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Subject[PATCH 02/52] fuse: add probe/remove virtio driver
Date
From: Stefan Hajnoczi <stefanha@redhat.com>

Add basic probe/remove functionality for the new virtio-fs device.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
fs/fuse/Kconfig | 1 +
fs/fuse/virtio_fs.c | 160 ++++++++++++++++++++++++++++++++++++++--
include/uapi/linux/virtio_fs.h | 41 ++++++++++
include/uapi/linux/virtio_ids.h | 1 +
4 files changed, 195 insertions(+), 8 deletions(-)
create mode 100644 include/uapi/linux/virtio_fs.h

diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
index 0b1375126420..46e9a8ff9f7a 100644
--- a/fs/fuse/Kconfig
+++ b/fs/fuse/Kconfig
@@ -30,6 +30,7 @@ config CUSE
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.
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 6b7d3973bd85..aac9c3c42827 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -4,13 +4,139 @@
* Copyright (C) 2018 Red Hat, Inc.
*/

-#include <linux/module.h>
#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/virtio.h>
+#include <linux/virtio_fs.h>

-MODULE_AUTHOR("Stefan Hajnoczi <stefanha@redhat.com>");
-MODULE_DESCRIPTION("Virtio Filesystem");
-MODULE_LICENSE("GPL");
-MODULE_ALIAS_FS(KBUILD_MODNAME);
+/* List of virtio-fs device instances and a lock for the list */
+static DEFINE_MUTEX(virtio_fs_mutex);
+static LIST_HEAD(virtio_fs_instances);
+
+/* A virtio-fs device instance */
+struct virtio_fs {
+ struct list_head list; /* on virtio_fs_instances */
+ char *tag;
+};
+
+/* 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;
+}
+
+/* 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;
+}
+
+static int virtio_fs_probe(struct virtio_device *vdev)
+{
+ struct virtio_fs *fs;
+ int ret;
+
+ fs = devm_kzalloc(&vdev->dev, sizeof(*fs), GFP_KERNEL);
+ if (!fs)
+ return -ENOMEM;
+ vdev->priv = fs;
+
+ ret = virtio_fs_read_tag(vdev, fs);
+ if (ret < 0)
+ goto out;
+
+ ret = virtio_fs_add_instance(fs);
+ if (ret < 0)
+ goto out;
+
+ return 0;
+
+out:
+ vdev->priv = NULL;
+ return ret;
+}
+
+static void virtio_fs_remove(struct virtio_device *vdev)
+{
+ struct virtio_fs *fs = vdev->priv;
+
+ vdev->config->reset(vdev);
+
+ mutex_lock(&virtio_fs_mutex);
+ list_del(&fs->list);
+ mutex_unlock(&virtio_fs_mutex);
+
+ vdev->priv = NULL;
+}
+
+#ifdef CONFIG_PM
+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 */
+
+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),
+ /* TODO validate config_get != NULL */
+ .probe = virtio_fs_probe,
+ .remove = virtio_fs_remove,
+#ifdef CONFIG_PM_SLEEP
+ .freeze = virtio_fs_freeze,
+ .restore = virtio_fs_restore,
+#endif
+};

static struct file_system_type virtio_fs_type = {
.owner = THIS_MODULE,
@@ -21,13 +147,31 @@ static struct file_system_type virtio_fs_type = {

static int __init virtio_fs_init(void)
{
- return register_filesystem(&virtio_fs_type);
+ 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_init(virtio_fs_init);
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);
diff --git a/include/uapi/linux/virtio_fs.h b/include/uapi/linux/virtio_fs.h
new file mode 100644
index 000000000000..48f3590dcfbe
--- /dev/null
+++ b/include/uapi/linux/virtio_fs.h
@@ -0,0 +1,41 @@
+#ifndef _UAPI_LINUX_VIRTIO_FS_H
+#define _UAPI_LINUX_VIRTIO_FS_H
+/* This header is BSD licensed so anyone can use the definitions to implement
+ * compatible drivers/servers.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of IBM nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE. */
+#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 */
diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
index 6d5c3b2d4f4d..884b0e2734bb 100644
--- a/include/uapi/linux/virtio_ids.h
+++ b/include/uapi/linux/virtio_ids.h
@@ -43,5 +43,6 @@
#define VIRTIO_ID_INPUT 18 /* virtio input */
#define VIRTIO_ID_VSOCK 19 /* virtio vsock transport */
#define VIRTIO_ID_CRYPTO 20 /* virtio crypto */
+#define VIRTIO_ID_FS 26 /* virtio filesystem */

#endif /* _LINUX_VIRTIO_IDS_H */
--
2.13.6
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