fsys_zfs.c

xen虚拟机源代码安装包

/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 1999,2000,2001,2002,2003,2004  Free Software Foundation, Inc.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * All files in the zfs directory are derived from the OpenSolaris
 * zfs grub files.  All files in the zfs-include directory were
 * included without changes.
 */

/*
 * The zfs plug-in routines for GRUB are:
 *
 * zfs_mount() - locates a valid uberblock of the root pool and reads
 *		in its MOS at the memory address MOS.
 *
 * zfs_open() - locates a plain file object by following the MOS
 *		and places its dnode at the memory address DNODE.
 *
 * zfs_read() - read in the data blocks pointed by the DNODE.
 *
 * ZFS_SCRATCH is used as a working area.
 *
 * (memory addr)   MOS      DNODE	ZFS_SCRATCH
 *		    |         |          |
 *	    +-------V---------V----------V---------------+
 *   memory |       | dnode   | dnode    |  scratch      |
 *	    |       | 512B    | 512B     |  area         |
 *	    +--------------------------------------------+
 */

#include <stdio.h>
#include <strings.h>

/* From "shared.h" */
#include "mb_info.h"

/* Boot signature related defines for the findroot command */
#define	BOOTSIGN_DIR	"/boot/grub/bootsign"
#define	BOOTSIGN_BACKUP	"/etc/bootsign"

/* Maybe redirect memory requests through grub_scratch_mem. */
#define	RAW_ADDR(x) (x)
#define	RAW_SEG(x) (x)

/* ZFS will use the top 4 Meg of physical memory (below 4Gig) for sratch */
#define	ZFS_SCRATCH_SIZE 0x400000

#define	MIN(x, y) ((x) < (y) ? (x) : (y))
/* End from shared.h */

#include "fsys_zfs.h"

/* cache for a file block of the currently zfs_open()-ed file */
#define	file_buf zfs_ba->zfs_file_buf
#define	file_start zfs_ba->zfs_file_start
#define	file_end zfs_ba->zfs_file_end

/* cache for a dnode block */
#define	dnode_buf zfs_ba->zfs_dnode_buf
#define	dnode_mdn zfs_ba->zfs_dnode_mdn
#define	dnode_start zfs_ba->zfs_dnode_start
#define	dnode_end zfs_ba->zfs_dnode_end

#define	stackbase zfs_ba->zfs_stackbase

decomp_entry_t decomp_table[ZIO_COMPRESS_FUNCTIONS] =
{
	{"noop", 0},
	{"on", lzjb_decompress}, 	/* ZIO_COMPRESS_ON */
	{"off", 0},
	{"lzjb", lzjb_decompress}	/* ZIO_COMPRESS_LZJB */
};

/* From disk_io.c */
/* ZFS root filesystem for booting */
#define	current_bootpath zfs_ba->zfs_current_bootpath
#define	current_rootpool zfs_ba->zfs_current_rootpool
#define	current_bootfs zfs_ba->zfs_current_bootfs
#define	current_bootfs_obj zfs_ba->zfs_current_bootfs_obj
#define	is_zfs_mount (*fsig_int1(ffi))
/* End from disk_io.c */

#define	is_zfs_open zfs_ba->zfs_open

/*
 * Our own version of bcmp().
 */
static int
zfs_bcmp(const void *s1, const void *s2, size_t n)
{
	const unsigned char *ps1 = s1;
	const unsigned char *ps2 = s2;

	if (s1 != s2 && n != 0) {
		do {
			if (*ps1++ != *ps2++)
				return (1);
		} while (--n != 0);
	}

	return (0);
}

/*
 * Our own version of log2().  Same thing as highbit()-1.
 */
static int
zfs_log2(uint64_t num)
{
	int i = 0;

	while (num > 1) {
		i++;
		num = num >> 1;
	}

	return (i);
}

/* Checksum Functions */
static void
zio_checksum_off(const void *buf, uint64_t size, zio_cksum_t *zcp)
{
	ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
}

/* Checksum Table and Values */
zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
	{{NULL,			NULL},			0, 0,	"inherit"},
	{{NULL,			NULL},			0, 0,	"on"},
	{{zio_checksum_off,	zio_checksum_off},	0, 0,	"off"},
	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 1,	"label"},
	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 1,	"gang_header"},
	{{fletcher_2_native,	fletcher_2_byteswap},	0, 1,	"zilog"},
	{{fletcher_2_native,	fletcher_2_byteswap},	0, 0,	"fletcher2"},
	{{fletcher_4_native,	fletcher_4_byteswap},	1, 0,	"fletcher4"},
	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 0,	"SHA256"}
};

/*
 * zio_checksum_verify: Provides support for checksum verification.
 *
 * Fletcher2, Fletcher4, and SHA256 are supported.
 *
 * Return:
 * 	-1 = Failure
 *	 0 = Success
 */
static int
zio_checksum_verify(blkptr_t *bp, char *data, int size)
{
	zio_cksum_t zc = bp->blk_cksum;
	uint32_t checksum = BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER :
	    BP_GET_CHECKSUM(bp);
	int byteswap = BP_SHOULD_BYTESWAP(bp);
	zio_block_tail_t *zbt = (zio_block_tail_t *)(data + size) - 1;
	zio_checksum_info_t *ci = &zio_checksum_table[checksum];
	zio_cksum_t actual_cksum, expected_cksum;

	/* byteswap is not supported */
	if (byteswap)
		return (-1);

	if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
		return (-1);

	if (ci->ci_zbt) {
		if (checksum == ZIO_CHECKSUM_GANG_HEADER) {
			/*
			 * 'gang blocks' is not supported.
			 */
			return (-1);
		}

		if (zbt->zbt_magic == BSWAP_64(ZBT_MAGIC)) {
			/* byte swapping is not supported */
			return (-1);
		} else {
			expected_cksum = zbt->zbt_cksum;
			zbt->zbt_cksum = zc;
			ci->ci_func[0](data, size, &actual_cksum);
			zbt->zbt_cksum = expected_cksum;
		}
		zc = expected_cksum;

	} else {
		if (BP_IS_GANG(bp))
			return (-1);
		ci->ci_func[byteswap](data, size, &actual_cksum);
	}

	if ((actual_cksum.zc_word[0] - zc.zc_word[0]) |
	    (actual_cksum.zc_word[1] - zc.zc_word[1]) |
	    (actual_cksum.zc_word[2] - zc.zc_word[2]) |
	    (actual_cksum.zc_word[3] - zc.zc_word[3]))
		return (-1);

	return (0);
}

/*
 * vdev_label_offset takes "offset" (the offset within a vdev_label) and
 * returns its physical disk offset (starting from the beginning of the vdev).
 *
 * Input:
 *	psize	: Physical size of this vdev
 *      l	: Label Number (0-3)
 *	offset	: The offset with a vdev_label in which we want the physical
 *		  address
 * Return:
 * 	Success : physical disk offset
 * 	Failure : errnum = ERR_BAD_ARGUMENT, return value is meaningless
 */
static uint64_t
vdev_label_offset(fsi_file_t *ffi, uint64_t psize, int l, uint64_t offset)
{
	/* XXX Need to add back label support! */
	if (l >= VDEV_LABELS/2 || offset > sizeof (vdev_label_t)) {
		errnum = ERR_BAD_ARGUMENT;
		return (0);
	}

	return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ?
	    0 : psize - VDEV_LABELS * sizeof (vdev_label_t)));

}

/*
 * vdev_uberblock_compare takes two uberblock structures and returns an integer
 * indicating the more recent of the two.
 * 	Return Value = 1 if ub2 is more recent
 * 	Return Value = -1 if ub1 is more recent
 * The most recent uberblock is determined using its transaction number and
 * timestamp.  The uberblock with the highest transaction number is
 * considered "newer".  If the transaction numbers of the two blocks match, the
 * timestamps are compared to determine the "newer" of the two.
 */
static int
vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
{
	if (ub1->ub_txg < ub2->ub_txg)
		return (-1);
	if (ub1->ub_txg > ub2->ub_txg)
		return (1);

	if (ub1->ub_timestamp < ub2->ub_timestamp)
		return (-1);
	if (ub1->ub_timestamp > ub2->ub_timestamp)
		return (1);

	return (0);
}

/*
 * Three pieces of information are needed to verify an uberblock: the magic
 * number, the version number, and the checksum.
 *
 * Currently Implemented: version number, magic number
 * Need to Implement: checksum
 *
 * Return:
 *     0 - Success
 *    -1 - Failure
 */
static int
uberblock_verify(uberblock_phys_t *ub, int offset)
{

	uberblock_t *uber = &ub->ubp_uberblock;
	blkptr_t bp;

	BP_ZERO(&bp);
	BP_SET_CHECKSUM(&bp, ZIO_CHECKSUM_LABEL);
	BP_SET_BYTEORDER(&bp, ZFS_HOST_BYTEORDER);
	ZIO_SET_CHECKSUM(&bp.blk_cksum, offset, 0, 0, 0);

	if (zio_checksum_verify(&bp, (char *)ub, UBERBLOCK_SIZE) != 0)
		return (-1);

	if (uber->ub_magic == UBERBLOCK_MAGIC &&
	    uber->ub_version >= SPA_VERSION_1 &&
	    uber->ub_version <= SPA_VERSION)
		return (0);

	return (-1);
}

/*
 * Find the best uberblock.
 * Return:
 *    Success - Pointer to the best uberblock.
 *    Failure - NULL
 */
static uberblock_phys_t *
find_bestub(fsi_file_t *ffi, uberblock_phys_t *ub_array, int label)
{
	uberblock_phys_t *ubbest = NULL;
	int i, offset;

	for (i = 0; i < (VDEV_UBERBLOCK_RING >> VDEV_UBERBLOCK_SHIFT); i++) {
		offset = vdev_label_offset(ffi, 0, label,
		    VDEV_UBERBLOCK_OFFSET(i));
		if (errnum == ERR_BAD_ARGUMENT)
			return (NULL);
		if (uberblock_verify(&ub_array[i], offset) == 0) {
			if (ubbest == NULL) {
				ubbest = &ub_array[i];
			} else if (vdev_uberblock_compare(
			    &(ub_array[i].ubp_uberblock),
			    &(ubbest->ubp_uberblock)) > 0) {
				ubbest = &ub_array[i];
			}
		}
	}

	return (ubbest);
}

/*
 * Read in a block and put its uncompressed data in buf.
 *
 * Return:
 *	0 - success
 *	errnum - failure
 */
static int
zio_read(fsi_file_t *ffi, blkptr_t *bp, void *buf, char *stack)
{
	uint64_t offset, sector;
	int psize, lsize;
	int i, comp, cksum;

	psize = BP_GET_PSIZE(bp);
	lsize = BP_GET_LSIZE(bp);
	comp = BP_GET_COMPRESS(bp);
	cksum = BP_GET_CHECKSUM(bp);

	if ((unsigned int)comp >= ZIO_COMPRESS_FUNCTIONS ||
	    (comp != ZIO_COMPRESS_OFF &&
	    decomp_table[comp].decomp_func == NULL))
		return (ERR_FSYS_CORRUPT);

	/* pick a good dva from the block pointer */
	for (i = 0; i < SPA_DVAS_PER_BP; i++) {

		if (bp->blk_dva[i].dva_word[0] == 0 &&
		    bp->blk_dva[i].dva_word[1] == 0)
			continue;

		/* read in a block */
		offset = DVA_GET_OFFSET(&bp->blk_dva[i]);
		sector =  DVA_OFFSET_TO_PHYS_SECTOR(offset);

		if (comp != ZIO_COMPRESS_OFF) {

			if (devread(ffi, sector, 0, psize, stack) == 0)
				continue;
			if (zio_checksum_verify(bp, stack, psize) != 0)
				continue;
			decomp_table[comp].decomp_func(stack, buf, psize,
			    lsize);
		} else {
			if (devread(ffi, sector, 0, psize, buf) == 0)
				continue;
			if (zio_checksum_verify(bp, buf, psize) != 0)
				continue;
		}
		return (0);
	}

	return (ERR_FSYS_CORRUPT);
}

/*
 * Get the block from a block id.
 * push the block onto the stack.
 *
 * Return:
 * 	0 - success
 * 	errnum - failure
 */
static int
dmu_read(fsi_file_t *ffi, dnode_phys_t *dn, uint64_t blkid, void *buf,
    char *stack)
{
	int idx, level;
	blkptr_t *bp_array = dn->dn_blkptr;
	int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
	blkptr_t *bp, *tmpbuf;

	bp = (blkptr_t *)stack;
	stack += sizeof (blkptr_t);

	tmpbuf = (blkptr_t *)stack;
	stack += 1<<dn->dn_indblkshift;

	for (level = dn->dn_nlevels - 1; level >= 0; level--) {
		idx = (blkid >> (epbs * level)) & ((1<<epbs)-1);
		*bp = bp_array[idx];
		if (level == 0)
			tmpbuf = buf;
		if (BP_IS_HOLE(bp)) {
			grub_memset(buf, 0,
			    dn->dn_datablkszsec << SPA_MINBLOCKSHIFT);
			break;
		} else if ((errnum = zio_read(ffi, bp, tmpbuf, stack))) {
			return (errnum);
		}
		bp_array = tmpbuf;
	}

	return (0);
}

/*
 * mzap_lookup: Looks up property described by "name" and returns the value
 * in "value".
 *
 * Return:
 *	0 - success
 *	errnum - failure
 */
static int
mzap_lookup(mzap_phys_t *zapobj, int objsize, char *name,
	uint64_t *value)
{
	int i, chunks;
	mzap_ent_phys_t *mzap_ent = zapobj->mz_chunk;

	chunks = objsize/MZAP_ENT_LEN - 1;
	for (i = 0; i < chunks; i++) {
		if (strcmp(mzap_ent[i].mze_name, name) == 0) {
			*value = mzap_ent[i].mze_value;
			return (0);
		}
	}

	return (ERR_FSYS_CORRUPT);
}

static uint64_t
zap_hash(fsi_file_t *ffi, uint64_t salt, const char *name)
{
	static uint64_t table[256];
	const uint8_t *cp;
	uint8_t c;
	uint64_t crc = salt;

	if (table[128] == 0) {
		uint64_t *ct;
		int i, j;
		for (i = 0; i < 256; i++) {
			for (ct = table + i, *ct = i, j = 8; j > 0; j--)
				*ct = (*ct >> 1) ^ (-(*ct & 1) &
				    ZFS_CRC64_POLY);
		}
	}

	if (crc == 0 || table[128] != ZFS_CRC64_POLY) {
		errnum = ERR_FSYS_CORRUPT;
		return (0);
	}

	for (cp = (const uint8_t *)name; (c = *cp) != '\0'; cp++)
		crc = (crc >> 8) ^ table[(crc ^ c) & 0xFF];