1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * This file contians vfs file ops for 9P2000.
4 *
5 * Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
6 * Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
7 */
8
9 #include <linux/module.h>
10 #include <linux/errno.h>
11 #include <linux/fs.h>
12 #include <linux/filelock.h>
13 #include <linux/sched.h>
14 #include <linux/file.h>
15 #include <linux/stat.h>
16 #include <linux/string.h>
17 #include <linux/list.h>
18 #include <linux/pagemap.h>
19 #include <linux/utsname.h>
20 #include <linux/uaccess.h>
21 #include <linux/uio.h>
22 #include <linux/slab.h>
23 #include <net/9p/9p.h>
24 #include <net/9p/client.h>
25
26 #include "v9fs.h"
27 #include "v9fs_vfs.h"
28 #include "fid.h"
29 #include "cache.h"
30
31 static const struct vm_operations_struct v9fs_mmap_file_vm_ops;
32
33 /**
34 * v9fs_file_open - open a file (or directory)
35 * @inode: inode to be opened
36 * @file: file being opened
37 *
38 */
39
v9fs_file_open(struct inode * inode,struct file * file)40 int v9fs_file_open(struct inode *inode, struct file *file)
41 {
42 int err;
43 struct v9fs_session_info *v9ses;
44 struct p9_fid *fid;
45 int omode;
46
47 p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, file);
48 v9ses = v9fs_inode2v9ses(inode);
49 if (v9fs_proto_dotl(v9ses))
50 omode = v9fs_open_to_dotl_flags(file->f_flags);
51 else
52 omode = v9fs_uflags2omode(file->f_flags,
53 v9fs_proto_dotu(v9ses));
54 fid = file->private_data;
55 if (!fid) {
56 fid = v9fs_fid_clone(file_dentry(file));
57 if (IS_ERR(fid))
58 return PTR_ERR(fid);
59
60 if ((v9ses->cache & CACHE_WRITEBACK) && (omode & P9_OWRITE)) {
61 int writeback_omode = (omode & ~P9_OWRITE) | P9_ORDWR;
62
63 p9_debug(P9_DEBUG_CACHE, "write-only file with writeback enabled, try opening O_RDWR\n");
64 err = p9_client_open(fid, writeback_omode);
65 if (err < 0) {
66 p9_debug(P9_DEBUG_CACHE, "could not open O_RDWR, disabling caches\n");
67 err = p9_client_open(fid, omode);
68 fid->mode |= P9L_DIRECT;
69 }
70 } else {
71 err = p9_client_open(fid, omode);
72 }
73 if (err < 0) {
74 p9_fid_put(fid);
75 return err;
76 }
77 if ((file->f_flags & O_APPEND) &&
78 (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)))
79 generic_file_llseek(file, 0, SEEK_END);
80
81 file->private_data = fid;
82 }
83
84 #ifdef CONFIG_9P_FSCACHE
85 if (v9ses->cache & CACHE_FSCACHE)
86 fscache_use_cookie(v9fs_inode_cookie(V9FS_I(inode)),
87 file->f_mode & FMODE_WRITE);
88 #endif
89 v9fs_fid_add_modes(fid, v9ses->flags, v9ses->cache, file->f_flags);
90 v9fs_open_fid_add(inode, &fid);
91 return 0;
92 }
93
94 /**
95 * v9fs_file_lock - lock a file (or directory)
96 * @filp: file to be locked
97 * @cmd: lock command
98 * @fl: file lock structure
99 *
100 * Bugs: this looks like a local only lock, we should extend into 9P
101 * by using open exclusive
102 */
103
v9fs_file_lock(struct file * filp,int cmd,struct file_lock * fl)104 static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
105 {
106 struct inode *inode = file_inode(filp);
107
108 p9_debug(P9_DEBUG_VFS, "filp: %p lock: %p\n", filp, fl);
109
110 if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
111 filemap_write_and_wait(inode->i_mapping);
112 invalidate_mapping_pages(&inode->i_data, 0, -1);
113 }
114
115 return 0;
116 }
117
v9fs_file_do_lock(struct file * filp,int cmd,struct file_lock * fl)118 static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
119 {
120 struct p9_flock flock;
121 struct p9_fid *fid;
122 uint8_t status = P9_LOCK_ERROR;
123 int res = 0;
124 unsigned char fl_type;
125 struct v9fs_session_info *v9ses;
126
127 fid = filp->private_data;
128 BUG_ON(fid == NULL);
129
130 BUG_ON((fl->fl_flags & FL_POSIX) != FL_POSIX);
131
132 res = locks_lock_file_wait(filp, fl);
133 if (res < 0)
134 goto out;
135
136 /* convert posix lock to p9 tlock args */
137 memset(&flock, 0, sizeof(flock));
138 /* map the lock type */
139 switch (fl->fl_type) {
140 case F_RDLCK:
141 flock.type = P9_LOCK_TYPE_RDLCK;
142 break;
143 case F_WRLCK:
144 flock.type = P9_LOCK_TYPE_WRLCK;
145 break;
146 case F_UNLCK:
147 flock.type = P9_LOCK_TYPE_UNLCK;
148 break;
149 }
150 flock.start = fl->fl_start;
151 if (fl->fl_end == OFFSET_MAX)
152 flock.length = 0;
153 else
154 flock.length = fl->fl_end - fl->fl_start + 1;
155 flock.proc_id = fl->fl_pid;
156 flock.client_id = fid->clnt->name;
157 if (IS_SETLKW(cmd))
158 flock.flags = P9_LOCK_FLAGS_BLOCK;
159
160 v9ses = v9fs_inode2v9ses(file_inode(filp));
161
162 /*
163 * if its a blocked request and we get P9_LOCK_BLOCKED as the status
164 * for lock request, keep on trying
165 */
166 for (;;) {
167 res = p9_client_lock_dotl(fid, &flock, &status);
168 if (res < 0)
169 goto out_unlock;
170
171 if (status != P9_LOCK_BLOCKED)
172 break;
173 if (status == P9_LOCK_BLOCKED && !IS_SETLKW(cmd))
174 break;
175 if (schedule_timeout_interruptible(v9ses->session_lock_timeout)
176 != 0)
177 break;
178 /*
179 * p9_client_lock_dotl overwrites flock.client_id with the
180 * server message, free and reuse the client name
181 */
182 if (flock.client_id != fid->clnt->name) {
183 kfree(flock.client_id);
184 flock.client_id = fid->clnt->name;
185 }
186 }
187
188 /* map 9p status to VFS status */
189 switch (status) {
190 case P9_LOCK_SUCCESS:
191 res = 0;
192 break;
193 case P9_LOCK_BLOCKED:
194 res = -EAGAIN;
195 break;
196 default:
197 WARN_ONCE(1, "unknown lock status code: %d\n", status);
198 fallthrough;
199 case P9_LOCK_ERROR:
200 case P9_LOCK_GRACE:
201 res = -ENOLCK;
202 break;
203 }
204
205 out_unlock:
206 /*
207 * incase server returned error for lock request, revert
208 * it locally
209 */
210 if (res < 0 && fl->fl_type != F_UNLCK) {
211 fl_type = fl->fl_type;
212 fl->fl_type = F_UNLCK;
213 /* Even if this fails we want to return the remote error */
214 locks_lock_file_wait(filp, fl);
215 fl->fl_type = fl_type;
216 }
217 if (flock.client_id != fid->clnt->name)
218 kfree(flock.client_id);
219 out:
220 return res;
221 }
222
v9fs_file_getlock(struct file * filp,struct file_lock * fl)223 static int v9fs_file_getlock(struct file *filp, struct file_lock *fl)
224 {
225 struct p9_getlock glock;
226 struct p9_fid *fid;
227 int res = 0;
228
229 fid = filp->private_data;
230 BUG_ON(fid == NULL);
231
232 posix_test_lock(filp, fl);
233 /*
234 * if we have a conflicting lock locally, no need to validate
235 * with server
236 */
237 if (fl->fl_type != F_UNLCK)
238 return res;
239
240 /* convert posix lock to p9 tgetlock args */
241 memset(&glock, 0, sizeof(glock));
242 glock.type = P9_LOCK_TYPE_UNLCK;
243 glock.start = fl->fl_start;
244 if (fl->fl_end == OFFSET_MAX)
245 glock.length = 0;
246 else
247 glock.length = fl->fl_end - fl->fl_start + 1;
248 glock.proc_id = fl->fl_pid;
249 glock.client_id = fid->clnt->name;
250
251 res = p9_client_getlock_dotl(fid, &glock);
252 if (res < 0)
253 goto out;
254 /* map 9p lock type to os lock type */
255 switch (glock.type) {
256 case P9_LOCK_TYPE_RDLCK:
257 fl->fl_type = F_RDLCK;
258 break;
259 case P9_LOCK_TYPE_WRLCK:
260 fl->fl_type = F_WRLCK;
261 break;
262 case P9_LOCK_TYPE_UNLCK:
263 fl->fl_type = F_UNLCK;
264 break;
265 }
266 if (glock.type != P9_LOCK_TYPE_UNLCK) {
267 fl->fl_start = glock.start;
268 if (glock.length == 0)
269 fl->fl_end = OFFSET_MAX;
270 else
271 fl->fl_end = glock.start + glock.length - 1;
272 fl->fl_pid = -glock.proc_id;
273 }
274 out:
275 if (glock.client_id != fid->clnt->name)
276 kfree(glock.client_id);
277 return res;
278 }
279
280 /**
281 * v9fs_file_lock_dotl - lock a file (or directory)
282 * @filp: file to be locked
283 * @cmd: lock command
284 * @fl: file lock structure
285 *
286 */
287
v9fs_file_lock_dotl(struct file * filp,int cmd,struct file_lock * fl)288 static int v9fs_file_lock_dotl(struct file *filp, int cmd, struct file_lock *fl)
289 {
290 struct inode *inode = file_inode(filp);
291 int ret = -ENOLCK;
292
293 p9_debug(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %pD\n",
294 filp, cmd, fl, filp);
295
296 if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
297 filemap_write_and_wait(inode->i_mapping);
298 invalidate_mapping_pages(&inode->i_data, 0, -1);
299 }
300
301 if (IS_SETLK(cmd) || IS_SETLKW(cmd))
302 ret = v9fs_file_do_lock(filp, cmd, fl);
303 else if (IS_GETLK(cmd))
304 ret = v9fs_file_getlock(filp, fl);
305 else
306 ret = -EINVAL;
307 return ret;
308 }
309
310 /**
311 * v9fs_file_flock_dotl - lock a file
312 * @filp: file to be locked
313 * @cmd: lock command
314 * @fl: file lock structure
315 *
316 */
317
v9fs_file_flock_dotl(struct file * filp,int cmd,struct file_lock * fl)318 static int v9fs_file_flock_dotl(struct file *filp, int cmd,
319 struct file_lock *fl)
320 {
321 struct inode *inode = file_inode(filp);
322 int ret = -ENOLCK;
323
324 p9_debug(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %pD\n",
325 filp, cmd, fl, filp);
326
327 if (!(fl->fl_flags & FL_FLOCK))
328 goto out_err;
329
330 if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
331 filemap_write_and_wait(inode->i_mapping);
332 invalidate_mapping_pages(&inode->i_data, 0, -1);
333 }
334 /* Convert flock to posix lock */
335 fl->fl_flags |= FL_POSIX;
336 fl->fl_flags ^= FL_FLOCK;
337
338 if (IS_SETLK(cmd) | IS_SETLKW(cmd))
339 ret = v9fs_file_do_lock(filp, cmd, fl);
340 else
341 ret = -EINVAL;
342 out_err:
343 return ret;
344 }
345
346 /**
347 * v9fs_file_read_iter - read from a file
348 * @iocb: The operation parameters
349 * @to: The buffer to read into
350 *
351 */
352 static ssize_t
v9fs_file_read_iter(struct kiocb * iocb,struct iov_iter * to)353 v9fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
354 {
355 struct p9_fid *fid = iocb->ki_filp->private_data;
356 int ret, err = 0;
357
358 p9_debug(P9_DEBUG_VFS, "fid %d count %zu offset %lld\n",
359 fid->fid, iov_iter_count(to), iocb->ki_pos);
360
361 if (!(fid->mode & P9L_DIRECT)) {
362 p9_debug(P9_DEBUG_VFS, "(cached)\n");
363 return generic_file_read_iter(iocb, to);
364 }
365
366 if (iocb->ki_filp->f_flags & O_NONBLOCK)
367 ret = p9_client_read_once(fid, iocb->ki_pos, to, &err);
368 else
369 ret = p9_client_read(fid, iocb->ki_pos, to, &err);
370 if (!ret)
371 return err;
372
373 iocb->ki_pos += ret;
374 return ret;
375 }
376
377 /*
378 * v9fs_file_splice_read - splice-read from a file
379 * @in: The 9p file to read from
380 * @ppos: Where to find/update the file position
381 * @pipe: The pipe to splice into
382 * @len: The maximum amount of data to splice
383 * @flags: SPLICE_F_* flags
384 */
v9fs_file_splice_read(struct file * in,loff_t * ppos,struct pipe_inode_info * pipe,size_t len,unsigned int flags)385 static ssize_t v9fs_file_splice_read(struct file *in, loff_t *ppos,
386 struct pipe_inode_info *pipe,
387 size_t len, unsigned int flags)
388 {
389 struct p9_fid *fid = in->private_data;
390
391 p9_debug(P9_DEBUG_VFS, "fid %d count %zu offset %lld\n",
392 fid->fid, len, *ppos);
393
394 if (fid->mode & P9L_DIRECT)
395 return copy_splice_read(in, ppos, pipe, len, flags);
396 return filemap_splice_read(in, ppos, pipe, len, flags);
397 }
398
399 /**
400 * v9fs_file_write_iter - write to a file
401 * @iocb: The operation parameters
402 * @from: The data to write
403 *
404 */
405 static ssize_t
v9fs_file_write_iter(struct kiocb * iocb,struct iov_iter * from)406 v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
407 {
408 struct file *file = iocb->ki_filp;
409 struct p9_fid *fid = file->private_data;
410 ssize_t retval;
411 loff_t origin;
412 int err = 0;
413
414 p9_debug(P9_DEBUG_VFS, "fid %d\n", fid->fid);
415
416 if (!(fid->mode & (P9L_DIRECT | P9L_NOWRITECACHE))) {
417 p9_debug(P9_DEBUG_CACHE, "(cached)\n");
418 return generic_file_write_iter(iocb, from);
419 }
420
421 retval = generic_write_checks(iocb, from);
422 if (retval <= 0)
423 return retval;
424
425 origin = iocb->ki_pos;
426 retval = p9_client_write(file->private_data, iocb->ki_pos, from, &err);
427 if (retval > 0) {
428 struct inode *inode = file_inode(file);
429 loff_t i_size;
430 unsigned long pg_start, pg_end;
431
432 pg_start = origin >> PAGE_SHIFT;
433 pg_end = (origin + retval - 1) >> PAGE_SHIFT;
434 if (inode->i_mapping && inode->i_mapping->nrpages)
435 invalidate_inode_pages2_range(inode->i_mapping,
436 pg_start, pg_end);
437 iocb->ki_pos += retval;
438 i_size = i_size_read(inode);
439 if (iocb->ki_pos > i_size) {
440 inode_add_bytes(inode, iocb->ki_pos - i_size);
441 /*
442 * Need to serialize against i_size_write() in
443 * v9fs_stat2inode()
444 */
445 v9fs_i_size_write(inode, iocb->ki_pos);
446 }
447 return retval;
448 }
449 return err;
450 }
451
v9fs_file_fsync(struct file * filp,loff_t start,loff_t end,int datasync)452 static int v9fs_file_fsync(struct file *filp, loff_t start, loff_t end,
453 int datasync)
454 {
455 struct p9_fid *fid;
456 struct inode *inode = filp->f_mapping->host;
457 struct p9_wstat wstat;
458 int retval;
459
460 retval = file_write_and_wait_range(filp, start, end);
461 if (retval)
462 return retval;
463
464 inode_lock(inode);
465 p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
466
467 fid = filp->private_data;
468 v9fs_blank_wstat(&wstat);
469
470 retval = p9_client_wstat(fid, &wstat);
471 inode_unlock(inode);
472
473 return retval;
474 }
475
v9fs_file_fsync_dotl(struct file * filp,loff_t start,loff_t end,int datasync)476 int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
477 int datasync)
478 {
479 struct p9_fid *fid;
480 struct inode *inode = filp->f_mapping->host;
481 int retval;
482
483 retval = file_write_and_wait_range(filp, start, end);
484 if (retval)
485 return retval;
486
487 inode_lock(inode);
488 p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
489
490 fid = filp->private_data;
491
492 retval = p9_client_fsync(fid, datasync);
493 inode_unlock(inode);
494
495 return retval;
496 }
497
498 static int
v9fs_file_mmap(struct file * filp,struct vm_area_struct * vma)499 v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
500 {
501 int retval;
502 struct inode *inode = file_inode(filp);
503 struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
504
505 p9_debug(P9_DEBUG_MMAP, "filp :%p\n", filp);
506
507 if (!(v9ses->cache & CACHE_WRITEBACK)) {
508 p9_debug(P9_DEBUG_CACHE, "(read-only mmap mode)");
509 return generic_file_readonly_mmap(filp, vma);
510 }
511
512 retval = generic_file_mmap(filp, vma);
513 if (!retval)
514 vma->vm_ops = &v9fs_mmap_file_vm_ops;
515
516 return retval;
517 }
518
519 static vm_fault_t
v9fs_vm_page_mkwrite(struct vm_fault * vmf)520 v9fs_vm_page_mkwrite(struct vm_fault *vmf)
521 {
522 struct folio *folio = page_folio(vmf->page);
523 struct file *filp = vmf->vma->vm_file;
524 struct inode *inode = file_inode(filp);
525
526
527 p9_debug(P9_DEBUG_VFS, "folio %p fid %lx\n",
528 folio, (unsigned long)filp->private_data);
529
530 /* Wait for the page to be written to the cache before we allow it to
531 * be modified. We then assume the entire page will need writing back.
532 */
533 #ifdef CONFIG_9P_FSCACHE
534 if (folio_test_fscache(folio) &&
535 folio_wait_fscache_killable(folio) < 0)
536 return VM_FAULT_NOPAGE;
537 #endif
538
539 /* Update file times before taking page lock */
540 file_update_time(filp);
541
542 if (folio_lock_killable(folio) < 0)
543 return VM_FAULT_RETRY;
544 if (folio_mapping(folio) != inode->i_mapping)
545 goto out_unlock;
546 folio_wait_stable(folio);
547
548 return VM_FAULT_LOCKED;
549 out_unlock:
550 folio_unlock(folio);
551 return VM_FAULT_NOPAGE;
552 }
553
v9fs_mmap_vm_close(struct vm_area_struct * vma)554 static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
555 {
556 struct inode *inode;
557
558 struct writeback_control wbc = {
559 .nr_to_write = LONG_MAX,
560 .sync_mode = WB_SYNC_ALL,
561 .range_start = (loff_t)vma->vm_pgoff * PAGE_SIZE,
562 /* absolute end, byte at end included */
563 .range_end = (loff_t)vma->vm_pgoff * PAGE_SIZE +
564 (vma->vm_end - vma->vm_start - 1),
565 };
566
567 if (!(vma->vm_flags & VM_SHARED))
568 return;
569
570 p9_debug(P9_DEBUG_VFS, "9p VMA close, %p, flushing", vma);
571
572 inode = file_inode(vma->vm_file);
573 filemap_fdatawrite_wbc(inode->i_mapping, &wbc);
574 }
575
576 static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
577 .close = v9fs_mmap_vm_close,
578 .fault = filemap_fault,
579 .map_pages = filemap_map_pages,
580 .page_mkwrite = v9fs_vm_page_mkwrite,
581 };
582
583 const struct file_operations v9fs_file_operations = {
584 .llseek = generic_file_llseek,
585 .read_iter = v9fs_file_read_iter,
586 .write_iter = v9fs_file_write_iter,
587 .open = v9fs_file_open,
588 .release = v9fs_dir_release,
589 .lock = v9fs_file_lock,
590 .mmap = generic_file_readonly_mmap,
591 .splice_read = v9fs_file_splice_read,
592 .splice_write = iter_file_splice_write,
593 .fsync = v9fs_file_fsync,
594 .setlease = simple_nosetlease,
595 };
596
597 const struct file_operations v9fs_file_operations_dotl = {
598 .llseek = generic_file_llseek,
599 .read_iter = v9fs_file_read_iter,
600 .write_iter = v9fs_file_write_iter,
601 .open = v9fs_file_open,
602 .release = v9fs_dir_release,
603 .lock = v9fs_file_lock_dotl,
604 .flock = v9fs_file_flock_dotl,
605 .mmap = v9fs_file_mmap,
606 .splice_read = v9fs_file_splice_read,
607 .splice_write = iter_file_splice_write,
608 .fsync = v9fs_file_fsync_dotl,
609 .setlease = simple_nosetlease,
610 };
611