On 12/21/2016 08:50 AM, Christoph Hellwig wrote: > On Tue, Dec 20, 2016 at 12:02:27AM -0200, Mauricio Faria de Oliveira wrote: >> When a SCSI command (e.g., read operation) is partially completed >> with good status and residual bytes (i.e., not all the bytes from >> the specified transfer length were transferred) the SCSI midlayer >> will update the request/bios with the completed bytes and requeue >> the request in order to complete the remainder/pending bytes. >> >> However, when the device sector size is greater than the 512-byte >> default/kernel sector size, alignment restrictions and validation >> apply (both to the starting logical block address, and the number >> of logical blocks to transfer) -- values must be multiples of the >> device sector size, otherwise the kernel fails the request in the >> preparation stage (e.g., sd_setup_read_write_cmnd() at sd.c file): > > How do you even get an unaligned residual count? Except for SES > processor devices (which will only issue BLOCK_PC commands) this is > not allowed by SPC: > > "The residual count shall be reported in bytes if the peripheral device > type in the destination target descriptor is 03h (i.e., processor device), > and in destination device blocks for all other device type codes." Which actually would be pretty much my objection, too. This would only be applicable for 512e drives, where we _might_ end up with a residual smaller than the physical sector size. But that should be handled by firmware; after all, that's what the 'e' implies, right? Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
