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TOMOYO Linux Cross Reference
Linux/fs/read_write.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  linux/fs/read_write.c
  4  *
  5  *  Copyright (C) 1991, 1992  Linus Torvalds
  6  */
  7 
  8 #include <linux/slab.h>
  9 #include <linux/stat.h>
 10 #include <linux/sched/xacct.h>
 11 #include <linux/fcntl.h>
 12 #include <linux/file.h>
 13 #include <linux/uio.h>
 14 #include <linux/fsnotify.h>
 15 #include <linux/security.h>
 16 #include <linux/export.h>
 17 #include <linux/syscalls.h>
 18 #include <linux/pagemap.h>
 19 #include <linux/splice.h>
 20 #include <linux/compat.h>
 21 #include <linux/mount.h>
 22 #include <linux/fs.h>
 23 #include "internal.h"
 24 
 25 #include <linux/uaccess.h>
 26 #include <asm/unistd.h>
 27 
 28 const struct file_operations generic_ro_fops = {
 29         .llseek         = generic_file_llseek,
 30         .read_iter      = generic_file_read_iter,
 31         .mmap           = generic_file_readonly_mmap,
 32         .splice_read    = generic_file_splice_read,
 33 };
 34 
 35 EXPORT_SYMBOL(generic_ro_fops);
 36 
 37 static inline bool unsigned_offsets(struct file *file)
 38 {
 39         return file->f_mode & FMODE_UNSIGNED_OFFSET;
 40 }
 41 
 42 /**
 43  * vfs_setpos - update the file offset for lseek
 44  * @file:       file structure in question
 45  * @offset:     file offset to seek to
 46  * @maxsize:    maximum file size
 47  *
 48  * This is a low-level filesystem helper for updating the file offset to
 49  * the value specified by @offset if the given offset is valid and it is
 50  * not equal to the current file offset.
 51  *
 52  * Return the specified offset on success and -EINVAL on invalid offset.
 53  */
 54 loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize)
 55 {
 56         if (offset < 0 && !unsigned_offsets(file))
 57                 return -EINVAL;
 58         if (offset > maxsize)
 59                 return -EINVAL;
 60 
 61         if (offset != file->f_pos) {
 62                 file->f_pos = offset;
 63                 file->f_version = 0;
 64         }
 65         return offset;
 66 }
 67 EXPORT_SYMBOL(vfs_setpos);
 68 
 69 /**
 70  * generic_file_llseek_size - generic llseek implementation for regular files
 71  * @file:       file structure to seek on
 72  * @offset:     file offset to seek to
 73  * @whence:     type of seek
 74  * @size:       max size of this file in file system
 75  * @eof:        offset used for SEEK_END position
 76  *
 77  * This is a variant of generic_file_llseek that allows passing in a custom
 78  * maximum file size and a custom EOF position, for e.g. hashed directories
 79  *
 80  * Synchronization:
 81  * SEEK_SET and SEEK_END are unsynchronized (but atomic on 64bit platforms)
 82  * SEEK_CUR is synchronized against other SEEK_CURs, but not read/writes.
 83  * read/writes behave like SEEK_SET against seeks.
 84  */
 85 loff_t
 86 generic_file_llseek_size(struct file *file, loff_t offset, int whence,
 87                 loff_t maxsize, loff_t eof)
 88 {
 89         switch (whence) {
 90         case SEEK_END:
 91                 offset += eof;
 92                 break;
 93         case SEEK_CUR:
 94                 /*
 95                  * Here we special-case the lseek(fd, 0, SEEK_CUR)
 96                  * position-querying operation.  Avoid rewriting the "same"
 97                  * f_pos value back to the file because a concurrent read(),
 98                  * write() or lseek() might have altered it
 99                  */
100                 if (offset == 0)
101                         return file->f_pos;
102                 /*
103                  * f_lock protects against read/modify/write race with other
104                  * SEEK_CURs. Note that parallel writes and reads behave
105                  * like SEEK_SET.
106                  */
107                 spin_lock(&file->f_lock);
108                 offset = vfs_setpos(file, file->f_pos + offset, maxsize);
109                 spin_unlock(&file->f_lock);
110                 return offset;
111         case SEEK_DATA:
112                 /*
113                  * In the generic case the entire file is data, so as long as
114                  * offset isn't at the end of the file then the offset is data.
115                  */
116                 if ((unsigned long long)offset >= eof)
117                         return -ENXIO;
118                 break;
119         case SEEK_HOLE:
120                 /*
121                  * There is a virtual hole at the end of the file, so as long as
122                  * offset isn't i_size or larger, return i_size.
123                  */
124                 if ((unsigned long long)offset >= eof)
125                         return -ENXIO;
126                 offset = eof;
127                 break;
128         }
129 
130         return vfs_setpos(file, offset, maxsize);
131 }
132 EXPORT_SYMBOL(generic_file_llseek_size);
133 
134 /**
135  * generic_file_llseek - generic llseek implementation for regular files
136  * @file:       file structure to seek on
137  * @offset:     file offset to seek to
138  * @whence:     type of seek
139  *
140  * This is a generic implemenation of ->llseek useable for all normal local
141  * filesystems.  It just updates the file offset to the value specified by
142  * @offset and @whence.
143  */
144 loff_t generic_file_llseek(struct file *file, loff_t offset, int whence)
145 {
146         struct inode *inode = file->f_mapping->host;
147 
148         return generic_file_llseek_size(file, offset, whence,
149                                         inode->i_sb->s_maxbytes,
150                                         i_size_read(inode));
151 }
152 EXPORT_SYMBOL(generic_file_llseek);
153 
154 /**
155  * fixed_size_llseek - llseek implementation for fixed-sized devices
156  * @file:       file structure to seek on
157  * @offset:     file offset to seek to
158  * @whence:     type of seek
159  * @size:       size of the file
160  *
161  */
162 loff_t fixed_size_llseek(struct file *file, loff_t offset, int whence, loff_t size)
163 {
164         switch (whence) {
165         case SEEK_SET: case SEEK_CUR: case SEEK_END:
166                 return generic_file_llseek_size(file, offset, whence,
167                                                 size, size);
168         default:
169                 return -EINVAL;
170         }
171 }
172 EXPORT_SYMBOL(fixed_size_llseek);
173 
174 /**
175  * no_seek_end_llseek - llseek implementation for fixed-sized devices
176  * @file:       file structure to seek on
177  * @offset:     file offset to seek to
178  * @whence:     type of seek
179  *
180  */
181 loff_t no_seek_end_llseek(struct file *file, loff_t offset, int whence)
182 {
183         switch (whence) {
184         case SEEK_SET: case SEEK_CUR:
185                 return generic_file_llseek_size(file, offset, whence,
186                                                 OFFSET_MAX, 0);
187         default:
188                 return -EINVAL;
189         }
190 }
191 EXPORT_SYMBOL(no_seek_end_llseek);
192 
193 /**
194  * no_seek_end_llseek_size - llseek implementation for fixed-sized devices
195  * @file:       file structure to seek on
196  * @offset:     file offset to seek to
197  * @whence:     type of seek
198  * @size:       maximal offset allowed
199  *
200  */
201 loff_t no_seek_end_llseek_size(struct file *file, loff_t offset, int whence, loff_t size)
202 {
203         switch (whence) {
204         case SEEK_SET: case SEEK_CUR:
205                 return generic_file_llseek_size(file, offset, whence,
206                                                 size, 0);
207         default:
208                 return -EINVAL;
209         }
210 }
211 EXPORT_SYMBOL(no_seek_end_llseek_size);
212 
213 /**
214  * noop_llseek - No Operation Performed llseek implementation
215  * @file:       file structure to seek on
216  * @offset:     file offset to seek to
217  * @whence:     type of seek
218  *
219  * This is an implementation of ->llseek useable for the rare special case when
220  * userspace expects the seek to succeed but the (device) file is actually not
221  * able to perform the seek. In this case you use noop_llseek() instead of
222  * falling back to the default implementation of ->llseek.
223  */
224 loff_t noop_llseek(struct file *file, loff_t offset, int whence)
225 {
226         return file->f_pos;
227 }
228 EXPORT_SYMBOL(noop_llseek);
229 
230 loff_t no_llseek(struct file *file, loff_t offset, int whence)
231 {
232         return -ESPIPE;
233 }
234 EXPORT_SYMBOL(no_llseek);
235 
236 loff_t default_llseek(struct file *file, loff_t offset, int whence)
237 {
238         struct inode *inode = file_inode(file);
239         loff_t retval;
240 
241         inode_lock(inode);
242         switch (whence) {
243                 case SEEK_END:
244                         offset += i_size_read(inode);
245                         break;
246                 case SEEK_CUR:
247                         if (offset == 0) {
248                                 retval = file->f_pos;
249                                 goto out;
250                         }
251                         offset += file->f_pos;
252                         break;
253                 case SEEK_DATA:
254                         /*
255                          * In the generic case the entire file is data, so as
256                          * long as offset isn't at the end of the file then the
257                          * offset is data.
258                          */
259                         if (offset >= inode->i_size) {
260                                 retval = -ENXIO;
261                                 goto out;
262                         }
263                         break;
264                 case SEEK_HOLE:
265                         /*
266                          * There is a virtual hole at the end of the file, so
267                          * as long as offset isn't i_size or larger, return
268                          * i_size.
269                          */
270                         if (offset >= inode->i_size) {
271                                 retval = -ENXIO;
272                                 goto out;
273                         }
274                         offset = inode->i_size;
275                         break;
276         }
277         retval = -EINVAL;
278         if (offset >= 0 || unsigned_offsets(file)) {
279                 if (offset != file->f_pos) {
280                         file->f_pos = offset;
281                         file->f_version = 0;
282                 }
283                 retval = offset;
284         }
285 out:
286         inode_unlock(inode);
287         return retval;
288 }
289 EXPORT_SYMBOL(default_llseek);
290 
291 loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
292 {
293         loff_t (*fn)(struct file *, loff_t, int);
294 
295         fn = no_llseek;
296         if (file->f_mode & FMODE_LSEEK) {
297                 if (file->f_op->llseek)
298                         fn = file->f_op->llseek;
299         }
300         return fn(file, offset, whence);
301 }
302 EXPORT_SYMBOL(vfs_llseek);
303 
304 off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence)
305 {
306         off_t retval;
307         struct fd f = fdget_pos(fd);
308         if (!f.file)
309                 return -EBADF;
310 
311         retval = -EINVAL;
312         if (whence <= SEEK_MAX) {
313                 loff_t res = vfs_llseek(f.file, offset, whence);
314                 retval = res;
315                 if (res != (loff_t)retval)
316                         retval = -EOVERFLOW;    /* LFS: should only happen on 32 bit platforms */
317         }
318         fdput_pos(f);
319         return retval;
320 }
321 
322 SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence)
323 {
324         return ksys_lseek(fd, offset, whence);
325 }
326 
327 #ifdef CONFIG_COMPAT
328 COMPAT_SYSCALL_DEFINE3(lseek, unsigned int, fd, compat_off_t, offset, unsigned int, whence)
329 {
330         return ksys_lseek(fd, offset, whence);
331 }
332 #endif
333 
334 #if !defined(CONFIG_64BIT) || defined(CONFIG_COMPAT)
335 SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high,
336                 unsigned long, offset_low, loff_t __user *, result,
337                 unsigned int, whence)
338 {
339         int retval;
340         struct fd f = fdget_pos(fd);
341         loff_t offset;
342 
343         if (!f.file)
344                 return -EBADF;
345 
346         retval = -EINVAL;
347         if (whence > SEEK_MAX)
348                 goto out_putf;
349 
350         offset = vfs_llseek(f.file, ((loff_t) offset_high << 32) | offset_low,
351                         whence);
352 
353         retval = (int)offset;
354         if (offset >= 0) {
355                 retval = -EFAULT;
356                 if (!copy_to_user(result, &offset, sizeof(offset)))
357                         retval = 0;
358         }
359 out_putf:
360         fdput_pos(f);
361         return retval;
362 }
363 #endif
364 
365 int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t count)
366 {
367         struct inode *inode;
368         loff_t pos;
369         int retval = -EINVAL;
370 
371         inode = file_inode(file);
372         if (unlikely((ssize_t) count < 0))
373                 return retval;
374         pos = *ppos;
375         if (unlikely(pos < 0)) {
376                 if (!unsigned_offsets(file))
377                         return retval;
378                 if (count >= -pos) /* both values are in 0..LLONG_MAX */
379                         return -EOVERFLOW;
380         } else if (unlikely((loff_t) (pos + count) < 0)) {
381                 if (!unsigned_offsets(file))
382                         return retval;
383         }
384 
385         if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
386                 retval = locks_mandatory_area(inode, file, pos, pos + count - 1,
387                                 read_write == READ ? F_RDLCK : F_WRLCK);
388                 if (retval < 0)
389                         return retval;
390         }
391         return security_file_permission(file,
392                                 read_write == READ ? MAY_READ : MAY_WRITE);
393 }
394 
395 static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
396 {
397         struct iovec iov = { .iov_base = buf, .iov_len = len };
398         struct kiocb kiocb;
399         struct iov_iter iter;
400         ssize_t ret;
401 
402         init_sync_kiocb(&kiocb, filp);
403         kiocb.ki_pos = *ppos;
404         iov_iter_init(&iter, READ, &iov, 1, len);
405 
406         ret = call_read_iter(filp, &kiocb, &iter);
407         BUG_ON(ret == -EIOCBQUEUED);
408         *ppos = kiocb.ki_pos;
409         return ret;
410 }
411 
412 ssize_t __vfs_read(struct file *file, char __user *buf, size_t count,
413                    loff_t *pos)
414 {
415         if (file->f_op->read)
416                 return file->f_op->read(file, buf, count, pos);
417         else if (file->f_op->read_iter)
418                 return new_sync_read(file, buf, count, pos);
419         else
420                 return -EINVAL;
421 }
422 
423 ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
424 {
425         mm_segment_t old_fs;
426         ssize_t result;
427 
428         old_fs = get_fs();
429         set_fs(KERNEL_DS);
430         /* The cast to a user pointer is valid due to the set_fs() */
431         result = vfs_read(file, (void __user *)buf, count, pos);
432         set_fs(old_fs);
433         return result;
434 }
435 EXPORT_SYMBOL(kernel_read);
436 
437 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
438 {
439         ssize_t ret;
440 
441         if (!(file->f_mode & FMODE_READ))
442                 return -EBADF;
443         if (!(file->f_mode & FMODE_CAN_READ))
444                 return -EINVAL;
445         if (unlikely(!access_ok(buf, count)))
446                 return -EFAULT;
447 
448         ret = rw_verify_area(READ, file, pos, count);
449         if (!ret) {
450                 if (count > MAX_RW_COUNT)
451                         count =  MAX_RW_COUNT;
452                 ret = __vfs_read(file, buf, count, pos);
453                 if (ret > 0) {
454                         fsnotify_access(file);
455                         add_rchar(current, ret);
456                 }
457                 inc_syscr(current);
458         }
459 
460         return ret;
461 }
462 
463 static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
464 {
465         struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
466         struct kiocb kiocb;
467         struct iov_iter iter;
468         ssize_t ret;
469 
470         init_sync_kiocb(&kiocb, filp);
471         kiocb.ki_pos = *ppos;
472         iov_iter_init(&iter, WRITE, &iov, 1, len);
473 
474         ret = call_write_iter(filp, &kiocb, &iter);
475         BUG_ON(ret == -EIOCBQUEUED);
476         if (ret > 0)
477                 *ppos = kiocb.ki_pos;
478         return ret;
479 }
480 
481 static ssize_t __vfs_write(struct file *file, const char __user *p,
482                            size_t count, loff_t *pos)
483 {
484         if (file->f_op->write)
485                 return file->f_op->write(file, p, count, pos);
486         else if (file->f_op->write_iter)
487                 return new_sync_write(file, p, count, pos);
488         else
489                 return -EINVAL;
490 }
491 
492 ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos)
493 {
494         mm_segment_t old_fs;
495         const char __user *p;
496         ssize_t ret;
497 
498         if (!(file->f_mode & FMODE_CAN_WRITE))
499                 return -EINVAL;
500 
501         old_fs = get_fs();
502         set_fs(KERNEL_DS);
503         p = (__force const char __user *)buf;
504         if (count > MAX_RW_COUNT)
505                 count =  MAX_RW_COUNT;
506         ret = __vfs_write(file, p, count, pos);
507         set_fs(old_fs);
508         if (ret > 0) {
509                 fsnotify_modify(file);
510                 add_wchar(current, ret);
511         }
512         inc_syscw(current);
513         return ret;
514 }
515 EXPORT_SYMBOL(__kernel_write);
516 
517 ssize_t kernel_write(struct file *file, const void *buf, size_t count,
518                             loff_t *pos)
519 {
520         mm_segment_t old_fs;
521         ssize_t res;
522 
523         old_fs = get_fs();
524         set_fs(KERNEL_DS);
525         /* The cast to a user pointer is valid due to the set_fs() */
526         res = vfs_write(file, (__force const char __user *)buf, count, pos);
527         set_fs(old_fs);
528 
529         return res;
530 }
531 EXPORT_SYMBOL(kernel_write);
532 
533 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
534 {
535         ssize_t ret;
536 
537         if (!(file->f_mode & FMODE_WRITE))
538                 return -EBADF;
539         if (!(file->f_mode & FMODE_CAN_WRITE))
540                 return -EINVAL;
541         if (unlikely(!access_ok(buf, count)))
542                 return -EFAULT;
543 
544         ret = rw_verify_area(WRITE, file, pos, count);
545         if (!ret) {
546                 if (count > MAX_RW_COUNT)
547                         count =  MAX_RW_COUNT;
548                 file_start_write(file);
549                 ret = __vfs_write(file, buf, count, pos);
550                 if (ret > 0) {
551                         fsnotify_modify(file);
552                         add_wchar(current, ret);
553                 }
554                 inc_syscw(current);
555                 file_end_write(file);
556         }
557 
558         return ret;
559 }
560 
561 static inline loff_t file_pos_read(struct file *file)
562 {
563         return file->f_pos;
564 }
565 
566 static inline void file_pos_write(struct file *file, loff_t pos)
567 {
568         file->f_pos = pos;
569 }
570 
571 ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count)
572 {
573         struct fd f = fdget_pos(fd);
574         ssize_t ret = -EBADF;
575 
576         if (f.file) {
577                 loff_t pos = file_pos_read(f.file);
578                 ret = vfs_read(f.file, buf, count, &pos);
579                 if (ret >= 0)
580                         file_pos_write(f.file, pos);
581                 fdput_pos(f);
582         }
583         return ret;
584 }
585 
586 SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
587 {
588         return ksys_read(fd, buf, count);
589 }
590 
591 ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count)
592 {
593         struct fd f = fdget_pos(fd);
594         ssize_t ret = -EBADF;
595 
596         if (f.file) {
597                 loff_t pos = file_pos_read(f.file);
598                 ret = vfs_write(f.file, buf, count, &pos);
599                 if (ret >= 0)
600                         file_pos_write(f.file, pos);
601                 fdput_pos(f);
602         }
603 
604         return ret;
605 }
606 
607 SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf,
608                 size_t, count)
609 {
610         return ksys_write(fd, buf, count);
611 }
612 
613 ssize_t ksys_pread64(unsigned int fd, char __user *buf, size_t count,
614                      loff_t pos)
615 {
616         struct fd f;
617         ssize_t ret = -EBADF;
618 
619         if (pos < 0)
620                 return -EINVAL;
621 
622         f = fdget(fd);
623         if (f.file) {
624                 ret = -ESPIPE;
625                 if (f.file->f_mode & FMODE_PREAD)
626                         ret = vfs_read(f.file, buf, count, &pos);
627                 fdput(f);
628         }
629 
630         return ret;
631 }
632 
633 SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf,
634                         size_t, count, loff_t, pos)
635 {
636         return ksys_pread64(fd, buf, count, pos);
637 }
638 
639 ssize_t ksys_pwrite64(unsigned int fd, const char __user *buf,
640                       size_t count, loff_t pos)
641 {
642         struct fd f;
643         ssize_t ret = -EBADF;
644 
645         if (pos < 0)
646                 return -EINVAL;
647 
648         f = fdget(fd);
649         if (f.file) {
650                 ret = -ESPIPE;
651                 if (f.file->f_mode & FMODE_PWRITE)  
652                         ret = vfs_write(f.file, buf, count, &pos);
653                 fdput(f);
654         }
655 
656         return ret;
657 }
658 
659 SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf,
660                          size_t, count, loff_t, pos)
661 {
662         return ksys_pwrite64(fd, buf, count, pos);
663 }
664 
665 static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
666                 loff_t *ppos, int type, rwf_t flags)
667 {
668         struct kiocb kiocb;
669         ssize_t ret;
670 
671         init_sync_kiocb(&kiocb, filp);
672         ret = kiocb_set_rw_flags(&kiocb, flags);
673         if (ret)
674                 return ret;
675         kiocb.ki_pos = *ppos;
676 
677         if (type == READ)
678                 ret = call_read_iter(filp, &kiocb, iter);
679         else
680                 ret = call_write_iter(filp, &kiocb, iter);
681         BUG_ON(ret == -EIOCBQUEUED);
682         *ppos = kiocb.ki_pos;
683         return ret;
684 }
685 
686 /* Do it by hand, with file-ops */
687 static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
688                 loff_t *ppos, int type, rwf_t flags)
689 {
690         ssize_t ret = 0;
691 
692         if (flags & ~RWF_HIPRI)
693                 return -EOPNOTSUPP;
694 
695         while (iov_iter_count(iter)) {
696                 struct iovec iovec = iov_iter_iovec(iter);
697                 ssize_t nr;
698 
699                 if (type == READ) {
700                         nr = filp->f_op->read(filp, iovec.iov_base,
701                                               iovec.iov_len, ppos);
702                 } else {
703                         nr = filp->f_op->write(filp, iovec.iov_base,
704                                                iovec.iov_len, ppos);
705                 }
706 
707                 if (nr < 0) {
708                         if (!ret)
709                                 ret = nr;
710                         break;
711                 }
712                 ret += nr;
713                 if (nr != iovec.iov_len)
714                         break;
715                 iov_iter_advance(iter, nr);
716         }
717 
718         return ret;
719 }
720 
721 /**
722  * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace
723  *     into the kernel and check that it is valid.
724  *
725  * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE.
726  * @uvector: Pointer to the userspace array.
727  * @nr_segs: Number of elements in userspace array.
728  * @fast_segs: Number of elements in @fast_pointer.
729  * @fast_pointer: Pointer to (usually small on-stack) kernel array.
730  * @ret_pointer: (output parameter) Pointer to a variable that will point to
731  *     either @fast_pointer, a newly allocated kernel array, or NULL,
732  *     depending on which array was used.
733  *
734  * This function copies an array of &struct iovec of @nr_segs from
735  * userspace into the kernel and checks that each element is valid (e.g.
736  * it does not point to a kernel address or cause overflow by being too
737  * large, etc.).
738  *
739  * As an optimization, the caller may provide a pointer to a small
740  * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long
741  * (the size of this array, or 0 if unused, should be given in @fast_segs).
742  *
743  * @ret_pointer will always point to the array that was used, so the
744  * caller must take care not to call kfree() on it e.g. in case the
745  * @fast_pointer array was used and it was allocated on the stack.
746  *
747  * Return: The total number of bytes covered by the iovec array on success
748  *   or a negative error code on error.
749  */
750 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
751                               unsigned long nr_segs, unsigned long fast_segs,
752                               struct iovec *fast_pointer,
753                               struct iovec **ret_pointer)
754 {
755         unsigned long seg;
756         ssize_t ret;
757         struct iovec *iov = fast_pointer;
758 
759         /*
760          * SuS says "The readv() function *may* fail if the iovcnt argument
761          * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
762          * traditionally returned zero for zero segments, so...
763          */
764         if (nr_segs == 0) {
765                 ret = 0;
766                 goto out;
767         }
768 
769         /*
770          * First get the "struct iovec" from user memory and
771          * verify all the pointers
772          */
773         if (nr_segs > UIO_MAXIOV) {
774                 ret = -EINVAL;
775                 goto out;
776         }
777         if (nr_segs > fast_segs) {
778                 iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
779                 if (iov == NULL) {
780                         ret = -ENOMEM;
781                         goto out;
782                 }
783         }
784         if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
785                 ret = -EFAULT;
786                 goto out;
787         }
788 
789         /*
790          * According to the Single Unix Specification we should return EINVAL
791          * if an element length is < 0 when cast to ssize_t or if the
792          * total length would overflow the ssize_t return value of the
793          * system call.
794          *
795          * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
796          * overflow case.
797          */
798         ret = 0;
799         for (seg = 0; seg < nr_segs; seg++) {
800                 void __user *buf = iov[seg].iov_base;
801                 ssize_t len = (ssize_t)iov[seg].iov_len;
802 
803                 /* see if we we're about to use an invalid len or if
804                  * it's about to overflow ssize_t */
805                 if (len < 0) {
806                         ret = -EINVAL;
807                         goto out;
808                 }
809                 if (type >= 0
810                     && unlikely(!access_ok(buf, len))) {
811                         ret = -EFAULT;
812                         goto out;
813                 }
814                 if (len > MAX_RW_COUNT - ret) {
815                         len = MAX_RW_COUNT - ret;
816                         iov[seg].iov_len = len;
817                 }
818                 ret += len;
819         }
820 out:
821         *ret_pointer = iov;
822         return ret;
823 }
824 
825 #ifdef CONFIG_COMPAT
826 ssize_t compat_rw_copy_check_uvector(int type,
827                 const struct compat_iovec __user *uvector, unsigned long nr_segs,
828                 unsigned long fast_segs, struct iovec *fast_pointer,
829                 struct iovec **ret_pointer)
830 {
831         compat_ssize_t tot_len;
832         struct iovec *iov = *ret_pointer = fast_pointer;
833         ssize_t ret = 0;
834         int seg;
835 
836         /*
837          * SuS says "The readv() function *may* fail if the iovcnt argument
838          * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
839          * traditionally returned zero for zero segments, so...
840          */
841         if (nr_segs == 0)
842                 goto out;
843 
844         ret = -EINVAL;
845         if (nr_segs > UIO_MAXIOV)
846                 goto out;
847         if (nr_segs > fast_segs) {
848                 ret = -ENOMEM;
849                 iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
850                 if (iov == NULL)
851                         goto out;
852         }
853         *ret_pointer = iov;
854 
855         ret = -EFAULT;
856         if (!access_ok(uvector, nr_segs*sizeof(*uvector)))
857                 goto out;
858 
859         /*
860          * Single unix specification:
861          * We should -EINVAL if an element length is not >= 0 and fitting an
862          * ssize_t.
863          *
864          * In Linux, the total length is limited to MAX_RW_COUNT, there is
865          * no overflow possibility.
866          */
867         tot_len = 0;
868         ret = -EINVAL;
869         for (seg = 0; seg < nr_segs; seg++) {
870                 compat_uptr_t buf;
871                 compat_ssize_t len;
872 
873                 if (__get_user(len, &uvector->iov_len) ||
874                    __get_user(buf, &uvector->iov_base)) {
875                         ret = -EFAULT;
876                         goto out;
877                 }
878                 if (len < 0)    /* size_t not fitting in compat_ssize_t .. */
879                         goto out;
880                 if (type >= 0 &&
881                     !access_ok(compat_ptr(buf), len)) {
882                         ret = -EFAULT;
883                         goto out;
884                 }
885                 if (len > MAX_RW_COUNT - tot_len)
886                         len = MAX_RW_COUNT - tot_len;
887                 tot_len += len;
888                 iov->iov_base = compat_ptr(buf);
889                 iov->iov_len = (compat_size_t) len;
890                 uvector++;
891                 iov++;
892         }
893         ret = tot_len;
894 
895 out:
896         return ret;
897 }
898 #endif
899 
900 static ssize_t do_iter_read(struct file *file, struct iov_iter *iter,
901                 loff_t *pos, rwf_t flags)
902 {
903         size_t tot_len;
904         ssize_t ret = 0;
905 
906         if (!(file->f_mode & FMODE_READ))
907                 return -EBADF;
908         if (!(file->f_mode & FMODE_CAN_READ))
909                 return -EINVAL;
910 
911         tot_len = iov_iter_count(iter);
912         if (!tot_len)
913                 goto out;
914         ret = rw_verify_area(READ, file, pos, tot_len);
915         if (ret < 0)
916                 return ret;
917 
918         if (file->f_op->read_iter)
919                 ret = do_iter_readv_writev(file, iter, pos, READ, flags);
920         else
921                 ret = do_loop_readv_writev(file, iter, pos, READ, flags);
922 out:
923         if (ret >= 0)
924                 fsnotify_access(file);
925         return ret;
926 }
927 
928 ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
929                 rwf_t flags)
930 {
931         if (!file->f_op->read_iter)
932                 return -EINVAL;
933         return do_iter_read(file, iter, ppos, flags);
934 }
935 EXPORT_SYMBOL(vfs_iter_read);
936 
937 static ssize_t do_iter_write(struct file *file, struct iov_iter *iter,
938                 loff_t *pos, rwf_t flags)
939 {
940         size_t tot_len;
941         ssize_t ret = 0;
942 
943         if (!(file->f_mode & FMODE_WRITE))
944                 return -EBADF;
945         if (!(file->f_mode & FMODE_CAN_WRITE))
946                 return -EINVAL;
947 
948         tot_len = iov_iter_count(iter);
949         if (!tot_len)
950                 return 0;
951         ret = rw_verify_area(WRITE, file, pos, tot_len);
952         if (ret < 0)
953                 return ret;
954 
955         if (file->f_op->write_iter)
956                 ret = do_iter_readv_writev(file, iter, pos, WRITE, flags);
957         else
958                 ret = do_loop_readv_writev(file, iter, pos, WRITE, flags);
959         if (ret > 0)
960                 fsnotify_modify(file);
961         return ret;
962 }
963 
964 ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
965                 rwf_t flags)
966 {
967         if (!file->f_op->write_iter)
968                 return -EINVAL;
969         return do_iter_write(file, iter, ppos, flags);
970 }
971 EXPORT_SYMBOL(vfs_iter_write);
972 
973 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
974                   unsigned long vlen, loff_t *pos, rwf_t flags)
975 {
976         struct iovec iovstack[UIO_FASTIOV];
977         struct iovec *iov = iovstack;
978         struct iov_iter iter;
979         ssize_t ret;
980 
981         ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
982         if (ret >= 0) {
983                 ret = do_iter_read(file, &iter, pos, flags);
984                 kfree(iov);
985         }
986 
987         return ret;
988 }
989 
990 static ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
991                    unsigned long vlen, loff_t *pos, rwf_t flags)
992 {
993         struct iovec iovstack[UIO_FASTIOV];
994         struct iovec *iov = iovstack;
995         struct iov_iter iter;
996         ssize_t ret;
997 
998         ret = import_iovec(WRITE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
999         if (ret >= 0) {
1000                 file_start_write(file);
1001                 ret = do_iter_write(file, &iter, pos, flags);
1002                 file_end_write(file);
1003                 kfree(iov);
1004         }
1005         return ret;
1006 }
1007 
1008 static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec,
1009                         unsigned long vlen, rwf_t flags)
1010 {
1011         struct fd f = fdget_pos(fd);
1012         ssize_t ret = -EBADF;
1013 
1014         if (f.file) {
1015                 loff_t pos = file_pos_read(f.file);
1016                 ret = vfs_readv(f.file, vec, vlen, &pos, flags);
1017                 if (ret >= 0)
1018                         file_pos_write(f.file, pos);
1019                 fdput_pos(f);
1020         }
1021 
1022         if (ret > 0)
1023                 add_rchar(current, ret);
1024         inc_syscr(current);
1025         return ret;
1026 }
1027 
1028 static ssize_t do_writev(unsigned long fd, const struct iovec __user *vec,
1029                          unsigned long vlen, rwf_t flags)
1030 {
1031         struct fd f = fdget_pos(fd);
1032         ssize_t ret = -EBADF;
1033 
1034         if (f.file) {
1035                 loff_t pos = file_pos_read(f.file);
1036                 ret = vfs_writev(f.file, vec, vlen, &pos, flags);
1037                 if (ret >= 0)
1038                         file_pos_write(f.file, pos);
1039                 fdput_pos(f);
1040         }
1041 
1042         if (ret > 0)
1043                 add_wchar(current, ret);
1044         inc_syscw(current);
1045         return ret;
1046 }
1047 
1048 static inline loff_t pos_from_hilo(unsigned long high, unsigned long low)
1049 {
1050 #define HALF_LONG_BITS (BITS_PER_LONG / 2)
1051         return (((loff_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low;
1052 }
1053 
1054 static ssize_t do_preadv(unsigned long fd, const struct iovec __user *vec,
1055                          unsigned long vlen, loff_t pos, rwf_t flags)
1056 {
1057         struct fd f;
1058         ssize_t ret = -EBADF;
1059 
1060         if (pos < 0)
1061                 return -EINVAL;
1062 
1063         f = fdget(fd);
1064         if (f.file) {
1065                 ret = -ESPIPE;
1066                 if (f.file->f_mode & FMODE_PREAD)
1067                         ret = vfs_readv(f.file, vec, vlen, &pos, flags);
1068                 fdput(f);
1069         }
1070 
1071         if (ret > 0)
1072                 add_rchar(current, ret);
1073         inc_syscr(current);
1074         return ret;
1075 }
1076 
1077 static ssize_t do_pwritev(unsigned long fd, const struct iovec __user *vec,
1078                           unsigned long vlen, loff_t pos, rwf_t flags)
1079 {
1080         struct fd f;
1081         ssize_t ret = -EBADF;
1082 
1083         if (pos < 0)
1084                 return -EINVAL;
1085 
1086         f = fdget(fd);
1087         if (f.file) {
1088                 ret = -ESPIPE;
1089                 if (f.file->f_mode & FMODE_PWRITE)
1090                         ret = vfs_writev(f.file, vec, vlen, &pos, flags);
1091                 fdput(f);
1092         }
1093 
1094         if (ret > 0)
1095                 add_wchar(current, ret);
1096         inc_syscw(current);
1097         return ret;
1098 }
1099 
1100 SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
1101                 unsigned long, vlen)
1102 {
1103         return do_readv(fd, vec, vlen, 0);
1104 }
1105 
1106 SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
1107                 unsigned long, vlen)
1108 {
1109         return do_writev(fd, vec, vlen, 0);
1110 }
1111 
1112 SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
1113                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
1114 {
1115         loff_t pos = pos_from_hilo(pos_h, pos_l);
1116 
1117         return do_preadv(fd, vec, vlen, pos, 0);
1118 }
1119 
1120 SYSCALL_DEFINE6(preadv2, unsigned long, fd, const struct iovec __user *, vec,
1121                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
1122                 rwf_t, flags)
1123 {
1124         loff_t pos = pos_from_hilo(pos_h, pos_l);
1125 
1126         if (pos == -1)
1127                 return do_readv(fd, vec, vlen, flags);
1128 
1129         return do_preadv(fd, vec, vlen, pos, flags);
1130 }
1131 
1132 SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
1133                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
1134 {
1135         loff_t pos = pos_from_hilo(pos_h, pos_l);
1136 
1137         return do_pwritev(fd, vec, vlen, pos, 0);
1138 }
1139 
1140 SYSCALL_DEFINE6(pwritev2, unsigned long, fd, const struct iovec __user *, vec,
1141                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
1142                 rwf_t, flags)
1143 {
1144         loff_t pos = pos_from_hilo(pos_h, pos_l);
1145 
1146         if (pos == -1)
1147                 return do_writev(fd, vec, vlen, flags);
1148 
1149         return do_pwritev(fd, vec, vlen, pos, flags);
1150 }
1151 
1152 #ifdef CONFIG_COMPAT
1153 static size_t compat_readv(struct file *file,
1154                            const struct compat_iovec __user *vec,
1155                            unsigned long vlen, loff_t *pos, rwf_t flags)
1156 {
1157         struct iovec iovstack[UIO_FASTIOV];
1158         struct iovec *iov = iovstack;
1159         struct iov_iter iter;
1160         ssize_t ret;
1161 
1162         ret = compat_import_iovec(READ, vec, vlen, UIO_FASTIOV, &iov, &iter);
1163         if (ret >= 0) {
1164                 ret = do_iter_read(file, &iter, pos, flags);
1165                 kfree(iov);
1166         }
1167         if (ret > 0)
1168                 add_rchar(current, ret);
1169         inc_syscr(current);
1170         return ret;
1171 }
1172 
1173 static size_t do_compat_readv(compat_ulong_t fd,
1174                                  const struct compat_iovec __user *vec,
1175                                  compat_ulong_t vlen, rwf_t flags)
1176 {
1177         struct fd f = fdget_pos(fd);
1178         ssize_t ret;
1179         loff_t pos;
1180 
1181         if (!f.file)
1182                 return -EBADF;
1183         pos = f.file->f_pos;
1184         ret = compat_readv(f.file, vec, vlen, &pos, flags);
1185         if (ret >= 0)
1186                 f.file->f_pos = pos;
1187         fdput_pos(f);
1188         return ret;
1189 
1190 }
1191 
1192 COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
1193                 const struct compat_iovec __user *,vec,
1194                 compat_ulong_t, vlen)
1195 {
1196         return do_compat_readv(fd, vec, vlen, 0);
1197 }
1198 
1199 static long do_compat_preadv64(unsigned long fd,
1200                                   const struct compat_iovec __user *vec,
1201                                   unsigned long vlen, loff_t pos, rwf_t flags)
1202 {
1203         struct fd f;
1204         ssize_t ret;
1205 
1206         if (pos < 0)
1207                 return -EINVAL;
1208         f = fdget(fd);
1209         if (!f.file)
1210                 return -EBADF;
1211         ret = -ESPIPE;
1212         if (f.file->f_mode & FMODE_PREAD)
1213                 ret = compat_readv(f.file, vec, vlen, &pos, flags);
1214         fdput(f);
1215         return ret;
1216 }
1217 
1218 #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64
1219 COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd,
1220                 const struct compat_iovec __user *,vec,
1221                 unsigned long, vlen, loff_t, pos)
1222 {
1223         return do_compat_preadv64(fd, vec, vlen, pos, 0);
1224 }
1225 #endif
1226 
1227 COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd,
1228                 const struct compat_iovec __user *,vec,
1229                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
1230 {
1231         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1232 
1233         return do_compat_preadv64(fd, vec, vlen, pos, 0);
1234 }
1235 
1236 #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64V2
1237 COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
1238                 const struct compat_iovec __user *,vec,
1239                 unsigned long, vlen, loff_t, pos, rwf_t, flags)
1240 {
1241         if (pos == -1)
1242                 return do_compat_readv(fd, vec, vlen, flags);
1243 
1244         return do_compat_preadv64(fd, vec, vlen, pos, flags);
1245 }
1246 #endif
1247 
1248 COMPAT_SYSCALL_DEFINE6(preadv2, compat_ulong_t, fd,
1249                 const struct compat_iovec __user *,vec,
1250                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high,
1251                 rwf_t, flags)
1252 {
1253         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1254 
1255         if (pos == -1)
1256                 return do_compat_readv(fd, vec, vlen, flags);
1257 
1258         return do_compat_preadv64(fd, vec, vlen, pos, flags);
1259 }
1260 
1261 static size_t compat_writev(struct file *file,
1262                             const struct compat_iovec __user *vec,
1263                             unsigned long vlen, loff_t *pos, rwf_t flags)
1264 {
1265         struct iovec iovstack[UIO_FASTIOV];
1266         struct iovec *iov = iovstack;
1267         struct iov_iter iter;
1268         ssize_t ret;
1269 
1270         ret = compat_import_iovec(WRITE, vec, vlen, UIO_FASTIOV, &iov, &iter);
1271         if (ret >= 0) {
1272                 file_start_write(file);
1273                 ret = do_iter_write(file, &iter, pos, flags);
1274                 file_end_write(file);
1275                 kfree(iov);
1276         }
1277         if (ret > 0)
1278                 add_wchar(current, ret);
1279         inc_syscw(current);
1280         return ret;
1281 }
1282 
1283 static size_t do_compat_writev(compat_ulong_t fd,
1284                                   const struct compat_iovec __user* vec,
1285                                   compat_ulong_t vlen, rwf_t flags)
1286 {
1287         struct fd f = fdget_pos(fd);
1288         ssize_t ret;
1289         loff_t pos;
1290 
1291         if (!f.file)
1292                 return -EBADF;
1293         pos = f.file->f_pos;
1294         ret = compat_writev(f.file, vec, vlen, &pos, flags);
1295         if (ret >= 0)
1296                 f.file->f_pos = pos;
1297         fdput_pos(f);
1298         return ret;
1299 }
1300 
1301 COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd,
1302                 const struct compat_iovec __user *, vec,
1303                 compat_ulong_t, vlen)
1304 {
1305         return do_compat_writev(fd, vec, vlen, 0);
1306 }
1307 
1308 static long do_compat_pwritev64(unsigned long fd,
1309                                    const struct compat_iovec __user *vec,
1310                                    unsigned long vlen, loff_t pos, rwf_t flags)
1311 {
1312         struct fd f;
1313         ssize_t ret;
1314 
1315         if (pos < 0)
1316                 return -EINVAL;
1317         f = fdget(fd);
1318         if (!f.file)
1319                 return -EBADF;
1320         ret = -ESPIPE;
1321         if (f.file->f_mode & FMODE_PWRITE)
1322                 ret = compat_writev(f.file, vec, vlen, &pos, flags);
1323         fdput(f);
1324         return ret;
1325 }
1326 
1327 #ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64
1328 COMPAT_SYSCALL_DEFINE4(pwritev64, unsigned long, fd,
1329                 const struct compat_iovec __user *,vec,
1330                 unsigned long, vlen, loff_t, pos)
1331 {
1332         return do_compat_pwritev64(fd, vec, vlen, pos, 0);
1333 }
1334 #endif
1335 
1336 COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
1337                 const struct compat_iovec __user *,vec,
1338                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
1339 {
1340         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1341 
1342         return do_compat_pwritev64(fd, vec, vlen, pos, 0);
1343 }
1344 
1345 #ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
1346 COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
1347                 const struct compat_iovec __user *,vec,
1348                 unsigned long, vlen, loff_t, pos, rwf_t, flags)
1349 {
1350         if (pos == -1)
1351                 return do_compat_writev(fd, vec, vlen, flags);
1352 
1353         return do_compat_pwritev64(fd, vec, vlen, pos, flags);
1354 }
1355 #endif
1356 
1357 COMPAT_SYSCALL_DEFINE6(pwritev2, compat_ulong_t, fd,
1358                 const struct compat_iovec __user *,vec,
1359                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high, rwf_t, flags)
1360 {
1361         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1362 
1363         if (pos == -1)
1364                 return do_compat_writev(fd, vec, vlen, flags);
1365 
1366         return do_compat_pwritev64(fd, vec, vlen, pos, flags);
1367 }
1368 
1369 #endif
1370 
1371 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
1372                            size_t count, loff_t max)
1373 {
1374         struct fd in, out;
1375         struct inode *in_inode, *out_inode;
1376         loff_t pos;
1377         loff_t out_pos;
1378         ssize_t retval;
1379         int fl;
1380 
1381         /*
1382          * Get input file, and verify that it is ok..
1383          */
1384         retval = -EBADF;
1385         in = fdget(in_fd);
1386         if (!in.file)
1387                 goto out;
1388         if (!(in.file->f_mode & FMODE_READ))
1389                 goto fput_in;
1390         retval = -ESPIPE;
1391         if (!ppos) {
1392                 pos = in.file->f_pos;
1393         } else {
1394                 pos = *ppos;
1395                 if (!(in.file->f_mode & FMODE_PREAD))
1396                         goto fput_in;
1397         }
1398         retval = rw_verify_area(READ, in.file, &pos, count);
1399         if (retval < 0)
1400                 goto fput_in;
1401         if (count > MAX_RW_COUNT)
1402                 count =  MAX_RW_COUNT;
1403 
1404         /*
1405          * Get output file, and verify that it is ok..
1406          */
1407         retval = -EBADF;
1408         out = fdget(out_fd);
1409         if (!out.file)
1410                 goto fput_in;
1411         if (!(out.file->f_mode & FMODE_WRITE))
1412                 goto fput_out;
1413         in_inode = file_inode(in.file);
1414         out_inode = file_inode(out.file);
1415         out_pos = out.file->f_pos;
1416         retval = rw_verify_area(WRITE, out.file, &out_pos, count);
1417         if (retval < 0)
1418                 goto fput_out;
1419 
1420         if (!max)
1421                 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
1422 
1423         if (unlikely(pos + count > max)) {
1424                 retval = -EOVERFLOW;
1425                 if (pos >= max)
1426                         goto fput_out;
1427                 count = max - pos;
1428         }
1429 
1430         fl = 0;
1431 #if 0
1432         /*
1433          * We need to debate whether we can enable this or not. The
1434          * man page documents EAGAIN return for the output at least,
1435          * and the application is arguably buggy if it doesn't expect
1436          * EAGAIN on a non-blocking file descriptor.
1437          */
1438         if (in.file->f_flags & O_NONBLOCK)
1439                 fl = SPLICE_F_NONBLOCK;
1440 #endif
1441         file_start_write(out.file);
1442         retval = do_splice_direct(in.file, &pos, out.file, &out_pos, count, fl);
1443         file_end_write(out.file);
1444 
1445         if (retval > 0) {
1446                 add_rchar(current, retval);
1447                 add_wchar(current, retval);
1448                 fsnotify_access(in.file);
1449                 fsnotify_modify(out.file);
1450                 out.file->f_pos = out_pos;
1451                 if (ppos)
1452                         *ppos = pos;
1453                 else
1454                         in.file->f_pos = pos;
1455         }
1456 
1457         inc_syscr(current);
1458         inc_syscw(current);
1459         if (pos > max)
1460                 retval = -EOVERFLOW;
1461 
1462 fput_out:
1463         fdput(out);
1464 fput_in:
1465         fdput(in);
1466 out:
1467         return retval;
1468 }
1469 
1470 SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, off_t __user *, offset, size_t, count)
1471 {
1472         loff_t pos;
1473         off_t off;
1474         ssize_t ret;
1475 
1476         if (offset) {
1477                 if (unlikely(get_user(off, offset)))
1478                         return -EFAULT;
1479                 pos = off;
1480                 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
1481                 if (unlikely(put_user(pos, offset)))
1482                         return -EFAULT;
1483                 return ret;
1484         }
1485 
1486         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1487 }
1488 
1489 SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, loff_t __user *, offset, size_t, count)
1490 {
1491         loff_t pos;
1492         ssize_t ret;
1493 
1494         if (offset) {
1495                 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
1496                         return -EFAULT;
1497                 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
1498                 if (unlikely(put_user(pos, offset)))
1499                         return -EFAULT;
1500                 return ret;
1501         }
1502 
1503         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1504 }
1505 
1506 #ifdef CONFIG_COMPAT
1507 COMPAT_SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd,
1508                 compat_off_t __user *, offset, compat_size_t, count)
1509 {
1510         loff_t pos;
1511         off_t off;
1512         ssize_t ret;
1513 
1514         if (offset) {
1515                 if (unlikely(get_user(off, offset)))
1516                         return -EFAULT;
1517                 pos = off;
1518                 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
1519                 if (unlikely(put_user(pos, offset)))
1520                         return -EFAULT;
1521                 return ret;
1522         }
1523 
1524         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1525 }
1526 
1527 COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
1528                 compat_loff_t __user *, offset, compat_size_t, count)
1529 {
1530         loff_t pos;
1531         ssize_t ret;
1532 
1533         if (offset) {
1534                 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
1535                         return -EFAULT;
1536                 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
1537                 if (unlikely(put_user(pos, offset)))
1538                         return -EFAULT;
1539                 return ret;
1540         }
1541 
1542         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1543 }
1544 #endif
1545 
1546 /*
1547  * copy_file_range() differs from regular file read and write in that it
1548  * specifically allows return partial success.  When it does so is up to
1549  * the copy_file_range method.
1550  */
1551 ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
1552                             struct file *file_out, loff_t pos_out,
1553                             size_t len, unsigned int flags)
1554 {
1555         struct inode *inode_in = file_inode(file_in);
1556         struct inode *inode_out = file_inode(file_out);
1557         ssize_t ret;
1558 
1559         if (flags != 0)
1560                 return -EINVAL;
1561 
1562         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
1563                 return -EISDIR;
1564         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
1565                 return -EINVAL;
1566 
1567         ret = rw_verify_area(READ, file_in, &pos_in, len);
1568         if (unlikely(ret))
1569                 return ret;
1570 
1571         ret = rw_verify_area(WRITE, file_out, &pos_out, len);
1572         if (unlikely(ret))
1573                 return ret;
1574 
1575         if (!(file_in->f_mode & FMODE_READ) ||
1576             !(file_out->f_mode & FMODE_WRITE) ||
1577             (file_out->f_flags & O_APPEND))
1578                 return -EBADF;
1579 
1580         /* this could be relaxed once a method supports cross-fs copies */
1581         if (inode_in->i_sb != inode_out->i_sb)
1582                 return -EXDEV;
1583 
1584         if (len == 0)
1585                 return 0;
1586 
1587         file_start_write(file_out);
1588 
1589         /*
1590          * Try cloning first, this is supported by more file systems, and
1591          * more efficient if both clone and copy are supported (e.g. NFS).
1592          */
1593         if (file_in->f_op->remap_file_range) {
1594                 loff_t cloned;
1595 
1596                 cloned = file_in->f_op->remap_file_range(file_in, pos_in,
1597                                 file_out, pos_out,
1598                                 min_t(loff_t, MAX_RW_COUNT, len),
1599                                 REMAP_FILE_CAN_SHORTEN);
1600                 if (cloned > 0) {
1601                         ret = cloned;
1602                         goto done;
1603                 }
1604         }
1605 
1606         if (file_out->f_op->copy_file_range) {
1607                 ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
1608                                                       pos_out, len, flags);
1609                 if (ret != -EOPNOTSUPP)
1610                         goto done;
1611         }
1612 
1613         ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
1614                         len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
1615 
1616 done:
1617         if (ret > 0) {
1618                 fsnotify_access(file_in);
1619                 add_rchar(current, ret);
1620                 fsnotify_modify(file_out);
1621                 add_wchar(current, ret);
1622         }
1623 
1624         inc_syscr(current);
1625         inc_syscw(current);
1626 
1627         file_end_write(file_out);
1628 
1629         return ret;
1630 }
1631 EXPORT_SYMBOL(vfs_copy_file_range);
1632 
1633 SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in,
1634                 int, fd_out, loff_t __user *, off_out,
1635                 size_t, len, unsigned int, flags)
1636 {
1637         loff_t pos_in;
1638         loff_t pos_out;
1639         struct fd f_in;
1640         struct fd f_out;
1641         ssize_t ret = -EBADF;
1642 
1643         f_in = fdget(fd_in);
1644         if (!f_in.file)
1645                 goto out2;
1646 
1647         f_out = fdget(fd_out);
1648         if (!f_out.file)
1649                 goto out1;
1650 
1651         ret = -EFAULT;
1652         if (off_in) {
1653                 if (copy_from_user(&pos_in, off_in, sizeof(loff_t)))
1654                         goto out;
1655         } else {
1656                 pos_in = f_in.file->f_pos;
1657         }
1658 
1659         if (off_out) {
1660                 if (copy_from_user(&pos_out, off_out, sizeof(loff_t)))
1661                         goto out;
1662         } else {
1663                 pos_out = f_out.file->f_pos;
1664         }
1665 
1666         ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len,
1667                                   flags);
1668         if (ret > 0) {
1669                 pos_in += ret;
1670                 pos_out += ret;
1671 
1672                 if (off_in) {
1673                         if (copy_to_user(off_in, &pos_in, sizeof(loff_t)))
1674                                 ret = -EFAULT;
1675                 } else {
1676                         f_in.file->f_pos = pos_in;
1677                 }
1678 
1679                 if (off_out) {
1680                         if (copy_to_user(off_out, &pos_out, sizeof(loff_t)))
1681                                 ret = -EFAULT;
1682                 } else {
1683                         f_out.file->f_pos = pos_out;
1684                 }
1685         }
1686 
1687 out:
1688         fdput(f_out);
1689 out1:
1690         fdput(f_in);
1691 out2:
1692         return ret;
1693 }
1694 
1695 static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
1696                              bool write)
1697 {
1698         struct inode *inode = file_inode(file);
1699 
1700         if (unlikely(pos < 0 || len < 0))
1701                 return -EINVAL;
1702 
1703          if (unlikely((loff_t) (pos + len) < 0))
1704                 return -EINVAL;
1705 
1706         if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
1707                 loff_t end = len ? pos + len - 1 : OFFSET_MAX;
1708                 int retval;
1709 
1710                 retval = locks_mandatory_area(inode, file, pos, end,
1711                                 write ? F_WRLCK : F_RDLCK);
1712                 if (retval < 0)
1713                         return retval;
1714         }
1715 
1716         return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
1717 }
1718 /*
1719  * Ensure that we don't remap a partial EOF block in the middle of something
1720  * else.  Assume that the offsets have already been checked for block
1721  * alignment.
1722  *
1723  * For deduplication we always scale down to the previous block because we
1724  * can't meaningfully compare post-EOF contents.
1725  *
1726  * For clone we only link a partial EOF block above the destination file's EOF.
1727  *
1728  * Shorten the request if possible.
1729  */
1730 static int generic_remap_check_len(struct inode *inode_in,
1731                                    struct inode *inode_out,
1732                                    loff_t pos_out,
1733                                    loff_t *len,
1734                                    unsigned int remap_flags)
1735 {
1736         u64 blkmask = i_blocksize(inode_in) - 1;
1737         loff_t new_len = *len;
1738 
1739         if ((*len & blkmask) == 0)
1740                 return 0;
1741 
1742         if ((remap_flags & REMAP_FILE_DEDUP) ||
1743             pos_out + *len < i_size_read(inode_out))
1744                 new_len &= ~blkmask;
1745 
1746         if (new_len == *len)
1747                 return 0;
1748 
1749         if (remap_flags & REMAP_FILE_CAN_SHORTEN) {
1750                 *len = new_len;
1751                 return 0;
1752         }
1753 
1754         return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
1755 }
1756 
1757 /*
1758  * Read a page's worth of file data into the page cache.  Return the page
1759  * locked.
1760  */
1761 static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
1762 {
1763         struct page *page;
1764 
1765         page = read_mapping_page(inode->i_mapping, offset >> PAGE_SHIFT, NULL);
1766         if (IS_ERR(page))
1767                 return page;
1768         if (!PageUptodate(page)) {
1769                 put_page(page);
1770                 return ERR_PTR(-EIO);
1771         }
1772         lock_page(page);
1773         return page;
1774 }
1775 
1776 /*
1777  * Compare extents of two files to see if they are the same.
1778  * Caller must have locked both inodes to prevent write races.
1779  */
1780 static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
1781                                          struct inode *dest, loff_t destoff,
1782                                          loff_t len, bool *is_same)
1783 {
1784         loff_t src_poff;
1785         loff_t dest_poff;
1786         void *src_addr;
1787         void *dest_addr;
1788         struct page *src_page;
1789         struct page *dest_page;
1790         loff_t cmp_len;
1791         bool same;
1792         int error;
1793 
1794         error = -EINVAL;
1795         same = true;
1796         while (len) {
1797                 src_poff = srcoff & (PAGE_SIZE - 1);
1798                 dest_poff = destoff & (PAGE_SIZE - 1);
1799                 cmp_len = min(PAGE_SIZE - src_poff,
1800                               PAGE_SIZE - dest_poff);
1801                 cmp_len = min(cmp_len, len);
1802                 if (cmp_len <= 0)
1803                         goto out_error;
1804 
1805                 src_page = vfs_dedupe_get_page(src, srcoff);
1806                 if (IS_ERR(src_page)) {
1807                         error = PTR_ERR(src_page);
1808                         goto out_error;
1809                 }
1810                 dest_page = vfs_dedupe_get_page(dest, destoff);
1811                 if (IS_ERR(dest_page)) {
1812                         error = PTR_ERR(dest_page);
1813                         unlock_page(src_page);
1814                         put_page(src_page);
1815                         goto out_error;
1816                 }
1817                 src_addr = kmap_atomic(src_page);
1818                 dest_addr = kmap_atomic(dest_page);
1819 
1820                 flush_dcache_page(src_page);
1821                 flush_dcache_page(dest_page);
1822 
1823                 if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
1824                         same = false;
1825 
1826                 kunmap_atomic(dest_addr);
1827                 kunmap_atomic(src_addr);
1828                 unlock_page(dest_page);
1829                 unlock_page(src_page);
1830                 put_page(dest_page);
1831                 put_page(src_page);
1832 
1833                 if (!same)
1834                         break;
1835 
1836                 srcoff += cmp_len;
1837                 destoff += cmp_len;
1838                 len -= cmp_len;
1839         }
1840 
1841         *is_same = same;
1842         return 0;
1843 
1844 out_error:
1845         return error;
1846 }
1847 
1848 /*
1849  * Check that the two inodes are eligible for cloning, the ranges make
1850  * sense, and then flush all dirty data.  Caller must ensure that the
1851  * inodes have been locked against any other modifications.
1852  *
1853  * If there's an error, then the usual negative error code is returned.
1854  * Otherwise returns 0 with *len set to the request length.
1855  */
1856 int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
1857                                   struct file *file_out, loff_t pos_out,
1858                                   loff_t *len, unsigned int remap_flags)
1859 {
1860         struct inode *inode_in = file_inode(file_in);
1861         struct inode *inode_out = file_inode(file_out);
1862         bool same_inode = (inode_in == inode_out);
1863         int ret;
1864 
1865         /* Don't touch certain kinds of inodes */
1866         if (IS_IMMUTABLE(inode_out))
1867                 return -EPERM;
1868 
1869         if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
1870                 return -ETXTBSY;
1871 
1872         /* Don't reflink dirs, pipes, sockets... */
1873         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
1874                 return -EISDIR;
1875         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
1876                 return -EINVAL;
1877 
1878         /* Zero length dedupe exits immediately; reflink goes to EOF. */
1879         if (*len == 0) {
1880                 loff_t isize = i_size_read(inode_in);
1881 
1882                 if ((remap_flags & REMAP_FILE_DEDUP) || pos_in == isize)
1883                         return 0;
1884                 if (pos_in > isize)
1885                         return -EINVAL;
1886                 *len = isize - pos_in;
1887                 if (*len == 0)
1888                         return 0;
1889         }
1890 
1891         /* Check that we don't violate system file offset limits. */
1892         ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
1893                         remap_flags);
1894         if (ret)
1895                 return ret;
1896 
1897         /* Wait for the completion of any pending IOs on both files */
1898         inode_dio_wait(inode_in);
1899         if (!same_inode)
1900                 inode_dio_wait(inode_out);
1901 
1902         ret = filemap_write_and_wait_range(inode_in->i_mapping,
1903                         pos_in, pos_in + *len - 1);
1904         if (ret)
1905                 return ret;
1906 
1907         ret = filemap_write_and_wait_range(inode_out->i_mapping,
1908                         pos_out, pos_out + *len - 1);
1909         if (ret)
1910                 return ret;
1911 
1912         /*
1913          * Check that the extents are the same.
1914          */
1915         if (remap_flags & REMAP_FILE_DEDUP) {
1916                 bool            is_same = false;
1917 
1918                 ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
1919                                 inode_out, pos_out, *len, &is_same);
1920                 if (ret)
1921                         return ret;
1922                 if (!is_same)
1923                         return -EBADE;
1924         }
1925 
1926         ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
1927                         remap_flags);
1928         if (ret)
1929                 return ret;
1930 
1931         /* If can't alter the file contents, we're done. */
1932         if (!(remap_flags & REMAP_FILE_DEDUP)) {
1933                 /* Update the timestamps, since we can alter file contents. */
1934                 if (!(file_out->f_mode & FMODE_NOCMTIME)) {
1935                         ret = file_update_time(file_out);
1936                         if (ret)
1937                                 return ret;
1938                 }
1939 
1940                 /*
1941                  * Clear the security bits if the process is not being run by
1942                  * root.  This keeps people from modifying setuid and setgid
1943                  * binaries.
1944                  */
1945                 ret = file_remove_privs(file_out);
1946                 if (ret)
1947                         return ret;
1948         }
1949 
1950         return 0;
1951 }
1952 EXPORT_SYMBOL(generic_remap_file_range_prep);
1953 
1954 loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
1955                            struct file *file_out, loff_t pos_out,
1956                            loff_t len, unsigned int remap_flags)
1957 {
1958         struct inode *inode_in = file_inode(file_in);
1959         struct inode *inode_out = file_inode(file_out);
1960         loff_t ret;
1961 
1962         WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
1963 
1964         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
1965                 return -EISDIR;
1966         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
1967                 return -EINVAL;
1968 
1969         /*
1970          * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on
1971          * the same mount. Practically, they only need to be on the same file
1972          * system.
1973          */
1974         if (inode_in->i_sb != inode_out->i_sb)
1975                 return -EXDEV;
1976 
1977         if (!(file_in->f_mode & FMODE_READ) ||
1978             !(file_out->f_mode & FMODE_WRITE) ||
1979             (file_out->f_flags & O_APPEND))
1980                 return -EBADF;
1981 
1982         if (!file_in->f_op->remap_file_range)
1983                 return -EOPNOTSUPP;
1984 
1985         ret = remap_verify_area(file_in, pos_in, len, false);
1986         if (ret)
1987                 return ret;
1988 
1989         ret = remap_verify_area(file_out, pos_out, len, true);
1990         if (ret)
1991                 return ret;
1992 
1993         ret = file_in->f_op->remap_file_range(file_in, pos_in,
1994                         file_out, pos_out, len, remap_flags);
1995         if (ret < 0)
1996                 return ret;
1997 
1998         fsnotify_access(file_in);
1999         fsnotify_modify(file_out);
2000         return ret;
2001 }
2002 EXPORT_SYMBOL(do_clone_file_range);
2003 
2004 loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
2005                             struct file *file_out, loff_t pos_out,
2006                             loff_t len, unsigned int remap_flags)
2007 {
2008         loff_t ret;
2009 
2010         file_start_write(file_out);
2011         ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
2012                                   remap_flags);
2013         file_end_write(file_out);
2014 
2015         return ret;
2016 }
2017 EXPORT_SYMBOL(vfs_clone_file_range);
2018 
2019 /* Check whether we are allowed to dedupe the destination file */
2020 static bool allow_file_dedupe(struct file *file)
2021 {
2022         if (capable(CAP_SYS_ADMIN))
2023                 return true;
2024         if (file->f_mode & FMODE_WRITE)
2025                 return true;
2026         if (uid_eq(current_fsuid(), file_inode(file)->i_uid))
2027                 return true;
2028         if (!inode_permission(file_inode(file), MAY_WRITE))
2029                 return true;
2030         return false;
2031 }
2032 
2033 loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
2034                                  struct file *dst_file, loff_t dst_pos,
2035                                  loff_t len, unsigned int remap_flags)
2036 {
2037         loff_t ret;
2038 
2039         WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP |
2040                                      REMAP_FILE_CAN_SHORTEN));
2041 
2042         ret = mnt_want_write_file(dst_file);
2043         if (ret)
2044                 return ret;
2045 
2046         ret = remap_verify_area(dst_file, dst_pos, len, true);
2047         if (ret < 0)
2048                 goto out_drop_write;
2049 
2050         ret = -EPERM;
2051         if (!allow_file_dedupe(dst_file))
2052                 goto out_drop_write;
2053 
2054         ret = -EXDEV;
2055         if (src_file->f_path.mnt != dst_file->f_path.mnt)
2056                 goto out_drop_write;
2057 
2058         ret = -EISDIR;
2059         if (S_ISDIR(file_inode(dst_file)->i_mode))
2060                 goto out_drop_write;
2061 
2062         ret = -EINVAL;
2063         if (!dst_file->f_op->remap_file_range)
2064                 goto out_drop_write;
2065 
2066         if (len == 0) {
2067                 ret = 0;
2068                 goto out_drop_write;
2069         }
2070 
2071         ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
2072                         dst_pos, len, remap_flags | REMAP_FILE_DEDUP);
2073 out_drop_write:
2074         mnt_drop_write_file(dst_file);
2075 
2076         return ret;
2077 }
2078 EXPORT_SYMBOL(vfs_dedupe_file_range_one);
2079 
2080 int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
2081 {
2082         struct file_dedupe_range_info *info;
2083         struct inode *src = file_inode(file);
2084         u64 off;
2085         u64 len;
2086         int i;
2087         int ret;
2088         u16 count = same->dest_count;
2089         loff_t deduped;
2090 
2091         if (!(file->f_mode & FMODE_READ))
2092                 return -EINVAL;
2093 
2094         if (same->reserved1 || same->reserved2)
2095                 return -EINVAL;
2096 
2097         off = same->src_offset;
2098         len = same->src_length;
2099 
2100         if (S_ISDIR(src->i_mode))
2101                 return -EISDIR;
2102 
2103         if (!S_ISREG(src->i_mode))
2104                 return -EINVAL;
2105 
2106         if (!file->f_op->remap_file_range)
2107                 return -EOPNOTSUPP;
2108 
2109         ret = remap_verify_area(file, off, len, false);
2110         if (ret < 0)
2111                 return ret;
2112         ret = 0;
2113 
2114         if (off + len > i_size_read(src))
2115                 return -EINVAL;
2116 
2117         /* Arbitrary 1G limit on a single dedupe request, can be raised. */
2118         len = min_t(u64, len, 1 << 30);
2119 
2120         /* pre-format output fields to sane values */
2121         for (i = 0; i < count; i++) {
2122                 same->info[i].bytes_deduped = 0ULL;
2123                 same->info[i].status = FILE_DEDUPE_RANGE_SAME;
2124         }
2125 
2126         for (i = 0, info = same->info; i < count; i++, info++) {
2127                 struct fd dst_fd = fdget(info->dest_fd);
2128                 struct file *dst_file = dst_fd.file;
2129 
2130                 if (!dst_file) {
2131                         info->status = -EBADF;
2132                         goto next_loop;
2133                 }
2134 
2135                 if (info->reserved) {
2136                         info->status = -EINVAL;
2137                         goto next_fdput;
2138                 }
2139 
2140                 deduped = vfs_dedupe_file_range_one(file, off, dst_file,
2141                                                     info->dest_offset, len,
2142                                                     REMAP_FILE_CAN_SHORTEN);
2143                 if (deduped == -EBADE)
2144                         info->status = FILE_DEDUPE_RANGE_DIFFERS;
2145                 else if (deduped < 0)
2146                         info->status = deduped;
2147                 else
2148                         info->bytes_deduped = len;
2149 
2150 next_fdput:
2151                 fdput(dst_fd);
2152 next_loop:
2153                 if (fatal_signal_pending(current))
2154                         break;
2155         }
2156         return ret;
2157 }
2158 EXPORT_SYMBOL(vfs_dedupe_file_range);
2159 

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