swh:1:snp:77163734605b0ec556b01d897b7bb4a7e30d46b6
Tip revision: a7904a538933c525096ca2ccde1e60d0ee62c08e authored by Linus Torvalds on 19 December 2021, 22:14:33 UTC
Linux 5.16-rc6
Linux 5.16-rc6
Tip revision: a7904a5
decompressor_lzma.c
// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/xz.h>
#include <linux/module.h>
#include "compress.h"
struct z_erofs_lzma {
struct z_erofs_lzma *next;
struct xz_dec_microlzma *state;
struct xz_buf buf;
u8 bounce[PAGE_SIZE];
};
/* considering the LZMA performance, no need to use a lockless list for now */
static DEFINE_SPINLOCK(z_erofs_lzma_lock);
static unsigned int z_erofs_lzma_max_dictsize;
static unsigned int z_erofs_lzma_nstrms, z_erofs_lzma_avail_strms;
static struct z_erofs_lzma *z_erofs_lzma_head;
static DECLARE_WAIT_QUEUE_HEAD(z_erofs_lzma_wq);
module_param_named(lzma_streams, z_erofs_lzma_nstrms, uint, 0444);
void z_erofs_lzma_exit(void)
{
/* there should be no running fs instance */
while (z_erofs_lzma_avail_strms) {
struct z_erofs_lzma *strm;
spin_lock(&z_erofs_lzma_lock);
strm = z_erofs_lzma_head;
if (!strm) {
spin_unlock(&z_erofs_lzma_lock);
DBG_BUGON(1);
return;
}
z_erofs_lzma_head = NULL;
spin_unlock(&z_erofs_lzma_lock);
while (strm) {
struct z_erofs_lzma *n = strm->next;
if (strm->state)
xz_dec_microlzma_end(strm->state);
kfree(strm);
--z_erofs_lzma_avail_strms;
strm = n;
}
}
}
int z_erofs_lzma_init(void)
{
unsigned int i;
/* by default, use # of possible CPUs instead */
if (!z_erofs_lzma_nstrms)
z_erofs_lzma_nstrms = num_possible_cpus();
for (i = 0; i < z_erofs_lzma_nstrms; ++i) {
struct z_erofs_lzma *strm = kzalloc(sizeof(*strm), GFP_KERNEL);
if (!strm) {
z_erofs_lzma_exit();
return -ENOMEM;
}
spin_lock(&z_erofs_lzma_lock);
strm->next = z_erofs_lzma_head;
z_erofs_lzma_head = strm;
spin_unlock(&z_erofs_lzma_lock);
++z_erofs_lzma_avail_strms;
}
return 0;
}
int z_erofs_load_lzma_config(struct super_block *sb,
struct erofs_super_block *dsb,
struct z_erofs_lzma_cfgs *lzma, int size)
{
static DEFINE_MUTEX(lzma_resize_mutex);
unsigned int dict_size, i;
struct z_erofs_lzma *strm, *head = NULL;
int err;
if (!lzma || size < sizeof(struct z_erofs_lzma_cfgs)) {
erofs_err(sb, "invalid lzma cfgs, size=%u", size);
return -EINVAL;
}
if (lzma->format) {
erofs_err(sb, "unidentified lzma format %x, please check kernel version",
le16_to_cpu(lzma->format));
return -EINVAL;
}
dict_size = le32_to_cpu(lzma->dict_size);
if (dict_size > Z_EROFS_LZMA_MAX_DICT_SIZE || dict_size < 4096) {
erofs_err(sb, "unsupported lzma dictionary size %u",
dict_size);
return -EINVAL;
}
erofs_info(sb, "EXPERIMENTAL MicroLZMA in use. Use at your own risk!");
/* in case 2 z_erofs_load_lzma_config() race to avoid deadlock */
mutex_lock(&lzma_resize_mutex);
if (z_erofs_lzma_max_dictsize >= dict_size) {
mutex_unlock(&lzma_resize_mutex);
return 0;
}
/* 1. collect/isolate all streams for the following check */
for (i = 0; i < z_erofs_lzma_avail_strms; ++i) {
struct z_erofs_lzma *last;
again:
spin_lock(&z_erofs_lzma_lock);
strm = z_erofs_lzma_head;
if (!strm) {
spin_unlock(&z_erofs_lzma_lock);
wait_event(z_erofs_lzma_wq,
READ_ONCE(z_erofs_lzma_head));
goto again;
}
z_erofs_lzma_head = NULL;
spin_unlock(&z_erofs_lzma_lock);
for (last = strm; last->next; last = last->next)
++i;
last->next = head;
head = strm;
}
err = 0;
/* 2. walk each isolated stream and grow max dict_size if needed */
for (strm = head; strm; strm = strm->next) {
if (strm->state)
xz_dec_microlzma_end(strm->state);
strm->state = xz_dec_microlzma_alloc(XZ_PREALLOC, dict_size);
if (!strm->state)
err = -ENOMEM;
}
/* 3. push back all to the global list and update max dict_size */
spin_lock(&z_erofs_lzma_lock);
DBG_BUGON(z_erofs_lzma_head);
z_erofs_lzma_head = head;
spin_unlock(&z_erofs_lzma_lock);
z_erofs_lzma_max_dictsize = dict_size;
mutex_unlock(&lzma_resize_mutex);
return err;
}
int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
struct page **pagepool)
{
const unsigned int nrpages_out =
PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
const unsigned int nrpages_in =
PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
unsigned int inputmargin, inlen, outlen, pageofs;
struct z_erofs_lzma *strm;
u8 *kin;
bool bounced = false;
int no, ni, j, err = 0;
/* 1. get the exact LZMA compressed size */
kin = kmap(*rq->in);
inputmargin = 0;
while (!kin[inputmargin & ~PAGE_MASK])
if (!(++inputmargin & ~PAGE_MASK))
break;
if (inputmargin >= PAGE_SIZE) {
kunmap(*rq->in);
return -EFSCORRUPTED;
}
rq->inputsize -= inputmargin;
/* 2. get an available lzma context */
again:
spin_lock(&z_erofs_lzma_lock);
strm = z_erofs_lzma_head;
if (!strm) {
spin_unlock(&z_erofs_lzma_lock);
wait_event(z_erofs_lzma_wq, READ_ONCE(z_erofs_lzma_head));
goto again;
}
z_erofs_lzma_head = strm->next;
spin_unlock(&z_erofs_lzma_lock);
/* 3. multi-call decompress */
inlen = rq->inputsize;
outlen = rq->outputsize;
xz_dec_microlzma_reset(strm->state, inlen, outlen,
!rq->partial_decoding);
pageofs = rq->pageofs_out;
strm->buf.in = kin + inputmargin;
strm->buf.in_pos = 0;
strm->buf.in_size = min_t(u32, inlen, PAGE_SIZE - inputmargin);
inlen -= strm->buf.in_size;
strm->buf.out = NULL;
strm->buf.out_pos = 0;
strm->buf.out_size = 0;
for (ni = 0, no = -1;;) {
enum xz_ret xz_err;
if (strm->buf.out_pos == strm->buf.out_size) {
if (strm->buf.out) {
kunmap(rq->out[no]);
strm->buf.out = NULL;
}
if (++no >= nrpages_out || !outlen) {
erofs_err(rq->sb, "decompressed buf out of bound");
err = -EFSCORRUPTED;
break;
}
strm->buf.out_pos = 0;
strm->buf.out_size = min_t(u32, outlen,
PAGE_SIZE - pageofs);
outlen -= strm->buf.out_size;
if (rq->out[no])
strm->buf.out = kmap(rq->out[no]) + pageofs;
pageofs = 0;
} else if (strm->buf.in_pos == strm->buf.in_size) {
kunmap(rq->in[ni]);
if (++ni >= nrpages_in || !inlen) {
erofs_err(rq->sb, "compressed buf out of bound");
err = -EFSCORRUPTED;
break;
}
strm->buf.in_pos = 0;
strm->buf.in_size = min_t(u32, inlen, PAGE_SIZE);
inlen -= strm->buf.in_size;
kin = kmap(rq->in[ni]);
strm->buf.in = kin;
bounced = false;
}
/*
* Handle overlapping: Use bounced buffer if the compressed
* data is under processing; Otherwise, Use short-lived pages
* from the on-stack pagepool where pages share with the same
* request.
*/
if (!bounced && rq->out[no] == rq->in[ni]) {
memcpy(strm->bounce, strm->buf.in, strm->buf.in_size);
strm->buf.in = strm->bounce;
bounced = true;
}
for (j = ni + 1; j < nrpages_in; ++j) {
struct page *tmppage;
if (rq->out[no] != rq->in[j])
continue;
DBG_BUGON(erofs_page_is_managed(EROFS_SB(rq->sb),
rq->in[j]));
tmppage = erofs_allocpage(pagepool,
GFP_KERNEL | __GFP_NOFAIL);
set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
copy_highpage(tmppage, rq->in[j]);
rq->in[j] = tmppage;
}
xz_err = xz_dec_microlzma_run(strm->state, &strm->buf);
DBG_BUGON(strm->buf.out_pos > strm->buf.out_size);
DBG_BUGON(strm->buf.in_pos > strm->buf.in_size);
if (xz_err != XZ_OK) {
if (xz_err == XZ_STREAM_END && !outlen)
break;
erofs_err(rq->sb, "failed to decompress %d in[%u] out[%u]",
xz_err, rq->inputsize, rq->outputsize);
err = -EFSCORRUPTED;
break;
}
}
if (no < nrpages_out && strm->buf.out)
kunmap(rq->in[no]);
if (ni < nrpages_in)
kunmap(rq->in[ni]);
/* 4. push back LZMA stream context to the global list */
spin_lock(&z_erofs_lzma_lock);
strm->next = z_erofs_lzma_head;
z_erofs_lzma_head = strm;
spin_unlock(&z_erofs_lzma_lock);
wake_up(&z_erofs_lzma_wq);
return err;
}