Bug 106871

Summary:	Lower log level for "No Caching mode page found" and "Assuming drive cache: write through"
Product:	IO/Storage	Reporter:	Tom Yan (tom.ty89)
Component:	SCSI	Assignee:	linux-scsi (linux-scsi)
Status:	NEW ---
Severity:	normal
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	4.2.4	Subsystem:
Regression:	No	Bisected commit-id:

Description Tom Yan 2015-10-29 08:29:00 UTC

Is there any particular reason that these two should be of error level? I don't see why we should pay that much of attention to them since it's just how vendors implemented the drive. Neither can the users or should they do anything to fix it. IMHO they should be of notice level or at most warning.

Comment 1 Tom Yan 2015-10-31 08:06:05 UTC

https://bugzilla.kernel.org/show_bug.cgi?id=16490#c8

The question is, why are we even using "write through" as fallback when if it can be dangerous? What's wrong with using "write back" as fallback instead? Would a SYNCHRONIZE CACHE command ever be a threat to devices without write cache or caching mode page?

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b81478d82e389dd0961760f5ff6f56b50d29db6d
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=eaa05dfcdb12cf3a7bedf8918dc8699c00944384

Seems like we consider "write back" an safer option everywhere else but we just somehow require users to use a quirk to switch to that for no reason. This just looks silly to me.