Re: [PATCH 3/4] kdump-lib: Get the mount point correctly, if the device has several mount point

[Baoquan He]

On 03/26/15 at 05:19pm, Minfei Huang wrote:
>  On 03/26/15 at 05:00pm, Baoquan He wrote:
>  > Please discard this patch. In mkdumprd we just add the mount info which
>  > will mount the needed device. In this stage we don't care the real dump
>  > path. Any point is OK, we just need care about the dump path. E.g on
>  > Atomic we have below mount point for lvm device. Then current code will
>  > take the first one, namely "/". It's fine, we just need dump to 
>  > /ostree/deploy/rhel-atomic-host/var/crash.
>  > 
>  > 
>  > -bash-4.2# findmnt -k  -n -r -o TARGET /dev/mapper/atomicos-root
>  > /
>  > /sysroot
>  > /var
>  > /usr
>  > 
>  
>  You are right that we can allways get the root mount point in
>  /dev/mapper/atomicos-root in atomic, if we use the command "findmnt -k
>  -n -r -o TARGET /dev/mapper/atomicos-root".
>  
>  But I think maybe we shall leave the hint how we can get the root mount
>  point correctly, if the target device is not /dev/mapper/atomicos-root,
>  or the os is not atomic. Otherwise it may be hard to be fixed. 
What do you mean? Here the code just do the device mounting. whatever
the mount poing is, it will be mounted in 2nd kernel.

And then with the correct dump path, e.g on /dev/sda, it will surely
dump to the parsed real dump path on /dev/sda. what is mount point
doesn't matter.

>  
>  Thanks
>  Minfei
>  
>  > On 03/04/15 at 01:07am, Minfei Huang wrote:
>  > > The filesystem support the device to be mounted different mount points.
>  > > The root path in the device may be different, if the mount point is
>  > > mounted by bind mode. In order to dump core correctly, we should find
>  > > the root path in the device.
>  > > 
>  > > Following is the case that device is mounted by bind mode.
>  > > 
>  > > TARGET    SOURCE   FSTYPE OPTIONS
>  > > /mnt/ext4 /dev/vda btrfs  rw,relatime,seclabel,space_cache
>  > > TARGET        SOURCE         FSTYPE OPTIONS
>  > > /mnt/bind-dir /dev/vda[/var] btrfs  rw,relatime,seclabel,space_cache
>  > > 
>  > > We can find that /mnt/bind-dir is mounted in the path /dev/vda[/var], in
>  > > the other word, the /mnt/bind-dir points to the /var directory in the
>  > > /dev/vda.
>  > > The /mnt/ext4 is the root path in the device.
>  > > 
>  > > Signed-off-by: Minfei Huang <mhuang(a)redhat.com&gt;
>  > > ---
>  > >  kdump-lib.sh | 7 ++++++-
>  > >  mkdumprd     | 8 ++------
>  > >  2 files changed, 8 insertions(+), 7 deletions(-)
>  > > 
>  > > diff --git a/kdump-lib.sh b/kdump-lib.sh
>  > > index 74b3c1c..4301eb4 100755
>  > > --- a/kdump-lib.sh
>  > > +++ b/kdump-lib.sh
>  > > @@ -135,7 +135,12 @@ get_fs_type_from_target()
>  > >  
>  > >  get_mntpoint_from_target()
>  > >  {
>  > > -    echo $(findmnt -k -f -n -r -o TARGET $1)
>  > > +    for _mnt in $(findmnt -k -n -r -o TARGET $1)
>  > > +    do
>  > > +        if ! is_bind_mount $_mnt; then
>  > > +            echo $_mnt
>  > > +        fi
>  > > +    done
>  > >  }
>  > >  
>  > >  # get_option_value <option_name>
>  > > diff --git a/mkdumprd b/mkdumprd
>  > > index a8f9cbb..7fdcebf 100644
>  > > --- a/mkdumprd
>  > > +++ b/mkdumprd
>  > > @@ -100,7 +100,7 @@ to_mount() {
>  > >      local _dev=$1 _source _target _fstype _options _mntopts _pdev
>  > >  
>  > >      _source=$(findmnt -k -f -n -r -o SOURCE $_dev)
>  > > -    _target=$(findmnt -k -f -n -r -o TARGET $_dev)
>  > > +    _target=$(get_mntpoint_from_target $_dev)
>  > >      # mount under /sysroot if dump to root disk or mount under
>  > >      #/kdumproot/$_target in other cases in 2nd kernel. systemd
>  > >      #will be in charge to umount it.
>  > > @@ -144,10 +144,6 @@ to_mount() {
>  > >      echo "$_pdev $_mntopts"
>  > >  }
>  > >  
>  > > -to_mount_point() {
>  > > -    echo $(findmnt -k -f -n -r -o TARGET $1)
>  > > -}
>  > > -
>  > >  is_readonly_mount() {
>  > >      local _mnt
>  > >      _mnt=$(findmnt -k -f -n -r -o OPTIONS $1)
>  > > @@ -201,7 +197,7 @@ mkdir_save_path_ssh()
>  > >  #Function: get_fs_size
>  > >  #$1=dump target
>  > >  get_fs_size() {
>  > > -    local _mnt=$(to_mount_point $1)
>  > > +    local _mnt=$(get_mntpoint_from_target $1)
>  > >      echo -n $(df -P "${_mnt}/$SAVE_PATH"|tail -1|awk '{print
> $4}')
>  > >  }
>  > >  
>  > > -- 
>  > > 1.9.3
>  > > 
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