[PATCH 2/11] FUSE - core

[Miklos Szeredi]

This patch adds FUSE core.

This contains the following files:

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

 o fuse_i.h
    - private header file

Signed-off-by: Miklos Szeredi <miklos@xxxxxxxxxx>
diff -Nurp a/fs/fuse/Makefile b/fs/fuse/Makefile
--- a/fs/fuse/Makefile	1970-01-01 01:00:00.000000000 +0100
+++ b/fs/fuse/Makefile	2005-01-10 19:28:38.000000000 +0100
@@ -0,0 +1,7 @@
+#
+# Makefile for the FUSE filesystem.
+#
+
+obj-$(CONFIG_FUSE) += fuse.o
+
+fuse-objs := inode.o
diff -Nurp a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
--- a/fs/fuse/fuse_i.h	1970-01-01 01:00:00.000000000 +0100
+++ b/fs/fuse/fuse_i.h	2005-01-10 19:28:38.000000000 +0100
@@ -0,0 +1,90 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2001-2005  Miklos Szeredi <miklos@xxxxxxxxxx>
+
+  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 <linux/mm.h>
+#include <linux/backing-dev.h>
+#include <asm/semaphore.h>
+
+/** FUSE specific inode data */
+struct fuse_inode {
+	/** Unique ID, which identifies the inode between userspace
+	 * and kernel */
+	u64 nodeid;
+
+	/** Time in jiffies until the file attributes are valid */
+	unsigned long i_time;
+};
+
+/**
+ * A Fuse connection.
+ *
+ * This structure is created, when the filesystem is mounted, 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 user id for this mount */
+	uid_t user_id;
+
+	/** Backing dev info */
+	struct backing_dev_info bdi;
+};
+
+static inline struct fuse_conn **get_fuse_conn_super_p(struct super_block *sb)
+{
+	return (struct fuse_conn **) &sb->s_fs_info;
+}
+
+static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
+{
+	return *get_fuse_conn_super_p(sb);
+}
+
+static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
+{
+	return get_fuse_conn_super(inode->i_sb);
+}
+
+static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
+{
+	return (struct fuse_inode *) (&inode[1]);
+}
+
+static inline u64 get_node_id(struct inode *inode)
+{
+	return get_fuse_inode(inode)->nodeid;
+}
+
+/**
+ * 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;
+
+/**
+ * Check if the connection can be released, and if yes, then free the
+ * connection structure
+ */
+void fuse_release_conn(struct fuse_conn *fc);
+
diff -Nurp a/fs/fuse/inode.c b/fs/fuse/inode.c
--- a/fs/fuse/inode.c	1970-01-01 01:00:00.000000000 +0100
+++ b/fs/fuse/inode.c	2005-01-10 19:28:38.000000000 +0100
@@ -0,0 +1,427 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2001-2005  Miklos Szeredi <miklos@xxxxxxxxxx>
+
+  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/init.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/parser.h>
+#include <linux/statfs.h>
+
+MODULE_AUTHOR("Miklos Szeredi <miklos@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Filesystem in Userspace");
+MODULE_LICENSE("GPL");
+
+spinlock_t fuse_lock;
+static kmem_cache_t *fuse_inode_cachep;
+static int mount_count;
+
+static int mount_max = 1000;
+module_param(mount_max, int, 0644);
+MODULE_PARM_DESC(mount_max, "Maximum number of FUSE mounts allowed, if -1 then unlimited (default: 1000)");
+
+#define FUSE_SUPER_MAGIC 0x65735546
+
+struct fuse_mount_data {
+	int fd;
+	unsigned rootmode;
+	unsigned user_id;
+};
+
+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 = get_fuse_inode(inode);
+	memset(fi, 0, sizeof(*fi));
+
+	return inode;
+}
+
+static void fuse_destroy_inode(struct inode *inode)
+{
+	kmem_cache_free(fuse_inode_cachep, inode);
+}
+
+static void fuse_read_inode(struct inode *inode)
+{
+	/* No op */
+}
+
+static void fuse_clear_inode(struct inode *inode)
+{
+}
+
+void fuse_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);
+}
+
+static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
+{
+	unsigned long nodeid = *(unsigned long *) _nodeidp;
+	if (get_node_id(inode) == nodeid)
+		return 1;
+	else
+		return 0;
+}
+
+static int fuse_inode_set(struct inode *inode, void *_nodeidp)
+{
+	unsigned long nodeid = *(unsigned long *) _nodeidp;
+	get_fuse_inode(inode)->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;
+	struct fuse_conn *fc = get_fuse_conn_super(sb);
+	int retried = 0;
+
+ retry:
+	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;
+		inode->i_data.backing_dev_info = &fc->bdi;
+		fuse_init_inode(inode, attr);
+		unlock_new_inode(inode);
+	} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
+		BUG_ON(retried);
+		/* Inode has changed type, any I/O on the old should fail */
+		make_bad_inode(inode);
+		iput(inode);
+		retried = 1;
+		goto retry;
+	}
+
+	fuse_change_attributes(inode, attr);
+	inode->i_version = version;
+	return inode;
+}
+
+static void fuse_put_super(struct super_block *sb)
+{
+	struct fuse_conn *fc = get_fuse_conn_super(sb);
+
+	spin_lock(&fuse_lock);
+	mount_count --;
+	fc->sb = NULL;
+	fc->user_id = 0;
+	fuse_release_conn(fc);
+	*get_fuse_conn_super_p(sb) = NULL;
+	spin_unlock(&fuse_lock);
+}
+
+enum {
+	OPT_FD,
+	OPT_ROOTMODE,
+	OPT_USER_ID,
+	OPT_DEFAULT_PERMISSIONS,
+	OPT_ALLOW_OTHER,
+	OPT_ALLOW_ROOT,
+	OPT_KERNEL_CACHE,
+	OPT_ERR
+};
+
+static match_table_t tokens = {
+	{OPT_FD,			"fd=%u"},
+	{OPT_ROOTMODE,			"rootmode=%o"},
+	{OPT_USER_ID,			"user_id=%u"},
+	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},
+	{OPT_ALLOW_OTHER,		"allow_other"},
+	{OPT_ALLOW_ROOT,		"allow_root"},
+	{OPT_KERNEL_CACHE,		"kernel_cache"},
+	{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_USER_ID:
+			if (match_int(&args[0], &value))
+				return 0;
+			d->user_id = 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 = get_fuse_conn_super(mnt->mnt_sb);
+
+	seq_printf(m, ",user_id=%u", fc->user_id);
+	return 0;
+}
+
+void fuse_release_conn(struct fuse_conn *fc)
+{
+	kfree(fc);
+}
+
+static struct fuse_conn *new_conn(void)
+{
+	struct fuse_conn *fc;
+
+	fc = kmalloc(sizeof(*fc), GFP_KERNEL);
+	if (fc != NULL) {
+		memset(fc, 0, sizeof(*fc));
+		fc->sb = NULL;
+		fc->user_id = 0;
+		fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
+		fc->bdi.unplug_io_fn = default_unplug_io_fn;
+	}
+	return fc;
+}
+
+static struct fuse_conn *get_conn(struct file *file, struct super_block *sb)
+{
+	struct fuse_conn *fc;
+
+	fc = new_conn();
+	if (fc == NULL)
+		return NULL;
+	spin_lock(&fuse_lock);
+	fc->sb = sb;
+	spin_unlock(&fuse_lock);
+	return fc;
+}
+
+static struct inode *get_root_inode(struct super_block *sb, unsigned 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 inc_mount_count(void)
+{
+	int success = 0;
+	spin_lock(&fuse_lock);
+	mount_count ++;
+	if (mount_max == -1 || mount_count <= mount_max)
+		success = 1;
+	spin_unlock(&fuse_lock);
+	return success;
+}
+
+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;
+	int err;
+
+	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->user_id = d.user_id;
+
+	*get_fuse_conn_super_p(sb) = fc;
+
+	err = -ENFILE;
+	if (!inc_mount_count() && current->uid != 0)
+		goto err;
+
+	err = -ENOMEM;
+	root = get_root_inode(sb, d.rootmode);
+	if (root == NULL)
+		goto err;
+
+	sb->s_root = d_alloc_root(root);
+	if (!sb->s_root) {
+		iput(root);
+		goto err;
+	}
+	return 0;
+
+ err:
+	spin_lock(&fuse_lock);
+	mount_count --;
+	fc->sb = NULL;
+	fuse_release_conn(fc);
+	spin_unlock(&fuse_lock);
+	*get_fuse_conn_super_p(sb) = NULL;
+	return err;
+}
+
+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);
+}
+
+static int __init 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;
+}
+
+static void fuse_fs_cleanup(void)
+{
+	unregister_filesystem(&fuse_fs_type);
+	kmem_cache_destroy(fuse_inode_cachep);
+}
+
+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;
+
+	return 0;
+
+ err:
+	return res;
+}
+
+void __exit fuse_exit(void)
+{
+	printk(KERN_DEBUG "fuse exit\n");
+
+	fuse_fs_cleanup();
+}
+
+module_init(fuse_init);
+module_exit(fuse_exit);
diff -Nurp a/include/linux/fuse.h b/include/linux/fuse.h
--- a/include/linux/fuse.h	1970-01-01 01:00:00.000000000 +0100
+++ b/include/linux/fuse.h	2005-01-10 19:28:38.000000000 +0100
@@ -0,0 +1,38 @@
+/*
+    FUSE: Filesystem in Userspace
+    Copyright (C) 2001-2005  Miklos Szeredi <miklos@xxxxxxxxxx>
+
+    This program can be distributed under the terms of the GNU GPL.
+    See the file COPYING.
+*/
+
+/* This file defines the kernel interface of FUSE */
+
+#include <asm/types.h>
+
+/** Version number of this interface */
+#define FUSE_KERNEL_VERSION 5
+
+/** Minor version number of this interface */
+#define FUSE_KERNEL_MINOR_VERSION 1
+
+/** The node ID of the root inode */
+#define FUSE_ROOT_ID 1
+
+struct fuse_attr {
+	__u64	ino;
+	__u64	size;
+	__u64	blocks;
+	__u64	atime;
+	__u64	mtime;
+	__u64	ctime;
+	__u32	atimensec;
+	__u32	mtimensec;
+	__u32	ctimensec;
+	__u32	mode;
+	__u32	nlink;
+	__u32	uid;
+	__u32	gid;
+	__u32	rdev;
+};
+
-
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