bmap.c revision 551e2e46ee2fdf8cfa16e153d3c560203f0f9a5e 
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
132static errcode_t extent_bmap(ext2_filsys fs, ext2_ino_t ino,
133			     struct ext2_inode *inode,
134			     ext2_extent_handle_t handle,
135			     char *block_buf, int bmap_flags, blk64_t block,
136			     int *ret_flags, int *blocks_alloc,
137			     blk64_t *phys_blk)
138{
139	struct ext2fs_extent	extent;
140	unsigned int		offset;
141	errcode_t		retval = 0;
142	blk64_t			blk64;
143
144	if (bmap_flags & BMAP_SET) {
145		retval = ext2fs_extent_set_bmap(handle, block,
146						*phys_blk, 0);
147		return retval;
148	}
149	retval = ext2fs_extent_goto(handle, block);
150	if (retval) {
151		/* If the extent is not found, return phys_blk = 0 */
152		if (retval == EXT2_ET_EXTENT_NOT_FOUND)
153			goto got_block;
154		return retval;
155	}
156	retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
157	if (retval)
158		return retval;
159	offset = block - extent.e_lblk;
160	if (block >= extent.e_lblk && (offset <= extent.e_len)) {
161		*phys_blk = extent.e_pblk + offset;
162		if (ret_flags && extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
163			*ret_flags |= BMAP_RET_UNINIT;
164	}
165got_block:
166	if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
167		retval = extent_bmap(fs, ino, inode, handle, block_buf,
168				     0, block-1, 0, blocks_alloc, &blk64);
169		if (retval)
170			blk64 = 0;
171		retval = ext2fs_alloc_block2(fs, blk64, block_buf,
172					     &blk64);
173		if (retval)
174			return retval;
175		retval = ext2fs_extent_set_bmap(handle, block,
176						blk64, 0);
177		if (retval)
178			return retval;
179		/* Update inode after setting extent */
180		retval = ext2fs_read_inode(fs, ino, inode);
181		if (retval)
182			return retval;
183		*blocks_alloc += 1;
184		*phys_blk = blk64;
185	}
186	return 0;
187}
188
189
190errcode_t ext2fs_bmap2(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
191		       char *block_buf, int bmap_flags, blk64_t block,
192		       int *ret_flags, blk64_t *phys_blk)
193{
194	struct ext2_inode inode_buf;
195	ext2_extent_handle_t handle = 0;
196	blk_t addr_per_block;
197	blk_t	b, blk32;
198	char	*buf = 0;
199	errcode_t	retval = 0;
200	int		blocks_alloc = 0, inode_dirty = 0;
201
202	if (!(bmap_flags & BMAP_SET))
203		*phys_blk = 0;
204
205	if (ret_flags)
206		*ret_flags = 0;
207
208	/* Read inode structure if necessary */
209	if (!inode) {
210		retval = ext2fs_read_inode(fs, ino, &inode_buf);
211		if (retval)
212			return retval;
213		inode = &inode_buf;
214	}
215	addr_per_block = (blk_t) fs->blocksize >> 2;
216
217	if (!block_buf) {
218		retval = ext2fs_get_array(2, fs->blocksize, &buf);
219		if (retval)
220			return retval;
221		block_buf = buf;
222	}
223
224	if (inode->i_flags & EXT4_EXTENTS_FL) {
225		retval = ext2fs_extent_open2(fs, ino, inode, &handle);
226		if (retval)
227			goto done;
228		retval = extent_bmap(fs, ino, inode, handle, block_buf,
229				     bmap_flags, block, ret_flags,
230				     &blocks_alloc, phys_blk);
231		goto done;
232	}
233
234	if (block < EXT2_NDIR_BLOCKS) {
235		if (bmap_flags & BMAP_SET) {
236			b = *phys_blk;
237			inode_bmap(inode, block) = b;
238			inode_dirty++;
239			goto done;
240		}
241
242		*phys_blk = inode_bmap(inode, block);
243		b = block ? inode_bmap(inode, block-1) : 0;
244
245		if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
246			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
247			if (retval)
248				goto done;
249			inode_bmap(inode, block) = b;
250			blocks_alloc++;
251			*phys_blk = b;
252		}
253		goto done;
254	}
255
256	/* Indirect block */
257	block -= EXT2_NDIR_BLOCKS;
258	blk32 = *phys_blk;
259	if (block < addr_per_block) {
260		b = inode_bmap(inode, EXT2_IND_BLOCK);
261		if (!b) {
262			if (!(bmap_flags & BMAP_ALLOC)) {
263				if (bmap_flags & BMAP_SET)
264					retval = EXT2_ET_SET_BMAP_NO_IND;
265				goto done;
266			}
267
268			b = inode_bmap(inode, EXT2_IND_BLOCK-1);
269 			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
270			if (retval)
271				goto done;
272			inode_bmap(inode, EXT2_IND_BLOCK) = b;
273			blocks_alloc++;
274		}
275		retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
276					&blocks_alloc, block, &blk32);
277		if (retval == 0)
278			*phys_blk = blk32;
279		goto done;
280	}
281
282	/* Doubly indirect block  */
283	block -= addr_per_block;
284	if (block < addr_per_block * addr_per_block) {
285		b = inode_bmap(inode, EXT2_DIND_BLOCK);
286		if (!b) {
287			if (!(bmap_flags & BMAP_ALLOC)) {
288				if (bmap_flags & BMAP_SET)
289					retval = EXT2_ET_SET_BMAP_NO_IND;
290				goto done;
291			}
292
293			b = inode_bmap(inode, EXT2_IND_BLOCK);
294 			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
295			if (retval)
296				goto done;
297			inode_bmap(inode, EXT2_DIND_BLOCK) = b;
298			blocks_alloc++;
299		}
300		retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
301					 &blocks_alloc, block, &blk32);
302		if (retval == 0)
303			*phys_blk = blk32;
304		goto done;
305	}
306
307	/* Triply indirect block */
308	block -= addr_per_block * addr_per_block;
309	b = inode_bmap(inode, EXT2_TIND_BLOCK);
310	if (!b) {
311		if (!(bmap_flags & BMAP_ALLOC)) {
312			if (bmap_flags & BMAP_SET)
313				retval = EXT2_ET_SET_BMAP_NO_IND;
314			goto done;
315		}
316
317		b = inode_bmap(inode, EXT2_DIND_BLOCK);
318		retval = ext2fs_alloc_block(fs, b, block_buf, &b);
319		if (retval)
320			goto done;
321		inode_bmap(inode, EXT2_TIND_BLOCK) = b;
322		blocks_alloc++;
323	}
324	retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
325				 &blocks_alloc, block, &blk32);
326	if (retval == 0)
327		*phys_blk = blk32;
328done:
329	if (buf)
330		ext2fs_free_mem(&buf);
331	if (handle)
332		ext2fs_extent_free(handle);
333	if ((retval == 0) && (blocks_alloc || inode_dirty)) {
334		ext2fs_iblk_add_blocks(fs, inode, blocks_alloc);
335		retval = ext2fs_write_inode(fs, ino, inode);
336	}
337	return retval;
338}
339
340errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
341		      char *block_buf, int bmap_flags, blk_t block,
342		      blk_t *phys_blk)
343{
344	errcode_t ret;
345	blk64_t	ret_blk = *phys_blk;
346
347	ret = ext2fs_bmap2(fs, ino, inode, block_buf, bmap_flags, block,
348			    0, &ret_blk);
349	if (ret)
350		return ret;
351	if (ret_blk >= ((long long) 1 << 32))
352		return EOVERFLOW;
353	*phys_blk = ret_blk;
354	return 0;
355}
356