On 2020/01/29 3:15, Greg Kroah-Hartman wrote:
On Tue, Jan 28, 2020 at 07:02:31PM +0100, Pavel Machek wrote:
Hi!
From: Masato Suzuki masato.suzuki@wdc.com
ZBC/ZAC report zones command may return less bytes than requested if the number of matching zones for the report request is small. However, unlike read or write commands, the remainder of incomplete report zones commands cannot be automatically requested by the block layer: the start sector of the next report cannot be known, and the report reply may not be 512B aligned for SAS drives (a report zone reply size is always a multiple of 64B). The regular request completion code executing bio_advance() and restart of the command remainder part currently causes invalid zone descriptor data to be reported to the caller if the report zone size is smaller than 512B (a case that can happen easily for a report of the last zones of a SAS drive for example).
What is the story here? Mainline does not seem to have this patch, so this is not the case of "upstream commit xxx" line simply missing. If the same bug is fixed in mainline different way, it would be nice to point to that commit..
Yes, this is not needed in 5.4 as it was rewritten differently there.
Correct. REQ_OP_ZONE_REPORT was dropped with kernel 4.20 and report zones is now handled through a device file method with scsi_execute() instead of a BIO. So this bug does not exist in kernels 4.20 and upward.
thanks,
greg k-h