bmap.c revision 062cc472e6cae60a1fa43976bcc6ff39f8351ccb 
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	blk64_t blk64;
139	blk_t addr_per_block;
140	blk_t	b, blk32;
141	char	*buf = 0;
142	errcode_t	retval = 0;
143	int		blocks_alloc = 0, inode_dirty = 0;
144
145	if (!(bmap_flags & BMAP_SET))
146		*phys_blk = 0;
147
148	if (ret_flags)
149		*ret_flags = 0;
150
151	/* Read inode structure if necessary */
152	if (!inode) {
153		retval = ext2fs_read_inode(fs, ino, &inode_buf);
154		if (retval)
155			return retval;
156		inode = &inode_buf;
157	}
158	addr_per_block = (blk_t) fs->blocksize >> 2;
159
160	if (inode->i_flags & EXT4_EXTENTS_FL) {
161		struct ext2fs_extent	extent;
162		unsigned int		offset;
163
164		retval = ext2fs_extent_open2(fs, ino, inode, &handle);
165		if (retval)
166			goto done;
167		if (bmap_flags & BMAP_SET) {
168			retval = ext2fs_extent_set_bmap(handle, block,
169							*phys_blk, 0);
170			goto done;
171		}
172		retval = ext2fs_extent_goto(handle, block);
173		if (retval) {
174			/* If the extent is not found, return phys_blk = 0 */
175			if (retval == EXT2_ET_EXTENT_NOT_FOUND)
176				goto got_block;
177			goto done;
178		}
179		retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
180		if (retval)
181			goto done;
182		offset = block - extent.e_lblk;
183		if (block >= extent.e_lblk && (offset <= extent.e_len)) {
184			*phys_blk = extent.e_pblk + offset;
185			if (ret_flags && extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
186				*ret_flags |= BMAP_RET_UNINIT;
187		}
188	got_block:
189		if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
190			retval = ext2fs_bmap2(fs, ino, inode, block_buf,
191					      0, block-1, 0, &blk64);
192			if (retval)
193				blk64 = 0;
194			retval = ext2fs_alloc_block2(fs, blk64, block_buf,
195						     &blk64);
196			if (retval)
197				goto done;
198			retval = ext2fs_extent_set_bmap(handle, block,
199							blk64, 0);
200			if (retval)
201				goto done;
202			/* Update inode after setting extent */
203			retval = ext2fs_read_inode(fs, ino, inode);
204			if (retval)
205				return retval;
206			blocks_alloc++;
207			*phys_blk = blk64;
208		}
209		retval = 0;
210		goto done;
211	}
212
213	if (!block_buf) {
214		retval = ext2fs_get_array(2, fs->blocksize, &buf);
215		if (retval)
216			return retval;
217		block_buf = buf;
218	}
219
220	if (block < EXT2_NDIR_BLOCKS) {
221		if (bmap_flags & BMAP_SET) {
222			b = *phys_blk;
223			inode_bmap(inode, block) = b;
224			inode_dirty++;
225			goto done;
226		}
227
228		*phys_blk = inode_bmap(inode, block);
229		b = block ? inode_bmap(inode, block-1) : 0;
230
231		if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
232			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
233			if (retval)
234				goto done;
235			inode_bmap(inode, block) = b;
236			blocks_alloc++;
237			*phys_blk = b;
238		}
239		goto done;
240	}
241
242	/* Indirect block */
243	block -= EXT2_NDIR_BLOCKS;
244	blk32 = *phys_blk;
245	if (block < addr_per_block) {
246		b = inode_bmap(inode, EXT2_IND_BLOCK);
247		if (!b) {
248			if (!(bmap_flags & BMAP_ALLOC)) {
249				if (bmap_flags & BMAP_SET)
250					retval = EXT2_ET_SET_BMAP_NO_IND;
251				goto done;
252			}
253
254			b = inode_bmap(inode, EXT2_IND_BLOCK-1);
255 			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
256			if (retval)
257				goto done;
258			inode_bmap(inode, EXT2_IND_BLOCK) = b;
259			blocks_alloc++;
260		}
261		retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
262					&blocks_alloc, block, &blk32);
263		if (retval == 0)
264			*phys_blk = blk32;
265		goto done;
266	}
267
268	/* Doubly indirect block  */
269	block -= addr_per_block;
270	if (block < addr_per_block * addr_per_block) {
271		b = inode_bmap(inode, EXT2_DIND_BLOCK);
272		if (!b) {
273			if (!(bmap_flags & BMAP_ALLOC)) {
274				if (bmap_flags & BMAP_SET)
275					retval = EXT2_ET_SET_BMAP_NO_IND;
276				goto done;
277			}
278
279			b = inode_bmap(inode, EXT2_IND_BLOCK);
280 			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
281			if (retval)
282				goto done;
283			inode_bmap(inode, EXT2_DIND_BLOCK) = b;
284			blocks_alloc++;
285		}
286		retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
287					 &blocks_alloc, block, &blk32);
288		if (retval == 0)
289			*phys_blk = blk32;
290		goto done;
291	}
292
293	/* Triply indirect block */
294	block -= addr_per_block * addr_per_block;
295	b = inode_bmap(inode, EXT2_TIND_BLOCK);
296	if (!b) {
297		if (!(bmap_flags & BMAP_ALLOC)) {
298			if (bmap_flags & BMAP_SET)
299				retval = EXT2_ET_SET_BMAP_NO_IND;
300			goto done;
301		}
302
303		b = inode_bmap(inode, EXT2_DIND_BLOCK);
304		retval = ext2fs_alloc_block(fs, b, block_buf, &b);
305		if (retval)
306			goto done;
307		inode_bmap(inode, EXT2_TIND_BLOCK) = b;
308		blocks_alloc++;
309	}
310	retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
311				 &blocks_alloc, block, &blk32);
312	if (retval == 0)
313		*phys_blk = blk32;
314done:
315	if (buf)
316		ext2fs_free_mem(&buf);
317	if (handle)
318		ext2fs_extent_free(handle);
319	if ((retval == 0) && (blocks_alloc || inode_dirty)) {
320		ext2fs_iblk_add_blocks(fs, inode, blocks_alloc);
321		retval = ext2fs_write_inode(fs, ino, inode);
322	}
323	return retval;
324}
325
326errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
327		      char *block_buf, int bmap_flags, blk_t block,
328		      blk_t *phys_blk)
329{
330	errcode_t ret;
331	blk64_t	ret_blk = *phys_blk;
332
333	ret = ext2fs_bmap2(fs, ino, inode, block_buf, bmap_flags, block,
334			    0, &ret_blk);
335	if (ret)
336		return ret;
337	if (ret_blk >= ((long long) 1 << 32))
338		return EOVERFLOW;
339	*phys_blk = ret_blk;
340	return 0;
341}
342