super.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 2,070 行 · 第 1/5 页

#else /* NTFS_RW */
	/*
	 * For the read-write compiled driver, if we are remounting read-write,
	 * make sure there are no volume errors and that no unsupported volume
	 * flags are set.  Also, empty the logfile journal as it would become
	 * stale as soon as something is written to the volume and mark the
	 * volume dirty so that chkdsk is run if the volume is not umounted
	 * cleanly.  Finally, mark the quotas out of date so Windows rescans
	 * the volume on boot and updates them.
	 *
	 * When remounting read-only, mark the volume clean if no volume errors
	 * have occured.
	 */
	if ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
		static const char *es = ".  Cannot remount read-write.";

		/* Remounting read-write. */
		if (NVolErrors(vol)) {
			ntfs_error(sb, "Volume has errors and is read-only%s",
					es);
			return -EROFS;
		}
		if (vol->vol_flags & VOLUME_IS_DIRTY) {
			ntfs_error(sb, "Volume is dirty and read-only%s", es);
			return -EROFS;
		}
		if (vol->vol_flags & VOLUME_MUST_MOUNT_RO_MASK) {
			ntfs_error(sb, "Volume has unsupported flags set and "
					"is read-only%s", es);
			return -EROFS;
		}
		if (ntfs_set_volume_flags(vol, VOLUME_IS_DIRTY)) {
			ntfs_error(sb, "Failed to set dirty bit in volume "
					"information flags%s", es);
			return -EROFS;
		}
#if 0
		// TODO: Enable this code once we start modifying anything that
		//	 is different between NTFS 1.2 and 3.x...
		/* Set NT4 compatibility flag on newer NTFS version volumes. */
		if ((vol->major_ver > 1)) {
			if (ntfs_set_volume_flags(vol, VOLUME_MOUNTED_ON_NT4)) {
				ntfs_error(sb, "Failed to set NT4 "
						"compatibility flag%s", es);
				NVolSetErrors(vol);
				return -EROFS;
			}
		}
#endif
		if (!ntfs_empty_logfile(vol->logfile_ino)) {
			ntfs_error(sb, "Failed to empty journal $LogFile%s",
					es);
			NVolSetErrors(vol);
			return -EROFS;
		}
		if (!ntfs_mark_quotas_out_of_date(vol)) {
			ntfs_error(sb, "Failed to mark quotas out of date%s",
					es);
			NVolSetErrors(vol);
			return -EROFS;
		}
	} else if (!(sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY)) {
		/* Remounting read-only. */
		if (!NVolErrors(vol)) {
			if (ntfs_clear_volume_flags(vol, VOLUME_IS_DIRTY))
				ntfs_warning(sb, "Failed to clear dirty bit "
						"in volume information "
						"flags.  Run chkdsk.");
		}
	}
#endif /* NTFS_RW */

	// TODO: Deal with *flags.

	if (!parse_options(vol, opt))
		return -EINVAL;
	ntfs_debug("Done.");
	return 0;
}

/**
 * is_boot_sector_ntfs - check whether a boot sector is a valid NTFS boot sector
 * @sb:		Super block of the device to which @b belongs.
 * @b:		Boot sector of device @sb to check.
 * @silent:	If TRUE, all output will be silenced.
 *
 * is_boot_sector_ntfs() checks whether the boot sector @b is a valid NTFS boot
 * sector. Returns TRUE if it is valid and FALSE if not.
 *
 * @sb is only needed for warning/error output, i.e. it can be NULL when silent
 * is TRUE.
 */
static BOOL is_boot_sector_ntfs(const struct super_block *sb,
		const NTFS_BOOT_SECTOR *b, const BOOL silent)
{
	/*
	 * Check that checksum == sum of u32 values from b to the checksum
	 * field. If checksum is zero, no checking is done.
	 */
	if ((void*)b < (void*)&b->checksum && b->checksum) {
		le32 *u;
		u32 i;

		for (i = 0, u = (le32*)b; u < (le32*)(&b->checksum); ++u)
			i += le32_to_cpup(u);
		if (le32_to_cpu(b->checksum) != i)
			goto not_ntfs;
	}
	/* Check OEMidentifier is "NTFS    " */
	if (b->oem_id != magicNTFS)
		goto not_ntfs;
	/* Check bytes per sector value is between 256 and 4096. */
	if (le16_to_cpu(b->bpb.bytes_per_sector) < 0x100 ||
			le16_to_cpu(b->bpb.bytes_per_sector) > 0x1000)
		goto not_ntfs;
	/* Check sectors per cluster value is valid. */
	switch (b->bpb.sectors_per_cluster) {
	case 1: case 2: case 4: case 8: case 16: case 32: case 64: case 128:
		break;
	default:
		goto not_ntfs;
	}
	/* Check the cluster size is not above 65536 bytes. */
	if ((u32)le16_to_cpu(b->bpb.bytes_per_sector) *
			b->bpb.sectors_per_cluster > 0x10000)
		goto not_ntfs;
	/* Check reserved/unused fields are really zero. */
	if (le16_to_cpu(b->bpb.reserved_sectors) ||
			le16_to_cpu(b->bpb.root_entries) ||
			le16_to_cpu(b->bpb.sectors) ||
			le16_to_cpu(b->bpb.sectors_per_fat) ||
			le32_to_cpu(b->bpb.large_sectors) || b->bpb.fats)
		goto not_ntfs;
	/* Check clusters per file mft record value is valid. */
	if ((u8)b->clusters_per_mft_record < 0xe1 ||
			(u8)b->clusters_per_mft_record > 0xf7)
		switch (b->clusters_per_mft_record) {
		case 1: case 2: case 4: case 8: case 16: case 32: case 64:
			break;
		default:
			goto not_ntfs;
		}
	/* Check clusters per index block value is valid. */
	if ((u8)b->clusters_per_index_record < 0xe1 ||
			(u8)b->clusters_per_index_record > 0xf7)
		switch (b->clusters_per_index_record) {
		case 1: case 2: case 4: case 8: case 16: case 32: case 64:
			break;
		default:
			goto not_ntfs;
		}
	/*
	 * Check for valid end of sector marker. We will work without it, but
	 * many BIOSes will refuse to boot from a bootsector if the magic is
	 * incorrect, so we emit a warning.
	 */
	if (!silent && b->end_of_sector_marker != cpu_to_le16(0xaa55))
		ntfs_warning(sb, "Invalid end of sector marker.");
	return TRUE;
not_ntfs:
	return FALSE;
}

/**
 * read_ntfs_boot_sector - read the NTFS boot sector of a device
 * @sb:		super block of device to read the boot sector from
 * @silent:	if true, suppress all output
 *
 * Reads the boot sector from the device and validates it. If that fails, tries
 * to read the backup boot sector, first from the end of the device a-la NT4 and
 * later and then from the middle of the device a-la NT3.51 and before.
 *
 * If a valid boot sector is found but it is not the primary boot sector, we
 * repair the primary boot sector silently (unless the device is read-only or
 * the primary boot sector is not accessible).
 *
 * NOTE: To call this function, @sb must have the fields s_dev, the ntfs super
 * block (u.ntfs_sb), nr_blocks and the device flags (s_flags) initialized
 * to their respective values.
 *
 * Return the unlocked buffer head containing the boot sector or NULL on error.
 */
static struct buffer_head *read_ntfs_boot_sector(struct super_block *sb,
		const int silent)
{
	const char *read_err_str = "Unable to read %s boot sector.";
	struct buffer_head *bh_primary, *bh_backup;
	long nr_blocks = NTFS_SB(sb)->nr_blocks;

	/* Try to read primary boot sector. */
	if ((bh_primary = sb_bread(sb, 0))) {
		if (is_boot_sector_ntfs(sb, (NTFS_BOOT_SECTOR*)
				bh_primary->b_data, silent))
			return bh_primary;
		if (!silent)
			ntfs_error(sb, "Primary boot sector is invalid.");
	} else if (!silent)
		ntfs_error(sb, read_err_str, "primary");
	if (!(NTFS_SB(sb)->on_errors & ON_ERRORS_RECOVER)) {
		if (bh_primary)
			brelse(bh_primary);
		if (!silent)
			ntfs_error(sb, "Mount option errors=recover not used. "
					"Aborting without trying to recover.");
		return NULL;
	}
	/* Try to read NT4+ backup boot sector. */
	if ((bh_backup = sb_bread(sb, nr_blocks - 1))) {
		if (is_boot_sector_ntfs(sb, (NTFS_BOOT_SECTOR*)
				bh_backup->b_data, silent))
			goto hotfix_primary_boot_sector;
		brelse(bh_backup);
	} else if (!silent)
		ntfs_error(sb, read_err_str, "backup");
	/* Try to read NT3.51- backup boot sector. */
	if ((bh_backup = sb_bread(sb, nr_blocks >> 1))) {
		if (is_boot_sector_ntfs(sb, (NTFS_BOOT_SECTOR*)
				bh_backup->b_data, silent))
			goto hotfix_primary_boot_sector;
		if (!silent)
			ntfs_error(sb, "Could not find a valid backup boot "
					"sector.");
		brelse(bh_backup);
	} else if (!silent)
		ntfs_error(sb, read_err_str, "backup");
	/* We failed. Cleanup and return. */
	if (bh_primary)
		brelse(bh_primary);
	return NULL;
hotfix_primary_boot_sector:
	if (bh_primary) {
		/*
		 * If we managed to read sector zero and the volume is not
		 * read-only, copy the found, valid backup boot sector to the
		 * primary boot sector.
		 */
		if (!(sb->s_flags & MS_RDONLY)) {
			ntfs_warning(sb, "Hot-fix: Recovering invalid primary "
					"boot sector from backup copy.");
			memcpy(bh_primary->b_data, bh_backup->b_data,
					sb->s_blocksize);
			mark_buffer_dirty(bh_primary);
			sync_dirty_buffer(bh_primary);
			if (buffer_uptodate(bh_primary)) {
				brelse(bh_backup);
				return bh_primary;
			}
			ntfs_error(sb, "Hot-fix: Device write error while "
					"recovering primary boot sector.");
		} else {
			ntfs_warning(sb, "Hot-fix: Recovery of primary boot "
					"sector failed: Read-only mount.");
		}
		brelse(bh_primary);
	}
	ntfs_warning(sb, "Using backup boot sector.");
	return bh_backup;
}

/**
 * parse_ntfs_boot_sector - parse the boot sector and store the data in @vol
 * @vol:	volume structure to initialise with data from boot sector
 * @b:		boot sector to parse
 *
 * Parse the ntfs boot sector @b and store all imporant information therein in
 * the ntfs super block @vol. Return TRUE on success and FALSE on error.
 */
static BOOL parse_ntfs_boot_sector(ntfs_volume *vol, const NTFS_BOOT_SECTOR *b)
{
	unsigned int sectors_per_cluster_bits, nr_hidden_sects;
	int clusters_per_mft_record, clusters_per_index_record;
	s64 ll;

	vol->sector_size = le16_to_cpu(b->bpb.bytes_per_sector);
	vol->sector_size_bits = ffs(vol->sector_size) - 1;
	ntfs_debug("vol->sector_size = %i (0x%x)", vol->sector_size,
			vol->sector_size);
	ntfs_debug("vol->sector_size_bits = %i (0x%x)", vol->sector_size_bits,
			vol->sector_size_bits);
	if (vol->sector_size != vol->sb->s_blocksize)
		ntfs_warning(vol->sb, "The boot sector indicates a sector size "
				"different from the device sector size.");
	ntfs_debug("sectors_per_cluster = 0x%x", b->bpb.sectors_per_cluster);
	sectors_per_cluster_bits = ffs(b->bpb.sectors_per_cluster) - 1;
	ntfs_debug("sectors_per_cluster_bits = 0x%x",
			sectors_per_cluster_bits);
	nr_hidden_sects = le32_to_cpu(b->bpb.hidden_sectors);
	ntfs_debug("number of hidden sectors = 0x%x", nr_hidden_sects);
	vol->cluster_size = vol->sector_size << sectors_per_cluster_bits;
	vol->cluster_size_mask = vol->cluster_size - 1;
	vol->cluster_size_bits = ffs(vol->cluster_size) - 1;
	ntfs_debug("vol->cluster_size = %i (0x%x)", vol->cluster_size,
			vol->cluster_size);
	ntfs_debug("vol->cluster_size_mask = 0x%x", vol->cluster_size_mask);
	ntfs_debug("vol->cluster_size_bits = %i (0x%x)",
			vol->cluster_size_bits, vol->cluster_size_bits);
	if (vol->sector_size > vol->cluster_size) {
		ntfs_error(vol->sb, "Sector sizes above the cluster size are "
				"not supported. Sorry.");
		return FALSE;
	}
	if (vol->sb->s_blocksize > vol->cluster_size) {
		ntfs_error(vol->sb, "Cluster sizes smaller than the device "
				"sector size are not supported. Sorry.");
		return FALSE;
	}
	clusters_per_mft_record = b->clusters_per_mft_record;
	ntfs_debug("clusters_per_mft_record = %i (0x%x)",
			clusters_per_mft_record, clusters_per_mft_record);
	if (clusters_per_mft_record > 0)
		vol->mft_record_size = vol->cluster_size <<
				(ffs(clusters_per_mft_record) - 1);
	else
		/*
		 * When mft_record_size < cluster_size, clusters_per_mft_record
		 * = -log2(mft_record_size) bytes. mft_record_size normaly is
		 * 1024 bytes, which is encoded as 0xF6 (-10 in decimal).
		 */
		vol->mft_record_size = 1 << -clusters_per_mft_record;
	vol->mft_record_size_mask = vol->mft_record_size - 1;
	vol->mft_record_size_bits = ffs(vol->mft_record_size) - 1;
	ntfs_debug("vol->mft_record_size = %i (0x%x)", vol->mft_record_size,
			vol->mft_record_size);
	ntfs_debug("vol->mft_record_size_mask = 0x%x",
			vol->mft_record_size_mask);
	ntfs_debug("vol->mft_record_size_bits = %i (0x%x)",
			vol->mft_record_size_bits, vol->mft_record_size_bits);
	clusters_per_index_record = b->clusters_per_index_record;
	ntfs_debug("clusters_per_index_record = %i (0x%x)",
			clusters_per_index_record, clusters_per_index_record);
	if (clusters_per_index_record > 0)
		vol->index_record_size = vol->cluster_size <<
				(ffs(clusters_per_index_record) - 1);
	else
		/*
		 * When index_record_size < cluster_size,
		 * clusters_per_index_record = -log2(index_record_size) bytes.
		 * index_record_size normaly equals 4096 bytes, which is
		 * encoded as 0xF4 (-12 in decimal).
		 */
		vol->index_record_size = 1 << -clusters_per_index_record;
	vol->index_record_size_mask = vol->index_record_size - 1;
	vol->index_record_size_bits = ffs(vol->index_record_size) - 1;
	ntfs_debug("vol->index_record_size = %i (0x%x)",
			vol->index_record_size, vol->index_record_size);
	ntfs_debug("vol->index_record_size_mask = 0x%x",
			vol->index_record_size_mask);
	ntfs_debug("vol->index_record_size_bits = %i (0x%x)",
			vol->index_record_size_bits,
			vol->index_record_size_bits);
	/*
	 * Get the size of the volume in clusters and check for 64-bit-ness.
	 * Windows currently only uses 32 bits to save the clusters so we do
	 * the same as it is much faster on 32-bit CPUs.
	 */
	ll = sle64_to_cpu(b->number_of_sectors) >> sectors_per_cluster_bits;
	if ((u64)ll >= 1ULL << 32) {
		ntfs_error(vol->sb, "Cannot handle 64-bit clusters. Sorry.");
		return FALSE;
	}
	vol->nr_clusters = ll;
	ntfs_debug("vol->nr_clusters = 0x%llx", (long long)vol->nr_clusters);
	/*
	 * On an architecture where unsigned long is 32-bits, we restrict the
	 * volume size to 2TiB (2^41). On a 64-bit architecture, the compiler
	 * will hopefully optimize the whole check away.
	 */
	if (sizeof(unsigned long) < 8) {
		if ((ll << vol->cluster_size_bits) >= (1ULL << 41)) {
			ntfs_error(vol->sb, "Volume size (%lluTiB) is too "
					"large for this architecture. Maximum "
					"supported is 2TiB. Sorry.",
					(unsigned long long)ll >> (40 -
					vol->cluster_size_bits));
			return FALSE;
		}
	}
	ll = sle64_to_cpu(b->mft_lcn);
	if (ll >= vol->nr_clusters) {
		ntfs_error(vol->sb, "MFT LCN is beyond end of volume. Weird.");
		return FALSE;
	}
	vol->mft_lcn = ll;
	ntfs_debug("vol->mft_lcn = 0x%llx", (long long)vol->mft_lcn);
	ll = sle64_to_cpu(b->mftmirr_lcn);
	if (ll >= vol->nr_clusters) {
		ntfs_error(vol->sb, "MFTMirr LCN is beyond end of volume. "
				"Weird.");
		return FALSE;
	}
	vol->mftmirr_lcn = ll;
	ntfs_debug("vol->mftmirr_lcn = 0x%llx", (long long)vol->mftmirr_lcn);
#ifdef NTFS_RW
	/*
	 * Work out the size of the mft mirror in number of mft records. If the
	 * cluster size is less than or equal to the size taken by four mft
	 * records, the mft mirror stores the first four mft records. If the
	 * cluster size is bigger than the size taken by four mft records, the
	 * mft mirror contains as many mft records as will fit into one
	 * cluster.
	 */
	if (vol->cluster_size <= (4 << vol->mft_record_size_bits))
		vol->mftmirr_size = 4;
	else
		vol->mftmirr_size = vol->cluster_size >>
				vol->mft_record_size_bits;
	ntfs_debug("vol->mftmirr_size = %i", vol->mftmirr_size);
#endif /* NTFS_RW */
	vol->serial_no = le64_to_cpu(b->volume_serial_number);
	ntfs_debug("vol->serial_no = 0x%llx",
			(unsigned long long)vol->serial_no);
	return TRUE;
}