Граф коммитов

10 Коммитов

Автор SHA1 Сообщение Дата
Vivek Goyal c2d0ad00d9 virtiofs: implement dax read/write operations
This patch implements basic DAX support. mmap() is not implemented
yet and will come in later patches. This patch looks into implemeting
read/write.

We make use of interval tree to keep track of per inode dax mappings.

Do not use dax for file extending writes, instead just send WRITE message
to daemon (like we do for direct I/O path). This will keep write and
i_size change atomic w.r.t crash.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Peng Tao <tao.peng@linux.alibaba.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2020-09-10 11:39:23 +02:00
Vivek Goyal 1dd539577c virtiofs: add a mount option to enable dax
Add a mount option to allow using dax with virtio_fs.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2020-09-10 11:39:22 +02:00
André Almeida c1b0c62715 fuse: update project homepage
As stated in https://sourceforge.net/projects/fuse/, "the FUSE project has
moved to https://github.com/libfuse/" in 22-Dec-2015. Update URLs to
reflect this.

Signed-off-by: André Almeida <andrealmeid@collabora.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2020-09-04 11:32:10 +02:00
Mauro Carvalho Chehab 72ef5e52b3 docs: fix broken references to text files
Several references got broken due to txt to ReST conversion.

Several of them can be automatically fixed with:

	scripts/documentation-file-ref-check --fix

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> # hwtracing/coresight/Kconfig
Reviewed-by: Paul E. McKenney <paulmck@kernel.org> # memory-barrier.txt
Acked-by: Alex Shi <alex.shi@linux.alibaba.com> # translations/zh_CN
Acked-by: Federico Vaga <federico.vaga@vaga.pv.it> # translations/it_IT
Acked-by: Marc Zyngier <maz@kernel.org> # kvm/arm64
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/6f919ddb83a33b5f2a63b6b5f0575737bb2b36aa.1586881715.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-20 15:35:59 -06:00
Krzysztof Kozlowski 8d66fcb748 fuse: fix Kconfig indentation
Adjust indentation from spaces to tab (+optional two spaces) as in
coding style with command like:
	$ sed -e 's/^        /\t/' -i */Kconfig

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2019-11-27 09:35:20 +01:00
Stefan Hajnoczi a62a8ef9d9 virtio-fs: add virtiofs filesystem
Add a basic file system module for virtio-fs.  This does not yet contain
shared data support between host and guest or metadata coherency speedups.
However it is already significantly faster than virtio-9p.

Design Overview
===============

With the goal of designing something with better performance and local file
system semantics, a bunch of ideas were proposed.

 - Use fuse protocol (instead of 9p) for communication between guest and
   host.  Guest kernel will be fuse client and a fuse server will run on
   host to serve the requests.

 - For data access inside guest, mmap portion of file in QEMU address space
   and guest accesses this memory using dax.  That way guest page cache is
   bypassed and there is only one copy of data (on host).  This will also
   enable mmap(MAP_SHARED) between guests.

 - For metadata coherency, there is a shared memory region which contains
   version number associated with metadata and any guest changing metadata
   updates version number and other guests refresh metadata on next access.
   This is yet to be implemented.

How virtio-fs differs from existing approaches
==============================================

The unique idea behind virtio-fs is to take advantage of the co-location of
the virtual machine and hypervisor to avoid communication (vmexits).

DAX allows file contents to be accessed without communication with the
hypervisor.  The shared memory region for metadata avoids communication in
the common case where metadata is unchanged.

By replacing expensive communication with cheaper shared memory accesses,
we expect to achieve better performance than approaches based on network
file system protocols.  In addition, this also makes it easier to achieve
local file system semantics (coherency).

These techniques are not applicable to network file system protocols since
the communications channel is bypassed by taking advantage of shared memory
on a local machine.  This is why we decided to build virtio-fs rather than
focus on 9P or NFS.

Caching Modes
=============

Like virtio-9p, different caching modes are supported which determine the
coherency level as well.  The “cache=FOO” and “writeback” options control
the level of coherence between the guest and host filesystems.

 - cache=none
   metadata, data and pathname lookup are not cached in guest.  They are
   always fetched from host and any changes are immediately pushed to host.

 - cache=always
   metadata, data and pathname lookup are cached in guest and never expire.

 - cache=auto
   metadata and pathname lookup cache expires after a configured amount of
   time (default is 1 second).  Data is cached while the file is open
   (close to open consistency).

 - writeback/no_writeback
   These options control the writeback strategy.  If writeback is disabled,
   then normal writes will immediately be synchronized with the host fs.
   If writeback is enabled, then writes may be cached in the guest until
   the file is closed or an fsync(2) performed.  This option has no effect
   on mmap-ed writes or writes going through the DAX mechanism.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2019-09-18 20:17:50 +02:00
Thomas Gleixner ec8f24b7fa treewide: Add SPDX license identifier - Makefile/Kconfig
Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 10:50:46 +02:00
Seth Forshee 60bcc88ad1 fuse: Add posix ACL support
Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with
userspace.  When it is set in the INIT response, ACL support will be
enabled.  ACL support also implies "default_permissions".

When ACL support is enabled, the kernel will cache and have responsibility
for enforcing ACLs.  ACL xattrs will be passed to userspace, which is
responsible for updating the ACLs in the filesystem, keeping the file mode
in sync, and inheritance of default ACLs when new filesystem nodes are
created.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-10-01 07:32:32 +02:00
Robert P. J. Day 807185eb3e fuse: Move CUSE Kconfig entry from fs/Kconfig into fs/fuse/Kconfig
Given that CUSE depends on FUSE, it only makes sense to move its
Kconfig entry into the FUSE Kconfig file.  Also, add a few grammatical
and semantic touchups.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2013-01-17 13:08:45 +01:00
Alexey Dobriyan 3ef7784e47 fs/Kconfig: move fuse out
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
2009-01-22 13:15:55 +03:00