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Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type
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From: |
Charles Arnold |
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Subject: |
Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type |
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Date: |
Wed, 01 Feb 2012 09:51:22 -0700 |
>>> On 2/1/2012 at 05:15 AM, in message <address@hidden>, Kevin Wolf
<address@hidden> wrote:
> Am 01.02.2012 00:04, schrieb Charles Arnold:
>> Thanks Andreas,
>>
>> The 'TODO uuid is missing' comment in the patch is from the
>> original sources (as well as many '//' comments). The vhd footer
>> and header data structures contain a field for a UUID but no code
>> was ever developed to generate one.
>> The revised patch is below after running scripts/checkpatch.pl and
>> fixing the 32 bit issues.
>>
>> - Charles
>>
>>
>> The Virtual Hard Disk Image Format Specification allows for three
>> types of hard disk formats, Fixed, Dynamic, and Differencing. Qemu
>> currently only supports Dynamic disks. This patch adds support for
>> the Fixed Disk format.
>>
>> Usage:
>> Example 1: qemu-img create -f vpc -o type=fixed <filename> [size]
>> Example 2: qemu-img convert -O vpc -o type=fixed <input filename>
>> <output
> filename>
>>
>> While it is also allowed to specify '-o type=dynamic', the default disk type
>> remains Dynamic and is what is used when the type is left unspecified.
>>
>> Signed-off-by: Charles Arnold <address@hidden>
>
> You have a lot of trailing whitespace in your patch, to the extent that
> the patch is corrupted:
>
> error: block/vpc.c : does not exist in
> index
>
> Please consider using git send-email.
Sorry about that.
>
>>
>> diff --git a/block/vpc.c b/block/vpc.c
>> index 89a5ee2..04db372 100644
>> --- a/block/vpc.c
>> +++ b/block/vpc.c
>> @@ -160,14 +160,25 @@ static int vpc_open(BlockDriverState *bs, int flags)
>> struct vhd_dyndisk_header* dyndisk_header;
>> uint8_t buf[HEADER_SIZE];
>> uint32_t checksum;
>> + int disk_type = VHD_DYNAMIC;
>> int err = -1;
>>
>> if (bdrv_pread(bs->file, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
>> goto fail;
>>
>> footer = (struct vhd_footer*) s->footer_buf;
>> - if (strncmp(footer->creator, "conectix", 8))
>> - goto fail;
>> + if (strncmp(footer->creator, "conectix", 8)) {
>> + int64_t offset = bdrv_getlength(bs->file);
>
> bdrv_getlength can fail.
Ok, I'll fix this.
>
>> + /* If a fixed disk, the footer is found only at the end of the file
> */
>> + if (bdrv_pread(bs->file, offset-HEADER_SIZE, s->footer_buf,
>> HEADER_SIZE)
>> + != HEADER_SIZE) {
>
>> + goto fail;
>
>> + }
>
>> + if (strncmp(footer->creator, "conectix", 8)) {
>>
>
>> + goto fail;
>
>> + }
>
>> + disk_type = VHD_FIXED;
>
>> + }
>
>>
>
>> checksum = be32_to_cpu(footer->checksum);
>>
>
>> footer->checksum = 0;
>>
>
>> @@ -186,6 +197,14 @@ static int vpc_open(BlockDriverState *bs, int flags)
>>
>
>> goto fail;
>
>> }
>
>>
>
>> + /* The footer is all that is needed for fixed disks */
>
>> + if (disk_type == VHD_FIXED) {
>
>> + /* The fixed disk format doesn't use footer->data_offset but it
>>
>
>> + should be initialized */
>
>> + footer->data_offset = be64_to_cpu(0xFFFFFFFFFFFFFFFFULL);
>>
>
>
> Why should it be changed? s->footer_buf is only used for updating the
> footer, so you will change the value that is in the image file.
The spec states the following about the data_offset field in the footer,
"This field is used for dynamic disks and differencing disks,
but not fixed disks. For fixed disks, this field should be set to 0xFFFFFFFF."
(Windows initializes all 8 bytes of the field)
>
>> + return 0;
>
> This leaves most of BDRVVPCState uninitialised. I can't imagine how
> bdrv_read/write could possibly work with an image in this state.
>
> Something essential seems to be missing here.
If vpc_open is opening a fixed disk, there is no dynamic disk header from
which to acquire information for filling out the BDRVVPCState structure.
However, you are right about the read/write code likely not working with
the structure left uninitialised. I'll look into what needs to be done here.
>
>> + }
>
>> +
>
>> if (bdrv_pread(bs->file, be64_to_cpu(footer->data_offset), buf,
> HEADER_SIZE)
>> != HEADER_SIZE)
>
>> goto fail;
>
>> @@ -533,10 +552,10 @@ static int calculate_geometry(int64_t total_sectors,
> uint16_t* cyls,
>> return 0;
>
>> }
>
>>
>
>> -static int vpc_create(const char *filename, QEMUOptionParameter *options)
>>
>
>> +static int vpc_create_dynamic_disk(const char *filename, int64_t
> total_size)
>> {
>
>> uint8_t buf[1024];
>
>> - struct vhd_footer* footer = (struct vhd_footer*) buf;
>>
>
>> + struct vhd_footer* footer = (struct vhd_footer *) buf;
>
>
> Don't reformat existing code.
Even if scripts/checkpatch.pl complains?
What is the policy here if a patch contains changes that are within 3 lines
of existing code that doesn't follow the style guidelines?
>
>> struct vhd_dyndisk_header* dyndisk_header =
>
>> (struct vhd_dyndisk_header*) buf;
>
>> int fd, i;
>
>> @@ -544,13 +563,9 @@ static int vpc_create(const char *filename,
> QEMUOptionParameter *options)
>> uint8_t heads = 0;
>
>> uint8_t secs_per_cyl = 0;
>
>> size_t block_size, num_bat_entries;
>
>> - int64_t total_sectors = 0;
>>
>
>> + int64_t total_sectors = total_size / BDRV_SECTOR_SIZE;
>
>> int ret = -EIO;
>>
>
>>
>
>> - // Read out options
>>
>
>> - total_sectors = get_option_parameter(options, BLOCK_OPT_SIZE)->value.n
>> /
>
>> - BDRV_SECTOR_SIZE;
>>
>
>> -
>>
>
>> // Create the file
>
>> fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
>
>> if (fd < 0)
>>
>
>> @@ -657,6 +672,101 @@ static int vpc_create(const char *filename,
> QEMUOptionParameter *options)
>> return ret;
>
>> }
>
>>
>
>> +static int vpc_create_fixed_disk(const char *filename, int64_t total_size)
>
>> +{
>
>> + uint8_t buf[1024];
>
>> + struct vhd_footer* footer = (struct vhd_footer *) buf;
>
>> + int fd;
>
>> + uint16_t cyls = 0;
>
>> + uint8_t heads = 0;
>
>> + uint8_t secs_per_cyl = 0;
>
>> + int64_t total_sectors = total_size / BDRV_SECTOR_SIZE;
>
>> + int ret = -EIO;
>>
>
>> +
>
>> + /* Create the file */
>
>> + fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
>
>> + if (fd < 0) {
>>
>
>> + return -EIO;
>>
>
>> + }
>
>> +
>
>> + /* Calculate matching total_size and geometry. */
>
>> + if (calculate_geometry(total_sectors, &cyls, &heads, &secs_per_cyl)) {
>>
>
>> + ret = -EFBIG;
>>
>
>> + goto fail;
>
>> + }
>
>> + total_sectors = (int64_t) cyls * heads * secs_per_cyl;
>
>> +
>
>> + /* Prepare the Hard Disk Footer */
>
>> + memset(buf, 0, 1024);
>
>> +
>
>> + memcpy(footer->creator, "conectix", 8);
>>
>
>> + /* TODO Check if "qemu" creator_app is ok for VPC */
>
>> + memcpy(footer->creator_app, "qemu", 4);
>>
>
>> + memcpy(footer->creator_os, "Wi2k", 4);
>>
>
>> +
>
>> + footer->features = be32_to_cpu(0x02);
>>
>
>> + footer->version = be32_to_cpu(0x00010000);
>>
>
>> + footer->data_offset = be64_to_cpu(0xFFFFFFFFFFFFFFFFULL);
>>
>
>> + footer->timestamp = be32_to_cpu(time(NULL) - VHD_TIMESTAMP_BASE);
>>
>
>> +
>
>> + /* Version of Virtual PC 2007 */
>
>> + footer->major = be16_to_cpu(0x0005);
>>
>
>> + footer->minor = be16_to_cpu(0x0003);
>>
>
>> + footer->orig_size = be64_to_cpu(total_size);
>>
>
>> + footer->size = be64_to_cpu(total_size);
>>
>
>> + footer->cyls = be16_to_cpu(cyls);
>>
>
>> + footer->heads = heads;
>>
>
>> + footer->secs_per_cyl = secs_per_cyl;
>>
>
>> +
>
>> + footer->type = be32_to_cpu(VHD_FIXED);
>>
>
>> +
>
>> + /* TODO uuid is missing */
>
>> +
>
>> + footer->checksum = be32_to_cpu(vpc_checksum(buf, HEADER_SIZE));
>>
>
>> +
>
>> + total_size += 512;
>
>> + if (ftruncate(fd, total_size) != 0) {
>
>> + ret = -errno;
>>
>
>> + goto fail;
>
>> + }
>
>> + if (lseek(fd, -512, SEEK_END) < 0) {
>>
>
>> + goto fail;
>
>> + }
>
>> + if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE) {
>> + goto fail;
>> + }
>> +
>> + ret = 0;
>> +
>> + fail:
>> + close(fd);
>> + return ret;
>> +}
>
> This is a lot of duplication. You should be able to share some code with
> vpc_create_dynamic.
Yes, I noticed that. My original work just created a flag that was used in the
original
vpc_create without splitting out two additional functions.
Perhaps I should have kept my original approach.
>
>> +
>> +static int vpc_create(const char *filename, QEMUOptionParameter *options)
>> +{
>> + int64_t total_size = 0;
>> + QEMUOptionParameter *disk_type_param;
>> + int ret = -EIO;
>
> This value is unused, and -EIO wouldn't really make sense. Better leave
> it uninitialised here and let the compiler warn if some case doesn't
> change ret.
Ok.
>
>> +
>> + /* Read out options */
>> + total_size = get_option_parameter(options, BLOCK_OPT_SIZE)->value.n;
>> +
>> + disk_type_param = get_option_parameter(options, BLOCK_OPT_TYPE);
>> + if (disk_type_param && disk_type_param->value.s) {
>> + if (!strcmp(disk_type_param->value.s, "dynamic")) {
>> + ret = vpc_create_dynamic_disk(filename, total_size);
>> + } else if (!strcmp(disk_type_param->value.s, "fixed")) {
>> + ret = vpc_create_fixed_disk(filename, total_size);
>> + } else {
>> + ret = -EINVAL;
>> + }
>> + } else {
>> + ret = vpc_create_dynamic_disk(filename, total_size);
>> + }
>> + return ret;
>> +}
>> +
>> static void vpc_close(BlockDriverState *bs)
>> {
>> BDRVVPCState *s = bs->opaque;
>> @@ -675,6 +785,13 @@ static QEMUOptionParameter vpc_create_options[] = {
>> .type = OPT_SIZE,
>> .help = "Virtual disk size"
>> },
>> + {
>> + .name = BLOCK_OPT_TYPE,
>> + .type = OPT_STRING,
>> + .help =
>> + "Type of virtual hard disk format. Supported formats are "
>> + "{dynamic (default) | fixed} "
>> + },
>> { NULL }
>> };
>>
>> diff --git a/block_int.h b/block_int.h
>> index 311bd2a..6d6cc96 100644
>> --- a/block_int.h
>> +++ b/block_int.h
>> @@ -50,6 +50,7 @@
>> #define BLOCK_OPT_TABLE_SIZE "table_size"
>> #define BLOCK_OPT_PREALLOC "preallocation"
>> #define BLOCK_OPT_SUBFMT "subformat"
>> +#define BLOCK_OPT_TYPE "type"
>
> Looks like BLOCK_OPT_SUBFMT could be reused.
Sure, if that is the preferred option.
>
> Kevin
Thanks for taking the time to review the patch. I'll rework it and send it out
again.
- Charles
- Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type, Kevin Wolf, 2012/02/01
- Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type,
Charles Arnold <=
- Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type, Stefan Weil, 2012/02/01
- Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type, Kevin Wolf, 2012/02/02
- Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type, Charles Arnold, 2012/02/02
- Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type, Kevin Wolf, 2012/02/06
- Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type, Charles Arnold, 2012/02/06
- Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type, Kevin Wolf, 2012/02/06
- Re: [Qemu-devel] [PATCH] block: Add support for vpc Fixed Disk type, Charles Arnold, 2012/02/06
- [Qemu-devel] [PATCH] vpc: Round up image size during fixed image creation, Kevin Wolf, 2012/02/07