock(&ctl->tree_lock);
                                 goto loop;
                         }
@@ -7720,6 +7721,8 @@ loop:
         }
 out:
         if (ret == -ENOSPC) {
+                if (!max_extent_size)
+                        max_extent_size = max_free_space;
                 spin_lock(&space_info->lock);
                 space_info->max_extent_size = max_extent_size;
                 spin_unlock(&space_info->lock);