• Jeff Mahoney's avatar
    btrfs: replace pending/pinned chunks lists with io tree · 1c11b63e
    Jeff Mahoney authored
    The pending chunks list contains chunks that are allocated in the
    current transaction but haven't been created yet. The pinned chunks
    list contains chunks that are being released in the current transaction.
    Both describe chunks that are not reflected on disk as in use but are
    unavailable just the same.
    
    The pending chunks list is anchored by the transaction handle, which
    means that we need to hold a reference to a transaction when working
    with the list.
    
    The way we use them is by iterating over both lists to perform
    comparisons on the stripes they describe for each device. This is
    backwards and requires that we keep a transaction handle open while
    we're trimming.
    
    This patchset adds an extent_io_tree to btrfs_device that maintains
    the allocation state of the device.  Extents are set dirty when
    chunks are first allocated -- when the extent maps are added to the
    mapping tree. They're cleared when last removed -- when the extent
    maps are removed from the mapping tree. This matches the lifespan
    of the pending and pinned chunks list and allows us to do trims
    on unallocated space safely without pinning the transaction for what
    may be a lengthy operation. We can also use this io tree to mark
    which chunks have already been trimmed so we don't repeat the operation.
    Signed-off-by: default avatarJeff Mahoney <jeffm@suse.com>
    Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
    Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
    1c11b63e
volumes.c 206 KB