fs/fuse/file.c

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2005  Miklos Szeredi <miklos@szeredi.hu>
   4
   5   This program can be distributed under the terms of the GNU GPL.
   6   See the file COPYING.
   7 */
   8
   9 #include "fuse_i.h"
  10
  11 #include <linux/pagemap.h>
  12 #include <linux/slab.h>
  13 #include <linux/kernel.h>
  14
  15 static int fuse_open(struct inode *inode, struct file *file)
  16 {
  17         struct fuse_conn *fc = get_fuse_conn(inode);
  18         struct fuse_req *req;
  19         struct fuse_open_in inarg;
  20         struct fuse_open_out outarg;
  21         struct fuse_file *ff;
  22         int err;
  23         /* Restarting the syscall is not allowed if O_CREAT and O_EXCL
  24            are both set, because creation will fail on the restart */
  25         int excl = (file->f_flags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL);
  26
  27         err = generic_file_open(inode, file);
  28         if (err)
  29                 return err;
  30
  31         /* If opening the root node, no lookup has been performed on
  32            it, so the attributes must be refreshed */
  33         if (get_node_id(inode) == FUSE_ROOT_ID) {
  34                 int err = fuse_do_getattr(inode);
  35                 if (err)
  36                         return err;
  37         }
  38
  39         if (excl)
  40                 req = fuse_get_request_nonint(fc);
  41         else
  42                 req = fuse_get_request(fc);
  43         if (!req)
  44                 return excl ? -EINTR : -ERESTARTSYS;
  45
  46         err = -ENOMEM;
  47         ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
  48         if (!ff)
  49                 goto out_put_request;
  50
  51         ff->release_req = fuse_request_alloc();
  52         if (!ff->release_req) {
  53                 kfree(ff);
  54                 goto out_put_request;
  55         }
  56
  57         memset(&inarg, 0, sizeof(inarg));
  58         inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
  59         req->in.h.opcode = FUSE_OPEN;
  60         req->in.h.nodeid = get_node_id(inode);
  61         req->inode = inode;
  62         req->in.numargs = 1;
  63         req->in.args[0].size = sizeof(inarg);
  64         req->in.args[0].value = &inarg;
  65         req->out.numargs = 1;
  66         req->out.args[0].size = sizeof(outarg);
  67         req->out.args[0].value = &outarg;
  68         if (excl)
  69                 request_send_nonint(fc, req);
  70         else
  71                 request_send(fc, req);
  72         err = req->out.h.error;
  73         if (!err && !(fc->flags & FUSE_KERNEL_CACHE))
  74                 invalidate_inode_pages(inode->i_mapping);
  75         if (err) {
  76                 fuse_request_free(ff->release_req);
  77                 kfree(ff);
  78         } else {
  79                 ff->fh = outarg.fh;
  80                 file->private_data = ff;
  81         }
  82
  83  out_put_request:
  84         fuse_put_request(fc, req);
  85         return err;
  86 }
  87
  88 static int fuse_release(struct inode *inode, struct file *file)
  89 {
  90         struct fuse_conn *fc = get_fuse_conn(inode);
  91         struct fuse_file *ff = file->private_data;
  92         struct fuse_req *req = ff->release_req;
  93         struct fuse_release_in *inarg = &req->misc.release_in;
  94
  95         inarg->fh = ff->fh;
  96         inarg->flags = file->f_flags & ~O_EXCL;
  97         req->in.h.opcode = FUSE_RELEASE;
  98         req->in.h.nodeid = get_node_id(inode);
  99         req->inode = inode;
 100         req->in.numargs = 1;
 101         req->in.args[0].size = sizeof(struct fuse_release_in);
 102         req->in.args[0].value = inarg;
 103         request_send_background(fc, req);
 104         kfree(ff);
 105
 106         /* Return value is ignored by VFS */
 107         return 0;
 108 }
 109
 110 static int fuse_flush(struct file *file)
 111 {
 112         struct inode *inode = file->f_dentry->d_inode;
 113         struct fuse_conn *fc = get_fuse_conn(inode);
 114         struct fuse_file *ff = file->private_data;
 115         struct fuse_req *req;
 116         struct fuse_flush_in inarg;
 117         int err;
 118
 119         if (fc->no_flush)
 120                 return 0;
 121
 122         req = fuse_get_request_nonint(fc);
 123         if (!req)
 124                 return -EINTR;
 125
 126         memset(&inarg, 0, sizeof(inarg));
 127         inarg.fh = ff->fh;
 128         req->in.h.opcode = FUSE_FLUSH;
 129         req->in.h.nodeid = get_node_id(inode);
 130         req->inode = inode;
 131         req->file = file;
 132         req->in.numargs = 1;
 133         req->in.args[0].size = sizeof(inarg);
 134         req->in.args[0].value = &inarg;
 135         request_send_nonint(fc, req);
 136         err = req->out.h.error;
 137         fuse_put_request(fc, req);
 138         if (err == -ENOSYS) {
 139                 fc->no_flush = 1;
 140                 err = 0;
 141         }
 142         return err;
 143 }
 144
 145 static int fuse_fsync(struct file *file, struct dentry *de, int datasync)
 146 {
 147         struct inode *inode = de->d_inode;
 148         struct fuse_conn *fc = get_fuse_conn(inode);
 149         struct fuse_file *ff = file->private_data;
 150         struct fuse_req *req;
 151         struct fuse_fsync_in inarg;
 152         int err;
 153
 154         if (fc->no_fsync)
 155                 return 0;
 156
 157         req = fuse_get_request(fc);
 158         if (!req)
 159                 return -ERESTARTSYS;
 160
 161         memset(&inarg, 0, sizeof(inarg));
 162         inarg.fh = ff->fh;
 163         inarg.fsync_flags = datasync ? 1 : 0;
 164         req->in.h.opcode = FUSE_FSYNC;
 165         req->in.h.nodeid = get_node_id(inode);
 166         req->inode = inode;
 167         req->file = file;
 168         req->in.numargs = 1;
 169         req->in.args[0].size = sizeof(inarg);
 170         req->in.args[0].value = &inarg;
 171         request_send(fc, req);
 172         err = req->out.h.error;
 173         fuse_put_request(fc, req);
 174         if (err == -ENOSYS) {
 175                 fc->no_fsync = 1;
 176                 err = 0;
 177         }
 178         return err;
 179 }
 180
 181 static ssize_t fuse_send_read(struct fuse_req *req, struct file *file,
 182                               struct inode *inode, loff_t pos,  size_t count)
 183 {
 184         struct fuse_conn *fc = get_fuse_conn(inode);
 185         struct fuse_file *ff = file->private_data;
 186         struct fuse_read_in inarg;
 187
 188         memset(&inarg, 0, sizeof(struct fuse_read_in));
 189         inarg.fh = ff->fh;
 190         inarg.offset = pos;
 191         inarg.size = count;
 192         req->in.h.opcode = FUSE_READ;
 193         req->in.h.nodeid = get_node_id(inode);
 194         req->inode = inode;
 195         req->file = file;
 196         req->in.numargs = 1;
 197         req->in.args[0].size = sizeof(struct fuse_read_in);
 198         req->in.args[0].value = &inarg;
 199         req->out.argpages = 1;
 200         req->out.argvar = 1;
 201         req->out.numargs = 1;
 202         req->out.args[0].size = count;
 203         request_send_nonint(fc, req);
 204         return req->out.args[0].size;
 205 }
 206
 207 static int fuse_readpage(struct file *file, struct page *page)
 208 {
 209         struct inode *inode = page->mapping->host;
 210         struct fuse_conn *fc = get_fuse_conn(inode);
 211         loff_t pos = (loff_t) page->index << PAGE_CACHE_SHIFT;
 212         struct fuse_req *req = fuse_get_request_nonint(fc);
 213         int err = -EINTR;
 214         if (!req)
 215                 goto out;
 216
 217         req->out.page_zeroing = 1;
 218         req->num_pages = 1;
 219         req->pages[0] = page;
 220         fuse_send_read(req, file, inode, pos, PAGE_CACHE_SIZE);
 221         err = req->out.h.error;
 222         fuse_put_request(fc, req);
 223         if (!err)
 224                 SetPageUptodate(page);
 225  out:
 226         unlock_page(page);
 227         return err;
 228 }
 229
 230 static int fuse_send_readpages(struct fuse_req *req, struct file *file,
 231                                struct inode *inode)
 232 {
 233         loff_t pos = (loff_t) req->pages[0]->index << PAGE_CACHE_SHIFT;
 234         size_t count = req->num_pages << PAGE_CACHE_SHIFT;
 235         unsigned i;
 236         req->out.page_zeroing = 1;
 237         fuse_send_read(req, file, inode, pos, count);
 238         for (i = 0; i < req->num_pages; i++) {
 239                 struct page *page = req->pages[i];
 240                 if (!req->out.h.error)
 241                         SetPageUptodate(page);
 242                 unlock_page(page);
 243         }
 244         return req->out.h.error;
 245 }
 246
 247 struct fuse_readpages_data {
 248         struct fuse_req *req;
 249         struct file *file;
 250         struct inode *inode;
 251 };
 252
 253 static int fuse_readpages_fill(void *_data, struct page *page)
 254 {
 255         struct fuse_readpages_data *data = _data;
 256         struct fuse_req *req = data->req;
 257         struct inode *inode = data->inode;
 258         struct fuse_conn *fc = get_fuse_conn(inode);
 259
 260         if (req->num_pages &&
 261             (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
 262              (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
 263              req->pages[req->num_pages - 1]->index + 1 != page->index)) {
 264                 int err = fuse_send_readpages(req, data->file, inode);
 265                 if (err) {
 266                         unlock_page(page);
 267                         return err;
 268                 }
 269                 fuse_reset_request(req);
 270         }
 271         req->pages[req->num_pages] = page;
 272         req->num_pages ++;
 273         return 0;
 274 }
 275
 276 static int fuse_readpages(struct file *file, struct address_space *mapping,
 277                           struct list_head *pages, unsigned nr_pages)
 278 {
 279         struct inode *inode = mapping->host;
 280         struct fuse_conn *fc = get_fuse_conn(inode);
 281         struct fuse_readpages_data data;
 282         int err;
 283         data.file = file;
 284         data.inode = inode;
 285         data.req = fuse_get_request_nonint(fc);
 286         if (!data.req)
 287                 return -EINTR;
 288
 289         err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
 290         if (!err && data.req->num_pages)
 291                 err = fuse_send_readpages(data.req, file, inode);
 292         fuse_put_request(fc, data.req);
 293         return err;
 294 }
 295
 296 static ssize_t fuse_send_write(struct fuse_req *req, struct file *file,
 297                                struct inode *inode, loff_t pos, size_t count)
 298 {
 299         struct fuse_conn *fc = get_fuse_conn(inode);
 300         struct fuse_file *ff = file->private_data;
 301         struct fuse_write_in inarg;
 302         struct fuse_write_out outarg;
 303
 304         memset(&inarg, 0, sizeof(struct fuse_write_in));
 305         inarg.fh = ff->fh;
 306         inarg.offset = pos;
 307         inarg.size = count;
 308         req->in.h.opcode = FUSE_WRITE;
 309         req->in.h.nodeid = get_node_id(inode);
 310         req->inode = inode;
 311         req->file = file;
 312         req->in.argpages = 1;
 313         req->in.numargs = 2;
 314         req->in.args[0].size = sizeof(struct fuse_write_in);
 315         req->in.args[0].value = &inarg;
 316         req->in.args[1].size = count;
 317         req->out.numargs = 1;
 318         req->out.args[0].size = sizeof(struct fuse_write_out);
 319         req->out.args[0].value = &outarg;
 320         request_send_nonint(fc, req);
 321         return outarg.size;
 322 }
 323
 324 static int fuse_prepare_write(struct file *file, struct page *page,
 325                               unsigned offset, unsigned to)
 326 {
 327         /* No op */
 328         return 0;
 329 }
 330
 331 static int fuse_commit_write(struct file *file, struct page *page,
 332                              unsigned offset, unsigned to)
 333 {
 334         int err;
 335         ssize_t nres;
 336         unsigned count = to - offset;
 337         struct inode *inode = page->mapping->host;
 338         struct fuse_conn *fc = get_fuse_conn(inode);
 339         loff_t pos = ((loff_t) page->index << PAGE_CACHE_SHIFT) + offset;
 340         struct fuse_req *req = fuse_get_request_nonint(fc);
 341         if (!req)
 342                 return -EINTR;
 343
 344         req->num_pages = 1;
 345         req->pages[0] = page;
 346         req->page_offset = offset;
 347         nres = fuse_send_write(req, file, inode, pos, count);
 348         err = req->out.h.error;
 349         fuse_put_request(fc, req);
 350         if (!err && nres != count)
 351                 err = -EIO;
 352         if (!err) {
 353                 pos += count;
 354                 if (pos > i_size_read(inode))
 355                         i_size_write(inode, pos);
 356
 357                 if (offset == 0 && to == PAGE_CACHE_SIZE) {
 358                         clear_page_dirty(page);
 359                         SetPageUptodate(page);
 360                 }
 361         } else if (err == -EINTR || err == -EIO)
 362                 fuse_invalidate_attr(inode);
 363         return err;
 364 }
 365
 366 static void fuse_release_user_pages(struct fuse_req *req, int write)
 367 {
 368         unsigned i;
 369
 370         for (i = 0; i < req->num_pages; i++) {
 371                 struct page *page = req->pages[i];
 372                 if (write)
 373                         set_page_dirty_lock(page);
 374                 put_page(page);
 375         }
 376 }
 377
 378 static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
 379                                unsigned nbytes, int write)
 380 {
 381         unsigned long user_addr = (unsigned long) buf;
 382         unsigned offset = user_addr & ~PAGE_MASK;
 383         int npages;
 384
 385         /* This doesn't work with nfsd */
 386         if (!current->mm)
 387                 return -EPERM;
 388
 389         nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
 390         npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
 391         npages = min(npages, FUSE_MAX_PAGES_PER_REQ);
 392         down_read(&current->mm->mmap_sem);
 393         npages = get_user_pages(current, current->mm, user_addr, npages, write,
 394                                 0, req->pages, NULL);
 395         up_read(&current->mm->mmap_sem);
 396         if (npages < 0)
 397                 return npages;
 398
 399         req->num_pages = npages;
 400         req->page_offset = offset;
 401         return 0;
 402 }
 403
 404 static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
 405                               size_t count, loff_t *ppos, int write)
 406 {
 407         struct inode *inode = file->f_dentry->d_inode;
 408         struct fuse_conn *fc = get_fuse_conn(inode);
 409         size_t nmax = write ? fc->max_write : fc->max_read;
 410         loff_t pos = *ppos;
 411         ssize_t res = 0;
 412         struct fuse_req *req = fuse_get_request(fc);
 413         if (!req)
 414                 return -ERESTARTSYS;
 415
 416         while (count) {
 417                 size_t tmp;
 418                 size_t nres;
 419                 size_t nbytes = min(count, nmax);
 420                 int err = fuse_get_user_pages(req, buf, nbytes, !write);
 421                 if (err) {
 422                         res = err;
 423                         break;
 424                 }
 425                 tmp = (req->num_pages << PAGE_SHIFT) - req->page_offset;
 426                 nbytes = min(nbytes, tmp);
 427                 if (write)
 428                         nres = fuse_send_write(req, file, inode, pos, nbytes);
 429                 else
 430                         nres = fuse_send_read(req, file, inode, pos, nbytes);
 431                 fuse_release_user_pages(req, !write);
 432                 if (req->out.h.error) {
 433                         if (!res)
 434                                 res = req->out.h.error;
 435                         break;
 436                 } else if (nres > nbytes) {
 437                         res = -EIO;
 438                         break;
 439                 }
 440                 count -= nres;
 441                 res += nres;
 442                 pos += nres;
 443                 buf += nres;
 444                 if (nres != nbytes)
 445                         break;
 446                 if (count)
 447                         fuse_reset_request(req);
 448         }
 449         fuse_put_request(fc, req);
 450         if (res > 0) {
 451                 if (write && pos > i_size_read(inode))
 452                         i_size_write(inode, pos);
 453                 *ppos = pos;
 454         } else if (write && (res == -EINTR || res == -EIO))
 455                 fuse_invalidate_attr(inode);
 456
 457         return res;
 458 }
 459
 460 static ssize_t fuse_direct_read(struct file *file, char __user *buf,
 461                                      size_t count, loff_t *ppos)
 462 {
 463         return fuse_direct_io(file, buf, count, ppos, 0);
 464 }
 465
 466 static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
 467                                  size_t count, loff_t *ppos)
 468 {
 469         struct inode *inode = file->f_dentry->d_inode;
 470         ssize_t res;
 471         /* Don't allow parallel writes to the same file */
 472         down(&inode->i_sem);
 473         res = fuse_direct_io(file, buf, count, ppos, 1);
 474         up(&inode->i_sem);
 475         return res;
 476 }
 477
 478 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
 479 {
 480         if ((vma->vm_flags & VM_SHARED)) {
 481                 if ((vma->vm_flags & VM_WRITE))
 482                         return -ENODEV;
 483                 else
 484                         vma->vm_flags &= ~VM_MAYWRITE;
 485         }
 486         return generic_file_mmap(file, vma);
 487 }
 488
 489 static int fuse_set_page_dirty(struct page *page)
 490 {
 491         printk("fuse_set_page_dirty: should not happen\n");
 492         dump_stack();
 493         return 0;
 494 }
 495
 496 static struct file_operations fuse_file_operations = {
 497         .llseek         = generic_file_llseek,
 498         .read           = generic_file_read,
 499         .write          = generic_file_write,
 500         .mmap           = fuse_file_mmap,
 501         .open           = fuse_open,
 502         .flush          = fuse_flush,
 503         .release        = fuse_release,
 504         .fsync          = fuse_fsync,
 505         .sendfile       = generic_file_sendfile,
 506 };
 507
 508 static struct file_operations fuse_direct_io_file_operations = {
 509         .llseek         = generic_file_llseek,
 510         .read           = fuse_direct_read,
 511         .write          = fuse_direct_write,
 512         .open           = fuse_open,
 513         .flush          = fuse_flush,
 514         .release        = fuse_release,
 515         .fsync          = fuse_fsync,
 516         /* no mmap and sendfile */
 517 };
 518
 519 static struct address_space_operations fuse_file_aops  = {
 520         .readpage       = fuse_readpage,
 521         .prepare_write  = fuse_prepare_write,
 522         .commit_write   = fuse_commit_write,
 523         .readpages      = fuse_readpages,
 524         .set_page_dirty = fuse_set_page_dirty,
 525 };
 526
 527 void fuse_init_file_inode(struct inode *inode)
 528 {
 529         struct fuse_conn *fc = get_fuse_conn(inode);
 530
 531         if (fc->flags & FUSE_DIRECT_IO)
 532                 inode->i_fop = &fuse_direct_io_file_operations;
 533         else {
 534                 inode->i_fop = &fuse_file_operations;
 535                 inode->i_data.a_ops = &fuse_file_aops;
 536         }
 537 }