fs: move struct kiocb to fs.h
[cascardo/linux.git] / fs / ext4 / file.c
1 /*
2  *  linux/fs/ext4/file.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card (card@masi.ibp.fr)
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  *  from
10  *
11  *  linux/fs/minix/file.c
12  *
13  *  Copyright (C) 1991, 1992  Linus Torvalds
14  *
15  *  ext4 fs regular file handling primitives
16  *
17  *  64-bit file support on 64-bit platforms by Jakub Jelinek
18  *      (jj@sunsite.ms.mff.cuni.cz)
19  */
20
21 #include <linux/time.h>
22 #include <linux/fs.h>
23 #include <linux/jbd2.h>
24 #include <linux/mount.h>
25 #include <linux/path.h>
26 #include <linux/quotaops.h>
27 #include <linux/pagevec.h>
28 #include <linux/uio.h>
29 #include "ext4.h"
30 #include "ext4_jbd2.h"
31 #include "xattr.h"
32 #include "acl.h"
33
34 /*
35  * Called when an inode is released. Note that this is different
36  * from ext4_file_open: open gets called at every open, but release
37  * gets called only when /all/ the files are closed.
38  */
39 static int ext4_release_file(struct inode *inode, struct file *filp)
40 {
41         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
42                 ext4_alloc_da_blocks(inode);
43                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
44         }
45         /* if we are the last writer on the inode, drop the block reservation */
46         if ((filp->f_mode & FMODE_WRITE) &&
47                         (atomic_read(&inode->i_writecount) == 1) &&
48                         !EXT4_I(inode)->i_reserved_data_blocks)
49         {
50                 down_write(&EXT4_I(inode)->i_data_sem);
51                 ext4_discard_preallocations(inode);
52                 up_write(&EXT4_I(inode)->i_data_sem);
53         }
54         if (is_dx(inode) && filp->private_data)
55                 ext4_htree_free_dir_info(filp->private_data);
56
57         return 0;
58 }
59
60 static void ext4_unwritten_wait(struct inode *inode)
61 {
62         wait_queue_head_t *wq = ext4_ioend_wq(inode);
63
64         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
65 }
66
67 /*
68  * This tests whether the IO in question is block-aligned or not.
69  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
70  * are converted to written only after the IO is complete.  Until they are
71  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
72  * it needs to zero out portions of the start and/or end block.  If 2 AIO
73  * threads are at work on the same unwritten block, they must be synchronized
74  * or one thread will zero the other's data, causing corruption.
75  */
76 static int
77 ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
78 {
79         struct super_block *sb = inode->i_sb;
80         int blockmask = sb->s_blocksize - 1;
81
82         if (pos >= i_size_read(inode))
83                 return 0;
84
85         if ((pos | iov_iter_alignment(from)) & blockmask)
86                 return 1;
87
88         return 0;
89 }
90
91 static ssize_t
92 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
93 {
94         struct file *file = iocb->ki_filp;
95         struct inode *inode = file_inode(iocb->ki_filp);
96         struct mutex *aio_mutex = NULL;
97         struct blk_plug plug;
98         int o_direct = io_is_direct(file);
99         int overwrite = 0;
100         size_t length = iov_iter_count(from);
101         ssize_t ret;
102         loff_t pos = iocb->ki_pos;
103
104         /*
105          * Unaligned direct AIO must be serialized; see comment above
106          * In the case of O_APPEND, assume that we must always serialize
107          */
108         if (o_direct &&
109             ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
110             !is_sync_kiocb(iocb) &&
111             (file->f_flags & O_APPEND ||
112              ext4_unaligned_aio(inode, from, pos))) {
113                 aio_mutex = ext4_aio_mutex(inode);
114                 mutex_lock(aio_mutex);
115                 ext4_unwritten_wait(inode);
116         }
117
118         mutex_lock(&inode->i_mutex);
119         if (file->f_flags & O_APPEND)
120                 iocb->ki_pos = pos = i_size_read(inode);
121
122         /*
123          * If we have encountered a bitmap-format file, the size limit
124          * is smaller than s_maxbytes, which is for extent-mapped files.
125          */
126         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
127                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
128
129                 if ((pos > sbi->s_bitmap_maxbytes) ||
130                     (pos == sbi->s_bitmap_maxbytes && length > 0)) {
131                         mutex_unlock(&inode->i_mutex);
132                         ret = -EFBIG;
133                         goto errout;
134                 }
135
136                 if (pos + length > sbi->s_bitmap_maxbytes)
137                         iov_iter_truncate(from, sbi->s_bitmap_maxbytes - pos);
138         }
139
140         iocb->private = &overwrite;
141         if (o_direct) {
142                 blk_start_plug(&plug);
143
144
145                 /* check whether we do a DIO overwrite or not */
146                 if (ext4_should_dioread_nolock(inode) && !aio_mutex &&
147                     !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
148                         struct ext4_map_blocks map;
149                         unsigned int blkbits = inode->i_blkbits;
150                         int err, len;
151
152                         map.m_lblk = pos >> blkbits;
153                         map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
154                                 - map.m_lblk;
155                         len = map.m_len;
156
157                         err = ext4_map_blocks(NULL, inode, &map, 0);
158                         /*
159                          * 'err==len' means that all of blocks has
160                          * been preallocated no matter they are
161                          * initialized or not.  For excluding
162                          * unwritten extents, we need to check
163                          * m_flags.  There are two conditions that
164                          * indicate for initialized extents.  1) If we
165                          * hit extent cache, EXT4_MAP_MAPPED flag is
166                          * returned; 2) If we do a real lookup,
167                          * non-flags are returned.  So we should check
168                          * these two conditions.
169                          */
170                         if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
171                                 overwrite = 1;
172                 }
173         }
174
175         ret = __generic_file_write_iter(iocb, from);
176         mutex_unlock(&inode->i_mutex);
177
178         if (ret > 0) {
179                 ssize_t err;
180
181                 err = generic_write_sync(file, iocb->ki_pos - ret, ret);
182                 if (err < 0)
183                         ret = err;
184         }
185         if (o_direct)
186                 blk_finish_plug(&plug);
187
188 errout:
189         if (aio_mutex)
190                 mutex_unlock(aio_mutex);
191         return ret;
192 }
193
194 #ifdef CONFIG_FS_DAX
195 static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
196 {
197         return dax_fault(vma, vmf, ext4_get_block);
198                                         /* Is this the right get_block? */
199 }
200
201 static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
202 {
203         return dax_mkwrite(vma, vmf, ext4_get_block);
204 }
205
206 static const struct vm_operations_struct ext4_dax_vm_ops = {
207         .fault          = ext4_dax_fault,
208         .page_mkwrite   = ext4_dax_mkwrite,
209 };
210 #else
211 #define ext4_dax_vm_ops ext4_file_vm_ops
212 #endif
213
214 static const struct vm_operations_struct ext4_file_vm_ops = {
215         .fault          = filemap_fault,
216         .map_pages      = filemap_map_pages,
217         .page_mkwrite   = ext4_page_mkwrite,
218 };
219
220 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
221 {
222         file_accessed(file);
223         if (IS_DAX(file_inode(file))) {
224                 vma->vm_ops = &ext4_dax_vm_ops;
225                 vma->vm_flags |= VM_MIXEDMAP;
226         } else {
227                 vma->vm_ops = &ext4_file_vm_ops;
228         }
229         return 0;
230 }
231
232 static int ext4_file_open(struct inode * inode, struct file * filp)
233 {
234         struct super_block *sb = inode->i_sb;
235         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
236         struct vfsmount *mnt = filp->f_path.mnt;
237         struct path path;
238         char buf[64], *cp;
239
240         if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
241                      !(sb->s_flags & MS_RDONLY))) {
242                 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
243                 /*
244                  * Sample where the filesystem has been mounted and
245                  * store it in the superblock for sysadmin convenience
246                  * when trying to sort through large numbers of block
247                  * devices or filesystem images.
248                  */
249                 memset(buf, 0, sizeof(buf));
250                 path.mnt = mnt;
251                 path.dentry = mnt->mnt_root;
252                 cp = d_path(&path, buf, sizeof(buf));
253                 if (!IS_ERR(cp)) {
254                         handle_t *handle;
255                         int err;
256
257                         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
258                         if (IS_ERR(handle))
259                                 return PTR_ERR(handle);
260                         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
261                         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
262                         if (err) {
263                                 ext4_journal_stop(handle);
264                                 return err;
265                         }
266                         strlcpy(sbi->s_es->s_last_mounted, cp,
267                                 sizeof(sbi->s_es->s_last_mounted));
268                         ext4_handle_dirty_super(handle, sb);
269                         ext4_journal_stop(handle);
270                 }
271         }
272         /*
273          * Set up the jbd2_inode if we are opening the inode for
274          * writing and the journal is present
275          */
276         if (filp->f_mode & FMODE_WRITE) {
277                 int ret = ext4_inode_attach_jinode(inode);
278                 if (ret < 0)
279                         return ret;
280         }
281         return dquot_file_open(inode, filp);
282 }
283
284 /*
285  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
286  * file rather than ext4_ext_walk_space() because we can introduce
287  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
288  * function.  When extent status tree has been fully implemented, it will
289  * track all extent status for a file and we can directly use it to
290  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
291  */
292
293 /*
294  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
295  * lookup page cache to check whether or not there has some data between
296  * [startoff, endoff] because, if this range contains an unwritten extent,
297  * we determine this extent as a data or a hole according to whether the
298  * page cache has data or not.
299  */
300 static int ext4_find_unwritten_pgoff(struct inode *inode,
301                                      int whence,
302                                      struct ext4_map_blocks *map,
303                                      loff_t *offset)
304 {
305         struct pagevec pvec;
306         unsigned int blkbits;
307         pgoff_t index;
308         pgoff_t end;
309         loff_t endoff;
310         loff_t startoff;
311         loff_t lastoff;
312         int found = 0;
313
314         blkbits = inode->i_sb->s_blocksize_bits;
315         startoff = *offset;
316         lastoff = startoff;
317         endoff = (loff_t)(map->m_lblk + map->m_len) << blkbits;
318
319         index = startoff >> PAGE_CACHE_SHIFT;
320         end = endoff >> PAGE_CACHE_SHIFT;
321
322         pagevec_init(&pvec, 0);
323         do {
324                 int i, num;
325                 unsigned long nr_pages;
326
327                 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
328                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
329                                           (pgoff_t)num);
330                 if (nr_pages == 0) {
331                         if (whence == SEEK_DATA)
332                                 break;
333
334                         BUG_ON(whence != SEEK_HOLE);
335                         /*
336                          * If this is the first time to go into the loop and
337                          * offset is not beyond the end offset, it will be a
338                          * hole at this offset
339                          */
340                         if (lastoff == startoff || lastoff < endoff)
341                                 found = 1;
342                         break;
343                 }
344
345                 /*
346                  * If this is the first time to go into the loop and
347                  * offset is smaller than the first page offset, it will be a
348                  * hole at this offset.
349                  */
350                 if (lastoff == startoff && whence == SEEK_HOLE &&
351                     lastoff < page_offset(pvec.pages[0])) {
352                         found = 1;
353                         break;
354                 }
355
356                 for (i = 0; i < nr_pages; i++) {
357                         struct page *page = pvec.pages[i];
358                         struct buffer_head *bh, *head;
359
360                         /*
361                          * If the current offset is not beyond the end of given
362                          * range, it will be a hole.
363                          */
364                         if (lastoff < endoff && whence == SEEK_HOLE &&
365                             page->index > end) {
366                                 found = 1;
367                                 *offset = lastoff;
368                                 goto out;
369                         }
370
371                         lock_page(page);
372
373                         if (unlikely(page->mapping != inode->i_mapping)) {
374                                 unlock_page(page);
375                                 continue;
376                         }
377
378                         if (!page_has_buffers(page)) {
379                                 unlock_page(page);
380                                 continue;
381                         }
382
383                         if (page_has_buffers(page)) {
384                                 lastoff = page_offset(page);
385                                 bh = head = page_buffers(page);
386                                 do {
387                                         if (buffer_uptodate(bh) ||
388                                             buffer_unwritten(bh)) {
389                                                 if (whence == SEEK_DATA)
390                                                         found = 1;
391                                         } else {
392                                                 if (whence == SEEK_HOLE)
393                                                         found = 1;
394                                         }
395                                         if (found) {
396                                                 *offset = max_t(loff_t,
397                                                         startoff, lastoff);
398                                                 unlock_page(page);
399                                                 goto out;
400                                         }
401                                         lastoff += bh->b_size;
402                                         bh = bh->b_this_page;
403                                 } while (bh != head);
404                         }
405
406                         lastoff = page_offset(page) + PAGE_SIZE;
407                         unlock_page(page);
408                 }
409
410                 /*
411                  * The no. of pages is less than our desired, that would be a
412                  * hole in there.
413                  */
414                 if (nr_pages < num && whence == SEEK_HOLE) {
415                         found = 1;
416                         *offset = lastoff;
417                         break;
418                 }
419
420                 index = pvec.pages[i - 1]->index + 1;
421                 pagevec_release(&pvec);
422         } while (index <= end);
423
424 out:
425         pagevec_release(&pvec);
426         return found;
427 }
428
429 /*
430  * ext4_seek_data() retrieves the offset for SEEK_DATA.
431  */
432 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
433 {
434         struct inode *inode = file->f_mapping->host;
435         struct ext4_map_blocks map;
436         struct extent_status es;
437         ext4_lblk_t start, last, end;
438         loff_t dataoff, isize;
439         int blkbits;
440         int ret = 0;
441
442         mutex_lock(&inode->i_mutex);
443
444         isize = i_size_read(inode);
445         if (offset >= isize) {
446                 mutex_unlock(&inode->i_mutex);
447                 return -ENXIO;
448         }
449
450         blkbits = inode->i_sb->s_blocksize_bits;
451         start = offset >> blkbits;
452         last = start;
453         end = isize >> blkbits;
454         dataoff = offset;
455
456         do {
457                 map.m_lblk = last;
458                 map.m_len = end - last + 1;
459                 ret = ext4_map_blocks(NULL, inode, &map, 0);
460                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
461                         if (last != start)
462                                 dataoff = (loff_t)last << blkbits;
463                         break;
464                 }
465
466                 /*
467                  * If there is a delay extent at this offset,
468                  * it will be as a data.
469                  */
470                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
471                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
472                         if (last != start)
473                                 dataoff = (loff_t)last << blkbits;
474                         break;
475                 }
476
477                 /*
478                  * If there is a unwritten extent at this offset,
479                  * it will be as a data or a hole according to page
480                  * cache that has data or not.
481                  */
482                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
483                         int unwritten;
484                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_DATA,
485                                                               &map, &dataoff);
486                         if (unwritten)
487                                 break;
488                 }
489
490                 last++;
491                 dataoff = (loff_t)last << blkbits;
492         } while (last <= end);
493
494         mutex_unlock(&inode->i_mutex);
495
496         if (dataoff > isize)
497                 return -ENXIO;
498
499         return vfs_setpos(file, dataoff, maxsize);
500 }
501
502 /*
503  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
504  */
505 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
506 {
507         struct inode *inode = file->f_mapping->host;
508         struct ext4_map_blocks map;
509         struct extent_status es;
510         ext4_lblk_t start, last, end;
511         loff_t holeoff, isize;
512         int blkbits;
513         int ret = 0;
514
515         mutex_lock(&inode->i_mutex);
516
517         isize = i_size_read(inode);
518         if (offset >= isize) {
519                 mutex_unlock(&inode->i_mutex);
520                 return -ENXIO;
521         }
522
523         blkbits = inode->i_sb->s_blocksize_bits;
524         start = offset >> blkbits;
525         last = start;
526         end = isize >> blkbits;
527         holeoff = offset;
528
529         do {
530                 map.m_lblk = last;
531                 map.m_len = end - last + 1;
532                 ret = ext4_map_blocks(NULL, inode, &map, 0);
533                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
534                         last += ret;
535                         holeoff = (loff_t)last << blkbits;
536                         continue;
537                 }
538
539                 /*
540                  * If there is a delay extent at this offset,
541                  * we will skip this extent.
542                  */
543                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
544                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
545                         last = es.es_lblk + es.es_len;
546                         holeoff = (loff_t)last << blkbits;
547                         continue;
548                 }
549
550                 /*
551                  * If there is a unwritten extent at this offset,
552                  * it will be as a data or a hole according to page
553                  * cache that has data or not.
554                  */
555                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
556                         int unwritten;
557                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
558                                                               &map, &holeoff);
559                         if (!unwritten) {
560                                 last += ret;
561                                 holeoff = (loff_t)last << blkbits;
562                                 continue;
563                         }
564                 }
565
566                 /* find a hole */
567                 break;
568         } while (last <= end);
569
570         mutex_unlock(&inode->i_mutex);
571
572         if (holeoff > isize)
573                 holeoff = isize;
574
575         return vfs_setpos(file, holeoff, maxsize);
576 }
577
578 /*
579  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
580  * by calling generic_file_llseek_size() with the appropriate maxbytes
581  * value for each.
582  */
583 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
584 {
585         struct inode *inode = file->f_mapping->host;
586         loff_t maxbytes;
587
588         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
589                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
590         else
591                 maxbytes = inode->i_sb->s_maxbytes;
592
593         switch (whence) {
594         case SEEK_SET:
595         case SEEK_CUR:
596         case SEEK_END:
597                 return generic_file_llseek_size(file, offset, whence,
598                                                 maxbytes, i_size_read(inode));
599         case SEEK_DATA:
600                 return ext4_seek_data(file, offset, maxbytes);
601         case SEEK_HOLE:
602                 return ext4_seek_hole(file, offset, maxbytes);
603         }
604
605         return -EINVAL;
606 }
607
608 const struct file_operations ext4_file_operations = {
609         .llseek         = ext4_llseek,
610         .read           = new_sync_read,
611         .write          = new_sync_write,
612         .read_iter      = generic_file_read_iter,
613         .write_iter     = ext4_file_write_iter,
614         .unlocked_ioctl = ext4_ioctl,
615 #ifdef CONFIG_COMPAT
616         .compat_ioctl   = ext4_compat_ioctl,
617 #endif
618         .mmap           = ext4_file_mmap,
619         .open           = ext4_file_open,
620         .release        = ext4_release_file,
621         .fsync          = ext4_sync_file,
622         .splice_read    = generic_file_splice_read,
623         .splice_write   = iter_file_splice_write,
624         .fallocate      = ext4_fallocate,
625 };
626
627 #ifdef CONFIG_FS_DAX
628 const struct file_operations ext4_dax_file_operations = {
629         .llseek         = ext4_llseek,
630         .read           = new_sync_read,
631         .write          = new_sync_write,
632         .read_iter      = generic_file_read_iter,
633         .write_iter     = ext4_file_write_iter,
634         .unlocked_ioctl = ext4_ioctl,
635 #ifdef CONFIG_COMPAT
636         .compat_ioctl   = ext4_compat_ioctl,
637 #endif
638         .mmap           = ext4_file_mmap,
639         .open           = ext4_file_open,
640         .release        = ext4_release_file,
641         .fsync          = ext4_sync_file,
642         /* Splice not yet supported with DAX */
643         .fallocate      = ext4_fallocate,
644 };
645 #endif
646
647 const struct inode_operations ext4_file_inode_operations = {
648         .setattr        = ext4_setattr,
649         .getattr        = ext4_getattr,
650         .setxattr       = generic_setxattr,
651         .getxattr       = generic_getxattr,
652         .listxattr      = ext4_listxattr,
653         .removexattr    = generic_removexattr,
654         .get_acl        = ext4_get_acl,
655         .set_acl        = ext4_set_acl,
656         .fiemap         = ext4_fiemap,
657 };
658