[Libguestfs] [PATCH nbdkit 0/9] cache: Implement cache-max-size and method of reclaiming space from the cache.

[Richard W.M. Jones]

This patch series enhances the cache filter in a few ways, primarily
adding a "cache-on-read" feature (similar to qemu's copyonread); and
adding the ability to limit the cache size and the antecedent of that
which is having a method to reclaim cache blocks.

As the cache is stored as a sparse temporary file, reclaiming cache
blocks simply means punching holes in the temporary file.  The tricky
bit is working out where to punch the holes to avoid reclaiming
recently/frequently used blocks.

I believe the status of the patch series is:

[1/9] cache: Rename blk_writeback function.
[2/9] cache: Add cache-on-read mode.
[3/9] common/bitmap: Include <nbdkit-plugin.h>.
[4/9] cache: Split out the block/bitmap code into

 - All of the above patches are pretty uncontroversial and ready for
   review and upstreaming.

[5/9] cache: Allow this filter to serve requests in

 - Probably needs more testing, but should be OK too.

[6/9] common/bitmap: Add bitmap_next function and tests.
[7/9] common/bitmap: Add bitmap_clear function.
[8/9] cache: Implement LRU structure.
[9/9] cache: Implement cache-max-size and method of

 - Needs much better testing, and maybe even review of the design.

Rich.