>>>>> "Nick" == Nick Piggin <npiggin@xxxxxxx> writes: >> 1) filesystem changed it >> 2) corruption on the wire or in the raid controller >> 3) the page was corrupted while the IO layer was doing the IO. >> >> 1 and 2 are easy, we bounce, retry and everyone continues on with >> their lives. With #3, we'll recrc and send the IO down again >> thinking the data is correct when really we're writing garbage. >> >> How can we tell these three cases apart? Nick> Do we really need to handle #3? It could have happened before the Nick> checksum was calculated. Reason #3 is one of the main reasons for having the checksum in the first place. The whole premise of the data integrity extensions is that the checksum is calculated in close temporal proximity to the data creation. I.e. eventually in userland. Filesystems will inevitably have to be integrity-aware for that to work. And it will be their job to keep the data pages stable during DMA. -- 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
