Re: [2.6.13-rc6-latest] SCSI disk registration msgs repeat themselves
On Tue, Aug 16, 2005 at 10:51:13PM -0700, Pete Zaitcev wrote:
> On Tue, 16 Aug 2005 21:39:33 -0700, Patrick Mansfield <[EMAIL PROTECTED]>
> wrote:
> > On Tue, Aug 16, 2005 at 11:01:30PM -0400, Chuck Ebbert wrote:
>
> > > I just added some usb-storage devices to my system and got the below.
>
> > > Why do the first four lines repeat for each device? (Not sure if
> > > this is a SCSI or USB problem.)
> >
> > It is in the partition code. I posted twice before about this with no
> > response.
>
> It's not an important problem, presumably. I observe dual revalidations
> as well, but they are not that bothersome. Add to it that your patch
Yes.
Does this *only* happens for sd (scsi) devices?
> appears wrong (see below). If you offered an acceptable solution, I would
> expect a warmer welcome... But even then getting a reply from linux-scsi
> folks is like pulling a tooth (if my own little CD-ROM sizing patch is
> any indication). So, steel yourself for challenges of this life, Patrick!
;-)
> Here's what it was in 2.6.9, as documented in drivers/block/ub.c:
>
> + /*
> + * This is a workaround for a specific problem in our block layer.
> + * In 2.6.9, register_disk duplicates the code from rescan_partitions.
> + * However, if we do add_disk with a device which persistently reports
> + * a changed media, add_disk calls register_disk, which does do_open,
> + * which will call rescan_paritions for changed media. After that,
> + * register_disk attempts to do it all again and causes double kobject
> + * registration and a eventually an oops on module removal.
> + *
> + * The bottom line is, Al Viro says that we should not allow
> + * bdev->bd_invalidated to be set when doing add_disk no matter what.
> + */
> + if (sc->first_open) {
> + if (sc->changed) {
> + sc->first_open = 0;
> + rc = -ENOMEDIUM;
> + goto err_open;
> + }
> + }
>
> Users were hitting it with oopses like these:
> http://www.ussg.iu.edu/hypermail/linux/kernel/0409.2/0011.html
>
> The ub alone was not suffient to motivate Al for the fix, so I added
> this silly "first_open" thingie, which papered over it. It was thought
> that sd was miraclously immune.
>
> However, over time users hit it with usb-storage and sd, like this:
> http://lkml.org/lkml/2004/2/21/19
> This prompted Al's action. He simply dropped all the extra code like
> this:
>
> --- linux-2.6.9-11.5.EL/fs/partitions/check.c 2004-10-18 14:55:07.0
> -0700
> +++ linux-2.6.12/fs/partitions/check.c2005-06-17 12:48:29.0
> -0700
> @@ -358,24 +357,9 @@ void register_disk(struct gendisk *disk)
> if (!bdev)
> return;
>
> + bdev->bd_invalidated = 1;
> if (blkdev_get(bdev, FMODE_READ, 0) < 0)
> return;
> - state = check_partition(disk, bdev);
> - if (state) {
> - for (j = 1; j < state->limit; j++) {
> - sector_t size = state->parts[j].size;
> - sector_t from = state->parts[j].from;
> - if (!size)
> - continue;
> - add_partition(disk, j, from, size);
> -#ifdef CONFIG_BLK_DEV_MD
> - if (!state->parts[j].flags)
> - continue;
> - md_autodetect_dev(bdev->bd_dev+j);
> -#endif
> - }
> - kfree(state);
> - }
> blkdev_put(bdev);
> }
OK, thanks for posting those links and information.
> > --- linux-2.6.11-rc1/fs/partitions/check.c Fri Dec 24 13:35:28 2004
> > +++ no-double-sd-linux-2.6.11-rc1/fs/partitions/check.c Fri Jan 21
> > 11:19:00 2005
> > @@ -375,8 +375,6 @@ int rescan_partitions(struct gendisk *di
> > bdev->bd_invalidated = 0;
> > for (p = 1; p < disk->minors; p++)
> > delete_partition(disk, p);
> > - if (disk->fops->revalidate_disk)
> > - disk->fops->revalidate_disk(disk);
>
> As for your proposed fix, it may be problematic. The ->revalidate
> method has to be called at least once for a new device, because
> that's when drivers fetch the capacities. But ->open only calls
> check_disk_change() for removable devices. Who is going to call
> ->revalidate inside add_disk() for non-removable devices?
sd.c always calls its revalidate_disk method (sd_revalidate_disk) when the
device is attached, so for scsi, we definitely do not miss anything.
I thought revalidate_disk was not called prior to Al's patch, so why do we
need to call it on the first open now?
You already have to call set_capacity() before add_disk(), else
register_disk thinks there is no media present, and won't set
bd_invalidated. So drivers must already get the capacity (or fake it)
prior to calling add_disk.
-- Patrick Mansfield
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Re: [2.6.13-rc6-latest] SCSI disk registration msgs repeat themselves
On Tue, 16 Aug 2005 21:39:33 -0700, Patrick Mansfield <[EMAIL PROTECTED]> wrote:
> On Tue, Aug 16, 2005 at 11:01:30PM -0400, Chuck Ebbert wrote:
> > I just added some usb-storage devices to my system and got the below.
> > Why do the first four lines repeat for each device? (Not sure if
> > this is a SCSI or USB problem.)
>
> It is in the partition code. I posted twice before about this with no
> response.
It's not an important problem, presumably. I observe dual revalidations
as well, but they are not that bothersome. Add to it that your patch
appears wrong (see below). If you offered an acceptable solution, I would
expect a warmer welcome... But even then getting a reply from linux-scsi
folks is like pulling a tooth (if my own little CD-ROM sizing patch is
any indication). So, steel yourself for challenges of this life, Patrick!
> The changelog said it was a workaround for a borken device, but not what
> device it was or any other details.
Here's what it was in 2.6.9, as documented in drivers/block/ub.c:
+ /*
+* This is a workaround for a specific problem in our block layer.
+* In 2.6.9, register_disk duplicates the code from rescan_partitions.
+* However, if we do add_disk with a device which persistently reports
+* a changed media, add_disk calls register_disk, which does do_open,
+* which will call rescan_paritions for changed media. After that,
+* register_disk attempts to do it all again and causes double kobject
+* registration and a eventually an oops on module removal.
+*
+* The bottom line is, Al Viro says that we should not allow
+* bdev->bd_invalidated to be set when doing add_disk no matter what.
+*/
+ if (sc->first_open) {
+ if (sc->changed) {
+ sc->first_open = 0;
+ rc = -ENOMEDIUM;
+ goto err_open;
+ }
+ }
Users were hitting it with oopses like these:
http://www.ussg.iu.edu/hypermail/linux/kernel/0409.2/0011.html
The ub alone was not suffient to motivate Al for the fix, so I added
this silly "first_open" thingie, which papered over it. It was thought
that sd was miraclously immune.
However, over time users hit it with usb-storage and sd, like this:
http://lkml.org/lkml/2004/2/21/19
This prompted Al's action. He simply dropped all the extra code like
this:
--- linux-2.6.9-11.5.EL/fs/partitions/check.c 2004-10-18 14:55:07.0
-0700
+++ linux-2.6.12/fs/partitions/check.c 2005-06-17 12:48:29.0 -0700
@@ -358,24 +357,9 @@ void register_disk(struct gendisk *disk)
if (!bdev)
return;
+ bdev->bd_invalidated = 1;
if (blkdev_get(bdev, FMODE_READ, 0) < 0)
return;
- state = check_partition(disk, bdev);
- if (state) {
- for (j = 1; j < state->limit; j++) {
- sector_t size = state->parts[j].size;
- sector_t from = state->parts[j].from;
- if (!size)
- continue;
- add_partition(disk, j, from, size);
-#ifdef CONFIG_BLK_DEV_MD
- if (!state->parts[j].flags)
- continue;
- md_autodetect_dev(bdev->bd_dev+j);
-#endif
- }
- kfree(state);
- }
blkdev_put(bdev);
}
I was just about to remove "first_open" from ub, because it's unnecessary
with Al's fix and it was getting on my nerves.
> --- linux-2.6.11-rc1/fs/partitions/check.cFri Dec 24 13:35:28 2004
> +++ no-double-sd-linux-2.6.11-rc1/fs/partitions/check.c Fri Jan 21
> 11:19:00 2005
> @@ -375,8 +375,6 @@ int rescan_partitions(struct gendisk *di
> bdev->bd_invalidated = 0;
> for (p = 1; p < disk->minors; p++)
> delete_partition(disk, p);
> - if (disk->fops->revalidate_disk)
> - disk->fops->revalidate_disk(disk);
As for your proposed fix, it may be problematic. The ->revalidate
method has to be called at least once for a new device, because
that's when drivers fetch the capacities. But ->open only calls
check_disk_change() for removable devices. Who is going to call
->revalidate inside add_disk() for non-removable devices?
-- Pete
-
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Please read the FAQ at http://www.tux.org/lkml/
Re: [2.6.13-rc6-latest] SCSI disk registration msgs repeat themselves
On Tue, Aug 16, 2005 at 11:01:30PM -0400, Chuck Ebbert wrote: > I just added some usb-storage devices to my system and got the below. > Why do the first four lines repeat for each device? (Not sure if > this is a SCSI or USB problem.) It is in the partition code. I posted twice before about this with no response. The changelog said it was a workaround for a borken device, but not what device it was or any other details. There is a patch (against 2.6.11) in the below, I haven't tried it with recent kernels: http://marc.theaimsgroup.com/?l=linux-scsi&m=110719123625593&w=2 http://marc.theaimsgroup.com/?l=linux-scsi&m=110848617107098&w=2 -- Patrick Mansfield - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[2.6.13-rc6-latest] SCSI disk registration msgs repeat themselves
I just added some usb-storage devices to my system and got the below. Why do the first four lines repeat for each device? (Not sure if this is a SCSI or USB problem.) [ 23.433725] SCSI device sda: 63424 512-byte hdwr sectors (32 MB) [ 23.560564] sda: Write Protect is off [ 23.560581] sda: Mode Sense: 02 00 00 00 [ 23.560593] sda: assuming drive cache: write through [ 23.572525] SCSI device sda: 63424 512-byte hdwr sectors (32 MB) [ 23.576504] sda: Write Protect is off [ 23.576519] sda: Mode Sense: 02 00 00 00 [ 23.576530] sda: assuming drive cache: write through [ 23.576545] sda: sda1 [ 23.583752] Attached scsi removable disk sda at scsi1, channel 0, id 0, lun 0 [ 23.583847] Attached scsi generic sg1 at scsi1, channel 0, id 0, lun 0, type 0 [ 23.584701] usb-storage: device scan complete [ 32.116248] SCSI device sdb: 196608 512-byte hdwr sectors (101 MB) [ 32.141310] sdb: Write Protect is off [ 32.153477] sdb: Mode Sense: 45 00 00 08 [ 32.153490] sdb: assuming drive cache: write through [ 32.178386] SCSI device sdb: 196608 512-byte hdwr sectors (101 MB) [ 32.204473] sdb: Write Protect is off [ 32.216654] sdb: Mode Sense: 45 00 00 08 [ 32.216735] sdb: assuming drive cache: write through [ 32.233259] sdb: sdb4 [ 32.246595] Attached scsi removable disk sdb at scsi2, channel 0, id 0, lun 0 [ 32.270348] Attached scsi generic sg2 at scsi2, channel 0, id 0, lun 0, type 0 [ 32.295843] usb-storage: device scan complete __ Chuck - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
