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 "ctree.h"
  36#include "disk-io.h"
  37#include "transaction.h"
  38#include "btrfs_inode.h"
  39#include "volumes.h"
  40#include "ordered-data.h"
  41#include "compression.h"
  42#include "extent_io.h"
  43#include "extent_map.h"
 
 
 
  44
  45struct compressed_bio {
  46	/* number of bios pending for this compressed extent */
  47	atomic_t pending_bios;
  48
  49	/* the pages with the compressed data on them */
  50	struct page **compressed_pages;
  51
  52	/* inode that owns this data */
  53	struct inode *inode;
  54
  55	/* starting offset in the inode for our pages */
  56	u64 start;
 
 
 
 
 
 
 
 
 
  57
  58	/* number of bytes in the inode we're working on */
  59	unsigned long len;
  60
  61	/* number of bytes on disk */
  62	unsigned long compressed_len;
 
 
  63
  64	/* the compression algorithm for this bio */
  65	int compress_type;
 
 
 
  66
  67	/* number of compressed pages in the array */
  68	unsigned long nr_pages;
 
 
 
 
 
  69
  70	/* IO errors */
  71	int errors;
  72	int mirror_num;
  73
  74	/* for reads, this is the bio we are copying the data into */
  75	struct bio *orig_bio;
  76
  77	/*
  78	 * the start of a variable length array of checksums only
  79	 * used by reads
  80	 */
  81	u32 sums;
  82};
  83
  84static int btrfs_decompress_biovec(int type, struct page **pages_in,
  85				   u64 disk_start, struct bio_vec *bvec,
  86				   int vcnt, size_t srclen);
 
 
  87
  88static inline int compressed_bio_size(struct btrfs_root *root,
  89				      unsigned long disk_size)
 
 
  90{
  91	u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  92
  93	return sizeof(struct compressed_bio) +
  94		((disk_size + root->sectorsize - 1) / root->sectorsize) *
  95		csum_size;
 
 
 
 
 
 
 
 
 
 
 
 
  96}
  97
  98static struct bio *compressed_bio_alloc(struct block_device *bdev,
  99					u64 first_byte, gfp_t gfp_flags)
 
 100{
 101	int nr_vecs;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 102
 103	nr_vecs = bio_get_nr_vecs(bdev);
 104	return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
 
 
 
 105}
 106
 107static int check_compressed_csum(struct inode *inode,
 108				 struct compressed_bio *cb,
 109				 u64 disk_start)
 
 
 
 
 
 
 
 
 
 
 
 110{
 111	int ret;
 112	struct page *page;
 113	unsigned long i;
 114	char *kaddr;
 115	u32 csum;
 116	u32 *cb_sum = &cb->sums;
 117
 118	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
 119		return 0;
 
 
 
 
 120
 121	for (i = 0; i < cb->nr_pages; i++) {
 122		page = cb->compressed_pages[i];
 123		csum = ~(u32)0;
 124
 125		kaddr = kmap_atomic(page);
 126		csum = btrfs_csum_data(kaddr, csum, PAGE_CACHE_SIZE);
 127		btrfs_csum_final(csum, (char *)&csum);
 128		kunmap_atomic(kaddr);
 129
 130		if (csum != *cb_sum) {
 131			btrfs_info(BTRFS_I(inode)->root->fs_info,
 132			   "csum failed ino %llu extent %llu csum %u wanted %u mirror %d",
 133			   btrfs_ino(inode), disk_start, csum, *cb_sum,
 134			   cb->mirror_num);
 135			ret = -EIO;
 136			goto fail;
 137		}
 138		cb_sum++;
 
 
 139
 
 
 
 
 
 140	}
 141	ret = 0;
 142fail:
 143	return ret;
 144}
 145
 146/* when we finish reading compressed pages from the disk, we
 147 * decompress them and then run the bio end_io routines on the
 148 * decompressed pages (in the inode address space).
 149 *
 150 * This allows the checksumming and other IO error handling routines
 151 * to work normally
 152 *
 153 * The compressed pages are freed here, and it must be run
 154 * in process context
 155 */
 156static void end_compressed_bio_read(struct bio *bio, int err)
 157{
 158	struct compressed_bio *cb = bio->bi_private;
 159	struct inode *inode;
 160	struct page *page;
 161	unsigned long index;
 162	int ret;
 163
 164	if (err)
 165		cb->errors = 1;
 
 
 
 
 
 166
 167	/* if there are more bios still pending for this compressed
 168	 * extent, just exit
 169	 */
 170	if (!atomic_dec_and_test(&cb->pending_bios))
 171		goto out;
 172
 173	inode = cb->inode;
 174	ret = check_compressed_csum(inode, cb,
 175				    (u64)bio->bi_iter.bi_sector << 9);
 176	if (ret)
 177		goto csum_failed;
 178
 179	/* ok, we're the last bio for this extent, lets start
 180	 * the decompression.
 181	 */
 182	ret = btrfs_decompress_biovec(cb->compress_type,
 183				      cb->compressed_pages,
 184				      cb->start,
 185				      cb->orig_bio->bi_io_vec,
 186				      cb->orig_bio->bi_vcnt,
 187				      cb->compressed_len);
 188csum_failed:
 189	if (ret)
 190		cb->errors = 1;
 191
 192	/* release the compressed pages */
 193	index = 0;
 194	for (index = 0; index < cb->nr_pages; index++) {
 195		page = cb->compressed_pages[index];
 196		page->mapping = NULL;
 197		page_cache_release(page);
 198	}
 199
 200	/* do io completion on the original bio */
 201	if (cb->errors) {
 202		bio_io_error(cb->orig_bio);
 203	} else {
 204		int i;
 205		struct bio_vec *bvec;
 
 
 206
 207		/*
 208		 * we have verified the checksum already, set page
 209		 * checked so the end_io handlers know about it
 210		 */
 211		bio_for_each_segment_all(bvec, cb->orig_bio, i)
 212			SetPageChecked(bvec->bv_page);
 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 void 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}
 256
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 257/*
 258 * do the cleanup once all the compressed pages hit the disk.
 259 * This will clear writeback on the file pages and free the compressed
 260 * pages.
 261 *
 262 * This also calls the writeback end hooks for the file pages so that
 263 * metadata and checksums can be updated in the file.
 264 */
 265static void end_compressed_bio_write(struct bio *bio, int err)
 266{
 267	struct extent_io_tree *tree;
 268	struct compressed_bio *cb = bio->bi_private;
 269	struct inode *inode;
 270	struct page *page;
 271	unsigned long index;
 272
 273	if (err)
 274		cb->errors = 1;
 275
 276	/* if there are more bios still pending for this compressed
 277	 * extent, just exit
 278	 */
 279	if (!atomic_dec_and_test(&cb->pending_bios))
 280		goto out;
 281
 282	/* ok, we're the last bio for this extent, step one is to
 283	 * call back into the FS and do all the end_io operations
 284	 */
 285	inode = cb->inode;
 286	tree = &BTRFS_I(inode)->io_tree;
 287	cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
 288	tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
 289					 cb->start,
 290					 cb->start + cb->len - 1,
 291					 NULL, 1);
 292	cb->compressed_pages[0]->mapping = NULL;
 293
 294	end_compressed_writeback(inode, cb->start, cb->len);
 295	/* note, our inode could be gone now */
 296
 297	/*
 298	 * release the compressed pages, these came from alloc_page and
 299	 * are not attached to the inode at all
 300	 */
 301	index = 0;
 302	for (index = 0; index < cb->nr_pages; index++) {
 303		page = cb->compressed_pages[index];
 304		page->mapping = NULL;
 305		page_cache_release(page);
 306	}
 307
 308	/* finally free the cb struct */
 309	kfree(cb->compressed_pages);
 310	kfree(cb);
 311out:
 312	bio_put(bio);
 313}
 314
 315/*
 316 * worker function to build and submit bios for previously compressed pages.
 317 * The corresponding pages in the inode should be marked for writeback
 318 * and the compressed pages should have a reference on them for dropping
 319 * when the IO is complete.
 320 *
 321 * This also checksums the file bytes and gets things ready for
 322 * the end io hooks.
 323 */
 324int btrfs_submit_compressed_write(struct inode *inode, u64 start,
 325				 unsigned long len, u64 disk_start,
 326				 unsigned long compressed_len,
 327				 struct page **compressed_pages,
 328				 unsigned long nr_pages)
 329{
 330	struct bio *bio = NULL;
 331	struct btrfs_root *root = BTRFS_I(inode)->root;
 332	struct compressed_bio *cb;
 333	unsigned long bytes_left;
 334	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 335	int pg_index = 0;
 336	struct page *page;
 337	u64 first_byte = disk_start;
 338	struct block_device *bdev;
 339	int ret;
 340	int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
 341
 342	WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
 343	cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
 344	if (!cb)
 345		return -ENOMEM;
 346	atomic_set(&cb->pending_bios, 0);
 347	cb->errors = 0;
 348	cb->inode = inode;
 349	cb->start = start;
 350	cb->len = len;
 351	cb->mirror_num = 0;
 352	cb->compressed_pages = compressed_pages;
 353	cb->compressed_len = compressed_len;
 354	cb->orig_bio = NULL;
 
 355	cb->nr_pages = nr_pages;
 
 
 
 356
 357	bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
 358
 359	bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
 360	if (!bio) {
 361		kfree(cb);
 362		return -ENOMEM;
 363	}
 364	bio->bi_private = cb;
 365	bio->bi_end_io = end_compressed_bio_write;
 366	atomic_inc(&cb->pending_bios);
 367
 368	/* create and submit bios for the compressed pages */
 369	bytes_left = compressed_len;
 370	for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
 371		page = compressed_pages[pg_index];
 372		page->mapping = inode->i_mapping;
 373		if (bio->bi_iter.bi_size)
 374			ret = io_tree->ops->merge_bio_hook(WRITE, page, 0,
 375							   PAGE_CACHE_SIZE,
 376							   bio, 0);
 377		else
 378			ret = 0;
 379
 380		page->mapping = NULL;
 381		if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
 382		    PAGE_CACHE_SIZE) {
 383			bio_get(bio);
 384
 385			/*
 386			 * inc the count before we submit the bio so
 387			 * we know the end IO handler won't happen before
 388			 * we inc the count.  Otherwise, the cb might get
 389			 * freed before we're done setting it up
 390			 */
 391			atomic_inc(&cb->pending_bios);
 392			ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
 393			BUG_ON(ret); /* -ENOMEM */
 394
 395			if (!skip_sum) {
 396				ret = btrfs_csum_one_bio(root, inode, bio,
 397							 start, 1);
 398				BUG_ON(ret); /* -ENOMEM */
 399			}
 400
 401			ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
 402			BUG_ON(ret); /* -ENOMEM */
 403
 404			bio_put(bio);
 405
 406			bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
 407			BUG_ON(!bio);
 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			btrfs_info(BTRFS_I(inode)->root->fs_info,
 414					"bytes left %lu compress len %lu nr %lu",
 415			       bytes_left, cb->compressed_len, cb->nr_pages);
 416		}
 417		bytes_left -= PAGE_CACHE_SIZE;
 418		first_byte += PAGE_CACHE_SIZE;
 419		cond_resched();
 420	}
 421	bio_get(bio);
 422
 423	ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
 424	BUG_ON(ret); /* -ENOMEM */
 425
 426	if (!skip_sum) {
 427		ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
 428		BUG_ON(ret); /* -ENOMEM */
 429	}
 430
 431	ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
 432	BUG_ON(ret); /* -ENOMEM */
 433
 434	bio_put(bio);
 435	return 0;
 436}
 437
 
 
 
 
 
 
 
 
 
 
 
 438static noinline int add_ra_bio_pages(struct inode *inode,
 439				     u64 compressed_end,
 440				     struct compressed_bio *cb)
 
 441{
 
 442	unsigned long end_index;
 443	unsigned long pg_index;
 444	u64 last_offset;
 445	u64 isize = i_size_read(inode);
 446	int ret;
 447	struct page *page;
 448	unsigned long nr_pages = 0;
 449	struct extent_map *em;
 450	struct address_space *mapping = inode->i_mapping;
 451	struct extent_map_tree *em_tree;
 452	struct extent_io_tree *tree;
 453	u64 end;
 454	int misses = 0;
 455
 456	page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page;
 457	last_offset = (page_offset(page) + PAGE_CACHE_SIZE);
 458	em_tree = &BTRFS_I(inode)->extent_tree;
 459	tree = &BTRFS_I(inode)->io_tree;
 460
 461	if (isize == 0)
 462		return 0;
 463
 464	end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 
 
 
 
 
 
 
 
 
 
 465
 466	while (last_offset < compressed_end) {
 467		pg_index = last_offset >> PAGE_CACHE_SHIFT;
 
 
 468
 469		if (pg_index > end_index)
 470			break;
 471
 472		rcu_read_lock();
 473		page = radix_tree_lookup(&mapping->page_tree, pg_index);
 474		rcu_read_unlock();
 475		if (page && !radix_tree_exceptional_entry(page)) {
 476			misses++;
 477			if (misses > 4)
 
 478				break;
 479			goto next;
 
 
 
 
 
 
 480		}
 481
 482		page = __page_cache_alloc(mapping_gfp_mask(mapping) &
 483								~__GFP_FS);
 484		if (!page)
 485			break;
 486
 487		if (add_to_page_cache_lru(page, mapping, pg_index,
 488								GFP_NOFS)) {
 489			page_cache_release(page);
 490			goto next;
 
 491		}
 492
 493		end = last_offset + PAGE_CACHE_SIZE - 1;
 494		/*
 495		 * at this point, we have a locked page in the page cache
 496		 * for these bytes in the file.  But, we have to make
 497		 * sure they map to this compressed extent on disk.
 498		 */
 499		set_page_extent_mapped(page);
 500		lock_extent(tree, last_offset, end);
 
 
 
 
 
 
 501		read_lock(&em_tree->lock);
 502		em = lookup_extent_mapping(em_tree, last_offset,
 503					   PAGE_CACHE_SIZE);
 504		read_unlock(&em_tree->lock);
 505
 506		if (!em || last_offset < em->start ||
 507		    (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) ||
 508		    (em->block_start >> 9) != cb->orig_bio->bi_iter.bi_sector) {
 
 
 
 
 
 509			free_extent_map(em);
 510			unlock_extent(tree, last_offset, end);
 511			unlock_page(page);
 512			page_cache_release(page);
 513			break;
 514		}
 515		free_extent_map(em);
 516
 517		if (page->index == end_index) {
 518			char *userpage;
 519			size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1);
 520
 521			if (zero_offset) {
 522				int zeros;
 523				zeros = PAGE_CACHE_SIZE - zero_offset;
 524				userpage = kmap_atomic(page);
 525				memset(userpage + zero_offset, 0, zeros);
 526				flush_dcache_page(page);
 527				kunmap_atomic(userpage);
 528			}
 529		}
 530
 531		ret = bio_add_page(cb->orig_bio, page,
 532				   PAGE_CACHE_SIZE, 0);
 533
 534		if (ret == PAGE_CACHE_SIZE) {
 535			nr_pages++;
 536			page_cache_release(page);
 537		} else {
 538			unlock_extent(tree, last_offset, end);
 539			unlock_page(page);
 540			page_cache_release(page);
 541			break;
 542		}
 543next:
 544		last_offset += PAGE_CACHE_SIZE;
 
 
 
 
 
 
 
 
 545	}
 546	return 0;
 547}
 548
 549/*
 550 * for a compressed read, the bio we get passed has all the inode pages
 551 * in it.  We don't actually do IO on those pages but allocate new ones
 552 * to hold the compressed pages on disk.
 553 *
 554 * bio->bi_iter.bi_sector points to the compressed extent on disk
 555 * bio->bi_io_vec points to all of the inode pages
 556 * bio->bi_vcnt is a count of pages
 557 *
 558 * After the compressed pages are read, we copy the bytes into the
 559 * bio we were passed and then call the bio end_io calls
 560 */
 561int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 562				 int mirror_num, unsigned long bio_flags)
 563{
 564	struct extent_io_tree *tree;
 565	struct extent_map_tree *em_tree;
 
 566	struct compressed_bio *cb;
 567	struct btrfs_root *root = BTRFS_I(inode)->root;
 568	unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
 569	unsigned long compressed_len;
 570	unsigned long nr_pages;
 571	unsigned long pg_index;
 572	struct page *page;
 573	struct block_device *bdev;
 574	struct bio *comp_bio;
 575	u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9;
 576	u64 em_len;
 577	u64 em_start;
 578	struct extent_map *em;
 579	int ret = -ENOMEM;
 580	int faili = 0;
 581	u32 *sums;
 582
 583	tree = &BTRFS_I(inode)->io_tree;
 584	em_tree = &BTRFS_I(inode)->extent_tree;
 585
 586	/* we need the actual starting offset of this extent in the file */
 587	read_lock(&em_tree->lock);
 588	em = lookup_extent_mapping(em_tree,
 589				   page_offset(bio->bi_io_vec->bv_page),
 590				   PAGE_CACHE_SIZE);
 591	read_unlock(&em_tree->lock);
 592	if (!em)
 593		return -EIO;
 
 
 594
 
 595	compressed_len = em->block_len;
 596	cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
 597	if (!cb)
 598		goto out;
 599
 600	atomic_set(&cb->pending_bios, 0);
 601	cb->errors = 0;
 602	cb->inode = inode;
 603	cb->mirror_num = mirror_num;
 604	sums = &cb->sums;
 605
 606	cb->start = em->orig_start;
 607	em_len = em->len;
 608	em_start = em->start;
 609
 
 
 
 
 
 610	free_extent_map(em);
 611	em = NULL;
 612
 613	cb->len = uncompressed_len;
 614	cb->compressed_len = compressed_len;
 615	cb->compress_type = extent_compress_type(bio_flags);
 616	cb->orig_bio = bio;
 
 
 617
 618	nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
 619				 PAGE_CACHE_SIZE;
 620	cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages,
 621				       GFP_NOFS);
 622	if (!cb->compressed_pages)
 623		goto fail1;
 624
 625	bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
 626
 627	for (pg_index = 0; pg_index < nr_pages; pg_index++) {
 628		cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
 629							      __GFP_HIGHMEM);
 630		if (!cb->compressed_pages[pg_index]) {
 631			faili = pg_index - 1;
 632			ret = -ENOMEM;
 633			goto fail2;
 634		}
 635	}
 636	faili = nr_pages - 1;
 637	cb->nr_pages = nr_pages;
 638
 639	/* In the parent-locked case, we only locked the range we are
 640	 * interested in.  In all other cases, we can opportunistically
 641	 * cache decompressed data that goes beyond the requested range. */
 642	if (!(bio_flags & EXTENT_BIO_PARENT_LOCKED))
 643		add_ra_bio_pages(inode, em_start + em_len, cb);
 644
 645	/* include any pages we added in add_ra-bio_pages */
 646	uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
 647	cb->len = uncompressed_len;
 
 648
 649	comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
 650	if (!comp_bio)
 651		goto fail2;
 652	comp_bio->bi_private = cb;
 653	comp_bio->bi_end_io = end_compressed_bio_read;
 654	atomic_inc(&cb->pending_bios);
 655
 656	for (pg_index = 0; pg_index < nr_pages; pg_index++) {
 657		page = cb->compressed_pages[pg_index];
 658		page->mapping = inode->i_mapping;
 659		page->index = em_start >> PAGE_CACHE_SHIFT;
 660
 661		if (comp_bio->bi_iter.bi_size)
 662			ret = tree->ops->merge_bio_hook(READ, page, 0,
 663							PAGE_CACHE_SIZE,
 664							comp_bio, 0);
 665		else
 666			ret = 0;
 667
 668		page->mapping = NULL;
 669		if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
 670		    PAGE_CACHE_SIZE) {
 671			bio_get(comp_bio);
 672
 673			ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
 674			BUG_ON(ret); /* -ENOMEM */
 675
 676			/*
 677			 * inc the count before we submit the bio so
 678			 * we know the end IO handler won't happen before
 679			 * we inc the count.  Otherwise, the cb might get
 680			 * freed before we're done setting it up
 681			 */
 682			atomic_inc(&cb->pending_bios);
 683
 684			if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
 685				ret = btrfs_lookup_bio_sums(root, inode,
 686							comp_bio, sums);
 687				BUG_ON(ret); /* -ENOMEM */
 688			}
 689			sums += (comp_bio->bi_iter.bi_size +
 690				 root->sectorsize - 1) / root->sectorsize;
 
 
 691
 692			ret = btrfs_map_bio(root, READ, comp_bio,
 693					    mirror_num, 0);
 694			if (ret)
 695				bio_endio(comp_bio, ret);
 696
 697			bio_put(comp_bio);
 698
 699			comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
 700							GFP_NOFS);
 701			BUG_ON(!comp_bio);
 702			comp_bio->bi_private = cb;
 703			comp_bio->bi_end_io = end_compressed_bio_read;
 704
 705			bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
 706		}
 707		cur_disk_byte += PAGE_CACHE_SIZE;
 708	}
 709	bio_get(comp_bio);
 
 
 
 
 
 
 
 
 
 710
 711	ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
 712	BUG_ON(ret); /* -ENOMEM */
 
 713
 714	if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
 715		ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
 716		BUG_ON(ret); /* -ENOMEM */
 717	}
 
 
 
 
 
 
 718
 719	ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
 720	if (ret)
 721		bio_endio(comp_bio, ret);
 722
 723	bio_put(comp_bio);
 724	return 0;
 
 725
 726fail2:
 727	while (faili >= 0) {
 728		__free_page(cb->compressed_pages[faili]);
 729		faili--;
 730	}
 731
 732	kfree(cb->compressed_pages);
 733fail1:
 734	kfree(cb);
 735out:
 736	free_extent_map(em);
 737	return ret;
 738}
 739
 740static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES];
 741static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES];
 742static int comp_num_workspace[BTRFS_COMPRESS_TYPES];
 743static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES];
 744static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES];
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 745
 746static struct btrfs_compress_op *btrfs_compress_op[] = {
 
 
 
 
 
 
 
 
 
 
 
 
 
 747	&btrfs_zlib_compress,
 748	&btrfs_lzo_compress,
 
 749};
 750
 751void __init btrfs_init_compress(void)
 752{
 753	int i;
 
 
 
 
 
 
 
 
 
 
 
 
 754
 755	for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
 756		INIT_LIST_HEAD(&comp_idle_workspace[i]);
 757		spin_lock_init(&comp_workspace_lock[i]);
 758		atomic_set(&comp_alloc_workspace[i], 0);
 759		init_waitqueue_head(&comp_workspace_wait[i]);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 760	}
 761}
 762
 763/*
 764 * this finds an available workspace or allocates a new one
 765 * ERR_PTR is returned if things go bad.
 
 
 766 */
 767static struct list_head *find_workspace(int type)
 768{
 
 769	struct list_head *workspace;
 770	int cpus = num_online_cpus();
 771	int idx = type - 1;
 
 
 
 
 
 
 
 
 
 
 
 
 772
 773	struct list_head *idle_workspace	= &comp_idle_workspace[idx];
 774	spinlock_t *workspace_lock		= &comp_workspace_lock[idx];
 775	atomic_t *alloc_workspace		= &comp_alloc_workspace[idx];
 776	wait_queue_head_t *workspace_wait	= &comp_workspace_wait[idx];
 777	int *num_workspace			= &comp_num_workspace[idx];
 778again:
 779	spin_lock(workspace_lock);
 780	if (!list_empty(idle_workspace)) {
 781		workspace = idle_workspace->next;
 782		list_del(workspace);
 783		(*num_workspace)--;
 784		spin_unlock(workspace_lock);
 785		return workspace;
 786
 787	}
 788	if (atomic_read(alloc_workspace) > cpus) {
 789		DEFINE_WAIT(wait);
 790
 791		spin_unlock(workspace_lock);
 792		prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
 793		if (atomic_read(alloc_workspace) > cpus && !*num_workspace)
 794			schedule();
 795		finish_wait(workspace_wait, &wait);
 796		goto again;
 797	}
 798	atomic_inc(alloc_workspace);
 799	spin_unlock(workspace_lock);
 
 
 
 
 
 
 
 
 
 800
 801	workspace = btrfs_compress_op[idx]->alloc_workspace();
 802	if (IS_ERR(workspace)) {
 803		atomic_dec(alloc_workspace);
 804		wake_up(workspace_wait);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 805	}
 806	return workspace;
 807}
 808
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 809/*
 810 * put a workspace struct back on the list or free it if we have enough
 811 * idle ones sitting around
 812 */
 813static void free_workspace(int type, struct list_head *workspace)
 814{
 815	int idx = type - 1;
 816	struct list_head *idle_workspace	= &comp_idle_workspace[idx];
 817	spinlock_t *workspace_lock		= &comp_workspace_lock[idx];
 818	atomic_t *alloc_workspace		= &comp_alloc_workspace[idx];
 819	wait_queue_head_t *workspace_wait	= &comp_workspace_wait[idx];
 820	int *num_workspace			= &comp_num_workspace[idx];
 821
 822	spin_lock(workspace_lock);
 823	if (*num_workspace < num_online_cpus()) {
 824		list_add_tail(workspace, idle_workspace);
 825		(*num_workspace)++;
 826		spin_unlock(workspace_lock);
 
 
 
 
 
 
 
 827		goto wake;
 828	}
 829	spin_unlock(workspace_lock);
 830
 831	btrfs_compress_op[idx]->free_workspace(workspace);
 832	atomic_dec(alloc_workspace);
 833wake:
 834	smp_mb();
 835	if (waitqueue_active(workspace_wait))
 836		wake_up(workspace_wait);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 837}
 838
 839/*
 840 * cleanup function for module exit
 
 841 */
 842static void free_workspaces(void)
 843{
 844	struct list_head *workspace;
 845	int i;
 846
 847	for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
 848		while (!list_empty(&comp_idle_workspace[i])) {
 849			workspace = comp_idle_workspace[i].next;
 850			list_del(workspace);
 851			btrfs_compress_op[i]->free_workspace(workspace);
 852			atomic_dec(&comp_alloc_workspace[i]);
 853		}
 854	}
 855}
 856
 857/*
 858 * given an address space and start/len, compress the bytes.
 
 859 *
 860 * pages are allocated to hold the compressed result and stored
 861 * in 'pages'
 
 
 862 *
 863 * out_pages is used to return the number of pages allocated.  There
 864 * may be pages allocated even if we return an error
 865 *
 866 * total_in is used to return the number of bytes actually read.  It
 867 * may be smaller then len if we had to exit early because we
 868 * ran out of room in the pages array or because we cross the
 869 * max_out threshold.
 870 *
 871 * total_out is used to return the total number of compressed bytes
 872 *
 873 * max_out tells us the max number of bytes that we're allowed to
 874 * stuff into pages
 875 */
 876int btrfs_compress_pages(int type, struct address_space *mapping,
 877			 u64 start, unsigned long len,
 878			 struct page **pages,
 879			 unsigned long nr_dest_pages,
 880			 unsigned long *out_pages,
 881			 unsigned long *total_in,
 882			 unsigned long *total_out,
 883			 unsigned long max_out)
 884{
 
 
 885	struct list_head *workspace;
 886	int ret;
 887
 888	workspace = find_workspace(type);
 889	if (IS_ERR(workspace))
 890		return -1;
 891
 892	ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
 893						      start, len, pages,
 894						      nr_dest_pages, out_pages,
 895						      total_in, total_out,
 896						      max_out);
 897	free_workspace(type, workspace);
 898	return ret;
 899}
 900
 901/*
 902 * pages_in is an array of pages with compressed data.
 903 *
 904 * disk_start is the starting logical offset of this array in the file
 905 *
 906 * bvec is a bio_vec of pages from the file that we want to decompress into
 907 *
 908 * vcnt is the count of pages in the biovec
 909 *
 910 * srclen is the number of bytes in pages_in
 911 *
 912 * The basic idea is that we have a bio that was created by readpages.
 913 * The pages in the bio are for the uncompressed data, and they may not
 914 * be contiguous.  They all correspond to the range of bytes covered by
 915 * the compressed extent.
 916 */
 917static int btrfs_decompress_biovec(int type, struct page **pages_in,
 918				   u64 disk_start, struct bio_vec *bvec,
 919				   int vcnt, size_t srclen)
 920{
 921	struct list_head *workspace;
 922	int ret;
 
 923
 924	workspace = find_workspace(type);
 925	if (IS_ERR(workspace))
 926		return -ENOMEM;
 927
 928	ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
 929							 disk_start,
 930							 bvec, vcnt, srclen);
 931	free_workspace(type, workspace);
 932	return ret;
 933}
 934
 935/*
 936 * a less complex decompression routine.  Our compressed data fits in a
 937 * single page, and we want to read a single page out of it.
 938 * start_byte tells us the offset into the compressed data we're interested in
 939 */
 940int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
 941		     unsigned long start_byte, size_t srclen, size_t destlen)
 942{
 
 943	struct list_head *workspace;
 
 944	int ret;
 945
 946	workspace = find_workspace(type);
 947	if (IS_ERR(workspace))
 948		return -ENOMEM;
 
 
 
 949
 950	ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
 951						  dest_page, start_byte,
 952						  srclen, destlen);
 
 953
 954	free_workspace(type, workspace);
 955	return ret;
 956}
 957
 958void btrfs_exit_compress(void)
 959{
 960	free_workspaces();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 961}
 962
 963/*
 964 * Copy uncompressed data from working buffer to pages.
 965 *
 966 * buf_start is the byte offset we're of the start of our workspace buffer.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 967 *
 968 * total_out is the last byte of the buffer
 
 969 */
 970int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
 971			      unsigned long total_out, u64 disk_start,
 972			      struct bio_vec *bvec, int vcnt,
 973			      unsigned long *pg_index,
 974			      unsigned long *pg_offset)
 975{
 976	unsigned long buf_offset;
 977	unsigned long current_buf_start;
 978	unsigned long start_byte;
 979	unsigned long working_bytes = total_out - buf_start;
 980	unsigned long bytes;
 981	char *kaddr;
 982	struct page *page_out = bvec[*pg_index].bv_page;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 983
 984	/*
 985	 * start byte is the first byte of the page we're currently
 986	 * copying into relative to the start of the compressed data.
 987	 */
 988	start_byte = page_offset(page_out) - disk_start;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 989
 990	/* we haven't yet hit data corresponding to this page */
 991	if (total_out <= start_byte)
 992		return 1;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 993
 994	/*
 995	 * the start of the data we care about is offset into
 996	 * the middle of our working buffer
 
 997	 */
 998	if (total_out > start_byte && buf_start < start_byte) {
 999		buf_offset = start_byte - buf_start;
1000		working_bytes -= buf_offset;
1001	} else {
1002		buf_offset = 0;
 
1003	}
1004	current_buf_start = buf_start;
1005
1006	/* copy bytes from the working buffer into the pages */
1007	while (working_bytes > 0) {
1008		bytes = min(PAGE_CACHE_SIZE - *pg_offset,
1009			    PAGE_CACHE_SIZE - buf_offset);
1010		bytes = min(bytes, working_bytes);
1011		kaddr = kmap_atomic(page_out);
1012		memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
1013		if (*pg_index == (vcnt - 1) && *pg_offset == 0)
1014			memset(kaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
1015		kunmap_atomic(kaddr);
1016		flush_dcache_page(page_out);
1017
1018		*pg_offset += bytes;
1019		buf_offset += bytes;
1020		working_bytes -= bytes;
1021		current_buf_start += bytes;
1022
1023		/* check if we need to pick another page */
1024		if (*pg_offset == PAGE_CACHE_SIZE) {
1025			(*pg_index)++;
1026			if (*pg_index >= vcnt)
1027				return 0;
1028
1029			page_out = bvec[*pg_index].bv_page;
1030			*pg_offset = 0;
1031			start_byte = page_offset(page_out) - disk_start;
1032
1033			/*
1034			 * make sure our new page is covered by this
1035			 * working buffer
1036			 */
1037			if (total_out <= start_byte)
1038				return 1;
1039
1040			/*
1041			 * the next page in the biovec might not be adjacent
1042			 * to the last page, but it might still be found
1043			 * inside this working buffer. bump our offset pointer
1044			 */
1045			if (total_out > start_byte &&
1046			    current_buf_start < start_byte) {
1047				buf_offset = start_byte - buf_start;
1048				working_bytes = total_out - start_byte;
1049				current_buf_start = buf_start + buf_offset;
1050			}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1051		}
 
 
 
 
1052	}
1053
1054	return 1;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1055}