Re: [PATCH 2/3 v2] kdump-lib: Get the mount point correctly, if the device has several mount point

[Minfei Huang]

On 04/09/15 at 10:46am, Dave Young wrote:
>  On 04/08/15 at 12:30am, 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 | 11 ++++++++++-
>  >  mkdumprd     |  8 ++------
>  >  2 files changed, 12 insertions(+), 7 deletions(-)
>  > 
>  > diff --git a/kdump-lib.sh b/kdump-lib.sh
>  > index 2ad528e..75d7673 100755
>  > --- a/kdump-lib.sh
>  > +++ b/kdump-lib.sh
>  > @@ -135,7 +135,16 @@ 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
>  > +            return
>  > +        fi
>  > +    done
>  > +
>  > +    echo "Mount $1 firstly, without the bind mode" >&2
>  > +    exit 1
>  
>  Per discussion, we should limit the function only to atomic case.
>  
>  So it should be like below:
>  
>  get_mntpoint_from_target(){
>  if (!atomic)
>    echo $(findmnt -k -f -n -r -o TARGET $1)
>  else {
>   ...
>  }
>  } 
It does not impact on the general system, so there is no limitation
for this function.

Thanks
Minfei

>  
>  >  }
>  >  
>  >  # 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
>  >