On Fri, 05 Dec 2014 13:28:00 +0300 Michael Tokarev <mjt@xxxxxxxxxx> wrote: > Neil, will you take the patch in this bugreport for the next version? > > http://bugs.debian.org/763917. > > Thanks, > > /mjt > > On Fri, 3 Oct 2014 20:24:54 +0200 Jan Echternach <jan@xxxxxxxxx> wrote: > > Package: mdadm > > Version: 3.3.2-1 > > Severity: minor > > Tags: patch > > > > > > While setting up a new system, I noticed an incorrect value in the output > > of mdadm --examine: > > > > Avail Dev Size : 2095080 (1023.16 MiB 1072.68 MB) > > > > The 1023.16 MiB were quite irritating because the underlying partition has > > a size of exactly 1023 MiB. > > > > The number of sectors seems plausible: 2095080 sectors * 512 bytes/sector > > are 1022.988 MiB or 1072.681 MB. I looked into the code and found an > > inaccuracy in human_size() and human_size_brief(). The formula used for > > the MiB value is essentially > > > > long cMiB = (bytes / ( (1LL<<20) / 200LL ) +1) /2; > > > > but (1LL<<20) / 200LL is not an integer. It's rounded down and cMiB becomes > > too large. The quick fix would have been multiplying by 200 before dividing > > by 1<<20, but that might cause integer overflows in the GiB case. Given that we are doing 64bit arithmetic, we would need about 56bits of bytes for there to be a rounding problem. That's 64 petabytes. I decide to just do the simple transformation. If we get arrays close to petabytes I would want to make other changes, like reporting the number of terabytes for larger arrays. Thanks, NeilBrown > > > > The following patch uses a more complicated formula that computes the > > fractional portion separately from the integer portion. It also changes some > > longs to long longs to eliminate a different cause of integer overflows. > > > > > > --- mdadm-3.3.2/util.c 2014-10-03 19:06:51.000000000 +0200 > > +++ mdadm-3.3.2/util.c 2014-10-03 19:08:06.000000000 +0200 > > @@ -671,15 +671,17 @@ > > if (bytes < 5000*1024) > > buf[0] = 0; > > else if (bytes < 2*1024LL*1024LL*1024LL) { > > - long cMiB = (bytes / ( (1LL<<20) / 200LL ) +1) /2; > > + long cMiB = bytes / (1LL<<20) * 100 > > + + ((bytes % (1LL<<20)) * 200 / (1LL<<20) +1) /2; > > long cMB = (bytes / ( 1000000LL / 200LL ) +1) /2; > > snprintf(buf, sizeof(buf), " (%ld.%02ld MiB %ld.%02ld MB)", > > cMiB/100 , cMiB % 100, > > cMB/100, cMB % 100); > > } else { > > - long cGiB = (bytes / ( (1LL<<30) / 200LL ) +1) /2; > > - long cGB = (bytes / (1000000000LL/200LL ) +1) /2; > > - snprintf(buf, sizeof(buf), " (%ld.%02ld GiB %ld.%02ld GB)", > > + long long cGiB = bytes / (1LL<<30) * 100 > > + + ((bytes % (1LL<<30)) * 200 / (1LL<<30) +1) /2; > > + long long cGB = (bytes / (1000000000LL/200LL ) +1) /2; > > + snprintf(buf, sizeof(buf), " (%lld.%02lld GiB %lld.%02lld GB)", > > cGiB/100 , cGiB % 100, > > cGB/100, cGB % 100); > > } > > @@ -706,12 +708,14 @@ > > buf[0] = 0; > > else if (prefix == IEC) { > > if (bytes < 2*1024LL*1024LL*1024LL) { > > - long cMiB = (bytes / ( (1LL<<20) / 200LL ) +1) /2; > > + long cMiB = bytes / (1LL<<20) * 100 > > _______________________________________________ > pkg-mdadm-devel mailing list > pkg-mdadm-devel@xxxxxxxxxxxxxxxxxxxxxxx > http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/pkg-mdadm-devel
Attachment:
pgpIWb5mrWF5H.pgp
Description: OpenPGP digital signature
