Created attachment 26560 [details] The boot process captured from a serial console As of 2.6.27 if any SCSI disk is attached that has been formatted with a 256 byte sector size, the boot process hangs. 512, 768, and 1024 byte sector disks do not seem to trigger this. The disks in use do NOT have a partition table. They are being used by out applications via the sg_io interface only. A 2.6.26.8 kernel works fine. I have bisected this problem to the following commit: # git bisect good 427e59f09fdba387547106de7bab980b7fff77be is first bad commit commit 427e59f09fdba387547106de7bab980b7fff77be Author: James Bottomley <James.Bottomley@HansenPartnership.com> Date: Sat Mar 8 18:24:17 2008 -0600 [SCSI] make use of the residue value USB sometimes doesn't return an error but instead returns a residue value indicating part (or all) of the command wasn't completed. So if the driver _done() error processing indicates the command was fully processed, subtract off the residue so that this USB error gets propagated. Cc: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> :040000 040000 d3bad84ebe1bc231e8e7d6267907ca62fd4d0dcd c85f8cb8bd4910724f0101e41054555980727e16 M drivers Now, what USB has to do with my SCSI disks is beyond me. I have a feeling that this commit is just uncovering another problem. I've attached a bootlog from a serial console that ends where the boot hangs. The does the same thing on a 2.6.34 kernel. Anything I can do to help, I'm available. Thanks and regards Mark
On Thu, 27 May 2010, Andrew Morton wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=16058 > > Summary: [BUG] Cannot boot any kernel from 2.6.27 on if a 256 > byte sector SCSI disk is attached > As of 2.6.27 if any SCSI disk is attached that has been formatted with a 256 > byte sector size, the boot process hangs. 512, 768, and 1024 byte sector > disks > do not seem to trigger this. The disks in use do NOT have a partition table. > They are being used by out applications via the sg_io interface only. > > A 2.6.26.8 kernel works fine. > > I have bisected this problem to the following commit: > > # git bisect good > 427e59f09fdba387547106de7bab980b7fff77be is first bad commit > commit 427e59f09fdba387547106de7bab980b7fff77be > Author: James Bottomley <James.Bottomley@HansenPartnership.com> > Date: Sat Mar 8 18:24:17 2008 -0600 > > [SCSI] make use of the residue value > > USB sometimes doesn't return an error but instead returns a residue > value indicating part (or all) of the command wasn't completed. So if > the driver _done() error processing indicates the command was fully > processed, subtract off the residue so that this USB error gets > propagated. > > Cc: Alan Stern <stern@rowland.harvard.edu> > Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> > > :040000 040000 d3bad84ebe1bc231e8e7d6267907ca62fd4d0dcd > c85f8cb8bd4910724f0101e41054555980727e16 M drivers > > Now, what USB has to do with my SCSI disks is beyond me. I have a > feeling that this commit is just uncovering another problem. I've attached > a bootlog from a serial console that ends where the boot hangs. > > The does the same thing on a 2.6.34 kernel. Anything I can do to help, I'm > available. I'd guess that this has nothing to do with the sector size. Instead the drive probably reports a non-zero residue when it shouldn't. Can you add some debugging printk's to the patch to find out in more detail what's going wrong? Alan Stern
On Thu, 27 May 2010, Mark Hounschell wrote: > >> As of 2.6.27 if any SCSI disk is attached that has been formatted with a > 256 > >> byte sector size, the boot process hangs. 512, 768, and 1024 byte sector > disks > >> The does the same thing on a 2.6.34 kernel. Anything I can do to help, I'm > >> available. > Yes, I can. But first let me ask, since reverting this patch on at least > 2.6.32 - 2.6.34 does not help, would it possibly be better if I did a > little more work to find out where it stops working with the above patch > reverted or not? I'd do 2.6.27 first, since that's where the problem started. Then move on to 2.6.34. There may be two different problems. Alan Stern
On 05/27/2010 04:30 PM, Alan Stern wrote: > On Thu, 27 May 2010, Andrew Morton wrote: > >> https://bugzilla.kernel.org/show_bug.cgi?id=16058 >> >> Summary: [BUG] Cannot boot any kernel from 2.6.27 on if a 256 >> byte sector SCSI disk is attached > >> As of 2.6.27 if any SCSI disk is attached that has been formatted with a 256 >> byte sector size, the boot process hangs. 512, 768, and 1024 byte sector >> disks >> do not seem to trigger this. The disks in use do NOT have a partition table. >> They are being used by out applications via the sg_io interface only. >> >> A 2.6.26.8 kernel works fine. >> >> I have bisected this problem to the following commit: >> >> # git bisect good >> 427e59f09fdba387547106de7bab980b7fff77be is first bad commit >> commit 427e59f09fdba387547106de7bab980b7fff77be >> Author: James Bottomley <James.Bottomley@HansenPartnership.com> >> Date: Sat Mar 8 18:24:17 2008 -0600 >> >> [SCSI] make use of the residue value >> >> USB sometimes doesn't return an error but instead returns a residue >> value indicating part (or all) of the command wasn't completed. So if >> the driver _done() error processing indicates the command was fully >> processed, subtract off the residue so that this USB error gets >> propagated. >> >> Cc: Alan Stern <stern@rowland.harvard.edu> >> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> >> >> :040000 040000 d3bad84ebe1bc231e8e7d6267907ca62fd4d0dcd >> c85f8cb8bd4910724f0101e41054555980727e16 M drivers >> >> Now, what USB has to do with my SCSI disks is beyond me. I have a >> feeling that this commit is just uncovering another problem. I've attached >> a bootlog from a serial console that ends where the boot hangs. >> >> The does the same thing on a 2.6.34 kernel. Anything I can do to help, I'm >> available. > > I'd guess that this has nothing to do with the sector size. Instead > the drive probably reports a non-zero residue when it shouldn't. Can > you add some debugging printk's to the patch to find out in more detail > what's going wrong? > > Alan Stern > > Yes, I can. But first let me ask, since reverting this patch on at least 2.6.32 - 2.6.34 does not help, would it possibly be better if I did a little more work to find out where it stops working with the above patch reverted or not? Mark
On Fri, 28 May 2010, Mark Hounschell wrote: > First READ(10): > > sde: > ahc_calc_residual: Entered > ahc_calc_residual: return Case 5-1 resid = 0x800 > ahc_calc_residual: return Case 5-2 resid = 0x800 > > scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 0x00 > 0x00 0x00 0x08 0x00 > cmd->result = 0x00000000 > good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 > New good_bytes = 0x0 > scsi_finish_command: Complete > > From here it just keeps repeating this read of 8 blocks. (2048 bytes) so > it looks like the machine is hung. Probably not hung, just doing a lot of retries. It should time out eventually, but it might take a long time (perhaps as long as 15 minutes). The combination of the block layer and the SCSI layer isn't very good at knowing when to give up. > Now, I know for a fact that _if_ this read CDB is actually being sent to > the drive, it's actual residual count will be zero. These are working > disks and that read CDB is valid. > > Why is ahc_calc_residual saying that the residual count is as though the > read never took place? I noticed that the first read on all the SATA > drives was for 4096 bytes, why is this one only 2048? Should it have > been 4096 and ahc_calc_residual assume that? I don't know the answer to any of these questions. They could well be due to bugs in the driver, and I know nothing about how the aic7xxx driver works. You should talk to someone who does. In the meantime, you can track this down a little farther by adding printk's to the appropriate places in drivers/scsi/sd.c. Look at sd_prep_fn() to see why there's 2048 bytes instead of 4096. Alan Stern
On 05/27/2010 04:30 PM, Alan Stern wrote: > On Thu, 27 May 2010, Andrew Morton wrote: > > >> https://bugzilla.kernel.org/show_bug.cgi?id=16058 >> >> Summary: [BUG] Cannot boot any kernel from 2.6.27 on if a 256 >> byte sector SCSI disk is attached >> > >> As of 2.6.27 if any SCSI disk is attached that has been formatted with a 256 >> byte sector size, the boot process hangs. 512, 768, and 1024 byte sector >> disks >> do not seem to trigger this. The disks in use do NOT have a partition table. >> They are being used by out applications via the sg_io interface only. >> >> A 2.6.26.8 kernel works fine. >> >> I have bisected this problem to the following commit: >> >> # git bisect good >> 427e59f09fdba387547106de7bab980b7fff77be is first bad commit >> commit 427e59f09fdba387547106de7bab980b7fff77be >> Author: James Bottomley <James.Bottomley@HansenPartnership.com> >> Date: Sat Mar 8 18:24:17 2008 -0600 >> >> [SCSI] make use of the residue value >> >> USB sometimes doesn't return an error but instead returns a residue >> value indicating part (or all) of the command wasn't completed. So if >> the driver _done() error processing indicates the command was fully >> processed, subtract off the residue so that this USB error gets >> propagated. >> >> Cc: Alan Stern <stern@rowland.harvard.edu> >> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> >> >> :040000 040000 d3bad84ebe1bc231e8e7d6267907ca62fd4d0dcd >> c85f8cb8bd4910724f0101e41054555980727e16 M drivers >> >> Now, what USB has to do with my SCSI disks is beyond me. I have a >> feeling that this commit is just uncovering another problem. I've attached >> a bootlog from a serial console that ends where the boot hangs. >> >> The does the same thing on a 2.6.34 kernel. Anything I can do to help, I'm >> available. >> > I'd guess that this has nothing to do with the sector size. Instead > the drive probably reports a non-zero residue when it shouldn't. Can > you add some debugging printk's to the patch to find out in more detail > what's going wrong? > > Alan Stern > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Alan, I've added some printks in scsi.c and aic7xxx_core.c. A TUR: ahc_calc_residual: Entered ahc_calc_residual: return Case 2 sgptr = 0x00000001 ahc_calc_residual: Entered ahc_calc_residual: return Case 5-1 resid = 0xe ahc_calc_residual: return Case 5-2 resid = 0xe scsi_finish_command: Entered for cmd(6):0x00 0x00 0x00 0x00 0x00 0x00 cmd->result = 0x08000002 good_bytes = 0x0 scsi_finish_command: Complete Another TUR: scsi_finish_command: Entered for cmd(6):0x00 0x00 0x00 0x00 0x00 0x00 cmd->result = 0x00000000 good_bytes = 0x0 scsi_finish_command: Complete A Read Capicity: scsi_finish_command: Entered for cmd(10):0x25 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 cmd->result = 0x00000000 good_bytes = 0x8 scsi_finish_command: Complete sd 8:0:0:0: [sde] 7260582 256-byte hardware sectors (1859 MB) A Mode Sense: scsi_finish_command: Entered for cmd(6):0x1a 0x00 0x3f 0x00 0x04 0x00 cmd->result = 0x00000000 good_bytes = 0x4 scsi_finish_command: Complete sd 8:0:0:0: [sde] Write Protect is off Another Mode Sense: scsi_finish_command: Entered for cmd(6):0x1a 0x00 0x08 0x00 0x04 0x00 cmd->result = 0x00000000 good_bytes = 0x4 scsi_finish_command: Complete Another Mode Sense: ahc_calc_residual: Entered ahc_calc_residual: return Case 5-1 resid = 0x8 ahc_calc_residual: return Case 5-2 resid = 0x8 scsi_finish_command: Entered for cmd(6):0x1a 0x00 0x08 0x00 0x20 0x00 cmd->result = 0x00000000 good_bytes = 0x20 scsi_finish_command: Complete sd 8:0:0:0: [sde] Write cache: disabled, read cache: enabled, supports DPO and FUA Another TUR: scsi_finish_command: Entered for cmd(6):0x00 0x00 0x00 0x00 0x00 0x00 cmd->result = 0x00000000 good_bytes = 0x0 scsi_finish_command: Complete Another Read Capacity: scsi_finish_command: Entered for cmd(10):0x25 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 cmd->result = 0x00000000 good_bytes = 0x8 scsi_finish_command: Complete sd 8:0:0:0: [sde] 7260582 256-byte hardware sectors (1859 MB) Another Mode Sense: scsi_finish_command: Entered for cmd(6):0x1a 0x00 0x3f 0x00 0x04 0x00 cmd->result = 0x00000000 good_bytes = 0x4 scsi_finish_command: Complete sd 8:0:0:0: [sde] Write Protect is off Another Mode Sense: scsi_finish_command: Entered for cmd(6):0x1a 0x00 0x08 0x00 0x04 0x00 cmd->result = 0x00000000 good_bytes = 0x4 scsi_finish_command: Complete Another Mode Sense: ahc_calc_residual: Entered ahc_calc_residual: return Case 5-1 resid = 0x8 ahc_calc_residual: return Case 5-2 resid = 0x8 scsi_finish_command: Entered for cmd(6):0x1a 0x00 0x08 0x00 0x20 0x00 cmd->result = 0x00000000 good_bytes = 0x20 scsi_finish_command: Complete sd 8:0:0:0: [sde] Write cache: disabled, read cache: enabled, supports DPO and FUA Another TUR: scsi_finish_command: Entered for cmd(6):0x00 0x00 0x00 0x00 0x00 0x00 cmd->result = 0x00000000 good_bytes = 0x0 scsi_finish_command: Complete Another Read Capacity: scsi_finish_command: Entered for cmd(10):0x25 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 cmd->result = 0x00000000 good_bytes = 0x8 scsi_finish_command: Complete sd 8:0:0:0: [sde] 7260582 256-byte hardware sectors (1859 MB) Another Mode Sense: scsi_finish_command: Entered for cmd(6):0x1a 0x00 0x3f 0x00 0x04 0x00 cmd->result = 0x00000000 good_bytes = 0x4 scsi_finish_command: Complete sd 8:0:0:0: [sde] Write Protect is off Another Mode Sense: scsi_finish_command: Entered for cmd(6):0x1a 0x00 0x08 0x00 0x04 0x00 cmd->result = 0x00000000 good_bytes = 0x4 scsi_finish_command: Complete Another Mode Sense: ahc_calc_residual: Entered ahc_calc_residual: return Case 5-1 resid = 0x8 ahc_calc_residual: return Case 5-2 resid = 0x8 scsi_finish_command: Entered for cmd(6):0x1a 0x00 0x08 0x00 0x20 0x00 cmd->result = 0x00000000 good_bytes = 0x20 scsi_finish_command: Complete sd 8:0:0:0: [sde] Write cache: disabled, read cache: enabled, supports DPO and FUA First READ(10): sde: ahc_calc_residual: Entered ahc_calc_residual: return Case 5-1 resid = 0x800 ahc_calc_residual: return Case 5-2 resid = 0x800 scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x08 0x00 cmd->result = 0x00000000 good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 New good_bytes = 0x0 scsi_finish_command: Complete From here it just keeps repeating this read of 8 blocks. (2048 bytes) so it looks like the machine is hung. Now, I know for a fact that _if_ this read CDB is actually being sent to the drive, it's actual residual count will be zero. These are working disks and that read CDB is valid. Why is ahc_calc_residual saying that the residual count is as though the read never took place? I noticed that the first read on all the SATA drives was for 4096 bytes, why is this one only 2048? Should it have been 4096 and ahc_calc_residual assume that? BTW, I'll be in and out all day today so I may not be able to respond quickly. One thing all these machines I have doing this, have in common, is the scsi controller (Aic7xxx). Regards Mark
Reply-To: James.Bottomley@suse.de On Fri, 2010-05-28 at 10:58 -0400, Alan Stern wrote: > On Fri, 28 May 2010, Mark Hounschell wrote: > > > First READ(10): > > > > sde: > > ahc_calc_residual: Entered > > ahc_calc_residual: return Case 5-1 resid = 0x800 > > ahc_calc_residual: return Case 5-2 resid = 0x800 > > > > scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 0x00 > > 0x00 0x00 0x08 0x00 > > cmd->result = 0x00000000 > > good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 > > New good_bytes = 0x0 > > scsi_finish_command: Complete > > > > From here it just keeps repeating this read of 8 blocks. (2048 bytes) so > > it looks like the machine is hung. > > Probably not hung, just doing a lot of retries. It should time out > eventually, but it might take a long time (perhaps as long as 15 > minutes). The combination of the block layer and the SCSI layer isn't > very good at knowing when to give up. Actually, I think this is a partition read. Each partition manager tends to read a page through the page cache. If we get an error, we seem to re-read to fill the cache. > > Now, I know for a fact that _if_ this read CDB is actually being sent to > > the drive, it's actual residual count will be zero. These are working > > disks and that read CDB is valid. > > > > Why is ahc_calc_residual saying that the residual count is as though the > > read never took place? I noticed that the first read on all the SATA > > drives was for 4096 bytes, why is this one only 2048? Should it have > > been 4096 and ahc_calc_residual assume that? > > I don't know the answer to any of these questions. They could well be > due to bugs in the driver, and I know nothing about how the aic7xxx > driver works. You should talk to someone who does. I'll take this one ... although we're a bit lacking in documentation for this driver. I think the 2048 is because something is hardcoded to think 8 sectors is a page. James
On 05/28/2010 12:34 PM, bugzilla-daemon@bugzilla.kernel.org wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=16058 > > > > > > --- Comment #6 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org> > 2010-05-28 16:34:28 --- > Reply-To: James.Bottomley@suse.de > > On Fri, 2010-05-28 at 10:58 -0400, Alan Stern wrote: > >> On Fri, 28 May 2010, Mark Hounschell wrote: >> >> >>> First READ(10): >>> >>> sde: >>> ahc_calc_residual: Entered >>> ahc_calc_residual: return Case 5-1 resid = 0x800 >>> ahc_calc_residual: return Case 5-2 resid = 0x800 >>> >>> scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 0x00 >>> 0x00 0x00 0x08 0x00 >>> cmd->result = 0x00000000 >>> good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 >>> New good_bytes = 0x0 >>> scsi_finish_command: Complete >>> >>> From here it just keeps repeating this read of 8 blocks. (2048 bytes) so >>> it looks like the machine is hung. >>> >> Probably not hung, just doing a lot of retries. It should time out >> eventually, but it might take a long time (perhaps as long as 15 >> minutes). The combination of the block layer and the SCSI layer isn't >> very good at knowing when to give up. >> > Actually, I think this is a partition read. Each partition manager > tends to read a page through the page cache. If we get an error, we > seem to re-read to fill the cache. > > >>> Now, I know for a fact that _if_ this read CDB is actually being sent to >>> the drive, it's actual residual count will be zero. These are working >>> disks and that read CDB is valid. >>> >>> Why is ahc_calc_residual saying that the residual count is as though the >>> read never took place? I noticed that the first read on all the SATA >>> drives was for 4096 bytes, why is this one only 2048? Should it have >>> been 4096 and ahc_calc_residual assume that? >>> >> I don't know the answer to any of these questions. They could well be >> due to bugs in the driver, and I know nothing about how the aic7xxx >> driver works. You should talk to someone who does. >> > I'll take this one ... although we're a bit lacking in documentation for > this driver. > > I think the 2048 is because something is hardcoded to think 8 sectors is > a page. > > James > > Your probably right. But is a 256 byte sector really a supported sector size for a linux fs on a SCSI disk? When it sees a 768 byte sector disk, it says it's an unsupported size and goes on with the boot process without even doing a read for a partition table. Should maybe it be doing the same for a 256 byte sector disk??? Regards Mark
Reply-To: James.Bottomley@suse.de On Fri, 2010-05-28 at 15:29 -0400, Mark Hounschell wrote: > On 05/28/2010 12:34 PM, bugzilla-daemon@bugzilla.kernel.org wrote: > > https://bugzilla.kernel.org/show_bug.cgi?id=16058 > > > > > > > > > > > > --- Comment #6 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org> > 2010-05-28 16:34:28 --- > > Reply-To: James.Bottomley@suse.de > > > > On Fri, 2010-05-28 at 10:58 -0400, Alan Stern wrote: > > > >> On Fri, 28 May 2010, Mark Hounschell wrote: > >> > >> > >>> First READ(10): > >>> > >>> sde: > >>> ahc_calc_residual: Entered > >>> ahc_calc_residual: return Case 5-1 resid = 0x800 > >>> ahc_calc_residual: return Case 5-2 resid = 0x800 > >>> > >>> scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 0x00 > >>> 0x00 0x00 0x08 0x00 > >>> cmd->result = 0x00000000 > >>> good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 > >>> New good_bytes = 0x0 > >>> scsi_finish_command: Complete > >>> > >>> From here it just keeps repeating this read of 8 blocks. (2048 bytes) so > >>> it looks like the machine is hung. > >>> > >> Probably not hung, just doing a lot of retries. It should time out > >> eventually, but it might take a long time (perhaps as long as 15 > >> minutes). The combination of the block layer and the SCSI layer isn't > >> very good at knowing when to give up. > >> > > Actually, I think this is a partition read. Each partition manager > > tends to read a page through the page cache. If we get an error, we > > seem to re-read to fill the cache. > > > > > >>> Now, I know for a fact that _if_ this read CDB is actually being sent to > >>> the drive, it's actual residual count will be zero. These are working > >>> disks and that read CDB is valid. > >>> > >>> Why is ahc_calc_residual saying that the residual count is as though the > >>> read never took place? I noticed that the first read on all the SATA > >>> drives was for 4096 bytes, why is this one only 2048? Should it have > >>> been 4096 and ahc_calc_residual assume that? > >>> > >> I don't know the answer to any of these questions. They could well be > >> due to bugs in the driver, and I know nothing about how the aic7xxx > >> driver works. You should talk to someone who does. > >> > > I'll take this one ... although we're a bit lacking in documentation for > > this driver. > > > > I think the 2048 is because something is hardcoded to think 8 sectors is > > a page. > > > > James > > > > > Your probably right. But is a 256 byte sector really a supported sector > size for a linux fs on a SCSI disk? In theory the block layer can support any power of two sector size (or really any sector size which is a divisor of the page size). We had a use for 256 byte sectors once, so they're in SCSI. In practice, since they're so rare, the code paths are never tested (as you found out) and there's a more annoying problem which is since the linux base sector size is 512, you have to multiply to get from 256 to 512 ... for all other sector sizes you have to divide, so any conversion routine that only right shifts would get this wrong. > When it sees a 768 byte sector disk, > it says it's an unsupported size and goes on with the boot process > without even doing a read for a partition table. that's because 768 isn't a power of 2, so it's completely unsupportable. > Should maybe it be > doing the same for a 256 byte sector disk??? Possibly ... I don't know what the 256 byte sector support was for ... all I know is that whatever it was, I don't have one. James
On 05/28/2010 04:25 PM, James Bottomley wrote: > On Fri, 2010-05-28 at 15:29 -0400, Mark Hounschell wrote: > >> On 05/28/2010 12:34 PM, bugzilla-daemon@bugzilla.kernel.org wrote: >> >>> https://bugzilla.kernel.org/show_bug.cgi?id=16058 >>> >>> >>> >>> >>> >>> --- Comment #6 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org> >>> 2010-05-28 16:34:28 --- >>> Reply-To: James.Bottomley@suse.de >>> >>> On Fri, 2010-05-28 at 10:58 -0400, Alan Stern wrote: >>> >>> >>>> On Fri, 28 May 2010, Mark Hounschell wrote: >>>> >>>> >>>> >>>>> First READ(10): >>>>> >>>>> sde: >>>>> ahc_calc_residual: Entered >>>>> ahc_calc_residual: return Case 5-1 resid = 0x800 >>>>> ahc_calc_residual: return Case 5-2 resid = 0x800 >>>>> >>>>> scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 0x00 >>>>> 0x00 0x00 0x08 0x00 >>>>> cmd->result = 0x00000000 >>>>> good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 >>>>> New good_bytes = 0x0 >>>>> scsi_finish_command: Complete >>>>> >>>>> From here it just keeps repeating this read of 8 blocks. (2048 bytes) so >>>>> it looks like the machine is hung. >>>>> >>>>> >>>> Probably not hung, just doing a lot of retries. It should time out >>>> eventually, but it might take a long time (perhaps as long as 15 >>>> minutes). The combination of the block layer and the SCSI layer isn't >>>> very good at knowing when to give up. >>>> >>>> >>> Actually, I think this is a partition read. Each partition manager >>> tends to read a page through the page cache. If we get an error, we >>> seem to re-read to fill the cache. >>> >>> >>> >>>>> Now, I know for a fact that _if_ this read CDB is actually being sent to >>>>> the drive, it's actual residual count will be zero. These are working >>>>> disks and that read CDB is valid. >>>>> >>>>> Why is ahc_calc_residual saying that the residual count is as though the >>>>> read never took place? I noticed that the first read on all the SATA >>>>> drives was for 4096 bytes, why is this one only 2048? Should it have >>>>> been 4096 and ahc_calc_residual assume that? >>>>> >>>>> >>>> I don't know the answer to any of these questions. They could well be >>>> due to bugs in the driver, and I know nothing about how the aic7xxx >>>> driver works. You should talk to someone who does. >>>> >>>> >>> I'll take this one ... although we're a bit lacking in documentation for >>> this driver. >>> >>> I think the 2048 is because something is hardcoded to think 8 sectors is >>> a page. >>> >>> James >>> >>> >>> >> Your probably right. But is a 256 byte sector really a supported sector >> size for a linux fs on a SCSI disk? >> > In theory the block layer can support any power of two sector size (or > really any sector size which is a divisor of the page size). We had a > use for 256 byte sectors once, so they're in SCSI. In practice, since > they're so rare, the code paths are never tested (as you found out) and > there's a more annoying problem which is since the linux base sector > size is 512, you have to multiply to get from 256 to 512 ... for all > other sector sizes you have to divide, so any conversion routine that > only right shifts would get this wrong. > > from the fdisk man page: -b sectorsize Specify the sector size of the disk. Valid values are 512, 1024, 2048 or 4096. (Recent kernels know the sector size. Use this only on old kernels or to override the kernel's ideas.) So how does one create a linux fs on a 256 byte sectored disk? >> When it sees a 768 byte sector disk, >> it says it's an unsupported size and goes on with the boot process >> without even doing a read for a partition table. >> > that's because 768 isn't a power of 2, so it's completely unsupportable. > > >> Should maybe it be >> doing the same for a 256 byte sector disk??? >> > Possibly ... I don't know what the 256 byte sector support was for ... > all I know is that whatever it was, I don't have one. > > Back in the old days, almost any scsi disk could be formatted with a 256 byte sector. At one time it probably made since to support it. But try to find one that supports that sector size today. In any case, if you can't even partition a 256 byte sector scsi disk in linux, why would the kernel still claim it supports that format? Regards Mark
On 05/30/2010 07:51 AM, Mark Hounschell wrote: > On 05/28/2010 04:25 PM, James Bottomley wrote: > >> On Fri, 2010-05-28 at 15:29 -0400, Mark Hounschell wrote: >> >> >>> On 05/28/2010 12:34 PM, bugzilla-daemon@bugzilla.kernel.org wrote: >>> >>> >>>> https://bugzilla.kernel.org/show_bug.cgi?id=16058 >>>> >>>> >>>> >>>> >>>> >>>> --- Comment #6 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org> >>>> 2010-05-28 16:34:28 --- >>>> Reply-To: James.Bottomley@suse.de >>>> >>>> On Fri, 2010-05-28 at 10:58 -0400, Alan Stern wrote: >>>> >>>> >>>> >>>>> On Fri, 28 May 2010, Mark Hounschell wrote: >>>>> >>>>> >>>>> >>>>> >>>>>> First READ(10): >>>>>> >>>>>> sde: >>>>>> ahc_calc_residual: Entered >>>>>> ahc_calc_residual: return Case 5-1 resid = 0x800 >>>>>> ahc_calc_residual: return Case 5-2 resid = 0x800 >>>>>> >>>>>> scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 0x00 >>>>>> 0x00 0x00 0x08 0x00 >>>>>> cmd->result = 0x00000000 >>>>>> good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 >>>>>> New good_bytes = 0x0 >>>>>> scsi_finish_command: Complete >>>>>> >>>>>> From here it just keeps repeating this read of 8 blocks. (2048 bytes) so >>>>>> it looks like the machine is hung. >>>>>> >>>>>> >>>>>> >>>>> Probably not hung, just doing a lot of retries. It should time out >>>>> eventually, but it might take a long time (perhaps as long as 15 >>>>> minutes). The combination of the block layer and the SCSI layer isn't >>>>> very good at knowing when to give up. >>>>> >>>>> >>>>> >>>> Actually, I think this is a partition read. Each partition manager >>>> tends to read a page through the page cache. If we get an error, we >>>> seem to re-read to fill the cache. >>>> >>>> >>>> >>>> >>>>>> Now, I know for a fact that _if_ this read CDB is actually being sent to >>>>>> the drive, it's actual residual count will be zero. These are working >>>>>> disks and that read CDB is valid. >>>>>> >>>>>> Why is ahc_calc_residual saying that the residual count is as though the >>>>>> read never took place? I noticed that the first read on all the SATA >>>>>> drives was for 4096 bytes, why is this one only 2048? Should it have >>>>>> been 4096 and ahc_calc_residual assume that? >>>>>> >>>>>> >>>>>> >>>>> I don't know the answer to any of these questions. They could well be >>>>> due to bugs in the driver, and I know nothing about how the aic7xxx >>>>> driver works. You should talk to someone who does. >>>>> >>>>> >>>>> >>>> I'll take this one ... although we're a bit lacking in documentation for >>>> this driver. >>>> >>>> I think the 2048 is because something is hardcoded to think 8 sectors is >>>> a page. >>>> >>>> James >>>> >>>> >>>> >>>> >>> Your probably right. But is a 256 byte sector really a supported sector >>> size for a linux fs on a SCSI disk? >>> >>> >> In theory the block layer can support any power of two sector size (or >> really any sector size which is a divisor of the page size). We had a >> use for 256 byte sectors once, so they're in SCSI. In practice, since >> they're so rare, the code paths are never tested (as you found out) and >> there's a more annoying problem which is since the linux base sector >> size is 512, you have to multiply to get from 256 to 512 ... for all >> other sector sizes you have to divide, so any conversion routine that >> only right shifts would get this wrong. >> >> >> > from the fdisk man page: > > -b sectorsize Specify the sector size of the disk. Valid > values are 512, 1024, 2048 or 4096. (Recent kernels know the sector > size. Use this only on old kernels or to override the kernel's ideas.) > > So how does one create a linux fs on a 256 byte sectored disk? > > >>> When it sees a 768 byte sector disk, >>> it says it's an unsupported size and goes on with the boot process >>> without even doing a read for a partition table. >>> >>> >> that's because 768 isn't a power of 2, so it's completely unsupportable. >> >> >> >>> Should maybe it be >>> doing the same for a 256 byte sector disk??? >>> >>> >> Possibly ... I don't know what the 256 byte sector support was for ... >> all I know is that whatever it was, I don't have one. >> >> >> > Back in the old days, almost any scsi disk could be formatted with a 256 > byte sector. At one time it probably made since to support it. But try > to find one that supports that sector size today. > > In any case, if you can't even partition a 256 byte sector scsi disk in > linux, why would the kernel still claim it supports that format? > > In fact, the attached patch works for me. However, if you wish to pursue functional 256 byte sector support, I have plenty of these disks and will be happy to test what ever you come up with. Not a lot I can really do without fdisk support though. Even so, I'm all ears??? Regards Mark
Reply-To: James.Bottomley@suse.de On Mon, 2010-05-31 at 07:25 -0400, Mark Hounschell wrote: > On 05/30/2010 07:51 AM, Mark Hounschell wrote: > > On 05/28/2010 04:25 PM, James Bottomley wrote: > > > >> On Fri, 2010-05-28 at 15:29 -0400, Mark Hounschell wrote: > >> > >> > >>> On 05/28/2010 12:34 PM, bugzilla-daemon@bugzilla.kernel.org wrote: > >>> > >>> > >>>> https://bugzilla.kernel.org/show_bug.cgi?id=16058 > >>>> > >>>> > >>>> > >>>> > >>>> > >>>> --- Comment #6 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org> > 2010-05-28 16:34:28 --- > >>>> Reply-To: James.Bottomley@suse.de > >>>> > >>>> On Fri, 2010-05-28 at 10:58 -0400, Alan Stern wrote: > >>>> > >>>> > >>>> > >>>>> On Fri, 28 May 2010, Mark Hounschell wrote: > >>>>> > >>>>> > >>>>> > >>>>> > >>>>>> First READ(10): > >>>>>> > >>>>>> sde: > >>>>>> ahc_calc_residual: Entered > >>>>>> ahc_calc_residual: return Case 5-1 resid = 0x800 > >>>>>> ahc_calc_residual: return Case 5-2 resid = 0x800 > >>>>>> > >>>>>> scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 0x00 > >>>>>> 0x00 0x00 0x08 0x00 > >>>>>> cmd->result = 0x00000000 > >>>>>> good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 > >>>>>> New good_bytes = 0x0 > >>>>>> scsi_finish_command: Complete > >>>>>> > >>>>>> From here it just keeps repeating this read of 8 blocks. (2048 bytes) > so > >>>>>> it looks like the machine is hung. > >>>>>> > >>>>>> > >>>>>> > >>>>> Probably not hung, just doing a lot of retries. It should time out > >>>>> eventually, but it might take a long time (perhaps as long as 15 > >>>>> minutes). The combination of the block layer and the SCSI layer isn't > >>>>> very good at knowing when to give up. > >>>>> > >>>>> > >>>>> > >>>> Actually, I think this is a partition read. Each partition manager > >>>> tends to read a page through the page cache. If we get an error, we > >>>> seem to re-read to fill the cache. > >>>> > >>>> > >>>> > >>>> > >>>>>> Now, I know for a fact that _if_ this read CDB is actually being sent > to > >>>>>> the drive, it's actual residual count will be zero. These are working > >>>>>> disks and that read CDB is valid. > >>>>>> > >>>>>> Why is ahc_calc_residual saying that the residual count is as though > the > >>>>>> read never took place? I noticed that the first read on all the SATA > >>>>>> drives was for 4096 bytes, why is this one only 2048? Should it have > >>>>>> been 4096 and ahc_calc_residual assume that? > >>>>>> > >>>>>> > >>>>>> > >>>>> I don't know the answer to any of these questions. They could well be > >>>>> due to bugs in the driver, and I know nothing about how the aic7xxx > >>>>> driver works. You should talk to someone who does. > >>>>> > >>>>> > >>>>> > >>>> I'll take this one ... although we're a bit lacking in documentation for > >>>> this driver. > >>>> > >>>> I think the 2048 is because something is hardcoded to think 8 sectors is > >>>> a page. > >>>> > >>>> James > >>>> > >>>> > >>>> > >>>> > >>> Your probably right. But is a 256 byte sector really a supported sector > >>> size for a linux fs on a SCSI disk? > >>> > >>> > >> In theory the block layer can support any power of two sector size (or > >> really any sector size which is a divisor of the page size). We had a > >> use for 256 byte sectors once, so they're in SCSI. In practice, since > >> they're so rare, the code paths are never tested (as you found out) and > >> there's a more annoying problem which is since the linux base sector > >> size is 512, you have to multiply to get from 256 to 512 ... for all > >> other sector sizes you have to divide, so any conversion routine that > >> only right shifts would get this wrong. > >> > >> > >> > > from the fdisk man page: > > > > -b sectorsize Specify the sector size of the disk. Valid > > values are 512, 1024, 2048 or 4096. (Recent kernels know the sector > > size. Use this only on old kernels or to override the kernel's ideas.) > > > > So how does one create a linux fs on a 256 byte sectored disk? > > > > > >>> When it sees a 768 byte sector disk, > >>> it says it's an unsupported size and goes on with the boot process > >>> without even doing a read for a partition table. > >>> > >>> > >> that's because 768 isn't a power of 2, so it's completely unsupportable. > >> > >> > >> > >>> Should maybe it be > >>> doing the same for a 256 byte sector disk??? > >>> > >>> > >> Possibly ... I don't know what the 256 byte sector support was for ... > >> all I know is that whatever it was, I don't have one. > >> > >> > >> > > Back in the old days, almost any scsi disk could be formatted with a 256 > > byte sector. At one time it probably made since to support it. But try > > to find one that supports that sector size today. > > > > In any case, if you can't even partition a 256 byte sector scsi disk in > > linux, why would the kernel still claim it supports that format? > > > > > > In fact, the attached patch works for me. However, if you wish to pursue > functional 256 byte sector support, I have plenty of these disks and > will be happy to test what ever you come up with. Um, well, since you've got a lot of them that does rather argue against their being obsolete ... > Not a lot I can really > do without fdisk support though. Even so, I'm all ears??? fdisk is only the dos label ... there's a lot you can't do with a dos label. I think parted will allow you to write a label that will work. I've got scsi_debug patched to work with 256 byte sectors. It actually looks like this has nothing to do with the residue. What I see is a hang because block is trying to do a zero sized read. I suspect something is trying to do a single sector read, which is impossible since the linux native sector size is 512 and it's getting rounded down. This might, of course, argue that block cannot now support 256 sector devices and so they need to be deprecated ... I'll see. James
On 05/31/2010 10:02 AM, James Bottomley wrote: > On Mon, 2010-05-31 at 07:25 -0400, Mark Hounschell wrote: > >> On 05/30/2010 07:51 AM, Mark Hounschell wrote: >> >>> On 05/28/2010 04:25 PM, James Bottomley wrote: >>> >>> >>>> On Fri, 2010-05-28 at 15:29 -0400, Mark Hounschell wrote: >>>> >>>> >>>> >>>>> On 05/28/2010 12:34 PM, bugzilla-daemon@bugzilla.kernel.org wrote: >>>>> >>>>> >>>>> >>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=16058 >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> --- Comment #6 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org> >>>>>> 2010-05-28 16:34:28 --- >>>>>> Reply-To: James.Bottomley@suse.de >>>>>> >>>>>> On Fri, 2010-05-28 at 10:58 -0400, Alan Stern wrote: >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>> On Fri, 28 May 2010, Mark Hounschell wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>>> First READ(10): >>>>>>>> >>>>>>>> sde: >>>>>>>> ahc_calc_residual: Entered >>>>>>>> ahc_calc_residual: return Case 5-1 resid = 0x800 >>>>>>>> ahc_calc_residual: return Case 5-2 resid = 0x800 >>>>>>>> >>>>>>>> scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 0x00 >>>>>>>> 0x00 0x00 0x08 0x00 >>>>>>>> cmd->result = 0x00000000 >>>>>>>> good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 >>>>>>>> New good_bytes = 0x0 >>>>>>>> scsi_finish_command: Complete >>>>>>>> >>>>>>>> From here it just keeps repeating this read of 8 blocks. (2048 bytes) >>>>>>>> so >>>>>>>> it looks like the machine is hung. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> Probably not hung, just doing a lot of retries. It should time out >>>>>>> eventually, but it might take a long time (perhaps as long as 15 >>>>>>> minutes). The combination of the block layer and the SCSI layer isn't >>>>>>> very good at knowing when to give up. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> Actually, I think this is a partition read. Each partition manager >>>>>> tends to read a page through the page cache. If we get an error, we >>>>>> seem to re-read to fill the cache. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>> Now, I know for a fact that _if_ this read CDB is actually being sent >>>>>>>> to >>>>>>>> the drive, it's actual residual count will be zero. These are working >>>>>>>> disks and that read CDB is valid. >>>>>>>> >>>>>>>> Why is ahc_calc_residual saying that the residual count is as though >>>>>>>> the >>>>>>>> read never took place? I noticed that the first read on all the SATA >>>>>>>> drives was for 4096 bytes, why is this one only 2048? Should it have >>>>>>>> been 4096 and ahc_calc_residual assume that? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> I don't know the answer to any of these questions. They could well be >>>>>>> due to bugs in the driver, and I know nothing about how the aic7xxx >>>>>>> driver works. You should talk to someone who does. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> I'll take this one ... although we're a bit lacking in documentation for >>>>>> this driver. >>>>>> >>>>>> I think the 2048 is because something is hardcoded to think 8 sectors is >>>>>> a page. >>>>>> >>>>>> James >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>> Your probably right. But is a 256 byte sector really a supported sector >>>>> size for a linux fs on a SCSI disk? >>>>> >>>>> >>>>> >>>> In theory the block layer can support any power of two sector size (or >>>> really any sector size which is a divisor of the page size). We had a >>>> use for 256 byte sectors once, so they're in SCSI. In practice, since >>>> they're so rare, the code paths are never tested (as you found out) and >>>> there's a more annoying problem which is since the linux base sector >>>> size is 512, you have to multiply to get from 256 to 512 ... for all >>>> other sector sizes you have to divide, so any conversion routine that >>>> only right shifts would get this wrong. >>>> >>>> >>>> >>>> >>> from the fdisk man page: >>> >>> -b sectorsize Specify the sector size of the disk. Valid >>> values are 512, 1024, 2048 or 4096. (Recent kernels know the sector >>> size. Use this only on old kernels or to override the kernel's ideas.) >>> >>> So how does one create a linux fs on a 256 byte sectored disk? >>> >>> >>> >>>>> When it sees a 768 byte sector disk, >>>>> it says it's an unsupported size and goes on with the boot process >>>>> without even doing a read for a partition table. >>>>> >>>>> >>>>> >>>> that's because 768 isn't a power of 2, so it's completely unsupportable. >>>> >>>> >>>> >>>> >>>>> Should maybe it be >>>>> doing the same for a 256 byte sector disk??? >>>>> >>>>> >>>>> >>>> Possibly ... I don't know what the 256 byte sector support was for ... >>>> all I know is that whatever it was, I don't have one. >>>> >>>> >>>> >>>> >>> Back in the old days, almost any scsi disk could be formatted with a 256 >>> byte sector. At one time it probably made since to support it. But try >>> to find one that supports that sector size today. >>> >>> In any case, if you can't even partition a 256 byte sector scsi disk in >>> linux, why would the kernel still claim it supports that format? >>> >>> >>> >> In fact, the attached patch works for me. However, if you wish to pursue >> functional 256 byte sector support, I have plenty of these disks and >> will be happy to test what ever you come up with. >> > Um, well, since you've got a lot of them that does rather argue against > their being obsolete ... > > Except I would _never_ attempt to use any of them for an actual Linux fs. If I did, and again I wouldn't, it would be after formatting them with a 512 byte sector. Way too slow and small. We only provide support for them in an emulation of an old RTOS called MPX-32 using the sg_io interface. >> Not a lot I can really >> do without fdisk support though. Even so, I'm all ears??? >> > fdisk is only the dos label ... there's a lot you can't do with a dos > label. I think parted will allow you to write a label that will work. > > I've got scsi_debug patched to work with 256 byte sectors. It actually > looks like this has nothing to do with the residue. What I see is a > hang because block is trying to do a zero sized read. I suspect > something is trying to do a single sector read, which is impossible > since the linux native sector size is 512 and it's getting rounded down. > > This might, of course, argue that block cannot now support 256 sector > devices and so they need to be deprecated ... I'll see. > > James > > > >
On 05/31/2010 11:17 AM, Mark Hounschell wrote: > On 05/31/2010 10:02 AM, James Bottomley wrote: > >> On Mon, 2010-05-31 at 07:25 -0400, Mark Hounschell wrote: >> >> >>> On 05/30/2010 07:51 AM, Mark Hounschell wrote: >>> >>> >>>> On 05/28/2010 04:25 PM, James Bottomley wrote: >>>> >>>> >>>> >>>>> On Fri, 2010-05-28 at 15:29 -0400, Mark Hounschell wrote: >>>>> >>>>> >>>>> >>>>> >>>>>> On 05/28/2010 12:34 PM, bugzilla-daemon@bugzilla.kernel.org wrote: >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=16058 >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> --- Comment #6 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org> >>>>>>> 2010-05-28 16:34:28 --- >>>>>>> Reply-To: James.Bottomley@suse.de >>>>>>> >>>>>>> On Fri, 2010-05-28 at 10:58 -0400, Alan Stern wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>>> On Fri, 28 May 2010, Mark Hounschell wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>> First READ(10): >>>>>>>>> >>>>>>>>> sde: >>>>>>>>> ahc_calc_residual: Entered >>>>>>>>> ahc_calc_residual: return Case 5-1 resid = 0x800 >>>>>>>>> ahc_calc_residual: return Case 5-2 resid = 0x800 >>>>>>>>> >>>>>>>>> scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 >>>>>>>>> 0x00 >>>>>>>>> 0x00 0x00 0x08 0x00 >>>>>>>>> cmd->result = 0x00000000 >>>>>>>>> good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 >>>>>>>>> New good_bytes = 0x0 >>>>>>>>> scsi_finish_command: Complete >>>>>>>>> >>>>>>>>> From here it just keeps repeating this read of 8 blocks. (2048 bytes) >>>>>>>>> so >>>>>>>>> it looks like the machine is hung. >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>> Probably not hung, just doing a lot of retries. It should time out >>>>>>>> eventually, but it might take a long time (perhaps as long as 15 >>>>>>>> minutes). The combination of the block layer and the SCSI layer isn't >>>>>>>> very good at knowing when to give up. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> Actually, I think this is a partition read. Each partition manager >>>>>>> tends to read a page through the page cache. If we get an error, we >>>>>>> seem to re-read to fill the cache. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>>>> Now, I know for a fact that _if_ this read CDB is actually being sent >>>>>>>>> to >>>>>>>>> the drive, it's actual residual count will be zero. These are working >>>>>>>>> disks and that read CDB is valid. >>>>>>>>> >>>>>>>>> Why is ahc_calc_residual saying that the residual count is as though >>>>>>>>> the >>>>>>>>> read never took place? I noticed that the first read on all the SATA >>>>>>>>> drives was for 4096 bytes, why is this one only 2048? Should it have >>>>>>>>> been 4096 and ahc_calc_residual assume that? >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>> I don't know the answer to any of these questions. They could well be >>>>>>>> due to bugs in the driver, and I know nothing about how the aic7xxx >>>>>>>> driver works. You should talk to someone who does. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> I'll take this one ... although we're a bit lacking in documentation >>>>>>> for >>>>>>> this driver. >>>>>>> >>>>>>> I think the 2048 is because something is hardcoded to think 8 sectors >>>>>>> is >>>>>>> a page. >>>>>>> >>>>>>> James >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> Your probably right. But is a 256 byte sector really a supported sector >>>>>> size for a linux fs on a SCSI disk? >>>>>> >>>>>> >>>>>> >>>>>> >>>>> In theory the block layer can support any power of two sector size (or >>>>> really any sector size which is a divisor of the page size). We had a >>>>> use for 256 byte sectors once, so they're in SCSI. In practice, since >>>>> they're so rare, the code paths are never tested (as you found out) and >>>>> there's a more annoying problem which is since the linux base sector >>>>> size is 512, you have to multiply to get from 256 to 512 ... for all >>>>> other sector sizes you have to divide, so any conversion routine that >>>>> only right shifts would get this wrong. >>>>> >>>>> >>>>> >>>>> >>>>> >>>> from the fdisk man page: >>>> >>>> -b sectorsize Specify the sector size of the disk. Valid >>>> values are 512, 1024, 2048 or 4096. (Recent kernels know the sector >>>> size. Use this only on old kernels or to override the kernel's ideas.) >>>> >>>> So how does one create a linux fs on a 256 byte sectored disk? >>>> >>>> >>>> >>>> >>>>>> When it sees a 768 byte sector disk, >>>>>> it says it's an unsupported size and goes on with the boot process >>>>>> without even doing a read for a partition table. >>>>>> >>>>>> >>>>>> >>>>>> >>>>> that's because 768 isn't a power of 2, so it's completely unsupportable. >>>>> >>>>> >>>>> >>>>> >>>>> >>>>>> Should maybe it be >>>>>> doing the same for a 256 byte sector disk??? >>>>>> >>>>>> >>>>>> >>>>>> >>>>> Possibly ... I don't know what the 256 byte sector support was for ... >>>>> all I know is that whatever it was, I don't have one. >>>>> >>>>> >>>>> >>>>> >>>>> >>>> Back in the old days, almost any scsi disk could be formatted with a 256 >>>> byte sector. At one time it probably made since to support it. But try >>>> to find one that supports that sector size today. >>>> >>>> In any case, if you can't even partition a 256 byte sector scsi disk in >>>> linux, why would the kernel still claim it supports that format? >>>> >>>> >>>> >>>> >>> In fact, the attached patch works for me. However, if you wish to pursue >>> functional 256 byte sector support, I have plenty of these disks and >>> will be happy to test what ever you come up with. >>> >>> >> Um, well, since you've got a lot of them that does rather argue against >> their being obsolete ... >> >> >> > Except I would _never_ attempt to use any of them for an actual Linux > fs. If I did, and again I wouldn't, it would be after formatting them > with a 512 byte sector. Way too slow and small. We only provide support > for them in an emulation of an old RTOS called MPX-32 using the sg_io > interface. > > >>> Not a lot I can really >>> do without fdisk support though. Even so, I'm all ears??? >>> >>> >> fdisk is only the dos label ... there's a lot you can't do with a dos >> label. I think parted will allow you to write a label that will work. >> >> I've got scsi_debug patched to work with 256 byte sectors. It actually >> looks like this has nothing to do with the residue. What I see is a >> hang because block is trying to do a zero sized read. I suspect >> something is trying to do a single sector read, which is impossible >> since the linux native sector size is 512 and it's getting rounded down. >> >> This might, of course, argue that block cannot now support 256 sector >> devices and so they need to be deprecated ... I'll see. >> >> James >> I know your a busy guy, I was just wondering if this BUG is still being given consideration? Thanks Mark
Reply-To: James.Bottomley@suse.de On Thu, 2010-06-17 at 07:04 -0400, Mark Hounschell wrote: > On 05/31/2010 11:17 AM, Mark Hounschell wrote: > > On 05/31/2010 10:02 AM, James Bottomley wrote: > > > >> On Mon, 2010-05-31 at 07:25 -0400, Mark Hounschell wrote: > >> > >> > >>> On 05/30/2010 07:51 AM, Mark Hounschell wrote: > >>> > >>> > >>>> On 05/28/2010 04:25 PM, James Bottomley wrote: > >>>> > >>>> > >>>> > >>>>> On Fri, 2010-05-28 at 15:29 -0400, Mark Hounschell wrote: > >>>>> > >>>>> > >>>>> > >>>>> > >>>>>> On 05/28/2010 12:34 PM, bugzilla-daemon@bugzilla.kernel.org wrote: > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=16058 > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> --- Comment #6 from Anonymous Emailer > <anonymous@kernel-bugs.osdl.org> 2010-05-28 16:34:28 --- > >>>>>>> Reply-To: James.Bottomley@suse.de > >>>>>>> > >>>>>>> On Fri, 2010-05-28 at 10:58 -0400, Alan Stern wrote: > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>>> On Fri, 28 May 2010, Mark Hounschell wrote: > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>>> First READ(10): > >>>>>>>>> > >>>>>>>>> sde: > >>>>>>>>> ahc_calc_residual: Entered > >>>>>>>>> ahc_calc_residual: return Case 5-1 resid = 0x800 > >>>>>>>>> ahc_calc_residual: return Case 5-2 resid = 0x800 > >>>>>>>>> > >>>>>>>>> scsi_finish_command: Entered for cmd(10):0x28 0x00 0x00 0x00 0x00 > 0x00 > >>>>>>>>> 0x00 0x00 0x08 0x00 > >>>>>>>>> cmd->result = 0x00000000 > >>>>>>>>> good_bytes == old_good_bytes = 0x800 scsi_get_resid(cmd) = 0x800 > >>>>>>>>> New good_bytes = 0x0 > >>>>>>>>> scsi_finish_command: Complete > >>>>>>>>> > >>>>>>>>> From here it just keeps repeating this read of 8 blocks. (2048 > bytes) so > >>>>>>>>> it looks like the machine is hung. > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>> Probably not hung, just doing a lot of retries. It should time out > >>>>>>>> eventually, but it might take a long time (perhaps as long as 15 > >>>>>>>> minutes). The combination of the block layer and the SCSI layer > isn't > >>>>>>>> very good at knowing when to give up. > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>> Actually, I think this is a partition read. Each partition manager > >>>>>>> tends to read a page through the page cache. If we get an error, we > >>>>>>> seem to re-read to fill the cache. > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>>>> Now, I know for a fact that _if_ this read CDB is actually being > sent to > >>>>>>>>> the drive, it's actual residual count will be zero. These are > working > >>>>>>>>> disks and that read CDB is valid. > >>>>>>>>> > >>>>>>>>> Why is ahc_calc_residual saying that the residual count is as > though the > >>>>>>>>> read never took place? I noticed that the first read on all the > SATA > >>>>>>>>> drives was for 4096 bytes, why is this one only 2048? Should it > have > >>>>>>>>> been 4096 and ahc_calc_residual assume that? > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>> I don't know the answer to any of these questions. They could well > be > >>>>>>>> due to bugs in the driver, and I know nothing about how the aic7xxx > >>>>>>>> driver works. You should talk to someone who does. > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>> I'll take this one ... although we're a bit lacking in documentation > for > >>>>>>> this driver. > >>>>>>> > >>>>>>> I think the 2048 is because something is hardcoded to think 8 sectors > is > >>>>>>> a page. > >>>>>>> > >>>>>>> James > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>> Your probably right. But is a 256 byte sector really a supported > sector > >>>>>> size for a linux fs on a SCSI disk? > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>> In theory the block layer can support any power of two sector size (or > >>>>> really any sector size which is a divisor of the page size). We had a > >>>>> use for 256 byte sectors once, so they're in SCSI. In practice, since > >>>>> they're so rare, the code paths are never tested (as you found out) and > >>>>> there's a more annoying problem which is since the linux base sector > >>>>> size is 512, you have to multiply to get from 256 to 512 ... for all > >>>>> other sector sizes you have to divide, so any conversion routine that > >>>>> only right shifts would get this wrong. > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>> from the fdisk man page: > >>>> > >>>> -b sectorsize Specify the sector size of the disk. Valid > >>>> values are 512, 1024, 2048 or 4096. (Recent kernels know the sector > >>>> size. Use this only on old kernels or to override the kernel's ideas.) > >>>> > >>>> So how does one create a linux fs on a 256 byte sectored disk? > >>>> > >>>> > >>>> > >>>> > >>>>>> When it sees a 768 byte sector disk, > >>>>>> it says it's an unsupported size and goes on with the boot process > >>>>>> without even doing a read for a partition table. > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>> that's because 768 isn't a power of 2, so it's completely > unsupportable. > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>>> Should maybe it be > >>>>>> doing the same for a 256 byte sector disk??? > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>> Possibly ... I don't know what the 256 byte sector support was for ... > >>>>> all I know is that whatever it was, I don't have one. > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>> Back in the old days, almost any scsi disk could be formatted with a 256 > >>>> byte sector. At one time it probably made since to support it. But try > >>>> to find one that supports that sector size today. > >>>> > >>>> In any case, if you can't even partition a 256 byte sector scsi disk in > >>>> linux, why would the kernel still claim it supports that format? > >>>> > >>>> > >>>> > >>>> > >>> In fact, the attached patch works for me. However, if you wish to pursue > >>> functional 256 byte sector support, I have plenty of these disks and > >>> will be happy to test what ever you come up with. > >>> > >>> > >> Um, well, since you've got a lot of them that does rather argue against > >> their being obsolete ... > >> > >> > >> > > Except I would _never_ attempt to use any of them for an actual Linux > > fs. If I did, and again I wouldn't, it would be after formatting them > > with a 512 byte sector. Way too slow and small. We only provide support > > for them in an emulation of an old RTOS called MPX-32 using the sg_io > > interface. > > > > > >>> Not a lot I can really > >>> do without fdisk support though. Even so, I'm all ears??? > >>> > >>> > >> fdisk is only the dos label ... there's a lot you can't do with a dos > >> label. I think parted will allow you to write a label that will work. > >> > >> I've got scsi_debug patched to work with 256 byte sectors. It actually > >> looks like this has nothing to do with the residue. What I see is a > >> hang because block is trying to do a zero sized read. I suspect > >> something is trying to do a single sector read, which is impossible > >> since the linux native sector size is 512 and it's getting rounded down. > >> > >> This might, of course, argue that block cannot now support 256 sector > >> devices and so they need to be deprecated ... I'll see. > >> > >> James > >> > > I know your a busy guy, I was just wondering if this BUG is still being > given consideration? Yes, but it got lost in the merge window. I was investigating where the break is ... since the whole of block has allowances for 256 byte sector devices, it seems that something once used it. James
This bug is against obsolete kernel. Please try with newer kernel to see if it's fixed. Cheers Nick
This bug is still valid. A 256 byte sector disk will cause kernel-4.0.2 to hang. Every since this bug was reported I have rolled my own patch that causes 256 byte sector disk to be unsupported for a linux fs. I use these disks in raw mode using sg3 API only. No one would ever use these disks for a linux fs. I would be happy to submit this patch. Mark
It would be good to get this fixed so if you have a patch it would be good to get it upstream. The only users I know of 256 byte/sector are a few ancient USB devices and also retro-computing folk . For the retro stuff the file systems are not native Linux anyway so requiring sg wouldn't be a problem.
Created attachment 176501 [details] make scsi disk 256 byte sector unsupported for linux filesystems This patch makes 256 byte sector disks unsupported for linux fs. Since kernel 2.6.x or so I have been unable to boot with a 256 byte sector installed.
Feel free to add my signed off by: Signed-off-by: Mark Hounschell <dmarkh@cfl.rr.com>