Merge branch '2022-03-15-add-erofs-support' into next

- Add erofs support

28 files changed, 3272 insertions, 218 deletions

diff --git a/.azure-pipelines.yml b/.azure-pipelines.yml
index 8352b10348d..cf49161c6f3 100644
--- a/.azure-pipelines.yml
+++ b/.azure-pipelines.yml
@@ -2,7 +2,7 @@ variables:
   windows_vm: windows-2019
   ubuntu_vm: ubuntu-18.04
   macos_vm: macOS-10.15
-  ci_runner_image: trini/u-boot-gitlab-ci-runner:focal-20220113-03Feb2022
+  ci_runner_image: trini/u-boot-gitlab-ci-runner:focal-20220302-15Mar2022
   # Add '-u 0' options for Azure pipelines, otherwise we get "permission
   # denied" error when it tries to "useradd -m -u 1001 vsts_azpcontainer",
   # since our $(ci_runner_image) user is not root.
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 1f4be626ada..31f50968a33 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -2,7 +2,7 @@
 
 # Grab our configured image.  The source for this is found at:
 # https://source.denx.de/u-boot/gitlab-ci-runner
-image: trini/u-boot-gitlab-ci-runner:focal-20220113-03Feb2022
+image: trini/u-boot-gitlab-ci-runner:focal-20220302-15Mar2022
 
 # We run some tests in different order, to catch some failures quicker.
 stages:
diff --git a/MAINTAINERS b/MAINTAINERS
index 5011a54e616..f25ca7cd002 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -809,6 +809,15 @@ S:	Maintained
 F:	doc/usage/environment.rst
 F:	scripts/env2string.awk
 
+EROFS
+M:	Huang Jianan <jnhuang95@gmail.com>
+L:	linux-erofs@lists.ozlabs.org
+S:	Maintained
+F:	cmd/erofs.c
+F:	fs/erofs/
+F:	include/erofs.h
+F:	test/py/tests/test_fs/test_erofs.py
+
 EVENTS
 M:	Simon Glass <sjg@chromium.org>
 S:	Maintained
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 1ed63fa06c1..9d0e803716d 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -2201,6 +2201,12 @@ config CMD_CRAMFS
 	     cramfsls   - lists files in a cramfs image
 	     cramfsload - loads a file from a cramfs image
 
+config CMD_EROFS
+	bool "EROFS command support"
+	select FS_EROFS
+	help
+	  Support for the EROFS fs
+
 config CMD_EXT2
 	bool "ext2 command support"
 	select FS_EXT4
diff --git a/cmd/Makefile b/cmd/Makefile
index 0d2b2ee092d..ede634d731c 100644
--- a/cmd/Makefile
+++ b/cmd/Makefile
@@ -61,6 +61,7 @@ obj-$(CONFIG_CMD_EEPROM) += eeprom.o
 obj-$(CONFIG_EFI) += efi.o
 obj-$(CONFIG_CMD_EFIDEBUG) += efidebug.o
 obj-$(CONFIG_CMD_ELF) += elf.o
+obj-$(CONFIG_CMD_EROFS) += erofs.o
 obj-$(CONFIG_HUSH_PARSER) += exit.o
 obj-$(CONFIG_CMD_EXT4) += ext4.o
 obj-$(CONFIG_CMD_EXT2) += ext2.o
diff --git a/cmd/erofs.c b/cmd/erofs.c
new file mode 100644
index 00000000000..add80b8b594
--- /dev/null
+++ b/cmd/erofs.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2022 Huang Jianan <jnhuang95@gmail.com>
+ *
+ * Author: Huang Jianan <jnhuang95@gmail.com>
+ *
+ * erofs.c:	implements EROFS related commands
+ */
+
+#include <command.h>
+#include <fs.h>
+#include <erofs.h>
+
+static int do_erofs_ls(struct cmd_tbl *cmdtp, int flag, int argc, char * const argv[])
+{
+	return do_ls(cmdtp, flag, argc, argv, FS_TYPE_EROFS);
+}
+
+U_BOOT_CMD(erofsls, 4, 1, do_erofs_ls,
+	   "List files in directory. Default: root (/).",
+	   "<interface> [<dev[:part]>] [directory]\n"
+	   "    - list files from 'dev' on 'interface' in 'directory'\n"
+);
+
+static int do_erofs_load(struct cmd_tbl *cmdtp, int flag, int argc, char * const argv[])
+{
+	return do_load(cmdtp, flag, argc, argv, FS_TYPE_EROFS);
+}
+
+U_BOOT_CMD(erofsload, 7, 0, do_erofs_load,
+	   "load binary file from a EROFS filesystem",
+	   "<interface> [<dev[:part]> [<addr> [<filename> [bytes [pos]]]]]\n"
+	   "    - Load binary file 'filename' from 'dev' on 'interface'\n"
+	   "      to address 'addr' from EROFS filesystem.\n"
+	   "      'pos' gives the file position to start loading from.\n"
+	   "      If 'pos' is omitted, 0 is used. 'pos' requires 'bytes'.\n"
+	   "      'bytes' gives the size to load. If 'bytes' is 0 or omitted,\n"
+	   "      the load stops on end of file.\n"
+	   "      If either 'pos' or 'bytes' are not aligned to\n"
+	   "      ARCH_DMA_MINALIGN then a misaligned buffer warning will\n"
+	   "      be printed and performance will suffer for the load."
+);
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index eaaac6d3fd9..41f73f8ecdf 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -104,6 +104,7 @@ CONFIG_CMD_TPM_TEST=y
 CONFIG_CMD_BTRFS=y
 CONFIG_CMD_CBFS=y
 CONFIG_CMD_CRAMFS=y
+CONFIG_CMD_EROFS=y
 CONFIG_CMD_EXT4_WRITE=y
 CONFIG_CMD_SQUASHFS=y
 CONFIG_CMD_MTDPARTS=y
diff --git a/fs/Kconfig b/fs/Kconfig
index 620af7f0447..cda9f66cc93 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -24,4 +24,6 @@ source "fs/yaffs2/Kconfig"
 
 source "fs/squashfs/Kconfig"
 
+source "fs/erofs/Kconfig"
+
 endmenu
diff --git a/fs/Makefile b/fs/Makefile
index 937cbcf6e85..f05a21c9e6d 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -25,5 +25,6 @@ obj-$(CONFIG_CMD_UBIFS) += ubifs/
 obj-$(CONFIG_YAFFS2) += yaffs2/
 obj-$(CONFIG_CMD_ZFS) += zfs/
 obj-$(CONFIG_FS_SQUASHFS) += squashfs/
+obj-$(CONFIG_FS_EROFS) += erofs/
 endif
 obj-y += fs_internal.o
diff --git a/fs/erofs/Kconfig b/fs/erofs/Kconfig
new file mode 100644
index 00000000000..ee4e777c5c8
--- /dev/null
+++ b/fs/erofs/Kconfig
@@ -0,0 +1,21 @@
+config FS_EROFS
+	bool "Enable EROFS filesystem support"
+	help
+	  This provides support for reading images from EROFS filesystem.
+	  EROFS (Enhanced Read-Only File System) is a lightweight read-only
+	  file system for scenarios which need high-performance read-only
+	  requirements.
+
+	  It also provides fixed-sized output compression support, which
+	  improves storage density, keeps relatively higher compression
+	  ratios, which is more useful to achieve high performance for
+	  embedded devices with limited memory.
+
+config FS_EROFS_ZIP
+	bool "EROFS Data Compression Support"
+	depends on FS_EROFS
+	select LZ4
+	default y
+	help
+	  Enable fixed-sized output compression for EROFS.
+	  If you don't want to enable compression feature, say N.
diff --git a/fs/erofs/Makefile b/fs/erofs/Makefile
new file mode 100644
index 00000000000..58af6a68e41
--- /dev/null
+++ b/fs/erofs/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+
+obj-$(CONFIG_$(SPL_)FS_EROFS) = fs.o \
+				super.o \
+				namei.o \
+				data.o \
+				decompress.o \
+				zmap.o
diff --git a/fs/erofs/data.c b/fs/erofs/data.c
new file mode 100644
index 00000000000..761896054c8
--- /dev/null
+++ b/fs/erofs/data.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include "internal.h"
+#include "decompress.h"
+
+static int erofs_map_blocks_flatmode(struct erofs_inode *inode,
+				     struct erofs_map_blocks *map,
+				     int flags)
+{
+	int err = 0;
+	erofs_blk_t nblocks, lastblk;
+	u64 offset = map->m_la;
+	struct erofs_inode *vi = inode;
+	bool tailendpacking = (vi->datalayout == EROFS_INODE_FLAT_INLINE);
+
+	nblocks = DIV_ROUND_UP(inode->i_size, EROFS_BLKSIZ);
+	lastblk = nblocks - tailendpacking;
+
+	/* there is no hole in flatmode */
+	map->m_flags = EROFS_MAP_MAPPED;
+
+	if (offset < blknr_to_addr(lastblk)) {
+		map->m_pa = blknr_to_addr(vi->u.i_blkaddr) + map->m_la;
+		map->m_plen = blknr_to_addr(lastblk) - offset;
+	} else if (tailendpacking) {
+		/* 2 - inode inline B: inode, [xattrs], inline last blk... */
+		map->m_pa = iloc(vi->nid) + vi->inode_isize +
+			vi->xattr_isize + erofs_blkoff(map->m_la);
+		map->m_plen = inode->i_size - offset;
+
+		/* inline data should be located in one meta block */
+		if (erofs_blkoff(map->m_pa) + map->m_plen > PAGE_SIZE) {
+			erofs_err("inline data cross block boundary @ nid %" PRIu64,
+				  vi->nid);
+			DBG_BUGON(1);
+			err = -EFSCORRUPTED;
+			goto err_out;
+		}
+
+		map->m_flags |= EROFS_MAP_META;
+	} else {
+		erofs_err("internal error @ nid: %" PRIu64 " (size %llu), m_la 0x%" PRIx64,
+			  vi->nid, (unsigned long long)inode->i_size, map->m_la);
+		DBG_BUGON(1);
+		err = -EIO;
+		goto err_out;
+	}
+
+	map->m_llen = map->m_plen;
+err_out:
+	return err;
+}
+
+int erofs_map_blocks(struct erofs_inode *inode,
+		     struct erofs_map_blocks *map, int flags)
+{
+	struct erofs_inode *vi = inode;
+	struct erofs_inode_chunk_index *idx;
+	u8 buf[EROFS_BLKSIZ];
+	u64 chunknr;
+	unsigned int unit;
+	erofs_off_t pos;
+	int err = 0;
+
+	map->m_deviceid = 0;
+	if (map->m_la >= inode->i_size) {
+		/* leave out-of-bound access unmapped */
+		map->m_flags = 0;
+		map->m_plen = 0;
+		goto out;
+	}
+
+	if (vi->datalayout != EROFS_INODE_CHUNK_BASED)
+		return erofs_map_blocks_flatmode(inode, map, flags);
+
+	if (vi->u.chunkformat & EROFS_CHUNK_FORMAT_INDEXES)
+		unit = sizeof(*idx);			/* chunk index */
+	else
+		unit = EROFS_BLOCK_MAP_ENTRY_SIZE;	/* block map */
+
+	chunknr = map->m_la >> vi->u.chunkbits;
+	pos = roundup(iloc(vi->nid) + vi->inode_isize +
+		      vi->xattr_isize, unit) + unit * chunknr;
+
+	err = erofs_blk_read(buf, erofs_blknr(pos), 1);
+	if (err < 0)
+		return -EIO;
+
+	map->m_la = chunknr << vi->u.chunkbits;
+	map->m_plen = min_t(erofs_off_t, 1UL << vi->u.chunkbits,
+			    roundup(inode->i_size - map->m_la, EROFS_BLKSIZ));
+
+	/* handle block map */
+	if (!(vi->u.chunkformat & EROFS_CHUNK_FORMAT_INDEXES)) {
+		__le32 *blkaddr = (void *)buf + erofs_blkoff(pos);
+
+		if (le32_to_cpu(*blkaddr) == EROFS_NULL_ADDR) {
+			map->m_flags = 0;
+		} else {
+			map->m_pa = blknr_to_addr(le32_to_cpu(*blkaddr));
+			map->m_flags = EROFS_MAP_MAPPED;
+		}
+		goto out;
+	}
+	/* parse chunk indexes */
+	idx = (void *)buf + erofs_blkoff(pos);
+	switch (le32_to_cpu(idx->blkaddr)) {
+	case EROFS_NULL_ADDR:
+		map->m_flags = 0;
+		break;
+	default:
+		map->m_deviceid = le16_to_cpu(idx->device_id) &
+			sbi.device_id_mask;
+		map->m_pa = blknr_to_addr(le32_to_cpu(idx->blkaddr));
+		map->m_flags = EROFS_MAP_MAPPED;
+		break;
+	}
+out:
+	map->m_llen = map->m_plen;
+	return err;
+}
+
+int erofs_map_dev(struct erofs_sb_info *sbi, struct erofs_map_dev *map)
+{
+	struct erofs_device_info *dif;
+	int id;
+
+	if (map->m_deviceid) {
+		if (sbi->extra_devices < map->m_deviceid)
+			return -ENODEV;
+	} else if (sbi->extra_devices) {
+		for (id = 0; id < sbi->extra_devices; ++id) {
+			erofs_off_t startoff, length;
+
+			dif = sbi->devs + id;
+			if (!dif->mapped_blkaddr)
+				continue;
+			startoff = blknr_to_addr(dif->mapped_blkaddr);
+			length = blknr_to_addr(dif->blocks);
+
+			if (map->m_pa >= startoff &&
+			    map->m_pa < startoff + length) {
+				map->m_pa -= startoff;
+				break;
+			}
+		}
+	}
+	return 0;
+}
+
+static int erofs_read_raw_data(struct erofs_inode *inode, char *buffer,
+			       erofs_off_t size, erofs_off_t offset)
+{
+	struct erofs_map_blocks map = {
+		.index = UINT_MAX,
+	};
+	struct erofs_map_dev mdev;
+	int ret;
+	erofs_off_t ptr = offset;
+
+	while (ptr < offset + size) {
+		char *const estart = buffer + ptr - offset;
+		erofs_off_t eend;
+
+		map.m_la = ptr;
+		ret = erofs_map_blocks(inode, &map, 0);
+		if (ret)
+			return ret;
+
+		DBG_BUGON(map.m_plen != map.m_llen);
+
+		mdev = (struct erofs_map_dev) {
+			.m_deviceid = map.m_deviceid,
+			.m_pa = map.m_pa,
+		};
+		ret = erofs_map_dev(&sbi, &mdev);
+		if (ret)
+			return ret;
+
+		/* trim extent */
+		eend = min(offset + size, map.m_la + map.m_llen);
+		DBG_BUGON(ptr < map.m_la);
+
+		if (!(map.m_flags & EROFS_MAP_MAPPED)) {
+			if (!map.m_llen) {
+				/* reached EOF */
+				memset(estart, 0, offset + size - ptr);
+				ptr = offset + size;
+				continue;
+			}
+			memset(estart, 0, eend - ptr);
+			ptr = eend;
+			continue;
+		}
+
+		if (ptr > map.m_la) {
+			mdev.m_pa += ptr - map.m_la;
+			map.m_la = ptr;
+		}
+
+		ret = erofs_dev_read(mdev.m_deviceid, estart, mdev.m_pa,
+				     eend - map.m_la);
+		if (ret < 0)
+			return -EIO;
+		ptr = eend;
+	}
+	return 0;
+}
+
+static int z_erofs_read_data(struct erofs_inode *inode, char *buffer,
+			     erofs_off_t size, erofs_off_t offset)
+{
+	erofs_off_t end, length, skip;
+	struct erofs_map_blocks map = {
+		.index = UINT_MAX,
+	};
+	struct erofs_map_dev mdev;
+	bool partial;
+	unsigned int bufsize = 0;
+	char *raw = NULL;
+	int ret = 0;
+
+	end = offset + size;
+	while (end > offset) {
+		map.m_la = end - 1;
+
+		ret = z_erofs_map_blocks_iter(inode, &map, 0);
+		if (ret)
+			break;
+
+		/* no device id here, thus it will always succeed */
+		mdev = (struct erofs_map_dev) {
+			.m_pa = map.m_pa,
+		};
+		ret = erofs_map_dev(&sbi, &mdev);
+		if (ret) {
+			DBG_BUGON(1);
+			break;
+		}
+
+		/*
+		 * trim to the needed size if the returned extent is quite
+		 * larger than requested, and set up partial flag as well.
+		 */
+		if (end < map.m_la + map.m_llen) {
+			length = end - map.m_la;
+			partial = true;
+		} else {
+			DBG_BUGON(end != map.m_la + map.m_llen);
+			length = map.m_llen;
+			partial = !(map.m_flags & EROFS_MAP_FULL_MAPPED);
+		}
+
+		if (map.m_la < offset) {
+			skip = offset - map.m_la;
+			end = offset;
+		} else {
+			skip = 0;
+			end = map.m_la;
+		}
+
+		if (!(map.m_flags & EROFS_MAP_MAPPED)) {
+			memset(buffer + end - offset, 0, length);
+			end = map.m_la;
+			continue;
+		}
+
+		if (map.m_plen > bufsize) {
+			bufsize = map.m_plen;
+			raw = realloc(raw, bufsize);
+			if (!raw) {
+				ret = -ENOMEM;
+				break;
+			}
+		}
+		ret = erofs_dev_read(mdev.m_deviceid, raw, mdev.m_pa, map.m_plen);
+		if (ret < 0)
+			break;
+
+		ret = z_erofs_decompress(&(struct z_erofs_decompress_req) {
+					.in = raw,
+					.out = buffer + end - offset,
+					.decodedskip = skip,
+					.inputsize = map.m_plen,
+					.decodedlength = length,
+					.alg = map.m_algorithmformat,
+					.partial_decoding = partial
+					 });
+		if (ret < 0)
+			break;
+	}
+	if (raw)
+		free(raw);
+	return ret < 0 ? ret : 0;
+}
+
+int erofs_pread(struct erofs_inode *inode, char *buf,
+		erofs_off_t count, erofs_off_t offset)
+{
+	switch (inode->datalayout) {
+	case EROFS_INODE_FLAT_PLAIN:
+	case EROFS_INODE_FLAT_INLINE:
+	case EROFS_INODE_CHUNK_BASED:
+		return erofs_read_raw_data(inode, buf, count, offset);
+	case EROFS_INODE_FLAT_COMPRESSION_LEGACY:
+	case EROFS_INODE_FLAT_COMPRESSION:
+		return z_erofs_read_data(inode, buf, count, offset);
+	default:
+		break;
+	}
+	return -EINVAL;
+}
diff --git a/fs/erofs/decompress.c b/fs/erofs/decompress.c
new file mode 100644
index 00000000000..2be3b844cfc
--- /dev/null
+++ b/fs/erofs/decompress.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include "decompress.h"
+
+#if IS_ENABLED(CONFIG_LZ4)
+#include <u-boot/lz4.h>
+static int z_erofs_decompress_lz4(struct z_erofs_decompress_req *rq)
+{
+	int ret = 0;
+	char *dest = rq->out;
+	char *src = rq->in;
+	char *buff = NULL;
+	bool support_0padding = false;
+	unsigned int inputmargin = 0;
+
+	if (erofs_sb_has_lz4_0padding()) {
+		support_0padding = true;
+
+		while (!src[inputmargin & ~PAGE_MASK])
+			if (!(++inputmargin & ~PAGE_MASK))
+				break;
+
+		if (inputmargin >= rq->inputsize)
+			return -EIO;
+	}
+
+	if (rq->decodedskip) {
+		buff = malloc(rq->decodedlength);
+		if (!buff)
+			return -ENOMEM;
+		dest = buff;
+	}
+
+	if (rq->partial_decoding || !support_0padding)
+		ret = LZ4_decompress_safe_partial(src + inputmargin, dest,
+						  rq->inputsize - inputmargin,
+						  rq->decodedlength, rq->decodedlength);
+	else
+		ret = LZ4_decompress_safe(src + inputmargin, dest,
+					  rq->inputsize - inputmargin,
+					  rq->decodedlength);
+
+	if (ret != (int)rq->decodedlength) {
+		ret = -EIO;
+		goto out;
+	}
+
+	if (rq->decodedskip)
+		memcpy(rq->out, dest + rq->decodedskip,
+		       rq->decodedlength - rq->decodedskip);
+
+out:
+	if (buff)
+		free(buff);
+
+	return ret;
+}
+#endif
+
+int z_erofs_decompress(struct z_erofs_decompress_req *rq)
+{
+	if (rq->alg == Z_EROFS_COMPRESSION_SHIFTED) {
+		if (rq->inputsize != EROFS_BLKSIZ)
+			return -EFSCORRUPTED;
+
+		DBG_BUGON(rq->decodedlength > EROFS_BLKSIZ);
+		DBG_BUGON(rq->decodedlength < rq->decodedskip);
+
+		memcpy(rq->out, rq->in + rq->decodedskip,
+		       rq->decodedlength - rq->decodedskip);
+		return 0;
+	}
+
+#if IS_ENABLED(CONFIG_LZ4)
+	if (rq->alg == Z_EROFS_COMPRESSION_LZ4)
+		return z_erofs_decompress_lz4(rq);
+#endif
+	return -EOPNOTSUPP;
+}
diff --git a/fs/erofs/decompress.h b/fs/erofs/decompress.h
new file mode 100644
index 00000000000..81d5fb84f6c
--- /dev/null
+++ b/fs/erofs/decompress.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef __EROFS_DECOMPRESS_H
+#define __EROFS_DECOMPRESS_H
+
+#include "internal.h"
+
+struct z_erofs_decompress_req {
+	char *in, *out;
+
+	/*
+	 * initial decompressed bytes that need to be skipped
+	 * when finally copying to output buffer
+	 */
+	unsigned int decodedskip;
+	unsigned int inputsize, decodedlength;
+
+	/* indicate the algorithm will be used for decompression */
+	unsigned int alg;
+	bool partial_decoding;
+};
+
+int z_erofs_decompress(struct z_erofs_decompress_req *rq);
+
+#endif
diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h
new file mode 100644
index 00000000000..6b62c7a4f5f
--- /dev/null
+++ b/fs/erofs/erofs_fs.h
@@ -0,0 +1,436 @@
+/* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */
+/*
+ * EROFS (Enhanced ROM File System) on-disk format definition
+ *
+ * Copyright (C) 2017-2018 HUAWEI, Inc.
+ *             http://www.huawei.com/
+ * Copyright (C) 2021, Alibaba Cloud
+ */
+#ifndef __EROFS_FS_H
+#define __EROFS_FS_H
+
+#include <asm/unaligned.h>
+#include <fs.h>
+#include <part.h>
+#include <stdint.h>
+#include <compiler.h>
+
+#define EROFS_SUPER_MAGIC_V1    0xE0F5E1E2
+#define EROFS_SUPER_OFFSET      1024
+
+#define EROFS_FEATURE_COMPAT_SB_CHKSUM		0x00000001
+
+/*
+ * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
+ * be incompatible with this kernel version.
+ */
+#define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING	0x00000001
+#define EROFS_FEATURE_INCOMPAT_COMPR_CFGS	0x00000002
+#define EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER	0x00000002
+#define EROFS_FEATURE_INCOMPAT_CHUNKED_FILE	0x00000004
+#define EROFS_FEATURE_INCOMPAT_DEVICE_TABLE	0x00000008
+#define EROFS_ALL_FEATURE_INCOMPAT		\
+	(EROFS_FEATURE_INCOMPAT_LZ4_0PADDING | \
+	 EROFS_FEATURE_INCOMPAT_COMPR_CFGS | \
+	 EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER | \
+	 EROFS_FEATURE_INCOMPAT_CHUNKED_FILE | \
+	 EROFS_FEATURE_INCOMPAT_DEVICE_TABLE)
+
+#define EROFS_SB_EXTSLOT_SIZE	16
+
+struct erofs_deviceslot {
+	union {
+		u8 uuid[16];		/* used for device manager later */
+		u8 userdata[64];	/* digest(sha256), etc. */
+	} u;
+	__le32 blocks;			/* total fs blocks of this device */
+	__le32 mapped_blkaddr;		/* map starting at mapped_blkaddr */
+	u8 reserved[56];
+};
+
+#define EROFS_DEVT_SLOT_SIZE	sizeof(struct erofs_deviceslot)
+
+/* erofs on-disk super block (currently 128 bytes) */
+struct erofs_super_block {
+	__le32 magic;           /* file system magic number */
+	__le32 checksum;        /* crc32c(super_block) */
+	__le32 feature_compat;
+	__u8 blkszbits;         /* support block_size == PAGE_SIZE only */
+	__u8 sb_extslots;	/* superblock size = 128 + sb_extslots * 16 */
+
+	__le16 root_nid;	/* nid of root directory */
+	__le64 inos;            /* total valid ino # (== f_files - f_favail) */
+
+	__le64 build_time;      /* inode v1 time derivation */
+	__le32 build_time_nsec;	/* inode v1 time derivation in nano scale */
+	__le32 blocks;          /* used for statfs */
+	__le32 meta_blkaddr;	/* start block address of metadata area */
+	__le32 xattr_blkaddr;	/* start block address of shared xattr area */
+	__u8 uuid[16];          /* 128-bit uuid for volume */
+	__u8 volume_name[16];   /* volume name */
+	__le32 feature_incompat;
+	union {
+		/* bitmap for available compression algorithms */
+		__le16 available_compr_algs;
+		/* customized sliding window size instead of 64k by default */
+		__le16 lz4_max_distance;
+	} __packed u1;
+	__le16 extra_devices;	/* # of devices besides the primary device */
+	__le16 devt_slotoff;	/* startoff = devt_slotoff * devt_slotsize */
+	__u8 reserved2[38];
+};
+
+/*
+ * erofs inode datalayout (i_format in on-disk inode):
+ * 0 - inode plain without inline data A:
+ * inode, [xattrs], ... | ... | no-holed data
+ * 1 - inode VLE compression B (legacy):
+ * inode, [xattrs], extents ... | ...
+ * 2 - inode plain with inline data C:
+ * inode, [xattrs], last_inline_data, ... | ... | no-holed data
+ * 3 - inode compression D:
+ * inode, [xattrs], map_header, extents ... | ...
+ * 4 - inode chunk-based E:
+ * inode, [xattrs], chunk indexes ... | ...
+ * 5~7 - reserved
+ */
+enum {
+	EROFS_INODE_FLAT_PLAIN			= 0,
+	EROFS_INODE_FLAT_COMPRESSION_LEGACY	= 1,
+	EROFS_INODE_FLAT_INLINE			= 2,
+	EROFS_INODE_FLAT_COMPRESSION		= 3,
+	EROFS_INODE_CHUNK_BASED			= 4,
+	EROFS_INODE_DATALAYOUT_MAX
+};
+
+static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
+{
+	return datamode == EROFS_INODE_FLAT_COMPRESSION ||
+		datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY;
+}
+
+/* bit definitions of inode i_advise */
+#define EROFS_I_VERSION_BITS            1
+#define EROFS_I_DATALAYOUT_BITS         3
+
+#define EROFS_I_VERSION_BIT             0
+#define EROFS_I_DATALAYOUT_BIT          1
+
+#define EROFS_I_ALL	\
+	((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1)
+
+/* indicate chunk blkbits, thus 'chunksize = blocksize << chunk blkbits' */
+#define EROFS_CHUNK_FORMAT_BLKBITS_MASK		0x001F
+/* with chunk indexes or just a 4-byte blkaddr array */
+#define EROFS_CHUNK_FORMAT_INDEXES		0x0020
+
+#define EROFS_CHUNK_FORMAT_ALL	\
+	(EROFS_CHUNK_FORMAT_BLKBITS_MASK | EROFS_CHUNK_FORMAT_INDEXES)
+
+struct erofs_inode_chunk_info {
+	__le16 format;		/* chunk blkbits, etc. */
+	__le16 reserved;
+};
+
+/* 32-byte reduced form of an ondisk inode */
+struct erofs_inode_compact {
+	__le16 i_format;	/* inode format hints */
+
+/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
+	__le16 i_xattr_icount;
+	__le16 i_mode;
+	__le16 i_nlink;
+	__le32 i_size;
+	__le32 i_reserved;
+	union {
+		/* file total compressed blocks for data mapping 1 */
+		__le32 compressed_blocks;
+		__le32 raw_blkaddr;
+
+		/* for device files, used to indicate old/new device # */
+		__le32 rdev;
+
+		/* for chunk-based files, it contains the summary info */
+		struct erofs_inode_chunk_info c;
+	} i_u;
+	__le32 i_ino;           /* only used for 32-bit stat compatibility */
+	__le16 i_uid;
+	__le16 i_gid;
+	__le32 i_reserved2;
+};
+
+/* 32 bytes on-disk inode */
+#define EROFS_INODE_LAYOUT_COMPACT	0
+/* 64 bytes on-disk inode */
+#define EROFS_INODE_LAYOUT_EXTENDED	1
+
+/* 64-byte complete form of an ondisk inode */
+struct erofs_inode_extended {
+	__le16 i_format;	/* inode format hints */
+
+/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
+	__le16 i_xattr_icount;
+	__le16 i_mode;
+	__le16 i_reserved;
+	__le64 i_size;
+	union {
+		/* file total compressed blocks for data mapping 1 */
+		__le32 compressed_blocks;
+		__le32 raw_blkaddr;
+
+		/* for device files, used to indicate old/new device # */
+		__le32 rdev;
+
+		/* for chunk-based files, it contains the summary info */
+		struct erofs_inode_chunk_info c;
+	} i_u;
+
+	/* only used for 32-bit stat compatibility */
+	__le32 i_ino;
+
+	__le32 i_uid;
+	__le32 i_gid;
+	__le64 i_ctime;
+	__le32 i_ctime_nsec;
+	__le32 i_nlink;
+	__u8   i_reserved2[16];
+};
+
+#define EROFS_MAX_SHARED_XATTRS         (128)
+/* h_shared_count between 129 ... 255 are special # */
+#define EROFS_SHARED_XATTR_EXTENT       (255)
+
+/*
+ * inline xattrs (n == i_xattr_icount):
+ * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes
+ *          12 bytes           /                   \
+ *                            /                     \
+ *                           /-----------------------\
+ *                           |  erofs_xattr_entries+ |
+ *                           +-----------------------+
+ * inline xattrs must starts in erofs_xattr_ibody_header,
+ * for read-only fs, no need to introduce h_refcount
+ */
+struct erofs_xattr_ibody_header {
+	__le32 h_reserved;
+	__u8   h_shared_count;
+	__u8   h_reserved2[7];
+	__le32 h_shared_xattrs[0];      /* shared xattr id array */
+};
+
+/* Name indexes */
+#define EROFS_XATTR_INDEX_USER              1
+#define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS  2
+#define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
+#define EROFS_XATTR_INDEX_TRUSTED           4
+#define EROFS_XATTR_INDEX_LUSTRE            5
+#define EROFS_XATTR_INDEX_SECURITY          6
+
+/* xattr entry (for both inline & shared xattrs) */
+struct erofs_xattr_entry {
+	__u8   e_name_len;      /* length of name */
+	__u8   e_name_index;    /* attribute name index */
+	__le16 e_value_size;    /* size of attribute value */
+	/* followed by e_name and e_value */
+	char   e_name[0];       /* attribute name */
+};
+
+static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
+{
+	if (!i_xattr_icount)
+		return 0;
+
+	return sizeof(struct erofs_xattr_ibody_header) +
+		sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1);
+}
+
+#define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
+
+static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e)
+{
+	return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) +
+				 e->e_name_len + le16_to_cpu(e->e_value_size));
+}
+
+/* represent a zeroed chunk (hole) */
+#define EROFS_NULL_ADDR			-1
+
+/* 4-byte block address array */
+#define EROFS_BLOCK_MAP_ENTRY_SIZE	sizeof(__le32)
+
+/* 8-byte inode chunk indexes */
+struct erofs_inode_chunk_index {
+	__le16 advise;		/* always 0, don't care for now */
+	__le16 device_id;	/* back-end storage id (with bits masked) */
+	__le32 blkaddr;		/* start block address of this inode chunk */
+};
+
+/* maximum supported size of a physical compression cluster */
+#define Z_EROFS_PCLUSTER_MAX_SIZE	(1024 * 1024)
+
+/* available compression algorithm types (for h_algorithmtype) */
+enum {
+	Z_EROFS_COMPRESSION_LZ4		= 0,
+	Z_EROFS_COMPRESSION_LZMA	= 1,
+	Z_EROFS_COMPRESSION_MAX
+};
+
+#define Z_EROFS_ALL_COMPR_ALGS		(1 << (Z_EROFS_COMPRESSION_MAX - 1))
+
+/* 14 bytes (+ length field = 16 bytes) */
+struct z_erofs_lz4_cfgs {
+	__le16 max_distance;
+	__le16 max_pclusterblks;
+	u8 reserved[10];
+} __packed;
+
+/* 14 bytes (+ length field = 16 bytes) */
+struct z_erofs_lzma_cfgs {
+	__le32 dict_size;
+	__le16 format;
+	u8 reserved[8];
+} __packed;
+#define Z_EROFS_LZMA_MAX_DICT_SIZE	(8 * Z_EROFS_PCLUSTER_MAX_SIZE)
+
+/*
+ * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
+ *  e.g. for 4k logical cluster size,      4B        if compacted 2B is off;
+ *                                  (4B) + 2B + (4B) if compacted 2B is on.
+ * bit 1 : HEAD1 big pcluster (0 - off; 1 - on)
+ * bit 2 : HEAD2 big pcluster (0 - off; 1 - on)
+ */
+#define Z_EROFS_ADVISE_COMPACTED_2B		0x0001
+#define Z_EROFS_ADVISE_BIG_PCLUSTER_1		0x0002
+#define Z_EROFS_ADVISE_BIG_PCLUSTER_2		0x0004
+
+struct z_erofs_map_header {
+	__le32	h_reserved1;
+	__le16	h_advise;
+	/*
+	 * bit 0-3 : algorithm type of head 1 (logical cluster type 01);
+	 * bit 4-7 : algorithm type of head 2 (logical cluster type 11).
+	 */
+	__u8	h_algorithmtype;
+	/*
+	 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
+	 * bit 3-7 : reserved.
+	 */
+	__u8	h_clusterbits;
+};
+
+#define Z_EROFS_VLE_LEGACY_HEADER_PADDING       8
+
+/*
+ * Fixed-sized output compression ondisk Logical Extent cluster type:
+ *    0 - literal (uncompressed) cluster
+ *    1 - compressed cluster (for the head logical cluster)
+ *    2 - compressed cluster (for the other logical clusters)
+ *
+ * In detail,
+ *    0 - literal (uncompressed) cluster,
+ *        di_advise = 0
+ *        di_clusterofs = the literal data offset of the cluster
+ *        di_blkaddr = the blkaddr of the literal cluster
+ *
+ *    1 - compressed cluster (for the head logical cluster)
+ *        di_advise = 1
+ *        di_clusterofs = the decompressed data offset of the cluster
+ *        di_blkaddr = the blkaddr of the compressed cluster
+ *
+ *    2 - compressed cluster (for the other logical clusters)
+ *        di_advise = 2
+ *        di_clusterofs =
+ *           the decompressed data offset in its own head cluster
+ *        di_u.delta[0] = distance to its corresponding head cluster
+ *        di_u.delta[1] = distance to its corresponding tail cluster
+ *                (di_advise could be 0, 1 or 2)
+ */
+enum {
+	Z_EROFS_VLE_CLUSTER_TYPE_PLAIN		= 0,
+	Z_EROFS_VLE_CLUSTER_TYPE_HEAD		= 1,
+	Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD	= 2,
+	Z_EROFS_VLE_CLUSTER_TYPE_RESERVED	= 3,
+	Z_EROFS_VLE_CLUSTER_TYPE_MAX
+};
+
+#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS        2
+#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT         0
+
+/*
+ * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the
+ * compressed block count of a compressed extent (in logical clusters, aka.
+ * block count of a pcluster).
+ */
+#define Z_EROFS_VLE_DI_D0_CBLKCNT		(1 << 11)
+
+struct z_erofs_vle_decompressed_index {
+	__le16 di_advise;
+	/* where to decompress in the head cluster */
+	__le16 di_clusterofs;
+
+	union {
+		/* for the head cluster */
+		__le32 blkaddr;
+		/*
+		 * for the rest clusters
+		 * eg. for 4k page-sized cluster, maximum 4K*64k = 256M)
+		 * [0] - pointing to the head cluster
+		 * [1] - pointing to the tail cluster
+		 */
+		__le16 delta[2];
+	} di_u;
+};
+
+#define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \
+	(round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \
+	 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING)
+
+#define Z_EROFS_VLE_EXTENT_ALIGN(size) round_up(size, \
+	sizeof(struct z_erofs_vle_decompressed_index))
+
+/* dirent sorts in alphabet order, thus we can do binary search */
+struct erofs_dirent {
+	__le64 nid;     /* node number */
+	__le16 nameoff; /* start offset of file name */
+	__u8 file_type; /* file type */
+	__u8 reserved;  /* reserved */
+} __packed;
+
+/* file types used in inode_info->flags */
+enum {
+	EROFS_FT_UNKNOWN,
+	EROFS_FT_REG_FILE,
+	EROFS_FT_DIR,
+	EROFS_FT_CHRDEV,
+	EROFS_FT_BLKDEV,
+	EROFS_FT_FIFO,
+	EROFS_FT_SOCK,
+	EROFS_FT_SYMLINK,
+	EROFS_FT_MAX
+};
+
+#define EROFS_NAME_LEN      255
+
+/* check the EROFS on-disk layout strictly at compile time */
+static inline void erofs_check_ondisk_layout_definitions(void)
+{
+	BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
+	BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32);
+	BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64);
+	BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
+	BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
+	BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_info) != 4);
+	BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) != 8);
+	BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8);
+	BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
+	BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
+	/* keep in sync between 2 index structures for better extendibility */
+	BUILD_BUG_ON(sizeof(struct erofs_inode_chunk_index) !=
+		     sizeof(struct z_erofs_vle_decompressed_index));
+	BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128);
+
+	BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) <
+		     Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1);
+}
+
+#endif
diff --git a/fs/erofs/fs.c b/fs/erofs/fs.c
new file mode 100644
index 00000000000..89269750f8b
--- /dev/null
+++ b/fs/erofs/fs.c
@@ -0,0 +1,267 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include "internal.h"
+#include <fs_internal.h>
+
+struct erofs_sb_info sbi;
+
+static struct erofs_ctxt {
+	struct disk_partition cur_part_info;
+	struct blk_desc *cur_dev;
+} ctxt;
+
+int erofs_dev_read(int device_id, void *buf, u64 offset, size_t len)
+{
+	lbaint_t sect = offset >> ctxt.cur_dev->log2blksz;
+	int off = offset & (ctxt.cur_dev->blksz - 1);
+
+	if (!ctxt.cur_dev)
+		return -EIO;
+
+	if (fs_devread(ctxt.cur_dev, &ctxt.cur_part_info, sect,
+		       off, len, buf))
+		return 0;
+	return -EIO;
+}
+
+int erofs_blk_read(void *buf, erofs_blk_t start, u32 nblocks)
+{
+	return erofs_dev_read(0, buf, blknr_to_addr(start),
+			 blknr_to_addr(nblocks));
+}
+
+int erofs_probe(struct blk_desc *fs_dev_desc,
+		struct disk_partition *fs_partition)
+{
+	int ret;
+
+	ctxt.cur_dev = fs_dev_desc;
+	ctxt.cur_part_info = *fs_partition;
+
+	ret = erofs_read_superblock();
+	if (ret)
+		goto error;
+
+	return 0;
+error:
+	ctxt.cur_dev = NULL;
+	return ret;
+}
+
+struct erofs_dir_stream {
+	struct fs_dir_stream fs_dirs;
+	struct fs_dirent dirent;
+
+	struct erofs_inode inode;
+	char dblk[EROFS_BLKSIZ];
+	unsigned int maxsize, de_end;
+	erofs_off_t pos;
+};
+
+static int erofs_readlink(struct erofs_inode *vi)
+{
+	size_t len = vi->i_size;
+	char *target;
+	int err;
+
+	target = malloc(len + 1);
+	if (!target)
+		return -ENOMEM;
+	target[len] = '\0';
+
+	err = erofs_pread(vi, target, len, 0);
+	if (err)
+		goto err_out;
+
+	err = erofs_ilookup(target, vi);
+	if (err)
+		goto err_out;
+
+err_out:
+	free(target);
+	return err;
+}
+
+int erofs_opendir(const char *filename, struct fs_dir_stream **dirsp)
+{
+	struct erofs_dir_stream *dirs;
+	int err;
+
+	dirs = calloc(1, sizeof(*dirs));
+	if (!dirs)
+		return -ENOMEM;
+
+	err = erofs_ilookup(filename, &dirs->inode);
+	if (err)
+		goto err_out;
+
+	if (S_ISLNK(dirs->inode.i_mode)) {
+		err = erofs_readlink(&dirs->inode);
+		if (err)
+			goto err_out;
+	}
+
+	if (!S_ISDIR(dirs->inode.i_mode)) {
+		err = -ENOTDIR;
+		goto err_out;
+	}
+	*dirsp = (struct fs_dir_stream *)dirs;
+	return 0;
+err_out:
+	free(dirs);
+	return err;
+}
+
+int erofs_readdir(struct fs_dir_stream *fs_dirs, struct fs_dirent **dentp)
+{
+	struct erofs_dir_stream *dirs = (struct erofs_dir_stream *)fs_dirs;
+	struct fs_dirent *dent = &dirs->dirent;
+	erofs_off_t pos = dirs->pos;
+	unsigned int nameoff, de_namelen;
+	struct erofs_dirent *de;
+	char *de_name;
+	int err;
+
+	if (pos >= dirs->inode.i_size)
+		return 1;
+
+	if (!dirs->maxsize) {
+		dirs->maxsize = min_t(unsigned int, EROFS_BLKSIZ,
+				      dirs->inode.i_size - pos);
+
+		err = erofs_pread(&dirs->inode, dirs->dblk,
+				  dirs->maxsize, pos);
+		if (err)
+			return err;
+
+		de = (struct erofs_dirent *)dirs->dblk;
+		dirs->de_end = le16_to_cpu(de->nameoff);
+		if (dirs->de_end < sizeof(struct erofs_dirent) ||
+		    dirs->de_end >= EROFS_BLKSIZ) {
+			erofs_err("invalid de[0].nameoff %u @ nid %llu",
+				  dirs->de_end, de->nid | 0ULL);
+			return -EFSCORRUPTED;
+		}
+	}
+
+	de = (struct erofs_dirent *)(dirs->dblk + erofs_blkoff(pos));
+	nameoff = le16_to_cpu(de->nameoff);
+	de_name = (char *)dirs->dblk + nameoff;
+
+	/* the last dirent in the block? */
+	if (de + 1 >= (struct erofs_dirent *)(dirs->dblk + dirs->de_end))
+		de_namelen = strnlen(de_name, dirs->maxsize - nameoff);
+	else
+		de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
+
+	/* a corrupted entry is found */
+	if (nameoff + de_namelen > dirs->maxsize ||
+	    de_namelen > EROFS_NAME_LEN) {
+		erofs_err("bogus dirent @ nid %llu", de->nid | 0ULL);
+		DBG_BUGON(1);
+		return -EFSCORRUPTED;
+	}
+
+	memcpy(dent->name, de_name, de_namelen);
+	dent->name[de_namelen] = '\0';
+
+	if (de->file_type == EROFS_FT_DIR) {
+		dent->type = FS_DT_DIR;
+	} else if (de->file_type == EROFS_FT_SYMLINK) {
+		dent->type = FS_DT_LNK;
+	} else {
+		struct erofs_inode vi;
+
+		dent->type = FS_DT_REG;
+		vi.nid = de->nid;
+
+		err = erofs_read_inode_from_disk(&vi);
+		if (err)
+			return err;
+		dent->size = vi.i_size;
+	}
+	*dentp = dent;
+
+	pos += sizeof(*de);
+	if (erofs_blkoff(pos) >= dirs->de_end) {
+		pos = blknr_to_addr(erofs_blknr(pos) + 1);
+		dirs->maxsize = 0;
+	}
+	dirs->pos = pos;
+	return 0;
+}
+
+void erofs_closedir(struct fs_dir_stream *fs_dirs)
+{
+	free(fs_dirs);
+}
+
+int erofs_exists(const char *filename)
+{
+	struct erofs_inode vi;
+	int err;
+
+	err = erofs_ilookup(filename, &vi);
+	return err == 0;
+}
+
+int erofs_size(const char *filename, loff_t *size)
+{
+	struct erofs_inode vi;
+	int err;
+
+	err = erofs_ilookup(filename, &vi);
+	if (err)
+		return err;
+	*size = vi.i_size;
+	return 0;
+}
+
+int erofs_read(const char *filename, void *buf, loff_t offset, loff_t len,
+	       loff_t *actread)
+{
+	struct erofs_inode vi;
+	int err;
+
+	err = erofs_ilookup(filename, &vi);
+	if (err)
+		return err;
+
+	if (S_ISLNK(vi.i_mode)) {
+		err = erofs_readlink(&vi);
+		if (err)
+			return err;
+	}
+
+	if (!len)
+		len = vi.i_size;
+
+	err = erofs_pread(&vi, buf, len, offset);
+	if (err) {
+		*actread = 0;
+		return err;
+	}
+
+	if (offset >= vi.i_size)
+		*actread = 0;
+	else if (offset + len > vi.i_size)
+		*actread = vi.i_size - offset;
+	else
+		*actread = len;
+	return 0;
+}
+
+void erofs_close(void)
+{
+	ctxt.cur_dev = NULL;
+}
+
+int erofs_uuid(char *uuid_str)
+{
+	if (IS_ENABLED(CONFIG_LIB_UUID)) {
+		if (ctxt.cur_dev)
+			uuid_bin_to_str(sbi.uuid, uuid_str,
+					UUID_STR_FORMAT_STD);
+		return 0;
+	}
+	return -ENOSYS;
+}
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
new file mode 100644
index 00000000000..4af7c91560c
--- /dev/null
+++ b/fs/erofs/internal.h
@@ -0,0 +1,313 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef __EROFS_INTERNAL_H
+#define __EROFS_INTERNAL_H
+
+#define __packed __attribute__((__packed__))
+
+#include <linux/stat.h>
+#include <linux/bug.h>
+#include <linux/err.h>
+#include <linux/printk.h>
+#include <linux/log2.h>
+#include <inttypes.h>
+#include "erofs_fs.h"
+
+#define erofs_err(fmt, ...)	\
+	pr_err(fmt "\n", ##__VA_ARGS__)
+
+#define erofs_info(fmt, ...)	\
+	pr_info(fmt "\n", ##__VA_ARGS__)
+
+#define erofs_dbg(fmt, ...)	\
+	pr_debug(fmt "\n", ##__VA_ARGS__)
+
+#define DBG_BUGON(condition)	BUG_ON(condition)
+
+/* no obvious reason to support explicit PAGE_SIZE != 4096 for now */
+#if PAGE_SIZE != 4096
+#error incompatible PAGE_SIZE is already defined
+#endif
+
+#define PAGE_MASK		(~(PAGE_SIZE - 1))
+
+#define LOG_BLOCK_SIZE          (12)
+#define EROFS_BLKSIZ            (1U << LOG_BLOCK_SIZE)
+
+#define EROFS_ISLOTBITS		5
+#define EROFS_SLOTSIZE		(1U << EROFS_ISLOTBITS)
+
+typedef u64 erofs_off_t;
+typedef u64 erofs_nid_t;
+/* data type for filesystem-wide blocks number */
+typedef u32 erofs_blk_t;
+
+#define NULL_ADDR	((unsigned int)-1)
+#define NULL_ADDR_UL	((unsigned long)-1)
+
+#define erofs_blknr(addr)       ((addr) / EROFS_BLKSIZ)
+#define erofs_blkoff(addr)      ((addr) % EROFS_BLKSIZ)
+#define blknr_to_addr(nr)       ((erofs_off_t)(nr) * EROFS_BLKSIZ)
+
+#define BLK_ROUND_UP(addr)	DIV_ROUND_UP(addr, EROFS_BLKSIZ)
+
+struct erofs_buffer_head;
+
+struct erofs_device_info {
+	u32 blocks;
+	u32 mapped_blkaddr;
+};
+
+struct erofs_sb_info {
+	struct erofs_device_info *devs;
+
+	u64 total_blocks;
+	u64 primarydevice_blocks;
+
+	erofs_blk_t meta_blkaddr;
+	erofs_blk_t xattr_blkaddr;
+
+	u32 feature_compat;
+	u32 feature_incompat;
+	u64 build_time;
+	u32 build_time_nsec;
+
+	unsigned char islotbits;
+
+	/* what we really care is nid, rather than ino.. */
+	erofs_nid_t root_nid;
+	/* used for statfs, f_files - f_favail */
+	u64 inos;
+
+	u8 uuid[16];
+
+	u16 available_compr_algs;
+	u16 lz4_max_distance;
+	u32 checksum;
+	u16 extra_devices;
+	union {
+		u16 devt_slotoff;		/* used for mkfs */
+		u16 device_id_mask;		/* used for others */
+	};
+};
+
+/* global sbi */
+extern struct erofs_sb_info sbi;
+
+static inline erofs_off_t iloc(erofs_nid_t nid)
+{
+	return blknr_to_addr(sbi.meta_blkaddr) + (nid << sbi.islotbits);
+}
+
+#define EROFS_FEATURE_FUNCS(name, compat, feature) \
+static inline bool erofs_sb_has_##name(void) \
+{ \
+	return sbi.feature_##compat & EROFS_FEATURE_##feature; \
+} \
+static inline void erofs_sb_set_##name(void) \
+{ \
+	sbi.feature_##compat |= EROFS_FEATURE_##feature; \
+} \
+static inline void erofs_sb_clear_##name(void) \
+{ \
+	sbi.feature_##compat &= ~EROFS_FEATURE_##feature; \
+}
+
+EROFS_FEATURE_FUNCS(lz4_0padding, incompat, INCOMPAT_LZ4_0PADDING)
+EROFS_FEATURE_FUNCS(compr_cfgs, incompat, INCOMPAT_COMPR_CFGS)
+EROFS_FEATURE_FUNCS(big_pcluster, incompat, INCOMPAT_BIG_PCLUSTER)
+EROFS_FEATURE_FUNCS(chunked_file, incompat, INCOMPAT_CHUNKED_FILE)
+EROFS_FEATURE_FUNCS(device_table, incompat, INCOMPAT_DEVICE_TABLE)
+EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)
+
+#define EROFS_I_EA_INITED	(1 << 0)
+#define EROFS_I_Z_INITED	(1 << 1)
+
+struct erofs_inode {
+	struct list_head i_hash, i_subdirs, i_xattrs;
+
+	union {
+		/* (erofsfuse) runtime flags */
+		unsigned int flags;
+		/* (mkfs.erofs) device ID containing source file */
+		u32 dev;
+	};
+	unsigned int i_count;
+	struct erofs_inode *i_parent;
+
+	umode_t i_mode;
+	erofs_off_t i_size;
+
+	u64 i_ino[2];
+	u32 i_uid;
+	u32 i_gid;
+	u64 i_ctime;
+	u32 i_ctime_nsec;
+	u32 i_nlink;
+
+	union {
+		u32 i_blkaddr;
+		u32 i_blocks;
+		u32 i_rdev;
+		struct {
+			unsigned short	chunkformat;
+			unsigned char	chunkbits;
+		};
+	} u;
+
+	unsigned char datalayout;
+	unsigned char inode_isize;
+	/* inline tail-end packing size */
+	unsigned short idata_size;
+
+	unsigned int xattr_isize;
+	unsigned int extent_isize;
+
+	erofs_nid_t nid;
+	struct erofs_buffer_head *bh;
+	struct erofs_buffer_head *bh_inline, *bh_data;
+
+	void *idata;
+
+	union {
+		void *compressmeta;
+		void *chunkindexes;
+		struct {
+			uint16_t z_advise;
+			uint8_t  z_algorithmtype[2];
+			uint8_t  z_logical_clusterbits;
+			uint8_t  z_physical_clusterblks;
+		};
+	};
+};
+
+static inline bool is_inode_layout_compression(struct erofs_inode *inode)
+{
+	return erofs_inode_is_data_compressed(inode->datalayout);
+}
+
+static inline unsigned int erofs_bitrange(unsigned int value, unsigned int bit,
+					  unsigned int bits)
+{
+	return (value >> bit) & ((1 << bits) - 1);
+}
+
+static inline unsigned int erofs_inode_version(unsigned int value)
+{
+	return erofs_bitrange(value, EROFS_I_VERSION_BIT,
+			      EROFS_I_VERSION_BITS);
+}
+
+static inline unsigned int erofs_inode_datalayout(unsigned int value)
+{
+	return erofs_bitrange(value, EROFS_I_DATALAYOUT_BIT,
+			      EROFS_I_DATALAYOUT_BITS);
+}
+
+#define IS_ROOT(x)	((x) == (x)->i_parent)
+
+struct erofs_dentry {
+	struct list_head d_child;	/* child of parent list */
+
+	unsigned int type;
+	char name[EROFS_NAME_LEN];
+	union {
+		struct erofs_inode *inode;
+		erofs_nid_t nid;
+	};
+};
+
+static inline bool is_dot_dotdot(const char *name)
+{
+	if (name[0] != '.')
+		return false;
+
+	return name[1] == '\0' || (name[1] == '.' && name[2] == '\0');
+}
+
+enum {
+	BH_Meta,
+	BH_Mapped,
+	BH_Encoded,
+	BH_FullMapped,
+};
+
+/* Has a disk mapping */
+#define EROFS_MAP_MAPPED	(1 << BH_Mapped)
+/* Located in metadata (could be copied from bd_inode) */
+#define EROFS_MAP_META		(1 << BH_Meta)
+/* The extent is encoded */
+#define EROFS_MAP_ENCODED	(1 << BH_Encoded)
+/* The length of extent is full */
+#define EROFS_MAP_FULL_MAPPED	(1 << BH_FullMapped)
+
+struct erofs_map_blocks {
+	char mpage[EROFS_BLKSIZ];
+
+	erofs_off_t m_pa, m_la;
+	u64 m_plen, m_llen;
+
+	unsigned short m_deviceid;
+	char m_algorithmformat;
+	unsigned int m_flags;
+	erofs_blk_t index;
+};
+
+/*
+ * Used to get the exact decompressed length, e.g. fiemap (consider lookback
+ * approach instead if possible since it's more metadata lightweight.)
+ */
+#define EROFS_GET_BLOCKS_FIEMAP	0x0002
+
+enum {
+	Z_EROFS_COMPRESSION_SHIFTED = Z_EROFS_COMPRESSION_MAX,
+	Z_EROFS_COMPRESSION_RUNTIME_MAX
+};
+
+struct erofs_map_dev {
+	erofs_off_t m_pa;
+	unsigned int m_deviceid;
+};
+
+/* fs.c */
+int erofs_blk_read(void *buf, erofs_blk_t start, u32 nblocks);
+int erofs_dev_read(int device_id, void *buf, u64 offset, size_t len);
+
+/* super.c */
+int erofs_read_superblock(void);
+
+/* namei.c */
+int erofs_read_inode_from_disk(struct erofs_inode *vi);
+int erofs_ilookup(const char *path, struct erofs_inode *vi);
+int erofs_read_inode_from_disk(struct erofs_inode *vi);
+
+/* data.c */
+int erofs_pread(struct erofs_inode *inode, char *buf,
+		erofs_off_t count, erofs_off_t offset);
+int erofs_map_blocks(struct erofs_inode *inode,
+		     struct erofs_map_blocks *map, int flags);
+int erofs_map_dev(struct erofs_sb_info *sbi, struct erofs_map_dev *map);
+/* zmap.c */
+int z_erofs_fill_inode(struct erofs_inode *vi);
+int z_erofs_map_blocks_iter(struct erofs_inode *vi,
+			    struct erofs_map_blocks *map, int flags);
+
+#ifdef EUCLEAN
+#define EFSCORRUPTED	EUCLEAN		/* Filesystem is corrupted */
+#else
+#define EFSCORRUPTED	EIO
+#endif
+
+#define CRC32C_POLY_LE	0x82F63B78
+static inline u32 erofs_crc32c(u32 crc, const u8 *in, size_t len)
+{
+	int i;
+
+	while (len--) {
+		crc ^= *in++;
+		for (i = 0; i < 8; i++)
+			crc = (crc >> 1) ^ ((crc & 1) ? CRC32C_POLY_LE : 0);
+	}
+	return crc;
+}
+
+#endif
diff --git a/fs/erofs/namei.c b/fs/erofs/namei.c
new file mode 100644
index 00000000000..d1d4757c507
--- /dev/null
+++ b/fs/erofs/namei.c
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include "internal.h"
+
+int erofs_read_inode_from_disk(struct erofs_inode *vi)
+{
+	int ret, ifmt;
+	char buf[sizeof(struct erofs_inode_extended)];
+	struct erofs_inode_compact *dic;
+	struct erofs_inode_extended *die;
+	const erofs_off_t inode_loc = iloc(vi->nid);
+
+	ret = erofs_dev_read(0, buf, inode_loc, sizeof(*dic));
+	if (ret < 0)
+		return -EIO;
+
+	dic = (struct erofs_inode_compact *)buf;
+	ifmt = le16_to_cpu(dic->i_format);
+
+	vi->datalayout = erofs_inode_datalayout(ifmt);
+	if (vi->datalayout >= EROFS_INODE_DATALAYOUT_MAX) {
+		erofs_err("unsupported datalayout %u of nid %llu",
+			  vi->datalayout, vi->nid | 0ULL);
+		return -EOPNOTSUPP;
+	}
+	switch (erofs_inode_version(ifmt)) {
+	case EROFS_INODE_LAYOUT_EXTENDED:
+		vi->inode_isize = sizeof(struct erofs_inode_extended);
+
+		ret = erofs_dev_read(0, buf + sizeof(*dic), inode_loc + sizeof(*dic),
+				     sizeof(*die) - sizeof(*dic));
+		if (ret < 0)
+			return -EIO;
+
+		die = (struct erofs_inode_extended *)buf;
+		vi->xattr_isize = erofs_xattr_ibody_size(die->i_xattr_icount);
+		vi->i_mode = le16_to_cpu(die->i_mode);
+
+		switch (vi->i_mode & S_IFMT) {
+		case S_IFREG:
+		case S_IFDIR:
+		case S_IFLNK:
+			vi->u.i_blkaddr = le32_to_cpu(die->i_u.raw_blkaddr);
+			break;
+		case S_IFCHR:
+		case S_IFBLK:
+			vi->u.i_rdev = 0;
+			break;
+		case S_IFIFO:
+		case S_IFSOCK:
+			vi->u.i_rdev = 0;
+			break;
+		default:
+			goto bogusimode;
+		}
+
+		vi->i_uid = le32_to_cpu(die->i_uid);
+		vi->i_gid = le32_to_cpu(die->i_gid);
+		vi->i_nlink = le32_to_cpu(die->i_nlink);
+
+		vi->i_ctime = le64_to_cpu(die->i_ctime);
+		vi->i_ctime_nsec = le64_to_cpu(die->i_ctime_nsec);
+		vi->i_size = le64_to_cpu(die->i_size);
+		if (vi->datalayout == EROFS_INODE_CHUNK_BASED)
+			/* fill chunked inode summary info */
+			vi->u.chunkformat = le16_to_cpu(die->i_u.c.format);
+		break;
+	case EROFS_INODE_LAYOUT_COMPACT:
+		vi->inode_isize = sizeof(struct erofs_inode_compact);
+		vi->xattr_isize = erofs_xattr_ibody_size(dic->i_xattr_icount);
+		vi->i_mode = le16_to_cpu(dic->i_mode);
+
+		switch (vi->i_mode & S_IFMT) {
+		case S_IFREG:
+		case S_IFDIR:
+		case S_IFLNK:
+			vi->u.i_blkaddr = le32_to_cpu(dic->i_u.raw_blkaddr);
+			break;
+		case S_IFCHR:
+		case S_IFBLK:
+			vi->u.i_rdev = 0;
+			break;
+		case S_IFIFO:
+		case S_IFSOCK:
+			vi->u.i_rdev = 0;
+			break;
+		default:
+			goto bogusimode;
+		}
+
+		vi->i_uid = le16_to_cpu(dic->i_uid);
+		vi->i_gid = le16_to_cpu(dic->i_gid);
+		vi->i_nlink = le16_to_cpu(dic->i_nlink);
+
+		vi->i_ctime = sbi.build_time;
+		vi->i_ctime_nsec = sbi.build_time_nsec;
+
+		vi->i_size = le32_to_cpu(dic->i_size);
+		if (vi->datalayout == EROFS_INODE_CHUNK_BASED)
+			vi->u.chunkformat = le16_to_cpu(dic->i_u.c.format);
+		break;
+	default:
+		erofs_err("unsupported on-disk inode version %u of nid %llu",
+			  erofs_inode_version(ifmt), vi->nid | 0ULL);
+		return -EOPNOTSUPP;
+	}
+
+	vi->flags = 0;
+	if (vi->datalayout == EROFS_INODE_CHUNK_BASED) {
+		if (vi->u.chunkformat & ~EROFS_CHUNK_FORMAT_ALL) {
+			erofs_err("unsupported chunk format %x of nid %llu",
+				  vi->u.chunkformat, vi->nid | 0ULL);
+			return -EOPNOTSUPP;
+		}
+		vi->u.chunkbits = LOG_BLOCK_SIZE +
+			(vi->u.chunkformat & EROFS_CHUNK_FORMAT_BLKBITS_MASK);
+	} else if (erofs_inode_is_data_compressed(vi->datalayout))
+		z_erofs_fill_inode(vi);
+	return 0;
+bogusimode:
+	erofs_err("bogus i_mode (%o) @ nid %llu", vi->i_mode, vi->nid | 0ULL);
+	return -EFSCORRUPTED;
+}
+
+struct erofs_dirent *find_target_dirent(erofs_nid_t pnid,
+					void *dentry_blk,
+					const char *name, unsigned int len,
+					unsigned int nameoff,
+					unsigned int maxsize)
+{
+	struct erofs_dirent *de = dentry_blk;
+	const struct erofs_dirent *end = dentry_blk + nameoff;
+
+	while (de < end) {
+		const char *de_name;
+		unsigned int de_namelen;
+
+		nameoff = le16_to_cpu(de->nameoff);
+		de_name = (char *)dentry_blk + nameoff;
+
+		/* the last dirent in the block? */
+		if (de + 1 >= end)
+			de_namelen = strnlen(de_name, maxsize - nameoff);
+		else
+			de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
+
+		/* a corrupted entry is found */
+		if (nameoff + de_namelen > maxsize ||
+		    de_namelen > EROFS_NAME_LEN) {
+			erofs_err("bogus dirent @ nid %llu", pnid | 0ULL);
+			DBG_BUGON(1);
+			return ERR_PTR(-EFSCORRUPTED);
+		}
+
+		if (len == de_namelen && !memcmp(de_name, name, de_namelen))
+			return de;
+		++de;
+	}
+	return NULL;
+}
+
+struct nameidata {
+	erofs_nid_t	nid;
+	unsigned int	ftype;
+};
+
+int erofs_namei(struct nameidata *nd,
+		const char *name, unsigned int len)
+{
+	erofs_nid_t nid = nd->nid;
+	int ret;
+	char buf[EROFS_BLKSIZ];
+	struct erofs_inode vi = { .nid = nid };
+	erofs_off_t offset;
+
+	ret = erofs_read_inode_from_disk(&vi);
+	if (ret)
+		return ret;
+
+	offset = 0;
+	while (offset < vi.i_size) {
+		erofs_off_t maxsize = min_t(erofs_off_t,
+					    vi.i_size - offset, EROFS_BLKSIZ);
+		struct erofs_dirent *de = (void *)buf;
+		unsigned int nameoff;
+
+		ret = erofs_pread(&vi, buf, maxsize, offset);
+		if (ret)
+			return ret;
+
+		nameoff = le16_to_cpu(de->nameoff);
+		if (nameoff < sizeof(struct erofs_dirent) ||
+		    nameoff >= PAGE_SIZE) {
+			erofs_err("invalid de[0].nameoff %u @ nid %llu",
+				  nameoff, nid | 0ULL);
+			return -EFSCORRUPTED;
+		}
+
+		de = find_target_dirent(nid, buf, name, len,
+					nameoff, maxsize);
+		if (IS_ERR(de))
+			return PTR_ERR(de);
+
+		if (de) {
+			nd->nid = le64_to_cpu(de->nid);
+			return 0;
+		}
+		offset += maxsize;
+	}
+	return -ENOENT;
+}
+
+static int link_path_walk(const char *name, struct nameidata *nd)
+{
+	nd->nid = sbi.root_nid;
+
+	while (*name == '/')
+		name++;
+
+	/* At this point we know we have a real path component. */
+	while (*name != '\0') {
+		const char *p = name;
+		int ret;
+
+		do {
+			++p;
+		} while (*p != '\0' && *p != '/');
+
+		DBG_BUGON(p <= name);
+		ret = erofs_namei(nd, name, p - name);
+		if (ret)
+			return ret;
+
+		name = p;
+		/* Skip until no more slashes. */
+		for (name = p; *name == '/'; ++name)
+			;
+	}
+	return 0;
+}
+
+int erofs_ilookup(const char *path, struct erofs_inode *vi)
+{
+	int ret;
+	struct nameidata nd;
+
+	ret = link_path_walk(path, &nd);
+	if (ret)
+		return ret;
+
+	vi->nid = nd.nid;
+	return erofs_read_inode_from_disk(vi);
+}
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
new file mode 100644
index 00000000000..4cca322b9ea
--- /dev/null
+++ b/fs/erofs/super.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include "internal.h"
+
+static bool check_layout_compatibility(struct erofs_sb_info *sbi,
+				       struct erofs_super_block *dsb)
+{
+	const unsigned int feature = le32_to_cpu(dsb->feature_incompat);
+
+	sbi->feature_incompat = feature;
+
+	/* check if current kernel meets all mandatory requirements */
+	if (feature & (~EROFS_ALL_FEATURE_INCOMPAT)) {
+		erofs_err("unidentified incompatible feature %x, please upgrade kernel version",
+			  feature & ~EROFS_ALL_FEATURE_INCOMPAT);
+		return false;
+	}
+	return true;
+}
+
+static int erofs_init_devices(struct erofs_sb_info *sbi,
+			      struct erofs_super_block *dsb)
+{
+	unsigned int ondisk_extradevs, i;
+	erofs_off_t pos;
+
+	sbi->total_blocks = sbi->primarydevice_blocks;
+
+	if (!erofs_sb_has_device_table())
+		ondisk_extradevs = 0;
+	else
+		ondisk_extradevs = le16_to_cpu(dsb->extra_devices);
+
+	if (ondisk_extradevs != sbi->extra_devices) {
+		erofs_err("extra devices don't match (ondisk %u, given %u)",
+			  ondisk_extradevs, sbi->extra_devices);
+		return -EINVAL;
+	}
+	if (!ondisk_extradevs)
+		return 0;
+
+	sbi->device_id_mask = roundup_pow_of_two(ondisk_extradevs + 1) - 1;
+	sbi->devs = calloc(ondisk_extradevs, sizeof(*sbi->devs));
+	pos = le16_to_cpu(dsb->devt_slotoff) * EROFS_DEVT_SLOT_SIZE;
+	for (i = 0; i < ondisk_extradevs; ++i) {
+		struct erofs_deviceslot dis;
+		int ret;
+
+		ret = erofs_dev_read(0, &dis, pos, sizeof(dis));
+		if (ret < 0)
+			return ret;
+
+		sbi->devs[i].mapped_blkaddr = dis.mapped_blkaddr;
+		sbi->total_blocks += dis.blocks;
+		pos += EROFS_DEVT_SLOT_SIZE;
+	}
+	return 0;
+}
+
+int erofs_read_superblock(void)
+{
+	char data[EROFS_BLKSIZ];
+	struct erofs_super_block *dsb;
+	unsigned int blkszbits;
+	int ret;
+
+	ret = erofs_blk_read(data, 0, 1);
+	if (ret < 0) {
+		erofs_err("cannot read erofs superblock: %d", ret);
+		return -EIO;
+	}
+	dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);
+
+	ret = -EINVAL;
+	if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
+		erofs_err("cannot find valid erofs superblock");
+		return ret;
+	}
+
+	sbi.feature_compat = le32_to_cpu(dsb->feature_compat);
+
+	blkszbits = dsb->blkszbits;
+	/* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
+	if (blkszbits != LOG_BLOCK_SIZE) {
+		erofs_err("blksize %u isn't supported on this platform",
+			  1 << blkszbits);
+		return ret;
+	}
+
+	if (!check_layout_compatibility(&sbi, dsb))
+		return ret;
+
+	sbi.primarydevice_blocks = le32_to_cpu(dsb->blocks);
+	sbi.meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
+	sbi.xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
+	sbi.islotbits = EROFS_ISLOTBITS;
+	sbi.root_nid = le16_to_cpu(dsb->root_nid);
+	sbi.inos = le64_to_cpu(dsb->inos);
+	sbi.checksum = le32_to_cpu(dsb->checksum);
+
+	sbi.build_time = le64_to_cpu(dsb->build_time);
+	sbi.build_time_nsec = le32_to_cpu(dsb->build_time_nsec);
+
+	memcpy(&sbi.uuid, dsb->uuid, sizeof(dsb->uuid));
+	return erofs_init_devices(&sbi, dsb);
+}
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
new file mode 100644
index 00000000000..be2599ac4f9
--- /dev/null
+++ b/fs/erofs/zmap.c
@@ -0,0 +1,601 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include "internal.h"
+
+int z_erofs_fill_inode(struct erofs_inode *vi)
+{
+	if (!erofs_sb_has_big_pcluster() &&
+	    vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY) {
+		vi->z_advise = 0;
+		vi->z_algorithmtype[0] = 0;
+		vi->z_algorithmtype[1] = 0;
+		vi->z_logical_clusterbits = LOG_BLOCK_SIZE;
+
+		vi->flags |= EROFS_I_Z_INITED;
+	}
+	return 0;
+}
+
+static int z_erofs_fill_inode_lazy(struct erofs_inode *vi)
+{
+	int ret;
+	erofs_off_t pos;
+	struct z_erofs_map_header *h;
+	char buf[sizeof(struct z_erofs_map_header)];
+
+	if (vi->flags & EROFS_I_Z_INITED)
+		return 0;
+
+	DBG_BUGON(!erofs_sb_has_big_pcluster() &&
+		  vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY);
+	pos = round_up(iloc(vi->nid) + vi->inode_isize + vi->xattr_isize, 8);
+
+	ret = erofs_dev_read(0, buf, pos, sizeof(buf));
+	if (ret < 0)
+		return -EIO;
+
+	h = (struct z_erofs_map_header *)buf;
+	vi->z_advise = le16_to_cpu(h->h_advise);
+	vi->z_algorithmtype[0] = h->h_algorithmtype & 15;
+	vi->z_algorithmtype[1] = h->h_algorithmtype >> 4;
+
+	if (vi->z_algorithmtype[0] >= Z_EROFS_COMPRESSION_MAX) {
+		erofs_err("unknown compression format %u for nid %llu",
+			  vi->z_algorithmtype[0], (unsigned long long)vi->nid);
+		return -EOPNOTSUPP;
+	}
+
+	vi->z_logical_clusterbits = LOG_BLOCK_SIZE + (h->h_clusterbits & 7);
+	if (vi->datalayout == EROFS_INODE_FLAT_COMPRESSION &&
+	    !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1) ^
+	    !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2)) {
+		erofs_err("big pcluster head1/2 of compact indexes should be consistent for nid %llu",
+			  vi->nid * 1ULL);
+		return -EFSCORRUPTED;
+	}
+	vi->flags |= EROFS_I_Z_INITED;
+	return 0;
+}
+
+struct z_erofs_maprecorder {
+	struct erofs_inode *inode;
+	struct erofs_map_blocks *map;
+	void *kaddr;
+
+	unsigned long lcn;
+	/* compression extent information gathered */
+	u8  type, headtype;
+	u16 clusterofs;
+	u16 delta[2];
+	erofs_blk_t pblk, compressedlcs;
+};
+
+static int z_erofs_reload_indexes(struct z_erofs_maprecorder *m,
+				  erofs_blk_t eblk)
+{
+	int ret;
+	struct erofs_map_blocks *const map = m->map;
+	char *mpage = map->mpage;
+
+	if (map->index == eblk)
+		return 0;
+
+	ret = erofs_blk_read(mpage, eblk, 1);
+	if (ret < 0)
+		return -EIO;
+
+	map->index = eblk;
+
+	return 0;
+}
+
+static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
+					 unsigned long lcn)
+{
+	struct erofs_inode *const vi = m->inode;
+	const erofs_off_t ibase = iloc(vi->nid);
+	const erofs_off_t pos =
+		Z_EROFS_VLE_LEGACY_INDEX_ALIGN(ibase + vi->inode_isize +
+					       vi->xattr_isize) +
+		lcn * sizeof(struct z_erofs_vle_decompressed_index);
+	struct z_erofs_vle_decompressed_index *di;
+	unsigned int advise, type;
+	int err;
+
+	err = z_erofs_reload_indexes(m, erofs_blknr(pos));
+	if (err)
+		return err;
+
+	m->lcn = lcn;
+	di = m->kaddr + erofs_blkoff(pos);
+
+	advise = le16_to_cpu(di->di_advise);
+	type = (advise >> Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT) &
+		((1 << Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) - 1);
+	switch (type) {
+	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		m->clusterofs = 1 << vi->z_logical_clusterbits;
+		m->delta[0] = le16_to_cpu(di->di_u.delta[0]);
+		if (m->delta[0] & Z_EROFS_VLE_DI_D0_CBLKCNT) {
+			if (!(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) {
+				DBG_BUGON(1);
+				return -EFSCORRUPTED;
+			}
+			m->compressedlcs = m->delta[0] &
+				~Z_EROFS_VLE_DI_D0_CBLKCNT;
+			m->delta[0] = 1;
+		}
+		m->delta[1] = le16_to_cpu(di->di_u.delta[1]);
+		break;
+	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+		m->clusterofs = le16_to_cpu(di->di_clusterofs);
+		m->pblk = le32_to_cpu(di->di_u.blkaddr);
+		break;
+	default:
+		DBG_BUGON(1);
+		return -EOPNOTSUPP;
+	}
+	m->type = type;
+	return 0;
+}
+
+static unsigned int decode_compactedbits(unsigned int lobits,
+					 unsigned int lomask,
+					 u8 *in, unsigned int pos, u8 *type)
+{
+	const unsigned int v = get_unaligned_le32(in + pos / 8) >> (pos & 7);
+	const unsigned int lo = v & lomask;
+
+	*type = (v >> lobits) & 3;
+	return lo;
+}
+
+static int get_compacted_la_distance(unsigned int lclusterbits,
+				     unsigned int encodebits,
+				     unsigned int vcnt, u8 *in, int i)
+{
+	const unsigned int lomask = (1 << lclusterbits) - 1;
+	unsigned int lo, d1 = 0;
+	u8 type;
+
+	DBG_BUGON(i >= vcnt);
+
+	do {
+		lo = decode_compactedbits(lclusterbits, lomask,
+					  in, encodebits * i, &type);
+
+		if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
+			return d1;
+		++d1;
+	} while (++i < vcnt);
+
+	/* vcnt - 1 (Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) item */
+	if (!(lo & Z_EROFS_VLE_DI_D0_CBLKCNT))
+		d1 += lo - 1;
+	return d1;
+}
+
+static int unpack_compacted_index(struct z_erofs_maprecorder *m,
+				  unsigned int amortizedshift,
+				  unsigned int eofs, bool lookahead)
+{
+	struct erofs_inode *const vi = m->inode;
+	const unsigned int lclusterbits = vi->z_logical_clusterbits;
+	const unsigned int lomask = (1 << lclusterbits) - 1;
+	unsigned int vcnt, base, lo, encodebits, nblk;
+	int i;
+	u8 *in, type;
+	bool big_pcluster;
+
+	if (1 << amortizedshift == 4)
+		vcnt = 2;
+	else if (1 << amortizedshift == 2 && lclusterbits == 12)
+		vcnt = 16;
+	else
+		return -EOPNOTSUPP;
+
+	big_pcluster = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1;
+	encodebits = ((vcnt << amortizedshift) - sizeof(__le32)) * 8 / vcnt;
+	base = round_down(eofs, vcnt << amortizedshift);
+	in = m->kaddr + base;
+
+	i = (eofs - base) >> amortizedshift;
+
+	lo = decode_compactedbits(lclusterbits, lomask,
+				  in, encodebits * i, &type);
+	m->type = type;
+	if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
+		m->clusterofs = 1 << lclusterbits;
+
+		/* figure out lookahead_distance: delta[1] if needed */
+		if (lookahead)
+			m->delta[1] = get_compacted_la_distance(lclusterbits,
+								encodebits,
+								vcnt, in, i);
+		if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) {
+			if (!big_pcluster) {
+				DBG_BUGON(1);
+				return -EFSCORRUPTED;
+			}
+			m->compressedlcs = lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT;
+			m->delta[0] = 1;
+			return 0;
+		} else if (i + 1 != (int)vcnt) {
+			m->delta[0] = lo;
+			return 0;
+		}
+		/*
+		 * since the last lcluster in the pack is special,
+		 * of which lo saves delta[1] rather than delta[0].
+		 * Hence, get delta[0] by the previous lcluster indirectly.
+		 */
+		lo = decode_compactedbits(lclusterbits, lomask,
+					  in, encodebits * (i - 1), &type);
+		if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
+			lo = 0;
+		else if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT)
+			lo = 1;
+		m->delta[0] = lo + 1;
+		return 0;
+	}
+	m->clusterofs = lo;
+	m->delta[0] = 0;
+	/* figout out blkaddr (pblk) for HEAD lclusters */
+	if (!big_pcluster) {
+		nblk = 1;
+		while (i > 0) {
+			--i;
+			lo = decode_compactedbits(lclusterbits, lomask,
+						  in, encodebits * i, &type);
+			if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
+				i -= lo;
+
+			if (i >= 0)
+				++nblk;
+		}
+	} else {
+		nblk = 0;
+		while (i > 0) {
+			--i;
+			lo = decode_compactedbits(lclusterbits, lomask,
+						  in, encodebits * i, &type);
+			if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
+				if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) {
+					--i;
+					nblk += lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT;
+					continue;
+				}
+				if (lo == 1) {
+					DBG_BUGON(1);
+					/* --i; ++nblk;	continue; */
+					return -EFSCORRUPTED;
+				}
+				i -= lo - 2;
+				continue;
+			}
+			++nblk;
+		}
+	}
+	in += (vcnt << amortizedshift) - sizeof(__le32);
+	m->pblk = le32_to_cpu(*(__le32 *)in) + nblk;
+	return 0;
+}
+
+static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
+					    unsigned long lcn, bool lookahead)
+{
+	struct erofs_inode *const vi = m->inode;
+	const unsigned int lclusterbits = vi->z_logical_clusterbits;
+	const erofs_off_t ebase = round_up(iloc(vi->nid) + vi->inode_isize +
+					   vi->xattr_isize, 8) +
+		sizeof(struct z_erofs_map_header);
+	const unsigned int totalidx = DIV_ROUND_UP(vi->i_size, EROFS_BLKSIZ);
+	unsigned int compacted_4b_initial, compacted_2b;
+	unsigned int amortizedshift;
+	erofs_off_t pos;
+	int err;
+
+	if (lclusterbits != 12)
+		return -EOPNOTSUPP;
+
+	if (lcn >= totalidx)
+		return -EINVAL;
+
+	m->lcn = lcn;
+	/* used to align to 32-byte (compacted_2b) alignment */
+	compacted_4b_initial = (32 - ebase % 32) / 4;
+	if (compacted_4b_initial == 32 / 4)
+		compacted_4b_initial = 0;
+
+	if (vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B)
+		compacted_2b = rounddown(totalidx - compacted_4b_initial, 16);
+	else
+		compacted_2b = 0;
+
+	pos = ebase;
+	if (lcn < compacted_4b_initial) {
+		amortizedshift = 2;
+		goto out;
+	}
+	pos += compacted_4b_initial * 4;
+	lcn -= compacted_4b_initial;
+
+	if (lcn < compacted_2b) {
+		amortizedshift = 1;
+		goto out;
+	}
+	pos += compacted_2b * 2;
+	lcn -= compacted_2b;
+	amortizedshift = 2;
+out:
+	pos += lcn * (1 << amortizedshift);
+	err = z_erofs_reload_indexes(m, erofs_blknr(pos));
+	if (err)
+		return err;
+	return unpack_compacted_index(m, amortizedshift, erofs_blkoff(pos),
+				      lookahead);
+}
+
+static int z_erofs_load_cluster_from_disk(struct z_erofs_maprecorder *m,
+					  unsigned int lcn, bool lookahead)
+{
+	const unsigned int datamode = m->inode->datalayout;
+
+	if (datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY)
+		return legacy_load_cluster_from_disk(m, lcn);
+
+	if (datamode == EROFS_INODE_FLAT_COMPRESSION)
+		return compacted_load_cluster_from_disk(m, lcn, lookahead);
+
+	return -EINVAL;
+}
+
+static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
+				   unsigned int lookback_distance)
+{
+	struct erofs_inode *const vi = m->inode;
+	struct erofs_map_blocks *const map = m->map;
+	const unsigned int lclusterbits = vi->z_logical_clusterbits;
+	unsigned long lcn = m->lcn;
+	int err;
+
+	if (lcn < lookback_distance) {
+		erofs_err("bogus lookback distance @ nid %llu",
+			  (unsigned long long)vi->nid);
+		DBG_BUGON(1);
+		return -EFSCORRUPTED;
+	}
+
+	/* load extent head logical cluster if needed */
+	lcn -= lookback_distance;
+	err = z_erofs_load_cluster_from_disk(m, lcn, false);
+	if (err)
+		return err;
+
+	switch (m->type) {
+	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		if (!m->delta[0]) {
+			erofs_err("invalid lookback distance 0 @ nid %llu",
+				  (unsigned long long)vi->nid);
+			DBG_BUGON(1);
+			return -EFSCORRUPTED;
+		}
+		return z_erofs_extent_lookback(m, m->delta[0]);
+	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+		m->headtype = m->type;
+		map->m_la = (lcn << lclusterbits) | m->clusterofs;
+		break;
+	default:
+		erofs_err("unknown type %u @ lcn %lu of nid %llu",
+			  m->type, lcn, (unsigned long long)vi->nid);
+		DBG_BUGON(1);
+		return -EOPNOTSUPP;
+	}
+	return 0;
+}
+
+static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
+					    unsigned int initial_lcn)
+{
+	struct erofs_inode *const vi = m->inode;
+	struct erofs_map_blocks *const map = m->map;
+	const unsigned int lclusterbits = vi->z_logical_clusterbits;
+	unsigned long lcn;
+	int err;
+
+	DBG_BUGON(m->type != Z_EROFS_VLE_CLUSTER_TYPE_PLAIN &&
+		  m->type != Z_EROFS_VLE_CLUSTER_TYPE_HEAD);
+	if (m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN ||
+	    !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) {
+		map->m_plen = 1 << lclusterbits;
+		return 0;
+	}
+
+	lcn = m->lcn + 1;
+	if (m->compressedlcs)
+		goto out;
+
+	err = z_erofs_load_cluster_from_disk(m, lcn, false);
+	if (err)
+		return err;
+
+	/*
+	 * If the 1st NONHEAD lcluster has already been handled initially w/o
+	 * valid compressedlcs, which means at least it mustn't be CBLKCNT, or
+	 * an internal implemenatation error is detected.
+	 *
+	 * The following code can also handle it properly anyway, but let's
+	 * BUG_ON in the debugging mode only for developers to notice that.
+	 */
+	DBG_BUGON(lcn == initial_lcn &&
+		  m->type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD);
+
+	switch (m->type) {
+	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+		/*
+		 * if the 1st NONHEAD lcluster is actually PLAIN or HEAD type
+		 * rather than CBLKCNT, it's a 1 lcluster-sized pcluster.
+		 */
+		m->compressedlcs = 1;
+		break;
+	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		if (m->delta[0] != 1)
+			goto err_bonus_cblkcnt;
+		if (m->compressedlcs)
+			break;
+		/* fallthrough */
+	default:
+		erofs_err("cannot found CBLKCNT @ lcn %lu of nid %llu",
+			  lcn, vi->nid | 0ULL);
+		DBG_BUGON(1);
+		return -EFSCORRUPTED;
+	}
+out:
+	map->m_plen = m->compressedlcs << lclusterbits;
+	return 0;
+err_bonus_cblkcnt:
+	erofs_err("bogus CBLKCNT @ lcn %lu of nid %llu",
+		  lcn, vi->nid | 0ULL);
+	DBG_BUGON(1);
+	return -EFSCORRUPTED;
+}
+
+static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
+{
+	struct erofs_inode *const vi = m->inode;
+	struct erofs_map_blocks *map = m->map;
+	unsigned int lclusterbits = vi->z_logical_clusterbits;
+	u64 lcn = m->lcn, headlcn = map->m_la >> lclusterbits;
+	int err;
+
+	do {
+		/* handle the last EOF pcluster (no next HEAD lcluster) */
+		if ((lcn << lclusterbits) >= vi->i_size) {
+			map->m_llen = vi->i_size - map->m_la;
+			return 0;
+		}
+
+		err = z_erofs_load_cluster_from_disk(m, lcn, true);
+		if (err)
+			return err;
+
+		if (m->type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
+			DBG_BUGON(!m->delta[1] &&
+				  m->clusterofs != 1 << lclusterbits);
+		} else if (m->type == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN ||
+			   m->type == Z_EROFS_VLE_CLUSTER_TYPE_HEAD) {
+			/* go on until the next HEAD lcluster */
+			if (lcn != headlcn)
+				break;
+			m->delta[1] = 1;
+		} else {
+			erofs_err("unknown type %u @ lcn %llu of nid %llu",
+				  m->type, lcn | 0ULL,
+				  (unsigned long long)vi->nid);
+			DBG_BUGON(1);
+			return -EOPNOTSUPP;
+		}
+		lcn += m->delta[1];
+	} while (m->delta[1]);
+
+	map->m_llen = (lcn << lclusterbits) + m->clusterofs - map->m_la;
+	return 0;
+}
+
+int z_erofs_map_blocks_iter(struct erofs_inode *vi,
+			    struct erofs_map_blocks *map,
+			    int flags)
+{
+	struct z_erofs_maprecorder m = {
+		.inode = vi,
+		.map = map,
+		.kaddr = map->mpage,
+	};
+	int err = 0;
+	unsigned int lclusterbits, endoff;
+	unsigned long initial_lcn;
+	unsigned long long ofs, end;
+
+	/* when trying to read beyond EOF, leave it unmapped */
+	if (map->m_la >= vi->i_size) {
+		map->m_llen = map->m_la + 1 - vi->i_size;
+		map->m_la = vi->i_size;
+		map->m_flags = 0;
+		goto out;
+	}
+
+	err = z_erofs_fill_inode_lazy(vi);
+	if (err)
+		goto out;
+
+	lclusterbits = vi->z_logical_clusterbits;
+	ofs = map->m_la;
+	initial_lcn = ofs >> lclusterbits;
+	endoff = ofs & ((1 << lclusterbits) - 1);
+
+	err = z_erofs_load_cluster_from_disk(&m, initial_lcn, false);
+	if (err)
+		goto out;
+
+	map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_ENCODED;
+	end = (m.lcn + 1ULL) << lclusterbits;
+	switch (m.type) {
+	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+		if (endoff >= m.clusterofs) {
+			m.headtype = m.type;
+			map->m_la = (m.lcn << lclusterbits) | m.clusterofs;
+			break;
+		}
+		/* m.lcn should be >= 1 if endoff < m.clusterofs */
+		if (!m.lcn) {
+			erofs_err("invalid logical cluster 0 at nid %llu",
+				  (unsigned long long)vi->nid);
+			err = -EFSCORRUPTED;
+			goto out;
+		}
+		end = (m.lcn << lclusterbits) | m.clusterofs;
+		map->m_flags |= EROFS_MAP_FULL_MAPPED;
+		m.delta[0] = 1;
+		/* fallthrough */
+	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		/* get the correspoinding first chunk */
+		err = z_erofs_extent_lookback(&m, m.delta[0]);
+		if (err)
+			goto out;
+		break;
+	default:
+		erofs_err("unknown type %u @ offset %llu of nid %llu",
+			  m.type, ofs, (unsigned long long)vi->nid);
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	map->m_llen = end - map->m_la;
+	map->m_pa = blknr_to_addr(m.pblk);
+
+	err = z_erofs_get_extent_compressedlen(&m, initial_lcn);
+	if (err)
+		goto out;
+
+	if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN)
+		map->m_algorithmformat = Z_EROFS_COMPRESSION_SHIFTED;
+	else
+		map->m_algorithmformat = vi->z_algorithmtype[0];
+
+	if (flags & EROFS_GET_BLOCKS_FIEMAP) {
+		err = z_erofs_get_extent_decompressedlen(&m);
+		if (!err)
+			map->m_flags |= EROFS_MAP_FULL_MAPPED;
+	}
+
+out:
+	erofs_dbg("m_la %" PRIu64 " m_pa %" PRIu64 " m_llen %" PRIu64 " m_plen %" PRIu64 " m_flags 0%o",
+		  map->m_la, map->m_pa,
+		  map->m_llen, map->m_plen, map->m_flags);
+
+	DBG_BUGON(err < 0 && err != -ENOMEM);
+	return err;
+}
diff --git a/fs/fs.c b/fs/fs.c
index 023f89cafec..99dac0fd79f 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -26,6 +26,7 @@
 #include <linux/math64.h>
 #include <efi_loader.h>
 #include <squashfs.h>
+#include <erofs.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -305,6 +306,27 @@ static struct fstype_info fstypes[] = {
 		.mkdir = fs_mkdir_unsupported,
 	},
 #endif
+#if IS_ENABLED(CONFIG_FS_EROFS)
+	{
+		.fstype = FS_TYPE_EROFS,
+		.name = "erofs",
+		.null_dev_desc_ok = false,
+		.probe = erofs_probe,
+		.opendir = erofs_opendir,
+		.readdir = erofs_readdir,
+		.ls = fs_ls_generic,
+		.read = erofs_read,
+		.size = erofs_size,
+		.close = erofs_close,
+		.closedir = erofs_closedir,
+		.exists = erofs_exists,
+		.uuid = fs_uuid_unsupported,
+		.write = fs_write_unsupported,
+		.ln = fs_ln_unsupported,
+		.unlink = fs_unlink_unsupported,
+		.mkdir = fs_mkdir_unsupported,
+	},
+#endif
 	{
 		.fstype = FS_TYPE_ANY,
 		.name = "unsupported",
diff --git a/include/erofs.h b/include/erofs.h
new file mode 100644
index 00000000000..1fbe82bf72c
--- /dev/null
+++ b/include/erofs.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _EROFS_H_
+#define _EROFS_H_
+
+struct disk_partition;
+
+int erofs_opendir(const char *filename, struct fs_dir_stream **dirsp);
+int erofs_readdir(struct fs_dir_stream *dirs, struct fs_dirent **dentp);
+int erofs_probe(struct blk_desc *fs_dev_desc,
+		struct disk_partition *fs_partition);
+int erofs_read(const char *filename, void *buf, loff_t offset,
+	       loff_t len, loff_t *actread);
+int erofs_size(const char *filename, loff_t *size);
+int erofs_exists(const char *filename);
+void erofs_close(void);
+void erofs_closedir(struct fs_dir_stream *dirs);
+int erofs_uuid(char *uuid_str);
+
+#endif /* _EROFS_H */
diff --git a/include/fs.h b/include/fs.h
index c8df3886ac6..b607b0028dc 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -17,6 +17,7 @@ struct cmd_tbl;
 #define FS_TYPE_UBIFS	4
 #define FS_TYPE_BTRFS	5
 #define FS_TYPE_SQUASHFS 6
+#define FS_TYPE_EROFS   7
 
 struct blk_desc;
 
diff --git a/include/u-boot/lz4.h b/include/u-boot/lz4.h
index e18b39a5dc9..655adbfcd18 100644
--- a/include/u-boot/lz4.h
+++ b/include/u-boot/lz4.h
@@ -21,4 +21,53 @@
  */
 int ulz4fn(const void *src, size_t srcn, void *dst, size_t *dstn);
 
+/**
+ * LZ4_decompress_safe() - Decompression protected against buffer overflow
+ * @source: source address of the compressed data
+ * @dest: output buffer address of the uncompressed data
+ *	which must be already allocated
+ * @compressedSize: is the precise full size of the compressed block
+ * @maxDecompressedSize: is the size of 'dest' buffer
+ *
+ * Decompresses data from 'source' into 'dest'.
+ * If the source stream is detected malformed, the function will
+ * stop decoding and return a negative result.
+ * This function is protected against buffer overflow exploits,
+ * including malicious data packets. It never writes outside output buffer,
+ * nor reads outside input buffer.
+ *
+ * Return: number of bytes decompressed into destination buffer
+ *	(necessarily <= maxDecompressedSize)
+ *	or a negative result in case of error
+ */
+int LZ4_decompress_safe(const char *source, char *dest,
+	int compressedSize, int maxDecompressedSize);
+
+/**
+ * LZ4_decompress_safe_partial() - Decompress a block of size 'compressedSize'
+ *	at position 'source' into buffer 'dest'
+ * @source: source address of the compressed data
+ * @dest: output buffer address of the decompressed data which must be
+ *	already allocated
+ * @compressedSize: is the precise full size of the compressed block.
+ * @targetOutputSize: the decompression operation will try
+ *	to stop as soon as 'targetOutputSize' has been reached
+ * @maxDecompressedSize: is the size of destination buffer
+ *
+ * This function decompresses a compressed block of size 'compressedSize'
+ * at position 'source' into destination buffer 'dest'
+ * of size 'maxDecompressedSize'.
+ * The function tries to stop decompressing operation as soon as
+ * 'targetOutputSize' has been reached, reducing decompression time.
+ * This function never writes outside of output buffer,
+ * and never reads outside of input buffer.
+ * It is therefore protected against malicious data packets.
+ *
+ * Return: the number of bytes decoded in the destination buffer
+ *	(necessarily <= maxDecompressedSize)
+ *	or a negative result in case of error
+ *
+ */
+int LZ4_decompress_safe_partial(const char *src, char *dst,
+	int compressedSize, int targetOutputSize, int dstCapacity);
 #endif
diff --git a/lib/lz4.c b/lib/lz4.c
index 046c34e3906..5337842126c 100644
--- a/lib/lz4.c
+++ b/lib/lz4.c
@@ -1,13 +1,63 @@
-// SPDX-License-Identifier: BSD-2-Clause
+// SPDX-License-Identifier: GPL 2.0+ OR BSD-2-Clause
 /*
-   LZ4 - Fast LZ compression algorithm
-   Copyright (C) 2011-2015, Yann Collet.
+ * LZ4 - Fast LZ compression algorithm
+ * Copyright (C) 2011 - 2016, Yann Collet.
+ * BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php)
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *	* Redistributions of source code must retain the above copyright
+ *	  notice, this list of conditions and the following disclaimer.
+ *	* Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * You can contact the author at :
+ *	- LZ4 homepage : http://www.lz4.org
+ *	- LZ4 source repository : https://github.com/lz4/lz4
+ */
+#include <common.h>
+#include <compiler.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/bug.h>
+#include <asm/unaligned.h>
+#include <u-boot/lz4.h>
+
+#define FORCE_INLINE inline __attribute__((always_inline))
+
+static FORCE_INLINE u16 LZ4_readLE16(const void *src)
+{
+	return get_unaligned_le16(src);
+}
 
-   You can contact the author at :
-   - LZ4 source repository : https://github.com/Cyan4973/lz4
-   - LZ4 public forum : https://groups.google.com/forum/#!forum/lz4c
-*/
+static FORCE_INLINE void LZ4_copy8(void *dst, const void *src)
+{
+	put_unaligned(get_unaligned((const u64 *)src), (u64 *)dst);
+}
+
+typedef  uint8_t BYTE;
+typedef uint16_t U16;
+typedef uint32_t U32;
+typedef  int32_t S32;
+typedef uint64_t U64;
+typedef uintptr_t uptrval;
 
+static FORCE_INLINE void LZ4_write32(void *memPtr, U32 value)
+{
+	put_unaligned(value, (U32 *)memPtr);
+}
 
 /**************************************
 *  Reading and writing into memory
@@ -28,14 +78,17 @@ static void LZ4_wildCopy(void* dstPtr, const void* srcPtr, void* dstEnd)
 **************************************/
 #define MINMATCH 4
 
-#define COPYLENGTH 8
+#define WILDCOPYLENGTH 8
 #define LASTLITERALS 5
-#define MFLIMIT (COPYLENGTH+MINMATCH)
-static const int LZ4_minLength = (MFLIMIT+1);
+#define MFLIMIT (WILDCOPYLENGTH + MINMATCH)
 
-#define KB *(1 <<10)
-#define MB *(1 <<20)
-#define GB *(1U<<30)
+/*
+ * ensure it's possible to write 2 x wildcopyLength
+ * without overflowing output buffer
+ */
+#define MATCH_SAFEGUARD_DISTANCE  ((2 * WILDCOPYLENGTH) - MINMATCH)
+
+#define KB (1 <<10)
 
 #define MAXD_LOG 16
 #define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
@@ -45,198 +98,438 @@ static const int LZ4_minLength = (MFLIMIT+1);
 #define RUN_BITS (8-ML_BITS)
 #define RUN_MASK ((1U<<RUN_BITS)-1)
 
+#define LZ4_STATIC_ASSERT(c)	BUILD_BUG_ON(!(c))
 
 /**************************************
 *  Local Structures and types
 **************************************/
 typedef enum { noDict = 0, withPrefix64k, usingExtDict } dict_directive;
 typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
-typedef enum { full = 0, partial = 1 } earlyEnd_directive;
+typedef enum { decode_full_block = 0, partial_decode = 1 } earlyEnd_directive;
 
+#define DEBUGLOG(l, ...) {}	/* disabled */
 
+#ifndef assert
+#define assert(condition) ((void)0)
+#endif
 
-/*******************************
-*  Decompression functions
-*******************************/
 /*
- * This generic decompression function cover all use cases.
- * It shall be instantiated several times, using different sets of directives
- * Note that it is essential this generic function is really inlined,
+ * LZ4_decompress_generic() :
+ * This generic decompression function covers all use cases.
+ * It shall be instantiated several times, using different sets of directives.
+ * Note that it is important for performance that this function really get inlined,
  * in order to remove useless branches during compilation optimization.
  */
-FORCE_INLINE int LZ4_decompress_generic(
-                 const char* const source,
-                 char* const dest,
-                 int inputSize,
-                 int outputSize,         /* If endOnInput==endOnInputSize, this value is the max size of Output Buffer. */
-
-                 int endOnInput,         /* endOnOutputSize, endOnInputSize */
-                 int partialDecoding,    /* full, partial */
-                 int targetOutputSize,   /* only used if partialDecoding==partial */
-                 int dict,               /* noDict, withPrefix64k, usingExtDict */
-                 const BYTE* const lowPrefix,  /* == dest if dict == noDict */
-                 const BYTE* const dictStart,  /* only if dict==usingExtDict */
-                 const size_t dictSize         /* note : = 0 if noDict */
-                 )
+static FORCE_INLINE int LZ4_decompress_generic(
+	 const char * const src,
+	 char * const dst,
+	 int srcSize,
+		/*
+		 * If endOnInput == endOnInputSize,
+		 * this value is `dstCapacity`
+		 */
+	 int outputSize,
+	 /* endOnOutputSize, endOnInputSize */
+	 endCondition_directive endOnInput,
+	 /* full, partial */
+	 earlyEnd_directive partialDecoding,
+	 /* noDict, withPrefix64k, usingExtDict */
+	 dict_directive dict,
+	 /* always <= dst, == dst when no prefix */
+	 const BYTE * const lowPrefix,
+	 /* only if dict == usingExtDict */
+	 const BYTE * const dictStart,
+	 /* note : = 0 if noDict */
+	 const size_t dictSize
+	 )
 {
-    /* Local Variables */
-    const BYTE* ip = (const BYTE*) source;
-    const BYTE* const iend = ip + inputSize;
-
-    BYTE* op = (BYTE*) dest;
-    BYTE* const oend = op + outputSize;
-    BYTE* cpy;
-    BYTE* oexit = op + targetOutputSize;
-    const BYTE* const lowLimit = lowPrefix - dictSize;
-
-    const BYTE* const dictEnd = (const BYTE*)dictStart + dictSize;
-    const size_t dec32table[] = {4, 1, 2, 1, 4, 4, 4, 4};
-    const size_t dec64table[] = {0, 0, 0, (size_t)-1, 0, 1, 2, 3};
-
-    const int safeDecode = (endOnInput==endOnInputSize);
-    const int checkOffset = ((safeDecode) && (dictSize < (int)(64 KB)));
-
-
-    /* Special cases */
-    if ((partialDecoding) && (oexit> oend-MFLIMIT)) oexit = oend-MFLIMIT;                         /* targetOutputSize too high => decode everything */
-    if ((endOnInput) && (unlikely(outputSize==0))) return ((inputSize==1) && (*ip==0)) ? 0 : -1;  /* Empty output buffer */
-    if ((!endOnInput) && (unlikely(outputSize==0))) return (*ip==0?1:-1);
-
-
-    /* Main Loop */
-    while (1)
-    {
-        unsigned token;
-        size_t length;
-        const BYTE* match;
-
-        /* get literal length */
-        token = *ip++;
-        if ((length=(token>>ML_BITS)) == RUN_MASK)
-        {
-            unsigned s;
-            do
-            {
-                s = *ip++;
-                length += s;
-            }
-            while (likely((endOnInput)?ip<iend-RUN_MASK:1) && (s==255));
-            if ((safeDecode) && unlikely((size_t)(op+length)<(size_t)(op))) goto _output_error;   /* overflow detection */
-            if ((safeDecode) && unlikely((size_t)(ip+length)<(size_t)(ip))) goto _output_error;   /* overflow detection */
-        }
-
-        /* copy literals */
-        cpy = op+length;
-        if (((endOnInput) && ((cpy>(partialDecoding?oexit:oend-MFLIMIT)) || (ip+length>iend-(2+1+LASTLITERALS))) )
-            || ((!endOnInput) && (cpy>oend-COPYLENGTH)))
-        {
-            if (partialDecoding)
-            {
-                if (cpy > oend) goto _output_error;                           /* Error : write attempt beyond end of output buffer */
-                if ((endOnInput) && (ip+length > iend)) goto _output_error;   /* Error : read attempt beyond end of input buffer */
-            }
-            else
-            {
-                if ((!endOnInput) && (cpy != oend)) goto _output_error;       /* Error : block decoding must stop exactly there */
-                if ((endOnInput) && ((ip+length != iend) || (cpy > oend))) goto _output_error;   /* Error : input must be consumed */
-            }
-            memcpy(op, ip, length);
-            ip += length;
-            op += length;
-            break;     /* Necessarily EOF, due to parsing restrictions */
-        }
-        LZ4_wildCopy(op, ip, cpy);
-        ip += length; op = cpy;
-
-        /* get offset */
-        match = cpy - LZ4_readLE16(ip); ip+=2;
-        if ((checkOffset) && (unlikely(match < lowLimit))) goto _output_error;   /* Error : offset outside destination buffer */
-
-        /* get matchlength */
-        length = token & ML_MASK;
-        if (length == ML_MASK)
-        {
-            unsigned s;
-            do
-            {
-                if ((endOnInput) && (ip > iend-LASTLITERALS)) goto _output_error;
-                s = *ip++;
-                length += s;
-            } while (s==255);
-            if ((safeDecode) && unlikely((size_t)(op+length)<(size_t)op)) goto _output_error;   /* overflow detection */
-        }
-        length += MINMATCH;
-
-        /* check external dictionary */
-        if ((dict==usingExtDict) && (match < lowPrefix))
-        {
-            if (unlikely(op+length > oend-LASTLITERALS)) goto _output_error;   /* doesn't respect parsing restriction */
-
-            if (length <= (size_t)(lowPrefix-match))
-            {
-                /* match can be copied as a single segment from external dictionary */
-                match = dictEnd - (lowPrefix-match);
-                memmove(op, match, length); op += length;
-            }
-            else
-            {
-                /* match encompass external dictionary and current segment */
-                size_t copySize = (size_t)(lowPrefix-match);
-                memcpy(op, dictEnd - copySize, copySize);
-                op += copySize;
-                copySize = length - copySize;
-                if (copySize > (size_t)(op-lowPrefix))   /* overlap within current segment */
-                {
-                    BYTE* const endOfMatch = op + copySize;
-                    const BYTE* copyFrom = lowPrefix;
-                    while (op < endOfMatch) *op++ = *copyFrom++;
-                }
-                else
-                {
-                    memcpy(op, lowPrefix, copySize);
-                    op += copySize;
-                }
-            }
-            continue;
-        }
-
-        /* copy repeated sequence */
-        cpy = op + length;
-        if (unlikely((op-match)<8))
-        {
-            const size_t dec64 = dec64table[op-match];
-            op[0] = match[0];
-            op[1] = match[1];
-            op[2] = match[2];
-            op[3] = match[3];
-            match += dec32table[op-match];
-            LZ4_copy4(op+4, match);
-            op += 8; match -= dec64;
-        } else { LZ4_copy8(op, match); op+=8; match+=8; }
-
-        if (unlikely(cpy>oend-12))
-        {
-            if (cpy > oend-LASTLITERALS) goto _output_error;    /* Error : last LASTLITERALS bytes must be literals */
-            if (op < oend-8)
-            {
-                LZ4_wildCopy(op, match, oend-8);
-                match += (oend-8) - op;
-                op = oend-8;
-            }
-            while (op<cpy) *op++ = *match++;
-        }
-        else
-            LZ4_wildCopy(op, match, cpy);
-        op=cpy;   /* correction */
-    }
-
-    /* end of decoding */
-    if (endOnInput)
-       return (int) (((char*)op)-dest);     /* Nb of output bytes decoded */
-    else
-       return (int) (((const char*)ip)-source);   /* Nb of input bytes read */
-
-    /* Overflow error detected */
+	const BYTE *ip = (const BYTE *) src;
+	const BYTE * const iend = ip + srcSize;
+
+	BYTE *op = (BYTE *) dst;
+	BYTE * const oend = op + outputSize;
+	BYTE *cpy;
+
+	const BYTE * const dictEnd = (const BYTE *)dictStart + dictSize;
+	static const unsigned int inc32table[8] = {0, 1, 2, 1, 0, 4, 4, 4};
+	static const int dec64table[8] = {0, 0, 0, -1, -4, 1, 2, 3};
+
+	const int safeDecode = (endOnInput == endOnInputSize);
+	const int checkOffset = ((safeDecode) && (dictSize < (int)(64 * KB)));
+
+	/* Set up the "end" pointers for the shortcut. */
+	const BYTE *const shortiend = iend -
+		(endOnInput ? 14 : 8) /*maxLL*/ - 2 /*offset*/;
+	const BYTE *const shortoend = oend -
+		(endOnInput ? 14 : 8) /*maxLL*/ - 18 /*maxML*/;
+
+	DEBUGLOG(5, "%s (srcSize:%i, dstSize:%i)", __func__,
+		 srcSize, outputSize);
+
+	/* Special cases */
+	assert(lowPrefix <= op);
+	assert(src != NULL);
+
+	/* Empty output buffer */
+	if ((endOnInput) && (unlikely(outputSize == 0)))
+		return ((srcSize == 1) && (*ip == 0)) ? 0 : -1;
+
+	if ((!endOnInput) && (unlikely(outputSize == 0)))
+		return (*ip == 0 ? 1 : -1);
+
+	if ((endOnInput) && unlikely(srcSize == 0))
+		return -1;
+
+	/* Main Loop : decode sequences */
+	while (1) {
+		size_t length;
+		const BYTE *match;
+		size_t offset;
+
+		/* get literal length */
+		unsigned int const token = *ip++;
+		length = token>>ML_BITS;
+
+		/* ip < iend before the increment */
+		assert(!endOnInput || ip <= iend);
+
+		/*
+		 * A two-stage shortcut for the most common case:
+		 * 1) If the literal length is 0..14, and there is enough
+		 * space, enter the shortcut and copy 16 bytes on behalf
+		 * of the literals (in the fast mode, only 8 bytes can be
+		 * safely copied this way).
+		 * 2) Further if the match length is 4..18, copy 18 bytes
+		 * in a similar manner; but we ensure that there's enough
+		 * space in the output for those 18 bytes earlier, upon
+		 * entering the shortcut (in other words, there is a
+		 * combined check for both stages).
+		 *
+		 * The & in the likely() below is intentionally not && so that
+		 * some compilers can produce better parallelized runtime code
+		 */
+		if ((endOnInput ? length != RUN_MASK : length <= 8)
+		   /*
+		    * strictly "less than" on input, to re-enter
+		    * the loop with at least one byte
+		    */
+		   && likely((endOnInput ? ip < shortiend : 1) &
+			     (op <= shortoend))) {
+			/* Copy the literals */
+			memcpy(op, ip, endOnInput ? 16 : 8);
+			op += length; ip += length;
+
+			/*
+			 * The second stage:
+			 * prepare for match copying, decode full info.
+			 * If it doesn't work out, the info won't be wasted.
+			 */
+			length = token & ML_MASK; /* match length */
+			offset = LZ4_readLE16(ip);
+			ip += 2;
+			match = op - offset;
+			assert(match <= op); /* check overflow */
+
+			/* Do not deal with overlapping matches. */
+			if ((length != ML_MASK) &&
+			    (offset >= 8) &&
+			    (dict == withPrefix64k || match >= lowPrefix)) {
+				/* Copy the match. */
+				memcpy(op + 0, match + 0, 8);
+				memcpy(op + 8, match + 8, 8);
+				memcpy(op + 16, match + 16, 2);
+				op += length + MINMATCH;
+				/* Both stages worked, load the next token. */
+				continue;
+			}
+
+			/*
+			 * The second stage didn't work out, but the info
+			 * is ready. Propel it right to the point of match
+			 * copying.
+			 */
+			goto _copy_match;
+		}
+
+		/* decode literal length */
+		if (length == RUN_MASK) {
+			unsigned int s;
+
+			if (unlikely(endOnInput ? ip >= iend - RUN_MASK : 0)) {
+				/* overflow detection */
+				goto _output_error;
+			}
+			do {
+				s = *ip++;
+				length += s;
+			} while (likely(endOnInput
+				? ip < iend - RUN_MASK
+				: 1) & (s == 255));
+
+			if ((safeDecode)
+			    && unlikely((uptrval)(op) +
+					length < (uptrval)(op))) {
+				/* overflow detection */
+				goto _output_error;
+			}
+			if ((safeDecode)
+			    && unlikely((uptrval)(ip) +
+					length < (uptrval)(ip))) {
+				/* overflow detection */
+				goto _output_error;
+			}
+		}
+
+		/* copy literals */
+		cpy = op + length;
+		LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH);
+
+		if (((endOnInput) && ((cpy > oend - MFLIMIT)
+			|| (ip + length > iend - (2 + 1 + LASTLITERALS))))
+			|| ((!endOnInput) && (cpy > oend - WILDCOPYLENGTH))) {
+			if (partialDecoding) {
+				if (cpy > oend) {
+					/*
+					 * Partial decoding :
+					 * stop in the middle of literal segment
+					 */
+					cpy = oend;
+					length = oend - op;
+				}
+				if ((endOnInput)
+					&& (ip + length > iend)) {
+					/*
+					 * Error :
+					 * read attempt beyond
+					 * end of input buffer
+					 */
+					goto _output_error;
+				}
+			} else {
+				if ((!endOnInput)
+					&& (cpy != oend)) {
+					/*
+					 * Error :
+					 * block decoding must
+					 * stop exactly there
+					 */
+					goto _output_error;
+				}
+				if ((endOnInput)
+					&& ((ip + length != iend)
+					|| (cpy > oend))) {
+					/*
+					 * Error :
+					 * input must be consumed
+					 */
+					goto _output_error;
+				}
+			}
+
+			/*
+			 * supports overlapping memory regions; only matters
+			 * for in-place decompression scenarios
+			 */
+			memmove(op, ip, length);
+			ip += length;
+			op += length;
+
+			/* Necessarily EOF, due to parsing restrictions */
+			if (!partialDecoding || (cpy == oend))
+				break;
+		} else {
+			/* may overwrite up to WILDCOPYLENGTH beyond cpy */
+			LZ4_wildCopy(op, ip, cpy);
+			ip += length;
+			op = cpy;
+		}
+
+		/* get offset */
+		offset = LZ4_readLE16(ip);
+		ip += 2;
+		match = op - offset;
+
+		/* get matchlength */
+		length = token & ML_MASK;
+
+_copy_match:
+		if ((checkOffset) && (unlikely(match + dictSize < lowPrefix))) {
+			/* Error : offset outside buffers */
+			goto _output_error;
+		}
+
+		/* costs ~1%; silence an msan warning when offset == 0 */
+		/*
+		 * note : when partialDecoding, there is no guarantee that
+		 * at least 4 bytes remain available in output buffer
+		 */
+		if (!partialDecoding) {
+			assert(oend > op);
+			assert(oend - op >= 4);
+
+			LZ4_write32(op, (U32)offset);
+		}
+
+		if (length == ML_MASK) {
+			unsigned int s;
+
+			do {
+				s = *ip++;
+
+				if ((endOnInput) && (ip > iend - LASTLITERALS))
+					goto _output_error;
+
+				length += s;
+			} while (s == 255);
+
+			if ((safeDecode)
+				&& unlikely(
+					(uptrval)(op) + length < (uptrval)op)) {
+				/* overflow detection */
+				goto _output_error;
+			}
+		}
+
+		length += MINMATCH;
+
+		/* match starting within external dictionary */
+		if ((dict == usingExtDict) && (match < lowPrefix)) {
+			if (unlikely(op + length > oend - LASTLITERALS)) {
+				/* doesn't respect parsing restriction */
+				if (!partialDecoding)
+					goto _output_error;
+				length = min(length, (size_t)(oend - op));
+			}
+
+			if (length <= (size_t)(lowPrefix - match)) {
+				/*
+				 * match fits entirely within external
+				 * dictionary : just copy
+				 */
+				memmove(op, dictEnd - (lowPrefix - match),
+					length);
+				op += length;
+			} else {
+				/*
+				 * match stretches into both external
+				 * dictionary and current block
+				 */
+				size_t const copySize = (size_t)(lowPrefix - match);
+				size_t const restSize = length - copySize;
+
+				memcpy(op, dictEnd - copySize, copySize);
+				op += copySize;
+				if (restSize > (size_t)(op - lowPrefix)) {
+					/* overlap copy */
+					BYTE * const endOfMatch = op + restSize;
+					const BYTE *copyFrom = lowPrefix;
+
+					while (op < endOfMatch)
+						*op++ = *copyFrom++;
+				} else {
+					memcpy(op, lowPrefix, restSize);
+					op += restSize;
+				}
+			}
+			continue;
+		}
+
+		/* copy match within block */
+		cpy = op + length;
+
+		/*
+		 * partialDecoding :
+		 * may not respect endBlock parsing restrictions
+		 */
+		assert(op <= oend);
+		if (partialDecoding &&
+		    (cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
+			size_t const mlen = min(length, (size_t)(oend - op));
+			const BYTE * const matchEnd = match + mlen;
+			BYTE * const copyEnd = op + mlen;
+
+			if (matchEnd > op) {
+				/* overlap copy */
+				while (op < copyEnd)
+					*op++ = *match++;
+			} else {
+				memcpy(op, match, mlen);
+			}
+			op = copyEnd;
+			if (op == oend)
+				break;
+			continue;
+		}
+
+		if (unlikely(offset < 8)) {
+			op[0] = match[0];
+			op[1] = match[1];
+			op[2] = match[2];
+			op[3] = match[3];
+			match += inc32table[offset];
+			memcpy(op + 4, match, 4);
+			match -= dec64table[offset];
+		} else {
+			LZ4_copy8(op, match);
+			match += 8;
+		}
+
+		op += 8;
+
+		if (unlikely(cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
+			BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);
+
+			if (cpy > oend - LASTLITERALS) {
+				/*
+				 * Error : last LASTLITERALS bytes
+				 * must be literals (uncompressed)
+				 */
+				goto _output_error;
+			}
+
+			if (op < oCopyLimit) {
+				LZ4_wildCopy(op, match, oCopyLimit);
+				match += oCopyLimit - op;
+				op = oCopyLimit;
+			}
+			while (op < cpy)
+				*op++ = *match++;
+		} else {
+			LZ4_copy8(op, match);
+			if (length > 16)
+				LZ4_wildCopy(op + 8, match + 8, cpy);
+		}
+		op = cpy; /* wildcopy correction */
+	}
+
+	/* end of decoding */
+	if (endOnInput) {
+		/* Nb of output bytes decoded */
+		return (int) (((char *)op) - dst);
+	} else {
+		/* Nb of input bytes read */
+		return (int) (((const char *)ip) - src);
+	}
+
+	/* Overflow error detected */
 _output_error:
-    return (int) (-(((const char*)ip)-source))-1;
+	return (int) (-(((const char *)ip) - src)) - 1;
+}
+
+int LZ4_decompress_safe(const char *source, char *dest,
+	int compressedSize, int maxDecompressedSize)
+{
+	return LZ4_decompress_generic(source, dest,
+				      compressedSize, maxDecompressedSize,
+				      endOnInputSize, decode_full_block,
+				      noDict, (BYTE *)dest, NULL, 0);
+}
+
+int LZ4_decompress_safe_partial(const char *src, char *dst,
+	int compressedSize, int targetOutputSize, int dstCapacity)
+{
+	dstCapacity = min(targetOutputSize, dstCapacity);
+	return LZ4_decompress_generic(src, dst, compressedSize, dstCapacity,
+				      endOnInputSize, partial_decode,
+				      noDict, (BYTE *)dst, NULL, 0);
 }
diff --git a/lib/lz4_wrapper.c b/lib/lz4_wrapper.c
index ebcb5c09a22..0d2a3655a8a 100644
--- a/lib/lz4_wrapper.c
+++ b/lib/lz4_wrapper.c
@@ -11,27 +11,6 @@
 #include <asm/unaligned.h>
 #include <u-boot/lz4.h>
 
-static u16 LZ4_readLE16(const void *src)
-{
-	return get_unaligned_le16(src);
-}
-static void LZ4_copy4(void *dst, const void *src)
-{
-	put_unaligned(get_unaligned((const u32 *)src), (u32 *)dst);
-}
-static void LZ4_copy8(void *dst, const void *src)
-{
-	put_unaligned(get_unaligned((const u64 *)src), (u64 *)dst);
-}
-
-typedef  uint8_t BYTE;
-typedef uint16_t U16;
-typedef uint32_t U32;
-typedef  int32_t S32;
-typedef uint64_t U64;
-
-#define FORCE_INLINE static inline __attribute__((always_inline))
-
 /* lz4.c is unaltered (except removing unrelated code) from github.com/Cyan4973/lz4. */
 #include "lz4.c"	/* #include for inlining, do not link! */
 
@@ -112,7 +91,7 @@ int ulz4fn(const void *src, size_t srcn, void *dst, size_t *dstn)
 			/* constant folding essential, do not touch params! */
 			ret = LZ4_decompress_generic(in, out, block_size,
 					end - out, endOnInputSize,
-					full, 0, noDict, out, NULL, 0);
+					decode_full_block, noDict, out, NULL, 0);
 			if (ret < 0) {
 				ret = -EPROTO;	/* decompression error */
 				break;
diff --git a/test/py/tests/test_fs/test_erofs.py b/test/py/tests/test_fs/test_erofs.py
new file mode 100644
index 00000000000..458a52ba79d
--- /dev/null
+++ b/test/py/tests/test_fs/test_erofs.py
@@ -0,0 +1,211 @@
+# SPDX-License-Identifier: GPL-2.0+
+# Copyright (C) 2022 Huang Jianan <jnhuang95@gmail.com>
+# Author: Huang Jianan <jnhuang95@gmail.com>
+
+import os
+import pytest
+import shutil
+import subprocess
+
+EROFS_SRC_DIR = 'erofs_src_dir'
+EROFS_IMAGE_NAME = 'erofs.img'
+
+def generate_file(name, size):
+    """
+    Generates a file filled with 'x'.
+    """
+    content = 'x' * size
+    file = open(name, 'w')
+    file.write(content)
+    file.close()
+
+def make_erofs_image(build_dir):
+    """
+    Makes the EROFS images used for the test.
+
+    The image is generated at build_dir with the following structure:
+    erofs_src_dir/
+    ├── f4096
+    ├── f7812
+    ├── subdir/
+    │   └── subdir-file
+    ├── symdir -> subdir
+    └── symfile -> f5096
+    """
+    root = os.path.join(build_dir, EROFS_SRC_DIR)
+    os.makedirs(root)
+
+    # 4096: uncompressed file
+    generate_file(os.path.join(root, 'f4096'), 4096)
+
+    # 7812: Compressed file
+    generate_file(os.path.join(root, 'f7812'), 7812)
+
+    # sub-directory with a single file inside
+    subdir_path = os.path.join(root, 'subdir')
+    os.makedirs(subdir_path)
+    generate_file(os.path.join(subdir_path, 'subdir-file'), 100)
+
+    # symlink
+    os.symlink('subdir', os.path.join(root, 'symdir'))
+    os.symlink('f7812', os.path.join(root, 'symfile'))
+
+    input_path = os.path.join(build_dir, EROFS_SRC_DIR)
+    output_path = os.path.join(build_dir, EROFS_IMAGE_NAME)
+    args = ' '.join([output_path, input_path])
+    subprocess.run(['mkfs.erofs -zlz4 ' + args], shell=True, check=True,
+                   stdout=subprocess.DEVNULL)
+
+def clean_erofs_image(build_dir):
+    """
+    Deletes the image and src_dir at build_dir.
+    """
+    path = os.path.join(build_dir, EROFS_SRC_DIR)
+    shutil.rmtree(path)
+    image_path = os.path.join(build_dir, EROFS_IMAGE_NAME)
+    os.remove(image_path)
+
+def erofs_ls_at_root(u_boot_console):
+    """
+    Test if all the present files and directories were listed.
+    """
+    no_slash = u_boot_console.run_command('erofsls host 0')
+    slash = u_boot_console.run_command('erofsls host 0 /')
+    assert no_slash == slash
+
+    expected_lines = ['./', '../', '4096   f4096', '7812   f7812', 'subdir/',
+                      '<SYM>   symdir', '<SYM>   symfile', '4 file(s), 3 dir(s)']
+
+    output = u_boot_console.run_command('erofsls host 0')
+    for line in expected_lines:
+        assert line in output
+
+def erofs_ls_at_subdir(u_boot_console):
+    """
+    Test if the path resolution works.
+    """
+    expected_lines = ['./', '../', '100   subdir-file', '1 file(s), 2 dir(s)']
+    output = u_boot_console.run_command('erofsls host 0 subdir')
+    for line in expected_lines:
+        assert line in output
+
+def erofs_ls_at_symlink(u_boot_console):
+    """
+    Test if the symbolic link's target resolution works.
+    """
+    output = u_boot_console.run_command('erofsls host 0 symdir')
+    output_subdir = u_boot_console.run_command('erofsls host 0 subdir')
+    assert output == output_subdir
+
+    expected_lines = ['./', '../', '100   subdir-file', '1 file(s), 2 dir(s)']
+    for line in expected_lines:
+        assert line in output
+
+def erofs_ls_at_non_existent_dir(u_boot_console):
+    """
+    Test if the EROFS support will crash when get a nonexistent directory.
+    """
+    out_non_existent = u_boot_console.run_command('erofsls host 0 fff')
+    out_not_dir = u_boot_console.run_command('erofsls host 0 f1000')
+    assert out_non_existent == out_not_dir
+    assert '' in out_non_existent
+
+def erofs_load_files(u_boot_console, files, sizes, address):
+    """
+    Loads files and asserts their checksums.
+    """
+    build_dir = u_boot_console.config.build_dir
+    for (file, size) in zip(files, sizes):
+        out = u_boot_console.run_command('erofsload host 0 {} {}'.format(address, file))
+
+        # check if the right amount of bytes was read
+        assert size in out
+
+        # calculate u-boot file's checksum
+        out = u_boot_console.run_command('md5sum {} {}'.format(address, hex(int(size))))
+        u_boot_checksum = out.split()[-1]
+
+        # calculate original file's checksum
+        original_file_path = os.path.join(build_dir, EROFS_SRC_DIR + '/' + file)
+        out = subprocess.run(['md5sum ' + original_file_path], shell=True, check=True,
+                             capture_output=True, text=True)
+        original_checksum = out.stdout.split()[0]
+
+        # compare checksum
+        assert u_boot_checksum == original_checksum
+
+def erofs_load_files_at_root(u_boot_console):
+    """
+    Test load file from the root directory.
+    """
+    files = ['f4096', 'f7812']
+    sizes = ['4096', '7812']
+    address = '$kernel_addr_r'
+    erofs_load_files(u_boot_console, files, sizes, address)
+
+def erofs_load_files_at_subdir(u_boot_console):
+    """
+    Test load file from the subdirectory.
+    """
+    files = ['subdir/subdir-file']
+    sizes = ['100']
+    address = '$kernel_addr_r'
+    erofs_load_files(u_boot_console, files, sizes, address)
+
+def erofs_load_files_at_symlink(u_boot_console):
+    """
+    Test load file from the symlink.
+    """
+    files = ['symfile']
+    sizes = ['7812']
+    address = '$kernel_addr_r'
+    erofs_load_files(u_boot_console, files, sizes, address)
+
+def erofs_load_non_existent_file(u_boot_console):
+    """
+    Test if the EROFS support will crash when load a nonexistent file.
+    """
+    address = '$kernel_addr_r'
+    file = 'non-existent'
+    out = u_boot_console.run_command('erofsload host 0 {} {}'.format(address, file))
+    assert 'Failed to load' in out
+
+def erofs_run_all_tests(u_boot_console):
+    """
+    Runs all test cases.
+    """
+    erofs_ls_at_root(u_boot_console)
+    erofs_ls_at_subdir(u_boot_console)
+    erofs_ls_at_symlink(u_boot_console)
+    erofs_ls_at_non_existent_dir(u_boot_console)
+    erofs_load_files_at_root(u_boot_console)
+    erofs_load_files_at_subdir(u_boot_console)
+    erofs_load_files_at_symlink(u_boot_console)
+    erofs_load_non_existent_file(u_boot_console)
+
+@pytest.mark.boardspec('sandbox')
+@pytest.mark.buildconfigspec('cmd_fs_generic')
+@pytest.mark.buildconfigspec('cmd_erofs')
+@pytest.mark.buildconfigspec('fs_erofs')
+@pytest.mark.requiredtool('mkfs.erofs')
+@pytest.mark.requiredtool('md5sum')
+
+def test_erofs(u_boot_console):
+    """
+    Executes the erofs test suite.
+    """
+    build_dir = u_boot_console.config.build_dir
+
+    try:
+        # setup test environment
+        make_erofs_image(build_dir)
+        image_path = os.path.join(build_dir, EROFS_IMAGE_NAME)
+        u_boot_console.run_command('host bind 0 {}'.format(image_path))
+        # run all tests
+        erofs_run_all_tests(u_boot_console)
+    except:
+        clean_erofs_image(build_dir)
+        raise AssertionError
+
+    # clean test environment
+    clean_erofs_image(build_dir)
diff --git a/tools/docker/Dockerfile b/tools/docker/Dockerfile
index 7a3f5cbade4..c51e3430137 100644
--- a/tools/docker/Dockerfile
+++ b/tools/docker/Dockerfile
@@ -2,7 +2,7 @@
 # This Dockerfile is used to build an image containing basic stuff to be used
 # to build U-Boot and run our test suites.
 
-FROM ubuntu:focal-20220113
+FROM ubuntu:focal-20220302
 MAINTAINER Tom Rini <trini@konsulko.com>
 LABEL Description=" This image is for building U-Boot inside a container"
 
@@ -48,6 +48,7 @@ RUN apt-get update && apt-get install -y \
 	dosfstools \
 	e2fsprogs \
 	efitools \
+	erofs-utils \
 	expect \
 	fakeroot \
 	flex \