erofs: DEFLATE compression support

Add DEFLATE compression as the 3rd supported algorithm.

DEFLATE is a popular generic-purpose compression algorithm for quite
long time (many advanced formats like gzip, zlib, zip, png are all
based on that) as Apple documentation written "If you require
interoperability with non-Apple devices, use COMPRESSION_ZLIB. [1]".

Due to its popularity, there are several hardware on-market DEFLATE
accelerators, such as (s390) DFLTCC, (Intel) IAA/QAT, (HiSilicon) ZIP
accelerator, etc.  In addition, there are also several high-performence
IP cores and even open-source FPGA approches available for DEFLATE.
Therefore, it's useful to support DEFLATE compression in order to find
a way to utilize these accelerators for asynchronous I/Os and get
benefits from these later.

Besides, it's a good choice to trade off between compression ratios
and performance compared to LZ4 and LZMA.  The DEFLATE core format is
simple as well as easy to understand, therefore the code size of its
decompressor is small even for the bootloader use cases.  The runtime
memory consumption is quite limited too (e.g. 32K + ~7K for each zlib
stream).  As usual, EROFS ourperforms similar approaches too.

Alternatively, DEFLATE could still be used for some specific files
since EROFS supports multiple compression algorithms in one image.

[1] https://developer.apple.com/documentation/compression/compression_algorithm
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230810154859.118330-1-hsiangkao@linux.alibaba.com

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index cfad1eac7fd9..332ec5f74002 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -379,4 +379,10 @@ const struct z_erofs_decompressor erofs_decompressors[] = {
 		.name = "lzma"
 	},
 #endif
+#ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
+	[Z_EROFS_COMPRESSION_DEFLATE] = {
+		.decompress = z_erofs_deflate_decompress,
+		.name = "deflate"
+	},
+#endif
 };