>>>>> "Bart" == Bart Van Assche <bart.vanassche@xxxxxxxxxxx> writes: Bart> Today if a BLKDISCARD ioctl passes a non-aligned start and/or end Bart> sector to the kernel then the block layer will submit invalid Bart> (non-aligned) REQ_DISCARD requests to the block driver the ioctl Bart> applies to. I do not know what you mean by "invalid". A device that implements UNMAP can freely ignore any parts of a request block range that are not aligned to its internal allocation units. >From SBC: "An unmap request with a number of logical blocks that is not a multiple of this value (OPTIMAL UNMAP GRANULARITY) may result in unmap operations on fewer LBAs than requested." and "An unmap request with a starting LBA that is not optimal may result in unmap operations on fewer LBAs than requested." The same is true for SATA which has no way report granularity and alignment at all. Nowhere does it say that a request that is not an aligned multiple of any reported granularity should be considered "invalid" or rejected by the storage. -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
