On Sat, Dec 03, 2016 at 10:25:17AM -0800, Omar Sandoval wrote: > On Sat, Dec 03, 2016 at 01:19:38AM -0500, Zygo Blaxell wrote: > > I got tired of seeing "16.00EiB" whenever btrfs-progs encounters a > > negative size value. > > > > e.g. during filesystem shrink we see: > > > > Unallocated: > > /dev/mapper/testvol0 16.00EiB > > > > Interpreting this as a signed quantity is much more useful: > > > > Unallocated: > > /dev/mapper/testvol0 -26.29GiB > > > > Signed-off-by: Zygo Blaxell <[email protected]> > > --- > > utils.c | 13 ++++++++----- > > 1 file changed, 8 insertions(+), 5 deletions(-) > > > > diff --git a/utils.c b/utils.c > > index 69b580a..bd2b66e 100644 > > --- a/utils.c > > +++ b/utils.c > > @@ -2594,20 +2594,23 @@ static const char* unit_suffix_binary[] = > > static const char* unit_suffix_decimal[] = > > { "B", "kB", "MB", "GB", "TB", "PB", "EB"}; > > > > -int pretty_size_snprintf(u64 size, char *str, size_t str_size, unsigned > > unit_mode) > > +int pretty_size_snprintf(u64 usize, char *str, size_t str_size, unsigned > > unit_mode) > > { > > int num_divs; > > float fraction; > > - u64 base = 0; > > + s64 base = 0; > > int mult = 0; > > const char** suffix = NULL; > > - u64 last_size; > > + s64 last_size; > > > > if (str_size == 0) > > return 0; > > > > + /* Negative numbers are more plausible than sizes over 8 EiB. */ > > + s64 size = (s64)usize; > > Just make pretty_size_snprintf() take an s64 size so it's clear from the > function signature that it's signed instead of hidden in the definition.
I intentionally buried the unsigned -> signed conversion in the lowest
level function so I wouldn't trigger signed/unsigned conversion warnings
at all 46 call sites for pretty_size_mode. The btrfs code uses u64
endemically for all size data, and I wasn't about to try to change that.
The word "pretty" in the function name should imply that what comes out
is a possibly lossy transformation of what goes in. Since "16.00EiB"
is much more lossy than "-29.96GiB", I believe I am merely reducing the
lossiness quantitatively rather than qualitatively.
On the other hand, the signed/unsigned warning isn't enabled by default
in this project. I can certainly do it that way if you prefer.
> > +
> > if ((unit_mode & ~UNITS_MODE_MASK) == UNITS_RAW) {
> > - snprintf(str, str_size, "%llu", size);
> > + snprintf(str, str_size, "%lld", size);
> > return 0;
> > }
> >
> > @@ -2642,7 +2645,7 @@ int pretty_size_snprintf(u64 size, char *str, size_t
> > str_size, unsigned unit_mod
> > num_divs = 0;
> > break;
> > default:
> > - while (size >= mult) {
> > + while ((size < 0 ? -size : size) >= mult) {
> > last_size = size;
> > size /= mult;
> > num_divs++;
> > --
> > 2.1.4
> >
> > --
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> > the body of a message to [email protected]
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>
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