xref: /linux/fs/9p/vfs_file.c (revision 3a07362fab1653d3aca31a9155c8cc776138fd02)
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->c.flc_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 	struct v9fs_session_info *v9ses;
125 
126 	fid = filp->private_data;
127 	BUG_ON(fid == NULL);
128 
129 	BUG_ON((fl->c.flc_flags & FL_POSIX) != FL_POSIX);
130 
131 	res = locks_lock_file_wait(filp, fl);
132 	if (res < 0)
133 		goto out;
134 
135 	/* convert posix lock to p9 tlock args */
136 	memset(&flock, 0, sizeof(flock));
137 	/* map the lock type */
138 	switch (fl->c.flc_type) {
139 	case F_RDLCK:
140 		flock.type = P9_LOCK_TYPE_RDLCK;
141 		break;
142 	case F_WRLCK:
143 		flock.type = P9_LOCK_TYPE_WRLCK;
144 		break;
145 	case F_UNLCK:
146 		flock.type = P9_LOCK_TYPE_UNLCK;
147 		break;
148 	}
149 	flock.start = fl->fl_start;
150 	if (fl->fl_end == OFFSET_MAX)
151 		flock.length = 0;
152 	else
153 		flock.length = fl->fl_end - fl->fl_start + 1;
154 	flock.proc_id = fl->c.flc_pid;
155 	flock.client_id = fid->clnt->name;
156 	if (IS_SETLKW(cmd))
157 		flock.flags = P9_LOCK_FLAGS_BLOCK;
158 
159 	v9ses = v9fs_inode2v9ses(file_inode(filp));
160 
161 	/*
162 	 * if its a blocked request and we get P9_LOCK_BLOCKED as the status
163 	 * for lock request, keep on trying
164 	 */
165 	for (;;) {
166 		res = p9_client_lock_dotl(fid, &flock, &status);
167 		if (res < 0)
168 			goto out_unlock;
169 
170 		if (status != P9_LOCK_BLOCKED)
171 			break;
172 		if (status == P9_LOCK_BLOCKED && !IS_SETLKW(cmd))
173 			break;
174 		if (schedule_timeout_interruptible(v9ses->session_lock_timeout)
175 				!= 0)
176 			break;
177 		/*
178 		 * p9_client_lock_dotl overwrites flock.client_id with the
179 		 * server message, free and reuse the client name
180 		 */
181 		if (flock.client_id != fid->clnt->name) {
182 			kfree(flock.client_id);
183 			flock.client_id = fid->clnt->name;
184 		}
185 	}
186 
187 	/* map 9p status to VFS status */
188 	switch (status) {
189 	case P9_LOCK_SUCCESS:
190 		res = 0;
191 		break;
192 	case P9_LOCK_BLOCKED:
193 		res = -EAGAIN;
194 		break;
195 	default:
196 		WARN_ONCE(1, "unknown lock status code: %d\n", status);
197 		fallthrough;
198 	case P9_LOCK_ERROR:
199 	case P9_LOCK_GRACE:
200 		res = -ENOLCK;
201 		break;
202 	}
203 
204 out_unlock:
205 	/*
206 	 * incase server returned error for lock request, revert
207 	 * it locally
208 	 */
209 	if (res < 0 && fl->c.flc_type != F_UNLCK) {
210 		unsigned char type = fl->c.flc_type;
211 
212 		fl->c.flc_type = F_UNLCK;
213 		/* Even if this fails we want to return the remote error */
214 		locks_lock_file_wait(filp, fl);
215 		fl->c.flc_type = 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->c.flc_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->c.flc_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->c.flc_type = F_RDLCK;
258 		break;
259 	case P9_LOCK_TYPE_WRLCK:
260 		fl->c.flc_type = F_WRLCK;
261 		break;
262 	case P9_LOCK_TYPE_UNLCK:
263 		fl->c.flc_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->c.flc_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->c.flc_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->c.flc_flags & FL_FLOCK))
328 		goto out_err;
329 
330 	if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->c.flc_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->c.flc_flags |= FL_POSIX;
336 	fl->c.flc_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 
357 	p9_debug(P9_DEBUG_VFS, "fid %d count %zu offset %lld\n",
358 		 fid->fid, iov_iter_count(to), iocb->ki_pos);
359 
360 	if (fid->mode & P9L_DIRECT)
361 		return netfs_unbuffered_read_iter(iocb, to);
362 
363 	p9_debug(P9_DEBUG_VFS, "(cached)\n");
364 	return netfs_file_read_iter(iocb, to);
365 }
366 
367 /*
368  * v9fs_file_splice_read - splice-read from a file
369  * @in: The 9p file to read from
370  * @ppos: Where to find/update the file position
371  * @pipe: The pipe to splice into
372  * @len: The maximum amount of data to splice
373  * @flags: SPLICE_F_* flags
374  */
v9fs_file_splice_read(struct file * in,loff_t * ppos,struct pipe_inode_info * pipe,size_t len,unsigned int flags)375 static ssize_t v9fs_file_splice_read(struct file *in, loff_t *ppos,
376 				     struct pipe_inode_info *pipe,
377 				     size_t len, unsigned int flags)
378 {
379 	struct p9_fid *fid = in->private_data;
380 
381 	p9_debug(P9_DEBUG_VFS, "fid %d count %zu offset %lld\n",
382 		 fid->fid, len, *ppos);
383 
384 	if (fid->mode & P9L_DIRECT)
385 		return copy_splice_read(in, ppos, pipe, len, flags);
386 	return filemap_splice_read(in, ppos, pipe, len, flags);
387 }
388 
389 /**
390  * v9fs_file_write_iter - write to a file
391  * @iocb: The operation parameters
392  * @from: The data to write
393  *
394  */
395 static ssize_t
v9fs_file_write_iter(struct kiocb * iocb,struct iov_iter * from)396 v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
397 {
398 	struct file *file = iocb->ki_filp;
399 	struct p9_fid *fid = file->private_data;
400 
401 	p9_debug(P9_DEBUG_VFS, "fid %d\n", fid->fid);
402 
403 	if (fid->mode & (P9L_DIRECT | P9L_NOWRITECACHE))
404 		return netfs_unbuffered_write_iter(iocb, from);
405 
406 	p9_debug(P9_DEBUG_CACHE, "(cached)\n");
407 	return netfs_file_write_iter(iocb, from);
408 }
409 
v9fs_file_fsync(struct file * filp,loff_t start,loff_t end,int datasync)410 static int v9fs_file_fsync(struct file *filp, loff_t start, loff_t end,
411 			   int datasync)
412 {
413 	struct p9_fid *fid;
414 	struct inode *inode = filp->f_mapping->host;
415 	struct p9_wstat wstat;
416 	int retval;
417 
418 	retval = file_write_and_wait_range(filp, start, end);
419 	if (retval)
420 		return retval;
421 
422 	inode_lock(inode);
423 	p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
424 
425 	fid = filp->private_data;
426 	v9fs_blank_wstat(&wstat);
427 
428 	retval = p9_client_wstat(fid, &wstat);
429 	inode_unlock(inode);
430 
431 	return retval;
432 }
433 
v9fs_file_fsync_dotl(struct file * filp,loff_t start,loff_t end,int datasync)434 int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
435 			 int datasync)
436 {
437 	struct p9_fid *fid;
438 	struct inode *inode = filp->f_mapping->host;
439 	int retval;
440 
441 	retval = file_write_and_wait_range(filp, start, end);
442 	if (retval)
443 		return retval;
444 
445 	inode_lock(inode);
446 	p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
447 
448 	fid = filp->private_data;
449 
450 	retval = p9_client_fsync(fid, datasync);
451 	inode_unlock(inode);
452 
453 	return retval;
454 }
455 
456 static int
v9fs_file_mmap(struct file * filp,struct vm_area_struct * vma)457 v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
458 {
459 	int retval;
460 	struct inode *inode = file_inode(filp);
461 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
462 
463 	p9_debug(P9_DEBUG_MMAP, "filp :%p\n", filp);
464 
465 	if (!(v9ses->cache & CACHE_WRITEBACK)) {
466 		p9_debug(P9_DEBUG_CACHE, "(read-only mmap mode)");
467 		return generic_file_readonly_mmap(filp, vma);
468 	}
469 
470 	retval = generic_file_mmap(filp, vma);
471 	if (!retval)
472 		vma->vm_ops = &v9fs_mmap_file_vm_ops;
473 
474 	return retval;
475 }
476 
477 static vm_fault_t
v9fs_vm_page_mkwrite(struct vm_fault * vmf)478 v9fs_vm_page_mkwrite(struct vm_fault *vmf)
479 {
480 	return netfs_page_mkwrite(vmf, NULL);
481 }
482 
v9fs_mmap_vm_close(struct vm_area_struct * vma)483 static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
484 {
485 	struct inode *inode;
486 
487 	struct writeback_control wbc = {
488 		.nr_to_write = LONG_MAX,
489 		.sync_mode = WB_SYNC_ALL,
490 		.range_start = (loff_t)vma->vm_pgoff * PAGE_SIZE,
491 		 /* absolute end, byte at end included */
492 		.range_end = (loff_t)vma->vm_pgoff * PAGE_SIZE +
493 			(vma->vm_end - vma->vm_start - 1),
494 	};
495 
496 	if (!(vma->vm_flags & VM_SHARED))
497 		return;
498 
499 	p9_debug(P9_DEBUG_VFS, "9p VMA close, %p, flushing", vma);
500 
501 	inode = file_inode(vma->vm_file);
502 	filemap_fdatawrite_wbc(inode->i_mapping, &wbc);
503 }
504 
505 static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
506 	.close = v9fs_mmap_vm_close,
507 	.fault = filemap_fault,
508 	.map_pages = filemap_map_pages,
509 	.page_mkwrite = v9fs_vm_page_mkwrite,
510 };
511 
512 const struct file_operations v9fs_file_operations = {
513 	.llseek = generic_file_llseek,
514 	.read_iter = v9fs_file_read_iter,
515 	.write_iter = v9fs_file_write_iter,
516 	.open = v9fs_file_open,
517 	.release = v9fs_dir_release,
518 	.lock = v9fs_file_lock,
519 	.mmap = generic_file_readonly_mmap,
520 	.splice_read = v9fs_file_splice_read,
521 	.splice_write = iter_file_splice_write,
522 	.fsync = v9fs_file_fsync,
523 	.setlease = simple_nosetlease,
524 };
525 
526 const struct file_operations v9fs_file_operations_dotl = {
527 	.llseek = generic_file_llseek,
528 	.read_iter = v9fs_file_read_iter,
529 	.write_iter = v9fs_file_write_iter,
530 	.open = v9fs_file_open,
531 	.release = v9fs_dir_release,
532 	.lock = v9fs_file_lock_dotl,
533 	.flock = v9fs_file_flock_dotl,
534 	.mmap = v9fs_file_mmap,
535 	.splice_read = v9fs_file_splice_read,
536 	.splice_write = iter_file_splice_write,
537 	.fsync = v9fs_file_fsync_dotl,
538 	.setlease = simple_nosetlease,
539 };
540