Scalable mapping structures for supporting log writes

A method, comprising:

• storing, in a log filesystem and by a system comprising at least one processor,
• a group of virtual chunk extents arranged in a chain data structure, wherein respective virtual chunk extents of the group of virtual chunk extents comprise respective pointers to respective next virtual chunk extents, and wherein respective virtual pointers of the respective virtual chunk extents identify locations within a data chunk, and
• a backpointer from a chunk descriptor that corresponds to the data chunk to a head virtual chunk extent of the group of virtual chunk extents;
• and
• based on performing an iteration of garbage collection of data in the data chunk, increasing, by the system, a number of virtual pointers of the virtual pointers while refraining from adding a new backpointer to the chunk descriptor, wherein respective virtual pointers of the virtual pointers point to respective compressed data that is produced from the performing of the iteration of the garbage collection of the data.

A non-transitory computer-readable medium comprising instructions that, in response to execution, cause a system comprising at least one processor to perform operations, comprising:

• in a log filesystem comprising a group of virtual chunk extents arranged in a chain data structure, wherein respective virtual pointers of the respective virtual chunk extents of the group identify respective locations within a chunk, and further comprising a backpointer from a chunk descriptor that corresponds to the chunk to a head virtual chunk extent of the group of virtual chunk extents, and based on performing an iteration of garbage collection of data in the chunk,
• increasing a number of virtual pointers of the virtual pointers, wherein respective virtual pointers of the virtual pointers point to respective compressed data that is produced from the performing of the iteration of the garbage collection of the data;
• and
• determining not to add a new backpointer to the chunk descriptor.