[PATCH 2/11] FUSE - core

From: Miklos Szeredi (miklos_at_szeredi.hu)
Date: 01/11/05

  • Next message: Miklos Szeredi: "[PATCH 3/11] FUSE - device functions" 
    To: akpm@osdl.org, torvalds@osdl.org
Date:	Tue, 11 Jan 2005 17:25:07 +0100

    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@szeredi.hu>
    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 2005-01-11 16:28:29.000000000 +0100
    @@ -0,0 +1,7 @@
    +#
    +# Makefile for the FUSE filesystem.
    +#
    +
    +obj-$(CONFIG_FUSE_FS) += 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 2005-01-11 16:28:29.000000000 +0100
    @@ -0,0 +1,89 @@
    +/*
    + FUSE: Filesystem in Userspace
    + Copyright (C) 2001-2005 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 <linux/mm.h>
    +#include <linux/backing-dev.h>
    +#include <asm/semaphore.h>
    +
    +/** FUSE inode */
    +struct fuse_inode {
    + /** Inode data */
    + struct inode 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 container_of(inode, struct fuse_inode, inode);
    +}
    +
    +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 s_fs_info field of the super block
    + * - the sb (super_block) 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 2005-01-11 16:28:29.000000000 +0100
    @@ -0,0 +1,428 @@
    +/*
    + FUSE: Filesystem in Userspace
    + Copyright (C) 2001-2005 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/init.h>
    +#include <linux/module.h>
    +#include <linux/moduleparam.h>
    +#include <linux/parser.h>
    +#include <linux/statfs.h>
    +
    +MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
    +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);
    + fi->i_time = jiffies - 1;
    + fi->nodeid = 0;
    +
    + 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_fill_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_fill_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 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);
    +}
    +
    +static 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;
    +}
    +
    +static 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 2005-01-11 16:28:29.000000000 +0100
    @@ -0,0 +1,38 @@
    +/*
    + FUSE: Filesystem in Userspace
    + Copyright (C) 2001-2005 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 */
    +
    +#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;
    +};
    +
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  • Next message: Miklos Szeredi: "[PATCH 3/11] FUSE - device functions"

    Relevant Pages

    • [PATCH 3/13] Filesystem in Userspace
      ... This patch adds FUSE core. ... +static void request_wait_answer ... +static int fuse_dev_release(struct inode *inode, ...
      (Linux-Kernel)
    • [PATCH 2/11] FUSE - core
      ... This patch adds FUSE core. ... +# Makefile for the FUSE filesystem. ... +struct fuse_inode { ... +static inline u64 get_node_id(struct inode *inode) ...
      (Linux-Kernel)
    • [RFC][PATCH] VFS: update documentation (take #2)
      ... filesystem interface to userspace programs. ... These are taken from the inode data. ... owner: for internal VFS use: you should initialize this to NULL ... struct super_block *sb: the superblock structure. ...
      (Linux-Kernel)
    • [RFC] LogFS
      ... I've been hacking on a small filesystem. ... +This filesystem started with the codename "Logfs", ... +struct logfs_disk_super { ... +static inline void logfs_iput(struct inode *inode) ...
      (Linux-Kernel)
    • Re: [RFC] [PATCH 1/8] inode_diet: Replace inode.u.generic_ip with inode.i_private
      ... struct inode i_inode; ... although I'm not sure that it would be as significant as the memory ... What you do gain though is (on umount of a filesystem) a much greater ...
      (Linux-Kernel)