1 /*-
2 * Copyright (c) 1989, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)ufs_bmap.c 8.7 (Berkeley) 3/21/95
35 * $FreeBSD: releng/9.1/sys/fs/ext2fs/ext2_bmap.c 229549 2012-01-05 01:35:01Z pfg $
36 */
37
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/bio.h>
41 #include <sys/buf.h>
42 #include <sys/proc.h>
43 #include <sys/vnode.h>
44 #include <sys/mount.h>
45 #include <sys/resourcevar.h>
46 #include <sys/stat.h>
47
48 #include <fs/ext2fs/inode.h>
49 #include <fs/ext2fs/ext2fs.h>
50 #include <fs/ext2fs/ext2_mount.h>
51 #include <fs/ext2fs/ext2_extern.h>
52
53 /*
54 * Bmap converts the logical block number of a file to its physical block
55 * number on the disk. The conversion is done by using the logical block
56 * number to index into the array of block pointers described by the dinode.
57 */
58 int
59 ext2_bmap(ap)
60 struct vop_bmap_args /* {
61 struct vnode *a_vp;
62 daddr_t a_bn;
63 struct bufobj **a_bop;
64 daddr_t *a_bnp;
65 int *a_runp;
66 int *a_runb;
67 } */ *ap;
68 {
69 int32_t blkno;
70 int error;
71
72 /*
73 * Check for underlying vnode requests and ensure that logical
74 * to physical mapping is requested.
75 */
76 if (ap->a_bop != NULL)
77 *ap->a_bop = &VTOI(ap->a_vp)->i_devvp->v_bufobj;
78 if (ap->a_bnp == NULL)
79 return (0);
80
81 error = ext2_bmaparray(ap->a_vp, ap->a_bn, &blkno,
82 ap->a_runp, ap->a_runb);
83 *ap->a_bnp = blkno;
84 return (error);
85 }
86
87 /*
88 * Indirect blocks are now on the vnode for the file. They are given negative
89 * logical block numbers. Indirect blocks are addressed by the negative
90 * address of the first data block to which they point. Double indirect blocks
91 * are addressed by one less than the address of the first indirect block to
92 * which they point. Triple indirect blocks are addressed by one less than
93 * the address of the first double indirect block to which they point.
94 *
95 * ext2_bmaparray does the bmap conversion, and if requested returns the
96 * array of logical blocks which must be traversed to get to a block.
97 * Each entry contains the offset into that block that gets you to the
98 * next block and the disk address of the block (if it is assigned).
99 */
100
101 int
102 ext2_bmaparray(vp, bn, bnp, runp, runb)
103 struct vnode *vp;
104 int32_t bn;
105 int32_t *bnp;
106 int *runp;
107 int *runb;
108 {
109 struct inode *ip;
110 struct buf *bp;
111 struct ext2mount *ump;
112 struct mount *mp;
113 struct vnode *devvp;
114 struct indir a[NIADDR+1], *ap;
115 int32_t daddr;
116 long metalbn;
117 int error, num, maxrun = 0, bsize;
118 int *nump;
119
120 ap = NULL;
121 ip = VTOI(vp);
122 mp = vp->v_mount;
123 ump = VFSTOEXT2(mp);
124 devvp = ump->um_devvp;
125
126 bsize = EXT2_BLOCK_SIZE(ump->um_e2fs);
127
128 if (runp) {
129 maxrun = mp->mnt_iosize_max / bsize - 1;
130 *runp = 0;
131 }
132
133 if (runb) {
134 *runb = 0;
135 }
136
137
138 ap = a;
139 nump = #
140 error = ext2_getlbns(vp, bn, ap, nump);
141 if (error)
142 return (error);
143
144 num = *nump;
145 if (num == 0) {
146 *bnp = blkptrtodb(ump, ip->i_db[bn]);
147 if (*bnp == 0) {
148 *bnp = -1;
149 } else if (runp) {
150 int32_t bnb = bn;
151 for (++bn; bn < NDADDR && *runp < maxrun &&
152 is_sequential(ump, ip->i_db[bn - 1], ip->i_db[bn]);
153 ++bn, ++*runp);
154 bn = bnb;
155 if (runb && (bn > 0)) {
156 for (--bn; (bn >= 0) && (*runb < maxrun) &&
157 is_sequential(ump, ip->i_db[bn],
158 ip->i_db[bn+1]);
159 --bn, ++*runb);
160 }
161 }
162 return (0);
163 }
164
165
166 /* Get disk address out of indirect block array */
167 daddr = ip->i_ib[ap->in_off];
168
169 for (bp = NULL, ++ap; --num; ++ap) {
170 /*
171 * Exit the loop if there is no disk address assigned yet and
172 * the indirect block isn't in the cache, or if we were
173 * looking for an indirect block and we've found it.
174 */
175
176 metalbn = ap->in_lbn;
177 if ((daddr == 0 && !incore(&vp->v_bufobj, metalbn)) || metalbn == bn)
178 break;
179 /*
180 * If we get here, we've either got the block in the cache
181 * or we have a disk address for it, go fetch it.
182 */
183 if (bp)
184 bqrelse(bp);
185
186 ap->in_exists = 1;
187 bp = getblk(vp, metalbn, bsize, 0, 0, 0);
188 if ((bp->b_flags & B_CACHE) == 0) {
189 #ifdef DIAGNOSTIC
190 if (!daddr)
191 panic("ufs_bmaparray: indirect block not in cache");
192 #endif
193 bp->b_blkno = blkptrtodb(ump, daddr);
194 bp->b_iocmd = BIO_READ;
195 bp->b_flags &= ~B_INVAL;
196 bp->b_ioflags &= ~BIO_ERROR;
197 vfs_busy_pages(bp, 0);
198 bp->b_iooffset = dbtob(bp->b_blkno);
199 bstrategy(bp);
200 curthread->td_ru.ru_inblock++;
201 error = bufwait(bp);
202 if (error) {
203 brelse(bp);
204 return (error);
205 }
206 }
207
208 daddr = ((int32_t *)bp->b_data)[ap->in_off];
209 if (num == 1 && daddr && runp) {
210 for (bn = ap->in_off + 1;
211 bn < MNINDIR(ump) && *runp < maxrun &&
212 is_sequential(ump,
213 ((int32_t *)bp->b_data)[bn - 1],
214 ((int32_t *)bp->b_data)[bn]);
215 ++bn, ++*runp);
216 bn = ap->in_off;
217 if (runb && bn) {
218 for (--bn; bn >= 0 && *runb < maxrun &&
219 is_sequential(ump, ((int32_t *)bp->b_data)[bn],
220 ((int32_t *)bp->b_data)[bn+1]);
221 --bn, ++*runb);
222 }
223 }
224 }
225 if (bp)
226 bqrelse(bp);
227
228 /*
229 * Since this is FFS independent code, we are out of scope for the
230 * definitions of BLK_NOCOPY and BLK_SNAP, but we do know that they
231 * will fall in the range 1..um_seqinc, so we use that test and
232 * return a request for a zeroed out buffer if attempts are made
233 * to read a BLK_NOCOPY or BLK_SNAP block.
234 */
235 if ((ip->i_flags & SF_SNAPSHOT) && daddr > 0 && daddr < ump->um_seqinc){
236 *bnp = -1;
237 return (0);
238 }
239 *bnp = blkptrtodb(ump, daddr);
240 if (*bnp == 0) {
241 *bnp = -1;
242 }
243 return (0);
244 }
245
246 /*
247 * Create an array of logical block number/offset pairs which represent the
248 * path of indirect blocks required to access a data block. The first "pair"
249 * contains the logical block number of the appropriate single, double or
250 * triple indirect block and the offset into the inode indirect block array.
251 * Note, the logical block number of the inode single/double/triple indirect
252 * block appears twice in the array, once with the offset into the i_ib and
253 * once with the offset into the page itself.
254 */
255 int
256 ext2_getlbns(vp, bn, ap, nump)
257 struct vnode *vp;
258 int32_t bn;
259 struct indir *ap;
260 int *nump;
261 {
262 long blockcnt, metalbn, realbn;
263 struct ext2mount *ump;
264 int i, numlevels, off;
265 int64_t qblockcnt;
266
267 ump = VFSTOEXT2(vp->v_mount);
268 if (nump)
269 *nump = 0;
270 numlevels = 0;
271 realbn = bn;
272 if ((long)bn < 0)
273 bn = -(long)bn;
274
275 /* The first NDADDR blocks are direct blocks. */
276 if (bn < NDADDR)
277 return (0);
278
279 /*
280 * Determine the number of levels of indirection. After this loop
281 * is done, blockcnt indicates the number of data blocks possible
282 * at the previous level of indirection, and NIADDR - i is the number
283 * of levels of indirection needed to locate the requested block.
284 */
285 for (blockcnt = 1, i = NIADDR, bn -= NDADDR;; i--, bn -= blockcnt) {
286 if (i == 0)
287 return (EFBIG);
288 /*
289 * Use int64_t's here to avoid overflow for triple indirect
290 * blocks when longs have 32 bits and the block size is more
291 * than 4K.
292 */
293 qblockcnt = (int64_t)blockcnt * MNINDIR(ump);
294 if (bn < qblockcnt)
295 break;
296 blockcnt = qblockcnt;
297 }
298
299 /* Calculate the address of the first meta-block. */
300 if (realbn >= 0)
301 metalbn = -(realbn - bn + NIADDR - i);
302 else
303 metalbn = -(-realbn - bn + NIADDR - i);
304
305 /*
306 * At each iteration, off is the offset into the bap array which is
307 * an array of disk addresses at the current level of indirection.
308 * The logical block number and the offset in that block are stored
309 * into the argument array.
310 */
311 ap->in_lbn = metalbn;
312 ap->in_off = off = NIADDR - i;
313 ap->in_exists = 0;
314 ap++;
315 for (++numlevels; i <= NIADDR; i++) {
316 /* If searching for a meta-data block, quit when found. */
317 if (metalbn == realbn)
318 break;
319
320 off = (bn / blockcnt) % MNINDIR(ump);
321
322 ++numlevels;
323 ap->in_lbn = metalbn;
324 ap->in_off = off;
325 ap->in_exists = 0;
326 ++ap;
327
328 metalbn -= -1 + off * blockcnt;
329 blockcnt /= MNINDIR(ump);
330 }
331 if (nump)
332 *nump = numlevels;
333 return (0);
334 }
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