ext2_bmap.c revision 261311
1209920Snwhitehorn/*- 2209920Snwhitehorn * Copyright (c) 1989, 1991, 1993 3209920Snwhitehorn * The Regents of the University of California. All rights reserved. 4209920Snwhitehorn * (c) UNIX System Laboratories, Inc. 5209920Snwhitehorn * All or some portions of this file are derived from material licensed 6209920Snwhitehorn * to the University of California by American Telephone and Telegraph 7209920Snwhitehorn * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8209920Snwhitehorn * the permission of UNIX System Laboratories, Inc. 9209920Snwhitehorn * 10209920Snwhitehorn * Redistribution and use in source and binary forms, with or without 11209920Snwhitehorn * modification, are permitted provided that the following conditions 12209920Snwhitehorn * are met: 13209920Snwhitehorn * 1. Redistributions of source code must retain the above copyright 14209920Snwhitehorn * notice, this list of conditions and the following disclaimer. 15209920Snwhitehorn * 2. Redistributions in binary form must reproduce the above copyright 16209920Snwhitehorn * notice, this list of conditions and the following disclaimer in the 17209920Snwhitehorn * documentation and/or other materials provided with the distribution. 18209920Snwhitehorn * 4. Neither the name of the University nor the names of its contributors 19209920Snwhitehorn * may be used to endorse or promote products derived from this software 20209920Snwhitehorn * without specific prior written permission. 21209920Snwhitehorn * 22209920Snwhitehorn * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23209920Snwhitehorn * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24209920Snwhitehorn * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25209920Snwhitehorn * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26209920Snwhitehorn * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27209920Snwhitehorn * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28209920Snwhitehorn * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29209920Snwhitehorn * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30209920Snwhitehorn * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31209920Snwhitehorn * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32209920Snwhitehorn * SUCH DAMAGE. 33209920Snwhitehorn * 34209920Snwhitehorn * @(#)ufs_bmap.c 8.7 (Berkeley) 3/21/95 35209920Snwhitehorn * $FreeBSD: stable/10/sys/fs/ext2fs/ext2_bmap.c 261311 2014-01-31 03:58:36Z pfg $ 36209920Snwhitehorn */ 37209920Snwhitehorn 38209920Snwhitehorn#include <sys/param.h> 39209920Snwhitehorn#include <sys/systm.h> 40209920Snwhitehorn#include <sys/bio.h> 41209920Snwhitehorn#include <sys/buf.h> 42209920Snwhitehorn#include <sys/proc.h> 43209920Snwhitehorn#include <sys/vnode.h> 44209920Snwhitehorn#include <sys/mount.h> 45209920Snwhitehorn#include <sys/resourcevar.h> 46209920Snwhitehorn#include <sys/stat.h> 47209920Snwhitehorn 48209920Snwhitehorn#include <fs/ext2fs/inode.h> 49209920Snwhitehorn#include <fs/ext2fs/fs.h> 50209920Snwhitehorn#include <fs/ext2fs/ext2fs.h> 51209920Snwhitehorn#include <fs/ext2fs/ext2_dinode.h> 52209920Snwhitehorn#include <fs/ext2fs/ext2_extern.h> 53209920Snwhitehorn#include <fs/ext2fs/ext2_mount.h> 54209920Snwhitehorn 55209920Snwhitehornstatic int ext4_bmapext(struct vnode *, int32_t, int64_t *, int *, int *); 56209920Snwhitehorn 57209920Snwhitehorn/* 58209920Snwhitehorn * Bmap converts the logical block number of a file to its physical block 59209920Snwhitehorn * number on the disk. The conversion is done by using the logical block 60209920Snwhitehorn * number to index into the array of block pointers described by the dinode. 61209920Snwhitehorn */ 62209920Snwhitehornint 63209920Snwhitehornext2_bmap(struct vop_bmap_args *ap) 64209920Snwhitehorn{ 65209920Snwhitehorn daddr_t blkno; 66209920Snwhitehorn int error; 67209920Snwhitehorn 68209920Snwhitehorn /* 69209920Snwhitehorn * Check for underlying vnode requests and ensure that logical 70209920Snwhitehorn * to physical mapping is requested. 71209920Snwhitehorn */ 72209920Snwhitehorn if (ap->a_bop != NULL) 73209920Snwhitehorn *ap->a_bop = &VTOI(ap->a_vp)->i_devvp->v_bufobj; 74209920Snwhitehorn if (ap->a_bnp == NULL) 75209920Snwhitehorn return (0); 76209920Snwhitehorn 77209920Snwhitehorn if (VTOI(ap->a_vp)->i_flag & IN_E4EXTENTS) 78209920Snwhitehorn error = ext4_bmapext(ap->a_vp, ap->a_bn, &blkno, 79209920Snwhitehorn ap->a_runp, ap->a_runb); 80209920Snwhitehorn else 81209920Snwhitehorn error = ext2_bmaparray(ap->a_vp, ap->a_bn, &blkno, 82209920Snwhitehorn ap->a_runp, ap->a_runb); 83209920Snwhitehorn *ap->a_bnp = blkno; 84209920Snwhitehorn return (error); 85209920Snwhitehorn} 86209920Snwhitehorn 87209920Snwhitehorn/* 88209920Snwhitehorn * This function converts the logical block number of a file to 89209920Snwhitehorn * its physical block number on the disk within ext4 extents. 90209920Snwhitehorn */ 91209920Snwhitehornstatic int 92209920Snwhitehornext4_bmapext(struct vnode *vp, int32_t bn, int64_t *bnp, int *runp, int *runb) 93209920Snwhitehorn{ 94209920Snwhitehorn struct inode *ip; 95209920Snwhitehorn struct m_ext2fs *fs; 96209920Snwhitehorn struct ext4_extent *ep; 97209920Snwhitehorn struct ext4_extent_path path; 98209920Snwhitehorn daddr_t lbn; 99209920Snwhitehorn 100209920Snwhitehorn ip = VTOI(vp); 101209920Snwhitehorn fs = ip->i_e2fs; 102 lbn = bn; 103 104 /* 105 * TODO: need to implement read ahead to improve the performance. 106 */ 107 if (runp != NULL) 108 *runp = 0; 109 110 if (runb != NULL) 111 *runb = 0; 112 113 ext4_ext_find_extent(fs, ip, lbn, &path); 114 ep = path.ep_ext; 115 if (ep == NULL) 116 return (EIO); 117 118 *bnp = fsbtodb(fs, lbn - ep->e_blk + 119 (ep->e_start_lo | (daddr_t)ep->e_start_hi << 32)); 120 121 if (*bnp == 0) 122 *bnp = -1; 123 124 return (0); 125} 126 127/* 128 * Indirect blocks are now on the vnode for the file. They are given negative 129 * logical block numbers. Indirect blocks are addressed by the negative 130 * address of the first data block to which they point. Double indirect blocks 131 * are addressed by one less than the address of the first indirect block to 132 * which they point. Triple indirect blocks are addressed by one less than 133 * the address of the first double indirect block to which they point. 134 * 135 * ext2_bmaparray does the bmap conversion, and if requested returns the 136 * array of logical blocks which must be traversed to get to a block. 137 * Each entry contains the offset into that block that gets you to the 138 * next block and the disk address of the block (if it is assigned). 139 */ 140 141int 142ext2_bmaparray(struct vnode *vp, daddr_t bn, daddr_t *bnp, int *runp, int *runb) 143{ 144 struct inode *ip; 145 struct buf *bp; 146 struct ext2mount *ump; 147 struct mount *mp; 148 struct vnode *devvp; 149 struct indir a[NIADDR+1], *ap; 150 daddr_t daddr; 151 e2fs_lbn_t metalbn; 152 int error, num, maxrun = 0, bsize; 153 int *nump; 154 155 ap = NULL; 156 ip = VTOI(vp); 157 mp = vp->v_mount; 158 ump = VFSTOEXT2(mp); 159 devvp = ump->um_devvp; 160 161 bsize = EXT2_BLOCK_SIZE(ump->um_e2fs); 162 163 if (runp) { 164 maxrun = mp->mnt_iosize_max / bsize - 1; 165 *runp = 0; 166 } 167 168 if (runb) { 169 *runb = 0; 170 } 171 172 173 ap = a; 174 nump = # 175 error = ext2_getlbns(vp, bn, ap, nump); 176 if (error) 177 return (error); 178 179 num = *nump; 180 if (num == 0) { 181 *bnp = blkptrtodb(ump, ip->i_db[bn]); 182 if (*bnp == 0) { 183 *bnp = -1; 184 } else if (runp) { 185 daddr_t bnb = bn; 186 for (++bn; bn < NDADDR && *runp < maxrun && 187 is_sequential(ump, ip->i_db[bn - 1], ip->i_db[bn]); 188 ++bn, ++*runp); 189 bn = bnb; 190 if (runb && (bn > 0)) { 191 for (--bn; (bn >= 0) && (*runb < maxrun) && 192 is_sequential(ump, ip->i_db[bn], 193 ip->i_db[bn + 1]); 194 --bn, ++*runb); 195 } 196 } 197 return (0); 198 } 199 200 201 /* Get disk address out of indirect block array */ 202 daddr = ip->i_ib[ap->in_off]; 203 204 for (bp = NULL, ++ap; --num; ++ap) { 205 /* 206 * Exit the loop if there is no disk address assigned yet and 207 * the indirect block isn't in the cache, or if we were 208 * looking for an indirect block and we've found it. 209 */ 210 211 metalbn = ap->in_lbn; 212 if ((daddr == 0 && !incore(&vp->v_bufobj, metalbn)) || metalbn == bn) 213 break; 214 /* 215 * If we get here, we've either got the block in the cache 216 * or we have a disk address for it, go fetch it. 217 */ 218 if (bp) 219 bqrelse(bp); 220 221 bp = getblk(vp, metalbn, bsize, 0, 0, 0); 222 if ((bp->b_flags & B_CACHE) == 0) { 223#ifdef INVARIANTS 224 if (!daddr) 225 panic("ext2_bmaparray: indirect block not in cache"); 226#endif 227 bp->b_blkno = blkptrtodb(ump, daddr); 228 bp->b_iocmd = BIO_READ; 229 bp->b_flags &= ~B_INVAL; 230 bp->b_ioflags &= ~BIO_ERROR; 231 vfs_busy_pages(bp, 0); 232 bp->b_iooffset = dbtob(bp->b_blkno); 233 bstrategy(bp); 234 curthread->td_ru.ru_inblock++; 235 error = bufwait(bp); 236 if (error) { 237 brelse(bp); 238 return (error); 239 } 240 } 241 242 daddr = ((e2fs_daddr_t *)bp->b_data)[ap->in_off]; 243 if (num == 1 && daddr && runp) { 244 for (bn = ap->in_off + 1; 245 bn < MNINDIR(ump) && *runp < maxrun && 246 is_sequential(ump, 247 ((e2fs_daddr_t *)bp->b_data)[bn - 1], 248 ((e2fs_daddr_t *)bp->b_data)[bn]); 249 ++bn, ++*runp); 250 bn = ap->in_off; 251 if (runb && bn) { 252 for (--bn; bn >= 0 && *runb < maxrun && 253 is_sequential(ump, 254 ((e2fs_daddr_t *)bp->b_data)[bn], 255 ((e2fs_daddr_t *)bp->b_data)[bn + 1]); 256 --bn, ++*runb); 257 } 258 } 259 } 260 if (bp) 261 bqrelse(bp); 262 263 /* 264 * Since this is FFS independent code, we are out of scope for the 265 * definitions of BLK_NOCOPY and BLK_SNAP, but we do know that they 266 * will fall in the range 1..um_seqinc, so we use that test and 267 * return a request for a zeroed out buffer if attempts are made 268 * to read a BLK_NOCOPY or BLK_SNAP block. 269 */ 270 if ((ip->i_flags & SF_SNAPSHOT) && daddr > 0 && daddr < ump->um_seqinc){ 271 *bnp = -1; 272 return (0); 273 } 274 *bnp = blkptrtodb(ump, daddr); 275 if (*bnp == 0) { 276 *bnp = -1; 277 } 278 return (0); 279} 280 281/* 282 * Create an array of logical block number/offset pairs which represent the 283 * path of indirect blocks required to access a data block. The first "pair" 284 * contains the logical block number of the appropriate single, double or 285 * triple indirect block and the offset into the inode indirect block array. 286 * Note, the logical block number of the inode single/double/triple indirect 287 * block appears twice in the array, once with the offset into the i_ib and 288 * once with the offset into the page itself. 289 */ 290int 291ext2_getlbns(struct vnode *vp, daddr_t bn, struct indir *ap, int *nump) 292{ 293 long blockcnt; 294 e2fs_lbn_t metalbn, realbn; 295 struct ext2mount *ump; 296 int i, numlevels, off; 297 int64_t qblockcnt; 298 299 ump = VFSTOEXT2(vp->v_mount); 300 if (nump) 301 *nump = 0; 302 numlevels = 0; 303 realbn = bn; 304 if ((long)bn < 0) 305 bn = -(long)bn; 306 307 /* The first NDADDR blocks are direct blocks. */ 308 if (bn < NDADDR) 309 return (0); 310 311 /* 312 * Determine the number of levels of indirection. After this loop 313 * is done, blockcnt indicates the number of data blocks possible 314 * at the previous level of indirection, and NIADDR - i is the number 315 * of levels of indirection needed to locate the requested block. 316 */ 317 for (blockcnt = 1, i = NIADDR, bn -= NDADDR;; i--, bn -= blockcnt) { 318 if (i == 0) 319 return (EFBIG); 320 /* 321 * Use int64_t's here to avoid overflow for triple indirect 322 * blocks when longs have 32 bits and the block size is more 323 * than 4K. 324 */ 325 qblockcnt = (int64_t)blockcnt * MNINDIR(ump); 326 if (bn < qblockcnt) 327 break; 328 blockcnt = qblockcnt; 329 } 330 331 /* Calculate the address of the first meta-block. */ 332 if (realbn >= 0) 333 metalbn = -(realbn - bn + NIADDR - i); 334 else 335 metalbn = -(-realbn - bn + NIADDR - i); 336 337 /* 338 * At each iteration, off is the offset into the bap array which is 339 * an array of disk addresses at the current level of indirection. 340 * The logical block number and the offset in that block are stored 341 * into the argument array. 342 */ 343 ap->in_lbn = metalbn; 344 ap->in_off = off = NIADDR - i; 345 ap++; 346 for (++numlevels; i <= NIADDR; i++) { 347 /* If searching for a meta-data block, quit when found. */ 348 if (metalbn == realbn) 349 break; 350 351 off = (bn / blockcnt) % MNINDIR(ump); 352 353 ++numlevels; 354 ap->in_lbn = metalbn; 355 ap->in_off = off; 356 ++ap; 357 358 metalbn -= -1 + off * blockcnt; 359 blockcnt /= MNINDIR(ump); 360 } 361 if (nump) 362 *nump = numlevels; 363 return (0); 364} 365