diff options
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/block-group.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index 5fe37bc82f11..378d9103a207 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -2729,6 +2729,37 @@ next: btrfs_dec_delayed_refs_rsv_bg_inserts(fs_info); list_del_init(&block_group->bg_list); clear_bit(BLOCK_GROUP_FLAG_NEW, &block_group->runtime_flags); + + /* + * If the block group is still unused, add it to the list of + * unused block groups. The block group may have been created in + * order to satisfy a space reservation, in which case the + * extent allocation only happens later. But often we don't + * actually need to allocate space that we previously reserved, + * so the block group may become unused for a long time. For + * example for metadata we generally reserve space for a worst + * possible scenario, but then don't end up allocating all that + * space or none at all (due to no need to COW, extent buffers + * were already COWed in the current transaction and still + * unwritten, tree heights lower than the maximum possible + * height, etc). For data we generally reserve the axact amount + * of space we are going to allocate later, the exception is + * when using compression, as we must reserve space based on the + * uncompressed data size, because the compression is only done + * when writeback triggered and we don't know how much space we + * are actually going to need, so we reserve the uncompressed + * size because the data may be uncompressible in the worst case. + */ + if (ret == 0) { + bool used; + + spin_lock(&block_group->lock); + used = btrfs_is_block_group_used(block_group); + spin_unlock(&block_group->lock); + + if (!used) + btrfs_mark_bg_unused(block_group); + } } btrfs_trans_release_chunk_metadata(trans); } |