mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-06 02:24:14 +08:00
00032d38ea
The data and metadata callback implementation both use the same function. We can remove the call indirection completely. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
1607 lines
41 KiB
C
1607 lines
41 KiB
C
// 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/highmem.h>
|
|
#include <linux/time.h>
|
|
#include <linux/init.h>
|
|
#include <linux/string.h>
|
|
#include <linux/backing-dev.h>
|
|
#include <linux/writeback.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/sched/mm.h>
|
|
#include <linux/log2.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"
|
|
|
|
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];
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static int btrfs_decompress_bio(struct compressed_bio *cb);
|
|
|
|
static inline int compressed_bio_size(struct btrfs_fs_info *fs_info,
|
|
unsigned long disk_size)
|
|
{
|
|
u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
|
|
|
|
return sizeof(struct compressed_bio) +
|
|
(DIV_ROUND_UP(disk_size, fs_info->sectorsize)) * csum_size;
|
|
}
|
|
|
|
static int check_compressed_csum(struct btrfs_inode *inode,
|
|
struct compressed_bio *cb,
|
|
u64 disk_start)
|
|
{
|
|
int ret;
|
|
struct page *page;
|
|
unsigned long i;
|
|
char *kaddr;
|
|
u32 csum;
|
|
u32 *cb_sum = &cb->sums;
|
|
|
|
if (inode->flags & BTRFS_INODE_NODATASUM)
|
|
return 0;
|
|
|
|
for (i = 0; i < cb->nr_pages; i++) {
|
|
page = cb->compressed_pages[i];
|
|
csum = ~(u32)0;
|
|
|
|
kaddr = kmap_atomic(page);
|
|
csum = btrfs_csum_data(kaddr, csum, PAGE_SIZE);
|
|
btrfs_csum_final(csum, (u8 *)&csum);
|
|
kunmap_atomic(kaddr);
|
|
|
|
if (csum != *cb_sum) {
|
|
btrfs_print_data_csum_error(inode, disk_start, csum,
|
|
*cb_sum, cb->mirror_num);
|
|
ret = -EIO;
|
|
goto fail;
|
|
}
|
|
cb_sum++;
|
|
|
|
}
|
|
ret = 0;
|
|
fail:
|
|
return ret;
|
|
}
|
|
|
|
/* when we finish reading compressed pages from the disk, we
|
|
* decompress them and then run the bio end_io routines on the
|
|
* decompressed pages (in the inode address space).
|
|
*
|
|
* This allows the checksumming and other IO error handling routines
|
|
* to work normally
|
|
*
|
|
* The compressed pages are freed here, and it must be run
|
|
* in process context
|
|
*/
|
|
static void end_compressed_bio_read(struct bio *bio)
|
|
{
|
|
struct compressed_bio *cb = bio->bi_private;
|
|
struct inode *inode;
|
|
struct page *page;
|
|
unsigned long index;
|
|
unsigned int mirror = btrfs_io_bio(bio)->mirror_num;
|
|
int ret = 0;
|
|
|
|
if (bio->bi_status)
|
|
cb->errors = 1;
|
|
|
|
/* if there are more bios still pending for this compressed
|
|
* extent, just exit
|
|
*/
|
|
if (!refcount_dec_and_test(&cb->pending_bios))
|
|
goto out;
|
|
|
|
/*
|
|
* Record the correct mirror_num in cb->orig_bio so that
|
|
* read-repair can work properly.
|
|
*/
|
|
ASSERT(btrfs_io_bio(cb->orig_bio));
|
|
btrfs_io_bio(cb->orig_bio)->mirror_num = mirror;
|
|
cb->mirror_num = mirror;
|
|
|
|
/*
|
|
* Some IO in this cb have failed, just skip checksum as there
|
|
* is no way it could be correct.
|
|
*/
|
|
if (cb->errors == 1)
|
|
goto csum_failed;
|
|
|
|
inode = cb->inode;
|
|
ret = check_compressed_csum(BTRFS_I(inode), cb,
|
|
(u64)bio->bi_iter.bi_sector << 9);
|
|
if (ret)
|
|
goto csum_failed;
|
|
|
|
/* ok, we're the last bio for this extent, lets start
|
|
* the decompression.
|
|
*/
|
|
ret = btrfs_decompress_bio(cb);
|
|
|
|
csum_failed:
|
|
if (ret)
|
|
cb->errors = 1;
|
|
|
|
/* release the compressed pages */
|
|
index = 0;
|
|
for (index = 0; index < cb->nr_pages; index++) {
|
|
page = cb->compressed_pages[index];
|
|
page->mapping = NULL;
|
|
put_page(page);
|
|
}
|
|
|
|
/* do io completion on the original bio */
|
|
if (cb->errors) {
|
|
bio_io_error(cb->orig_bio);
|
|
} else {
|
|
int i;
|
|
struct bio_vec *bvec;
|
|
|
|
/*
|
|
* we have verified the checksum already, set page
|
|
* checked so the end_io handlers know about it
|
|
*/
|
|
ASSERT(!bio_flagged(bio, BIO_CLONED));
|
|
bio_for_each_segment_all(bvec, cb->orig_bio, i)
|
|
SetPageChecked(bvec->bv_page);
|
|
|
|
bio_endio(cb->orig_bio);
|
|
}
|
|
|
|
/* finally free the cb struct */
|
|
kfree(cb->compressed_pages);
|
|
kfree(cb);
|
|
out:
|
|
bio_put(bio);
|
|
}
|
|
|
|
/*
|
|
* Clear the writeback bits on all of the file
|
|
* pages for a compressed write
|
|
*/
|
|
static noinline void end_compressed_writeback(struct inode *inode,
|
|
const struct compressed_bio *cb)
|
|
{
|
|
unsigned long index = cb->start >> PAGE_SHIFT;
|
|
unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT;
|
|
struct page *pages[16];
|
|
unsigned long nr_pages = end_index - index + 1;
|
|
int i;
|
|
int ret;
|
|
|
|
if (cb->errors)
|
|
mapping_set_error(inode->i_mapping, -EIO);
|
|
|
|
while (nr_pages > 0) {
|
|
ret = find_get_pages_contig(inode->i_mapping, index,
|
|
min_t(unsigned long,
|
|
nr_pages, ARRAY_SIZE(pages)), pages);
|
|
if (ret == 0) {
|
|
nr_pages -= 1;
|
|
index += 1;
|
|
continue;
|
|
}
|
|
for (i = 0; i < ret; i++) {
|
|
if (cb->errors)
|
|
SetPageError(pages[i]);
|
|
end_page_writeback(pages[i]);
|
|
put_page(pages[i]);
|
|
}
|
|
nr_pages -= ret;
|
|
index += ret;
|
|
}
|
|
/* the inode may be gone now */
|
|
}
|
|
|
|
/*
|
|
* do the cleanup once all the compressed pages hit the disk.
|
|
* This will clear writeback on the file pages and free the compressed
|
|
* pages.
|
|
*
|
|
* This also calls the writeback end hooks for the file pages so that
|
|
* metadata and checksums can be updated in the file.
|
|
*/
|
|
static void end_compressed_bio_write(struct bio *bio)
|
|
{
|
|
struct extent_io_tree *tree;
|
|
struct compressed_bio *cb = bio->bi_private;
|
|
struct inode *inode;
|
|
struct page *page;
|
|
unsigned long index;
|
|
|
|
if (bio->bi_status)
|
|
cb->errors = 1;
|
|
|
|
/* if there are more bios still pending for this compressed
|
|
* extent, just exit
|
|
*/
|
|
if (!refcount_dec_and_test(&cb->pending_bios))
|
|
goto out;
|
|
|
|
/* ok, we're the last bio for this extent, step one is to
|
|
* call back into the FS and do all the end_io operations
|
|
*/
|
|
inode = cb->inode;
|
|
tree = &BTRFS_I(inode)->io_tree;
|
|
cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
|
|
tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
|
|
cb->start,
|
|
cb->start + cb->len - 1,
|
|
NULL,
|
|
bio->bi_status ?
|
|
BLK_STS_OK : BLK_STS_NOTSUPP);
|
|
cb->compressed_pages[0]->mapping = NULL;
|
|
|
|
end_compressed_writeback(inode, cb);
|
|
/* note, our inode could be gone now */
|
|
|
|
/*
|
|
* release the compressed pages, these came from alloc_page and
|
|
* are not attached to the inode at all
|
|
*/
|
|
index = 0;
|
|
for (index = 0; index < cb->nr_pages; index++) {
|
|
page = cb->compressed_pages[index];
|
|
page->mapping = NULL;
|
|
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 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 btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
|
|
struct bio *bio = NULL;
|
|
struct compressed_bio *cb;
|
|
unsigned long bytes_left;
|
|
int pg_index = 0;
|
|
struct page *page;
|
|
u64 first_byte = disk_start;
|
|
struct block_device *bdev;
|
|
blk_status_t ret;
|
|
int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
|
|
|
|
WARN_ON(start & ((u64)PAGE_SIZE - 1));
|
|
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;
|
|
cb->start = start;
|
|
cb->len = len;
|
|
cb->mirror_num = 0;
|
|
cb->compressed_pages = compressed_pages;
|
|
cb->compressed_len = compressed_len;
|
|
cb->orig_bio = NULL;
|
|
cb->nr_pages = nr_pages;
|
|
|
|
bdev = fs_info->fs_devices->latest_bdev;
|
|
|
|
bio = btrfs_bio_alloc(bdev, first_byte);
|
|
bio->bi_opf = REQ_OP_WRITE | write_flags;
|
|
bio->bi_private = cb;
|
|
bio->bi_end_io = end_compressed_bio_write;
|
|
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->i_mapping;
|
|
if (bio->bi_iter.bi_size)
|
|
submit = btrfs_merge_bio_hook(page, 0, 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, 1);
|
|
if (ret) {
|
|
bio->bi_status = ret;
|
|
bio_endio(bio);
|
|
}
|
|
|
|
bio = btrfs_bio_alloc(bdev, first_byte);
|
|
bio->bi_opf = REQ_OP_WRITE | write_flags;
|
|
bio->bi_private = cb;
|
|
bio->bi_end_io = end_compressed_bio_write;
|
|
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, 1);
|
|
if (ret) {
|
|
bio->bi_status = ret;
|
|
bio_endio(bio);
|
|
}
|
|
|
|
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;
|
|
|
|
rcu_read_lock();
|
|
page = radix_tree_lookup(&mapping->i_pages, pg_index);
|
|
rcu_read_unlock();
|
|
if (page && !radix_tree_exceptional_entry(page)) {
|
|
misses++;
|
|
if (misses > 4)
|
|
break;
|
|
goto next;
|
|
}
|
|
|
|
page = __page_cache_alloc(mapping_gfp_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 = isize & (PAGE_SIZE - 1);
|
|
|
|
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_io_tree *tree;
|
|
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 block_device *bdev;
|
|
struct bio *comp_bio;
|
|
u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9;
|
|
u64 em_len;
|
|
u64 em_start;
|
|
struct extent_map *em;
|
|
blk_status_t ret = BLK_STS_RESOURCE;
|
|
int faili = 0;
|
|
u32 *sums;
|
|
|
|
tree = &BTRFS_I(inode)->io_tree;
|
|
em_tree = &BTRFS_I(inode)->extent_tree;
|
|
|
|
/* we need the actual starting offset of this extent in the file */
|
|
read_lock(&em_tree->lock);
|
|
em = lookup_extent_mapping(em_tree,
|
|
page_offset(bio_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;
|
|
|
|
bdev = fs_info->fs_devices->latest_bdev;
|
|
|
|
for (pg_index = 0; pg_index < nr_pages; pg_index++) {
|
|
cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
|
|
__GFP_HIGHMEM);
|
|
if (!cb->compressed_pages[pg_index]) {
|
|
faili = pg_index - 1;
|
|
ret = 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(bdev, 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_merge_bio_hook(page, 0, PAGE_SIZE,
|
|
comp_bio, 0);
|
|
|
|
page->mapping = NULL;
|
|
if (submit || bio_add_page(comp_bio, page, PAGE_SIZE, 0) <
|
|
PAGE_SIZE) {
|
|
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,
|
|
sums);
|
|
BUG_ON(ret); /* -ENOMEM */
|
|
}
|
|
sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
|
|
fs_info->sectorsize);
|
|
|
|
ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
|
|
if (ret) {
|
|
comp_bio->bi_status = ret;
|
|
bio_endio(comp_bio);
|
|
}
|
|
|
|
comp_bio = btrfs_bio_alloc(bdev, 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, sums);
|
|
BUG_ON(ret); /* -ENOMEM */
|
|
}
|
|
|
|
ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
|
|
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 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(void)
|
|
{
|
|
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);
|
|
}
|
|
|
|
struct workspaces_list {
|
|
struct list_head idle_ws;
|
|
spinlock_t ws_lock;
|
|
/* Number of free workspaces */
|
|
int free_ws;
|
|
/* Total number of allocated workspaces */
|
|
atomic_t total_ws;
|
|
/* Waiters for a free workspace */
|
|
wait_queue_head_t ws_wait;
|
|
};
|
|
|
|
static struct workspaces_list btrfs_comp_ws[BTRFS_COMPRESS_TYPES];
|
|
|
|
static struct workspaces_list btrfs_heuristic_ws;
|
|
|
|
static const struct btrfs_compress_op * const btrfs_compress_op[] = {
|
|
&btrfs_zlib_compress,
|
|
&btrfs_lzo_compress,
|
|
&btrfs_zstd_compress,
|
|
};
|
|
|
|
void __init btrfs_init_compress(void)
|
|
{
|
|
struct list_head *workspace;
|
|
int i;
|
|
|
|
INIT_LIST_HEAD(&btrfs_heuristic_ws.idle_ws);
|
|
spin_lock_init(&btrfs_heuristic_ws.ws_lock);
|
|
atomic_set(&btrfs_heuristic_ws.total_ws, 0);
|
|
init_waitqueue_head(&btrfs_heuristic_ws.ws_wait);
|
|
|
|
workspace = alloc_heuristic_ws();
|
|
if (IS_ERR(workspace)) {
|
|
pr_warn(
|
|
"BTRFS: cannot preallocate heuristic workspace, will try later\n");
|
|
} else {
|
|
atomic_set(&btrfs_heuristic_ws.total_ws, 1);
|
|
btrfs_heuristic_ws.free_ws = 1;
|
|
list_add(workspace, &btrfs_heuristic_ws.idle_ws);
|
|
}
|
|
|
|
for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
|
|
INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws);
|
|
spin_lock_init(&btrfs_comp_ws[i].ws_lock);
|
|
atomic_set(&btrfs_comp_ws[i].total_ws, 0);
|
|
init_waitqueue_head(&btrfs_comp_ws[i].ws_wait);
|
|
|
|
/*
|
|
* Preallocate one workspace for each compression type so
|
|
* we can guarantee forward progress in the worst case
|
|
*/
|
|
workspace = btrfs_compress_op[i]->alloc_workspace();
|
|
if (IS_ERR(workspace)) {
|
|
pr_warn("BTRFS: cannot preallocate compression workspace, will try later\n");
|
|
} else {
|
|
atomic_set(&btrfs_comp_ws[i].total_ws, 1);
|
|
btrfs_comp_ws[i].free_ws = 1;
|
|
list_add(workspace, &btrfs_comp_ws[i].idle_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.
|
|
*/
|
|
static struct list_head *__find_workspace(int type, bool heuristic)
|
|
{
|
|
struct list_head *workspace;
|
|
int cpus = num_online_cpus();
|
|
int idx = type - 1;
|
|
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;
|
|
|
|
if (heuristic) {
|
|
idle_ws = &btrfs_heuristic_ws.idle_ws;
|
|
ws_lock = &btrfs_heuristic_ws.ws_lock;
|
|
total_ws = &btrfs_heuristic_ws.total_ws;
|
|
ws_wait = &btrfs_heuristic_ws.ws_wait;
|
|
free_ws = &btrfs_heuristic_ws.free_ws;
|
|
} else {
|
|
idle_ws = &btrfs_comp_ws[idx].idle_ws;
|
|
ws_lock = &btrfs_comp_ws[idx].ws_lock;
|
|
total_ws = &btrfs_comp_ws[idx].total_ws;
|
|
ws_wait = &btrfs_comp_ws[idx].ws_wait;
|
|
free_ws = &btrfs_comp_ws[idx].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();
|
|
if (heuristic)
|
|
workspace = alloc_heuristic_ws();
|
|
else
|
|
workspace = btrfs_compress_op[idx]->alloc_workspace();
|
|
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 *find_workspace(int type)
|
|
{
|
|
return __find_workspace(type, false);
|
|
}
|
|
|
|
/*
|
|
* put a workspace struct back on the list or free it if we have enough
|
|
* idle ones sitting around
|
|
*/
|
|
static void __free_workspace(int type, struct list_head *workspace,
|
|
bool heuristic)
|
|
{
|
|
int idx = type - 1;
|
|
struct list_head *idle_ws;
|
|
spinlock_t *ws_lock;
|
|
atomic_t *total_ws;
|
|
wait_queue_head_t *ws_wait;
|
|
int *free_ws;
|
|
|
|
if (heuristic) {
|
|
idle_ws = &btrfs_heuristic_ws.idle_ws;
|
|
ws_lock = &btrfs_heuristic_ws.ws_lock;
|
|
total_ws = &btrfs_heuristic_ws.total_ws;
|
|
ws_wait = &btrfs_heuristic_ws.ws_wait;
|
|
free_ws = &btrfs_heuristic_ws.free_ws;
|
|
} else {
|
|
idle_ws = &btrfs_comp_ws[idx].idle_ws;
|
|
ws_lock = &btrfs_comp_ws[idx].ws_lock;
|
|
total_ws = &btrfs_comp_ws[idx].total_ws;
|
|
ws_wait = &btrfs_comp_ws[idx].ws_wait;
|
|
free_ws = &btrfs_comp_ws[idx].free_ws;
|
|
}
|
|
|
|
spin_lock(ws_lock);
|
|
if (*free_ws <= num_online_cpus()) {
|
|
list_add(workspace, idle_ws);
|
|
(*free_ws)++;
|
|
spin_unlock(ws_lock);
|
|
goto wake;
|
|
}
|
|
spin_unlock(ws_lock);
|
|
|
|
if (heuristic)
|
|
free_heuristic_ws(workspace);
|
|
else
|
|
btrfs_compress_op[idx]->free_workspace(workspace);
|
|
atomic_dec(total_ws);
|
|
wake:
|
|
cond_wake_up(ws_wait);
|
|
}
|
|
|
|
static void free_workspace(int type, struct list_head *ws)
|
|
{
|
|
return __free_workspace(type, ws, false);
|
|
}
|
|
|
|
/*
|
|
* cleanup function for module exit
|
|
*/
|
|
static void free_workspaces(void)
|
|
{
|
|
struct list_head *workspace;
|
|
int i;
|
|
|
|
while (!list_empty(&btrfs_heuristic_ws.idle_ws)) {
|
|
workspace = btrfs_heuristic_ws.idle_ws.next;
|
|
list_del(workspace);
|
|
free_heuristic_ws(workspace);
|
|
atomic_dec(&btrfs_heuristic_ws.total_ws);
|
|
}
|
|
|
|
for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
|
|
while (!list_empty(&btrfs_comp_ws[i].idle_ws)) {
|
|
workspace = btrfs_comp_ws[i].idle_ws.next;
|
|
list_del(workspace);
|
|
btrfs_compress_op[i]->free_workspace(workspace);
|
|
atomic_dec(&btrfs_comp_ws[i].total_ws);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
struct list_head *workspace;
|
|
int ret;
|
|
int type = type_level & 0xF;
|
|
|
|
workspace = find_workspace(type);
|
|
|
|
btrfs_compress_op[type - 1]->set_level(workspace, type_level);
|
|
ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
|
|
start, pages,
|
|
out_pages,
|
|
total_in, total_out);
|
|
free_workspace(type, workspace);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* pages_in is an array of pages with compressed data.
|
|
*
|
|
* disk_start is the starting logical offset of this array in the file
|
|
*
|
|
* 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 = find_workspace(type);
|
|
ret = btrfs_compress_op[type - 1]->decompress_bio(workspace, cb);
|
|
free_workspace(type, workspace);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* a less complex decompression routine. Our compressed data fits in a
|
|
* single page, and we want to read a single page out of it.
|
|
* start_byte tells us the offset into the compressed data we're interested in
|
|
*/
|
|
int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
|
|
unsigned long start_byte, size_t srclen, size_t destlen)
|
|
{
|
|
struct list_head *workspace;
|
|
int ret;
|
|
|
|
workspace = find_workspace(type);
|
|
|
|
ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
|
|
dest_page, start_byte,
|
|
srclen, destlen);
|
|
|
|
free_workspace(type, workspace);
|
|
return ret;
|
|
}
|
|
|
|
void __cold btrfs_exit_compress(void)
|
|
{
|
|
free_workspaces();
|
|
}
|
|
|
|
/*
|
|
* Copy uncompressed data from working buffer to pages.
|
|
*
|
|
* buf_start is the byte offset we're of the start of our workspace buffer.
|
|
*
|
|
* total_out is the last byte of the buffer
|
|
*/
|
|
int btrfs_decompress_buf2page(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);
|
|
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 compressiability 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 possition 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 = __find_workspace(0, true);
|
|
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:
|
|
__free_workspace(0, ws_list, true);
|
|
return ret;
|
|
}
|
|
|
|
unsigned int btrfs_compress_str2level(const char *str)
|
|
{
|
|
if (strncmp(str, "zlib", 4) != 0)
|
|
return 0;
|
|
|
|
/* Accepted form: zlib:1 up to zlib:9 and nothing left after the number */
|
|
if (str[4] == ':' && '1' <= str[5] && str[5] <= '9' && str[6] == 0)
|
|
return str[5] - '0';
|
|
|
|
return BTRFS_ZLIB_DEFAULT_LEVEL;
|
|
}
|