qed: Add QEMU Enhanced Disk image format (75411d23) · Commits · SUMMER2020 / students / proj-2021291

Makefile.objs

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Original line number	Diff line number	Diff line
		@@ -20,6 +20,7 @@ block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o

		block-nested-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vvfat.o
		block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o
		block-nested-y += qed.o
		block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
		block-nested-$(CONFIG_WIN32) += raw-win32.o
		block-nested-$(CONFIG_POSIX) += raw-posix.o

block/qed.c

0 → 100644

+554 −0

Original line number	Diff line number	Diff line
		/*
		* QEMU Enhanced Disk Format
		*
		* Copyright IBM, Corp. 2010
		*
		* Authors:
		* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
		* Anthony Liguori <aliguori@us.ibm.com>
		*
		* This work is licensed under the terms of the GNU LGPL, version 2 or later.
		* See the COPYING.LIB file in the top-level directory.
		*
		*/

		#include "qed.h"

		static int bdrv_qed_probe(const uint8_t *buf, int buf_size,
		const char *filename)
		{
		const QEDHeader header = (const QEDHeader )buf;

		if (buf_size < sizeof(*header)) {
		return 0;
		}
		if (le32_to_cpu(header->magic) != QED_MAGIC) {
		return 0;
		}
		return 100;
		}

		/**
		* Check whether an image format is raw
		*
		* @fmt: Backing file format, may be NULL
		*/
		static bool qed_fmt_is_raw(const char *fmt)
		{
		return fmt && strcmp(fmt, "raw") == 0;
		}

		static void qed_header_le_to_cpu(const QEDHeader le, QEDHeader cpu)
		{
		cpu->magic = le32_to_cpu(le->magic);
		cpu->cluster_size = le32_to_cpu(le->cluster_size);
		cpu->table_size = le32_to_cpu(le->table_size);
		cpu->header_size = le32_to_cpu(le->header_size);
		cpu->features = le64_to_cpu(le->features);
		cpu->compat_features = le64_to_cpu(le->compat_features);
		cpu->autoclear_features = le64_to_cpu(le->autoclear_features);
		cpu->l1_table_offset = le64_to_cpu(le->l1_table_offset);
		cpu->image_size = le64_to_cpu(le->image_size);
		cpu->backing_filename_offset = le32_to_cpu(le->backing_filename_offset);
		cpu->backing_filename_size = le32_to_cpu(le->backing_filename_size);
		}

		static void qed_header_cpu_to_le(const QEDHeader cpu, QEDHeader le)
		{
		le->magic = cpu_to_le32(cpu->magic);
		le->cluster_size = cpu_to_le32(cpu->cluster_size);
		le->table_size = cpu_to_le32(cpu->table_size);
		le->header_size = cpu_to_le32(cpu->header_size);
		le->features = cpu_to_le64(cpu->features);
		le->compat_features = cpu_to_le64(cpu->compat_features);
		le->autoclear_features = cpu_to_le64(cpu->autoclear_features);
		le->l1_table_offset = cpu_to_le64(cpu->l1_table_offset);
		le->image_size = cpu_to_le64(cpu->image_size);
		le->backing_filename_offset = cpu_to_le32(cpu->backing_filename_offset);
		le->backing_filename_size = cpu_to_le32(cpu->backing_filename_size);
		}

		static int qed_write_header_sync(BDRVQEDState *s)
		{
		QEDHeader le;
		int ret;

		qed_header_cpu_to_le(&s->header, &le);
		ret = bdrv_pwrite(s->bs->file, 0, &le, sizeof(le));
		if (ret != sizeof(le)) {
		return ret;
		}
		return 0;
		}

		static uint64_t qed_max_image_size(uint32_t cluster_size, uint32_t table_size)
		{
		uint64_t table_entries;
		uint64_t l2_size;

		table_entries = (table_size * cluster_size) / sizeof(uint64_t);
		l2_size = table_entries * cluster_size;

		return l2_size * table_entries;
		}

		static bool qed_is_cluster_size_valid(uint32_t cluster_size)
		{
		if (cluster_size < QED_MIN_CLUSTER_SIZE \|\|
		cluster_size > QED_MAX_CLUSTER_SIZE) {
		return false;
		}
		if (cluster_size & (cluster_size - 1)) {
		return false; /* not power of 2 */
		}
		return true;
		}

		static bool qed_is_table_size_valid(uint32_t table_size)
		{
		if (table_size < QED_MIN_TABLE_SIZE \|\|
		table_size > QED_MAX_TABLE_SIZE) {
		return false;
		}
		if (table_size & (table_size - 1)) {
		return false; /* not power of 2 */
		}
		return true;
		}

		static bool qed_is_image_size_valid(uint64_t image_size, uint32_t cluster_size,
		uint32_t table_size)
		{
		if (image_size % BDRV_SECTOR_SIZE != 0) {
		return false; /* not multiple of sector size */
		}
		if (image_size > qed_max_image_size(cluster_size, table_size)) {
		return false; /* image is too large */
		}
		return true;
		}

		/**
		* Read a string of known length from the image file
		*
		* @file: Image file
		* @offset: File offset to start of string, in bytes
		* @n: String length in bytes
		* @buf: Destination buffer
		* @buflen: Destination buffer length in bytes
		* @ret: 0 on success, -errno on failure
		*
		* The string is NUL-terminated.
		*/
		static int qed_read_string(BlockDriverState *file, uint64_t offset, size_t n,
		char *buf, size_t buflen)
		{
		int ret;
		if (n >= buflen) {
		return -EINVAL;
		}
		ret = bdrv_pread(file, offset, buf, n);
		if (ret < 0) {
		return ret;
		}
		buf[n] = '\0';
		return 0;
		}

		static int bdrv_qed_open(BlockDriverState *bs, int flags)
		{
		BDRVQEDState *s = bs->opaque;
		QEDHeader le_header;
		int64_t file_size;
		int ret;

		s->bs = bs;

		ret = bdrv_pread(bs->file, 0, &le_header, sizeof(le_header));
		if (ret < 0) {
		return ret;
		}
		ret = 0; /* ret should always be 0 or -errno */
		qed_header_le_to_cpu(&le_header, &s->header);

		if (s->header.magic != QED_MAGIC) {
		return -EINVAL;
		}
		if (s->header.features & ~QED_FEATURE_MASK) {
		return -ENOTSUP; /* image uses unsupported feature bits */
		}
		if (!qed_is_cluster_size_valid(s->header.cluster_size)) {
		return -EINVAL;
		}

		/* Round down file size to the last cluster */
		file_size = bdrv_getlength(bs->file);
		if (file_size < 0) {
		return file_size;
		}
		s->file_size = qed_start_of_cluster(s, file_size);

		if (!qed_is_table_size_valid(s->header.table_size)) {
		return -EINVAL;
		}
		if (!qed_is_image_size_valid(s->header.image_size,
		s->header.cluster_size,
		s->header.table_size)) {
		return -EINVAL;
		}
		if (!qed_check_table_offset(s, s->header.l1_table_offset)) {
		return -EINVAL;
		}

		s->table_nelems = (s->header.cluster_size * s->header.table_size) /
		sizeof(uint64_t);
		s->l2_shift = ffs(s->header.cluster_size) - 1;
		s->l2_mask = s->table_nelems - 1;
		s->l1_shift = s->l2_shift + ffs(s->table_nelems) - 1;

		if ((s->header.features & QED_F_BACKING_FILE)) {
		if ((uint64_t)s->header.backing_filename_offset +
		s->header.backing_filename_size >
		s->header.cluster_size * s->header.header_size) {
		return -EINVAL;
		}

		ret = qed_read_string(bs->file, s->header.backing_filename_offset,
		s->header.backing_filename_size, bs->backing_file,
		sizeof(bs->backing_file));
		if (ret < 0) {
		return ret;
		}

		if (s->header.features & QED_F_BACKING_FORMAT_NO_PROBE) {
		pstrcpy(bs->backing_format, sizeof(bs->backing_format), "raw");
		}
		}

		/* Reset unknown autoclear feature bits. This is a backwards
		* compatibility mechanism that allows images to be opened by older
		* programs, which "knock out" unknown feature bits. When an image is
		* opened by a newer program again it can detect that the autoclear
		* feature is no longer valid.
		*/
		if ((s->header.autoclear_features & ~QED_AUTOCLEAR_FEATURE_MASK) != 0 &&
		!bdrv_is_read_only(bs->file)) {
		s->header.autoclear_features &= QED_AUTOCLEAR_FEATURE_MASK;

		ret = qed_write_header_sync(s);
		if (ret) {
		return ret;
		}

		/* From here on only known autoclear feature bits are valid */
		bdrv_flush(bs->file);
		}

		return ret;
		}

		static void bdrv_qed_close(BlockDriverState *bs)
		{
		}

		static int bdrv_qed_flush(BlockDriverState *bs)
		{
		return bdrv_flush(bs->file);
		}

		static int qed_create(const char *filename, uint32_t cluster_size,
		uint64_t image_size, uint32_t table_size,
		const char backing_file, const char backing_fmt)
		{
		QEDHeader header = {
		.magic = QED_MAGIC,
		.cluster_size = cluster_size,
		.table_size = table_size,
		.header_size = 1,
		.features = 0,
		.compat_features = 0,
		.l1_table_offset = cluster_size,
		.image_size = image_size,
		};
		QEDHeader le_header;
		uint8_t *l1_table = NULL;
		size_t l1_size = header.cluster_size * header.table_size;
		int ret = 0;
		BlockDriverState *bs = NULL;

		ret = bdrv_create_file(filename, NULL);
		if (ret < 0) {
		return ret;
		}

		ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR \| BDRV_O_CACHE_WB);
		if (ret < 0) {
		return ret;
		}

		if (backing_file) {
		header.features \|= QED_F_BACKING_FILE;
		header.backing_filename_offset = sizeof(le_header);
		header.backing_filename_size = strlen(backing_file);

		if (qed_fmt_is_raw(backing_fmt)) {
		header.features \|= QED_F_BACKING_FORMAT_NO_PROBE;
		}
		}

		qed_header_cpu_to_le(&header, &le_header);
		ret = bdrv_pwrite(bs, 0, &le_header, sizeof(le_header));
		if (ret < 0) {
		goto out;
		}
		ret = bdrv_pwrite(bs, sizeof(le_header), backing_file,
		header.backing_filename_size);
		if (ret < 0) {
		goto out;
		}

		l1_table = qemu_mallocz(l1_size);
		ret = bdrv_pwrite(bs, header.l1_table_offset, l1_table, l1_size);
		if (ret < 0) {
		goto out;
		}

		ret = 0; /* success */
		out:
		qemu_free(l1_table);
		bdrv_delete(bs);
		return ret;
		}

		static int bdrv_qed_create(const char filename, QEMUOptionParameter options)
		{
		uint64_t image_size = 0;
		uint32_t cluster_size = QED_DEFAULT_CLUSTER_SIZE;
		uint32_t table_size = QED_DEFAULT_TABLE_SIZE;
		const char *backing_file = NULL;
		const char *backing_fmt = NULL;

		while (options && options->name) {
		if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
		image_size = options->value.n;
		} else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) {
		backing_file = options->value.s;
		} else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) {
		backing_fmt = options->value.s;
		} else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) {
		if (options->value.n) {
		cluster_size = options->value.n;
		}
		} else if (!strcmp(options->name, BLOCK_OPT_TABLE_SIZE)) {
		if (options->value.n) {
		table_size = options->value.n;
		}
		}
		options++;
		}

		if (!qed_is_cluster_size_valid(cluster_size)) {
		fprintf(stderr, "QED cluster size must be within range [%u, %u] and power of 2\n",
		QED_MIN_CLUSTER_SIZE, QED_MAX_CLUSTER_SIZE);
		return -EINVAL;
		}
		if (!qed_is_table_size_valid(table_size)) {
		fprintf(stderr, "QED table size must be within range [%u, %u] and power of 2\n",
		QED_MIN_TABLE_SIZE, QED_MAX_TABLE_SIZE);
		return -EINVAL;
		}
		if (!qed_is_image_size_valid(image_size, cluster_size, table_size)) {
		fprintf(stderr, "QED image size must be a non-zero multiple of "
		"cluster size and less than %" PRIu64 " bytes\n",
		qed_max_image_size(cluster_size, table_size));
		return -EINVAL;
		}

		return qed_create(filename, cluster_size, image_size, table_size,
		backing_file, backing_fmt);
		}

		static int bdrv_qed_is_allocated(BlockDriverState *bs, int64_t sector_num,
		int nb_sectors, int *pnum)
		{
		return -ENOTSUP;
		}

		static int bdrv_qed_make_empty(BlockDriverState *bs)
		{
		return -ENOTSUP;
		}

		static BlockDriverAIOCB bdrv_qed_aio_readv(BlockDriverState bs,
		int64_t sector_num,
		QEMUIOVector *qiov, int nb_sectors,
		BlockDriverCompletionFunc *cb,
		void *opaque)
		{
		return NULL;
		}

		static BlockDriverAIOCB bdrv_qed_aio_writev(BlockDriverState bs,
		int64_t sector_num,
		QEMUIOVector *qiov, int nb_sectors,
		BlockDriverCompletionFunc *cb,
		void *opaque)
		{
		return NULL;
		}

		static BlockDriverAIOCB bdrv_qed_aio_flush(BlockDriverState bs,
		BlockDriverCompletionFunc *cb,
		void *opaque)
		{
		return bdrv_aio_flush(bs->file, cb, opaque);
		}

		static int bdrv_qed_truncate(BlockDriverState *bs, int64_t offset)
		{
		return -ENOTSUP;
		}

		static int64_t bdrv_qed_getlength(BlockDriverState *bs)
		{
		BDRVQEDState *s = bs->opaque;
		return s->header.image_size;
		}

		static int bdrv_qed_get_info(BlockDriverState bs, BlockDriverInfo bdi)
		{
		BDRVQEDState *s = bs->opaque;

		memset(bdi, 0, sizeof(*bdi));
		bdi->cluster_size = s->header.cluster_size;
		return 0;
		}

		static int bdrv_qed_change_backing_file(BlockDriverState *bs,
		const char *backing_file,
		const char *backing_fmt)
		{
		BDRVQEDState *s = bs->opaque;
		QEDHeader new_header, le_header;
		void *buffer;
		size_t buffer_len, backing_file_len;
		int ret;

		/* Refuse to set backing filename if unknown compat feature bits are
		* active. If the image uses an unknown compat feature then we may not
		* know the layout of data following the header structure and cannot safely
		* add a new string.
		*/
		if (backing_file && (s->header.compat_features &
		~QED_COMPAT_FEATURE_MASK)) {
		return -ENOTSUP;
		}

		memcpy(&new_header, &s->header, sizeof(new_header));

		new_header.features &= ~(QED_F_BACKING_FILE \|
		QED_F_BACKING_FORMAT_NO_PROBE);

		/* Adjust feature flags */
		if (backing_file) {
		new_header.features \|= QED_F_BACKING_FILE;

		if (qed_fmt_is_raw(backing_fmt)) {
		new_header.features \|= QED_F_BACKING_FORMAT_NO_PROBE;
		}
		}

		/* Calculate new header size */
		backing_file_len = 0;

		if (backing_file) {
		backing_file_len = strlen(backing_file);
		}

		buffer_len = sizeof(new_header);
		new_header.backing_filename_offset = buffer_len;
		new_header.backing_filename_size = backing_file_len;
		buffer_len += backing_file_len;

		/* Make sure we can rewrite header without failing */
		if (buffer_len > new_header.header_size * new_header.cluster_size) {
		return -ENOSPC;
		}

		/* Prepare new header */
		buffer = qemu_malloc(buffer_len);

		qed_header_cpu_to_le(&new_header, &le_header);
		memcpy(buffer, &le_header, sizeof(le_header));
		buffer_len = sizeof(le_header);

		memcpy(buffer + buffer_len, backing_file, backing_file_len);
		buffer_len += backing_file_len;

		/* Write new header */
		ret = bdrv_pwrite_sync(bs->file, 0, buffer, buffer_len);
		qemu_free(buffer);
		if (ret == 0) {
		memcpy(&s->header, &new_header, sizeof(new_header));
		}
		return ret;
		}

		static int bdrv_qed_check(BlockDriverState bs, BdrvCheckResult result)
		{
		return -ENOTSUP;
		}

		static QEMUOptionParameter qed_create_options[] = {
		{
		.name = BLOCK_OPT_SIZE,
		.type = OPT_SIZE,
		.help = "Virtual disk size (in bytes)"
		}, {
		.name = BLOCK_OPT_BACKING_FILE,
		.type = OPT_STRING,
		.help = "File name of a base image"
		}, {
		.name = BLOCK_OPT_BACKING_FMT,
		.type = OPT_STRING,
		.help = "Image format of the base image"
		}, {
		.name = BLOCK_OPT_CLUSTER_SIZE,
		.type = OPT_SIZE,
		.help = "Cluster size (in bytes)"
		}, {
		.name = BLOCK_OPT_TABLE_SIZE,
		.type = OPT_SIZE,
		.help = "L1/L2 table size (in clusters)"
		},
		{ /* end of list */ }
		};

		static BlockDriver bdrv_qed = {
		.format_name = "qed",
		.instance_size = sizeof(BDRVQEDState),
		.create_options = qed_create_options,

		.bdrv_probe = bdrv_qed_probe,
		.bdrv_open = bdrv_qed_open,
		.bdrv_close = bdrv_qed_close,
		.bdrv_create = bdrv_qed_create,
		.bdrv_flush = bdrv_qed_flush,
		.bdrv_is_allocated = bdrv_qed_is_allocated,
		.bdrv_make_empty = bdrv_qed_make_empty,
		.bdrv_aio_readv = bdrv_qed_aio_readv,
		.bdrv_aio_writev = bdrv_qed_aio_writev,
		.bdrv_aio_flush = bdrv_qed_aio_flush,
		.bdrv_truncate = bdrv_qed_truncate,
		.bdrv_getlength = bdrv_qed_getlength,
		.bdrv_get_info = bdrv_qed_get_info,
		.bdrv_change_backing_file = bdrv_qed_change_backing_file,
		.bdrv_check = bdrv_qed_check,
		};

		static void bdrv_qed_init(void)
		{
		bdrv_register(&bdrv_qed);
		}

		block_init(bdrv_qed_init);

block/qed.h

0 → 100644

+148 −0

Original line number	Diff line number	Diff line
		/*
		* QEMU Enhanced Disk Format
		*
		* Copyright IBM, Corp. 2010
		*
		* Authors:
		* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
		* Anthony Liguori <aliguori@us.ibm.com>
		*
		* This work is licensed under the terms of the GNU LGPL, version 2 or later.
		* See the COPYING.LIB file in the top-level directory.
		*
		*/

		#ifndef BLOCK_QED_H
		#define BLOCK_QED_H

		#include "block_int.h"

		/* The layout of a QED file is as follows:
		*
		* +--------+----------+----------+----------+-----+
		* \| header \| L1 table \| cluster0 \| cluster1 \| ... \|
		* +--------+----------+----------+----------+-----+
		*
		* There is a 2-level pagetable for cluster allocation:
		*
		* +----------+
		* \| L1 table \|
		* +----------+
		* ,------' \| '------.
		* +----------+ \| +----------+
		* \| L2 table \| ... \| L2 table \|
		* +----------+ +----------+
		* ,------' \| '------.
		* +----------+ \| +----------+
		* \| Data \| ... \| Data \|
		* +----------+ +----------+
		*
		* The L1 table is fixed size and always present. L2 tables are allocated on
		* demand. The L1 table size determines the maximum possible image size; it
		* can be influenced using the cluster_size and table_size values.
		*
		* All fields are little-endian on disk.
		*/

		enum {
		QED_MAGIC = 'Q' \| 'E' << 8 \| 'D' << 16 \| '\0' << 24,

		/* The image supports a backing file */
		QED_F_BACKING_FILE = 0x01,

		/* The backing file format must not be probed, treat as raw image */
		QED_F_BACKING_FORMAT_NO_PROBE = 0x04,

		/* Feature bits must be used when the on-disk format changes */
		QED_FEATURE_MASK = QED_F_BACKING_FILE \| /* supported feature bits */
		QED_F_BACKING_FORMAT_NO_PROBE,
		QED_COMPAT_FEATURE_MASK = 0, /* supported compat feature bits */
		QED_AUTOCLEAR_FEATURE_MASK = 0, /* supported autoclear feature bits */

		/* Data is stored in groups of sectors called clusters. Cluster size must
		* be large to avoid keeping too much metadata. I/O requests that have
		* sub-cluster size will require read-modify-write.
		*/
		QED_MIN_CLUSTER_SIZE = 4 * 1024, /* in bytes */
		QED_MAX_CLUSTER_SIZE = 64 * 1024 * 1024,
		QED_DEFAULT_CLUSTER_SIZE = 64 * 1024,

		/* Allocated clusters are tracked using a 2-level pagetable. Table size is
		* a multiple of clusters so large maximum image sizes can be supported
		* without jacking up the cluster size too much.
		*/
		QED_MIN_TABLE_SIZE = 1, /* in clusters */
		QED_MAX_TABLE_SIZE = 16,
		QED_DEFAULT_TABLE_SIZE = 4,
		};

		typedef struct {
		uint32_t magic; /* QED\0 */

		uint32_t cluster_size; /* in bytes */
		uint32_t table_size; /* for L1 and L2 tables, in clusters */
		uint32_t header_size; /* in clusters */

		uint64_t features; /* format feature bits */
		uint64_t compat_features; /* compatible feature bits */
		uint64_t autoclear_features; /* self-resetting feature bits */

		uint64_t l1_table_offset; /* in bytes */
		uint64_t image_size; /* total logical image size, in bytes */

		/* if (features & QED_F_BACKING_FILE) */
		uint32_t backing_filename_offset; /* in bytes from start of header */
		uint32_t backing_filename_size; /* in bytes */
		} QEDHeader;

		typedef struct {
		BlockDriverState bs; / device */
		uint64_t file_size; /* length of image file, in bytes */

		QEDHeader header; /* always cpu-endian */
		uint32_t table_nelems;
		uint32_t l1_shift;
		uint32_t l2_shift;
		uint32_t l2_mask;
		} BDRVQEDState;

		/**
		* Round down to the start of a cluster
		*/
		static inline uint64_t qed_start_of_cluster(BDRVQEDState *s, uint64_t offset)
		{
		return offset & ~(uint64_t)(s->header.cluster_size - 1);
		}

		/**
		* Test if a cluster offset is valid
		*/
		static inline bool qed_check_cluster_offset(BDRVQEDState *s, uint64_t offset)
		{
		uint64_t header_size = (uint64_t)s->header.header_size *
		s->header.cluster_size;

		if (offset & (s->header.cluster_size - 1)) {
		return false;
		}
		return offset >= header_size && offset < s->file_size;
		}

		/**
		* Test if a table offset is valid
		*/
		static inline bool qed_check_table_offset(BDRVQEDState *s, uint64_t offset)
		{
		uint64_t end_offset = offset + (s->header.table_size - 1) *
		s->header.cluster_size;

		/* Overflow check */
		if (end_offset <= offset) {
		return false;
		}

		return qed_check_cluster_offset(s, offset) &&
		qed_check_cluster_offset(s, end_offset);
		}

		#endif /* BLOCK_QED_H */

block_int.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -37,6 +37,7 @@
		#define BLOCK_OPT_BACKING_FILE "backing_file"
		#define BLOCK_OPT_BACKING_FMT "backing_fmt"
		#define BLOCK_OPT_CLUSTER_SIZE "cluster_size"
		#define BLOCK_OPT_TABLE_SIZE "table_size"
		#define BLOCK_OPT_PREALLOC "preallocation"

		typedef struct AIOPool {