Bootlin

Embedded Linux Experts

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/uaccess.h>

#include <linux/fs.h>
#include <linux/pagemap.h>

#define DEBUG_SUBSYSTEM S_LLITE

#include "../include/lustre_lite.h"
#include "llite_internal.h"
#include "../include/linux/lustre_compat25.h"

static const struct vm_operations_struct ll_file_vm_ops;

void policy_from_vma(ldlm_policy_data_t *policy,
		     struct vm_area_struct *vma, unsigned long addr,
		     size_t count)
{
	policy->l_extent.start = ((addr - vma->vm_start) & PAGE_MASK) +
				 (vma->vm_pgoff << PAGE_SHIFT);
	policy->l_extent.end = (policy->l_extent.start + count - 1) |
			       ~PAGE_MASK;
}

struct vm_area_struct *our_vma(struct mm_struct *mm, unsigned long addr,
			       size_t count)
{
	struct vm_area_struct *vma, *ret = NULL;

	/* mmap_sem must have been held by caller. */
	LASSERT(!down_write_trylock(&mm->mmap_sem));

	for (vma = find_vma(mm, addr);
	    vma && vma->vm_start < (addr + count); vma = vma->vm_next) {
		if (vma->vm_ops && vma->vm_ops == &ll_file_vm_ops &&
		    vma->vm_flags & VM_SHARED) {
			ret = vma;
			break;
		}
	}
	return ret;
}

/**
 * API independent part for page fault initialization.
 * \param vma - virtual memory area addressed to page fault
 * \param env - corespondent lu_env to processing
 * \param nest - nested level
 * \param index - page index corespondent to fault.
 * \parm ra_flags - vma readahead flags.
 *
 * \return allocated and initialized env for fault operation.
 * \retval EINVAL if env can't allocated
 * \return other error codes from cl_io_init.
 */
static struct cl_io *
ll_fault_io_init(struct vm_area_struct *vma, struct lu_env **env_ret,
		 struct cl_env_nest *nest, pgoff_t index,
		 unsigned long *ra_flags)
{
	struct file	       *file = vma->vm_file;
	struct inode	       *inode = file_inode(file);
	struct cl_io	       *io;
	struct cl_fault_io     *fio;
	struct lu_env	       *env;
	int			rc;

	*env_ret = NULL;
	if (ll_file_nolock(file))
		return ERR_PTR(-EOPNOTSUPP);

	/*
	 * page fault can be called when lustre IO is
	 * already active for the current thread, e.g., when doing read/write
	 * against user level buffer mapped from Lustre buffer. To avoid
	 * stomping on existing context, optionally force an allocation of a new
	 * one.
	 */
	env = cl_env_nested_get(nest);
	if (IS_ERR(env))
		return ERR_PTR(-EINVAL);

	*env_ret = env;

restart:
	io = vvp_env_thread_io(env);
	io->ci_obj = ll_i2info(inode)->lli_clob;
	LASSERT(io->ci_obj);

	fio = &io->u.ci_fault;
	fio->ft_index      = index;
	fio->ft_executable = vma->vm_flags&VM_EXEC;

	/*
	 * disable VM_SEQ_READ and use VM_RAND_READ to make sure that
	 * the kernel will not read other pages not covered by ldlm in
	 * filemap_nopage. we do our readahead in ll_readpage.
	 */
	if (ra_flags)
		*ra_flags = vma->vm_flags & (VM_RAND_READ|VM_SEQ_READ);
	vma->vm_flags &= ~VM_SEQ_READ;
	vma->vm_flags |= VM_RAND_READ;

	CDEBUG(D_MMAP, "vm_flags: %lx (%lu %d)\n", vma->vm_flags,
	       fio->ft_index, fio->ft_executable);

	rc = cl_io_init(env, io, CIT_FAULT, io->ci_obj);
	if (rc == 0) {
		struct vvp_io *vio = vvp_env_io(env);
		struct ll_file_data *fd = LUSTRE_FPRIVATE(file);

		LASSERT(vio->vui_cl.cis_io == io);

		/* mmap lock must be MANDATORY it has to cache pages. */
		io->ci_lockreq = CILR_MANDATORY;
		vio->vui_fd = fd;
	} else {
		LASSERT(rc < 0);
		cl_io_fini(env, io);
		if (io->ci_need_restart)
			goto restart;

		cl_env_nested_put(nest, env);
		io = ERR_PTR(rc);
	}

	return io;
}

/* Sharing code of page_mkwrite method for rhel5 and rhel6 */
static int ll_page_mkwrite0(struct vm_area_struct *vma, struct page *vmpage,
			    bool *retry)
{
	struct lu_env	   *env;
	struct cl_io	    *io;
	struct vvp_io	   *vio;
	struct cl_env_nest       nest;
	int		      result;
	sigset_t	     set;
	struct inode	     *inode;
	struct ll_inode_info     *lli;

	io = ll_fault_io_init(vma, &env,  &nest, vmpage->index, NULL);
	if (IS_ERR(io)) {
		result = PTR_ERR(io);
		goto out;
	}

	result = io->ci_result;
	if (result < 0)
		goto out_io;

	io->u.ci_fault.ft_mkwrite = 1;
	io->u.ci_fault.ft_writable = 1;

	vio = vvp_env_io(env);
	vio->u.fault.ft_vma    = vma;
	vio->u.fault.ft_vmpage = vmpage;

	set = cfs_block_sigsinv(sigmask(SIGKILL) | sigmask(SIGTERM));

	inode = vvp_object_inode(io->ci_obj);
	lli = ll_i2info(inode);

	result = cl_io_loop(env, io);

	cfs_restore_sigs(set);

	if (result == 0) {
		struct inode *inode = file_inode(vma->vm_file);
		struct ll_inode_info *lli = ll_i2info(inode);

		lock_page(vmpage);
		if (!vmpage->mapping) {
			unlock_page(vmpage);

			/* page was truncated and lock was cancelled, return
			 * ENODATA so that VM_FAULT_NOPAGE will be returned
			 * to handle_mm_fault().
			 */
			if (result == 0)
				result = -ENODATA;
		} else if (!PageDirty(vmpage)) {
			/* race, the page has been cleaned by ptlrpcd after
			 * it was unlocked, it has to be added into dirty
			 * cache again otherwise this soon-to-dirty page won't
			 * consume any grants, even worse if this page is being
			 * transferred because it will break RPC checksum.
			 */
			unlock_page(vmpage);

			CDEBUG(D_MMAP, "Race on page_mkwrite %p/%lu, page has been written out, retry.\n",
			       vmpage, vmpage->index);

			*retry = true;
			result = -EAGAIN;
		}

		if (result == 0) {
			spin_lock(&lli->lli_lock);
			lli->lli_flags |= LLIF_DATA_MODIFIED;
			spin_unlock(&lli->lli_lock);
		}
	}

out_io:
	cl_io_fini(env, io);
	cl_env_nested_put(&nest, env);
out:
	CDEBUG(D_MMAP, "%s mkwrite with %d\n", current->comm, result);
	LASSERT(ergo(result == 0, PageLocked(vmpage)));

	return result;
}

static inline int to_fault_error(int result)
{
	switch (result) {
	case 0:
		result = VM_FAULT_LOCKED;
		break;
	case -EFAULT:
		result = VM_FAULT_NOPAGE;
		break;
	case -ENOMEM:
		result = VM_FAULT_OOM;
		break;
	default:
		result = VM_FAULT_SIGBUS;
		break;
	}
	return result;
}

/**
 * Lustre implementation of a vm_operations_struct::fault() method, called by
 * VM to server page fault (both in kernel and user space).
 *
 * \param vma - is virtual area struct related to page fault
 * \param vmf - structure which describe type and address where hit fault
 *
 * \return allocated and filled _locked_ page for address
 * \retval VM_FAULT_ERROR on general error
 * \retval NOPAGE_OOM not have memory for allocate new page
 */
static int ll_fault0(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	struct lu_env	   *env;
	struct cl_io	    *io;
	struct vvp_io	   *vio = NULL;
	struct page	     *vmpage;
	unsigned long	    ra_flags;
	struct cl_env_nest       nest;
	int		      result;
	int		      fault_ret = 0;

	io = ll_fault_io_init(vma, &env,  &nest, vmf->pgoff, &ra_flags);
	if (IS_ERR(io))
		return to_fault_error(PTR_ERR(io));

	result = io->ci_result;
	if (result == 0) {
		vio = vvp_env_io(env);
		vio->u.fault.ft_vma       = vma;
		vio->u.fault.ft_vmpage    = NULL;
		vio->u.fault.ft_vmf = vmf;
		vio->u.fault.ft_flags = 0;
		vio->u.fault.ft_flags_valid = false;

		/* May call ll_readpage() */
		ll_cl_add(vma->vm_file, env, io);

		result = cl_io_loop(env, io);

		ll_cl_remove(vma->vm_file, env);

		/* ft_flags are only valid if we reached
		 * the call to filemap_fault
		 */
		if (vio->u.fault.ft_flags_valid)
			fault_ret = vio->u.fault.ft_flags;

		vmpage = vio->u.fault.ft_vmpage;
		if (result != 0 && vmpage) {
			put_page(vmpage);
			vmf->page = NULL;
		}
	}
	cl_io_fini(env, io);
	cl_env_nested_put(&nest, env);

	vma->vm_flags |= ra_flags;
	if (result != 0 && !(fault_ret & VM_FAULT_RETRY))
		fault_ret |= to_fault_error(result);

	CDEBUG(D_MMAP, "%s fault %d/%d\n",
	       current->comm, fault_ret, result);
	return fault_ret;
}

static int ll_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	int count = 0;
	bool printed = false;
	int result;
	sigset_t set;

	/* Only SIGKILL and SIGTERM are allowed for fault/nopage/mkwrite
	 * so that it can be killed by admin but not cause segfault by
	 * other signals.
	 */
	set = cfs_block_sigsinv(sigmask(SIGKILL) | sigmask(SIGTERM));

restart:
	result = ll_fault0(vma, vmf);
	LASSERT(!(result & VM_FAULT_LOCKED));
	if (result == 0) {
		struct page *vmpage = vmf->page;

		/* check if this page has been truncated */
		lock_page(vmpage);
		if (unlikely(!vmpage->mapping)) { /* unlucky */
			unlock_page(vmpage);
			put_page(vmpage);
			vmf->page = NULL;

			if (!printed && ++count > 16) {
				CWARN("the page is under heavy contention, maybe your app(%s) needs revising :-)\n",
				      current->comm);
				printed = true;
			}

			goto restart;
		}

		result = VM_FAULT_LOCKED;
	}
	cfs_restore_sigs(set);
	return result;
}

static int ll_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	int count = 0;
	bool printed = false;
	bool retry;
	int result;

	do {
		retry = false;
		result = ll_page_mkwrite0(vma, vmf->page, &retry);

		if (!printed && ++count > 16) {
			const struct dentry *de = vma->vm_file->f_path.dentry;

			CWARN("app(%s): the page %lu of file "DFID" is under heavy contention\n",
			      current->comm, vmf->pgoff,
			      PFID(ll_inode2fid(de->d_inode)));
			printed = true;
		}
	} while (retry);

	switch (result) {
	case 0:
		LASSERT(PageLocked(vmf->page));
		result = VM_FAULT_LOCKED;
		break;
	case -ENODATA:
	case -EFAULT:
		result = VM_FAULT_NOPAGE;
		break;
	case -ENOMEM:
		result = VM_FAULT_OOM;
		break;
	case -EAGAIN:
		result = VM_FAULT_RETRY;
		break;
	default:
		result = VM_FAULT_SIGBUS;
		break;
	}

	return result;
}

/**
 *  To avoid cancel the locks covering mmapped region for lock cache pressure,
 *  we track the mapped vma count in vvp_object::vob_mmap_cnt.
 */
static void ll_vm_open(struct vm_area_struct *vma)
{
	struct inode *inode    = file_inode(vma->vm_file);
	struct vvp_object *vob = cl_inode2vvp(inode);

	LASSERT(vma->vm_file);
	LASSERT(atomic_read(&vob->vob_mmap_cnt) >= 0);
	atomic_inc(&vob->vob_mmap_cnt);
}

/**
 * Dual to ll_vm_open().
 */
static void ll_vm_close(struct vm_area_struct *vma)
{
	struct inode      *inode = file_inode(vma->vm_file);
	struct vvp_object *vob   = cl_inode2vvp(inode);

	LASSERT(vma->vm_file);
	atomic_dec(&vob->vob_mmap_cnt);
	LASSERT(atomic_read(&vob->vob_mmap_cnt) >= 0);
}

/* XXX put nice comment here.  talk about __free_pte -> dirty pages and
 * nopage's reference passing to the pte
 */
int ll_teardown_mmaps(struct address_space *mapping, __u64 first, __u64 last)
{
	int rc = -ENOENT;

	LASSERTF(last > first, "last %llu first %llu\n", last, first);
	if (mapping_mapped(mapping)) {
		rc = 0;
		unmap_mapping_range(mapping, first + PAGE_SIZE - 1,
				    last - first + 1, 0);
	}

	return rc;
}

static const struct vm_operations_struct ll_file_vm_ops = {
	.fault			= ll_fault,
	.page_mkwrite		= ll_page_mkwrite,
	.open			= ll_vm_open,
	.close			= ll_vm_close,
};

int ll_file_mmap(struct file *file, struct vm_area_struct *vma)
{
	struct inode *inode = file_inode(file);
	int rc;

	if (ll_file_nolock(file))
		return -EOPNOTSUPP;

	ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_MAP, 1);
	rc = generic_file_mmap(file, vma);
	if (rc == 0) {
		vma->vm_ops = &ll_file_vm_ops;
		vma->vm_ops->open(vma);
		/* update the inode's size and mtime */
		rc = ll_glimpse_size(inode);
	}

	return rc;
}