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* [PATCH] blockdev: Don't fail on missing start sector
@ 2020-05-31 23:35 Stanislav Brabec
  2020-06-01  8:13 ` Karel Zak
  2020-06-03 15:16 ` Karel Zak
  0 siblings, 2 replies; 6+ messages in thread
From: Stanislav Brabec @ 2020-05-31 23:35 UTC (permalink / raw)
  To: util-linux; +Cc: Martin Wilck

Device mapper devices don't provide start sector.

It causes "blockdev --report" error:
blockdev: /dev/dm-9: failed to read partition start from sysfs: No such
file or directory

There is no reliable way to detect a geometry in this case.
Report N/A instead.

Signed-off-by: Stanislav Brabec <sbrabec@suse.cz>
Cc: Martin Wilck <martin.wilck@suse.com>
---
 disk-utils/blockdev.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/disk-utils/blockdev.c b/disk-utils/blockdev.c
index f1067c815..ab18cfa66 100644
--- a/disk-utils/blockdev.c
+++ b/disk-utils/blockdev.c
@@ -455,6 +455,7 @@ static void report_device(char *device, int quiet)
     long ra;
     unsigned long long bytes;
     uint64_t start = 0;
+    char start_str[11] = "";
     struct stat st;
 
     fd = open(device, O_RDONLY | O_NONBLOCK);
@@ -476,19 +477,21 @@ static void report_device(char *device, int quiet)
             disk != st.st_rdev) {
 
             if (ul_path_read_u64(pc, &start, "start") != 0)
-                err(EXIT_FAILURE,
-                    _("%s: failed to read partition start from sysfs"),
-                    device);
+                /* TRANSLATORS: Start sector not available. Max. 10
letters. */
+                sprintf(start_str, "%10s", _("N/A"));
         }
         ul_unref_path(pc);
     }
+    if (start_str[0] == 0)
+        sprintf(start_str, "%10ju", start);
+
     if (ioctl(fd, BLKROGET, &ro) == 0 &&
         ioctl(fd, BLKRAGET, &ra) == 0 &&
         ioctl(fd, BLKSSZGET, &ssz) == 0 &&
         ioctl(fd, BLKBSZGET, &bsz) == 0 &&
         blkdev_get_size(fd, &bytes) == 0) {
-        printf("%s %5ld %5d %5d %10ju %15lld   %s\n",
-               ro ? "ro" : "rw", ra, ssz, bsz, start, bytes, device);
+        printf("%s %5ld %5d %5d %s %15lld   %s\n",
+               ro ? "ro" : "rw", ra, ssz, bsz, start_str, bytes, device);
     } else {
         if (!quiet)
             warnx(_("ioctl error on %s"), device);
-- 
2.25.1

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
---------------------------------------------------------------------
SUSE LINUX, s. r. o.                         e-mail: sbrabec@suse.com
Křižíkova 148/34 (Corso IIa)                    tel: +420 284 084 060
186 00 Praha 8-Karlín                          fax:  +420 284 084 001
Czech Republic                                    http://www.suse.cz/
PGP: 830B 40D5 9E05 35D8 5E27 6FA3 717C 209F A04F CD76



^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] blockdev: Don't fail on missing start sector
  2020-05-31 23:35 [PATCH] blockdev: Don't fail on missing start sector Stanislav Brabec
@ 2020-06-01  8:13 ` Karel Zak
  2020-06-02  1:52   ` Stanislav Brabec
  2020-06-03 15:16 ` Karel Zak
  1 sibling, 1 reply; 6+ messages in thread
From: Karel Zak @ 2020-06-01  8:13 UTC (permalink / raw)
  To: Stanislav Brabec; +Cc: util-linux, Martin Wilck

On Mon, Jun 01, 2020 at 01:35:44AM +0200, Stanislav Brabec wrote:
> Device mapper devices don't provide start sector.

for which type of the device/mapping? I'd like to reproduce this
issue.

> It causes "blockdev --report" error:
> blockdev: /dev/dm-9: failed to read partition start from sysfs: No such
> file or directory
> 
> There is no reliable way to detect a geometry in this case.
> Report N/A instead.

I guess the "start" file missing in the sysfs/ in this case, right?

>              if (ul_path_read_u64(pc, &start, "start") != 0)
> -                err(EXIT_FAILURE,
> -                    _("%s: failed to read partition start from sysfs"),
> -                    device);
> +                /* TRANSLATORS: Start sector not available. Max. 10
> letters. */
> +                sprintf(start_str, "%10s", _("N/A"));
>          }
>          ul_unref_path(pc);
>      }
> +    if (start_str[0] == 0)
> +        sprintf(start_str, "%10ju", start);


Maybe we ca use ul_path_read_buffer() rather than ul_path_read_u64() to keep 
it as string and to avoid sprintf().

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] blockdev: Don't fail on missing start sector
  2020-06-01  8:13 ` Karel Zak
@ 2020-06-02  1:52   ` Stanislav Brabec
  0 siblings, 0 replies; 6+ messages in thread
From: Stanislav Brabec @ 2020-06-02  1:52 UTC (permalink / raw)
  To: Karel Zak; +Cc: util-linux, Martin Wilck

Karel Zak wrote:
> On Mon, Jun 01, 2020 at 01:35:44AM +0200, Stanislav Brabec wrote:
>> Device mapper devices don't provide start sector.
> for which type of the device/mapping? I'd like to reproduce this
> issue.
kpartx-style partition on multipath.
>> It causes "blockdev --report" error:
>> blockdev: /dev/dm-9: failed to read partition start from sysfs: No such
>> file or directory
>>
>> There is no reliable way to detect a geometry in this case.
>> Report N/A instead.
> I guess the "start" file missing in the sysfs/ in this case, right?
Yes.

Actually, debugging shows:

sysfs_blkdev_get_wholedisk(): This function has a special code for
device mapper: If /sys/dev/block/{major}:{minor}/partition does not
exist, check for /sys/dev/block/{major}:{minor}/dm/uuid, parse the
result and attempt to check the structure. (Split by "-", check, whether
string starts by "part".) It starts with "part1" => Device mapper is
detected. => Partition is detected.

The code returns to report_device(), and because partition is detected,
it unconditionally attempts to read "start" file from
"/sys/dev/block/254:9". This fails.

>>              if (ul_path_read_u64(pc, &start, "start") != 0)
>> -                err(EXIT_FAILURE,
>> -                    _("%s: failed to read partition start from sysfs"),
>> -                    device);
>> +                /* TRANSLATORS: Start sector not available. Max. 10
>> letters. */
>> +                sprintf(start_str, "%10s", _("N/A"));
>>          }
>>          ul_unref_path(pc);
>>      }
>> +    if (start_str[0] == 0)
>> +        sprintf(start_str, "%10ju", start);
>
> Maybe we ca use ul_path_read_buffer() rather than ul_path_read_u64() to keep 
> it as string and to avoid sprintf().
This was in the original code, but your proposal makes a perfect sense.
%10ju is just a space padded original string.

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
---------------------------------------------------------------------
SUSE LINUX, s. r. o.                         e-mail: sbrabec@suse.com
Křižíkova 148/34 (Corso IIa)                    tel: +420 284 084 060
186 00 Praha 8-Karlín                          fax:  +420 284 084 001
Czech Republic                                    http://www.suse.cz/
PGP: 830B 40D5 9E05 35D8 5E27 6FA3 717C 209F A04F CD76



^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] blockdev: Don't fail on missing start sector
  2020-05-31 23:35 [PATCH] blockdev: Don't fail on missing start sector Stanislav Brabec
  2020-06-01  8:13 ` Karel Zak
@ 2020-06-03 15:16 ` Karel Zak
  2020-06-05  8:06   ` Karel Zak
  1 sibling, 1 reply; 6+ messages in thread
From: Karel Zak @ 2020-06-03 15:16 UTC (permalink / raw)
  To: Stanislav Brabec; +Cc: util-linux, Martin Wilck

On Mon, Jun 01, 2020 at 01:35:44AM +0200, Stanislav Brabec wrote:
> It causes "blockdev --report" error:
> blockdev: /dev/dm-9: failed to read partition start from sysfs: No such
> file or directory

Stanislav, can you re-send the patch by git-send-email or create PR on
git-hub? Please. It seems the patch is broken by your/my email client (or
so) :-(

Thanks!

 Applying: blockdev: Don't fail on missing start sector
 error: corrupt patch at line 10

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] blockdev: Don't fail on missing start sector
  2020-06-03 15:16 ` Karel Zak
@ 2020-06-05  8:06   ` Karel Zak
  2020-06-13 20:52     ` Stanislav Brabec
  0 siblings, 1 reply; 6+ messages in thread
From: Karel Zak @ 2020-06-05  8:06 UTC (permalink / raw)
  To: Stanislav Brabec; +Cc: util-linux, Martin Wilck

On Wed, Jun 03, 2020 at 05:16:26PM +0200, Karel Zak wrote:
> Stanislav, can you re-send the patch by git-send-email or create PR on
> git-hub? Please. It seems the patch is broken by your/my email client (or
> so) :-(

OK, applied manually. You don't need to resend it :-)

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] blockdev: Don't fail on missing start sector
  2020-06-05  8:06   ` Karel Zak
@ 2020-06-13 20:52     ` Stanislav Brabec
  0 siblings, 0 replies; 6+ messages in thread
From: Stanislav Brabec @ 2020-06-13 20:52 UTC (permalink / raw)
  To: Karel Zak; +Cc: util-linux, Martin Wilck

Dne 05. 06. 20 v 10:06 Karel Zak napsal(a):
> On Wed, Jun 03, 2020 at 05:16:26PM +0200, Karel Zak wrote:
>> Stanislav, can you re-send the patch by git-send-email or create PR on
>> git-hub? Please. It seems the patch is broken by your/my email client (or
>> so) :-(
> OK, applied manually. You don't need to resend it :-)
>
>     Karel
>
Thanks. I used a different instance of Thunderbird, and probably didn't
configure it for a proper patch work.

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
---------------------------------------------------------------------
SUSE LINUX, s. r. o.                         e-mail: sbrabec@suse.com
Křižíkova 148/34 (Corso IIa)                    tel: +420 284 084 060
186 00 Praha 8-Karlín                          fax:  +420 284 084 001
Czech Republic                                    http://www.suse.cz/
PGP: 830B 40D5 9E05 35D8 5E27 6FA3 717C 209F A04F CD76


^ permalink raw reply	[flat|nested] 6+ messages in thread

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Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-31 23:35 [PATCH] blockdev: Don't fail on missing start sector Stanislav Brabec
2020-06-01  8:13 ` Karel Zak
2020-06-02  1:52   ` Stanislav Brabec
2020-06-03 15:16 ` Karel Zak
2020-06-05  8:06   ` Karel Zak
2020-06-13 20:52     ` Stanislav Brabec

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