@@ -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.
@@ -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
@@ -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);
+
+ /**
+ * Cleanup up when fuse_iqueue is destroyed
+ */
+ void (*release)(struct fuse_iqueue *fiq);
};
/** /dev/fuse input queue operations */
@@ -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);
new file mode 100644
@@ -0,0 +1,1191 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * virtio-fs: Virtio Filesystem
+ * Copyright (C) 2018 Red Hat, Inc.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/virtio.h>
+#include <linux/virtio_fs.h>
+#include <linux/delay.h>
+#include <linux/fs_context.h>
+#include <linux/highmem.h>
+#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_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);
+ 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_queues,
+ &fs->num_queues);
+ if (fs->num_queues == 0)
+ return -EINVAL;
+
+ fs->nvqs = 1 + fs->num_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)
+{
+ return 0; /* TODO */
+}
+
+static int virtio_fs_restore(struct virtio_device *vdev)
+{
+ return 0; /* TODO */
+}
+#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) {
+ /* TODO handle full virtqueue */
+ 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 */
+ 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 refernce 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 <stefanha@redhat.com>");
+MODULE_DESCRIPTION("Virtio Filesystem");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_FS(KBUILD_MODNAME);
+MODULE_DEVICE_TABLE(virtio, id_table);
new file mode 100644
@@ -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 <linux/types.h>
+#include <linux/virtio_ids.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_types.h>
+
+struct virtio_fs_config {
+ /* Filesystem name (UTF-8, not NUL-terminated, padded with NULs) */
+ __u8 tag[36];
+
+ /* Number of request queues */
+ __u32 num_queues;
+} __attribute__((packed));
+
+#endif /* _UAPI_LINUX_VIRTIO_FS_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 */