blob: 796b0e4f51196ab2be5d6a701fca12232663bf18
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * bmap.c --- logical to physical block mapping |
4 | * |
5 | * Copyright (C) 1997 Theodore Ts'o. |
6 | * |
7 | * %Begin-Header% |
8 | * This file may be redistributed under the terms of the GNU Public |
9 | * License. |
10 | * %End-Header% |
11 | */ |
12 | |
13 | #include <stdio.h> |
14 | #include <string.h> |
15 | #if HAVE_UNISTD_H |
16 | #include <unistd.h> |
17 | #endif |
18 | |
19 | #include "ext2_fs.h" |
20 | #include "ext2fs.h" |
21 | |
22 | extern errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, |
23 | struct ext2_inode *inode, |
24 | char *block_buf, int bmap_flags, |
25 | blk_t block, blk_t *phys_blk); |
26 | |
27 | #define inode_bmap(inode, nr) ((inode)->i_block[(nr)]) |
28 | |
29 | static errcode_t block_ind_bmap(ext2_filsys fs, int flags, |
30 | blk_t ind, char *block_buf, |
31 | int *blocks_alloc, |
32 | blk_t nr, blk_t *ret_blk) |
33 | { |
34 | errcode_t retval; |
35 | blk_t b; |
36 | |
37 | if (!ind) { |
38 | if (flags & BMAP_SET) |
39 | return EXT2_ET_SET_BMAP_NO_IND; |
40 | *ret_blk = 0; |
41 | return 0; |
42 | } |
43 | retval = io_channel_read_blk(fs->io, ind, 1, block_buf); |
44 | if (retval) |
45 | return retval; |
46 | |
47 | if (flags & BMAP_SET) { |
48 | b = *ret_blk; |
49 | #if BB_BIG_ENDIAN |
50 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) || |
51 | (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)) |
52 | b = ext2fs_swab32(b); |
53 | #endif |
54 | ((blk_t *) block_buf)[nr] = b; |
55 | return io_channel_write_blk(fs->io, ind, 1, block_buf); |
56 | } |
57 | |
58 | b = ((blk_t *) block_buf)[nr]; |
59 | |
60 | #if BB_BIG_ENDIAN |
61 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) || |
62 | (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)) |
63 | b = ext2fs_swab32(b); |
64 | #endif |
65 | |
66 | if (!b && (flags & BMAP_ALLOC)) { |
67 | b = nr ? ((blk_t *) block_buf)[nr-1] : 0; |
68 | retval = ext2fs_alloc_block(fs, b, |
69 | block_buf + fs->blocksize, &b); |
70 | if (retval) |
71 | return retval; |
72 | |
73 | #if BB_BIG_ENDIAN |
74 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) || |
75 | (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)) |
76 | ((blk_t *) block_buf)[nr] = ext2fs_swab32(b); |
77 | else |
78 | #endif |
79 | ((blk_t *) block_buf)[nr] = b; |
80 | |
81 | retval = io_channel_write_blk(fs->io, ind, 1, block_buf); |
82 | if (retval) |
83 | return retval; |
84 | |
85 | (*blocks_alloc)++; |
86 | } |
87 | |
88 | *ret_blk = b; |
89 | return 0; |
90 | } |
91 | |
92 | static errcode_t block_dind_bmap(ext2_filsys fs, int flags, |
93 | blk_t dind, char *block_buf, |
94 | int *blocks_alloc, |
95 | blk_t nr, blk_t *ret_blk) |
96 | { |
97 | blk_t b; |
98 | errcode_t retval; |
99 | blk_t addr_per_block; |
100 | |
101 | addr_per_block = (blk_t) fs->blocksize >> 2; |
102 | |
103 | retval = block_ind_bmap(fs, flags & ~BMAP_SET, dind, block_buf, |
104 | blocks_alloc, nr / addr_per_block, &b); |
105 | if (retval) |
106 | return retval; |
107 | retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc, |
108 | nr % addr_per_block, ret_blk); |
109 | return retval; |
110 | } |
111 | |
112 | static errcode_t block_tind_bmap(ext2_filsys fs, int flags, |
113 | blk_t tind, char *block_buf, |
114 | int *blocks_alloc, |
115 | blk_t nr, blk_t *ret_blk) |
116 | { |
117 | blk_t b; |
118 | errcode_t retval; |
119 | blk_t addr_per_block; |
120 | |
121 | addr_per_block = (blk_t) fs->blocksize >> 2; |
122 | |
123 | retval = block_dind_bmap(fs, flags & ~BMAP_SET, tind, block_buf, |
124 | blocks_alloc, nr / addr_per_block, &b); |
125 | if (retval) |
126 | return retval; |
127 | retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc, |
128 | nr % addr_per_block, ret_blk); |
129 | return retval; |
130 | } |
131 | |
132 | errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode, |
133 | char *block_buf, int bmap_flags, blk_t block, |
134 | blk_t *phys_blk) |
135 | { |
136 | struct ext2_inode inode_buf; |
137 | blk_t addr_per_block; |
138 | blk_t b; |
139 | char *buf = NULL; |
140 | errcode_t retval = 0; |
141 | int blocks_alloc = 0, inode_dirty = 0; |
142 | |
143 | if (!(bmap_flags & BMAP_SET)) |
144 | *phys_blk = 0; |
145 | |
146 | /* Read inode structure if necessary */ |
147 | if (!inode) { |
148 | retval = ext2fs_read_inode(fs, ino, &inode_buf); |
149 | if (retval) |
150 | return retval; |
151 | inode = &inode_buf; |
152 | } |
153 | addr_per_block = (blk_t) fs->blocksize >> 2; |
154 | |
155 | if (!block_buf) { |
156 | retval = ext2fs_get_mem(fs->blocksize * 2, &buf); |
157 | if (retval) |
158 | return retval; |
159 | block_buf = buf; |
160 | } |
161 | |
162 | if (block < EXT2_NDIR_BLOCKS) { |
163 | if (bmap_flags & BMAP_SET) { |
164 | b = *phys_blk; |
165 | #if BB_BIG_ENDIAN |
166 | if ((fs->flags & EXT2_FLAG_SWAP_BYTES) || |
167 | (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)) |
168 | b = ext2fs_swab32(b); |
169 | #endif |
170 | inode_bmap(inode, block) = b; |
171 | inode_dirty++; |
172 | goto done; |
173 | } |
174 | |
175 | *phys_blk = inode_bmap(inode, block); |
176 | b = block ? inode_bmap(inode, block-1) : 0; |
177 | |
178 | if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) { |
179 | retval = ext2fs_alloc_block(fs, b, block_buf, &b); |
180 | if (retval) |
181 | goto done; |
182 | inode_bmap(inode, block) = b; |
183 | blocks_alloc++; |
184 | *phys_blk = b; |
185 | } |
186 | goto done; |
187 | } |
188 | |
189 | /* Indirect block */ |
190 | block -= EXT2_NDIR_BLOCKS; |
191 | if (block < addr_per_block) { |
192 | b = inode_bmap(inode, EXT2_IND_BLOCK); |
193 | if (!b) { |
194 | if (!(bmap_flags & BMAP_ALLOC)) { |
195 | if (bmap_flags & BMAP_SET) |
196 | retval = EXT2_ET_SET_BMAP_NO_IND; |
197 | goto done; |
198 | } |
199 | |
200 | b = inode_bmap(inode, EXT2_IND_BLOCK-1); |
201 | retval = ext2fs_alloc_block(fs, b, block_buf, &b); |
202 | if (retval) |
203 | goto done; |
204 | inode_bmap(inode, EXT2_IND_BLOCK) = b; |
205 | blocks_alloc++; |
206 | } |
207 | retval = block_ind_bmap(fs, bmap_flags, b, block_buf, |
208 | &blocks_alloc, block, phys_blk); |
209 | goto done; |
210 | } |
211 | |
212 | /* Doubly indirect block */ |
213 | block -= addr_per_block; |
214 | if (block < addr_per_block * addr_per_block) { |
215 | b = inode_bmap(inode, EXT2_DIND_BLOCK); |
216 | if (!b) { |
217 | if (!(bmap_flags & BMAP_ALLOC)) { |
218 | if (bmap_flags & BMAP_SET) |
219 | retval = EXT2_ET_SET_BMAP_NO_IND; |
220 | goto done; |
221 | } |
222 | |
223 | b = inode_bmap(inode, EXT2_IND_BLOCK); |
224 | retval = ext2fs_alloc_block(fs, b, block_buf, &b); |
225 | if (retval) |
226 | goto done; |
227 | inode_bmap(inode, EXT2_DIND_BLOCK) = b; |
228 | blocks_alloc++; |
229 | } |
230 | retval = block_dind_bmap(fs, bmap_flags, b, block_buf, |
231 | &blocks_alloc, block, phys_blk); |
232 | goto done; |
233 | } |
234 | |
235 | /* Triply indirect block */ |
236 | block -= addr_per_block * addr_per_block; |
237 | b = inode_bmap(inode, EXT2_TIND_BLOCK); |
238 | if (!b) { |
239 | if (!(bmap_flags & BMAP_ALLOC)) { |
240 | if (bmap_flags & BMAP_SET) |
241 | retval = EXT2_ET_SET_BMAP_NO_IND; |
242 | goto done; |
243 | } |
244 | |
245 | b = inode_bmap(inode, EXT2_DIND_BLOCK); |
246 | retval = ext2fs_alloc_block(fs, b, block_buf, &b); |
247 | if (retval) |
248 | goto done; |
249 | inode_bmap(inode, EXT2_TIND_BLOCK) = b; |
250 | blocks_alloc++; |
251 | } |
252 | retval = block_tind_bmap(fs, bmap_flags, b, block_buf, |
253 | &blocks_alloc, block, phys_blk); |
254 | done: |
255 | ext2fs_free_mem(&buf); |
256 | if ((retval == 0) && (blocks_alloc || inode_dirty)) { |
257 | inode->i_blocks += (blocks_alloc * fs->blocksize) / 512; |
258 | retval = ext2fs_write_inode(fs, ino, inode); |
259 | } |
260 | return retval; |
261 | } |
262 |