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-rw-r--r--fs/erofs/decompressor.c445
1 files changed, 445 insertions, 0 deletions
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
new file mode 100644
index 0000000000..d36b3963c0
--- /dev/null
+++ b/fs/erofs/decompressor.c
@@ -0,0 +1,445 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019 HUAWEI, Inc.
+ * https://www.huawei.com/
+ */
+#include "compress.h"
+#include <linux/module.h>
+#include <linux/lz4.h>
+
+#ifndef LZ4_DISTANCE_MAX /* history window size */
+#define LZ4_DISTANCE_MAX 65535 /* set to maximum value by default */
+#endif
+
+#define LZ4_MAX_DISTANCE_PAGES (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
+#ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
+#define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize) (((srcsize) >> 8) + 32)
+#endif
+
+struct z_erofs_lz4_decompress_ctx {
+ struct z_erofs_decompress_req *rq;
+ /* # of encoded, decoded pages */
+ unsigned int inpages, outpages;
+ /* decoded block total length (used for in-place decompression) */
+ unsigned int oend;
+};
+
+static int z_erofs_load_lz4_config(struct super_block *sb,
+ struct erofs_super_block *dsb, void *data, int size)
+{
+ struct erofs_sb_info *sbi = EROFS_SB(sb);
+ struct z_erofs_lz4_cfgs *lz4 = data;
+ u16 distance;
+
+ if (lz4) {
+ if (size < sizeof(struct z_erofs_lz4_cfgs)) {
+ erofs_err(sb, "invalid lz4 cfgs, size=%u", size);
+ return -EINVAL;
+ }
+ distance = le16_to_cpu(lz4->max_distance);
+
+ sbi->lz4.max_pclusterblks = le16_to_cpu(lz4->max_pclusterblks);
+ if (!sbi->lz4.max_pclusterblks) {
+ sbi->lz4.max_pclusterblks = 1; /* reserved case */
+ } else if (sbi->lz4.max_pclusterblks >
+ erofs_blknr(sb, Z_EROFS_PCLUSTER_MAX_SIZE)) {
+ erofs_err(sb, "too large lz4 pclusterblks %u",
+ sbi->lz4.max_pclusterblks);
+ return -EINVAL;
+ }
+ } else {
+ distance = le16_to_cpu(dsb->u1.lz4_max_distance);
+ sbi->lz4.max_pclusterblks = 1;
+ }
+
+ sbi->lz4.max_distance_pages = distance ?
+ DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
+ LZ4_MAX_DISTANCE_PAGES;
+ return erofs_pcpubuf_growsize(sbi->lz4.max_pclusterblks);
+}
+
+/*
+ * Fill all gaps with bounce pages if it's a sparse page list. Also check if
+ * all physical pages are consecutive, which can be seen for moderate CR.
+ */
+static int z_erofs_lz4_prepare_dstpages(struct z_erofs_lz4_decompress_ctx *ctx,
+ struct page **pagepool)
+{
+ struct z_erofs_decompress_req *rq = ctx->rq;
+ struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
+ unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
+ BITS_PER_LONG)] = { 0 };
+ unsigned int lz4_max_distance_pages =
+ EROFS_SB(rq->sb)->lz4.max_distance_pages;
+ void *kaddr = NULL;
+ unsigned int i, j, top;
+
+ top = 0;
+ for (i = j = 0; i < ctx->outpages; ++i, ++j) {
+ struct page *const page = rq->out[i];
+ struct page *victim;
+
+ if (j >= lz4_max_distance_pages)
+ j = 0;
+
+ /* 'valid' bounced can only be tested after a complete round */
+ if (!rq->fillgaps && test_bit(j, bounced)) {
+ DBG_BUGON(i < lz4_max_distance_pages);
+ DBG_BUGON(top >= lz4_max_distance_pages);
+ availables[top++] = rq->out[i - lz4_max_distance_pages];
+ }
+
+ if (page) {
+ __clear_bit(j, bounced);
+ if (!PageHighMem(page)) {
+ if (!i) {
+ kaddr = page_address(page);
+ continue;
+ }
+ if (kaddr &&
+ kaddr + PAGE_SIZE == page_address(page)) {
+ kaddr += PAGE_SIZE;
+ continue;
+ }
+ }
+ kaddr = NULL;
+ continue;
+ }
+ kaddr = NULL;
+ __set_bit(j, bounced);
+
+ if (top) {
+ victim = availables[--top];
+ get_page(victim);
+ } else {
+ victim = erofs_allocpage(pagepool,
+ GFP_KERNEL | __GFP_NOFAIL);
+ set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
+ }
+ rq->out[i] = victim;
+ }
+ return kaddr ? 1 : 0;
+}
+
+static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,
+ void *inpage, void *out, unsigned int *inputmargin,
+ int *maptype, bool may_inplace)
+{
+ struct z_erofs_decompress_req *rq = ctx->rq;
+ unsigned int omargin, total, i;
+ struct page **in;
+ void *src, *tmp;
+
+ if (rq->inplace_io) {
+ omargin = PAGE_ALIGN(ctx->oend) - ctx->oend;
+ if (rq->partial_decoding || !may_inplace ||
+ omargin < LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize))
+ goto docopy;
+
+ for (i = 0; i < ctx->inpages; ++i)
+ if (rq->out[ctx->outpages - ctx->inpages + i] !=
+ rq->in[i])
+ goto docopy;
+ kunmap_local(inpage);
+ *maptype = 3;
+ return out + ((ctx->outpages - ctx->inpages) << PAGE_SHIFT);
+ }
+
+ if (ctx->inpages <= 1) {
+ *maptype = 0;
+ return inpage;
+ }
+ kunmap_local(inpage);
+ src = erofs_vm_map_ram(rq->in, ctx->inpages);
+ if (!src)
+ return ERR_PTR(-ENOMEM);
+ *maptype = 1;
+ return src;
+
+docopy:
+ /* Or copy compressed data which can be overlapped to per-CPU buffer */
+ in = rq->in;
+ src = erofs_get_pcpubuf(ctx->inpages);
+ if (!src) {
+ DBG_BUGON(1);
+ kunmap_local(inpage);
+ return ERR_PTR(-EFAULT);
+ }
+
+ tmp = src;
+ total = rq->inputsize;
+ while (total) {
+ unsigned int page_copycnt =
+ min_t(unsigned int, total, PAGE_SIZE - *inputmargin);
+
+ if (!inpage)
+ inpage = kmap_local_page(*in);
+ memcpy(tmp, inpage + *inputmargin, page_copycnt);
+ kunmap_local(inpage);
+ inpage = NULL;
+ tmp += page_copycnt;
+ total -= page_copycnt;
+ ++in;
+ *inputmargin = 0;
+ }
+ *maptype = 2;
+ return src;
+}
+
+/*
+ * Get the exact inputsize with zero_padding feature.
+ * - For LZ4, it should work if zero_padding feature is on (5.3+);
+ * - For MicroLZMA, it'd be enabled all the time.
+ */
+int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
+ unsigned int padbufsize)
+{
+ const char *padend;
+
+ padend = memchr_inv(padbuf, 0, padbufsize);
+ if (!padend)
+ return -EFSCORRUPTED;
+ rq->inputsize -= padend - padbuf;
+ rq->pageofs_in += padend - padbuf;
+ return 0;
+}
+
+static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
+ u8 *dst)
+{
+ struct z_erofs_decompress_req *rq = ctx->rq;
+ bool support_0padding = false, may_inplace = false;
+ unsigned int inputmargin;
+ u8 *out, *headpage, *src;
+ int ret, maptype;
+
+ DBG_BUGON(*rq->in == NULL);
+ headpage = kmap_local_page(*rq->in);
+
+ /* LZ4 decompression inplace is only safe if zero_padding is enabled */
+ if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
+ support_0padding = true;
+ ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
+ min_t(unsigned int, rq->inputsize,
+ rq->sb->s_blocksize - rq->pageofs_in));
+ if (ret) {
+ kunmap_local(headpage);
+ return ret;
+ }
+ may_inplace = !((rq->pageofs_in + rq->inputsize) &
+ (rq->sb->s_blocksize - 1));
+ }
+
+ inputmargin = rq->pageofs_in;
+ src = z_erofs_lz4_handle_overlap(ctx, headpage, dst, &inputmargin,
+ &maptype, may_inplace);
+ if (IS_ERR(src))
+ return PTR_ERR(src);
+
+ out = dst + rq->pageofs_out;
+ /* legacy format could compress extra data in a pcluster. */
+ if (rq->partial_decoding || !support_0padding)
+ ret = LZ4_decompress_safe_partial(src + inputmargin, out,
+ rq->inputsize, rq->outputsize, rq->outputsize);
+ else
+ ret = LZ4_decompress_safe(src + inputmargin, out,
+ rq->inputsize, rq->outputsize);
+
+ if (ret != rq->outputsize) {
+ erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
+ ret, rq->inputsize, inputmargin, rq->outputsize);
+
+ print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
+ 16, 1, src + inputmargin, rq->inputsize, true);
+ print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
+ 16, 1, out, rq->outputsize, true);
+
+ if (ret >= 0)
+ memset(out + ret, 0, rq->outputsize - ret);
+ ret = -EIO;
+ } else {
+ ret = 0;
+ }
+
+ if (maptype == 0) {
+ kunmap_local(headpage);
+ } else if (maptype == 1) {
+ vm_unmap_ram(src, ctx->inpages);
+ } else if (maptype == 2) {
+ erofs_put_pcpubuf(src);
+ } else if (maptype != 3) {
+ DBG_BUGON(1);
+ return -EFAULT;
+ }
+ return ret;
+}
+
+static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
+ struct page **pagepool)
+{
+ struct z_erofs_lz4_decompress_ctx ctx;
+ unsigned int dst_maptype;
+ void *dst;
+ int ret;
+
+ ctx.rq = rq;
+ ctx.oend = rq->pageofs_out + rq->outputsize;
+ ctx.outpages = PAGE_ALIGN(ctx.oend) >> PAGE_SHIFT;
+ ctx.inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
+
+ /* one optimized fast path only for non bigpcluster cases yet */
+ if (ctx.inpages == 1 && ctx.outpages == 1 && !rq->inplace_io) {
+ DBG_BUGON(!*rq->out);
+ dst = kmap_local_page(*rq->out);
+ dst_maptype = 0;
+ goto dstmap_out;
+ }
+
+ /* general decoding path which can be used for all cases */
+ ret = z_erofs_lz4_prepare_dstpages(&ctx, pagepool);
+ if (ret < 0) {
+ return ret;
+ } else if (ret > 0) {
+ dst = page_address(*rq->out);
+ dst_maptype = 1;
+ } else {
+ dst = erofs_vm_map_ram(rq->out, ctx.outpages);
+ if (!dst)
+ return -ENOMEM;
+ dst_maptype = 2;
+ }
+
+dstmap_out:
+ ret = z_erofs_lz4_decompress_mem(&ctx, dst);
+ if (!dst_maptype)
+ kunmap_local(dst);
+ else if (dst_maptype == 2)
+ vm_unmap_ram(dst, ctx.outpages);
+ return ret;
+}
+
+static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
+ struct page **pagepool)
+{
+ const unsigned int inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
+ const unsigned int outpages =
+ PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
+ const unsigned int righthalf = min_t(unsigned int, rq->outputsize,
+ PAGE_SIZE - rq->pageofs_out);
+ const unsigned int lefthalf = rq->outputsize - righthalf;
+ const unsigned int interlaced_offset =
+ rq->alg == Z_EROFS_COMPRESSION_SHIFTED ? 0 : rq->pageofs_out;
+ u8 *src;
+
+ if (outpages > 2 && rq->alg == Z_EROFS_COMPRESSION_SHIFTED) {
+ DBG_BUGON(1);
+ return -EFSCORRUPTED;
+ }
+
+ if (rq->out[0] == *rq->in) {
+ DBG_BUGON(rq->pageofs_out);
+ return 0;
+ }
+
+ src = kmap_local_page(rq->in[inpages - 1]) + rq->pageofs_in;
+ if (rq->out[0])
+ memcpy_to_page(rq->out[0], rq->pageofs_out,
+ src + interlaced_offset, righthalf);
+
+ if (outpages > inpages) {
+ DBG_BUGON(!rq->out[outpages - 1]);
+ if (rq->out[outpages - 1] != rq->in[inpages - 1]) {
+ memcpy_to_page(rq->out[outpages - 1], 0, src +
+ (interlaced_offset ? 0 : righthalf),
+ lefthalf);
+ } else if (!interlaced_offset) {
+ memmove(src, src + righthalf, lefthalf);
+ flush_dcache_page(rq->in[inpages - 1]);
+ }
+ }
+ kunmap_local(src);
+ return 0;
+}
+
+const struct z_erofs_decompressor erofs_decompressors[] = {
+ [Z_EROFS_COMPRESSION_SHIFTED] = {
+ .decompress = z_erofs_transform_plain,
+ .name = "shifted"
+ },
+ [Z_EROFS_COMPRESSION_INTERLACED] = {
+ .decompress = z_erofs_transform_plain,
+ .name = "interlaced"
+ },
+ [Z_EROFS_COMPRESSION_LZ4] = {
+ .config = z_erofs_load_lz4_config,
+ .decompress = z_erofs_lz4_decompress,
+ .name = "lz4"
+ },
+#ifdef CONFIG_EROFS_FS_ZIP_LZMA
+ [Z_EROFS_COMPRESSION_LZMA] = {
+ .config = z_erofs_load_lzma_config,
+ .decompress = z_erofs_lzma_decompress,
+ .name = "lzma"
+ },
+#endif
+#ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
+ [Z_EROFS_COMPRESSION_DEFLATE] = {
+ .config = z_erofs_load_deflate_config,
+ .decompress = z_erofs_deflate_decompress,
+ .name = "deflate"
+ },
+#endif
+};
+
+int z_erofs_parse_cfgs(struct super_block *sb, struct erofs_super_block *dsb)
+{
+ struct erofs_sb_info *sbi = EROFS_SB(sb);
+ struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
+ unsigned int algs, alg;
+ erofs_off_t offset;
+ int size, ret = 0;
+
+ if (!erofs_sb_has_compr_cfgs(sbi)) {
+ sbi->available_compr_algs = 1 << Z_EROFS_COMPRESSION_LZ4;
+ return z_erofs_load_lz4_config(sb, dsb, NULL, 0);
+ }
+
+ sbi->available_compr_algs = le16_to_cpu(dsb->u1.available_compr_algs);
+ if (sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS) {
+ erofs_err(sb, "unidentified algorithms %x, please upgrade kernel",
+ sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS);
+ return -EOPNOTSUPP;
+ }
+
+ erofs_init_metabuf(&buf, sb);
+ offset = EROFS_SUPER_OFFSET + sbi->sb_size;
+ alg = 0;
+ for (algs = sbi->available_compr_algs; algs; algs >>= 1, ++alg) {
+ void *data;
+
+ if (!(algs & 1))
+ continue;
+
+ data = erofs_read_metadata(sb, &buf, &offset, &size);
+ if (IS_ERR(data)) {
+ ret = PTR_ERR(data);
+ break;
+ }
+
+ if (alg >= ARRAY_SIZE(erofs_decompressors) ||
+ !erofs_decompressors[alg].config) {
+ erofs_err(sb, "algorithm %d isn't enabled on this kernel",
+ alg);
+ ret = -EOPNOTSUPP;
+ } else {
+ ret = erofs_decompressors[alg].config(sb,
+ dsb, data, size);
+ }
+
+ kfree(data);
+ if (ret)
+ break;
+ }
+ erofs_put_metabuf(&buf);
+ return ret;
+}
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