shmem.c 63.1 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8
/*
 * Resizable virtual memory filesystem for Linux.
 *
 * Copyright (C) 2000 Linus Torvalds.
 *		 2000 Transmeta Corp.
 *		 2000-2001 Christoph Rohland
 *		 2000-2001 SAP AG
 *		 2002 Red Hat Inc.
9 10
 * Copyright (C) 2002-2005 Hugh Dickins.
 * Copyright (C) 2002-2005 VERITAS Software Corporation.
Linus Torvalds's avatar
Linus Torvalds committed
11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
 * Copyright (C) 2004 Andi Kleen, SuSE Labs
 *
 * Extended attribute support for tmpfs:
 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
 *
 * This file is released under the GPL.
 */

/*
 * This virtual memory filesystem is heavily based on the ramfs. It
 * extends ramfs by the ability to use swap and honor resource limits
 * which makes it a completely usable filesystem.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
29 30
#include <linux/xattr.h>
#include <linux/generic_acl.h>
Linus Torvalds's avatar
Linus Torvalds committed
31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/file.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/backing-dev.h>
#include <linux/shmem_fs.h>
#include <linux/mount.h>
#include <linux/writeback.h>
#include <linux/vfs.h>
#include <linux/blkdev.h>
#include <linux/security.h>
#include <linux/swapops.h>
#include <linux/mempolicy.h>
#include <linux/namei.h>
48
#include <linux/ctype.h>
49
#include <linux/migrate.h>
50
#include <linux/highmem.h>
51
#include <linux/backing-dev.h>
52

Linus Torvalds's avatar
Linus Torvalds committed
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
#include <asm/uaccess.h>
#include <asm/div64.h>
#include <asm/pgtable.h>

/* This magic number is used in glibc for posix shared memory */
#define TMPFS_MAGIC	0x01021994

#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
#define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)

#define SHMEM_MAX_INDEX  (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
#define SHMEM_MAX_BYTES  ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)

#define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)

/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
#define SHMEM_PAGEIN	 VM_READ
#define SHMEM_TRUNCATE	 VM_WRITE

/* Definition to limit shmem_truncate's steps between cond_rescheds */
#define LATENCY_LIMIT	 64

/* Pretend that each entry is of this size in directory's i_size */
#define BOGO_DIRENT_SIZE 20

/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
enum sgp_type {
	SGP_QUICK,	/* don't try more than file page cache lookup */
	SGP_READ,	/* don't exceed i_size, don't allocate page */
	SGP_CACHE,	/* don't exceed i_size, may allocate page */
	SGP_WRITE,	/* may exceed i_size, may allocate page */
};

static int shmem_getpage(struct inode *inode, unsigned long idx,
			 struct page **pagep, enum sgp_type sgp, int *type);

Al Viro's avatar
Al Viro committed
90
static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
Linus Torvalds's avatar
Linus Torvalds committed
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
{
	/*
	 * The above definition of ENTRIES_PER_PAGE, and the use of
	 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
	 * might be reconsidered if it ever diverges from PAGE_SIZE.
	 */
	return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
}

static inline void shmem_dir_free(struct page *page)
{
	__free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
}

static struct page **shmem_dir_map(struct page *page)
{
	return (struct page **)kmap_atomic(page, KM_USER0);
}

static inline void shmem_dir_unmap(struct page **dir)
{
	kunmap_atomic(dir, KM_USER0);
}

static swp_entry_t *shmem_swp_map(struct page *page)
{
	return (swp_entry_t *)kmap_atomic(page, KM_USER1);
}

static inline void shmem_swp_balance_unmap(void)
{
	/*
	 * When passing a pointer to an i_direct entry, to code which
	 * also handles indirect entries and so will shmem_swp_unmap,
	 * we must arrange for the preempt count to remain in balance.
	 * What kmap_atomic of a lowmem page does depends on config
	 * and architecture, so pretend to kmap_atomic some lowmem page.
	 */
	(void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
}

static inline void shmem_swp_unmap(swp_entry_t *entry)
{
	kunmap_atomic(entry, KM_USER1);
}

static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
{
	return sb->s_fs_info;
}

/*
 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
 * for shared memory and for shared anonymous (/dev/zero) mappings
 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
 * consistent with the pre-accounting of private mappings ...
 */
static inline int shmem_acct_size(unsigned long flags, loff_t size)
{
	return (flags & VM_ACCOUNT)?
		security_vm_enough_memory(VM_ACCT(size)): 0;
}

static inline void shmem_unacct_size(unsigned long flags, loff_t size)
{
	if (flags & VM_ACCOUNT)
		vm_unacct_memory(VM_ACCT(size));
}

/*
 * ... whereas tmpfs objects are accounted incrementally as
 * pages are allocated, in order to allow huge sparse files.
 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
 */
static inline int shmem_acct_block(unsigned long flags)
{
	return (flags & VM_ACCOUNT)?
		0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
}

static inline void shmem_unacct_blocks(unsigned long flags, long pages)
{
	if (!(flags & VM_ACCOUNT))
		vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
}

static struct super_operations shmem_ops;
179
static const struct address_space_operations shmem_aops;
180
static const struct file_operations shmem_file_operations;
Linus Torvalds's avatar
Linus Torvalds committed
181 182
static struct inode_operations shmem_inode_operations;
static struct inode_operations shmem_dir_inode_operations;
183
static struct inode_operations shmem_special_inode_operations;
Linus Torvalds's avatar
Linus Torvalds committed
184 185
static struct vm_operations_struct shmem_vm_ops;

186
static struct backing_dev_info shmem_backing_dev_info  __read_mostly = {
Linus Torvalds's avatar
Linus Torvalds committed
187 188 189 190 191 192 193 194 195 196 197
	.ra_pages	= 0,	/* No readahead */
	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
	.unplug_io_fn	= default_unplug_io_fn,
};

static LIST_HEAD(shmem_swaplist);
static DEFINE_SPINLOCK(shmem_swaplist_lock);

static void shmem_free_blocks(struct inode *inode, long pages)
{
	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
198
	if (sbinfo->max_blocks) {
Linus Torvalds's avatar
Linus Torvalds committed
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
		spin_lock(&sbinfo->stat_lock);
		sbinfo->free_blocks += pages;
		inode->i_blocks -= pages*BLOCKS_PER_PAGE;
		spin_unlock(&sbinfo->stat_lock);
	}
}

/*
 * shmem_recalc_inode - recalculate the size of an inode
 *
 * @inode: inode to recalc
 *
 * We have to calculate the free blocks since the mm can drop
 * undirtied hole pages behind our back.
 *
 * But normally   info->alloced == inode->i_mapping->nrpages + info->swapped
 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
 *
 * It has to be called with the spinlock held.
 */
static void shmem_recalc_inode(struct inode *inode)
{
	struct shmem_inode_info *info = SHMEM_I(inode);
	long freed;

	freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
	if (freed > 0) {
		info->alloced -= freed;
		shmem_unacct_blocks(info->flags, freed);
		shmem_free_blocks(inode, freed);
	}
}

/*
 * shmem_swp_entry - find the swap vector position in the info structure
 *
 * @info:  info structure for the inode
 * @index: index of the page to find
 * @page:  optional page to add to the structure. Has to be preset to
 *         all zeros
 *
 * If there is no space allocated yet it will return NULL when
 * page is NULL, else it will use the page for the needed block,
 * setting it to NULL on return to indicate that it has been used.
 *
 * The swap vector is organized the following way:
 *
 * There are SHMEM_NR_DIRECT entries directly stored in the
 * shmem_inode_info structure. So small files do not need an addional
 * allocation.
 *
 * For pages with index > SHMEM_NR_DIRECT there is the pointer
 * i_indirect which points to a page which holds in the first half
 * doubly indirect blocks, in the second half triple indirect blocks:
 *
 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
 * following layout (for SHMEM_NR_DIRECT == 16):
 *
 * i_indirect -> dir --> 16-19
 * 	      |	     +-> 20-23
 * 	      |
 * 	      +-->dir2 --> 24-27
 * 	      |	       +-> 28-31
 * 	      |	       +-> 32-35
 * 	      |	       +-> 36-39
 * 	      |
 * 	      +-->dir3 --> 40-43
 * 	       	       +-> 44-47
 * 	      	       +-> 48-51
 * 	      	       +-> 52-55
 */
static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
{
	unsigned long offset;
	struct page **dir;
	struct page *subdir;

	if (index < SHMEM_NR_DIRECT) {
		shmem_swp_balance_unmap();
		return info->i_direct+index;
	}
	if (!info->i_indirect) {
		if (page) {
			info->i_indirect = *page;
			*page = NULL;
		}
		return NULL;			/* need another page */
	}

	index -= SHMEM_NR_DIRECT;
	offset = index % ENTRIES_PER_PAGE;
	index /= ENTRIES_PER_PAGE;
	dir = shmem_dir_map(info->i_indirect);

	if (index >= ENTRIES_PER_PAGE/2) {
		index -= ENTRIES_PER_PAGE/2;
		dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
		index %= ENTRIES_PER_PAGE;
		subdir = *dir;
		if (!subdir) {
			if (page) {
				*dir = *page;
				*page = NULL;
			}
			shmem_dir_unmap(dir);
			return NULL;		/* need another page */
		}
		shmem_dir_unmap(dir);
		dir = shmem_dir_map(subdir);
	}

	dir += index;
	subdir = *dir;
	if (!subdir) {
		if (!page || !(subdir = *page)) {
			shmem_dir_unmap(dir);
			return NULL;		/* need a page */
		}
		*dir = subdir;
		*page = NULL;
	}
	shmem_dir_unmap(dir);
	return shmem_swp_map(subdir) + offset;
}

static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
{
	long incdec = value? 1: -1;

	entry->val = value;
	info->swapped += incdec;
330 331 332 333
	if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
		struct page *page = kmap_atomic_to_page(entry);
		set_page_private(page, page_private(page) + incdec);
	}
Linus Torvalds's avatar
Linus Torvalds committed
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
}

/*
 * shmem_swp_alloc - get the position of the swap entry for the page.
 *                   If it does not exist allocate the entry.
 *
 * @info:	info structure for the inode
 * @index:	index of the page to find
 * @sgp:	check and recheck i_size? skip allocation?
 */
static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
{
	struct inode *inode = &info->vfs_inode;
	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
	struct page *page = NULL;
	swp_entry_t *entry;

	if (sgp != SGP_WRITE &&
	    ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
		return ERR_PTR(-EINVAL);

	while (!(entry = shmem_swp_entry(info, index, &page))) {
		if (sgp == SGP_READ)
			return shmem_swp_map(ZERO_PAGE(0));
		/*
		 * Test free_blocks against 1 not 0, since we have 1 data
		 * page (and perhaps indirect index pages) yet to allocate:
		 * a waste to allocate index if we cannot allocate data.
		 */
363
		if (sbinfo->max_blocks) {
Linus Torvalds's avatar
Linus Torvalds committed
364 365 366 367 368 369 370 371 372 373 374 375
			spin_lock(&sbinfo->stat_lock);
			if (sbinfo->free_blocks <= 1) {
				spin_unlock(&sbinfo->stat_lock);
				return ERR_PTR(-ENOSPC);
			}
			sbinfo->free_blocks--;
			inode->i_blocks += BLOCKS_PER_PAGE;
			spin_unlock(&sbinfo->stat_lock);
		}

		spin_unlock(&info->lock);
		page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
376 377
		if (page)
			set_page_private(page, 0);
Linus Torvalds's avatar
Linus Torvalds committed
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
		spin_lock(&info->lock);

		if (!page) {
			shmem_free_blocks(inode, 1);
			return ERR_PTR(-ENOMEM);
		}
		if (sgp != SGP_WRITE &&
		    ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
			entry = ERR_PTR(-EINVAL);
			break;
		}
		if (info->next_index <= index)
			info->next_index = index + 1;
	}
	if (page) {
		/* another task gave its page, or truncated the file */
		shmem_free_blocks(inode, 1);
		shmem_dir_free(page);
	}
	if (info->next_index <= index && !IS_ERR(entry))
		info->next_index = index + 1;
	return entry;
}

/*
 * shmem_free_swp - free some swap entries in a directory
 *
 * @dir:   pointer to the directory
 * @edir:  pointer after last entry of the directory
 */
static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
{
	swp_entry_t *ptr;
	int freed = 0;

	for (ptr = dir; ptr < edir; ptr++) {
		if (ptr->val) {
			free_swap_and_cache(*ptr);
			*ptr = (swp_entry_t){0};
			freed++;
		}
	}
	return freed;
}

static int shmem_map_and_free_swp(struct page *subdir,
		int offset, int limit, struct page ***dir)
{
	swp_entry_t *ptr;
	int freed = 0;

	ptr = shmem_swp_map(subdir);
	for (; offset < limit; offset += LATENCY_LIMIT) {
		int size = limit - offset;
		if (size > LATENCY_LIMIT)
			size = LATENCY_LIMIT;
		freed += shmem_free_swp(ptr+offset, ptr+offset+size);
		if (need_resched()) {
			shmem_swp_unmap(ptr);
			if (*dir) {
				shmem_dir_unmap(*dir);
				*dir = NULL;
			}
			cond_resched();
			ptr = shmem_swp_map(subdir);
		}
	}
	shmem_swp_unmap(ptr);
	return freed;
}

static void shmem_free_pages(struct list_head *next)
{
	struct page *page;
	int freed = 0;

	do {
		page = container_of(next, struct page, lru);
		next = next->next;
		shmem_dir_free(page);
		freed++;
		if (freed >= LATENCY_LIMIT) {
			cond_resched();
			freed = 0;
		}
	} while (next);
}

466
static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
Linus Torvalds's avatar
Linus Torvalds committed
467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483
{
	struct shmem_inode_info *info = SHMEM_I(inode);
	unsigned long idx;
	unsigned long size;
	unsigned long limit;
	unsigned long stage;
	unsigned long diroff;
	struct page **dir;
	struct page *topdir;
	struct page *middir;
	struct page *subdir;
	swp_entry_t *ptr;
	LIST_HEAD(pages_to_free);
	long nr_pages_to_free = 0;
	long nr_swaps_freed = 0;
	int offset;
	int freed;
484
	int punch_hole = 0;
Linus Torvalds's avatar
Linus Torvalds committed
485 486

	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
487
	idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds's avatar
Linus Torvalds committed
488 489 490 491 492
	if (idx >= info->next_index)
		return;

	spin_lock(&info->lock);
	info->flags |= SHMEM_TRUNCATE;
493 494 495 496 497 498 499 500 501 502
	if (likely(end == (loff_t) -1)) {
		limit = info->next_index;
		info->next_index = idx;
	} else {
		limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
		if (limit > info->next_index)
			limit = info->next_index;
		punch_hole = 1;
	}

Linus Torvalds's avatar
Linus Torvalds committed
503
	topdir = info->i_indirect;
504
	if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
Linus Torvalds's avatar
Linus Torvalds committed
505 506 507 508 509 510 511 512 513 514 515 516 517
		info->i_indirect = NULL;
		nr_pages_to_free++;
		list_add(&topdir->lru, &pages_to_free);
	}
	spin_unlock(&info->lock);

	if (info->swapped && idx < SHMEM_NR_DIRECT) {
		ptr = info->i_direct;
		size = limit;
		if (size > SHMEM_NR_DIRECT)
			size = SHMEM_NR_DIRECT;
		nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
	}
518 519 520 521 522 523

	/*
	 * If there are no indirect blocks or we are punching a hole
	 * below indirect blocks, nothing to be done.
	 */
	if (!topdir || (punch_hole && (limit <= SHMEM_NR_DIRECT)))
Linus Torvalds's avatar
Linus Torvalds committed
524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581
		goto done2;

	BUG_ON(limit <= SHMEM_NR_DIRECT);
	limit -= SHMEM_NR_DIRECT;
	idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
	offset = idx % ENTRIES_PER_PAGE;
	idx -= offset;

	dir = shmem_dir_map(topdir);
	stage = ENTRIES_PER_PAGEPAGE/2;
	if (idx < ENTRIES_PER_PAGEPAGE/2) {
		middir = topdir;
		diroff = idx/ENTRIES_PER_PAGE;
	} else {
		dir += ENTRIES_PER_PAGE/2;
		dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
		while (stage <= idx)
			stage += ENTRIES_PER_PAGEPAGE;
		middir = *dir;
		if (*dir) {
			diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
				ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
			if (!diroff && !offset) {
				*dir = NULL;
				nr_pages_to_free++;
				list_add(&middir->lru, &pages_to_free);
			}
			shmem_dir_unmap(dir);
			dir = shmem_dir_map(middir);
		} else {
			diroff = 0;
			offset = 0;
			idx = stage;
		}
	}

	for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
		if (unlikely(idx == stage)) {
			shmem_dir_unmap(dir);
			dir = shmem_dir_map(topdir) +
			    ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
			while (!*dir) {
				dir++;
				idx += ENTRIES_PER_PAGEPAGE;
				if (idx >= limit)
					goto done1;
			}
			stage = idx + ENTRIES_PER_PAGEPAGE;
			middir = *dir;
			*dir = NULL;
			nr_pages_to_free++;
			list_add(&middir->lru, &pages_to_free);
			shmem_dir_unmap(dir);
			cond_resched();
			dir = shmem_dir_map(middir);
			diroff = 0;
		}
		subdir = dir[diroff];
582
		if (subdir && page_private(subdir)) {
Linus Torvalds's avatar
Linus Torvalds committed
583 584 585 586 587 588 589 590 591 592
			size = limit - idx;
			if (size > ENTRIES_PER_PAGE)
				size = ENTRIES_PER_PAGE;
			freed = shmem_map_and_free_swp(subdir,
						offset, size, &dir);
			if (!dir)
				dir = shmem_dir_map(middir);
			nr_swaps_freed += freed;
			if (offset)
				spin_lock(&info->lock);
593
			set_page_private(subdir, page_private(subdir) - freed);
Linus Torvalds's avatar
Linus Torvalds committed
594 595
			if (offset)
				spin_unlock(&info->lock);
596 597
			if (!punch_hole)
				BUG_ON(page_private(subdir) > offset);
Linus Torvalds's avatar
Linus Torvalds committed
598 599 600
		}
		if (offset)
			offset = 0;
601
		else if (subdir && !page_private(subdir)) {
Linus Torvalds's avatar
Linus Torvalds committed
602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617
			dir[diroff] = NULL;
			nr_pages_to_free++;
			list_add(&subdir->lru, &pages_to_free);
		}
	}
done1:
	shmem_dir_unmap(dir);
done2:
	if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
		/*
		 * Call truncate_inode_pages again: racing shmem_unuse_inode
		 * may have swizzled a page in from swap since vmtruncate or
		 * generic_delete_inode did it, before we lowered next_index.
		 * Also, though shmem_getpage checks i_size before adding to
		 * cache, no recheck after: so fix the narrow window there too.
		 */
618
		truncate_inode_pages_range(inode->i_mapping, start, end);
Linus Torvalds's avatar
Linus Torvalds committed
619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637
	}

	spin_lock(&info->lock);
	info->flags &= ~SHMEM_TRUNCATE;
	info->swapped -= nr_swaps_freed;
	if (nr_pages_to_free)
		shmem_free_blocks(inode, nr_pages_to_free);
	shmem_recalc_inode(inode);
	spin_unlock(&info->lock);

	/*
	 * Empty swap vector directory pages to be freed?
	 */
	if (!list_empty(&pages_to_free)) {
		pages_to_free.prev->next = NULL;
		shmem_free_pages(pages_to_free.next);
	}
}

638 639 640 641 642
static void shmem_truncate(struct inode *inode)
{
	shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
}

Linus Torvalds's avatar
Linus Torvalds committed
643 644 645 646 647 648
static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
{
	struct inode *inode = dentry->d_inode;
	struct page *page = NULL;
	int error;

649
	if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
Linus Torvalds's avatar
Linus Torvalds committed
650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681
		if (attr->ia_size < inode->i_size) {
			/*
			 * If truncating down to a partial page, then
			 * if that page is already allocated, hold it
			 * in memory until the truncation is over, so
			 * truncate_partial_page cannnot miss it were
			 * it assigned to swap.
			 */
			if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
				(void) shmem_getpage(inode,
					attr->ia_size>>PAGE_CACHE_SHIFT,
						&page, SGP_READ, NULL);
			}
			/*
			 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
			 * detect if any pages might have been added to cache
			 * after truncate_inode_pages.  But we needn't bother
			 * if it's being fully truncated to zero-length: the
			 * nrpages check is efficient enough in that case.
			 */
			if (attr->ia_size) {
				struct shmem_inode_info *info = SHMEM_I(inode);
				spin_lock(&info->lock);
				info->flags &= ~SHMEM_PAGEIN;
				spin_unlock(&info->lock);
			}
		}
	}

	error = inode_change_ok(inode, attr);
	if (!error)
		error = inode_setattr(inode, attr);
682 683 684 685
#ifdef CONFIG_TMPFS_POSIX_ACL
	if (!error && (attr->ia_valid & ATTR_MODE))
		error = generic_acl_chmod(inode, &shmem_acl_ops);
#endif
Linus Torvalds's avatar
Linus Torvalds committed
686 687 688 689 690 691 692 693 694 695 696
	if (page)
		page_cache_release(page);
	return error;
}

static void shmem_delete_inode(struct inode *inode)
{
	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
	struct shmem_inode_info *info = SHMEM_I(inode);

	if (inode->i_op->truncate == shmem_truncate) {
697
		truncate_inode_pages(inode->i_mapping, 0);
Linus Torvalds's avatar
Linus Torvalds committed
698 699 700 701 702 703 704 705 706
		shmem_unacct_size(info->flags, inode->i_size);
		inode->i_size = 0;
		shmem_truncate(inode);
		if (!list_empty(&info->swaplist)) {
			spin_lock(&shmem_swaplist_lock);
			list_del_init(&info->swaplist);
			spin_unlock(&shmem_swaplist_lock);
		}
	}
707 708
	BUG_ON(inode->i_blocks);
	if (sbinfo->max_inodes) {
Linus Torvalds's avatar
Linus Torvalds committed
709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773
		spin_lock(&sbinfo->stat_lock);
		sbinfo->free_inodes++;
		spin_unlock(&sbinfo->stat_lock);
	}
	clear_inode(inode);
}

static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
{
	swp_entry_t *ptr;

	for (ptr = dir; ptr < edir; ptr++) {
		if (ptr->val == entry.val)
			return ptr - dir;
	}
	return -1;
}

static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
{
	struct inode *inode;
	unsigned long idx;
	unsigned long size;
	unsigned long limit;
	unsigned long stage;
	struct page **dir;
	struct page *subdir;
	swp_entry_t *ptr;
	int offset;

	idx = 0;
	ptr = info->i_direct;
	spin_lock(&info->lock);
	limit = info->next_index;
	size = limit;
	if (size > SHMEM_NR_DIRECT)
		size = SHMEM_NR_DIRECT;
	offset = shmem_find_swp(entry, ptr, ptr+size);
	if (offset >= 0) {
		shmem_swp_balance_unmap();
		goto found;
	}
	if (!info->i_indirect)
		goto lost2;

	dir = shmem_dir_map(info->i_indirect);
	stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;

	for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
		if (unlikely(idx == stage)) {
			shmem_dir_unmap(dir-1);
			dir = shmem_dir_map(info->i_indirect) +
			    ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
			while (!*dir) {
				dir++;
				idx += ENTRIES_PER_PAGEPAGE;
				if (idx >= limit)
					goto lost1;
			}
			stage = idx + ENTRIES_PER_PAGEPAGE;
			subdir = *dir;
			shmem_dir_unmap(dir);
			dir = shmem_dir_map(subdir);
		}
		subdir = *dir;
774
		if (subdir && page_private(subdir)) {
Linus Torvalds's avatar
Linus Torvalds committed
775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887
			ptr = shmem_swp_map(subdir);
			size = limit - idx;
			if (size > ENTRIES_PER_PAGE)
				size = ENTRIES_PER_PAGE;
			offset = shmem_find_swp(entry, ptr, ptr+size);
			if (offset >= 0) {
				shmem_dir_unmap(dir);
				goto found;
			}
			shmem_swp_unmap(ptr);
		}
	}
lost1:
	shmem_dir_unmap(dir-1);
lost2:
	spin_unlock(&info->lock);
	return 0;
found:
	idx += offset;
	inode = &info->vfs_inode;
	if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
		info->flags |= SHMEM_PAGEIN;
		shmem_swp_set(info, ptr + offset, 0);
	}
	shmem_swp_unmap(ptr);
	spin_unlock(&info->lock);
	/*
	 * Decrement swap count even when the entry is left behind:
	 * try_to_unuse will skip over mms, then reincrement count.
	 */
	swap_free(entry);
	return 1;
}

/*
 * shmem_unuse() search for an eventually swapped out shmem page.
 */
int shmem_unuse(swp_entry_t entry, struct page *page)
{
	struct list_head *p, *next;
	struct shmem_inode_info *info;
	int found = 0;

	spin_lock(&shmem_swaplist_lock);
	list_for_each_safe(p, next, &shmem_swaplist) {
		info = list_entry(p, struct shmem_inode_info, swaplist);
		if (!info->swapped)
			list_del_init(&info->swaplist);
		else if (shmem_unuse_inode(info, entry, page)) {
			/* move head to start search for next from here */
			list_move_tail(&shmem_swaplist, &info->swaplist);
			found = 1;
			break;
		}
	}
	spin_unlock(&shmem_swaplist_lock);
	return found;
}

/*
 * Move the page from the page cache to the swap cache.
 */
static int shmem_writepage(struct page *page, struct writeback_control *wbc)
{
	struct shmem_inode_info *info;
	swp_entry_t *entry, swap;
	struct address_space *mapping;
	unsigned long index;
	struct inode *inode;

	BUG_ON(!PageLocked(page));
	BUG_ON(page_mapped(page));

	mapping = page->mapping;
	index = page->index;
	inode = mapping->host;
	info = SHMEM_I(inode);
	if (info->flags & VM_LOCKED)
		goto redirty;
	swap = get_swap_page();
	if (!swap.val)
		goto redirty;

	spin_lock(&info->lock);
	shmem_recalc_inode(inode);
	if (index >= info->next_index) {
		BUG_ON(!(info->flags & SHMEM_TRUNCATE));
		goto unlock;
	}
	entry = shmem_swp_entry(info, index, NULL);
	BUG_ON(!entry);
	BUG_ON(entry->val);

	if (move_to_swap_cache(page, swap) == 0) {
		shmem_swp_set(info, entry, swap.val);
		shmem_swp_unmap(entry);
		spin_unlock(&info->lock);
		if (list_empty(&info->swaplist)) {
			spin_lock(&shmem_swaplist_lock);
			/* move instead of add in case we're racing */
			list_move_tail(&info->swaplist, &shmem_swaplist);
			spin_unlock(&shmem_swaplist_lock);
		}
		unlock_page(page);
		return 0;
	}

	shmem_swp_unmap(entry);
unlock:
	spin_unlock(&info->lock);
	swap_free(swap);
redirty:
	set_page_dirty(page);
888
	return AOP_WRITEPAGE_ACTIVATE;	/* Return with the page locked */
Linus Torvalds's avatar
Linus Torvalds committed
889 890 891
}

#ifdef CONFIG_NUMA
892
static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936
{
	char *nodelist = strchr(value, ':');
	int err = 1;

	if (nodelist) {
		/* NUL-terminate policy string */
		*nodelist++ = '\0';
		if (nodelist_parse(nodelist, *policy_nodes))
			goto out;
	}
	if (!strcmp(value, "default")) {
		*policy = MPOL_DEFAULT;
		/* Don't allow a nodelist */
		if (!nodelist)
			err = 0;
	} else if (!strcmp(value, "prefer")) {
		*policy = MPOL_PREFERRED;
		/* Insist on a nodelist of one node only */
		if (nodelist) {
			char *rest = nodelist;
			while (isdigit(*rest))
				rest++;
			if (!*rest)
				err = 0;
		}
	} else if (!strcmp(value, "bind")) {
		*policy = MPOL_BIND;
		/* Insist on a nodelist */
		if (nodelist)
			err = 0;
	} else if (!strcmp(value, "interleave")) {
		*policy = MPOL_INTERLEAVE;
		/* Default to nodes online if no nodelist */
		if (!nodelist)
			*policy_nodes = node_online_map;
		err = 0;
	}
out:
	/* Restore string for error message */
	if (nodelist)
		*--nodelist = ':';
	return err;
}

Linus Torvalds's avatar
Linus Torvalds committed
937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973
static struct page *shmem_swapin_async(struct shared_policy *p,
				       swp_entry_t entry, unsigned long idx)
{
	struct page *page;
	struct vm_area_struct pvma;

	/* Create a pseudo vma that just contains the policy */
	memset(&pvma, 0, sizeof(struct vm_area_struct));
	pvma.vm_end = PAGE_SIZE;
	pvma.vm_pgoff = idx;
	pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
	page = read_swap_cache_async(entry, &pvma, 0);
	mpol_free(pvma.vm_policy);
	return page;
}

struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
			  unsigned long idx)
{
	struct shared_policy *p = &info->policy;
	int i, num;
	struct page *page;
	unsigned long offset;

	num = valid_swaphandles(entry, &offset);
	for (i = 0; i < num; offset++, i++) {
		page = shmem_swapin_async(p,
				swp_entry(swp_type(entry), offset), idx);
		if (!page)
			break;
		page_cache_release(page);
	}
	lru_add_drain();	/* Push any new pages onto the LRU now */
	return shmem_swapin_async(p, entry, idx);
}

static struct page *
Al Viro's avatar
Al Viro committed
974
shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info,
Linus Torvalds's avatar
Linus Torvalds committed
975 976 977 978 979 980 981 982 983 984 985 986 987 988
		 unsigned long idx)
{
	struct vm_area_struct pvma;
	struct page *page;

	memset(&pvma, 0, sizeof(struct vm_area_struct));
	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
	pvma.vm_pgoff = idx;
	pvma.vm_end = PAGE_SIZE;
	page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
	mpol_free(pvma.vm_policy);
	return page;
}
#else
989 990 991 992 993
static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
{
	return 1;
}

Linus Torvalds's avatar
Linus Torvalds committed
994 995 996 997 998 999 1000 1001
static inline struct page *
shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
{
	swapin_readahead(entry, 0, NULL);
	return read_swap_cache_async(entry, NULL, 0);
}

static inline struct page *
1002
shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds's avatar
Linus Torvalds committed
1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062
{
	return alloc_page(gfp | __GFP_ZERO);
}
#endif

/*
 * shmem_getpage - either get the page from swap or allocate a new one
 *
 * If we allocate a new one we do not mark it dirty. That's up to the
 * vm. If we swap it in we mark it dirty since we also free the swap
 * entry since a page cannot live in both the swap and page cache
 */
static int shmem_getpage(struct inode *inode, unsigned long idx,
			struct page **pagep, enum sgp_type sgp, int *type)
{
	struct address_space *mapping = inode->i_mapping;
	struct shmem_inode_info *info = SHMEM_I(inode);
	struct shmem_sb_info *sbinfo;
	struct page *filepage = *pagep;
	struct page *swappage;
	swp_entry_t *entry;
	swp_entry_t swap;
	int error;

	if (idx >= SHMEM_MAX_INDEX)
		return -EFBIG;
	/*
	 * Normally, filepage is NULL on entry, and either found
	 * uptodate immediately, or allocated and zeroed, or read
	 * in under swappage, which is then assigned to filepage.
	 * But shmem_prepare_write passes in a locked filepage,
	 * which may be found not uptodate by other callers too,
	 * and may need to be copied from the swappage read in.
	 */
repeat:
	if (!filepage)
		filepage = find_lock_page(mapping, idx);
	if (filepage && PageUptodate(filepage))
		goto done;
	error = 0;
	if (sgp == SGP_QUICK)
		goto failed;

	spin_lock(&info->lock);
	shmem_recalc_inode(inode);
	entry = shmem_swp_alloc(info, idx, sgp);
	if (IS_ERR(entry)) {
		spin_unlock(&info->lock);
		error = PTR_ERR(entry);
		goto failed;
	}
	swap = *entry;

	if (swap.val) {
		/* Look it up and read it in.. */
		swappage = lookup_swap_cache(swap);
		if (!swappage) {
			shmem_swp_unmap(entry);
			/* here we actually do the io */
			if (type && *type == VM_FAULT_MINOR) {
1063
				__count_vm_event(PGMAJFAULT);
Linus Torvalds's avatar
Linus Torvalds committed
1064 1065
				*type = VM_FAULT_MAJOR;
			}
1066
			spin_unlock(&info->lock);
Linus Torvalds's avatar
Linus Torvalds committed
1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139
			swappage = shmem_swapin(info, swap, idx);
			if (!swappage) {
				spin_lock(&info->lock);
				entry = shmem_swp_alloc(info, idx, sgp);
				if (IS_ERR(entry))
					error = PTR_ERR(entry);
				else {
					if (entry->val == swap.val)
						error = -ENOMEM;
					shmem_swp_unmap(entry);
				}
				spin_unlock(&info->lock);
				if (error)
					goto failed;
				goto repeat;
			}
			wait_on_page_locked(swappage);
			page_cache_release(swappage);
			goto repeat;
		}

		/* We have to do this with page locked to prevent races */
		if (TestSetPageLocked(swappage)) {
			shmem_swp_unmap(entry);
			spin_unlock(&info->lock);
			wait_on_page_locked(swappage);
			page_cache_release(swappage);
			goto repeat;
		}
		if (PageWriteback(swappage)) {
			shmem_swp_unmap(entry);
			spin_unlock(&info->lock);
			wait_on_page_writeback(swappage);
			unlock_page(swappage);
			page_cache_release(swappage);
			goto repeat;
		}
		if (!PageUptodate(swappage)) {
			shmem_swp_unmap(entry);
			spin_unlock(&info->lock);
			unlock_page(swappage);
			page_cache_release(swappage);
			error = -EIO;
			goto failed;
		}

		if (filepage) {
			shmem_swp_set(info, entry, 0);
			shmem_swp_unmap(entry);
			delete_from_swap_cache(swappage);
			spin_unlock(&info->lock);
			copy_highpage(filepage, swappage);
			unlock_page(swappage);
			page_cache_release(swappage);
			flush_dcache_page(filepage);
			SetPageUptodate(filepage);
			set_page_dirty(filepage);
			swap_free(swap);
		} else if (!(error = move_from_swap_cache(
				swappage, idx, mapping))) {
			info->flags |= SHMEM_PAGEIN;
			shmem_swp_set(info, entry, 0);
			shmem_swp_unmap(entry);
			spin_unlock(&info->lock);
			filepage = swappage;
			swap_free(swap);
		} else {
			shmem_swp_unmap(entry);
			spin_unlock(&info->lock);
			unlock_page(swappage);
			page_cache_release(swappage);
			if (error == -ENOMEM) {
				/* let kswapd refresh zone for GFP_ATOMICs */
1140
				congestion_wait(WRITE, HZ/50);
Linus Torvalds's avatar
Linus Torvalds committed
1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158
			}
			goto repeat;
		}
	} else if (sgp == SGP_READ && !filepage) {
		shmem_swp_unmap(entry);
		filepage = find_get_page(mapping, idx);
		if (filepage &&
		    (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
			spin_unlock(&info->lock);
			wait_on_page_locked(filepage);
			page_cache_release(filepage);
			filepage = NULL;
			goto repeat;
		}
		spin_unlock(&info->lock);
	} else {
		shmem_swp_unmap(entry);
		sbinfo = SHMEM_SB(inode->i_sb);
1159
		if (sbinfo->max_blocks) {
Linus Torvalds's avatar
Linus Torvalds committed
1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232
			spin_lock(&sbinfo->stat_lock);
			if (sbinfo->free_blocks == 0 ||
			    shmem_acct_block(info->flags)) {
				spin_unlock(&sbinfo->stat_lock);
				spin_unlock(&info->lock);
				error = -ENOSPC;
				goto failed;
			}
			sbinfo->free_blocks--;
			inode->i_blocks += BLOCKS_PER_PAGE;
			spin_unlock(&sbinfo->stat_lock);
		} else if (shmem_acct_block(info->flags)) {
			spin_unlock(&info->lock);
			error = -ENOSPC;
			goto failed;
		}

		if (!filepage) {
			spin_unlock(&info->lock);
			filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
						    info,
						    idx);
			if (!filepage) {
				shmem_unacct_blocks(info->flags, 1);
				shmem_free_blocks(inode, 1);
				error = -ENOMEM;
				goto failed;
			}

			spin_lock(&info->lock);
			entry = shmem_swp_alloc(info, idx, sgp);
			if (IS_ERR(entry))
				error = PTR_ERR(entry);
			else {
				swap = *entry;
				shmem_swp_unmap(entry);
			}
			if (error || swap.val || 0 != add_to_page_cache_lru(
					filepage, mapping, idx, GFP_ATOMIC)) {
				spin_unlock(&info->lock);
				page_cache_release(filepage);
				shmem_unacct_blocks(info->flags, 1);
				shmem_free_blocks(inode, 1);
				filepage = NULL;
				if (error)
					goto failed;
				goto repeat;
			}
			info->flags |= SHMEM_PAGEIN;
		}

		info->alloced++;
		spin_unlock(&info->lock);
		flush_dcache_page(filepage);
		SetPageUptodate(filepage);
	}
done:
	if (*pagep != filepage) {
		unlock_page(filepage);
		*pagep = filepage;
	}
	return 0;

failed:
	if (*pagep != filepage) {
		unlock_page(filepage);
		page_cache_release(filepage);
	}
	return error;
}

struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
{
1233
	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255
	struct page *page = NULL;
	unsigned long idx;
	int error;

	idx = (address - vma->vm_start) >> PAGE_SHIFT;
	idx += vma->vm_pgoff;
	idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
	if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
		return NOPAGE_SIGBUS;

	error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
	if (error)
		return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;

	mark_page_accessed(page);
	return page;
}

static int shmem_populate(struct vm_area_struct *vma,
	unsigned long addr, unsigned long len,
	pgprot_t prot, unsigned long pgoff, int nonblock)
{
1256
	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273
	struct mm_struct *mm = vma->vm_mm;
	enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
	unsigned long size;

	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
	if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
		return -EINVAL;

	while ((long) len > 0) {
		struct page *page = NULL;
		int err;
		/*
		 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
		 */
		err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
		if (err)
			return err;
1274
		/* Page may still be null, but only if nonblock was set. */
Linus Torvalds's avatar
Linus Torvalds committed
1275 1276 1277 1278 1279 1280 1281
		if (page) {
			mark_page_accessed(page);
			err = install_page(mm, vma, addr, page, prot);
			if (err) {
				page_cache_release(page);
				return err;
			}
1282
		} else if (vma->vm_flags & VM_NONLINEAR) {
1283 1284 1285
			/* No page was found just because we can't read it in
			 * now (being here implies nonblock != 0), but the page
			 * may exist, so set the PTE to fault it in later. */
Linus Torvalds's avatar
Linus Torvalds committed
1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300
    			err = install_file_pte(mm, vma, addr, pgoff, prot);
			if (err)
	    			return err;
		}

		len -= PAGE_SIZE;
		addr += PAGE_SIZE;
		pgoff++;
	}
	return 0;
}

#ifdef CONFIG_NUMA
int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
{
1301
	struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
1302 1303 1304 1305 1306 1307
	return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
}

struct mempolicy *
shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
{
1308
	struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
1309 1310 1311 1312 1313 1314 1315 1316 1317
	unsigned long idx;

	idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
	return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
}
#endif

int shmem_lock(struct file *file, int lock, struct user_struct *user)
{
1318
	struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337
	struct shmem_inode_info *info = SHMEM_I(inode);
	int retval = -ENOMEM;

	spin_lock(&info->lock);
	if (lock && !(info->flags & VM_LOCKED)) {
		if (!user_shm_lock(inode->i_size, user))
			goto out_nomem;
		info->flags |= VM_LOCKED;
	}
	if (!lock && (info->flags & VM_LOCKED) && user) {
		user_shm_unlock(inode->i_size, user);
		info->flags &= ~VM_LOCKED;
	}
	retval = 0;
out_nomem:
	spin_unlock(&info->lock);
	return retval;
}

1338
int shmem_mmap(struct file *file, struct vm_area_struct *vma)
Linus Torvalds's avatar
Linus Torvalds committed
1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351
{
	file_accessed(file);
	vma->vm_ops = &shmem_vm_ops;
	return 0;
}

static struct inode *
shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
{
	struct inode *inode;
	struct shmem_inode_info *info;
	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);

1352
	if (sbinfo->max_inodes) {
Linus Torvalds's avatar
Linus Torvalds committed
1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370
		spin_lock(&sbinfo->stat_lock);
		if (!sbinfo->free_inodes) {
			spin_unlock(&sbinfo->stat_lock);
			return NULL;
		}
		sbinfo->free_inodes--;
		spin_unlock(&sbinfo->stat_lock);
	}

	inode = new_inode(sb);
	if (inode) {
		inode->i_mode = mode;
		inode->i_uid = current->fsuid;
		inode->i_gid = current->fsgid;
		inode->i_blocks = 0;
		inode->i_mapping->a_ops = &shmem_aops;
		inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1371
		inode->i_generation = get_seconds();
Linus Torvalds's avatar
Linus Torvalds committed
1372 1373 1374 1375 1376 1377 1378
		info = SHMEM_I(inode);
		memset(info, 0, (char *)inode - (char *)info);
		spin_lock_init(&info->lock);
		INIT_LIST_HEAD(&info->swaplist);

		switch (mode & S_IFMT) {
		default:
1379
			inode->i_op = &shmem_special_inode_operations;
Linus Torvalds's avatar
Linus Torvalds committed
1380 1381 1382 1383 1384
			init_special_inode(inode, mode, dev);
			break;
		case S_IFREG:
			inode->i_op = &shmem_inode_operations;
			inode->i_fop = &shmem_file_operations;
1385 1386
			mpol_shared_policy_init(&info->policy, sbinfo->policy,
							&sbinfo->policy_nodes);
Linus Torvalds's avatar
Linus Torvalds committed
1387 1388
			break;
		case S_IFDIR:
1389
			inc_nlink(inode);
Linus Torvalds's avatar
Linus Torvalds committed
1390 1391 1392 1393 1394 1395 1396 1397 1398 1399
			/* Some things misbehave if size == 0 on a directory */
			inode->i_size = 2 * BOGO_DIRENT_SIZE;
			inode->i_op = &shmem_dir_inode_operations;
			inode->i_fop = &simple_dir_operations;
			break;
		case S_IFLNK:
			/*
			 * Must not load anything in the rbtree,
			 * mpol_free_shared_policy will not be called.
			 */
1400 1401
			mpol_shared_policy_init(&info->policy, MPOL_DEFAULT,
						NULL);
Linus Torvalds's avatar
Linus Torvalds committed
1402 1403
			break;
		}
1404
	} else if (sbinfo->max_inodes) {
Linus Torvalds's avatar
Linus Torvalds committed
1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429
		spin_lock(&sbinfo->stat_lock);
		sbinfo->free_inodes++;
		spin_unlock(&sbinfo->stat_lock);
	}
	return inode;
}

#ifdef CONFIG_TMPFS
static struct inode_operations shmem_symlink_inode_operations;
static struct inode_operations shmem_symlink_inline_operations;

/*
 * Normally tmpfs makes no use of shmem_prepare_write, but it
 * lets a tmpfs file be used read-write below the loop driver.
 */
static int
shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
{
	struct inode *inode = page->mapping->host;
	return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
}

static ssize_t
shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
1430
	struct inode	*inode = file->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
1431 1432 1433 1434 1435 1436 1437 1438 1439 1440
	loff_t		pos;
	unsigned long	written;
	ssize_t		err;

	if ((ssize_t) count < 0)
		return -EINVAL;

	if (!access_ok(VERIFY_READ, buf, count))
		return -EFAULT;

1441
	mutex_lock(&inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1442 1443 1444 1445 1446 1447 1448 1449

	pos = *ppos;
	written = 0;

	err = generic_write_checks(file, &pos, &count, 0);
	if (err || !count)
		goto out;

1450
	err = remove_suid(file->f_path.dentry);
Linus Torvalds's avatar
Linus Torvalds committed
1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525
	if (err)
		goto out;

	inode->i_ctime = inode->i_mtime = CURRENT_TIME;

	do {
		struct page *page = NULL;
		unsigned long bytes, index, offset;
		char *kaddr;
		int left;

		offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
		index = pos >> PAGE_CACHE_SHIFT;
		bytes = PAGE_CACHE_SIZE - offset;
		if (bytes > count)
			bytes = count;

		/*
		 * We don't hold page lock across copy from user -
		 * what would it guard against? - so no deadlock here.
		 * But it still may be a good idea to prefault below.
		 */

		err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
		if (err)
			break;

		left = bytes;
		if (PageHighMem(page)) {
			volatile unsigned char dummy;
			__get_user(dummy, buf);
			__get_user(dummy, buf + bytes - 1);

			kaddr = kmap_atomic(page, KM_USER0);
			left = __copy_from_user_inatomic(kaddr + offset,
							buf, bytes);
			kunmap_atomic(kaddr, KM_USER0);
		}
		if (left) {
			kaddr = kmap(page);
			left = __copy_from_user(kaddr + offset, buf, bytes);
			kunmap(page);
		}

		written += bytes;
		count -= bytes;
		pos += bytes;
		buf += bytes;
		if (pos > inode->i_size)
			i_size_write(inode, pos);

		flush_dcache_page(page);
		set_page_dirty(page);
		mark_page_accessed(page);
		page_cache_release(page);

		if (left) {
			pos -= left;
			written -= left;
			err = -EFAULT;
			break;
		}

		/*
		 * Our dirty pages are not counted in nr_dirty,
		 * and we do not attempt to balance dirty pages.
		 */

		cond_resched();
	} while (count);

	*ppos = pos;
	if (written)
		err = written;
out:
1526
	mutex_unlock(&inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1527 1528 1529 1530 1531
	return err;
}

static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
{
1532
	struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561
	struct address_space *mapping = inode->i_mapping;
	unsigned long index, offset;

	index = *ppos >> PAGE_CACHE_SHIFT;
	offset = *ppos & ~PAGE_CACHE_MASK;

	for (;;) {
		struct page *page = NULL;
		unsigned long end_index, nr, ret;
		loff_t i_size = i_size_read(inode);

		end_index = i_size >> PAGE_CACHE_SHIFT;
		if (index > end_index)
			break;
		if (index == end_index) {
			nr = i_size & ~PAGE_CACHE_MASK;
			if (nr <= offset)
				break;
		}

		desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
		if (desc->error) {
			if (desc->error == -EINVAL)
				desc->error = 0;
			break;
		}

		/*
		 * We must evaluate after, since reads (unlike writes)
1562
		 * are called without i_mutex protection against truncate
Linus Torvalds's avatar
Linus Torvalds committed
1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589
		 */
		nr = PAGE_CACHE_SIZE;
		i_size = i_size_read(inode);
		end_index = i_size >> PAGE_CACHE_SHIFT;
		if (index == end_index) {
			nr = i_size & ~PAGE_CACHE_MASK;
			if (nr <= offset) {
				if (page)
					page_cache_release(page);
				break;
			}
		}
		nr -= offset;

		if (page) {
			/*
			 * If users can be writing to this page using arbitrary
			 * virtual addresses, take care about potential aliasing
			 * before reading the page on the kernel side.
			 */
			if (mapping_writably_mapped(mapping))
				flush_dcache_page(page);
			/*
			 * Mark the page accessed if we read the beginning.
			 */
			if (!offset)
				mark_page_accessed(page);
1590
		} else {
Linus Torvalds's avatar
Linus Torvalds committed
1591
			page = ZERO_PAGE(0);
1592 1593
			page_cache_get(page);
		}
Linus Torvalds's avatar
Linus Torvalds committed
1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661

		/*
		 * Ok, we have the page, and it's up-to-date, so
		 * now we can copy it to user space...
		 *
		 * The actor routine returns how many bytes were actually used..
		 * NOTE! This may not be the same as how much of a user buffer
		 * we filled up (we may be padding etc), so we can only update
		 * "pos" here (the actor routine has to update the user buffer
		 * pointers and the remaining count).
		 */
		ret = actor(desc, page, offset, nr);
		offset += ret;
		index += offset >> PAGE_CACHE_SHIFT;
		offset &= ~PAGE_CACHE_MASK;

		page_cache_release(page);
		if (ret != nr || !desc->count)
			break;

		cond_resched();
	}

	*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
	file_accessed(filp);
}

static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
{
	read_descriptor_t desc;

	if ((ssize_t) count < 0)
		return -EINVAL;
	if (!access_ok(VERIFY_WRITE, buf, count))
		return -EFAULT;
	if (!count)
		return 0;

	desc.written = 0;
	desc.count = count;
	desc.arg.buf = buf;
	desc.error = 0;

	do_shmem_file_read(filp, ppos, &desc, file_read_actor);
	if (desc.written)
		return desc.written;
	return desc.error;
}

static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
			 size_t count, read_actor_t actor, void *target)
{
	read_descriptor_t desc;

	if (!count)
		return 0;

	desc.written = 0;
	desc.count = count;
	desc.arg.data = target;
	desc.error = 0;

	do_shmem_file_read(in_file, ppos, &desc, actor);
	if (desc.written)
		return desc.written;
	return desc.error;
}

1662
static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds's avatar
Linus Torvalds committed
1663
{
1664
	struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
Linus Torvalds's avatar
Linus Torvalds committed
1665 1666 1667 1668

	buf->f_type = TMPFS_MAGIC;
	buf->f_bsize = PAGE_CACHE_SIZE;
	buf->f_namelen = NAME_MAX;
1669 1670
	spin_lock(&sbinfo->stat_lock);
	if (sbinfo->max_blocks) {
Linus Torvalds's avatar
Linus Torvalds committed
1671 1672
		buf->f_blocks = sbinfo->max_blocks;
		buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1673 1674
	}
	if (sbinfo->max_inodes) {
Linus Torvalds's avatar
Linus Torvalds committed
1675 1676 1677 1678
		buf->f_files = sbinfo->max_inodes;
		buf->f_ffree = sbinfo->free_inodes;
	}
	/* else leave those fields 0 like simple_statfs */
1679
	spin_unlock(&sbinfo->stat_lock);
Linus Torvalds's avatar
Linus Torvalds committed
1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692
	return 0;
}

/*
 * File creation. Allocate an inode, and we're done..
 */
static int
shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
{
	struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
	int error = -ENOSPC;

	if (inode) {
1693 1694 1695 1696 1697 1698 1699
		error = security_inode_init_security(inode, dir, NULL, NULL,
						     NULL);
		if (error) {
			if (error != -EOPNOTSUPP) {
				iput(inode);
				return error;
			}
1700 1701 1702 1703 1704
		}
		error = shmem_acl_init(inode, dir);
		if (error) {
			iput(inode);
			return error;
1705
		}
Linus Torvalds's avatar
Linus Torvalds committed
1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724
		if (dir->i_mode & S_ISGID) {
			inode->i_gid = dir->i_gid;
			if (S_ISDIR(mode))
				inode->i_mode |= S_ISGID;
		}
		dir->i_size += BOGO_DIRENT_SIZE;
		dir->i_ctime = dir->i_mtime = CURRENT_TIME;
		d_instantiate(dentry, inode);
		dget(dentry); /* Extra count - pin the dentry in core */
	}
	return error;
}

static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
	int error;

	if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
		return error;
1725
	inc_nlink(dir);
Linus Torvalds's avatar
Linus Torvalds committed
1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747
	return 0;
}

static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
		struct nameidata *nd)
{
	return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
}

/*
 * Link a file..
 */
static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = old_dentry->d_inode;
	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);

	/*
	 * No ordinary (disk based) filesystem counts links as inodes;
	 * but each new link needs a new dentry, pinning lowmem, and
	 * tmpfs dentries cannot be pruned until they are unlinked.
	 */
1748
	if (sbinfo->max_inodes) {
Linus Torvalds's avatar
Linus Torvalds committed
1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759
		spin_lock(&sbinfo->stat_lock);
		if (!sbinfo->free_inodes) {
			spin_unlock(&sbinfo->stat_lock);
			return -ENOSPC;
		}
		sbinfo->free_inodes--;
		spin_unlock(&sbinfo->stat_lock);
	}

	dir->i_size += BOGO_DIRENT_SIZE;
	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1760
	inc_nlink(inode);
Linus Torvalds's avatar
Linus Torvalds committed
1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772
	atomic_inc(&inode->i_count);	/* New dentry reference */
	dget(dentry);		/* Extra pinning count for the created dentry */
	d_instantiate(dentry, inode);
	return 0;
}

static int shmem_unlink(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;

	if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
		struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1773
		if (sbinfo->max_inodes) {
Linus Torvalds's avatar
Linus Torvalds committed
1774 1775 1776 1777 1778 1779 1780 1781
			spin_lock(&sbinfo->stat_lock);
			sbinfo->free_inodes++;
			spin_unlock(&sbinfo->stat_lock);
		}
	}

	dir->i_size -= BOGO_DIRENT_SIZE;
	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1782
	drop_nlink(inode);
Linus Torvalds's avatar
Linus Torvalds committed
1783 1784 1785 1786 1787 1788 1789 1790 1791
	dput(dentry);	/* Undo the count from "create" - this does all the work */
	return 0;
}

static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
{
	if (!simple_empty(dentry))
		return -ENOTEMPTY;

1792 1793
	drop_nlink(dentry->d_inode);
	drop_nlink(dir);
Linus Torvalds's avatar
Linus Torvalds committed
1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813
	return shmem_unlink(dir, dentry);
}

/*
 * The VFS layer already does all the dentry stuff for rename,
 * we just have to decrement the usage count for the target if
 * it exists so that the VFS layer correctly free's it when it
 * gets overwritten.
 */
static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
{
	struct inode *inode = old_dentry->d_inode;
	int they_are_dirs = S_ISDIR(inode->i_mode);

	if (!simple_empty(new_dentry))
		return -ENOTEMPTY;

	if (new_dentry->d_inode) {
		(void) shmem_unlink(new_dir, new_dentry);
		if (they_are_dirs)
1814
			drop_nlink(old_dir);
Linus Torvalds's avatar
Linus Torvalds committed
1815
	} else if (they_are_dirs) {
1816
		drop_nlink(old_dir);
1817
		inc_nlink(new_dir);
Linus Torvalds's avatar
Linus Torvalds committed
1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844
	}

	old_dir->i_size -= BOGO_DIRENT_SIZE;
	new_dir->i_size += BOGO_DIRENT_SIZE;
	old_dir->i_ctime = old_dir->i_mtime =
	new_dir->i_ctime = new_dir->i_mtime =
	inode->i_ctime = CURRENT_TIME;
	return 0;
}

static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
{
	int error;
	int len;
	struct inode *inode;
	struct page *page = NULL;
	char *kaddr;
	struct shmem_inode_info *info;

	len = strlen(symname) + 1;
	if (len > PAGE_CACHE_SIZE)
		return -ENAMETOOLONG;

	inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
	if (!inode)
		return -ENOSPC;

1845 1846 1847 1848 1849 1850 1851 1852 1853 1854
	error = security_inode_init_security(inode, dir, NULL, NULL,
					     NULL);
	if (error) {
		if (error != -EOPNOTSUPP) {
			iput(inode);
			return error;
		}
		error = 0;
	}

Linus Torvalds's avatar
Linus Torvalds committed
1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882
	info = SHMEM_I(inode);
	inode->i_size = len-1;
	if (len <= (char *)inode - (char *)info) {
		/* do it inline */
		memcpy(info, symname, len);
		inode->i_op = &shmem_symlink_inline_operations;
	} else {
		error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
		if (error) {
			iput(inode);
			return error;
		}
		inode->i_op = &shmem_symlink_inode_operations;
		kaddr = kmap_atomic(page, KM_USER0);
		memcpy(kaddr, symname, len);
		kunmap_atomic(kaddr, KM_USER0);
		set_page_dirty(page);
		page_cache_release(page);
	}
	if (dir->i_mode & S_ISGID)
		inode->i_gid = dir->i_gid;
	dir->i_size += BOGO_DIRENT_SIZE;
	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	d_instantiate(dentry, inode);
	dget(dentry);
	return 0;
}

1883
static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds's avatar
Linus Torvalds committed
1884 1885
{
	nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1886
	return NULL;
Linus Torvalds's avatar
Linus Torvalds committed
1887 1888
}

1889
static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds's avatar
Linus Torvalds committed
1890 1891 1892 1893
{
	struct page *page = NULL;
	int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
	nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1894
	return page;
Linus Torvalds's avatar
Linus Torvalds committed
1895 1896
}

1897
static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds's avatar
Linus Torvalds committed
1898 1899
{
	if (!IS_ERR(nd_get_link(nd))) {
1900
		struct page *page = cookie;
Linus Torvalds's avatar
Linus Torvalds committed
1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918
		kunmap(page);
		mark_page_accessed(page);
		page_cache_release(page);
	}
}

static struct inode_operations shmem_symlink_inline_operations = {
	.readlink	= generic_readlink,
	.follow_link	= shmem_follow_link_inline,
};

static struct inode_operations shmem_symlink_inode_operations = {
	.truncate	= shmem_truncate,
	.readlink	= generic_readlink,
	.follow_link	= shmem_follow_link,
	.put_link	= shmem_put_link,
};

1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950
#ifdef CONFIG_TMPFS_POSIX_ACL
/**
 * Superblocks without xattr inode operations will get security.* xattr
 * support from the VFS "for free". As soon as we have any other xattrs
 * like ACLs, we also need to implement the security.* handlers at
 * filesystem level, though.
 */

static size_t shmem_xattr_security_list(struct inode *inode, char *list,
					size_t list_len, const char *name,
					size_t name_len)
{
	return security_inode_listsecurity(inode, list, list_len);
}

static int shmem_xattr_security_get(struct inode *inode, const char *name,
				    void *buffer, size_t size)
{
	if (strcmp(name, "") == 0)
		return -EINVAL;
	return security_inode_getsecurity(inode, name, buffer, size,
					  -EOPNOTSUPP);
}

static int shmem_xattr_security_set(struct inode *inode, const char *name,
				    const void *value, size_t size, int flags)
{
	if (strcmp(name, "") == 0)
		return -EINVAL;
	return security_inode_setsecurity(inode, name, value, size, flags);
}

1951
static struct xattr_handler shmem_xattr_security_handler = {
1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965
	.prefix = XATTR_SECURITY_PREFIX,
	.list   = shmem_xattr_security_list,
	.get    = shmem_xattr_security_get,
	.set    = shmem_xattr_security_set,
};

static struct xattr_handler *shmem_xattr_handlers[] = {
	&shmem_xattr_acl_access_handler,
	&shmem_xattr_acl_default_handler,
	&shmem_xattr_security_handler,
	NULL
};
#endif

1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044
static struct dentry *shmem_get_parent(struct dentry *child)
{
	return ERR_PTR(-ESTALE);
}

static int shmem_match(struct inode *ino, void *vfh)
{
	__u32 *fh = vfh;
	__u64 inum = fh[2];
	inum = (inum << 32) | fh[1];
	return ino->i_ino == inum && fh[0] == ino->i_generation;
}

static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh)
{
	struct dentry *de = NULL;
	struct inode *inode;
	__u32 *fh = vfh;
	__u64 inum = fh[2];
	inum = (inum << 32) | fh[1];

	inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh);
	if (inode) {
		de = d_find_alias(inode);
		iput(inode);
	}

	return de? de: ERR_PTR(-ESTALE);
}

static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh,
		int len, int type,
		int (*acceptable)(void *context, struct dentry *de),
		void *context)
{
	if (len < 3)
		return ERR_PTR(-ESTALE);

	return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable,
							context);
}

static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
				int connectable)
{
	struct inode *inode = dentry->d_inode;

	if (*len < 3)
		return 255;

	if (hlist_unhashed(&inode->i_hash)) {
		/* Unfortunately insert_inode_hash is not idempotent,
		 * so as we hash inodes here rather than at creation
		 * time, we need a lock to ensure we only try
		 * to do it once
		 */
		static DEFINE_SPINLOCK(lock);
		spin_lock(&lock);
		if (hlist_unhashed(&inode->i_hash))
			__insert_inode_hash(inode,
					    inode->i_ino + inode->i_generation);
		spin_unlock(&lock);
	}

	fh[0] = inode->i_generation;
	fh[1] = inode->i_ino;
	fh[2] = ((__u64)inode->i_ino) >> 32;

	*len = 3;
	return 1;
}

static struct export_operations shmem_export_ops = {
	.get_parent     = shmem_get_parent,
	.get_dentry     = shmem_get_dentry,
	.encode_fh      = shmem_encode_fh,
	.decode_fh      = shmem_decode_fh,
};

2045 2046 2047
static int shmem_parse_options(char *options, int *mode, uid_t *uid,
	gid_t *gid, unsigned long *blocks, unsigned long *inodes,
	int *policy, nodemask_t *policy_nodes)
Linus Torvalds's avatar
Linus Torvalds committed
2048 2049 2050
{
	char *this_char, *value, *rest;

2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067
	while (options != NULL) {
		this_char = options;
		for (;;) {
			/*
			 * NUL-terminate this option: unfortunately,
			 * mount options form a comma-separated list,
			 * but mpol's nodelist may also contain commas.
			 */
			options = strchr(options, ',');
			if (options == NULL)
				break;
			options++;
			if (!isdigit(*options)) {
				options[-1] = '\0';
				break;
			}
		}
Linus Torvalds's avatar
Linus Torvalds committed
2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116
		if (!*this_char)
			continue;
		if ((value = strchr(this_char,'=')) != NULL) {
			*value++ = 0;
		} else {
			printk(KERN_ERR
			    "tmpfs: No value for mount option '%s'\n",
			    this_char);
			return 1;
		}

		if (!strcmp(this_char,"size")) {
			unsigned long long size;
			size = memparse(value,&rest);
			if (*rest == '%') {
				size <<= PAGE_SHIFT;
				size *= totalram_pages;
				do_div(size, 100);
				rest++;
			}
			if (*rest)
				goto bad_val;
			*blocks = size >> PAGE_CACHE_SHIFT;
		} else if (!strcmp(this_char,"nr_blocks")) {
			*blocks = memparse(value,&rest);
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"nr_inodes")) {
			*inodes = memparse(value,&rest);
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"mode")) {
			if (!mode)
				continue;
			*mode = simple_strtoul(value,&rest,8);
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"uid")) {
			if (!uid)
				continue;
			*uid = simple_strtoul(value,&rest,0);
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"gid")) {
			if (!gid)
				continue;
			*gid = simple_strtoul(value,&rest,0);
			if (*rest)
				goto bad_val;
2117
		} else if (!strcmp(this_char,"mpol")) {
2118
			if (shmem_parse_mpol(value,policy,policy_nodes))
2119
				goto bad_val;
Linus Torvalds's avatar
Linus Torvalds committed
2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137
		} else {
			printk(KERN_ERR "tmpfs: Bad mount option %s\n",
			       this_char);
			return 1;
		}
	}
	return 0;

bad_val:
	printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
	       value, this_char);
	return 1;

}

static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
{
	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2138 2139
	unsigned long max_blocks = sbinfo->max_blocks;
	unsigned long max_inodes = sbinfo->max_inodes;
2140 2141
	int policy = sbinfo->policy;
	nodemask_t policy_nodes = sbinfo->policy_nodes;
2142 2143 2144 2145
	unsigned long blocks;
	unsigned long inodes;
	int error = -EINVAL;

2146 2147
	if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks,
				&max_inodes, &policy, &policy_nodes))
2148
		return error;
Linus Torvalds's avatar
Linus Torvalds committed
2149

2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172
	spin_lock(&sbinfo->stat_lock);
	blocks = sbinfo->max_blocks - sbinfo->free_blocks;
	inodes = sbinfo->max_inodes - sbinfo->free_inodes;
	if (max_blocks < blocks)
		goto out;
	if (max_inodes < inodes)
		goto out;
	/*
	 * Those tests also disallow limited->unlimited while any are in
	 * use, so i_blocks will always be zero when max_blocks is zero;
	 * but we must separately disallow unlimited->limited, because
	 * in that case we have no record of how much is already in use.
	 */
	if (max_blocks && !sbinfo->max_blocks)
		goto out;
	if (max_inodes && !sbinfo->max_inodes)
		goto out;

	error = 0;
	sbinfo->max_blocks  = max_blocks;
	sbinfo->free_blocks = max_blocks - blocks;
	sbinfo->max_inodes  = max_inodes;
	sbinfo->free_inodes = max_inodes - inodes;
2173 2174
	sbinfo->policy = policy;
	sbinfo->policy_nodes = policy_nodes;
2175 2176 2177
out:
	spin_unlock(&sbinfo->stat_lock);
	return error;
Linus Torvalds's avatar
Linus Torvalds committed
2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195
}
#endif

static void shmem_put_super(struct super_block *sb)
{
	kfree(sb->s_fs_info);
	sb->s_fs_info = NULL;
}

static int shmem_fill_super(struct super_block *sb,
			    void *data, int silent)
{
	struct inode *inode;
	struct dentry *root;
	int mode   = S_IRWXUGO | S_ISVTX;
	uid_t uid = current->fsuid;
	gid_t gid = current->fsgid;
	int err = -ENOMEM;
2196
	struct shmem_sb_info *sbinfo;
Linus Torvalds's avatar
Linus Torvalds committed
2197 2198
	unsigned long blocks = 0;
	unsigned long inodes = 0;
2199 2200
	int policy = MPOL_DEFAULT;
	nodemask_t policy_nodes = node_online_map;
Linus Torvalds's avatar
Linus Torvalds committed
2201

2202
#ifdef CONFIG_TMPFS
Linus Torvalds's avatar
Linus Torvalds committed
2203 2204 2205 2206 2207 2208 2209 2210 2211 2212
	/*
	 * Per default we only allow half of the physical ram per
	 * tmpfs instance, limiting inodes to one per page of lowmem;
	 * but the internal instance is left unlimited.
	 */
	if (!(sb->s_flags & MS_NOUSER)) {
		blocks = totalram_pages / 2;
		inodes = totalram_pages - totalhigh_pages;
		if (inodes > blocks)
			inodes = blocks;
2213 2214
		if (shmem_parse_options(data, &mode, &uid, &gid, &blocks,
					&inodes, &policy, &policy_nodes))
Linus Torvalds's avatar
Linus Torvalds committed
2215 2216
			return -EINVAL;
	}
2217
	sb->s_export_op = &shmem_export_ops;
Linus Torvalds's avatar
Linus Torvalds committed
2218 2219 2220 2221
#else
	sb->s_flags |= MS_NOUSER;
#endif

2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232
	/* Round up to L1_CACHE_BYTES to resist false sharing */
	sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
				L1_CACHE_BYTES), GFP_KERNEL);
	if (!sbinfo)
		return -ENOMEM;

	spin_lock_init(&sbinfo->stat_lock);
	sbinfo->max_blocks = blocks;
	sbinfo->free_blocks = blocks;
	sbinfo->max_inodes = inodes;
	sbinfo->free_inodes = inodes;
2233 2234
	sbinfo->policy = policy;
	sbinfo->policy_nodes = policy_nodes;
2235 2236

	sb->s_fs_info = sbinfo;
Linus Torvalds's avatar
Linus Torvalds committed
2237 2238 2239 2240 2241
	sb->s_maxbytes = SHMEM_MAX_BYTES;
	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	sb->s_magic = TMPFS_MAGIC;
	sb->s_op = &shmem_ops;
2242
	sb->s_time_gran = 1;
2243 2244 2245 2246
#ifdef CONFIG_TMPFS_POSIX_ACL
	sb->s_xattr = shmem_xattr_handlers;
	sb->s_flags |= MS_POSIXACL;
#endif
2247

Linus Torvalds's avatar
Linus Torvalds committed
2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265
	inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
	if (!inode)
		goto failed;
	inode->i_uid = uid;
	inode->i_gid = gid;
	root = d_alloc_root(inode);
	if (!root)
		goto failed_iput;
	sb->s_root = root;
	return 0;

failed_iput:
	iput(inode);
failed:
	shmem_put_super(sb);
	return err;
}

2266
static struct kmem_cache *shmem_inode_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
2267 2268 2269 2270

static struct inode *shmem_alloc_inode(struct super_block *sb)
{
	struct shmem_inode_info *p;
2271
	p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
Linus Torvalds's avatar
Linus Torvalds committed
2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282
	if (!p)
		return NULL;
	return &p->vfs_inode;
}

static void shmem_destroy_inode(struct inode *inode)
{
	if ((inode->i_mode & S_IFMT) == S_IFREG) {
		/* only struct inode is valid if it's an inline symlink */
		mpol_free_shared_policy(&SHMEM_I(inode)->policy);
	}
2283 <