diff options
Diffstat (limited to 'fs/btrfs/compression.c')
| -rw-r--r-- | fs/btrfs/compression.c | 1091 |
1 files changed, 1091 insertions, 0 deletions
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c new file mode 100644 index 000000000..ce62324c7 --- /dev/null +++ b/fs/btrfs/compression.c @@ -0,0 +1,1091 @@ +/* + * 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/backing-dev.h> +#include <linux/mpage.h> +#include <linux/swap.h> +#include <linux/writeback.h> +#include <linux/bit_spinlock.h> +#include <linux/slab.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; + + /* the compression algorithm for this bio */ + int compress_type; + + /* 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 int btrfs_decompress_biovec(int type, struct page **pages_in, + u64 disk_start, struct bio_vec *bvec, + int vcnt, size_t srclen); + +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) + + (DIV_ROUND_UP(disk_size, root->sectorsize)) * csum_size; +} + +static struct bio *compressed_bio_alloc(struct block_device *bdev, + u64 first_byte, gfp_t gfp_flags) +{ + int nr_vecs; + + nr_vecs = bio_get_nr_vecs(bdev); + return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags); +} + +static int check_compressed_csum(struct inode *inode, + struct compressed_bio *cb, + u64 disk_start) +{ + int ret; + struct page *page; + unsigned long i; + char *kaddr; + u32 csum; + u32 *cb_sum = &cb->sums; + + if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) + return 0; + + for (i = 0; i < cb->nr_pages; i++) { + page = cb->compressed_pages[i]; + csum = ~(u32)0; + + kaddr = kmap_atomic(page); + csum = btrfs_csum_data(kaddr, csum, PAGE_CACHE_SIZE); + btrfs_csum_final(csum, (char *)&csum); + kunmap_atomic(kaddr); + + if (csum != *cb_sum) { + btrfs_info(BTRFS_I(inode)->root->fs_info, + "csum failed ino %llu extent %llu csum %u wanted %u mirror %d", + btrfs_ino(inode), 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 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_iter.bi_sector << 9); + if (ret) + goto csum_failed; + + /* ok, we're the last bio for this extent, lets start + * the decompression. + */ + ret = btrfs_decompress_biovec(cb->compress_type, + 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 i; + struct bio_vec *bvec; + + /* + * we have verified the checksum already, set page + * checked so the end_io handlers know about it + */ + bio_for_each_segment_all(bvec, cb->orig_bio, i) + SetPageChecked(bvec->bv_page); + + 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 void end_compressed_writeback(struct inode *inode, + const struct compressed_bio *cb) +{ + unsigned long index = cb->start >> PAGE_CACHE_SHIFT; + unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_CACHE_SHIFT; + struct page *pages[16]; + unsigned long nr_pages = end_index - index + 1; + int i; + int ret; + + if (cb->errors) + mapping_set_error(inode->i_mapping, -EIO); + + 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++) { + if (cb->errors) + SetPageError(pages[i]); + end_page_writeback(pages[i]); + page_cache_release(pages[i]); + } + nr_pages -= ret; + index += ret; + } + /* the inode may be gone now */ +} + +/* + * 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, + err ? 0 : 1); + cb->compressed_pages[0]->mapping = NULL; + + end_compressed_writeback(inode, cb); + /* 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 pg_index = 0; + struct page *page; + u64 first_byte = disk_start; + struct block_device *bdev; + int ret; + int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM; + + WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1)); + cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS); + if (!cb) + return -ENOMEM; + 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); + if (!bio) { + kfree(cb); + return -ENOMEM; + } + 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 (pg_index = 0; pg_index < cb->nr_pages; pg_index++) { + page = compressed_pages[pg_index]; + page->mapping = inode->i_mapping; + if (bio->bi_iter.bi_size) + ret = io_tree->ops->merge_bio_hook(WRITE, 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, + BTRFS_WQ_ENDIO_DATA); + BUG_ON(ret); /* -ENOMEM */ + + if (!skip_sum) { + ret = btrfs_csum_one_bio(root, inode, bio, + start, 1); + BUG_ON(ret); /* -ENOMEM */ + } + + ret = btrfs_map_bio(root, WRITE, bio, 0, 1); + BUG_ON(ret); /* -ENOMEM */ + + bio_put(bio); + + bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS); + BUG_ON(!bio); + 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) { + btrfs_info(BTRFS_I(inode)->root->fs_info, + "bytes left %lu compress len %lu nr %lu", + 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, BTRFS_WQ_ENDIO_DATA); + BUG_ON(ret); /* -ENOMEM */ + + if (!skip_sum) { + ret = btrfs_csum_one_bio(root, inode, bio, start, 1); + BUG_ON(ret); /* -ENOMEM */ + } + + ret = btrfs_map_bio(root, WRITE, bio, 0, 1); + BUG_ON(ret); /* -ENOMEM */ + + 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 pg_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 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; + + while (last_offset < compressed_end) { + pg_index = last_offset >> PAGE_CACHE_SHIFT; + + if (pg_index > end_index) + break; + + rcu_read_lock(); + page = radix_tree_lookup(&mapping->page_tree, pg_index); + rcu_read_unlock(); + if (page && !radix_tree_exceptional_entry(page)) { + misses++; + if (misses > 4) + break; + goto next; + } + + page = __page_cache_alloc(mapping_gfp_mask(mapping) & + ~__GFP_FS); + if (!page) + break; + + if (add_to_page_cache_lru(page, mapping, pg_index, + GFP_NOFS)) { + page_cache_release(page); + goto next; + } + + 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); + read_lock(&em_tree->lock); + em = lookup_extent_mapping(em_tree, last_offset, + PAGE_CACHE_SIZE); + read_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_iter.bi_sector) { + free_extent_map(em); + unlock_extent(tree, last_offset, end); + 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); + memset(userpage + zero_offset, 0, zeros); + flush_dcache_page(page); + kunmap_atomic(userpage); + } + } + + 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); + unlock_page(page); + page_cache_release(page); + break; + } +next: + last_offset += PAGE_CACHE_SIZE; + } + 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_iter.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 pg_index; + struct page *page; + struct block_device *bdev; + struct bio *comp_bio; + u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9; + u64 em_len; + u64 em_start; + struct extent_map *em; + int ret = -ENOMEM; + int faili = 0; + 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 */ + read_lock(&em_tree->lock); + em = lookup_extent_mapping(em_tree, + page_offset(bio->bi_io_vec->bv_page), + PAGE_CACHE_SIZE); + read_unlock(&em_tree->lock); + if (!em) + return -EIO; + + compressed_len = em->block_len; + cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS); + if (!cb) + goto out; + + 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->compress_type = extent_compress_type(bio_flags); + cb->orig_bio = bio; + + nr_pages = DIV_ROUND_UP(compressed_len, PAGE_CACHE_SIZE); + cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *), + GFP_NOFS); + if (!cb->compressed_pages) + goto fail1; + + bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev; + + for (pg_index = 0; pg_index < nr_pages; pg_index++) { + cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS | + __GFP_HIGHMEM); + if (!cb->compressed_pages[pg_index]) { + faili = pg_index - 1; + ret = -ENOMEM; + goto fail2; + } + } + faili = nr_pages - 1; + cb->nr_pages = nr_pages; + + /* In the parent-locked case, we only locked the range we are + * interested in. In all other cases, we can opportunistically + * cache decompressed data that goes beyond the requested range. */ + if (!(bio_flags & EXTENT_BIO_PARENT_LOCKED)) + 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); + if (!comp_bio) + goto fail2; + comp_bio->bi_private = cb; + comp_bio->bi_end_io = end_compressed_bio_read; + atomic_inc(&cb->pending_bios); + + for (pg_index = 0; pg_index < nr_pages; pg_index++) { + page = cb->compressed_pages[pg_index]; + page->mapping = inode->i_mapping; + page->index = em_start >> PAGE_CACHE_SHIFT; + + if (comp_bio->bi_iter.bi_size) + ret = tree->ops->merge_bio_hook(READ, 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, + BTRFS_WQ_ENDIO_DATA); + BUG_ON(ret); /* -ENOMEM */ + + /* + * 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_I(inode)->flags & BTRFS_INODE_NODATASUM)) { + ret = btrfs_lookup_bio_sums(root, inode, + comp_bio, sums); + BUG_ON(ret); /* -ENOMEM */ + } + sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size, + root->sectorsize); + + ret = btrfs_map_bio(root, READ, comp_bio, + mirror_num, 0); + if (ret) + bio_endio(comp_bio, ret); + + bio_put(comp_bio); + + comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, + GFP_NOFS); + BUG_ON(!comp_bio); + 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, + BTRFS_WQ_ENDIO_DATA); + BUG_ON(ret); /* -ENOMEM */ + + if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) { + ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums); + BUG_ON(ret); /* -ENOMEM */ + } + + ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0); + if (ret) + bio_endio(comp_bio, ret); + + bio_put(comp_bio); + return 0; + +fail2: + while (faili >= 0) { + __free_page(cb->compressed_pages[faili]); + faili--; + } + + kfree(cb->compressed_pages); +fail1: + kfree(cb); +out: + free_extent_map(em); + return ret; +} + +static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES]; +static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES]; +static int comp_num_workspace[BTRFS_COMPRESS_TYPES]; +static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES]; +static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES]; + +static const struct btrfs_compress_op * const btrfs_compress_op[] = { + &btrfs_zlib_compress, + &btrfs_lzo_compress, +}; + +void __init btrfs_init_compress(void) +{ + int i; + + for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) { + INIT_LIST_HEAD(&comp_idle_workspace[i]); + spin_lock_init(&comp_workspace_lock[i]); + atomic_set(&comp_alloc_workspace[i], 0); + init_waitqueue_head(&comp_workspace_wait[i]); + } +} + +/* + * this finds an available workspace or allocates a new one + * ERR_PTR is returned if things go bad. + */ +static struct list_head *find_workspace(int type) +{ + struct list_head *workspace; + int cpus = num_online_cpus(); + int idx = type - 1; + + struct list_head *idle_workspace = &comp_idle_workspace[idx]; + spinlock_t *workspace_lock = &comp_workspace_lock[idx]; + atomic_t *alloc_workspace = &comp_alloc_workspace[idx]; + wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx]; + int *num_workspace = &comp_num_workspace[idx]; +again: + spin_lock(workspace_lock); + if (!list_empty(idle_workspace)) { + workspace = idle_workspace->next; + list_del(workspace); + (*num_workspace)--; + spin_unlock(workspace_lock); + return workspace; + + } + if (atomic_read(alloc_workspace) > cpus) { + DEFINE_WAIT(wait); + + spin_unlock(workspace_lock); + prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE); + if (atomic_read(alloc_workspace) > cpus && !*num_workspace) + schedule(); + finish_wait(workspace_wait, &wait); + goto again; + } + atomic_inc(alloc_workspace); + spin_unlock(workspace_lock); + + workspace = btrfs_compress_op[idx]->alloc_workspace(); + if (IS_ERR(workspace)) { + atomic_dec(alloc_workspace); + wake_up(workspace_wait); + } + return workspace; +} + +/* + * put a workspace struct back on the list or free it if we have enough + * idle ones sitting around + */ +static void free_workspace(int type, struct list_head *workspace) +{ + int idx = type - 1; + struct list_head *idle_workspace = &comp_idle_workspace[idx]; + spinlock_t *workspace_lock = &comp_workspace_lock[idx]; + atomic_t *alloc_workspace = &comp_alloc_workspace[idx]; + wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx]; + int *num_workspace = &comp_num_workspace[idx]; + + spin_lock(workspace_lock); + if (*num_workspace < num_online_cpus()) { + list_add(workspace, idle_workspace); + (*num_workspace)++; + spin_unlock(workspace_lock); + goto wake; + } + spin_unlock(workspace_lock); + + btrfs_compress_op[idx]->free_workspace(workspace); + atomic_dec(alloc_workspace); +wake: + smp_mb(); + if (waitqueue_active(workspace_wait)) + wake_up(workspace_wait); +} + +/* + * cleanup function for module exit + */ +static void free_workspaces(void) +{ + struct list_head *workspace; + int i; + + for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) { + while (!list_empty(&comp_idle_workspace[i])) { + workspace = comp_idle_workspace[i].next; + list_del(workspace); + btrfs_compress_op[i]->free_workspace(workspace); + atomic_dec(&comp_alloc_workspace[i]); + } + } +} + +/* + * given an address space and start/len, compress the bytes. + * + * pages are allocated to hold the compressed result and stored + * in 'pages' + * + * out_pages is used to return the number of pages allocated. There + * may be pages allocated even if we return an error + * + * total_in is used to return the number of bytes actually read. It + * may be smaller then len if we had to exit early because we + * ran out of room in the pages array or because we cross the + * max_out threshold. + * + * total_out is used to return the total number of compressed bytes + * + * max_out tells us the max number of bytes that we're allowed to + * stuff into pages + */ +int btrfs_compress_pages(int type, struct address_space *mapping, + u64 start, unsigned long len, + struct page **pages, + unsigned long nr_dest_pages, + unsigned long *out_pages, + unsigned long *total_in, + unsigned long *total_out, + unsigned long max_out) +{ + struct list_head *workspace; + int ret; + + workspace = find_workspace(type); + if (IS_ERR(workspace)) + return PTR_ERR(workspace); + + ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping, + start, len, pages, + nr_dest_pages, out_pages, + total_in, total_out, + max_out); + free_workspace(type, workspace); + return ret; +} + +/* + * pages_in is an array of pages with compressed data. + * + * disk_start is the starting logical offset of this array in the file + * + * bvec is a bio_vec of pages from the file that we want to decompress into + * + * vcnt is the count of pages in the biovec + * + * srclen is the number of bytes in pages_in + * + * The basic idea is that we have a bio that was created by readpages. + * The pages in the bio are for the uncompressed data, and they may not + * be contiguous. They all correspond to the range of bytes covered by + * the compressed extent. + */ +static int btrfs_decompress_biovec(int type, struct page **pages_in, + u64 disk_start, struct bio_vec *bvec, + int vcnt, size_t srclen) +{ + struct list_head *workspace; + int ret; + + workspace = find_workspace(type); + if (IS_ERR(workspace)) + return PTR_ERR(workspace); + + ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in, + disk_start, + bvec, vcnt, srclen); + free_workspace(type, workspace); + return ret; +} + +/* + * a less complex decompression routine. Our compressed data fits in a + * single page, and we want to read a single page out of it. + * start_byte tells us the offset into the compressed data we're interested in + */ +int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page, + unsigned long start_byte, size_t srclen, size_t destlen) +{ + struct list_head *workspace; + int ret; + + workspace = find_workspace(type); + if (IS_ERR(workspace)) + return PTR_ERR(workspace); + + ret = btrfs_compress_op[type-1]->decompress(workspace, data_in, + dest_page, start_byte, + srclen, destlen); + + free_workspace(type, workspace); + return ret; +} + +void btrfs_exit_compress(void) +{ + free_workspaces(); +} + +/* + * Copy uncompressed data from working buffer to pages. + * + * buf_start is the byte offset we're of the start of our workspace buffer. + * + * total_out is the last byte of the buffer + */ +int btrfs_decompress_buf2page(char *buf, unsigned long buf_start, + unsigned long total_out, u64 disk_start, + struct bio_vec *bvec, int vcnt, + unsigned long *pg_index, + unsigned long *pg_offset) +{ + unsigned long buf_offset; + unsigned long current_buf_start; + unsigned long start_byte; + unsigned long working_bytes = total_out - buf_start; + unsigned long bytes; + char *kaddr; + struct page *page_out = bvec[*pg_index].bv_page; + + /* + * start byte is the first byte of the page we're currently + * copying into relative to the start of the compressed data. + */ + start_byte = page_offset(page_out) - disk_start; + + /* we haven't yet hit data corresponding to this page */ + if (total_out <= start_byte) + return 1; + + /* + * the start of the data we care about is offset into + * the middle of our working buffer + */ + if (total_out > start_byte && buf_start < start_byte) { + buf_offset = start_byte - buf_start; + working_bytes -= buf_offset; + } else { + buf_offset = 0; + } + current_buf_start = buf_start; + + /* copy bytes from the working buffer into the pages */ + while (working_bytes > 0) { + bytes = min(PAGE_CACHE_SIZE - *pg_offset, + PAGE_CACHE_SIZE - buf_offset); + bytes = min(bytes, working_bytes); + kaddr = kmap_atomic(page_out); + memcpy(kaddr + *pg_offset, buf + buf_offset, bytes); + kunmap_atomic(kaddr); + flush_dcache_page(page_out); + + *pg_offset += bytes; + buf_offset += bytes; + working_bytes -= bytes; + current_buf_start += bytes; + + /* check if we need to pick another page */ + if (*pg_offset == PAGE_CACHE_SIZE) { + (*pg_index)++; + if (*pg_index >= vcnt) + return 0; + + page_out = bvec[*pg_index].bv_page; + *pg_offset = 0; + start_byte = page_offset(page_out) - disk_start; + + /* + * make sure our new page is covered by this + * working buffer + */ + if (total_out <= start_byte) + return 1; + + /* + * the next page in the biovec might not be adjacent + * to the last page, but it might still be found + * inside this working buffer. bump our offset pointer + */ + if (total_out > start_byte && + current_buf_start < start_byte) { + buf_offset = start_byte - buf_start; + working_bytes = total_out - start_byte; + current_buf_start = buf_start + buf_offset; + } + } + } + + return 1; +} + +/* + * When uncompressing data, we need to make sure and zero any parts of + * the biovec that were not filled in by the decompression code. pg_index + * and pg_offset indicate the last page and the last offset of that page + * that have been filled in. This will zero everything remaining in the + * biovec. + */ +void btrfs_clear_biovec_end(struct bio_vec *bvec, int vcnt, + unsigned long pg_index, + unsigned long pg_offset) +{ + while (pg_index < vcnt) { + struct page *page = bvec[pg_index].bv_page; + unsigned long off = bvec[pg_index].bv_offset; + unsigned long len = bvec[pg_index].bv_len; + + if (pg_offset < off) + pg_offset = off; + if (pg_offset < off + len) { + unsigned long bytes = off + len - pg_offset; + char *kaddr; + + kaddr = kmap_atomic(page); + memset(kaddr + pg_offset, 0, bytes); + kunmap_atomic(kaddr); + } + pg_index++; + pg_offset = 0; + } +} |