Updated the lz4 decompressor

As an experiment, I stole the lz4 decompressor from
upstream lz4 (1.9.3), and landed it.

Feedback suggested that keeping the vendor lz4 code isolated and
unlinted was probably reasonable, so I lobbed it into its own file.

It also seemed reasonable to put the mostly-untouched* code into
lz4.c proper, and relegate the integrated and ZFS-specific code to
lz4_zfs.c.

Reviewed-by: Matthew Ahrens <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Rich Ercolani <[email protected]>
Closes openzfs#12805

Makefile.am

@@ -126,6 +126,7 @@ cstyle:
 		! -name 'zfs_config.*' ! -name '*.mod.c' \
 		! -name 'opt_global.h' ! -name '*_if*.h' \
 		! -path './module/zstd/lib/*' \
+		! -path './module/zfs/lz4.c' \
 		$(cstyle_line)
 
 filter_executable = -exec test -x '{}' \; -print

config/ax_code_coverage.m4

@@ -224,6 +224,7 @@ CODE_COVERAGE_GENHTML_OPTIONS ?= $(CODE_COVERAGE_GENHTML_OPTIONS_DEFAULT)
 # Ignore tmp and tests themselves
 CODE_COVERAGE_IGNORE_PATTERN ?= "/tmp/*" "*/tests/*"
 CODE_COVERAGE_IGNORE_PATTERN += "*/module/zstd/lib/*"
+CODE_COVERAGE_IGNORE_PATTERN += "*/module/zfs/lz4.c"
 
 GITIGNOREFILES ?=
 GITIGNOREFILES += $(CODE_COVERAGE_OUTPUT_FILE) $(CODE_COVERAGE_OUTPUT_DIRECTORY)

lib/libzpool/Makefile.am

@@ -94,6 +94,7 @@ KERNEL_C = \
 	gzip.c \
 	hkdf.c \
 	lz4.c \
+	lz4_zfs.c \
 	lzjb.c \
 	metaslab.c \
 	mmp.c \

module/Makefile.bsd

@@ -228,6 +228,7 @@ SRCS+=	abd.c \
 	gzip.c \
 	lzjb.c \
 	lz4.c \
+	lz4_zfs.c \
 	metaslab.c \
 	mmp.c \
 	multilist.c \
@@ -352,7 +353,7 @@ CFLAGS.dsl_deadlist.c= -Wno-cast-qual
 CFLAGS.dsl_prop.c= -Wno-cast-qual
 CFLAGS.edonr.c=-Wno-cast-qual
 CFLAGS.fm.c= -Wno-cast-qual
-CFLAGS.lz4.c= -Wno-cast-qual
+CFLAGS.lz4_zfs.c= -Wno-cast-qual
 CFLAGS.spa.c= -Wno-cast-qual
 CFLAGS.spa_misc.c= -Wno-cast-qual
 CFLAGS.sysctl_os.c= -include ../zfs_config.h

module/zfs/Makefile.in

@@ -56,6 +56,7 @@ $(MODULE)-objs += fm.o
 $(MODULE)-objs += gzip.o
 $(MODULE)-objs += hkdf.o
 $(MODULE)-objs += lz4.o
+$(MODULE)-objs += lz4_zfs.o
 $(MODULE)-objs += lzjb.o
 $(MODULE)-objs += metaslab.o
 $(MODULE)-objs += mmp.o