xref: /openbmc/linux/fs/ext4/file.c (revision ae3473231e77a3f1909d48cd144cebe5e1d049b3)
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/mount.h>
24 #include <linux/path.h>
25 #include <linux/dax.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 #ifdef CONFIG_FS_DAX
35 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
36 {
37 	struct inode *inode = file_inode(iocb->ki_filp);
38 	ssize_t ret;
39 
40 	inode_lock_shared(inode);
41 	/*
42 	 * Recheck under inode lock - at this point we are sure it cannot
43 	 * change anymore
44 	 */
45 	if (!IS_DAX(inode)) {
46 		inode_unlock_shared(inode);
47 		/* Fallback to buffered IO in case we cannot support DAX */
48 		return generic_file_read_iter(iocb, to);
49 	}
50 	ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
51 	inode_unlock_shared(inode);
52 
53 	file_accessed(iocb->ki_filp);
54 	return ret;
55 }
56 #endif
57 
58 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
59 {
60 	if (!iov_iter_count(to))
61 		return 0; /* skip atime */
62 
63 #ifdef CONFIG_FS_DAX
64 	if (IS_DAX(file_inode(iocb->ki_filp)))
65 		return ext4_dax_read_iter(iocb, to);
66 #endif
67 	return generic_file_read_iter(iocb, to);
68 }
69 
70 /*
71  * Called when an inode is released. Note that this is different
72  * from ext4_file_open: open gets called at every open, but release
73  * gets called only when /all/ the files are closed.
74  */
75 static int ext4_release_file(struct inode *inode, struct file *filp)
76 {
77 	if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
78 		ext4_alloc_da_blocks(inode);
79 		ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
80 	}
81 	/* if we are the last writer on the inode, drop the block reservation */
82 	if ((filp->f_mode & FMODE_WRITE) &&
83 			(atomic_read(&inode->i_writecount) == 1) &&
84 		        !EXT4_I(inode)->i_reserved_data_blocks)
85 	{
86 		down_write(&EXT4_I(inode)->i_data_sem);
87 		ext4_discard_preallocations(inode);
88 		up_write(&EXT4_I(inode)->i_data_sem);
89 	}
90 	if (is_dx(inode) && filp->private_data)
91 		ext4_htree_free_dir_info(filp->private_data);
92 
93 	return 0;
94 }
95 
96 static void ext4_unwritten_wait(struct inode *inode)
97 {
98 	wait_queue_head_t *wq = ext4_ioend_wq(inode);
99 
100 	wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
101 }
102 
103 /*
104  * This tests whether the IO in question is block-aligned or not.
105  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
106  * are converted to written only after the IO is complete.  Until they are
107  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
108  * it needs to zero out portions of the start and/or end block.  If 2 AIO
109  * threads are at work on the same unwritten block, they must be synchronized
110  * or one thread will zero the other's data, causing corruption.
111  */
112 static int
113 ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
114 {
115 	struct super_block *sb = inode->i_sb;
116 	int blockmask = sb->s_blocksize - 1;
117 
118 	if (pos >= i_size_read(inode))
119 		return 0;
120 
121 	if ((pos | iov_iter_alignment(from)) & blockmask)
122 		return 1;
123 
124 	return 0;
125 }
126 
127 /* Is IO overwriting allocated and initialized blocks? */
128 static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
129 {
130 	struct ext4_map_blocks map;
131 	unsigned int blkbits = inode->i_blkbits;
132 	int err, blklen;
133 
134 	if (pos + len > i_size_read(inode))
135 		return false;
136 
137 	map.m_lblk = pos >> blkbits;
138 	map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
139 	blklen = map.m_len;
140 
141 	err = ext4_map_blocks(NULL, inode, &map, 0);
142 	/*
143 	 * 'err==len' means that all of the blocks have been preallocated,
144 	 * regardless of whether they have been initialized or not. To exclude
145 	 * unwritten extents, we need to check m_flags.
146 	 */
147 	return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
148 }
149 
150 static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
151 {
152 	struct inode *inode = file_inode(iocb->ki_filp);
153 	ssize_t ret;
154 
155 	ret = generic_write_checks(iocb, from);
156 	if (ret <= 0)
157 		return ret;
158 	/*
159 	 * If we have encountered a bitmap-format file, the size limit
160 	 * is smaller than s_maxbytes, which is for extent-mapped files.
161 	 */
162 	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
163 		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
164 
165 		if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
166 			return -EFBIG;
167 		iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
168 	}
169 	return iov_iter_count(from);
170 }
171 
172 #ifdef CONFIG_FS_DAX
173 static ssize_t
174 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
175 {
176 	struct inode *inode = file_inode(iocb->ki_filp);
177 	ssize_t ret;
178 	bool overwrite = false;
179 
180 	inode_lock(inode);
181 	ret = ext4_write_checks(iocb, from);
182 	if (ret <= 0)
183 		goto out;
184 	ret = file_remove_privs(iocb->ki_filp);
185 	if (ret)
186 		goto out;
187 	ret = file_update_time(iocb->ki_filp);
188 	if (ret)
189 		goto out;
190 
191 	if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {
192 		overwrite = true;
193 		downgrade_write(&inode->i_rwsem);
194 	}
195 	ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
196 out:
197 	if (!overwrite)
198 		inode_unlock(inode);
199 	else
200 		inode_unlock_shared(inode);
201 	if (ret > 0)
202 		ret = generic_write_sync(iocb, ret);
203 	return ret;
204 }
205 #endif
206 
207 static ssize_t
208 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
209 {
210 	struct inode *inode = file_inode(iocb->ki_filp);
211 	int o_direct = iocb->ki_flags & IOCB_DIRECT;
212 	int unaligned_aio = 0;
213 	int overwrite = 0;
214 	ssize_t ret;
215 
216 #ifdef CONFIG_FS_DAX
217 	if (IS_DAX(inode))
218 		return ext4_dax_write_iter(iocb, from);
219 #endif
220 
221 	inode_lock(inode);
222 	ret = ext4_write_checks(iocb, from);
223 	if (ret <= 0)
224 		goto out;
225 
226 	/*
227 	 * Unaligned direct AIO must be serialized among each other as zeroing
228 	 * of partial blocks of two competing unaligned AIOs can result in data
229 	 * corruption.
230 	 */
231 	if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
232 	    !is_sync_kiocb(iocb) &&
233 	    ext4_unaligned_aio(inode, from, iocb->ki_pos)) {
234 		unaligned_aio = 1;
235 		ext4_unwritten_wait(inode);
236 	}
237 
238 	iocb->private = &overwrite;
239 	/* Check whether we do a DIO overwrite or not */
240 	if (o_direct && ext4_should_dioread_nolock(inode) && !unaligned_aio &&
241 	    ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from)))
242 		overwrite = 1;
243 
244 	ret = __generic_file_write_iter(iocb, from);
245 	inode_unlock(inode);
246 
247 	if (ret > 0)
248 		ret = generic_write_sync(iocb, ret);
249 
250 	return ret;
251 
252 out:
253 	inode_unlock(inode);
254 	return ret;
255 }
256 
257 #ifdef CONFIG_FS_DAX
258 static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
259 {
260 	int result;
261 	handle_t *handle = NULL;
262 	struct inode *inode = file_inode(vma->vm_file);
263 	struct super_block *sb = inode->i_sb;
264 	bool write = vmf->flags & FAULT_FLAG_WRITE;
265 
266 	if (write) {
267 		sb_start_pagefault(sb);
268 		file_update_time(vma->vm_file);
269 		down_read(&EXT4_I(inode)->i_mmap_sem);
270 		handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
271 						EXT4_DATA_TRANS_BLOCKS(sb));
272 	} else
273 		down_read(&EXT4_I(inode)->i_mmap_sem);
274 
275 	if (IS_ERR(handle))
276 		result = VM_FAULT_SIGBUS;
277 	else
278 		result = dax_iomap_fault(vma, vmf, &ext4_iomap_ops);
279 
280 	if (write) {
281 		if (!IS_ERR(handle))
282 			ext4_journal_stop(handle);
283 		up_read(&EXT4_I(inode)->i_mmap_sem);
284 		sb_end_pagefault(sb);
285 	} else
286 		up_read(&EXT4_I(inode)->i_mmap_sem);
287 
288 	return result;
289 }
290 
291 static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
292 						pmd_t *pmd, unsigned int flags)
293 {
294 	int result;
295 	handle_t *handle = NULL;
296 	struct inode *inode = file_inode(vma->vm_file);
297 	struct super_block *sb = inode->i_sb;
298 	bool write = flags & FAULT_FLAG_WRITE;
299 
300 	if (write) {
301 		sb_start_pagefault(sb);
302 		file_update_time(vma->vm_file);
303 		down_read(&EXT4_I(inode)->i_mmap_sem);
304 		handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
305 				ext4_chunk_trans_blocks(inode,
306 							PMD_SIZE / PAGE_SIZE));
307 	} else
308 		down_read(&EXT4_I(inode)->i_mmap_sem);
309 
310 	if (IS_ERR(handle))
311 		result = VM_FAULT_SIGBUS;
312 	else {
313 		result = dax_iomap_pmd_fault(vma, addr, pmd, flags,
314 					     &ext4_iomap_ops);
315 	}
316 
317 	if (write) {
318 		if (!IS_ERR(handle))
319 			ext4_journal_stop(handle);
320 		up_read(&EXT4_I(inode)->i_mmap_sem);
321 		sb_end_pagefault(sb);
322 	} else
323 		up_read(&EXT4_I(inode)->i_mmap_sem);
324 
325 	return result;
326 }
327 
328 /*
329  * Handle write fault for VM_MIXEDMAP mappings. Similarly to ext4_dax_fault()
330  * handler we check for races agaist truncate. Note that since we cycle through
331  * i_mmap_sem, we are sure that also any hole punching that began before we
332  * were called is finished by now and so if it included part of the file we
333  * are working on, our pte will get unmapped and the check for pte_same() in
334  * wp_pfn_shared() fails. Thus fault gets retried and things work out as
335  * desired.
336  */
337 static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma,
338 				struct vm_fault *vmf)
339 {
340 	struct inode *inode = file_inode(vma->vm_file);
341 	struct super_block *sb = inode->i_sb;
342 	loff_t size;
343 	int ret;
344 
345 	sb_start_pagefault(sb);
346 	file_update_time(vma->vm_file);
347 	down_read(&EXT4_I(inode)->i_mmap_sem);
348 	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
349 	if (vmf->pgoff >= size)
350 		ret = VM_FAULT_SIGBUS;
351 	else
352 		ret = dax_pfn_mkwrite(vma, vmf);
353 	up_read(&EXT4_I(inode)->i_mmap_sem);
354 	sb_end_pagefault(sb);
355 
356 	return ret;
357 }
358 
359 static const struct vm_operations_struct ext4_dax_vm_ops = {
360 	.fault		= ext4_dax_fault,
361 	.pmd_fault	= ext4_dax_pmd_fault,
362 	.page_mkwrite	= ext4_dax_fault,
363 	.pfn_mkwrite	= ext4_dax_pfn_mkwrite,
364 };
365 #else
366 #define ext4_dax_vm_ops	ext4_file_vm_ops
367 #endif
368 
369 static const struct vm_operations_struct ext4_file_vm_ops = {
370 	.fault		= ext4_filemap_fault,
371 	.map_pages	= filemap_map_pages,
372 	.page_mkwrite   = ext4_page_mkwrite,
373 };
374 
375 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
376 {
377 	struct inode *inode = file->f_mapping->host;
378 
379 	if (ext4_encrypted_inode(inode)) {
380 		int err = fscrypt_get_encryption_info(inode);
381 		if (err)
382 			return 0;
383 		if (!fscrypt_has_encryption_key(inode))
384 			return -ENOKEY;
385 	}
386 	file_accessed(file);
387 	if (IS_DAX(file_inode(file))) {
388 		vma->vm_ops = &ext4_dax_vm_ops;
389 		vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
390 	} else {
391 		vma->vm_ops = &ext4_file_vm_ops;
392 	}
393 	return 0;
394 }
395 
396 static int ext4_file_open(struct inode * inode, struct file * filp)
397 {
398 	struct super_block *sb = inode->i_sb;
399 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
400 	struct vfsmount *mnt = filp->f_path.mnt;
401 	struct dentry *dir;
402 	struct path path;
403 	char buf[64], *cp;
404 	int ret;
405 
406 	if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
407 		     !(sb->s_flags & MS_RDONLY))) {
408 		sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
409 		/*
410 		 * Sample where the filesystem has been mounted and
411 		 * store it in the superblock for sysadmin convenience
412 		 * when trying to sort through large numbers of block
413 		 * devices or filesystem images.
414 		 */
415 		memset(buf, 0, sizeof(buf));
416 		path.mnt = mnt;
417 		path.dentry = mnt->mnt_root;
418 		cp = d_path(&path, buf, sizeof(buf));
419 		if (!IS_ERR(cp)) {
420 			handle_t *handle;
421 			int err;
422 
423 			handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
424 			if (IS_ERR(handle))
425 				return PTR_ERR(handle);
426 			BUFFER_TRACE(sbi->s_sbh, "get_write_access");
427 			err = ext4_journal_get_write_access(handle, sbi->s_sbh);
428 			if (err) {
429 				ext4_journal_stop(handle);
430 				return err;
431 			}
432 			strlcpy(sbi->s_es->s_last_mounted, cp,
433 				sizeof(sbi->s_es->s_last_mounted));
434 			ext4_handle_dirty_super(handle, sb);
435 			ext4_journal_stop(handle);
436 		}
437 	}
438 	if (ext4_encrypted_inode(inode)) {
439 		ret = fscrypt_get_encryption_info(inode);
440 		if (ret)
441 			return -EACCES;
442 		if (!fscrypt_has_encryption_key(inode))
443 			return -ENOKEY;
444 	}
445 
446 	dir = dget_parent(file_dentry(filp));
447 	if (ext4_encrypted_inode(d_inode(dir)) &&
448 			!fscrypt_has_permitted_context(d_inode(dir), inode)) {
449 		ext4_warning(inode->i_sb,
450 			     "Inconsistent encryption contexts: %lu/%lu",
451 			     (unsigned long) d_inode(dir)->i_ino,
452 			     (unsigned long) inode->i_ino);
453 		dput(dir);
454 		return -EPERM;
455 	}
456 	dput(dir);
457 	/*
458 	 * Set up the jbd2_inode if we are opening the inode for
459 	 * writing and the journal is present
460 	 */
461 	if (filp->f_mode & FMODE_WRITE) {
462 		ret = ext4_inode_attach_jinode(inode);
463 		if (ret < 0)
464 			return ret;
465 	}
466 	return dquot_file_open(inode, filp);
467 }
468 
469 /*
470  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
471  * file rather than ext4_ext_walk_space() because we can introduce
472  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
473  * function.  When extent status tree has been fully implemented, it will
474  * track all extent status for a file and we can directly use it to
475  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
476  */
477 
478 /*
479  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
480  * lookup page cache to check whether or not there has some data between
481  * [startoff, endoff] because, if this range contains an unwritten extent,
482  * we determine this extent as a data or a hole according to whether the
483  * page cache has data or not.
484  */
485 static int ext4_find_unwritten_pgoff(struct inode *inode,
486 				     int whence,
487 				     ext4_lblk_t end_blk,
488 				     loff_t *offset)
489 {
490 	struct pagevec pvec;
491 	unsigned int blkbits;
492 	pgoff_t index;
493 	pgoff_t end;
494 	loff_t endoff;
495 	loff_t startoff;
496 	loff_t lastoff;
497 	int found = 0;
498 
499 	blkbits = inode->i_sb->s_blocksize_bits;
500 	startoff = *offset;
501 	lastoff = startoff;
502 	endoff = (loff_t)end_blk << blkbits;
503 
504 	index = startoff >> PAGE_SHIFT;
505 	end = endoff >> PAGE_SHIFT;
506 
507 	pagevec_init(&pvec, 0);
508 	do {
509 		int i, num;
510 		unsigned long nr_pages;
511 
512 		num = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
513 		nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
514 					  (pgoff_t)num);
515 		if (nr_pages == 0) {
516 			if (whence == SEEK_DATA)
517 				break;
518 
519 			BUG_ON(whence != SEEK_HOLE);
520 			/*
521 			 * If this is the first time to go into the loop and
522 			 * offset is not beyond the end offset, it will be a
523 			 * hole at this offset
524 			 */
525 			if (lastoff == startoff || lastoff < endoff)
526 				found = 1;
527 			break;
528 		}
529 
530 		/*
531 		 * If this is the first time to go into the loop and
532 		 * offset is smaller than the first page offset, it will be a
533 		 * hole at this offset.
534 		 */
535 		if (lastoff == startoff && whence == SEEK_HOLE &&
536 		    lastoff < page_offset(pvec.pages[0])) {
537 			found = 1;
538 			break;
539 		}
540 
541 		for (i = 0; i < nr_pages; i++) {
542 			struct page *page = pvec.pages[i];
543 			struct buffer_head *bh, *head;
544 
545 			/*
546 			 * If the current offset is not beyond the end of given
547 			 * range, it will be a hole.
548 			 */
549 			if (lastoff < endoff && whence == SEEK_HOLE &&
550 			    page->index > end) {
551 				found = 1;
552 				*offset = lastoff;
553 				goto out;
554 			}
555 
556 			lock_page(page);
557 
558 			if (unlikely(page->mapping != inode->i_mapping)) {
559 				unlock_page(page);
560 				continue;
561 			}
562 
563 			if (!page_has_buffers(page)) {
564 				unlock_page(page);
565 				continue;
566 			}
567 
568 			if (page_has_buffers(page)) {
569 				lastoff = page_offset(page);
570 				bh = head = page_buffers(page);
571 				do {
572 					if (buffer_uptodate(bh) ||
573 					    buffer_unwritten(bh)) {
574 						if (whence == SEEK_DATA)
575 							found = 1;
576 					} else {
577 						if (whence == SEEK_HOLE)
578 							found = 1;
579 					}
580 					if (found) {
581 						*offset = max_t(loff_t,
582 							startoff, lastoff);
583 						unlock_page(page);
584 						goto out;
585 					}
586 					lastoff += bh->b_size;
587 					bh = bh->b_this_page;
588 				} while (bh != head);
589 			}
590 
591 			lastoff = page_offset(page) + PAGE_SIZE;
592 			unlock_page(page);
593 		}
594 
595 		/*
596 		 * The no. of pages is less than our desired, that would be a
597 		 * hole in there.
598 		 */
599 		if (nr_pages < num && whence == SEEK_HOLE) {
600 			found = 1;
601 			*offset = lastoff;
602 			break;
603 		}
604 
605 		index = pvec.pages[i - 1]->index + 1;
606 		pagevec_release(&pvec);
607 	} while (index <= end);
608 
609 out:
610 	pagevec_release(&pvec);
611 	return found;
612 }
613 
614 /*
615  * ext4_seek_data() retrieves the offset for SEEK_DATA.
616  */
617 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
618 {
619 	struct inode *inode = file->f_mapping->host;
620 	struct extent_status es;
621 	ext4_lblk_t start, last, end;
622 	loff_t dataoff, isize;
623 	int blkbits;
624 	int ret;
625 
626 	inode_lock(inode);
627 
628 	isize = i_size_read(inode);
629 	if (offset >= isize) {
630 		inode_unlock(inode);
631 		return -ENXIO;
632 	}
633 
634 	blkbits = inode->i_sb->s_blocksize_bits;
635 	start = offset >> blkbits;
636 	last = start;
637 	end = isize >> blkbits;
638 	dataoff = offset;
639 
640 	do {
641 		ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
642 		if (ret <= 0) {
643 			/* No extent found -> no data */
644 			if (ret == 0)
645 				ret = -ENXIO;
646 			inode_unlock(inode);
647 			return ret;
648 		}
649 
650 		last = es.es_lblk;
651 		if (last != start)
652 			dataoff = (loff_t)last << blkbits;
653 		if (!ext4_es_is_unwritten(&es))
654 			break;
655 
656 		/*
657 		 * If there is a unwritten extent at this offset,
658 		 * it will be as a data or a hole according to page
659 		 * cache that has data or not.
660 		 */
661 		if (ext4_find_unwritten_pgoff(inode, SEEK_DATA,
662 					      es.es_lblk + es.es_len, &dataoff))
663 			break;
664 		last += es.es_len;
665 		dataoff = (loff_t)last << blkbits;
666 		cond_resched();
667 	} while (last <= end);
668 
669 	inode_unlock(inode);
670 
671 	if (dataoff > isize)
672 		return -ENXIO;
673 
674 	return vfs_setpos(file, dataoff, maxsize);
675 }
676 
677 /*
678  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
679  */
680 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
681 {
682 	struct inode *inode = file->f_mapping->host;
683 	struct extent_status es;
684 	ext4_lblk_t start, last, end;
685 	loff_t holeoff, isize;
686 	int blkbits;
687 	int ret;
688 
689 	inode_lock(inode);
690 
691 	isize = i_size_read(inode);
692 	if (offset >= isize) {
693 		inode_unlock(inode);
694 		return -ENXIO;
695 	}
696 
697 	blkbits = inode->i_sb->s_blocksize_bits;
698 	start = offset >> blkbits;
699 	last = start;
700 	end = isize >> blkbits;
701 	holeoff = offset;
702 
703 	do {
704 		ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
705 		if (ret < 0) {
706 			inode_unlock(inode);
707 			return ret;
708 		}
709 		/* Found a hole? */
710 		if (ret == 0 || es.es_lblk > last) {
711 			if (last != start)
712 				holeoff = (loff_t)last << blkbits;
713 			break;
714 		}
715 		/*
716 		 * If there is a unwritten extent at this offset,
717 		 * it will be as a data or a hole according to page
718 		 * cache that has data or not.
719 		 */
720 		if (ext4_es_is_unwritten(&es) &&
721 		    ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
722 					      last + es.es_len, &holeoff))
723 			break;
724 
725 		last += es.es_len;
726 		holeoff = (loff_t)last << blkbits;
727 		cond_resched();
728 	} while (last <= end);
729 
730 	inode_unlock(inode);
731 
732 	if (holeoff > isize)
733 		holeoff = isize;
734 
735 	return vfs_setpos(file, holeoff, maxsize);
736 }
737 
738 /*
739  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
740  * by calling generic_file_llseek_size() with the appropriate maxbytes
741  * value for each.
742  */
743 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
744 {
745 	struct inode *inode = file->f_mapping->host;
746 	loff_t maxbytes;
747 
748 	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
749 		maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
750 	else
751 		maxbytes = inode->i_sb->s_maxbytes;
752 
753 	switch (whence) {
754 	case SEEK_SET:
755 	case SEEK_CUR:
756 	case SEEK_END:
757 		return generic_file_llseek_size(file, offset, whence,
758 						maxbytes, i_size_read(inode));
759 	case SEEK_DATA:
760 		return ext4_seek_data(file, offset, maxbytes);
761 	case SEEK_HOLE:
762 		return ext4_seek_hole(file, offset, maxbytes);
763 	}
764 
765 	return -EINVAL;
766 }
767 
768 const struct file_operations ext4_file_operations = {
769 	.llseek		= ext4_llseek,
770 	.read_iter	= ext4_file_read_iter,
771 	.write_iter	= ext4_file_write_iter,
772 	.unlocked_ioctl = ext4_ioctl,
773 #ifdef CONFIG_COMPAT
774 	.compat_ioctl	= ext4_compat_ioctl,
775 #endif
776 	.mmap		= ext4_file_mmap,
777 	.open		= ext4_file_open,
778 	.release	= ext4_release_file,
779 	.fsync		= ext4_sync_file,
780 	.get_unmapped_area = thp_get_unmapped_area,
781 	.splice_read	= generic_file_splice_read,
782 	.splice_write	= iter_file_splice_write,
783 	.fallocate	= ext4_fallocate,
784 };
785 
786 const struct inode_operations ext4_file_inode_operations = {
787 	.setattr	= ext4_setattr,
788 	.getattr	= ext4_getattr,
789 	.listxattr	= ext4_listxattr,
790 	.get_acl	= ext4_get_acl,
791 	.set_acl	= ext4_set_acl,
792 	.fiemap		= ext4_fiemap,
793 };
794 
795