block/blkio: Tolerate device size changes
Some libblkio drivers may be able to work with regular files (e.g., io_uring) or otherwise resizable devices. Conservatively set BlockDriver::has_variable_length to true to ensure bdrv_nb_sectors() always gives up-to-date results. Also implement BlockDriver::bdrv_co_truncate for the case where no preallocation is needed and the device already has a size compatible with what was requested. Signed-off-by: Alberto Faria <afaria@redhat.com> Message-id: 20221029122031.975273-1-afaria@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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@ -848,6 +848,31 @@ static int64_t blkio_getlength(BlockDriverState *bs)
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return capacity;
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}
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static int coroutine_fn blkio_truncate(BlockDriverState *bs, int64_t offset,
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bool exact, PreallocMode prealloc,
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BdrvRequestFlags flags, Error **errp)
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{
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int64_t current_length;
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if (prealloc != PREALLOC_MODE_OFF) {
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error_setg(errp, "Unsupported preallocation mode '%s'",
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PreallocMode_str(prealloc));
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return -ENOTSUP;
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}
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current_length = blkio_getlength(bs);
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if (offset > current_length) {
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error_setg(errp, "Cannot grow device");
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return -EINVAL;
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} else if (exact && offset != current_length) {
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error_setg(errp, "Cannot resize device");
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return -ENOTSUP;
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}
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return 0;
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}
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static int blkio_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
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{
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return 0;
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@ -963,10 +988,12 @@ static void blkio_refresh_limits(BlockDriverState *bs, Error **errp)
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{ \
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.format_name = name, \
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.protocol_name = name, \
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.has_variable_length = true, \
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.instance_size = sizeof(BDRVBlkioState), \
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.bdrv_file_open = blkio_file_open, \
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.bdrv_close = blkio_close, \
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.bdrv_getlength = blkio_getlength, \
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.bdrv_co_truncate = blkio_truncate, \
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.bdrv_get_info = blkio_get_info, \
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.bdrv_attach_aio_context = blkio_attach_aio_context, \
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.bdrv_detach_aio_context = blkio_detach_aio_context, \
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