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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 2382 | konopa | 1 | /* Superblock support. */ |
| 2 | |||
| 3 | /* Methods: |
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| 4 | * init_super: initializes the superblock structure for later use |
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| 5 | * get_super: return pointer at the superblock |
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| 6 | * read_super: read a superblock |
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| 7 | */ |
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| 8 | |||
| 9 | #include <string.h> |
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| 10 | #include "fs.h" |
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| 11 | #include "block.h" |
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| 12 | #include "inode.h" |
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| 13 | #include "super.h" |
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| 14 | #include <stdio.h> |
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| 15 | |||
| 16 | |||
| 17 | super_block_t* super_block; |
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| 18 | |||
| 19 | static int v1(int magic, int *version, int *extend); |
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| 20 | static int v2(int magic ,int*version, int *extend); |
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| 21 | static int get_native(int magic, int *version, int *extend); |
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| 22 | |||
| 23 | int (*versions[TOTAL_VERSIONS])(int , int*, int*) = { |
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| 24 | v1, /* 0 = V1 version */ |
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| 25 | v2 /* 1 = V2 version */ |
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| 26 | }; |
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| 27 | |||
| 28 | int init_super_block() |
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| 29 | { |
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| 30 | |||
| 31 | super_block = (super_block_t*)malloc(sizeof(super_block_t)); |
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| 32 | if (super_block != NULL) |
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| 33 | return TRUE; |
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| 34 | |||
| 35 | return FALSE; |
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| 36 | } |
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| 37 | |||
| 38 | super_block_t *get_super() |
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| 39 | { |
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| 40 | return super_block; |
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| 41 | } |
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| 42 | |||
| 43 | int read_super(register super_block_t *sp) |
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| 44 | { |
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| 45 | |||
| 46 | /* Read a superblock. */ |
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| 47 | |||
| 48 | register block_t *bp; |
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| 49 | int magic, version, extend, native; |
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| 50 | |||
| 51 | |||
| 52 | bp = get_block(SUPER_BLOCK); |
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| 53 | memcpy((void *)sp, (void *)(bp->b.b__data), (size_t)SUPER_SIZE); |
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| 54 | magic = sp->s_magic; /* determines file system type */ |
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| 55 | |||
| 56 | |||
| 57 | /* Get file system version and type. */ |
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| 58 | native = get_native(magic, &version, &extend); |
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| 59 | |||
| 60 | if (native == FS_EINVAL) { |
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| 61 | print_console("Unknown version of file system\n"); |
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| 62 | print_console("Magic is bad\n"); |
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| 63 | return FS_EINVAL; |
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| 64 | } |
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| 65 | |||
| 66 | /* In V1, the device size was kept in a short, s_nzones, which limited |
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| 67 | * devices to 32K zones. For V2, it was decided to keep the size as a |
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| 68 | * long. However, just changing s_nzones to a long would not work, since |
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| 69 | * then the position of s_magic in the super block would not be the same |
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| 70 | * in V1 and V2 file systems, and there would be no way to tell whether |
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| 71 | * a newly mounted file system was V1 or V2. The solution was to introduce |
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| 72 | * a new variable, s_zones, and copy the size there. |
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| 73 | * |
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| 74 | * Calculate some other numbers that depend on the version here too, to |
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| 75 | * hide some of the differences. |
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| 76 | */ |
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| 77 | |||
| 78 | if (version == V1) { |
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| 79 | sp->s_zones = sp->s_nzones; /* only V1 needs this copy */ |
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| 80 | sp->s_inodes_per_block = V1_INODES_PER_BLOCK; |
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| 81 | sp->s_ndzones = V1_NR_DZONES; |
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| 82 | sp->s_nindirs = V1_INDIRECTS; |
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| 83 | } |
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| 84 | else { |
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| 85 | sp->s_inodes_per_block = V2_INODES_PER_BLOCK; |
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| 86 | sp->s_ndzones = V2_NR_DZONES; |
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| 87 | sp->s_nindirs = V2_INDIRECTS; |
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| 88 | } |
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| 89 | |||
| 90 | sp->s_isearch = 0; /* inode searches initially start at 0 */ |
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| 91 | sp->s_zsearch = 0; /* zone searches initially start at 0 */ |
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| 92 | sp->s_version = version; |
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| 93 | sp->s_native = native; |
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| 94 | sp->s_extend = extend; |
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| 95 | |||
| 96 | |||
| 97 | /* Make a few basic checks to see if super block looks reasonable. */ |
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| 98 | if (sp->s_imap_blocks < 1 || sp->s_zmap_blocks < 1 |
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| 99 | || sp->s_ninodes < 1 || sp->s_zones < 1 |
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| 100 | || (unsigned) sp->s_log_zone_size > 4) { |
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| 101 | return FS_EINVAL; |
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| 102 | } |
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| 103 | |||
| 104 | return OK; |
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| 105 | } |
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| 106 | |||
| 107 | int v1(int magic, int* version, int *extend) |
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| 108 | { |
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| 109 | |||
| 110 | if (magic == SUPER_MAGIC || magic == conv2(BYTE_SWAP,SUPER_MAGIC)) { |
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| 111 | |||
| 112 | *version = V1; *extend = FALSE; |
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| 113 | return TRUE; |
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| 114 | } |
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| 115 | if (magic == SUPER_MAGIC2 || magic == conv2(BYTE_SWAP,SUPER_MAGIC2)) { |
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| 116 | *version = V1; *extend = TRUE; |
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| 117 | return TRUE; |
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| 118 | } |
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| 119 | |||
| 120 | return FALSE; |
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| 121 | } |
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| 122 | |||
| 123 | int v2(int magic, int *version, int *extend) |
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| 124 | { |
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| 125 | |||
| 126 | if (magic == SUPER_V2 || magic == conv2(BYTE_SWAP,SUPER_V2)) { |
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| 127 | *version = V2; *extend = FALSE; |
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| 128 | return TRUE; |
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| 129 | } |
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| 130 | |||
| 131 | if (magic == SUPER_V2E || magic == conv2(BYTE_SWAP,SUPER_V2E)) { |
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| 132 | *version = V2; *extend = TRUE; |
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| 133 | return TRUE; |
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| 134 | } |
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| 135 | |||
| 136 | return FALSE; |
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| 137 | } |
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| 138 | |||
| 139 | int get_native(int magic, int *version, int *extend) |
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| 140 | { |
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| 141 | |||
| 142 | |||
| 143 | int i, result; |
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| 144 | |||
| 145 | /* Get file system version and type */ |
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| 146 | for (i = 0; i < TOTAL_VERSIONS; i++) { |
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| 147 | result = versions[i](magic, version, extend); |
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| 148 | if (result) { |
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| 149 | return result; |
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| 150 | } |
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| 151 | } |
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| 152 | |||
| 153 | return FS_EINVAL; |
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| 154 | } |