Btrfs: use bytes_may_use for all ENOSPC reservations

We have been using bytes_reserved for metadata reservations, which is wrong
since we use that to keep track of outstanding reservations from the allocator.
This resulted in us doing a lot of silly things to make sure we don't allocate a
bunch of metadata chunks since we never had a real view of how much space was
actually in use by metadata.

This passes Arne's enospc test and xfstests as well as my own enospc tests.
Hopefully this will get us moving in the right direction.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

1 files changed, 23 insertions, 6 deletions

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 41ac927401d..79c16a68a2b 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -2472,9 +2472,19 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
                 spin_unlock(&ctl->tree_lock);
 
                 if (bytes >= minlen) {
-                        int update_ret;
-                        update_ret = btrfs_update_reserved_bytes(block_group,
-                                                                 bytes, 1, 1);
+                        struct btrfs_space_info *space_info;
+                        int update = 0;
+
+                        space_info = block_group->space_info;
+                        spin_lock(&space_info->lock);
+                        spin_lock(&block_group->lock);
+                        if (!block_group->ro) {
+                                block_group->reserved += bytes;
+                                space_info->bytes_reserved += bytes;
+                                update = 1;
+                        }
+                        spin_unlock(&block_group->lock);
+                        spin_unlock(&space_info->lock);
 
                         ret = btrfs_error_discard_extent(fs_info->extent_root,
                                                          start,
@@ -2482,9 +2492,16 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
                                                          &actually_trimmed);
 
                         btrfs_add_free_space(block_group, start, bytes);
-                        if (!update_ret)
-                                btrfs_update_reserved_bytes(block_group,
-                                                            bytes, 0, 1);
+                        if (update) {
+                                spin_lock(&space_info->lock);
+                                spin_lock(&block_group->lock);
+                                if (block_group->ro)
+                                        space_info->bytes_readonly += bytes;
+                                block_group->reserved -= bytes;
+                                space_info->bytes_reserved -= bytes;
+                                spin_unlock(&space_info->lock);
+                                spin_unlock(&block_group->lock);
+                        }
 
                         if (ret)
                                 break;