>>>>> "Linus" == Linus Torvalds <torva...@linux-foundation.org> writes:
Linus> On Thu, Mar 3, 2016 at 9:02 AM, Theodore Ts'o <ty...@mit.edu> wrote: >> >> There is a massive bug in the SATA specs about trim, which is that it >> is considered advisory. So the storage device can throw it away >> whenever it feels like it. (In practice, when it's too busy doing >> other things). Linus> Ugh. SCSI UNMAP provides similar semantics :( Linus> But that essentially says that we shouldn't expose this interface Linus> at all (unless we trust our white-lists - I'm sure they are Linus> getting better, but if nobody has ever really _relied_ on the Linus> zeroing behavior of trim, then I guess there could be tons of Linus> bugs lurking). We started out with the blacklist approach and it blew up. So now we're down to a whitelist of drives that have been sanctioned by their manufacturers to do the right thing. Occasionally a new SSD model messes things up but we haven't updated it since last summer. The drive vendors are much better at testing using Linux than they used to be. -- Martin K. Petersen Oracle Linux Engineering
