243 lines
6.6 KiB
Diff
243 lines
6.6 KiB
Diff
commit 7289653483a0579c3b63a06abf008210c8cc6c8b
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Author: Sean Purcell <me@seanp.xyz>
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Date: Thu Apr 27 14:56:25 2017 -0700
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Add zstd support to kernel squashfs
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diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
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index ffb093e..1adb334 100644
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--- a/fs/squashfs/Kconfig
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+++ b/fs/squashfs/Kconfig
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@@ -165,6 +165,20 @@ config SQUASHFS_XZ
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If unsure, say N.
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+config SQUASHFS_ZSTD
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+ bool "Include support for ZSTD compressed file systems"
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+ depends on SQUASHFS
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+ select ZSTD_DECOMPRESS
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+ help
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+ Saying Y here includes support for reading Squashfs file systems
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+ compressed with ZSTD compression. ZSTD gives better compression than
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+ the default ZLIB compression, while using less CPU.
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+
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+ ZSTD is not the standard compression used in Squashfs and so most
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+ file systems will be readable without selecting this option.
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+
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+ If unsure, say N.
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+
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config SQUASHFS_4K_DEVBLK_SIZE
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bool "Use 4K device block size?"
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depends on SQUASHFS
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diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
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index 246a6f3..6655631 100644
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--- a/fs/squashfs/Makefile
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+++ b/fs/squashfs/Makefile
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@@ -15,3 +15,4 @@ squashfs-$(CONFIG_SQUASHFS_LZ4) += lz4_wrapper.o
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squashfs-$(CONFIG_SQUASHFS_LZO) += lzo_wrapper.o
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squashfs-$(CONFIG_SQUASHFS_XZ) += xz_wrapper.o
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squashfs-$(CONFIG_SQUASHFS_ZLIB) += zlib_wrapper.o
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+squashfs-$(CONFIG_SQUASHFS_ZSTD) += zstd_wrapper.o
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diff --git a/fs/squashfs/decompressor.c b/fs/squashfs/decompressor.c
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index d2bc136..8366398 100644
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--- a/fs/squashfs/decompressor.c
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+++ b/fs/squashfs/decompressor.c
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@@ -65,6 +65,12 @@ static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
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};
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#endif
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+#ifndef CONFIG_SQUASHFS_ZSTD
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+static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
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+ NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
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+};
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+#endif
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+
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static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
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NULL, NULL, NULL, NULL, 0, "unknown", 0
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};
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@@ -75,6 +81,7 @@ static const struct squashfs_decompressor *decompressor[] = {
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&squashfs_lzo_comp_ops,
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&squashfs_xz_comp_ops,
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&squashfs_lzma_unsupported_comp_ops,
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+ &squashfs_zstd_comp_ops,
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&squashfs_unknown_comp_ops
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};
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diff --git a/fs/squashfs/decompressor.h b/fs/squashfs/decompressor.h
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index a25713c..0f5a8e4 100644
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--- a/fs/squashfs/decompressor.h
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+++ b/fs/squashfs/decompressor.h
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@@ -58,4 +58,8 @@ extern const struct squashfs_decompressor squashfs_lzo_comp_ops;
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extern const struct squashfs_decompressor squashfs_zlib_comp_ops;
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#endif
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+#ifdef CONFIG_SQUASHFS_ZSTD
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+extern const struct squashfs_decompressor squashfs_zstd_comp_ops;
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+#endif
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+
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#endif
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diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
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index 506f4ba..24d12fd 100644
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--- a/fs/squashfs/squashfs_fs.h
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+++ b/fs/squashfs/squashfs_fs.h
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@@ -241,6 +241,7 @@ struct meta_index {
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#define LZO_COMPRESSION 3
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#define XZ_COMPRESSION 4
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#define LZ4_COMPRESSION 5
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+#define ZSTD_COMPRESSION 6
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struct squashfs_super_block {
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__le32 s_magic;
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diff --git a/fs/squashfs/zstd_wrapper.c b/fs/squashfs/zstd_wrapper.c
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new file mode 100644
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index 0000000..81f4b5a
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--- /dev/null
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+++ b/fs/squashfs/zstd_wrapper.c
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@@ -0,0 +1,146 @@
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+/*
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+ * Squashfs - a compressed read only filesystem for Linux
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+ *
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+ * Copyright (c) 2017 Facebook
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License
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+ * as published by the Free Software Foundation; either version 2,
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+ * or (at your option) any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with this program; if not, write to the Free Software
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+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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+ *
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+ * zstd_wrapper.c
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+ */
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+
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+#include <linux/mutex.h>
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+#include <linux/buffer_head.h>
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+#include <linux/slab.h>
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+#include <linux/zstd.h>
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+#include <linux/vmalloc.h>
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+
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+#include "squashfs_fs.h"
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+#include "squashfs_fs_sb.h"
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+#include "squashfs.h"
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+#include "decompressor.h"
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+#include "page_actor.h"
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+
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+struct workspace {
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+ void *mem;
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+ size_t mem_size;
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+};
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+
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+static void *zstd_init(struct squashfs_sb_info *msblk, void *buff)
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+{
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+ struct workspace *wksp = kmalloc(sizeof(*wksp), GFP_KERNEL);
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+ if (wksp == NULL)
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+ goto failed;
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+ wksp->mem_size = ZSTD_DStreamWorkspaceBound(max_t(size_t,
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+ msblk->block_size, SQUASHFS_METADATA_SIZE));
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+ wksp->mem = vmalloc(wksp->mem_size);
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+ if (wksp->mem == NULL)
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+ goto failed;
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+
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+ return wksp;
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+
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+failed:
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+ ERROR("Failed to allocate zstd workspace\n");
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+ kfree(wksp);
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+ return ERR_PTR(-ENOMEM);
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+}
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+
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+
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+static void zstd_free(void *strm)
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+{
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+ struct workspace *wksp = strm;
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+
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+ if (wksp)
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+ vfree(wksp->mem);
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+ kfree(wksp);
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+}
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+
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+
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+static int zstd_uncompress(struct squashfs_sb_info *msblk, void *strm,
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+ struct buffer_head **bh, int b, int offset, int length,
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+ struct squashfs_page_actor *output)
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+{
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+ struct workspace *wksp = strm;
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+ ZSTD_DStream *stream;
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+ size_t total_out = 0;
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+ size_t zstd_err;
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+ int k = 0;
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+ ZSTD_inBuffer in_buf = { NULL, 0, 0 };
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+ ZSTD_outBuffer out_buf = { NULL, 0, 0 };
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+
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+ stream = ZSTD_initDStream(wksp->mem_size, wksp->mem, wksp->mem_size);
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+
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+ if (!stream) {
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+ ERROR("Failed to initialize zstd decompressor\n");
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+ goto out;
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+ }
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+
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+ out_buf.size = PAGE_SIZE;
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+ out_buf.dst = squashfs_first_page(output);
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+
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+ do {
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+ if (in_buf.pos == in_buf.size && k < b) {
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+ int avail = min(length, msblk->devblksize - offset);
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+ length -= avail;
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+ in_buf.src = bh[k]->b_data + offset;
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+ in_buf.size = avail;
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+ in_buf.pos = 0;
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+ offset = 0;
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+ }
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+
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+ if (out_buf.pos == out_buf.size) {
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+ out_buf.dst = squashfs_next_page(output);
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+ out_buf.pos = 0;
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+ if (out_buf.dst != NULL) {
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+ out_buf.size = PAGE_SIZE;
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+ } else {
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+ out_buf.size = 0;
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+ }
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+ }
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+
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+ total_out -= out_buf.pos;
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+ zstd_err = ZSTD_decompressStream(stream, &out_buf, &in_buf);
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+ total_out += out_buf.pos; /* add the additional data produced */
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+
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+ if (in_buf.pos == in_buf.size && k < b)
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+ put_bh(bh[k++]);
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+ } while (zstd_err != 0 && !ZSTD_isError(zstd_err));
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+
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+ if (ZSTD_isError(zstd_err)) {
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+ ERROR("zstd decompression error: %d\n",
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+ (int)ZSTD_getErrorCode(zstd_err));
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+ }
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+
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+ squashfs_finish_page(output);
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+
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+ if (k < b)
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+ goto out;
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+
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+ return total_out;
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+
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+out:
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+ for (; k < b; k++)
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+ put_bh(bh[k]);
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+
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+ return -EIO;
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+}
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+
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+const struct squashfs_decompressor squashfs_zstd_comp_ops = {
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+ .init = zstd_init,
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+ .free = zstd_free,
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+ .decompress = zstd_uncompress,
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+ .id = ZSTD_COMPRESSION,
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+ .name = "zstd",
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+ .supported = 1
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+};
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