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         err = generic_file_open(inode, file);
  27         if (err)
  28                 return err;
  29
  30         /* If opening the root node, no lookup has been performed on
  31            it, so the attributes must be refreshed */
  32         if (get_node_id(inode) == FUSE_ROOT_ID) {
  33                 int err = fuse_do_getattr(inode);
  34                 if (err)
  35                         return err;
  36         }
  37
  38         req = fuse_get_request(fc);
  39         if (!req)
  40                 return -EINTR;
  41
  42         err = -ENOMEM;
  43         ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
  44         if (!ff)
  45                 goto out_put_request;
  46
  47         ff->release_req = fuse_request_alloc();
  48         if (!ff->release_req) {
  49                 kfree(ff);
  50                 goto out_put_request;
  51         }
  52
  53         memset(&inarg, 0, sizeof(inarg));
  54         inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
  55         req->in.h.opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
  56         req->in.h.nodeid = get_node_id(inode);
  57         req->inode = inode;
  58         req->in.numargs = 1;
  59         req->in.args[0].size = sizeof(inarg);
  60         req->in.args[0].value = &inarg;
  61         req->out.numargs = 1;
  62         req->out.args[0].size = sizeof(outarg);
  63         req->out.args[0].value = &outarg;
  64         request_send(fc, req);
  65         err = req->out.h.error;
  66         if (err) {
  67                 fuse_request_free(ff->release_req);
  68                 kfree(ff);
  69         } else {
  70                 if (!isdir && (outarg.open_flags & FOPEN_DIRECT_IO))
  71                         file->f_op = &fuse_direct_io_file_operations;
  72                 if (!(outarg.open_flags & FOPEN_KEEP_CACHE))
  73                         invalidate_inode_pages(inode->i_mapping);
  74                 ff->fh = outarg.fh;
  75                 file->private_data = ff;
  76         }
  77
  78  out_put_request:
  79         fuse_put_request(fc, req);
  80         return err;
  81 }
  82
  83 int fuse_release_common(struct inode *inode, struct file *file, int isdir)
  84 {
  85         struct fuse_conn *fc = get_fuse_conn(inode);
  86         struct fuse_file *ff = file->private_data;
  87         struct fuse_req *req = ff->release_req;
  88         struct fuse_release_in *inarg = &req->misc.release_in;
  89
  90         inarg->fh = ff->fh;
  91         inarg->flags = file->f_flags & ~O_EXCL;
  92         req->in.h.opcode = isdir ? FUSE_RELEASEDIR : FUSE_RELEASE;
  93         req->in.h.nodeid = get_node_id(inode);
  94         req->inode = inode;
  95         req->in.numargs = 1;
  96         req->in.args[0].size = sizeof(struct fuse_release_in);
  97         req->in.args[0].value = inarg;
  98         request_send_background(fc, req);
  99         kfree(ff);
 100
 101         /* Return value is ignored by VFS */
 102         return 0;
 103 }
 104
 105 static int fuse_open(struct inode *inode, struct file *file)
 106 {
 107         return fuse_open_common(inode, file, 0);
 108 }
 109
 110 static int fuse_release(struct inode *inode, struct file *file)
 111 {
 112         return fuse_release_common(inode, file, 0);
 113 }
 114
 115 static int fuse_flush(struct file *file)
 116 {
 117         struct inode *inode = file->f_dentry->d_inode;
 118         struct fuse_conn *fc = get_fuse_conn(inode);
 119         struct fuse_file *ff = file->private_data;
 120         struct fuse_req *req;
 121         struct fuse_flush_in inarg;
 122         int err;
 123
 124         if (fc->no_flush)
 125                 return 0;
 126
 127         req = fuse_get_request(fc);
 128         if (!req)
 129                 return -EINTR;
 130
 131         memset(&inarg, 0, sizeof(inarg));
 132         inarg.fh = ff->fh;
 133         req->in.h.opcode = FUSE_FLUSH;
 134         req->in.h.nodeid = get_node_id(inode);
 135         req->inode = inode;
 136         req->file = file;
 137         req->in.numargs = 1;
 138         req->in.args[0].size = sizeof(inarg);
 139         req->in.args[0].value = &inarg;
 140         request_send(fc, req);
 141         err = req->out.h.error;
 142         fuse_put_request(fc, req);
 143         if (err == -ENOSYS) {
 144                 fc->no_flush = 1;
 145                 err = 0;
 146         }
 147         return err;
 148 }
 149
 150 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
 151                       int isdir)
 152 {
 153         struct inode *inode = de->d_inode;
 154         struct fuse_conn *fc = get_fuse_conn(inode);
 155         struct fuse_file *ff = file->private_data;
 156         struct fuse_req *req;
 157         struct fuse_fsync_in inarg;
 158         int err;
 159
 160         if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir))
 161                 return 0;
 162
 163         req = fuse_get_request(fc);
 164         if (!req)
 165                 return -EINTR;
 166
 167         memset(&inarg, 0, sizeof(inarg));
 168         inarg.fh = ff->fh;
 169         inarg.fsync_flags = datasync ? 1 : 0;
 170         req->in.h.opcode = isdir ? FUSE_FSYNCDIR : FUSE_FSYNC;
 171         req->in.h.nodeid = get_node_id(inode);
 172         req->inode = inode;
 173         req->file = file;
 174         req->in.numargs = 1;
 175         req->in.args[0].size = sizeof(inarg);
 176         req->in.args[0].value = &inarg;
 177         request_send(fc, req);
 178         err = req->out.h.error;
 179         fuse_put_request(fc, req);
 180         if (err == -ENOSYS) {
 181                 if (isdir)
 182                         fc->no_fsyncdir = 1;
 183                 else
 184                         fc->no_fsync = 1;
 185                 err = 0;
 186         }
 187         return err;
 188 }
 189
 190 static int fuse_fsync(struct file *file, struct dentry *de, int datasync)
 191 {
 192         return fuse_fsync_common(file, de, datasync, 0);
 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(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(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         fuse_invalidate_attr(inode); /* atime changed */
 248  out:
 249         unlock_page(page);
 250         return err;
 251 }
 252
 253 static int fuse_send_readpages(struct fuse_req *req, struct file *file,
 254                                struct inode *inode)
 255 {
 256         loff_t pos = (loff_t) req->pages[0]->index << PAGE_CACHE_SHIFT;
 257         size_t count = req->num_pages << PAGE_CACHE_SHIFT;
 258         unsigned i;
 259         req->out.page_zeroing = 1;
 260         fuse_send_read(req, file, inode, pos, count);
 261         for (i = 0; i < req->num_pages; i++) {
 262                 struct page *page = req->pages[i];
 263                 if (!req->out.h.error)
 264                         SetPageUptodate(page);
 265                 unlock_page(page);
 266         }
 267         return req->out.h.error;
 268 }
 269
 270 struct fuse_readpages_data {
 271         struct fuse_req *req;
 272         struct file *file;
 273         struct inode *inode;
 274 };
 275
 276 static int fuse_readpages_fill(void *_data, struct page *page)
 277 {
 278         struct fuse_readpages_data *data = _data;
 279         struct fuse_req *req = data->req;
 280         struct inode *inode = data->inode;
 281         struct fuse_conn *fc = get_fuse_conn(inode);
 282
 283         if (req->num_pages &&
 284             (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
 285              (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
 286              req->pages[req->num_pages - 1]->index + 1 != page->index)) {
 287                 int err = fuse_send_readpages(req, data->file, inode);
 288                 if (err) {
 289                         unlock_page(page);
 290                         return err;
 291                 }
 292                 fuse_reset_request(req);
 293         }
 294         req->pages[req->num_pages] = page;
 295         req->num_pages ++;
 296         return 0;
 297 }
 298
 299 static int fuse_readpages(struct file *file, struct address_space *mapping,
 300                           struct list_head *pages, unsigned nr_pages)
 301 {
 302         struct inode *inode = mapping->host;
 303         struct fuse_conn *fc = get_fuse_conn(inode);
 304         struct fuse_readpages_data data;
 305         int err;
 306         data.file = file;
 307         data.inode = inode;
 308         data.req = fuse_get_request(fc);
 309         if (!data.req)
 310                 return -EINTR;
 311
 312         err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
 313         if (!err && data.req->num_pages)
 314                 err = fuse_send_readpages(data.req, file, inode);
 315         fuse_put_request(fc, data.req);
 316         fuse_invalidate_attr(inode); /* atime changed */
 317         return err;
 318 }
 319
 320 static size_t fuse_send_write(struct fuse_req *req, struct file *file,
 321                               struct inode *inode, loff_t pos, size_t count)
 322 {
 323         struct fuse_conn *fc = get_fuse_conn(inode);
 324         struct fuse_file *ff = file->private_data;
 325         struct fuse_write_in inarg;
 326         struct fuse_write_out outarg;
 327
 328         memset(&inarg, 0, sizeof(struct fuse_write_in));
 329         inarg.fh = ff->fh;
 330         inarg.offset = pos;
 331         inarg.size = count;
 332         req->in.h.opcode = FUSE_WRITE;
 333         req->in.h.nodeid = get_node_id(inode);
 334         req->inode = inode;
 335         req->file = file;
 336         req->in.argpages = 1;
 337         req->in.numargs = 2;
 338         req->in.args[0].size = sizeof(struct fuse_write_in);
 339         req->in.args[0].value = &inarg;
 340         req->in.args[1].size = count;
 341         req->out.numargs = 1;
 342         req->out.args[0].size = sizeof(struct fuse_write_out);
 343         req->out.args[0].value = &outarg;
 344         request_send(fc, req);
 345         return outarg.size;
 346 }
 347
 348 static int fuse_prepare_write(struct file *file, struct page *page,
 349                               unsigned offset, unsigned to)
 350 {
 351         /* No op */
 352         return 0;
 353 }
 354
 355 static int fuse_commit_write(struct file *file, struct page *page,
 356                              unsigned offset, unsigned to)
 357 {
 358         int err;
 359         size_t nres;
 360         unsigned count = to - offset;
 361         struct inode *inode = page->mapping->host;
 362         struct fuse_conn *fc = get_fuse_conn(inode);
 363         loff_t pos = ((loff_t) page->index << PAGE_CACHE_SHIFT) + offset;
 364         struct fuse_req *req = fuse_get_request(fc);
 365         if (!req)
 366                 return -EINTR;
 367
 368         req->num_pages = 1;
 369         req->pages[0] = page;
 370         req->page_offset = offset;
 371         nres = fuse_send_write(req, file, inode, pos, count);
 372         err = req->out.h.error;
 373         fuse_put_request(fc, req);
 374         if (!err && nres != count)
 375                 err = -EIO;
 376         if (!err) {
 377                 pos += count;
 378                 if (pos > i_size_read(inode))
 379                         i_size_write(inode, pos);
 380
 381                 if (offset == 0 && to == PAGE_CACHE_SIZE) {
 382                         clear_page_dirty(page);
 383                         SetPageUptodate(page);
 384                 }
 385         }
 386         fuse_invalidate_attr(inode);
 387         return err;
 388 }
 389
 390 static void fuse_release_user_pages(struct fuse_req *req, int write)
 391 {
 392         unsigned i;
 393
 394         for (i = 0; i < req->num_pages; i++) {
 395                 struct page *page = req->pages[i];
 396                 if (write)
 397                         set_page_dirty_lock(page);
 398                 put_page(page);
 399         }
 400 }
 401
 402 static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
 403                                unsigned nbytes, int write)
 404 {
 405         unsigned long user_addr = (unsigned long) buf;
 406         unsigned offset = user_addr & ~PAGE_MASK;
 407         int npages;
 408
 409         /* This doesn't work with nfsd */
 410         if (!current->mm)
 411                 return -EPERM;
 412
 413         nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
 414         npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
 415         npages = min(npages, FUSE_MAX_PAGES_PER_REQ);
 416         down_read(&current->mm->mmap_sem);
 417         npages = get_user_pages(current, current->mm, user_addr, npages, write,
 418                                 0, req->pages, NULL);
 419         up_read(&current->mm->mmap_sem);
 420         if (npages < 0)
 421                 return npages;
 422
 423         req->num_pages = npages;
 424         req->page_offset = offset;
 425         return 0;
 426 }
 427
 428 static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
 429                               size_t count, loff_t *ppos, int write)
 430 {
 431         struct inode *inode = file->f_dentry->d_inode;
 432         struct fuse_conn *fc = get_fuse_conn(inode);
 433         size_t nmax = write ? fc->max_write : fc->max_read;
 434         loff_t pos = *ppos;
 435         ssize_t res = 0;
 436         struct fuse_req *req = fuse_get_request(fc);
 437         if (!req)
 438                 return -EINTR;
 439
 440         while (count) {
 441                 size_t tmp;
 442                 size_t nres;
 443                 size_t nbytes = min(count, nmax);
 444                 int err = fuse_get_user_pages(req, buf, nbytes, !write);
 445                 if (err) {
 446                         res = err;
 447                         break;
 448                 }
 449                 tmp = (req->num_pages << PAGE_SHIFT) - req->page_offset;
 450                 nbytes = min(nbytes, tmp);
 451                 if (write)
 452                         nres = fuse_send_write(req, file, inode, pos, nbytes);
 453                 else
 454                         nres = fuse_send_read(req, file, inode, pos, nbytes);
 455                 fuse_release_user_pages(req, !write);
 456                 if (req->out.h.error) {
 457                         if (!res)
 458                                 res = req->out.h.error;
 459                         break;
 460                 } else if (nres > nbytes) {
 461                         res = -EIO;
 462                         break;
 463                 }
 464                 count -= nres;
 465                 res += nres;
 466                 pos += nres;
 467                 buf += nres;
 468                 if (nres != nbytes)
 469                         break;
 470                 if (count)
 471                         fuse_reset_request(req);
 472         }
 473         fuse_put_request(fc, req);
 474         if (res > 0) {
 475                 if (write && pos > i_size_read(inode))
 476                         i_size_write(inode, pos);
 477                 *ppos = pos;
 478         }
 479         fuse_invalidate_attr(inode);
 480
 481         return res;
 482 }
 483
 484 static ssize_t fuse_direct_read(struct file *file, char __user *buf,
 485                                      size_t count, loff_t *ppos)
 486 {
 487         return fuse_direct_io(file, buf, count, ppos, 0);
 488 }
 489
 490 static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
 491                                  size_t count, loff_t *ppos)
 492 {
 493         struct inode *inode = file->f_dentry->d_inode;
 494         ssize_t res;
 495         /* Don't allow parallel writes to the same file */
 496         down(&inode->i_sem);
 497         res = fuse_direct_io(file, buf, count, ppos, 1);
 498         up(&inode->i_sem);
 499         return res;
 500 }
 501
 502 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
 503 {
 504         if ((vma->vm_flags & VM_SHARED)) {
 505                 if ((vma->vm_flags & VM_WRITE))
 506                         return -ENODEV;
 507                 else
 508                         vma->vm_flags &= ~VM_MAYWRITE;
 509         }
 510         return generic_file_mmap(file, vma);
 511 }
 512
 513 static int fuse_set_page_dirty(struct page *page)
 514 {
 515         printk("fuse_set_page_dirty: should not happen\n");
 516         dump_stack();
 517         return 0;
 518 }
 519
 520 static struct file_operations fuse_file_operations = {
 521         .llseek         = generic_file_llseek,
 522         .read           = generic_file_read,
 523         .write          = generic_file_write,
 524         .mmap           = fuse_file_mmap,
 525         .open           = fuse_open,
 526         .flush          = fuse_flush,
 527         .release        = fuse_release,
 528         .fsync          = fuse_fsync,
 529         .sendfile       = generic_file_sendfile,
 530 };
 531
 532 static struct file_operations fuse_direct_io_file_operations = {
 533         .llseek         = generic_file_llseek,
 534         .read           = fuse_direct_read,
 535         .write          = fuse_direct_write,
 536         .open           = fuse_open,
 537         .flush          = fuse_flush,
 538         .release        = fuse_release,
 539         .fsync          = fuse_fsync,
 540         /* no mmap and sendfile */
 541 };
 542
 543 static struct address_space_operations fuse_file_aops  = {
 544         .readpage       = fuse_readpage,
 545         .prepare_write  = fuse_prepare_write,
 546         .commit_write   = fuse_commit_write,
 547         .readpages      = fuse_readpages,
 548         .set_page_dirty = fuse_set_page_dirty,
 549 };
 550
 551 void fuse_init_file_inode(struct inode *inode)
 552 {
 553         inode->i_fop = &fuse_file_operations;
 554         inode->i_data.a_ops = &fuse_file_aops;
 555 }