[PATCH] ide-cd: document capacity hack

[PATCH] ide-cd: document capacity hack

[Bartlomiej Zolnierkiewicz]

From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Subject: [PATCH] ide-cd: document capacity hack

Just copy the comment from drivers/scsi/sr.c::sr_done()
(from which the capacity hack has been originated).

Cc: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
---
 drivers/ide/ide-cd.c |    8 ++++++++
 1 file changed, 8 insertions(+)

Index: b/drivers/ide/ide-cd.c
===================================================================
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -189,6 +189,14 @@ static void cdrom_analyze_sense_data(ide
 			bio_sectors = max(bio_sectors(failed_command->bio), 4U);
 			sector &= ~(bio_sectors - 1);
 
+			/*
+			 * The SCSI specification allows for the value
+			 * returned by READ CAPACITY to be up to 75 2K
+			 * sectors past the last readable block.
+			 * Therefore, if we hit a medium error within the
+			 * last 75 2K sectors, we decrease the saved size
+			 * value.
+			 */
 			if (sector < get_capacity(info->disk) &&
 			    drive->probed_capacity - sector < 4 * 75)
 				set_capacity(info->disk, sector);

Re: [PATCH] ide-cd: document capacity hack

[Sergei Shtylyov]

Hello.

Bartlomiej Zolnierkiewicz wrote:

> Just copy the comment from drivers/scsi/sr.c::sr_done()
> (from which the capacity hack has been originated).

> Cc: Borislav Petkov <petkovbb@gmail.com>
> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>

> Index: b/drivers/ide/ide-cd.c
> ===================================================================
> --- a/drivers/ide/ide-cd.c
> +++ b/drivers/ide/ide-cd.c
> @@ -189,6 +189,14 @@ static void cdrom_analyze_sense_data(ide
>  			bio_sectors = max(bio_sectors(failed_command->bio), 4U);
>  			sector &= ~(bio_sectors - 1);
>  
> +			/*
> +			 * The SCSI specification allows for the value
> +			 * returned by READ CAPACITY to be up to 75 2K
> +			 * sectors past the last readable block.

    Oh horror... :-)

> +			 * Therefore, if we hit a medium error within the
> +			 * last 75 2K sectors, we decrease the saved size
> +			 * value.
> +			 */
>  			if (sector < get_capacity(info->disk) &&
>  			    drive->probed_capacity - sector < 4 * 75)
>  				set_capacity(info->disk, sector);

    Would be nice if the CHS capacity workround was finally documented too? ;-)

MBR, Sergei

Re: [PATCH] ide-cd: document capacity hack

[Bartlomiej Zolnierkiewicz]

On Wednesday 18 February 2009, Sergei Shtylyov wrote:
> Hello.
> 
> Bartlomiej Zolnierkiewicz wrote:
> 
> > Just copy the comment from drivers/scsi/sr.c::sr_done()
> > (from which the capacity hack has been originated).
> 
> > Cc: Borislav Petkov <petkovbb@gmail.com>
> > Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> 
> Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
> 
> > Index: b/drivers/ide/ide-cd.c
> > ===================================================================
> > --- a/drivers/ide/ide-cd.c
> > +++ b/drivers/ide/ide-cd.c
> > @@ -189,6 +189,14 @@ static void cdrom_analyze_sense_data(ide
> >  			bio_sectors = max(bio_sectors(failed_command->bio), 4U);
> >  			sector &= ~(bio_sectors - 1);
> >  
> > +			/*
> > +			 * The SCSI specification allows for the value
> > +			 * returned by READ CAPACITY to be up to 75 2K
> > +			 * sectors past the last readable block.
> 
>     Oh horror... :-)
> 
> > +			 * Therefore, if we hit a medium error within the
> > +			 * last 75 2K sectors, we decrease the saved size
> > +			 * value.
> > +			 */
> >  			if (sector < get_capacity(info->disk) &&
> >  			    drive->probed_capacity - sector < 4 * 75)
> >  				set_capacity(info->disk, sector);
> 
>     Would be nice if the CHS capacity workround was finally documented too? ;-)

Send patches.  I have my hands full of work...