xref: /dflybsd-src/sys/vfs/ext2fs/ext2_bmap.c (revision fb08533b96dcdf4157f83e82dfab1313b49013d3)

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1989, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)ufs_bmap.c	8.7 (Berkeley) 3/21/95
 * $FreeBSD$
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/endian.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/resourcevar.h>
#include <sys/stat.h>

#include <vfs/ext2fs/fs.h>
#include <vfs/ext2fs/inode.h>
#include <vfs/ext2fs/ext2fs.h>
#include <vfs/ext2fs/ext2_dinode.h>
#include <vfs/ext2fs/ext2_extern.h>
#include <vfs/ext2fs/ext2_mount.h>

/*
 * Bmap converts the logical block number of a file to its physical block
 * number on the disk. The conversion is done by using the logical block
 * number to index into the array of block pointers described by the dinode.
 *
 * BMAP must return the contiguous before and after run in bytes, inclusive
 * of the returned block.
 */
int
ext2_bmap(struct vop_bmap_args *ap)
{
	struct m_ext2fs *fs;
	daddr_t lbn, dbn;
	int error;

	/*
	 * Check for underlying vnode requests and ensure that logical
	 * to physical mapping is requested.
	 */
	if (ap->a_doffsetp == NULL)
		return (0);

	fs = VTOI(ap->a_vp)->i_e2fs;
	KKASSERT(((int)ap->a_loffset & ((1 << fs->e2fs_bshift) - 1)) == 0);
	lbn = ap->a_loffset >> fs->e2fs_bshift;

	if (VTOI(ap->a_vp)->i_flag & IN_E4EXTENTS)
		error = ext4_bmapext(ap->a_vp, lbn, &dbn, ap->a_runp,
		    ap->a_runb);
	else
		error = ext2_bmaparray(ap->a_vp, lbn, &dbn, ap->a_runp,
		    ap->a_runb);

	if (error || dbn == (daddr_t)-1) {
		*ap->a_doffsetp = NOOFFSET;
	} else {
		*ap->a_doffsetp = dbtodoff(fs, dbn);
		if (ap->a_runp)
			*ap->a_runp = (*ap->a_runp + 1) << fs->e2fs_bshift;
		if (ap->a_runb)
			*ap->a_runb = *ap->a_runb << fs->e2fs_bshift;
	}
	return (error);
}

/*
 * Convert the logical block number of a file to its physical block number
 * on the disk within ext4 extents.
 */
int
ext4_bmapext(struct vnode *vp, int32_t bn, daddr_t/*int64_t*/ *bnp, int *runp, int *runb)
{
	return (EINVAL);
}

static int
readindir(struct vnode *vp, e2fs_lbn_t lbn, e2fs_daddr_t daddr, struct buf **bpp)
{
	struct buf *bp;
	struct mount *mp;
	struct ext2mount *ump;
	struct m_ext2fs *fs;
	int error;

	mp = vp->v_mount;
	ump = VFSTOEXT2(mp);
	fs = VTOI(vp)->i_e2fs;

	bp = getblk(vp, lblktodoff(fs, lbn), mp->mnt_stat.f_iosize, 0, 0);
	if ((bp->b_flags & B_CACHE) == 0) {
		KASSERT(daddr != 0,
		    ("readindir: indirect block not in cache"));
		/*
		 * This runs through ext2_strategy using bio2 to
		 * cache the disk offset, then comes back through
		 * bio1.  So we want to wait on bio1.
		 */
		bp->b_bio1.bio_done = biodone_sync;
		bp->b_bio1.bio_flags |= BIO_SYNC;
		bp->b_bio2.bio_offset = fsbtodoff(fs, daddr);
		bp->b_flags &= ~(B_INVAL | B_ERROR);
		bp->b_cmd = BUF_CMD_READ;
		vfs_busy_pages(bp->b_vp, bp);
		vn_strategy(bp->b_vp, &bp->b_bio1);
#ifdef RACCT
		if (racct_enable) {
			PROC_LOCK(curproc);
			racct_add_buf(curproc, bp, 0);
			PROC_UNLOCK(curproc);
		}
#endif
		error = biowait(&bp->b_bio1, "biord");
		if (error) {
			brelse(bp);
			return (error);
		}
	}
	*bpp = bp;
	return (0);
}

/*
 * Indirect blocks are now on the vnode for the file.  They are given negative
 * logical block numbers.  Indirect blocks are addressed by the negative
 * address of the first data block to which they point.  Double indirect blocks
 * are addressed by one less than the address of the first indirect block to
 * which they point.  Triple indirect blocks are addressed by one less than
 * the address of the first double indirect block to which they point.
 *
 * ext2_bmaparray does the bmap conversion, and if requested returns the
 * array of logical blocks which must be traversed to get to a block.
 * Each entry contains the offset into that block that gets you to the
 * next block and the disk address of the block (if it is assigned).
 */

int
ext2_bmaparray(struct vnode *vp, daddr_t bn, daddr_t *bnp, int *runp, int *runb)
{
	struct inode *ip;
	struct buf *bp;
	struct ext2mount *ump;
	struct mount *mp;
	struct m_ext2fs *fs;
	struct indir a[EXT2_NIADDR + 1], *ap;
	daddr_t daddr;
	e2fs_lbn_t metalbn;
	int error, num, maxrun = 0, bsize;
	int *nump;

	ap = NULL;
	ip = VTOI(vp);
	mp = vp->v_mount;
	ump = VFSTOEXT2(mp);
	fs = ip->i_e2fs;

	bsize = EXT2_BLOCK_SIZE(ump->um_e2fs);

	if (runp) {
		maxrun = mp->mnt_iosize_max / bsize - 1;
		*runp = 0;
	}
	if (runb)
		*runb = 0;

	ap = a;
	nump = &num;
	error = ext2_getlbns(vp, bn, ap, nump);
	if (error)
		return (error);

	num = *nump;
	if (num == 0) {
		*bnp = blkptrtodb(ump, ip->i_db[bn]);
		if (*bnp == 0) {
			*bnp = -1;
		} else if (runp) {
			daddr_t bnb = bn;

			for (++bn; bn < EXT2_NDADDR && *runp < maxrun &&
			    is_sequential(ump, ip->i_db[bn - 1], ip->i_db[bn]);
			    ++bn, ++*runp);
			bn = bnb;
			if (runb && (bn > 0)) {
				for (--bn; (bn >= 0) && (*runb < maxrun) &&
					is_sequential(ump, ip->i_db[bn],
						ip->i_db[bn + 1]);
						--bn, ++*runb);
			}
		}
		return (0);
	}

	/* Get disk address out of indirect block array */
	daddr = ip->i_ib[ap->in_off];

	for (bp = NULL, ++ap; --num; ++ap) {
		/*
		 * Exit the loop if there is no disk address assigned yet and
		 * the indirect block isn't in the cache, or if we were
		 * looking for an indirect block and we've found it.
		 */

		metalbn = ap->in_lbn;
		if ((daddr == 0 &&
		    !findblk(vp, dbtodoff(fs, metalbn), FINDBLK_TEST)) ||
		    metalbn == bn)
			break;
		/*
		 * If we get here, we've either got the block in the cache
		 * or we have a disk address for it, go fetch it.
		 */
		if (bp)
			bqrelse(bp);
		error = readindir(vp, metalbn, daddr, &bp);
		if (error != 0)
			return (error);

		daddr = le32toh(((e2fs_daddr_t *)bp->b_data)[ap->in_off]);
		if (num == 1 && daddr && runp) {
			for (bn = ap->in_off + 1;
			    bn < MNINDIR(ump) && *runp < maxrun &&
			    is_sequential(ump,
			    ((e2fs_daddr_t *)bp->b_data)[bn - 1],
			    ((e2fs_daddr_t *)bp->b_data)[bn]);
			    ++bn, ++*runp);
			bn = ap->in_off;
			if (runb && bn) {
				for (--bn; bn >= 0 && *runb < maxrun &&
					is_sequential(ump,
					((e2fs_daddr_t *)bp->b_data)[bn],
					((e2fs_daddr_t *)bp->b_data)[bn + 1]);
					--bn, ++*runb);
			}
		}
	}
	if (bp)
		bqrelse(bp);

	*bnp = blkptrtodb(ump, daddr);
	if (*bnp == 0) {
		*bnp = -1;
	}
	return (0);
}

/*
 * Create an array of logical block number/offset pairs which represent the
 * path of indirect blocks required to access a data block.  The first "pair"
 * contains the logical block number of the appropriate single, double or
 * triple indirect block and the offset into the inode indirect block array.
 * Note, the logical block number of the inode single/double/triple indirect
 * block appears twice in the array, once with the offset into the i_ib and
 * once with the offset into the page itself.
 */
int
ext2_getlbns(struct vnode *vp, daddr_t bn, struct indir *ap, int *nump)
{
	long blockcnt;
	e2fs_lbn_t metalbn, realbn;
	struct ext2mount *ump;
	int i, numlevels, off;
	int64_t qblockcnt;

	ump = VFSTOEXT2(vp->v_mount);
	if (nump)
		*nump = 0;
	numlevels = 0;
	realbn = bn;
	if ((long)bn < 0)
		bn = -(long)bn;

	/* The first EXT2_NDADDR blocks are direct blocks. */
	if (bn < EXT2_NDADDR)
		return (0);

	/*
	 * Determine the number of levels of indirection.  After this loop
	 * is done, blockcnt indicates the number of data blocks possible
	 * at the previous level of indirection, and EXT2_NIADDR - i is the
	 * number of levels of indirection needed to locate the requested block.
	 */
	for (blockcnt = 1, i = EXT2_NIADDR, bn -= EXT2_NDADDR; ;
	    i--, bn -= blockcnt) {
		if (i == 0)
			return (EFBIG);
		/*
		 * Use int64_t's here to avoid overflow for triple indirect
		 * blocks when longs have 32 bits and the block size is more
		 * than 4K.
		 */
		qblockcnt = (int64_t)blockcnt * MNINDIR(ump);
		if (bn < qblockcnt)
			break;
		blockcnt = qblockcnt;
	}

	/* Calculate the address of the first meta-block. */
	if (realbn >= 0)
		metalbn = -(realbn - bn + EXT2_NIADDR - i);
	else
		metalbn = -(-realbn - bn + EXT2_NIADDR - i);

	/*
	 * At each iteration, off is the offset into the bap array which is
	 * an array of disk addresses at the current level of indirection.
	 * The logical block number and the offset in that block are stored
	 * into the argument array.
	 */
	ap->in_lbn = metalbn;
	ap->in_off = off = EXT2_NIADDR - i;
	ap++;
	for (++numlevels; i <= EXT2_NIADDR; i++) {
		/* If searching for a meta-data block, quit when found. */
		if (metalbn == realbn)
			break;

		off = (bn / blockcnt) % MNINDIR(ump);

		++numlevels;
		ap->in_lbn = metalbn;
		ap->in_off = off;
		++ap;

		metalbn -= -1 + off * blockcnt;
		blockcnt /= MNINDIR(ump);
	}
	if (nump)
		*nump = numlevels;
	return (0);
}