Annotation of sys/ufs/ufs/ufs_bmap.c, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: ufs_bmap.c,v 1.25 2007/06/01 23:47:57 deraadt Exp $ */
! 2: /* $NetBSD: ufs_bmap.c,v 1.3 1996/02/09 22:36:00 christos Exp $ */
! 3:
! 4: /*
! 5: * Copyright (c) 1989, 1991, 1993
! 6: * The Regents of the University of California. All rights reserved.
! 7: * (c) UNIX System Laboratories, Inc.
! 8: * All or some portions of this file are derived from material licensed
! 9: * to the University of California by American Telephone and Telegraph
! 10: * Co. or Unix System Laboratories, Inc. and are reproduced herein with
! 11: * the permission of UNIX System Laboratories, Inc.
! 12: *
! 13: * Redistribution and use in source and binary forms, with or without
! 14: * modification, are permitted provided that the following conditions
! 15: * are met:
! 16: * 1. Redistributions of source code must retain the above copyright
! 17: * notice, this list of conditions and the following disclaimer.
! 18: * 2. Redistributions in binary form must reproduce the above copyright
! 19: * notice, this list of conditions and the following disclaimer in the
! 20: * documentation and/or other materials provided with the distribution.
! 21: * 3. Neither the name of the University nor the names of its contributors
! 22: * may be used to endorse or promote products derived from this software
! 23: * without specific prior written permission.
! 24: *
! 25: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 26: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 27: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 28: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 29: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 30: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 31: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 32: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 33: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 34: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 35: * SUCH DAMAGE.
! 36: *
! 37: * @(#)ufs_bmap.c 8.6 (Berkeley) 1/21/94
! 38: */
! 39:
! 40: #include <sys/param.h>
! 41: #include <sys/systm.h>
! 42: #include <sys/buf.h>
! 43: #include <sys/proc.h>
! 44: #include <sys/vnode.h>
! 45: #include <sys/mount.h>
! 46: #include <sys/resourcevar.h>
! 47:
! 48: #include <miscfs/specfs/specdev.h>
! 49:
! 50: #include <ufs/ufs/quota.h>
! 51: #include <ufs/ufs/inode.h>
! 52: #include <ufs/ufs/ufsmount.h>
! 53: #include <ufs/ufs/ufs_extern.h>
! 54:
! 55: /*
! 56: * Bmap converts a the logical block number of a file to its physical block
! 57: * number on the disk. The conversion is done by using the logical block
! 58: * number to index into the array of block pointers described by the dinode.
! 59: */
! 60: int
! 61: ufs_bmap(void *v)
! 62: {
! 63: struct vop_bmap_args *ap = v;
! 64:
! 65: /*
! 66: * Check for underlying vnode requests and ensure that logical
! 67: * to physical mapping is requested.
! 68: */
! 69: if (ap->a_vpp != NULL)
! 70: *ap->a_vpp = VTOI(ap->a_vp)->i_devvp;
! 71: if (ap->a_bnp == NULL)
! 72: return (0);
! 73:
! 74: return (ufs_bmaparray(ap->a_vp, ap->a_bn, ap->a_bnp, NULL, NULL,
! 75: ap->a_runp));
! 76: }
! 77:
! 78: /*
! 79: * Indirect blocks are now on the vnode for the file. They are given negative
! 80: * logical block numbers. Indirect blocks are addressed by the negative
! 81: * address of the first data block to which they point. Double indirect blocks
! 82: * are addressed by one less than the address of the first indirect block to
! 83: * which they point. Triple indirect blocks are addressed by one less than
! 84: * the address of the first double indirect block to which they point.
! 85: *
! 86: * ufs_bmaparray does the bmap conversion, and if requested returns the
! 87: * array of logical blocks which must be traversed to get to a block.
! 88: * Each entry contains the offset into that block that gets you to the
! 89: * next block and the disk address of the block (if it is assigned).
! 90: */
! 91: int
! 92: ufs_bmaparray(struct vnode *vp, daddr_t bn, daddr64_t *bnp, struct indir *ap,
! 93: int *nump, int *runp)
! 94: {
! 95: struct inode *ip;
! 96: struct buf *bp;
! 97: struct ufsmount *ump;
! 98: struct mount *mp;
! 99: struct vnode *devvp;
! 100: struct indir a[NIADDR+1], *xap;
! 101: daddr64_t daddr;
! 102: long metalbn;
! 103: int error, maxrun = 0, num;
! 104:
! 105: ip = VTOI(vp);
! 106: mp = vp->v_mount;
! 107: ump = VFSTOUFS(mp);
! 108: #ifdef DIAGNOSTIC
! 109: if ((ap != NULL && nump == NULL) || (ap == NULL && nump != NULL))
! 110: panic("ufs_bmaparray: invalid arguments");
! 111: #endif
! 112:
! 113: if (runp) {
! 114: /*
! 115: * XXX
! 116: * If MAXBSIZE is the largest transfer the disks can handle,
! 117: * we probably want maxrun to be 1 block less so that we
! 118: * don't create a block larger than the device can handle.
! 119: */
! 120: *runp = 0;
! 121: maxrun = MAXBSIZE / mp->mnt_stat.f_iosize - 1;
! 122: }
! 123:
! 124: xap = ap == NULL ? a : ap;
! 125: if (!nump)
! 126: nump = #
! 127: if ((error = ufs_getlbns(vp, bn, xap, nump)) != 0)
! 128: return (error);
! 129:
! 130: num = *nump;
! 131: if (num == 0) {
! 132: *bnp = blkptrtodb(ump, DIP(ip, db[bn]));
! 133: if (*bnp == 0)
! 134: *bnp = -1;
! 135: else if (runp)
! 136: for (++bn; bn < NDADDR && *runp < maxrun &&
! 137: is_sequential(ump, DIP(ip, db[bn - 1]),
! 138: DIP(ip, db[bn]));
! 139: ++bn, ++*runp);
! 140: return (0);
! 141: }
! 142:
! 143:
! 144: /* Get disk address out of indirect block array */
! 145: daddr = DIP(ip, ib[xap->in_off]);
! 146:
! 147: devvp = VFSTOUFS(vp->v_mount)->um_devvp;
! 148: for (bp = NULL, ++xap; --num; ++xap) {
! 149: /*
! 150: * Exit the loop if there is no disk address assigned yet and
! 151: * the indirect block isn't in the cache, or if we were
! 152: * looking for an indirect block and we've found it.
! 153: */
! 154:
! 155: metalbn = xap->in_lbn;
! 156: if ((daddr == 0 && !incore(vp, metalbn)) || metalbn == bn)
! 157: break;
! 158: /*
! 159: * If we get here, we've either got the block in the cache
! 160: * or we have a disk address for it, go fetch it.
! 161: */
! 162: if (bp)
! 163: brelse(bp);
! 164:
! 165: xap->in_exists = 1;
! 166: bp = getblk(vp, metalbn, mp->mnt_stat.f_iosize, 0, 0);
! 167: if (bp->b_flags & (B_DONE | B_DELWRI)) {
! 168: ;
! 169: }
! 170: #ifdef DIAGNOSTIC
! 171: else if (!daddr)
! 172: panic("ufs_bmaparray: indirect block not in cache");
! 173: #endif
! 174: else {
! 175: bp->b_blkno = blkptrtodb(ump, daddr);
! 176: bp->b_flags |= B_READ;
! 177: VOP_STRATEGY(bp);
! 178: curproc->p_stats->p_ru.ru_inblock++; /* XXX */
! 179: if ((error = biowait(bp)) != 0) {
! 180: brelse(bp);
! 181: return (error);
! 182: }
! 183: }
! 184:
! 185: #ifdef FFS2
! 186: if (ip->i_ump->um_fstype == UM_UFS2) {
! 187: daddr = ((daddr64_t *)bp->b_data)[xap->in_off];
! 188: if (num == 1 && daddr && runp)
! 189: for (bn = xap->in_off + 1;
! 190: bn < MNINDIR(ump) && *runp < maxrun &&
! 191: is_sequential(ump,
! 192: ((daddr64_t *)bp->b_data)[bn - 1],
! 193: ((daddr64_t *)bp->b_data)[bn]);
! 194: ++bn, ++*runp);
! 195:
! 196: continue;
! 197: }
! 198:
! 199: #endif /* FFS2 */
! 200:
! 201: daddr = ((daddr_t *)bp->b_data)[xap->in_off];
! 202: if (num == 1 && daddr && runp)
! 203: for (bn = xap->in_off + 1;
! 204: bn < MNINDIR(ump) && *runp < maxrun &&
! 205: is_sequential(ump,
! 206: ((daddr_t *)bp->b_data)[bn - 1],
! 207: ((daddr_t *)bp->b_data)[bn]);
! 208: ++bn, ++*runp);
! 209: }
! 210: if (bp)
! 211: brelse(bp);
! 212:
! 213: daddr = blkptrtodb(ump, daddr);
! 214: *bnp = daddr == 0 ? -1 : daddr;
! 215: return (0);
! 216: }
! 217:
! 218: /*
! 219: * Create an array of logical block number/offset pairs which represent the
! 220: * path of indirect blocks required to access a data block. The first "pair"
! 221: * contains the logical block number of the appropriate single, double or
! 222: * triple indirect block and the offset into the inode indirect block array.
! 223: * Note, the logical block number of the inode single/double/triple indirect
! 224: * block appears twice in the array, once with the offset into the i_ffs_ib and
! 225: * once with the offset into the page itself.
! 226: */
! 227: int
! 228: ufs_getlbns(struct vnode *vp, daddr_t bn, struct indir *ap, int *nump)
! 229: {
! 230: long metalbn, realbn;
! 231: struct ufsmount *ump;
! 232: int64_t blockcnt;
! 233: int i, numlevels, off;
! 234:
! 235: ump = VFSTOUFS(vp->v_mount);
! 236: if (nump)
! 237: *nump = 0;
! 238: numlevels = 0;
! 239: realbn = bn;
! 240: if ((long)bn < 0)
! 241: bn = -(long)bn;
! 242:
! 243: #ifdef DIAGNOSTIC
! 244: if (realbn < 0 && realbn > -NDADDR) {
! 245: panic ("ufs_getlbns: Invalid indirect block %d specified",
! 246: realbn);
! 247: }
! 248: #endif
! 249:
! 250: /* The first NDADDR blocks are direct blocks. */
! 251: if (bn < NDADDR)
! 252: return (0);
! 253:
! 254: /*
! 255: * Determine the number of levels of indirection. After this loop
! 256: * is done, blockcnt indicates the number of data blocks possible
! 257: * at the given level of indirection, and NIADDR - i is the number
! 258: * of levels of indirection needed to locate the requested block.
! 259: */
! 260: for (blockcnt = 1, i = NIADDR, bn -= NDADDR;; i--, bn -= blockcnt) {
! 261: if (i == 0)
! 262: return (EFBIG);
! 263: blockcnt *= MNINDIR(ump);
! 264: if (bn < blockcnt)
! 265: break;
! 266: }
! 267:
! 268: /* Calculate the address of the first meta-block. */
! 269: if (realbn >= 0)
! 270: metalbn = -(realbn - bn + NIADDR - i);
! 271: else
! 272: metalbn = -(-realbn - bn + NIADDR - i);
! 273:
! 274: /*
! 275: * At each iteration, off is the offset into the bap array which is
! 276: * an array of disk addresses at the current level of indirection.
! 277: * The logical block number and the offset in that block are stored
! 278: * into the argument array.
! 279: */
! 280: ap->in_lbn = metalbn;
! 281: ap->in_off = off = NIADDR - i;
! 282: ap->in_exists = 0;
! 283: ap++;
! 284: for (++numlevels; i <= NIADDR; i++) {
! 285: /* If searching for a meta-data block, quit when found. */
! 286: if (metalbn == realbn)
! 287: break;
! 288:
! 289: blockcnt /= MNINDIR(ump);
! 290: off = (bn / blockcnt) % MNINDIR(ump);
! 291:
! 292: ++numlevels;
! 293: ap->in_lbn = metalbn;
! 294: ap->in_off = off;
! 295: ap->in_exists = 0;
! 296: ++ap;
! 297:
! 298: metalbn -= -1 + off * blockcnt;
! 299: }
! 300: #ifdef DIAGNOSTIC
! 301: if (realbn < 0 && metalbn != realbn) {
! 302: panic("ufs_getlbns: indirect block %d not found", realbn);
! 303: }
! 304: #endif
! 305: if (nump)
! 306: *nump = numlevels;
! 307: return (0);
! 308: }
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