admin-guide/device-mapper/vdo-design.rst

50 the next phase of its operation requires access to the structures in the
54 each zone has an implicit lock on the structures it manages for all its
76 when the index is full, it should cull its oldest records to make space for
113 only a subset of the block name as its key, so it cannot guarantee that an
127 mapping each block name to the chapter containing its newest record. This
131 not been deleted from its chapter. Like the chapter index, the volume index
132 uses only a subset of the block name as its key and can not definitively
140 request looks up its name in the chapter index. This will indicate either
142 new, the request will look for its name in the indicated record page.
160 splitting its key space into many sub-lists, each starting at a fixed key
202 vdo. The vio is kept separate from its related bio because there are many
255 indicating whether or not the slab has ever been used, whether all of its
294 maintains its own cache of leaf pages. The size of this cache is
304 remapping, the journal records the logical address affected and its old and
368     the leaf page for its logical address. If any interior tree page is
400     data_vio can write its data somewhere even if deduplication and
446     data_vio will wait for the agent to complete its work and then share
447     its result.
451     step 8h and attempts to write its data directly. This can happen if two
454 8.  The hash lock agent attempts to deduplicate or compress its data with
457     a. The agent initializes and sends its embedded deduplication request
486     e. The agent attempts to compress its data. If the data does not
487        compress, the data_vio will continue to step 8h to write its data
506        before more compressible blocks need to use its bin. An evicted
507        data_vio will proceed to step 8h to write its data directly.
509     f. If the agent fills a packer bin, either because all 14 of its slots
511        using the allocated physical block from one of its data_vios. Step
514     g. Each data_vio sets the compressed block as its new physical address.
521        step 3. It will write its data to that allocated physical block.
524        lock, it will reacquire the implicit hash zone lock and share its
526        possible. Each data_vio will then proceed to step 9 to record its
548     recovery blocks up to the one containing its entry have been written
554     holding a lock on the affected physical slab, covered by its implicit
569     lock and releases its hash lock to the pool.
572     the struct pbn_lock it holds for its allocated block. If it had an
585 1 and 2 in the write path to obtain a data_vio and lock its logical