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1732 lines
44 KiB
1732 lines
44 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2008 Oracle. All rights reserved. |
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*/ |
|
|
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#include <linux/kernel.h> |
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#include <linux/bio.h> |
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#include <linux/file.h> |
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#include <linux/fs.h> |
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#include <linux/pagemap.h> |
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#include <linux/highmem.h> |
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#include <linux/time.h> |
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#include <linux/init.h> |
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#include <linux/string.h> |
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#include <linux/backing-dev.h> |
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#include <linux/writeback.h> |
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#include <linux/slab.h> |
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#include <linux/sched/mm.h> |
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#include <linux/log2.h> |
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#include <crypto/hash.h> |
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#include "misc.h" |
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#include "ctree.h" |
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#include "disk-io.h" |
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#include "transaction.h" |
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#include "btrfs_inode.h" |
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#include "volumes.h" |
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#include "ordered-data.h" |
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#include "compression.h" |
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#include "extent_io.h" |
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#include "extent_map.h" |
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|
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static const char* const btrfs_compress_types[] = { "", "zlib", "lzo", "zstd" }; |
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|
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const char* btrfs_compress_type2str(enum btrfs_compression_type type) |
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{ |
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switch (type) { |
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case BTRFS_COMPRESS_ZLIB: |
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case BTRFS_COMPRESS_LZO: |
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case BTRFS_COMPRESS_ZSTD: |
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case BTRFS_COMPRESS_NONE: |
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return btrfs_compress_types[type]; |
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default: |
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break; |
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} |
|
|
|
return NULL; |
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} |
|
|
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bool btrfs_compress_is_valid_type(const char *str, size_t len) |
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{ |
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int i; |
|
|
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for (i = 1; i < ARRAY_SIZE(btrfs_compress_types); i++) { |
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size_t comp_len = strlen(btrfs_compress_types[i]); |
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|
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if (len < comp_len) |
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continue; |
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|
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if (!strncmp(btrfs_compress_types[i], str, comp_len)) |
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return true; |
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} |
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return false; |
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} |
|
|
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static int compression_compress_pages(int type, struct list_head *ws, |
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struct address_space *mapping, u64 start, struct page **pages, |
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unsigned long *out_pages, unsigned long *total_in, |
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unsigned long *total_out) |
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{ |
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switch (type) { |
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case BTRFS_COMPRESS_ZLIB: |
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return zlib_compress_pages(ws, mapping, start, pages, |
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out_pages, total_in, total_out); |
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case BTRFS_COMPRESS_LZO: |
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return lzo_compress_pages(ws, mapping, start, pages, |
|
out_pages, total_in, total_out); |
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case BTRFS_COMPRESS_ZSTD: |
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return zstd_compress_pages(ws, mapping, start, pages, |
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out_pages, total_in, total_out); |
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case BTRFS_COMPRESS_NONE: |
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default: |
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/* |
|
* This can happen when compression races with remount setting |
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* it to 'no compress', while caller doesn't call |
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* inode_need_compress() to check if we really need to |
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* compress. |
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* |
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* Not a big deal, just need to inform caller that we |
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* haven't allocated any pages yet. |
|
*/ |
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*out_pages = 0; |
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return -E2BIG; |
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} |
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} |
|
|
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static int compression_decompress_bio(int type, struct list_head *ws, |
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struct compressed_bio *cb) |
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{ |
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switch (type) { |
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case BTRFS_COMPRESS_ZLIB: return zlib_decompress_bio(ws, cb); |
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case BTRFS_COMPRESS_LZO: return lzo_decompress_bio(ws, cb); |
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case BTRFS_COMPRESS_ZSTD: return zstd_decompress_bio(ws, cb); |
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case BTRFS_COMPRESS_NONE: |
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default: |
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/* |
|
* This can't happen, the type is validated several times |
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* before we get here. |
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*/ |
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BUG(); |
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} |
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} |
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|
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static int compression_decompress(int type, struct list_head *ws, |
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unsigned char *data_in, struct page *dest_page, |
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unsigned long start_byte, size_t srclen, size_t destlen) |
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{ |
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switch (type) { |
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case BTRFS_COMPRESS_ZLIB: return zlib_decompress(ws, data_in, dest_page, |
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start_byte, srclen, destlen); |
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case BTRFS_COMPRESS_LZO: return lzo_decompress(ws, data_in, dest_page, |
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start_byte, srclen, destlen); |
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case BTRFS_COMPRESS_ZSTD: return zstd_decompress(ws, data_in, dest_page, |
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start_byte, srclen, destlen); |
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case BTRFS_COMPRESS_NONE: |
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default: |
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/* |
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* This can't happen, the type is validated several times |
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* before we get here. |
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*/ |
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BUG(); |
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} |
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} |
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|
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static int btrfs_decompress_bio(struct compressed_bio *cb); |
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|
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static inline int compressed_bio_size(struct btrfs_fs_info *fs_info, |
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unsigned long disk_size) |
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{ |
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u16 csum_size = btrfs_super_csum_size(fs_info->super_copy); |
|
|
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return sizeof(struct compressed_bio) + |
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(DIV_ROUND_UP(disk_size, fs_info->sectorsize)) * csum_size; |
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} |
|
|
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static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio, |
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u64 disk_start) |
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{ |
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struct btrfs_fs_info *fs_info = inode->root->fs_info; |
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SHASH_DESC_ON_STACK(shash, fs_info->csum_shash); |
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const u16 csum_size = btrfs_super_csum_size(fs_info->super_copy); |
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struct page *page; |
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unsigned long i; |
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char *kaddr; |
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u8 csum[BTRFS_CSUM_SIZE]; |
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struct compressed_bio *cb = bio->bi_private; |
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u8 *cb_sum = cb->sums; |
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|
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if (inode->flags & BTRFS_INODE_NODATASUM) |
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return 0; |
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|
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shash->tfm = fs_info->csum_shash; |
|
|
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for (i = 0; i < cb->nr_pages; i++) { |
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page = cb->compressed_pages[i]; |
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|
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kaddr = kmap_atomic(page); |
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crypto_shash_digest(shash, kaddr, PAGE_SIZE, csum); |
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kunmap_atomic(kaddr); |
|
|
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if (memcmp(&csum, cb_sum, csum_size)) { |
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btrfs_print_data_csum_error(inode, disk_start, |
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csum, cb_sum, cb->mirror_num); |
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if (btrfs_io_bio(bio)->device) |
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btrfs_dev_stat_inc_and_print( |
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btrfs_io_bio(bio)->device, |
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BTRFS_DEV_STAT_CORRUPTION_ERRS); |
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return -EIO; |
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} |
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cb_sum += csum_size; |
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} |
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return 0; |
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} |
|
|
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/* when we finish reading compressed pages from the disk, we |
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* decompress them and then run the bio end_io routines on the |
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* decompressed pages (in the inode address space). |
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* |
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* This allows the checksumming and other IO error handling routines |
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* to work normally |
|
* |
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* The compressed pages are freed here, and it must be run |
|
* in process context |
|
*/ |
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static void end_compressed_bio_read(struct bio *bio) |
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{ |
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struct compressed_bio *cb = bio->bi_private; |
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struct inode *inode; |
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struct page *page; |
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unsigned long index; |
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unsigned int mirror = btrfs_io_bio(bio)->mirror_num; |
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int ret = 0; |
|
|
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if (bio->bi_status) |
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cb->errors = 1; |
|
|
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/* if there are more bios still pending for this compressed |
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* extent, just exit |
|
*/ |
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if (!refcount_dec_and_test(&cb->pending_bios)) |
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goto out; |
|
|
|
/* |
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* Record the correct mirror_num in cb->orig_bio so that |
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* read-repair can work properly. |
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*/ |
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btrfs_io_bio(cb->orig_bio)->mirror_num = mirror; |
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cb->mirror_num = mirror; |
|
|
|
/* |
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* Some IO in this cb have failed, just skip checksum as there |
|
* is no way it could be correct. |
|
*/ |
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if (cb->errors == 1) |
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goto csum_failed; |
|
|
|
inode = cb->inode; |
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ret = check_compressed_csum(BTRFS_I(inode), bio, |
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(u64)bio->bi_iter.bi_sector << 9); |
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if (ret) |
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goto csum_failed; |
|
|
|
/* ok, we're the last bio for this extent, lets start |
|
* the decompression. |
|
*/ |
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ret = btrfs_decompress_bio(cb); |
|
|
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csum_failed: |
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if (ret) |
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cb->errors = 1; |
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|
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/* release the compressed pages */ |
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index = 0; |
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for (index = 0; index < cb->nr_pages; index++) { |
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page = cb->compressed_pages[index]; |
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page->mapping = NULL; |
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put_page(page); |
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} |
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|
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/* do io completion on the original bio */ |
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if (cb->errors) { |
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bio_io_error(cb->orig_bio); |
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} else { |
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struct bio_vec *bvec; |
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struct bvec_iter_all iter_all; |
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|
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/* |
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* we have verified the checksum already, set page |
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* checked so the end_io handlers know about it |
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*/ |
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ASSERT(!bio_flagged(bio, BIO_CLONED)); |
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bio_for_each_segment_all(bvec, cb->orig_bio, iter_all) |
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SetPageChecked(bvec->bv_page); |
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|
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bio_endio(cb->orig_bio); |
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} |
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|
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/* finally free the cb struct */ |
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kfree(cb->compressed_pages); |
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kfree(cb); |
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out: |
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bio_put(bio); |
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} |
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|
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/* |
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* Clear the writeback bits on all of the file |
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* pages for a compressed write |
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*/ |
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static noinline void end_compressed_writeback(struct inode *inode, |
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const struct compressed_bio *cb) |
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{ |
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unsigned long index = cb->start >> PAGE_SHIFT; |
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unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT; |
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struct page *pages[16]; |
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unsigned long nr_pages = end_index - index + 1; |
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int i; |
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int ret; |
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|
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if (cb->errors) |
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mapping_set_error(inode->i_mapping, -EIO); |
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|
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while (nr_pages > 0) { |
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ret = find_get_pages_contig(inode->i_mapping, index, |
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min_t(unsigned long, |
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nr_pages, ARRAY_SIZE(pages)), pages); |
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if (ret == 0) { |
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nr_pages -= 1; |
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index += 1; |
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continue; |
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} |
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for (i = 0; i < ret; i++) { |
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if (cb->errors) |
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SetPageError(pages[i]); |
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end_page_writeback(pages[i]); |
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put_page(pages[i]); |
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} |
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nr_pages -= ret; |
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index += ret; |
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} |
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/* the inode may be gone now */ |
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} |
|
|
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/* |
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* do the cleanup once all the compressed pages hit the disk. |
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* This will clear writeback on the file pages and free the compressed |
|
* pages. |
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* |
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* This also calls the writeback end hooks for the file pages so that |
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* metadata and checksums can be updated in the file. |
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*/ |
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static void end_compressed_bio_write(struct bio *bio) |
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{ |
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struct compressed_bio *cb = bio->bi_private; |
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struct inode *inode; |
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struct page *page; |
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unsigned long index; |
|
|
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if (bio->bi_status) |
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cb->errors = 1; |
|
|
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/* if there are more bios still pending for this compressed |
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* extent, just exit |
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*/ |
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if (!refcount_dec_and_test(&cb->pending_bios)) |
|
goto out; |
|
|
|
/* ok, we're the last bio for this extent, step one is to |
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* call back into the FS and do all the end_io operations |
|
*/ |
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inode = cb->inode; |
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cb->compressed_pages[0]->mapping = cb->inode->i_mapping; |
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btrfs_writepage_endio_finish_ordered(cb->compressed_pages[0], |
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cb->start, cb->start + cb->len - 1, |
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!cb->errors); |
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cb->compressed_pages[0]->mapping = NULL; |
|
|
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end_compressed_writeback(inode, cb); |
|
/* note, our inode could be gone now */ |
|
|
|
/* |
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* release the compressed pages, these came from alloc_page and |
|
* are not attached to the inode at all |
|
*/ |
|
index = 0; |
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for (index = 0; index < cb->nr_pages; index++) { |
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page = cb->compressed_pages[index]; |
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page->mapping = NULL; |
|
put_page(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. |
|
*/ |
|
blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start, |
|
unsigned long len, u64 disk_start, |
|
unsigned long compressed_len, |
|
struct page **compressed_pages, |
|
unsigned long nr_pages, |
|
unsigned int write_flags, |
|
struct cgroup_subsys_state *blkcg_css) |
|
{ |
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struct btrfs_fs_info *fs_info = inode->root->fs_info; |
|
struct bio *bio = NULL; |
|
struct compressed_bio *cb; |
|
unsigned long bytes_left; |
|
int pg_index = 0; |
|
struct page *page; |
|
u64 first_byte = disk_start; |
|
blk_status_t ret; |
|
int skip_sum = inode->flags & BTRFS_INODE_NODATASUM; |
|
|
|
WARN_ON(!PAGE_ALIGNED(start)); |
|
cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS); |
|
if (!cb) |
|
return BLK_STS_RESOURCE; |
|
refcount_set(&cb->pending_bios, 0); |
|
cb->errors = 0; |
|
cb->inode = &inode->vfs_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; |
|
|
|
bio = btrfs_bio_alloc(first_byte); |
|
bio->bi_opf = REQ_OP_WRITE | write_flags; |
|
bio->bi_private = cb; |
|
bio->bi_end_io = end_compressed_bio_write; |
|
|
|
if (blkcg_css) { |
|
bio->bi_opf |= REQ_CGROUP_PUNT; |
|
kthread_associate_blkcg(blkcg_css); |
|
} |
|
refcount_set(&cb->pending_bios, 1); |
|
|
|
/* create and submit bios for the compressed pages */ |
|
bytes_left = compressed_len; |
|
for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) { |
|
int submit = 0; |
|
|
|
page = compressed_pages[pg_index]; |
|
page->mapping = inode->vfs_inode.i_mapping; |
|
if (bio->bi_iter.bi_size) |
|
submit = btrfs_bio_fits_in_stripe(page, PAGE_SIZE, bio, |
|
0); |
|
|
|
page->mapping = NULL; |
|
if (submit || bio_add_page(bio, page, PAGE_SIZE, 0) < |
|
PAGE_SIZE) { |
|
/* |
|
* 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 |
|
*/ |
|
refcount_inc(&cb->pending_bios); |
|
ret = btrfs_bio_wq_end_io(fs_info, bio, |
|
BTRFS_WQ_ENDIO_DATA); |
|
BUG_ON(ret); /* -ENOMEM */ |
|
|
|
if (!skip_sum) { |
|
ret = btrfs_csum_one_bio(inode, bio, start, 1); |
|
BUG_ON(ret); /* -ENOMEM */ |
|
} |
|
|
|
ret = btrfs_map_bio(fs_info, bio, 0); |
|
if (ret) { |
|
bio->bi_status = ret; |
|
bio_endio(bio); |
|
} |
|
|
|
bio = btrfs_bio_alloc(first_byte); |
|
bio->bi_opf = REQ_OP_WRITE | write_flags; |
|
bio->bi_private = cb; |
|
bio->bi_end_io = end_compressed_bio_write; |
|
if (blkcg_css) |
|
bio->bi_opf |= REQ_CGROUP_PUNT; |
|
bio_add_page(bio, page, PAGE_SIZE, 0); |
|
} |
|
if (bytes_left < PAGE_SIZE) { |
|
btrfs_info(fs_info, |
|
"bytes left %lu compress len %lu nr %lu", |
|
bytes_left, cb->compressed_len, cb->nr_pages); |
|
} |
|
bytes_left -= PAGE_SIZE; |
|
first_byte += PAGE_SIZE; |
|
cond_resched(); |
|
} |
|
|
|
ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA); |
|
BUG_ON(ret); /* -ENOMEM */ |
|
|
|
if (!skip_sum) { |
|
ret = btrfs_csum_one_bio(inode, bio, start, 1); |
|
BUG_ON(ret); /* -ENOMEM */ |
|
} |
|
|
|
ret = btrfs_map_bio(fs_info, bio, 0); |
|
if (ret) { |
|
bio->bi_status = ret; |
|
bio_endio(bio); |
|
} |
|
|
|
if (blkcg_css) |
|
kthread_associate_blkcg(NULL); |
|
|
|
return 0; |
|
} |
|
|
|
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; |
|
} |
|
|
|
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; |
|
|
|
last_offset = bio_end_offset(cb->orig_bio); |
|
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_SHIFT; |
|
|
|
while (last_offset < compressed_end) { |
|
pg_index = last_offset >> PAGE_SHIFT; |
|
|
|
if (pg_index > end_index) |
|
break; |
|
|
|
page = xa_load(&mapping->i_pages, pg_index); |
|
if (page && !xa_is_value(page)) { |
|
misses++; |
|
if (misses > 4) |
|
break; |
|
goto next; |
|
} |
|
|
|
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); |
|
goto next; |
|
} |
|
|
|
end = last_offset + PAGE_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_SIZE); |
|
read_unlock(&em_tree->lock); |
|
|
|
if (!em || last_offset < em->start || |
|
(last_offset + PAGE_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); |
|
put_page(page); |
|
break; |
|
} |
|
free_extent_map(em); |
|
|
|
if (page->index == end_index) { |
|
char *userpage; |
|
size_t zero_offset = offset_in_page(isize); |
|
|
|
if (zero_offset) { |
|
int zeros; |
|
zeros = PAGE_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_SIZE, 0); |
|
|
|
if (ret == PAGE_SIZE) { |
|
nr_pages++; |
|
put_page(page); |
|
} else { |
|
unlock_extent(tree, last_offset, end); |
|
unlock_page(page); |
|
put_page(page); |
|
break; |
|
} |
|
next: |
|
last_offset += PAGE_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 |
|
*/ |
|
blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, |
|
int mirror_num, unsigned long bio_flags) |
|
{ |
|
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); |
|
struct extent_map_tree *em_tree; |
|
struct compressed_bio *cb; |
|
unsigned long compressed_len; |
|
unsigned long nr_pages; |
|
unsigned long pg_index; |
|
struct page *page; |
|
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; |
|
blk_status_t ret = BLK_STS_RESOURCE; |
|
int faili = 0; |
|
const u16 csum_size = btrfs_super_csum_size(fs_info->super_copy); |
|
u8 *sums; |
|
|
|
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_first_page_all(bio)), |
|
PAGE_SIZE); |
|
read_unlock(&em_tree->lock); |
|
if (!em) |
|
return BLK_STS_IOERR; |
|
|
|
compressed_len = em->block_len; |
|
cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS); |
|
if (!cb) |
|
goto out; |
|
|
|
refcount_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 = bio->bi_iter.bi_size; |
|
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_SIZE); |
|
cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *), |
|
GFP_NOFS); |
|
if (!cb->compressed_pages) |
|
goto fail1; |
|
|
|
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 = BLK_STS_RESOURCE; |
|
goto fail2; |
|
} |
|
} |
|
faili = nr_pages - 1; |
|
cb->nr_pages = nr_pages; |
|
|
|
add_ra_bio_pages(inode, em_start + em_len, cb); |
|
|
|
/* include any pages we added in add_ra-bio_pages */ |
|
cb->len = bio->bi_iter.bi_size; |
|
|
|
comp_bio = btrfs_bio_alloc(cur_disk_byte); |
|
comp_bio->bi_opf = REQ_OP_READ; |
|
comp_bio->bi_private = cb; |
|
comp_bio->bi_end_io = end_compressed_bio_read; |
|
refcount_set(&cb->pending_bios, 1); |
|
|
|
for (pg_index = 0; pg_index < nr_pages; pg_index++) { |
|
int submit = 0; |
|
|
|
page = cb->compressed_pages[pg_index]; |
|
page->mapping = inode->i_mapping; |
|
page->index = em_start >> PAGE_SHIFT; |
|
|
|
if (comp_bio->bi_iter.bi_size) |
|
submit = btrfs_bio_fits_in_stripe(page, PAGE_SIZE, |
|
comp_bio, 0); |
|
|
|
page->mapping = NULL; |
|
if (submit || bio_add_page(comp_bio, page, PAGE_SIZE, 0) < |
|
PAGE_SIZE) { |
|
unsigned int nr_sectors; |
|
|
|
ret = btrfs_bio_wq_end_io(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 |
|
*/ |
|
refcount_inc(&cb->pending_bios); |
|
|
|
if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) { |
|
ret = btrfs_lookup_bio_sums(inode, comp_bio, |
|
(u64)-1, sums); |
|
BUG_ON(ret); /* -ENOMEM */ |
|
} |
|
|
|
nr_sectors = DIV_ROUND_UP(comp_bio->bi_iter.bi_size, |
|
fs_info->sectorsize); |
|
sums += csum_size * nr_sectors; |
|
|
|
ret = btrfs_map_bio(fs_info, comp_bio, mirror_num); |
|
if (ret) { |
|
comp_bio->bi_status = ret; |
|
bio_endio(comp_bio); |
|
} |
|
|
|
comp_bio = btrfs_bio_alloc(cur_disk_byte); |
|
comp_bio->bi_opf = REQ_OP_READ; |
|
comp_bio->bi_private = cb; |
|
comp_bio->bi_end_io = end_compressed_bio_read; |
|
|
|
bio_add_page(comp_bio, page, PAGE_SIZE, 0); |
|
} |
|
cur_disk_byte += PAGE_SIZE; |
|
} |
|
|
|
ret = btrfs_bio_wq_end_io(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(inode, comp_bio, (u64)-1, sums); |
|
BUG_ON(ret); /* -ENOMEM */ |
|
} |
|
|
|
ret = btrfs_map_bio(fs_info, comp_bio, mirror_num); |
|
if (ret) { |
|
comp_bio->bi_status = ret; |
|
bio_endio(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; |
|
} |
|
|
|
/* |
|
* 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 |
|
* |
|
* @max_out tells us the max number of bytes that we're allowed to |
|
* stuff into pages |
|
*/ |
|
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; |
|
} |
|
|
|
/* |
|
* pages_in is an array of pages with compressed data. |
|
* |
|
* disk_start is the starting logical offset of this array in the file |
|
* |
|
* orig_bio contains the pages from the file that we want to decompress into |
|
* |
|
* 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_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(type, 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 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(const char *buf, unsigned long buf_start, |
|
unsigned long total_out, u64 disk_start, |
|
struct bio *bio) |
|
{ |
|
unsigned long buf_offset; |
|
unsigned long current_buf_start; |
|
unsigned long start_byte; |
|
unsigned long prev_start_byte; |
|
unsigned long working_bytes = total_out - buf_start; |
|
unsigned long bytes; |
|
char *kaddr; |
|
struct bio_vec bvec = bio_iter_iovec(bio, bio->bi_iter); |
|
|
|
/* |
|
* 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(bvec.bv_page) - 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_t(unsigned long, bvec.bv_len, |
|
PAGE_SIZE - (buf_offset % PAGE_SIZE)); |
|
bytes = min(bytes, working_bytes); |
|
|
|
kaddr = kmap_atomic(bvec.bv_page); |
|
memcpy(kaddr + bvec.bv_offset, buf + buf_offset, bytes); |
|
kunmap_atomic(kaddr); |
|
flush_dcache_page(bvec.bv_page); |
|
|
|
buf_offset += bytes; |
|
working_bytes -= bytes; |
|
current_buf_start += bytes; |
|
|
|
/* check if we need to pick another page */ |
|
bio_advance(bio, bytes); |
|
if (!bio->bi_iter.bi_size) |
|
return 0; |
|
bvec = bio_iter_iovec(bio, bio->bi_iter); |
|
prev_start_byte = start_byte; |
|
start_byte = page_offset(bvec.bv_page) - disk_start; |
|
|
|
/* |
|
* We need to make sure we're only adjusting |
|
* our offset into compression working buffer when |
|
* we're switching pages. Otherwise we can incorrectly |
|
* keep copying when we were actually done. |
|
*/ |
|
if (start_byte != prev_start_byte) { |
|
/* |
|
* 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; |
|
} |
|
|
|
/* |
|
* 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(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(page); |
|
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; |
|
}
|
|
|