On Wed, Sep 25, 2013 at 05:02:56PM -0400, Jeff Cody wrote:
> @@ -1070,7 +1070,43 @@ exit:
> return ret;
> }
>
> +/*
> + * Allocate a new payload block at the end of the file.
> + *
> + * Allocation will happen at 1MB alignment inside the file
> + *
> + * Returns the file offset start of the new payload block
> + */
> +static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s,
> + uint64_t *new_offset)
> +{
> + *new_offset = bdrv_getlength(bs->file);
> +
> + /* per the spec, the address for a block is in units of 1MB */
> + *new_offset = ROUND_UP(*new_offset, 1024*1024);
> +
> + return bdrv_truncate(bs->file, *new_offset + s->block_size);
> +}
> +
> +/*
> + * Update the BAT tablet entry with the new file offset, and the new entry
s/tablet/table/
> + * state */
> +static void vhdx_update_bat_table_entry(BlockDriverState *bs, BDRVVHDXState
> *s,
> + VHDXSectorInfo *sinfo,
> + uint64_t *bat_entry,
> + uint64_t *bat_offset, int state)
> +{
> + /* The BAT entry is a uint64, with 44 bits for the file offset in units
> of
> + * 1MB, and 3 bits for the block state. */
> + s->bat[sinfo->bat_idx] = ((sinfo->file_offset>>20) <<
QEMU coding style requires space around the '>>'. Please run
scripts/checkpatch.pl.
> + VHDX_BAT_FILE_OFF_BITS);
>
> + s->bat[sinfo->bat_idx] |= state & VHDX_BAT_STATE_BIT_MASK;
> +
> + *bat_entry = cpu_to_le64(s->bat[sinfo->bat_idx]);
Call this argument bat_entry_le so callers know now to manipulate the
little-endian value directly?
> + *bat_offset = s->bat_offset + sinfo->bat_idx * sizeof(VHDXBatEntry);
> +
> +}
>
> /* Per the spec, on the first write of guest-visible data to the file the
> * data write guid must be updated in the header */
> @@ -1087,7 +1123,117 @@ int vhdx_user_visible_write(BlockDriverState *bs,
> BDRVVHDXState *s)
> static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t
> sector_num,
> int nb_sectors, QEMUIOVector *qiov)
> {
> - return -ENOTSUP;
> + int ret = -ENOTSUP;
> + BDRVVHDXState *s = bs->opaque;
> + VHDXSectorInfo sinfo;
> + uint64_t bytes_done = 0;
> + uint64_t bat_entry = 0;
> + uint64_t bat_entry_offset = 0;
> + bool bat_update;
> + QEMUIOVector hd_qiov;
> +
> + qemu_iovec_init(&hd_qiov, qiov->niov);
> +
> + qemu_co_mutex_lock(&s->lock);
> +
> + ret = vhdx_user_visible_write(bs, s);
> + if (ret < 0) {
> + goto exit;
> + }
> +
> + while (nb_sectors > 0) {
> + if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) {
> + /* not supported yet */
> + ret = -ENOTSUP;
> + goto exit;
> + } else {
> + bat_update = false;
> + vhdx_block_translate(s, sector_num, nb_sectors, &sinfo);
> +
> + qemu_iovec_reset(&hd_qiov);
> + qemu_iovec_concat(&hd_qiov, qiov, bytes_done,
> sinfo.bytes_avail);
> + /* check the payload block state */
> + switch (s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK) {
> + case PAYLOAD_BLOCK_ZERO:
> + /* in this case, we need to preserve zero writes for
> + * data that is not part of this write, so we must pad
> + * the rest of the buffer to zeroes */
> +
> + /* if we are on a posix system with ftruncate() that extends
> + * a file, then it is zero-filled for us. On Win32, the raw
> + * layer uses SetFilePointer and SetFileEnd, which does not
> + * zero fill AFAIK */
> +
> + /* TODO: queue another write of zero buffers if the host OS
> does
> + * not zero-fill on file extension */
This is never addressed in the series.
> +
> + /* fall through */
> + case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */
> + case PAYLOAD_BLOCK_UNMAPPED: /* fall through */
> + case PAYLOAD_BLOCK_UNDEFINED: /* fall through */
> + ret = vhdx_allocate_block(bs, s, &sinfo.file_offset);
> + if (ret < 0) {
> + goto exit;
> + }
> + /* once we support differencing files, this may also be
> + * partially present */
> + /* update block state to the newly specified state */
> + vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry,
> + &bat_entry_offset,
> + PAYLOAD_BLOCK_FULL_PRESENT);
In the specification the constant is called PAYLOAD_BLOCK_FULLY_PRESENT.
Is s/FULLY/FULL/ intentional and can you match the spec for consistency?
> + bat_update = true;
> + /* since we just allocated a block, file_offset is the
> + * beginning of the payload block. It needs to be the
> + * write address, which includes the offset into the block */
> + sinfo.file_offset += sinfo.block_offset;
> + /* fall through */
> + case PAYLOAD_BLOCK_FULL_PRESENT:
> + /* if the file offset address is in the header zone,
> + * there is a problem */
> + if (sinfo.file_offset < (1024*1024)) {
> + ret = -EFAULT;
> + goto exit;
> + }
> + /* block exists, so we can just overwrite it */
> + qemu_co_mutex_unlock(&s->lock);
> + ret = bdrv_co_writev(bs->file,
> + sinfo.file_offset>>BDRV_SECTOR_BITS,
> + sinfo.sectors_avail, &hd_qiov);
> + qemu_co_mutex_lock(&s->lock);
> + if (ret < 0) {
> + goto exit;
> + }
> + break;
> + case PAYLOAD_BLOCK_PARTIALLY_PRESENT:
> + /* we don't yet support difference files, fall through
> + * to error */
> + default:
> + ret = -EIO;
> + goto exit;
> + break;
> + }
> +
> + if (bat_update) {
Data must be stable on disk before we can expose the updated BAT entry.
Missing bdrv_co_flush().
