From c4bb667eaf520f21b3a3db0489682becc9c49bcc Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Fri, 2 Aug 2019 18:15:19 +0100 Subject: [PATCH 1/3] fuse: reserve values for mapping protocol SETUPMAPPING is a command for use with 'virtiofsd', a fuse-over-virtio implementation; it may find use in other fuse impelementations as well in which the kernel does not have access to the address space of the daemon directly. A SETUPMAPPING operation causes a section of a file to be mapped into a memory window visible to the kernel. The offsets in the file and the window are defined by the kernel performing the operation. The daemon may reject the request, for reasons including permissions and limited resources. When a request perfectly overlaps a previous mapping, the previous mapping is replaced. When a mapping partially overlaps a previous mapping, the previous mapping is split into one or two smaller mappings. REMOVEMAPPING is the complement to SETUPMAPPING; it unmaps a range of mapped files from the window visible to the kernel. The map_alignment field communicates the alignment constraint for FUSE_SETUPMAPPING/FUSE_REMOVEMAPPING and allows the daemon to constrain the addresses and file offsets chosen by the kernel. Signed-off-by: Dr. David Alan Gilbert Signed-off-by: Vivek Goyal Signed-off-by: Stefan Hajnoczi Signed-off-by: Miklos Szeredi --- include/uapi/linux/fuse.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index df2e12fb3381..802b0377a49e 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -133,6 +133,8 @@ * * 7.31 * - add FUSE_WRITE_KILL_PRIV flag + * - add FUSE_SETUPMAPPING and FUSE_REMOVEMAPPING + * - add map_alignment to fuse_init_out, add FUSE_MAP_ALIGNMENT flag */ #ifndef _LINUX_FUSE_H @@ -274,6 +276,7 @@ struct fuse_file_lock { * FUSE_CACHE_SYMLINKS: cache READLINK responses * FUSE_NO_OPENDIR_SUPPORT: kernel supports zero-message opendir * FUSE_EXPLICIT_INVAL_DATA: only invalidate cached pages on explicit request + * FUSE_MAP_ALIGNMENT: map_alignment field is valid */ #define FUSE_ASYNC_READ (1 << 0) #define FUSE_POSIX_LOCKS (1 << 1) @@ -301,6 +304,7 @@ struct fuse_file_lock { #define FUSE_CACHE_SYMLINKS (1 << 23) #define FUSE_NO_OPENDIR_SUPPORT (1 << 24) #define FUSE_EXPLICIT_INVAL_DATA (1 << 25) +#define FUSE_MAP_ALIGNMENT (1 << 26) /** * CUSE INIT request/reply flags @@ -422,6 +426,8 @@ enum fuse_opcode { FUSE_RENAME2 = 45, FUSE_LSEEK = 46, FUSE_COPY_FILE_RANGE = 47, + FUSE_SETUPMAPPING = 48, + FUSE_REMOVEMAPPING = 49, /* CUSE specific operations */ CUSE_INIT = 4096, @@ -656,7 +662,7 @@ struct fuse_init_out { uint32_t max_write; uint32_t time_gran; uint16_t max_pages; - uint16_t padding; + uint16_t map_alignment; uint32_t unused[8]; }; From 2d1d25d0a224dcd2021004d52342fc1727ccd85f Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Thu, 29 Aug 2019 14:41:04 +0100 Subject: [PATCH 2/3] virtio-fs: add Documentation/filesystems/virtiofs.rst Add information about the new "virtiofs" file system. Signed-off-by: Stefan Hajnoczi Signed-off-by: Miklos Szeredi --- Documentation/filesystems/index.rst | 10 +++++ Documentation/filesystems/virtiofs.rst | 60 ++++++++++++++++++++++++++ MAINTAINERS | 12 ++++++ 3 files changed, 82 insertions(+) create mode 100644 Documentation/filesystems/virtiofs.rst diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst index 2de2fe2ab078..56e94bfc580f 100644 --- a/Documentation/filesystems/index.rst +++ b/Documentation/filesystems/index.rst @@ -32,3 +32,13 @@ filesystem implementations. journalling fscrypt + +Filesystems +=========== + +Documentation for filesystem implementations. + +.. toctree:: + :maxdepth: 2 + + virtiofs diff --git a/Documentation/filesystems/virtiofs.rst b/Documentation/filesystems/virtiofs.rst new file mode 100644 index 000000000000..4f338e3cb3f7 --- /dev/null +++ b/Documentation/filesystems/virtiofs.rst @@ -0,0 +1,60 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=================================================== +virtiofs: virtio-fs host<->guest shared file system +=================================================== + +- Copyright (C) 2019 Red Hat, Inc. + +Introduction +============ +The virtiofs file system for Linux implements a driver for the paravirtualized +VIRTIO "virtio-fs" device for guest<->host file system sharing. It allows a +guest to mount a directory that has been exported on the host. + +Guests often require access to files residing on the host or remote systems. +Use cases include making files available to new guests during installation, +booting from a root file system located on the host, persistent storage for +stateless or ephemeral guests, and sharing a directory between guests. + +Although it is possible to use existing network file systems for some of these +tasks, they require configuration steps that are hard to automate and they +expose the storage network to the guest. The virtio-fs device was designed to +solve these problems by providing file system access without networking. + +Furthermore the virtio-fs device takes advantage of the co-location of the +guest and host to increase performance and provide semantics that are not +possible with network file systems. + +Usage +===== +Mount file system with tag ``myfs`` on ``/mnt``: + +.. code-block:: sh + + guest# mount -t virtiofs myfs /mnt + +Please see https://virtio-fs.gitlab.io/ for details on how to configure QEMU +and the virtiofsd daemon. + +Internals +========= +Since the virtio-fs device uses the FUSE protocol for file system requests, the +virtiofs file system for Linux is integrated closely with the FUSE file system +client. The guest acts as the FUSE client while the host acts as the FUSE +server. The /dev/fuse interface between the kernel and userspace is replaced +with the virtio-fs device interface. + +FUSE requests are placed into a virtqueue and processed by the host. The +response portion of the buffer is filled in by the host and the guest handles +the request completion. + +Mapping /dev/fuse to virtqueues requires solving differences in semantics +between /dev/fuse and virtqueues. Each time the /dev/fuse device is read, the +FUSE client may choose which request to transfer, making it possible to +prioritize certain requests over others. Virtqueues have queue semantics and +it is not possible to change the order of requests that have been enqueued. +This is especially important if the virtqueue becomes full since it is then +impossible to add high priority requests. In order to address this difference, +the virtio-fs device uses a "hiprio" virtqueue specifically for requests that +have priority over normal requests. diff --git a/MAINTAINERS b/MAINTAINERS index 9cbcf167bdd0..953e8c60d1c0 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -17117,6 +17117,18 @@ S: Supported F: drivers/s390/virtio/ F: arch/s390/include/uapi/asm/virtio-ccw.h +VIRTIO FILE SYSTEM +M: Vivek Goyal +M: Stefan Hajnoczi +M: Miklos Szeredi +L: virtualization@lists.linux-foundation.org +L: linux-fsdevel@vger.kernel.org +W: https://virtio-fs.gitlab.io/ +S: Supported +F: fs/fuse/virtio_fs.c +F: include/uapi/linux/virtio_fs.h +F: Documentation/filesystems/virtiofs.rst + VIRTIO GPU DRIVER M: David Airlie M: Gerd Hoffmann From a62a8ef9d97da23762a588592c8b8eb50a8deb6a Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 12 Jun 2018 09:41:17 +0100 Subject: [PATCH 3/3] virtio-fs: add virtiofs filesystem MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Vivek Goyal Acked-by: Michael S. Tsirkin Signed-off-by: Miklos Szeredi --- fs/fuse/Kconfig | 11 + fs/fuse/Makefile | 1 + fs/fuse/fuse_i.h | 9 + fs/fuse/inode.c | 4 + fs/fuse/virtio_fs.c | 1195 +++++++++++++++++++++++++++++++ include/uapi/linux/virtio_fs.h | 19 + include/uapi/linux/virtio_ids.h | 1 + 7 files changed, 1240 insertions(+) create mode 100644 fs/fuse/virtio_fs.c create mode 100644 include/uapi/linux/virtio_fs.h diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig index 24fc5a5c1b97..0635cba19971 100644 --- a/fs/fuse/Kconfig +++ b/fs/fuse/Kconfig @@ -27,3 +27,14 @@ config CUSE If you want to develop or use a userspace character device based on CUSE, answer Y or M. + +config VIRTIO_FS + tristate "Virtio Filesystem" + depends on FUSE_FS + select VIRTIO + help + The Virtio Filesystem allows guests to mount file systems from the + host. + + If you want to share files between guests or with the host, answer Y + or M. diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile index 9485019c2a14..6419a2b3510d 100644 --- a/fs/fuse/Makefile +++ b/fs/fuse/Makefile @@ -5,5 +5,6 @@ obj-$(CONFIG_FUSE_FS) += fuse.o obj-$(CONFIG_CUSE) += cuse.o +obj-$(CONFIG_VIRTIO_FS) += virtio_fs.o fuse-objs := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index fc89cb40e874..956aeaf961ae 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -353,6 +353,10 @@ struct fuse_req { /** Used to wake up the task waiting for completion of request*/ wait_queue_head_t waitq; +#if IS_ENABLED(CONFIG_VIRTIO_FS) + /** virtio-fs's physically contiguous buffer for in and out args */ + void *argbuf; +#endif }; struct fuse_iqueue; @@ -383,6 +387,11 @@ struct fuse_iqueue_ops { */ void (*wake_pending_and_unlock)(struct fuse_iqueue *fiq) __releases(fiq->lock); + + /** + * Clean up when fuse_iqueue is destroyed + */ + void (*release)(struct fuse_iqueue *fiq); }; /** /dev/fuse input queue operations */ diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 10d193b24fb8..3d598a5bb5b5 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -630,6 +630,10 @@ EXPORT_SYMBOL_GPL(fuse_conn_init); void fuse_conn_put(struct fuse_conn *fc) { if (refcount_dec_and_test(&fc->count)) { + struct fuse_iqueue *fiq = &fc->iq; + + if (fiq->ops->release) + fiq->ops->release(fiq); put_pid_ns(fc->pid_ns); put_user_ns(fc->user_ns); fc->release(fc); diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c new file mode 100644 index 000000000000..6af3f131e468 --- /dev/null +++ b/fs/fuse/virtio_fs.c @@ -0,0 +1,1195 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * virtio-fs: Virtio Filesystem + * Copyright (C) 2018 Red Hat, Inc. + */ + +#include +#include +#include +#include +#include +#include +#include +#include "fuse_i.h" + +/* List of virtio-fs device instances and a lock for the list. Also provides + * mutual exclusion in device removal and mounting path + */ +static DEFINE_MUTEX(virtio_fs_mutex); +static LIST_HEAD(virtio_fs_instances); + +enum { + VQ_HIPRIO, + VQ_REQUEST +}; + +/* Per-virtqueue state */ +struct virtio_fs_vq { + spinlock_t lock; + struct virtqueue *vq; /* protected by ->lock */ + struct work_struct done_work; + struct list_head queued_reqs; + struct delayed_work dispatch_work; + struct fuse_dev *fud; + bool connected; + long in_flight; + char name[24]; +} ____cacheline_aligned_in_smp; + +/* A virtio-fs device instance */ +struct virtio_fs { + struct kref refcount; + struct list_head list; /* on virtio_fs_instances */ + char *tag; + struct virtio_fs_vq *vqs; + unsigned int nvqs; /* number of virtqueues */ + unsigned int num_request_queues; /* number of request queues */ +}; + +struct virtio_fs_forget { + struct fuse_in_header ih; + struct fuse_forget_in arg; + /* This request can be temporarily queued on virt queue */ + struct list_head list; +}; + +static inline struct virtio_fs_vq *vq_to_fsvq(struct virtqueue *vq) +{ + struct virtio_fs *fs = vq->vdev->priv; + + return &fs->vqs[vq->index]; +} + +static inline struct fuse_pqueue *vq_to_fpq(struct virtqueue *vq) +{ + return &vq_to_fsvq(vq)->fud->pq; +} + +static void release_virtio_fs_obj(struct kref *ref) +{ + struct virtio_fs *vfs = container_of(ref, struct virtio_fs, refcount); + + kfree(vfs->vqs); + kfree(vfs); +} + +/* Make sure virtiofs_mutex is held */ +static void virtio_fs_put(struct virtio_fs *fs) +{ + kref_put(&fs->refcount, release_virtio_fs_obj); +} + +static void virtio_fs_fiq_release(struct fuse_iqueue *fiq) +{ + struct virtio_fs *vfs = fiq->priv; + + mutex_lock(&virtio_fs_mutex); + virtio_fs_put(vfs); + mutex_unlock(&virtio_fs_mutex); +} + +static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq) +{ + WARN_ON(fsvq->in_flight < 0); + + /* Wait for in flight requests to finish.*/ + while (1) { + spin_lock(&fsvq->lock); + if (!fsvq->in_flight) { + spin_unlock(&fsvq->lock); + break; + } + spin_unlock(&fsvq->lock); + /* TODO use completion instead of timeout */ + usleep_range(1000, 2000); + } + + flush_work(&fsvq->done_work); + flush_delayed_work(&fsvq->dispatch_work); +} + +static inline void drain_hiprio_queued_reqs(struct virtio_fs_vq *fsvq) +{ + struct virtio_fs_forget *forget; + + spin_lock(&fsvq->lock); + while (1) { + forget = list_first_entry_or_null(&fsvq->queued_reqs, + struct virtio_fs_forget, list); + if (!forget) + break; + list_del(&forget->list); + kfree(forget); + } + spin_unlock(&fsvq->lock); +} + +static void virtio_fs_drain_all_queues(struct virtio_fs *fs) +{ + struct virtio_fs_vq *fsvq; + int i; + + for (i = 0; i < fs->nvqs; i++) { + fsvq = &fs->vqs[i]; + if (i == VQ_HIPRIO) + drain_hiprio_queued_reqs(fsvq); + + virtio_fs_drain_queue(fsvq); + } +} + +static void virtio_fs_start_all_queues(struct virtio_fs *fs) +{ + struct virtio_fs_vq *fsvq; + int i; + + for (i = 0; i < fs->nvqs; i++) { + fsvq = &fs->vqs[i]; + spin_lock(&fsvq->lock); + fsvq->connected = true; + spin_unlock(&fsvq->lock); + } +} + +/* Add a new instance to the list or return -EEXIST if tag name exists*/ +static int virtio_fs_add_instance(struct virtio_fs *fs) +{ + struct virtio_fs *fs2; + bool duplicate = false; + + mutex_lock(&virtio_fs_mutex); + + list_for_each_entry(fs2, &virtio_fs_instances, list) { + if (strcmp(fs->tag, fs2->tag) == 0) + duplicate = true; + } + + if (!duplicate) + list_add_tail(&fs->list, &virtio_fs_instances); + + mutex_unlock(&virtio_fs_mutex); + + if (duplicate) + return -EEXIST; + return 0; +} + +/* Return the virtio_fs with a given tag, or NULL */ +static struct virtio_fs *virtio_fs_find_instance(const char *tag) +{ + struct virtio_fs *fs; + + mutex_lock(&virtio_fs_mutex); + + list_for_each_entry(fs, &virtio_fs_instances, list) { + if (strcmp(fs->tag, tag) == 0) { + kref_get(&fs->refcount); + goto found; + } + } + + fs = NULL; /* not found */ + +found: + mutex_unlock(&virtio_fs_mutex); + + return fs; +} + +static void virtio_fs_free_devs(struct virtio_fs *fs) +{ + unsigned int i; + + for (i = 0; i < fs->nvqs; i++) { + struct virtio_fs_vq *fsvq = &fs->vqs[i]; + + if (!fsvq->fud) + continue; + + fuse_dev_free(fsvq->fud); + fsvq->fud = NULL; + } +} + +/* Read filesystem name from virtio config into fs->tag (must kfree()). */ +static int virtio_fs_read_tag(struct virtio_device *vdev, struct virtio_fs *fs) +{ + char tag_buf[sizeof_field(struct virtio_fs_config, tag)]; + char *end; + size_t len; + + virtio_cread_bytes(vdev, offsetof(struct virtio_fs_config, tag), + &tag_buf, sizeof(tag_buf)); + end = memchr(tag_buf, '\0', sizeof(tag_buf)); + if (end == tag_buf) + return -EINVAL; /* empty tag */ + if (!end) + end = &tag_buf[sizeof(tag_buf)]; + + len = end - tag_buf; + fs->tag = devm_kmalloc(&vdev->dev, len + 1, GFP_KERNEL); + if (!fs->tag) + return -ENOMEM; + memcpy(fs->tag, tag_buf, len); + fs->tag[len] = '\0'; + return 0; +} + +/* Work function for hiprio completion */ +static void virtio_fs_hiprio_done_work(struct work_struct *work) +{ + struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq, + done_work); + struct virtqueue *vq = fsvq->vq; + + /* Free completed FUSE_FORGET requests */ + spin_lock(&fsvq->lock); + do { + unsigned int len; + void *req; + + virtqueue_disable_cb(vq); + + while ((req = virtqueue_get_buf(vq, &len)) != NULL) { + kfree(req); + fsvq->in_flight--; + } + } while (!virtqueue_enable_cb(vq) && likely(!virtqueue_is_broken(vq))); + spin_unlock(&fsvq->lock); +} + +static void virtio_fs_dummy_dispatch_work(struct work_struct *work) +{ +} + +static void virtio_fs_hiprio_dispatch_work(struct work_struct *work) +{ + struct virtio_fs_forget *forget; + struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq, + dispatch_work.work); + struct virtqueue *vq = fsvq->vq; + struct scatterlist sg; + struct scatterlist *sgs[] = {&sg}; + bool notify; + int ret; + + pr_debug("virtio-fs: worker %s called.\n", __func__); + while (1) { + spin_lock(&fsvq->lock); + forget = list_first_entry_or_null(&fsvq->queued_reqs, + struct virtio_fs_forget, list); + if (!forget) { + spin_unlock(&fsvq->lock); + return; + } + + list_del(&forget->list); + if (!fsvq->connected) { + spin_unlock(&fsvq->lock); + kfree(forget); + continue; + } + + sg_init_one(&sg, forget, sizeof(*forget)); + + /* Enqueue the request */ + dev_dbg(&vq->vdev->dev, "%s\n", __func__); + ret = virtqueue_add_sgs(vq, sgs, 1, 0, forget, GFP_ATOMIC); + if (ret < 0) { + if (ret == -ENOMEM || ret == -ENOSPC) { + pr_debug("virtio-fs: Could not queue FORGET: err=%d. Will try later\n", + ret); + list_add_tail(&forget->list, + &fsvq->queued_reqs); + schedule_delayed_work(&fsvq->dispatch_work, + msecs_to_jiffies(1)); + } else { + pr_debug("virtio-fs: Could not queue FORGET: err=%d. Dropping it.\n", + ret); + kfree(forget); + } + spin_unlock(&fsvq->lock); + return; + } + + fsvq->in_flight++; + notify = virtqueue_kick_prepare(vq); + spin_unlock(&fsvq->lock); + + if (notify) + virtqueue_notify(vq); + pr_debug("virtio-fs: worker %s dispatched one forget request.\n", + __func__); + } +} + +/* Allocate and copy args into req->argbuf */ +static int copy_args_to_argbuf(struct fuse_req *req) +{ + struct fuse_args *args = req->args; + unsigned int offset = 0; + unsigned int num_in; + unsigned int num_out; + unsigned int len; + unsigned int i; + + num_in = args->in_numargs - args->in_pages; + num_out = args->out_numargs - args->out_pages; + len = fuse_len_args(num_in, (struct fuse_arg *) args->in_args) + + fuse_len_args(num_out, args->out_args); + + req->argbuf = kmalloc(len, GFP_ATOMIC); + if (!req->argbuf) + return -ENOMEM; + + for (i = 0; i < num_in; i++) { + memcpy(req->argbuf + offset, + args->in_args[i].value, + args->in_args[i].size); + offset += args->in_args[i].size; + } + + return 0; +} + +/* Copy args out of and free req->argbuf */ +static void copy_args_from_argbuf(struct fuse_args *args, struct fuse_req *req) +{ + unsigned int remaining; + unsigned int offset; + unsigned int num_in; + unsigned int num_out; + unsigned int i; + + remaining = req->out.h.len - sizeof(req->out.h); + num_in = args->in_numargs - args->in_pages; + num_out = args->out_numargs - args->out_pages; + offset = fuse_len_args(num_in, (struct fuse_arg *)args->in_args); + + for (i = 0; i < num_out; i++) { + unsigned int argsize = args->out_args[i].size; + + if (args->out_argvar && + i == args->out_numargs - 1 && + argsize > remaining) { + argsize = remaining; + } + + memcpy(args->out_args[i].value, req->argbuf + offset, argsize); + offset += argsize; + + if (i != args->out_numargs - 1) + remaining -= argsize; + } + + /* Store the actual size of the variable-length arg */ + if (args->out_argvar) + args->out_args[args->out_numargs - 1].size = remaining; + + kfree(req->argbuf); + req->argbuf = NULL; +} + +/* Work function for request completion */ +static void virtio_fs_requests_done_work(struct work_struct *work) +{ + struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq, + done_work); + struct fuse_pqueue *fpq = &fsvq->fud->pq; + struct fuse_conn *fc = fsvq->fud->fc; + struct virtqueue *vq = fsvq->vq; + struct fuse_req *req; + struct fuse_args_pages *ap; + struct fuse_req *next; + struct fuse_args *args; + unsigned int len, i, thislen; + struct page *page; + LIST_HEAD(reqs); + + /* Collect completed requests off the virtqueue */ + spin_lock(&fsvq->lock); + do { + virtqueue_disable_cb(vq); + + while ((req = virtqueue_get_buf(vq, &len)) != NULL) { + spin_lock(&fpq->lock); + list_move_tail(&req->list, &reqs); + spin_unlock(&fpq->lock); + } + } while (!virtqueue_enable_cb(vq) && likely(!virtqueue_is_broken(vq))); + spin_unlock(&fsvq->lock); + + /* End requests */ + list_for_each_entry_safe(req, next, &reqs, list) { + /* + * TODO verify that server properly follows FUSE protocol + * (oh.uniq, oh.len) + */ + args = req->args; + copy_args_from_argbuf(args, req); + + if (args->out_pages && args->page_zeroing) { + len = args->out_args[args->out_numargs - 1].size; + ap = container_of(args, typeof(*ap), args); + for (i = 0; i < ap->num_pages; i++) { + thislen = ap->descs[i].length; + if (len < thislen) { + WARN_ON(ap->descs[i].offset); + page = ap->pages[i]; + zero_user_segment(page, len, thislen); + len = 0; + } else { + len -= thislen; + } + } + } + + spin_lock(&fpq->lock); + clear_bit(FR_SENT, &req->flags); + list_del_init(&req->list); + spin_unlock(&fpq->lock); + + fuse_request_end(fc, req); + spin_lock(&fsvq->lock); + fsvq->in_flight--; + spin_unlock(&fsvq->lock); + } +} + +/* Virtqueue interrupt handler */ +static void virtio_fs_vq_done(struct virtqueue *vq) +{ + struct virtio_fs_vq *fsvq = vq_to_fsvq(vq); + + dev_dbg(&vq->vdev->dev, "%s %s\n", __func__, fsvq->name); + + schedule_work(&fsvq->done_work); +} + +/* Initialize virtqueues */ +static int virtio_fs_setup_vqs(struct virtio_device *vdev, + struct virtio_fs *fs) +{ + struct virtqueue **vqs; + vq_callback_t **callbacks; + const char **names; + unsigned int i; + int ret = 0; + + virtio_cread(vdev, struct virtio_fs_config, num_request_queues, + &fs->num_request_queues); + if (fs->num_request_queues == 0) + return -EINVAL; + + fs->nvqs = 1 + fs->num_request_queues; + fs->vqs = kcalloc(fs->nvqs, sizeof(fs->vqs[VQ_HIPRIO]), GFP_KERNEL); + if (!fs->vqs) + return -ENOMEM; + + vqs = kmalloc_array(fs->nvqs, sizeof(vqs[VQ_HIPRIO]), GFP_KERNEL); + callbacks = kmalloc_array(fs->nvqs, sizeof(callbacks[VQ_HIPRIO]), + GFP_KERNEL); + names = kmalloc_array(fs->nvqs, sizeof(names[VQ_HIPRIO]), GFP_KERNEL); + if (!vqs || !callbacks || !names) { + ret = -ENOMEM; + goto out; + } + + callbacks[VQ_HIPRIO] = virtio_fs_vq_done; + snprintf(fs->vqs[VQ_HIPRIO].name, sizeof(fs->vqs[VQ_HIPRIO].name), + "hiprio"); + names[VQ_HIPRIO] = fs->vqs[VQ_HIPRIO].name; + INIT_WORK(&fs->vqs[VQ_HIPRIO].done_work, virtio_fs_hiprio_done_work); + INIT_LIST_HEAD(&fs->vqs[VQ_HIPRIO].queued_reqs); + INIT_DELAYED_WORK(&fs->vqs[VQ_HIPRIO].dispatch_work, + virtio_fs_hiprio_dispatch_work); + spin_lock_init(&fs->vqs[VQ_HIPRIO].lock); + + /* Initialize the requests virtqueues */ + for (i = VQ_REQUEST; i < fs->nvqs; i++) { + spin_lock_init(&fs->vqs[i].lock); + INIT_WORK(&fs->vqs[i].done_work, virtio_fs_requests_done_work); + INIT_DELAYED_WORK(&fs->vqs[i].dispatch_work, + virtio_fs_dummy_dispatch_work); + INIT_LIST_HEAD(&fs->vqs[i].queued_reqs); + snprintf(fs->vqs[i].name, sizeof(fs->vqs[i].name), + "requests.%u", i - VQ_REQUEST); + callbacks[i] = virtio_fs_vq_done; + names[i] = fs->vqs[i].name; + } + + ret = virtio_find_vqs(vdev, fs->nvqs, vqs, callbacks, names, NULL); + if (ret < 0) + goto out; + + for (i = 0; i < fs->nvqs; i++) + fs->vqs[i].vq = vqs[i]; + + virtio_fs_start_all_queues(fs); +out: + kfree(names); + kfree(callbacks); + kfree(vqs); + if (ret) + kfree(fs->vqs); + return ret; +} + +/* Free virtqueues (device must already be reset) */ +static void virtio_fs_cleanup_vqs(struct virtio_device *vdev, + struct virtio_fs *fs) +{ + vdev->config->del_vqs(vdev); +} + +static int virtio_fs_probe(struct virtio_device *vdev) +{ + struct virtio_fs *fs; + int ret; + + fs = kzalloc(sizeof(*fs), GFP_KERNEL); + if (!fs) + return -ENOMEM; + kref_init(&fs->refcount); + vdev->priv = fs; + + ret = virtio_fs_read_tag(vdev, fs); + if (ret < 0) + goto out; + + ret = virtio_fs_setup_vqs(vdev, fs); + if (ret < 0) + goto out; + + /* TODO vq affinity */ + + /* Bring the device online in case the filesystem is mounted and + * requests need to be sent before we return. + */ + virtio_device_ready(vdev); + + ret = virtio_fs_add_instance(fs); + if (ret < 0) + goto out_vqs; + + return 0; + +out_vqs: + vdev->config->reset(vdev); + virtio_fs_cleanup_vqs(vdev, fs); + +out: + vdev->priv = NULL; + kfree(fs); + return ret; +} + +static void virtio_fs_stop_all_queues(struct virtio_fs *fs) +{ + struct virtio_fs_vq *fsvq; + int i; + + for (i = 0; i < fs->nvqs; i++) { + fsvq = &fs->vqs[i]; + spin_lock(&fsvq->lock); + fsvq->connected = false; + spin_unlock(&fsvq->lock); + } +} + +static void virtio_fs_remove(struct virtio_device *vdev) +{ + struct virtio_fs *fs = vdev->priv; + + mutex_lock(&virtio_fs_mutex); + /* This device is going away. No one should get new reference */ + list_del_init(&fs->list); + virtio_fs_stop_all_queues(fs); + virtio_fs_drain_all_queues(fs); + vdev->config->reset(vdev); + virtio_fs_cleanup_vqs(vdev, fs); + + vdev->priv = NULL; + /* Put device reference on virtio_fs object */ + virtio_fs_put(fs); + mutex_unlock(&virtio_fs_mutex); +} + +#ifdef CONFIG_PM_SLEEP +static int virtio_fs_freeze(struct virtio_device *vdev) +{ + /* TODO need to save state here */ + pr_warn("virtio-fs: suspend/resume not yet supported\n"); + return -EOPNOTSUPP; +} + +static int virtio_fs_restore(struct virtio_device *vdev) +{ + /* TODO need to restore state here */ + return 0; +} +#endif /* CONFIG_PM_SLEEP */ + +const static struct virtio_device_id id_table[] = { + { VIRTIO_ID_FS, VIRTIO_DEV_ANY_ID }, + {}, +}; + +const static unsigned int feature_table[] = {}; + +static struct virtio_driver virtio_fs_driver = { + .driver.name = KBUILD_MODNAME, + .driver.owner = THIS_MODULE, + .id_table = id_table, + .feature_table = feature_table, + .feature_table_size = ARRAY_SIZE(feature_table), + .probe = virtio_fs_probe, + .remove = virtio_fs_remove, +#ifdef CONFIG_PM_SLEEP + .freeze = virtio_fs_freeze, + .restore = virtio_fs_restore, +#endif +}; + +static void virtio_fs_wake_forget_and_unlock(struct fuse_iqueue *fiq) +__releases(fiq->lock) +{ + struct fuse_forget_link *link; + struct virtio_fs_forget *forget; + struct scatterlist sg; + struct scatterlist *sgs[] = {&sg}; + struct virtio_fs *fs; + struct virtqueue *vq; + struct virtio_fs_vq *fsvq; + bool notify; + u64 unique; + int ret; + + link = fuse_dequeue_forget(fiq, 1, NULL); + unique = fuse_get_unique(fiq); + + fs = fiq->priv; + fsvq = &fs->vqs[VQ_HIPRIO]; + spin_unlock(&fiq->lock); + + /* Allocate a buffer for the request */ + forget = kmalloc(sizeof(*forget), GFP_NOFS | __GFP_NOFAIL); + + forget->ih = (struct fuse_in_header){ + .opcode = FUSE_FORGET, + .nodeid = link->forget_one.nodeid, + .unique = unique, + .len = sizeof(*forget), + }; + forget->arg = (struct fuse_forget_in){ + .nlookup = link->forget_one.nlookup, + }; + + sg_init_one(&sg, forget, sizeof(*forget)); + + /* Enqueue the request */ + spin_lock(&fsvq->lock); + + if (!fsvq->connected) { + kfree(forget); + spin_unlock(&fsvq->lock); + goto out; + } + + vq = fsvq->vq; + dev_dbg(&vq->vdev->dev, "%s\n", __func__); + + ret = virtqueue_add_sgs(vq, sgs, 1, 0, forget, GFP_ATOMIC); + if (ret < 0) { + if (ret == -ENOMEM || ret == -ENOSPC) { + pr_debug("virtio-fs: Could not queue FORGET: err=%d. Will try later.\n", + ret); + list_add_tail(&forget->list, &fsvq->queued_reqs); + schedule_delayed_work(&fsvq->dispatch_work, + msecs_to_jiffies(1)); + } else { + pr_debug("virtio-fs: Could not queue FORGET: err=%d. Dropping it.\n", + ret); + kfree(forget); + } + spin_unlock(&fsvq->lock); + goto out; + } + + fsvq->in_flight++; + notify = virtqueue_kick_prepare(vq); + + spin_unlock(&fsvq->lock); + + if (notify) + virtqueue_notify(vq); +out: + kfree(link); +} + +static void virtio_fs_wake_interrupt_and_unlock(struct fuse_iqueue *fiq) +__releases(fiq->lock) +{ + /* + * TODO interrupts. + * + * Normal fs operations on a local filesystems aren't interruptible. + * Exceptions are blocking lock operations; for example fcntl(F_SETLKW) + * with shared lock between host and guest. + */ + spin_unlock(&fiq->lock); +} + +/* Return the number of scatter-gather list elements required */ +static unsigned int sg_count_fuse_req(struct fuse_req *req) +{ + struct fuse_args *args = req->args; + struct fuse_args_pages *ap = container_of(args, typeof(*ap), args); + unsigned int total_sgs = 1 /* fuse_in_header */; + + if (args->in_numargs - args->in_pages) + total_sgs += 1; + + if (args->in_pages) + total_sgs += ap->num_pages; + + if (!test_bit(FR_ISREPLY, &req->flags)) + return total_sgs; + + total_sgs += 1 /* fuse_out_header */; + + if (args->out_numargs - args->out_pages) + total_sgs += 1; + + if (args->out_pages) + total_sgs += ap->num_pages; + + return total_sgs; +} + +/* Add pages to scatter-gather list and return number of elements used */ +static unsigned int sg_init_fuse_pages(struct scatterlist *sg, + struct page **pages, + struct fuse_page_desc *page_descs, + unsigned int num_pages, + unsigned int total_len) +{ + unsigned int i; + unsigned int this_len; + + for (i = 0; i < num_pages && total_len; i++) { + sg_init_table(&sg[i], 1); + this_len = min(page_descs[i].length, total_len); + sg_set_page(&sg[i], pages[i], this_len, page_descs[i].offset); + total_len -= this_len; + } + + return i; +} + +/* Add args to scatter-gather list and return number of elements used */ +static unsigned int sg_init_fuse_args(struct scatterlist *sg, + struct fuse_req *req, + struct fuse_arg *args, + unsigned int numargs, + bool argpages, + void *argbuf, + unsigned int *len_used) +{ + struct fuse_args_pages *ap = container_of(req->args, typeof(*ap), args); + unsigned int total_sgs = 0; + unsigned int len; + + len = fuse_len_args(numargs - argpages, args); + if (len) + sg_init_one(&sg[total_sgs++], argbuf, len); + + if (argpages) + total_sgs += sg_init_fuse_pages(&sg[total_sgs], + ap->pages, ap->descs, + ap->num_pages, + args[numargs - 1].size); + + if (len_used) + *len_used = len; + + return total_sgs; +} + +/* Add a request to a virtqueue and kick the device */ +static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq, + struct fuse_req *req) +{ + /* requests need at least 4 elements */ + struct scatterlist *stack_sgs[6]; + struct scatterlist stack_sg[ARRAY_SIZE(stack_sgs)]; + struct scatterlist **sgs = stack_sgs; + struct scatterlist *sg = stack_sg; + struct virtqueue *vq; + struct fuse_args *args = req->args; + unsigned int argbuf_used = 0; + unsigned int out_sgs = 0; + unsigned int in_sgs = 0; + unsigned int total_sgs; + unsigned int i; + int ret; + bool notify; + + /* Does the sglist fit on the stack? */ + total_sgs = sg_count_fuse_req(req); + if (total_sgs > ARRAY_SIZE(stack_sgs)) { + sgs = kmalloc_array(total_sgs, sizeof(sgs[0]), GFP_ATOMIC); + sg = kmalloc_array(total_sgs, sizeof(sg[0]), GFP_ATOMIC); + if (!sgs || !sg) { + ret = -ENOMEM; + goto out; + } + } + + /* Use a bounce buffer since stack args cannot be mapped */ + ret = copy_args_to_argbuf(req); + if (ret < 0) + goto out; + + /* Request elements */ + sg_init_one(&sg[out_sgs++], &req->in.h, sizeof(req->in.h)); + out_sgs += sg_init_fuse_args(&sg[out_sgs], req, + (struct fuse_arg *)args->in_args, + args->in_numargs, args->in_pages, + req->argbuf, &argbuf_used); + + /* Reply elements */ + if (test_bit(FR_ISREPLY, &req->flags)) { + sg_init_one(&sg[out_sgs + in_sgs++], + &req->out.h, sizeof(req->out.h)); + in_sgs += sg_init_fuse_args(&sg[out_sgs + in_sgs], req, + args->out_args, args->out_numargs, + args->out_pages, + req->argbuf + argbuf_used, NULL); + } + + WARN_ON(out_sgs + in_sgs != total_sgs); + + for (i = 0; i < total_sgs; i++) + sgs[i] = &sg[i]; + + spin_lock(&fsvq->lock); + + if (!fsvq->connected) { + spin_unlock(&fsvq->lock); + ret = -ENOTCONN; + goto out; + } + + vq = fsvq->vq; + ret = virtqueue_add_sgs(vq, sgs, out_sgs, in_sgs, req, GFP_ATOMIC); + if (ret < 0) { + spin_unlock(&fsvq->lock); + goto out; + } + + fsvq->in_flight++; + notify = virtqueue_kick_prepare(vq); + + spin_unlock(&fsvq->lock); + + if (notify) + virtqueue_notify(vq); + +out: + if (ret < 0 && req->argbuf) { + kfree(req->argbuf); + req->argbuf = NULL; + } + if (sgs != stack_sgs) { + kfree(sgs); + kfree(sg); + } + + return ret; +} + +static void virtio_fs_wake_pending_and_unlock(struct fuse_iqueue *fiq) +__releases(fiq->lock) +{ + unsigned int queue_id = VQ_REQUEST; /* TODO multiqueue */ + struct virtio_fs *fs; + struct fuse_conn *fc; + struct fuse_req *req; + struct fuse_pqueue *fpq; + int ret; + + WARN_ON(list_empty(&fiq->pending)); + req = list_last_entry(&fiq->pending, struct fuse_req, list); + clear_bit(FR_PENDING, &req->flags); + list_del_init(&req->list); + WARN_ON(!list_empty(&fiq->pending)); + spin_unlock(&fiq->lock); + + fs = fiq->priv; + fc = fs->vqs[queue_id].fud->fc; + + pr_debug("%s: opcode %u unique %#llx nodeid %#llx in.len %u out.len %u\n", + __func__, req->in.h.opcode, req->in.h.unique, + req->in.h.nodeid, req->in.h.len, + fuse_len_args(req->args->out_numargs, req->args->out_args)); + + fpq = &fs->vqs[queue_id].fud->pq; + spin_lock(&fpq->lock); + if (!fpq->connected) { + spin_unlock(&fpq->lock); + req->out.h.error = -ENODEV; + pr_err("virtio-fs: %s disconnected\n", __func__); + fuse_request_end(fc, req); + return; + } + list_add_tail(&req->list, fpq->processing); + spin_unlock(&fpq->lock); + set_bit(FR_SENT, &req->flags); + /* matches barrier in request_wait_answer() */ + smp_mb__after_atomic(); + +retry: + ret = virtio_fs_enqueue_req(&fs->vqs[queue_id], req); + if (ret < 0) { + if (ret == -ENOMEM || ret == -ENOSPC) { + /* Virtqueue full. Retry submission */ + /* TODO use completion instead of timeout */ + usleep_range(20, 30); + goto retry; + } + req->out.h.error = ret; + pr_err("virtio-fs: virtio_fs_enqueue_req() failed %d\n", ret); + spin_lock(&fpq->lock); + clear_bit(FR_SENT, &req->flags); + list_del_init(&req->list); + spin_unlock(&fpq->lock); + fuse_request_end(fc, req); + return; + } +} + +const static struct fuse_iqueue_ops virtio_fs_fiq_ops = { + .wake_forget_and_unlock = virtio_fs_wake_forget_and_unlock, + .wake_interrupt_and_unlock = virtio_fs_wake_interrupt_and_unlock, + .wake_pending_and_unlock = virtio_fs_wake_pending_and_unlock, + .release = virtio_fs_fiq_release, +}; + +static int virtio_fs_fill_super(struct super_block *sb) +{ + struct fuse_conn *fc = get_fuse_conn_super(sb); + struct virtio_fs *fs = fc->iq.priv; + unsigned int i; + int err; + struct fuse_fs_context ctx = { + .rootmode = S_IFDIR, + .default_permissions = 1, + .allow_other = 1, + .max_read = UINT_MAX, + .blksize = 512, + .destroy = true, + .no_control = true, + .no_force_umount = true, + }; + + mutex_lock(&virtio_fs_mutex); + + /* After holding mutex, make sure virtiofs device is still there. + * Though we are holding a reference to it, drive ->remove might + * still have cleaned up virtual queues. In that case bail out. + */ + err = -EINVAL; + if (list_empty(&fs->list)) { + pr_info("virtio-fs: tag <%s> not found\n", fs->tag); + goto err; + } + + err = -ENOMEM; + /* Allocate fuse_dev for hiprio and notification queues */ + for (i = 0; i < VQ_REQUEST; i++) { + struct virtio_fs_vq *fsvq = &fs->vqs[i]; + + fsvq->fud = fuse_dev_alloc(); + if (!fsvq->fud) + goto err_free_fuse_devs; + } + + ctx.fudptr = (void **)&fs->vqs[VQ_REQUEST].fud; + err = fuse_fill_super_common(sb, &ctx); + if (err < 0) + goto err_free_fuse_devs; + + fc = fs->vqs[VQ_REQUEST].fud->fc; + + for (i = 0; i < fs->nvqs; i++) { + struct virtio_fs_vq *fsvq = &fs->vqs[i]; + + if (i == VQ_REQUEST) + continue; /* already initialized */ + fuse_dev_install(fsvq->fud, fc); + } + + /* Previous unmount will stop all queues. Start these again */ + virtio_fs_start_all_queues(fs); + fuse_send_init(fc); + mutex_unlock(&virtio_fs_mutex); + return 0; + +err_free_fuse_devs: + virtio_fs_free_devs(fs); +err: + mutex_unlock(&virtio_fs_mutex); + return err; +} + +static void virtio_kill_sb(struct super_block *sb) +{ + struct fuse_conn *fc = get_fuse_conn_super(sb); + struct virtio_fs *vfs; + struct virtio_fs_vq *fsvq; + + /* If mount failed, we can still be called without any fc */ + if (!fc) + return fuse_kill_sb_anon(sb); + + vfs = fc->iq.priv; + fsvq = &vfs->vqs[VQ_HIPRIO]; + + /* Stop forget queue. Soon destroy will be sent */ + spin_lock(&fsvq->lock); + fsvq->connected = false; + spin_unlock(&fsvq->lock); + virtio_fs_drain_all_queues(vfs); + + fuse_kill_sb_anon(sb); + + /* fuse_kill_sb_anon() must have sent destroy. Stop all queues + * and drain one more time and free fuse devices. Freeing fuse + * devices will drop their reference on fuse_conn and that in + * turn will drop its reference on virtio_fs object. + */ + virtio_fs_stop_all_queues(vfs); + virtio_fs_drain_all_queues(vfs); + virtio_fs_free_devs(vfs); +} + +static int virtio_fs_test_super(struct super_block *sb, + struct fs_context *fsc) +{ + struct fuse_conn *fc = fsc->s_fs_info; + + return fc->iq.priv == get_fuse_conn_super(sb)->iq.priv; +} + +static int virtio_fs_set_super(struct super_block *sb, + struct fs_context *fsc) +{ + int err; + + err = get_anon_bdev(&sb->s_dev); + if (!err) + fuse_conn_get(fsc->s_fs_info); + + return err; +} + +static int virtio_fs_get_tree(struct fs_context *fsc) +{ + struct virtio_fs *fs; + struct super_block *sb; + struct fuse_conn *fc; + int err; + + /* This gets a reference on virtio_fs object. This ptr gets installed + * in fc->iq->priv. Once fuse_conn is going away, it calls ->put() + * to drop the reference to this object. + */ + fs = virtio_fs_find_instance(fsc->source); + if (!fs) { + pr_info("virtio-fs: tag <%s> not found\n", fsc->source); + return -EINVAL; + } + + fc = kzalloc(sizeof(struct fuse_conn), GFP_KERNEL); + if (!fc) { + mutex_lock(&virtio_fs_mutex); + virtio_fs_put(fs); + mutex_unlock(&virtio_fs_mutex); + return -ENOMEM; + } + + fuse_conn_init(fc, get_user_ns(current_user_ns()), &virtio_fs_fiq_ops, + fs); + fc->release = fuse_free_conn; + fc->delete_stale = true; + + fsc->s_fs_info = fc; + sb = sget_fc(fsc, virtio_fs_test_super, virtio_fs_set_super); + fuse_conn_put(fc); + if (IS_ERR(sb)) + return PTR_ERR(sb); + + if (!sb->s_root) { + err = virtio_fs_fill_super(sb); + if (err) { + deactivate_locked_super(sb); + return err; + } + + sb->s_flags |= SB_ACTIVE; + } + + WARN_ON(fsc->root); + fsc->root = dget(sb->s_root); + return 0; +} + +static const struct fs_context_operations virtio_fs_context_ops = { + .get_tree = virtio_fs_get_tree, +}; + +static int virtio_fs_init_fs_context(struct fs_context *fsc) +{ + fsc->ops = &virtio_fs_context_ops; + return 0; +} + +static struct file_system_type virtio_fs_type = { + .owner = THIS_MODULE, + .name = "virtiofs", + .init_fs_context = virtio_fs_init_fs_context, + .kill_sb = virtio_kill_sb, +}; + +static int __init virtio_fs_init(void) +{ + int ret; + + ret = register_virtio_driver(&virtio_fs_driver); + if (ret < 0) + return ret; + + ret = register_filesystem(&virtio_fs_type); + if (ret < 0) { + unregister_virtio_driver(&virtio_fs_driver); + return ret; + } + + return 0; +} +module_init(virtio_fs_init); + +static void __exit virtio_fs_exit(void) +{ + unregister_filesystem(&virtio_fs_type); + unregister_virtio_driver(&virtio_fs_driver); +} +module_exit(virtio_fs_exit); + +MODULE_AUTHOR("Stefan Hajnoczi "); +MODULE_DESCRIPTION("Virtio Filesystem"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_FS(KBUILD_MODNAME); +MODULE_DEVICE_TABLE(virtio, id_table); diff --git a/include/uapi/linux/virtio_fs.h b/include/uapi/linux/virtio_fs.h new file mode 100644 index 000000000000..b02eb2ac3d99 --- /dev/null +++ b/include/uapi/linux/virtio_fs.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */ + +#ifndef _UAPI_LINUX_VIRTIO_FS_H +#define _UAPI_LINUX_VIRTIO_FS_H + +#include +#include +#include +#include + +struct virtio_fs_config { + /* Filesystem name (UTF-8, not NUL-terminated, padded with NULs) */ + __u8 tag[36]; + + /* Number of request queues */ + __u32 num_request_queues; +} __attribute__((packed)); + +#endif /* _UAPI_LINUX_VIRTIO_FS_H */ diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h index 348fd0176f75..585e07b27333 100644 --- a/include/uapi/linux/virtio_ids.h +++ b/include/uapi/linux/virtio_ids.h @@ -44,6 +44,7 @@ #define VIRTIO_ID_VSOCK 19 /* virtio vsock transport */ #define VIRTIO_ID_CRYPTO 20 /* virtio crypto */ #define VIRTIO_ID_IOMMU 23 /* virtio IOMMU */ +#define VIRTIO_ID_FS 26 /* virtio filesystem */ #define VIRTIO_ID_PMEM 27 /* virtio pmem */ #endif /* _LINUX_VIRTIO_IDS_H */