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-rw-r--r--src/zstd/contrib/linux-kernel/0003-btrfs-Add-zstd-support.patch740
1 files changed, 740 insertions, 0 deletions
diff --git a/src/zstd/contrib/linux-kernel/0003-btrfs-Add-zstd-support.patch b/src/zstd/contrib/linux-kernel/0003-btrfs-Add-zstd-support.patch
new file mode 100644
index 00000000..edc7839a
--- /dev/null
+++ b/src/zstd/contrib/linux-kernel/0003-btrfs-Add-zstd-support.patch
@@ -0,0 +1,740 @@
+From 8a9dddfbf6551afea73911e367dd4be64d62b9fd Mon Sep 17 00:00:00 2001
+From: Nick Terrell <terrelln@fb.com>
+Date: Mon, 17 Jul 2017 17:08:39 -0700
+Subject: [PATCH v5 3/5] 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>
+---
+v2 -> v3:
+- Port upstream BtrFS commits e1ddce71d6, 389a6cfc2a, and 6acafd1eff
+- Change default compression level for BtrFS to 3
+
+v3 -> v4:
+- Add missing includes, which fixes the aarch64 build
+- Fix minor linter warnings
+
+ 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 | 432 +++++++++++++++++++++++++++++++++++++++++++++
+ include/uapi/linux/btrfs.h | 8 +-
+ 12 files changed, 468 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
++++ b/fs/btrfs/Kconfig
+@@ -6,6 +6,8 @@ config BTRFS_FS
+ select ZLIB_DEFLATE
+ select LZO_COMPRESS
+ select LZO_DECOMPRESS
++ select ZSTD_COMPRESS
++ select ZSTD_DECOMPRESS
+ select RAID6_PQ
+ select XOR_BLOCKS
+ select SRCU
+diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
+index 128ce17..962a95a 100644
+--- a/fs/btrfs/Makefile
++++ b/fs/btrfs/Makefile
+@@ -6,7 +6,7 @@ btrfs-y += super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
+ transaction.o inode.o file.o tree-defrag.o \
+ extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \
+ extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \
+- export.o tree-log.o free-space-cache.o zlib.o lzo.o \
++ export.o tree-log.o free-space-cache.o zlib.o lzo.o zstd.o \
+ compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o \
+ 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 d2ef9ac..4ff42d1 100644
+--- a/fs/btrfs/compression.c
++++ b/fs/btrfs/compression.c
+@@ -704,6 +704,7 @@ static struct {
+ static const struct btrfs_compress_op * const btrfs_compress_op[] = {
+ &btrfs_zlib_compress,
+ &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 87f6d33..2269e00 100644
+--- a/fs/btrfs/compression.h
++++ b/fs/btrfs/compression.h
+@@ -99,8 +99,9 @@ enum btrfs_compression_type {
+ BTRFS_COMPRESS_NONE = 0,
+ BTRFS_COMPRESS_ZLIB = 1,
+ BTRFS_COMPRESS_LZO = 2,
+- BTRFS_COMPRESS_TYPES = 2,
+- BTRFS_COMPRESS_LAST = 3,
++ BTRFS_COMPRESS_ZSTD = 3,
++ BTRFS_COMPRESS_TYPES = 3,
++ BTRFS_COMPRESS_LAST = 4,
+ };
+
+ struct btrfs_compress_op {
+@@ -128,5 +129,6 @@ 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 3f3eb7b..845d77c 100644
+--- a/fs/btrfs/ctree.h
++++ b/fs/btrfs/ctree.h
+@@ -270,6 +270,7 @@ struct btrfs_super_block {
+ BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS | \
+ BTRFS_FEATURE_INCOMPAT_BIG_METADATA | \
+ BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO | \
++ BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD | \
+ BTRFS_FEATURE_INCOMPAT_RAID56 | \
+ 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 080e2eb..04632f4 100644
+--- a/fs/btrfs/disk-io.c
++++ b/fs/btrfs/disk-io.c
+@@ -2828,6 +2828,8 @@ 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 (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 fa1b78c..b9963d9 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
++ else if (fs_info->compress_type == BTRFS_COMPRESS_ZLIB)
+ comp = "zlib";
++ else
++ comp = "zstd";
+ ret = btrfs_set_prop(inode, "btrfs.compression",
+ comp, strlen(comp), 0);
+ if (ret)
+@@ -1466,6 +1468,8 @@ 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 4b23ae5..20631e9 100644
+--- a/fs/btrfs/props.c
++++ b/fs/btrfs/props.c
+@@ -390,6 +390,8 @@ static int prop_compression_validate(const char *value, size_t len)
+ return 0;
+ else if (!strncmp("zlib", value, len))
+ return 0;
++ else if (!strncmp("zstd", value, len))
++ return 0;
+
+ return -EINVAL;
+ }
+@@ -412,6 +414,8 @@ static int prop_compression_apply(struct inode *inode,
+ type = BTRFS_COMPRESS_LZO;
+ else if (!strncmp("zlib", value, len))
+ type = BTRFS_COMPRESS_ZLIB;
++ else if (!strncmp("zstd", value, len))
++ type = BTRFS_COMPRESS_ZSTD;
+ else
+ return -EINVAL;
+
+@@ -429,6 +433,8 @@ static const char *prop_compression_extract(struct inode *inode)
+ return "zlib";
+ case BTRFS_COMPRESS_LZO:
+ return "lzo";
++ case BTRFS_COMPRESS_ZSTD:
++ return "zstd";
+ }
+
+ return NULL;
+diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
+index 12540b6..c370dea 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,
+ btrfs_clear_opt(info->mount_opt, NODATASUM);
+ btrfs_set_fs_incompat(info, COMPRESS_LZO);
+ no_compress = 0;
++ } else if (strcmp(args[0].from, "zstd") == 0) {
++ compress_type = "zstd";
++ info->compress_type = BTRFS_COMPRESS_ZSTD;
++ btrfs_set_opt(info->mount_opt, COMPRESS);
++ btrfs_clear_opt(info->mount_opt, NODATACOW);
++ btrfs_clear_opt(info->mount_opt, NODATASUM);
++ btrfs_set_fs_incompat(info, COMPRESS_ZSTD);
++ no_compress = 0;
+ } else if (strncmp(args[0].from, "no", 2) == 0) {
+ compress_type = "no";
+ btrfs_clear_opt(info->mount_opt, COMPRESS);
+@@ -1227,8 +1235,10 @@ 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";
+- else
++ else if (info->compress_type == BTRFS_COMPRESS_LZO)
+ compress_type = "lzo";
++ else
++ compress_type = "zstd";
+ if (btrfs_test_opt(info, FORCE_COMPRESS))
+ seq_printf(seq, ",compress-force=%s", compress_type);
+ else
+diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
+index c2d5f35..2b6d37c 100644
+--- a/fs/btrfs/sysfs.c
++++ b/fs/btrfs/sysfs.c
+@@ -200,6 +200,7 @@ BTRFS_FEAT_ATTR_INCOMPAT(mixed_backref, MIXED_BACKREF);
+ BTRFS_FEAT_ATTR_INCOMPAT(default_subvol, DEFAULT_SUBVOL);
+ BTRFS_FEAT_ATTR_INCOMPAT(mixed_groups, MIXED_GROUPS);
+ BTRFS_FEAT_ATTR_INCOMPAT(compress_lzo, COMPRESS_LZO);
++BTRFS_FEAT_ATTR_INCOMPAT(compress_zstd, COMPRESS_ZSTD);
+ BTRFS_FEAT_ATTR_INCOMPAT(big_metadata, BIG_METADATA);
+ BTRFS_FEAT_ATTR_INCOMPAT(extended_iref, EXTENDED_IREF);
+ BTRFS_FEAT_ATTR_INCOMPAT(raid56, RAID56);
+@@ -212,6 +213,7 @@ static struct attribute *btrfs_supported_feature_attrs[] = {
+ BTRFS_FEAT_ATTR_PTR(default_subvol),
+ BTRFS_FEAT_ATTR_PTR(mixed_groups),
+ BTRFS_FEAT_ATTR_PTR(compress_lzo),
++ BTRFS_FEAT_ATTR_PTR(compress_zstd),
+ BTRFS_FEAT_ATTR_PTR(big_metadata),
+ BTRFS_FEAT_ATTR_PTR(extended_iref),
+ BTRFS_FEAT_ATTR_PTR(raid56),
+diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
+new file mode 100644
+index 0000000..607ce47
+--- /dev/null
++++ b/fs/btrfs/zstd.c
+@@ -0,0 +1,432 @@
++/*
++ * Copyright (c) 2016-present, Facebook, Inc.
++ * All rights reserved.
++ *
++ * This program is free software; you can redistribute it and/or
++ * modify it under the terms of the GNU General Public
++ * License v2 as published by the Free Software Foundation.
++ *
++ * This program is distributed in the hope that it will be useful,
++ * but WITHOUT ANY WARRANTY; without even the implied warranty of
++ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
++ * General Public License for more details.
++ */
++#include <linux/bio.h>
++#include <linux/err.h>
++#include <linux/init.h>
++#include <linux/kernel.h>
++#include <linux/mm.h>
++#include <linux/pagemap.h>
++#include <linux/refcount.h>
++#include <linux/sched.h>
++#include <linux/slab.h>
++#include <linux/zstd.h>
++#include "compression.h"
++
++#define ZSTD_BTRFS_MAX_WINDOWLOG 17
++#define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
++#define ZSTD_BTRFS_DEFAULT_LEVEL 3
++
++static ZSTD_parameters zstd_get_btrfs_parameters(size_t src_len)
++{
++ ZSTD_parameters params = ZSTD_getParams(ZSTD_BTRFS_DEFAULT_LEVEL,
++ src_len, 0);
++
++ if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG)
++ params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG;
++ WARN_ON(src_len > ZSTD_BTRFS_MAX_INPUT);
++ return params;
++}
++
++struct workspace {
++ void *mem;
++ size_t size;
++ char *buf;
++ struct list_head list;
++};
++
++static void zstd_free_workspace(struct list_head *ws)
++{
++ struct workspace *workspace = list_entry(ws, struct workspace, list);
++
++ kvfree(workspace->mem);
++ kfree(workspace->buf);
++ kfree(workspace);
++}
++
++static struct list_head *zstd_alloc_workspace(void)
++{
++ ZSTD_parameters params =
++ zstd_get_btrfs_parameters(ZSTD_BTRFS_MAX_INPUT);
++ struct workspace *workspace;
++
++ workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
++ if (!workspace)
++ return ERR_PTR(-ENOMEM);
++
++ workspace->size = max_t(size_t,
++ ZSTD_CStreamWorkspaceBound(params.cParams),
++ ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
++ workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
++ workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
++ if (!workspace->mem || !workspace->buf)
++ goto fail;
++
++ INIT_LIST_HEAD(&workspace->list);
++
++ return &workspace->list;
++fail:
++ zstd_free_workspace(&workspace->list);
++ return ERR_PTR(-ENOMEM);
++}
++
++static int zstd_compress_pages(struct list_head *ws,
++ struct address_space *mapping,
++ u64 start,
++ struct page **pages,
++ unsigned long *out_pages,
++ unsigned long *total_in,
++ unsigned long *total_out)
++{
++ struct workspace *workspace = list_entry(ws, struct workspace, list);
++ ZSTD_CStream *stream;
++ int ret = 0;
++ int nr_pages = 0;
++ struct page *in_page = NULL; /* The current page to read */
++ struct page *out_page = NULL; /* The current page to write to */
++ ZSTD_inBuffer in_buf = { NULL, 0, 0 };
++ ZSTD_outBuffer out_buf = { NULL, 0, 0 };
++ unsigned long tot_in = 0;
++ unsigned long tot_out = 0;
++ unsigned long len = *total_out;
++ const unsigned long nr_dest_pages = *out_pages;
++ unsigned long max_out = nr_dest_pages * PAGE_SIZE;
++ ZSTD_parameters params = zstd_get_btrfs_parameters(len);
++
++ *out_pages = 0;
++ *total_out = 0;
++ *total_in = 0;
++
++ /* Initialize the stream */
++ stream = ZSTD_initCStream(params, len, workspace->mem,
++ workspace->size);
++ if (!stream) {
++ pr_warn("BTRFS: ZSTD_initCStream failed\n");
++ ret = -EIO;
++ goto out;
++ }
++
++ /* map in the first page of input data */
++ in_page = find_get_page(mapping, start >> PAGE_SHIFT);
++ in_buf.src = kmap(in_page);
++ in_buf.pos = 0;
++ in_buf.size = min_t(size_t, len, PAGE_SIZE);
++
++
++ /* Allocate and map in the output buffer */
++ out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
++ if (out_page == NULL) {
++ ret = -ENOMEM;
++ goto out;
++ }
++ pages[nr_pages++] = out_page;
++ out_buf.dst = kmap(out_page);
++ out_buf.pos = 0;
++ out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
++
++ while (1) {
++ size_t ret2;
++
++ ret2 = ZSTD_compressStream(stream, &out_buf, &in_buf);
++ if (ZSTD_isError(ret2)) {
++ pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
++ ZSTD_getErrorCode(ret2));
++ ret = -EIO;
++ goto out;
++ }
++
++ /* Check to see if we are making it bigger */
++ if (tot_in + in_buf.pos > 8192 &&
++ tot_in + in_buf.pos <
++ tot_out + out_buf.pos) {
++ ret = -E2BIG;
++ goto out;
++ }
++
++ /* We've reached the end of our output range */
++ if (out_buf.pos >= max_out) {
++ tot_out += out_buf.pos;
++ ret = -E2BIG;
++ goto out;
++ }
++
++ /* Check if we need more output space */
++ if (out_buf.pos == out_buf.size) {
++ tot_out += PAGE_SIZE;
++ max_out -= PAGE_SIZE;
++ kunmap(out_page);
++ if (nr_pages == nr_dest_pages) {
++ out_page = NULL;
++ ret = -E2BIG;
++ goto out;
++ }
++ out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
++ if (out_page == NULL) {
++ ret = -ENOMEM;
++ goto out;
++ }
++ pages[nr_pages++] = out_page;
++ out_buf.dst = kmap(out_page);
++ out_buf.pos = 0;
++ out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
++ }
++
++ /* We've reached the end of the input */
++ if (in_buf.pos >= len) {
++ tot_in += in_buf.pos;
++ break;
++ }
++
++ /* Check if we need more input */
++ if (in_buf.pos == in_buf.size) {
++ tot_in += PAGE_SIZE;
++ kunmap(in_page);
++ put_page(in_page);
++
++ start += PAGE_SIZE;
++ len -= PAGE_SIZE;
++ in_page = find_get_page(mapping, start >> PAGE_SHIFT);
++ in_buf.src = kmap(in_page);
++ in_buf.pos = 0;
++ in_buf.size = min_t(size_t, len, PAGE_SIZE);
++ }
++ }
++ while (1) {
++ size_t ret2;
++
++ ret2 = ZSTD_endStream(stream, &out_buf);
++ if (ZSTD_isError(ret2)) {
++ pr_debug("BTRFS: ZSTD_endStream returned %d\n",
++ ZSTD_getErrorCode(ret2));
++ ret = -EIO;
++ goto out;
++ }
++ if (ret2 == 0) {
++ tot_out += out_buf.pos;
++ break;
++ }
++ if (out_buf.pos >= max_out) {
++ tot_out += out_buf.pos;
++ ret = -E2BIG;
++ goto out;
++ }
++
++ tot_out += PAGE_SIZE;
++ max_out -= PAGE_SIZE;
++ kunmap(out_page);
++ if (nr_pages == nr_dest_pages) {
++ out_page = NULL;
++ ret = -E2BIG;
++ goto out;
++ }
++ out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
++ if (out_page == NULL) {
++ ret = -ENOMEM;
++ goto out;
++ }
++ pages[nr_pages++] = out_page;
++ out_buf.dst = kmap(out_page);
++ out_buf.pos = 0;
++ out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
++ }
++
++ if (tot_out >= tot_in) {
++ ret = -E2BIG;
++ goto out;
++ }
++
++ ret = 0;
++ *total_in = tot_in;
++ *total_out = tot_out;
++out:
++ *out_pages = nr_pages;
++ /* Cleanup */
++ if (in_page) {
++ kunmap(in_page);
++ put_page(in_page);
++ }
++ if (out_page)
++ kunmap(out_page);
++ return ret;
++}
++
++static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
++{
++ struct workspace *workspace = list_entry(ws, struct workspace, list);
++ struct page **pages_in = cb->compressed_pages;
++ u64 disk_start = cb->start;
++ struct bio *orig_bio = cb->orig_bio;
++ size_t srclen = cb->compressed_len;
++ ZSTD_DStream *stream;
++ int ret = 0;
++ unsigned long page_in_index = 0;
++ unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
++ unsigned long buf_start;
++ unsigned long total_out = 0;
++ ZSTD_inBuffer in_buf = { NULL, 0, 0 };
++ ZSTD_outBuffer out_buf = { NULL, 0, 0 };
++
++ stream = ZSTD_initDStream(
++ ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
++ if (!stream) {
++ pr_debug("BTRFS: ZSTD_initDStream failed\n");
++ ret = -EIO;
++ goto done;
++ }
++
++ in_buf.src = kmap(pages_in[page_in_index]);
++ in_buf.pos = 0;
++ in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
++
++ out_buf.dst = workspace->buf;
++ out_buf.pos = 0;
++ out_buf.size = PAGE_SIZE;
++
++ while (1) {
++ size_t ret2;
++
++ ret2 = ZSTD_decompressStream(stream, &out_buf, &in_buf);
++ if (ZSTD_isError(ret2)) {
++ pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
++ ZSTD_getErrorCode(ret2));
++ ret = -EIO;
++ goto done;
++ }
++ buf_start = total_out;
++ total_out += out_buf.pos;
++ out_buf.pos = 0;
++
++ ret = btrfs_decompress_buf2page(out_buf.dst, buf_start,
++ total_out, disk_start, orig_bio);
++ if (ret == 0)
++ break;
++
++ if (in_buf.pos >= srclen)
++ break;
++
++ /* Check if we've hit the end of a frame */
++ if (ret2 == 0)
++ break;
++
++ if (in_buf.pos == in_buf.size) {
++ kunmap(pages_in[page_in_index++]);
++ if (page_in_index >= total_pages_in) {
++ in_buf.src = NULL;
++ ret = -EIO;
++ goto done;
++ }
++ srclen -= PAGE_SIZE;
++ in_buf.src = kmap(pages_in[page_in_index]);
++ in_buf.pos = 0;
++ in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
++ }
++ }
++ ret = 0;
++ zero_fill_bio(orig_bio);
++done:
++ if (in_buf.src)
++ kunmap(pages_in[page_in_index]);
++ return ret;
++}
++
++static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
++ struct page *dest_page,
++ unsigned long start_byte,
++ size_t srclen, size_t destlen)
++{
++ struct workspace *workspace = list_entry(ws, struct workspace, list);
++ ZSTD_DStream *stream;
++ int ret = 0;
++ size_t ret2;
++ ZSTD_inBuffer in_buf = { NULL, 0, 0 };
++ ZSTD_outBuffer out_buf = { NULL, 0, 0 };
++ unsigned long total_out = 0;
++ unsigned long pg_offset = 0;
++ char *kaddr;
++
++ stream = ZSTD_initDStream(
++ ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
++ if (!stream) {
++ pr_warn("BTRFS: ZSTD_initDStream failed\n");
++ ret = -EIO;
++ goto finish;
++ }
++
++ destlen = min_t(size_t, destlen, PAGE_SIZE);
++
++ in_buf.src = data_in;
++ in_buf.pos = 0;
++ in_buf.size = srclen;
++
++ out_buf.dst = workspace->buf;
++ out_buf.pos = 0;
++ out_buf.size = PAGE_SIZE;
++
++ ret2 = 1;
++ while (pg_offset < destlen && in_buf.pos < in_buf.size) {
++ unsigned long buf_start;
++ unsigned long buf_offset;
++ unsigned long bytes;
++
++ /* Check if the frame is over and we still need more input */
++ if (ret2 == 0) {
++ pr_debug("BTRFS: ZSTD_decompressStream ended early\n");
++ ret = -EIO;
++ goto finish;
++ }
++ ret2 = ZSTD_decompressStream(stream, &out_buf, &in_buf);
++ if (ZSTD_isError(ret2)) {
++ pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
++ ZSTD_getErrorCode(ret2));
++ ret = -EIO;
++ goto finish;
++ }
++
++ buf_start = total_out;
++ total_out += out_buf.pos;
++ out_buf.pos = 0;
++
++ if (total_out <= start_byte)
++ continue;
++
++ if (total_out > start_byte && buf_start < start_byte)
++ buf_offset = start_byte - buf_start;
++ else
++ buf_offset = 0;
++
++ bytes = min_t(unsigned long, destlen - pg_offset,
++ out_buf.size - buf_offset);
++
++ kaddr = kmap_atomic(dest_page);
++ memcpy(kaddr + pg_offset, out_buf.dst + buf_offset, bytes);
++ kunmap_atomic(kaddr);
++
++ pg_offset += bytes;
++ }
++ ret = 0;
++finish:
++ if (pg_offset < destlen) {
++ kaddr = kmap_atomic(dest_page);
++ memset(kaddr + pg_offset, 0, destlen - pg_offset);
++ kunmap_atomic(kaddr);
++ }
++ return ret;
++}
++
++const struct btrfs_compress_op btrfs_zstd_compress = {
++ .alloc_workspace = zstd_alloc_workspace,
++ .free_workspace = zstd_free_workspace,
++ .compress_pages = zstd_compress_pages,
++ .decompress_bio = zstd_decompress_bio,
++ .decompress = zstd_decompress,
++};
+diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
+index 9aa74f3..378230c 100644
+--- a/include/uapi/linux/btrfs.h
++++ b/include/uapi/linux/btrfs.h
+@@ -255,13 +255,7 @@ struct btrfs_ioctl_fs_info_args {
+ #define BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL (1ULL << 1)
+ #define BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS (1ULL << 2)
+ #define BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO (1ULL << 3)
+-/*
+- * some patches floated around with a second compression method
+- * lets save that incompat here for when they do get in
+- * Note we don't actually support it, we're just reserving the
+- * number
+- */
+-#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