On Fri, Aug 10, 2012 at 11:39:44PM +0800, Dong Xu Wang wrote:
> add-cow file format core code. It use block-cache.c as cache code.
>
> Signed-off-by: Dong Xu Wang <wdon...@linux.vnet.ibm.com>
> ---
> block/Makefile.objs | 1 +
> block/add-cow.c | 613
> +++++++++++++++++++++++++++++++++++++++++++++++++++
> block/add-cow.h | 85 +++++++
> block_int.h | 2 +
> 4 files changed, 701 insertions(+), 0 deletions(-)
> create mode 100644 block/add-cow.c
> create mode 100644 block/add-cow.h
>
> diff --git a/block/Makefile.objs b/block/Makefile.objs
> index 23bdfc8..7ed5051 100644
> --- a/block/Makefile.objs
> +++ b/block/Makefile.objs
> @@ -2,6 +2,7 @@ block-obj-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o
> bochs.o vpc.o vvfat
> block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o
> block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
> block-obj-y += qed-check.o
> +block-obj-y += add-cow.o
> block-obj-y += block-cache.o
> block-obj-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
> block-obj-y += stream.o
> diff --git a/block/add-cow.c b/block/add-cow.c
> new file mode 100644
> index 0000000..d4711d5
> --- /dev/null
> +++ b/block/add-cow.c
> @@ -0,0 +1,613 @@
> +/*
> + * QEMU ADD-COW Disk Format
> + *
> + * Copyright IBM, Corp. 2012
> + *
> + * Authors:
> + * Dong Xu Wang <wdon...@linux.vnet.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 "qemu-common.h"
> +#include "block_int.h"
> +#include "module.h"
> +#include "add-cow.h"
> +
> +static void add_cow_header_le_to_cpu(const AddCowHeader *le, AddCowHeader
> *cpu)
> +{
> + cpu->magic = le64_to_cpu(le->magic);
> + cpu->version = le32_to_cpu(le->version);
> +
> + cpu->backing_filename_offset =
> le32_to_cpu(le->backing_filename_offset);
> + cpu->backing_filename_size = le32_to_cpu(le->backing_filename_size);
> +
> + cpu->image_filename_offset = le32_to_cpu(le->image_filename_offset);
> + cpu->image_filename_size = le32_to_cpu(le->image_filename_size);
> +
> + cpu->features = le64_to_cpu(le->features);
> + cpu->optional_features = le64_to_cpu(le->optional_features);
> + cpu->header_pages_size = le32_to_cpu(le->header_pages_size);
> +}
> +
> +static void add_cow_header_cpu_to_le(const AddCowHeader *cpu, AddCowHeader
> *le)
> +{
> + le->magic = cpu_to_le64(cpu->magic);
> + le->version = cpu_to_le32(cpu->version);
> +
> + le->backing_filename_offset =
> cpu_to_le32(cpu->backing_filename_offset);
> + le->backing_filename_size =
> cpu_to_le32(cpu->backing_filename_size);
> +
> + le->image_filename_offset =
> cpu_to_le32(cpu->image_filename_offset);
> + le->image_filename_size = cpu_to_le32(cpu->image_filename_size);
> +
> + le->features = cpu_to_le64(cpu->features);
> + le->optional_features = cpu_to_le64(cpu->optional_features);
> + le->header_pages_size = cpu_to_le32(cpu->header_pages_size);
> +}
> +
> +static int add_cow_probe(const uint8_t *buf, int buf_size, const char
> *filename)
> +{
> + const AddCowHeader *header = (const AddCowHeader *)buf;
> +
> + if (le64_to_cpu(header->magic) == ADD_COW_MAGIC &&
> + le32_to_cpu(header->version) == ADD_COW_VERSION) {
> + return 100;
> + } else {
> + return 0;
> + }
> +}
> +
> +static int add_cow_create(const char *filename, QEMUOptionParameter *options)
> +{
> + AddCowHeader header = {
> + .magic = ADD_COW_MAGIC,
> + .version = ADD_COW_VERSION,
> + .features = 0,
> + .optional_features = 0,
> + .header_pages_size = ADD_COW_DEFAULT_PAGE_SIZE,
> + };
> + AddCowHeader le_header;
> + int64_t image_len = 0;
> + const char *backing_filename = NULL;
> + const char *backing_fmt = NULL;
> + const char *image_filename = NULL;
> + const char *image_format = NULL;
> + BlockDriverState *bs, *image_bs = NULL, *backing_bs = NULL;
> + BlockDriver *drv = bdrv_find_format("add-cow");
> + BDRVAddCowState s;
> + int ret;
> +
> + while (options && options->name) {
> + if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
> + image_len = options->value.n;
> + } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) {
> + backing_filename = options->value.s;
> + } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) {
> + backing_fmt = options->value.s;
> + } else if (!strcmp(options->name, BLOCK_OPT_IMAGE_FILE)) {
> + image_filename = options->value.s;
> + } else if (!strcmp(options->name, BLOCK_OPT_IMAGE_FORMAT)) {
> + image_format = options->value.s;
> + }
> + options++;
> + }
> +
> + if (backing_filename) {
> + header.backing_filename_offset = sizeof(header)
> + + sizeof(s.backing_file_format) + sizeof(s.image_file_format);
> + header.backing_filename_size = strlen(backing_filename);
> +
> + if (!backing_fmt) {
> + backing_bs = bdrv_new("image");
> + ret = bdrv_open(backing_bs, backing_filename, BDRV_O_RDWR
> + | BDRV_O_CACHE_WB, NULL);
> + if (ret < 0) {
> + return ret;
> + }
> + backing_fmt = bdrv_get_format_name(backing_bs);
> + bdrv_delete(backing_bs);
> + }
> + } else {
> + header.features |= ADD_COW_F_All_ALLOCATED;
> + }
> +
> + if (image_filename) {
> + header.image_filename_offset =
> + sizeof(header) + sizeof(s.backing_file_format)
> + + sizeof(s.image_file_format) + header.backing_filename_size;
> + header.image_filename_size = strlen(image_filename);
> + } else {
> + error_report("Error: image_file should be given.");
> + return -EINVAL;
> + }
> +
> + if (backing_filename && !strcmp(backing_filename, image_filename)) {
> + error_report("Error: Trying to create an image with the "
> + "same backing file name as the image file name");
> + return -EINVAL;
> + }
> +
> + if (!strcmp(filename, image_filename)) {
> + error_report("Error: Trying to create an image with the "
> + "same filename as the image file name");
> + return -EINVAL;
> + }
> +
> + if (header.image_filename_offset + header.image_filename_size
> + > ADD_COW_PAGE_SIZE * ADD_COW_DEFAULT_PAGE_SIZE) {
> + error_report("image_file name or backing_file name too long.");
> + return -ENOSPC;
> + }
> +
> + ret = bdrv_file_open(&image_bs, image_filename, BDRV_O_RDWR);
> + if (ret < 0) {
> + return ret;
> + }
> + bdrv_delete(image_bs);
> +
> + ret = bdrv_create_file(filename, NULL);
> + if (ret < 0) {
> + return ret;
> + }
> +
> + ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR);
> + if (ret < 0) {
> + return ret;
> + }
> + add_cow_header_cpu_to_le(&header, &le_header);
> + ret = bdrv_pwrite(bs, 0, &le_header, sizeof(le_header));
> + if (ret < 0) {
> + bdrv_delete(bs);
> + return ret;
> + }
> +
> + ret = bdrv_pwrite(bs, sizeof(le_header), backing_fmt ? backing_fmt : "",
> + backing_fmt ? strlen(backing_fmt) : 0);
> + if (ret < 0) {
> + bdrv_delete(bs);
> + return ret;
> + }
> +
> + ret = bdrv_pwrite(bs, sizeof(le_header) + sizeof(s.backing_file_format),
> + image_format ? image_format : "raw",
> + image_format ? strlen(image_format) : sizeof("raw"));
> + if (ret < 0) {
> + bdrv_delete(bs);
> + return ret;
> + }
> +
> + if (backing_filename) {
> + ret = bdrv_pwrite(bs, header.backing_filename_offset,
> + backing_filename, header.backing_filename_size);
> + if (ret < 0) {
> + bdrv_delete(bs);
> + return ret;
> + }
> + }
> +
> + ret = bdrv_pwrite(bs, header.image_filename_offset,
> + image_filename, header.image_filename_size);
> + if (ret < 0) {
> + bdrv_delete(bs);
> + return ret;
> + }
> +
> + ret = bdrv_open(bs, filename, BDRV_O_RDWR | BDRV_O_NO_FLUSH, drv);
> + if (ret < 0) {
> + bdrv_delete(bs);
> + return ret;
> + }
> +
> + ret = bdrv_truncate(bs, image_len);
> + bdrv_delete(bs);
> + return ret;
> +}
> +
> +static int add_cow_open(BlockDriverState *bs, int flags)
> +{
> + char image_filename[ADD_COW_FILE_LEN];
> + char tmp_name[ADD_COW_FILE_LEN];
> + BlockDriver *image_drv = NULL;
> + int ret;
> + int sector_per_byte;
> + BDRVAddCowState *s = bs->opaque;
> + AddCowHeader le_header;
> +
> + ret = bdrv_pread(bs->file, 0, &le_header, sizeof(le_header));
> + if (ret != sizeof(s->header)) {
> + goto fail;
> + }
> +
> + add_cow_header_le_to_cpu(&le_header, &s->header);
> +
> + if (le64_to_cpu(s->header.magic) != ADD_COW_MAGIC) {
> + ret = -EINVAL;
> + goto fail;
> + }
> +
> + if (s->header.version != ADD_COW_VERSION) {
> + char version[64];
> + snprintf(version, sizeof(version), "ADD-COW version %d",
> + s->header.version);
> + qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE,
> + bs->device_name, "add-cow", version);
> + ret = -ENOTSUP;
> + goto fail;
> + }
> +
> + if (s->header.features & ~ADD_COW_FEATURE_MASK) {
> + char buf[64];
> + snprintf(buf, sizeof(buf), "%" PRIx64,
> + s->header.features & ~ADD_COW_FEATURE_MASK);
> + qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE,
> + bs->device_name, "add-cow", buf);
> + return -ENOTSUP;
> + }
> +
> + if ((s->header.features & ADD_COW_F_All_ALLOCATED) == 0) {
> + ret = bdrv_read_string(bs->file, sizeof(s->header),
> + sizeof(s->backing_file_format) - 1, s->backing_file_format,
> + sizeof(s->backing_file_format));
> + if (ret < 0) {
> + goto fail;
> + }
> + }
> +
> + ret = bdrv_read_string(bs->file,
> + sizeof(s->header) + sizeof(s->image_file_format),
> + sizeof(s->image_file_format) - 1, s->image_file_format,
> + sizeof(s->image_file_format));
> + if (ret < 0) {
> + goto fail;
> + }
> +
> + if ((s->header.features & ADD_COW_F_All_ALLOCATED) == 0) {
> + ret = bdrv_read_string(bs->file, s->header.backing_filename_offset,
> + s->header.backing_filename_size, bs->backing_file,
> + sizeof(bs->backing_file));
> + if (ret < 0) {
> + goto fail;
> + }
> + }
> +
> + ret = bdrv_read_string(bs->file, s->header.image_filename_offset,
> + s->header.image_filename_size, tmp_name,
> + sizeof(tmp_name));
> + if (ret < 0) {
> + goto fail;
> + }
> +
> + s->image_hd = bdrv_new("");
> + if (path_has_protocol(image_filename)) {
> + pstrcpy(image_filename, sizeof(image_filename), tmp_name);
> + } else {
> + path_combine(image_filename, sizeof(image_filename),
> + bs->filename, tmp_name);
> + }
> +
> + ret = bdrv_open(s->image_hd, image_filename, flags, image_drv);
> + if (ret < 0) {
> + bdrv_delete(s->image_hd);
> + goto fail;
> + }
> +
> + bs->total_sectors = bdrv_getlength(s->image_hd) >> 9;
> + s->cluster_size = ADD_COW_CLUSTER_SIZE;
> + sector_per_byte = SECTORS_PER_CLUSTER * 8;
> + s->bitmap_size =
> + (bs->total_sectors + sector_per_byte - 1) / sector_per_byte;
> + s->bitmap_cache =
> + block_cache_create(bs, ADD_COW_CACHE_SIZE, ADD_COW_CACHE_ENTRY_SIZE);
> +
> + qemu_co_mutex_init(&s->lock);
> + return 0;
> +fail:
> + if (s->bitmap_cache) {
> + block_cache_destroy(bs, s->bitmap_cache, BLOCK_TABLE_BITMAP);
> + }
> + return ret;
> +}
> +
> +static void add_cow_close(BlockDriverState *bs)
> +{
> + BDRVAddCowState *s = bs->opaque;
> + block_cache_destroy(bs, s->bitmap_cache, BLOCK_TABLE_BITMAP);
> + bdrv_delete(s->image_hd);
> +}
> +
> +static bool is_allocated(BlockDriverState *bs, int64_t sector_num)
> +{
> + BDRVAddCowState *s = bs->opaque;
> + BlockCache *c = s->bitmap_cache;
> + int64_t cluster_num = sector_num / SECTORS_PER_CLUSTER;
> + uint8_t *table = NULL;
> + uint64_t offset = ADD_COW_PAGE_SIZE * s->header.header_pages_size
> + + (offset_in_bitmap(sector_num) & (~(c->entry_size - 1)));
> + int ret = block_cache_get(bs, s->bitmap_cache, offset,
> + (void **)&table, BLOCK_TABLE_BITMAP, ADD_COW_CACHE_ENTRY_SIZE);
> +
> + if (ret < 0) {
> + return ret;
> + }
> + return table[cluster_num / 8 % ADD_COW_CACHE_ENTRY_SIZE]
> + & (1 << (cluster_num % 8));
> +}
> +
> +static coroutine_fn int add_cow_is_allocated(BlockDriverState *bs,
> + int64_t sector_num, int nb_sectors, int *num_same)
> +{
> + BDRVAddCowState *s = bs->opaque;
> + int changed;
> +
> + if (nb_sectors == 0) {
> + *num_same = 0;
> + return 0;
> + }
> +
> + if (s->header.features & ADD_COW_F_All_ALLOCATED) {
> + *num_same = nb_sectors - 1;
> + return 1;
> + }
> + changed = is_allocated(bs, sector_num);
> +
> + for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) {
> + if (is_allocated(bs, sector_num + *num_same) != changed) {
> + break;
> + }
> + }
> + return changed;
> +}
> +
> +static int add_cow_backing_read(BlockDriverState *bs, QEMUIOVector *qiov,
> + int64_t sector_num, int nb_sectors)
> +{
> + int n1;
> + if ((sector_num + nb_sectors) <= bs->total_sectors) {
> + return nb_sectors;
> + }
> + if (sector_num >= bs->total_sectors) {
> + n1 = 0;
> + } else {
> + n1 = bs->total_sectors - sector_num;
> + }
> +
> + qemu_iovec_memset(qiov, BDRV_SECTOR_SIZE * n1,
> + 0, BDRV_SECTOR_SIZE * (nb_sectors - n1));
> +
> + return n1;
> +}
> +
> +static coroutine_fn int add_cow_co_readv(BlockDriverState *bs,
> + int64_t sector_num, int remaining_sectors, QEMUIOVector *qiov)
> +{
> + BDRVAddCowState *s = bs->opaque;
> + int cur_nr_sectors;
> + uint64_t bytes_done = 0;
> + QEMUIOVector hd_qiov;
> + int n, n1, ret = 0;
> +
> + qemu_iovec_init(&hd_qiov, qiov->niov);
> + qemu_co_mutex_lock(&s->lock);
> + while (remaining_sectors != 0) {
> + cur_nr_sectors = remaining_sectors;
> + if (add_cow_is_allocated(bs, sector_num, cur_nr_sectors, &n)) {
> + cur_nr_sectors = n;
> + qemu_iovec_reset(&hd_qiov);
> + qemu_iovec_concat(&hd_qiov, qiov, bytes_done,
> + cur_nr_sectors * BDRV_SECTOR_SIZE);
> + qemu_co_mutex_unlock(&s->lock);
> + ret = bdrv_co_readv(s->image_hd, sector_num, n, &hd_qiov);
> + qemu_co_mutex_lock(&s->lock);
> + if (ret < 0) {
> + goto fail;
> + }
> + } else {
> + cur_nr_sectors = n;
> + if (bs->backing_hd) {
> + qemu_iovec_reset(&hd_qiov);
> + qemu_iovec_concat(&hd_qiov, qiov, bytes_done,
> + cur_nr_sectors * BDRV_SECTOR_SIZE);
> + n1 = add_cow_backing_read(bs->backing_hd, &hd_qiov,
> + sector_num, cur_nr_sectors);
> + if (n1 > 0) {
> + qemu_co_mutex_unlock(&s->lock);
> + ret = bdrv_co_readv(bs->backing_hd, sector_num,
> + n, &hd_qiov);
> + qemu_co_mutex_lock(&s->lock);
> + if (ret < 0) {
> + goto fail;
> + }
> + }
> + } else {
> + qemu_iovec_memset(&hd_qiov, 0, 0,
> + BDRV_SECTOR_SIZE * cur_nr_sectors);
> + }
> + }
> + remaining_sectors -= cur_nr_sectors;
> + sector_num += cur_nr_sectors;
> + bytes_done += cur_nr_sectors * BDRV_SECTOR_SIZE;
> + }
> +fail:
> + qemu_co_mutex_unlock(&s->lock);
> + qemu_iovec_destroy(&hd_qiov);
> + return ret;
> +}
> +
> +static int coroutine_fn copy_sectors(BlockDriverState *bs,
> + int n_start, int n_end)
> +{
> + BDRVAddCowState *s = bs->opaque;
> + QEMUIOVector qiov;
> + struct iovec iov;
> + int n, ret;
> +
> + n = n_end - n_start;
> + if (n <= 0) {
> + return 0;
> + }
> +
> + iov.iov_len = n * BDRV_SECTOR_SIZE;
> + iov.iov_base = qemu_blockalign(bs, iov.iov_len);
> +
> + qemu_iovec_init_external(&qiov, &iov, 1);
> +
> + ret = bdrv_co_readv(bs->backing_hd, n_start, n, &qiov);
> + if (ret < 0) {
> + goto out;
> + }
> + ret = bdrv_co_writev(s->image_hd, n_start, n, &qiov);
> + if (ret < 0) {
> + goto out;
> + }
> +
> + ret = 0;
> +out:
> + qemu_vfree(iov.iov_base);
> + return ret;
> +}
> +
> +static coroutine_fn int add_cow_co_writev(BlockDriverState *bs,
> + int64_t sector_num, int remaining_sectors, QEMUIOVector *qiov)
> +{
> + BDRVAddCowState *s = bs->opaque;
> + BlockCache *c = s->bitmap_cache;
> + int ret = 0, i;
> + QEMUIOVector hd_qiov;
> + uint8_t *table;
> + uint64_t offset;
> +
> + qemu_co_mutex_lock(&s->lock);
> + qemu_iovec_init(&hd_qiov, qiov->niov);
> + ret = bdrv_co_writev(s->image_hd,
> + sector_num,
> + remaining_sectors, qiov);
alignment ^
or even at ^ if you prefer and have done in some places, just need to be
consistent about it for better readability.
> +
> + if (ret < 0) {
> + goto fail;
> + }
> + if ((s->header.features & ADD_COW_F_All_ALLOCATED) == 0) {
> + /* Copy content of unmodified sectors */
> + if (!is_cluster_head(sector_num) && !is_allocated(bs, sector_num)) {
Why do we avoid a COW when writing to the first sector of a cluster?
> + ret = copy_sectors(bs, sector_num & ~(SECTORS_PER_CLUSTER - 1),
> + sector_num);
> + if (ret < 0) {
> + goto fail;
> + }
> + }
> +
> + if (!is_cluster_tail(sector_num + remaining_sectors - 1)
> + && !is_allocated(bs, sector_num + remaining_sectors - 1)) {
> + ret = copy_sectors(bs, sector_num + remaining_sectors,
> + ((sector_num + remaining_sectors) | (SECTORS_PER_CLUSTER -
> 1)) + 1);
> + if (ret < 0) {
> + goto fail;
> + }
> + }
> +
> + for (i = sector_num / SECTORS_PER_CLUSTER;
> + i <= (sector_num + remaining_sectors - 1) / SECTORS_PER_CLUSTER;
> + i++) {
> + offset = ADD_COW_PAGE_SIZE * s->header.header_pages_size
> + + (offset_in_bitmap(i * SECTORS_PER_CLUSTER) &
> (~(c->entry_size - 1)));
> + ret = block_cache_get(bs, s->bitmap_cache, offset,
> + (void **)&table, BLOCK_TABLE_BITMAP,
> ADD_COW_CACHE_ENTRY_SIZE);
> + if (ret < 0) {
> + goto fail;
> + }
> + if ((table[i / 8] & (1 << (i % 8))) == 0) {
> + table[i / 8] |= (1 << (i % 8));
> + block_cache_entry_mark_dirty(s->bitmap_cache, table);
> + }
> + }
> + }
> + ret = 0;
> +fail:
> + qemu_co_mutex_unlock(&s->lock);
> + qemu_iovec_destroy(&hd_qiov);
> + return ret;
> +}
> +
> +static int bdrv_add_cow_truncate(BlockDriverState *bs, int64_t size)
> +{
> + BDRVAddCowState *s = bs->opaque;
> + int sector_per_byte = SECTORS_PER_CLUSTER * 8;
> + int ret;
> + uint32_t bitmap_pos = s->header.header_pages_size * ADD_COW_PAGE_SIZE;
> + int64_t bitmap_size =
> + (size / BDRV_SECTOR_SIZE + sector_per_byte - 1) / sector_per_byte;
> + bitmap_size = (bitmap_size + ADD_COW_CACHE_ENTRY_SIZE - 1)
> + & (~(ADD_COW_CACHE_ENTRY_SIZE - 1));
> +
> + ret = bdrv_truncate(bs->file, bitmap_pos + bitmap_size);
> + if (ret < 0) {
> + return ret;
> + }
> + return 0;
> +}
> +
> +static coroutine_fn int add_cow_co_flush(BlockDriverState *bs)
> +{
> + BDRVAddCowState *s = bs->opaque;
> + int ret;
> +
> + qemu_co_mutex_lock(&s->lock);
> + ret = block_cache_flush(bs, s->bitmap_cache, BLOCK_TABLE_BITMAP,
> + ADD_COW_CACHE_ENTRY_SIZE);
> + qemu_co_mutex_unlock(&s->lock);
> + return ret;
> +}
> +
> +static QEMUOptionParameter add_cow_create_options[] = {
> + {
> + .name = BLOCK_OPT_SIZE,
> + .type = OPT_SIZE,
> + .help = "Virtual disk size"
> + },
> + {
> + .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_IMAGE_FILE,
> + .type = OPT_STRING,
> + .help = "File name of a image file"
> + },
> + {
> + .name = BLOCK_OPT_IMAGE_FORMAT,
> + .type = OPT_STRING,
> + .help = "Image format of the image file"
> + },
> + { NULL }
> +};
> +
> +static BlockDriver bdrv_add_cow = {
> + .format_name = "add-cow",
> + .instance_size = sizeof(BDRVAddCowState),
> + .bdrv_probe = add_cow_probe,
> + .bdrv_open = add_cow_open,
> + .bdrv_close = add_cow_close,
> + .bdrv_create = add_cow_create,
> + .bdrv_co_readv = add_cow_co_readv,
> + .bdrv_co_writev = add_cow_co_writev,
> + .bdrv_truncate = bdrv_add_cow_truncate,
> + .bdrv_co_is_allocated = add_cow_is_allocated,
> +
> + .create_options = add_cow_create_options,
> + .bdrv_co_flush_to_os = add_cow_co_flush,
> +};
> +
> +static void bdrv_add_cow_init(void)
> +{
> + bdrv_register(&bdrv_add_cow);
> +}
> +
> +block_init(bdrv_add_cow_init);
> diff --git a/block/add-cow.h b/block/add-cow.h
> new file mode 100644
> index 0000000..f058376
> --- /dev/null
> +++ b/block/add-cow.h
> @@ -0,0 +1,85 @@
> +/*
> + * QEMU ADD-COW Disk Format
> + *
> + * Copyright IBM, Corp. 2012
> + *
> + * Authors:
> + * Dong Xu Wang <wdon...@linux.vnet.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_ADD_COW_H
> +#define BLOCK_ADD_COW_H
> +#include "block-cache.h"
> +
> +enum {
> + ADD_COW_F_All_ALLOCATED = 0X01,
Please use "ADD_COW_F_ALL_ALLOCATED" (all caps)
was searching your patch for how this was used and was scratching my
head when I wasn't seeing any matches :)
> + ADD_COW_FEATURE_MASK = ADD_COW_F_All_ALLOCATED,
> +
> + ADD_COW_MAGIC = (((uint64_t)'A' << 56) | ((uint64_t)'D' << 48) | \
> + ((uint64_t)'D' << 40) | ((uint64_t)'_' << 32) | \
> + ((uint64_t)'C' << 24) | ((uint64_t)'O' << 16) | \
> + ((uint64_t)'W' << 8) | 0xFF),
> + ADD_COW_VERSION = 1,
> + ADD_COW_FILE_LEN = 1024,
> + ADD_COW_CACHE_SIZE = 16,
> + ADD_COW_CACHE_ENTRY_SIZE = 65536,
> + ADD_COW_CLUSTER_SIZE = 65536,
> + SECTORS_PER_CLUSTER = (ADD_COW_CLUSTER_SIZE / BDRV_SECTOR_SIZE),
> + ADD_COW_PAGE_SIZE = 4096,
> + ADD_COW_DEFAULT_PAGE_SIZE = 1,
> +};
> +
> +typedef struct AddCowHeader {
> + uint64_t magic;
> + uint32_t version;
> +
> + uint32_t backing_filename_offset;
> + uint32_t backing_filename_size;
> +
> + uint32_t image_filename_offset;
> + uint32_t image_filename_size;
> +
> + uint64_t features;
> + uint64_t optional_features;
> + uint32_t header_pages_size;
> +} QEMU_PACKED AddCowHeader;
You should avoid using packed structures for image format headers.
Instead, I would either:
a) re-order the fields so that 32/64-bit fields, respectively, fall on
32/64-bit boundaries (in your case, for instance, moving header_pages_size
above features) like qed/qcow2 do, or
b) read/write the fields individually rather than reading/writing directly
into/from the header struct.
The safest route is b). Adds a few lines of code, but you won't have to
re-work things (or worry about introducing bugs) later if you were to add,
say, a 32-bit value, and then a 64-bit value later.
> +
> +typedef struct BDRVAddCowState {
> + BlockDriverState *image_hd;
> + CoMutex lock;
> + int cluster_size;
> + BlockCache *bitmap_cache;
> + uint64_t bitmap_size;
> + AddCowHeader header;
> + char backing_file_format[16];
> + char image_file_format[16];
> +} BDRVAddCowState;
> +
> +/* Convert sector_num to offset in bitmap */
> +static inline int64_t offset_in_bitmap(int64_t sector_num)
> +{
> + int64_t cluster_num = sector_num / SECTORS_PER_CLUSTER;
> + return cluster_num / 8;
> +}
> +
> +static inline bool is_cluster_head(int64_t sector_num)
> +{
> + return sector_num % SECTORS_PER_CLUSTER == 0;
> +}
> +
> +static inline bool is_cluster_tail(int64_t sector_num)
> +{
> + return (sector_num + 1) % SECTORS_PER_CLUSTER == 0;
> +}
> +
> +BlockCache *add_cow_cache_create(BlockDriverState *bs, int num_tables);
> +int add_cow_cache_destroy(BlockDriverState *bs, BlockCache *c);
> +void add_cow_cache_entry_mark_dirty(BlockCache *c, void *table);
> +int add_cow_cache_get(BlockDriverState *bs, BlockCache *c, uint64_t offset,
> + void **table);
> +int add_cow_cache_flush(BlockDriverState *bs, BlockCache *c);
> +#endif
> diff --git a/block_int.h b/block_int.h
> index 6c1d9ca..67954ec 100644
> --- a/block_int.h
> +++ b/block_int.h
> @@ -53,6 +53,8 @@
> #define BLOCK_OPT_SUBFMT "subformat"
> #define BLOCK_OPT_COMPAT_LEVEL "compat"
> #define BLOCK_OPT_LAZY_REFCOUNTS "lazy_refcounts"
> +#define BLOCK_OPT_IMAGE_FILE "image_file"
> +#define BLOCK_OPT_IMAGE_FORMAT "image_format"
>
> typedef struct BdrvTrackedRequest BdrvTrackedRequest;
>
> --
> 1.7.1
>
>
