如果空间不包含可扩展块且存储池不包含请求的空间，命令会失败。
If the space contains no extendable chunks and the storage pool does not contain the requested space, the command will fail.
一个丢弃请求是此块层的一部分，提供了丢弃块的途径，并最终会导致向提供支持的ATA设备发出一个trim命令。
A discard request is part of the block layer and provides the means to discard blocks, eventually resulting in a trim command to a supporting ATA drive.
一个丢弃请求是此块层的一部分，提供了丢弃块的途径，并最终会导致向提供支持的ATA设备发出一个trim命令。
A discard request is part of the block layer and provides the means to discard blocks, eventually resulting in a trim command to a supporting ATA drive.
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