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 * $FreeBSD$ 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(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 int32_t daddr; 103 long 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 DIAGNOSTIC 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, metalbn, realbn; 245 struct ext2mount *ump; 246 int i, numlevels, off; 247 int64_t qblockcnt; 248 249 ump = VFSTOEXT2(vp->v_mount); 250 if (nump) 251 *nump = 0; 252 numlevels = 0; 253 realbn = bn; 254 if ((long)bn < 0) 255 bn = -(long)bn; 256 257 /* The first NDADDR blocks are direct blocks. */ 258 if (bn < NDADDR) 259 return (0); 260 261 /* 262 * Determine the number of levels of indirection. After this loop 263 * is done, blockcnt indicates the number of data blocks possible 264 * at the previous level of indirection, and NIADDR - i is the number 265 * of levels of indirection needed to locate the requested block. 266 */ 267 for (blockcnt = 1, i = NIADDR, bn -= NDADDR;; i--, bn -= blockcnt) { 268 if (i == 0) 269 return (EFBIG); 270 /* 271 * Use int64_t's here to avoid overflow for triple indirect 272 * blocks when longs have 32 bits and the block size is more 273 * than 4K. 274 */ 275 qblockcnt = (int64_t)blockcnt * MNINDIR(ump); 276 if (bn < qblockcnt) 277 break; 278 blockcnt = qblockcnt; 279 } 280 281 /* Calculate the address of the first meta-block. */ 282 if (realbn >= 0) 283 metalbn = -(realbn - bn + NIADDR - i); 284 else 285 metalbn = -(-realbn - bn + NIADDR - i); 286 287 /* 288 * At each iteration, off is the offset into the bap array which is 289 * an array of disk addresses at the current level of indirection. 290 * The logical block number and the offset in that block are stored 291 * into the argument array. 292 */ 293 ap->in_lbn = metalbn; 294 ap->in_off = off = NIADDR - i; 295 ap++; 296 for (++numlevels; i <= NIADDR; i++) { 297 /* If searching for a meta-data block, quit when found. */ 298 if (metalbn == realbn) 299 break; 300 301 off = (bn / blockcnt) % MNINDIR(ump); 302 303 ++numlevels; 304 ap->in_lbn = metalbn; 305 ap->in_off = off; 306 ++ap; 307 308 metalbn -= -1 + off * blockcnt; 309 blockcnt /= MNINDIR(ump); 310 } 311 if (nump) 312 *nump = numlevels; 313 return (0); 314 } 315