1/*
   2 * Copyright (C) 2008 Oracle.  All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public
   6 * License v2 as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 * General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public
  14 * License along with this program; if not, write to the
  15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16 * Boston, MA 021110-1307, USA.
  17 */
  18
  19#include <linux/kernel.h>
  20#include <linux/bio.h>
  21#include <linux/buffer_head.h>
  22#include <linux/file.h>
  23#include <linux/fs.h>
  24#include <linux/pagemap.h>
 
  25#include <linux/highmem.h>
 
  26#include <linux/time.h>
  27#include <linux/init.h>
  28#include <linux/string.h>
  29#include <linux/backing-dev.h>
  30#include <linux/mpage.h>
  31#include <linux/swap.h>
  32#include <linux/writeback.h>
  33#include <linux/bit_spinlock.h>
  34#include <linux/slab.h>
  35#include "compat.h"
 
 
 
 
  36#include "ctree.h"
  37#include "disk-io.h"
  38#include "transaction.h"
  39#include "btrfs_inode.h"
  40#include "volumes.h"
  41#include "ordered-data.h"
  42#include "compression.h"
  43#include "extent_io.h"
  44#include "extent_map.h"
 
 
 
  45
  46struct compressed_bio {
  47	/* number of bios pending for this compressed extent */
  48	atomic_t pending_bios;
  49
  50	/* the pages with the compressed data on them */
  51	struct page **compressed_pages;
  52
  53	/* inode that owns this data */
  54	struct inode *inode;
 
 
 
 
 
 
 
 
 
  55
  56	/* starting offset in the inode for our pages */
  57	u64 start;
  58
  59	/* number of bytes in the inode we're working on */
  60	unsigned long len;
 
 
  61
  62	/* number of bytes on disk */
  63	unsigned long compressed_len;
 
 
 
  64
  65	/* the compression algorithm for this bio */
  66	int compress_type;
 
 
 
 
 
  67
  68	/* number of compressed pages in the array */
  69	unsigned long nr_pages;
 
  70
  71	/* IO errors */
  72	int errors;
  73	int mirror_num;
  74
  75	/* for reads, this is the bio we are copying the data into */
  76	struct bio *orig_bio;
  77
  78	/*
  79	 * the start of a variable length array of checksums only
  80	 * used by reads
  81	 */
  82	u32 sums;
  83};
  84
  85static inline int compressed_bio_size(struct btrfs_root *root,
  86				      unsigned long disk_size)
 
 
  87{
  88	u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
  89	return sizeof(struct compressed_bio) +
  90		((disk_size + root->sectorsize - 1) / root->sectorsize) *
  91		csum_size;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  92}
  93
  94static struct bio *compressed_bio_alloc(struct block_device *bdev,
  95					u64 first_byte, gfp_t gfp_flags)
  96{
  97	int nr_vecs;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  98
  99	nr_vecs = bio_get_nr_vecs(bdev);
 100	return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
 
 
 
 101}
 102
 103static int check_compressed_csum(struct inode *inode,
 104				 struct compressed_bio *cb,
 105				 u64 disk_start)
 
 
 
 
 
 
 
 
 
 
 
 106{
 107	int ret;
 108	struct btrfs_root *root = BTRFS_I(inode)->root;
 109	struct page *page;
 110	unsigned long i;
 111	char *kaddr;
 112	u32 csum;
 113	u32 *cb_sum = &cb->sums;
 114
 115	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
 116		return 0;
 
 
 
 
 117
 118	for (i = 0; i < cb->nr_pages; i++) {
 119		page = cb->compressed_pages[i];
 120		csum = ~(u32)0;
 121
 122		kaddr = kmap_atomic(page, KM_USER0);
 123		csum = btrfs_csum_data(root, kaddr, csum, PAGE_CACHE_SIZE);
 124		btrfs_csum_final(csum, (char *)&csum);
 125		kunmap_atomic(kaddr, KM_USER0);
 126
 127		if (csum != *cb_sum) {
 128			printk(KERN_INFO "btrfs csum failed ino %llu "
 129			       "extent %llu csum %u "
 130			       "wanted %u mirror %d\n",
 131			       (unsigned long long)btrfs_ino(inode),
 132			       (unsigned long long)disk_start,
 133			       csum, *cb_sum, cb->mirror_num);
 134			ret = -EIO;
 135			goto fail;
 136		}
 137		cb_sum++;
 
 
 
 138
 
 
 139	}
 140	ret = 0;
 141fail:
 142	return ret;
 143}
 144
 145/* when we finish reading compressed pages from the disk, we
 146 * decompress them and then run the bio end_io routines on the
 147 * decompressed pages (in the inode address space).
 148 *
 149 * This allows the checksumming and other IO error handling routines
 150 * to work normally
 151 *
 152 * The compressed pages are freed here, and it must be run
 153 * in process context
 154 */
 155static void end_compressed_bio_read(struct bio *bio, int err)
 156{
 157	struct compressed_bio *cb = bio->bi_private;
 158	struct inode *inode;
 159	struct page *page;
 160	unsigned long index;
 161	int ret;
 162
 163	if (err)
 164		cb->errors = 1;
 
 
 
 
 
 165
 166	/* if there are more bios still pending for this compressed
 167	 * extent, just exit
 168	 */
 169	if (!atomic_dec_and_test(&cb->pending_bios))
 170		goto out;
 171
 172	inode = cb->inode;
 173	ret = check_compressed_csum(inode, cb, (u64)bio->bi_sector << 9);
 174	if (ret)
 175		goto csum_failed;
 176
 177	/* ok, we're the last bio for this extent, lets start
 178	 * the decompression.
 179	 */
 180	ret = btrfs_decompress_biovec(cb->compress_type,
 181				      cb->compressed_pages,
 182				      cb->start,
 183				      cb->orig_bio->bi_io_vec,
 184				      cb->orig_bio->bi_vcnt,
 185				      cb->compressed_len);
 186csum_failed:
 187	if (ret)
 188		cb->errors = 1;
 189
 190	/* release the compressed pages */
 191	index = 0;
 192	for (index = 0; index < cb->nr_pages; index++) {
 193		page = cb->compressed_pages[index];
 194		page->mapping = NULL;
 195		page_cache_release(page);
 196	}
 197
 198	/* do io completion on the original bio */
 199	if (cb->errors) {
 200		bio_io_error(cb->orig_bio);
 201	} else {
 202		int bio_index = 0;
 203		struct bio_vec *bvec = cb->orig_bio->bi_io_vec;
 204
 205		/*
 206		 * we have verified the checksum already, set page
 207		 * checked so the end_io handlers know about it
 208		 */
 209		while (bio_index < cb->orig_bio->bi_vcnt) {
 210			SetPageChecked(bvec->bv_page);
 211			bvec++;
 212			bio_index++;
 213		}
 214		bio_endio(cb->orig_bio, 0);
 215	}
 
 216
 217	/* finally free the cb struct */
 218	kfree(cb->compressed_pages);
 219	kfree(cb);
 220out:
 221	bio_put(bio);
 
 
 
 
 
 
 
 
 
 
 
 
 
 222}
 223
 224/*
 225 * Clear the writeback bits on all of the file
 226 * pages for a compressed write
 227 */
 228static noinline int end_compressed_writeback(struct inode *inode, u64 start,
 229					     unsigned long ram_size)
 230{
 231	unsigned long index = start >> PAGE_CACHE_SHIFT;
 232	unsigned long end_index = (start + ram_size - 1) >> PAGE_CACHE_SHIFT;
 233	struct page *pages[16];
 234	unsigned long nr_pages = end_index - index + 1;
 
 
 235	int i;
 236	int ret;
 237
 238	while (nr_pages > 0) {
 239		ret = find_get_pages_contig(inode->i_mapping, index,
 240				     min_t(unsigned long,
 241				     nr_pages, ARRAY_SIZE(pages)), pages);
 242		if (ret == 0) {
 243			nr_pages -= 1;
 244			index += 1;
 245			continue;
 246		}
 
 
 247		for (i = 0; i < ret; i++) {
 248			end_page_writeback(pages[i]);
 249			page_cache_release(pages[i]);
 
 
 250		}
 251		nr_pages -= ret;
 252		index += ret;
 253	}
 254	/* the inode may be gone now */
 255	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 256}
 257
 258/*
 259 * do the cleanup once all the compressed pages hit the disk.
 260 * This will clear writeback on the file pages and free the compressed
 261 * pages.
 262 *
 263 * This also calls the writeback end hooks for the file pages so that
 264 * metadata and checksums can be updated in the file.
 265 */
 266static void end_compressed_bio_write(struct bio *bio, int err)
 267{
 268	struct extent_io_tree *tree;
 269	struct compressed_bio *cb = bio->bi_private;
 270	struct inode *inode;
 271	struct page *page;
 272	unsigned long index;
 273
 274	if (err)
 275		cb->errors = 1;
 276
 277	/* if there are more bios still pending for this compressed
 278	 * extent, just exit
 279	 */
 280	if (!atomic_dec_and_test(&cb->pending_bios))
 281		goto out;
 282
 283	/* ok, we're the last bio for this extent, step one is to
 284	 * call back into the FS and do all the end_io operations
 285	 */
 286	inode = cb->inode;
 287	tree = &BTRFS_I(inode)->io_tree;
 288	cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
 289	tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
 290					 cb->start,
 291					 cb->start + cb->len - 1,
 292					 NULL, 1);
 293	cb->compressed_pages[0]->mapping = NULL;
 294
 295	end_compressed_writeback(inode, cb->start, cb->len);
 296	/* note, our inode could be gone now */
 
 
 297
 298	/*
 299	 * release the compressed pages, these came from alloc_page and
 300	 * are not attached to the inode at all
 301	 */
 302	index = 0;
 303	for (index = 0; index < cb->nr_pages; index++) {
 304		page = cb->compressed_pages[index];
 305		page->mapping = NULL;
 306		page_cache_release(page);
 307	}
 308
 309	/* finally free the cb struct */
 310	kfree(cb->compressed_pages);
 311	kfree(cb);
 312out:
 313	bio_put(bio);
 314}
 315
 316/*
 317 * worker function to build and submit bios for previously compressed pages.
 318 * The corresponding pages in the inode should be marked for writeback
 319 * and the compressed pages should have a reference on them for dropping
 320 * when the IO is complete.
 321 *
 322 * This also checksums the file bytes and gets things ready for
 323 * the end io hooks.
 324 */
 325int btrfs_submit_compressed_write(struct inode *inode, u64 start,
 326				 unsigned long len, u64 disk_start,
 327				 unsigned long compressed_len,
 328				 struct page **compressed_pages,
 329				 unsigned long nr_pages)
 330{
 331	struct bio *bio = NULL;
 332	struct btrfs_root *root = BTRFS_I(inode)->root;
 333	struct compressed_bio *cb;
 334	unsigned long bytes_left;
 335	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 336	int pg_index = 0;
 337	struct page *page;
 338	u64 first_byte = disk_start;
 339	struct block_device *bdev;
 340	int ret;
 341	int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
 342
 343	WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
 344	cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
 345	if (!cb)
 346		return -ENOMEM;
 347	atomic_set(&cb->pending_bios, 0);
 348	cb->errors = 0;
 349	cb->inode = inode;
 350	cb->start = start;
 351	cb->len = len;
 352	cb->mirror_num = 0;
 353	cb->compressed_pages = compressed_pages;
 354	cb->compressed_len = compressed_len;
 355	cb->orig_bio = NULL;
 356	cb->nr_pages = nr_pages;
 357
 358	bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
 359
 360	bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
 361	if(!bio) {
 362		kfree(cb);
 363		return -ENOMEM;
 364	}
 365	bio->bi_private = cb;
 366	bio->bi_end_io = end_compressed_bio_write;
 367	atomic_inc(&cb->pending_bios);
 368
 369	/* create and submit bios for the compressed pages */
 370	bytes_left = compressed_len;
 371	for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
 372		page = compressed_pages[pg_index];
 373		page->mapping = inode->i_mapping;
 374		if (bio->bi_size)
 375			ret = io_tree->ops->merge_bio_hook(page, 0,
 376							   PAGE_CACHE_SIZE,
 377							   bio, 0);
 378		else
 379			ret = 0;
 380
 381		page->mapping = NULL;
 382		if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
 383		    PAGE_CACHE_SIZE) {
 384			bio_get(bio);
 385
 386			/*
 387			 * inc the count before we submit the bio so
 388			 * we know the end IO handler won't happen before
 389			 * we inc the count.  Otherwise, the cb might get
 390			 * freed before we're done setting it up
 391			 */
 392			atomic_inc(&cb->pending_bios);
 393			ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
 394			BUG_ON(ret);
 395
 396			if (!skip_sum) {
 397				ret = btrfs_csum_one_bio(root, inode, bio,
 398							 start, 1);
 399				BUG_ON(ret);
 400			}
 401
 402			ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
 403			BUG_ON(ret);
 404
 405			bio_put(bio);
 406
 407			bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
 408			bio->bi_private = cb;
 409			bio->bi_end_io = end_compressed_bio_write;
 410			bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
 411		}
 412		if (bytes_left < PAGE_CACHE_SIZE) {
 413			printk("bytes left %lu compress len %lu nr %lu\n",
 414			       bytes_left, cb->compressed_len, cb->nr_pages);
 415		}
 416		bytes_left -= PAGE_CACHE_SIZE;
 417		first_byte += PAGE_CACHE_SIZE;
 418		cond_resched();
 419	}
 420	bio_get(bio);
 421
 422	ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
 423	BUG_ON(ret);
 424
 425	if (!skip_sum) {
 426		ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
 427		BUG_ON(ret);
 428	}
 429
 430	ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
 431	BUG_ON(ret);
 
 
 
 
 
 
 
 
 
 
 
 432
 433	bio_put(bio);
 434	return 0;
 435}
 436
 
 
 
 
 
 
 
 
 
 
 
 437static noinline int add_ra_bio_pages(struct inode *inode,
 438				     u64 compressed_end,
 439				     struct compressed_bio *cb)
 
 440{
 
 441	unsigned long end_index;
 442	unsigned long pg_index;
 443	u64 last_offset;
 444	u64 isize = i_size_read(inode);
 445	int ret;
 446	struct page *page;
 447	unsigned long nr_pages = 0;
 448	struct extent_map *em;
 449	struct address_space *mapping = inode->i_mapping;
 450	struct extent_map_tree *em_tree;
 451	struct extent_io_tree *tree;
 452	u64 end;
 453	int misses = 0;
 454
 455	page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page;
 456	last_offset = (page_offset(page) + PAGE_CACHE_SIZE);
 457	em_tree = &BTRFS_I(inode)->extent_tree;
 458	tree = &BTRFS_I(inode)->io_tree;
 459
 460	if (isize == 0)
 461		return 0;
 462
 463	end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 
 
 
 
 
 
 
 
 464
 465	while (last_offset < compressed_end) {
 466		pg_index = last_offset >> PAGE_CACHE_SHIFT;
 
 
 
 
 467
 468		if (pg_index > end_index)
 469			break;
 470
 471		rcu_read_lock();
 472		page = radix_tree_lookup(&mapping->page_tree, pg_index);
 473		rcu_read_unlock();
 474		if (page) {
 475			misses++;
 476			if (misses > 4)
 
 
 
 
 
 477				break;
 478			goto next;
 
 
 
 
 
 
 479		}
 480
 481		page = __page_cache_alloc(mapping_gfp_mask(mapping) &
 482								~__GFP_FS);
 483		if (!page)
 484			break;
 485
 486		if (add_to_page_cache_lru(page, mapping, pg_index,
 487								GFP_NOFS)) {
 488			page_cache_release(page);
 489			goto next;
 
 490		}
 491
 492		end = last_offset + PAGE_CACHE_SIZE - 1;
 493		/*
 494		 * at this point, we have a locked page in the page cache
 495		 * for these bytes in the file.  But, we have to make
 496		 * sure they map to this compressed extent on disk.
 497		 */
 498		set_page_extent_mapped(page);
 499		lock_extent(tree, last_offset, end, GFP_NOFS);
 
 
 
 
 
 
 500		read_lock(&em_tree->lock);
 501		em = lookup_extent_mapping(em_tree, last_offset,
 502					   PAGE_CACHE_SIZE);
 503		read_unlock(&em_tree->lock);
 504
 505		if (!em || last_offset < em->start ||
 506		    (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) ||
 507		    (em->block_start >> 9) != cb->orig_bio->bi_sector) {
 
 
 
 
 
 
 508			free_extent_map(em);
 509			unlock_extent(tree, last_offset, end, GFP_NOFS);
 510			unlock_page(page);
 511			page_cache_release(page);
 512			break;
 513		}
 
 514		free_extent_map(em);
 
 515
 516		if (page->index == end_index) {
 517			char *userpage;
 518			size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1);
 519
 520			if (zero_offset) {
 521				int zeros;
 522				zeros = PAGE_CACHE_SIZE - zero_offset;
 523				userpage = kmap_atomic(page, KM_USER0);
 524				memset(userpage + zero_offset, 0, zeros);
 525				flush_dcache_page(page);
 526				kunmap_atomic(userpage, KM_USER0);
 527			}
 528		}
 529
 530		ret = bio_add_page(cb->orig_bio, page,
 531				   PAGE_CACHE_SIZE, 0);
 532
 533		if (ret == PAGE_CACHE_SIZE) {
 534			nr_pages++;
 535			page_cache_release(page);
 536		} else {
 537			unlock_extent(tree, last_offset, end, GFP_NOFS);
 538			unlock_page(page);
 539			page_cache_release(page);
 540			break;
 541		}
 542next:
 543		last_offset += PAGE_CACHE_SIZE;
 
 
 
 
 
 
 
 544	}
 545	return 0;
 546}
 547
 548/*
 549 * for a compressed read, the bio we get passed has all the inode pages
 550 * in it.  We don't actually do IO on those pages but allocate new ones
 551 * to hold the compressed pages on disk.
 552 *
 553 * bio->bi_sector points to the compressed extent on disk
 554 * bio->bi_io_vec points to all of the inode pages
 555 * bio->bi_vcnt is a count of pages
 556 *
 557 * After the compressed pages are read, we copy the bytes into the
 558 * bio we were passed and then call the bio end_io calls
 559 */
 560int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 561				 int mirror_num, unsigned long bio_flags)
 562{
 563	struct extent_io_tree *tree;
 564	struct extent_map_tree *em_tree;
 
 565	struct compressed_bio *cb;
 566	struct btrfs_root *root = BTRFS_I(inode)->root;
 567	unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
 568	unsigned long compressed_len;
 569	unsigned long nr_pages;
 570	unsigned long pg_index;
 571	struct page *page;
 572	struct block_device *bdev;
 573	struct bio *comp_bio;
 574	u64 cur_disk_byte = (u64)bio->bi_sector << 9;
 575	u64 em_len;
 576	u64 em_start;
 577	struct extent_map *em;
 578	int ret = -ENOMEM;
 579	u32 *sums;
 580
 581	tree = &BTRFS_I(inode)->io_tree;
 582	em_tree = &BTRFS_I(inode)->extent_tree;
 583
 584	/* we need the actual starting offset of this extent in the file */
 585	read_lock(&em_tree->lock);
 586	em = lookup_extent_mapping(em_tree,
 587				   page_offset(bio->bi_io_vec->bv_page),
 588				   PAGE_CACHE_SIZE);
 589	read_unlock(&em_tree->lock);
 590
 591	compressed_len = em->block_len;
 592	cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
 593	if (!cb)
 594		goto out;
 
 
 
 
 595
 596	atomic_set(&cb->pending_bios, 0);
 597	cb->errors = 0;
 598	cb->inode = inode;
 599	cb->mirror_num = mirror_num;
 600	sums = &cb->sums;
 601
 602	cb->start = em->orig_start;
 603	em_len = em->len;
 604	em_start = em->start;
 605
 
 
 
 
 
 606	free_extent_map(em);
 607	em = NULL;
 608
 609	cb->len = uncompressed_len;
 610	cb->compressed_len = compressed_len;
 611	cb->compress_type = extent_compress_type(bio_flags);
 612	cb->orig_bio = bio;
 
 
 613
 614	nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
 615				 PAGE_CACHE_SIZE;
 616	cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages,
 617				       GFP_NOFS);
 618	if (!cb->compressed_pages)
 619		goto fail1;
 620
 621	bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
 622
 623	for (pg_index = 0; pg_index < nr_pages; pg_index++) {
 624		cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
 625							      __GFP_HIGHMEM);
 626		if (!cb->compressed_pages[pg_index])
 627			goto fail2;
 628	}
 629	cb->nr_pages = nr_pages;
 630
 631	add_ra_bio_pages(inode, em_start + em_len, cb);
 
 632
 633	/* include any pages we added in add_ra-bio_pages */
 634	uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
 635	cb->len = uncompressed_len;
 636
 637	comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
 638	if (!comp_bio)
 639		goto fail2;
 640	comp_bio->bi_private = cb;
 641	comp_bio->bi_end_io = end_compressed_bio_read;
 642	atomic_inc(&cb->pending_bios);
 643
 644	for (pg_index = 0; pg_index < nr_pages; pg_index++) {
 645		page = cb->compressed_pages[pg_index];
 646		page->mapping = inode->i_mapping;
 647		page->index = em_start >> PAGE_CACHE_SHIFT;
 648
 649		if (comp_bio->bi_size)
 650			ret = tree->ops->merge_bio_hook(page, 0,
 651							PAGE_CACHE_SIZE,
 652							comp_bio, 0);
 653		else
 654			ret = 0;
 655
 656		page->mapping = NULL;
 657		if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
 658		    PAGE_CACHE_SIZE) {
 659			bio_get(comp_bio);
 660
 661			ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
 662			BUG_ON(ret);
 
 
 
 
 
 
 
 663
 664			/*
 665			 * inc the count before we submit the bio so
 666			 * we know the end IO handler won't happen before
 667			 * we inc the count.  Otherwise, the cb might get
 668			 * freed before we're done setting it up
 669			 */
 670			atomic_inc(&cb->pending_bios);
 671
 672			if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
 673				ret = btrfs_lookup_bio_sums(root, inode,
 674							comp_bio, sums);
 675				BUG_ON(ret);
 676			}
 677			sums += (comp_bio->bi_size + root->sectorsize - 1) /
 678				root->sectorsize;
 
 
 
 
 
 
 
 679
 680			ret = btrfs_map_bio(root, READ, comp_bio,
 681					    mirror_num, 0);
 682			BUG_ON(ret);
 683
 684			bio_put(comp_bio);
 
 
 
 
 
 
 
 
 
 685
 686			comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
 687							GFP_NOFS);
 688			comp_bio->bi_private = cb;
 689			comp_bio->bi_end_io = end_compressed_bio_read;
 690
 691			bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
 692		}
 693		cur_disk_byte += PAGE_CACHE_SIZE;
 694	}
 695	bio_get(comp_bio);
 696
 697	ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
 698	BUG_ON(ret);
 699
 700	if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
 701		ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
 702		BUG_ON(ret);
 703	}
 
 704
 705	ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
 706	BUG_ON(ret);
 
 707
 708	bio_put(comp_bio);
 709	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 710
 711fail2:
 712	for (pg_index = 0; pg_index < nr_pages; pg_index++)
 713		free_page((unsigned long)cb->compressed_pages[pg_index]);
 714
 715	kfree(cb->compressed_pages);
 716fail1:
 717	kfree(cb);
 718out:
 719	free_extent_map(em);
 720	return ret;
 721}
 722
 723static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES];
 724static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES];
 725static int comp_num_workspace[BTRFS_COMPRESS_TYPES];
 726static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES];
 727static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES];
 728
 729struct btrfs_compress_op *btrfs_compress_op[] = {
 
 
 730	&btrfs_zlib_compress,
 731	&btrfs_lzo_compress,
 
 732};
 733
 734int __init btrfs_init_compress(void)
 735{
 736	int i;
 
 
 
 
 
 
 
 
 
 
 
 
 737
 738	for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
 739		INIT_LIST_HEAD(&comp_idle_workspace[i]);
 740		spin_lock_init(&comp_workspace_lock[i]);
 741		atomic_set(&comp_alloc_workspace[i], 0);
 742		init_waitqueue_head(&comp_workspace_wait[i]);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 743	}
 744	return 0;
 745}
 746
 747/*
 748 * this finds an available workspace or allocates a new one
 749 * ERR_PTR is returned if things go bad.
 
 
 750 */
 751static struct list_head *find_workspace(int type)
 752{
 
 753	struct list_head *workspace;
 754	int cpus = num_online_cpus();
 755	int idx = type - 1;
 
 
 
 
 
 
 
 
 
 
 
 
 756
 757	struct list_head *idle_workspace	= &comp_idle_workspace[idx];
 758	spinlock_t *workspace_lock		= &comp_workspace_lock[idx];
 759	atomic_t *alloc_workspace		= &comp_alloc_workspace[idx];
 760	wait_queue_head_t *workspace_wait	= &comp_workspace_wait[idx];
 761	int *num_workspace			= &comp_num_workspace[idx];
 762again:
 763	spin_lock(workspace_lock);
 764	if (!list_empty(idle_workspace)) {
 765		workspace = idle_workspace->next;
 766		list_del(workspace);
 767		(*num_workspace)--;
 768		spin_unlock(workspace_lock);
 769		return workspace;
 770
 771	}
 772	if (atomic_read(alloc_workspace) > cpus) {
 773		DEFINE_WAIT(wait);
 774
 775		spin_unlock(workspace_lock);
 776		prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
 777		if (atomic_read(alloc_workspace) > cpus && !*num_workspace)
 778			schedule();
 779		finish_wait(workspace_wait, &wait);
 780		goto again;
 781	}
 782	atomic_inc(alloc_workspace);
 783	spin_unlock(workspace_lock);
 
 
 
 
 
 
 
 
 
 784
 785	workspace = btrfs_compress_op[idx]->alloc_workspace();
 786	if (IS_ERR(workspace)) {
 787		atomic_dec(alloc_workspace);
 788		wake_up(workspace_wait);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 789	}
 790	return workspace;
 791}
 792
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 793/*
 794 * put a workspace struct back on the list or free it if we have enough
 795 * idle ones sitting around
 796 */
 797static void free_workspace(int type, struct list_head *workspace)
 798{
 799	int idx = type - 1;
 800	struct list_head *idle_workspace	= &comp_idle_workspace[idx];
 801	spinlock_t *workspace_lock		= &comp_workspace_lock[idx];
 802	atomic_t *alloc_workspace		= &comp_alloc_workspace[idx];
 803	wait_queue_head_t *workspace_wait	= &comp_workspace_wait[idx];
 804	int *num_workspace			= &comp_num_workspace[idx];
 805
 806	spin_lock(workspace_lock);
 807	if (*num_workspace < num_online_cpus()) {
 808		list_add_tail(workspace, idle_workspace);
 809		(*num_workspace)++;
 810		spin_unlock(workspace_lock);
 
 
 
 
 
 
 
 811		goto wake;
 812	}
 813	spin_unlock(workspace_lock);
 814
 815	btrfs_compress_op[idx]->free_workspace(workspace);
 816	atomic_dec(alloc_workspace);
 817wake:
 818	if (waitqueue_active(workspace_wait))
 819		wake_up(workspace_wait);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 820}
 821
 822/*
 823 * cleanup function for module exit
 
 824 */
 825static void free_workspaces(void)
 826{
 827	struct list_head *workspace;
 828	int i;
 829
 830	for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
 831		while (!list_empty(&comp_idle_workspace[i])) {
 832			workspace = comp_idle_workspace[i].next;
 833			list_del(workspace);
 834			btrfs_compress_op[i]->free_workspace(workspace);
 835			atomic_dec(&comp_alloc_workspace[i]);
 836		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 837	}
 
 
 838}
 839
 840/*
 841 * given an address space and start/len, compress the bytes.
 
 842 *
 843 * pages are allocated to hold the compressed result and stored
 844 * in 'pages'
 
 
 845 *
 846 * out_pages is used to return the number of pages allocated.  There
 847 * may be pages allocated even if we return an error
 848 *
 849 * total_in is used to return the number of bytes actually read.  It
 850 * may be smaller then len if we had to exit early because we
 851 * ran out of room in the pages array or because we cross the
 852 * max_out threshold.
 853 *
 854 * total_out is used to return the total number of compressed bytes
 855 *
 856 * max_out tells us the max number of bytes that we're allowed to
 857 * stuff into pages
 858 */
 859int btrfs_compress_pages(int type, struct address_space *mapping,
 860			 u64 start, unsigned long len,
 861			 struct page **pages,
 862			 unsigned long nr_dest_pages,
 863			 unsigned long *out_pages,
 864			 unsigned long *total_in,
 865			 unsigned long *total_out,
 866			 unsigned long max_out)
 867{
 
 
 
 868	struct list_head *workspace;
 869	int ret;
 870
 871	workspace = find_workspace(type);
 872	if (IS_ERR(workspace))
 873		return -1;
 874
 875	ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
 876						      start, len, pages,
 877						      nr_dest_pages, out_pages,
 878						      total_in, total_out,
 879						      max_out);
 880	free_workspace(type, workspace);
 881	return ret;
 882}
 883
 884/*
 885 * pages_in is an array of pages with compressed data.
 886 *
 887 * disk_start is the starting logical offset of this array in the file
 888 *
 889 * bvec is a bio_vec of pages from the file that we want to decompress into
 890 *
 891 * vcnt is the count of pages in the biovec
 892 *
 893 * srclen is the number of bytes in pages_in
 894 *
 895 * The basic idea is that we have a bio that was created by readpages.
 896 * The pages in the bio are for the uncompressed data, and they may not
 897 * be contiguous.  They all correspond to the range of bytes covered by
 898 * the compressed extent.
 899 */
 900int btrfs_decompress_biovec(int type, struct page **pages_in, u64 disk_start,
 901			    struct bio_vec *bvec, int vcnt, size_t srclen)
 902{
 903	struct list_head *workspace;
 904	int ret;
 
 905
 906	workspace = find_workspace(type);
 907	if (IS_ERR(workspace))
 908		return -ENOMEM;
 909
 910	ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
 911							 disk_start,
 912							 bvec, vcnt, srclen);
 913	free_workspace(type, workspace);
 914	return ret;
 915}
 916
 917/*
 918 * a less complex decompression routine.  Our compressed data fits in a
 919 * single page, and we want to read a single page out of it.
 920 * start_byte tells us the offset into the compressed data we're interested in
 921 */
 922int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
 923		     unsigned long start_byte, size_t srclen, size_t destlen)
 924{
 
 925	struct list_head *workspace;
 
 926	int ret;
 927
 928	workspace = find_workspace(type);
 929	if (IS_ERR(workspace))
 930		return -ENOMEM;
 
 
 
 931
 932	ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
 933						  dest_page, start_byte,
 934						  srclen, destlen);
 
 935
 936	free_workspace(type, workspace);
 937	return ret;
 938}
 939
 940void btrfs_exit_compress(void)
 941{
 942	free_workspaces();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 943}
 944
 945/*
 946 * Copy uncompressed data from working buffer to pages.
 
 
 
 
 947 *
 948 * buf_start is the byte offset we're of the start of our workspace buffer.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 949 *
 950 * total_out is the last byte of the buffer
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 951 */
 952int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
 953			      unsigned long total_out, u64 disk_start,
 954			      struct bio_vec *bvec, int vcnt,
 955			      unsigned long *pg_index,
 956			      unsigned long *pg_offset)
 957{
 958	unsigned long buf_offset;
 959	unsigned long current_buf_start;
 960	unsigned long start_byte;
 961	unsigned long working_bytes = total_out - buf_start;
 962	unsigned long bytes;
 963	char *kaddr;
 964	struct page *page_out = bvec[*pg_index].bv_page;
 965
 966	/*
 967	 * start byte is the first byte of the page we're currently
 968	 * copying into relative to the start of the compressed data.
 
 969	 */
 970	start_byte = page_offset(page_out) - disk_start;
 
 
 
 
 
 
 971
 972	/* we haven't yet hit data corresponding to this page */
 973	if (total_out <= start_byte)
 974		return 1;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 975
 976	/*
 977	 * the start of the data we care about is offset into
 978	 * the middle of our working buffer
 
 
 
 
 
 979	 */
 980	if (total_out > start_byte && buf_start < start_byte) {
 981		buf_offset = start_byte - buf_start;
 982		working_bytes -= buf_offset;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 983	} else {
 984		buf_offset = 0;
 
 985	}
 986	current_buf_start = buf_start;
 987
 988	/* copy bytes from the working buffer into the pages */
 989	while (working_bytes > 0) {
 990		bytes = min(PAGE_CACHE_SIZE - *pg_offset,
 991			    PAGE_CACHE_SIZE - buf_offset);
 992		bytes = min(bytes, working_bytes);
 993		kaddr = kmap_atomic(page_out, KM_USER0);
 994		memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
 995		kunmap_atomic(kaddr, KM_USER0);
 996		flush_dcache_page(page_out);
 997
 998		*pg_offset += bytes;
 999		buf_offset += bytes;
1000		working_bytes -= bytes;
1001		current_buf_start += bytes;
1002
1003		/* check if we need to pick another page */
1004		if (*pg_offset == PAGE_CACHE_SIZE) {
1005			(*pg_index)++;
1006			if (*pg_index >= vcnt)
1007				return 0;
1008
1009			page_out = bvec[*pg_index].bv_page;
1010			*pg_offset = 0;
1011			start_byte = page_offset(page_out) - disk_start;
1012
1013			/*
1014			 * make sure our new page is covered by this
1015			 * working buffer
1016			 */
1017			if (total_out <= start_byte)
1018				return 1;
 
 
1019
1020			/*
1021			 * the next page in the biovec might not be adjacent
1022			 * to the last page, but it might still be found
1023			 * inside this working buffer. bump our offset pointer
1024			 */
1025			if (total_out > start_byte &&
1026			    current_buf_start < start_byte) {
1027				buf_offset = start_byte - buf_start;
1028				working_bytes = total_out - start_byte;
1029				current_buf_start = buf_start + buf_offset;
1030			}
1031		}
1032	}
1033
1034	return 1;
 
 
1035}