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fs/erofs: add erofs filesystem support

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This patch mainly deals with uncompressed files.

Signed-off-by: Huang Jianan <jnhuang95@gmail.com>
This commit is contained in:
Huang Jianan
2022-02-26 15:05:47 +08:00
committed by Tom Rini
parent 17af72eb16
commit 830613f8f5
14 changed files with 1667 additions and 0 deletions
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7
MAINTAINERS
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@@ -809,6 +809,13 @@ 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: fs/erofs/
F: include/erofs.h
EVENTS
M: Simon Glass <sjg@chromium.org>
S: Maintained

2
fs/Kconfig
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@@ -24,4 +24,6 @@ source "fs/yaffs2/Kconfig"
source "fs/squashfs/Kconfig"
source "fs/erofs/Kconfig"
endmenu

1
fs/Makefile
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@@ -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

12
fs/erofs/Kconfig Normal file
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@@ -0,0 +1,12 @@
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.

7
fs/erofs/Makefile Normal file
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@@ -0,0 +1,7 @@
# SPDX-License-Identifier: GPL-2.0+
#
obj-$(CONFIG_$(SPL_)FS_EROFS) = fs.o \
super.o \
namei.o \
data.o

223
fs/erofs/data.c Normal file
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@@ -0,0 +1,223 @@
// SPDX-License-Identifier: GPL-2.0+
#include "internal.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;
}
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 -EOPNOTSUPP;
default:
break;
}
return -EINVAL;
}

436
fs/erofs/erofs_fs.h Normal file
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@@ -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

267
fs/erofs/fs.c Normal file
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// 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;
}

313
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/* 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

252
fs/erofs/namei.c Normal file
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// 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))
return -EOPNOTSUPP;
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);
}

105
fs/erofs/super.c Normal file
View File

@@ -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);
}

22
fs/fs.c
View File

@@ -26,6 +26,7 @@
#include <linux/math64.h>
#include <efi_loader.h>
#include <squashfs.h>
#include <erofs.h>
DECLARE_GLOBAL_DATA_PTR;
@@ -304,6 +305,27 @@ static struct fstype_info fstypes[] = {
.unlink = fs_unlink_unsupported,
.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,

19
include/erofs.h Normal file
View File

@@ -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 */

1
include/fs.h
View File

@@ -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;