68 lines
2.1 KiB
C
68 lines
2.1 KiB
C
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/*
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* volume_id - reads filesystem label and uuid
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*
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* Copyright (C) 2020 Norbert Lange <nolange79@gmail.com>
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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//config:config FEATURE_VOLUMEID_EROFS
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//config: bool "erofs filesystem"
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//config: default y
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//config: depends on VOLUMEID
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//config: help
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//config: Erofs is a compressed readonly filesystem for Linux.
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//kbuild:lib-$(CONFIG_FEATURE_VOLUMEID_EROFS) += erofs.o
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#include "volume_id_internal.h"
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#define EROFS_SUPER_MAGIC_V1 0xE0F5E1E2
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#define EROFS_SUPER_OFFSET 1024
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#define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001
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/* 128-byte erofs on-disk super block */
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struct erofs_super_block {
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uint32_t magic; /* file system magic number */
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uint32_t checksum; /* crc32c(super_block) */
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uint32_t feature_compat;
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uint8_t blkszbits; /* support block_size == PAGE_SIZE only */
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uint8_t reserved;
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uint16_t root_nid; /* nid of root directory */
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uint64_t inos; /* total valid ino # (== f_files - f_favail) */
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uint64_t build_time; /* inode v1 time derivation */
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uint32_t build_time_nsec; /* inode v1 time derivation in nano scale */
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uint32_t blocks; /* used for statfs */
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uint32_t meta_blkaddr; /* start block address of metadata area */
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uint32_t xattr_blkaddr; /* start block address of shared xattr area */
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uint8_t uuid[16]; /* 128-bit uuid for volume */
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uint8_t volume_name[16]; /* volume name */
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uint32_t feature_incompat;
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uint8_t reserved2[44];
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} PACKED;
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int FAST_FUNC volume_id_probe_erofs(struct volume_id *id /*,uint64_t off*/)
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{
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struct erofs_super_block *sb;
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BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
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dbg("erofs: probing at offset 0x%llx", EROFS_SUPER_OFFSET);
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sb = volume_id_get_buffer(id, EROFS_SUPER_OFFSET, sizeof(*sb));
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if (!sb)
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return -1;
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if (sb->magic != cpu_to_le32(EROFS_SUPER_MAGIC_V1))
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return -1;
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IF_FEATURE_BLKID_TYPE(id->type = "erofs");
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volume_id_set_label_string(id, sb->volume_name,
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MIN(sizeof(sb->volume_name), VOLUME_ID_LABEL_SIZE));
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volume_id_set_uuid(id, sb->uuid, UUID_DCE);
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return 0;
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}
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