bmap.c revision a6ce1349539f866334ef3d5758bc2ee44a454acd 
1/*
2 * bmap.c --- logical to physical block mapping
3 *
4 * Copyright (C) 1997 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Library
8 * General Public License, version 2.
9 * %End-Header%
10 */
11
12#include <stdio.h>
13#include <string.h>
14#if HAVE_UNISTD_H
15#include <unistd.h>
16#endif
17#include <errno.h>
18
19#include "ext2_fs.h"
20#include "ext2fs.h"
21
22#if defined(__GNUC__) && !defined(NO_INLINE_FUNCS)
23#define _BMAP_INLINE_	__inline__
24#else
25#define _BMAP_INLINE_
26#endif
27
28extern errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino,
29			     struct ext2_inode *inode,
30			     char *block_buf, int bmap_flags,
31			     blk_t block, blk_t *phys_blk);
32
33#define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
34
35static _BMAP_INLINE_ errcode_t block_ind_bmap(ext2_filsys fs, int flags,
36					      blk_t ind, char *block_buf,
37					      int *blocks_alloc,
38					      blk_t nr, blk_t *ret_blk)
39{
40	errcode_t	retval;
41	blk_t		b;
42
43	if (!ind) {
44		if (flags & BMAP_SET)
45			return EXT2_ET_SET_BMAP_NO_IND;
46		*ret_blk = 0;
47		return 0;
48	}
49	retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
50	if (retval)
51		return retval;
52
53	if (flags & BMAP_SET) {
54		b = *ret_blk;
55#ifdef WORDS_BIGENDIAN
56		b = ext2fs_swab32(b);
57#endif
58		((blk_t *) block_buf)[nr] = b;
59		return io_channel_write_blk(fs->io, ind, 1, block_buf);
60	}
61
62	b = ((blk_t *) block_buf)[nr];
63
64#ifdef WORDS_BIGENDIAN
65	b = ext2fs_swab32(b);
66#endif
67
68	if (!b && (flags & BMAP_ALLOC)) {
69		b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
70		retval = ext2fs_alloc_block(fs, b,
71					    block_buf + fs->blocksize, &b);
72		if (retval)
73			return retval;
74
75#ifdef WORDS_BIGENDIAN
76		((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
77#else
78		((blk_t *) block_buf)[nr] = b;
79#endif
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
92static _BMAP_INLINE_ 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
112static _BMAP_INLINE_ 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
132errcode_t ext2fs_bmap2(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
133		       char *block_buf, int bmap_flags, blk64_t block,
134		       int *ret_flags, blk64_t *phys_blk)
135{
136	struct ext2_inode inode_buf;
137	ext2_extent_handle_t handle = 0;
138	blk_t addr_per_block;
139	blk_t	b, blk32;
140	char	*buf = 0;
141	errcode_t	retval = 0;
142	int		blocks_alloc = 0, inode_dirty = 0;
143
144	if (!(bmap_flags & BMAP_SET))
145		*phys_blk = 0;
146
147	if (ret_flags)
148		*ret_flags = 0;
149
150	/* Read inode structure if necessary */
151	if (!inode) {
152		retval = ext2fs_read_inode(fs, ino, &inode_buf);
153		if (retval)
154			return retval;
155		inode = &inode_buf;
156	}
157	addr_per_block = (blk_t) fs->blocksize >> 2;
158
159	if (inode->i_flags & EXT4_EXTENTS_FL) {
160		struct ext2fs_extent	extent;
161		unsigned int		offset;
162
163		retval = ext2fs_extent_open2(fs, ino, inode, &handle);
164		if (retval)
165			goto done;
166		if (bmap_flags & BMAP_SET) {
167			retval = ext2fs_extent_set_bmap(handle, block,
168							*phys_blk, 0);
169			goto done;
170		}
171		retval = ext2fs_extent_goto(handle, block);
172		if (retval) {
173			/* If the extent is not found, return phys_blk = 0 */
174			if (retval == EXT2_ET_EXTENT_NOT_FOUND)
175				goto got_block;
176			goto done;
177		}
178		retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
179		if (retval)
180			goto done;
181		offset = block - extent.e_lblk;
182		if (block >= extent.e_lblk && (offset <= extent.e_len)) {
183			*phys_blk = extent.e_pblk + offset;
184			if (ret_flags && extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
185				*ret_flags |= BMAP_RET_UNINIT;
186		}
187	got_block:
188		if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
189			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
190			if (retval)
191				goto done;
192			retval = ext2fs_extent_set_bmap(handle, block,
193							(blk64_t) b, 0);
194			if (retval)
195				goto done;
196			/* Update inode after setting extent */
197			retval = ext2fs_read_inode(fs, ino, inode);
198			if (retval)
199				return retval;
200			blocks_alloc++;
201			*phys_blk = b;
202		}
203		retval = 0;
204		goto done;
205	}
206
207	if (!block_buf) {
208		retval = ext2fs_get_array(2, fs->blocksize, &buf);
209		if (retval)
210			return retval;
211		block_buf = buf;
212	}
213
214	if (block < EXT2_NDIR_BLOCKS) {
215		if (bmap_flags & BMAP_SET) {
216			b = *phys_blk;
217			inode_bmap(inode, block) = b;
218			inode_dirty++;
219			goto done;
220		}
221
222		*phys_blk = inode_bmap(inode, block);
223		b = block ? inode_bmap(inode, block-1) : 0;
224
225		if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
226			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
227			if (retval)
228				goto done;
229			inode_bmap(inode, block) = b;
230			blocks_alloc++;
231			*phys_blk = b;
232		}
233		goto done;
234	}
235
236	/* Indirect block */
237	block -= EXT2_NDIR_BLOCKS;
238	blk32 = *phys_blk;
239	if (block < addr_per_block) {
240		b = inode_bmap(inode, EXT2_IND_BLOCK);
241		if (!b) {
242			if (!(bmap_flags & BMAP_ALLOC)) {
243				if (bmap_flags & BMAP_SET)
244					retval = EXT2_ET_SET_BMAP_NO_IND;
245				goto done;
246			}
247
248			b = inode_bmap(inode, EXT2_IND_BLOCK-1);
249 			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
250			if (retval)
251				goto done;
252			inode_bmap(inode, EXT2_IND_BLOCK) = b;
253			blocks_alloc++;
254		}
255		retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
256					&blocks_alloc, block, &blk32);
257		if (retval == 0)
258			*phys_blk = blk32;
259		goto done;
260	}
261
262	/* Doubly indirect block  */
263	block -= addr_per_block;
264	if (block < addr_per_block * addr_per_block) {
265		b = inode_bmap(inode, EXT2_DIND_BLOCK);
266		if (!b) {
267			if (!(bmap_flags & BMAP_ALLOC)) {
268				if (bmap_flags & BMAP_SET)
269					retval = EXT2_ET_SET_BMAP_NO_IND;
270				goto done;
271			}
272
273			b = inode_bmap(inode, EXT2_IND_BLOCK);
274 			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
275			if (retval)
276				goto done;
277			inode_bmap(inode, EXT2_DIND_BLOCK) = b;
278			blocks_alloc++;
279		}
280		retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
281					 &blocks_alloc, block, &blk32);
282		if (retval == 0)
283			*phys_blk = blk32;
284		goto done;
285	}
286
287	/* Triply indirect block */
288	block -= addr_per_block * addr_per_block;
289	b = inode_bmap(inode, EXT2_TIND_BLOCK);
290	if (!b) {
291		if (!(bmap_flags & BMAP_ALLOC)) {
292			if (bmap_flags & BMAP_SET)
293				retval = EXT2_ET_SET_BMAP_NO_IND;
294			goto done;
295		}
296
297		b = inode_bmap(inode, EXT2_DIND_BLOCK);
298		retval = ext2fs_alloc_block(fs, b, block_buf, &b);
299		if (retval)
300			goto done;
301		inode_bmap(inode, EXT2_TIND_BLOCK) = b;
302		blocks_alloc++;
303	}
304	retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
305				 &blocks_alloc, block, &blk32);
306	if (retval == 0)
307		*phys_blk = blk32;
308done:
309	if (buf)
310		ext2fs_free_mem(&buf);
311	if (handle)
312		ext2fs_extent_free(handle);
313	if ((retval == 0) && (blocks_alloc || inode_dirty)) {
314		ext2fs_iblk_add_blocks(fs, inode, blocks_alloc);
315		retval = ext2fs_write_inode(fs, ino, inode);
316	}
317	return retval;
318}
319
320errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
321		      char *block_buf, int bmap_flags, blk_t block,
322		      blk_t *phys_blk)
323{
324	errcode_t ret;
325	blk64_t	ret_blk = *phys_blk;
326
327	ret = ext2fs_bmap2(fs, ino, inode, block_buf, bmap_flags, block,
328			    0, &ret_blk);
329	if (ret)
330		return ret;
331	if (ret_blk >= ((long long) 1 << 32))
332		return EOVERFLOW;
333	*phys_blk = ret_blk;
334	return 0;
335}
336