fuse: fix race between getattr and write

[firewire-audio.git] / fs / fuse / file.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2006  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/kernel.h>
#include <linux/sched.h>

static const struct file_operations fuse_direct_io_file_operations;

static int fuse_send_open(struct inode *inode, struct file *file, int isdir,
                          struct fuse_open_out *outargp)
{
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_open_in inarg;
        struct fuse_req *req;
        int err;

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

        memset(&inarg, 0, sizeof(inarg));
        inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
        req->in.h.opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
        req->in.h.nodeid = get_node_id(inode);
        req->in.numargs = 1;
        req->in.args[0].size = sizeof(inarg);
        req->in.args[0].value = &inarg;
        req->out.numargs = 1;
        req->out.args[0].size = sizeof(*outargp);
        req->out.args[0].value = outargp;
        request_send(fc, req);
        err = req->out.h.error;
        fuse_put_request(fc, req);

        return err;
}

struct fuse_file *fuse_file_alloc(void)
{
        struct fuse_file *ff;
        ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
        if (ff) {
                ff->reserved_req = fuse_request_alloc();
                if (!ff->reserved_req) {
                        kfree(ff);
                        ff = NULL;
                }
                atomic_set(&ff->count, 0);
        }
        return ff;
}

void fuse_file_free(struct fuse_file *ff)
{
        fuse_request_free(ff->reserved_req);
        kfree(ff);
}

static struct fuse_file *fuse_file_get(struct fuse_file *ff)
{
        atomic_inc(&ff->count);
        return ff;
}

static void fuse_release_end(struct fuse_conn *fc, struct fuse_req *req)
{
        dput(req->dentry);
        mntput(req->vfsmount);
        fuse_put_request(fc, req);
}

static void fuse_file_put(struct fuse_file *ff)
{
        if (atomic_dec_and_test(&ff->count)) {
                struct fuse_req *req = ff->reserved_req;
                struct fuse_conn *fc = get_fuse_conn(req->dentry->d_inode);
                req->end = fuse_release_end;
                request_send_background(fc, req);
                kfree(ff);
        }
}

void fuse_finish_open(struct inode *inode, struct file *file,
                      struct fuse_file *ff, struct fuse_open_out *outarg)
{
        if (outarg->open_flags & FOPEN_DIRECT_IO)
                file->f_op = &fuse_direct_io_file_operations;
        if (!(outarg->open_flags & FOPEN_KEEP_CACHE))
                invalidate_inode_pages2(inode->i_mapping);
        ff->fh = outarg->fh;
        file->private_data = fuse_file_get(ff);
}

int fuse_open_common(struct inode *inode, struct file *file, int isdir)
{
        struct fuse_open_out outarg;
        struct fuse_file *ff;
        int err;

        /* VFS checks this, but only _after_ ->open() */
        if (file->f_flags & O_DIRECT)
                return -EINVAL;

        err = generic_file_open(inode, file);
        if (err)
                return err;

        ff = fuse_file_alloc();
        if (!ff)
                return -ENOMEM;

        err = fuse_send_open(inode, file, isdir, &outarg);
        if (err)
                fuse_file_free(ff);
        else {
                if (isdir)
                        outarg.open_flags &= ~FOPEN_DIRECT_IO;
                fuse_finish_open(inode, file, ff, &outarg);
        }

        return err;
}

void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode)
{
        struct fuse_req *req = ff->reserved_req;
        struct fuse_release_in *inarg = &req->misc.release_in;

        inarg->fh = ff->fh;
        inarg->flags = flags;
        req->in.h.opcode = opcode;
        req->in.h.nodeid = nodeid;
        req->in.numargs = 1;
        req->in.args[0].size = sizeof(struct fuse_release_in);
        req->in.args[0].value = inarg;
}

int fuse_release_common(struct inode *inode, struct file *file, int isdir)
{
        struct fuse_file *ff = file->private_data;
        if (ff) {
                fuse_release_fill(ff, get_node_id(inode), file->f_flags,
                                  isdir ? FUSE_RELEASEDIR : FUSE_RELEASE);

                /* Hold vfsmount and dentry until release is finished */
                ff->reserved_req->vfsmount = mntget(file->f_path.mnt);
                ff->reserved_req->dentry = dget(file->f_path.dentry);
                /*
                 * Normally this will send the RELEASE request,
                 * however if some asynchronous READ or WRITE requests
                 * are outstanding, the sending will be delayed
                 */
                fuse_file_put(ff);
        }

        /* Return value is ignored by VFS */
        return 0;
}

static int fuse_open(struct inode *inode, struct file *file)
{
        return fuse_open_common(inode, file, 0);
}

static int fuse_release(struct inode *inode, struct file *file)
{
        return fuse_release_common(inode, file, 0);
}

/*
 * Scramble the ID space with XTEA, so that the value of the files_struct
 * pointer is not exposed to userspace.
 */
static u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
{
        u32 *k = fc->scramble_key;
        u64 v = (unsigned long) id;
        u32 v0 = v;
        u32 v1 = v >> 32;
        u32 sum = 0;
        int i;

        for (i = 0; i < 32; i++) {
                v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
                sum += 0x9E3779B9;
                v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
        }

        return (u64) v0 + ((u64) v1 << 32);
}

static int fuse_flush(struct file *file, fl_owner_t id)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_file *ff = file->private_data;
        struct fuse_req *req;
        struct fuse_flush_in inarg;
        int err;

        if (is_bad_inode(inode))
                return -EIO;

        if (fc->no_flush)
                return 0;

        req = fuse_get_req_nofail(fc, file);
        memset(&inarg, 0, sizeof(inarg));
        inarg.fh = ff->fh;
        inarg.lock_owner = fuse_lock_owner_id(fc, id);
        req->in.h.opcode = FUSE_FLUSH;
        req->in.h.nodeid = get_node_id(inode);
        req->in.numargs = 1;
        req->in.args[0].size = sizeof(inarg);
        req->in.args[0].value = &inarg;
        req->force = 1;
        request_send(fc, req);
        err = req->out.h.error;
        fuse_put_request(fc, req);
        if (err == -ENOSYS) {
                fc->no_flush = 1;
                err = 0;
        }
        return err;
}

int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
                      int isdir)
{
        struct inode *inode = de->d_inode;
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_file *ff = file->private_data;
        struct fuse_req *req;
        struct fuse_fsync_in inarg;
        int err;

        if (is_bad_inode(inode))
                return -EIO;

        if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir))
                return 0;

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

        memset(&inarg, 0, sizeof(inarg));
        inarg.fh = ff->fh;
        inarg.fsync_flags = datasync ? 1 : 0;
        req->in.h.opcode = isdir ? FUSE_FSYNCDIR : FUSE_FSYNC;
        req->in.h.nodeid = get_node_id(inode);
        req->in.numargs = 1;
        req->in.args[0].size = sizeof(inarg);
        req->in.args[0].value = &inarg;
        request_send(fc, req);
        err = req->out.h.error;
        fuse_put_request(fc, req);
        if (err == -ENOSYS) {
                if (isdir)
                        fc->no_fsyncdir = 1;
                else
                        fc->no_fsync = 1;
                err = 0;
        }
        return err;
}

static int fuse_fsync(struct file *file, struct dentry *de, int datasync)
{
        return fuse_fsync_common(file, de, datasync, 0);
}

void fuse_read_fill(struct fuse_req *req, struct fuse_file *ff,
                    struct inode *inode, loff_t pos, size_t count, int opcode)
{
        struct fuse_read_in *inarg = &req->misc.read_in;

        inarg->fh = ff->fh;
        inarg->offset = pos;
        inarg->size = count;
        req->in.h.opcode = opcode;
        req->in.h.nodeid = get_node_id(inode);
        req->in.numargs = 1;
        req->in.args[0].size = sizeof(struct fuse_read_in);
        req->in.args[0].value = inarg;
        req->out.argpages = 1;
        req->out.argvar = 1;
        req->out.numargs = 1;
        req->out.args[0].size = count;
}

static size_t fuse_send_read(struct fuse_req *req, struct file *file,
                             struct inode *inode, loff_t pos, size_t count)
{
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_file *ff = file->private_data;
        fuse_read_fill(req, ff, inode, pos, count, FUSE_READ);
        request_send(fc, req);
        return req->out.args[0].size;
}

static int fuse_readpage(struct file *file, struct page *page)
{
        struct inode *inode = page->mapping->host;
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_req *req;
        int err;

        err = -EIO;
        if (is_bad_inode(inode))
                goto out;

        req = fuse_get_req(fc);
        err = PTR_ERR(req);
        if (IS_ERR(req))
                goto out;

        req->out.page_zeroing = 1;
        req->num_pages = 1;
        req->pages[0] = page;
        fuse_send_read(req, file, inode, page_offset(page), PAGE_CACHE_SIZE);
        err = req->out.h.error;
        fuse_put_request(fc, req);
        if (!err)
                SetPageUptodate(page);
        fuse_invalidate_attr(inode); /* atime changed */
 out:
        unlock_page(page);
        return err;
}

static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_req *req)
{
        int i;

        fuse_invalidate_attr(req->pages[0]->mapping->host); /* atime changed */

        for (i = 0; i < req->num_pages; i++) {
                struct page *page = req->pages[i];
                if (!req->out.h.error)
                        SetPageUptodate(page);
                else
                        SetPageError(page);
                unlock_page(page);
        }
        if (req->ff)
                fuse_file_put(req->ff);
        fuse_put_request(fc, req);
}

static void fuse_send_readpages(struct fuse_req *req, struct fuse_file *ff,
                                struct inode *inode)
{
        struct fuse_conn *fc = get_fuse_conn(inode);
        loff_t pos = page_offset(req->pages[0]);
        size_t count = req->num_pages << PAGE_CACHE_SHIFT;
        req->out.page_zeroing = 1;
        fuse_read_fill(req, ff, inode, pos, count, FUSE_READ);
        if (fc->async_read) {
                req->ff = fuse_file_get(ff);
                req->end = fuse_readpages_end;
                request_send_background(fc, req);
        } else {
                request_send(fc, req);
                fuse_readpages_end(fc, req);
        }
}

struct fuse_fill_data {
        struct fuse_req *req;
        struct fuse_file *ff;
        struct inode *inode;
};

static int fuse_readpages_fill(void *_data, struct page *page)
{
        struct fuse_fill_data *data = _data;
        struct fuse_req *req = data->req;
        struct inode *inode = data->inode;
        struct fuse_conn *fc = get_fuse_conn(inode);

        if (req->num_pages &&
            (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
             (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
             req->pages[req->num_pages - 1]->index + 1 != page->index)) {
                fuse_send_readpages(req, data->ff, inode);
                data->req = req = fuse_get_req(fc);
                if (IS_ERR(req)) {
                        unlock_page(page);
                        return PTR_ERR(req);
                }
        }
        req->pages[req->num_pages] = page;
        req->num_pages ++;
        return 0;
}

static int fuse_readpages(struct file *file, struct address_space *mapping,
                          struct list_head *pages, unsigned nr_pages)
{
        struct inode *inode = mapping->host;
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_fill_data data;
        int err;

        err = -EIO;
        if (is_bad_inode(inode))
                goto out;

        data.ff = file->private_data;
        data.inode = inode;
        data.req = fuse_get_req(fc);
        err = PTR_ERR(data.req);
        if (IS_ERR(data.req))
                goto out;

        err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
        if (!err) {
                if (data.req->num_pages)
                        fuse_send_readpages(data.req, data.ff, inode);
                else
                        fuse_put_request(fc, data.req);
        }
out:
        return err;
}

static size_t fuse_send_write(struct fuse_req *req, struct file *file,
                              struct inode *inode, loff_t pos, size_t count)
{
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_file *ff = file->private_data;
        struct fuse_write_in inarg;
        struct fuse_write_out outarg;

        memset(&inarg, 0, sizeof(struct fuse_write_in));
        inarg.fh = ff->fh;
        inarg.offset = pos;
        inarg.size = count;
        req->in.h.opcode = FUSE_WRITE;
        req->in.h.nodeid = get_node_id(inode);
        req->in.argpages = 1;
        req->in.numargs = 2;
        req->in.args[0].size = sizeof(struct fuse_write_in);
        req->in.args[0].value = &inarg;
        req->in.args[1].size = count;
        req->out.numargs = 1;
        req->out.args[0].size = sizeof(struct fuse_write_out);
        req->out.args[0].value = &outarg;
        request_send(fc, req);
        return outarg.size;
}

static int fuse_write_begin(struct file *file, struct address_space *mapping,
                        loff_t pos, unsigned len, unsigned flags,
                        struct page **pagep, void **fsdata)
{
        pgoff_t index = pos >> PAGE_CACHE_SHIFT;

        *pagep = __grab_cache_page(mapping, index);
        if (!*pagep)
                return -ENOMEM;
        return 0;
}

static int fuse_buffered_write(struct file *file, struct inode *inode,
                               loff_t pos, unsigned count, struct page *page)
{
        int err;
        size_t nres;
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_inode *fi = get_fuse_inode(inode);
        unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
        struct fuse_req *req;

        if (is_bad_inode(inode))
                return -EIO;

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

        req->num_pages = 1;
        req->pages[0] = page;
        req->page_offset = offset;
        nres = fuse_send_write(req, file, inode, pos, count);
        err = req->out.h.error;
        fuse_put_request(fc, req);
        if (!err && !nres)
                err = -EIO;
        if (!err) {
                pos += nres;
                spin_lock(&fc->lock);
                fi->attr_version = ++fc->attr_version;
                if (pos > inode->i_size)
                        i_size_write(inode, pos);
                spin_unlock(&fc->lock);

                if (count == PAGE_CACHE_SIZE)
                        SetPageUptodate(page);
        }
        fuse_invalidate_attr(inode);
        return err ? err : nres;
}

static int fuse_write_end(struct file *file, struct address_space *mapping,
                        loff_t pos, unsigned len, unsigned copied,
                        struct page *page, void *fsdata)
{
        struct inode *inode = mapping->host;
        int res = 0;

        if (copied)
                res = fuse_buffered_write(file, inode, pos, copied, page);

        unlock_page(page);
        page_cache_release(page);
        return res;
}

static void fuse_release_user_pages(struct fuse_req *req, int write)
{
        unsigned i;

        for (i = 0; i < req->num_pages; i++) {
                struct page *page = req->pages[i];
                if (write)
                        set_page_dirty_lock(page);
                put_page(page);
        }
}

static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
                               unsigned nbytes, int write)
{
        unsigned long user_addr = (unsigned long) buf;
        unsigned offset = user_addr & ~PAGE_MASK;
        int npages;

        /* This doesn't work with nfsd */
        if (!current->mm)
                return -EPERM;

        nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
        npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
        npages = min(max(npages, 1), FUSE_MAX_PAGES_PER_REQ);
        down_read(&current->mm->mmap_sem);
        npages = get_user_pages(current, current->mm, user_addr, npages, write,
                                0, req->pages, NULL);
        up_read(&current->mm->mmap_sem);
        if (npages < 0)
                return npages;

        req->num_pages = npages;
        req->page_offset = offset;
        return 0;
}

static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
                              size_t count, loff_t *ppos, int write)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        struct fuse_conn *fc = get_fuse_conn(inode);
        size_t nmax = write ? fc->max_write : fc->max_read;
        loff_t pos = *ppos;
        ssize_t res = 0;
        struct fuse_req *req;

        if (is_bad_inode(inode))
                return -EIO;

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

        while (count) {
                size_t nres;
                size_t nbytes = min(count, nmax);
                int err = fuse_get_user_pages(req, buf, nbytes, !write);
                if (err) {
                        res = err;
                        break;
                }
                nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset;
                nbytes = min(count, nbytes);
                if (write)
                        nres = fuse_send_write(req, file, inode, pos, nbytes);
                else
                        nres = fuse_send_read(req, file, inode, pos, nbytes);
                fuse_release_user_pages(req, !write);
                if (req->out.h.error) {
                        if (!res)
                                res = req->out.h.error;
                        break;
                } else if (nres > nbytes) {
                        res = -EIO;
                        break;
                }
                count -= nres;
                res += nres;
                pos += nres;
                buf += nres;
                if (nres != nbytes)
                        break;
                if (count) {
                        fuse_put_request(fc, req);
                        req = fuse_get_req(fc);
                        if (IS_ERR(req))
                                break;
                }
        }
        fuse_put_request(fc, req);
        if (res > 0) {
                if (write) {
                        spin_lock(&fc->lock);
                        if (pos > inode->i_size)
                                i_size_write(inode, pos);
                        spin_unlock(&fc->lock);
                }
                *ppos = pos;
        }
        fuse_invalidate_attr(inode);

        return res;
}

static ssize_t fuse_direct_read(struct file *file, char __user *buf,
                                     size_t count, loff_t *ppos)
{
        return fuse_direct_io(file, buf, count, ppos, 0);
}

static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
                                 size_t count, loff_t *ppos)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        ssize_t res;
        /* Don't allow parallel writes to the same file */
        mutex_lock(&inode->i_mutex);
        res = generic_write_checks(file, ppos, &count, 0);
        if (!res)
                res = fuse_direct_io(file, buf, count, ppos, 1);
        mutex_unlock(&inode->i_mutex);
        return res;
}

static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
{
        if ((vma->vm_flags & VM_SHARED)) {
                if ((vma->vm_flags & VM_WRITE))
                        return -ENODEV;
                else
                        vma->vm_flags &= ~VM_MAYWRITE;
        }
        return generic_file_mmap(file, vma);
}

static int fuse_set_page_dirty(struct page *page)
{
        printk("fuse_set_page_dirty: should not happen\n");
        dump_stack();
        return 0;
}

static int convert_fuse_file_lock(const struct fuse_file_lock *ffl,
                                  struct file_lock *fl)
{
        switch (ffl->type) {
        case F_UNLCK:
                break;

        case F_RDLCK:
        case F_WRLCK:
                if (ffl->start > OFFSET_MAX || ffl->end > OFFSET_MAX ||
                    ffl->end < ffl->start)
                        return -EIO;

                fl->fl_start = ffl->start;
                fl->fl_end = ffl->end;
                fl->fl_pid = ffl->pid;
                break;

        default:
                return -EIO;
        }
        fl->fl_type = ffl->type;
        return 0;
}

static void fuse_lk_fill(struct fuse_req *req, struct file *file,
                         const struct file_lock *fl, int opcode, pid_t pid)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_file *ff = file->private_data;
        struct fuse_lk_in *arg = &req->misc.lk_in;

        arg->fh = ff->fh;
        arg->owner = fuse_lock_owner_id(fc, fl->fl_owner);
        arg->lk.start = fl->fl_start;
        arg->lk.end = fl->fl_end;
        arg->lk.type = fl->fl_type;
        arg->lk.pid = pid;
        req->in.h.opcode = opcode;
        req->in.h.nodeid = get_node_id(inode);
        req->in.numargs = 1;
        req->in.args[0].size = sizeof(*arg);
        req->in.args[0].value = arg;
}

static int fuse_getlk(struct file *file, struct file_lock *fl)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_req *req;
        struct fuse_lk_out outarg;
        int err;

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

        fuse_lk_fill(req, file, fl, FUSE_GETLK, 0);
        req->out.numargs = 1;
        req->out.args[0].size = sizeof(outarg);
        req->out.args[0].value = &outarg;
        request_send(fc, req);
        err = req->out.h.error;
        fuse_put_request(fc, req);
        if (!err)
                err = convert_fuse_file_lock(&outarg.lk, fl);

        return err;
}

static int fuse_setlk(struct file *file, struct file_lock *fl)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_req *req;
        int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
        pid_t pid = fl->fl_type != F_UNLCK ? current->tgid : 0;
        int err;

        /* Unlock on close is handled by the flush method */
        if (fl->fl_flags & FL_CLOSE)
                return 0;

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

        fuse_lk_fill(req, file, fl, opcode, pid);
        request_send(fc, req);
        err = req->out.h.error;
        /* locking is restartable */
        if (err == -EINTR)
                err = -ERESTARTSYS;
        fuse_put_request(fc, req);
        return err;
}

static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        struct fuse_conn *fc = get_fuse_conn(inode);
        int err;

        if (cmd == F_GETLK) {
                if (fc->no_lock) {
                        posix_test_lock(file, fl);
                        err = 0;
                } else
                        err = fuse_getlk(file, fl);
        } else {
                if (fc->no_lock)
                        err = posix_lock_file_wait(file, fl);
                else
                        err = fuse_setlk(file, fl);
        }
        return err;
}

static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
{
        struct inode *inode = mapping->host;
        struct fuse_conn *fc = get_fuse_conn(inode);
        struct fuse_req *req;
        struct fuse_bmap_in inarg;
        struct fuse_bmap_out outarg;
        int err;

        if (!inode->i_sb->s_bdev || fc->no_bmap)
                return 0;

        req = fuse_get_req(fc);
        if (IS_ERR(req))
                return 0;

        memset(&inarg, 0, sizeof(inarg));
        inarg.block = block;
        inarg.blocksize = inode->i_sb->s_blocksize;
        req->in.h.opcode = FUSE_BMAP;
        req->in.h.nodeid = get_node_id(inode);
        req->in.numargs = 1;
        req->in.args[0].size = sizeof(inarg);
        req->in.args[0].value = &inarg;
        req->out.numargs = 1;
        req->out.args[0].size = sizeof(outarg);
        req->out.args[0].value = &outarg;
        request_send(fc, req);
        err = req->out.h.error;
        fuse_put_request(fc, req);
        if (err == -ENOSYS)
                fc->no_bmap = 1;

        return err ? 0 : outarg.block;
}

static const struct file_operations fuse_file_operations = {
        .llseek         = generic_file_llseek,
        .read           = do_sync_read,
        .aio_read       = generic_file_aio_read,
        .write          = do_sync_write,
        .aio_write      = generic_file_aio_write,
        .mmap           = fuse_file_mmap,
        .open           = fuse_open,
        .flush          = fuse_flush,
        .release        = fuse_release,
        .fsync          = fuse_fsync,
        .lock           = fuse_file_lock,
        .splice_read    = generic_file_splice_read,
};

static const struct file_operations fuse_direct_io_file_operations = {
        .llseek         = generic_file_llseek,
        .read           = fuse_direct_read,
        .write          = fuse_direct_write,
        .open           = fuse_open,
        .flush          = fuse_flush,
        .release        = fuse_release,
        .fsync          = fuse_fsync,
        .lock           = fuse_file_lock,
        /* no mmap and splice_read */
};

static const struct address_space_operations fuse_file_aops  = {
        .readpage       = fuse_readpage,
        .write_begin    = fuse_write_begin,
        .write_end      = fuse_write_end,
        .readpages      = fuse_readpages,
        .set_page_dirty = fuse_set_page_dirty,
        .bmap           = fuse_bmap,
};

void fuse_init_file_inode(struct inode *inode)
{
        inode->i_fop = &fuse_file_operations;
        inode->i_data.a_ops = &fuse_file_aops;
}