Re: [Qemu-devel] [RFC PATCH v4 08/28] QEMUSizedBuffer: Introduce two help functions for qsb

[zhanghailiang <zhang.zhanghailiang@huawei.com>]

On 2015/5/15 19:56, Dr. David Alan Gilbert wrote:
> * zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
>> Introduce two new QEMUSizedBuffer APIs which will be used by COLO to buffer
>> VM state:
>> One is qsb_put_buffer(), which put the content of a given QEMUSizedBuffer
>> into QEMUFile, this is used to send buffered VM state to secondary.
>> Another is qsb_fill_buffer(), read 'size' bytes of data from the file into
>> qsb, this is used to get VM state from socket into a buffer.
>>
>> Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>
> (I could use these in my postcopy world)

Please feel free to do that, maybe this patch can be merged in advance as prerequisite patch ;)

>
>> ---
>>   include/migration/qemu-file.h |  3 ++-
>>   migration/qemu-file-buf.c     | 58 +++++++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 60 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
>> index 745a850..09a0e2a 100644
>> --- a/include/migration/qemu-file.h
>> +++ b/include/migration/qemu-file.h
>> @@ -140,7 +140,8 @@ ssize_t qsb_get_buffer(const QEMUSizedBuffer *, off_t start, size_t count,
>>                          uint8_t *buf);
>>   ssize_t qsb_write_at(QEMUSizedBuffer *qsb, const uint8_t *buf,
>>                        off_t pos, size_t count);
>> -
>> +void qsb_put_buffer(QEMUFile *f, QEMUSizedBuffer *qsb, int size);
>> +int qsb_fill_buffer(QEMUSizedBuffer *qsb, QEMUFile *f, int size);
>>
>>   /*
>>    * For use on files opened with qemu_bufopen
>> diff --git a/migration/qemu-file-buf.c b/migration/qemu-file-buf.c
>> index 16a51a1..686f417 100644
>> --- a/migration/qemu-file-buf.c
>> +++ b/migration/qemu-file-buf.c
>> @@ -365,6 +365,64 @@ ssize_t qsb_write_at(QEMUSizedBuffer *qsb, const uint8_t *source,
>>       return count;
>>   }
>>
>> +
>> +/**
>> + * Put the content of a given QEMUSizedBuffer into QEMUFile.
>> + *
>> + * @f: A QEMUFile
>> + * @qsb: A QEMUSizedBuffer
>> + * @size: size of content to write
>> + */
>> +void qsb_put_buffer(QEMUFile *f, QEMUSizedBuffer *qsb, int size)
>> +{
>> +    int i, l;
>> +
>> +    for (i = 0; i < qsb->n_iov && size > 0; i++) {
>> +        l = MIN(qsb->iov[i].iov_len, size);
>> +        qemu_put_buffer(f, qsb->iov[i].iov_base, l);
>> +        size -= l;
>> +    }
>> +}
>> +
>> +/*
>> + * Read 'size' bytes of data from the file into qsb.
>> + * always fill from pos 0 and used after qsb_create().
>> + *
>> + * It will return size bytes unless there was an error, in which case it will
>> + * return as many as it managed to read (assuming blocking fd's which
>> + * all current QEMUFile are)
>> + */
>> +int qsb_fill_buffer(QEMUSizedBuffer *qsb, QEMUFile *f, int size)
>> +{
>> +    ssize_t rc = qsb_grow(qsb, size);
>> +    int pending = size, i;
>> +    qsb->used = 0;
>> +    uint8_t *buf = NULL;
>> +
>> +    if (rc < 0) {
>> +        return rc;
>> +    }
>> +
>> +    for (i = 0; i < qsb->n_iov && pending > 0; i++) {
>> +        int doneone = 0;
>> +        /* read until iov full */
>> +        while (doneone < qsb->iov[i].iov_len && pending > 0) {
>> +            int readone = 0;
>> +            buf = qsb->iov[i].iov_base;
>> +            readone = qemu_get_buffer(f, buf,
>> +                                MIN(qsb->iov[i].iov_len - doneone, pending));
>> +            if (readone == 0) {
>> +                return qsb->used;
>> +            }
>> +            buf += readone;
>> +            doneone += readone;
>> +            pending -= readone;
>> +            qsb->used += readone;
>> +        }
>> +    }
>> +    return qsb->used;
>> +}
>> +
>>   typedef struct QEMUBuffer {
>>       QEMUSizedBuffer *qsb;
>>       QEMUFile *file;
>> --
>> 1.7.12.4
>>
>>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>
> .
>