e8a28f87d8
Long ago, bread() set b_blkno to the disk block number as a side effect of doing physical i/o (or it just retained the setting from when the i/o was done). The setting is lost when buffers go away and then are reconsituted from VM. bread() originally compensated by doing a VOP_BMAP() to recover b_blkno, but this was no good since it sometimes caused extra i/o or even deadlock for bread()ing metadata to do the bmap. This was fixed in vfs_bio.c 1.33 (1995/03/03) and ffs_balloc.c 1.5, etc., by removing the VOP_BMAP() from bread() and breadn(), and changing all (?) places that used b_blkno to set it if necessary. ext2fs was not imported until later in 1995 and was still depending on the old behaviour of bread() in at least ext2_balloc(). This caused filesystem and file corruption by clobbering direct block numbers in inodes.
318 lines
8.7 KiB
C
318 lines
8.7 KiB
C
/*
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* modified for Lites 1.1
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*
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* Aug 1995, Godmar Back (gback@cs.utah.edu)
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* University of Utah, Department of Computer Science
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*/
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/*
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* Copyright (c) 1982, 1986, 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)ffs_balloc.c 8.4 (Berkeley) 9/23/93
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bio.h>
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#include <sys/buf.h>
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#include <sys/lock.h>
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#include <sys/ucred.h>
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#include <sys/vnode.h>
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#include <ufs/ufs/quota.h>
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#include <ufs/ufs/inode.h>
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#include <ufs/ufs/ufs_extern.h>
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#include <gnu/ext2fs/ext2_fs.h>
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#include <gnu/ext2fs/ext2_fs_sb.h>
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#include <gnu/ext2fs/fs.h>
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#include <gnu/ext2fs/ext2_extern.h>
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/*
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* Balloc defines the structure of file system storage
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* by allocating the physical blocks on a device given
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* the inode and the logical block number in a file.
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*/
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int
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ext2_balloc(ip, bn, size, cred, bpp, flags)
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register struct inode *ip;
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register daddr_t bn;
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int size;
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struct ucred *cred;
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struct buf **bpp;
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int flags;
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{
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register struct ext2_sb_info *fs;
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register daddr_t nb;
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struct buf *bp, *nbp;
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struct vnode *vp = ITOV(ip);
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struct indir indirs[NIADDR + 2];
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daddr_t newb, lbn, *bap, pref;
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int osize, nsize, num, i, error;
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/*
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ext2_debug("ext2_balloc called (%d, %d, %d)\n",
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ip->i_number, (int)bn, (int)size);
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*/
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*bpp = NULL;
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if (bn < 0)
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return (EFBIG);
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fs = ip->i_e2fs;
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lbn = bn;
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/*
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* check if this is a sequential block allocation.
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* If so, increment next_alloc fields to allow ext2_blkpref
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* to make a good guess
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*/
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if (lbn == ip->i_next_alloc_block + 1) {
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ip->i_next_alloc_block++;
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ip->i_next_alloc_goal++;
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}
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/*
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* The first NDADDR blocks are direct blocks
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*/
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if (bn < NDADDR) {
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nb = ip->i_db[bn];
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/* no new block is to be allocated, and no need to expand
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the file */
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if (nb != 0 && ip->i_size >= (bn + 1) * fs->s_blocksize) {
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error = bread(vp, bn, fs->s_blocksize, NOCRED, &bp);
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if (error) {
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brelse(bp);
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return (error);
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}
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bp->b_blkno = fsbtodb(fs, nb);
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*bpp = bp;
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return (0);
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}
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if (nb != 0) {
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/*
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* Consider need to reallocate a fragment.
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*/
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osize = fragroundup(fs, blkoff(fs, ip->i_size));
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nsize = fragroundup(fs, size);
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if (nsize <= osize) {
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error = bread(vp, bn, osize, NOCRED, &bp);
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if (error) {
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brelse(bp);
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return (error);
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}
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bp->b_blkno = fsbtodb(fs, nb);
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} else {
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/* Godmar thinks: this shouldn't happen w/o fragments */
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printf("nsize %d(%d) > osize %d(%d) nb %d\n",
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(int)nsize, (int)size, (int)osize,
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(int)ip->i_size, (int)nb);
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panic(
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"ext2_balloc: Something is terribly wrong");
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/*
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* please note there haven't been any changes from here on -
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* FFS seems to work.
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*/
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}
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} else {
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if (ip->i_size < (bn + 1) * fs->s_blocksize)
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nsize = fragroundup(fs, size);
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else
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nsize = fs->s_blocksize;
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error = ext2_alloc(ip, bn,
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ext2_blkpref(ip, bn, (int)bn, &ip->i_db[0], 0),
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nsize, cred, &newb);
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if (error)
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return (error);
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bp = getblk(vp, bn, nsize, 0, 0);
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bp->b_blkno = fsbtodb(fs, newb);
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if (flags & B_CLRBUF)
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vfs_bio_clrbuf(bp);
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}
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ip->i_db[bn] = dbtofsb(fs, bp->b_blkno);
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ip->i_flag |= IN_CHANGE | IN_UPDATE;
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*bpp = bp;
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return (0);
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}
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/*
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* Determine the number of levels of indirection.
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*/
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pref = 0;
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if ((error = ufs_getlbns(vp, bn, indirs, &num)) != 0)
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return(error);
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#if DIAGNOSTIC
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if (num < 1)
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panic ("ext2_balloc: ufs_bmaparray returned indirect block");
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#endif
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/*
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* Fetch the first indirect block allocating if necessary.
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*/
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--num;
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nb = ip->i_ib[indirs[0].in_off];
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if (nb == 0) {
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#if 0
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pref = ext2_blkpref(ip, lbn, 0, (daddr_t *)0, 0);
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#else
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/* see the comment by ext2_blkpref. What we do here is
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to pretend that it'd be good for a block holding indirect
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pointers to be allocated near its predecessor in terms
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of indirection, or the last direct block.
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We shamelessly exploit the fact that i_ib immediately
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follows i_db.
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Godmar thinks it make sense to allocate i_ib[0] immediately
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after i_db[11], but it's not utterly clear whether this also
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applies to i_ib[1] and i_ib[0]
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*/
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pref = ext2_blkpref(ip, lbn, indirs[0].in_off +
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EXT2_NDIR_BLOCKS, &ip->i_db[0], 0);
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#endif
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if ((error = ext2_alloc(ip, lbn, pref, (int)fs->s_blocksize,
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cred, &newb)) != 0)
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return (error);
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nb = newb;
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bp = getblk(vp, indirs[1].in_lbn, fs->s_blocksize, 0, 0);
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bp->b_blkno = fsbtodb(fs, newb);
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vfs_bio_clrbuf(bp);
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/*
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* Write synchronously so that indirect blocks
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* never point at garbage.
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*/
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if ((error = bwrite(bp)) != 0) {
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ext2_blkfree(ip, nb, fs->s_blocksize);
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return (error);
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}
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ip->i_ib[indirs[0].in_off] = newb;
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ip->i_flag |= IN_CHANGE | IN_UPDATE;
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}
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/*
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* Fetch through the indirect blocks, allocating as necessary.
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*/
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for (i = 1;;) {
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error = bread(vp,
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indirs[i].in_lbn, (int)fs->s_blocksize, NOCRED, &bp);
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if (error) {
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brelse(bp);
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return (error);
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}
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bap = (daddr_t *)bp->b_data;
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nb = bap[indirs[i].in_off];
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if (i == num)
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break;
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i += 1;
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if (nb != 0) {
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brelse(bp);
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continue;
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}
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if (pref == 0)
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#if 1
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/* see the comment above and by ext2_blkpref
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* I think this implements Linux policy, but
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* does it really make sense to allocate to
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* block containing pointers together ?
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* Also, will it ever succeed ?
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*/
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pref = ext2_blkpref(ip, lbn, indirs[i].in_off, bap,
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bp->b_lblkno);
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#else
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pref = ext2_blkpref(ip, lbn, 0, (daddr_t *)0, 0);
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#endif
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if ((error =
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ext2_alloc(ip, lbn, pref, (int)fs->s_blocksize, cred, &newb)) != 0) {
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brelse(bp);
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return (error);
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}
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nb = newb;
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nbp = getblk(vp, indirs[i].in_lbn, fs->s_blocksize, 0, 0);
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nbp->b_blkno = fsbtodb(fs, nb);
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vfs_bio_clrbuf(nbp);
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/*
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* Write synchronously so that indirect blocks
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* never point at garbage.
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*/
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if ((error = bwrite(nbp)) != 0) {
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ext2_blkfree(ip, nb, fs->s_blocksize);
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brelse(bp);
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return (error);
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}
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bap[indirs[i - 1].in_off] = nb;
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/*
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* If required, write synchronously, otherwise use
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* delayed write.
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*/
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if (flags & B_SYNC) {
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bwrite(bp);
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} else {
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bdwrite(bp);
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}
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}
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/*
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* Get the data block, allocating if necessary.
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*/
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if (nb == 0) {
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pref = ext2_blkpref(ip, lbn, indirs[i].in_off, &bap[0],
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bp->b_lblkno);
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if ((error = ext2_alloc(ip,
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lbn, pref, (int)fs->s_blocksize, cred, &newb)) != 0) {
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brelse(bp);
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return (error);
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}
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nb = newb;
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nbp = getblk(vp, lbn, fs->s_blocksize, 0, 0);
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nbp->b_blkno = fsbtodb(fs, nb);
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if (flags & B_CLRBUF)
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vfs_bio_clrbuf(nbp);
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bap[indirs[i].in_off] = nb;
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/*
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* If required, write synchronously, otherwise use
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* delayed write.
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*/
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if (flags & B_SYNC) {
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bwrite(bp);
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} else {
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bdwrite(bp);
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}
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*bpp = nbp;
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return (0);
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}
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brelse(bp);
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if (flags & B_CLRBUF) {
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error = bread(vp, lbn, (int)fs->s_blocksize, NOCRED, &nbp);
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if (error) {
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brelse(nbp);
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return (error);
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}
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} else {
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nbp = getblk(vp, lbn, fs->s_blocksize, 0, 0);
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nbp->b_blkno = fsbtodb(fs, nb);
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}
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*bpp = nbp;
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return (0);
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}
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