Re: [Qemu-devel] [PATCH V18 5/6] add-cow file format core code.

[Jeff Cody <jcody@redhat.com>]

On Wed, Apr 10, 2013 at 04:11:52PM +0800, Dong Xu Wang wrote:
> add-cow file format core code. It use block-cache.c as cache code.
> It lacks of snapshot_blkdev support.
> 
> Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
> ---
> v17-v18:
> 1) use error_report, not fprintf.
> 2) remove version field from header.
> 3) header_size is MAX(cluster_size, 4096).
> 4) introduce s->cluster_sectors.
> 5) use BLKDBG_L2_LOAD/UPDATE.
> 
> v16->v17:
> 1) Use stringify.
> 
> v15->v16:
> 1) Judge if opts is null in add_cow_create function.
>  block/Makefile.objs       |   1 +
>  block/add-cow.c           | 741 ++++++++++++++++++++++++++++++++++++++++++++++
>  block/block-cache.c       |   4 +-
>  block/qcow2.h             |   6 +-
>  include/block/block_int.h |   2 +
>  5 files changed, 749 insertions(+), 5 deletions(-)
>  create mode 100644 block/add-cow.c
> 
> diff --git a/block/Makefile.objs b/block/Makefile.objs
> index 4fe81dc..69cbb09 100644
> --- a/block/Makefile.objs
> +++ b/block/Makefile.objs
> @@ -1,6 +1,7 @@
>  block-obj-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vvfat.o
>  block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o
>  block-obj-y += block-cache.o
> +block-obj-y += add-cow.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 += parallels.o blkdebug.o blkverify.o
> diff --git a/block/add-cow.c b/block/add-cow.c
> new file mode 100644
> index 0000000..904b008
> --- /dev/null
> +++ b/block/add-cow.c
> @@ -0,0 +1,741 @@
> +/*
> + * QEMU ADD-COW Disk Format
> + *
> + * Copyright IBM, Corp. 2012
> + *
> + * Authors:
> + *  Dong Xu Wang <wdongxu@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/block_int.h"
> +#include "qemu/module.h"
> +#include "block/block-cache.h"
> +
> +#define ACOW_CLUSTER_SIZE 65536
> +enum {
> +    /* compat_features bit */
> +    ACOW_F_ALL_ALLOCATED    = 0X01,
> +
> +    /* none feature bit used now */
> +    ACOW_FEATURE_MASK       = 0,
> +
> +    ACOW_MAGIC              = 'A' | 'C' << 8 | 'O' << 16 | 'W' << 24,
> +    ACOW_CACHE_SIZE         = 16,
> +    DEFAULT_HEADER_SIZE    = 4096,
> +    MIN_CLUSTER_BITS            = 9,
> +    MAX_CLUSTER_BITS            = 21,
> +};
> +
> +typedef struct AddCowHeader {
> +    uint32_t    magic;
> +
> +    uint32_t    backing_offset;
> +    uint32_t    backing_size;
> +    uint32_t    image_offset;
> +    uint32_t    image_size;
> +
> +    uint32_t    cluster_bits;
> +    uint64_t    features;
> +    uint64_t    compat_features;
> +    uint32_t    header_size;
> +
> +    char        backing_fmt[16];
> +    char        image_fmt[16];
> +} QEMU_PACKED AddCowHeader;
> +
> +typedef struct BDRVAddCowState {
> +    BlockDriverState    *image_hd;
> +    CoMutex             lock;
> +    int                 cluster_size;
> +    int                 cluster_sectors;
> +    BlockCache          *bitmap_cache;
> +    uint64_t            bitmap_size;
> +    AddCowHeader        header;
> +    char                backing_fmt[16];
> +    char                image_fmt[16];
> +} BDRVAddCowState;
> +
> +/* Convert sector_num to offset in bitmap */
> +static inline int64_t offset_in_bitmap(int64_t sector_num,
> +                                       int64_t cluster_sectors)
> +{
> +    int64_t cluster_num = sector_num / cluster_sectors;
> +    return cluster_num / 8;
> +}
> +
> +static inline bool is_cluster_head(int64_t sector_num,
> +                                   int64_t cluster_sectors)
> +{
> +    return sector_num % cluster_sectors == 0;
> +}
> +
> +static inline bool is_cluster_tail(int64_t sector_num,
> +                                   int64_t cluster_sectors)
> +{
> +    return (sector_num + 1) % cluster_sectors == 0;
> +}
> +
> +static void add_cow_header_le_to_cpu(const AddCowHeader *le, AddCowHeader *cpu)
> +{
> +    cpu->magic              = le32_to_cpu(le->magic);
> +
> +    cpu->backing_offset     = le32_to_cpu(le->backing_offset);
> +    cpu->backing_size       = le32_to_cpu(le->backing_size);
> +    cpu->image_offset       = le32_to_cpu(le->image_offset);
> +    cpu->image_size         = le32_to_cpu(le->image_size);
> +
> +    cpu->cluster_bits       = le32_to_cpu(le->cluster_bits);
> +    cpu->features           = le64_to_cpu(le->features);
> +    cpu->compat_features    = le64_to_cpu(le->compat_features);
> +    cpu->header_size        = le32_to_cpu(le->header_size);
> +
> +    memcpy(cpu->backing_fmt, le->backing_fmt, sizeof(cpu->backing_fmt));
> +    memcpy(cpu->image_fmt, le->image_fmt, sizeof(cpu->image_fmt));
> +}
> +
> +static void add_cow_header_cpu_to_le(const AddCowHeader *cpu, AddCowHeader *le)
> +{
> +    le->magic               = cpu_to_le32(cpu->magic);
> +
> +    le->backing_offset      = cpu_to_le32(cpu->backing_offset);
> +    le->backing_size        = cpu_to_le32(cpu->backing_size);
> +    le->image_offset        = cpu_to_le32(cpu->image_offset);
> +    le->image_size          = cpu_to_le32(cpu->image_size);
> +
> +    le->cluster_bits        = cpu_to_le32(cpu->cluster_bits);
> +    le->features            = cpu_to_le64(cpu->features);
> +    le->compat_features     = cpu_to_le64(cpu->compat_features);
> +    le->header_size         = cpu_to_le32(cpu->header_size);
> +    memcpy(le->backing_fmt, cpu->backing_fmt, sizeof(le->backing_fmt));
> +    memcpy(le->image_fmt, cpu->image_fmt, sizeof(le->image_fmt));
> +}
> +
> +static int add_cow_probe(const uint8_t *buf, int buf_size, const char *filename)
> +{
> +    const AddCowHeader *header = (const AddCowHeader *)buf;
> +
> +    if (buf_size < sizeof(*header)) {
> +        return 0;
> +    }
> +    if (le32_to_cpu(header->magic) == ACOW_MAGIC) {
> +        return 100;
> +    }
> +    return 0;
> +}
> +
> +static int add_cow_create(const char *filename, QemuOpts *opts)
> +{
> +    AddCowHeader header = {
> +        .magic      = ACOW_MAGIC,
> +        .features   = 0,
> +        .compat_features = 0,
> +    };
> +    AddCowHeader le_header;
> +    int64_t image_len = 0;
> +    const char *backing_filename = NULL, *backing_fmt = NULL;
> +    const char *image_filename = NULL, *image_format = NULL;
> +    size_t cluster_size = ACOW_CLUSTER_SIZE;
> +    BlockDriverState *bs, *backing_bs;
> +    BlockDriver *drv = bdrv_find_format("add-cow");
> +    int ret;
> +
> +    image_len = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 0);
> +    backing_filename = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
> +    backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
> +    image_filename = qemu_opt_get(opts, BLOCK_OPT_IMAGE_FILE);
> +    image_format = qemu_opt_get(opts, BLOCK_OPT_IMAGE_FMT);
> +    cluster_size = qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE,
> +                                     ACOW_CLUSTER_SIZE);
> +
> +    header.cluster_bits = ffs(cluster_size) - 1;
> +    if (header.cluster_bits < MIN_CLUSTER_BITS ||
> +        header.cluster_bits > MAX_CLUSTER_BITS ||
> +        (1 << header.cluster_bits) != cluster_size) {
> +        error_report(
> +            "Cluster size must be a power of two between %d and %dk",
> +            1 << MIN_CLUSTER_BITS, 1 << (MAX_CLUSTER_BITS - 10));
> +        return -EINVAL;
> +    }
> +
> +   header.header_size = MAX(cluster_size, DEFAULT_HEADER_SIZE);
> +    if (backing_filename) {
> +        header.backing_offset = sizeof(header);
> +        header.backing_size = strlen(backing_filename);
> +
> +        if (!backing_fmt) {
> +            backing_bs = bdrv_new("image");
> +            ret = bdrv_open(backing_bs, backing_filename, NULL,
> +                            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.compat_features |= ACOW_F_ALL_ALLOCATED;
> +    }
> +
> +    if (image_filename) {
> +        header.image_offset = sizeof(header) + header.backing_size;
> +        header.image_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_offset + header.image_size > header.header_size) {
> +        error_report("image_file name or backing_file name too long.");
> +        return -ENOSPC;
> +    }
> +
> +    ret = bdrv_file_open(&bs, image_filename, NULL, 0);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +    bdrv_close(bs);
> +
> +    ret = bdrv_create_file(filename, NULL);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +
> +    ret = bdrv_file_open(&bs, filename, NULL, BDRV_O_RDWR);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +    snprintf(header.backing_fmt, sizeof(header.backing_fmt), "%s",
> +             backing_fmt ? backing_fmt : "");
> +    snprintf(header.image_fmt, sizeof(header.image_fmt), "%s",
> +             image_format ? image_format : "raw");
> +    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, header.image_offset, image_filename,
> +                      header.image_size);
> +    if (ret < 0) {
> +        bdrv_delete(bs);
> +        return ret;
> +    }
> +
> +    if (backing_filename) {
> +        ret = bdrv_pwrite(bs, header.backing_offset, backing_filename,
> +                          header.backing_size);
> +        if (ret < 0) {
> +            bdrv_delete(bs);
> +            return ret;
> +        }
> +    }
> +    bdrv_close(bs);
> +
> +    ret = bdrv_open(bs, filename, NULL, 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, QDict *options, int flags)
> +{
> +    char                image_filename[PATH_MAX];
> +    char                tmp_name[PATH_MAX];
> +    int                 ret;
> +    int                 sector_per_byte;
> +    BDRVAddCowState     *s = bs->opaque;
> +    AddCowHeader        le_header;
> +    char backing_filename[PATH_MAX];
> +
> +    ret = bdrv_pread(bs->file, 0, &le_header, sizeof(le_header));
> +    if (ret < 0) {
> +        goto fail;
> +    }
> +
> +    add_cow_header_le_to_cpu(&le_header, &s->header);
> +
> +    if (s->header.magic != ACOW_MAGIC) {
> +        ret = -EINVAL;
> +        goto fail;
> +    }
> +
> +    if (s->header.features & ~ACOW_FEATURE_MASK) {
> +        char buf[64];
> +        snprintf(buf, sizeof(buf), "Feature Flags: %" PRIx64,
> +                 s->header.features & ~ACOW_FEATURE_MASK);
> +        qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE,
> +                      bs->device_name, "add-cow", buf);
> +        return -ENOTSUP;
> +    }
> +
> +    if ((s->header.compat_features & ACOW_F_ALL_ALLOCATED) == 0) {
> +        snprintf(bs->backing_format, sizeof(bs->backing_format),
> +                 "%s", s->header.backing_fmt);
> +    }
> +
> +    if (s->header.cluster_bits < MIN_CLUSTER_BITS ||
> +        s->header.cluster_bits > MAX_CLUSTER_BITS) {
> +        ret = -EINVAL;
> +        goto fail;
> +    }
> +
> +    s->cluster_size = 1 << s->header.cluster_bits;
> +    if (s->header.header_size != MAX(s->cluster_size, DEFAULT_HEADER_SIZE)) {
> +        char buf[64];
> +        snprintf(buf, sizeof(buf), "Header size: %d",
> +                 s->header.header_size);
> +        qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE,
> +                      bs->device_name, "add-cow", buf);
> +        return -ENOTSUP;
> +    }
> +
> +    if ((s->header.compat_features & ACOW_F_ALL_ALLOCATED) == 0) {
> +        ret = bdrv_read_string(bs->file, s->header.backing_offset,
> +                               s->header.backing_size,
> +                               bs->backing_file,
> +                               sizeof(bs->backing_file));
> +        if (ret < 0) {
> +            goto fail;
> +        }
> +    }
> +
> +    ret = bdrv_read_string(bs->file, s->header.image_offset,
> +                           s->header.image_size, tmp_name,
> +                           sizeof(tmp_name));
> +    if (ret < 0) {
> +        goto fail;
> +    }
> +
> +    if (path_has_protocol(tmp_name)) {
> +        pstrcpy(image_filename, sizeof(image_filename), tmp_name);
> +    } else {
> +        path_combine(image_filename, sizeof(image_filename),
> +                     bs->filename, tmp_name);
> +    }
> +    bdrv_get_full_backing_filename(bs, backing_filename,
> +                                   sizeof(backing_filename));
> +    if (!strcmp(backing_filename, image_filename)) {
> +        error_report("Error: backing file and image file are same: %s\n",
> +                     backing_filename);
> +        ret = EINVAL;
> +        goto fail;
> +    }
> +    s->image_hd = bdrv_new("");
> +    ret = bdrv_open(s->image_hd, image_filename, NULL, flags,
> +                    bdrv_find_format(s->header.image_fmt));
> +    if (ret < 0) {
> +        bdrv_delete(s->image_hd);
> +        goto fail;
> +    }
> +
> +    bs->total_sectors = bdrv_getlength(s->image_hd) / BDRV_SECTOR_SIZE;
> +    s->cluster_sectors = s->cluster_size / BDRV_SECTOR_SIZE;
> +    sector_per_byte = s->cluster_sectors * 8;
> +    s->bitmap_size =
> +        (bs->total_sectors + sector_per_byte - 1) / sector_per_byte;
> +    s->bitmap_cache =  block_cache_create(bs, ACOW_CACHE_SIZE,
> +                                          s->cluster_size,
> +                                          BLOCK_TABLE_BITMAP);
> +    qemu_co_mutex_init(&s->lock);
> +    return 0;
> +fail:
> +    return ret;
> +}
> +
> +static void add_cow_close(BlockDriverState *bs)
> +{
> +    BDRVAddCowState *s = bs->opaque;
> +    if (s->bitmap_cache) {
> +        block_cache_destroy(bs, s->bitmap_cache);
> +    }
> +    bdrv_delete(s->image_hd);
> +}
> +
> +static bool is_allocated(BlockDriverState *bs, int64_t sector_num)
> +{
> +    BDRVAddCowState *s  = bs->opaque;
> +    int64_t cluster_num = sector_num / s->cluster_sectors;
> +    uint8_t *table      = NULL;
> +    bool val = false;
> +    int ret;
> +
> +    uint64_t offset = s->header.header_size +
> +        (offset_in_bitmap(sector_num, s->cluster_sectors)
> +            & (~(s->cluster_size - 1)));
> +    ret = block_cache_get(bs, s->bitmap_cache, offset, (void **)&table);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +
> +    val = table[cluster_num / 8 % s->cluster_size] & (1 << (cluster_num % 8));
> +    ret = block_cache_put(bs, s->bitmap_cache, (void **)&table);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +    return val;
> +}
> +
> +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.compat_features & ACOW_F_ALL_ALLOCATED) {
> +        *num_same = nb_sectors;
> +        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 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,
> +                                 &cur_nr_sectors)) {
> +            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,
> +                                cur_nr_sectors, &hd_qiov);
> +            qemu_co_mutex_lock(&s->lock);
> +            if (ret < 0) {
> +                goto fail;
> +            }
> +        } else {
> +            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,
> +                                        cur_nr_sectors, &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;
> +    int ret = 0, i;
> +    QEMUIOVector hd_qiov;
> +    uint8_t *table;
> +    uint64_t offset;
> +    int mask = s->cluster_sectors - 1;
> +    int cluster_mask = s->cluster_size - 1;
> +
> +    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);
> +
> +    if (ret < 0) {
> +        goto fail;
> +    }
> +    if ((s->header.compat_features & ACOW_F_ALL_ALLOCATED) == 0) {
> +        /* Copy content of unmodified sectors */
> +        if (!is_cluster_head(sector_num, s->cluster_sectors)
> +            && !is_allocated(bs, sector_num)) {
> +            ret = copy_sectors(bs, sector_num & ~mask, sector_num);
> +            if (ret < 0) {
> +                goto fail;
> +            }
> +        }
> +
> +        if (!is_cluster_tail(sector_num + remaining_sectors - 1,
> +                             s->cluster_sectors)
> +            && !is_allocated(bs, sector_num + remaining_sectors - 1)) {
> +            ret = copy_sectors(bs, sector_num + remaining_sectors,
> +                               ((sector_num + remaining_sectors) | mask) + 1);
> +            if (ret < 0) {
> +                goto fail;
> +            }
> +        }
> +
> +        for (i = sector_num / s->cluster_sectors;
> +            i <= (sector_num + remaining_sectors - 1) / s->cluster_sectors;
> +            i++) {
> +            offset = s->header.header_size
> +                + (offset_in_bitmap(i * s->cluster_sectors,
> +                s->cluster_sectors) & (~cluster_mask));
> +            ret = block_cache_get(bs, s->bitmap_cache, offset, (void **)&table);
> +            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 = block_cache_put(bs, s->bitmap_cache, (void **) &table);
> +            if (ret < 0) {
> +                goto fail;
> +            }
> +        }
> +    }
> +    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 = s->cluster_sectors * 8;
> +    int ret;
> +    int64_t bitmap_size =
> +        (size / BDRV_SECTOR_SIZE + sector_per_byte - 1) / sector_per_byte;
> +    bitmap_size = (bitmap_size + s->cluster_size - 1)
> +        & (~(s->cluster_size - 1));
> +
> +    ret = bdrv_truncate(bs->file, s->header.header_size + bitmap_size);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +
> +    ret = bdrv_truncate(s->image_hd, size);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +    return 0;
> +}
> +
> +static int add_cow_reopen_prepare(BDRVReopenState *state,
> +                                  BlockReopenQueue *queue, Error **errp)
> +{
> +    BDRVAddCowState *s;
> +    int ret = -1;
> +
> +    assert(state != NULL);
> +    assert(state->bs != NULL);
> +
> +    if (queue == NULL) {
> +        error_set(errp, ERROR_CLASS_GENERIC_ERROR,
> +                  "No reopen queue for add-cow");
> +        goto exit;
> +    }
> +
> +    s = state->bs->opaque;
> +
> +    assert(s != NULL);
> +
> +
> +    bdrv_reopen_queue(queue, s->image_hd, state->flags);
> +    ret = 0;
> +
> +exit:
> +    return ret;
> +}
> +
> +
> +static coroutine_fn int add_cow_co_flush(BlockDriverState *bs)
> +{
> +    BDRVAddCowState *s = bs->opaque;
> +    int ret;
> +
> +    qemu_co_mutex_lock(&s->lock);
> +    if (s->bitmap_cache) {
> +        ret = block_cache_flush(bs, s->bitmap_cache);
> +        if (ret < 0) {
> +            return ret;
> +        }
> +    }
> +    ret = bdrv_flush(s->image_hd);
> +    qemu_co_mutex_unlock(&s->lock);
> +    return ret;
> +}
> +
> +static int add_cow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
> +{
> +    BDRVAddCowState *s = bs->opaque;
> +    bdi->cluster_size = s->cluster_size;
> +    return 0;
> +}
> +
> +static QemuOptsList add_cow_create_opts = {
> +    .name = "add-cow-create-opts",
> +    .head = QTAILQ_HEAD_INITIALIZER(add_cow_create_opts.head),
> +    .desc = {
> +        {
> +            .name = BLOCK_OPT_SIZE,
> +            .type = QEMU_OPT_SIZE,
> +            .help = "Virtual disk size"
> +        },
> +        {
> +            .name = BLOCK_OPT_BACKING_FILE,
> +            .type = QEMU_OPT_STRING,
> +            .help = "File name of a base image"
> +        },
> +        {
> +            .name = BLOCK_OPT_BACKING_FMT,
> +            .type = QEMU_OPT_STRING,
> +            .help = "Image format of the base image"
> +        },
> +        {
> +            .name = BLOCK_OPT_IMAGE_FILE,
> +            .type = QEMU_OPT_STRING,
> +            .help = "File name of a image file"
> +        },
> +        {
> +            .name = BLOCK_OPT_IMAGE_FMT,
> +            .type = QEMU_OPT_STRING,
> +            .help = "Image format of the image file"
> +        },
> +        {
> +            .name = BLOCK_OPT_CLUSTER_SIZE,
> +            .type = QEMU_OPT_SIZE,
> +            .help = "add-cow cluster size",
> +            .def_value_str = stringify(ACOW_CLUSTER_SIZE)

Hi Dong,

.def_value_str is undefined - it looks like this series is dependent
on:

[PATCH V14 1/6] add def_value_str in QemuOptDesc struct and rewrite qemu_opts_print

In that 6-part series, patches 2,4,5 are also dependent on the above
patch.  Should these series be combined?

You did mention in the header that this uses QemuOpts, but until I
applied and tried compiling, it wasn't obvious (at least to me) the
external patch dependency above.

Thanks,
Jeff


> +        },
> +        { /* end of list */ }
> +    }
> +};
> +
> +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,
> +    .bdrv_reopen_prepare        = add_cow_reopen_prepare,
> +    .bdrv_get_info              = add_cow_get_info,
> +
> +    .bdrv_create_opts           = &add_cow_create_opts,
> +    .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/block-cache.c b/block/block-cache.c
> index 3544691..4824632 100644
> --- a/block/block-cache.c
> +++ b/block/block-cache.c
> @@ -130,7 +130,7 @@ static int block_cache_entry_flush(BlockDriverState *bs, BlockCache *c, int i)
>      } else if (c->table_type == BLOCK_TABLE_L2) {
>          BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE);
>      } else if (c->table_type == BLOCK_TABLE_BITMAP) {
> -        BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE);
> +        BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD);
>      }
>  
>      ret = bdrv_pwrite(bs->file, c->entries[i].offset,
> @@ -265,7 +265,7 @@ static int block_cache_do_get(BlockDriverState *bs, BlockCache *c,
>          if (c->table_type == BLOCK_TABLE_L2) {
>              BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD);
>          } else if (c->table_type == BLOCK_TABLE_BITMAP) {
> -            BLKDBG_EVENT(bs->file, BLKDBG_COW_READ);
> +            BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD);
>          }
>  
>          ret = bdrv_pread(bs->file, offset, c->entries[i].table,
> diff --git a/block/qcow2.h b/block/qcow2.h
> index e7f6aec..a4e514b 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -98,6 +98,9 @@ typedef struct QCowSnapshot {
>      uint64_t vm_clock_nsec;
>  } QCowSnapshot;
>  
> +struct BlockCache;
> +typedef struct BlockCache BlockCache;
> +
>  typedef struct Qcow2UnknownHeaderExtension {
>      uint32_t magic;
>      uint32_t len;
> @@ -389,7 +392,4 @@ int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name);
>  void qcow2_free_snapshots(BlockDriverState *bs);
>  int qcow2_read_snapshots(BlockDriverState *bs);
>  
> -/* qcow2-cache.c functions */
> -
> -
>  #endif
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index a44a9ac..b9eb9b8 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -57,6 +57,8 @@
>  #define BLOCK_OPT_COMPAT_LEVEL      "compat"
>  #define BLOCK_OPT_LAZY_REFCOUNTS    "lazy_refcounts"
>  #define BLOCK_OPT_ADAPTER_TYPE      "adapter_type"
> +#define BLOCK_OPT_IMAGE_FILE        "image_file"
> +#define BLOCK_OPT_IMAGE_FMT         "image_fmt"
>  
>  typedef struct BdrvTrackedRequest BdrvTrackedRequest;
>  
> -- 
> 1.7.11.7
> 
>