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Linux/fs/fuse/file.c

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  1 /*
  2   FUSE: Filesystem in Userspace
  3   Copyright (C) 2001-2008  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 #include <linux/sched.h>
 15 #include <linux/module.h>
 16 #include <linux/compat.h>
 17 #include <linux/swap.h>
 18 #include <linux/falloc.h>
 19 #include <linux/uio.h>
 20 
 21 static const struct file_operations fuse_direct_io_file_operations;
 22 
 23 static int fuse_send_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
 24                           int opcode, struct fuse_open_out *outargp)
 25 {
 26         struct fuse_open_in inarg;
 27         FUSE_ARGS(args);
 28 
 29         memset(&inarg, 0, sizeof(inarg));
 30         inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY);
 31         if (!fc->atomic_o_trunc)
 32                 inarg.flags &= ~O_TRUNC;
 33         args.in.h.opcode = opcode;
 34         args.in.h.nodeid = nodeid;
 35         args.in.numargs = 1;
 36         args.in.args[0].size = sizeof(inarg);
 37         args.in.args[0].value = &inarg;
 38         args.out.numargs = 1;
 39         args.out.args[0].size = sizeof(*outargp);
 40         args.out.args[0].value = outargp;
 41 
 42         return fuse_simple_request(fc, &args);
 43 }
 44 
 45 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc)
 46 {
 47         struct fuse_file *ff;
 48 
 49         ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
 50         if (unlikely(!ff))
 51                 return NULL;
 52 
 53         ff->fc = fc;
 54         ff->reserved_req = fuse_request_alloc(0);
 55         if (unlikely(!ff->reserved_req)) {
 56                 kfree(ff);
 57                 return NULL;
 58         }
 59 
 60         INIT_LIST_HEAD(&ff->write_entry);
 61         atomic_set(&ff->count, 0);
 62         RB_CLEAR_NODE(&ff->polled_node);
 63         init_waitqueue_head(&ff->poll_wait);
 64 
 65         spin_lock(&fc->lock);
 66         ff->kh = ++fc->khctr;
 67         spin_unlock(&fc->lock);
 68 
 69         return ff;
 70 }
 71 
 72 void fuse_file_free(struct fuse_file *ff)
 73 {
 74         fuse_request_free(ff->reserved_req);
 75         kfree(ff);
 76 }
 77 
 78 struct fuse_file *fuse_file_get(struct fuse_file *ff)
 79 {
 80         atomic_inc(&ff->count);
 81         return ff;
 82 }
 83 
 84 static void fuse_release_end(struct fuse_conn *fc, struct fuse_req *req)
 85 {
 86         iput(req->misc.release.inode);
 87 }
 88 
 89 static void fuse_file_put(struct fuse_file *ff, bool sync)
 90 {
 91         if (atomic_dec_and_test(&ff->count)) {
 92                 struct fuse_req *req = ff->reserved_req;
 93 
 94                 if (ff->fc->no_open) {
 95                         /*
 96                          * Drop the release request when client does not
 97                          * implement 'open'
 98                          */
 99                         __clear_bit(FR_BACKGROUND, &req->flags);
100                         iput(req->misc.release.inode);
101                         fuse_put_request(ff->fc, req);
102                 } else if (sync) {
103                         __clear_bit(FR_BACKGROUND, &req->flags);
104                         fuse_request_send(ff->fc, req);
105                         iput(req->misc.release.inode);
106                         fuse_put_request(ff->fc, req);
107                 } else {
108                         req->end = fuse_release_end;
109                         __set_bit(FR_BACKGROUND, &req->flags);
110                         fuse_request_send_background(ff->fc, req);
111                 }
112                 kfree(ff);
113         }
114 }
115 
116 int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
117                  bool isdir)
118 {
119         struct fuse_file *ff;
120         int opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
121 
122         ff = fuse_file_alloc(fc);
123         if (!ff)
124                 return -ENOMEM;
125 
126         ff->fh = 0;
127         ff->open_flags = FOPEN_KEEP_CACHE; /* Default for no-open */
128         if (!fc->no_open || isdir) {
129                 struct fuse_open_out outarg;
130                 int err;
131 
132                 err = fuse_send_open(fc, nodeid, file, opcode, &outarg);
133                 if (!err) {
134                         ff->fh = outarg.fh;
135                         ff->open_flags = outarg.open_flags;
136 
137                 } else if (err != -ENOSYS || isdir) {
138                         fuse_file_free(ff);
139                         return err;
140                 } else {
141                         fc->no_open = 1;
142                 }
143         }
144 
145         if (isdir)
146                 ff->open_flags &= ~FOPEN_DIRECT_IO;
147 
148         ff->nodeid = nodeid;
149         file->private_data = fuse_file_get(ff);
150 
151         return 0;
152 }
153 EXPORT_SYMBOL_GPL(fuse_do_open);
154 
155 static void fuse_link_write_file(struct file *file)
156 {
157         struct inode *inode = file_inode(file);
158         struct fuse_conn *fc = get_fuse_conn(inode);
159         struct fuse_inode *fi = get_fuse_inode(inode);
160         struct fuse_file *ff = file->private_data;
161         /*
162          * file may be written through mmap, so chain it onto the
163          * inodes's write_file list
164          */
165         spin_lock(&fc->lock);
166         if (list_empty(&ff->write_entry))
167                 list_add(&ff->write_entry, &fi->write_files);
168         spin_unlock(&fc->lock);
169 }
170 
171 void fuse_finish_open(struct inode *inode, struct file *file)
172 {
173         struct fuse_file *ff = file->private_data;
174         struct fuse_conn *fc = get_fuse_conn(inode);
175 
176         if (ff->open_flags & FOPEN_DIRECT_IO)
177                 file->f_op = &fuse_direct_io_file_operations;
178         if (!(ff->open_flags & FOPEN_KEEP_CACHE))
179                 invalidate_inode_pages2(inode->i_mapping);
180         if (ff->open_flags & FOPEN_NONSEEKABLE)
181                 nonseekable_open(inode, file);
182         if (fc->atomic_o_trunc && (file->f_flags & O_TRUNC)) {
183                 struct fuse_inode *fi = get_fuse_inode(inode);
184 
185                 spin_lock(&fc->lock);
186                 fi->attr_version = ++fc->attr_version;
187                 i_size_write(inode, 0);
188                 spin_unlock(&fc->lock);
189                 fuse_invalidate_attr(inode);
190                 if (fc->writeback_cache)
191                         file_update_time(file);
192         }
193         if ((file->f_mode & FMODE_WRITE) && fc->writeback_cache)
194                 fuse_link_write_file(file);
195 }
196 
197 int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
198 {
199         struct fuse_conn *fc = get_fuse_conn(inode);
200         int err;
201         bool lock_inode = (file->f_flags & O_TRUNC) &&
202                           fc->atomic_o_trunc &&
203                           fc->writeback_cache;
204 
205         err = generic_file_open(inode, file);
206         if (err)
207                 return err;
208 
209         if (lock_inode)
210                 inode_lock(inode);
211 
212         err = fuse_do_open(fc, get_node_id(inode), file, isdir);
213 
214         if (!err)
215                 fuse_finish_open(inode, file);
216 
217         if (lock_inode)
218                 inode_unlock(inode);
219 
220         return err;
221 }
222 
223 static void fuse_prepare_release(struct fuse_file *ff, int flags, int opcode)
224 {
225         struct fuse_conn *fc = ff->fc;
226         struct fuse_req *req = ff->reserved_req;
227         struct fuse_release_in *inarg = &req->misc.release.in;
228 
229         spin_lock(&fc->lock);
230         list_del(&ff->write_entry);
231         if (!RB_EMPTY_NODE(&ff->polled_node))
232                 rb_erase(&ff->polled_node, &fc->polled_files);
233         spin_unlock(&fc->lock);
234 
235         wake_up_interruptible_all(&ff->poll_wait);
236 
237         inarg->fh = ff->fh;
238         inarg->flags = flags;
239         req->in.h.opcode = opcode;
240         req->in.h.nodeid = ff->nodeid;
241         req->in.numargs = 1;
242         req->in.args[0].size = sizeof(struct fuse_release_in);
243         req->in.args[0].value = inarg;
244 }
245 
246 void fuse_release_common(struct file *file, int opcode)
247 {
248         struct fuse_file *ff;
249         struct fuse_req *req;
250 
251         ff = file->private_data;
252         if (unlikely(!ff))
253                 return;
254 
255         req = ff->reserved_req;
256         fuse_prepare_release(ff, file->f_flags, opcode);
257 
258         if (ff->flock) {
259                 struct fuse_release_in *inarg = &req->misc.release.in;
260                 inarg->release_flags |= FUSE_RELEASE_FLOCK_UNLOCK;
261                 inarg->lock_owner = fuse_lock_owner_id(ff->fc,
262                                                        (fl_owner_t) file);
263         }
264         /* Hold inode until release is finished */
265         req->misc.release.inode = igrab(file_inode(file));
266 
267         /*
268          * Normally this will send the RELEASE request, however if
269          * some asynchronous READ or WRITE requests are outstanding,
270          * the sending will be delayed.
271          *
272          * Make the release synchronous if this is a fuseblk mount,
273          * synchronous RELEASE is allowed (and desirable) in this case
274          * because the server can be trusted not to screw up.
275          */
276         fuse_file_put(ff, ff->fc->destroy_req != NULL);
277 }
278 
279 static int fuse_open(struct inode *inode, struct file *file)
280 {
281         return fuse_open_common(inode, file, false);
282 }
283 
284 static int fuse_release(struct inode *inode, struct file *file)
285 {
286         struct fuse_conn *fc = get_fuse_conn(inode);
287 
288         /* see fuse_vma_close() for !writeback_cache case */
289         if (fc->writeback_cache)
290                 write_inode_now(inode, 1);
291 
292         fuse_release_common(file, FUSE_RELEASE);
293 
294         /* return value is ignored by VFS */
295         return 0;
296 }
297 
298 void fuse_sync_release(struct fuse_file *ff, int flags)
299 {
300         WARN_ON(atomic_read(&ff->count) > 1);
301         fuse_prepare_release(ff, flags, FUSE_RELEASE);
302         __set_bit(FR_FORCE, &ff->reserved_req->flags);
303         __clear_bit(FR_BACKGROUND, &ff->reserved_req->flags);
304         fuse_request_send(ff->fc, ff->reserved_req);
305         fuse_put_request(ff->fc, ff->reserved_req);
306         kfree(ff);
307 }
308 EXPORT_SYMBOL_GPL(fuse_sync_release);
309 
310 /*
311  * Scramble the ID space with XTEA, so that the value of the files_struct
312  * pointer is not exposed to userspace.
313  */
314 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
315 {
316         u32 *k = fc->scramble_key;
317         u64 v = (unsigned long) id;
318         u32 v0 = v;
319         u32 v1 = v >> 32;
320         u32 sum = 0;
321         int i;
322 
323         for (i = 0; i < 32; i++) {
324                 v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
325                 sum += 0x9E3779B9;
326                 v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
327         }
328 
329         return (u64) v0 + ((u64) v1 << 32);
330 }
331 
332 /*
333  * Check if any page in a range is under writeback
334  *
335  * This is currently done by walking the list of writepage requests
336  * for the inode, which can be pretty inefficient.
337  */
338 static bool fuse_range_is_writeback(struct inode *inode, pgoff_t idx_from,
339                                    pgoff_t idx_to)
340 {
341         struct fuse_conn *fc = get_fuse_conn(inode);
342         struct fuse_inode *fi = get_fuse_inode(inode);
343         struct fuse_req *req;
344         bool found = false;
345 
346         spin_lock(&fc->lock);
347         list_for_each_entry(req, &fi->writepages, writepages_entry) {
348                 pgoff_t curr_index;
349 
350                 BUG_ON(req->inode != inode);
351                 curr_index = req->misc.write.in.offset >> PAGE_SHIFT;
352                 if (idx_from < curr_index + req->num_pages &&
353                     curr_index <= idx_to) {
354                         found = true;
355                         break;
356                 }
357         }
358         spin_unlock(&fc->lock);
359 
360         return found;
361 }
362 
363 static inline bool fuse_page_is_writeback(struct inode *inode, pgoff_t index)
364 {
365         return fuse_range_is_writeback(inode, index, index);
366 }
367 
368 /*
369  * Wait for page writeback to be completed.
370  *
371  * Since fuse doesn't rely on the VM writeback tracking, this has to
372  * use some other means.
373  */
374 static int fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index)
375 {
376         struct fuse_inode *fi = get_fuse_inode(inode);
377 
378         wait_event(fi->page_waitq, !fuse_page_is_writeback(inode, index));
379         return 0;
380 }
381 
382 /*
383  * Wait for all pending writepages on the inode to finish.
384  *
385  * This is currently done by blocking further writes with FUSE_NOWRITE
386  * and waiting for all sent writes to complete.
387  *
388  * This must be called under i_mutex, otherwise the FUSE_NOWRITE usage
389  * could conflict with truncation.
390  */
391 static void fuse_sync_writes(struct inode *inode)
392 {
393         fuse_set_nowrite(inode);
394         fuse_release_nowrite(inode);
395 }
396 
397 static int fuse_flush(struct file *file, fl_owner_t id)
398 {
399         struct inode *inode = file_inode(file);
400         struct fuse_conn *fc = get_fuse_conn(inode);
401         struct fuse_file *ff = file->private_data;
402         struct fuse_req *req;
403         struct fuse_flush_in inarg;
404         int err;
405 
406         if (is_bad_inode(inode))
407                 return -EIO;
408 
409         if (fc->no_flush)
410                 return 0;
411 
412         err = write_inode_now(inode, 1);
413         if (err)
414                 return err;
415 
416         inode_lock(inode);
417         fuse_sync_writes(inode);
418         inode_unlock(inode);
419 
420         if (test_bit(AS_ENOSPC, &file->f_mapping->flags) &&
421             test_and_clear_bit(AS_ENOSPC, &file->f_mapping->flags))
422                 err = -ENOSPC;
423         if (test_bit(AS_EIO, &file->f_mapping->flags) &&
424             test_and_clear_bit(AS_EIO, &file->f_mapping->flags))
425                 err = -EIO;
426         if (err)
427                 return err;
428 
429         req = fuse_get_req_nofail_nopages(fc, file);
430         memset(&inarg, 0, sizeof(inarg));
431         inarg.fh = ff->fh;
432         inarg.lock_owner = fuse_lock_owner_id(fc, id);
433         req->in.h.opcode = FUSE_FLUSH;
434         req->in.h.nodeid = get_node_id(inode);
435         req->in.numargs = 1;
436         req->in.args[0].size = sizeof(inarg);
437         req->in.args[0].value = &inarg;
438         __set_bit(FR_FORCE, &req->flags);
439         fuse_request_send(fc, req);
440         err = req->out.h.error;
441         fuse_put_request(fc, req);
442         if (err == -ENOSYS) {
443                 fc->no_flush = 1;
444                 err = 0;
445         }
446         return err;
447 }
448 
449 int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
450                       int datasync, int isdir)
451 {
452         struct inode *inode = file->f_mapping->host;
453         struct fuse_conn *fc = get_fuse_conn(inode);
454         struct fuse_file *ff = file->private_data;
455         FUSE_ARGS(args);
456         struct fuse_fsync_in inarg;
457         int err;
458 
459         if (is_bad_inode(inode))
460                 return -EIO;
461 
462         inode_lock(inode);
463 
464         /*
465          * Start writeback against all dirty pages of the inode, then
466          * wait for all outstanding writes, before sending the FSYNC
467          * request.
468          */
469         err = filemap_write_and_wait_range(inode->i_mapping, start, end);
470         if (err)
471                 goto out;
472 
473         fuse_sync_writes(inode);
474 
475         /*
476          * Due to implementation of fuse writeback
477          * filemap_write_and_wait_range() does not catch errors.
478          * We have to do this directly after fuse_sync_writes()
479          */
480         if (test_bit(AS_ENOSPC, &file->f_mapping->flags) &&
481             test_and_clear_bit(AS_ENOSPC, &file->f_mapping->flags))
482                 err = -ENOSPC;
483         if (test_bit(AS_EIO, &file->f_mapping->flags) &&
484             test_and_clear_bit(AS_EIO, &file->f_mapping->flags))
485                 err = -EIO;
486         if (err)
487                 goto out;
488 
489         err = sync_inode_metadata(inode, 1);
490         if (err)
491                 goto out;
492 
493         if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir))
494                 goto out;
495 
496         memset(&inarg, 0, sizeof(inarg));
497         inarg.fh = ff->fh;
498         inarg.fsync_flags = datasync ? 1 : 0;
499         args.in.h.opcode = isdir ? FUSE_FSYNCDIR : FUSE_FSYNC;
500         args.in.h.nodeid = get_node_id(inode);
501         args.in.numargs = 1;
502         args.in.args[0].size = sizeof(inarg);
503         args.in.args[0].value = &inarg;
504         err = fuse_simple_request(fc, &args);
505         if (err == -ENOSYS) {
506                 if (isdir)
507                         fc->no_fsyncdir = 1;
508                 else
509                         fc->no_fsync = 1;
510                 err = 0;
511         }
512 out:
513         inode_unlock(inode);
514         return err;
515 }
516 
517 static int fuse_fsync(struct file *file, loff_t start, loff_t end,
518                       int datasync)
519 {
520         return fuse_fsync_common(file, start, end, datasync, 0);
521 }
522 
523 void fuse_read_fill(struct fuse_req *req, struct file *file, loff_t pos,
524                     size_t count, int opcode)
525 {
526         struct fuse_read_in *inarg = &req->misc.read.in;
527         struct fuse_file *ff = file->private_data;
528 
529         inarg->fh = ff->fh;
530         inarg->offset = pos;
531         inarg->size = count;
532         inarg->flags = file->f_flags;
533         req->in.h.opcode = opcode;
534         req->in.h.nodeid = ff->nodeid;
535         req->in.numargs = 1;
536         req->in.args[0].size = sizeof(struct fuse_read_in);
537         req->in.args[0].value = inarg;
538         req->out.argvar = 1;
539         req->out.numargs = 1;
540         req->out.args[0].size = count;
541 }
542 
543 static void fuse_release_user_pages(struct fuse_req *req, bool should_dirty)
544 {
545         unsigned i;
546 
547         for (i = 0; i < req->num_pages; i++) {
548                 struct page *page = req->pages[i];
549                 if (should_dirty)
550                         set_page_dirty_lock(page);
551                 put_page(page);
552         }
553 }
554 
555 static void fuse_io_release(struct kref *kref)
556 {
557         kfree(container_of(kref, struct fuse_io_priv, refcnt));
558 }
559 
560 static ssize_t fuse_get_res_by_io(struct fuse_io_priv *io)
561 {
562         if (io->err)
563                 return io->err;
564 
565         if (io->bytes >= 0 && io->write)
566                 return -EIO;
567 
568         return io->bytes < 0 ? io->size : io->bytes;
569 }
570 
571 /**
572  * In case of short read, the caller sets 'pos' to the position of
573  * actual end of fuse request in IO request. Otherwise, if bytes_requested
574  * == bytes_transferred or rw == WRITE, the caller sets 'pos' to -1.
575  *
576  * An example:
577  * User requested DIO read of 64K. It was splitted into two 32K fuse requests,
578  * both submitted asynchronously. The first of them was ACKed by userspace as
579  * fully completed (req->out.args[0].size == 32K) resulting in pos == -1. The
580  * second request was ACKed as short, e.g. only 1K was read, resulting in
581  * pos == 33K.
582  *
583  * Thus, when all fuse requests are completed, the minimal non-negative 'pos'
584  * will be equal to the length of the longest contiguous fragment of
585  * transferred data starting from the beginning of IO request.
586  */
587 static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
588 {
589         bool is_sync = is_sync_kiocb(io->iocb);
590         int left;
591 
592         spin_lock(&io->lock);
593         if (err)
594                 io->err = io->err ? : err;
595         else if (pos >= 0 && (io->bytes < 0 || pos < io->bytes))
596                 io->bytes = pos;
597 
598         left = --io->reqs;
599         if (!left && is_sync)
600                 complete(io->done);
601         spin_unlock(&io->lock);
602 
603         if (!left && !is_sync) {
604                 ssize_t res = fuse_get_res_by_io(io);
605 
606                 if (res >= 0) {
607                         struct inode *inode = file_inode(io->iocb->ki_filp);
608                         struct fuse_conn *fc = get_fuse_conn(inode);
609                         struct fuse_inode *fi = get_fuse_inode(inode);
610 
611                         spin_lock(&fc->lock);
612                         fi->attr_version = ++fc->attr_version;
613                         spin_unlock(&fc->lock);
614                 }
615 
616                 io->iocb->ki_complete(io->iocb, res, 0);
617         }
618 
619         kref_put(&io->refcnt, fuse_io_release);
620 }
621 
622 static void fuse_aio_complete_req(struct fuse_conn *fc, struct fuse_req *req)
623 {
624         struct fuse_io_priv *io = req->io;
625         ssize_t pos = -1;
626 
627         fuse_release_user_pages(req, !io->write);
628 
629         if (io->write) {
630                 if (req->misc.write.in.size != req->misc.write.out.size)
631                         pos = req->misc.write.in.offset - io->offset +
632                                 req->misc.write.out.size;
633         } else {
634                 if (req->misc.read.in.size != req->out.args[0].size)
635                         pos = req->misc.read.in.offset - io->offset +
636                                 req->out.args[0].size;
637         }
638 
639         fuse_aio_complete(io, req->out.h.error, pos);
640 }
641 
642 static size_t fuse_async_req_send(struct fuse_conn *fc, struct fuse_req *req,
643                 size_t num_bytes, struct fuse_io_priv *io)
644 {
645         spin_lock(&io->lock);
646         kref_get(&io->refcnt);
647         io->size += num_bytes;
648         io->reqs++;
649         spin_unlock(&io->lock);
650 
651         req->io = io;
652         req->end = fuse_aio_complete_req;
653 
654         __fuse_get_request(req);
655         fuse_request_send_background(fc, req);
656 
657         return num_bytes;
658 }
659 
660 static size_t fuse_send_read(struct fuse_req *req, struct fuse_io_priv *io,
661                              loff_t pos, size_t count, fl_owner_t owner)
662 {
663         struct file *file = io->file;
664         struct fuse_file *ff = file->private_data;
665         struct fuse_conn *fc = ff->fc;
666 
667         fuse_read_fill(req, file, pos, count, FUSE_READ);
668         if (owner != NULL) {
669                 struct fuse_read_in *inarg = &req->misc.read.in;
670 
671                 inarg->read_flags |= FUSE_READ_LOCKOWNER;
672                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
673         }
674 
675         if (io->async)
676                 return fuse_async_req_send(fc, req, count, io);
677 
678         fuse_request_send(fc, req);
679         return req->out.args[0].size;
680 }
681 
682 static void fuse_read_update_size(struct inode *inode, loff_t size,
683                                   u64 attr_ver)
684 {
685         struct fuse_conn *fc = get_fuse_conn(inode);
686         struct fuse_inode *fi = get_fuse_inode(inode);
687 
688         spin_lock(&fc->lock);
689         if (attr_ver == fi->attr_version && size < inode->i_size &&
690             !test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
691                 fi->attr_version = ++fc->attr_version;
692                 i_size_write(inode, size);
693         }
694         spin_unlock(&fc->lock);
695 }
696 
697 static void fuse_short_read(struct fuse_req *req, struct inode *inode,
698                             u64 attr_ver)
699 {
700         size_t num_read = req->out.args[0].size;
701         struct fuse_conn *fc = get_fuse_conn(inode);
702 
703         if (fc->writeback_cache) {
704                 /*
705                  * A hole in a file. Some data after the hole are in page cache,
706                  * but have not reached the client fs yet. So, the hole is not
707                  * present there.
708                  */
709                 int i;
710                 int start_idx = num_read >> PAGE_SHIFT;
711                 size_t off = num_read & (PAGE_SIZE - 1);
712 
713                 for (i = start_idx; i < req->num_pages; i++) {
714                         zero_user_segment(req->pages[i], off, PAGE_SIZE);
715                         off = 0;
716                 }
717         } else {
718                 loff_t pos = page_offset(req->pages[0]) + num_read;
719                 fuse_read_update_size(inode, pos, attr_ver);
720         }
721 }
722 
723 static int fuse_do_readpage(struct file *file, struct page *page)
724 {
725         struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
726         struct inode *inode = page->mapping->host;
727         struct fuse_conn *fc = get_fuse_conn(inode);
728         struct fuse_req *req;
729         size_t num_read;
730         loff_t pos = page_offset(page);
731         size_t count = PAGE_SIZE;
732         u64 attr_ver;
733         int err;
734 
735         /*
736          * Page writeback can extend beyond the lifetime of the
737          * page-cache page, so make sure we read a properly synced
738          * page.
739          */
740         fuse_wait_on_page_writeback(inode, page->index);
741 
742         req = fuse_get_req(fc, 1);
743         if (IS_ERR(req))
744                 return PTR_ERR(req);
745 
746         attr_ver = fuse_get_attr_version(fc);
747 
748         req->out.page_zeroing = 1;
749         req->out.argpages = 1;
750         req->num_pages = 1;
751         req->pages[0] = page;
752         req->page_descs[0].length = count;
753         num_read = fuse_send_read(req, &io, pos, count, NULL);
754         err = req->out.h.error;
755 
756         if (!err) {
757                 /*
758                  * Short read means EOF.  If file size is larger, truncate it
759                  */
760                 if (num_read < count)
761                         fuse_short_read(req, inode, attr_ver);
762 
763                 SetPageUptodate(page);
764         }
765 
766         fuse_put_request(fc, req);
767 
768         return err;
769 }
770 
771 static int fuse_readpage(struct file *file, struct page *page)
772 {
773         struct inode *inode = page->mapping->host;
774         int err;
775 
776         err = -EIO;
777         if (is_bad_inode(inode))
778                 goto out;
779 
780         err = fuse_do_readpage(file, page);
781         fuse_invalidate_atime(inode);
782  out:
783         unlock_page(page);
784         return err;
785 }
786 
787 static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_req *req)
788 {
789         int i;
790         size_t count = req->misc.read.in.size;
791         size_t num_read = req->out.args[0].size;
792         struct address_space *mapping = NULL;
793 
794         for (i = 0; mapping == NULL && i < req->num_pages; i++)
795                 mapping = req->pages[i]->mapping;
796 
797         if (mapping) {
798                 struct inode *inode = mapping->host;
799 
800                 /*
801                  * Short read means EOF. If file size is larger, truncate it
802                  */
803                 if (!req->out.h.error && num_read < count)
804                         fuse_short_read(req, inode, req->misc.read.attr_ver);
805 
806                 fuse_invalidate_atime(inode);
807         }
808 
809         for (i = 0; i < req->num_pages; i++) {
810                 struct page *page = req->pages[i];
811                 if (!req->out.h.error)
812                         SetPageUptodate(page);
813                 else
814                         SetPageError(page);
815                 unlock_page(page);
816                 put_page(page);
817         }
818         if (req->ff)
819                 fuse_file_put(req->ff, false);
820 }
821 
822 static void fuse_send_readpages(struct fuse_req *req, struct file *file)
823 {
824         struct fuse_file *ff = file->private_data;
825         struct fuse_conn *fc = ff->fc;
826         loff_t pos = page_offset(req->pages[0]);
827         size_t count = req->num_pages << PAGE_SHIFT;
828 
829         req->out.argpages = 1;
830         req->out.page_zeroing = 1;
831         req->out.page_replace = 1;
832         fuse_read_fill(req, file, pos, count, FUSE_READ);
833         req->misc.read.attr_ver = fuse_get_attr_version(fc);
834         if (fc->async_read) {
835                 req->ff = fuse_file_get(ff);
836                 req->end = fuse_readpages_end;
837                 fuse_request_send_background(fc, req);
838         } else {
839                 fuse_request_send(fc, req);
840                 fuse_readpages_end(fc, req);
841                 fuse_put_request(fc, req);
842         }
843 }
844 
845 struct fuse_fill_data {
846         struct fuse_req *req;
847         struct file *file;
848         struct inode *inode;
849         unsigned nr_pages;
850 };
851 
852 static int fuse_readpages_fill(void *_data, struct page *page)
853 {
854         struct fuse_fill_data *data = _data;
855         struct fuse_req *req = data->req;
856         struct inode *inode = data->inode;
857         struct fuse_conn *fc = get_fuse_conn(inode);
858 
859         fuse_wait_on_page_writeback(inode, page->index);
860 
861         if (req->num_pages &&
862             (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
863              (req->num_pages + 1) * PAGE_SIZE > fc->max_read ||
864              req->pages[req->num_pages - 1]->index + 1 != page->index)) {
865                 int nr_alloc = min_t(unsigned, data->nr_pages,
866                                      FUSE_MAX_PAGES_PER_REQ);
867                 fuse_send_readpages(req, data->file);
868                 if (fc->async_read)
869                         req = fuse_get_req_for_background(fc, nr_alloc);
870                 else
871                         req = fuse_get_req(fc, nr_alloc);
872 
873                 data->req = req;
874                 if (IS_ERR(req)) {
875                         unlock_page(page);
876                         return PTR_ERR(req);
877                 }
878         }
879 
880         if (WARN_ON(req->num_pages >= req->max_pages)) {
881                 fuse_put_request(fc, req);
882                 return -EIO;
883         }
884 
885         get_page(page);
886         req->pages[req->num_pages] = page;
887         req->page_descs[req->num_pages].length = PAGE_SIZE;
888         req->num_pages++;
889         data->nr_pages--;
890         return 0;
891 }
892 
893 static int fuse_readpages(struct file *file, struct address_space *mapping,
894                           struct list_head *pages, unsigned nr_pages)
895 {
896         struct inode *inode = mapping->host;
897         struct fuse_conn *fc = get_fuse_conn(inode);
898         struct fuse_fill_data data;
899         int err;
900         int nr_alloc = min_t(unsigned, nr_pages, FUSE_MAX_PAGES_PER_REQ);
901 
902         err = -EIO;
903         if (is_bad_inode(inode))
904                 goto out;
905 
906         data.file = file;
907         data.inode = inode;
908         if (fc->async_read)
909                 data.req = fuse_get_req_for_background(fc, nr_alloc);
910         else
911                 data.req = fuse_get_req(fc, nr_alloc);
912         data.nr_pages = nr_pages;
913         err = PTR_ERR(data.req);
914         if (IS_ERR(data.req))
915                 goto out;
916 
917         err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
918         if (!err) {
919                 if (data.req->num_pages)
920                         fuse_send_readpages(data.req, file);
921                 else
922                         fuse_put_request(fc, data.req);
923         }
924 out:
925         return err;
926 }
927 
928 static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
929 {
930         struct inode *inode = iocb->ki_filp->f_mapping->host;
931         struct fuse_conn *fc = get_fuse_conn(inode);
932 
933         /*
934          * In auto invalidate mode, always update attributes on read.
935          * Otherwise, only update if we attempt to read past EOF (to ensure
936          * i_size is up to date).
937          */
938         if (fc->auto_inval_data ||
939             (iocb->ki_pos + iov_iter_count(to) > i_size_read(inode))) {
940                 int err;
941                 err = fuse_update_attributes(inode, NULL, iocb->ki_filp, NULL);
942                 if (err)
943                         return err;
944         }
945 
946         return generic_file_read_iter(iocb, to);
947 }
948 
949 static void fuse_write_fill(struct fuse_req *req, struct fuse_file *ff,
950                             loff_t pos, size_t count)
951 {
952         struct fuse_write_in *inarg = &req->misc.write.in;
953         struct fuse_write_out *outarg = &req->misc.write.out;
954 
955         inarg->fh = ff->fh;
956         inarg->offset = pos;
957         inarg->size = count;
958         req->in.h.opcode = FUSE_WRITE;
959         req->in.h.nodeid = ff->nodeid;
960         req->in.numargs = 2;
961         if (ff->fc->minor < 9)
962                 req->in.args[0].size = FUSE_COMPAT_WRITE_IN_SIZE;
963         else
964                 req->in.args[0].size = sizeof(struct fuse_write_in);
965         req->in.args[0].value = inarg;
966         req->in.args[1].size = count;
967         req->out.numargs = 1;
968         req->out.args[0].size = sizeof(struct fuse_write_out);
969         req->out.args[0].value = outarg;
970 }
971 
972 static size_t fuse_send_write(struct fuse_req *req, struct fuse_io_priv *io,
973                               loff_t pos, size_t count, fl_owner_t owner)
974 {
975         struct file *file = io->file;
976         struct fuse_file *ff = file->private_data;
977         struct fuse_conn *fc = ff->fc;
978         struct fuse_write_in *inarg = &req->misc.write.in;
979 
980         fuse_write_fill(req, ff, pos, count);
981         inarg->flags = file->f_flags;
982         if (owner != NULL) {
983                 inarg->write_flags |= FUSE_WRITE_LOCKOWNER;
984                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
985         }
986 
987         if (io->async)
988                 return fuse_async_req_send(fc, req, count, io);
989 
990         fuse_request_send(fc, req);
991         return req->misc.write.out.size;
992 }
993 
994 bool fuse_write_update_size(struct inode *inode, loff_t pos)
995 {
996         struct fuse_conn *fc = get_fuse_conn(inode);
997         struct fuse_inode *fi = get_fuse_inode(inode);
998         bool ret = false;
999 
1000         spin_lock(&fc->lock);
1001         fi->attr_version = ++fc->attr_version;
1002         if (pos > inode->i_size) {
1003                 i_size_write(inode, pos);
1004                 ret = true;
1005         }
1006         spin_unlock(&fc->lock);
1007 
1008         return ret;
1009 }
1010 
1011 static size_t fuse_send_write_pages(struct fuse_req *req, struct file *file,
1012                                     struct inode *inode, loff_t pos,
1013                                     size_t count)
1014 {
1015         size_t res;
1016         unsigned offset;
1017         unsigned i;
1018         struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
1019 
1020         for (i = 0; i < req->num_pages; i++)
1021                 fuse_wait_on_page_writeback(inode, req->pages[i]->index);
1022 
1023         res = fuse_send_write(req, &io, pos, count, NULL);
1024 
1025         offset = req->page_descs[0].offset;
1026         count = res;
1027         for (i = 0; i < req->num_pages; i++) {
1028                 struct page *page = req->pages[i];
1029 
1030                 if (!req->out.h.error && !offset && count >= PAGE_SIZE)
1031                         SetPageUptodate(page);
1032 
1033                 if (count > PAGE_SIZE - offset)
1034                         count -= PAGE_SIZE - offset;
1035                 else
1036                         count = 0;
1037                 offset = 0;
1038 
1039                 unlock_page(page);
1040                 put_page(page);
1041         }
1042 
1043         return res;
1044 }
1045 
1046 static ssize_t fuse_fill_write_pages(struct fuse_req *req,
1047                                struct address_space *mapping,
1048                                struct iov_iter *ii, loff_t pos)
1049 {
1050         struct fuse_conn *fc = get_fuse_conn(mapping->host);
1051         unsigned offset = pos & (PAGE_SIZE - 1);
1052         size_t count = 0;
1053         int err;
1054 
1055         req->in.argpages = 1;
1056         req->page_descs[0].offset = offset;
1057 
1058         do {
1059                 size_t tmp;
1060                 struct page *page;
1061                 pgoff_t index = pos >> PAGE_SHIFT;
1062                 size_t bytes = min_t(size_t, PAGE_SIZE - offset,
1063                                      iov_iter_count(ii));
1064 
1065                 bytes = min_t(size_t, bytes, fc->max_write - count);
1066 
1067  again:
1068                 err = -EFAULT;
1069                 if (iov_iter_fault_in_readable(ii, bytes))
1070                         break;
1071 
1072                 err = -ENOMEM;
1073                 page = grab_cache_page_write_begin(mapping, index, 0);
1074                 if (!page)
1075                         break;
1076 
1077                 if (mapping_writably_mapped(mapping))
1078                         flush_dcache_page(page);
1079 
1080                 tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);
1081                 flush_dcache_page(page);
1082 
1083                 iov_iter_advance(ii, tmp);
1084                 if (!tmp) {
1085                         unlock_page(page);
1086                         put_page(page);
1087                         bytes = min(bytes, iov_iter_single_seg_count(ii));
1088                         goto again;
1089                 }
1090 
1091                 err = 0;
1092                 req->pages[req->num_pages] = page;
1093                 req->page_descs[req->num_pages].length = tmp;
1094                 req->num_pages++;
1095 
1096                 count += tmp;
1097                 pos += tmp;
1098                 offset += tmp;
1099                 if (offset == PAGE_SIZE)
1100                         offset = 0;
1101 
1102                 if (!fc->big_writes)
1103                         break;
1104         } while (iov_iter_count(ii) && count < fc->max_write &&
1105                  req->num_pages < req->max_pages && offset == 0);
1106 
1107         return count > 0 ? count : err;
1108 }
1109 
1110 static inline unsigned fuse_wr_pages(loff_t pos, size_t len)
1111 {
1112         return min_t(unsigned,
1113                      ((pos + len - 1) >> PAGE_SHIFT) -
1114                      (pos >> PAGE_SHIFT) + 1,
1115                      FUSE_MAX_PAGES_PER_REQ);
1116 }
1117 
1118 static ssize_t fuse_perform_write(struct file *file,
1119                                   struct address_space *mapping,
1120                                   struct iov_iter *ii, loff_t pos)
1121 {
1122         struct inode *inode = mapping->host;
1123         struct fuse_conn *fc = get_fuse_conn(inode);
1124         struct fuse_inode *fi = get_fuse_inode(inode);
1125         int err = 0;
1126         ssize_t res = 0;
1127 
1128         if (is_bad_inode(inode))
1129                 return -EIO;
1130 
1131         if (inode->i_size < pos + iov_iter_count(ii))
1132                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1133 
1134         do {
1135                 struct fuse_req *req;
1136                 ssize_t count;
1137                 unsigned nr_pages = fuse_wr_pages(pos, iov_iter_count(ii));
1138 
1139                 req = fuse_get_req(fc, nr_pages);
1140                 if (IS_ERR(req)) {
1141                         err = PTR_ERR(req);
1142                         break;
1143                 }
1144 
1145                 count = fuse_fill_write_pages(req, mapping, ii, pos);
1146                 if (count <= 0) {
1147                         err = count;
1148                 } else {
1149                         size_t num_written;
1150 
1151                         num_written = fuse_send_write_pages(req, file, inode,
1152                                                             pos, count);
1153                         err = req->out.h.error;
1154                         if (!err) {
1155                                 res += num_written;
1156                                 pos += num_written;
1157 
1158                                 /* break out of the loop on short write */
1159                                 if (num_written != count)
1160                                         err = -EIO;
1161                         }
1162                 }
1163                 fuse_put_request(fc, req);
1164         } while (!err && iov_iter_count(ii));
1165 
1166         if (res > 0)
1167                 fuse_write_update_size(inode, pos);
1168 
1169         clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1170         fuse_invalidate_attr(inode);
1171 
1172         return res > 0 ? res : err;
1173 }
1174 
1175 static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
1176 {
1177         struct file *file = iocb->ki_filp;
1178         struct address_space *mapping = file->f_mapping;
1179         ssize_t written = 0;
1180         ssize_t written_buffered = 0;
1181         struct inode *inode = mapping->host;
1182         ssize_t err;
1183         loff_t endbyte = 0;
1184 
1185         if (get_fuse_conn(inode)->writeback_cache) {
1186                 /* Update size (EOF optimization) and mode (SUID clearing) */
1187                 err = fuse_update_attributes(mapping->host, NULL, file, NULL);
1188                 if (err)
1189                         return err;
1190 
1191                 return generic_file_write_iter(iocb, from);
1192         }
1193 
1194         inode_lock(inode);
1195 
1196         /* We can write back this queue in page reclaim */
1197         current->backing_dev_info = inode_to_bdi(inode);
1198 
1199         err = generic_write_checks(iocb, from);
1200         if (err <= 0)
1201                 goto out;
1202 
1203         err = file_remove_privs(file);
1204         if (err)
1205                 goto out;
1206 
1207         err = file_update_time(file);
1208         if (err)
1209                 goto out;
1210 
1211         if (iocb->ki_flags & IOCB_DIRECT) {
1212                 loff_t pos = iocb->ki_pos;
1213                 written = generic_file_direct_write(iocb, from);
1214                 if (written < 0 || !iov_iter_count(from))
1215                         goto out;
1216 
1217                 pos += written;
1218 
1219                 written_buffered = fuse_perform_write(file, mapping, from, pos);
1220                 if (written_buffered < 0) {
1221                         err = written_buffered;
1222                         goto out;
1223                 }
1224                 endbyte = pos + written_buffered - 1;
1225 
1226                 err = filemap_write_and_wait_range(file->f_mapping, pos,
1227                                                    endbyte);
1228                 if (err)
1229                         goto out;
1230 
1231                 invalidate_mapping_pages(file->f_mapping,
1232                                          pos >> PAGE_SHIFT,
1233                                          endbyte >> PAGE_SHIFT);
1234 
1235                 written += written_buffered;
1236                 iocb->ki_pos = pos + written_buffered;
1237         } else {
1238                 written = fuse_perform_write(file, mapping, from, iocb->ki_pos);
1239                 if (written >= 0)
1240                         iocb->ki_pos += written;
1241         }
1242 out:
1243         current->backing_dev_info = NULL;
1244         inode_unlock(inode);
1245 
1246         return written ? written : err;
1247 }
1248 
1249 static inline void fuse_page_descs_length_init(struct fuse_req *req,
1250                 unsigned index, unsigned nr_pages)
1251 {
1252         int i;
1253 
1254         for (i = index; i < index + nr_pages; i++)
1255                 req->page_descs[i].length = PAGE_SIZE -
1256                         req->page_descs[i].offset;
1257 }
1258 
1259 static inline unsigned long fuse_get_user_addr(const struct iov_iter *ii)
1260 {
1261         return (unsigned long)ii->iov->iov_base + ii->iov_offset;
1262 }
1263 
1264 static inline size_t fuse_get_frag_size(const struct iov_iter *ii,
1265                                         size_t max_size)
1266 {
1267         return min(iov_iter_single_seg_count(ii), max_size);
1268 }
1269 
1270 static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
1271                                size_t *nbytesp, int write)
1272 {
1273         size_t nbytes = 0;  /* # bytes already packed in req */
1274         ssize_t ret = 0;
1275 
1276         /* Special case for kernel I/O: can copy directly into the buffer */
1277         if (ii->type & ITER_KVEC) {
1278                 unsigned long user_addr = fuse_get_user_addr(ii);
1279                 size_t frag_size = fuse_get_frag_size(ii, *nbytesp);
1280 
1281                 if (write)
1282                         req->in.args[1].value = (void *) user_addr;
1283                 else
1284                         req->out.args[0].value = (void *) user_addr;
1285 
1286                 iov_iter_advance(ii, frag_size);
1287                 *nbytesp = frag_size;
1288                 return 0;
1289         }
1290 
1291         while (nbytes < *nbytesp && req->num_pages < req->max_pages) {
1292                 unsigned npages;
1293                 size_t start;
1294                 ret = iov_iter_get_pages(ii, &req->pages[req->num_pages],
1295                                         *nbytesp - nbytes,
1296                                         req->max_pages - req->num_pages,
1297                                         &start);
1298                 if (ret < 0)
1299                         break;
1300 
1301                 iov_iter_advance(ii, ret);
1302                 nbytes += ret;
1303 
1304                 ret += start;
1305                 npages = (ret + PAGE_SIZE - 1) / PAGE_SIZE;
1306 
1307                 req->page_descs[req->num_pages].offset = start;
1308                 fuse_page_descs_length_init(req, req->num_pages, npages);
1309 
1310                 req->num_pages += npages;
1311                 req->page_descs[req->num_pages - 1].length -=
1312                         (PAGE_SIZE - ret) & (PAGE_SIZE - 1);
1313         }
1314 
1315         if (write)
1316                 req->in.argpages = 1;
1317         else
1318                 req->out.argpages = 1;
1319 
1320         *nbytesp = nbytes;
1321 
1322         return ret < 0 ? ret : 0;
1323 }
1324 
1325 static inline int fuse_iter_npages(const struct iov_iter *ii_p)
1326 {
1327         return iov_iter_npages(ii_p, FUSE_MAX_PAGES_PER_REQ);
1328 }
1329 
1330 ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
1331                        loff_t *ppos, int flags)
1332 {
1333         int write = flags & FUSE_DIO_WRITE;
1334         bool should_dirty = !write && iter_is_iovec(iter);
1335         int cuse = flags & FUSE_DIO_CUSE;
1336         struct file *file = io->file;
1337         struct inode *inode = file->f_mapping->host;
1338         struct fuse_file *ff = file->private_data;
1339         struct fuse_conn *fc = ff->fc;
1340         size_t nmax = write ? fc->max_write : fc->max_read;
1341         loff_t pos = *ppos;
1342         size_t count = iov_iter_count(iter);
1343         pgoff_t idx_from = pos >> PAGE_SHIFT;
1344         pgoff_t idx_to = (pos + count - 1) >> PAGE_SHIFT;
1345         ssize_t res = 0;
1346         struct fuse_req *req;
1347         int err = 0;
1348 
1349         if (io->async)
1350                 req = fuse_get_req_for_background(fc, fuse_iter_npages(iter));
1351         else
1352                 req = fuse_get_req(fc, fuse_iter_npages(iter));
1353         if (IS_ERR(req))
1354                 return PTR_ERR(req);
1355 
1356         if (!cuse && fuse_range_is_writeback(inode, idx_from, idx_to)) {
1357                 if (!write)
1358                         inode_lock(inode);
1359                 fuse_sync_writes(inode);
1360                 if (!write)
1361                         inode_unlock(inode);
1362         }
1363 
1364         while (count) {
1365                 size_t nres;
1366                 fl_owner_t owner = current->files;
1367                 size_t nbytes = min(count, nmax);
1368                 err = fuse_get_user_pages(req, iter, &nbytes, write);
1369                 if (err && !nbytes)
1370                         break;
1371 
1372                 if (write)
1373                         nres = fuse_send_write(req, io, pos, nbytes, owner);
1374                 else
1375                         nres = fuse_send_read(req, io, pos, nbytes, owner);
1376 
1377                 if (!io->async)
1378                         fuse_release_user_pages(req, should_dirty);
1379                 if (req->out.h.error) {
1380                         err = req->out.h.error;
1381                         break;
1382                 } else if (nres > nbytes) {
1383                         res = 0;
1384                         err = -EIO;
1385                         break;
1386                 }
1387                 count -= nres;
1388                 res += nres;
1389                 pos += nres;
1390                 if (nres != nbytes)
1391                         break;
1392                 if (count) {
1393                         fuse_put_request(fc, req);
1394                         if (io->async)
1395                                 req = fuse_get_req_for_background(fc,
1396                                         fuse_iter_npages(iter));
1397                         else
1398                                 req = fuse_get_req(fc, fuse_iter_npages(iter));
1399                         if (IS_ERR(req))
1400                                 break;
1401                 }
1402         }
1403         if (!IS_ERR(req))
1404                 fuse_put_request(fc, req);
1405         if (res > 0)
1406                 *ppos = pos;
1407 
1408         return res > 0 ? res : err;
1409 }
1410 EXPORT_SYMBOL_GPL(fuse_direct_io);
1411 
1412 static ssize_t __fuse_direct_read(struct fuse_io_priv *io,
1413                                   struct iov_iter *iter,
1414                                   loff_t *ppos)
1415 {
1416         ssize_t res;
1417         struct file *file = io->file;
1418         struct inode *inode = file_inode(file);
1419 
1420         if (is_bad_inode(inode))
1421                 return -EIO;
1422 
1423         res = fuse_direct_io(io, iter, ppos, 0);
1424 
1425         fuse_invalidate_attr(inode);
1426 
1427         return res;
1428 }
1429 
1430 static ssize_t fuse_direct_read_iter(struct kiocb *iocb, struct iov_iter *to)
1431 {
1432         struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb->ki_filp);
1433         return __fuse_direct_read(&io, to, &iocb->ki_pos);
1434 }
1435 
1436 static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
1437 {
1438         struct file *file = iocb->ki_filp;
1439         struct inode *inode = file_inode(file);
1440         struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
1441         ssize_t res;
1442 
1443         if (is_bad_inode(inode))
1444                 return -EIO;
1445 
1446         /* Don't allow parallel writes to the same file */
1447         inode_lock(inode);
1448         res = generic_write_checks(iocb, from);
1449         if (res > 0)
1450                 res = fuse_direct_io(&io, from, &iocb->ki_pos, FUSE_DIO_WRITE);
1451         fuse_invalidate_attr(inode);
1452         if (res > 0)
1453                 fuse_write_update_size(inode, iocb->ki_pos);
1454         inode_unlock(inode);
1455 
1456         return res;
1457 }
1458 
1459 static void fuse_writepage_free(struct fuse_conn *fc, struct fuse_req *req)
1460 {
1461         int i;
1462 
1463         for (i = 0; i < req->num_pages; i++)
1464                 __free_page(req->pages[i]);
1465 
1466         if (req->ff)
1467                 fuse_file_put(req->ff, false);
1468 }
1469 
1470 static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
1471 {
1472         struct inode *inode = req->inode;
1473         struct fuse_inode *fi = get_fuse_inode(inode);
1474         struct backing_dev_info *bdi = inode_to_bdi(inode);
1475         int i;
1476 
1477         list_del(&req->writepages_entry);
1478         for (i = 0; i < req->num_pages; i++) {
1479                 dec_wb_stat(&bdi->wb, WB_WRITEBACK);
1480                 dec_zone_page_state(req->pages[i], NR_WRITEBACK_TEMP);
1481                 wb_writeout_inc(&bdi->wb);
1482         }
1483         wake_up(&fi->page_waitq);
1484 }
1485 
1486 /* Called under fc->lock, may release and reacquire it */
1487 static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req,
1488                                 loff_t size)
1489 __releases(fc->lock)
1490 __acquires(fc->lock)
1491 {
1492         struct fuse_inode *fi = get_fuse_inode(req->inode);
1493         struct fuse_write_in *inarg = &req->misc.write.in;
1494         __u64 data_size = req->num_pages * PAGE_SIZE;
1495 
1496         if (!fc->connected)
1497                 goto out_free;
1498 
1499         if (inarg->offset + data_size <= size) {
1500                 inarg->size = data_size;
1501         } else if (inarg->offset < size) {
1502                 inarg->size = size - inarg->offset;
1503         } else {
1504                 /* Got truncated off completely */
1505                 goto out_free;
1506         }
1507 
1508         req->in.args[1].size = inarg->size;
1509         fi->writectr++;
1510         fuse_request_send_background_locked(fc, req);
1511         return;
1512 
1513  out_free:
1514         fuse_writepage_finish(fc, req);
1515         spin_unlock(&fc->lock);
1516         fuse_writepage_free(fc, req);
1517         fuse_put_request(fc, req);
1518         spin_lock(&fc->lock);
1519 }
1520 
1521 /*
1522  * If fi->writectr is positive (no truncate or fsync going on) send
1523  * all queued writepage requests.
1524  *
1525  * Called with fc->lock
1526  */
1527 void fuse_flush_writepages(struct inode *inode)
1528 __releases(fc->lock)
1529 __acquires(fc->lock)
1530 {
1531         struct fuse_conn *fc = get_fuse_conn(inode);
1532         struct fuse_inode *fi = get_fuse_inode(inode);
1533         size_t crop = i_size_read(inode);
1534         struct fuse_req *req;
1535 
1536         while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) {
1537                 req = list_entry(fi->queued_writes.next, struct fuse_req, list);
1538                 list_del_init(&req->list);
1539                 fuse_send_writepage(fc, req, crop);
1540         }
1541 }
1542 
1543 static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req)
1544 {
1545         struct inode *inode = req->inode;
1546         struct fuse_inode *fi = get_fuse_inode(inode);
1547 
1548         mapping_set_error(inode->i_mapping, req->out.h.error);
1549         spin_lock(&fc->lock);
1550         while (req->misc.write.next) {
1551                 struct fuse_conn *fc = get_fuse_conn(inode);
1552                 struct fuse_write_in *inarg = &req->misc.write.in;
1553                 struct fuse_req *next = req->misc.write.next;
1554                 req->misc.write.next = next->misc.write.next;
1555                 next->misc.write.next = NULL;
1556                 next->ff = fuse_file_get(req->ff);
1557                 list_add(&next->writepages_entry, &fi->writepages);
1558 
1559                 /*
1560                  * Skip fuse_flush_writepages() to make it easy to crop requests
1561                  * based on primary request size.
1562                  *
1563                  * 1st case (trivial): there are no concurrent activities using
1564                  * fuse_set/release_nowrite.  Then we're on safe side because
1565                  * fuse_flush_writepages() would call fuse_send_writepage()
1566                  * anyway.
1567                  *
1568                  * 2nd case: someone called fuse_set_nowrite and it is waiting
1569                  * now for completion of all in-flight requests.  This happens
1570                  * rarely and no more than once per page, so this should be
1571                  * okay.
1572                  *
1573                  * 3rd case: someone (e.g. fuse_do_setattr()) is in the middle
1574                  * of fuse_set_nowrite..fuse_release_nowrite section.  The fact
1575                  * that fuse_set_nowrite returned implies that all in-flight
1576                  * requests were completed along with all of their secondary
1577                  * requests.  Further primary requests are blocked by negative
1578                  * writectr.  Hence there cannot be any in-flight requests and
1579                  * no invocations of fuse_writepage_end() while we're in
1580                  * fuse_set_nowrite..fuse_release_nowrite section.
1581                  */
1582                 fuse_send_writepage(fc, next, inarg->offset + inarg->size);
1583         }
1584         fi->writectr--;
1585         fuse_writepage_finish(fc, req);
1586         spin_unlock(&fc->lock);
1587         fuse_writepage_free(fc, req);
1588 }
1589 
1590 static struct fuse_file *__fuse_write_file_get(struct fuse_conn *fc,
1591                                                struct fuse_inode *fi)
1592 {
1593         struct fuse_file *ff = NULL;
1594 
1595         spin_lock(&fc->lock);
1596         if (!list_empty(&fi->write_files)) {
1597                 ff = list_entry(fi->write_files.next, struct fuse_file,
1598                                 write_entry);
1599                 fuse_file_get(ff);
1600         }
1601         spin_unlock(&fc->lock);
1602 
1603         return ff;
1604 }
1605 
1606 static struct fuse_file *fuse_write_file_get(struct fuse_conn *fc,
1607                                              struct fuse_inode *fi)
1608 {
1609         struct fuse_file *ff = __fuse_write_file_get(fc, fi);
1610         WARN_ON(!ff);
1611         return ff;
1612 }
1613 
1614 int fuse_write_inode(struct inode *inode, struct writeback_control *wbc)
1615 {
1616         struct fuse_conn *fc = get_fuse_conn(inode);
1617         struct fuse_inode *fi = get_fuse_inode(inode);
1618         struct fuse_file *ff;
1619         int err;
1620 
1621         ff = __fuse_write_file_get(fc, fi);
1622         err = fuse_flush_times(inode, ff);
1623         if (ff)
1624                 fuse_file_put(ff, 0);
1625 
1626         return err;
1627 }
1628 
1629 static int fuse_writepage_locked(struct page *page)
1630 {
1631         struct address_space *mapping = page->mapping;
1632         struct inode *inode = mapping->host;
1633         struct fuse_conn *fc = get_fuse_conn(inode);
1634         struct fuse_inode *fi = get_fuse_inode(inode);
1635         struct fuse_req *req;
1636         struct page *tmp_page;
1637         int error = -ENOMEM;
1638 
1639         set_page_writeback(page);
1640 
1641         req = fuse_request_alloc_nofs(1);
1642         if (!req)
1643                 goto err;
1644 
1645         /* writeback always goes to bg_queue */
1646         __set_bit(FR_BACKGROUND, &req->flags);
1647         tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
1648         if (!tmp_page)
1649                 goto err_free;
1650 
1651         error = -EIO;
1652         req->ff = fuse_write_file_get(fc, fi);
1653         if (!req->ff)
1654                 goto err_nofile;
1655 
1656         fuse_write_fill(req, req->ff, page_offset(page), 0);
1657 
1658         copy_highpage(tmp_page, page);
1659         req->misc.write.in.write_flags |= FUSE_WRITE_CACHE;
1660         req->misc.write.next = NULL;
1661         req->in.argpages = 1;
1662         req->num_pages = 1;
1663         req->pages[0] = tmp_page;
1664         req->page_descs[0].offset = 0;
1665         req->page_descs[0].length = PAGE_SIZE;
1666         req->end = fuse_writepage_end;
1667         req->inode = inode;
1668 
1669         inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
1670         inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
1671 
1672         spin_lock(&fc->lock);
1673         list_add(&req->writepages_entry, &fi->writepages);
1674         list_add_tail(&req->list, &fi->queued_writes);
1675         fuse_flush_writepages(inode);
1676         spin_unlock(&fc->lock);
1677 
1678         end_page_writeback(page);
1679 
1680         return 0;
1681 
1682 err_nofile:
1683         __free_page(tmp_page);
1684 err_free:
1685         fuse_request_free(req);
1686 err:
1687         end_page_writeback(page);
1688         return error;
1689 }
1690 
1691 static int fuse_writepage(struct page *page, struct writeback_control *wbc)
1692 {
1693         int err;
1694 
1695         if (fuse_page_is_writeback(page->mapping->host, page->index)) {
1696                 /*
1697                  * ->writepages() should be called for sync() and friends.  We
1698                  * should only get here on direct reclaim and then we are
1699                  * allowed to skip a page which is already in flight
1700                  */
1701                 WARN_ON(wbc->sync_mode == WB_SYNC_ALL);
1702 
1703                 redirty_page_for_writepage(wbc, page);
1704                 return 0;
1705         }
1706 
1707         err = fuse_writepage_locked(page);
1708         unlock_page(page);
1709 
1710         return err;
1711 }
1712 
1713 struct fuse_fill_wb_data {
1714         struct fuse_req *req;
1715         struct fuse_file *ff;
1716         struct inode *inode;
1717         struct page **orig_pages;
1718 };
1719 
1720 static void fuse_writepages_send(struct fuse_fill_wb_data *data)
1721 {
1722         struct fuse_req *req = data->req;
1723         struct inode *inode = data->inode;
1724         struct fuse_conn *fc = get_fuse_conn(inode);
1725         struct fuse_inode *fi = get_fuse_inode(inode);
1726         int num_pages = req->num_pages;
1727         int i;
1728 
1729         req->ff = fuse_file_get(data->ff);
1730         spin_lock(&fc->lock);
1731         list_add_tail(&req->list, &fi->queued_writes);
1732         fuse_flush_writepages(inode);
1733         spin_unlock(&fc->lock);
1734 
1735         for (i = 0; i < num_pages; i++)
1736                 end_page_writeback(data->orig_pages[i]);
1737 }
1738 
1739 static bool fuse_writepage_in_flight(struct fuse_req *new_req,
1740                                      struct page *page)
1741 {
1742         struct fuse_conn *fc = get_fuse_conn(new_req->inode);
1743         struct fuse_inode *fi = get_fuse_inode(new_req->inode);
1744         struct fuse_req *tmp;
1745         struct fuse_req *old_req;
1746         bool found = false;
1747         pgoff_t curr_index;
1748 
1749         BUG_ON(new_req->num_pages != 0);
1750 
1751         spin_lock(&fc->lock);
1752         list_del(&new_req->writepages_entry);
1753         list_for_each_entry(old_req, &fi->writepages, writepages_entry) {
1754                 BUG_ON(old_req->inode != new_req->inode);
1755                 curr_index = old_req->misc.write.in.offset >> PAGE_SHIFT;
1756                 if (curr_index <= page->index &&
1757                     page->index < curr_index + old_req->num_pages) {
1758                         found = true;
1759                         break;
1760                 }
1761         }
1762         if (!found) {
1763                 list_add(&new_req->writepages_entry, &fi->writepages);
1764                 goto out_unlock;
1765         }
1766 
1767         new_req->num_pages = 1;
1768         for (tmp = old_req; tmp != NULL; tmp = tmp->misc.write.next) {
1769                 BUG_ON(tmp->inode != new_req->inode);
1770                 curr_index = tmp->misc.write.in.offset >> PAGE_SHIFT;
1771                 if (tmp->num_pages == 1 &&
1772                     curr_index == page->index) {
1773                         old_req = tmp;
1774                 }
1775         }
1776 
1777         if (old_req->num_pages == 1 && test_bit(FR_PENDING, &old_req->flags)) {
1778                 struct backing_dev_info *bdi = inode_to_bdi(page->mapping->host);
1779 
1780                 copy_highpage(old_req->pages[0], page);
1781                 spin_unlock(&fc->lock);
1782 
1783                 dec_wb_stat(&bdi->wb, WB_WRITEBACK);
1784                 dec_zone_page_state(page, NR_WRITEBACK_TEMP);
1785                 wb_writeout_inc(&bdi->wb);
1786                 fuse_writepage_free(fc, new_req);
1787                 fuse_request_free(new_req);
1788                 goto out;
1789         } else {
1790                 new_req->misc.write.next = old_req->misc.write.next;
1791                 old_req->misc.write.next = new_req;
1792         }
1793 out_unlock:
1794         spin_unlock(&fc->lock);
1795 out:
1796         return found;
1797 }
1798 
1799 static int fuse_writepages_fill(struct page *page,
1800                 struct writeback_control *wbc, void *_data)
1801 {
1802         struct fuse_fill_wb_data *data = _data;
1803         struct fuse_req *req = data->req;
1804         struct inode *inode = data->inode;
1805         struct fuse_conn *fc = get_fuse_conn(inode);
1806         struct page *tmp_page;
1807         bool is_writeback;
1808         int err;
1809 
1810         if (!data->ff) {
1811                 err = -EIO;
1812                 data->ff = fuse_write_file_get(fc, get_fuse_inode(inode));
1813                 if (!data->ff)
1814                         goto out_unlock;
1815         }
1816 
1817         /*
1818          * Being under writeback is unlikely but possible.  For example direct
1819          * read to an mmaped fuse file will set the page dirty twice; once when
1820          * the pages are faulted with get_user_pages(), and then after the read
1821          * completed.
1822          */
1823         is_writeback = fuse_page_is_writeback(inode, page->index);
1824 
1825         if (req && req->num_pages &&
1826             (is_writeback || req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
1827              (req->num_pages + 1) * PAGE_SIZE > fc->max_write ||
1828              data->orig_pages[req->num_pages - 1]->index + 1 != page->index)) {
1829                 fuse_writepages_send(data);
1830                 data->req = NULL;
1831         }
1832         err = -ENOMEM;
1833         tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
1834         if (!tmp_page)
1835                 goto out_unlock;
1836 
1837         /*
1838          * The page must not be redirtied until the writeout is completed
1839          * (i.e. userspace has sent a reply to the write request).  Otherwise
1840          * there could be more than one temporary page instance for each real
1841          * page.
1842          *
1843          * This is ensured by holding the page lock in page_mkwrite() while
1844          * checking fuse_page_is_writeback().  We already hold the page lock
1845          * since clear_page_dirty_for_io() and keep it held until we add the
1846          * request to the fi->writepages list and increment req->num_pages.
1847          * After this fuse_page_is_writeback() will indicate that the page is
1848          * under writeback, so we can release the page lock.
1849          */
1850         if (data->req == NULL) {
1851                 struct fuse_inode *fi = get_fuse_inode(inode);
1852 
1853                 err = -ENOMEM;
1854                 req = fuse_request_alloc_nofs(FUSE_MAX_PAGES_PER_REQ);
1855                 if (!req) {
1856                         __free_page(tmp_page);
1857                         goto out_unlock;
1858                 }
1859 
1860                 fuse_write_fill(req, data->ff, page_offset(page), 0);
1861                 req->misc.write.in.write_flags |= FUSE_WRITE_CACHE;
1862                 req->misc.write.next = NULL;
1863                 req->in.argpages = 1;
1864                 __set_bit(FR_BACKGROUND, &req->flags);
1865                 req->num_pages = 0;
1866                 req->end = fuse_writepage_end;
1867                 req->inode = inode;
1868 
1869                 spin_lock(&fc->lock);
1870                 list_add(&req->writepages_entry, &fi->writepages);
1871                 spin_unlock(&fc->lock);
1872 
1873                 data->req = req;
1874         }
1875         set_page_writeback(page);
1876 
1877         copy_highpage(tmp_page, page);
1878         req->pages[req->num_pages] = tmp_page;
1879         req->page_descs[req->num_pages].offset = 0;
1880         req->page_descs[req->num_pages].length = PAGE_SIZE;
1881 
1882         inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
1883         inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
1884 
1885         err = 0;
1886         if (is_writeback && fuse_writepage_in_flight(req, page)) {
1887                 end_page_writeback(page);
1888                 data->req = NULL;
1889                 goto out_unlock;
1890         }
1891         data->orig_pages[req->num_pages] = page;
1892 
1893         /*
1894          * Protected by fc->lock against concurrent access by
1895          * fuse_page_is_writeback().
1896          */
1897         spin_lock(&fc->lock);
1898         req->num_pages++;
1899         spin_unlock(&fc->lock);
1900 
1901 out_unlock:
1902         unlock_page(page);
1903 
1904         return err;
1905 }
1906 
1907 static int fuse_writepages(struct address_space *mapping,
1908                            struct writeback_control *wbc)
1909 {
1910         struct inode *inode = mapping->host;
1911         struct fuse_fill_wb_data data;
1912         int err;
1913 
1914         err = -EIO;
1915         if (is_bad_inode(inode))
1916                 goto out;
1917 
1918         data.inode = inode;
1919         data.req = NULL;
1920         data.ff = NULL;
1921 
1922         err = -ENOMEM;
1923         data.orig_pages = kcalloc(FUSE_MAX_PAGES_PER_REQ,
1924                                   sizeof(struct page *),
1925                                   GFP_NOFS);
1926         if (!data.orig_pages)
1927                 goto out;
1928 
1929         err = write_cache_pages(mapping, wbc, fuse_writepages_fill, &data);
1930         if (data.req) {
1931                 /* Ignore errors if we can write at least one page */
1932                 BUG_ON(!data.req->num_pages);
1933                 fuse_writepages_send(&data);
1934                 err = 0;
1935         }
1936         if (data.ff)
1937                 fuse_file_put(data.ff, false);
1938 
1939         kfree(data.orig_pages);
1940 out:
1941         return err;
1942 }
1943 
1944 /*
1945  * It's worthy to make sure that space is reserved on disk for the write,
1946  * but how to implement it without killing performance need more thinking.
1947  */
1948 static int fuse_write_begin(struct file *file, struct address_space *mapping,
1949                 loff_t pos, unsigned len, unsigned flags,
1950                 struct page **pagep, void **fsdata)
1951 {
1952         pgoff_t index = pos >> PAGE_SHIFT;
1953         struct fuse_conn *fc = get_fuse_conn(file_inode(file));
1954         struct page *page;
1955         loff_t fsize;
1956         int err = -ENOMEM;
1957 
1958         WARN_ON(!fc->writeback_cache);
1959 
1960         page = grab_cache_page_write_begin(mapping, index, flags);
1961         if (!page)
1962                 goto error;
1963 
1964         fuse_wait_on_page_writeback(mapping->host, page->index);
1965 
1966         if (PageUptodate(page) || len == PAGE_SIZE)
1967                 goto success;
1968         /*
1969          * Check if the start this page comes after the end of file, in which
1970          * case the readpage can be optimized away.
1971          */
1972         fsize = i_size_read(mapping->host);
1973         if (fsize <= (pos & PAGE_MASK)) {
1974                 size_t off = pos & ~PAGE_MASK;
1975                 if (off)
1976                         zero_user_segment(page, 0, off);
1977                 goto success;
1978         }
1979         err = fuse_do_readpage(file, page);
1980         if (err)
1981                 goto cleanup;
1982 success:
1983         *pagep = page;
1984         return 0;
1985 
1986 cleanup:
1987         unlock_page(page);
1988         put_page(page);
1989 error:
1990         return err;
1991 }
1992 
1993 static int fuse_write_end(struct file *file, struct address_space *mapping,
1994                 loff_t pos, unsigned len, unsigned copied,
1995                 struct page *page, void *fsdata)
1996 {
1997         struct inode *inode = page->mapping->host;
1998 
1999         if (!PageUptodate(page)) {
2000                 /* Zero any unwritten bytes at the end of the page */
2001                 size_t endoff = (pos + copied) & ~PAGE_MASK;
2002                 if (endoff)
2003                         zero_user_segment(page, endoff, PAGE_SIZE);
2004                 SetPageUptodate(page);
2005         }
2006 
2007         fuse_write_update_size(inode, pos + copied);
2008         set_page_dirty(page);
2009         unlock_page(page);
2010         put_page(page);
2011 
2012         return copied;
2013 }
2014 
2015 static int fuse_launder_page(struct page *page)
2016 {
2017         int err = 0;
2018         if (clear_page_dirty_for_io(page)) {
2019                 struct inode *inode = page->mapping->host;
2020                 err = fuse_writepage_locked(page);
2021                 if (!err)
2022                         fuse_wait_on_page_writeback(inode, page->index);
2023         }
2024         return err;
2025 }
2026 
2027 /*
2028  * Write back dirty pages now, because there may not be any suitable
2029  * open files later
2030  */
2031 static void fuse_vma_close(struct vm_area_struct *vma)
2032 {
2033         filemap_write_and_wait(vma->vm_file->f_mapping);
2034 }
2035 
2036 /*
2037  * Wait for writeback against this page to complete before allowing it
2038  * to be marked dirty again, and hence written back again, possibly
2039  * before the previous writepage completed.
2040  *
2041  * Block here, instead of in ->writepage(), so that the userspace fs
2042  * can only block processes actually operating on the filesystem.
2043  *
2044  * Otherwise unprivileged userspace fs would be able to block
2045  * unrelated:
2046  *
2047  * - page migration
2048  * - sync(2)
2049  * - try_to_free_pages() with order > PAGE_ALLOC_COSTLY_ORDER
2050  */
2051 static int fuse_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
2052 {
2053         struct page *page = vmf->page;
2054         struct inode *inode = file_inode(vma->vm_file);
2055 
2056         file_update_time(vma->vm_file);
2057         lock_page(page);
2058         if (page->mapping != inode->i_mapping) {
2059                 unlock_page(page);
2060                 return VM_FAULT_NOPAGE;
2061         }
2062 
2063         fuse_wait_on_page_writeback(inode, page->index);
2064         return VM_FAULT_LOCKED;
2065 }
2066 
2067 static const struct vm_operations_struct fuse_file_vm_ops = {
2068         .close          = fuse_vma_close,
2069         .fault          = filemap_fault,
2070         .map_pages      = filemap_map_pages,
2071         .page_mkwrite   = fuse_page_mkwrite,
2072 };
2073 
2074 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
2075 {
2076         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
2077                 fuse_link_write_file(file);
2078 
2079         file_accessed(file);
2080         vma->vm_ops = &fuse_file_vm_ops;
2081         return 0;
2082 }
2083 
2084 static int fuse_direct_mmap(struct file *file, struct vm_area_struct *vma)
2085 {
2086         /* Can't provide the coherency needed for MAP_SHARED */
2087         if (vma->vm_flags & VM_MAYSHARE)
2088                 return -ENODEV;
2089 
2090         invalidate_inode_pages2(file->f_mapping);
2091 
2092         return generic_file_mmap(file, vma);
2093 }
2094 
2095 static int convert_fuse_file_lock(const struct fuse_file_lock *ffl,
2096                                   struct file_lock *fl)
2097 {
2098         switch (ffl->type) {
2099         case F_UNLCK:
2100                 break;
2101 
2102         case F_RDLCK:
2103         case F_WRLCK:
2104                 if (ffl->start > OFFSET_MAX || ffl->end > OFFSET_MAX ||
2105                     ffl->end < ffl->start)
2106                         return -EIO;
2107 
2108                 fl->fl_start = ffl->start;
2109                 fl->fl_end = ffl->end;
2110                 fl->fl_pid = ffl->pid;
2111                 break;
2112 
2113         default:
2114                 return -EIO;
2115         }
2116         fl->fl_type = ffl->type;
2117         return 0;
2118 }
2119 
2120 static void fuse_lk_fill(struct fuse_args *args, struct file *file,
2121                          const struct file_lock *fl, int opcode, pid_t pid,
2122                          int flock, struct fuse_lk_in *inarg)
2123 {
2124         struct inode *inode = file_inode(file);
2125         struct fuse_conn *fc = get_fuse_conn(inode);
2126         struct fuse_file *ff = file->private_data;
2127 
2128         memset(inarg, 0, sizeof(*inarg));
2129         inarg->fh = ff->fh;
2130         inarg->owner = fuse_lock_owner_id(fc, fl->fl_owner);
2131         inarg->lk.start = fl->fl_start;
2132         inarg->lk.end = fl->fl_end;
2133         inarg->lk.type = fl->fl_type;
2134         inarg->lk.pid = pid;
2135         if (flock)
2136                 inarg->lk_flags |= FUSE_LK_FLOCK;
2137         args->in.h.opcode = opcode;
2138         args->in.h.nodeid = get_node_id(inode);
2139         args->in.numargs = 1;
2140         args->in.args[0].size = sizeof(*inarg);
2141         args->in.args[0].value = inarg;
2142 }
2143 
2144 static int fuse_getlk(struct file *file, struct file_lock *fl)
2145 {
2146         struct inode *inode = file_inode(file);
2147         struct fuse_conn *fc = get_fuse_conn(inode);
2148         FUSE_ARGS(args);
2149         struct fuse_lk_in inarg;
2150         struct fuse_lk_out outarg;
2151         int err;
2152 
2153         fuse_lk_fill(&args, file, fl, FUSE_GETLK, 0, 0, &inarg);
2154         args.out.numargs = 1;
2155         args.out.args[0].size = sizeof(outarg);
2156         args.out.args[0].value = &outarg;
2157         err = fuse_simple_request(fc, &args);
2158         if (!err)
2159                 err = convert_fuse_file_lock(&outarg.lk, fl);
2160 
2161         return err;
2162 }
2163 
2164 static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
2165 {
2166         struct inode *inode = file_inode(file);
2167         struct fuse_conn *fc = get_fuse_conn(inode);
2168         FUSE_ARGS(args);
2169         struct fuse_lk_in inarg;
2170         int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
2171         pid_t pid = fl->fl_type != F_UNLCK ? current->tgid : 0;
2172         int err;
2173 
2174         if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
2175                 /* NLM needs asynchronous locks, which we don't support yet */
2176                 return -ENOLCK;
2177         }
2178 
2179         /* Unlock on close is handled by the flush method */
2180         if (fl->fl_flags & FL_CLOSE)
2181                 return 0;
2182 
2183         fuse_lk_fill(&args, file, fl, opcode, pid, flock, &inarg);
2184         err = fuse_simple_request(fc, &args);
2185 
2186         /* locking is restartable */
2187         if (err == -EINTR)
2188                 err = -ERESTARTSYS;
2189 
2190         return err;
2191 }
2192 
2193 static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
2194 {
2195         struct inode *inode = file_inode(file);
2196         struct fuse_conn *fc = get_fuse_conn(inode);
2197         int err;
2198 
2199         if (cmd == F_CANCELLK) {
2200                 err = 0;
2201         } else if (cmd == F_GETLK) {
2202                 if (fc->no_lock) {
2203                         posix_test_lock(file, fl);
2204                         err = 0;
2205                 } else
2206                         err = fuse_getlk(file, fl);
2207         } else {
2208                 if (fc->no_lock)
2209                         err = posix_lock_file(file, fl, NULL);
2210                 else
2211                         err = fuse_setlk(file, fl, 0);
2212         }
2213         return err;
2214 }
2215 
2216 static int fuse_file_flock(struct file *file, int cmd, struct file_lock *fl)
2217 {
2218         struct inode *inode = file_inode(file);
2219         struct fuse_conn *fc = get_fuse_conn(inode);
2220         int err;
2221 
2222         if (fc->no_flock) {
2223                 err = locks_lock_file_wait(file, fl);
2224         } else {
2225                 struct fuse_file *ff = file->private_data;
2226 
2227                 /* emulate flock with POSIX locks */
2228                 ff->flock = true;
2229                 err = fuse_setlk(file, fl, 1);
2230         }
2231 
2232         return err;
2233 }
2234 
2235 static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
2236 {
2237         struct inode *inode = mapping->host;
2238         struct fuse_conn *fc = get_fuse_conn(inode);
2239         FUSE_ARGS(args);
2240         struct fuse_bmap_in inarg;
2241         struct fuse_bmap_out outarg;
2242         int err;
2243 
2244         if (!inode->i_sb->s_bdev || fc->no_bmap)
2245                 return 0;
2246 
2247         memset(&inarg, 0, sizeof(inarg));
2248         inarg.block = block;
2249         inarg.blocksize = inode->i_sb->s_blocksize;
2250         args.in.h.opcode = FUSE_BMAP;
2251         args.in.h.nodeid = get_node_id(inode);
2252         args.in.numargs = 1;
2253         args.in.args[0].size = sizeof(inarg);
2254         args.in.args[0].value = &inarg;
2255         args.out.numargs = 1;
2256         args.out.args[0].size = sizeof(outarg);
2257         args.out.args[0].value = &outarg;
2258         err = fuse_simple_request(fc, &args);
2259         if (err == -ENOSYS)
2260                 fc->no_bmap = 1;
2261 
2262         return err ? 0 : outarg.block;
2263 }
2264 
2265 static loff_t fuse_lseek(struct file *file, loff_t offset, int whence)
2266 {
2267         struct inode *inode = file->f_mapping->host;
2268         struct fuse_conn *fc = get_fuse_conn(inode);
2269         struct fuse_file *ff = file->private_data;
2270         FUSE_ARGS(args);
2271         struct fuse_lseek_in inarg = {
2272                 .fh = ff->fh,
2273                 .offset = offset,
2274                 .whence = whence
2275         };
2276         struct fuse_lseek_out outarg;
2277         int err;
2278 
2279         if (fc->no_lseek)
2280                 goto fallback;
2281 
2282         args.in.h.opcode = FUSE_LSEEK;
2283         args.in.h.nodeid = ff->nodeid;
2284         args.in.numargs = 1;
2285         args.in.args[0].size = sizeof(inarg);
2286         args.in.args[0].value = &inarg;
2287         args.out.numargs = 1;
2288         args.out.args[0].size = sizeof(outarg);
2289         args.out.args[0].value = &outarg;
2290         err = fuse_simple_request(fc, &args);
2291         if (err) {
2292                 if (err == -ENOSYS) {
2293                         fc->no_lseek = 1;
2294                         goto fallback;
2295                 }
2296                 return err;
2297         }
2298 
2299         return vfs_setpos(file, outarg.offset, inode->i_sb->s_maxbytes);
2300 
2301 fallback:
2302         err = fuse_update_attributes(inode, NULL, file, NULL);
2303         if (!err)
2304                 return generic_file_llseek(file, offset, whence);
2305         else
2306                 return err;
2307 }
2308 
2309 static loff_t fuse_file_llseek(struct file *file, loff_t offset, int whence)
2310 {
2311         loff_t retval;
2312         struct inode *inode = file_inode(file);
2313 
2314         switch (whence) {
2315         case SEEK_SET:
2316         case SEEK_CUR:
2317                  /* No i_mutex protection necessary for SEEK_CUR and SEEK_SET */
2318                 retval = generic_file_llseek(file, offset, whence);
2319                 break;
2320         case SEEK_END:
2321                 inode_lock(inode);
2322                 retval = fuse_update_attributes(inode, NULL, file, NULL);
2323                 if (!retval)
2324                         retval = generic_file_llseek(file, offset, whence);
2325                 inode_unlock(inode);
2326                 break;
2327         case SEEK_HOLE:
2328         case SEEK_DATA:
2329                 inode_lock(inode);
2330                 retval = fuse_lseek(file, offset, whence);
2331                 inode_unlock(inode);
2332                 break;
2333         default:
2334                 retval = -EINVAL;
2335         }
2336 
2337         return retval;
2338 }
2339 
2340 static int fuse_ioctl_copy_user(struct page **pages, struct iovec *iov,
2341                         unsigned int nr_segs, size_t bytes, bool to_user)
2342 {
2343         struct iov_iter ii;
2344         int page_idx = 0;
2345 
2346         if (!bytes)
2347                 return 0;
2348 
2349         iov_iter_init(&ii, to_user ? READ : WRITE, iov, nr_segs, bytes);
2350 
2351         while (iov_iter_count(&ii)) {
2352                 struct page *page = pages[page_idx++];
2353                 size_t todo = min_t(size_t, PAGE_SIZE, iov_iter_count(&ii));
2354                 void *kaddr;
2355 
2356                 kaddr = kmap(page);
2357 
2358                 while (todo) {
2359                         char __user *uaddr = ii.iov->iov_base + ii.iov_offset;
2360                         size_t iov_len = ii.iov->iov_len - ii.iov_offset;
2361                         size_t copy = min(todo, iov_len);
2362                         size_t left;
2363 
2364                         if (!to_user)
2365                                 left = copy_from_user(kaddr, uaddr, copy);
2366                         else
2367                                 left = copy_to_user(uaddr, kaddr, copy);
2368 
2369                         if (unlikely(left))
2370                                 return -EFAULT;
2371 
2372                         iov_iter_advance(&ii, copy);
2373                         todo -= copy;
2374                         kaddr += copy;
2375                 }
2376 
2377                 kunmap(page);
2378         }
2379 
2380         return 0;
2381 }
2382 
2383 /*
2384  * CUSE servers compiled on 32bit broke on 64bit kernels because the
2385  * ABI was defined to be 'struct iovec' which is different on 32bit
2386  * and 64bit.  Fortunately we can determine which structure the server
2387  * used from the size of the reply.
2388  */
2389 static int fuse_copy_ioctl_iovec_old(struct iovec *dst, void *src,
2390                                      size_t transferred, unsigned count,
2391                                      bool is_compat)
2392 {
2393 #ifdef CONFIG_COMPAT
2394         if (count * sizeof(struct compat_iovec) == transferred) {
2395                 struct compat_iovec *ciov = src;
2396                 unsigned i;
2397 
2398                 /*
2399                  * With this interface a 32bit server cannot support
2400                  * non-compat (i.e. ones coming from 64bit apps) ioctl
2401                  * requests
2402                  */
2403                 if (!is_compat)
2404                         return -EINVAL;
2405 
2406                 for (i = 0; i < count; i++) {
2407                         dst[i].iov_base = compat_ptr(ciov[i].iov_base);
2408                         dst[i].iov_len = ciov[i].iov_len;
2409                 }
2410                 return 0;
2411         }
2412 #endif
2413 
2414         if (count * sizeof(struct iovec) != transferred)
2415                 return -EIO;
2416 
2417         memcpy(dst, src, transferred);
2418         return 0;
2419 }
2420 
2421 /* Make sure iov_length() won't overflow */
2422 static int fuse_verify_ioctl_iov(struct iovec *iov, size_t count)
2423 {
2424         size_t n;
2425         u32 max = FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT;
2426 
2427         for (n = 0; n < count; n++, iov++) {
2428                 if (iov->iov_len > (size_t) max)
2429                         return -ENOMEM;
2430                 max -= iov->iov_len;
2431         }
2432         return 0;
2433 }
2434 
2435 static int fuse_copy_ioctl_iovec(struct fuse_conn *fc, struct iovec *dst,
2436                                  void *src, size_t transferred, unsigned count,
2437                                  bool is_compat)
2438 {
2439         unsigned i;
2440         struct fuse_ioctl_iovec *fiov = src;
2441 
2442         if (fc->minor < 16) {
2443                 return fuse_copy_ioctl_iovec_old(dst, src, transferred,
2444                                                  count, is_compat);
2445         }
2446 
2447         if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
2448                 return -EIO;
2449 
2450         for (i = 0; i < count; i++) {
2451                 /* Did the server supply an inappropriate value? */
2452                 if (fiov[i].base != (unsigned long) fiov[i].base ||
2453                     fiov[i].len != (unsigned long) fiov[i].len)
2454                         return -EIO;
2455 
2456                 dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
2457                 dst[i].iov_len = (size_t) fiov[i].len;
2458 
2459 #ifdef CONFIG_COMPAT
2460                 if (is_compat &&
2461                     (ptr_to_compat(dst[i].iov_base) != fiov[i].base ||
2462                      (compat_size_t) dst[i].iov_len != fiov[i].len))
2463                         return -EIO;
2464 #endif
2465         }
2466 
2467         return 0;
2468 }
2469 
2470 
2471 /*
2472  * For ioctls, there is no generic way to determine how much memory
2473  * needs to be read and/or written.  Furthermore, ioctls are allowed
2474  * to dereference the passed pointer, so the parameter requires deep
2475  * copying but FUSE has no idea whatsoever about what to copy in or
2476  * out.
2477  *
2478  * This is solved by allowing FUSE server to retry ioctl with
2479  * necessary in/out iovecs.  Let's assume the ioctl implementation
2480  * needs to read in the following structure.
2481  *
2482  * struct a {
2483  *      char    *buf;
2484  *      size_t  buflen;
2485  * }
2486  *
2487  * On the first callout to FUSE server, inarg->in_size and
2488  * inarg->out_size will be NULL; then, the server completes the ioctl
2489  * with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
2490  * the actual iov array to
2491  *
2492  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a) } }
2493  *
2494  * which tells FUSE to copy in the requested area and retry the ioctl.
2495  * On the second round, the server has access to the structure and
2496  * from that it can tell what to look for next, so on the invocation,
2497  * it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
2498  *
2499  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a)     },
2500  *   { .iov_base = a.buf,       .iov_len = a.buflen             } }
2501  *
2502  * FUSE will copy both struct a and the pointed buffer from the
2503  * process doing the ioctl and retry ioctl with both struct a and the
2504  * buffer.
2505  *
2506  * This time, FUSE server has everything it needs and completes ioctl
2507  * without FUSE_IOCTL_RETRY which finishes the ioctl call.
2508  *
2509  * Copying data out works the same way.
2510  *
2511  * Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
2512  * automatically initializes in and out iovs by decoding @cmd with
2513  * _IOC_* macros and the server is not allowed to request RETRY.  This
2514  * limits ioctl data transfers to well-formed ioctls and is the forced
2515  * behavior for all FUSE servers.
2516  */
2517 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
2518                    unsigned int flags)
2519 {
2520         struct fuse_file *ff = file->private_data;
2521         struct fuse_conn *fc = ff->fc;
2522         struct fuse_ioctl_in inarg = {
2523                 .fh = ff->fh,
2524                 .cmd = cmd,
2525                 .arg = arg,
2526                 .flags = flags
2527         };
2528         struct fuse_ioctl_out outarg;
2529         struct fuse_req *req = NULL;
2530         struct page **pages = NULL;
2531         struct iovec *iov_page = NULL;
2532         struct iovec *in_iov = NULL, *out_iov = NULL;
2533         unsigned int in_iovs = 0, out_iovs = 0, num_pages = 0, max_pages;
2534         size_t in_size, out_size, transferred;
2535         int err;
2536 
2537 #if BITS_PER_LONG == 32
2538         inarg.flags |= FUSE_IOCTL_32BIT;
2539 #else
2540         if (flags & FUSE_IOCTL_COMPAT)
2541                 inarg.flags |= FUSE_IOCTL_32BIT;
2542 #endif
2543 
2544         /* assume all the iovs returned by client always fits in a page */
2545         BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
2546 
2547         err = -ENOMEM;
2548         pages = kcalloc(FUSE_MAX_PAGES_PER_REQ, sizeof(pages[0]), GFP_KERNEL);
2549         iov_page = (struct iovec *) __get_free_page(GFP_KERNEL);
2550         if (!pages || !iov_page)
2551                 goto out;
2552 
2553         /*
2554          * If restricted, initialize IO parameters as encoded in @cmd.
2555          * RETRY from server is not allowed.
2556          */
2557         if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
2558                 struct iovec *iov = iov_page;
2559 
2560                 iov->iov_base = (void __user *)arg;
2561                 iov->iov_len = _IOC_SIZE(cmd);
2562 
2563                 if (_IOC_DIR(cmd) & _IOC_WRITE) {
2564                         in_iov = iov;
2565                         in_iovs = 1;
2566                 }
2567 
2568                 if (_IOC_DIR(cmd) & _IOC_READ) {
2569                         out_iov = iov;
2570                         out_iovs = 1;
2571                 }
2572         }
2573 
2574  retry:
2575         inarg.in_size = in_size = iov_length(in_iov, in_iovs);
2576         inarg.out_size = out_size = iov_length(out_iov, out_iovs);
2577 
2578         /*
2579          * Out data can be used either for actual out data or iovs,
2580          * make sure there always is at least one page.
2581          */
2582         out_size = max_t(size_t, out_size, PAGE_SIZE);
2583         max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);
2584 
2585         /* make sure there are enough buffer pages and init request with them */
2586         err = -ENOMEM;
2587         if (max_pages > FUSE_MAX_PAGES_PER_REQ)
2588                 goto out;
2589         while (num_pages < max_pages) {
2590                 pages[num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
2591                 if (!pages[num_pages])
2592                         goto out;
2593                 num_pages++;
2594         }
2595 
2596         req = fuse_get_req(fc, num_pages);
2597         if (IS_ERR(req)) {
2598                 err = PTR_ERR(req);
2599                 req = NULL;
2600                 goto out;
2601         }
2602         memcpy(req->pages, pages, sizeof(req->pages[0]) * num_pages);
2603         req->num_pages = num_pages;
2604         fuse_page_descs_length_init(req, 0, req->num_pages);
2605 
2606         /* okay, let's send it to the client */
2607         req->in.h.opcode = FUSE_IOCTL;
2608         req->in.h.nodeid = ff->nodeid;
2609         req->in.numargs = 1;
2610         req->in.args[0].size = sizeof(inarg);
2611         req->in.args[0].value = &inarg;
2612         if (in_size) {
2613                 req->in.numargs++;
2614                 req->in.args[1].size = in_size;
2615                 req->in.argpages = 1;
2616 
2617                 err = fuse_ioctl_copy_user(pages, in_iov, in_iovs, in_size,
2618                                            false);
2619                 if (err)
2620                         goto out;
2621         }
2622 
2623         req->out.numargs = 2;
2624         req->out.args[0].size = sizeof(outarg);
2625         req->out.args[0].value = &outarg;
2626         req->out.args[1].size = out_size;
2627         req->out.argpages = 1;
2628         req->out.argvar = 1;
2629 
2630         fuse_request_send(fc, req);
2631         err = req->out.h.error;
2632         transferred = req->out.args[1].size;
2633         fuse_put_request(fc, req);
2634         req = NULL;
2635         if (err)
2636                 goto out;
2637 
2638         /* did it ask for retry? */
2639         if (outarg.flags & FUSE_IOCTL_RETRY) {
2640                 void *vaddr;
2641 
2642                 /* no retry if in restricted mode */
2643                 err = -EIO;
2644                 if (!(flags & FUSE_IOCTL_UNRESTRICTED))
2645                         goto out;
2646 
2647                 in_iovs = outarg.in_iovs;
2648                 out_iovs = outarg.out_iovs;
2649 
2650                 /*
2651                  * Make sure things are in boundary, separate checks
2652                  * are to protect against overflow.
2653                  */
2654                 err = -ENOMEM;
2655                 if (in_iovs > FUSE_IOCTL_MAX_IOV ||
2656                     out_iovs > FUSE_IOCTL_MAX_IOV ||
2657                     in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
2658                         goto out;
2659 
2660                 vaddr = kmap_atomic(pages[0]);
2661                 err = fuse_copy_ioctl_iovec(fc, iov_page, vaddr,
2662                                             transferred, in_iovs + out_iovs,
2663                                             (flags & FUSE_IOCTL_COMPAT) != 0);
2664                 kunmap_atomic(vaddr);
2665                 if (err)
2666                         goto out;
2667 
2668                 in_iov = iov_page;
2669                 out_iov = in_iov + in_iovs;
2670 
2671                 err = fuse_verify_ioctl_iov(in_iov, in_iovs);
2672                 if (err)
2673                         goto out;
2674 
2675                 err = fuse_verify_ioctl_iov(out_iov, out_iovs);
2676                 if (err)
2677                         goto out;
2678 
2679                 goto retry;
2680         }
2681 
2682         err = -EIO;
2683         if (transferred > inarg.out_size)
2684                 goto out;
2685 
2686         err = fuse_ioctl_copy_user(pages, out_iov, out_iovs, transferred, true);
2687  out:
2688         if (req)
2689                 fuse_put_request(fc, req);
2690         free_page((unsigned long) iov_page);
2691         while (num_pages)
2692                 __free_page(pages[--num_pages]);
2693         kfree(pages);
2694 
2695         return err ? err : outarg.result;
2696 }
2697 EXPORT_SYMBOL_GPL(fuse_do_ioctl);
2698 
2699 long fuse_ioctl_common(struct file *file, unsigned int cmd,
2700                        unsigned long arg, unsigned int flags)
2701 {
2702         struct inode *inode = file_inode(file);
2703         struct fuse_conn *fc = get_fuse_conn(inode);
2704 
2705         if (!fuse_allow_current_process(fc))
2706                 return -EACCES;
2707 
2708         if (is_bad_inode(inode))
2709                 return -EIO;
2710 
2711         return fuse_do_ioctl(file, cmd, arg, flags);
2712 }
2713 
2714 static long fuse_file_ioctl(struct file *file, unsigned int cmd,
2715                             unsigned long arg)
2716 {
2717         return fuse_ioctl_common(file, cmd, arg, 0);
2718 }
2719 
2720 static long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
2721                                    unsigned long arg)
2722 {
2723         return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_COMPAT);
2724 }
2725 
2726 /*
2727  * All files which have been polled are linked to RB tree
2728  * fuse_conn->polled_files which is indexed by kh.  Walk the tree and
2729  * find the matching one.
2730  */
2731 static struct rb_node **fuse_find_polled_node(struct fuse_conn *fc, u64 kh,
2732                                               struct rb_node **parent_out)
2733 {
2734         struct rb_node **link = &fc->polled_files.rb_node;
2735         struct rb_node *last = NULL;
2736 
2737         while (*link) {
2738                 struct fuse_file *ff;
2739 
2740                 last = *link;
2741                 ff = rb_entry(last, struct fuse_file, polled_node);
2742 
2743                 if (kh < ff->kh)
2744                         link = &last->rb_left;
2745                 else if (kh > ff->kh)
2746                         link = &last->rb_right;
2747                 else
2748                         return link;
2749         }
2750 
2751         if (parent_out)
2752                 *parent_out = last;
2753         return link;
2754 }
2755 
2756 /*
2757  * The file is about to be polled.  Make sure it's on the polled_files
2758  * RB tree.  Note that files once added to the polled_files tree are
2759  * not removed before the file is released.  This is because a file
2760  * polled once is likely to be polled again.
2761  */
2762 static void fuse_register_polled_file(struct fuse_conn *fc,
2763                                       struct fuse_file *ff)
2764 {
2765         spin_lock(&fc->lock);
2766         if (RB_EMPTY_NODE(&ff->polled_node)) {
2767                 struct rb_node **link, *uninitialized_var(parent);
2768 
2769                 link = fuse_find_polled_node(fc, ff->kh, &parent);
2770                 BUG_ON(*link);
2771                 rb_link_node(&ff->polled_node, parent, link);
2772                 rb_insert_color(&ff->polled_node, &fc->polled_files);
2773         }
2774         spin_unlock(&fc->lock);
2775 }
2776 
2777 unsigned fuse_file_poll(struct file *file, poll_table *wait)
2778 {
2779         struct fuse_file *ff = file->private_data;
2780         struct fuse_conn *fc = ff->fc;
2781         struct fuse_poll_in inarg = { .fh = ff->fh, .kh = ff->kh };
2782         struct fuse_poll_out outarg;
2783         FUSE_ARGS(args);
2784         int err;
2785 
2786         if (fc->no_poll)
2787                 return DEFAULT_POLLMASK;
2788 
2789         poll_wait(file, &ff->poll_wait, wait);
2790         inarg.events = (__u32)poll_requested_events(wait);
2791 
2792         /*
2793          * Ask for notification iff there's someone waiting for it.
2794          * The client may ignore the flag and always notify.
2795          */
2796         if (waitqueue_active(&ff->poll_wait)) {
2797                 inarg.flags |= FUSE_POLL_SCHEDULE_NOTIFY;
2798                 fuse_register_polled_file(fc, ff);
2799         }
2800 
2801         args.in.h.opcode = FUSE_POLL;
2802         args.in.h.nodeid = ff->nodeid;
2803         args.in.numargs = 1;
2804         args.in.args[0].size = sizeof(inarg);
2805         args.in.args[0].value = &inarg;
2806         args.out.numargs = 1;
2807         args.out.args[0].size = sizeof(outarg);
2808         args.out.args[0].value = &outarg;
2809         err = fuse_simple_request(fc, &args);
2810 
2811         if (!err)
2812                 return outarg.revents;
2813         if (err == -ENOSYS) {
2814                 fc->no_poll = 1;
2815                 return DEFAULT_POLLMASK;
2816         }
2817         return POLLERR;
2818 }
2819 EXPORT_SYMBOL_GPL(fuse_file_poll);
2820 
2821 /*
2822  * This is called from fuse_handle_notify() on FUSE_NOTIFY_POLL and
2823  * wakes up the poll waiters.
2824  */
2825 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
2826                             struct fuse_notify_poll_wakeup_out *outarg)
2827 {
2828         u64 kh = outarg->kh;
2829         struct rb_node **link;
2830 
2831         spin_lock(&fc->lock);
2832 
2833         link = fuse_find_polled_node(fc, kh, NULL);
2834         if (*link) {
2835                 struct fuse_file *ff;
2836 
2837                 ff = rb_entry(*link, struct fuse_file, polled_node);
2838                 wake_up_interruptible_sync(&ff->poll_wait);
2839         }
2840 
2841         spin_unlock(&fc->lock);
2842         return 0;
2843 }
2844 
2845 static void fuse_do_truncate(struct file *file)
2846 {
2847         struct inode *inode = file->f_mapping->host;
2848         struct iattr attr;
2849 
2850         attr.ia_valid = ATTR_SIZE;
2851         attr.ia_size = i_size_read(inode);
2852 
2853         attr.ia_file = file;
2854         attr.ia_valid |= ATTR_FILE;
2855 
2856         fuse_do_setattr(inode, &attr, file);
2857 }
2858 
2859 static inline loff_t fuse_round_up(loff_t off)
2860 {
2861         return round_up(off, FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
2862 }
2863 
2864 static ssize_t
2865 fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
2866 {
2867         DECLARE_COMPLETION_ONSTACK(wait);
2868         ssize_t ret = 0;
2869         struct file *file = iocb->ki_filp;
2870         struct fuse_file *ff = file->private_data;
2871         bool async_dio = ff->fc->async_dio;
2872         loff_t pos = 0;
2873         struct inode *inode;
2874         loff_t i_size;
2875         size_t count = iov_iter_count(iter);
2876         loff_t offset = iocb->ki_pos;
2877         struct fuse_io_priv *io;
2878         bool is_sync = is_sync_kiocb(iocb);
2879 
2880         pos = offset;
2881         inode = file->f_mapping->host;
2882         i_size = i_size_read(inode);
2883 
2884         if ((iov_iter_rw(iter) == READ) && (offset > i_size))
2885                 return 0;
2886 
2887         /* optimization for short read */
2888         if (async_dio && iov_iter_rw(iter) != WRITE && offset + count > i_size) {
2889                 if (offset >= i_size)
2890                         return 0;
2891                 iov_iter_truncate(iter, fuse_round_up(i_size - offset));
2892                 count = iov_iter_count(iter);
2893         }
2894 
2895         io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
2896         if (!io)
2897                 return -ENOMEM;
2898         spin_lock_init(&io->lock);
2899         kref_init(&io->refcnt);
2900         io->reqs = 1;
2901         io->bytes = -1;
2902         io->size = 0;
2903         io->offset = offset;
2904         io->write = (iov_iter_rw(iter) == WRITE);
2905         io->err = 0;
2906         io->file = file;
2907         /*
2908          * By default, we want to optimize all I/Os with async request
2909          * submission to the client filesystem if supported.
2910          */
2911         io->async = async_dio;
2912         io->iocb = iocb;
2913 
2914         /*
2915          * We cannot asynchronously extend the size of a file. We have no method
2916          * to wait on real async I/O requests, so we must submit this request
2917          * synchronously.
2918          */
2919         if (!is_sync && (offset + count > i_size) &&
2920             iov_iter_rw(iter) == WRITE)
2921                 io->async = false;
2922 
2923         if (io->async && is_sync) {
2924                 /*
2925                  * Additional reference to keep io around after
2926                  * calling fuse_aio_complete()
2927                  */
2928                 kref_get(&io->refcnt);
2929                 io->done = &wait;
2930         }
2931 
2932         if (iov_iter_rw(iter) == WRITE) {
2933                 ret = fuse_direct_io(io, iter, &pos, FUSE_DIO_WRITE);
2934                 fuse_invalidate_attr(inode);
2935         } else {
2936                 ret = __fuse_direct_read(io, iter, &pos);
2937         }
2938 
2939         if (io->async) {
2940                 fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
2941 
2942                 /* we have a non-extending, async request, so return */
2943                 if (!is_sync)
2944                         return -EIOCBQUEUED;
2945 
2946                 wait_for_completion(&wait);
2947                 ret = fuse_get_res_by_io(io);
2948         }
2949 
2950         kref_put(&io->refcnt, fuse_io_release);
2951 
2952         if (iov_iter_rw(iter) == WRITE) {
2953                 if (ret > 0)
2954                         fuse_write_update_size(inode, pos);
2955                 else if (ret < 0 && offset + count > i_size)
2956                         fuse_do_truncate(file);
2957         }
2958 
2959         return ret;
2960 }
2961 
2962 static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
2963                                 loff_t length)
2964 {
2965         struct fuse_file *ff = file->private_data;
2966         struct inode *inode = file_inode(file);
2967         struct fuse_inode *fi = get_fuse_inode(inode);
2968         struct fuse_conn *fc = ff->fc;
2969         FUSE_ARGS(args);
2970         struct fuse_fallocate_in inarg = {
2971                 .fh = ff->fh,
2972                 .offset = offset,
2973                 .length = length,
2974                 .mode = mode
2975         };
2976         int err;
2977         bool lock_inode = !(mode & FALLOC_FL_KEEP_SIZE) ||
2978                            (mode & FALLOC_FL_PUNCH_HOLE);
2979 
2980         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2981                 return -EOPNOTSUPP;
2982 
2983         if (fc->no_fallocate)
2984                 return -EOPNOTSUPP;
2985 
2986         if (lock_inode) {
2987                 inode_lock(inode);
2988                 if (mode & FALLOC_FL_PUNCH_HOLE) {
2989                         loff_t endbyte = offset + length - 1;
2990                         err = filemap_write_and_wait_range(inode->i_mapping,
2991                                                            offset, endbyte);
2992                         if (err)
2993                                 goto out;
2994 
2995                         fuse_sync_writes(inode);
2996                 }
2997         }
2998 
2999         if (!(mode & FALLOC_FL_KEEP_SIZE))
3000                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
3001 
3002         args.in.h.opcode = FUSE_FALLOCATE;
3003         args.in.h.nodeid = ff->nodeid;
3004         args.in.numargs = 1;
3005         args.in.args[0].size = sizeof(inarg);
3006         args.in.args[0].value = &inarg;
3007         err = fuse_simple_request(fc, &args);
3008         if (err == -ENOSYS) {
3009                 fc->no_fallocate = 1;
3010                 err = -EOPNOTSUPP;
3011         }
3012         if (err)
3013                 goto out;
3014 
3015         /* we could have extended the file */
3016         if (!(mode & FALLOC_FL_KEEP_SIZE)) {
3017                 bool changed = fuse_write_update_size(inode, offset + length);
3018 
3019                 if (changed && fc->writeback_cache)
3020                         file_update_time(file);
3021         }
3022 
3023         if (mode & FALLOC_FL_PUNCH_HOLE)
3024                 truncate_pagecache_range(inode, offset, offset + length - 1);
3025 
3026         fuse_invalidate_attr(inode);
3027 
3028 out:
3029         if (!(mode & FALLOC_FL_KEEP_SIZE))
3030                 clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
3031 
3032         if (lock_inode)
3033                 inode_unlock(inode);
3034 
3035         return err;
3036 }
3037 
3038 static const struct file_operations fuse_file_operations = {
3039         .llseek         = fuse_file_llseek,
3040         .read_iter      = fuse_file_read_iter,
3041         .write_iter     = fuse_file_write_iter,
3042         .mmap           = fuse_file_mmap,
3043         .open           = fuse_open,
3044         .flush          = fuse_flush,
3045         .release        = fuse_release,
3046         .fsync          = fuse_fsync,
3047         .lock           = fuse_file_lock,
3048         .flock          = fuse_file_flock,
3049         .splice_read    = generic_file_splice_read,
3050         .unlocked_ioctl = fuse_file_ioctl,
3051         .compat_ioctl   = fuse_file_compat_ioctl,
3052         .poll           = fuse_file_poll,
3053         .fallocate      = fuse_file_fallocate,
3054 };
3055 
3056 static const struct file_operations fuse_direct_io_file_operations = {
3057         .llseek         = fuse_file_llseek,
3058         .read_iter      = fuse_direct_read_iter,
3059         .write_iter     = fuse_direct_write_iter,
3060         .mmap           = fuse_direct_mmap,
3061         .open           = fuse_open,
3062         .flush          = fuse_flush,
3063         .release        = fuse_release,
3064         .fsync          = fuse_fsync,
3065         .lock           = fuse_file_lock,
3066         .flock          = fuse_file_flock,
3067         .unlocked_ioctl = fuse_file_ioctl,
3068         .compat_ioctl   = fuse_file_compat_ioctl,
3069         .poll           = fuse_file_poll,
3070         .fallocate      = fuse_file_fallocate,
3071         /* no splice_read */
3072 };
3073 
3074 static const struct address_space_operations fuse_file_aops  = {
3075         .readpage       = fuse_readpage,
3076         .writepage      = fuse_writepage,
3077         .writepages     = fuse_writepages,
3078         .launder_page   = fuse_launder_page,
3079         .readpages      = fuse_readpages,
3080         .set_page_dirty = __set_page_dirty_nobuffers,
3081         .bmap           = fuse_bmap,
3082         .direct_IO      = fuse_direct_IO,
3083         .write_begin    = fuse_write_begin,
3084         .write_end      = fuse_write_end,
3085 };
3086 
3087 void fuse_init_file_inode(struct inode *inode)
3088 {
3089         inode->i_fop = &fuse_file_operations;
3090         inode->i_data.a_ops = &fuse_file_aops;
3091 }
3092 

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