Btrfs: account for space used by the super mirrors

As we get closer to proper -ENOSPC handling in btrfs, we need more accurate
space accounting for the space info's.  Currently we exclude the free space for
the super mirrors, but the space they take up isn't accounted for in any of the
counters.  This patch introduces bytes_super, which keeps track of the amount
of bytes used for a super mirror in the block group cache and space info.  This
makes sure that our free space caclucations will be completely accurate.

Signed-off-by: Josef Bacik <jbacik@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 2b15fb97d23f..80599b4e42bd 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -674,6 +674,7 @@ struct btrfs_space_info {
         u64 bytes_reserved;     /* total bytes the allocator has reserved for
                                    current allocations */
         u64 bytes_readonly;     /* total bytes that are read only */
+        u64 bytes_super;        /* total bytes reserved for the super blocks */
 
         /* delalloc accounting */
         u64 bytes_delalloc;     /* number of bytes reserved for allocation,
@@ -746,6 +747,7 @@ struct btrfs_block_group_cache {
         spinlock_t lock;
         u64 pinned;
         u64 reserved;
+        u64 bytes_super;
         u64 flags;
         u64 sectorsize;
         int extents_thresh;