Initial Spring 2016 commit.
This commit is contained in:
Geoffrey Challen
310
userland/sbin/sfsck/freemap.c
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310
userland/sbin/sfsck/freemap.c
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/*
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* Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2009, 2013, 2014
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* The President and Fellows of Harvard College.
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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. 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 UNIVERSITY 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 UNIVERSITY 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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#include <sys/types.h> /* for CHAR_BIT */
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#include <limits.h> /* also for CHAR_BIT */
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#include <stdint.h>
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#include <stdio.h>
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#include <assert.h>
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#include <err.h>
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#include "compat.h"
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#include <kern/sfs.h>
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#include "utils.h"
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#include "sfs.h"
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#include "sb.h"
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#include "freemap.h"
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#include "main.h"
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static unsigned long blocksinuse = 0;
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static uint8_t *freemapdata;
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static uint8_t *tofreedata;
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/*
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* Allocate space to keep track of the free block bitmap. This is
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* called after the superblock is loaded so we can ask how big the
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* volume is.
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*/
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void
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freemap_setup(void)
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{
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size_t i, mapbytes;
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uint32_t fsblocks, mapblocks;
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fsblocks = sb_totalblocks();
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mapblocks = sb_freemapblocks();
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mapbytes = mapblocks * SFS_BLOCKSIZE;
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freemapdata = domalloc(mapbytes * sizeof(uint8_t));
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tofreedata = domalloc(mapbytes * sizeof(uint8_t));
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for (i=0; i<mapbytes; i++) {
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freemapdata[i] = tofreedata[i] = 0;
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}
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/* Mark off what's in the freemap but past the volume end. */
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for (i=fsblocks; i < mapblocks*SFS_BITSPERBLOCK; i++) {
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freemap_blockinuse(i, B_PASTEND, 0);
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}
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/* Mark the superblock block and the freemap blocks in use */
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freemap_blockinuse(SFS_SUPER_BLOCK, B_SUPERBLOCK, 0);
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for (i=0; i < mapblocks; i++) {
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freemap_blockinuse(SFS_FREEMAP_START+i, B_FREEMAPBLOCK, i);
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}
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}
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/*
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* Return a string for a blockusage; used for printing errors.
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*/
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static
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const char *
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blockusagestr(blockusage_t how, uint32_t howdesc)
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{
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static char rv[256];
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switch (how) {
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case B_SUPERBLOCK:
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return "superblock";
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case B_FREEMAPBLOCK:
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snprintf(rv, sizeof(rv), "freemap block %lu",
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(unsigned long) howdesc);
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break;
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case B_INODE:
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snprintf(rv, sizeof(rv), "inode %lu",
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(unsigned long) howdesc);
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break;
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case B_IBLOCK:
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snprintf(rv, sizeof(rv), "indirect block of inode %lu",
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(unsigned long) howdesc);
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break;
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case B_DIRDATA:
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snprintf(rv, sizeof(rv), "directory data from inode %lu",
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(unsigned long) howdesc);
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break;
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case B_DATA:
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snprintf(rv, sizeof(rv), "file data from inode %lu",
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(unsigned long) howdesc);
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break;
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case B_PASTEND:
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return "past the end of the fs";
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}
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return rv;
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}
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/*
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* Mark block BLOCK in use. HOW and HOWDESC describe how it was found
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* to be in use, so we can print a useful message if it's wrong.
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*
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* FUTURE: this should not produce unrecoverable errors.
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*/
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void
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freemap_blockinuse(uint32_t block, blockusage_t how, uint32_t howdesc)
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{
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unsigned index = block/8;
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uint8_t mask = ((uint8_t)1)<<(block%8);
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if (tofreedata[index] & mask) {
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/* really using the block, don't free it */
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tofreedata[index] &= ~mask;
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}
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if (freemapdata[index] & mask) {
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warnx("Block %lu (used as %s) already in use! (NOT FIXED)",
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(unsigned long) block, blockusagestr(how, howdesc));
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setbadness(EXIT_UNRECOV);
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}
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freemapdata[index] |= mask;
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if (how != B_PASTEND) {
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blocksinuse++;
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}
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}
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/*
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* Mark a block free. This is specifically for blocks that we are
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* freeing, that might be marked allocated in the on-disk freemap. If
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* the block has been found in use, assume the reference that's in use
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* is valid. This can be caused by freeing a block, reallocating it
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* somewhere else and then dying without erasing all of the original
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* usage on disk; most such cases will just show the block in use
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* twice, which is (not) handled above, but it's possible for the
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* original usage to be something we are dropping, e.g. if a truncate
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* (to a nonzero length > INOMAX_D) got partially completed.
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*/
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void
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freemap_blockfree(uint32_t block)
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{
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unsigned index = block/8;
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uint8_t mask = ((uint8_t)1)<<(block%8);
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if (tofreedata[index] & mask) {
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/* already marked to free once, ignore */
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return;
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}
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if (freemapdata[index] & mask) {
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/* block is used elsewhere, ignore */
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return;
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}
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tofreedata[index] |= mask;
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}
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/*
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* Count the number of bits set.
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*/
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static
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int
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countbits(uint8_t val)
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{
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uint8_t x;
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int ct=0;
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for (x=1; x; x<<=1) {
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if (val & x) ct++;
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}
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return ct;
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}
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/*
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* Print a complaint about freemap bits being wrong.
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*
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* FREEMAPBLOCK is the block number within the freemap; BYTE is the
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* byte offset within that block; VAL is the byte value; WHAT is a
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* string indicating what happened.
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*/
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static
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void
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reportfreemap(uint32_t mapblock, uint32_t byte, uint8_t val, const char *what)
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{
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uint8_t x, y;
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uint32_t blocknum;
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for (x=1, y=0; x; x<<=1, y++) {
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if (val & x) {
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blocknum = mapblock*SFS_BITSPERBLOCK +
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byte*CHAR_BIT + y;
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warnx("Block %lu erroneously shown %s in freemap",
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(unsigned long) blocknum, what);
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}
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}
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}
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/*
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* Scan the freemap.
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*
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* This is called after (at the end of) pass 1, when we've recursively
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* found all the reachable blocks and marked them.
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*/
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void
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freemap_check(void)
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{
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uint8_t actual[SFS_BLOCKSIZE], *expected, *tofree, tmp;
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uint32_t alloccount=0, freecount=0, i, j;
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int bchanged;
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uint32_t bitblocks;
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bitblocks = sb_freemapblocks();
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for (i=0; i<bitblocks; i++) {
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sfs_readfreemapblock(i, actual);
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expected = freemapdata + i*SFS_BLOCKSIZE;
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tofree = tofreedata + i*SFS_BLOCKSIZE;
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bchanged = 0;
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for (j=0; j<SFS_BLOCKSIZE; j++) {
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/* we shouldn't have blocks marked both ways */
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assert((expected[j] & tofree[j])==0);
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/* what's there is what should be there */
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if (actual[j] == expected[j]) {
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continue;
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}
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/* what's there is what should be there modulo frees */
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if (actual[j] == (expected[j] | tofree[j])) {
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actual[j] = expected[j];
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bchanged = 1;
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continue;
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}
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/* oops, it doesn't match... */
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/* free the ones we're freeing (don't report these) */
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actual[j] &= ~tofree[j];
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/* are we short any? */
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if ((actual[j] & expected[j]) != expected[j]) {
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tmp = expected[j] & ~actual[j];
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alloccount += countbits(tmp);
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if (tmp != 0) {
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reportfreemap(i, j, tmp, "free");
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}
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}
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/* do we have any extra? */
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if ((actual[j] & expected[j]) != actual[j]) {
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tmp = actual[j] & ~expected[j];
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freecount += countbits(tmp);
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if (tmp != 0) {
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reportfreemap(i, j, tmp, "allocated");
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}
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}
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/* set it to what it should be */
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actual[j] = expected[j];
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bchanged = 1;
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}
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/* write the block back if necessary */
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if (bchanged) {
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sfs_writefreemapblock(i, actual);
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}
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}
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if (alloccount > 0) {
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warnx("%lu blocks erroneously shown free in freemap (fixed)",
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(unsigned long) alloccount);
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setbadness(EXIT_RECOV);
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}
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if (freecount > 0) {
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warnx("%lu blocks erroneously shown used in freemap (fixed)",
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(unsigned long) freecount);
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setbadness(EXIT_RECOV);
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}
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}
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/*
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* Return the total number of blocks in use, which we count during
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* pass 1.
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*/
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unsigned long
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freemap_blocksused(void)
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{
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return blocksinuse;
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}
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