| Message ID | 20170525184327.23570-6-bart.vanassche@sandisk.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, May 25, 2017 at 11:43:13AM -0700, Bart Van Assche wrote: > Since the cdrom driver only supports request queues for which > struct scsi_request is the first member of their private request > data, refuse to register block layer queues for which this is > not the case. Hmm. I think we have a deeper issue there. The cdrom layer usually sends packets commands through the cdrom ops ->generic_packet method, but one function (cdrom_read_cdda_bpc) seems to directly send a scsi passthrough request. It is only used if the cdda_method is not CDDA_OLD, which is set if the cdrom_device_info structure does not have a gendisk pointer hanging off it. It seems like the legacy cdrom drivers fall into that category and would be broken by this change.
On Fri, 2017-05-26 at 08:08 +0200, Christoph Hellwig wrote: > On Thu, May 25, 2017 at 11:43:13AM -0700, Bart Van Assche wrote: > > Since the cdrom driver only supports request queues for which > > struct scsi_request is the first member of their private request > > data, refuse to register block layer queues for which this is > > not the case. > > Hmm. I think we have a deeper issue there. The cdrom layer usually > sends packets commands through the cdrom ops ->generic_packet > method, but one function (cdrom_read_cdda_bpc) seems to directly > send a scsi passthrough request. It is only used if the cdda_method > is not CDDA_OLD, which is set if the cdrom_device_info structure > does not have a gendisk pointer hanging off it. It seems like > the legacy cdrom drivers fall into that category and would be > broken by this change. Hello Christoph, How about moving the check into cdrom_read_cdda_bpc()? As far as I can see that function is only called if a CDROMREADAUDIO ioctl is submitted. Although Documentation/cdrom/cdrom-standard.tex mentions that that ioctl is unsupported applications like cdparanoia use it. Bart.
On Fri, May 26, 2017 at 03:50:42PM +0000, Bart Van Assche wrote: > On Fri, 2017-05-26 at 08:08 +0200, Christoph Hellwig wrote: > > On Thu, May 25, 2017 at 11:43:13AM -0700, Bart Van Assche wrote: > > > Since the cdrom driver only supports request queues for which > > > struct scsi_request is the first member of their private request > > > data, refuse to register block layer queues for which this is > > > not the case. > > > > Hmm. I think we have a deeper issue there. The cdrom layer usually > > sends packets commands through the cdrom ops ->generic_packet > > method, but one function (cdrom_read_cdda_bpc) seems to directly > > send a scsi passthrough request. It is only used if the cdda_method > > is not CDDA_OLD, which is set if the cdrom_device_info structure > > does not have a gendisk pointer hanging off it. It seems like > > the legacy cdrom drivers fall into that category and would be > > broken by this change. > > Hello Christoph, > > How about moving the check into cdrom_read_cdda_bpc()? As far as I can see > that function is only called if a CDROMREADAUDIO ioctl is submitted. Although > Documentation/cdrom/cdrom-standard.tex mentions that that ioctl is unsupported > applications like cdparanoia use it. I guess that's fine for now. In the long run we can probably replace the current users of generic_packet method with direct scsi passthrough requests, but that can be left for later.
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c index 76c952fd9ab9..5c1fec31b7ef 100644 --- a/drivers/cdrom/cdrom.c +++ b/drivers/cdrom/cdrom.c @@ -594,6 +594,10 @@ int register_cdrom(struct cdrom_device_info *cdi) if (cdo->open == NULL || cdo->release == NULL) return -EINVAL; + if (!blk_queue_scsi_pdu(cdi->disk->queue)) { + WARN_ONCE(true, "Attempt to register a non-SCSI queue\n"); + return -EINVAL; + } if (!banner_printed) { pr_info("Uniform CD-ROM driver " REVISION "\n"); banner_printed = 1;
Since the cdrom driver only supports request queues for which struct scsi_request is the first member of their private request data, refuse to register block layer queues for which this is not the case. References: commit 82ed4db499b8 ("block: split scsi_request out of struct request") Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Omar Sandoval <osandov@fb.com> Cc: linux-block@vger.kernel.org --- drivers/cdrom/cdrom.c | 4 ++++ 1 file changed, 4 insertions(+)