mke2fs.8: Improve valid block size documentation

Explain which valid block sizes mke2fs supports in more detail.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 misc/mke2fs.8.in | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

On Oct 13, 2020, at 7:38 AM, Jan Kara <jack@suse.cz> wrote:
> 
> Explain which valid block sizes mke2fs supports in more detail.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>

Should this mention that the default block size is 4096 bytes for most
filesystems?

It might mention e.g. ppc64 or aarch64 can use 64KB page size, but this
is definitely an improvement already.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>

> ---
> misc/mke2fs.8.in | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
> index e6bfc6d6fd2d..0814d216f3a4 100644
> --- a/misc/mke2fs.8.in
> +++ b/misc/mke2fs.8.in
> @@ -207,10 +207,11 @@ manual page for more details.
> .SH OPTIONS
> .TP
> .BI \-b " block-size"
> -Specify the size of blocks in bytes.  Valid block-size values are 1024,
> -2048 and 4096 bytes per block.  If omitted,
> -block-size is heuristically determined by the filesystem size and
> -the expected usage of the filesystem (see the
> +Specify the size of blocks in bytes.  Valid block-size values are powers of two
> +from 1024 up to 65536 (however note that the kernel is able to mount only
> +filesystems with block-size smaller or equal to the system page size - 4k on
> +x86 systems). If omitted, block-size is heuristically determined by the
> +filesystem size and the expected usage of the filesystem (see the
> .B \-T
> option).  If
> .I block-size
> --
> 2.16.4
> 


Cheers, Andreas

On Wed 14-10-20 18:56:13, Andreas Dilger wrote:
> On Oct 13, 2020, at 7:38 AM, Jan Kara <jack@suse.cz> wrote:
> > 
> > Explain which valid block sizes mke2fs supports in more detail.
> > 
> > Signed-off-by: Jan Kara <jack@suse.cz>
> 
> Should this mention that the default block size is 4096 bytes for most
> filesystems?

That would be to the "heuristic" parts. Yes, I agree, I'll add that.

> It might mention e.g. ppc64 or aarch64 can use 64KB page size, but this
> is definitely an improvement already.

Yeah, I can add that to the "page size" part. But with these archs there's
a catch that page size can be configured in the kernel config so the
formulation will need to be a bit more careful. But I'll add something.

> Reviewed-by: Andreas Dilger <adilger@dilger.ca>

Thanks! I'll send v2.

								Honza
> 
> > ---
> > misc/mke2fs.8.in | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> > 
> > diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
> > index e6bfc6d6fd2d..0814d216f3a4 100644
> > --- a/misc/mke2fs.8.in
> > +++ b/misc/mke2fs.8.in
> > @@ -207,10 +207,11 @@ manual page for more details.
> > .SH OPTIONS
> > .TP
> > .BI \-b " block-size"
> > -Specify the size of blocks in bytes.  Valid block-size values are 1024,
> > -2048 and 4096 bytes per block.  If omitted,
> > -block-size is heuristically determined by the filesystem size and
> > -the expected usage of the filesystem (see the
> > +Specify the size of blocks in bytes.  Valid block-size values are powers of two
> > +from 1024 up to 65536 (however note that the kernel is able to mount only
> > +filesystems with block-size smaller or equal to the system page size - 4k on
> > +x86 systems). If omitted, block-size is heuristically determined by the
> > +filesystem size and the expected usage of the filesystem (see the
> > .B \-T
> > option).  If
> > .I block-size
> > --
> > 2.16.4
> > 
> 
> 
> Cheers, Andreas
> 
> 
> 
> 
>

On Thu, Oct 15, 2020 at 11:27:31AM +0200, Jan Kara wrote:
> On Wed 14-10-20 18:56:13, Andreas Dilger wrote:
> > On Oct 13, 2020, at 7:38 AM, Jan Kara <jack@suse.cz> wrote:
> > > 
> > > Explain which valid block sizes mke2fs supports in more detail.
> > > 
> > > Signed-off-by: Jan Kara <jack@suse.cz>
> > 
> > Should this mention that the default block size is 4096 bytes for most
> > filesystems?
> 
> That would be to the "heuristic" parts. Yes, I agree, I'll add that.
> 
> > It might mention e.g. ppc64 or aarch64 can use 64KB page size, but this
> > is definitely an improvement already.
> 
> Yeah, I can add that to the "page size" part. But with these archs there's
> a catch that page size can be configured in the kernel config so the
> formulation will need to be a bit more careful. But I'll add something.
> 
> > Reviewed-by: Andreas Dilger <adilger@dilger.ca>
> 
> Thanks! I'll send v2.

Did you ever send a v2 of this patch?  I can't seem to find it in my
archives or in patchwork.

Thanks!!

					- Ted

On Tue 15-12-20 13:50:27, Theodore Y. Ts'o wrote:
> On Thu, Oct 15, 2020 at 11:27:31AM +0200, Jan Kara wrote:
> > On Wed 14-10-20 18:56:13, Andreas Dilger wrote:
> > > On Oct 13, 2020, at 7:38 AM, Jan Kara <jack@suse.cz> wrote:
> > > > 
> > > > Explain which valid block sizes mke2fs supports in more detail.
> > > > 
> > > > Signed-off-by: Jan Kara <jack@suse.cz>
> > > 
> > > Should this mention that the default block size is 4096 bytes for most
> > > filesystems?
> > 
> > That would be to the "heuristic" parts. Yes, I agree, I'll add that.
> > 
> > > It might mention e.g. ppc64 or aarch64 can use 64KB page size, but this
> > > is definitely an improvement already.
> > 
> > Yeah, I can add that to the "page size" part. But with these archs there's
> > a catch that page size can be configured in the kernel config so the
> > formulation will need to be a bit more careful. But I'll add something.
> > 
> > > Reviewed-by: Andreas Dilger <adilger@dilger.ca>
> > 
> > Thanks! I'll send v2.
> 
> Did you ever send a v2 of this patch?  I can't seem to find it in my
> archives or in patchwork.

I think I did but probably it got lost somewhere. Anyway, I've resent it
now. Thanks for noticing!

								Honza