With FUSE it is possible to implement a fully functional filesystem
in a userspace program.
- There's also companion library: libfuse. This library along with
- utilities is available from the FUSE homepage:
+ There's also a companion library: libfuse2. This library is available
+ from the FUSE homepage:
<http://fuse.sourceforge.net/>
+ although chances are your distribution already has that library
+ installed if you've installed the "fuse" package itself.
See <file:Documentation/filesystems/fuse.txt> for more information.
See <file:Documentation/Changes> for needed library/utility version.
If you want to develop a userspace FS, or if you want to use
a filesystem based on FUSE, answer Y or M.
+
+config CUSE
+ tristate "Character device in Userspace support"
+ depends on FUSE_FS
+ help
+ This FUSE extension allows character devices to be
+ implemented in userspace.
+
+ If you want to develop or use a userspace character device
+ based on CUSE, answer Y or M.
#include <linux/miscdevice.h>
#include <linux/mutex.h>
#include <linux/slab.h>
-#include <linux/spinlock.h>
#include <linux/stat.h>
#include <linux/module.h>
bool unrestricted_ioctl;
};
-static DEFINE_SPINLOCK(cuse_lock); /* protects cuse_conntbl */
+static DEFINE_MUTEX(cuse_lock); /* protects registration */
static struct list_head cuse_conntbl[CUSE_CONNTBL_LEN];
static struct class *cuse_class;
int rc;
/* look up and get the connection */
- spin_lock(&cuse_lock);
+ mutex_lock(&cuse_lock);
list_for_each_entry(pos, cuse_conntbl_head(devt), list)
if (pos->dev->devt == devt) {
fuse_conn_get(&pos->fc);
cc = pos;
break;
}
- spin_unlock(&cuse_lock);
+ mutex_unlock(&cuse_lock);
/* dead? */
if (!cc)
static int cuse_parse_devinfo(char *p, size_t len, struct cuse_devinfo *devinfo)
{
char *end = p + len;
- char *key, *val;
+ char *uninitialized_var(key), *uninitialized_var(val);
int rc;
while (true) {
*/
static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
{
- struct cuse_conn *cc = fc_to_cc(fc);
+ struct cuse_conn *cc = fc_to_cc(fc), *pos;
struct cuse_init_out *arg = req->out.args[0].value;
struct page *page = req->pages[0];
struct cuse_devinfo devinfo = { };
struct device *dev;
struct cdev *cdev;
dev_t devt;
- int rc;
+ int rc, i;
if (req->out.h.error ||
arg->major != FUSE_KERNEL_VERSION || arg->minor < 11) {
dev_set_drvdata(dev, cc);
dev_set_name(dev, "%s", devinfo.name);
+ mutex_lock(&cuse_lock);
+
+ /* make sure the device-name is unique */
+ for (i = 0; i < CUSE_CONNTBL_LEN; ++i) {
+ list_for_each_entry(pos, &cuse_conntbl[i], list)
+ if (!strcmp(dev_name(pos->dev), dev_name(dev)))
+ goto err_unlock;
+ }
+
rc = device_add(dev);
if (rc)
- goto err_device;
+ goto err_unlock;
/* register cdev */
rc = -ENOMEM;
cdev = cdev_alloc();
if (!cdev)
- goto err_device;
+ goto err_unlock;
cdev->owner = THIS_MODULE;
cdev->ops = &cuse_frontend_fops;
cc->cdev = cdev;
/* make the device available */
- spin_lock(&cuse_lock);
list_add(&cc->list, cuse_conntbl_head(devt));
- spin_unlock(&cuse_lock);
+ mutex_unlock(&cuse_lock);
/* announce device availability */
dev_set_uevent_suppress(dev, 0);
err_cdev:
cdev_del(cdev);
-err_device:
+err_unlock:
+ mutex_unlock(&cuse_lock);
put_device(dev);
err_region:
unregister_chrdev_region(devt, 1);
int rc;
/* remove from the conntbl, no more access from this point on */
- spin_lock(&cuse_lock);
+ mutex_lock(&cuse_lock);
list_del_init(&cc->list);
- spin_unlock(&cuse_lock);
+ mutex_unlock(&cuse_lock);
/* remove device */
if (cc->dev)
struct page *oldpage = *pagep;
struct page *newpage;
struct pipe_buffer *buf = cs->pipebufs;
- struct address_space *mapping;
- pgoff_t index;
unlock_request(cs->fc, cs->req);
fuse_copy_finish(cs);
if (fuse_check_page(newpage) != 0)
goto out_fallback_unlock;
- mapping = oldpage->mapping;
- index = oldpage->index;
-
/*
* This is a new and locked page, it shouldn't be mapped or
* have any special flags on it
return ret;
}
-long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
- loff_t length)
+static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
+ loff_t length)
{
struct fuse_file *ff = file->private_data;
struct fuse_conn *fc = ff->fc;
return err;
}
-EXPORT_SYMBOL_GPL(fuse_file_fallocate);
static const struct file_operations fuse_file_operations = {
.llseek = fuse_file_llseek,