inode.c

linux 内核源代码

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2006  Miklos Szeredi <[e-mail]>

  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/seq_file.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/parser.h>
#include <linux/statfs.h>
#include <linux/random.h>
#include <linux/sched.h>

MODULE_AUTHOR("Miklos Szeredi <[e-mail]>");
MODULE_DESCRIPTION("Filesystem in Userspace");
MODULE_LICENSE("GPL");

static struct kmem_cache *fuse_inode_cachep;
struct list_head fuse_conn_list;
DEFINE_MUTEX(fuse_mutex);

#define FUSE_SUPER_MAGIC 0x65735546

struct fuse_mount_data {
	int fd;
	unsigned rootmode;
	unsigned user_id;
	unsigned group_id;
	unsigned fd_present : 1;
	unsigned rootmode_present : 1;
	unsigned user_id_present : 1;
	unsigned group_id_present : 1;
	unsigned flags;
	unsigned max_read;
	unsigned blksize;
};

static struct inode *fuse_alloc_inode(struct super_block *sb)
{
	struct inode *inode;
	struct fuse_inode *fi;

	inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
	if (!inode)
		return NULL;

	fi = get_fuse_inode(inode);
	fi->i_time = 0;
	fi->nodeid = 0;
	fi->nlookup = 0;
	fi->attr_version = 0;
	INIT_LIST_HEAD(&fi->write_files);
	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 = get_fuse_inode(inode);
	BUG_ON(!list_empty(&fi->write_files));
	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, u64 nlookup)
{
	struct fuse_forget_in *inarg = &req->misc.forget_in;
	inarg->nlookup = nlookup;
	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)
{
	if (inode->i_sb->s_flags & MS_ACTIVE) {
		struct fuse_conn *fc = get_fuse_conn(inode);
		struct fuse_inode *fi = get_fuse_inode(inode);
		fuse_send_forget(fc, fi->forget_req, fi->nodeid, fi->nlookup);
		fi->forget_req = NULL;
	}
}

static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
{
	if (*flags & MS_MANDLOCK)
		return -EINVAL;

	return 0;
}

static void fuse_truncate(struct address_space *mapping, loff_t offset)
{
	/* See vmtruncate() */
	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
	truncate_inode_pages(mapping, offset);
	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
}


void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
			    u64 attr_valid, u64 attr_version)
{
	struct fuse_conn *fc = get_fuse_conn(inode);
	struct fuse_inode *fi = get_fuse_inode(inode);
	loff_t oldsize;

	spin_lock(&fc->lock);
	if (attr_version != 0 && fi->attr_version > attr_version) {
		spin_unlock(&fc->lock);
		return;
	}
	fi->attr_version = ++fc->attr_version;
	fi->i_time = attr_valid;

	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;
	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;

	if (attr->blksize != 0)
		inode->i_blkbits = ilog2(attr->blksize);
	else
		inode->i_blkbits = inode->i_sb->s_blocksize_bits;

	/*
	 * Don't set the sticky bit in i_mode, unless we want the VFS
	 * to check permissions.  This prevents failures due to the
	 * check in may_delete().
	 */
	fi->orig_i_mode = inode->i_mode;
	if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
		inode->i_mode &= ~S_ISVTX;

	oldsize = inode->i_size;
	i_size_write(inode, attr->size);
	spin_unlock(&fc->lock);

	if (S_ISREG(inode->i_mode) && oldsize != attr->size) {
		if (attr->size < oldsize)
			fuse_truncate(inode->i_mapping, attr->size);
		invalidate_inode_pages2(inode->i_mapping);
	}
}

static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
{
	inode->i_mode = attr->mode & S_IFMT;
	inode->i_size = attr->size;
	if (S_ISREG(inode->i_mode)) {
		fuse_init_common(inode);
		fuse_init_file_inode(inode);
	} else if (S_ISDIR(inode->i_mode))
		fuse_init_dir(inode);
	else if (S_ISLNK(inode->i_mode))
		fuse_init_symlink(inode);
	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
		 S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
		fuse_init_common(inode);
		init_special_inode(inode, inode->i_mode,
				   new_decode_dev(attr->rdev));
	} else
		BUG();
}

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,
			u64 attr_valid, u64 attr_version)
{
	struct inode *inode;
	struct fuse_inode *fi;
	struct fuse_conn *fc = get_fuse_conn_super(sb);

 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_flags |= S_NOATIME|S_NOCMTIME;
		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) {
		/* Inode has changed type, any I/O on the old should fail */
		make_bad_inode(inode);
		iput(inode);
		goto retry;
	}

	fi = get_fuse_inode(inode);
	spin_lock(&fc->lock);
	fi->nlookup ++;
	spin_unlock(&fc->lock);
	fuse_change_attributes(inode, attr, attr_valid, attr_version);

	return inode;
}

static void fuse_umount_begin(struct vfsmount *vfsmnt, int flags)
{
	if (flags & MNT_FORCE)
		fuse_abort_conn(get_fuse_conn_super(vfsmnt->mnt_sb));
}

static void fuse_send_destroy(struct fuse_conn *fc)
{
	struct fuse_req *req = fc->destroy_req;
	if (req && fc->conn_init) {
		fc->destroy_req = NULL;
		req->in.h.opcode = FUSE_DESTROY;
		req->force = 1;
		request_send(fc, req);
		fuse_put_request(fc, req);
	}
}

static void fuse_put_super(struct super_block *sb)
{
	struct fuse_conn *fc = get_fuse_conn_super(sb);

	fuse_send_destroy(fc);
	spin_lock(&fc->lock);
	fc->connected = 0;
	fc->blocked = 0;
	spin_unlock(&fc->lock);
	/* Flush all readers on this fs */
	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
	wake_up_all(&fc->waitq);
	wake_up_all(&fc->blocked_waitq);
	wake_up_all(&fc->reserved_req_waitq);
	mutex_lock(&fuse_mutex);
	list_del(&fc->entry);
	fuse_ctl_remove_conn(fc);
	mutex_unlock(&fuse_mutex);
	fuse_conn_put(fc);
}

static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
{
	stbuf->f_type    = FUSE_SUPER_MAGIC;
	stbuf->f_bsize   = attr->bsize;
	stbuf->f_frsize  = attr->frsize;
	stbuf->f_blocks  = attr->blocks;
	stbuf->f_bfree   = attr->bfree;
	stbuf->f_bavail  = attr->bavail;
	stbuf->f_files   = attr->files;
	stbuf->f_ffree   = attr->ffree;
	stbuf->f_namelen = attr->namelen;
	/* fsid is left zero */
}

static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
{
	struct super_block *sb = dentry->d_sb;
	struct fuse_conn *fc = get_fuse_conn_super(sb);
	struct fuse_req *req;
	struct fuse_statfs_out outarg;
	int err;

	if (!fuse_allow_task(fc, current)) {
		buf->f_type = FUSE_SUPER_MAGIC;
		return 0;
	}

	req = fuse_get_req(fc);
	if (IS_ERR(req))
		return PTR_ERR(req);

	memset(&outarg, 0, sizeof(outarg));
	req->in.numargs = 0;
	req->in.h.opcode = FUSE_STATFS;
	req->in.h.nodeid = get_node_id(dentry->d_inode);
	req->out.numargs = 1;
	req->out.args[0].size =
		fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg);
	req->out.args[0].value = &outarg;
	request_send(fc, req);
	err = req->out.h.error;
	if (!err)
		convert_fuse_statfs(buf, &outarg.st);
	fuse_put_request(fc, req);
	return err;
}

enum {
	OPT_FD,
	OPT_ROOTMODE,
	OPT_USER_ID,
	OPT_GROUP_ID,
	OPT_DEFAULT_PERMISSIONS,
	OPT_ALLOW_OTHER,
	OPT_MAX_READ,
	OPT_BLKSIZE,
	OPT_ERR
};

static match_table_t tokens = {
	{OPT_FD,			"fd=%u"},
	{OPT_ROOTMODE,			"rootmode=%o"},
	{OPT_USER_ID,			"user_id=%u"},
	{OPT_GROUP_ID,			"group_id=%u"},
	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},
	{OPT_ALLOW_OTHER,		"allow_other"},
	{OPT_MAX_READ,			"max_read=%u"},
	{OPT_BLKSIZE,			"blksize=%u"},
	{OPT_ERR,			NULL}
};

static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
{
	char *p;
	memset(d, 0, sizeof(struct fuse_mount_data));
	d->max_read = ~0;
	d->blksize = 512;

	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;
			d->fd_present = 1;
			break;

		case OPT_ROOTMODE:
			if (match_octal(&args[0], &value))
				return 0;
			if (!fuse_valid_type(value))
				return 0;
			d->rootmode = value;
			d->rootmode_present = 1;
			break;

		case OPT_USER_ID:
			if (match_int(&args[0], &value))
				return 0;
			d->user_id = value;
			d->user_id_present = 1;
			break;

		case OPT_GROUP_ID:
			if (match_int(&args[0], &value))
				return 0;
			d->group_id = value;
			d->group_id_present = 1;
			break;

		case OPT_DEFAULT_PERMISSIONS:
			d->flags |= FUSE_DEFAULT_PERMISSIONS;
			break;

		case OPT_ALLOW_OTHER:
			d->flags |= FUSE_ALLOW_OTHER;
			break;

		case OPT_MAX_READ:
			if (match_int(&args[0], &value))
				return 0;
			d->max_read = value;
			break;

		case OPT_BLKSIZE:
			if (!is_bdev || match_int(&args[0], &value))
				return 0;
			d->blksize = value;
			break;

		default:
			return 0;
		}
	}

	if (!d->fd_present || !d->rootmode_present ||
	    !d->user_id_present || !d->group_id_present)
		return 0;

	return 1;
}