This patch adds LZMA compression algorithm support to erofs-utils
compression framework with upstream liblzma.

Cc: Lasse Collin <[email protected]>
Signed-off-by: Gao Xiang <[email protected]>
---
 include/erofs/config.h   |   1 +
 include/erofs_fs.h       |   6 +++
 lib/Makefile.am          |   3 ++
 lib/compress.c           |  37 ++++++++++++--
 lib/compressor.c         |   3 ++
 lib/compressor.h         |   1 +
 lib/compressor_liblzma.c | 105 +++++++++++++++++++++++++++++++++++++++
 mkfs/main.c              |   1 -
 8 files changed, 152 insertions(+), 5 deletions(-)
 create mode 100644 lib/compressor_liblzma.c

diff --git a/include/erofs/config.h b/include/erofs/config.h
index 574dd52be12d..a18c88301279 100644
--- a/include/erofs/config.h
+++ b/include/erofs/config.h
@@ -60,6 +60,7 @@ struct erofs_configure {
 
        u32 c_pclusterblks_max, c_pclusterblks_def;
        u32 c_max_decompressed_extent_bytes;
+       u32 c_dict_size;
        u64 c_unix_timestamp;
        u32 c_uid, c_gid;
 #ifdef WITH_ANDROID
diff --git a/include/erofs_fs.h b/include/erofs_fs.h
index 86ad6f5fd86c..4291970753a8 100644
--- a/include/erofs_fs.h
+++ b/include/erofs_fs.h
@@ -261,6 +261,12 @@ struct z_erofs_lz4_cfgs {
        u8 reserved[10];
 } __packed;
 
+/* 14 bytes (+ length field = 16 bytes) */
+struct z_erofs_lzma_cfgs {
+       __le32 dict_size;
+       __le16 format;
+       u8 reserved[8];
+} __packed;
 #define Z_EROFS_LZMA_MAX_DICT_SIZE     (8 * Z_EROFS_PCLUSTER_MAX_SIZE)
 
 /*
diff --git a/lib/Makefile.am b/lib/Makefile.am
index 370de844146f..58ad192c51b3 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -31,4 +31,7 @@ if ENABLE_LZ4HC
 liberofs_la_SOURCES += compressor_lz4hc.c
 endif
 endif
+if ENABLE_LIBLZMA
 liberofs_la_CFLAGS += ${liblzma_CFLAGS}
+liberofs_la_SOURCES += compressor_liblzma.c
+endif
diff --git a/lib/compress.c b/lib/compress.c
index 6ca5bedaf596..98be7a26383b 100644
--- a/lib/compress.c
+++ b/lib/compress.c
@@ -588,6 +588,8 @@ static int erofs_get_compress_algorithm_id(const char *name)
 {
        if (!strcmp(name, "lz4") || !strcmp(name, "lz4hc"))
                return Z_EROFS_COMPRESSION_LZ4;
+       if (!strcmp(name, "lzma"))
+               return Z_EROFS_COMPRESSION_LZMA;
        return -ENOTSUP;
 }
 
@@ -619,6 +621,29 @@ int z_erofs_build_compr_cfgs(struct erofs_buffer_head 
*sb_bh)
                                sizeof(lz4alg));
                bh->op = &erofs_drop_directly_bhops;
        }
+#ifdef HAVE_LIBLZMA
+       if (sbi.available_compr_algs & (1 << Z_EROFS_COMPRESSION_LZMA)) {
+               struct {
+                       __le16 size;
+                       struct z_erofs_lzma_cfgs lzma;
+               } __packed lzmaalg = {
+                       .size = cpu_to_le16(sizeof(struct z_erofs_lzma_cfgs)),
+                       .lzma = {
+                               .dict_size = cpu_to_le32(cfg.c_dict_size),
+                       }
+               };
+
+               bh = erofs_battach(bh, META, sizeof(lzmaalg));
+               if (IS_ERR(bh)) {
+                       DBG_BUGON(1);
+                       return PTR_ERR(bh);
+               }
+               erofs_mapbh(bh->block);
+               ret = dev_write(&lzmaalg, erofs_btell(bh, false),
+                               sizeof(lzmaalg));
+               bh->op = &erofs_drop_directly_bhops;
+       }
+#endif
        return ret;
 }
 
@@ -632,17 +657,18 @@ int z_erofs_compress_init(struct erofs_buffer_head *sb_bh)
                return ret;
 
        /*
-        * if primary algorithm is not lz4* (e.g. compression off),
-        * clear LZ4_0PADDING feature for old kernel compatibility.
+        * if primary algorithm is empty (e.g. compression off),
+        * clear 0PADDING feature for old kernel compatibility.
         */
        if (!cfg.c_compr_alg_master ||
-           strncmp(cfg.c_compr_alg_master, "lz4", 3))
+           (cfg.c_legacy_compress && !strcmp(cfg.c_compr_alg_master, "lz4")))
                erofs_sb_clear_lz4_0padding();
 
        if (!cfg.c_compr_alg_master)
                return 0;
 
-       ret = erofs_compressor_setlevel(&compresshandle, 
cfg.c_compr_level_master);
+       ret = erofs_compressor_setlevel(&compresshandle,
+                                       cfg.c_compr_level_master);
        if (ret)
                return ret;
 
@@ -668,6 +694,9 @@ int z_erofs_compress_init(struct erofs_buffer_head *sb_bh)
                erofs_warn("EXPERIMENTAL big pcluster feature in use. Use at 
your own risk!");
        }
 
+       if (ret != Z_EROFS_COMPRESSION_LZ4)
+               erofs_sb_set_compr_cfgs();
+
        if (erofs_sb_has_compr_cfgs()) {
                sbi.available_compr_algs |= 1 << ret;
                return z_erofs_build_compr_cfgs(sb_bh);
diff --git a/lib/compressor.c b/lib/compressor.c
index 89c1be10dd0c..ad12cdf2ceed 100644
--- a/lib/compressor.c
+++ b/lib/compressor.c
@@ -17,6 +17,9 @@ static struct erofs_compressor *compressors[] = {
 #endif
                &erofs_compressor_lz4,
 #endif
+#if HAVE_LIBLZMA
+               &erofs_compressor_lzma,
+#endif
 };
 
 int erofs_compress_destsize(struct erofs_compress *c,
diff --git a/lib/compressor.h b/lib/compressor.h
index d1b43c87291f..aa85ae0bdc2f 100644
--- a/lib/compressor.h
+++ b/lib/compressor.h
@@ -43,6 +43,7 @@ struct erofs_compress {
 /* list of compression algorithms */
 extern struct erofs_compressor erofs_compressor_lz4;
 extern struct erofs_compressor erofs_compressor_lz4hc;
+extern struct erofs_compressor erofs_compressor_lzma;
 
 int erofs_compress_destsize(struct erofs_compress *c,
                            void *src, unsigned int *srcsize,
diff --git a/lib/compressor_liblzma.c b/lib/compressor_liblzma.c
new file mode 100644
index 000000000000..e9bfcc556c54
--- /dev/null
+++ b/lib/compressor_liblzma.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * erofs-utils/lib/compressor_liblzma.c
+ *
+ * Copyright (C) 2021 Gao Xiang <[email protected]>
+ */
+#include <stdlib.h>
+#include <lzma.h>
+#include "erofs/config.h"
+#include "erofs/print.h"
+#include "erofs/internal.h"
+#include "compressor.h"
+
+struct erofs_liblzma_context {
+       lzma_options_lzma opt;
+       lzma_stream strm;
+};
+
+static int erofs_liblzma_compress_destsize(struct erofs_compress *c,
+                                          void *src, unsigned int *srcsize,
+                                          void *dst, unsigned int dstsize)
+{
+       struct erofs_liblzma_context *ctx = c->private_data;
+       lzma_stream *strm = &ctx->strm;
+
+       lzma_ret ret = lzma_microlzma_encoder(strm, &ctx->opt);
+       if (ret != LZMA_OK)
+               return -EFAULT;
+
+       strm->next_in = src;
+       strm->avail_in = *srcsize;
+       strm->next_out = dst;
+       strm->avail_out = dstsize;
+
+       ret = lzma_code(strm, LZMA_FINISH);
+       if (ret != LZMA_STREAM_END)
+               return -EBADMSG;
+
+       *srcsize = strm->total_in;
+       return strm->total_out;
+}
+
+static int erofs_compressor_liblzma_exit(struct erofs_compress *c)
+{
+       struct erofs_liblzma_context *ctx = c->private_data;
+
+       if (!ctx)
+               return -EINVAL;
+
+       lzma_end(&ctx->strm);
+       free(ctx);
+       return 0;
+}
+
+static int erofs_compressor_liblzma_setlevel(struct erofs_compress *c,
+                                            int compression_level)
+{
+       struct erofs_liblzma_context *ctx = c->private_data;
+
+       if (compression_level < 0)
+               compression_level = LZMA_PRESET_DEFAULT;
+
+       if (lzma_lzma_preset(&ctx->opt, compression_level))
+               return -EINVAL;
+
+       /* XXX: temporary hack */
+       if (cfg.c_dict_size) {
+               if (cfg.c_dict_size > Z_EROFS_LZMA_MAX_DICT_SIZE) {
+                       erofs_err("dict size %u is too large", cfg.c_dict_size);
+                       return -EINVAL;
+               }
+               ctx->opt.dict_size = cfg.c_dict_size;
+       } else {
+               if (ctx->opt.dict_size > Z_EROFS_LZMA_MAX_DICT_SIZE)
+                       ctx->opt.dict_size = Z_EROFS_LZMA_MAX_DICT_SIZE;
+               cfg.c_dict_size = ctx->opt.dict_size;
+       }
+       c->compression_level = compression_level;
+       return 0;
+}
+
+static int erofs_compressor_liblzma_init(struct erofs_compress *c)
+{
+       struct erofs_liblzma_context *ctx;
+
+       c->alg = &erofs_compressor_lzma;
+       ctx = malloc(sizeof(*ctx));
+       if (!ctx)
+               return -ENOMEM;
+       ctx->strm = (lzma_stream)LZMA_STREAM_INIT;
+       c->private_data = ctx;
+       erofs_warn("EXPERIMENTAL MicroLZMA feature in use. Use at your own 
risk!");
+       erofs_warn("Note that it may take more time since the compressor is 
still single-threaded for now.");
+       return 0;
+}
+
+struct erofs_compressor erofs_compressor_lzma = {
+       .name = "lzma",
+       .default_level = LZMA_PRESET_DEFAULT,
+       .best_level = LZMA_PRESET_EXTREME,
+       .init = erofs_compressor_liblzma_init,
+       .exit = erofs_compressor_liblzma_exit,
+       .setlevel = erofs_compressor_liblzma_setlevel,
+       .compress_destsize = erofs_liblzma_compress_destsize,
+};
diff --git a/mkfs/main.c b/mkfs/main.c
index 055d077988e9..028cf5a8911c 100644
--- a/mkfs/main.c
+++ b/mkfs/main.c
@@ -147,7 +147,6 @@ static int parse_extended_opts(const char *opts)
                                return -EINVAL;
                        /* disable compacted indexes and 0padding */
                        cfg.c_legacy_compress = true;
-                       erofs_sb_clear_lz4_0padding();
                }
 
                if (MATCH_EXTENTED_OPT("force-inode-compact", token, keylen)) {
-- 
2.20.1

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