[PATCH v5 0/2] virtio-fs: add virtio file system device

[Stefan Hajnoczi <stefanha@redhat.com>]

v5:
 * Explain multiqueue semantics: no ordering, identical functionality on each queue, one FUSE session state shared between all queues
 * Explain how the FUSE session is started with a FUSE_INIT request
 * Consistently use "submit" vs "made available" and "complete" vs "used" terminology [Michael]
 * Explain endianness [Michael]
 * Clarify hiprio vs normal queue usage [Michael]
 * Move SHOULD, MUST, etc wording into normative sections [Michael]
 * Mention that FUSE_INIT negotiated state needs to be transferred during live migration [Michael]
 * State that the DAX window is mapped with writeback caching like RAM [Michael]
 * Mention DAX window mapping alignment constraints (they are communicated via the FUSE protocol) [Michael]
 * Explain that FUSE_SETUPMAPPING fails when device resources are exhausted and that splitting mappings consumes resources too [Michael]
 * Clarify access rules to DAX window - only touch memory that has a mapping establised
 * Document that DAX data persistence is achieved via FUSE_FSYNC

v4:
 * Clarify that there are no request ordering guarantees between requests in a
   single queue [vgoyal]
 * Add explanation of FUSE session endianness detection [dgilbert]

v3:
 * Remove notifications virtqueue, it's unimplemented and can be added when
   needed [Miklos]
 * Add Security Considerations and Live Migration Considerations sections
   [Michael]
v2:
 * Clean up core virtio file system device spec
 * Add DAX window

These patches add the virtio file system device, which is based on Linux FUSE
but includes the DAX window extension.  Similar to virtio-scsi, which
transports SCSI commands, virtio-fs transports FUSE requests and the protocol
documentation is not duplicated here.

The DAX window allows file contents to be accessed directly from shared memory.
This eliminates copying of data, reduces the number of vmexits, and reduces the
guest's memory footprint.  It also allows coherent mmap MAP_SHARED semantics
between guests on the same host.

Stefan Hajnoczi (2):
  content: add virtio file system device
  virtio-fs: add DAX window

 content.tex      |   1 +
 introduction.tex |   3 +
 virtio-fs.tex    | 259 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 263 insertions(+)
 create mode 100644 virtio-fs.tex

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2.21.0