This change enables vhost_user_fs to process multiple requests in
parallel by scheduling them into a ThreadPool (from the Futures
crate).
Parallelism on a single file is limited by the nature of the operation
executed on it. A recent commit replaced the Mutex that protects the
File within HandleData with a RwLock, to allow some operations (at
this moment, only "read" and "write") to proceed in parallel by
acquiring a read lock.
A more complex approach was also implemented [1], involving
instrumentation through vhost_user_backend to be able to serialize
completions, reducing the pressure on the vring RwLock. This strategy
improved the performance on some corner cases, while making it worse
on other, more common ones. This fact, in addition to it requiring
wider changes through the source code, prompted me to drop it in favor
of this one.
[1] https://github.com/slp/cloud-hypervisor/tree/vuf_async
Signed-off-by: Sergio Lopez <slp@redhat.com>
This change, combined with the compiler hint to inline get_used_event,
shortens the window between the memory read and the actual check by
calling get_used_event from needs_notification.
Without it, when putting enough pressure on the vring, it's possible
that a notification is wrongly omitted, causing the queue to stall.
Signed-off-by: Sergio Lopez <slp@redhat.com>
We weren't processing events arriving at the HIPRIO queue, which
implied ignoring FUSE_INTERRUPT, FUSE_FORGET, and FUSE_BATCH_FORGET
requests.
One effect of this issue was that file descriptors weren't closed on
the server, so it eventually hits RLIMIT_NOFILE. Additionally, the
guest OS may hang while attempting to unmount the filesystem.
Signed-off-by: Sergio Lopez <slp@redhat.com>
vhost_user_fs doesn't really support all vhost protocol features, just
MQ and SLAVE_REQ, so return that in protocol_features().
Signed-off-by: Sergio Lopez <slp@redhat.com>
Add helpers to Vring and VhostUserSlaveReqHandler for EVENT_IDX, so
consumers of this crate can make use of this feature.
Signed-off-by: Sergio Lopez <slp@redhat.com>
This adds the missing part of supporting virtiofs dax on the slave end,
that is, receiving a socket pair fd from the master end to set up a
communication channel for sending setupmapping & removemapping messages.
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Rather than handling the KILL_EVENT in the event handler itself use the
newly added support in VhostUserBackend for providing a kill event
framework.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Because the vhost_user_backend crate needs some changes to support
moving the process to a different mount namespace and perform a pivot
root, it is not possible to change '/' to the given shared directory.
This commit, as a temporary measure, let the code point at the given
shared directory.
The long term solution is to perform the mount namespace change and the
pivot root as this will provide greater security.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This patch implements a vhost-user-fs daemon based on Rust. It only
supports communicating through the virtqueues. The support for the
shared memory region associated with DAX will be added later.
It relies on all the code copied over from the crosvm repository, based
on the commit 961461350c0b6824e5f20655031bf6c6bf6b7c30.
It also relies on the vhost_user_backend crate, limiting the amount of
code needed to get this daemon up and running.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
