1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/ext4/file.c
4 *
5 * Copyright (C) 1992, 1993, 1994, 1995
6 * Remy Card (card@masi.ibp.fr)
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
9 *
10 * from
11 *
12 * linux/fs/minix/file.c
13 *
14 * Copyright (C) 1991, 1992 Linus Torvalds
15 *
16 * ext4 fs regular file handling primitives
17 *
18 * 64-bit file support on 64-bit platforms by Jakub Jelinek
19 * (jj@sunsite.ms.mff.cuni.cz)
20 */
21
22 #include <linux/time.h>
23 #include <linux/fs.h>
24 #include <linux/iomap.h>
25 #include <linux/mount.h>
26 #include <linux/path.h>
27 #include <linux/dax.h>
28 #include <linux/quotaops.h>
29 #include <linux/pagevec.h>
30 #include <linux/uio.h>
31 #include <linux/mman.h>
32 #include "ext4.h"
33 #include "ext4_jbd2.h"
34 #include "xattr.h"
35 #include "acl.h"
36
37 #ifdef CONFIG_FS_DAX
ext4_dax_read_iter(struct kiocb * iocb,struct iov_iter * to)38 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
39 {
40 struct inode *inode = file_inode(iocb->ki_filp);
41 ssize_t ret;
42
43 if (!inode_trylock_shared(inode)) {
44 if (iocb->ki_flags & IOCB_NOWAIT)
45 return -EAGAIN;
46 inode_lock_shared(inode);
47 }
48 /*
49 * Recheck under inode lock - at this point we are sure it cannot
50 * change anymore
51 */
52 if (!IS_DAX(inode)) {
53 inode_unlock_shared(inode);
54 /* Fallback to buffered IO in case we cannot support DAX */
55 return generic_file_read_iter(iocb, to);
56 }
57 ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
58 inode_unlock_shared(inode);
59
60 file_accessed(iocb->ki_filp);
61 return ret;
62 }
63 #endif
64
ext4_file_read_iter(struct kiocb * iocb,struct iov_iter * to)65 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
66 {
67 if (unlikely(ext4_forced_shutdown(EXT4_SB(file_inode(iocb->ki_filp)->i_sb))))
68 return -EIO;
69
70 if (!iov_iter_count(to))
71 return 0; /* skip atime */
72
73 #ifdef CONFIG_FS_DAX
74 if (IS_DAX(file_inode(iocb->ki_filp)))
75 return ext4_dax_read_iter(iocb, to);
76 #endif
77 return generic_file_read_iter(iocb, to);
78 }
79
80 /*
81 * Called when an inode is released. Note that this is different
82 * from ext4_file_open: open gets called at every open, but release
83 * gets called only when /all/ the files are closed.
84 */
ext4_release_file(struct inode * inode,struct file * filp)85 static int ext4_release_file(struct inode *inode, struct file *filp)
86 {
87 if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
88 ext4_alloc_da_blocks(inode);
89 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
90 }
91 /* if we are the last writer on the inode, drop the block reservation */
92 if ((filp->f_mode & FMODE_WRITE) &&
93 (atomic_read(&inode->i_writecount) == 1) &&
94 !EXT4_I(inode)->i_reserved_data_blocks)
95 {
96 down_write(&EXT4_I(inode)->i_data_sem);
97 ext4_discard_preallocations(inode);
98 up_write(&EXT4_I(inode)->i_data_sem);
99 }
100 if (is_dx(inode) && filp->private_data)
101 ext4_htree_free_dir_info(filp->private_data);
102
103 return 0;
104 }
105
ext4_unwritten_wait(struct inode * inode)106 static void ext4_unwritten_wait(struct inode *inode)
107 {
108 wait_queue_head_t *wq = ext4_ioend_wq(inode);
109
110 wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
111 }
112
113 /*
114 * This tests whether the IO in question is block-aligned or not.
115 * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
116 * are converted to written only after the IO is complete. Until they are
117 * mapped, these blocks appear as holes, so dio_zero_block() will assume that
118 * it needs to zero out portions of the start and/or end block. If 2 AIO
119 * threads are at work on the same unwritten block, they must be synchronized
120 * or one thread will zero the other's data, causing corruption.
121 */
122 static int
ext4_unaligned_aio(struct inode * inode,struct iov_iter * from,loff_t pos)123 ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
124 {
125 struct super_block *sb = inode->i_sb;
126 int blockmask = sb->s_blocksize - 1;
127
128 if (pos >= ALIGN(i_size_read(inode), sb->s_blocksize))
129 return 0;
130
131 if ((pos | iov_iter_alignment(from)) & blockmask)
132 return 1;
133
134 return 0;
135 }
136
137 /* Is IO overwriting allocated and initialized blocks? */
ext4_overwrite_io(struct inode * inode,loff_t pos,loff_t len)138 static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
139 {
140 struct ext4_map_blocks map;
141 unsigned int blkbits = inode->i_blkbits;
142 int err, blklen;
143
144 if (pos + len > i_size_read(inode))
145 return false;
146
147 map.m_lblk = pos >> blkbits;
148 map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
149 blklen = map.m_len;
150
151 err = ext4_map_blocks(NULL, inode, &map, 0);
152 /*
153 * 'err==len' means that all of the blocks have been preallocated,
154 * regardless of whether they have been initialized or not. To exclude
155 * unwritten extents, we need to check m_flags.
156 */
157 return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
158 }
159
ext4_write_checks(struct kiocb * iocb,struct iov_iter * from)160 static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
161 {
162 struct inode *inode = file_inode(iocb->ki_filp);
163 ssize_t ret;
164
165 ret = generic_write_checks(iocb, from);
166 if (ret <= 0)
167 return ret;
168
169 if (unlikely(IS_IMMUTABLE(inode)))
170 return -EPERM;
171
172 /*
173 * If we have encountered a bitmap-format file, the size limit
174 * is smaller than s_maxbytes, which is for extent-mapped files.
175 */
176 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
177 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
178
179 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
180 return -EFBIG;
181 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
182 }
183 return iov_iter_count(from);
184 }
185
186 #ifdef CONFIG_FS_DAX
187 static ssize_t
ext4_dax_write_iter(struct kiocb * iocb,struct iov_iter * from)188 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
189 {
190 struct inode *inode = file_inode(iocb->ki_filp);
191 ssize_t ret;
192
193 if (!inode_trylock(inode)) {
194 if (iocb->ki_flags & IOCB_NOWAIT)
195 return -EAGAIN;
196 inode_lock(inode);
197 }
198 ret = ext4_write_checks(iocb, from);
199 if (ret <= 0)
200 goto out;
201 ret = file_remove_privs(iocb->ki_filp);
202 if (ret)
203 goto out;
204 ret = file_update_time(iocb->ki_filp);
205 if (ret)
206 goto out;
207
208 ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
209 out:
210 inode_unlock(inode);
211 if (ret > 0)
212 ret = generic_write_sync(iocb, ret);
213 return ret;
214 }
215 #endif
216
217 static ssize_t
ext4_file_write_iter(struct kiocb * iocb,struct iov_iter * from)218 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
219 {
220 struct inode *inode = file_inode(iocb->ki_filp);
221 int o_direct = iocb->ki_flags & IOCB_DIRECT;
222 int unaligned_aio = 0;
223 int overwrite = 0;
224 ssize_t ret;
225
226 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
227 return -EIO;
228
229 #ifdef CONFIG_FS_DAX
230 if (IS_DAX(inode))
231 return ext4_dax_write_iter(iocb, from);
232 #endif
233
234 if (!inode_trylock(inode)) {
235 if (iocb->ki_flags & IOCB_NOWAIT)
236 return -EAGAIN;
237 inode_lock(inode);
238 }
239
240 ret = ext4_write_checks(iocb, from);
241 if (ret <= 0)
242 goto out;
243
244 /*
245 * Unaligned direct AIO must be serialized among each other as zeroing
246 * of partial blocks of two competing unaligned AIOs can result in data
247 * corruption.
248 */
249 if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
250 !is_sync_kiocb(iocb) &&
251 ext4_unaligned_aio(inode, from, iocb->ki_pos)) {
252 unaligned_aio = 1;
253 ext4_unwritten_wait(inode);
254 }
255
256 iocb->private = &overwrite;
257 /* Check whether we do a DIO overwrite or not */
258 if (o_direct && !unaligned_aio) {
259 if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {
260 if (ext4_should_dioread_nolock(inode))
261 overwrite = 1;
262 } else if (iocb->ki_flags & IOCB_NOWAIT) {
263 ret = -EAGAIN;
264 goto out;
265 }
266 }
267
268 ret = __generic_file_write_iter(iocb, from);
269 /*
270 * Unaligned direct AIO must be the only IO in flight. Otherwise
271 * overlapping aligned IO after unaligned might result in data
272 * corruption.
273 */
274 if (ret == -EIOCBQUEUED && unaligned_aio)
275 ext4_unwritten_wait(inode);
276 inode_unlock(inode);
277
278 if (ret > 0)
279 ret = generic_write_sync(iocb, ret);
280
281 return ret;
282
283 out:
284 inode_unlock(inode);
285 return ret;
286 }
287
288 #ifdef CONFIG_FS_DAX
ext4_dax_huge_fault(struct vm_fault * vmf,enum page_entry_size pe_size)289 static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
290 enum page_entry_size pe_size)
291 {
292 int error = 0;
293 vm_fault_t result;
294 int retries = 0;
295 handle_t *handle = NULL;
296 struct inode *inode = file_inode(vmf->vma->vm_file);
297 struct super_block *sb = inode->i_sb;
298
299 /*
300 * We have to distinguish real writes from writes which will result in a
301 * COW page; COW writes should *not* poke the journal (the file will not
302 * be changed). Doing so would cause unintended failures when mounted
303 * read-only.
304 *
305 * We check for VM_SHARED rather than vmf->cow_page since the latter is
306 * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
307 * other sizes, dax_iomap_fault will handle splitting / fallback so that
308 * we eventually come back with a COW page.
309 */
310 bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
311 (vmf->vma->vm_flags & VM_SHARED);
312 pfn_t pfn;
313
314 if (write) {
315 sb_start_pagefault(sb);
316 file_update_time(vmf->vma->vm_file);
317 down_read(&EXT4_I(inode)->i_mmap_sem);
318 retry:
319 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
320 EXT4_DATA_TRANS_BLOCKS(sb));
321 if (IS_ERR(handle)) {
322 up_read(&EXT4_I(inode)->i_mmap_sem);
323 sb_end_pagefault(sb);
324 return VM_FAULT_SIGBUS;
325 }
326 } else {
327 down_read(&EXT4_I(inode)->i_mmap_sem);
328 }
329 result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
330 if (write) {
331 ext4_journal_stop(handle);
332
333 if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
334 ext4_should_retry_alloc(sb, &retries))
335 goto retry;
336 /* Handling synchronous page fault? */
337 if (result & VM_FAULT_NEEDDSYNC)
338 result = dax_finish_sync_fault(vmf, pe_size, pfn);
339 up_read(&EXT4_I(inode)->i_mmap_sem);
340 sb_end_pagefault(sb);
341 } else {
342 up_read(&EXT4_I(inode)->i_mmap_sem);
343 }
344
345 return result;
346 }
347
ext4_dax_fault(struct vm_fault * vmf)348 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
349 {
350 return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
351 }
352
353 static const struct vm_operations_struct ext4_dax_vm_ops = {
354 .fault = ext4_dax_fault,
355 .huge_fault = ext4_dax_huge_fault,
356 .page_mkwrite = ext4_dax_fault,
357 .pfn_mkwrite = ext4_dax_fault,
358 };
359 #else
360 #define ext4_dax_vm_ops ext4_file_vm_ops
361 #endif
362
363 static const struct vm_operations_struct ext4_file_vm_ops = {
364 .fault = ext4_filemap_fault,
365 .map_pages = filemap_map_pages,
366 .page_mkwrite = ext4_page_mkwrite,
367 };
368
ext4_file_mmap(struct file * file,struct vm_area_struct * vma)369 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
370 {
371 struct inode *inode = file->f_mapping->host;
372 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
373 struct dax_device *dax_dev = sbi->s_daxdev;
374
375 if (unlikely(ext4_forced_shutdown(sbi)))
376 return -EIO;
377
378 /*
379 * We don't support synchronous mappings for non-DAX files and
380 * for DAX files if underneath dax_device is not synchronous.
381 */
382 if (!daxdev_mapping_supported(vma, dax_dev))
383 return -EOPNOTSUPP;
384
385 file_accessed(file);
386 if (IS_DAX(file_inode(file))) {
387 vma->vm_ops = &ext4_dax_vm_ops;
388 vma->vm_flags |= VM_HUGEPAGE;
389 } else {
390 vma->vm_ops = &ext4_file_vm_ops;
391 }
392 return 0;
393 }
394
ext4_sample_last_mounted(struct super_block * sb,struct vfsmount * mnt)395 static int ext4_sample_last_mounted(struct super_block *sb,
396 struct vfsmount *mnt)
397 {
398 struct ext4_sb_info *sbi = EXT4_SB(sb);
399 struct path path;
400 char buf[64], *cp;
401 handle_t *handle;
402 int err;
403
404 if (likely(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED))
405 return 0;
406
407 if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
408 return 0;
409
410 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
411 /*
412 * Sample where the filesystem has been mounted and
413 * store it in the superblock for sysadmin convenience
414 * when trying to sort through large numbers of block
415 * devices or filesystem images.
416 */
417 memset(buf, 0, sizeof(buf));
418 path.mnt = mnt;
419 path.dentry = mnt->mnt_root;
420 cp = d_path(&path, buf, sizeof(buf));
421 err = 0;
422 if (IS_ERR(cp))
423 goto out;
424
425 handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
426 err = PTR_ERR(handle);
427 if (IS_ERR(handle))
428 goto out;
429 BUFFER_TRACE(sbi->s_sbh, "get_write_access");
430 err = ext4_journal_get_write_access(handle, sbi->s_sbh);
431 if (err)
432 goto out_journal;
433 strlcpy(sbi->s_es->s_last_mounted, cp,
434 sizeof(sbi->s_es->s_last_mounted));
435 ext4_handle_dirty_super(handle, sb);
436 out_journal:
437 ext4_journal_stop(handle);
438 out:
439 sb_end_intwrite(sb);
440 return err;
441 }
442
ext4_file_open(struct inode * inode,struct file * filp)443 static int ext4_file_open(struct inode * inode, struct file * filp)
444 {
445 int ret;
446
447 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
448 return -EIO;
449
450 ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
451 if (ret)
452 return ret;
453
454 ret = fscrypt_file_open(inode, filp);
455 if (ret)
456 return ret;
457
458 ret = fsverity_file_open(inode, filp);
459 if (ret)
460 return ret;
461
462 /*
463 * Set up the jbd2_inode if we are opening the inode for
464 * writing and the journal is present
465 */
466 if (filp->f_mode & FMODE_WRITE) {
467 ret = ext4_inode_attach_jinode(inode);
468 if (ret < 0)
469 return ret;
470 }
471
472 filp->f_mode |= FMODE_NOWAIT;
473 return dquot_file_open(inode, filp);
474 }
475
476 /*
477 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
478 * by calling generic_file_llseek_size() with the appropriate maxbytes
479 * value for each.
480 */
ext4_llseek(struct file * file,loff_t offset,int whence)481 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
482 {
483 struct inode *inode = file->f_mapping->host;
484 loff_t maxbytes;
485
486 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
487 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
488 else
489 maxbytes = inode->i_sb->s_maxbytes;
490
491 switch (whence) {
492 default:
493 return generic_file_llseek_size(file, offset, whence,
494 maxbytes, i_size_read(inode));
495 case SEEK_HOLE:
496 inode_lock_shared(inode);
497 offset = iomap_seek_hole(inode, offset, &ext4_iomap_ops);
498 inode_unlock_shared(inode);
499 break;
500 case SEEK_DATA:
501 inode_lock_shared(inode);
502 offset = iomap_seek_data(inode, offset, &ext4_iomap_ops);
503 inode_unlock_shared(inode);
504 break;
505 }
506
507 if (offset < 0)
508 return offset;
509 return vfs_setpos(file, offset, maxbytes);
510 }
511
512 const struct file_operations ext4_file_operations = {
513 .llseek = ext4_llseek,
514 .read_iter = ext4_file_read_iter,
515 .write_iter = ext4_file_write_iter,
516 .unlocked_ioctl = ext4_ioctl,
517 #ifdef CONFIG_COMPAT
518 .compat_ioctl = ext4_compat_ioctl,
519 #endif
520 .mmap = ext4_file_mmap,
521 .mmap_supported_flags = MAP_SYNC,
522 .open = ext4_file_open,
523 .release = ext4_release_file,
524 .fsync = ext4_sync_file,
525 .get_unmapped_area = thp_get_unmapped_area,
526 .splice_read = generic_file_splice_read,
527 .splice_write = iter_file_splice_write,
528 .fallocate = ext4_fallocate,
529 };
530
531 const struct inode_operations ext4_file_inode_operations = {
532 .setattr = ext4_setattr,
533 .getattr = ext4_file_getattr,
534 .listxattr = ext4_listxattr,
535 .get_acl = ext4_get_acl,
536 .set_acl = ext4_set_acl,
537 .fiemap = ext4_fiemap,
538 };
539
540