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 struct file_operations fuse_direct_io_file_operations;
  16
  17 int fuse_open_common(struct inode *inode, struct file *file, int isdir)
  18 {
  19         struct fuse_conn *fc = get_fuse_conn(inode);
  20         struct fuse_req *req;
  21         struct fuse_open_in inarg;
  22         struct fuse_open_out outarg;
  23         struct fuse_file *ff;
  24         int err;
  25         /* Restarting the syscall is not allowed if O_CREAT and O_EXCL
  26            are both set, because creation will fail on the restart */
  27         int excl = (file->f_flags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL);
  28
  29         err = generic_file_open(inode, file);
  30         if (err)
  31                 return err;
  32
  33         /* If opening the root node, no lookup has been performed on
  34            it, so the attributes must be refreshed */
  35         if (get_node_id(inode) == FUSE_ROOT_ID) {
  36                 int err = fuse_do_getattr(inode);
  37                 if (err)
  38                         return err;
  39         }
  40
  41         if (excl)
  42                 req = fuse_get_request_nonint(fc);
  43         else
  44                 req = fuse_get_request(fc);
  45         if (!req)
  46                 return excl ? -EINTR : -ERESTARTSYS;
  47
  48         err = -ENOMEM;
  49         ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
  50         if (!ff)
  51                 goto out_put_request;
  52
  53         ff->release_req = fuse_request_alloc();
  54         if (!ff->release_req) {
  55                 kfree(ff);
  56                 goto out_put_request;
  57         }
  58
  59         memset(&inarg, 0, sizeof(inarg));
  60         inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
  61         req->in.h.opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
  62         req->in.h.nodeid = get_node_id(inode);
  63         req->inode = inode;
  64         req->in.numargs = 1;
  65         req->in.args[0].size = sizeof(inarg);
  66         req->in.args[0].value = &inarg;
  67         req->out.numargs = 1;
  68         req->out.args[0].size = sizeof(outarg);
  69         req->out.args[0].value = &outarg;
  70         if (excl)
  71                 request_send_nonint(fc, req);
  72         else
  73                 request_send(fc, req);
  74         err = req->out.h.error;
  75         if (err) {
  76                 fuse_request_free(ff->release_req);
  77                 kfree(ff);
  78         } else {
  79                 if (!isdir && (outarg.open_flags & FOPEN_DIRECT_IO))
  80                         file->f_op = &fuse_direct_io_file_operations;
  81                 if (!(outarg.open_flags & FOPEN_KEEP_CACHE))
  82                         invalidate_inode_pages(inode->i_mapping);
  83                 ff->fh = outarg.fh;
  84                 file->private_data = ff;
  85         }
  86
  87  out_put_request:
  88         fuse_put_request(fc, req);
  89         return err;
  90 }
  91
  92 int fuse_release_common(struct inode *inode, struct file *file, int isdir)
  93 {
  94         struct fuse_conn *fc = get_fuse_conn(inode);
  95         struct fuse_file *ff = file->private_data;
  96         struct fuse_req *req = ff->release_req;
  97         struct fuse_release_in *inarg = &req->misc.release_in;
  98
  99         inarg->fh = ff->fh;
 100         inarg->flags = file->f_flags & ~O_EXCL;
 101         req->in.h.opcode = isdir ? FUSE_RELEASEDIR : FUSE_RELEASE;
 102         req->in.h.nodeid = get_node_id(inode);
 103         req->inode = inode;
 104         req->in.numargs = 1;
 105         req->in.args[0].size = sizeof(struct fuse_release_in);
 106         req->in.args[0].value = inarg;
 107         request_send_background(fc, req);
 108         kfree(ff);
 109
 110         /* Return value is ignored by VFS */
 111         return 0;
 112 }
 113
 114 static int fuse_open(struct inode *inode, struct file *file)
 115 {
 116         return fuse_open_common(inode, file, 0);
 117 }
 118
 119 static int fuse_release(struct inode *inode, struct file *file)
 120 {
 121         return fuse_release_common(inode, file, 0);
 122 }
 123
 124 static int fuse_flush(struct file *file)
 125 {
 126         struct inode *inode = file->f_dentry->d_inode;
 127         struct fuse_conn *fc = get_fuse_conn(inode);
 128         struct fuse_file *ff = file->private_data;
 129         struct fuse_req *req;
 130         struct fuse_flush_in inarg;
 131         int err;
 132
 133         if (fc->no_flush)
 134                 return 0;
 135
 136         req = fuse_get_request_nonint(fc);
 137         if (!req)
 138                 return -EINTR;
 139
 140         memset(&inarg, 0, sizeof(inarg));
 141         inarg.fh = ff->fh;
 142         req->in.h.opcode = FUSE_FLUSH;
 143         req->in.h.nodeid = get_node_id(inode);
 144         req->inode = inode;
 145         req->file = file;
 146         req->in.numargs = 1;
 147         req->in.args[0].size = sizeof(inarg);
 148         req->in.args[0].value = &inarg;
 149         request_send_nonint(fc, req);
 150         err = req->out.h.error;
 151         fuse_put_request(fc, req);
 152         if (err == -ENOSYS) {
 153                 fc->no_flush = 1;
 154                 err = 0;
 155         }
 156         return err;
 157 }
 158
 159 static int fuse_fsync(struct file *file, struct dentry *de, int datasync)
 160 {
 161         struct inode *inode = de->d_inode;
 162         struct fuse_conn *fc = get_fuse_conn(inode);
 163         struct fuse_file *ff = file->private_data;
 164         struct fuse_req *req;
 165         struct fuse_fsync_in inarg;
 166         int err;
 167
 168         if (fc->no_fsync)
 169                 return 0;
 170
 171         req = fuse_get_request(fc);
 172         if (!req)
 173                 return -ERESTARTSYS;
 174
 175         memset(&inarg, 0, sizeof(inarg));
 176         inarg.fh = ff->fh;
 177         inarg.fsync_flags = datasync ? 1 : 0;
 178         req->in.h.opcode = FUSE_FSYNC;
 179         req->in.h.nodeid = get_node_id(inode);
 180         req->inode = inode;
 181         req->file = file;
 182         req->in.numargs = 1;
 183         req->in.args[0].size = sizeof(inarg);
 184         req->in.args[0].value = &inarg;
 185         request_send(fc, req);
 186         err = req->out.h.error;
 187         fuse_put_request(fc, req);
 188         if (err == -ENOSYS) {
 189                 fc->no_fsync = 1;
 190                 err = 0;
 191         }
 192         return err;
 193 }
 194
 195 size_t fuse_send_read_common(struct fuse_req *req, struct file *file,
 196                              struct inode *inode, loff_t pos, size_t count,
 197                              int isdir)
 198 {
 199         struct fuse_conn *fc = get_fuse_conn(inode);
 200         struct fuse_file *ff = file->private_data;
 201         struct fuse_read_in inarg;
 202
 203         memset(&inarg, 0, sizeof(struct fuse_read_in));
 204         inarg.fh = ff->fh;
 205         inarg.offset = pos;
 206         inarg.size = count;
 207         req->in.h.opcode = isdir ? FUSE_READDIR : FUSE_READ;
 208         req->in.h.nodeid = get_node_id(inode);
 209         req->inode = inode;
 210         req->file = file;
 211         req->in.numargs = 1;
 212         req->in.args[0].size = sizeof(struct fuse_read_in);
 213         req->in.args[0].value = &inarg;
 214         req->out.argpages = 1;
 215         req->out.argvar = 1;
 216         req->out.numargs = 1;
 217         req->out.args[0].size = count;
 218         request_send_nonint(fc, req);
 219         return req->out.args[0].size;
 220 }
 221
 222 static inline size_t fuse_send_read(struct fuse_req *req, struct file *file,
 223                                     struct inode *inode, loff_t pos,
 224                                     size_t count)
 225 {
 226         return fuse_send_read_common(req, file, inode, pos, count, 0);
 227 }
 228
 229 static int fuse_readpage(struct file *file, struct page *page)
 230 {
 231         struct inode *inode = page->mapping->host;
 232         struct fuse_conn *fc = get_fuse_conn(inode);
 233         loff_t pos = (loff_t) page->index << PAGE_CACHE_SHIFT;
 234         struct fuse_req *req = fuse_get_request_nonint(fc);
 235         int err = -EINTR;
 236         if (!req)
 237                 goto out;
 238
 239         req->out.page_zeroing = 1;
 240         req->num_pages = 1;
 241         req->pages[0] = page;
 242         fuse_send_read(req, file, inode, pos, PAGE_CACHE_SIZE);
 243         err = req->out.h.error;
 244         fuse_put_request(fc, req);
 245         if (!err)
 246                 SetPageUptodate(page);
 247  out:
 248         unlock_page(page);
 249         return err;
 250 }
 251
 252 static int fuse_send_readpages(struct fuse_req *req, struct file *file,
 253                                struct inode *inode)
 254 {
 255         loff_t pos = (loff_t) req->pages[0]->index << PAGE_CACHE_SHIFT;
 256         size_t count = req->num_pages << PAGE_CACHE_SHIFT;
 257         unsigned i;
 258         req->out.page_zeroing = 1;
 259         fuse_send_read(req, file, inode, pos, count);
 260         for (i = 0; i < req->num_pages; i++) {
 261                 struct page *page = req->pages[i];
 262                 if (!req->out.h.error)
 263                         SetPageUptodate(page);
 264                 unlock_page(page);
 265         }
 266         return req->out.h.error;
 267 }
 268
 269 struct fuse_readpages_data {
 270         struct fuse_req *req;
 271         struct file *file;
 272         struct inode *inode;
 273 };
 274
 275 static int fuse_readpages_fill(void *_data, struct page *page)
 276 {
 277         struct fuse_readpages_data *data = _data;
 278         struct fuse_req *req = data->req;
 279         struct inode *inode = data->inode;
 280         struct fuse_conn *fc = get_fuse_conn(inode);
 281
 282         if (req->num_pages &&
 283             (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
 284              (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
 285              req->pages[req->num_pages - 1]->index + 1 != page->index)) {
 286                 int err = fuse_send_readpages(req, data->file, inode);
 287                 if (err) {
 288                         unlock_page(page);
 289                         return err;
 290                 }
 291                 fuse_reset_request(req);
 292         }
 293         req->pages[req->num_pages] = page;
 294         req->num_pages ++;
 295         return 0;
 296 }
 297
 298 static int fuse_readpages(struct file *file, struct address_space *mapping,
 299                           struct list_head *pages, unsigned nr_pages)
 300 {
 301         struct inode *inode = mapping->host;
 302         struct fuse_conn *fc = get_fuse_conn(inode);
 303         struct fuse_readpages_data data;
 304         int err;
 305         data.file = file;
 306         data.inode = inode;
 307         data.req = fuse_get_request_nonint(fc);
 308         if (!data.req)
 309                 return -EINTR;
 310
 311         err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
 312         if (!err && data.req->num_pages)
 313                 err = fuse_send_readpages(data.req, file, inode);
 314         fuse_put_request(fc, data.req);
 315         return err;
 316 }
 317
 318 static size_t fuse_send_write(struct fuse_req *req, struct file *file,
 319                               struct inode *inode, loff_t pos, size_t count)
 320 {
 321         struct fuse_conn *fc = get_fuse_conn(inode);
 322         struct fuse_file *ff = file->private_data;
 323         struct fuse_write_in inarg;
 324         struct fuse_write_out outarg;
 325
 326         memset(&inarg, 0, sizeof(struct fuse_write_in));
 327         inarg.fh = ff->fh;
 328         inarg.offset = pos;
 329         inarg.size = count;
 330         req->in.h.opcode = FUSE_WRITE;
 331         req->in.h.nodeid = get_node_id(inode);
 332         req->inode = inode;
 333         req->file = file;
 334         req->in.argpages = 1;
 335         req->in.numargs = 2;
 336         req->in.args[0].size = sizeof(struct fuse_write_in);
 337         req->in.args[0].value = &inarg;
 338         req->in.args[1].size = count;
 339         req->out.numargs = 1;
 340         req->out.args[0].size = sizeof(struct fuse_write_out);
 341         req->out.args[0].value = &outarg;
 342         request_send_nonint(fc, req);
 343         return outarg.size;
 344 }
 345
 346 static int fuse_prepare_write(struct file *file, struct page *page,
 347                               unsigned offset, unsigned to)
 348 {
 349         /* No op */
 350         return 0;
 351 }
 352
 353 static int fuse_commit_write(struct file *file, struct page *page,
 354                              unsigned offset, unsigned to)
 355 {
 356         int err;
 357         size_t nres;
 358         unsigned count = to - offset;
 359         struct inode *inode = page->mapping->host;
 360         struct fuse_conn *fc = get_fuse_conn(inode);
 361         loff_t pos = ((loff_t) page->index << PAGE_CACHE_SHIFT) + offset;
 362         struct fuse_req *req = fuse_get_request_nonint(fc);
 363         if (!req)
 364                 return -EINTR;
 365
 366         req->num_pages = 1;
 367         req->pages[0] = page;
 368         req->page_offset = offset;
 369         nres = fuse_send_write(req, file, inode, pos, count);
 370         err = req->out.h.error;
 371         fuse_put_request(fc, req);
 372         if (!err && nres != count)
 373                 err = -EIO;
 374         if (!err) {
 375                 pos += count;
 376                 if (pos > i_size_read(inode))
 377                         i_size_write(inode, pos);
 378
 379                 if (offset == 0 && to == PAGE_CACHE_SIZE) {
 380                         clear_page_dirty(page);
 381                         SetPageUptodate(page);
 382                 }
 383         } else if (err == -EINTR || err == -EIO)
 384                 fuse_invalidate_attr(inode);
 385         return err;
 386 }
 387
 388 static void fuse_release_user_pages(struct fuse_req *req, int write)
 389 {
 390         unsigned i;
 391
 392         for (i = 0; i < req->num_pages; i++) {
 393                 struct page *page = req->pages[i];
 394                 if (write)
 395                         set_page_dirty_lock(page);
 396                 put_page(page);
 397         }
 398 }
 399
 400 static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
 401                                unsigned nbytes, int write)
 402 {
 403         unsigned long user_addr = (unsigned long) buf;
 404         unsigned offset = user_addr & ~PAGE_MASK;
 405         int npages;
 406
 407         /* This doesn't work with nfsd */
 408         if (!current->mm)
 409                 return -EPERM;
 410
 411         nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
 412         npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
 413         npages = min(npages, FUSE_MAX_PAGES_PER_REQ);
 414         down_read(&current->mm->mmap_sem);
 415         npages = get_user_pages(current, current->mm, user_addr, npages, write,
 416                                 0, req->pages, NULL);
 417         up_read(&current->mm->mmap_sem);
 418         if (npages < 0)
 419                 return npages;
 420
 421         req->num_pages = npages;
 422         req->page_offset = offset;
 423         return 0;
 424 }
 425
 426 static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
 427                               size_t count, loff_t *ppos, int write)
 428 {
 429         struct inode *inode = file->f_dentry->d_inode;
 430         struct fuse_conn *fc = get_fuse_conn(inode);
 431         size_t nmax = write ? fc->max_write : fc->max_read;
 432         loff_t pos = *ppos;
 433         ssize_t res = 0;
 434         struct fuse_req *req = fuse_get_request(fc);
 435         if (!req)
 436                 return -ERESTARTSYS;
 437
 438         while (count) {
 439                 size_t tmp;
 440                 size_t nres;
 441                 size_t nbytes = min(count, nmax);
 442                 int err = fuse_get_user_pages(req, buf, nbytes, !write);
 443                 if (err) {
 444                         res = err;
 445                         break;
 446                 }
 447                 tmp = (req->num_pages << PAGE_SHIFT) - req->page_offset;
 448                 nbytes = min(nbytes, tmp);
 449                 if (write)
 450                         nres = fuse_send_write(req, file, inode, pos, nbytes);
 451                 else
 452                         nres = fuse_send_read(req, file, inode, pos, nbytes);
 453                 fuse_release_user_pages(req, !write);
 454                 if (req->out.h.error) {
 455                         if (!res)
 456                                 res = req->out.h.error;
 457                         break;
 458                 } else if (nres > nbytes) {
 459                         res = -EIO;
 460                         break;
 461                 }
 462                 count -= nres;
 463                 res += nres;
 464                 pos += nres;
 465                 buf += nres;
 466                 if (nres != nbytes)
 467                         break;
 468                 if (count)
 469                         fuse_reset_request(req);
 470         }
 471         fuse_put_request(fc, req);
 472         if (res > 0) {
 473                 if (write && pos > i_size_read(inode))
 474                         i_size_write(inode, pos);
 475                 *ppos = pos;
 476         } else if (write && (res == -EINTR || res == -EIO))
 477                 fuse_invalidate_attr(inode);
 478
 479         return res;
 480 }
 481
 482 static ssize_t fuse_direct_read(struct file *file, char __user *buf,
 483                                      size_t count, loff_t *ppos)
 484 {
 485         return fuse_direct_io(file, buf, count, ppos, 0);
 486 }
 487
 488 static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
 489                                  size_t count, loff_t *ppos)
 490 {
 491         struct inode *inode = file->f_dentry->d_inode;
 492         ssize_t res;
 493         /* Don't allow parallel writes to the same file */
 494         down(&inode->i_sem);
 495         res = fuse_direct_io(file, buf, count, ppos, 1);
 496         up(&inode->i_sem);
 497         return res;
 498 }
 499
 500 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
 501 {
 502         if ((vma->vm_flags & VM_SHARED)) {
 503                 if ((vma->vm_flags & VM_WRITE))
 504                         return -ENODEV;
 505                 else
 506                         vma->vm_flags &= ~VM_MAYWRITE;
 507         }
 508         return generic_file_mmap(file, vma);
 509 }
 510
 511 static int fuse_set_page_dirty(struct page *page)
 512 {
 513         printk("fuse_set_page_dirty: should not happen\n");
 514         dump_stack();
 515         return 0;
 516 }
 517
 518 static struct file_operations fuse_file_operations = {
 519         .llseek         = generic_file_llseek,
 520         .read           = generic_file_read,
 521         .write          = generic_file_write,
 522         .mmap           = fuse_file_mmap,
 523         .open           = fuse_open,
 524         .flush          = fuse_flush,
 525         .release        = fuse_release,
 526         .fsync          = fuse_fsync,
 527         .sendfile       = generic_file_sendfile,
 528 };
 529
 530 static struct file_operations fuse_direct_io_file_operations = {
 531         .llseek         = generic_file_llseek,
 532         .read           = fuse_direct_read,
 533         .write          = fuse_direct_write,
 534         .open           = fuse_open,
 535         .flush          = fuse_flush,
 536         .release        = fuse_release,
 537         .fsync          = fuse_fsync,
 538         /* no mmap and sendfile */
 539 };
 540
 541 static struct address_space_operations fuse_file_aops  = {
 542         .readpage       = fuse_readpage,
 543         .prepare_write  = fuse_prepare_write,
 544         .commit_write   = fuse_commit_write,
 545         .readpages      = fuse_readpages,
 546         .set_page_dirty = fuse_set_page_dirty,
 547 };
 548
 549 void fuse_init_file_inode(struct inode *inode)
 550 {
 551         inode->i_fop = &fuse_file_operations;
 552         inode->i_data.a_ops = &fuse_file_aops;
 553 }