[PATCH 3/13] Filesystem in Userspace

[PATCH 3/13] Filesystem in Userspace

[Miklos Szeredi]

This patch adds FUSE core. 

This contains the following files:

 o dev.c
    - fuse device operations (read, write, release, poll)
    - adds /sys/fs/fuse/version
    - registers misc device

 o dir.c
    - directory operations (only lookup this patch)

 o inode.c
    - superblock operations (alloc_inode, destroy_inode, read_inode,
      clear_inode, put_super, show_options)
    - registers FUSE filesystem

 o util.c
    - module initialization and cleanup

 o fuse_i.h
    - private header file

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
--- linux-2.6.10-rc2/fs/fuse/dev.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.10-rc2-fuse/fs/fuse/dev.c	2004-11-20 22:56:25.000000000 +0100
@@ -0,0 +1,538 @@
+/*
+    FUSE: Filesystem in Userspace
+    Copyright (C) 2001-2004  Miklos Szeredi <miklos@szeredi.hu>
+
+    This program can be distributed under the terms of the GNU GPL.
+    See the file COPYING.
+*/
+
+#include "fuse_i.h"
+
+#include <linux/module.h>
+#include <linux/poll.h>
+#include <linux/kobject.h>
+#include <linux/miscdevice.h>
+#include <linux/file.h>
+
+static kmem_cache_t *fuse_req_cachep;
+
+static inline struct fuse_conn *fuse_get_conn(struct file *file)
+{
+	struct fuse_conn *fc;
+	spin_lock(&fuse_lock);
+	fc = file->private_data;
+	if (fc && !fc->sb)
+		fc = NULL;
+	spin_unlock(&fuse_lock);
+	return fc;
+}
+
+struct fuse_req *fuse_request_alloc(void)
+{
+	struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, SLAB_KERNEL);
+	if (req) {
+		memset(req, 0, sizeof(*req));
+		INIT_LIST_HEAD(&req->list);
+		init_waitqueue_head(&req->waitq);
+	}
+	return req;
+}
+
+void fuse_request_free(struct fuse_req *req)
+{
+	kmem_cache_free(fuse_req_cachep, req);
+}
+
+/* Called with fuse_lock held.  Releases, and then reaquires it. */
+static void request_wait_answer(struct fuse_req *req)
+{
+	spin_unlock(&fuse_lock);
+	wait_event(req->waitq, req->finished);
+	spin_lock(&fuse_lock);
+}
+
+static int get_unique(struct fuse_conn *fc)
+{
+	fc->reqctr++;
+	if (fc->reqctr == 0)
+		fc->reqctr = 1;
+	return fc->reqctr;
+}
+
+void fuse_reset_request(struct fuse_req *req)
+{
+	int preallocated = req->preallocated;
+	
+	memset(req, 0, sizeof(*req));
+	INIT_LIST_HEAD(&req->list);
+	init_waitqueue_head(&req->waitq);
+	req->preallocated = preallocated;
+}
+
+static struct fuse_req *do_get_request(struct fuse_conn *fc)
+{
+	struct fuse_req *req;
+
+	spin_lock(&fuse_lock);
+	BUG_ON(list_empty(&fc->unused_list));
+	req = list_entry(fc->unused_list.next, struct fuse_req, list);
+	list_del_init(&req->list);
+	spin_unlock(&fuse_lock);
+	fuse_reset_request(req);
+	req->in.h.uid = current->fsuid;
+	req->in.h.gid = current->fsgid;
+	req->in.h.pid = current->pid;
+	return req;
+}
+
+struct fuse_req *fuse_get_request(struct fuse_conn *fc)
+{
+	if (down_interruptible(&fc->unused_sem))
+		return NULL;
+	return  do_get_request(fc);
+}
+
+struct fuse_req *fuse_get_request_nonblock(struct fuse_conn *fc)
+{
+	if (down_trylock(&fc->unused_sem))
+		return NULL;
+	return  do_get_request(fc);
+}
+
+void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
+{
+	if (!req->preallocated)
+		fuse_request_free(req);
+	else {
+		spin_lock(&fuse_lock);
+		list_add(&req->list, &fc->unused_list);
+		spin_unlock(&fuse_lock);
+		up(&fc->unused_sem);
+	}
+}
+
+/* Must be called with fuse_lock held, and unlocks it */
+static void request_end(struct fuse_conn *fc, struct fuse_req *req)
+{
+	wake_up(&req->waitq);
+	spin_unlock(&fuse_lock);
+}
+
+void request_send(struct fuse_conn *fc, struct fuse_req *req)
+{
+	req->isreply = 1;
+		
+	spin_lock(&fuse_lock);
+	req->out.h.error = -ENOTCONN;
+	if (fc->file) {
+		req->in.h.unique = get_unique(fc);		
+		list_add_tail(&req->list, &fc->pending);
+		wake_up(&fc->waitq);
+		request_wait_answer(req);
+		list_del(&req->list);
+	}
+	spin_unlock(&fuse_lock);
+}
+
+void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req)
+{
+	req->isreply = 0;
+
+	spin_lock(&fuse_lock);
+	if (fc->file) {
+		list_add_tail(&req->list, &fc->pending);
+		wake_up(&fc->waitq);
+		spin_unlock(&fuse_lock);
+	} else {
+		spin_unlock(&fuse_lock);
+		fuse_put_request(fc, req);
+	}
+}
+
+static void request_wait(struct fuse_conn *fc)
+{
+	DECLARE_WAITQUEUE(wait, current);
+
+	add_wait_queue_exclusive(&fc->waitq, &wait);
+	while (fc->sb && list_empty(&fc->pending)) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (signal_pending(current))
+			break;
+
+		spin_unlock(&fuse_lock);
+		schedule();
+		spin_lock(&fuse_lock);
+	}
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&fc->waitq, &wait);
+}
+
+static inline int copy_in_one(const void *src, size_t srclen,
+			      char __user **dstp, size_t *dstlenp)
+{
+	if (*dstlenp < srclen) {
+		printk("fuse_dev_read: buffer too small\n");
+		return -EINVAL;
+	}
+			
+	if (srclen && copy_to_user(*dstp, src, srclen))
+		return -EFAULT;
+
+	*dstp += srclen;
+	*dstlenp -= srclen;
+
+	return 0;
+}
+
+static inline int copy_in_args(struct fuse_in *in, char __user *buf,
+			       size_t nbytes)
+{
+	int err;
+	int i;
+	size_t orignbytes = nbytes;
+		
+	err = copy_in_one(&in->h, sizeof(in->h), &buf, &nbytes);
+	if (err)
+		return err;
+
+	for (i = 0; i < in->numargs; i++) {
+		struct fuse_in_arg *arg = &in->args[i];
+		err = copy_in_one(arg->value, arg->size, &buf, &nbytes);
+		if (err)
+			return err;
+	}
+
+	return orignbytes - nbytes;
+}
+
+static ssize_t fuse_dev_read(struct file *file, char __user *buf,
+			     size_t nbytes, loff_t *off)
+{
+	ssize_t ret;
+	struct fuse_conn *fc;
+	struct fuse_req *req = NULL;
+
+	spin_lock(&fuse_lock);
+	fc = file->private_data;
+	if (!fc) {
+		spin_unlock(&fuse_lock);
+		return -EPERM;
+	}
+	request_wait(fc);
+	if (!fc->sb)
+		fc = NULL;
+	else if (!list_empty(&fc->pending)) {
+		req = list_entry(fc->pending.next, struct fuse_req, list);
+		list_del_init(&req->list);
+	}
+	spin_unlock(&fuse_lock);
+	if (!fc)
+		return -ENODEV;
+	if (req == NULL)
+		return -EINTR;
+
+	ret = copy_in_args(&req->in, buf, nbytes);
+	spin_lock(&fuse_lock);
+	if (req->isreply) {
+		if (ret < 0) {
+			req->out.h.error = -EPROTO;
+			req->finished = 1;
+		} else
+			list_add_tail(&req->list, &fc->processing);
+		if (ret < 0)
+			/* Unlocks fuse_lock: */
+			request_end(fc, req);
+		else
+			spin_unlock(&fuse_lock);
+	} else {
+		spin_unlock(&fuse_lock);
+		fuse_put_request(fc, req);
+	}
+	return ret;
+}
+
+static struct fuse_req *request_find(struct fuse_conn *fc, unsigned int unique)
+{
+	struct list_head *entry;
+	struct fuse_req *req = NULL;
+
+	list_for_each(entry, &fc->processing) {
+		struct fuse_req *tmp;
+		tmp = list_entry(entry, struct fuse_req, list);
+		if (tmp->in.h.unique == unique) {
+			req = tmp;
+			break;
+		}
+	}
+
+	return req;
+}
+
+static inline int copy_out_one(struct fuse_out_arg *arg,
+			       const char __user **srcp,
+			       size_t *srclenp, int allowvar)
+{
+	size_t dstlen = arg->size;
+	if (*srclenp < dstlen) {
+		if (!allowvar) {
+			printk("fuse_dev_write: write is short\n");
+			return -EINVAL;
+		}
+		dstlen = *srclenp;
+	}
+
+	if (dstlen && copy_from_user(arg->value, *srcp, dstlen))
+		return -EFAULT;
+
+	*srcp += dstlen;
+	*srclenp -= dstlen;
+	arg->size = dstlen;
+
+	return 0;
+}
+
+static inline int copy_out_args(struct fuse_req *req, const char __user *buf,
+				size_t nbytes)
+{
+	struct fuse_out *out = &req->out;
+	int err;
+	int i;
+
+	buf += sizeof(struct fuse_out_header);
+	nbytes -= sizeof(struct fuse_out_header);
+		
+	if (!out->h.error) {
+		for (i = 0; i < out->numargs; i++) {
+			struct fuse_out_arg *arg = &out->args[i];
+			int allowvar;
+			
+			if (out->argvar && i == out->numargs - 1)
+				allowvar = 1;
+			else
+				allowvar = 0;
+			
+			err = copy_out_one(arg, &buf, &nbytes, allowvar);
+			if (err)
+				return err;
+		}
+	}
+
+	if (nbytes != 0) {
+		printk("fuse_dev_write: write is long\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static inline int copy_out_header(struct fuse_out_header *oh,
+				  const char __user *buf, size_t nbytes)
+{
+	if (nbytes < sizeof(struct fuse_out_header)) {
+		printk("fuse_dev_write: write is short\n");
+		return -EINVAL;
+	}
+	
+	if (copy_from_user(oh, buf, sizeof(struct fuse_out_header)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static ssize_t fuse_dev_write(struct file *file, const char __user *buf,
+			      size_t nbytes, loff_t *off)
+{
+	int err;
+	struct fuse_conn *fc = fuse_get_conn(file);
+	struct fuse_req *req;
+	struct fuse_out_header oh;
+	
+	if (!fc)
+		return -ENODEV;
+
+	err = copy_out_header(&oh, buf, nbytes);
+	if (err)
+		return err;
+
+	if (!oh.unique)	{
+		err = -EINVAL;
+		goto out;
+	}     
+
+        if (oh.error <= -1000 || oh.error > 0) {
+                printk("fuse_dev_write: bad error value\n");
+                return -EINVAL;
+        }
+
+	spin_lock(&fuse_lock);
+	req = request_find(fc, oh.unique);
+	if (req != NULL)
+		list_del_init(&req->list);
+	spin_unlock(&fuse_lock);
+	if (!req)
+		return -ENOENT;
+
+	req->out.h = oh;
+	err = copy_out_args(req, buf, nbytes);
+
+	spin_lock(&fuse_lock);
+	if (err)
+		req->out.h.error = -EPROTO;
+
+	req->finished = 1;
+	/* Unlocks fuse_lock: */
+	request_end(fc, req);
+
+  out:
+	if (!err)
+		return nbytes;
+	else
+		return err;
+}
+
+static unsigned int fuse_dev_poll(struct file *file, poll_table *wait)
+{
+	struct fuse_conn *fc = fuse_get_conn(file);
+	unsigned int mask = POLLOUT | POLLWRNORM;
+
+	if (!fc)
+		return -ENODEV;
+
+	poll_wait(file, &fc->waitq, wait);
+
+	spin_lock(&fuse_lock);
+	if (!list_empty(&fc->pending))
+                mask |= POLLIN | POLLRDNORM;
+	spin_unlock(&fuse_lock);
+
+	return mask;
+}
+
+static void end_requests(struct fuse_conn *fc, struct list_head *head)
+{
+	while (!list_empty(head)) {
+		struct fuse_req *req;
+		req = list_entry(head->next, struct fuse_req, list);
+		list_del_init(&req->list);
+		if (req->isreply) {
+			req->out.h.error = -ECONNABORTED;
+			req->finished = 1;
+			/* Unlocks fuse_lock: */
+			request_end(fc, req);
+			spin_lock(&fuse_lock);
+		} else {
+			spin_unlock(&fuse_lock);
+			fuse_put_request(fc, req);
+			spin_lock(&fuse_lock);
+		}
+	}
+}
+
+static int fuse_dev_release(struct inode *inode, struct file *file)
+{
+	struct fuse_conn *fc;
+
+	spin_lock(&fuse_lock);
+	fc = file->private_data;
+	if (fc) {
+		fc->file = NULL;
+		end_requests(fc, &fc->pending);
+		end_requests(fc, &fc->processing);
+		fuse_release_conn(fc);
+	}
+	spin_unlock(&fuse_lock);
+	return 0;
+}
+
+struct file_operations fuse_dev_operations = {
+	.owner		= THIS_MODULE,
+	.read		= fuse_dev_read,
+	.write		= fuse_dev_write,
+	.poll		= fuse_dev_poll,
+	.release	= fuse_dev_release,
+};
+
+#define FUSE_MINOR MISC_DYNAMIC_MINOR
+
+static decl_subsys(fuse, NULL, NULL);
+
+static ssize_t version_show(struct subsystem *subsys, char *buf)
+{
+	return sprintf(buf, "%i.%i\n", FUSE_KERNEL_VERSION,
+		       FUSE_KERNEL_MINOR_VERSION);
+}
+static struct subsys_attribute fuse_attr_version = __ATTR_RO(version);
+
+static struct miscdevice fuse_miscdevice = {
+	.minor = FUSE_MINOR,
+	.name  = "fuse",
+	.fops = &fuse_dev_operations,
+};
+
+static int __init fuse_sysfs_init(void)
+{
+	int err;
+	err = fs_subsys_register(&fuse_subsys);
+	if (err)
+		return err;
+	err = subsys_create_file(&fuse_subsys, &fuse_attr_version);
+	if (err) {
+		subsystem_unregister(&fuse_subsys);
+		return err;
+	}
+	return 0;
+}
+
+static void fuse_sysfs_clean(void)
+{
+	subsys_remove_file(&fuse_subsys, &fuse_attr_version);
+	subsystem_unregister(&fuse_subsys);
+}
+
+static int __init fuse_device_init(void)
+{
+	int err = fuse_sysfs_init();
+	if (err)
+		return err;
+
+	err = misc_register(&fuse_miscdevice);
+	if (err) {
+		fuse_sysfs_clean();
+		return err;
+	}
+	return 0;
+}
+
+static void fuse_device_clean(void)
+{
+	misc_deregister(&fuse_miscdevice);
+	fuse_sysfs_clean();
+}
+
+int __init fuse_dev_init(void)
+{
+	int err;
+	err = fuse_device_init();
+	if (err)
+		goto out;
+
+	err = -ENOMEM;
+	fuse_req_cachep = kmem_cache_create("fuser_request",
+					    sizeof(struct fuse_req),
+					    0, 0, NULL, NULL);
+	if (!fuse_req_cachep)
+		goto out_device_clean;
+	
+	return 0;
+	
+ out_device_clean:
+	fuse_device_clean();
+ out:
+	return err;
+}
+
+void fuse_dev_cleanup(void)
+{
+	fuse_device_clean();
+	kmem_cache_destroy(fuse_req_cachep);
+}
--- linux-2.6.10-rc2/fs/fuse/dir.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.10-rc2-fuse/fs/fuse/dir.c	2004-11-20 22:56:25.000000000 +0100
@@ -0,0 +1,166 @@
+/*
+    FUSE: Filesystem in Userspace
+    Copyright (C) 2001-2004  Miklos Szeredi <miklos@szeredi.hu>
+
+    This program can be distributed under the terms of the GNU GPL.
+    See the file COPYING.
+*/
+
+#include "fuse_i.h"
+
+#include <linux/pagemap.h>
+#include <linux/file.h>
+
+static struct inode_operations fuse_dir_inode_operations;
+
+static void change_attributes(struct inode *inode, struct fuse_attr *attr)
+{
+	if (S_ISREG(inode->i_mode) && i_size_read(inode) != attr->size) {
+		invalidate_inode_pages(inode->i_mapping);
+	}
+
+	inode->i_ino     = attr->ino;
+	inode->i_mode    = (inode->i_mode & S_IFMT) + (attr->mode & 07777);
+	inode->i_nlink   = attr->nlink;
+	inode->i_uid     = attr->uid;
+	inode->i_gid     = attr->gid;
+	i_size_write(inode, attr->size);
+	inode->i_blksize = PAGE_CACHE_SIZE;
+	inode->i_blocks  = attr->blocks;
+	inode->i_atime.tv_sec   = attr->atime;
+	inode->i_atime.tv_nsec  = attr->atimensec;
+	inode->i_mtime.tv_sec   = attr->mtime;
+	inode->i_mtime.tv_nsec  = attr->mtimensec;
+	inode->i_ctime.tv_sec   = attr->ctime;
+	inode->i_ctime.tv_nsec  = attr->ctimensec;
+}
+
+static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
+{
+	inode->i_mode = attr->mode & S_IFMT;
+	i_size_write(inode, attr->size);
+	if (S_ISDIR(inode->i_mode))
+		inode->i_op = &fuse_dir_inode_operations;
+}
+
+static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
+{
+	unsigned long nodeid = *(unsigned long *) _nodeidp;
+	struct fuse_inode *fi = INO_FI(inode);
+	if (fi->nodeid == nodeid)
+		return 1;
+	else
+		return 0;
+}
+
+static int fuse_inode_set(struct inode *inode, void *_nodeidp)
+{
+	unsigned long nodeid = *(unsigned long *) _nodeidp;
+	struct fuse_inode *fi = INO_FI(inode);
+	fi->nodeid = nodeid;
+	return 0;
+}
+
+struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
+			int generation, struct fuse_attr *attr, int version)
+{
+	struct inode *inode;
+
+	inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
+	if (!inode)
+		return NULL;
+
+	if ((inode->i_state & I_NEW)) {
+		inode->i_generation = generation;
+		fuse_init_inode(inode, attr);
+		unlock_new_inode(inode);
+	} else if (inode->i_generation != generation)
+		printk("fuse_iget: bad generation for node %lu\n", nodeid);
+
+	change_attributes(inode, attr);
+	inode->i_version = version;
+	return inode;
+}
+
+static int fuse_send_lookup(struct fuse_conn *fc, struct fuse_req *req,
+			    struct inode *dir, struct dentry *entry, 
+			    struct fuse_entry_out *outarg, int *version)
+{
+	struct fuse_inode *fi = INO_FI(dir);
+	req->in.h.opcode = FUSE_LOOKUP;
+	req->in.h.nodeid = fi->nodeid;
+	req->in.numargs = 1;
+	req->in.args[0].size = entry->d_name.len + 1;
+	req->in.args[0].value = entry->d_name.name;
+	req->out.numargs = 1;
+	req->out.args[0].size = sizeof(struct fuse_entry_out);
+	req->out.args[0].value = outarg;
+	request_send(fc, req);
+	*version = req->out.h.unique;
+	return req->out.h.error;
+}
+
+static inline unsigned long time_to_jiffies(unsigned long sec,
+					    unsigned long nsec)
+{
+	/* prevent wrapping of jiffies */
+	if (sec + 1 >= LONG_MAX / HZ)
+		return 0;
+	
+	return jiffies + sec * HZ + nsec / (1000000000 / HZ);
+}
+
+static int fuse_lookup_iget(struct inode *dir, struct dentry *entry,
+			    struct inode **inodep)
+{
+	struct fuse_conn *fc = INO_FC(dir);
+	int err;
+	struct fuse_entry_out outarg;
+	int version;
+	struct inode *inode = NULL;
+	struct fuse_req *req;
+
+	if (entry->d_name.len > FUSE_NAME_MAX)
+		return -ENAMETOOLONG;
+	req = fuse_get_request(fc);
+	if (!req)
+		return -ERESTARTSYS;
+
+	err = fuse_send_lookup(fc, req, dir, entry, &outarg, &version);
+	if (!err) {
+		inode = fuse_iget(dir->i_sb, outarg.nodeid, outarg.generation,
+				  &outarg.attr, version);
+		if (!inode) {
+			fuse_send_forget(fc, req, outarg.nodeid, version);
+			return -ENOMEM;
+		}
+	} 
+	fuse_put_request(fc, req);
+	if (err && err != -ENOENT)
+		return err;
+
+	if (inode) {
+		struct fuse_inode *fi = INO_FI(inode);
+		entry->d_time =	time_to_jiffies(outarg.entry_valid,
+						outarg.entry_valid_nsec);
+		fi->i_time = time_to_jiffies(outarg.attr_valid,
+					     outarg.attr_valid_nsec);
+	}
+
+	*inodep = inode;
+	return 0;
+}
+
+static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
+				   struct nameidata *nd)
+{
+	struct inode *inode;
+	int err = fuse_lookup_iget(dir, entry, &inode);
+	if (err)
+		return ERR_PTR(err);
+	return d_splice_alias(inode, entry);
+}
+
+static struct inode_operations fuse_dir_inode_operations = {
+	.lookup		= fuse_lookup,
+};
--- linux-2.6.10-rc2/fs/fuse/fuse_i.h	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.10-rc2-fuse/fs/fuse/fuse_i.h	2004-11-20 22:56:25.000000000 +0100
@@ -0,0 +1,216 @@
+/*
+    FUSE: Filesystem in Userspace
+    Copyright (C) 2001-2004  Miklos Szeredi <miklos@szeredi.hu>
+
+    This program can be distributed under the terms of the GNU GPL.
+    See the file COPYING.
+*/
+
+
+#include <linux/fuse.h>
+#include <linux/fs.h>
+#include <linux/wait.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <asm/semaphore.h>
+
+/* If more requests are outstanding, then the operation will block */
+#define FUSE_MAX_OUTSTANDING 10
+
+/** FUSE specific inode data */
+struct fuse_inode {
+	unsigned long nodeid;
+	struct fuse_req *forget_req;
+	unsigned long i_time;
+};
+
+/** One input argument of a request */
+struct fuse_in_arg {
+	unsigned int size;
+	const void *value;
+};
+
+/** The request input */
+struct fuse_in {
+	struct fuse_in_header h;
+	unsigned int numargs;
+	struct fuse_in_arg args[3];
+};
+
+/** One output argument of a request */
+struct fuse_out_arg {
+	unsigned int size;
+	void *value;
+};
+
+/** The request output */
+struct fuse_out {
+	struct fuse_out_header h;
+	unsigned int argvar;
+	unsigned int numargs;
+	struct fuse_out_arg args[3];
+};
+
+struct fuse_req;
+struct fuse_conn;
+
+/**
+ * A request to the client
+ */
+struct fuse_req {
+	/** The request list */
+	struct list_head list;
+
+	/** True if the request has reply */
+	unsigned int isreply:1;
+
+	/* The request is preallocated */
+	unsigned int preallocated:1;
+
+	/* The request is finished */
+	unsigned int finished;
+
+	/** The request input */
+	struct fuse_in in;
+
+	/** The request output */
+	struct fuse_out out;
+
+	/** Used to wake up the task waiting for completion of request*/
+	wait_queue_head_t waitq;
+
+	/** Data for asynchronous requests */
+	union {
+		struct fuse_forget_in forget_in;
+	} misc;
+};
+
+/**
+ * A Fuse connection.
+ *
+ * This structure is created, when the client device is opened, and is
+ * destroyed, when the client device is closed _and_ the filesystem is
+ * unmounted.
+ */
+struct fuse_conn {
+	/** The superblock of the mounted filesystem */
+	struct super_block *sb;
+	
+	/** The opened client device */
+	struct file *file;
+
+	/** The user id for this mount */
+	uid_t uid;
+
+	/** Readers of the connection are waiting on this */
+	wait_queue_head_t waitq;
+
+	/** The list of pending requests */
+	struct list_head pending;
+
+	/** The list of requests being processed */
+	struct list_head processing;
+
+	/** Controls the maximum number of outstanding requests */
+	struct semaphore unused_sem;
+
+	/** The list of unused requests */
+	struct list_head unused_list;
+	
+	/** The next unique request id */
+	int reqctr;
+};
+
+#define SB_FC(sb) ((sb)->s_fs_info)
+#define INO_FC(inode) SB_FC((inode)->i_sb)
+#define INO_FI(i) ((struct fuse_inode *) (((struct inode *)(i))+1))
+
+/** Device operations */
+extern struct file_operations fuse_dev_operations;
+
+/**
+ * This is the single global spinlock which protects FUSE's structures
+ *
+ * The following data is protected by this lock:
+ * 
+ *  - the private_data field of the device file
+ *  - the s_fs_info field of the super block
+ *  - unused_list, pending, processing lists in fuse_conn
+ *  - the unique request ID counter reqctr in fuse_conn
+ *  - the sb (super_block) field in fuse_conn
+ *  - the file (device file) field in fuse_conn
+ */
+extern spinlock_t fuse_lock;
+
+/**
+ * Get a filled in inode
+ */
+struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
+			int generation, struct fuse_attr *attr, int version);
+
+/**
+ * Send FORGET command
+ */
+void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
+		      unsigned long nodeid, int version);
+
+/**
+ * Check if the connection can be released, and if yes, then free the
+ * connection structure
+ */
+void fuse_release_conn(struct fuse_conn *fc);
+
+/**
+ * Initialize the client device
+ */
+int fuse_dev_init(void);
+
+/**
+ * Cleanup the client device
+ */
+void fuse_dev_cleanup(void);
+
+/**
+ * Initialize the fuse filesystem 
+ */
+int fuse_fs_init(void);
+
+/**
+ * Cleanup the fuse filesystem
+ */
+void fuse_fs_cleanup(void);
+
+/** 
+ * Allocate a request
+ */
+struct fuse_req *fuse_request_alloc(void);
+
+/**
+ * Free a request
+ */
+void fuse_request_free(struct fuse_req *req);
+
+/**
+ * Reinitialize a request, the preallocated flag is left unmodified
+ */
+void fuse_reset_request(struct fuse_req *req);
+
+/**
+ * Reserve a preallocated request
+ */
+struct fuse_req *fuse_get_request(struct fuse_conn *fc);
+
+/**
+ * Free a request
+ */
+void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
+
+/**
+ * Send a request
+ */
+void request_send(struct fuse_conn *fc, struct fuse_req *req);
+
+/**
+ * Send a request for which a reply is not expected
+ */
+void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
--- linux-2.6.10-rc2/fs/fuse/inode.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.10-rc2-fuse/fs/fuse/inode.c	2004-11-20 22:56:25.000000000 +0100
@@ -0,0 +1,361 @@
+/*
+    FUSE: Filesystem in Userspace
+    Copyright (C) 2001-2004  Miklos Szeredi <miklos@szeredi.hu>
+
+    This program can be distributed under the terms of the GNU GPL.
+    See the file COPYING.
+*/
+
+#include "fuse_i.h"
+
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/mount.h>
+#include <linux/seq_file.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/parser.h>
+
+static kmem_cache_t *fuse_inode_cachep;
+
+#define FUSE_SUPER_MAGIC 0x65735546
+
+struct fuse_mount_data {
+	int fd;
+	unsigned int rootmode;
+	unsigned int uid;
+};
+
+static struct inode *fuse_alloc_inode(struct super_block *sb)
+{
+	struct inode *inode;
+	struct fuse_inode *fi;
+
+	inode = kmem_cache_alloc(fuse_inode_cachep, SLAB_KERNEL);
+	if (!inode)
+		return NULL;
+
+
+	fi = INO_FI(inode);
+	memset(fi, 0, sizeof(*fi));
+	fi->forget_req = fuse_request_alloc();
+	if (!fi->forget_req) {
+		kmem_cache_free(fuse_inode_cachep, inode);
+		return NULL;
+	}
+	return inode;
+}
+
+static void fuse_destroy_inode(struct inode *inode)
+{
+	struct fuse_inode *fi = INO_FI(inode);
+	if (fi->forget_req)
+		fuse_request_free(fi->forget_req);
+	kmem_cache_free(fuse_inode_cachep, inode);
+}
+
+static void fuse_read_inode(struct inode *inode)
+{
+	/* No op */
+}
+
+void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
+		      unsigned long nodeid, int version)
+{
+	struct fuse_forget_in *inarg = &req->misc.forget_in;
+	inarg->version = version;
+	req->in.h.opcode = FUSE_FORGET;
+	req->in.h.nodeid = nodeid;
+	req->in.numargs = 1;
+	req->in.args[0].size = sizeof(struct fuse_forget_in);
+	req->in.args[0].value = inarg;
+	request_send_noreply(fc, req);
+}
+
+static void fuse_clear_inode(struct inode *inode)
+{
+	struct fuse_conn *fc = INO_FC(inode);
+	
+	if (fc) {
+		struct fuse_inode *fi = INO_FI(inode);
+		fuse_send_forget(fc, fi->forget_req, fi->nodeid, inode->i_version);
+		fi->forget_req = NULL;
+	}
+}
+
+static void fuse_put_super(struct super_block *sb)
+{
+	struct fuse_conn *fc = SB_FC(sb);
+
+	spin_lock(&fuse_lock);
+	fc->sb = NULL;
+	fc->uid = 0;
+	/* Flush all readers on this fs */
+	wake_up_all(&fc->waitq);
+	fuse_release_conn(fc);
+	SB_FC(sb) = NULL;
+	spin_unlock(&fuse_lock);
+}
+
+enum {
+	OPT_FD,
+	OPT_ROOTMODE,
+	OPT_UID,
+	OPT_ERR 
+};
+
+static match_table_t tokens = {
+	{OPT_FD,			"fd=%u"},
+	{OPT_ROOTMODE,			"rootmode=%o"},
+	{OPT_UID,			"uid=%u"},
+	{OPT_ERR,			NULL}
+};
+
+static int parse_fuse_opt(char *opt, struct fuse_mount_data *d)
+{
+	char *p;
+	memset(d, 0, sizeof(struct fuse_mount_data));
+	d->fd = -1;
+
+	while ((p = strsep(&opt, ",")) != NULL) {
+		int token;
+		int value;
+		substring_t args[MAX_OPT_ARGS];
+		if (!*p)
+			continue;
+		
+		token = match_token(p, tokens, args);
+		switch (token) {
+		case OPT_FD:
+			if (match_int(&args[0], &value))
+				return 0;
+			d->fd = value;
+			break;
+
+		case OPT_ROOTMODE:
+			if (match_octal(&args[0], &value))
+				return 0;
+			d->rootmode = value;
+			break;
+			
+		case OPT_UID:
+			if (match_int(&args[0], &value))
+				return 0;
+			d->uid = value;
+			break;
+			
+		default:
+			return 0;
+		}
+	}
+	if (d->fd == -1)
+		return 0;
+
+	return 1;
+}
+
+static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
+{
+	struct fuse_conn *fc = SB_FC(mnt->mnt_sb);
+
+	seq_printf(m, ",uid=%u", fc->uid);
+	return 0;
+}
+
+static void free_conn(struct fuse_conn *fc)
+{
+	while (!list_empty(&fc->unused_list)) {
+		struct fuse_req *req;
+		req = list_entry(fc->unused_list.next, struct fuse_req, list);
+		list_del(&req->list);
+		fuse_request_free(req);
+	}
+	kfree(fc);
+}
+
+/* Must be called with the fuse lock held */
+void fuse_release_conn(struct fuse_conn *fc)
+{
+	if (!fc->sb && !fc->file)
+		free_conn(fc);
+}
+
+static struct fuse_conn *new_conn(void)
+{
+	struct fuse_conn *fc;
+
+	fc = kmalloc(sizeof(*fc), GFP_KERNEL);
+	if (fc != NULL) {
+		int i;
+		memset(fc, 0, sizeof(*fc));
+		fc->sb = NULL;
+		fc->file = NULL;
+		fc->uid = 0;
+		init_waitqueue_head(&fc->waitq);
+		INIT_LIST_HEAD(&fc->pending);
+		INIT_LIST_HEAD(&fc->processing);
+		INIT_LIST_HEAD(&fc->unused_list);
+		sema_init(&fc->unused_sem, FUSE_MAX_OUTSTANDING);
+		for (i = 0; i < FUSE_MAX_OUTSTANDING; i++) {
+			struct fuse_req *req = fuse_request_alloc();
+			if (!req) {
+				free_conn(fc);
+				return NULL;
+			}
+			req->preallocated = 1;
+			list_add(&req->list, &fc->unused_list);
+		}
+		fc->reqctr = 1;
+	}
+	return fc;
+}
+
+static struct fuse_conn *get_conn(struct file *file, struct super_block *sb)
+{
+	struct fuse_conn *fc;
+
+	if (file->f_op != &fuse_dev_operations) {
+		printk("FUSE: bad communication file descriptor\n");
+		return NULL;
+	}
+	fc = new_conn();
+	if (fc == NULL) {
+		printk("FUSE: failed to allocate connection data\n");
+		return NULL;
+	}
+	spin_lock(&fuse_lock);
+	if (file->private_data) {
+		printk("fuse_read_super: connection already mounted\n");
+		free_conn(fc);
+		fc = NULL;
+	} else {
+		file->private_data = fc;
+		fc->sb = sb;
+		fc->file = file;
+	}
+	spin_unlock(&fuse_lock);
+	return fc;
+}
+
+static struct inode *get_root_inode(struct super_block *sb, unsigned int mode)
+{
+	struct fuse_attr attr;
+	memset(&attr, 0, sizeof(attr));
+
+	attr.mode = mode;
+	attr.ino = FUSE_ROOT_ID;
+	return fuse_iget(sb, 1, 0, &attr, 0);
+}
+
+static struct super_operations fuse_super_operations = {
+	.alloc_inode    = fuse_alloc_inode,
+	.destroy_inode  = fuse_destroy_inode,
+	.read_inode	= fuse_read_inode,
+	.clear_inode	= fuse_clear_inode,
+	.put_super	= fuse_put_super,
+	.show_options	= fuse_show_options,
+};
+
+static int fuse_read_super(struct super_block *sb, void *data, int silent)
+{	
+	struct fuse_conn *fc;
+	struct inode *root;
+	struct fuse_mount_data d;
+	struct file *file;
+
+	if (!parse_fuse_opt((char *) data, &d))
+		return -EINVAL;
+
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+	sb->s_magic = FUSE_SUPER_MAGIC;
+	sb->s_op = &fuse_super_operations;
+	sb->s_maxbytes = MAX_LFS_FILESIZE;
+
+	file = fget(d.fd);
+	if (!file)
+		return -EINVAL;
+
+	fc = get_conn(file, sb);
+	fput(file);
+	if (fc == NULL)
+		return -EINVAL;
+
+	fc->uid = d.uid;
+	
+	SB_FC(sb) = fc;
+
+	root = get_root_inode(sb, d.rootmode);
+	if (root == NULL) {
+		printk("fuse_read_super: failed to get root inode\n");
+		goto err;
+	}
+
+	sb->s_root = d_alloc_root(root);
+	if (!sb->s_root) {
+		iput(root);
+		goto err;
+	}
+
+	return 0;
+
+ err:
+	spin_lock(&fuse_lock);
+	fc->sb = NULL;
+	fuse_release_conn(fc);
+	spin_unlock(&fuse_lock);
+	SB_FC(sb) = NULL;
+	return -EINVAL;
+}
+
+static struct super_block *fuse_get_sb(struct file_system_type *fs_type,
+				       int flags, const char *dev_name,
+				       void *raw_data)
+{
+	return get_sb_nodev(fs_type, flags, raw_data, fuse_read_super);
+}
+
+static struct file_system_type fuse_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "fuse",
+	.get_sb		= fuse_get_sb,
+	.kill_sb	= kill_anon_super,
+};
+
+static void fuse_inode_init_once(void * foo, kmem_cache_t * cachep,
+				 unsigned long flags)
+{
+	struct inode * inode = foo;
+
+	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
+	    SLAB_CTOR_CONSTRUCTOR)
+		inode_init_once(inode);
+}
+
+int fuse_fs_init(void)
+{
+	int err;
+
+	err = register_filesystem(&fuse_fs_type);
+	if (err)
+		printk("fuse: failed to register filesystem\n");
+	else {
+		fuse_inode_cachep = kmem_cache_create("fuse_inode",
+						      sizeof(struct inode) + sizeof(struct fuse_inode) ,
+						      0, SLAB_HWCACHE_ALIGN,
+						      fuse_inode_init_once, NULL);
+		if (!fuse_inode_cachep) {
+			unregister_filesystem(&fuse_fs_type);
+			err = -ENOMEM;
+		}
+	}
+
+	return err;
+}
+
+void fuse_fs_cleanup(void)
+{
+	unregister_filesystem(&fuse_fs_type);
+	kmem_cache_destroy(fuse_inode_cachep);
+}
--- linux-2.6.10-rc2/fs/fuse/util.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.10-rc2-fuse/fs/fuse/util.c	2004-11-20 22:41:18.000000000 +0100
@@ -0,0 +1,53 @@
+/*
+    FUSE: Filesystem in Userspace
+    Copyright (C) 2001-2004  Miklos Szeredi <miklos@szeredi.hu>
+
+    This program can be distributed under the terms of the GNU GPL.
+    See the file COPYING.
+*/
+
+#include "fuse_i.h"
+
+#include <linux/init.h>
+#include <linux/module.h>
+
+MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
+MODULE_DESCRIPTION("Filesystem in Userspace");
+MODULE_LICENSE("GPL");
+
+spinlock_t fuse_lock;
+
+int __init fuse_init(void)
+{
+	int res;
+
+	printk("fuse init (API version %i.%i)\n",
+	       FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
+
+	spin_lock_init(&fuse_lock);
+	res = fuse_fs_init();
+	if (res)
+		goto err;
+	
+	res = fuse_dev_init();
+	if (res)
+		goto err_fs_cleanup;
+	
+	return 0;
+
+  err_fs_cleanup:
+	fuse_fs_cleanup();
+  err:
+	return res;
+}
+
+void __exit fuse_exit(void)
+{
+	printk(KERN_DEBUG "fuse exit\n");
+	
+	fuse_fs_cleanup();
+	fuse_dev_cleanup();
+}
+
+module_init(fuse_init);
+module_exit(fuse_exit);
--- linux-2.6.10-rc2/fs/fuse/Makefile	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.10-rc2-fuse/fs/fuse/Makefile	2004-11-20 22:56:24.000000000 +0100
@@ -0,0 +1,7 @@
+#
+# Makefile for the linux fuse routines.
+#
+
+obj-$(CONFIG_FUSE) += fuse.o
+
+fuse-objs := dev.o dir.o inode.o util.o
--- linux-2.6.10-rc2/include/linux/fuse.h	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.10-rc2-fuse/include/linux/fuse.h	2004-11-20 22:56:25.000000000 +0100
@@ -0,0 +1,103 @@
+/*
+    FUSE: Filesystem in Userspace
+    Copyright (C) 2001-2004  Miklos Szeredi <miklos@szeredi.hu>
+
+    This program can be distributed under the terms of the GNU GPL.
+    See the file COPYING.
+*/
+
+/* This file defines the kernel interface of FUSE */
+
+/** Version number of this interface */
+#define FUSE_KERNEL_VERSION 4
+
+/** Minor version number of this interface */
+#define FUSE_KERNEL_MINOR_VERSION 2
+
+/** The node ID of the root inode */
+#define FUSE_ROOT_ID 1
+
+/** Opening this will yield a new control file */
+#define FUSE_DEV "/dev/fuse"
+
+/** The file containing the version in the form MAJOR.MINOR */
+#define FUSE_VERSION_FILE "/sys/fs/fuse/version"
+
+struct fuse_attr {
+	unsigned long       ino;
+	unsigned int        mode;
+	unsigned int        nlink;
+	unsigned int        uid;
+	unsigned int        gid;
+	unsigned int        rdev;
+	unsigned long long  size;
+	unsigned long       blocks;
+	unsigned long       atime;
+	unsigned long       atimensec;
+	unsigned long       mtime;
+	unsigned long       mtimensec;
+	unsigned long       ctime;
+	unsigned long       ctimensec;
+};
+
+enum fuse_opcode {
+	FUSE_LOOKUP	   = 1,
+	FUSE_FORGET	   = 2,  /* no reply */
+	/* FUSE_GETATTR	   = 3, */
+	/* FUSE_SETATTR	   = 4, */
+	/* FUSE_READLINK   = 5, */
+	/* FUSE_SYMLINK	   = 6, */
+	/* FUSE_GETDIR	   = 7, */
+	/* FUSE_MKNOD	   = 8, */
+	/* FUSE_MKDIR	   = 9, */
+	/* FUSE_UNLINK	   = 10, */
+	/* FUSE_RMDIR	   = 11, */
+	/* FUSE_RENAME	   = 12, */
+	/* FUSE_LINK	   = 13, */
+	/* FUSE_OPEN	   = 14, */
+	/* FUSE_READ	   = 15, */
+	/* FUSE_WRITE	   = 16, */
+	/* FUSE_STATFS	   = 17, */
+	/* FUSE_RELEASE       = 18, */
+	/* FUSE_INVALIDATE    = 19, */
+	/* FUSE_FSYNC         = 20, */
+	/* FUSE_SETXATTR      = 21, */
+	/* FUSE_GETXATTR      = 22, */
+	/* FUSE_LISTXATTR     = 23, */
+	/* FUSE_REMOVEXATTR   = 24, */
+	/* FUSE_FLUSH         = 25, */
+};
+
+/* Conservative buffer size for the client */
+#define FUSE_MAX_IN 8192
+
+#define FUSE_NAME_MAX 1024
+
+struct fuse_entry_out {
+	unsigned long nodeid;      /* Inode ID */
+	unsigned long generation;  /* Inode generation: nodeid:gen must
+                                      be unique for the fs's lifetime */
+	unsigned long entry_valid; /* Cache timeout for the name */
+	unsigned long entry_valid_nsec;
+	unsigned long attr_valid;  /* Cache timeout for the attributes */
+	unsigned long attr_valid_nsec;
+	struct fuse_attr attr;
+};
+
+struct fuse_forget_in {
+	int version;
+};
+
+struct fuse_in_header {
+	int unique;
+	enum fuse_opcode opcode;
+	unsigned long nodeid;
+	unsigned int uid;
+	unsigned int gid;
+	unsigned int pid;
+};
+
+struct fuse_out_header {
+	int unique;
+	int error;
+};

Re: [PATCH 3/13] Filesystem in Userspace

[Diego Calleja]

El Sun, 21 Nov 2004 00:09:37 +0100 Miklos Szeredi <miklos@szeredi.hu>
escribió:

[...]
>     - adds /sys/fs/fuse/version

If FUSE is going to be included in the kernel, would you really need that?
 
If something it's in mainline "kernel version 2.6.56" is enought to describe
what code people are running.

Re: [PATCH 3/13] Filesystem in Userspace

[Miklos Szeredi]

> >     - adds /sys/fs/fuse/version
> 
> If FUSE is going to be included in the kernel, would you really need that?
>  
> If something it's in mainline "kernel version 2.6.56" is enought to describe
> what code people are running.

It's not for people, but for the library.  It's the version of the
userspace-kernel interface.

Miklos

Re: [PATCH 3/13] Filesystem in Userspace

[Arnd Bergmann]

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On Sünndag 21 November 2004 01:34, Miklos Szeredi wrote:
> > If something it's in mainline "kernel version 2.6.56" is enought to describe
> > what code people are running.
> 
> It's not for people, but for the library.  It's the version of the
> userspace-kernel interface.
> 
But once it is integrated, you can no longer make incompatible changes to
the API. You only need to know the difference between each API version
prior to the inclusion and the final version.

If the API gets extended later, any user should be able to deal with the
extension failing on older kernels.

	Arnd <><

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Re: [PATCH 3/13] Filesystem in Userspace

[Miklos Szeredi]

> But once it is integrated, you can no longer make incompatible changes to
> the API.

Yes, generally backward compatibility is a good thing and I shall try
to follow it as far as I can.

However, FUSE is still young (only 3 years old), and I can imagine,
that there will come a time, (not too often) when it's better to break
the API than to carry a lot of compatibility cruft around.  And in
that case the version is very useful.

Also it's useful to distingush the integrated version from the older
standalone versions.

Thanks,
Miklos