[PATCH 05/52] virtio_fs: get mount working

From: Vivek Goyal
Date: Mon Dec 10 2018 - 12:13:59 EST

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From: Stefan Hajnoczi <stefanha@xxxxxxxxxx>

Provide definitions of ->mount and ->kill_sb. This is still WIP.

Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
---
fs/fuse/fuse_i.h | 9 ++++
fs/fuse/inode.c | 12 ++++-
fs/fuse/virtio_fs.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 146 insertions(+), 4 deletions(-)

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 9b5b8b194f77..4fea75c92a7c 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -59,10 +59,12 @@ extern unsigned max_user_congthresh;
/** Mount options */
struct fuse_mount_data {
int fd;
+ const char *tag; /* lifetime: .fill_super() data argument */
unsigned rootmode;
kuid_t user_id;
kgid_t group_id;
unsigned fd_present:1;
+ unsigned tag_present:1;
unsigned rootmode_present:1;
unsigned user_id_present:1;
unsigned group_id_present:1;
@@ -1002,6 +1004,13 @@ int fuse_fill_super_common(struct super_block *sb,
void **fudptr);

/**
+ * Disassociate fuse connection from superblock and kill the superblock
+ *
+ * Calls kill_anon_super(), use with do not use with bdev mounts.
+ */
+void fuse_kill_sb_anon(struct super_block *sb);
+
+/**
* Add connection to control filesystem
*/
int fuse_ctl_add_conn(struct fuse_conn *fc);
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index f13133f0ebd1..65fd59fc1e81 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -431,6 +431,7 @@ static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)

enum {
OPT_FD,
+ OPT_TAG,
OPT_ROOTMODE,
OPT_USER_ID,
OPT_GROUP_ID,
@@ -443,6 +444,7 @@ enum {

static const match_table_t tokens = {
{OPT_FD, "fd=%u"},
+ {OPT_TAG, "tag=%s"},
{OPT_ROOTMODE, "rootmode=%o"},
{OPT_USER_ID, "user_id=%u"},
{OPT_GROUP_ID, "group_id=%u"},
@@ -489,6 +491,11 @@ int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev,
d->fd_present = 1;
break;

+ case OPT_TAG:
+ d->tag = args[0].from;
+ d->tag_present = 1;
+ break;
+
case OPT_ROOTMODE:
if (match_octal(&args[0], &value))
return 0;
@@ -1204,7 +1211,7 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
err = -EINVAL;
if (!parse_fuse_opt(data, &d, is_bdev, sb->s_user_ns))
goto err;
- if (!d.fd_present)
+ if (!d.fd_present || d.tag_present)
goto err;

file = fget(d.fd);
@@ -1249,11 +1256,12 @@ static void fuse_sb_destroy(struct super_block *sb)
}
}

-static void fuse_kill_sb_anon(struct super_block *sb)
+void fuse_kill_sb_anon(struct super_block *sb)
{
fuse_sb_destroy(sb);
kill_anon_super(sb);
}
+EXPORT_SYMBOL_GPL(fuse_kill_sb_anon);

static struct file_system_type fuse_fs_type = {
.owner = THIS_MODULE,
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index aac9c3c42827..8cdeb02f3778 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -8,6 +8,7 @@
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_fs.h>
+#include "fuse_i.h"

/* List of virtio-fs device instances and a lock for the list */
static DEFINE_MUTEX(virtio_fs_mutex);
@@ -17,6 +18,8 @@ static LIST_HEAD(virtio_fs_instances);
struct virtio_fs {
struct list_head list; /* on virtio_fs_instances */
char *tag;
+ struct fuse_dev **fud; /* 1:1 mapping with request queues */
+ unsigned int num_queues;
};

/* Add a new instance to the list or return -EEXIST if tag name exists*/
@@ -42,6 +45,46 @@ static int virtio_fs_add_instance(struct virtio_fs *fs)
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)
+ 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;
+
+ /* TODO lock */
+
+ if (!fs->fud)
+ return;
+
+ for (i = 0; i < fs->num_queues; i++) {
+ struct fuse_dev *fud = fs->fud[i];
+
+ if (fud)
+ fuse_dev_free(fud); /* TODO need to quiesce/end_requests/decrement dev_count */
+ }
+
+ kfree(fs->fud);
+ fs->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)
{
@@ -76,6 +119,13 @@ static int virtio_fs_probe(struct virtio_device *vdev)
return -ENOMEM;
vdev->priv = fs;

+ virtio_cread(vdev, struct virtio_fs_config, num_queues,
+ &fs->num_queues);
+ if (fs->num_queues == 0) {
+ ret = -EINVAL;
+ goto out;
+ }
+
ret = virtio_fs_read_tag(vdev, fs);
if (ret < 0)
goto out;
@@ -95,6 +145,8 @@ static void virtio_fs_remove(struct virtio_device *vdev)
{
struct virtio_fs *fs = vdev->priv;

+ virtio_fs_free_devs(fs);
+
vdev->config->reset(vdev);

mutex_lock(&virtio_fs_mutex);
@@ -138,11 +190,84 @@ static struct virtio_driver virtio_fs_driver = {
#endif
};

+static int virtio_fs_fill_super(struct super_block *sb, void *data,
+ int silent)
+{
+ struct fuse_mount_data d;
+ struct fuse_conn *fc;
+ struct virtio_fs *fs;
+ int is_bdev = sb->s_bdev != NULL;
+ unsigned int i;
+ int err;
+
+ err = -EINVAL;
+ if (!parse_fuse_opt(data, &d, is_bdev, sb->s_user_ns))
+ goto err;
+ if (d.fd_present) {
+ printk(KERN_ERR "virtio-fs: fd option cannot be used\n");
+ goto err;
+ }
+ if (!d.tag_present) {
+ printk(KERN_ERR "virtio-fs: missing tag option\n");
+ goto err;
+ }
+
+ fs = virtio_fs_find_instance(d.tag);
+ if (!fs) {
+ printk(KERN_ERR "virtio-fs: tag not found\n");
+ err = -ENOENT;
+ goto err;
+ }
+
+ /* TODO lock */
+ if (fs->fud) {
+ printk(KERN_ERR "virtio-fs: device already in use\n");
+ err = -EBUSY;
+ goto err;
+ }
+ fs->fud = kcalloc(fs->num_queues, sizeof(fs->fud[0]), GFP_KERNEL);
+ if (!fs->fud) {
+ err = -ENOMEM;
+ goto err_fud;
+ }
+
+ err = fuse_fill_super_common(sb, &d, (void **)&fs->fud[0]);
+ if (err < 0)
+ goto err_fud;
+
+ fc = fs->fud[0]->fc;
+
+ /* Allocate remaining fuse_devs */
+ err = -ENOMEM;
+ /* TODO take fuse_mutex around this loop? */
+ for (i = 1; i < fs->num_queues; i++) {
+ fs->fud[i] = fuse_dev_alloc(fc);
+ if (!fs->fud[i]) {
+ /* TODO */
+ }
+ atomic_inc(&fc->dev_count);
+ }
+
+ return 0;
+
+err_fud:
+ virtio_fs_free_devs(fs);
+err:
+ return err;
+}
+
+static struct dentry *virtio_fs_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name,
+ void *raw_data)
+{
+ return mount_nodev(fs_type, flags, raw_data, virtio_fs_fill_super);
+}
+
static struct file_system_type virtio_fs_type = {
.owner = THIS_MODULE,
.name = KBUILD_MODNAME,
- .mount = NULL,
- .kill_sb = NULL,
+ .mount = virtio_fs_mount,
+ .kill_sb = fuse_kill_sb_anon,
};

static int __init virtio_fs_init(void)
--
2.13.6

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