diff options
Diffstat (limited to 'fs/erofs/decompressor_lzma.c')
| -rw-r--r-- | fs/erofs/decompressor_lzma.c | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/fs/erofs/decompressor_lzma.c b/fs/erofs/decompressor_lzma.c new file mode 100644 index 000000000000..091fd5adf818 --- /dev/null +++ b/fs/erofs/decompressor_lzma.c @@ -0,0 +1,291 @@ +// 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); + wake_up_all(&z_erofs_lzma_wq); + + 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 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); + err = z_erofs_fixup_insize(rq, kin + rq->pageofs_in, + min_t(unsigned int, rq->inputsize, + EROFS_BLKSIZ - rq->pageofs_in)); + if (err) { + kunmap(*rq->in); + return err; + } + + /* 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 + rq->pageofs_in; + strm->buf.in_pos = 0; + strm->buf.in_size = min_t(u32, inlen, PAGE_SIZE - rq->pageofs_in); + 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] && rq->fillgaps) /* deduped */ + rq->out[no] = erofs_allocpage(pagepool, + GFP_KERNEL | __GFP_NOFAIL); + 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; +} |