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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(get_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 ssize_t __vfs_write(struct file *file, const char __user *p, size_t count,
482                     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(get_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(get_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_mode & FMODE_STREAM ? 0 : file->f_pos;
564 }
565 
566 static inline void file_pos_write(struct file *file, loff_t pos)
567 {
568         if ((file->f_mode & FMODE_STREAM) == 0)
569                 file->f_pos = pos;
570 }
571 
572 ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count)
573 {
574         struct fd f = fdget_pos(fd);
575         ssize_t ret = -EBADF;
576 
577         if (f.file) {
578                 loff_t pos = file_pos_read(f.file);
579                 ret = vfs_read(f.file, buf, count, &pos);
580                 if (ret >= 0)
581                         file_pos_write(f.file, pos);
582                 fdput_pos(f);
583         }
584         return ret;
585 }
586 
587 SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
588 {
589         return ksys_read(fd, buf, count);
590 }
591 
592 ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count)
593 {
594         struct fd f = fdget_pos(fd);
595         ssize_t ret = -EBADF;
596 
597         if (f.file) {
598                 loff_t pos = file_pos_read(f.file);
599                 ret = vfs_write(f.file, buf, count, &pos);
600                 if (ret >= 0)
601                         file_pos_write(f.file, pos);
602                 fdput_pos(f);
603         }
604 
605         return ret;
606 }
607 
608 SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf,
609                 size_t, count)
610 {
611         return ksys_write(fd, buf, count);
612 }
613 
614 ssize_t ksys_pread64(unsigned int fd, char __user *buf, size_t count,
615                      loff_t pos)
616 {
617         struct fd f;
618         ssize_t ret = -EBADF;
619 
620         if (pos < 0)
621                 return -EINVAL;
622 
623         f = fdget(fd);
624         if (f.file) {
625                 ret = -ESPIPE;
626                 if (f.file->f_mode & FMODE_PREAD)
627                         ret = vfs_read(f.file, buf, count, &pos);
628                 fdput(f);
629         }
630 
631         return ret;
632 }
633 
634 SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf,
635                         size_t, count, loff_t, pos)
636 {
637         return ksys_pread64(fd, buf, count, pos);
638 }
639 
640 ssize_t ksys_pwrite64(unsigned int fd, const char __user *buf,
641                       size_t count, loff_t pos)
642 {
643         struct fd f;
644         ssize_t ret = -EBADF;
645 
646         if (pos < 0)
647                 return -EINVAL;
648 
649         f = fdget(fd);
650         if (f.file) {
651                 ret = -ESPIPE;
652                 if (f.file->f_mode & FMODE_PWRITE)  
653                         ret = vfs_write(f.file, buf, count, &pos);
654                 fdput(f);
655         }
656 
657         return ret;
658 }
659 
660 SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf,
661                          size_t, count, loff_t, pos)
662 {
663         return ksys_pwrite64(fd, buf, count, pos);
664 }
665 
666 static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
667                 loff_t *ppos, int type, rwf_t flags)
668 {
669         struct kiocb kiocb;
670         ssize_t ret;
671 
672         init_sync_kiocb(&kiocb, filp);
673         ret = kiocb_set_rw_flags(&kiocb, flags);
674         if (ret)
675                 return ret;
676         kiocb.ki_pos = *ppos;
677 
678         if (type == READ)
679                 ret = call_read_iter(filp, &kiocb, iter);
680         else
681                 ret = call_write_iter(filp, &kiocb, iter);
682         BUG_ON(ret == -EIOCBQUEUED);
683         *ppos = kiocb.ki_pos;
684         return ret;
685 }
686 
687 /* Do it by hand, with file-ops */
688 static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
689                 loff_t *ppos, int type, rwf_t flags)
690 {
691         ssize_t ret = 0;
692 
693         if (flags & ~RWF_HIPRI)
694                 return -EOPNOTSUPP;
695 
696         while (iov_iter_count(iter)) {
697                 struct iovec iovec = iov_iter_iovec(iter);
698                 ssize_t nr;
699 
700                 if (type == READ) {
701                         nr = filp->f_op->read(filp, iovec.iov_base,
702                                               iovec.iov_len, ppos);
703                 } else {
704                         nr = filp->f_op->write(filp, iovec.iov_base,
705                                                iovec.iov_len, ppos);
706                 }
707 
708                 if (nr < 0) {
709                         if (!ret)
710                                 ret = nr;
711                         break;
712                 }
713                 ret += nr;
714                 if (nr != iovec.iov_len)
715                         break;
716                 iov_iter_advance(iter, nr);
717         }
718 
719         return ret;
720 }
721 
722 /**
723  * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace
724  *     into the kernel and check that it is valid.
725  *
726  * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE.
727  * @uvector: Pointer to the userspace array.
728  * @nr_segs: Number of elements in userspace array.
729  * @fast_segs: Number of elements in @fast_pointer.
730  * @fast_pointer: Pointer to (usually small on-stack) kernel array.
731  * @ret_pointer: (output parameter) Pointer to a variable that will point to
732  *     either @fast_pointer, a newly allocated kernel array, or NULL,
733  *     depending on which array was used.
734  *
735  * This function copies an array of &struct iovec of @nr_segs from
736  * userspace into the kernel and checks that each element is valid (e.g.
737  * it does not point to a kernel address or cause overflow by being too
738  * large, etc.).
739  *
740  * As an optimization, the caller may provide a pointer to a small
741  * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long
742  * (the size of this array, or 0 if unused, should be given in @fast_segs).
743  *
744  * @ret_pointer will always point to the array that was used, so the
745  * caller must take care not to call kfree() on it e.g. in case the
746  * @fast_pointer array was used and it was allocated on the stack.
747  *
748  * Return: The total number of bytes covered by the iovec array on success
749  *   or a negative error code on error.
750  */
751 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
752                               unsigned long nr_segs, unsigned long fast_segs,
753                               struct iovec *fast_pointer,
754                               struct iovec **ret_pointer)
755 {
756         unsigned long seg;
757         ssize_t ret;
758         struct iovec *iov = fast_pointer;
759 
760         /*
761          * SuS says "The readv() function *may* fail if the iovcnt argument
762          * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
763          * traditionally returned zero for zero segments, so...
764          */
765         if (nr_segs == 0) {
766                 ret = 0;
767                 goto out;
768         }
769 
770         /*
771          * First get the "struct iovec" from user memory and
772          * verify all the pointers
773          */
774         if (nr_segs > UIO_MAXIOV) {
775                 ret = -EINVAL;
776                 goto out;
777         }
778         if (nr_segs > fast_segs) {
779                 iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
780                 if (iov == NULL) {
781                         ret = -ENOMEM;
782                         goto out;
783                 }
784         }
785         if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
786                 ret = -EFAULT;
787                 goto out;
788         }
789 
790         /*
791          * According to the Single Unix Specification we should return EINVAL
792          * if an element length is < 0 when cast to ssize_t or if the
793          * total length would overflow the ssize_t return value of the
794          * system call.
795          *
796          * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
797          * overflow case.
798          */
799         ret = 0;
800         for (seg = 0; seg < nr_segs; seg++) {
801                 void __user *buf = iov[seg].iov_base;
802                 ssize_t len = (ssize_t)iov[seg].iov_len;
803 
804                 /* see if we we're about to use an invalid len or if
805                  * it's about to overflow ssize_t */
806                 if (len < 0) {
807                         ret = -EINVAL;
808                         goto out;
809                 }
810                 if (type >= 0
811                     && unlikely(!access_ok(buf, len))) {
812                         ret = -EFAULT;
813                         goto out;
814                 }
815                 if (len > MAX_RW_COUNT - ret) {
816                         len = MAX_RW_COUNT - ret;
817                         iov[seg].iov_len = len;
818                 }
819                 ret += len;
820         }
821 out:
822         *ret_pointer = iov;
823         return ret;
824 }
825 
826 #ifdef CONFIG_COMPAT
827 ssize_t compat_rw_copy_check_uvector(int type,
828                 const struct compat_iovec __user *uvector, unsigned long nr_segs,
829                 unsigned long fast_segs, struct iovec *fast_pointer,
830                 struct iovec **ret_pointer)
831 {
832         compat_ssize_t tot_len;
833         struct iovec *iov = *ret_pointer = fast_pointer;
834         ssize_t ret = 0;
835         int seg;
836 
837         /*
838          * SuS says "The readv() function *may* fail if the iovcnt argument
839          * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
840          * traditionally returned zero for zero segments, so...
841          */
842         if (nr_segs == 0)
843                 goto out;
844 
845         ret = -EINVAL;
846         if (nr_segs > UIO_MAXIOV)
847                 goto out;
848         if (nr_segs > fast_segs) {
849                 ret = -ENOMEM;
850                 iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
851                 if (iov == NULL)
852                         goto out;
853         }
854         *ret_pointer = iov;
855 
856         ret = -EFAULT;
857         if (!access_ok(uvector, nr_segs*sizeof(*uvector)))
858                 goto out;
859 
860         /*
861          * Single unix specification:
862          * We should -EINVAL if an element length is not >= 0 and fitting an
863          * ssize_t.
864          *
865          * In Linux, the total length is limited to MAX_RW_COUNT, there is
866          * no overflow possibility.
867          */
868         tot_len = 0;
869         ret = -EINVAL;
870         for (seg = 0; seg < nr_segs; seg++) {
871                 compat_uptr_t buf;
872                 compat_ssize_t len;
873 
874                 if (__get_user(len, &uvector->iov_len) ||
875                    __get_user(buf, &uvector->iov_base)) {
876                         ret = -EFAULT;
877                         goto out;
878                 }
879                 if (len < 0)    /* size_t not fitting in compat_ssize_t .. */
880                         goto out;
881                 if (type >= 0 &&
882                     !access_ok(compat_ptr(buf), len)) {
883                         ret = -EFAULT;
884                         goto out;
885                 }
886                 if (len > MAX_RW_COUNT - tot_len)
887                         len = MAX_RW_COUNT - tot_len;
888                 tot_len += len;
889                 iov->iov_base = compat_ptr(buf);
890                 iov->iov_len = (compat_size_t) len;
891                 uvector++;
892                 iov++;
893         }
894         ret = tot_len;
895 
896 out:
897         return ret;
898 }
899 #endif
900 
901 static ssize_t do_iter_read(struct file *file, struct iov_iter *iter,
902                 loff_t *pos, rwf_t flags)
903 {
904         size_t tot_len;
905         ssize_t ret = 0;
906 
907         if (!(file->f_mode & FMODE_READ))
908                 return -EBADF;
909         if (!(file->f_mode & FMODE_CAN_READ))
910                 return -EINVAL;
911 
912         tot_len = iov_iter_count(iter);
913         if (!tot_len)
914                 goto out;
915         ret = rw_verify_area(READ, file, pos, tot_len);
916         if (ret < 0)
917                 return ret;
918 
919         if (file->f_op->read_iter)
920                 ret = do_iter_readv_writev(file, iter, pos, READ, flags);
921         else
922                 ret = do_loop_readv_writev(file, iter, pos, READ, flags);
923 out:
924         if (ret >= 0)
925                 fsnotify_access(file);
926         return ret;
927 }
928 
929 ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
930                 rwf_t flags)
931 {
932         if (!file->f_op->read_iter)
933                 return -EINVAL;
934         return do_iter_read(file, iter, ppos, flags);
935 }
936 EXPORT_SYMBOL(vfs_iter_read);
937 
938 static ssize_t do_iter_write(struct file *file, struct iov_iter *iter,
939                 loff_t *pos, rwf_t flags)
940 {
941         size_t tot_len;
942         ssize_t ret = 0;
943 
944         if (!(file->f_mode & FMODE_WRITE))
945                 return -EBADF;
946         if (!(file->f_mode & FMODE_CAN_WRITE))
947                 return -EINVAL;
948 
949         tot_len = iov_iter_count(iter);
950         if (!tot_len)
951                 return 0;
952         ret = rw_verify_area(WRITE, file, pos, tot_len);
953         if (ret < 0)
954                 return ret;
955 
956         if (file->f_op->write_iter)
957                 ret = do_iter_readv_writev(file, iter, pos, WRITE, flags);
958         else
959                 ret = do_loop_readv_writev(file, iter, pos, WRITE, flags);
960         if (ret > 0)
961                 fsnotify_modify(file);
962         return ret;
963 }
964 
965 ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
966                 rwf_t flags)
967 {
968         if (!file->f_op->write_iter)
969                 return -EINVAL;
970         return do_iter_write(file, iter, ppos, flags);
971 }
972 EXPORT_SYMBOL(vfs_iter_write);
973 
974 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
975                   unsigned long vlen, loff_t *pos, rwf_t flags)
976 {
977         struct iovec iovstack[UIO_FASTIOV];
978         struct iovec *iov = iovstack;
979         struct iov_iter iter;
980         ssize_t ret;
981 
982         ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
983         if (ret >= 0) {
984                 ret = do_iter_read(file, &iter, pos, flags);
985                 kfree(iov);
986         }
987 
988         return ret;
989 }
990 
991 static ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
992                    unsigned long vlen, loff_t *pos, rwf_t flags)
993 {
994         struct iovec iovstack[UIO_FASTIOV];
995         struct iovec *iov = iovstack;
996         struct iov_iter iter;
997         ssize_t ret;
998 
999         ret = import_iovec(WRITE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
1000         if (ret >= 0) {
1001                 file_start_write(file);
1002                 ret = do_iter_write(file, &iter, pos, flags);
1003                 file_end_write(file);
1004                 kfree(iov);
1005         }
1006         return ret;
1007 }
1008 
1009 static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec,
1010                         unsigned long vlen, rwf_t flags)
1011 {
1012         struct fd f = fdget_pos(fd);
1013         ssize_t ret = -EBADF;
1014 
1015         if (f.file) {
1016                 loff_t pos = file_pos_read(f.file);
1017                 ret = vfs_readv(f.file, vec, vlen, &pos, flags);
1018                 if (ret >= 0)
1019                         file_pos_write(f.file, pos);
1020                 fdput_pos(f);
1021         }
1022 
1023         if (ret > 0)
1024                 add_rchar(current, ret);
1025         inc_syscr(current);
1026         return ret;
1027 }
1028 
1029 static ssize_t do_writev(unsigned long fd, const struct iovec __user *vec,
1030                          unsigned long vlen, rwf_t flags)
1031 {
1032         struct fd f = fdget_pos(fd);
1033         ssize_t ret = -EBADF;
1034 
1035         if (f.file) {
1036                 loff_t pos = file_pos_read(f.file);
1037                 ret = vfs_writev(f.file, vec, vlen, &pos, flags);
1038                 if (ret >= 0)
1039                         file_pos_write(f.file, pos);
1040                 fdput_pos(f);
1041         }
1042 
1043         if (ret > 0)
1044                 add_wchar(current, ret);
1045         inc_syscw(current);
1046         return ret;
1047 }
1048 
1049 static inline loff_t pos_from_hilo(unsigned long high, unsigned long low)
1050 {
1051 #define HALF_LONG_BITS (BITS_PER_LONG / 2)
1052         return (((loff_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low;
1053 }
1054 
1055 static ssize_t do_preadv(unsigned long fd, const struct iovec __user *vec,
1056                          unsigned long vlen, loff_t pos, rwf_t flags)
1057 {
1058         struct fd f;
1059         ssize_t ret = -EBADF;
1060 
1061         if (pos < 0)
1062                 return -EINVAL;
1063 
1064         f = fdget(fd);
1065         if (f.file) {
1066                 ret = -ESPIPE;
1067                 if (f.file->f_mode & FMODE_PREAD)
1068                         ret = vfs_readv(f.file, vec, vlen, &pos, flags);
1069                 fdput(f);
1070         }
1071 
1072         if (ret > 0)
1073                 add_rchar(current, ret);
1074         inc_syscr(current);
1075         return ret;
1076 }
1077 
1078 static ssize_t do_pwritev(unsigned long fd, const struct iovec __user *vec,
1079                           unsigned long vlen, loff_t pos, rwf_t flags)
1080 {
1081         struct fd f;
1082         ssize_t ret = -EBADF;
1083 
1084         if (pos < 0)
1085                 return -EINVAL;
1086 
1087         f = fdget(fd);
1088         if (f.file) {
1089                 ret = -ESPIPE;
1090                 if (f.file->f_mode & FMODE_PWRITE)
1091                         ret = vfs_writev(f.file, vec, vlen, &pos, flags);
1092                 fdput(f);
1093         }
1094 
1095         if (ret > 0)
1096                 add_wchar(current, ret);
1097         inc_syscw(current);
1098         return ret;
1099 }
1100 
1101 SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
1102                 unsigned long, vlen)
1103 {
1104         return do_readv(fd, vec, vlen, 0);
1105 }
1106 
1107 SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
1108                 unsigned long, vlen)
1109 {
1110         return do_writev(fd, vec, vlen, 0);
1111 }
1112 
1113 SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
1114                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
1115 {
1116         loff_t pos = pos_from_hilo(pos_h, pos_l);
1117 
1118         return do_preadv(fd, vec, vlen, pos, 0);
1119 }
1120 
1121 SYSCALL_DEFINE6(preadv2, unsigned long, fd, const struct iovec __user *, vec,
1122                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
1123                 rwf_t, flags)
1124 {
1125         loff_t pos = pos_from_hilo(pos_h, pos_l);
1126 
1127         if (pos == -1)
1128                 return do_readv(fd, vec, vlen, flags);
1129 
1130         return do_preadv(fd, vec, vlen, pos, flags);
1131 }
1132 
1133 SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
1134                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
1135 {
1136         loff_t pos = pos_from_hilo(pos_h, pos_l);
1137 
1138         return do_pwritev(fd, vec, vlen, pos, 0);
1139 }
1140 
1141 SYSCALL_DEFINE6(pwritev2, unsigned long, fd, const struct iovec __user *, vec,
1142                 unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
1143                 rwf_t, flags)
1144 {
1145         loff_t pos = pos_from_hilo(pos_h, pos_l);
1146 
1147         if (pos == -1)
1148                 return do_writev(fd, vec, vlen, flags);
1149 
1150         return do_pwritev(fd, vec, vlen, pos, flags);
1151 }
1152 
1153 #ifdef CONFIG_COMPAT
1154 static size_t compat_readv(struct file *file,
1155                            const struct compat_iovec __user *vec,
1156                            unsigned long vlen, loff_t *pos, rwf_t flags)
1157 {
1158         struct iovec iovstack[UIO_FASTIOV];
1159         struct iovec *iov = iovstack;
1160         struct iov_iter iter;
1161         ssize_t ret;
1162 
1163         ret = compat_import_iovec(READ, vec, vlen, UIO_FASTIOV, &iov, &iter);
1164         if (ret >= 0) {
1165                 ret = do_iter_read(file, &iter, pos, flags);
1166                 kfree(iov);
1167         }
1168         if (ret > 0)
1169                 add_rchar(current, ret);
1170         inc_syscr(current);
1171         return ret;
1172 }
1173 
1174 static size_t do_compat_readv(compat_ulong_t fd,
1175                                  const struct compat_iovec __user *vec,
1176                                  compat_ulong_t vlen, rwf_t flags)
1177 {
1178         struct fd f = fdget_pos(fd);
1179         ssize_t ret;
1180         loff_t pos;
1181 
1182         if (!f.file)
1183                 return -EBADF;
1184         pos = f.file->f_pos;
1185         ret = compat_readv(f.file, vec, vlen, &pos, flags);
1186         if (ret >= 0)
1187                 f.file->f_pos = pos;
1188         fdput_pos(f);
1189         return ret;
1190 
1191 }
1192 
1193 COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
1194                 const struct compat_iovec __user *,vec,
1195                 compat_ulong_t, vlen)
1196 {
1197         return do_compat_readv(fd, vec, vlen, 0);
1198 }
1199 
1200 static long do_compat_preadv64(unsigned long fd,
1201                                   const struct compat_iovec __user *vec,
1202                                   unsigned long vlen, loff_t pos, rwf_t flags)
1203 {
1204         struct fd f;
1205         ssize_t ret;
1206 
1207         if (pos < 0)
1208                 return -EINVAL;
1209         f = fdget(fd);
1210         if (!f.file)
1211                 return -EBADF;
1212         ret = -ESPIPE;
1213         if (f.file->f_mode & FMODE_PREAD)
1214                 ret = compat_readv(f.file, vec, vlen, &pos, flags);
1215         fdput(f);
1216         return ret;
1217 }
1218 
1219 #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64
1220 COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd,
1221                 const struct compat_iovec __user *,vec,
1222                 unsigned long, vlen, loff_t, pos)
1223 {
1224         return do_compat_preadv64(fd, vec, vlen, pos, 0);
1225 }
1226 #endif
1227 
1228 COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd,
1229                 const struct compat_iovec __user *,vec,
1230                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
1231 {
1232         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1233 
1234         return do_compat_preadv64(fd, vec, vlen, pos, 0);
1235 }
1236 
1237 #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64V2
1238 COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
1239                 const struct compat_iovec __user *,vec,
1240                 unsigned long, vlen, loff_t, pos, rwf_t, flags)
1241 {
1242         if (pos == -1)
1243                 return do_compat_readv(fd, vec, vlen, flags);
1244 
1245         return do_compat_preadv64(fd, vec, vlen, pos, flags);
1246 }
1247 #endif
1248 
1249 COMPAT_SYSCALL_DEFINE6(preadv2, compat_ulong_t, fd,
1250                 const struct compat_iovec __user *,vec,
1251                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high,
1252                 rwf_t, flags)
1253 {
1254         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1255 
1256         if (pos == -1)
1257                 return do_compat_readv(fd, vec, vlen, flags);
1258 
1259         return do_compat_preadv64(fd, vec, vlen, pos, flags);
1260 }
1261 
1262 static size_t compat_writev(struct file *file,
1263                             const struct compat_iovec __user *vec,
1264                             unsigned long vlen, loff_t *pos, rwf_t flags)
1265 {
1266         struct iovec iovstack[UIO_FASTIOV];
1267         struct iovec *iov = iovstack;
1268         struct iov_iter iter;
1269         ssize_t ret;
1270 
1271         ret = compat_import_iovec(WRITE, vec, vlen, UIO_FASTIOV, &iov, &iter);
1272         if (ret >= 0) {
1273                 file_start_write(file);
1274                 ret = do_iter_write(file, &iter, pos, flags);
1275                 file_end_write(file);
1276                 kfree(iov);
1277         }
1278         if (ret > 0)
1279                 add_wchar(current, ret);
1280         inc_syscw(current);
1281         return ret;
1282 }
1283 
1284 static size_t do_compat_writev(compat_ulong_t fd,
1285                                   const struct compat_iovec __user* vec,
1286                                   compat_ulong_t vlen, rwf_t flags)
1287 {
1288         struct fd f = fdget_pos(fd);
1289         ssize_t ret;
1290         loff_t pos;
1291 
1292         if (!f.file)
1293                 return -EBADF;
1294         pos = f.file->f_pos;
1295         ret = compat_writev(f.file, vec, vlen, &pos, flags);
1296         if (ret >= 0)
1297                 f.file->f_pos = pos;
1298         fdput_pos(f);
1299         return ret;
1300 }
1301 
1302 COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd,
1303                 const struct compat_iovec __user *, vec,
1304                 compat_ulong_t, vlen)
1305 {
1306         return do_compat_writev(fd, vec, vlen, 0);
1307 }
1308 
1309 static long do_compat_pwritev64(unsigned long fd,
1310                                    const struct compat_iovec __user *vec,
1311                                    unsigned long vlen, loff_t pos, rwf_t flags)
1312 {
1313         struct fd f;
1314         ssize_t ret;
1315 
1316         if (pos < 0)
1317                 return -EINVAL;
1318         f = fdget(fd);
1319         if (!f.file)
1320                 return -EBADF;
1321         ret = -ESPIPE;
1322         if (f.file->f_mode & FMODE_PWRITE)
1323                 ret = compat_writev(f.file, vec, vlen, &pos, flags);
1324         fdput(f);
1325         return ret;
1326 }
1327 
1328 #ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64
1329 COMPAT_SYSCALL_DEFINE4(pwritev64, unsigned long, fd,
1330                 const struct compat_iovec __user *,vec,
1331                 unsigned long, vlen, loff_t, pos)
1332 {
1333         return do_compat_pwritev64(fd, vec, vlen, pos, 0);
1334 }
1335 #endif
1336 
1337 COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
1338                 const struct compat_iovec __user *,vec,
1339                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
1340 {
1341         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1342 
1343         return do_compat_pwritev64(fd, vec, vlen, pos, 0);
1344 }
1345 
1346 #ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
1347 COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
1348                 const struct compat_iovec __user *,vec,
1349                 unsigned long, vlen, loff_t, pos, rwf_t, flags)
1350 {
1351         if (pos == -1)
1352                 return do_compat_writev(fd, vec, vlen, flags);
1353 
1354         return do_compat_pwritev64(fd, vec, vlen, pos, flags);
1355 }
1356 #endif
1357 
1358 COMPAT_SYSCALL_DEFINE6(pwritev2, compat_ulong_t, fd,
1359                 const struct compat_iovec __user *,vec,
1360                 compat_ulong_t, vlen, u32, pos_low, u32, pos_high, rwf_t, flags)
1361 {
1362         loff_t pos = ((loff_t)pos_high << 32) | pos_low;
1363 
1364         if (pos == -1)
1365                 return do_compat_writev(fd, vec, vlen, flags);
1366 
1367         return do_compat_pwritev64(fd, vec, vlen, pos, flags);
1368 }
1369 
1370 #endif
1371 
1372 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
1373                            size_t count, loff_t max)
1374 {
1375         struct fd in, out;
1376         struct inode *in_inode, *out_inode;
1377         loff_t pos;
1378         loff_t out_pos;
1379         ssize_t retval;
1380         int fl;
1381 
1382         /*
1383          * Get input file, and verify that it is ok..
1384          */
1385         retval = -EBADF;
1386         in = fdget(in_fd);
1387         if (!in.file)
1388                 goto out;
1389         if (!(in.file->f_mode & FMODE_READ))
1390                 goto fput_in;
1391         retval = -ESPIPE;
1392         if (!ppos) {
1393                 pos = in.file->f_pos;
1394         } else {
1395                 pos = *ppos;
1396                 if (!(in.file->f_mode & FMODE_PREAD))
1397                         goto fput_in;
1398         }
1399         retval = rw_verify_area(READ, in.file, &pos, count);
1400         if (retval < 0)
1401                 goto fput_in;
1402         if (count > MAX_RW_COUNT)
1403                 count =  MAX_RW_COUNT;
1404 
1405         /*
1406          * Get output file, and verify that it is ok..
1407          */
1408         retval = -EBADF;
1409         out = fdget(out_fd);
1410         if (!out.file)
1411                 goto fput_in;
1412         if (!(out.file->f_mode & FMODE_WRITE))
1413                 goto fput_out;
1414         in_inode = file_inode(in.file);
1415         out_inode = file_inode(out.file);
1416         out_pos = out.file->f_pos;
1417         retval = rw_verify_area(WRITE, out.file, &out_pos, count);
1418         if (retval < 0)
1419                 goto fput_out;
1420 
1421         if (!max)
1422                 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
1423 
1424         if (unlikely(pos + count > max)) {
1425                 retval = -EOVERFLOW;
1426                 if (pos >= max)
1427                         goto fput_out;
1428                 count = max - pos;
1429         }
1430 
1431         fl = 0;
1432 #if 0
1433         /*
1434          * We need to debate whether we can enable this or not. The
1435          * man page documents EAGAIN return for the output at least,
1436          * and the application is arguably buggy if it doesn't expect
1437          * EAGAIN on a non-blocking file descriptor.
1438          */
1439         if (in.file->f_flags & O_NONBLOCK)
1440                 fl = SPLICE_F_NONBLOCK;
1441 #endif
1442         file_start_write(out.file);
1443         retval = do_splice_direct(in.file, &pos, out.file, &out_pos, count, fl);
1444         file_end_write(out.file);
1445 
1446         if (retval > 0) {
1447                 add_rchar(current, retval);
1448                 add_wchar(current, retval);
1449                 fsnotify_access(in.file);
1450                 fsnotify_modify(out.file);
1451                 out.file->f_pos = out_pos;
1452                 if (ppos)
1453                         *ppos = pos;
1454                 else
1455                         in.file->f_pos = pos;
1456         }
1457 
1458         inc_syscr(current);
1459         inc_syscw(current);
1460         if (pos > max)
1461                 retval = -EOVERFLOW;
1462 
1463 fput_out:
1464         fdput(out);
1465 fput_in:
1466         fdput(in);
1467 out:
1468         return retval;
1469 }
1470 
1471 SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, off_t __user *, offset, size_t, count)
1472 {
1473         loff_t pos;
1474         off_t off;
1475         ssize_t ret;
1476 
1477         if (offset) {
1478                 if (unlikely(get_user(off, offset)))
1479                         return -EFAULT;
1480                 pos = off;
1481                 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
1482                 if (unlikely(put_user(pos, offset)))
1483                         return -EFAULT;
1484                 return ret;
1485         }
1486 
1487         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1488 }
1489 
1490 SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, loff_t __user *, offset, size_t, count)
1491 {
1492         loff_t pos;
1493         ssize_t ret;
1494 
1495         if (offset) {
1496                 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
1497                         return -EFAULT;
1498                 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
1499                 if (unlikely(put_user(pos, offset)))
1500                         return -EFAULT;
1501                 return ret;
1502         }
1503 
1504         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1505 }
1506 
1507 #ifdef CONFIG_COMPAT
1508 COMPAT_SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd,
1509                 compat_off_t __user *, offset, compat_size_t, count)
1510 {
1511         loff_t pos;
1512         off_t off;
1513         ssize_t ret;
1514 
1515         if (offset) {
1516                 if (unlikely(get_user(off, offset)))
1517                         return -EFAULT;
1518                 pos = off;
1519                 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
1520                 if (unlikely(put_user(pos, offset)))
1521                         return -EFAULT;
1522                 return ret;
1523         }
1524 
1525         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1526 }
1527 
1528 COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
1529                 compat_loff_t __user *, offset, compat_size_t, count)
1530 {
1531         loff_t pos;
1532         ssize_t ret;
1533 
1534         if (offset) {
1535                 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
1536                         return -EFAULT;
1537                 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
1538                 if (unlikely(put_user(pos, offset)))
1539                         return -EFAULT;
1540                 return ret;
1541         }
1542 
1543         return do_sendfile(out_fd, in_fd, NULL, count, 0);
1544 }
1545 #endif
1546 
1547 /*
1548  * copy_file_range() differs from regular file read and write in that it
1549  * specifically allows return partial success.  When it does so is up to
1550  * the copy_file_range method.
1551  */
1552 ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
1553                             struct file *file_out, loff_t pos_out,
1554                             size_t len, unsigned int flags)
1555 {
1556         struct inode *inode_in = file_inode(file_in);
1557         struct inode *inode_out = file_inode(file_out);
1558         ssize_t ret;
1559 
1560         if (flags != 0)
1561                 return -EINVAL;
1562 
1563         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
1564                 return -EISDIR;
1565         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
1566                 return -EINVAL;
1567 
1568         ret = rw_verify_area(READ, file_in, &pos_in, len);
1569         if (unlikely(ret))
1570                 return ret;
1571 
1572         ret = rw_verify_area(WRITE, file_out, &pos_out, len);
1573         if (unlikely(ret))
1574                 return ret;
1575 
1576         if (!(file_in->f_mode & FMODE_READ) ||
1577             !(file_out->f_mode & FMODE_WRITE) ||
1578             (file_out->f_flags & O_APPEND))
1579                 return -EBADF;
1580 
1581         /* this could be relaxed once a method supports cross-fs copies */
1582         if (inode_in->i_sb != inode_out->i_sb)
1583                 return -EXDEV;
1584 
1585         if (len == 0)
1586                 return 0;
1587 
1588         file_start_write(file_out);
1589 
1590         /*
1591          * Try cloning first, this is supported by more file systems, and
1592          * more efficient if both clone and copy are supported (e.g. NFS).
1593          */
1594         if (file_in->f_op->remap_file_range) {
1595                 loff_t cloned;
1596 
1597                 cloned = file_in->f_op->remap_file_range(file_in, pos_in,
1598                                 file_out, pos_out,
1599                                 min_t(loff_t, MAX_RW_COUNT, len),
1600                                 REMAP_FILE_CAN_SHORTEN);
1601                 if (cloned > 0) {
1602                         ret = cloned;
1603                         goto done;
1604                 }
1605         }
1606 
1607         if (file_out->f_op->copy_file_range) {
1608                 ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
1609                                                       pos_out, len, flags);
1610                 if (ret != -EOPNOTSUPP)
1611                         goto done;
1612         }
1613 
1614         ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
1615                         len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
1616 
1617 done:
1618         if (ret > 0) {
1619                 fsnotify_access(file_in);
1620                 add_rchar(current, ret);
1621                 fsnotify_modify(file_out);
1622                 add_wchar(current, ret);
1623         }
1624 
1625         inc_syscr(current);
1626         inc_syscw(current);
1627 
1628         file_end_write(file_out);
1629 
1630         return ret;
1631 }
1632 EXPORT_SYMBOL(vfs_copy_file_range);
1633 
1634 SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in,
1635                 int, fd_out, loff_t __user *, off_out,
1636                 size_t, len, unsigned int, flags)
1637 {
1638         loff_t pos_in;
1639         loff_t pos_out;
1640         struct fd f_in;
1641         struct fd f_out;
1642         ssize_t ret = -EBADF;
1643 
1644         f_in = fdget(fd_in);
1645         if (!f_in.file)
1646                 goto out2;
1647 
1648         f_out = fdget(fd_out);
1649         if (!f_out.file)
1650                 goto out1;
1651 
1652         ret = -EFAULT;
1653         if (off_in) {
1654                 if (copy_from_user(&pos_in, off_in, sizeof(loff_t)))
1655                         goto out;
1656         } else {
1657                 pos_in = f_in.file->f_pos;
1658         }
1659 
1660         if (off_out) {
1661                 if (copy_from_user(&pos_out, off_out, sizeof(loff_t)))
1662                         goto out;
1663         } else {
1664                 pos_out = f_out.file->f_pos;
1665         }
1666 
1667         ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len,
1668                                   flags);
1669         if (ret > 0) {
1670                 pos_in += ret;
1671                 pos_out += ret;
1672 
1673                 if (off_in) {
1674                         if (copy_to_user(off_in, &pos_in, sizeof(loff_t)))
1675                                 ret = -EFAULT;
1676                 } else {
1677                         f_in.file->f_pos = pos_in;
1678                 }
1679 
1680                 if (off_out) {
1681                         if (copy_to_user(off_out, &pos_out, sizeof(loff_t)))
1682                                 ret = -EFAULT;
1683                 } else {
1684                         f_out.file->f_pos = pos_out;
1685                 }
1686         }
1687 
1688 out:
1689         fdput(f_out);
1690 out1:
1691         fdput(f_in);
1692 out2:
1693         return ret;
1694 }
1695 
1696 static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
1697                              bool write)
1698 {
1699         struct inode *inode = file_inode(file);
1700 
1701         if (unlikely(pos < 0 || len < 0))
1702                 return -EINVAL;
1703 
1704          if (unlikely((loff_t) (pos + len) < 0))
1705                 return -EINVAL;
1706 
1707         if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
1708                 loff_t end = len ? pos + len - 1 : OFFSET_MAX;
1709                 int retval;
1710 
1711                 retval = locks_mandatory_area(inode, file, pos, end,
1712                                 write ? F_WRLCK : F_RDLCK);
1713                 if (retval < 0)
1714                         return retval;
1715         }
1716 
1717         return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
1718 }
1719 /*
1720  * Ensure that we don't remap a partial EOF block in the middle of something
1721  * else.  Assume that the offsets have already been checked for block
1722  * alignment.
1723  *
1724  * For deduplication we always scale down to the previous block because we
1725  * can't meaningfully compare post-EOF contents.
1726  *
1727  * For clone we only link a partial EOF block above the destination file's EOF.
1728  *
1729  * Shorten the request if possible.
1730  */
1731 static int generic_remap_check_len(struct inode *inode_in,
1732                                    struct inode *inode_out,
1733                                    loff_t pos_out,
1734                                    loff_t *len,
1735                                    unsigned int remap_flags)
1736 {
1737         u64 blkmask = i_blocksize(inode_in) - 1;
1738         loff_t new_len = *len;
1739 
1740         if ((*len & blkmask) == 0)
1741                 return 0;
1742 
1743         if ((remap_flags & REMAP_FILE_DEDUP) ||
1744             pos_out + *len < i_size_read(inode_out))
1745                 new_len &= ~blkmask;
1746 
1747         if (new_len == *len)
1748                 return 0;
1749 
1750         if (remap_flags & REMAP_FILE_CAN_SHORTEN) {
1751                 *len = new_len;
1752                 return 0;
1753         }
1754 
1755         return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
1756 }
1757 
1758 /*
1759  * Read a page's worth of file data into the page cache.  Return the page
1760  * locked.
1761  */
1762 static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
1763 {
1764         struct page *page;
1765 
1766         page = read_mapping_page(inode->i_mapping, offset >> PAGE_SHIFT, NULL);
1767         if (IS_ERR(page))
1768                 return page;
1769         if (!PageUptodate(page)) {
1770                 put_page(page);
1771                 return ERR_PTR(-EIO);
1772         }
1773         lock_page(page);
1774         return page;
1775 }
1776 
1777 /*
1778  * Compare extents of two files to see if they are the same.
1779  * Caller must have locked both inodes to prevent write races.
1780  */
1781 static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
1782                                          struct inode *dest, loff_t destoff,
1783                                          loff_t len, bool *is_same)
1784 {
1785         loff_t src_poff;
1786         loff_t dest_poff;
1787         void *src_addr;
1788         void *dest_addr;
1789         struct page *src_page;
1790         struct page *dest_page;
1791         loff_t cmp_len;
1792         bool same;
1793         int error;
1794 
1795         error = -EINVAL;
1796         same = true;
1797         while (len) {
1798                 src_poff = srcoff & (PAGE_SIZE - 1);
1799                 dest_poff = destoff & (PAGE_SIZE - 1);
1800                 cmp_len = min(PAGE_SIZE - src_poff,
1801                               PAGE_SIZE - dest_poff);
1802                 cmp_len = min(cmp_len, len);
1803                 if (cmp_len <= 0)
1804                         goto out_error;
1805 
1806                 src_page = vfs_dedupe_get_page(src, srcoff);
1807                 if (IS_ERR(src_page)) {
1808                         error = PTR_ERR(src_page);
1809                         goto out_error;
1810                 }
1811                 dest_page = vfs_dedupe_get_page(dest, destoff);
1812                 if (IS_ERR(dest_page)) {
1813                         error = PTR_ERR(dest_page);
1814                         unlock_page(src_page);
1815                         put_page(src_page);
1816                         goto out_error;
1817                 }
1818                 src_addr = kmap_atomic(src_page);
1819                 dest_addr = kmap_atomic(dest_page);
1820 
1821                 flush_dcache_page(src_page);
1822                 flush_dcache_page(dest_page);
1823 
1824                 if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
1825                         same = false;
1826 
1827                 kunmap_atomic(dest_addr);
1828                 kunmap_atomic(src_addr);
1829                 unlock_page(dest_page);
1830                 unlock_page(src_page);
1831                 put_page(dest_page);
1832                 put_page(src_page);
1833 
1834                 if (!same)
1835                         break;
1836 
1837                 srcoff += cmp_len;
1838                 destoff += cmp_len;
1839                 len -= cmp_len;
1840         }
1841 
1842         *is_same = same;
1843         return 0;
1844 
1845 out_error:
1846         return error;
1847 }
1848 
1849 /*
1850  * Check that the two inodes are eligible for cloning, the ranges make
1851  * sense, and then flush all dirty data.  Caller must ensure that the
1852  * inodes have been locked against any other modifications.
1853  *
1854  * If there's an error, then the usual negative error code is returned.
1855  * Otherwise returns 0 with *len set to the request length.
1856  */
1857 int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
1858                                   struct file *file_out, loff_t pos_out,
1859                                   loff_t *len, unsigned int remap_flags)
1860 {
1861         struct inode *inode_in = file_inode(file_in);
1862         struct inode *inode_out = file_inode(file_out);
1863         bool same_inode = (inode_in == inode_out);
1864         int ret;
1865 
1866         /* Don't touch certain kinds of inodes */
1867         if (IS_IMMUTABLE(inode_out))
1868                 return -EPERM;
1869 
1870         if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
1871                 return -ETXTBSY;
1872 
1873         /* Don't reflink dirs, pipes, sockets... */
1874         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
1875                 return -EISDIR;
1876         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
1877                 return -EINVAL;
1878 
1879         /* Zero length dedupe exits immediately; reflink goes to EOF. */
1880         if (*len == 0) {
1881                 loff_t isize = i_size_read(inode_in);
1882 
1883                 if ((remap_flags & REMAP_FILE_DEDUP) || pos_in == isize)
1884                         return 0;
1885                 if (pos_in > isize)
1886                         return -EINVAL;
1887                 *len = isize - pos_in;
1888                 if (*len == 0)
1889                         return 0;
1890         }
1891 
1892         /* Check that we don't violate system file offset limits. */
1893         ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
1894                         remap_flags);
1895         if (ret)
1896                 return ret;
1897 
1898         /* Wait for the completion of any pending IOs on both files */
1899         inode_dio_wait(inode_in);
1900         if (!same_inode)
1901                 inode_dio_wait(inode_out);
1902 
1903         ret = filemap_write_and_wait_range(inode_in->i_mapping,
1904                         pos_in, pos_in + *len - 1);
1905         if (ret)
1906                 return ret;
1907 
1908         ret = filemap_write_and_wait_range(inode_out->i_mapping,
1909                         pos_out, pos_out + *len - 1);
1910         if (ret)
1911                 return ret;
1912 
1913         /*
1914          * Check that the extents are the same.
1915          */
1916         if (remap_flags & REMAP_FILE_DEDUP) {
1917                 bool            is_same = false;
1918 
1919                 ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
1920                                 inode_out, pos_out, *len, &is_same);
1921                 if (ret)
1922                         return ret;
1923                 if (!is_same)
1924                         return -EBADE;
1925         }
1926 
1927         ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
1928                         remap_flags);
1929         if (ret)
1930                 return ret;
1931 
1932         /* If can't alter the file contents, we're done. */
1933         if (!(remap_flags & REMAP_FILE_DEDUP)) {
1934                 /* Update the timestamps, since we can alter file contents. */
1935                 if (!(file_out->f_mode & FMODE_NOCMTIME)) {
1936                         ret = file_update_time(file_out);
1937                         if (ret)
1938                                 return ret;
1939                 }
1940 
1941                 /*
1942                  * Clear the security bits if the process is not being run by
1943                  * root.  This keeps people from modifying setuid and setgid
1944                  * binaries.
1945                  */
1946                 ret = file_remove_privs(file_out);
1947                 if (ret)
1948                         return ret;
1949         }
1950 
1951         return 0;
1952 }
1953 EXPORT_SYMBOL(generic_remap_file_range_prep);
1954 
1955 loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
1956                            struct file *file_out, loff_t pos_out,
1957                            loff_t len, unsigned int remap_flags)
1958 {
1959         struct inode *inode_in = file_inode(file_in);
1960         struct inode *inode_out = file_inode(file_out);
1961         loff_t ret;
1962 
1963         WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
1964 
1965         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
1966                 return -EISDIR;
1967         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
1968                 return -EINVAL;
1969 
1970         /*
1971          * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on
1972          * the same mount. Practically, they only need to be on the same file
1973          * system.
1974          */
1975         if (inode_in->i_sb != inode_out->i_sb)
1976                 return -EXDEV;
1977 
1978         if (!(file_in->f_mode & FMODE_READ) ||
1979             !(file_out->f_mode & FMODE_WRITE) ||
1980             (file_out->f_flags & O_APPEND))
1981                 return -EBADF;
1982 
1983         if (!file_in->f_op->remap_file_range)
1984                 return -EOPNOTSUPP;
1985 
1986         ret = remap_verify_area(file_in, pos_in, len, false);
1987         if (ret)
1988                 return ret;
1989 
1990         ret = remap_verify_area(file_out, pos_out, len, true);
1991         if (ret)
1992                 return ret;
1993 
1994         ret = file_in->f_op->remap_file_range(file_in, pos_in,
1995                         file_out, pos_out, len, remap_flags);
1996         if (ret < 0)
1997                 return ret;
1998 
1999         fsnotify_access(file_in);
2000         fsnotify_modify(file_out);
2001         return ret;
2002 }
2003 EXPORT_SYMBOL(do_clone_file_range);
2004 
2005 loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
2006                             struct file *file_out, loff_t pos_out,
2007                             loff_t len, unsigned int remap_flags)
2008 {
2009         loff_t ret;
2010 
2011         file_start_write(file_out);
2012         ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
2013                                   remap_flags);
2014         file_end_write(file_out);
2015 
2016         return ret;
2017 }
2018 EXPORT_SYMBOL(vfs_clone_file_range);
2019 
2020 /* Check whether we are allowed to dedupe the destination file */
2021 static bool allow_file_dedupe(struct file *file)
2022 {
2023         if (capable(CAP_SYS_ADMIN))
2024                 return true;
2025         if (file->f_mode & FMODE_WRITE)
2026                 return true;
2027         if (uid_eq(current_fsuid(), file_inode(file)->i_uid))
2028                 return true;
2029         if (!inode_permission(file_inode(file), MAY_WRITE))
2030                 return true;
2031         return false;
2032 }
2033 
2034 loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
2035                                  struct file *dst_file, loff_t dst_pos,
2036                                  loff_t len, unsigned int remap_flags)
2037 {
2038         loff_t ret;
2039 
2040         WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP |
2041                                      REMAP_FILE_CAN_SHORTEN));
2042 
2043         ret = mnt_want_write_file(dst_file);
2044         if (ret)
2045                 return ret;
2046 
2047         ret = remap_verify_area(dst_file, dst_pos, len, true);
2048         if (ret < 0)
2049                 goto out_drop_write;
2050 
2051         ret = -EPERM;
2052         if (!allow_file_dedupe(dst_file))
2053                 goto out_drop_write;
2054 
2055         ret = -EXDEV;
2056         if (src_file->f_path.mnt != dst_file->f_path.mnt)
2057                 goto out_drop_write;
2058 
2059         ret = -EISDIR;
2060         if (S_ISDIR(file_inode(dst_file)->i_mode))
2061                 goto out_drop_write;
2062 
2063         ret = -EINVAL;
2064         if (!dst_file->f_op->remap_file_range)
2065                 goto out_drop_write;
2066 
2067         if (len == 0) {
2068                 ret = 0;
2069                 goto out_drop_write;
2070         }
2071 
2072         ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
2073                         dst_pos, len, remap_flags | REMAP_FILE_DEDUP);
2074 out_drop_write:
2075         mnt_drop_write_file(dst_file);
2076 
2077         return ret;
2078 }
2079 EXPORT_SYMBOL(vfs_dedupe_file_range_one);
2080 
2081 int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
2082 {
2083         struct file_dedupe_range_info *info;
2084         struct inode *src = file_inode(file);
2085         u64 off;
2086         u64 len;
2087         int i;
2088         int ret;
2089         u16 count = same->dest_count;
2090         loff_t deduped;
2091 
2092         if (!(file->f_mode & FMODE_READ))
2093                 return -EINVAL;
2094 
2095         if (same->reserved1 || same->reserved2)
2096                 return -EINVAL;
2097 
2098         off = same->src_offset;
2099         len = same->src_length;
2100 
2101         if (S_ISDIR(src->i_mode))
2102                 return -EISDIR;
2103 
2104         if (!S_ISREG(src->i_mode))
2105                 return -EINVAL;
2106 
2107         if (!file->f_op->remap_file_range)
2108                 return -EOPNOTSUPP;
2109 
2110         ret = remap_verify_area(file, off, len, false);
2111         if (ret < 0)
2112                 return ret;
2113         ret = 0;
2114 
2115         if (off + len > i_size_read(src))
2116                 return -EINVAL;
2117 
2118         /* Arbitrary 1G limit on a single dedupe request, can be raised. */
2119         len = min_t(u64, len, 1 << 30);
2120 
2121         /* pre-format output fields to sane values */
2122         for (i = 0; i < count; i++) {
2123                 same->info[i].bytes_deduped = 0ULL;
2124                 same->info[i].status = FILE_DEDUPE_RANGE_SAME;
2125         }
2126 
2127         for (i = 0, info = same->info; i < count; i++, info++) {
2128                 struct fd dst_fd = fdget(info->dest_fd);
2129                 struct file *dst_file = dst_fd.file;
2130 
2131                 if (!dst_file) {
2132                         info->status = -EBADF;
2133                         goto next_loop;
2134                 }
2135 
2136                 if (info->reserved) {
2137                         info->status = -EINVAL;
2138                         goto next_fdput;
2139                 }
2140 
2141                 deduped = vfs_dedupe_file_range_one(file, off, dst_file,
2142                                                     info->dest_offset, len,
2143                                                     REMAP_FILE_CAN_SHORTEN);
2144                 if (deduped == -EBADE)
2145                         info->status = FILE_DEDUPE_RANGE_DIFFERS;
2146                 else if (deduped < 0)
2147                         info->status = deduped;
2148                 else
2149                         info->bytes_deduped = len;
2150 
2151 next_fdput:
2152                 fdput(dst_fd);
2153 next_loop:
2154                 if (fatal_signal_pending(current))
2155                         break;
2156         }
2157         return ret;
2158 }
2159 EXPORT_SYMBOL(vfs_dedupe_file_range);
2160 

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