[CIFS] fix sparse warning
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / btrfs / compression.c
blob9d8ba4d54a37c3f96e9585de46b8e99d701410bc
1 /*
2 * Copyright (C) 2008 Oracle. All rights reserved.
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.
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.
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.
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/pagevec.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"
46 struct compressed_bio {
47 /* number of bios pending for this compressed extent */
48 atomic_t pending_bios;
50 /* the pages with the compressed data on them */
51 struct page **compressed_pages;
53 /* inode that owns this data */
54 struct inode *inode;
56 /* starting offset in the inode for our pages */
57 u64 start;
59 /* number of bytes in the inode we're working on */
60 unsigned long len;
62 /* number of bytes on disk */
63 unsigned long compressed_len;
65 /* number of compressed pages in the array */
66 unsigned long nr_pages;
68 /* IO errors */
69 int errors;
70 int mirror_num;
72 /* for reads, this is the bio we are copying the data into */
73 struct bio *orig_bio;
76 * the start of a variable length array of checksums only
77 * used by reads
79 u32 sums;
82 static inline int compressed_bio_size(struct btrfs_root *root,
83 unsigned long disk_size)
85 u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
86 return sizeof(struct compressed_bio) +
87 ((disk_size + root->sectorsize - 1) / root->sectorsize) *
88 csum_size;
91 static struct bio *compressed_bio_alloc(struct block_device *bdev,
92 u64 first_byte, gfp_t gfp_flags)
94 struct bio *bio;
95 int nr_vecs;
97 nr_vecs = bio_get_nr_vecs(bdev);
98 bio = bio_alloc(gfp_flags, nr_vecs);
100 if (bio == NULL && (current->flags & PF_MEMALLOC)) {
101 while (!bio && (nr_vecs /= 2))
102 bio = bio_alloc(gfp_flags, nr_vecs);
105 if (bio) {
106 bio->bi_size = 0;
107 bio->bi_bdev = bdev;
108 bio->bi_sector = first_byte >> 9;
110 return bio;
113 static int check_compressed_csum(struct inode *inode,
114 struct compressed_bio *cb,
115 u64 disk_start)
117 int ret;
118 struct btrfs_root *root = BTRFS_I(inode)->root;
119 struct page *page;
120 unsigned long i;
121 char *kaddr;
122 u32 csum;
123 u32 *cb_sum = &cb->sums;
125 if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
126 return 0;
128 for (i = 0; i < cb->nr_pages; i++) {
129 page = cb->compressed_pages[i];
130 csum = ~(u32)0;
132 kaddr = kmap_atomic(page, KM_USER0);
133 csum = btrfs_csum_data(root, kaddr, csum, PAGE_CACHE_SIZE);
134 btrfs_csum_final(csum, (char *)&csum);
135 kunmap_atomic(kaddr, KM_USER0);
137 if (csum != *cb_sum) {
138 printk(KERN_INFO "btrfs csum failed ino %lu "
139 "extent %llu csum %u "
140 "wanted %u mirror %d\n", inode->i_ino,
141 (unsigned long long)disk_start,
142 csum, *cb_sum, cb->mirror_num);
143 ret = -EIO;
144 goto fail;
146 cb_sum++;
149 ret = 0;
150 fail:
151 return ret;
154 /* when we finish reading compressed pages from the disk, we
155 * decompress them and then run the bio end_io routines on the
156 * decompressed pages (in the inode address space).
158 * This allows the checksumming and other IO error handling routines
159 * to work normally
161 * The compressed pages are freed here, and it must be run
162 * in process context
164 static void end_compressed_bio_read(struct bio *bio, int err)
166 struct extent_io_tree *tree;
167 struct compressed_bio *cb = bio->bi_private;
168 struct inode *inode;
169 struct page *page;
170 unsigned long index;
171 int ret;
173 if (err)
174 cb->errors = 1;
176 /* if there are more bios still pending for this compressed
177 * extent, just exit
179 if (!atomic_dec_and_test(&cb->pending_bios))
180 goto out;
182 inode = cb->inode;
183 ret = check_compressed_csum(inode, cb, (u64)bio->bi_sector << 9);
184 if (ret)
185 goto csum_failed;
187 /* ok, we're the last bio for this extent, lets start
188 * the decompression.
190 tree = &BTRFS_I(inode)->io_tree;
191 ret = btrfs_zlib_decompress_biovec(cb->compressed_pages,
192 cb->start,
193 cb->orig_bio->bi_io_vec,
194 cb->orig_bio->bi_vcnt,
195 cb->compressed_len);
196 csum_failed:
197 if (ret)
198 cb->errors = 1;
200 /* release the compressed pages */
201 index = 0;
202 for (index = 0; index < cb->nr_pages; index++) {
203 page = cb->compressed_pages[index];
204 page->mapping = NULL;
205 page_cache_release(page);
208 /* do io completion on the original bio */
209 if (cb->errors) {
210 bio_io_error(cb->orig_bio);
211 } else {
212 int bio_index = 0;
213 struct bio_vec *bvec = cb->orig_bio->bi_io_vec;
216 * we have verified the checksum already, set page
217 * checked so the end_io handlers know about it
219 while (bio_index < cb->orig_bio->bi_vcnt) {
220 SetPageChecked(bvec->bv_page);
221 bvec++;
222 bio_index++;
224 bio_endio(cb->orig_bio, 0);
227 /* finally free the cb struct */
228 kfree(cb->compressed_pages);
229 kfree(cb);
230 out:
231 bio_put(bio);
235 * Clear the writeback bits on all of the file
236 * pages for a compressed write
238 static noinline int end_compressed_writeback(struct inode *inode, u64 start,
239 unsigned long ram_size)
241 unsigned long index = start >> PAGE_CACHE_SHIFT;
242 unsigned long end_index = (start + ram_size - 1) >> PAGE_CACHE_SHIFT;
243 struct page *pages[16];
244 unsigned long nr_pages = end_index - index + 1;
245 int i;
246 int ret;
248 while (nr_pages > 0) {
249 ret = find_get_pages_contig(inode->i_mapping, index,
250 min_t(unsigned long,
251 nr_pages, ARRAY_SIZE(pages)), pages);
252 if (ret == 0) {
253 nr_pages -= 1;
254 index += 1;
255 continue;
257 for (i = 0; i < ret; i++) {
258 end_page_writeback(pages[i]);
259 page_cache_release(pages[i]);
261 nr_pages -= ret;
262 index += ret;
264 /* the inode may be gone now */
265 return 0;
269 * do the cleanup once all the compressed pages hit the disk.
270 * This will clear writeback on the file pages and free the compressed
271 * pages.
273 * This also calls the writeback end hooks for the file pages so that
274 * metadata and checksums can be updated in the file.
276 static void end_compressed_bio_write(struct bio *bio, int err)
278 struct extent_io_tree *tree;
279 struct compressed_bio *cb = bio->bi_private;
280 struct inode *inode;
281 struct page *page;
282 unsigned long index;
284 if (err)
285 cb->errors = 1;
287 /* if there are more bios still pending for this compressed
288 * extent, just exit
290 if (!atomic_dec_and_test(&cb->pending_bios))
291 goto out;
293 /* ok, we're the last bio for this extent, step one is to
294 * call back into the FS and do all the end_io operations
296 inode = cb->inode;
297 tree = &BTRFS_I(inode)->io_tree;
298 cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
299 tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
300 cb->start,
301 cb->start + cb->len - 1,
302 NULL, 1);
303 cb->compressed_pages[0]->mapping = NULL;
305 end_compressed_writeback(inode, cb->start, cb->len);
306 /* note, our inode could be gone now */
309 * release the compressed pages, these came from alloc_page and
310 * are not attached to the inode at all
312 index = 0;
313 for (index = 0; index < cb->nr_pages; index++) {
314 page = cb->compressed_pages[index];
315 page->mapping = NULL;
316 page_cache_release(page);
319 /* finally free the cb struct */
320 kfree(cb->compressed_pages);
321 kfree(cb);
322 out:
323 bio_put(bio);
327 * worker function to build and submit bios for previously compressed pages.
328 * The corresponding pages in the inode should be marked for writeback
329 * and the compressed pages should have a reference on them for dropping
330 * when the IO is complete.
332 * This also checksums the file bytes and gets things ready for
333 * the end io hooks.
335 int btrfs_submit_compressed_write(struct inode *inode, u64 start,
336 unsigned long len, u64 disk_start,
337 unsigned long compressed_len,
338 struct page **compressed_pages,
339 unsigned long nr_pages)
341 struct bio *bio = NULL;
342 struct btrfs_root *root = BTRFS_I(inode)->root;
343 struct compressed_bio *cb;
344 unsigned long bytes_left;
345 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
346 int page_index = 0;
347 struct page *page;
348 u64 first_byte = disk_start;
349 struct block_device *bdev;
350 int ret;
352 WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
353 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
354 atomic_set(&cb->pending_bios, 0);
355 cb->errors = 0;
356 cb->inode = inode;
357 cb->start = start;
358 cb->len = len;
359 cb->mirror_num = 0;
360 cb->compressed_pages = compressed_pages;
361 cb->compressed_len = compressed_len;
362 cb->orig_bio = NULL;
363 cb->nr_pages = nr_pages;
365 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
367 bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
368 bio->bi_private = cb;
369 bio->bi_end_io = end_compressed_bio_write;
370 atomic_inc(&cb->pending_bios);
372 /* create and submit bios for the compressed pages */
373 bytes_left = compressed_len;
374 for (page_index = 0; page_index < cb->nr_pages; page_index++) {
375 page = compressed_pages[page_index];
376 page->mapping = inode->i_mapping;
377 if (bio->bi_size)
378 ret = io_tree->ops->merge_bio_hook(page, 0,
379 PAGE_CACHE_SIZE,
380 bio, 0);
381 else
382 ret = 0;
384 page->mapping = NULL;
385 if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
386 PAGE_CACHE_SIZE) {
387 bio_get(bio);
390 * inc the count before we submit the bio so
391 * we know the end IO handler won't happen before
392 * we inc the count. Otherwise, the cb might get
393 * freed before we're done setting it up
395 atomic_inc(&cb->pending_bios);
396 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
397 BUG_ON(ret);
399 ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
400 BUG_ON(ret);
402 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
403 BUG_ON(ret);
405 bio_put(bio);
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);
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);
416 bytes_left -= PAGE_CACHE_SIZE;
417 first_byte += PAGE_CACHE_SIZE;
418 cond_resched();
420 bio_get(bio);
422 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
423 BUG_ON(ret);
425 ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
426 BUG_ON(ret);
428 ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
429 BUG_ON(ret);
431 bio_put(bio);
432 return 0;
435 static noinline int add_ra_bio_pages(struct inode *inode,
436 u64 compressed_end,
437 struct compressed_bio *cb)
439 unsigned long end_index;
440 unsigned long page_index;
441 u64 last_offset;
442 u64 isize = i_size_read(inode);
443 int ret;
444 struct page *page;
445 unsigned long nr_pages = 0;
446 struct extent_map *em;
447 struct address_space *mapping = inode->i_mapping;
448 struct pagevec pvec;
449 struct extent_map_tree *em_tree;
450 struct extent_io_tree *tree;
451 u64 end;
452 int misses = 0;
454 page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page;
455 last_offset = (page_offset(page) + PAGE_CACHE_SIZE);
456 em_tree = &BTRFS_I(inode)->extent_tree;
457 tree = &BTRFS_I(inode)->io_tree;
459 if (isize == 0)
460 return 0;
462 end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
464 pagevec_init(&pvec, 0);
465 while (last_offset < compressed_end) {
466 page_index = last_offset >> PAGE_CACHE_SHIFT;
468 if (page_index > end_index)
469 break;
471 rcu_read_lock();
472 page = radix_tree_lookup(&mapping->page_tree, page_index);
473 rcu_read_unlock();
474 if (page) {
475 misses++;
476 if (misses > 4)
477 break;
478 goto next;
481 page = alloc_page(mapping_gfp_mask(mapping) | GFP_NOFS);
482 if (!page)
483 break;
485 page->index = page_index;
487 * what we want to do here is call add_to_page_cache_lru,
488 * but that isn't exported, so we reproduce it here
490 if (add_to_page_cache(page, mapping,
491 page->index, GFP_NOFS)) {
492 page_cache_release(page);
493 goto next;
496 /* open coding of lru_cache_add, also not exported */
497 page_cache_get(page);
498 if (!pagevec_add(&pvec, page))
499 __pagevec_lru_add_file(&pvec);
501 end = last_offset + PAGE_CACHE_SIZE - 1;
503 * at this point, we have a locked page in the page cache
504 * for these bytes in the file. But, we have to make
505 * sure they map to this compressed extent on disk.
507 set_page_extent_mapped(page);
508 lock_extent(tree, last_offset, end, GFP_NOFS);
509 spin_lock(&em_tree->lock);
510 em = lookup_extent_mapping(em_tree, last_offset,
511 PAGE_CACHE_SIZE);
512 spin_unlock(&em_tree->lock);
514 if (!em || last_offset < em->start ||
515 (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) ||
516 (em->block_start >> 9) != cb->orig_bio->bi_sector) {
517 free_extent_map(em);
518 unlock_extent(tree, last_offset, end, GFP_NOFS);
519 unlock_page(page);
520 page_cache_release(page);
521 break;
523 free_extent_map(em);
525 if (page->index == end_index) {
526 char *userpage;
527 size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1);
529 if (zero_offset) {
530 int zeros;
531 zeros = PAGE_CACHE_SIZE - zero_offset;
532 userpage = kmap_atomic(page, KM_USER0);
533 memset(userpage + zero_offset, 0, zeros);
534 flush_dcache_page(page);
535 kunmap_atomic(userpage, KM_USER0);
539 ret = bio_add_page(cb->orig_bio, page,
540 PAGE_CACHE_SIZE, 0);
542 if (ret == PAGE_CACHE_SIZE) {
543 nr_pages++;
544 page_cache_release(page);
545 } else {
546 unlock_extent(tree, last_offset, end, GFP_NOFS);
547 unlock_page(page);
548 page_cache_release(page);
549 break;
551 next:
552 last_offset += PAGE_CACHE_SIZE;
554 if (pagevec_count(&pvec))
555 __pagevec_lru_add_file(&pvec);
556 return 0;
560 * for a compressed read, the bio we get passed has all the inode pages
561 * in it. We don't actually do IO on those pages but allocate new ones
562 * to hold the compressed pages on disk.
564 * bio->bi_sector points to the compressed extent on disk
565 * bio->bi_io_vec points to all of the inode pages
566 * bio->bi_vcnt is a count of pages
568 * After the compressed pages are read, we copy the bytes into the
569 * bio we were passed and then call the bio end_io calls
571 int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
572 int mirror_num, unsigned long bio_flags)
574 struct extent_io_tree *tree;
575 struct extent_map_tree *em_tree;
576 struct compressed_bio *cb;
577 struct btrfs_root *root = BTRFS_I(inode)->root;
578 unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
579 unsigned long compressed_len;
580 unsigned long nr_pages;
581 unsigned long page_index;
582 struct page *page;
583 struct block_device *bdev;
584 struct bio *comp_bio;
585 u64 cur_disk_byte = (u64)bio->bi_sector << 9;
586 u64 em_len;
587 u64 em_start;
588 struct extent_map *em;
589 int ret;
590 u32 *sums;
592 tree = &BTRFS_I(inode)->io_tree;
593 em_tree = &BTRFS_I(inode)->extent_tree;
595 /* we need the actual starting offset of this extent in the file */
596 spin_lock(&em_tree->lock);
597 em = lookup_extent_mapping(em_tree,
598 page_offset(bio->bi_io_vec->bv_page),
599 PAGE_CACHE_SIZE);
600 spin_unlock(&em_tree->lock);
602 compressed_len = em->block_len;
603 cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
604 atomic_set(&cb->pending_bios, 0);
605 cb->errors = 0;
606 cb->inode = inode;
607 cb->mirror_num = mirror_num;
608 sums = &cb->sums;
610 cb->start = em->orig_start;
611 em_len = em->len;
612 em_start = em->start;
614 free_extent_map(em);
615 em = NULL;
617 cb->len = uncompressed_len;
618 cb->compressed_len = compressed_len;
619 cb->orig_bio = bio;
621 nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
622 PAGE_CACHE_SIZE;
623 cb->compressed_pages = kmalloc(sizeof(struct page *) * nr_pages,
624 GFP_NOFS);
625 bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
627 for (page_index = 0; page_index < nr_pages; page_index++) {
628 cb->compressed_pages[page_index] = alloc_page(GFP_NOFS |
629 __GFP_HIGHMEM);
631 cb->nr_pages = nr_pages;
633 add_ra_bio_pages(inode, em_start + em_len, cb);
635 /* include any pages we added in add_ra-bio_pages */
636 uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
637 cb->len = uncompressed_len;
639 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
640 comp_bio->bi_private = cb;
641 comp_bio->bi_end_io = end_compressed_bio_read;
642 atomic_inc(&cb->pending_bios);
644 for (page_index = 0; page_index < nr_pages; page_index++) {
645 page = cb->compressed_pages[page_index];
646 page->mapping = inode->i_mapping;
647 page->index = em_start >> PAGE_CACHE_SHIFT;
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;
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);
661 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
662 BUG_ON(ret);
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
670 atomic_inc(&cb->pending_bios);
672 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
673 btrfs_lookup_bio_sums(root, inode, comp_bio,
674 sums);
676 sums += (comp_bio->bi_size + root->sectorsize - 1) /
677 root->sectorsize;
679 ret = btrfs_map_bio(root, READ, comp_bio,
680 mirror_num, 0);
681 BUG_ON(ret);
683 bio_put(comp_bio);
685 comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
686 GFP_NOFS);
687 comp_bio->bi_private = cb;
688 comp_bio->bi_end_io = end_compressed_bio_read;
690 bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
692 cur_disk_byte += PAGE_CACHE_SIZE;
694 bio_get(comp_bio);
696 ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
697 BUG_ON(ret);
699 if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM))
700 btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
702 ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
703 BUG_ON(ret);
705 bio_put(comp_bio);
706 return 0;