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
  26         /* VFS checks this, but only _after_ ->open() */
  27         if (file->f_flags & O_DIRECT)
  28                 return -EINVAL;
  29
  30         err = generic_file_open(inode, file);
  31         if (err)
  32                 return err;
  33
  34         /* If opening the root node, no lookup has been performed on
  35            it, so the attributes must be refreshed */
  36         if (get_node_id(inode) == FUSE_ROOT_ID) {
  37                 int err = fuse_do_getattr(inode);
  38                 if (err)
  39                         return err;
  40         }
  41
  42         req = fuse_get_request(fc);
  43         if (!req)
  44                 return -EINTR;
  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 = isdir ? FUSE_OPENDIR : 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         request_send(fc, req);
  69         err = req->out.h.error;
  70         if (err) {
  71                 fuse_request_free(ff->release_req);
  72                 kfree(ff);
  73         } else {
  74                 if (!isdir && (outarg.open_flags & FOPEN_DIRECT_IO))
  75                         file->f_op = &fuse_direct_io_file_operations;
  76                 if (!(outarg.open_flags & FOPEN_KEEP_CACHE))
  77                         invalidate_inode_pages(inode->i_mapping);
  78                 ff->fh = outarg.fh;
  79                 file->private_data = ff;
  80         }
  81
  82  out_put_request:
  83         fuse_put_request(fc, req);
  84         return err;
  85 }
  86
  87 int fuse_release_common(struct inode *inode, struct file *file, int isdir)
  88 {
  89         struct fuse_conn *fc = get_fuse_conn(inode);
  90         struct fuse_file *ff = file->private_data;
  91         struct fuse_req *req = ff->release_req;
  92         struct fuse_release_in *inarg = &req->misc.release_in;
  93
  94         inarg->fh = ff->fh;
  95         inarg->flags = file->f_flags & ~O_EXCL;
  96         req->in.h.opcode = isdir ? FUSE_RELEASEDIR : FUSE_RELEASE;
  97         req->in.h.nodeid = get_node_id(inode);
  98         req->inode = inode;
  99         req->in.numargs = 1;
 100         req->in.args[0].size = sizeof(struct fuse_release_in);
 101         req->in.args[0].value = inarg;
 102         request_send_background(fc, req);
 103         kfree(ff);
 104
 105         /* Return value is ignored by VFS */
 106         return 0;
 107 }
 108
 109 static int fuse_open(struct inode *inode, struct file *file)
 110 {
 111         return fuse_open_common(inode, file, 0);
 112 }
 113
 114 static int fuse_release(struct inode *inode, struct file *file)
 115 {
 116         return fuse_release_common(inode, file, 0);
 117 }
 118
 119 static int fuse_flush(struct file *file)
 120 {
 121         struct inode *inode = file->f_dentry->d_inode;
 122         struct fuse_conn *fc = get_fuse_conn(inode);
 123         struct fuse_file *ff = file->private_data;
 124         struct fuse_req *req;
 125         struct fuse_flush_in inarg;
 126         int err;
 127
 128         if (fc->no_flush)
 129                 return 0;
 130
 131         req = fuse_get_request(fc);
 132         if (!req)
 133                 return -EINTR;
 134
 135         memset(&inarg, 0, sizeof(inarg));
 136         inarg.fh = ff->fh;
 137         req->in.h.opcode = FUSE_FLUSH;
 138         req->in.h.nodeid = get_node_id(inode);
 139         req->inode = inode;
 140         req->file = file;
 141         req->in.numargs = 1;
 142         req->in.args[0].size = sizeof(inarg);
 143         req->in.args[0].value = &inarg;
 144         request_send(fc, req);
 145         err = req->out.h.error;
 146         fuse_put_request(fc, req);
 147         if (err == -ENOSYS) {
 148                 fc->no_flush = 1;
 149                 err = 0;
 150         }
 151         return err;
 152 }
 153
 154 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
 155                       int isdir)
 156 {
 157         struct inode *inode = de->d_inode;
 158         struct fuse_conn *fc = get_fuse_conn(inode);
 159         struct fuse_file *ff = file->private_data;
 160         struct fuse_req *req;
 161         struct fuse_fsync_in inarg;
 162         int err;
 163
 164         if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir))
 165                 return 0;
 166
 167         req = fuse_get_request(fc);
 168         if (!req)
 169                 return -EINTR;
 170
 171         memset(&inarg, 0, sizeof(inarg));
 172         inarg.fh = ff->fh;
 173         inarg.fsync_flags = datasync ? 1 : 0;
 174         req->in.h.opcode = isdir ? FUSE_FSYNCDIR : FUSE_FSYNC;
 175         req->in.h.nodeid = get_node_id(inode);
 176         req->inode = inode;
 177         req->file = file;
 178         req->in.numargs = 1;
 179         req->in.args[0].size = sizeof(inarg);
 180         req->in.args[0].value = &inarg;
 181         request_send(fc, req);
 182         err = req->out.h.error;
 183         fuse_put_request(fc, req);
 184         if (err == -ENOSYS) {
 185                 if (isdir)
 186                         fc->no_fsyncdir = 1;
 187                 else
 188                         fc->no_fsync = 1;
 189                 err = 0;
 190         }
 191         return err;
 192 }
 193
 194 static int fuse_fsync(struct file *file, struct dentry *de, int datasync)
 195 {
 196         return fuse_fsync_common(file, de, datasync, 0);
 197 }
 198
 199 size_t fuse_send_read_common(struct fuse_req *req, struct file *file,
 200                              struct inode *inode, loff_t pos, size_t count,
 201                              int isdir)
 202 {
 203         struct fuse_conn *fc = get_fuse_conn(inode);
 204         struct fuse_file *ff = file->private_data;
 205         struct fuse_read_in inarg;
 206
 207         memset(&inarg, 0, sizeof(struct fuse_read_in));
 208         inarg.fh = ff->fh;
 209         inarg.offset = pos;
 210         inarg.size = count;
 211         req->in.h.opcode = isdir ? FUSE_READDIR : FUSE_READ;
 212         req->in.h.nodeid = get_node_id(inode);
 213         req->inode = inode;
 214         req->file = file;
 215         req->in.numargs = 1;
 216         req->in.args[0].size = sizeof(struct fuse_read_in);
 217         req->in.args[0].value = &inarg;
 218         req->out.argpages = 1;
 219         req->out.argvar = 1;
 220         req->out.numargs = 1;
 221         req->out.args[0].size = count;
 222         request_send(fc, req);
 223         return req->out.args[0].size;
 224 }
 225
 226 static inline size_t fuse_send_read(struct fuse_req *req, struct file *file,
 227                                     struct inode *inode, loff_t pos,
 228                                     size_t count)
 229 {
 230         return fuse_send_read_common(req, file, inode, pos, count, 0);
 231 }
 232
 233 static int fuse_readpage(struct file *file, struct page *page)
 234 {
 235         struct inode *inode = page->mapping->host;
 236         struct fuse_conn *fc = get_fuse_conn(inode);
 237         loff_t pos = (loff_t) page->index << PAGE_CACHE_SHIFT;
 238         struct fuse_req *req = fuse_get_request(fc);
 239         int err = -EINTR;
 240         if (!req)
 241                 goto out;
 242
 243         req->out.page_zeroing = 1;
 244         req->num_pages = 1;
 245         req->pages[0] = page;
 246         fuse_send_read(req, file, inode, pos, PAGE_CACHE_SIZE);
 247         err = req->out.h.error;
 248         fuse_put_request(fc, req);
 249         if (!err)
 250                 SetPageUptodate(page);
 251         fuse_invalidate_attr(inode); /* atime changed */
 252  out:
 253         unlock_page(page);
 254         return err;
 255 }
 256
 257 static int fuse_send_readpages(struct fuse_req *req, struct file *file,
 258                                struct inode *inode)
 259 {
 260         loff_t pos = (loff_t) req->pages[0]->index << PAGE_CACHE_SHIFT;
 261         size_t count = req->num_pages << PAGE_CACHE_SHIFT;
 262         unsigned i;
 263         req->out.page_zeroing = 1;
 264         fuse_send_read(req, file, inode, pos, count);
 265         for (i = 0; i < req->num_pages; i++) {
 266                 struct page *page = req->pages[i];
 267                 if (!req->out.h.error)
 268                         SetPageUptodate(page);
 269                 unlock_page(page);
 270         }
 271         return req->out.h.error;
 272 }
 273
 274 struct fuse_readpages_data {
 275         struct fuse_req *req;
 276         struct file *file;
 277         struct inode *inode;
 278 };
 279
 280 static int fuse_readpages_fill(void *_data, struct page *page)
 281 {
 282         struct fuse_readpages_data *data = _data;
 283         struct fuse_req *req = data->req;
 284         struct inode *inode = data->inode;
 285         struct fuse_conn *fc = get_fuse_conn(inode);
 286
 287         if (req->num_pages &&
 288             (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
 289              (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
 290              req->pages[req->num_pages - 1]->index + 1 != page->index)) {
 291                 int err = fuse_send_readpages(req, data->file, inode);
 292                 if (err) {
 293                         unlock_page(page);
 294                         return err;
 295                 }
 296                 fuse_reset_request(req);
 297         }
 298         req->pages[req->num_pages] = page;
 299         req->num_pages ++;
 300         return 0;
 301 }
 302
 303 static int fuse_readpages(struct file *file, struct address_space *mapping,
 304                           struct list_head *pages, unsigned nr_pages)
 305 {
 306         struct inode *inode = mapping->host;
 307         struct fuse_conn *fc = get_fuse_conn(inode);
 308         struct fuse_readpages_data data;
 309         int err;
 310         data.file = file;
 311         data.inode = inode;
 312         data.req = fuse_get_request(fc);
 313         if (!data.req)
 314                 return -EINTR;
 315
 316         err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
 317         if (!err && data.req->num_pages)
 318                 err = fuse_send_readpages(data.req, file, inode);
 319         fuse_put_request(fc, data.req);
 320         fuse_invalidate_attr(inode); /* atime changed */
 321         return err;
 322 }
 323
 324 static size_t fuse_send_write(struct fuse_req *req, struct file *file,
 325                               struct inode *inode, loff_t pos, size_t count)
 326 {
 327         struct fuse_conn *fc = get_fuse_conn(inode);
 328         struct fuse_file *ff = file->private_data;
 329         struct fuse_write_in inarg;
 330         struct fuse_write_out outarg;
 331
 332         memset(&inarg, 0, sizeof(struct fuse_write_in));
 333         inarg.fh = ff->fh;
 334         inarg.offset = pos;
 335         inarg.size = count;
 336         req->in.h.opcode = FUSE_WRITE;
 337         req->in.h.nodeid = get_node_id(inode);
 338         req->inode = inode;
 339         req->file = file;
 340         req->in.argpages = 1;
 341         req->in.numargs = 2;
 342         req->in.args[0].size = sizeof(struct fuse_write_in);
 343         req->in.args[0].value = &inarg;
 344         req->in.args[1].size = count;
 345         req->out.numargs = 1;
 346         req->out.args[0].size = sizeof(struct fuse_write_out);
 347         req->out.args[0].value = &outarg;
 348         request_send(fc, req);
 349         return outarg.size;
 350 }
 351
 352 static int fuse_prepare_write(struct file *file, struct page *page,
 353                               unsigned offset, unsigned to)
 354 {
 355         /* No op */
 356         return 0;
 357 }
 358
 359 static int fuse_commit_write(struct file *file, struct page *page,
 360                              unsigned offset, unsigned to)
 361 {
 362         int err;
 363         size_t nres;
 364         unsigned count = to - offset;
 365         struct inode *inode = page->mapping->host;
 366         struct fuse_conn *fc = get_fuse_conn(inode);
 367         loff_t pos = ((loff_t) page->index << PAGE_CACHE_SHIFT) + offset;
 368         struct fuse_req *req = fuse_get_request(fc);
 369         if (!req)
 370                 return -EINTR;
 371
 372         req->num_pages = 1;
 373         req->pages[0] = page;
 374         req->page_offset = offset;
 375         nres = fuse_send_write(req, file, inode, pos, count);
 376         err = req->out.h.error;
 377         fuse_put_request(fc, req);
 378         if (!err && nres != count)
 379                 err = -EIO;
 380         if (!err) {
 381                 pos += count;
 382                 if (pos > i_size_read(inode))
 383                         i_size_write(inode, pos);
 384
 385                 if (offset == 0 && to == PAGE_CACHE_SIZE) {
 386                         clear_page_dirty(page);
 387                         SetPageUptodate(page);
 388                 }
 389         }
 390         fuse_invalidate_attr(inode);
 391         return err;
 392 }
 393
 394 static void fuse_release_user_pages(struct fuse_req *req, int write)
 395 {
 396         unsigned i;
 397
 398         for (i = 0; i < req->num_pages; i++) {
 399                 struct page *page = req->pages[i];
 400                 if (write)
 401                         set_page_dirty_lock(page);
 402                 put_page(page);
 403         }
 404 }
 405
 406 static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
 407                                unsigned nbytes, int write)
 408 {
 409         unsigned long user_addr = (unsigned long) buf;
 410         unsigned offset = user_addr & ~PAGE_MASK;
 411         int npages;
 412
 413         /* This doesn't work with nfsd */
 414         if (!current->mm)
 415                 return -EPERM;
 416
 417         nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
 418         npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
 419         npages = min(npages, FUSE_MAX_PAGES_PER_REQ);
 420         down_read(&current->mm->mmap_sem);
 421         npages = get_user_pages(current, current->mm, user_addr, npages, write,
 422                                 0, req->pages, NULL);
 423         up_read(&current->mm->mmap_sem);
 424         if (npages < 0)
 425                 return npages;
 426
 427         req->num_pages = npages;
 428         req->page_offset = offset;
 429         return 0;
 430 }
 431
 432 static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
 433                               size_t count, loff_t *ppos, int write)
 434 {
 435         struct inode *inode = file->f_dentry->d_inode;
 436         struct fuse_conn *fc = get_fuse_conn(inode);
 437         size_t nmax = write ? fc->max_write : fc->max_read;
 438         loff_t pos = *ppos;
 439         ssize_t res = 0;
 440         struct fuse_req *req = fuse_get_request(fc);
 441         if (!req)
 442                 return -EINTR;
 443
 444         while (count) {
 445                 size_t tmp;
 446                 size_t nres;
 447                 size_t nbytes = min(count, nmax);
 448                 int err = fuse_get_user_pages(req, buf, nbytes, !write);
 449                 if (err) {
 450                         res = err;
 451                         break;
 452                 }
 453                 tmp = (req->num_pages << PAGE_SHIFT) - req->page_offset;
 454                 nbytes = min(nbytes, tmp);
 455                 if (write)
 456                         nres = fuse_send_write(req, file, inode, pos, nbytes);
 457                 else
 458                         nres = fuse_send_read(req, file, inode, pos, nbytes);
 459                 fuse_release_user_pages(req, !write);
 460                 if (req->out.h.error) {
 461                         if (!res)
 462                                 res = req->out.h.error;
 463                         break;
 464                 } else if (nres > nbytes) {
 465                         res = -EIO;
 466                         break;
 467                 }
 468                 count -= nres;
 469                 res += nres;
 470                 pos += nres;
 471                 buf += nres;
 472                 if (nres != nbytes)
 473                         break;
 474                 if (count)
 475                         fuse_reset_request(req);
 476         }
 477         fuse_put_request(fc, req);
 478         if (res > 0) {
 479                 if (write && pos > i_size_read(inode))
 480                         i_size_write(inode, pos);
 481                 *ppos = pos;
 482         }
 483         fuse_invalidate_attr(inode);
 484
 485         return res;
 486 }
 487
 488 static ssize_t fuse_direct_read(struct file *file, char __user *buf,
 489                                      size_t count, loff_t *ppos)
 490 {
 491         return fuse_direct_io(file, buf, count, ppos, 0);
 492 }
 493
 494 static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
 495                                  size_t count, loff_t *ppos)
 496 {
 497         struct inode *inode = file->f_dentry->d_inode;
 498         ssize_t res;
 499         /* Don't allow parallel writes to the same file */
 500         down(&inode->i_sem);
 501         res = fuse_direct_io(file, buf, count, ppos, 1);
 502         up(&inode->i_sem);
 503         return res;
 504 }
 505
 506 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
 507 {
 508         if ((vma->vm_flags & VM_SHARED)) {
 509                 if ((vma->vm_flags & VM_WRITE))
 510                         return -ENODEV;
 511                 else
 512                         vma->vm_flags &= ~VM_MAYWRITE;
 513         }
 514         return generic_file_mmap(file, vma);
 515 }
 516
 517 static int fuse_set_page_dirty(struct page *page)
 518 {
 519         printk("fuse_set_page_dirty: should not happen\n");
 520         dump_stack();
 521         return 0;
 522 }
 523
 524 static struct file_operations fuse_file_operations = {
 525         .llseek         = generic_file_llseek,
 526         .read           = generic_file_read,
 527         .write          = generic_file_write,
 528         .mmap           = fuse_file_mmap,
 529         .open           = fuse_open,
 530         .flush          = fuse_flush,
 531         .release        = fuse_release,
 532         .fsync          = fuse_fsync,
 533         .sendfile       = generic_file_sendfile,
 534 };
 535
 536 static struct file_operations fuse_direct_io_file_operations = {
 537         .llseek         = generic_file_llseek,
 538         .read           = fuse_direct_read,
 539         .write          = fuse_direct_write,
 540         .open           = fuse_open,
 541         .flush          = fuse_flush,
 542         .release        = fuse_release,
 543         .fsync          = fuse_fsync,
 544         /* no mmap and sendfile */
 545 };
 546
 547 static struct address_space_operations fuse_file_aops  = {
 548         .readpage       = fuse_readpage,
 549         .prepare_write  = fuse_prepare_write,
 550         .commit_write   = fuse_commit_write,
 551         .readpages      = fuse_readpages,
 552         .set_page_dirty = fuse_set_page_dirty,
 553 };
 554
 555 void fuse_init_file_inode(struct inode *inode)
 556 {
 557         inode->i_fop = &fuse_file_operations;
 558         inode->i_data.a_ops = &fuse_file_aops;
 559 }