Re: [PATCH][BTRFS-PROGS][V1] btrfs filesystem df

[Ilya Dryomov <idryomov@gmail.com>]

On Wed, Oct 03, 2012 at 10:01:00PM +0200, Goffredo Baroncelli wrote:
> On 10/03/2012 07:46 PM, Ilya Dryomov wrote:
> >On Wed, Oct 03, 2012 at 06:46:00PM +0200, Goffredo Baroncelli wrote:
> >>On 10/03/2012 05:01 PM, Ilya Dryomov wrote:
> >>>"Type" for the first column is probably enough.
> >>>
> >>>Why is the third column called Chunk-size?  If my understanding is
> >>>correct, it's just a break down of Disk_allocated from the summary
> >>>section.  If so, why not call it Disk_allocated to avoid confusion?
> >>
> >>Using everywhere Disk_<something>  was my first attempt. But after
> >>some thoughts I decided that these are two different kind of
> >>information. It is true that Disk_allocated is the sum of
> >>Chunk-Sizes... But my feels is that this is a kind of
> >>"implementation details". If some other type of allocation unit will
> >>be added to BTRFS, then these will be added to Disk_allocated, but
> >>not to Chunk list...
> >>I prefer to not change the wording until an enough critical mass of
> >>people converge to a unique solution .
> >
> >It is the chunks that is the implementation detail that we want to hide.
> >Average Btrfs user wouldn't want to know anything about chunks, the only
> >thing he'd be interested in is Disk_allocated and similar fields.
> 
> The "df" standard tool id sufficient for the "average user".
> We need only to export these information via the standard syscall
> stat[v]fs. Basically we should try to implement the algorithm of the
> Free_(Estimated) space for the statfs(2) syscall.
> Who uses btrfs tools, is an user with knowledge of btrfs higher than
> the average.
> 
> >Moreover, I am pretty sure "Chunk-Size" would actually confuse people.
> >I stared at your example output for a few seconds trying to comprehend a
> >21GB Chunk-Size on a 72GB partition.  What you call "Chunk-Size" is
> >actually a sum of sizes of chunks of that particular type, and a few
> >lines above you call the same exact sum (only this time over all types
> >of chunks) "Disk_allocated".  So I think it's only logical to rename the
> >column in question to "Disk_allocated" to match the summary section.
> 
> What about
> [...]
> Details:
>   Chunk_type  Mode      Size_(disk) Size_(logical)     Used
>   Data        Single       21.01GB      21.01GB     10.53GB
>   System      DUP          80.00MB      40.00MB      4.00KB
> [...]
> 
> ?

This is definitely better.  Can you also drop "Chunk_type" in favor of
"Type"?

Thanks,

		Ilya