Dailey, Nate wrote: > These patches (against a 2.6.9 kernel, Redhat AS 4) for st add a > reference count, and fix a few bugs I hit during testing (administrative > removes and cable pulls with IO in progress). > > The primary change is adding a kref to the Scsi_Tape structure, to avoid > an oops when the tape drive is removed while open. This includes > scsi_tape_get/put routines and scsi_tape_release, and changes to st_open > and st_release. This is all based on the SCSI disk & CD reference > counting code. I've actually been working on a similar patch for mainline. I'd be happy to send out my patch, which has the kref added to Scsi_Tape and has been tested on current mainline. I haven't hit the additional bugs you mentioned below, but am still testing different scenarios. -Brian > > > I hit some bugs while I was testing this code. Fixes for these are also > included in the patch: > > - When an IO gets a "dead device" error, we need to check the rq_status > to determine if the request actually completed (scsi_wait_req does > this)... else there's no notification to the caller that the IO failed. > There are two changes for this, one in st_do_scsi and one in > write_behind_check. > > - When an async IO gets a "dead device" error, we're notified of the > completion by the block layer (end_that_request_last), so last_SRpnt > doesn't get set (as it would if the complete were done by > st_sleep_done). So I changed how last_SRpnt is used to get around > this... it's now set only for async IOs, just before the IO is issued > (and nulled out when the IO comes back). > > > I also hit the following problem when I briefly tested on a SUSE kernel > (it wasn't in the Redhat kernel I did most of my testing with, but it is > in 2.6.12): > > - In these kernels, we no longer get a "complete" from > end_that_request_last when a device goes away and an IO is rejected. I > therefore added to st_do_scsi (but it's commented in this patch) setting > SRpnt->sr_request->end_io to blk_end_sync_rq, which will do the > complete. Since blk_end_sync_rq nulls out rq->waiting, I changed > st_do_scsi to wait on a local variable, and added a check for null in > st_sleep_done (just in case). > > > And just one more thing: > > - I noticed that in 2.6.12, there is what appears to be a bogus use of > last_SRpnt in st_chk_result (this doesn't exist in the kernels I tested > with). This would cause problems if these patches are ported to 2.6.12, > because of how I changed the use of last_SRpnt. Either my code has to > change, or st_chk_result shouldn't use last_SRpnt. > > > Anyway... as I said, these are against a 2.6.9 kernel (Redhat AS 4). If > you're interested, I could port these changes to 2.6.12... can't promise > I'll be able to test with that kernel, though. > > Nate Dailey > Stratus Technologies > > > Signed-off-by: Nate Dailey <nate.dailey@xxxxxxxxxxx> -- Brian King eServer Storage I/O IBM Linux Technology Center - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
