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/9.2/sys/fs/ext2fs/ext2_bmap.c 252234 2013-06-26 04:34:16Z 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_extern.h>
51 #include <fs/ext2fs/ext2_mount.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(struct vop_bmap_args *ap)
60 {
61 int32_t blkno;
62 int error;
63
64 /*
65 * Check for underlying vnode requests and ensure that logical
66 * to physical mapping is requested.
67 */
68 if (ap->a_bop != NULL)
69 *ap->a_bop = &VTOI(ap->a_vp)->i_devvp->v_bufobj;
70 if (ap->a_bnp == NULL)
71 return (0);
72
73 error = ext2_bmaparray(ap->a_vp, ap->a_bn, &blkno,
74 ap->a_runp, ap->a_runb);
75 *ap->a_bnp = blkno;
76 return (error);
77 }
78
79 /*
80 * Indirect blocks are now on the vnode for the file. They are given negative
81 * logical block numbers. Indirect blocks are addressed by the negative
82 * address of the first data block to which they point. Double indirect blocks
83 * are addressed by one less than the address of the first indirect block to
84 * which they point. Triple indirect blocks are addressed by one less than
85 * the address of the first double indirect block to which they point.
86 *
87 * ext2_bmaparray does the bmap conversion, and if requested returns the
88 * array of logical blocks which must be traversed to get to a block.
89 * Each entry contains the offset into that block that gets you to the
90 * next block and the disk address of the block (if it is assigned).
91 */
92
93 int
94 ext2_bmaparray(struct vnode *vp, int32_t bn, int32_t *bnp, int *runp, int *runb)
95 {
96 struct inode *ip;
97 struct buf *bp;
98 struct ext2mount *ump;
99 struct mount *mp;
100 struct vnode *devvp;
101 struct indir a[NIADDR+1], *ap;
102 daddr_t daddr;
103 e2fs_lbn_t metalbn;
104 int error, num, maxrun = 0, bsize;
105 int *nump;
106
107 ap = NULL;
108 ip = VTOI(vp);
109 mp = vp->v_mount;
110 ump = VFSTOEXT2(mp);
111 devvp = ump->um_devvp;
112
113 bsize = EXT2_BLOCK_SIZE(ump->um_e2fs);
114
115 if (runp) {
116 maxrun = mp->mnt_iosize_max / bsize - 1;
117 *runp = 0;
118 }
119
120 if (runb) {
121 *runb = 0;
122 }
123
124
125 ap = a;
126 nump = #
127 error = ext2_getlbns(vp, bn, ap, nump);
128 if (error)
129 return (error);
130
131 num = *nump;
132 if (num == 0) {
133 *bnp = blkptrtodb(ump, ip->i_db[bn]);
134 if (*bnp == 0) {
135 *bnp = -1;
136 } else if (runp) {
137 int32_t bnb = bn;
138 for (++bn; bn < NDADDR && *runp < maxrun &&
139 is_sequential(ump, ip->i_db[bn - 1], ip->i_db[bn]);
140 ++bn, ++*runp);
141 bn = bnb;
142 if (runb && (bn > 0)) {
143 for (--bn; (bn >= 0) && (*runb < maxrun) &&
144 is_sequential(ump, ip->i_db[bn],
145 ip->i_db[bn+1]);
146 --bn, ++*runb);
147 }
148 }
149 return (0);
150 }
151
152
153 /* Get disk address out of indirect block array */
154 daddr = ip->i_ib[ap->in_off];
155
156 for (bp = NULL, ++ap; --num; ++ap) {
157 /*
158 * Exit the loop if there is no disk address assigned yet and
159 * the indirect block isn't in the cache, or if we were
160 * looking for an indirect block and we've found it.
161 */
162
163 metalbn = ap->in_lbn;
164 if ((daddr == 0 && !incore(&vp->v_bufobj, metalbn)) || metalbn == bn)
165 break;
166 /*
167 * If we get here, we've either got the block in the cache
168 * or we have a disk address for it, go fetch it.
169 */
170 if (bp)
171 bqrelse(bp);
172
173 bp = getblk(vp, metalbn, bsize, 0, 0, 0);
174 if ((bp->b_flags & B_CACHE) == 0) {
175 #ifdef INVARIANTS
176 if (!daddr)
177 panic("ext2_bmaparray: indirect block not in cache");
178 #endif
179 bp->b_blkno = blkptrtodb(ump, daddr);
180 bp->b_iocmd = BIO_READ;
181 bp->b_flags &= ~B_INVAL;
182 bp->b_ioflags &= ~BIO_ERROR;
183 vfs_busy_pages(bp, 0);
184 bp->b_iooffset = dbtob(bp->b_blkno);
185 bstrategy(bp);
186 curthread->td_ru.ru_inblock++;
187 error = bufwait(bp);
188 if (error) {
189 brelse(bp);
190 return (error);
191 }
192 }
193
194 daddr = ((int32_t *)bp->b_data)[ap->in_off];
195 if (num == 1 && daddr && runp) {
196 for (bn = ap->in_off + 1;
197 bn < MNINDIR(ump) && *runp < maxrun &&
198 is_sequential(ump,
199 ((int32_t *)bp->b_data)[bn - 1],
200 ((int32_t *)bp->b_data)[bn]);
201 ++bn, ++*runp);
202 bn = ap->in_off;
203 if (runb && bn) {
204 for (--bn; bn >= 0 && *runb < maxrun &&
205 is_sequential(ump, ((int32_t *)bp->b_data)[bn],
206 ((int32_t *)bp->b_data)[bn+1]);
207 --bn, ++*runb);
208 }
209 }
210 }
211 if (bp)
212 bqrelse(bp);
213
214 /*
215 * Since this is FFS independent code, we are out of scope for the
216 * definitions of BLK_NOCOPY and BLK_SNAP, but we do know that they
217 * will fall in the range 1..um_seqinc, so we use that test and
218 * return a request for a zeroed out buffer if attempts are made
219 * to read a BLK_NOCOPY or BLK_SNAP block.
220 */
221 if ((ip->i_flags & SF_SNAPSHOT) && daddr > 0 && daddr < ump->um_seqinc){
222 *bnp = -1;
223 return (0);
224 }
225 *bnp = blkptrtodb(ump, daddr);
226 if (*bnp == 0) {
227 *bnp = -1;
228 }
229 return (0);
230 }
231
232 /*
233 * Create an array of logical block number/offset pairs which represent the
234 * path of indirect blocks required to access a data block. The first "pair"
235 * contains the logical block number of the appropriate single, double or
236 * triple indirect block and the offset into the inode indirect block array.
237 * Note, the logical block number of the inode single/double/triple indirect
238 * block appears twice in the array, once with the offset into the i_ib and
239 * once with the offset into the page itself.
240 */
241 int
242 ext2_getlbns(struct vnode *vp, int32_t bn, struct indir *ap, int *nump)
243 {
244 long blockcnt;
245 e2fs_lbn_t metalbn, realbn;
246 struct ext2mount *ump;
247 int i, numlevels, off;
248 int64_t qblockcnt;
249
250 ump = VFSTOEXT2(vp->v_mount);
251 if (nump)
252 *nump = 0;
253 numlevels = 0;
254 realbn = bn;
255 if ((long)bn < 0)
256 bn = -(long)bn;
257
258 /* The first NDADDR blocks are direct blocks. */
259 if (bn < NDADDR)
260 return (0);
261
262 /*
263 * Determine the number of levels of indirection. After this loop
264 * is done, blockcnt indicates the number of data blocks possible
265 * at the previous level of indirection, and NIADDR - i is the number
266 * of levels of indirection needed to locate the requested block.
267 */
268 for (blockcnt = 1, i = NIADDR, bn -= NDADDR;; i--, bn -= blockcnt) {
269 if (i == 0)
270 return (EFBIG);
271 /*
272 * Use int64_t's here to avoid overflow for triple indirect
273 * blocks when longs have 32 bits and the block size is more
274 * than 4K.
275 */
276 qblockcnt = (int64_t)blockcnt * MNINDIR(ump);
277 if (bn < qblockcnt)
278 break;
279 blockcnt = qblockcnt;
280 }
281
282 /* Calculate the address of the first meta-block. */
283 if (realbn >= 0)
284 metalbn = -(realbn - bn + NIADDR - i);
285 else
286 metalbn = -(-realbn - bn + NIADDR - i);
287
288 /*
289 * At each iteration, off is the offset into the bap array which is
290 * an array of disk addresses at the current level of indirection.
291 * The logical block number and the offset in that block are stored
292 * into the argument array.
293 */
294 ap->in_lbn = metalbn;
295 ap->in_off = off = NIADDR - i;
296 ap++;
297 for (++numlevels; i <= NIADDR; i++) {
298 /* If searching for a meta-data block, quit when found. */
299 if (metalbn == realbn)
300 break;
301
302 off = (bn / blockcnt) % MNINDIR(ump);
303
304 ++numlevels;
305 ap->in_lbn = metalbn;
306 ap->in_off = off;
307 ++ap;
308
309 metalbn -= -1 + off * blockcnt;
310 blockcnt /= MNINDIR(ump);
311 }
312 if (nump)
313 *nump = numlevels;
314 return (0);
315 }
Cache object: 74dabc7c2251b64302d43a4ebcea50c3
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