> -----Original Message----- > From: James Bottomley [mailto:James.Bottomley@xxxxxxxxxxxxxxxxxxxxx] > Sent: Monday, October 17, 2011 11:27 AM > To: KY Srinivasan > Cc: gregkh@xxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > devel@xxxxxxxxxxxxxxxxxxxxxx; virtualization@xxxxxxxxxxxxxx; ohering@xxxxxxxx; > linux-scsi@xxxxxxxxxxxxxxx; hch@xxxxxxxxxxxxx; Haiyang Zhang > Subject: RE: [PATCH 1/1] Staging: hv: storvsc: Move the storage driver out of > staging > > On Mon, 2011-10-17 at 15:15 +0000, KY Srinivasan wrote: > > > As I deal with the review comments now, do you want me to get these > > changes > > applied first to Greg's tree before you would consider moving this > > driver to drivers/scsi > > directory, or could you move the driver as it is in Greg's tree under > > staging and I could give > > you patches against the moved driver. > > Either way is fine by me. The best route for this is to get the staging > update into Linus head, then work on the actual SCSI problems. I'd like > other SCSI people besides me to review it. Christoph had reviewed this code sometime back and I think I have addressed the issues he had raised. These patches have already been applied by Greg to his staging tree. > > > > OK, so as I read the code, what it can't handle is fragments except at > > > the ends. As long as everything always transfers in multiples of 4k, > > > the problem will never occur. This means that all devices you present > > > need to tell the OS they have 4k sectors. I *think* you can do this by > > > setting blk_limits_io_min() in the driver ... but you'll have to test > > > this. The minimum sector size gets set also in sd.c when we probe the > > > disk. I think that won't override blk_limits_io_min(), but please test > > > (we don't have any SCSI drivers which have ever used this setting). > > > > > > The way to test, is to read back the /sys/block/<dev>/queue/ settings > > > when presenting a 512 byte sector disk. (And the way to activate your > > > bounce code would be to create a filesystem with a < PAGE_SIZE block > > > size). > > > In any event, I will try your suggestion though. > > Just to be clear: Setting the minimum I/O size is completely well > tested: it's how we handle 4k sector drives. What hasn't been tested is > the ability of the *driver* to enforce the minimum using > blk_limits_io_min(). As long at that doesn't get overridden by sd when > it sees a 512b drive, the rest of the block paths (those which actually > enforce the minimum) have all been well tested. > James, I used the blk_limits_io_min() to 4k and yet I see I/O requests coming in to the driver that need to be handled with the bounce buffers. So I am not quite sure how to avoid having the bounce buffer handling code. This is with a file system with 2k block size. Other than this, I have addressed all of your other comments. I am going to send these patches out to the staging tree. Do you want me to send out a patch moving the driver out of staging for your review as well. Let me know. Regards, K. Y ��.n��������+%������w��{.n�����{������ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
