diff options
Diffstat (limited to 'fs/btrfs/compression.c')
| -rw-r--r-- | fs/btrfs/compression.c | 709 |
1 files changed, 709 insertions, 0 deletions
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c new file mode 100644 index 0000000..ee848d8 --- /dev/null +++ b/fs/btrfs/compression.c @@ -0,0 +1,709 @@ +/* + * Copyright (C) 2008 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + +#include <linux/kernel.h> +#include <linux/bio.h> +#include <linux/buffer_head.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/pagemap.h> +#include <linux/highmem.h> +#include <linux/time.h> +#include <linux/init.h> +#include <linux/string.h> +#include <linux/smp_lock.h> +#include <linux/backing-dev.h> +#include <linux/mpage.h> +#include <linux/swap.h> +#include <linux/writeback.h> +#include <linux/bit_spinlock.h> +#include <linux/version.h> +#include <linux/pagevec.h> +#include "compat.h" +#include "ctree.h" +#include "disk-io.h" +#include "transaction.h" +#include "btrfs_inode.h" +#include "volumes.h" +#include "ordered-data.h" +#include "compression.h" +#include "extent_io.h" +#include "extent_map.h" + +struct compressed_bio { + /* number of bios pending for this compressed extent */ + atomic_t pending_bios; + + /* the pages with the compressed data on them */ + struct page **compressed_pages; + + /* inode that owns this data */ + struct inode *inode; + + /* starting offset in the inode for our pages */ + u64 start; + + /* number of bytes in the inode we're working on */ + unsigned long len; + + /* number of bytes on disk */ + unsigned long compressed_len; + + /* number of compressed pages in the array */ + unsigned long nr_pages; + + /* IO errors */ + int errors; + int mirror_num; + + /* for reads, this is the bio we are copying the data into */ + struct bio *orig_bio; + + /* + * the start of a variable length array of checksums only + * used by reads + */ + u32 sums; +}; + +static inline int compressed_bio_size(struct btrfs_root *root, + unsigned long disk_size) +{ + u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy); + return sizeof(struct compressed_bio) + + ((disk_size + root->sectorsize - 1) / root->sectorsize) * + csum_size; +} + +static struct bio *compressed_bio_alloc(struct block_device *bdev, + u64 first_byte, gfp_t gfp_flags) +{ + struct bio *bio; + int nr_vecs; + + nr_vecs = bio_get_nr_vecs(bdev); + bio = bio_alloc(gfp_flags, nr_vecs); + + if (bio == NULL && (current->flags & PF_MEMALLOC)) { + while (!bio && (nr_vecs /= 2)) + bio = bio_alloc(gfp_flags, nr_vecs); + } + + if (bio) { + bio->bi_size = 0; + bio->bi_bdev = bdev; + bio->bi_sector = first_byte >> 9; + } + return bio; +} + +static int check_compressed_csum(struct inode *inode, + struct compressed_bio *cb, + u64 disk_start) +{ + int ret; + struct btrfs_root *root = BTRFS_I(inode)->root; + struct page *page; + unsigned long i; + char *kaddr; + u32 csum; + u32 *cb_sum = &cb->sums; + + if (btrfs_test_flag(inode, NODATASUM)) + return 0; + + for (i = 0; i < cb->nr_pages; i++) { + page = cb->compressed_pages[i]; + csum = ~(u32)0; + + kaddr = kmap_atomic(page, KM_USER0); + csum = btrfs_csum_data(root, kaddr, csum, PAGE_CACHE_SIZE); + btrfs_csum_final(csum, (char *)&csum); + kunmap_atomic(kaddr, KM_USER0); + + if (csum != *cb_sum) { + printk(KERN_INFO "btrfs csum failed ino %lu " + "extent %llu csum %u " + "wanted %u mirror %d\n", inode->i_ino, + (unsigned long long)disk_start, + csum, *cb_sum, cb->mirror_num); + ret = -EIO; + goto fail; + } + cb_sum++; + + } + ret = 0; +fail: + return ret; +} + +/* when we finish reading compressed pages from the disk, we + * decompress them and then run the bio end_io routines on the + * decompressed pages (in the inode address space). + * + * This allows the checksumming and other IO error handling routines + * to work normally + * + * The compressed pages are freed here, and it must be run + * in process context + */ +static void end_compressed_bio_read(struct bio *bio, int err) +{ + struct extent_io_tree *tree; + struct compressed_bio *cb = bio->bi_private; + struct inode *inode; + struct page *page; + unsigned long index; + int ret; + + if (err) + cb->errors = 1; + + /* if there are more bios still pending for this compressed + * extent, just exit + */ + if (!atomic_dec_and_test(&cb->pending_bios)) + goto out; + + inode = cb->inode; + ret = check_compressed_csum(inode, cb, (u64)bio->bi_sector << 9); + if (ret) + goto csum_failed; + + /* ok, we're the last bio for this extent, lets start + * the decompression. + */ + tree = &BTRFS_I(inode)->io_tree; + ret = btrfs_zlib_decompress_biovec(cb->compressed_pages, + cb->start, + cb->orig_bio->bi_io_vec, + cb->orig_bio->bi_vcnt, + cb->compressed_len); +csum_failed: + if (ret) + cb->errors = 1; + + /* release the compressed pages */ + index = 0; + for (index = 0; index < cb->nr_pages; index++) { + page = cb->compressed_pages[index]; + page->mapping = NULL; + page_cache_release(page); + } + + /* do io completion on the original bio */ + if (cb->errors) { + bio_io_error(cb->orig_bio); + } else { + int bio_index = 0; + struct bio_vec *bvec = cb->orig_bio->bi_io_vec; + + /* + * we have verified the checksum already, set page + * checked so the end_io handlers know about it + */ + while (bio_index < cb->orig_bio->bi_vcnt) { + SetPageChecked(bvec->bv_page); + bvec++; + bio_index++; + } + bio_endio(cb->orig_bio, 0); + } + + /* finally free the cb struct */ + kfree(cb->compressed_pages); + kfree(cb); +out: + bio_put(bio); +} + +/* + * Clear the writeback bits on all of the file + * pages for a compressed write + */ +static noinline int end_compressed_writeback(struct inode *inode, u64 start, + unsigned long ram_size) +{ + unsigned long index = start >> PAGE_CACHE_SHIFT; + unsigned long end_index = (start + ram_size - 1) >> PAGE_CACHE_SHIFT; + struct page *pages[16]; + unsigned long nr_pages = end_index - index + 1; + int i; + int ret; + + while (nr_pages > 0) { + ret = find_get_pages_contig(inode->i_mapping, index, + min_t(unsigned long, + nr_pages, ARRAY_SIZE(pages)), pages); + if (ret == 0) { + nr_pages -= 1; + index += 1; + continue; + } + for (i = 0; i < ret; i++) { + end_page_writeback(pages[i]); + page_cache_release(pages[i]); + } + nr_pages -= ret; + index += ret; + } + /* the inode may be gone now */ + return 0; +} + +/* + * do the cleanup once all the compressed pages hit the disk. + * This will clear writeback on the file pages and free the compressed + * pages. + * + * This also calls the writeback end hooks for the file pages so that + * metadata and checksums can be updated in the file. + */ +static void end_compressed_bio_write(struct bio *bio, int err) +{ + struct extent_io_tree *tree; + struct compressed_bio *cb = bio->bi_private; + struct inode *inode; + struct page *page; + unsigned long index; + + if (err) + cb->errors = 1; + + /* if there are more bios still pending for this compressed + * extent, just exit + */ + if (!atomic_dec_and_test(&cb->pending_bios)) + goto out; + + /* ok, we're the last bio for this extent, step one is to + * call back into the FS and do all the end_io operations + */ + inode = cb->inode; + tree = &BTRFS_I(inode)->io_tree; + cb->compressed_pages[0]->mapping = cb->inode->i_mapping; + tree->ops->writepage_end_io_hook(cb->compressed_pages[0], + cb->start, + cb->start + cb->len - 1, + NULL, 1); + cb->compressed_pages[0]->mapping = NULL; + + end_compressed_writeback(inode, cb->start, cb->len); + /* note, our inode could be gone now */ + + /* + * release the compressed pages, these came from alloc_page and + * are not attached to the inode at all + */ + index = 0; + for (index = 0; index < cb->nr_pages; index++) { + page = cb->compressed_pages[index]; + page->mapping = NULL; + page_cache_release(page); + } + + /* finally free the cb struct */ + kfree(cb->compressed_pages); + kfree(cb); +out: + bio_put(bio); +} + +/* + * worker function to build and submit bios for previously compressed pages. + * The corresponding pages in the inode should be marked for writeback + * and the compressed pages should have a reference on them for dropping + * when the IO is complete. + * + * This also checksums the file bytes and gets things ready for + * the end io hooks. + */ +int btrfs_submit_compressed_write(struct inode *inode, u64 start, + unsigned long len, u64 disk_start, + unsigned long compressed_len, + struct page **compressed_pages, + unsigned long nr_pages) +{ + struct bio *bio = NULL; + struct btrfs_root *root = BTRFS_I(inode)->root; + struct compressed_bio *cb; + unsigned long bytes_left; + struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; + int page_index = 0; + struct page *page; + u64 first_byte = disk_start; + struct block_device *bdev; + int ret; + + WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1)); + cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS); + atomic_set(&cb->pending_bios, 0); + cb->errors = 0; + cb->inode = inode; + cb->start = start; + cb->len = len; + cb->mirror_num = 0; + cb->compressed_pages = compressed_pages; + cb->compressed_len = compressed_len; + cb->orig_bio = NULL; + cb->nr_pages = nr_pages; + + bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev; + + bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS); + bio->bi_private = cb; + bio->bi_end_io = end_compressed_bio_write; + atomic_inc(&cb->pending_bios); + + /* create and submit bios for the compressed pages */ + bytes_left = compressed_len; + for (page_index = 0; page_index < cb->nr_pages; page_index++) { + page = compressed_pages[page_index]; + page->mapping = inode->i_mapping; + if (bio->bi_size) + ret = io_tree->ops->merge_bio_hook(page, 0, + PAGE_CACHE_SIZE, + bio, 0); + else + ret = 0; + + page->mapping = NULL; + if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < + PAGE_CACHE_SIZE) { + bio_get(bio); + + /* + * inc the count before we submit the bio so + * we know the end IO handler won't happen before + * we inc the count. Otherwise, the cb might get + * freed before we're done setting it up + */ + atomic_inc(&cb->pending_bios); + ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0); + BUG_ON(ret); + + ret = btrfs_csum_one_bio(root, inode, bio, start, 1); + BUG_ON(ret); + + ret = btrfs_map_bio(root, WRITE, bio, 0, 1); + BUG_ON(ret); + + bio_put(bio); + + bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS); + bio->bi_private = cb; + bio->bi_end_io = end_compressed_bio_write; + bio_add_page(bio, page, PAGE_CACHE_SIZE, 0); + } + if (bytes_left < PAGE_CACHE_SIZE) { + printk("bytes left %lu compress len %lu nr %lu\n", + bytes_left, cb->compressed_len, cb->nr_pages); + } + bytes_left -= PAGE_CACHE_SIZE; + first_byte += PAGE_CACHE_SIZE; + cond_resched(); + } + bio_get(bio); + + ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0); + BUG_ON(ret); + + ret = btrfs_csum_one_bio(root, inode, bio, start, 1); + BUG_ON(ret); + + ret = btrfs_map_bio(root, WRITE, bio, 0, 1); + BUG_ON(ret); + + bio_put(bio); + return 0; +} + +static noinline int add_ra_bio_pages(struct inode *inode, + u64 compressed_end, + struct compressed_bio *cb) +{ + unsigned long end_index; + unsigned long page_index; + u64 last_offset; + u64 isize = i_size_read(inode); + int ret; + struct page *page; + unsigned long nr_pages = 0; + struct extent_map *em; + struct address_space *mapping = inode->i_mapping; + struct pagevec pvec; + struct extent_map_tree *em_tree; + struct extent_io_tree *tree; + u64 end; + int misses = 0; + + page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page; + last_offset = (page_offset(page) + PAGE_CACHE_SIZE); + em_tree = &BTRFS_I(inode)->extent_tree; + tree = &BTRFS_I(inode)->io_tree; + + if (isize == 0) + return 0; + + end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT; + + pagevec_init(&pvec, 0); + while (last_offset < compressed_end) { + page_index = last_offset >> PAGE_CACHE_SHIFT; + + if (page_index > end_index) + break; + + rcu_read_lock(); + page = radix_tree_lookup(&mapping->page_tree, page_index); + rcu_read_unlock(); + if (page) { + misses++; + if (misses > 4) + break; + goto next; + } + + page = alloc_page(mapping_gfp_mask(mapping) | GFP_NOFS); + if (!page) + break; + + page->index = page_index; + /* + * what we want to do here is call add_to_page_cache_lru, + * but that isn't exported, so we reproduce it here + */ + if (add_to_page_cache(page, mapping, + page->index, GFP_NOFS)) { + page_cache_release(page); + goto next; + } + + /* open coding of lru_cache_add, also not exported */ + page_cache_get(page); + if (!pagevec_add(&pvec, page)) + __pagevec_lru_add_file(&pvec); + + end = last_offset + PAGE_CACHE_SIZE - 1; + /* + * at this point, we have a locked page in the page cache + * for these bytes in the file. But, we have to make + * sure they map to this compressed extent on disk. + */ + set_page_extent_mapped(page); + lock_extent(tree, last_offset, end, GFP_NOFS); + spin_lock(&em_tree->lock); + em = lookup_extent_mapping(em_tree, last_offset, + PAGE_CACHE_SIZE); + spin_unlock(&em_tree->lock); + + if (!em || last_offset < em->start || + (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) || + (em->block_start >> 9) != cb->orig_bio->bi_sector) { + free_extent_map(em); + unlock_extent(tree, last_offset, end, GFP_NOFS); + unlock_page(page); + page_cache_release(page); + break; + } + free_extent_map(em); + + if (page->index == end_index) { + char *userpage; + size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1); + + if (zero_offset) { + int zeros; + zeros = PAGE_CACHE_SIZE - zero_offset; + userpage = kmap_atomic(page, KM_USER0); + memset(userpage + zero_offset, 0, zeros); + flush_dcache_page(page); + kunmap_atomic(userpage, KM_USER0); + } + } + + ret = bio_add_page(cb->orig_bio, page, + PAGE_CACHE_SIZE, 0); + + if (ret == PAGE_CACHE_SIZE) { + nr_pages++; + page_cache_release(page); + } else { + unlock_extent(tree, last_offset, end, GFP_NOFS); + unlock_page(page); + page_cache_release(page); + break; + } +next: + last_offset += PAGE_CACHE_SIZE; + } + if (pagevec_count(&pvec)) + __pagevec_lru_add_file(&pvec); + return 0; +} + +/* + * for a compressed read, the bio we get passed has all the inode pages + * in it. We don't actually do IO on those pages but allocate new ones + * to hold the compressed pages on disk. + * + * bio->bi_sector points to the compressed extent on disk + * bio->bi_io_vec points to all of the inode pages + * bio->bi_vcnt is a count of pages + * + * After the compressed pages are read, we copy the bytes into the + * bio we were passed and then call the bio end_io calls + */ +int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, + int mirror_num, unsigned long bio_flags) +{ + struct extent_io_tree *tree; + struct extent_map_tree *em_tree; + struct compressed_bio *cb; + struct btrfs_root *root = BTRFS_I(inode)->root; + unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE; + unsigned long compressed_len; + unsigned long nr_pages; + unsigned long page_index; + struct page *page; + struct block_device *bdev; + struct bio *comp_bio; + u64 cur_disk_byte = (u64)bio->bi_sector << 9; + u64 em_len; + u64 em_start; + struct extent_map *em; + int ret; + u32 *sums; + + tree = &BTRFS_I(inode)->io_tree; + em_tree = &BTRFS_I(inode)->extent_tree; + + /* we need the actual starting offset of this extent in the file */ + spin_lock(&em_tree->lock); + em = lookup_extent_mapping(em_tree, + page_offset(bio->bi_io_vec->bv_page), + PAGE_CACHE_SIZE); + spin_unlock(&em_tree->lock); + + compressed_len = em->block_len; + cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS); + atomic_set(&cb->pending_bios, 0); + cb->errors = 0; + cb->inode = inode; + cb->mirror_num = mirror_num; + sums = &cb->sums; + + cb->start = em->orig_start; + em_len = em->len; + em_start = em->start; + + free_extent_map(em); + em = NULL; + + cb->len = uncompressed_len; + cb->compressed_len = compressed_len; + cb->orig_bio = bio; + + nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) / + PAGE_CACHE_SIZE; + cb->compressed_pages = kmalloc(sizeof(struct page *) * nr_pages, + GFP_NOFS); + bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev; + + for (page_index = 0; page_index < nr_pages; page_index++) { + cb->compressed_pages[page_index] = alloc_page(GFP_NOFS | + __GFP_HIGHMEM); + } + cb->nr_pages = nr_pages; + + add_ra_bio_pages(inode, em_start + em_len, cb); + + /* include any pages we added in add_ra-bio_pages */ + uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE; + cb->len = uncompressed_len; + + comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS); + comp_bio->bi_private = cb; + comp_bio->bi_end_io = end_compressed_bio_read; + atomic_inc(&cb->pending_bios); + + for (page_index = 0; page_index < nr_pages; page_index++) { + page = cb->compressed_pages[page_index]; + page->mapping = inode->i_mapping; + page->index = em_start >> PAGE_CACHE_SHIFT; + + if (comp_bio->bi_size) + ret = tree->ops->merge_bio_hook(page, 0, + PAGE_CACHE_SIZE, + comp_bio, 0); + else + ret = 0; + + page->mapping = NULL; + if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) < + PAGE_CACHE_SIZE) { + bio_get(comp_bio); + + ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0); + BUG_ON(ret); + + /* + * inc the count before we submit the bio so + * we know the end IO handler won't happen before + * we inc the count. Otherwise, the cb might get + * freed before we're done setting it up + */ + atomic_inc(&cb->pending_bios); + + if (!btrfs_test_flag(inode, NODATASUM)) { + btrfs_lookup_bio_sums(root, inode, comp_bio, + sums); + } + sums += (comp_bio->bi_size + root->sectorsize - 1) / + root->sectorsize; + + ret = btrfs_map_bio(root, READ, comp_bio, + mirror_num, 0); + BUG_ON(ret); + + bio_put(comp_bio); + + comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, + GFP_NOFS); + comp_bio->bi_private = cb; + comp_bio->bi_end_io = end_compressed_bio_read; + + bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0); + } + cur_disk_byte += PAGE_CACHE_SIZE; + } + bio_get(comp_bio); + + ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0); + BUG_ON(ret); + + if (!btrfs_test_flag(inode, NODATASUM)) + btrfs_lookup_bio_sums(root, inode, comp_bio, sums); + + ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0); + BUG_ON(ret); + + bio_put(comp_bio); + return 0; +} |
