diff options
Diffstat (limited to 'fs/btrfs/compression.c')
| -rw-r--r-- | fs/btrfs/compression.c | 526 |
1 files changed, 437 insertions, 89 deletions
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index a11a32058b50..6aad98cb343f 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -31,7 +31,7 @@ #include <linux/swap.h> #include <linux/writeback.h> #include <linux/bit_spinlock.h> -#include <linux/pagevec.h> +#include <linux/slab.h> #include "compat.h" #include "ctree.h" #include "disk-io.h" @@ -62,6 +62,9 @@ struct compressed_bio { /* 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; @@ -79,10 +82,15 @@ struct compressed_bio { 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); + 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; @@ -91,23 +99,10 @@ static inline int compressed_bio_size(struct btrfs_root *root, 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; + return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags); } static int check_compressed_csum(struct inode *inode, @@ -115,7 +110,6 @@ static int check_compressed_csum(struct inode *inode, u64 disk_start) { int ret; - struct btrfs_root *root = BTRFS_I(inode)->root; struct page *page; unsigned long i; char *kaddr; @@ -129,17 +123,17 @@ static int check_compressed_csum(struct inode *inode, page = cb->compressed_pages[i]; csum = ~(u32)0; - kaddr = kmap_atomic(page, KM_USER0); - csum = btrfs_csum_data(root, kaddr, csum, PAGE_CACHE_SIZE); + kaddr = kmap_atomic(page); + csum = btrfs_csum_data(kaddr, csum, PAGE_CACHE_SIZE); btrfs_csum_final(csum, (char *)&csum); - kunmap_atomic(kaddr, KM_USER0); + kunmap_atomic(kaddr); if (csum != *cb_sum) { - printk(KERN_INFO "btrfs csum failed ino %lu " + printk(KERN_INFO "btrfs csum failed ino %llu " "extent %llu csum %u " - "wanted %u mirror %d\n", inode->i_ino, - (unsigned long long)disk_start, - csum, *cb_sum, cb->mirror_num); + "wanted %u mirror %d\n", + btrfs_ino(inode), disk_start, csum, *cb_sum, + cb->mirror_num); ret = -EIO; goto fail; } @@ -163,7 +157,6 @@ fail: */ 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; @@ -187,12 +180,12 @@ static void end_compressed_bio_read(struct bio *bio, int err) /* 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); + 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; @@ -235,8 +228,8 @@ out: * 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) +static noinline void 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; @@ -262,7 +255,6 @@ static noinline int end_compressed_writeback(struct inode *inode, u64 start, index += ret; } /* the inode may be gone now */ - return 0; } /* @@ -343,14 +335,17 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start, struct compressed_bio *cb; unsigned long bytes_left; struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; - int page_index = 0; + 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; @@ -365,17 +360,21 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start, 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 (page_index = 0; page_index < cb->nr_pages; page_index++) { - page = compressed_pages[page_index]; + for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) { + page = compressed_pages[pg_index]; page->mapping = inode->i_mapping; if (bio->bi_size) - ret = io_tree->ops->merge_bio_hook(page, 0, + ret = io_tree->ops->merge_bio_hook(WRITE, page, 0, PAGE_CACHE_SIZE, bio, 0); else @@ -394,17 +393,21 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start, */ atomic_inc(&cb->pending_bios); ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0); - BUG_ON(ret); + BUG_ON(ret); /* -ENOMEM */ - ret = btrfs_csum_one_bio(root, inode, bio, start, 1); - BUG_ON(ret); + 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); + 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); @@ -420,13 +423,15 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start, bio_get(bio); ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0); - BUG_ON(ret); + BUG_ON(ret); /* -ENOMEM */ - ret = btrfs_csum_one_bio(root, inode, bio, start, 1); - BUG_ON(ret); + 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); + BUG_ON(ret); /* -ENOMEM */ bio_put(bio); return 0; @@ -437,7 +442,7 @@ static noinline int add_ra_bio_pages(struct inode *inode, struct compressed_bio *cb) { unsigned long end_index; - unsigned long page_index; + unsigned long pg_index; u64 last_offset; u64 isize = i_size_read(inode); int ret; @@ -445,7 +450,6 @@ static noinline int add_ra_bio_pages(struct inode *inode, 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; @@ -461,15 +465,14 @@ static noinline int add_ra_bio_pages(struct inode *inode, 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; + pg_index = last_offset >> PAGE_CACHE_SHIFT; - if (page_index > end_index) + if (pg_index > end_index) break; rcu_read_lock(); - page = radix_tree_lookup(&mapping->page_tree, page_index); + page = radix_tree_lookup(&mapping->page_tree, pg_index); rcu_read_unlock(); if (page) { misses++; @@ -478,26 +481,17 @@ static noinline int add_ra_bio_pages(struct inode *inode, goto next; } - page = alloc_page(mapping_gfp_mask(mapping) | GFP_NOFS); + page = __page_cache_alloc(mapping_gfp_mask(mapping) & + ~__GFP_FS); 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)) { + if (add_to_page_cache_lru(page, mapping, pg_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 @@ -505,7 +499,7 @@ static noinline int add_ra_bio_pages(struct inode *inode, * sure they map to this compressed extent on disk. */ set_page_extent_mapped(page); - lock_extent(tree, last_offset, end, GFP_NOFS); + lock_extent(tree, last_offset, end); read_lock(&em_tree->lock); em = lookup_extent_mapping(em_tree, last_offset, PAGE_CACHE_SIZE); @@ -515,7 +509,7 @@ static noinline int add_ra_bio_pages(struct inode *inode, (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_extent(tree, last_offset, end); unlock_page(page); page_cache_release(page); break; @@ -529,10 +523,10 @@ static noinline int add_ra_bio_pages(struct inode *inode, if (zero_offset) { int zeros; zeros = PAGE_CACHE_SIZE - zero_offset; - userpage = kmap_atomic(page, KM_USER0); + userpage = kmap_atomic(page); memset(userpage + zero_offset, 0, zeros); flush_dcache_page(page); - kunmap_atomic(userpage, KM_USER0); + kunmap_atomic(userpage); } } @@ -543,7 +537,7 @@ static noinline int add_ra_bio_pages(struct inode *inode, nr_pages++; page_cache_release(page); } else { - unlock_extent(tree, last_offset, end, GFP_NOFS); + unlock_extent(tree, last_offset, end); unlock_page(page); page_cache_release(page); break; @@ -551,8 +545,6 @@ static noinline int add_ra_bio_pages(struct inode *inode, next: last_offset += PAGE_CACHE_SIZE; } - if (pagevec_count(&pvec)) - __pagevec_lru_add_file(&pvec); return 0; } @@ -578,7 +570,7 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE; unsigned long compressed_len; unsigned long nr_pages; - unsigned long page_index; + unsigned long pg_index; struct page *page; struct block_device *bdev; struct bio *comp_bio; @@ -586,7 +578,8 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, u64 em_len; u64 em_start; struct extent_map *em; - int ret; + int ret = -ENOMEM; + int faili = 0; u32 *sums; tree = &BTRFS_I(inode)->io_tree; @@ -598,9 +591,14 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, 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; @@ -616,38 +614,54 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, cb->len = uncompressed_len; cb->compressed_len = compressed_len; + cb->compress_type = extent_compress_type(bio_flags); cb->orig_bio = bio; nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE; - cb->compressed_pages = kmalloc(sizeof(struct page *) * nr_pages, + cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS); + if (!cb->compressed_pages) + goto fail1; + 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 | + 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; - add_ra_bio_pages(inode, em_start + em_len, cb); + /* 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 (page_index = 0; page_index < nr_pages; page_index++) { - page = cb->compressed_pages[page_index]; + 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_size) - ret = tree->ops->merge_bio_hook(page, 0, + ret = tree->ops->merge_bio_hook(READ, page, 0, PAGE_CACHE_SIZE, comp_bio, 0); else @@ -659,7 +673,7 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, bio_get(comp_bio); ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0); - BUG_ON(ret); + BUG_ON(ret); /* -ENOMEM */ /* * inc the count before we submit the bio so @@ -670,20 +684,23 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, atomic_inc(&cb->pending_bios); if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) { - btrfs_lookup_bio_sums(root, inode, comp_bio, - sums); + ret = btrfs_lookup_bio_sums(root, inode, + comp_bio, sums); + BUG_ON(ret); /* -ENOMEM */ } sums += (comp_bio->bi_size + root->sectorsize - 1) / root->sectorsize; ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0); - BUG_ON(ret); + 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; @@ -694,14 +711,345 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, bio_get(comp_bio); ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0); - BUG_ON(ret); + BUG_ON(ret); /* -ENOMEM */ - if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) - btrfs_lookup_bio_sums(root, inode, comp_bio, sums); + 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); - BUG_ON(ret); + 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 struct btrfs_compress_op *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_tail(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 -1; + + 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 -ENOMEM; + + 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 -ENOMEM; + + 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; } |