Re: [Xen-devel] [PATCH 5/6] ts-xen-build-prep: mkfs a new /home/osstest, don't resize2fs

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-06-11 at 21:47 +0100, Ian Jackson wrote:
> Online resize is 40x slower than mkfs.  It appears that the
> backgrounded resize2fs can starve build tasks of IO bandwidth.
> 
> So instead, use mkfs to make a new filesystem for /home/osstest.
> We use rsync to copy in the old contents.
> 
> For convenience of (a) review (b) possible reversion, we keep (for
> now) the lvextend machinery.  So we create a new 1-extent LV for the
> lvextend machinery to work on.
> 
> But we don't call resize2fs when we extend it, because now it doesn't
> have a fs on it yet.  We make the filesystem later.
> 
> We move the ccache_setup until after this is done because it's a bit
> pointless to put things in the to-be-removed /home/osstest when they
> could be put in the new one after it had been set up.
> 
> We take slight care to make the rune slightly idempotent: if it
> completed successfully we detect this and do not run it again.  But if
> it didn't, things may be messed up and running it again is unlikely to
> help and may make things worse.
> 
> I have tested this on rice-weevil and the whole new target command
> (including rsync, mkfs, mount etc.) takes 126s.
> 
> Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> ---
>  ts-xen-build-prep |   46 ++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 42 insertions(+), 4 deletions(-)
> 
> diff --git a/ts-xen-build-prep b/ts-xen-build-prep
> index d600285..ab1346d 100755
> --- a/ts-xen-build-prep
> +++ b/ts-xen-build-prep
> @@ -30,7 +30,7 @@ exit 0 if $ho->{SharedReady};
>  
>  our ($vg,$lv);
>  
> -our $lvleaf = 'root';
> +our $lvleaf = 'osstest_home';
>  our $pe_size;
>  our $extended_pes = 0;
>  
> @@ -83,6 +83,11 @@ sub vginfo () {
>      return @vginfo;
>  }
>  
> +sub lvcreate () {
> +    target_cmd_output_root($ho,
> +                        "lvdisplay $lv || lvcreate -l 1 -n $lvleaf $vg");
> +}
> +
>  sub lvextend1 ($$$) {
>      my ($what, $max_more_gb)  = @_;
>  
> @@ -157,8 +162,39 @@ sub lvextend1 ($$$) {
>  
>      my $timeout = 2000 + int($pe_size * 0.000003 * $more_pe);
>      logm("$what: ${pe_size}k x $more_pe (timeout=$timeout)");
> -    my $cmd = "resize2fs $lv";
> -    target_cmd_root($ho, $cmd, $timeout);
> +}
> +
> +sub replace_home () {
> +    my $dir = '/home/osstest';
> +    my $mapper = lv_dev_mapper($vg,$lvleaf);
> +    my ($fstype,@opts) = qw(ext3 -m 0 -O sparse_super);
> +    target_cmd_root($ho, <<END, 1000);
> +        set -ex
> +     if mount | sed -e 's/^[^ ].* on //; s/ .*//' | grep -F '$dir'; then
> +         exit 0
> +     fi
> +     mkfs -t $fstype @opts $lv
> +        mount $lv /mnt

Some mixture hard and soft tabs here.

> +     rsync -aHx --numeric-ids $dir/. /mnt/.
> +     rm -rf $dir
> +     mkdir -m 2700 $dir
> +     echo '$mapper $dir $fstype defaults 0 0' >>/etc/fstab
> +     umount /mnt
> +     mount $dir
> +END
> +
> +        # for convenience, here is a small scriptlet to undo this:
> +        <<'END';
> +#!/bin/sh
> +set -ex
> +cd /home
> +rm -rf osstest.new
> +rsync -aH --numeric-ids osstest/. osstest.new

This made me wonder why not move the original one to osstest.foo instead
of rm -rf it? Doesn't really matter of course.

Ian.



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