| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Copyright (C) 2008 Oracle. All rights reserved. |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/bio.h> |
| #include <linux/file.h> |
| #include <linux/fs.h> |
| #include <linux/pagemap.h> |
| #include <linux/pagevec.h> |
| #include <linux/highmem.h> |
| #include <linux/kthread.h> |
| #include <linux/time.h> |
| #include <linux/init.h> |
| #include <linux/string.h> |
| #include <linux/backing-dev.h> |
| #include <linux/writeback.h> |
| #include <linux/psi.h> |
| #include <linux/slab.h> |
| #include <linux/sched/mm.h> |
| #include <linux/log2.h> |
| #include <crypto/hash.h> |
| #include "misc.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" |
| #include "subpage.h" |
| #include "zoned.h" |
| |
| static const char* const btrfs_compress_types[] = { "", "zlib", "lzo", "zstd" }; |
| |
| const char* btrfs_compress_type2str(enum btrfs_compression_type type) |
| { |
| switch (type) { |
| case BTRFS_COMPRESS_ZLIB: |
| case BTRFS_COMPRESS_LZO: |
| case BTRFS_COMPRESS_ZSTD: |
| case BTRFS_COMPRESS_NONE: |
| return btrfs_compress_types[type]; |
| default: |
| break; |
| } |
| |
| return NULL; |
| } |
| |
| bool btrfs_compress_is_valid_type(const char *str, size_t len) |
| { |
| int i; |
| |
| for (i = 1; i < ARRAY_SIZE(btrfs_compress_types); i++) { |
| size_t comp_len = strlen(btrfs_compress_types[i]); |
| |
| if (len < comp_len) |
| continue; |
| |
| if (!strncmp(btrfs_compress_types[i], str, comp_len)) |
| return true; |
| } |
| return false; |
| } |
| |
| static int compression_compress_pages(int type, struct list_head *ws, |
| struct address_space *mapping, u64 start, struct page **pages, |
| unsigned long *out_pages, unsigned long *total_in, |
| unsigned long *total_out) |
| { |
| switch (type) { |
| case BTRFS_COMPRESS_ZLIB: |
| return zlib_compress_pages(ws, mapping, start, pages, |
| out_pages, total_in, total_out); |
| case BTRFS_COMPRESS_LZO: |
| return lzo_compress_pages(ws, mapping, start, pages, |
| out_pages, total_in, total_out); |
| case BTRFS_COMPRESS_ZSTD: |
| return zstd_compress_pages(ws, mapping, start, pages, |
| out_pages, total_in, total_out); |
| case BTRFS_COMPRESS_NONE: |
| default: |
| /* |
| * This can happen when compression races with remount setting |
| * it to 'no compress', while caller doesn't call |
| * inode_need_compress() to check if we really need to |
| * compress. |
| * |
| * Not a big deal, just need to inform caller that we |
| * haven't allocated any pages yet. |
| */ |
| *out_pages = 0; |
| return -E2BIG; |
| } |
| } |
| |
| static int compression_decompress_bio(struct list_head *ws, |
| struct compressed_bio *cb) |
| { |
| switch (cb->compress_type) { |
| case BTRFS_COMPRESS_ZLIB: return zlib_decompress_bio(ws, cb); |
| case BTRFS_COMPRESS_LZO: return lzo_decompress_bio(ws, cb); |
| case BTRFS_COMPRESS_ZSTD: return zstd_decompress_bio(ws, cb); |
| case BTRFS_COMPRESS_NONE: |
| default: |
| /* |
| * This can't happen, the type is validated several times |
| * before we get here. |
| */ |
| BUG(); |
| } |
| } |
| |
| static int compression_decompress(int type, struct list_head *ws, |
| unsigned char *data_in, struct page *dest_page, |
| unsigned long start_byte, size_t srclen, size_t destlen) |
| { |
| switch (type) { |
| case BTRFS_COMPRESS_ZLIB: return zlib_decompress(ws, data_in, dest_page, |
| start_byte, srclen, destlen); |
| case BTRFS_COMPRESS_LZO: return lzo_decompress(ws, data_in, dest_page, |
| start_byte, srclen, destlen); |
| case BTRFS_COMPRESS_ZSTD: return zstd_decompress(ws, data_in, dest_page, |
| start_byte, srclen, destlen); |
| case BTRFS_COMPRESS_NONE: |
| default: |
| /* |
| * This can't happen, the type is validated several times |
| * before we get here. |
| */ |
| BUG(); |
| } |
| } |
| |
| static int btrfs_decompress_bio(struct compressed_bio *cb); |
| |
| static void finish_compressed_bio_read(struct compressed_bio *cb) |
| { |
| unsigned int index; |
| struct page *page; |
| |
| if (cb->status == BLK_STS_OK) |
| cb->status = errno_to_blk_status(btrfs_decompress_bio(cb)); |
| |
| /* Release the compressed pages */ |
| for (index = 0; index < cb->nr_pages; index++) { |
| page = cb->compressed_pages[index]; |
| page->mapping = NULL; |
| put_page(page); |
| } |
| |
| /* Do io completion on the original bio */ |
| btrfs_bio_end_io(btrfs_bio(cb->orig_bio), cb->status); |
| |
| /* Finally free the cb struct */ |
| kfree(cb->compressed_pages); |
| kfree(cb); |
| } |
| |
| /* |
| * Verify the checksums and kick off repair if needed on the uncompressed data |
| * before decompressing it into the original bio and freeing the uncompressed |
| * pages. |
| */ |
| static void end_compressed_bio_read(struct btrfs_bio *bbio) |
| { |
| struct compressed_bio *cb = bbio->private; |
| struct inode *inode = cb->inode; |
| struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); |
| struct btrfs_inode *bi = BTRFS_I(inode); |
| bool csum = !(bi->flags & BTRFS_INODE_NODATASUM) && |
| !test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state); |
| blk_status_t status = bbio->bio.bi_status; |
| struct bvec_iter iter; |
| struct bio_vec bv; |
| u32 offset; |
| |
| btrfs_bio_for_each_sector(fs_info, bv, bbio, iter, offset) { |
| u64 start = bbio->file_offset + offset; |
| |
| if (!status && |
| (!csum || !btrfs_check_data_csum(inode, bbio, offset, |
| bv.bv_page, bv.bv_offset))) { |
| btrfs_clean_io_failure(bi, start, bv.bv_page, |
| bv.bv_offset); |
| } else { |
| int ret; |
| |
| refcount_inc(&cb->pending_ios); |
| ret = btrfs_repair_one_sector(inode, bbio, offset, |
| bv.bv_page, bv.bv_offset, |
| btrfs_submit_data_read_bio); |
| if (ret) { |
| refcount_dec(&cb->pending_ios); |
| status = errno_to_blk_status(ret); |
| } |
| } |
| } |
| |
| if (status) |
| cb->status = status; |
| |
| if (refcount_dec_and_test(&cb->pending_ios)) |
| finish_compressed_bio_read(cb); |
| btrfs_bio_free_csum(bbio); |
| bio_put(&bbio->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) |
| { |
| struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); |
| unsigned long index = cb->start >> PAGE_SHIFT; |
| unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT; |
| struct folio_batch fbatch; |
| const int errno = blk_status_to_errno(cb->status); |
| int i; |
| int ret; |
| |
| if (errno) |
| mapping_set_error(inode->i_mapping, errno); |
| |
| folio_batch_init(&fbatch); |
| while (index <= end_index) { |
| ret = filemap_get_folios(inode->i_mapping, &index, end_index, |
| &fbatch); |
| |
| if (ret == 0) |
| return; |
| |
| for (i = 0; i < ret; i++) { |
| struct folio *folio = fbatch.folios[i]; |
| |
| if (errno) |
| folio_set_error(folio); |
| btrfs_page_clamp_clear_writeback(fs_info, &folio->page, |
| cb->start, cb->len); |
| } |
| folio_batch_release(&fbatch); |
| } |
| /* the inode may be gone now */ |
| } |
| |
| static void finish_compressed_bio_write(struct compressed_bio *cb) |
| { |
| struct inode *inode = cb->inode; |
| unsigned int index; |
| |
| /* |
| * 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. |
| */ |
| btrfs_writepage_endio_finish_ordered(BTRFS_I(inode), NULL, |
| cb->start, cb->start + cb->len - 1, |
| cb->status == BLK_STS_OK); |
| |
| if (cb->writeback) |
| 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 |
| */ |
| for (index = 0; index < cb->nr_pages; index++) { |
| struct page *page = cb->compressed_pages[index]; |
| |
| page->mapping = NULL; |
| put_page(page); |
| } |
| |
| /* Finally free the cb struct */ |
| kfree(cb->compressed_pages); |
| kfree(cb); |
| } |
| |
| static void btrfs_finish_compressed_write_work(struct work_struct *work) |
| { |
| struct compressed_bio *cb = |
| container_of(work, struct compressed_bio, write_end_work); |
| |
| finish_compressed_bio_write(cb); |
| } |
| |
| /* |
| * 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 btrfs_bio *bbio) |
| { |
| struct compressed_bio *cb = bbio->private; |
| |
| if (bbio->bio.bi_status) |
| cb->status = bbio->bio.bi_status; |
| |
| if (refcount_dec_and_test(&cb->pending_ios)) { |
| struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb); |
| |
| btrfs_record_physical_zoned(cb->inode, cb->start, &bbio->bio); |
| queue_work(fs_info->compressed_write_workers, &cb->write_end_work); |
| } |
| bio_put(&bbio->bio); |
| } |
| |
| /* |
| * Allocate a compressed_bio, which will be used to read/write on-disk |
| * (aka, compressed) * data. |
| * |
| * @cb: The compressed_bio structure, which records all the needed |
| * information to bind the compressed data to the uncompressed |
| * page cache. |
| * @disk_byten: The logical bytenr where the compressed data will be read |
| * from or written to. |
| * @endio_func: The endio function to call after the IO for compressed data |
| * is finished. |
| * @next_stripe_start: Return value of logical bytenr of where next stripe starts. |
| * Let the caller know to only fill the bio up to the stripe |
| * boundary. |
| */ |
| |
| |
| static struct bio *alloc_compressed_bio(struct compressed_bio *cb, u64 disk_bytenr, |
| blk_opf_t opf, |
| btrfs_bio_end_io_t endio_func, |
| u64 *next_stripe_start) |
| { |
| struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb); |
| struct btrfs_io_geometry geom; |
| struct extent_map *em; |
| struct bio *bio; |
| int ret; |
| |
| bio = btrfs_bio_alloc(BIO_MAX_VECS, opf, endio_func, cb); |
| bio->bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT; |
| |
| em = btrfs_get_chunk_map(fs_info, disk_bytenr, fs_info->sectorsize); |
| if (IS_ERR(em)) { |
| bio_put(bio); |
| return ERR_CAST(em); |
| } |
| |
| if (bio_op(bio) == REQ_OP_ZONE_APPEND) |
| bio_set_dev(bio, em->map_lookup->stripes[0].dev->bdev); |
| |
| ret = btrfs_get_io_geometry(fs_info, em, btrfs_op(bio), disk_bytenr, &geom); |
| free_extent_map(em); |
| if (ret < 0) { |
| bio_put(bio); |
| return ERR_PTR(ret); |
| } |
| *next_stripe_start = disk_bytenr + geom.len; |
| refcount_inc(&cb->pending_ios); |
| return 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. |
| */ |
| blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start, |
| unsigned int len, u64 disk_start, |
| unsigned int compressed_len, |
| struct page **compressed_pages, |
| unsigned int nr_pages, |
| blk_opf_t write_flags, |
| struct cgroup_subsys_state *blkcg_css, |
| bool writeback) |
| { |
| struct btrfs_fs_info *fs_info = inode->root->fs_info; |
| struct bio *bio = NULL; |
| struct compressed_bio *cb; |
| u64 cur_disk_bytenr = disk_start; |
| u64 next_stripe_start; |
| blk_status_t ret = BLK_STS_OK; |
| int skip_sum = inode->flags & BTRFS_INODE_NODATASUM; |
| const bool use_append = btrfs_use_zone_append(inode, disk_start); |
| const enum req_op bio_op = use_append ? REQ_OP_ZONE_APPEND : REQ_OP_WRITE; |
| |
| ASSERT(IS_ALIGNED(start, fs_info->sectorsize) && |
| IS_ALIGNED(len, fs_info->sectorsize)); |
| cb = kmalloc(sizeof(struct compressed_bio), GFP_NOFS); |
| if (!cb) |
| return BLK_STS_RESOURCE; |
| refcount_set(&cb->pending_ios, 1); |
| cb->status = BLK_STS_OK; |
| cb->inode = &inode->vfs_inode; |
| cb->start = start; |
| cb->len = len; |
| cb->compressed_pages = compressed_pages; |
| cb->compressed_len = compressed_len; |
| cb->writeback = writeback; |
| INIT_WORK(&cb->write_end_work, btrfs_finish_compressed_write_work); |
| cb->nr_pages = nr_pages; |
| |
| if (blkcg_css) |
| kthread_associate_blkcg(blkcg_css); |
| |
| while (cur_disk_bytenr < disk_start + compressed_len) { |
| u64 offset = cur_disk_bytenr - disk_start; |
| unsigned int index = offset >> PAGE_SHIFT; |
| unsigned int real_size; |
| unsigned int added; |
| struct page *page = compressed_pages[index]; |
| bool submit = false; |
| |
| /* Allocate new bio if submitted or not yet allocated */ |
| if (!bio) { |
| bio = alloc_compressed_bio(cb, cur_disk_bytenr, |
| bio_op | write_flags, end_compressed_bio_write, |
| &next_stripe_start); |
| if (IS_ERR(bio)) { |
| ret = errno_to_blk_status(PTR_ERR(bio)); |
| break; |
| } |
| if (blkcg_css) |
| bio->bi_opf |= REQ_CGROUP_PUNT; |
| } |
| /* |
| * We should never reach next_stripe_start start as we will |
| * submit comp_bio when reach the boundary immediately. |
| */ |
| ASSERT(cur_disk_bytenr != next_stripe_start); |
| |
| /* |
| * We have various limits on the real read size: |
| * - stripe boundary |
| * - page boundary |
| * - compressed length boundary |
| */ |
| real_size = min_t(u64, U32_MAX, next_stripe_start - cur_disk_bytenr); |
| real_size = min_t(u64, real_size, PAGE_SIZE - offset_in_page(offset)); |
| real_size = min_t(u64, real_size, compressed_len - offset); |
| ASSERT(IS_ALIGNED(real_size, fs_info->sectorsize)); |
| |
| if (use_append) |
| added = bio_add_zone_append_page(bio, page, real_size, |
| offset_in_page(offset)); |
| else |
| added = bio_add_page(bio, page, real_size, |
| offset_in_page(offset)); |
| /* Reached zoned boundary */ |
| if (added == 0) |
| submit = true; |
| |
| cur_disk_bytenr += added; |
| /* Reached stripe boundary */ |
| if (cur_disk_bytenr == next_stripe_start) |
| submit = true; |
| |
| /* Finished the range */ |
| if (cur_disk_bytenr == disk_start + compressed_len) |
| submit = true; |
| |
| if (submit) { |
| if (!skip_sum) { |
| ret = btrfs_csum_one_bio(inode, bio, start, true); |
| if (ret) { |
| btrfs_bio_end_io(btrfs_bio(bio), ret); |
| break; |
| } |
| } |
| |
| ASSERT(bio->bi_iter.bi_size); |
| btrfs_submit_bio(fs_info, bio, 0); |
| bio = NULL; |
| } |
| cond_resched(); |
| } |
| |
| if (blkcg_css) |
| kthread_associate_blkcg(NULL); |
| |
| if (refcount_dec_and_test(&cb->pending_ios)) |
| finish_compressed_bio_write(cb); |
| return ret; |
| } |
| |
| static u64 bio_end_offset(struct bio *bio) |
| { |
| struct bio_vec *last = bio_last_bvec_all(bio); |
| |
| return page_offset(last->bv_page) + last->bv_len + last->bv_offset; |
| } |
| |
| /* |
| * Add extra pages in the same compressed file extent so that we don't need to |
| * re-read the same extent again and again. |
| * |
| * NOTE: this won't work well for subpage, as for subpage read, we lock the |
| * full page then submit bio for each compressed/regular extents. |
| * |
| * This means, if we have several sectors in the same page points to the same |
| * on-disk compressed data, we will re-read the same extent many times and |
| * this function can only help for the next page. |
| */ |
| static noinline int add_ra_bio_pages(struct inode *inode, |
| u64 compressed_end, |
| struct compressed_bio *cb, |
| int *memstall, unsigned long *pflags) |
| { |
| struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); |
| unsigned long end_index; |
| u64 cur = bio_end_offset(cb->orig_bio); |
| u64 isize = i_size_read(inode); |
| int ret; |
| struct page *page; |
| struct extent_map *em; |
| struct address_space *mapping = inode->i_mapping; |
| struct extent_map_tree *em_tree; |
| struct extent_io_tree *tree; |
| int sectors_missed = 0; |
| |
| em_tree = &BTRFS_I(inode)->extent_tree; |
| tree = &BTRFS_I(inode)->io_tree; |
| |
| if (isize == 0) |
| return 0; |
| |
| /* |
| * For current subpage support, we only support 64K page size, |
| * which means maximum compressed extent size (128K) is just 2x page |
| * size. |
| * This makes readahead less effective, so here disable readahead for |
| * subpage for now, until full compressed write is supported. |
| */ |
| if (btrfs_sb(inode->i_sb)->sectorsize < PAGE_SIZE) |
| return 0; |
| |
| end_index = (i_size_read(inode) - 1) >> PAGE_SHIFT; |
| |
| while (cur < compressed_end) { |
| u64 page_end; |
| u64 pg_index = cur >> PAGE_SHIFT; |
| u32 add_size; |
| |
| if (pg_index > end_index) |
| break; |
| |
| page = xa_load(&mapping->i_pages, pg_index); |
| if (page && !xa_is_value(page)) { |
| sectors_missed += (PAGE_SIZE - offset_in_page(cur)) >> |
| fs_info->sectorsize_bits; |
| |
| /* Beyond threshold, no need to continue */ |
| if (sectors_missed > 4) |
| break; |
| |
| /* |
| * Jump to next page start as we already have page for |
| * current offset. |
| */ |
| cur = (pg_index << PAGE_SHIFT) + PAGE_SIZE; |
| continue; |
| } |
| |
| page = __page_cache_alloc(mapping_gfp_constraint(mapping, |
| ~__GFP_FS)); |
| if (!page) |
| break; |
| |
| if (add_to_page_cache_lru(page, mapping, pg_index, GFP_NOFS)) { |
| put_page(page); |
| /* There is already a page, skip to page end */ |
| cur = (pg_index << PAGE_SHIFT) + PAGE_SIZE; |
| continue; |
| } |
| |
| if (!*memstall && PageWorkingset(page)) { |
| psi_memstall_enter(pflags); |
| *memstall = 1; |
| } |
| |
| ret = set_page_extent_mapped(page); |
| if (ret < 0) { |
| unlock_page(page); |
| put_page(page); |
| break; |
| } |
| |
| page_end = (pg_index << PAGE_SHIFT) + PAGE_SIZE - 1; |
| lock_extent(tree, cur, page_end, NULL); |
| read_lock(&em_tree->lock); |
| em = lookup_extent_mapping(em_tree, cur, page_end + 1 - cur); |
| read_unlock(&em_tree->lock); |
| |
| /* |
| * 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. |
| */ |
| if (!em || cur < em->start || |
| (cur + fs_info->sectorsize > extent_map_end(em)) || |
| (em->block_start >> 9) != cb->orig_bio->bi_iter.bi_sector) { |
| free_extent_map(em); |
| unlock_extent(tree, cur, page_end, NULL); |
| unlock_page(page); |
| put_page(page); |
| break; |
| } |
| free_extent_map(em); |
| |
| if (page->index == end_index) { |
| size_t zero_offset = offset_in_page(isize); |
| |
| if (zero_offset) { |
| int zeros; |
| zeros = PAGE_SIZE - zero_offset; |
| memzero_page(page, zero_offset, zeros); |
| } |
| } |
| |
| add_size = min(em->start + em->len, page_end + 1) - cur; |
| ret = bio_add_page(cb->orig_bio, page, add_size, offset_in_page(cur)); |
| if (ret != add_size) { |
| unlock_extent(tree, cur, page_end, NULL); |
| unlock_page(page); |
| put_page(page); |
| break; |
| } |
| /* |
| * If it's subpage, we also need to increase its |
| * subpage::readers number, as at endio we will decrease |
| * subpage::readers and to unlock the page. |
| */ |
| if (fs_info->sectorsize < PAGE_SIZE) |
| btrfs_subpage_start_reader(fs_info, page, cur, add_size); |
| put_page(page); |
| cur += add_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 |
| * |
| * After the compressed pages are read, we copy the bytes into the |
| * bio we were passed and then call the bio end_io calls |
| */ |
| void btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, |
| int mirror_num) |
| { |
| struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); |
| struct extent_map_tree *em_tree; |
| struct compressed_bio *cb; |
| unsigned int compressed_len; |
| struct bio *comp_bio = NULL; |
| const u64 disk_bytenr = bio->bi_iter.bi_sector << SECTOR_SHIFT; |
| u64 cur_disk_byte = disk_bytenr; |
| u64 next_stripe_start; |
| u64 file_offset; |
| u64 em_len; |
| u64 em_start; |
| struct extent_map *em; |
| unsigned long pflags; |
| int memstall = 0; |
| blk_status_t ret; |
| int ret2; |
| int i; |
| |
| em_tree = &BTRFS_I(inode)->extent_tree; |
| |
| file_offset = bio_first_bvec_all(bio)->bv_offset + |
| page_offset(bio_first_page_all(bio)); |
| |
| /* we need the actual starting offset of this extent in the file */ |
| read_lock(&em_tree->lock); |
| em = lookup_extent_mapping(em_tree, file_offset, fs_info->sectorsize); |
| read_unlock(&em_tree->lock); |
| if (!em) { |
| ret = BLK_STS_IOERR; |
| goto out; |
| } |
| |
| ASSERT(em->compress_type != BTRFS_COMPRESS_NONE); |
| compressed_len = em->block_len; |
| cb = kmalloc(sizeof(struct compressed_bio), GFP_NOFS); |
| if (!cb) { |
| ret = BLK_STS_RESOURCE; |
| goto out; |
| } |
| |
| refcount_set(&cb->pending_ios, 1); |
| cb->status = BLK_STS_OK; |
| cb->inode = inode; |
| |
| cb->start = em->orig_start; |
| em_len = em->len; |
| em_start = em->start; |
| |
| cb->len = bio->bi_iter.bi_size; |
| cb->compressed_len = compressed_len; |
| cb->compress_type = em->compress_type; |
| cb->orig_bio = bio; |
| |
| free_extent_map(em); |
| em = NULL; |
| |
| cb->nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE); |
| cb->compressed_pages = kcalloc(cb->nr_pages, sizeof(struct page *), GFP_NOFS); |
| if (!cb->compressed_pages) { |
| ret = BLK_STS_RESOURCE; |
| goto fail; |
| } |
| |
| ret2 = btrfs_alloc_page_array(cb->nr_pages, cb->compressed_pages); |
| if (ret2) { |
| ret = BLK_STS_RESOURCE; |
| goto fail; |
| } |
| |
| add_ra_bio_pages(inode, em_start + em_len, cb, &memstall, &pflags); |
| |
| /* include any pages we added in add_ra-bio_pages */ |
| cb->len = bio->bi_iter.bi_size; |
| |
| while (cur_disk_byte < disk_bytenr + compressed_len) { |
| u64 offset = cur_disk_byte - disk_bytenr; |
| unsigned int index = offset >> PAGE_SHIFT; |
| unsigned int real_size; |
| unsigned int added; |
| struct page *page = cb->compressed_pages[index]; |
| bool submit = false; |
| |
| /* Allocate new bio if submitted or not yet allocated */ |
| if (!comp_bio) { |
| comp_bio = alloc_compressed_bio(cb, cur_disk_byte, |
| REQ_OP_READ, end_compressed_bio_read, |
| &next_stripe_start); |
| if (IS_ERR(comp_bio)) { |
| cb->status = errno_to_blk_status(PTR_ERR(comp_bio)); |
| break; |
| } |
| } |
| /* |
| * We should never reach next_stripe_start start as we will |
| * submit comp_bio when reach the boundary immediately. |
| */ |
| ASSERT(cur_disk_byte != next_stripe_start); |
| /* |
| * We have various limit on the real read size: |
| * - stripe boundary |
| * - page boundary |
| * - compressed length boundary |
| */ |
| real_size = min_t(u64, U32_MAX, next_stripe_start - cur_disk_byte); |
| real_size = min_t(u64, real_size, PAGE_SIZE - offset_in_page(offset)); |
| real_size = min_t(u64, real_size, compressed_len - offset); |
| ASSERT(IS_ALIGNED(real_size, fs_info->sectorsize)); |
| |
| added = bio_add_page(comp_bio, page, real_size, offset_in_page(offset)); |
| /* |
| * Maximum compressed extent is smaller than bio size limit, |
| * thus bio_add_page() should always success. |
| */ |
| ASSERT(added == real_size); |
| cur_disk_byte += added; |
| |
| /* Reached stripe boundary, need to submit */ |
| if (cur_disk_byte == next_stripe_start) |
| submit = true; |
| |
| /* Has finished the range, need to submit */ |
| if (cur_disk_byte == disk_bytenr + compressed_len) |
| submit = true; |
| |
| if (submit) { |
| /* Save the original iter for read repair */ |
| if (bio_op(comp_bio) == REQ_OP_READ) |
| btrfs_bio(comp_bio)->iter = comp_bio->bi_iter; |
| |
| /* |
| * Save the initial offset of this chunk, as there |
| * is no direct correlation between compressed pages and |
| * the original file offset. The field is only used for |
| * priting error messages. |
| */ |
| btrfs_bio(comp_bio)->file_offset = file_offset; |
| |
| ret = btrfs_lookup_bio_sums(inode, comp_bio, NULL); |
| if (ret) { |
| btrfs_bio_end_io(btrfs_bio(comp_bio), ret); |
| break; |
| } |
| |
| ASSERT(comp_bio->bi_iter.bi_size); |
| btrfs_submit_bio(fs_info, comp_bio, mirror_num); |
| comp_bio = NULL; |
| } |
| } |
| |
| if (memstall) |
| psi_memstall_leave(&pflags); |
| |
| if (refcount_dec_and_test(&cb->pending_ios)) |
| finish_compressed_bio_read(cb); |
| return; |
| |
| fail: |
| if (cb->compressed_pages) { |
| for (i = 0; i < cb->nr_pages; i++) { |
| if (cb->compressed_pages[i]) |
| __free_page(cb->compressed_pages[i]); |
| } |
| } |
| |
| kfree(cb->compressed_pages); |
| kfree(cb); |
| out: |
| free_extent_map(em); |
| btrfs_bio_end_io(btrfs_bio(bio), ret); |
| return; |
| } |
| |
| /* |
| * Heuristic uses systematic sampling to collect data from the input data |
| * range, the logic can be tuned by the following constants: |
| * |
| * @SAMPLING_READ_SIZE - how many bytes will be copied from for each sample |
| * @SAMPLING_INTERVAL - range from which the sampled data can be collected |
| */ |
| #define SAMPLING_READ_SIZE (16) |
| #define SAMPLING_INTERVAL (256) |
| |
| /* |
| * For statistical analysis of the input data we consider bytes that form a |
| * Galois Field of 256 objects. Each object has an attribute count, ie. how |
| * many times the object appeared in the sample. |
| */ |
| #define BUCKET_SIZE (256) |
| |
| /* |
| * The size of the sample is based on a statistical sampling rule of thumb. |
| * The common way is to perform sampling tests as long as the number of |
| * elements in each cell is at least 5. |
| * |
| * Instead of 5, we choose 32 to obtain more accurate results. |
| * If the data contain the maximum number of symbols, which is 256, we obtain a |
| * sample size bound by 8192. |
| * |
| * For a sample of at most 8KB of data per data range: 16 consecutive bytes |
| * from up to 512 locations. |
| */ |
| #define MAX_SAMPLE_SIZE (BTRFS_MAX_UNCOMPRESSED * \ |
| SAMPLING_READ_SIZE / SAMPLING_INTERVAL) |
| |
| struct bucket_item { |
| u32 count; |
| }; |
| |
| struct heuristic_ws { |
| /* Partial copy of input data */ |
| u8 *sample; |
| u32 sample_size; |
| /* Buckets store counters for each byte value */ |
| struct bucket_item *bucket; |
| /* Sorting buffer */ |
| struct bucket_item *bucket_b; |
| struct list_head list; |
| }; |
| |
| static struct workspace_manager heuristic_wsm; |
| |
| static void free_heuristic_ws(struct list_head *ws) |
| { |
| struct heuristic_ws *workspace; |
| |
| workspace = list_entry(ws, struct heuristic_ws, list); |
| |
| kvfree(workspace->sample); |
| kfree(workspace->bucket); |
| kfree(workspace->bucket_b); |
| kfree(workspace); |
| } |
| |
| static struct list_head *alloc_heuristic_ws(unsigned int level) |
| { |
| struct heuristic_ws *ws; |
| |
| ws = kzalloc(sizeof(*ws), GFP_KERNEL); |
| if (!ws) |
| return ERR_PTR(-ENOMEM); |
| |
| ws->sample = kvmalloc(MAX_SAMPLE_SIZE, GFP_KERNEL); |
| if (!ws->sample) |
| goto fail; |
| |
| ws->bucket = kcalloc(BUCKET_SIZE, sizeof(*ws->bucket), GFP_KERNEL); |
| if (!ws->bucket) |
| goto fail; |
| |
| ws->bucket_b = kcalloc(BUCKET_SIZE, sizeof(*ws->bucket_b), GFP_KERNEL); |
| if (!ws->bucket_b) |
| goto fail; |
| |
| INIT_LIST_HEAD(&ws->list); |
| return &ws->list; |
| fail: |
| free_heuristic_ws(&ws->list); |
| return ERR_PTR(-ENOMEM); |
| } |
| |
| const struct btrfs_compress_op btrfs_heuristic_compress = { |
| .workspace_manager = &heuristic_wsm, |
| }; |
| |
| static const struct btrfs_compress_op * const btrfs_compress_op[] = { |
| /* The heuristic is represented as compression type 0 */ |
| &btrfs_heuristic_compress, |
| &btrfs_zlib_compress, |
| &btrfs_lzo_compress, |
| &btrfs_zstd_compress, |
| }; |
| |
| static struct list_head *alloc_workspace(int type, unsigned int level) |
| { |
| switch (type) { |
| case BTRFS_COMPRESS_NONE: return alloc_heuristic_ws(level); |
| case BTRFS_COMPRESS_ZLIB: return zlib_alloc_workspace(level); |
| case BTRFS_COMPRESS_LZO: return lzo_alloc_workspace(level); |
| case BTRFS_COMPRESS_ZSTD: return zstd_alloc_workspace(level); |
| default: |
| /* |
| * This can't happen, the type is validated several times |
| * before we get here. |
| */ |
| BUG(); |
| } |
| } |
| |
| static void free_workspace(int type, struct list_head *ws) |
| { |
| switch (type) { |
| case BTRFS_COMPRESS_NONE: return free_heuristic_ws(ws); |
| case BTRFS_COMPRESS_ZLIB: return zlib_free_workspace(ws); |
| case BTRFS_COMPRESS_LZO: return lzo_free_workspace(ws); |
| case BTRFS_COMPRESS_ZSTD: return zstd_free_workspace(ws); |
| default: |
| /* |
| * This can't happen, the type is validated several times |
| * before we get here. |
| */ |
| BUG(); |
| } |
| } |
| |
| static void btrfs_init_workspace_manager(int type) |
| { |
| struct workspace_manager *wsm; |
| struct list_head *workspace; |
| |
| wsm = btrfs_compress_op[type]->workspace_manager; |
| INIT_LIST_HEAD(&wsm->idle_ws); |
| spin_lock_init(&wsm->ws_lock); |
| atomic_set(&wsm->total_ws, 0); |
| init_waitqueue_head(&wsm->ws_wait); |
| |
| /* |
| * Preallocate one workspace for each compression type so we can |
| * guarantee forward progress in the worst case |
| */ |
| workspace = alloc_workspace(type, 0); |
| if (IS_ERR(workspace)) { |
| pr_warn( |
| "BTRFS: cannot preallocate compression workspace, will try later\n"); |
| } else { |
| atomic_set(&wsm->total_ws, 1); |
| wsm->free_ws = 1; |
| list_add(workspace, &wsm->idle_ws); |
| } |
| } |
| |
| static void btrfs_cleanup_workspace_manager(int type) |
| { |
| struct workspace_manager *wsman; |
| struct list_head *ws; |
| |
| wsman = btrfs_compress_op[type]->workspace_manager; |
| while (!list_empty(&wsman->idle_ws)) { |
| ws = wsman->idle_ws.next; |
| list_del(ws); |
| free_workspace(type, ws); |
| atomic_dec(&wsman->total_ws); |
| } |
| } |
| |
| /* |
| * This finds an available workspace or allocates a new one. |
| * If it's not possible to allocate a new one, waits until there's one. |
| * Preallocation makes a forward progress guarantees and we do not return |
| * errors. |
| */ |
| struct list_head *btrfs_get_workspace(int type, unsigned int level) |
| { |
| struct workspace_manager *wsm; |
| struct list_head *workspace; |
| int cpus = num_online_cpus(); |
| unsigned nofs_flag; |
| struct list_head *idle_ws; |
| spinlock_t *ws_lock; |
| atomic_t *total_ws; |
| wait_queue_head_t *ws_wait; |
| int *free_ws; |
| |
| wsm = btrfs_compress_op[type]->workspace_manager; |
| idle_ws = &wsm->idle_ws; |
| ws_lock = &wsm->ws_lock; |
| total_ws = &wsm->total_ws; |
| ws_wait = &wsm->ws_wait; |
| free_ws = &wsm->free_ws; |
| |
| again: |
| spin_lock(ws_lock); |
| if (!list_empty(idle_ws)) { |
| workspace = idle_ws->next; |
| list_del(workspace); |
| (*free_ws)--; |
| spin_unlock(ws_lock); |
| return workspace; |
| |
| } |
| if (atomic_read(total_ws) > cpus) { |
| DEFINE_WAIT(wait); |
| |
| spin_unlock(ws_lock); |
| prepare_to_wait(ws_wait, &wait, TASK_UNINTERRUPTIBLE); |
| if (atomic_read(total_ws) > cpus && !*free_ws) |
| schedule(); |
| finish_wait(ws_wait, &wait); |
| goto again; |
| } |
| atomic_inc(total_ws); |
| spin_unlock(ws_lock); |
| |
| /* |
| * Allocation helpers call vmalloc that can't use GFP_NOFS, so we have |
| * to turn it off here because we might get called from the restricted |
| * context of btrfs_compress_bio/btrfs_compress_pages |
| */ |
| nofs_flag = memalloc_nofs_save(); |
| workspace = alloc_workspace(type, level); |
| memalloc_nofs_restore(nofs_flag); |
| |
| if (IS_ERR(workspace)) { |
| atomic_dec(total_ws); |
| wake_up(ws_wait); |
| |
| /* |
| * Do not return the error but go back to waiting. There's a |
| * workspace preallocated for each type and the compression |
| * time is bounded so we get to a workspace eventually. This |
| * makes our caller's life easier. |
| * |
| * To prevent silent and low-probability deadlocks (when the |
| * initial preallocation fails), check if there are any |
| * workspaces at all. |
| */ |
| if (atomic_read(total_ws) == 0) { |
| static DEFINE_RATELIMIT_STATE(_rs, |
| /* once per minute */ 60 * HZ, |
| /* no burst */ 1); |
| |
| if (__ratelimit(&_rs)) { |
| pr_warn("BTRFS: no compression workspaces, low memory, retrying\n"); |
| } |
| } |
| goto again; |
| } |
| return workspace; |
| } |
| |
| static struct list_head *get_workspace(int type, int level) |
| { |
| switch (type) { |
| case BTRFS_COMPRESS_NONE: return btrfs_get_workspace(type, level); |
| case BTRFS_COMPRESS_ZLIB: return zlib_get_workspace(level); |
| case BTRFS_COMPRESS_LZO: return btrfs_get_workspace(type, level); |
| case BTRFS_COMPRESS_ZSTD: return zstd_get_workspace(level); |
| default: |
| /* |
| * This can't happen, the type is validated several times |
| * before we get here. |
| */ |
| BUG(); |
| } |
| } |
| |
| /* |
| * put a workspace struct back on the list or free it if we have enough |
| * idle ones sitting around |
| */ |
| void btrfs_put_workspace(int type, struct list_head *ws) |
| { |
| struct workspace_manager *wsm; |
| struct list_head *idle_ws; |
| spinlock_t *ws_lock; |
| atomic_t *total_ws; |
| wait_queue_head_t *ws_wait; |
| int *free_ws; |
| |
| wsm = btrfs_compress_op[type]->workspace_manager; |
| idle_ws = &wsm->idle_ws; |
| ws_lock = &wsm->ws_lock; |
| total_ws = &wsm->total_ws; |
| ws_wait = &wsm->ws_wait; |
| free_ws = &wsm->free_ws; |
| |
| spin_lock(ws_lock); |
| if (*free_ws <= num_online_cpus()) { |
| list_add(ws, idle_ws); |
| (*free_ws)++; |
| spin_unlock(ws_lock); |
| goto wake; |
| } |
| spin_unlock(ws_lock); |
| |
| free_workspace(type, ws); |
| atomic_dec(total_ws); |
| wake: |
| cond_wake_up(ws_wait); |
| } |
| |
| static void put_workspace(int type, struct list_head *ws) |
| { |
| switch (type) { |
| case BTRFS_COMPRESS_NONE: return btrfs_put_workspace(type, ws); |
| case BTRFS_COMPRESS_ZLIB: return btrfs_put_workspace(type, ws); |
| case BTRFS_COMPRESS_LZO: return btrfs_put_workspace(type, ws); |
| case BTRFS_COMPRESS_ZSTD: return zstd_put_workspace(ws); |
| default: |
| /* |
| * This can't happen, the type is validated several times |
| * before we get here. |
| */ |
| BUG(); |
| } |
| } |
| |
| /* |
| * Adjust @level according to the limits of the compression algorithm or |
| * fallback to default |
| */ |
| static unsigned int btrfs_compress_set_level(int type, unsigned level) |
| { |
| const struct btrfs_compress_op *ops = btrfs_compress_op[type]; |
| |
| if (level == 0) |
| level = ops->default_level; |
| else |
| level = min(level, ops->max_level); |
| |
| return level; |
| } |
| |
| /* |
| * Given an address space and start and length, compress the bytes into @pages |
| * that are allocated on demand. |
| * |
| * @type_level is encoded algorithm and level, where level 0 means whatever |
| * default the algorithm chooses and is opaque here; |
| * - compression algo are 0-3 |
| * - the level are bits 4-7 |
| * |
| * @out_pages is an in/out parameter, holds maximum number of pages to allocate |
| * and returns number of actually allocated pages |
| * |
| * @total_in is used to return the number of bytes actually read. It |
| * may be smaller than the input length 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 an in/out parameter, must be set to the input length and will |
| * be also used to return the total number of compressed bytes |
| */ |
| int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping, |
| u64 start, struct page **pages, |
| unsigned long *out_pages, |
| unsigned long *total_in, |
| unsigned long *total_out) |
| { |
| int type = btrfs_compress_type(type_level); |
| int level = btrfs_compress_level(type_level); |
| struct list_head *workspace; |
| int ret; |
| |
| level = btrfs_compress_set_level(type, level); |
| workspace = get_workspace(type, level); |
| ret = compression_compress_pages(type, workspace, mapping, start, pages, |
| out_pages, total_in, total_out); |
| put_workspace(type, workspace); |
| return ret; |
| } |
| |
| static int btrfs_decompress_bio(struct compressed_bio *cb) |
| { |
| struct list_head *workspace; |
| int ret; |
| int type = cb->compress_type; |
| |
| workspace = get_workspace(type, 0); |
| ret = compression_decompress_bio(workspace, cb); |
| put_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 = get_workspace(type, 0); |
| ret = compression_decompress(type, workspace, data_in, dest_page, |
| start_byte, srclen, destlen); |
| put_workspace(type, workspace); |
| |
| return ret; |
| } |
| |
| void __init btrfs_init_compress(void) |
| { |
| btrfs_init_workspace_manager(BTRFS_COMPRESS_NONE); |
| btrfs_init_workspace_manager(BTRFS_COMPRESS_ZLIB); |
| btrfs_init_workspace_manager(BTRFS_COMPRESS_LZO); |
| zstd_init_workspace_manager(); |
| } |
| |
| void __cold btrfs_exit_compress(void) |
| { |
| btrfs_cleanup_workspace_manager(BTRFS_COMPRESS_NONE); |
| btrfs_cleanup_workspace_manager(BTRFS_COMPRESS_ZLIB); |
| btrfs_cleanup_workspace_manager(BTRFS_COMPRESS_LZO); |
| zstd_cleanup_workspace_manager(); |
| } |
| |
| /* |
| * Copy decompressed data from working buffer to pages. |
| * |
| * @buf: The decompressed data buffer |
| * @buf_len: The decompressed data length |
| * @decompressed: Number of bytes that are already decompressed inside the |
| * compressed extent |
| * @cb: The compressed extent descriptor |
| * @orig_bio: The original bio that the caller wants to read for |
| * |
| * An easier to understand graph is like below: |
| * |
| * |<- orig_bio ->| |<- orig_bio->| |
| * |<------- full decompressed extent ----->| |
| * |<----------- @cb range ---->| |
| * | |<-- @buf_len -->| |
| * |<--- @decompressed --->| |
| * |
| * Note that, @cb can be a subpage of the full decompressed extent, but |
| * @cb->start always has the same as the orig_file_offset value of the full |
| * decompressed extent. |
| * |
| * When reading compressed extent, we have to read the full compressed extent, |
| * while @orig_bio may only want part of the range. |
| * Thus this function will ensure only data covered by @orig_bio will be copied |
| * to. |
| * |
| * Return 0 if we have copied all needed contents for @orig_bio. |
| * Return >0 if we need continue decompress. |
| */ |
| int btrfs_decompress_buf2page(const char *buf, u32 buf_len, |
| struct compressed_bio *cb, u32 decompressed) |
| { |
| struct bio *orig_bio = cb->orig_bio; |
| /* Offset inside the full decompressed extent */ |
| u32 cur_offset; |
| |
| cur_offset = decompressed; |
| /* The main loop to do the copy */ |
| while (cur_offset < decompressed + buf_len) { |
| struct bio_vec bvec; |
| size_t copy_len; |
| u32 copy_start; |
| /* Offset inside the full decompressed extent */ |
| u32 bvec_offset; |
| |
| bvec = bio_iter_iovec(orig_bio, orig_bio->bi_iter); |
| /* |
| * cb->start may underflow, but subtracting that value can still |
| * give us correct offset inside the full decompressed extent. |
| */ |
| bvec_offset = page_offset(bvec.bv_page) + bvec.bv_offset - cb->start; |
| |
| /* Haven't reached the bvec range, exit */ |
| if (decompressed + buf_len <= bvec_offset) |
| return 1; |
| |
| copy_start = max(cur_offset, bvec_offset); |
| copy_len = min(bvec_offset + bvec.bv_len, |
| decompressed + buf_len) - copy_start; |
| ASSERT(copy_len); |
| |
| /* |
| * Extra range check to ensure we didn't go beyond |
| * @buf + @buf_len. |
| */ |
| ASSERT(copy_start - decompressed < buf_len); |
| memcpy_to_page(bvec.bv_page, bvec.bv_offset, |
| buf + copy_start - decompressed, copy_len); |
| cur_offset += copy_len; |
| |
| bio_advance(orig_bio, copy_len); |
| /* Finished the bio */ |
| if (!orig_bio->bi_iter.bi_size) |
| return 0; |
| } |
| return 1; |
| } |
| |
| /* |
| * Shannon Entropy calculation |
| * |
| * Pure byte distribution analysis fails to determine compressibility of data. |
| * Try calculating entropy to estimate the average minimum number of bits |
| * needed to encode the sampled data. |
| * |
| * For convenience, return the percentage of needed bits, instead of amount of |
| * bits directly. |
| * |
| * @ENTROPY_LVL_ACEPTABLE - below that threshold, sample has low byte entropy |
| * and can be compressible with high probability |
| * |
| * @ENTROPY_LVL_HIGH - data are not compressible with high probability |
| * |
| * Use of ilog2() decreases precision, we lower the LVL to 5 to compensate. |
| */ |
| #define ENTROPY_LVL_ACEPTABLE (65) |
| #define ENTROPY_LVL_HIGH (80) |
| |
| /* |
| * For increasead precision in shannon_entropy calculation, |
| * let's do pow(n, M) to save more digits after comma: |
| * |
| * - maximum int bit length is 64 |
| * - ilog2(MAX_SAMPLE_SIZE) -> 13 |
| * - 13 * 4 = 52 < 64 -> M = 4 |
| * |
| * So use pow(n, 4). |
| */ |
| static inline u32 ilog2_w(u64 n) |
| { |
| return ilog2(n * n * n * n); |
| } |
| |
| static u32 shannon_entropy(struct heuristic_ws *ws) |
| { |
| const u32 entropy_max = 8 * ilog2_w(2); |
| u32 entropy_sum = 0; |
| u32 p, p_base, sz_base; |
| u32 i; |
| |
| sz_base = ilog2_w(ws->sample_size); |
| for (i = 0; i < BUCKET_SIZE && ws->bucket[i].count > 0; i++) { |
| p = ws->bucket[i].count; |
| p_base = ilog2_w(p); |
| entropy_sum += p * (sz_base - p_base); |
| } |
| |
| entropy_sum /= ws->sample_size; |
| return entropy_sum * 100 / entropy_max; |
| } |
| |
| #define RADIX_BASE 4U |
| #define COUNTERS_SIZE (1U << RADIX_BASE) |
| |
| static u8 get4bits(u64 num, int shift) { |
| u8 low4bits; |
| |
| num >>= shift; |
| /* Reverse order */ |
| low4bits = (COUNTERS_SIZE - 1) - (num % COUNTERS_SIZE); |
| return low4bits; |
| } |
| |
| /* |
| * Use 4 bits as radix base |
| * Use 16 u32 counters for calculating new position in buf array |
| * |
| * @array - array that will be sorted |
| * @array_buf - buffer array to store sorting results |
| * must be equal in size to @array |
| * @num - array size |
| */ |
| static void radix_sort(struct bucket_item *array, struct bucket_item *array_buf, |
| int num) |
| { |
| u64 max_num; |
| u64 buf_num; |
| u32 counters[COUNTERS_SIZE]; |
| u32 new_addr; |
| u32 addr; |
| int bitlen; |
| int shift; |
| int i; |
| |
| /* |
| * Try avoid useless loop iterations for small numbers stored in big |
| * counters. Example: 48 33 4 ... in 64bit array |
| */ |
| max_num = array[0].count; |
| for (i = 1; i < num; i++) { |
| buf_num = array[i].count; |
| if (buf_num > max_num) |
| max_num = buf_num; |
| } |
| |
| buf_num = ilog2(max_num); |
| bitlen = ALIGN(buf_num, RADIX_BASE * 2); |
| |
| shift = 0; |
| while (shift < bitlen) { |
| memset(counters, 0, sizeof(counters)); |
| |
| for (i = 0; i < num; i++) { |
| buf_num = array[i].count; |
| addr = get4bits(buf_num, shift); |
| counters[addr]++; |
| } |
| |
| for (i = 1; i < COUNTERS_SIZE; i++) |
| counters[i] += counters[i - 1]; |
| |
| for (i = num - 1; i >= 0; i--) { |
| buf_num = array[i].count; |
| addr = get4bits(buf_num, shift); |
| counters[addr]--; |
| new_addr = counters[addr]; |
| array_buf[new_addr] = array[i]; |
| } |
| |
| shift += RADIX_BASE; |
| |
| /* |
| * Normal radix expects to move data from a temporary array, to |
| * the main one. But that requires some CPU time. Avoid that |
| * by doing another sort iteration to original array instead of |
| * memcpy() |
| */ |
| memset(counters, 0, sizeof(counters)); |
| |
| for (i = 0; i < num; i ++) { |
| buf_num = array_buf[i].count; |
| addr = get4bits(buf_num, shift); |
| counters[addr]++; |
| } |
| |
| for (i = 1; i < COUNTERS_SIZE; i++) |
| counters[i] += counters[i - 1]; |
| |
| for (i = num - 1; i >= 0; i--) { |
| buf_num = array_buf[i].count; |
| addr = get4bits(buf_num, shift); |
| counters[addr]--; |
| new_addr = counters[addr]; |
| array[new_addr] = array_buf[i]; |
| } |
| |
| shift += RADIX_BASE; |
| } |
| } |
| |
| /* |
| * Size of the core byte set - how many bytes cover 90% of the sample |
| * |
| * There are several types of structured binary data that use nearly all byte |
| * values. The distribution can be uniform and counts in all buckets will be |
| * nearly the same (eg. encrypted data). Unlikely to be compressible. |
| * |
| * Other possibility is normal (Gaussian) distribution, where the data could |
| * be potentially compressible, but we have to take a few more steps to decide |
| * how much. |
| * |
| * @BYTE_CORE_SET_LOW - main part of byte values repeated frequently, |
| * compression algo can easy fix that |
| * @BYTE_CORE_SET_HIGH - data have uniform distribution and with high |
| * probability is not compressible |
| */ |
| #define BYTE_CORE_SET_LOW (64) |
| #define BYTE_CORE_SET_HIGH (200) |
| |
| static int byte_core_set_size(struct heuristic_ws *ws) |
| { |
| u32 i; |
| u32 coreset_sum = 0; |
| const u32 core_set_threshold = ws->sample_size * 90 / 100; |
| struct bucket_item *bucket = ws->bucket; |
| |
| /* Sort in reverse order */ |
| radix_sort(ws->bucket, ws->bucket_b, BUCKET_SIZE); |
| |
| for (i = 0; i < BYTE_CORE_SET_LOW; i++) |
| coreset_sum += bucket[i].count; |
| |
| if (coreset_sum > core_set_threshold) |
| return i; |
| |
| for (; i < BYTE_CORE_SET_HIGH && bucket[i].count > 0; i++) { |
| coreset_sum += bucket[i].count; |
| if (coreset_sum > core_set_threshold) |
| break; |
| } |
| |
| return i; |
| } |
| |
| /* |
| * Count byte values in buckets. |
| * This heuristic can detect textual data (configs, xml, json, html, etc). |
| * Because in most text-like data byte set is restricted to limited number of |
| * possible characters, and that restriction in most cases makes data easy to |
| * compress. |
| * |
| * @BYTE_SET_THRESHOLD - consider all data within this byte set size: |
| * less - compressible |
| * more - need additional analysis |
| */ |
| #define BYTE_SET_THRESHOLD (64) |
| |
| static u32 byte_set_size(const struct heuristic_ws *ws) |
| { |
| u32 i; |
| u32 byte_set_size = 0; |
| |
| for (i = 0; i < BYTE_SET_THRESHOLD; i++) { |
| if (ws->bucket[i].count > 0) |
| byte_set_size++; |
| } |
| |
| /* |
| * Continue collecting count of byte values in buckets. If the byte |
| * set size is bigger then the threshold, it's pointless to continue, |
| * the detection technique would fail for this type of data. |
| */ |
| for (; i < BUCKET_SIZE; i++) { |
| if (ws->bucket[i].count > 0) { |
| byte_set_size++; |
| if (byte_set_size > BYTE_SET_THRESHOLD) |
| return byte_set_size; |
| } |
| } |
| |
| return byte_set_size; |
| } |
| |
| static bool sample_repeated_patterns(struct heuristic_ws *ws) |
| { |
| const u32 half_of_sample = ws->sample_size / 2; |
| const u8 *data = ws->sample; |
| |
| return memcmp(&data[0], &data[half_of_sample], half_of_sample) == 0; |
| } |
| |
| static void heuristic_collect_sample(struct inode *inode, u64 start, u64 end, |
| struct heuristic_ws *ws) |
| { |
| struct page *page; |
| u64 index, index_end; |
| u32 i, curr_sample_pos; |
| u8 *in_data; |
| |
| /* |
| * Compression handles the input data by chunks of 128KiB |
| * (defined by BTRFS_MAX_UNCOMPRESSED) |
| * |
| * We do the same for the heuristic and loop over the whole range. |
| * |
| * MAX_SAMPLE_SIZE - calculated under assumption that heuristic will |
| * process no more than BTRFS_MAX_UNCOMPRESSED at a time. |
| */ |
| if (end - start > BTRFS_MAX_UNCOMPRESSED) |
| end = start + BTRFS_MAX_UNCOMPRESSED; |
| |
| index = start >> PAGE_SHIFT; |
| index_end = end >> PAGE_SHIFT; |
| |
| /* Don't miss unaligned end */ |
| if (!IS_ALIGNED(end, PAGE_SIZE)) |
| index_end++; |
| |
| curr_sample_pos = 0; |
| while (index < index_end) { |
| page = find_get_page(inode->i_mapping, index); |
| in_data = kmap_local_page(page); |
| /* Handle case where the start is not aligned to PAGE_SIZE */ |
| i = start % PAGE_SIZE; |
| while (i < PAGE_SIZE - SAMPLING_READ_SIZE) { |
| /* Don't sample any garbage from the last page */ |
| if (start > end - SAMPLING_READ_SIZE) |
| break; |
| memcpy(&ws->sample[curr_sample_pos], &in_data[i], |
| SAMPLING_READ_SIZE); |
| i += SAMPLING_INTERVAL; |
| start += SAMPLING_INTERVAL; |
| curr_sample_pos += SAMPLING_READ_SIZE; |
| } |
| kunmap_local(in_data); |
| put_page(page); |
| |
| index++; |
| } |
| |
| ws->sample_size = curr_sample_pos; |
| } |
| |
| /* |
| * Compression heuristic. |
| * |
| * For now is's a naive and optimistic 'return true', we'll extend the logic to |
| * quickly (compared to direct compression) detect data characteristics |
| * (compressible/uncompressible) to avoid wasting CPU time on uncompressible |
| * data. |
| * |
| * The following types of analysis can be performed: |
| * - detect mostly zero data |
| * - detect data with low "byte set" size (text, etc) |
| * - detect data with low/high "core byte" set |
| * |
| * Return non-zero if the compression should be done, 0 otherwise. |
| */ |
| int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end) |
| { |
| struct list_head *ws_list = get_workspace(0, 0); |
| struct heuristic_ws *ws; |
| u32 i; |
| u8 byte; |
| int ret = 0; |
| |
| ws = list_entry(ws_list, struct heuristic_ws, list); |
| |
| heuristic_collect_sample(inode, start, end, ws); |
| |
| if (sample_repeated_patterns(ws)) { |
| ret = 1; |
| goto out; |
| } |
| |
| memset(ws->bucket, 0, sizeof(*ws->bucket)*BUCKET_SIZE); |
| |
| for (i = 0; i < ws->sample_size; i++) { |
| byte = ws->sample[i]; |
| ws->bucket[byte].count++; |
| } |
| |
| i = byte_set_size(ws); |
| if (i < BYTE_SET_THRESHOLD) { |
| ret = 2; |
| goto out; |
| } |
| |
| i = byte_core_set_size(ws); |
| if (i <= BYTE_CORE_SET_LOW) { |
| ret = 3; |
| goto out; |
| } |
| |
| if (i >= BYTE_CORE_SET_HIGH) { |
| ret = 0; |
| goto out; |
| } |
| |
| i = shannon_entropy(ws); |
| if (i <= ENTROPY_LVL_ACEPTABLE) { |
| ret = 4; |
| goto out; |
| } |
| |
| /* |
| * For the levels below ENTROPY_LVL_HIGH, additional analysis would be |
| * needed to give green light to compression. |
| * |
| * For now just assume that compression at that level is not worth the |
| * resources because: |
| * |
| * 1. it is possible to defrag the data later |
| * |
| * 2. the data would turn out to be hardly compressible, eg. 150 byte |
| * values, every bucket has counter at level ~54. The heuristic would |
| * be confused. This can happen when data have some internal repeated |
| * patterns like "abbacbbc...". This can be detected by analyzing |
| * pairs of bytes, which is too costly. |
| */ |
| if (i < ENTROPY_LVL_HIGH) { |
| ret = 5; |
| goto out; |
| } else { |
| ret = 0; |
| goto out; |
| } |
| |
| out: |
| put_workspace(0, ws_list); |
| return ret; |
| } |
| |
| /* |
| * Convert the compression suffix (eg. after "zlib" starting with ":") to |
| * level, unrecognized string will set the default level |
| */ |
| unsigned int btrfs_compress_str2level(unsigned int type, const char *str) |
| { |
| unsigned int level = 0; |
| int ret; |
| |
| if (!type) |
| return 0; |
| |
| if (str[0] == ':') { |
| ret = kstrtouint(str + 1, 10, &level); |
| if (ret) |
| level = 0; |
| } |
| |
| level = btrfs_compress_set_level(type, level); |
| |
| return level; |
| } |