[linux] Write all the patch summaries

contrib/linux-kernel/0001-lib-Add-xxhash-module.patch

@@ -1,6 +1,6 @@
-From 36b990a005e68a30495e2b2981e30c5ce97a8591 Mon Sep 17 00:00:00 2001
+From e75beb7c2e05550b2846e31ad8a0082c188504da Mon Sep 17 00:00:00 2001
 From: Nick Terrell <terrelln@fb.com>
-Date: Mon, 12 Jun 2017 12:13:48 -0700
+Date: Wed, 21 Jun 2017 17:27:42 -0700
 Subject: [PATCH 1/4] lib: Add xxhash module
 
 Adds xxhash kernel module with xxh32 and xxh64 hashes. xxhash is an
@@ -324,10 +324,10 @@ index 0000000..9e1f42c
 +
 +#endif /* XXHASH_H */
 diff --git a/lib/Kconfig b/lib/Kconfig
-index 260a80e..9db178f 100644
+index 0c8b78a..b6009d7 100644
 --- a/lib/Kconfig
 +++ b/lib/Kconfig
-@@ -185,6 +185,9 @@ config CRC8
+@@ -184,6 +184,9 @@ config CRC8
  	  when they need to do cyclic redundancy check according CRC8
  	  algorithm. Module will be called crc8.
  
@@ -338,10 +338,10 @@ index 260a80e..9db178f 100644
  	bool
  	depends on AUDIT && !AUDIT_ARCH
 diff --git a/lib/Makefile b/lib/Makefile
-index 50144a3..5644bad 100644
+index 0166fbc..1338226 100644
 --- a/lib/Makefile
 +++ b/lib/Makefile
-@@ -93,6 +93,7 @@ obj-$(CONFIG_CRC32)	+= crc32.o
+@@ -102,6 +102,7 @@ obj-$(CONFIG_CRC32_SELFTEST)	+= crc32test.o
  obj-$(CONFIG_CRC7)	+= crc7.o
  obj-$(CONFIG_LIBCRC32C)	+= libcrc32c.o
  obj-$(CONFIG_CRC8)	+= crc8.o

contrib/linux-kernel/0002-lib-Add-zstd-modules.patch

@@ -1,6 +1,6 @@
-From 536a2c59c5bc58f526e69dd0a35b83d39508ae74 Mon Sep 17 00:00:00 2001
+From b52ae824ae6c0f7c7786380b34da9daaa54bfc26 Mon Sep 17 00:00:00 2001
 From: Nick Terrell <terrelln@fb.com>
-Date: Wed, 21 Jun 2017 14:56:21 -0700
+Date: Wed, 21 Jun 2017 17:31:24 -0700
 Subject: [PATCH 2/4] lib: Add zstd modules
 
 Add zstd compression and decompression kernel modules.
@@ -1304,10 +1304,10 @@ index 0000000..249575e
 +
 +#endif  /* ZSTD_H */
 diff --git a/lib/Kconfig b/lib/Kconfig
-index 9db178f..8deab4f 100644
+index b6009d7..f00ddab 100644
 --- a/lib/Kconfig
 +++ b/lib/Kconfig
-@@ -242,6 +242,14 @@ config LZ4HC_COMPRESS
+@@ -241,6 +241,14 @@ config LZ4HC_COMPRESS
  config LZ4_DECOMPRESS
  	tristate
 
@@ -1323,10 +1323,10 @@ index 9db178f..8deab4f 100644
 
  #
 diff --git a/lib/Makefile b/lib/Makefile
-index 5644bad..aa630d4 100644
+index 1338226..4fcef16 100644
 --- a/lib/Makefile
 +++ b/lib/Makefile
-@@ -107,6 +107,8 @@ obj-$(CONFIG_LZO_DECOMPRESS) += lzo/
+@@ -116,6 +116,8 @@ obj-$(CONFIG_LZO_DECOMPRESS) += lzo/
  obj-$(CONFIG_LZ4_COMPRESS) += lz4/
  obj-$(CONFIG_LZ4HC_COMPRESS) += lz4/
  obj-$(CONFIG_LZ4_DECOMPRESS) += lz4/

contrib/linux-kernel/0003-btrfs-Add-zstd-support.patch

@@ -1,3 +1,83 @@
+From 599f8f2aaace3df939cb145368574a52268d82d0 Mon Sep 17 00:00:00 2001
+From: Nick Terrell <terrelln@fb.com>
+Date: Wed, 21 Jun 2017 17:31:39 -0700
+Subject: [PATCH 3/4] btrfs: Add zstd support
+
+Add zstd compression and decompression support to BtrFS. zstd at its
+fastest level compresses almost as well as zlib, while offering much
+faster compression and decompression, approaching lzo speeds.
+
+I benchmarked btrfs with zstd compression against no compression, lzo
+compression, and zlib compression. I benchmarked two scenarios. Copying
+a set of files to btrfs, and then reading the files. Copying a tarball
+to btrfs, extracting it to btrfs, and then reading the extracted files.
+After every operation, I call `sync` and include the sync time.
+Between every pair of operations I unmount and remount the filesystem
+to avoid caching. The benchmark files can be found in the upstream
+zstd source repository under
+`contrib/linux-kernel/{btrfs-benchmark.sh,btrfs-extract-benchmark.sh}`
+[1] [2].
+
+I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM.
+The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor,
+16 GB of RAM, and a SSD.
+
+The first compression benchmark is copying 10 copies of the unzipped
+Silesia corpus [3] into a BtrFS filesystem mounted with
+`-o compress-force=Method`. The decompression benchmark times how long
+it takes to `tar` all 10 copies into `/dev/null`. The compression ratio is
+measured by comparing the output of `df` and `du`. See the benchmark file
+[1] for details. I benchmarked multiple zstd compression levels, although
+the patch uses zstd level 1.
+
+| Method  | Ratio | Compression MB/s | Decompression speed |
+|---------|-------|------------------|---------------------|
+| None    |  0.99 |              504 |                 686 |
+| lzo     |  1.66 |              398 |                 442 |
+| zlib    |  2.58 |               65 |                 241 |
+| zstd 1  |  2.57 |              260 |                 383 |
+| zstd 3  |  2.71 |              174 |                 408 |
+| zstd 6  |  2.87 |               70 |                 398 |
+| zstd 9  |  2.92 |               43 |                 406 |
+| zstd 12 |  2.93 |               21 |                 408 |
+| zstd 15 |  3.01 |               11 |                 354 |
+
+The next benchmark first copies `linux-4.11.6.tar` [4] to btrfs. Then it
+measures the compression ratio, extracts the tar, and deletes the tar.
+Then it measures the compression ratio again, and `tar`s the extracted
+files into `/dev/null`. See the benchmark file [2] for details.
+
+| Method | Tar Ratio | Extract Ratio | Copy (s) | Extract (s)| Read (s) |
+|--------|-----------|---------------|----------|------------|----------|
+| None   |      0.97 |          0.78 |    0.981 |      5.501 |    8.807 |
+| lzo    |      2.06 |          1.38 |    1.631 |      8.458 |    8.585 |
+| zlib   |      3.40 |          1.86 |    7.750 |     21.544 |   11.744 |
+| zstd 1 |      3.57 |          1.85 |    2.579 |     11.479 |    9.389 |
+
+[1] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/btrfs-benchmark.sh
+[2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/btrfs-extract-benchmark.sh
+[3] http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia
+[4] https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.11.6.tar.xz
+
+zstd source repository: https://github.com/facebook/zstd
+
+Signed-off-by: Nick Terrell <terrelln@fb.com>
+---
+ fs/btrfs/Kconfig           |   2 +
+ fs/btrfs/Makefile          |   2 +-
+ fs/btrfs/compression.c     |   1 +
+ fs/btrfs/compression.h     |   6 +-
+ fs/btrfs/ctree.h           |   1 +
+ fs/btrfs/disk-io.c         |   2 +
+ fs/btrfs/ioctl.c           |   6 +-
+ fs/btrfs/props.c           |   6 +
+ fs/btrfs/super.c           |  12 +-
+ fs/btrfs/sysfs.c           |   2 +
+ fs/btrfs/zstd.c            | 433 +++++++++++++++++++++++++++++++++++++++++++++
+ include/uapi/linux/btrfs.h |   8 +-
+ 12 files changed, 469 insertions(+), 12 deletions(-)
+ create mode 100644 fs/btrfs/zstd.c
+
 diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
 index 80e9c18..a26c63b 100644
 --- a/fs/btrfs/Kconfig
@@ -25,7 +105,7 @@ index 128ce17..962a95a 100644
  	   reada.o backref.o ulist.o qgroup.o send.o dev-replace.o raid56.o \
  	   uuid-tree.o props.o hash.o free-space-tree.o
 diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
-index c7721a6..66d4ced 100644
+index 10e6b28..3beb0d0 100644
 --- a/fs/btrfs/compression.c
 +++ b/fs/btrfs/compression.c
 @@ -761,6 +761,7 @@ static struct {
@@ -34,7 +114,7 @@ index c7721a6..66d4ced 100644
  	&btrfs_lzo_compress,
 +	&btrfs_zstd_compress,
  };
- 
+
  void __init btrfs_init_compress(void)
 diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
 index 39ec43a..d99fc21 100644
@@ -50,20 +130,20 @@ index 39ec43a..d99fc21 100644
 +	BTRFS_COMPRESS_TYPES = 3,
 +	BTRFS_COMPRESS_LAST  = 4,
  };
- 
+
  struct btrfs_compress_op {
 @@ -92,5 +93,6 @@ struct btrfs_compress_op {
- 
+
  extern const struct btrfs_compress_op btrfs_zlib_compress;
  extern const struct btrfs_compress_op btrfs_lzo_compress;
 +extern const struct btrfs_compress_op btrfs_zstd_compress;
- 
+
  #endif
 diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
-index 29b7fc2..878b23b9 100644
+index 4f8f75d..61dd3dd 100644
 --- a/fs/btrfs/ctree.h
 +++ b/fs/btrfs/ctree.h
-@@ -270,6 +270,7 @@ struct btrfs_super_block {
+@@ -271,6 +271,7 @@ struct btrfs_super_block {
  	 BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS |		\
  	 BTRFS_FEATURE_INCOMPAT_BIG_METADATA |		\
  	 BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO |		\
@@ -72,24 +152,24 @@ index 29b7fc2..878b23b9 100644
  	 BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF |		\
  	 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA |	\
 diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
-index 08b74da..0c43e4e 100644
+index 5f678dc..49c0e91 100644
 --- a/fs/btrfs/disk-io.c
 +++ b/fs/btrfs/disk-io.c
-@@ -2853,6 +2853,8 @@ int open_ctree(struct super_block *sb,
+@@ -2831,6 +2831,8 @@ int open_ctree(struct super_block *sb,
  	features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
  	if (fs_info->compress_type == BTRFS_COMPRESS_LZO)
  		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO;
-+	else if (tree_root->fs_info->compress_type == BTRFS_COMPRESS_ZSTD)
++	else if (fs_info->compress_type == BTRFS_COMPRESS_ZSTD)
 +		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD;
- 
+
  	if (features & BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)
  		btrfs_info(fs_info, "has skinny extents");
 diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
-index dabfc7a..d8ea727 100644
+index e176375..f732cfd 100644
 --- a/fs/btrfs/ioctl.c
 +++ b/fs/btrfs/ioctl.c
 @@ -327,8 +327,10 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
- 
+
  		if (fs_info->compress_type == BTRFS_COMPRESS_LZO)
  			comp = "lzo";
 -		else
@@ -101,13 +181,13 @@ index dabfc7a..d8ea727 100644
  				     comp, strlen(comp), 0);
  		if (ret)
 @@ -1463,6 +1465,8 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
- 
+
  	if (range->compress_type == BTRFS_COMPRESS_LZO) {
  		btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
 +	} else if (range->compress_type == BTRFS_COMPRESS_ZSTD) {
 +		btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
  	}
- 
+
  	ret = defrag_count;
 diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
 index d6cb155..162105f 100644
@@ -119,7 +199,7 @@ index d6cb155..162105f 100644
  		return 0;
 +	else if (!strncmp("zstd", value, len))
 +		return 0;
- 
+
  	return -EINVAL;
  }
 @@ -405,6 +407,8 @@ static int prop_compression_apply(struct inode *inode,
@@ -130,7 +210,7 @@ index d6cb155..162105f 100644
 +		type = BTRFS_COMPRESS_ZSTD;
  	else
  		return -EINVAL;
- 
+
 @@ -422,6 +426,8 @@ static const char *prop_compression_extract(struct inode *inode)
  		return "zlib";
  	case BTRFS_COMPRESS_LZO:
@@ -138,10 +218,10 @@ index d6cb155..162105f 100644
 +	case BTRFS_COMPRESS_ZSTD:
 +		return "zstd";
  	}
- 
+
  	return NULL;
 diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
-index da687dc..b064456 100644
+index 4f1cdd5..4f792d5 100644
 --- a/fs/btrfs/super.c
 +++ b/fs/btrfs/super.c
 @@ -513,6 +513,14 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
@@ -159,7 +239,7 @@ index da687dc..b064456 100644
  			} else if (strncmp(args[0].from, "no", 2) == 0) {
  				compress_type = "no";
  				btrfs_clear_opt(info->mount_opt, COMPRESS);
-@@ -1230,8 +1238,10 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
+@@ -1240,8 +1248,10 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
  	if (btrfs_test_opt(info, COMPRESS)) {
  		if (info->compress_type == BTRFS_COMPRESS_ZLIB)
  			compress_type = "zlib";
@@ -631,7 +711,7 @@ index 0000000..838741b
 +	.decompress = zstd_decompress,
 +};
 diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
-index db4c253..f26c34f 100644
+index a456e53..992c150 100644
 --- a/include/uapi/linux/btrfs.h
 +++ b/include/uapi/linux/btrfs.h
 @@ -255,13 +255,7 @@ struct btrfs_ioctl_fs_info_args {
@@ -646,6 +726,8 @@ index db4c253..f26c34f 100644
 - */
 -#define BTRFS_FEATURE_INCOMPAT_COMPRESS_LZOv2	(1ULL << 4)
 +#define BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD	(1ULL << 4)
- 
+
  /*
   * older kernels tried to do bigger metadata blocks, but the
+--
+2.9.3

contrib/linux-kernel/0004-squashfs-Add-zstd-support.patch

@@ -1,11 +1,67 @@
+From 5ff6a64abaea7b7f11d37cb0fdf08642316a3a90 Mon Sep 17 00:00:00 2001
+From: Nick Terrell <terrelln@fb.com>
+Date: Mon, 12 Jun 2017 12:18:23 -0700
+Subject: [PATCH 4/4] squashfs: Add zstd support
+
+Add zstd compression and decompression support to SquashFS. zstd is a
+great fit for SquashFS because it can compress at ratios approaching xz,
+while decompressing twice as fast as zlib. For SquashFS in particular,
+it can decompress as fast as lzo and lz4. It also has the flexibility
+to turn down the compression ratio for faster compression times.
+
+The compression benchmark is run on the file tree from the SquashFS archive
+found in ubuntu-16.10-desktop-amd64.iso [1]. It uses `mksquashfs` with the
+default block size (128 KB) and and various compression algorithms/levels.
+xz and zstd are also benchmarked with 256 KB blocks. The decompression
+benchmark times how long it takes to `tar` the file tree into `/dev/null`.
+See the benchmark file in the upstream zstd source repository located under
+`contrib/linux-kernel/squashfs-benchmark.sh` [2] for details.
+
+I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM.
+The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor,
+16 GB of RAM, and a SSD.
+
+| Method         | Ratio | Compression MB/s | Decompression MB/s |
+|----------------|-------|------------------|--------------------|
+| gzip           |  2.92 |               15 |                128 |
+| lzo            |  2.64 |              9.5 |                217 |
+| lz4            |  2.12 |               94 |                218 |
+| xz             |  3.43 |              5.5 |                 35 |
+| xz 256 KB      |  3.53 |              5.4 |                 40 |
+| zstd 1         |  2.71 |               96 |                210 |
+| zstd 5         |  2.93 |               69 |                198 |
+| zstd 10        |  3.01 |               41 |                225 |
+| zstd 15        |  3.13 |             11.4 |                224 |
+| zstd 16 256 KB |  3.24 |              8.1 |                210 |
+
+This patch was written by Sean Purcell <me@seanp.xyz>, but I will be
+taking over the submission process.
+
+[1] http://releases.ubuntu.com/16.10/
+[2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/squashfs-benchmark.sh
+
+zstd source repository: https://github.com/facebook/zstd
+
+Cc: Sean Purcell <me@seanp.xyz>
+Signed-off-by: Nick Terrell <terrelln@fb.com>
+---
+ fs/squashfs/Kconfig        |  14 +++++
+ fs/squashfs/Makefile       |   1 +
+ fs/squashfs/decompressor.c |   7 +++
+ fs/squashfs/decompressor.h |   4 ++
+ fs/squashfs/squashfs_fs.h  |   1 +
+ fs/squashfs/zstd_wrapper.c | 150 +++++++++++++++++++++++++++++++++++++++++++++
+ 6 files changed, 177 insertions(+)
+ create mode 100644 fs/squashfs/zstd_wrapper.c
+
 diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
 index ffb093e..1adb334 100644
 --- a/fs/squashfs/Kconfig
 +++ b/fs/squashfs/Kconfig
 @@ -165,6 +165,20 @@ config SQUASHFS_XZ
- 
+
  	  If unsure, say N.
- 
+
 +config SQUASHFS_ZSTD
 +	bool "Include support for ZSTD compressed file systems"
 +	depends on SQUASHFS
@@ -39,7 +95,7 @@ index d2bc136..8366398 100644
 @@ -65,6 +65,12 @@ static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
  };
  #endif
- 
+
 +#ifndef CONFIG_SQUASHFS_ZSTD
 +static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
 +	NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
@@ -56,7 +112,7 @@ index d2bc136..8366398 100644
 +	&squashfs_zstd_comp_ops,
  	&squashfs_unknown_comp_ops
  };
- 
+
 diff --git a/fs/squashfs/decompressor.h b/fs/squashfs/decompressor.h
 index a25713c..0f5a8e4 100644
 --- a/fs/squashfs/decompressor.h
@@ -64,7 +120,7 @@ index a25713c..0f5a8e4 100644
 @@ -58,4 +58,8 @@ extern const struct squashfs_decompressor squashfs_lzo_comp_ops;
  extern const struct squashfs_decompressor squashfs_zlib_comp_ops;
  #endif
- 
+
 +#ifdef CONFIG_SQUASHFS_ZSTD
 +extern const struct squashfs_decompressor squashfs_zstd_comp_ops;
 +#endif
@@ -79,7 +135,7 @@ index 506f4ba..24d12fd 100644
  #define XZ_COMPRESSION		4
  #define LZ4_COMPRESSION		5
 +#define ZSTD_COMPRESSION	6
- 
+
  struct squashfs_super_block {
  	__le32			s_magic;
 diff --git a/fs/squashfs/zstd_wrapper.c b/fs/squashfs/zstd_wrapper.c
@@ -238,3 +294,5 @@ index 0000000..8cb7c76
 +	.name = "zstd",
 +	.supported = 1
 +};
+--
+2.9.3

contrib/linux-kernel/btrfs-extract-benchmark.sh

@@ -0,0 +1,99 @@
+# !/bin/sh
+set -e
+
+# Benchmarks run on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM.
+# The VM is running on a Macbook Pro with a 3.1 GHz Intel Core i7 processor and
+# 16 GB of RAM and an SSD.
+
+# silesia is a directory that can be downloaded from
+# http://mattmahoney.net/dc/silesia.html
+# ls -l silesia/
+# total 203M
+# -rwxr-xr-x 1 terrelln 9.8M Apr 12  2002 dickens
+# -rwxr-xr-x 1 terrelln  49M May 31  2002 mozilla
+# -rwxr-xr-x 1 terrelln 9.6M Mar 20  2003 mr
+# -rwxr-xr-x 1 terrelln  32M Apr  2  2002 nci
+# -rwxr-xr-x 1 terrelln 5.9M Jul  4  2002 ooffice
+# -rwxr-xr-x 1 terrelln 9.7M Apr 11  2002 osdb
+# -rwxr-xr-x 1 terrelln 6.4M Apr  2  2002 reymont
+# -rwxr-xr-x 1 terrelln  21M Mar 25  2002 samba
+# -rwxr-xr-x 1 terrelln 7.0M Mar 24  2002 sao
+# -rwxr-xr-x 1 terrelln  40M Mar 25  2002 webster
+# -rwxr-xr-x 1 terrelln 8.1M Apr  4  2002 x-ray
+# -rwxr-xr-x 1 terrelln 5.1M Nov 30  2000 xml
+
+# $HOME is on a ext4 filesystem
+BENCHMARK_FILE="linux-4.11.6.tar"
+BENCHMARK_DIR="$HOME/$BENCHMARK_FILE"
+
+# Normalize the environment
+sudo umount /mnt/btrfs 2> /dev/null > /dev/null || true
+sudo mount -t btrfs $@ /dev/sda3 /mnt/btrfs
+sudo rm -rf /mnt/btrfs/*
+sync
+sudo umount /mnt/btrfs
+sudo mount -t btrfs $@ /dev/sda3 /mnt/btrfs
+
+# Run the benchmark
+echo "Copy"
+time sh -c "sudo cp -r $BENCHMARK_DIR /mnt/btrfs/$BENCHMARK_FILE && sync"
+
+echo "Approximate tarred compression ratio"
+printf "%d / %d\n"                                                             \
+  $(df /mnt/btrfs --output=used -B 1 | tail -n 1)                              \
+  $(sudo du /mnt/btrfs -b -d 0 | tr '\t' '\n' | head -n 1);
+
+# Unmount and remount to avoid any caching
+sudo umount /mnt/btrfs
+sudo mount -t btrfs $@ /dev/sda3 /mnt/btrfs
+
+echo "Extract"
+time sh -c "sudo tar -C /mnt/btrfs -xf /mnt/btrfs/$BENCHMARK_FILE && sync"
+
+# Remove the tarball, leaving only the extracted data
+sudo rm /mnt/btrfs/$BENCHMARK_FILE
+# Unmount and remount to avoid any caching
+sudo umount /mnt/btrfs
+sudo mount -t btrfs $@ /dev/sda3 /mnt/btrfs
+
+echo "Approximate extracted compression ratio"
+printf "%d / %d\n"                                                             \
+  $(df /mnt/btrfs --output=used -B 1 | tail -n 1)                              \
+  $(sudo du /mnt/btrfs -b -d 0 | tr '\t' '\n' | head -n 1);
+
+echo "Read"
+time sudo tar -c /mnt/btrfs 2> /dev/null | wc -c > /dev/null
+
+sudo rm -rf /mnt/btrfs/*
+sudo umount /mnt/btrfs
+
+# Run for each of -o compress-force={none, lzo, zlib, zstd} 5 times and take the
+# min time and ratio.
+
+# none
+# copy: 0.981 s
+# extract: 5.501 s
+# read: 8.807 s
+# tarball ratio: 0.97
+# extracted ratio: 0.78
+
+# lzo
+# copy: 1.631 s
+# extract: 8.458 s
+# read: 8.585 s
+# tarball ratio: 2.06
+# extracted ratio: 1.38
+
+# zlib
+# copy: 7.750 s
+# extract: 21.544 s
+# read: 11.744 s
+# tarball ratio : 3.40
+# extracted ratio: 1.86
+
+# zstd 1
+# copy: 2.579 s
+# extract: 11.479 s
+# read: 9.389 s
+# tarball ratio : 3.57
+# extracted ratio: 1.85