This exists in the kernel free-space-tree.c but not in progs. We need
it to generate the free space items for new block groups, which is
needed when we start creating the free space tree in make_btrfs().
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[HICCUP]
There is a bug report that mkfs.btrfs -R free-space-tree still makes
kernel to try to cleanup the v1 space cache:
# mkfs.btrfs -R free-space-tree -f /dev/test/scratch1
# mount /dev/test/scratch1 /mnt/btrfs
# dmesg | grep cleaning
BTRFS info (device dm-6): cleaning free space cache v1
[CAUSE]
By default, mkfs.btrfs will set super cache generation to (u64)-1, which
will inform kernel that the v1 space cache is invalid, needs to
regenerate it.
But for free space cache tree, kernel will set super cache generation to
0, to indicate v1 space cache is not in use.
This means, even we enabled free space tree with all the RO compatible
bits and new tree, as long as super cache generation is not 0, kernel
still consider the fs has some invalid v1 space cache, and will try to
remove them.
[FIX]
This is not a big deal, but to make the "-R free-space-tree" to really
work as kernel, we also need to set super cache generation to 0.
Reported-by: Chris Murphy <lists@colorremedies.com>
Link: https://lore.kernel.org/linux-btrfs/CAJCQCtSvgzyOnxtrqQZZirSycEHp+g0eDH5c+Kw9mW=PgxuXmw@mail.gmail.com/
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add a runtime feature (-R) flag for the free space tree. A filesystem
that is mkfs'd with -R free-space-tree then mounted with no options has
the same contents as one mkfs'd without the option, then mounted with
'-o space_cache=v2'.
The only tricky thing is in exactly how to call the tree creation code.
Using btrfs_create_free_space_tree as is did not quite work, because an
extra reference to the eb (root->commit_root) is leaked, which mkfs
complains about with a warning. I opted to follow how the uuid tree is
created by adding it to the dirty roots list for cleanup by
commit_tree_roots in commit_transaction. As a result,
btrfs_create_free_space_tree no longer exactly matches the version in
the kernel sources.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
This would sync the code between kernel and btrfs-progs, and save at
least 1 byte for each btrfs_block_group_cache.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
