[PATCH v3] dracut-module-setup: Fix the incorrect dumping target in atomic

[Minfei Huang]

The kdump will dump the core in incorrect target directory
/sysroot/crash, if the target is bind mounted.

The /var is bind mounted in Atomic, kdump will dump the core in
/sysroot/crash, instead of /var/crash, if we specifies the value
"path /var/crash" in the /etc/kdump.conf.

To correct dumping target, we can construct the real dumping path, which
contains two part, one bind mounted path, the other specified dump
target.

Following is an example:

-bash-4.2# cat /etc/kdump.conf | grep ^path
    path /var/crash

-bash-4.2# findmnt /var | tail -n 1 | awk '{print $2}'
    /dev/mapper/atomicos-root[/ostree/deploy/rhel-atomic-host/var]

-bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
    /dev/mapper/atomicos-root

Then we can found it that the real path of dumping core is
/ostree/deploy/rhel-atomic-host/var/crash.

Signed-off-by: Minfei Huang 
---
 dracut-module-setup.sh | 29 +++++++++++++++++++----------
 kdump-lib.sh           | 32 ++++++++++++++++++++++++++++++++
 mkdumprd               |  4 +---
 3 files changed, 52 insertions(+), 13 deletions(-)

diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
index ff7a088..b7ef56d 100755
--- a/dracut-module-setup.sh
+++ b/dracut-module-setup.sh
@@ -304,10 +304,19 @@ kdump_install_net() {
     fi
 }

+adjust_dump_target()
+{
+    local _fstype=$1 _target=$2 _path=$3
+    echo "$_fstype $_target" >> /tmp/$$-kdump.conf
+
+    #erase the old path line, then insert the parsed path
+    sed -i "/^path/d" /tmp/$$-kdump.conf
+    echo "path $_path" >> /tmp/$$-kdump.conf
+}
+
 default_dump_target_install_conf()
 {
     local _target _fstype
-    local _s  _t
     local _mntpoint
     local _path _save_path

@@ -318,25 +327,25 @@ default_dump_target_install_conf()

_mntpoint=$(get_mntpoint_from_path $_save_path)
     _target=$(get_target_from_path $_save_path)
-    if [ "$_mntpoint" != "/" ]; then
-        _fstype=$(get_fs_type_from_target $_target)
+    _fstype=$(get_fs_type_from_target $_target)

+    if is_bind_mount $_mntpoint; then
+        _path=${_save_path##"$_mntpoint"}
+        # the real dump path in the 2nd kernel, if the mount point is bind mounted.
+        _path=$(get_bind_mount_directory $_mntpoint)/$_path
+
+        adjust_dump_target $_fstype $_target $_path
+    elif [ "$_mntpoint" != "/" ]; then
         if $(is_fs_type_nfs $_fstype); then
             kdump_install_net "$_target"
             _fstype="nfs"
         else
             _target=$(kdump_to_udev_name $_target)
         fi
-
-        echo "$_fstype $_target" >> /tmp/$$-kdump.conf
-
         _path=${_save_path##"$_mntpoint"}

-        #erase the old path line, then insert the parsed path
-        sed -i "/^path/d" /tmp/$$-kdump.conf
-        echo "path $_path" >> /tmp/$$-kdump.conf
+        adjust_dump_target $_fstype $_target $_path
     fi
-
 }

#install kdump.conf and what user specifies in kdump.conf
diff --git a/kdump-lib.sh b/kdump-lib.sh
index f24f08d..d8a547a 100755
--- a/kdump-lib.sh
+++ b/kdump-lib.sh
@@ -86,6 +86,38 @@ get_root_fs_device()
     return
 }

+# findmnt uses the option "-v, --nofsroot" to exclusive the [/dir]
+# in the SOURCE column for bind-mounts, then if $_mntpoint equals to
+# $_mntpoint_nofsroot, the mountpoint is not bind mounted directory.
+is_bind_mount()
+{
+    local _mntpoint=$(findmnt $1 | tail -n 1 | awk '{print $2}')
+    local _mntpoint_nofsroot=$(findmnt -v $1 | tail -n 1 | awk '{print $2}')
+
+    if [[ $_mntpoint = $_mntpoint_nofsroot ]]; then
+        return 1
+    else
+        return 0
+    fi
+}
+
+# the value of $_mntpoint will be
+# /dev/mapper/atomicos-root[/ostree/deploy/rhel-atomic-host/var], if the
+# directory is bind mounted. The former part represents the device path, rest
+# part is the bind mounted directory which quotes by bracket "[]".
+get_bind_mount_directory()
+{
+    local _mntpoint=$(findmnt $1 | tail -n 1 | awk '{print $2}')
+    local _mntpoint_nofsroot=$(findmnt -v $1 | tail -n 1 | awk '{print $2}')
+
+    _mntpoint=${_mntpoint##$_mntpoint_nofsroot}
+
+    _mntpoint=${_mntpoint#[}
+    _mntpoint=${_mntpoint%]}
+
+    echo $_mntpoint
+}
+
 get_mntpoint_from_path() 
 {
     echo $(df $1 | tail -1 |  awk '{print $NF}')
diff --git a/mkdumprd b/mkdumprd
index 4d251ba..951eb6d 100644
--- a/mkdumprd
+++ b/mkdumprd
@@ -201,8 +201,7 @@ mkdir_save_path_ssh()
 #Function: get_fs_size
 #$1=dump target
 get_fs_size() {
-    local _mnt=$(to_mount_point $1)
-    echo -n $(df -P "${_mnt}/$SAVE_PATH"|tail -1|awk '{print $4}')
+    echo -n $(df -P "$SAVE_PATH"|tail -1|awk '{print $4}')
 }

#Function: get_raw_size
@@ -364,7 +363,6 @@ handle_default_dump_target()
     _mntpoint=$(get_mntpoint_from_path $SAVE_PATH)
     _target=$(get_target_from_path $SAVE_PATH)
     if [ "$_mntpoint" != "/" ]; then
-        SAVE_PATH=${SAVE_PATH##"$_mntpoint"}
         _fstype=$(get_fs_type_from_target $_target)

if $(is_fs_type_nfs $_fstype); then

[Dave Young]

Minfei

The patch seems conflicts with Bao's patch for cleaning up /tmp/ files.

BTW, what's the difference between this version and the previous version?

On 02/16/15 at 06:03pm, Minfei Huang wrote:
> The kdump will dump the core in incorrect target directory
> /sysroot/crash, if the target is bind mounted.
>
> The /var is bind mounted in Atomic, kdump will dump the core in
> /sysroot/crash, instead of /var/crash, if we specifies the value
> "path /var/crash" in the /etc/kdump.conf.
>
> To correct dumping target, we can construct the real dumping path, which
> contains two part, one bind mounted path, the other specified dump
> target.
>
> Following is an example:
> -bash-4.2# cat /etc/kdump.conf | grep ^path
> path /var/crash
>
> -bash-4.2# findmnt /var | tail -n 1 | awk '{print $2}'
> /dev/mapper/atomicos-root[/ostree/deploy/rhel-atomic-host/var]
>
> -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> /dev/mapper/atomicos-root

There's no real dumping path for bind mount as we discussed in previous
thread, right?

BTW btrfs subvolumes also use [] in findmnt output, how to differenciate them?

I'm thinking we can do nothing for bind mount, we probably can only fix
things case by case..
> Then we can found it that the real path of dumping core is
> /ostree/deploy/rhel-atomic-host/var/crash.
> Signed-off-by: Minfei Huang
>
> dracut-module-setup.sh | 29 +++++++++++++++++++----------
>  kdump-lib.sh           | 32 ++++++++++++++++++++++++++++++++
>  mkdumprd               |  4 +---
>  3 files changed, 52 insertions(+), 13 deletions(-)
>
> diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> index ff7a088..b7ef56d 100755
> --- a/dracut-module-setup.sh
> +++ b/dracut-module-setup.sh
> @@ -304,10 +304,19 @@ kdump_install_net() {
>      fi
>  }
>
> +adjust_dump_target()
> +{
> local _fstype=$1 _target=$2 _path=$3
> echo "$_fstype $_target" >> /tmp/$$-kdump.conf
> #erase the old path line, then insert the parsed path
> sed -i "/^path/d" /tmp/$$-kdump.conf
> echo "path $_path" >> /tmp/$$-kdump.conf
>
> +}
>
> default_dump_target_install_conf()
>  {
>      local _target _fstype
> local _s  _t
> local _mntpoint
> local _path _save_path
>
> @@ -318,25 +327,25 @@ default_dump_target_install_conf()
>  _mntpoint=$(get_mntpoint_from_path $_save_path)
>  _target=$(get_target_from_path $_save_path)
> if [ "$_mntpoint" != "/" ]; then
>    _fstype=$(get_fs_type_from_target $_target)
>
> _fstype=$(get_fs_type_from_target $_target)
>
> if is_bind_mount $_mntpoint; then
>    _path=${_save_path##"$_mntpoint"}
>    # the real dump path in the 2nd kernel, if the mount point is bind mounted.
>    _path=$(get_bind_mount_directory $_mntpoint)/$_path
>    adjust_dump_target $_fstype $_target $_path
>
> elif [ "$_mntpoint" != "/" ]; then
>     if $(is_fs_type_nfs $_fstype); then
>         kdump_install_net "$_target"
>         _fstype="nfs"
>     else
>         _target=$(kdump_to_udev_name $_target)
>     fi
>    echo "$_fstype $_target" >> /tmp/$$-kdump.conf
>    _path=${_save_path##"$_mntpoint"}
>
>    #erase the old path line, then insert the parsed path
>    sed -i "/^path/d" /tmp/$$-kdump.conf
>    echo "path $_path" >> /tmp/$$-kdump.conf
>    adjust_dump_target $_fstype $_target $_path
> fi
>
> }
>
> #install kdump.conf and what user specifies in kdump.conf
> diff --git a/kdump-lib.sh b/kdump-lib.sh
> index f24f08d..d8a547a 100755
> --- a/kdump-lib.sh
> +++ b/kdump-lib.sh
> @@ -86,6 +86,38 @@ get_root_fs_device()
>      return
>  }
>
> +# findmnt uses the option "-v, --nofsroot" to exclusive the [/dir]
> +# in the SOURCE column for bind-mounts, then if $_mntpoint equals to
> +# $_mntpoint_nofsroot, the mountpoint is not bind mounted directory.
> +is_bind_mount()
> +{
> local _mntpoint=$(findmnt $1 | tail -n 1 | awk '{print $2}')
> local _mntpoint_nofsroot=$(findmnt -v $1 | tail -n 1 | awk '{print $2}')
> if [[ $_mntpoint = $_mntpoint_nofsroot ]]; then
>    return 1
> else
>    return 0
> fi
>
> +}
>
> +# the value of $_mntpoint will be
> +# /dev/mapper/atomicos-root[/ostree/deploy/rhel-atomic-host/var], if the
> +# directory is bind mounted. The former part represents the device path, rest
> +# part is the bind mounted directory which quotes by bracket "[]".
> +get_bind_mount_directory()
> +{
> local _mntpoint=$(findmnt $1 | tail -n 1 | awk '{print $2}')
> local _mntpoint_nofsroot=$(findmnt -v $1 | tail -n 1 | awk '{print $2}')
> _mntpoint=${_mntpoint##$_mntpoint_nofsroot}
> _mntpoint=${_mntpoint#[}
> _mntpoint=${_mntpoint%]}
> echo $_mntpoint
>
> +}
>
> get_mntpoint_from_path() 
>  {
>      echo $(df $1 | tail -1 |  awk '{print $NF}')
> diff --git a/mkdumprd b/mkdumprd
> index 4d251ba..951eb6d 100644
> --- a/mkdumprd
> +++ b/mkdumprd
> @@ -201,8 +201,7 @@ mkdir_save_path_ssh()
>  #Function: get_fs_size
>  #$1=dump target
>  get_fs_size() {
> local _mnt=$(to_mount_point $1)
> echo -n $(df -P "${_mnt}/$SAVE_PATH"|tail -1|awk '{print $4}')
> echo -n $(df -P "$SAVE_PATH"|tail -1|awk '{print $4}')
>
> }
>
> #Function: get_raw_size
> @@ -364,7 +363,6 @@ handle_default_dump_target()
>      _mntpoint=$(get_mntpoint_from_path $SAVE_PATH)
>      _target=$(get_target_from_path $SAVE_PATH)
>      if [ "$_mntpoint" != "/" ]; then
>    SAVE_PATH=${SAVE_PATH##"$_mntpoint"}
>    _fstype=$(get_fs_type_from_target $_target)
>
>    if $(is_fs_type_nfs $_fstype); then
>
> -- 
> 2.2.2
>
> kexec mailing list
> [e-mail]
> https://lists.fedoraproject.org/mailman/listinfo/kexec

[Minfei Huang]

On 02/25/15 at 02:25pm, Dave Young wrote:
> Minfei
>
> The patch seems conflicts with Bao's patch for cleaning up /tmp/ files.

Hi, Dave!

yes. I will add the prefix "${initdir}" to the "/tmp/".
> BTW, what's the difference between this version and the previous version?
>
> On 02/16/15 at 06:03pm, Minfei Huang wrote:
> > The kdump will dump the core in incorrect target directory
> > /sysroot/crash, if the target is bind mounted.
> >
> > The /var is bind mounted in Atomic, kdump will dump the core in
> > /sysroot/crash, instead of /var/crash, if we specifies the value
> > "path /var/crash" in the /etc/kdump.conf.
> >
> > To correct dumping target, we can construct the real dumping path, which
> > contains two part, one bind mounted path, the other specified dump
> > target.
> >
> > Following is an example:
> > -bash-4.2# cat /etc/kdump.conf | grep ^path
> > path /var/crash
> >
> > -bash-4.2# findmnt /var | tail -n 1 | awk '{print $2}'
> > /dev/mapper/atomicos-root[/ostree/deploy/rhel-atomic-host/var]
> >
> > -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> > /dev/mapper/atomicos-root
>
> There's no real dumping path for bind mount as we discussed in previous
> thread, right?

We can construct the real dump path for the bind mounted, using findmnt.
As the above comment, we can identify the bind mount directory by using
findmnt command.
> BTW btrfs subvolumes also use [] in findmnt output, how to differenciate them?

For now, I don't test the btrfs.

Thanks
Minfei
> I'm thinking we can do nothing for bind mount, we probably can only fix
> things case by case..
> > Then we can found it that the real path of dumping core is
> > /ostree/deploy/rhel-atomic-host/var/crash.
> > Signed-off-by: Minfei Huang
> >
> > dracut-module-setup.sh | 29 +++++++++++++++++++----------
> >  kdump-lib.sh           | 32 ++++++++++++++++++++++++++++++++
> >  mkdumprd               |  4 +---
> >  3 files changed, 52 insertions(+), 13 deletions(-)
> >
> > diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> > index ff7a088..b7ef56d 100755
> > --- a/dracut-module-setup.sh
> > +++ b/dracut-module-setup.sh
> > @@ -304,10 +304,19 @@ kdump_install_net() {
> >      fi
> >  }
> >
> > +adjust_dump_target()
> > +{
> > local _fstype=$1 _target=$2 _path=$3
> > echo "$_fstype $_target" >> /tmp/$$-kdump.conf
> > #erase the old path line, then insert the parsed path
> > sed -i "/^path/d" /tmp/$$-kdump.conf
> > echo "path $_path" >> /tmp/$$-kdump.conf
> >
> > +}
> >
> > default_dump_target_install_conf()
> >  {
> >      local _target _fstype
> > local _s  _t
> > local _mntpoint
> > local _path _save_path
> >
> > @@ -318,25 +327,25 @@ default_dump_target_install_conf()
> >  _mntpoint=$(get_mntpoint_from_path $_save_path)
> >  _target=$(get_target_from_path $_save_path)
> > if [ "$_mntpoint" != "/" ]; then
> >    _fstype=$(get_fs_type_from_target $_target)
> >
> > _fstype=$(get_fs_type_from_target $_target)
> >
> > if is_bind_mount $_mntpoint; then
> >    _path=${_save_path##"$_mntpoint"}
> >    # the real dump path in the 2nd kernel, if the mount point is bind mounted.
> >    _path=$(get_bind_mount_directory $_mntpoint)/$_path
> >    adjust_dump_target $_fstype $_target $_path
> >
> > elif [ "$_mntpoint" != "/" ]; then
> >     if $(is_fs_type_nfs $_fstype); then
> >         kdump_install_net "$_target"
> >         _fstype="nfs"
> >     else
> >         _target=$(kdump_to_udev_name $_target)
> >     fi
> >    echo "$_fstype $_target" >> /tmp/$$-kdump.conf
> >    _path=${_save_path##"$_mntpoint"}
> >
> >    #erase the old path line, then insert the parsed path
> >    sed -i "/^path/d" /tmp/$$-kdump.conf
> >    echo "path $_path" >> /tmp/$$-kdump.conf
> >    adjust_dump_target $_fstype $_target $_path
> > fi
> >
> > }
> >
> > #install kdump.conf and what user specifies in kdump.conf
> > diff --git a/kdump-lib.sh b/kdump-lib.sh
> > index f24f08d..d8a547a 100755
> > --- a/kdump-lib.sh
> > +++ b/kdump-lib.sh
> > @@ -86,6 +86,38 @@ get_root_fs_device()
> >      return
> >  }
> >
> > +# findmnt uses the option "-v, --nofsroot" to exclusive the [/dir]
> > +# in the SOURCE column for bind-mounts, then if $_mntpoint equals to
> > +# $_mntpoint_nofsroot, the mountpoint is not bind mounted directory.
> > +is_bind_mount()
> > +{
> > local _mntpoint=$(findmnt $1 | tail -n 1 | awk '{print $2}')
> > local _mntpoint_nofsroot=$(findmnt -v $1 | tail -n 1 | awk '{print $2}')
> > if [[ $_mntpoint = $_mntpoint_nofsroot ]]; then
> >    return 1
> > else
> >    return 0
> > fi
> >
> > +}
> >
> > +# the value of $_mntpoint will be
> > +# /dev/mapper/atomicos-root[/ostree/deploy/rhel-atomic-host/var], if the
> > +# directory is bind mounted. The former part represents the device path, rest
> > +# part is the bind mounted directory which quotes by bracket "[]".
> > +get_bind_mount_directory()
> > +{
> > local _mntpoint=$(findmnt $1 | tail -n 1 | awk '{print $2}')
> > local _mntpoint_nofsroot=$(findmnt -v $1 | tail -n 1 | awk '{print $2}')
> > _mntpoint=${_mntpoint##$_mntpoint_nofsroot}
> > _mntpoint=${_mntpoint#[}
> > _mntpoint=${_mntpoint%]}
> > echo $_mntpoint
> >
> > +}
> >
> > get_mntpoint_from_path() 
> >  {
> >      echo $(df $1 | tail -1 |  awk '{print $NF}')
> > diff --git a/mkdumprd b/mkdumprd
> > index 4d251ba..951eb6d 100644
> > --- a/mkdumprd
> > +++ b/mkdumprd
> > @@ -201,8 +201,7 @@ mkdir_save_path_ssh()
> >  #Function: get_fs_size
> >  #$1=dump target
> >  get_fs_size() {
> > local _mnt=$(to_mount_point $1)
> > echo -n $(df -P "${_mnt}/$SAVE_PATH"|tail -1|awk '{print $4}')
> > echo -n $(df -P "$SAVE_PATH"|tail -1|awk '{print $4}')
> >
> > }
> >
> > #Function: get_raw_size
> > @@ -364,7 +363,6 @@ handle_default_dump_target()
> >      _mntpoint=$(get_mntpoint_from_path $SAVE_PATH)
> >      _target=$(get_target_from_path $SAVE_PATH)
> >      if [ "$_mntpoint" != "/" ]; then
> >    SAVE_PATH=${SAVE_PATH##"$_mntpoint"}
> >    _fstype=$(get_fs_type_from_target $_target)
> >
> >    if $(is_fs_type_nfs $_fstype); then
> >
> > -- 
> > 2.2.2
> >
> > kexec mailing list
> > [e-mail]
> > https://lists.fedoraproject.org/mailman/listinfo/kexec

[Baoquan He]

On 02/25/15 at 03:10pm, Minfei Huang wrote:
> On 02/25/15 at 02:25pm, Dave Young wrote:
> > Minfei
> >
> > The patch seems conflicts with Bao's patch for cleaning up /tmp/ files.
>
> Hi, Dave!
>
> yes. I will add the prefix "${initdir}" to the "/tmp/".

I have merged the /tmp patch, you can pull the latest code and
repost on top of it.
> > BTW, what's the difference between this version and the previous version?
> >
> > On 02/16/15 at 06:03pm, Minfei Huang wrote:
> > > The kdump will dump the core in incorrect target directory
> > > /sysroot/crash, if the target is bind mounted.
> > >
> > > The /var is bind mounted in Atomic, kdump will dump the core in
> > > /sysroot/crash, instead of /var/crash, if we specifies the value
> > > "path /var/crash" in the /etc/kdump.conf.
> > >
> > > To correct dumping target, we can construct the real dumping path, which
> > > contains two part, one bind mounted path, the other specified dump
> > > target.
> > >
> > > Following is an example:
> > > -bash-4.2# cat /etc/kdump.conf | grep ^path
> > > path /var/crash
> > >
> > > -bash-4.2# findmnt /var | tail -n 1 | awk '{print $2}'
> > > /dev/mapper/atomicos-root[/ostree/deploy/rhel-atomic-host/var]
> > >
> > > -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> > > /dev/mapper/atomicos-root
> >
> > There's no real dumping path for bind mount as we discussed in previous
> > thread, right?
>
> We can construct the real dump path for the bind mounted, using findmnt.
> As the above comment, we can identify the bind mount directory by using
> findmnt command.
> > BTW btrfs subvolumes also use [] in findmnt output, how to differenciate them?
>
> For now, I don't test the btrfs.

It will be better to check btrfs. For now I think this patch is good.
2 things need be carefully tested, 1st is recursively bind mount, 2nd is
btrfs. If it doesn't break current code in above 2 cases, I would like
to ack it.
> Thanks
> Minfei
> > I'm thinking we can do nothing for bind mount, we probably can only fix
> > things case by case..

[Dave Young]

Hi, Minfei
> > > -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> > > /dev/mapper/atomicos-root
> >
> > There's no real dumping path for bind mount as we discussed in previous
> > thread, right?
>
> We can construct the real dump path for the bind mounted, using findmnt.
> As the above comment, we can identify the bind mount directory by using
> findmnt command.

No, it did not answer my question, As Karel said for bind mount is same as
non-bind mount, see below the original source can be unmounted while the
later bind mount still exist:

[dyoung@dhcp-xx-xx dyoung]# mount /dev/sda7 /mnt/sda7
[dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7
bin   dev  home  lib64       media  opt   dyoung  sbin  sys  usr
boot  etc  lib   lost+found  mnt    proc  run   srv   tmp  var
[dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7/var
adm    db     games  lock  mail  named  rwho   state  www
cache  empty  lib    log   man   run    spool  tmp    yp
[dyoung@dhcp-xx-xx dyoung]# mount -o bind /mnt/sda7/var tmp
[dyoung@dhcp-xx-xx dyoung]# ls tmp
adm    db     games  lock  mail  named  rwho   state  www
cache  empty  lib    log   man   run    spool  tmp    yp
[dyoung@dhcp-xx-xx dyoung]# umount /mnt/sda7
[dyoung@dhcp-xx-xx dyoung]# ls tmp
adm    db     games  lock  mail  named  rwho   state  www
cache  empty  lib    log   man   run    spool  tmp    yp
> > BTW btrfs subvolumes also use [] in findmnt output, how to differenciate them?
>
> For now, I don't test the btrfs.

btrfs is supported so we it need be taken care

Thanks
Dave

[Minfei Huang]

On 02/26/15 at 10:49am, Dave Young wrote:
> Hi, Minfei
> > > > -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> > > > /dev/mapper/atomicos-root
> > >
> > > There's no real dumping path for bind mount as we discussed in previous
> > > thread, right?
> >
> > We can construct the real dump path for the bind mounted, using findmnt.
> > As the above comment, we can identify the bind mount directory by using
> > findmnt command.
>
> No, it did not answer my question, As Karel said for bind mount is same as
> non-bind mount, see below the original source can be unmounted while the
> later bind mount still exist:
>
> [dyoung@dhcp-xx-xx dyoung]# mount /dev/sda7 /mnt/sda7
> [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7
> bin   dev  home  lib64       media  opt   dyoung  sbin  sys  usr
> boot  etc  lib   lost+found  mnt    proc  run   srv   tmp  var
> [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7/var
> adm    db     games  lock  mail  named  rwho   state  www
> cache  empty  lib    log   man   run    spool  tmp    yp
> [dyoung@dhcp-xx-xx dyoung]# mount -o bind /mnt/sda7/var tmp
> [dyoung@dhcp-xx-xx dyoung]# ls tmp
> adm    db     games  lock  mail  named  rwho   state  www
> cache  empty  lib    log   man   run    spool  tmp    yp
> [dyoung@dhcp-xx-xx dyoung]# umount /mnt/sda7
> [dyoung@dhcp-xx-xx dyoung]# ls tmp
> adm    db     games  lock  mail  named  rwho   state  www
> cache  empty  lib    log   man   run    spool  tmp    yp

Hi, Dave!

Yes, but we can use the findmnt to recognize the directory is bind
mounted or not, if the filesystem is not the btrfs.

In your case, we can find the fact that real path of tmp directory is
/dev/sda7[/var]. So we can dump core to the /dev/sda7[/var], if the
target is tmp.

The kdump's manner will be always correct, although the directory is
bind mounted.

Thanks
Minfei
> > > BTW btrfs subvolumes also use [] in findmnt output, how to differenciate them?
> >
> > For now, I don't test the btrfs.
>
> btrfs is supported so we it need be taken care
>
> Thanks
> Dave

[Baoquan He]

On 02/26/15 at 11:02am, Minfei Huang wrote:
> On 02/26/15 at 10:49am, Dave Young wrote:
> > Hi, Minfei
> > > > > -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> > > > > /dev/mapper/atomicos-root
> > > >
> > > > There's no real dumping path for bind mount as we discussed in previous
> > > > thread, right?
> > >
> > > We can construct the real dump path for the bind mounted, using findmnt.
> > > As the above comment, we can identify the bind mount directory by using
> > > findmnt command.
> >
> > No, it did not answer my question, As Karel said for bind mount is same as
> > non-bind mount, see below the original source can be unmounted while the
> > later bind mount still exist:
> >
> > [dyoung@dhcp-xx-xx dyoung]# mount /dev/sda7 /mnt/sda7
> > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7
> > bin   dev  home  lib64       media  opt   dyoung  sbin  sys  usr
> > boot  etc  lib   lost+found  mnt    proc  run   srv   tmp  var
> > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7/var
> > adm    db     games  lock  mail  named  rwho   state  www
> > cache  empty  lib    log   man   run    spool  tmp    yp
> > [dyoung@dhcp-xx-xx dyoung]# mount -o bind /mnt/sda7/var tmp
> > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > adm    db     games  lock  mail  named  rwho   state  www
> > cache  empty  lib    log   man   run    spool  tmp    yp
> > [dyoung@dhcp-xx-xx dyoung]# umount /mnt/sda7
> > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > adm    db     games  lock  mail  named  rwho   state  www
> > cache  empty  lib    log   man   run    spool  tmp    yp
>
> Hi, Dave!
>
> Yes, but we can use the findmnt to recognize the directory is bind
> mounted or not, if the filesystem is not the btrfs.
>
> In your case, we can find the fact that real path of tmp directory is
> /dev/sda7[/var]. So we can dump core to the /dev/sda7[/var], if the
> target is tmp.

Yeah, it looks reasonable for now.

I suggest you have a check on btrfs. Find a kvm guest and add a disk,
then make btrfs on that. It's easy to check if btrfs is special.
> The kdump's manner will be always correct, although the directory is
> bind mounted.
>
> Thanks
> Minfei

[Minfei Huang]

On 02/26/15 at 11:17am, Baoquan He wrote:
> On 02/26/15 at 11:02am, Minfei Huang wrote:
> > On 02/26/15 at 10:49am, Dave Young wrote:
> > > Hi, Minfei
> > > > > > -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> > > > > > /dev/mapper/atomicos-root
> > > > >
> > > > > There's no real dumping path for bind mount as we discussed in previous
> > > > > thread, right?
> > > >
> > > > We can construct the real dump path for the bind mounted, using findmnt.
> > > > As the above comment, we can identify the bind mount directory by using
> > > > findmnt command.
> > >
> > > No, it did not answer my question, As Karel said for bind mount is same as
> > > non-bind mount, see below the original source can be unmounted while the
> > > later bind mount still exist:
> > >
> > > [dyoung@dhcp-xx-xx dyoung]# mount /dev/sda7 /mnt/sda7
> > > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7
> > > bin   dev  home  lib64       media  opt   dyoung  sbin  sys  usr
> > > boot  etc  lib   lost+found  mnt    proc  run   srv   tmp  var
> > > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7/var
> > > adm    db     games  lock  mail  named  rwho   state  www
> > > cache  empty  lib    log   man   run    spool  tmp    yp
> > > [dyoung@dhcp-xx-xx dyoung]# mount -o bind /mnt/sda7/var tmp
> > > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > > adm    db     games  lock  mail  named  rwho   state  www
> > > cache  empty  lib    log   man   run    spool  tmp    yp
> > > [dyoung@dhcp-xx-xx dyoung]# umount /mnt/sda7
> > > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > > adm    db     games  lock  mail  named  rwho   state  www
> > > cache  empty  lib    log   man   run    spool  tmp    yp
> >
> > Hi, Dave!
> >
> > Yes, but we can use the findmnt to recognize the directory is bind
> > mounted or not, if the filesystem is not the btrfs.
> >
> > In your case, we can find the fact that real path of tmp directory is
> > /dev/sda7[/var]. So we can dump core to the /dev/sda7[/var], if the
> > target is tmp.
>
> Yeah, it looks reasonable for now.
>
> I suggest you have a check on btrfs. Find a kvm guest and add a disk,
> then make btrfs on that. It's easy to check if btrfs is special.

Agreed! The testing is still in process.

Thanks
Minfei
> > The kdump's manner will be always correct, although the directory is
> > bind mounted.
> >
> > Thanks
> > Minfei

[Dave Young]

On 02/26/15 at 11:02am, Minfei Huang wrote:
> On 02/26/15 at 10:49am, Dave Young wrote:
> > Hi, Minfei
> > > > > -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> > > > > /dev/mapper/atomicos-root
> > > >
> > > > There's no real dumping path for bind mount as we discussed in previous
> > > > thread, right?
> > >
> > > We can construct the real dump path for the bind mounted, using findmnt.
> > > As the above comment, we can identify the bind mount directory by using
> > > findmnt command.
> >
> > No, it did not answer my question, As Karel said for bind mount is same as
> > non-bind mount, see below the original source can be unmounted while the
> > later bind mount still exist:
> >
> > [dyoung@dhcp-xx-xx dyoung]# mount /dev/sda7 /mnt/sda7
> > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7
> > bin   dev  home  lib64       media  opt   dyoung  sbin  sys  usr
> > boot  etc  lib   lost+found  mnt    proc  run   srv   tmp  var
> > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7/var
> > adm    db     games  lock  mail  named  rwho   state  www
> > cache  empty  lib    log   man   run    spool  tmp    yp
> > [dyoung@dhcp-xx-xx dyoung]# mount -o bind /mnt/sda7/var tmp
> > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > adm    db     games  lock  mail  named  rwho   state  www
> > cache  empty  lib    log   man   run    spool  tmp    yp
> > [dyoung@dhcp-xx-xx dyoung]# umount /mnt/sda7
> > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > adm    db     games  lock  mail  named  rwho   state  www
> > cache  empty  lib    log   man   run    spool  tmp    yp
>
> Hi, Dave!
>
> Yes, but we can use the findmnt to recognize the directory is bind
> mounted or not, if the filesystem is not the btrfs.
>
> In your case, we can find the fact that real path of tmp directory is
> /dev/sda7[/var]. So we can dump core to the /dev/sda7[/var], if the
> target is tmp.
>
> The kdump's manner will be always correct, although the directory is
> bind mounted.

How did findmnt know this is a bindmnt, is it stable?
OTOH, we need consider more cases, such as non-root case I believe you tested
on atomic host. Have you tested normal bind mount test case, dump to root,
dump to non root, nfs, etc.?

Thanks
Dave

[Minfei Huang]

On 02/26/15 at 11:23am, Dave Young wrote:
> On 02/26/15 at 11:02am, Minfei Huang wrote:
> > On 02/26/15 at 10:49am, Dave Young wrote:
> > > Hi, Minfei
> > > > > > -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> > > > > > /dev/mapper/atomicos-root
> > > > >
> > > > > There's no real dumping path for bind mount as we discussed in previous
> > > > > thread, right?
> > > >
> > > > We can construct the real dump path for the bind mounted, using findmnt.
> > > > As the above comment, we can identify the bind mount directory by using
> > > > findmnt command.
> > >
> > > No, it did not answer my question, As Karel said for bind mount is same as
> > > non-bind mount, see below the original source can be unmounted while the
> > > later bind mount still exist:
> > >
> > > [dyoung@dhcp-xx-xx dyoung]# mount /dev/sda7 /mnt/sda7
> > > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7
> > > bin   dev  home  lib64       media  opt   dyoung  sbin  sys  usr
> > > boot  etc  lib   lost+found  mnt    proc  run   srv   tmp  var
> > > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7/var
> > > adm    db     games  lock  mail  named  rwho   state  www
> > > cache  empty  lib    log   man   run    spool  tmp    yp
> > > [dyoung@dhcp-xx-xx dyoung]# mount -o bind /mnt/sda7/var tmp
> > > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > > adm    db     games  lock  mail  named  rwho   state  www
> > > cache  empty  lib    log   man   run    spool  tmp    yp
> > > [dyoung@dhcp-xx-xx dyoung]# umount /mnt/sda7
> > > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > > adm    db     games  lock  mail  named  rwho   state  www
> > > cache  empty  lib    log   man   run    spool  tmp    yp
> >
> > Hi, Dave!
> >
> > Yes, but we can use the findmnt to recognize the directory is bind
> > mounted or not, if the filesystem is not the btrfs.
> >
> > In your case, we can find the fact that real path of tmp directory is
> > /dev/sda7[/var]. So we can dump core to the /dev/sda7[/var], if the
> > target is tmp.
> >
> > The kdump's manner will be always correct, although the directory is
> > bind mounted.
>
> How did findmnt know this is a bindmnt, is it stable?
> OTOH, we need consider more cases, such as non-root case I believe you tested
> on atomic host. Have you tested normal bind mount test case, dump to root,
> dump to non root, nfs, etc.?

Yes. I will test more cases to cover the generic testcase.

Thanks
Minfei
> Thanks
> Dave

[Dave Young]

On 02/26/15 at 01:02pm, Minfei Huang wrote:
> On 02/26/15 at 11:23am, Dave Young wrote:
> > On 02/26/15 at 11:02am, Minfei Huang wrote:
> > > On 02/26/15 at 10:49am, Dave Young wrote:
> > > > Hi, Minfei
> > > > > > >     -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> > > > > > >     /dev/mapper/atomicos-root
> > > > > >
> > > > > > There's no real dumping path for bind mount as we discussed in previous
> > > > > > thread, right?
> > > > >
> > > > > We can construct the real dump path for the bind mounted, using findmnt.
> > > > > As the above comment, we can identify the bind mount directory by using
> > > > > findmnt command.
> > > >
> > > > No, it did not answer my question, As Karel said for bind mount is same as
> > > > non-bind mount, see below the original source can be unmounted while the
> > > > later bind mount still exist:
> > > >
> > > > [dyoung@dhcp-xx-xx dyoung]# mount /dev/sda7 /mnt/sda7
> > > > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7
> > > > bin   dev  home  lib64       media  opt   dyoung  sbin  sys  usr
> > > > boot  etc  lib   lost+found  mnt    proc  run   srv   tmp  var
> > > > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7/var
> > > > adm    db     games  lock  mail  named  rwho   state  www
> > > > cache  empty  lib    log   man   run    spool  tmp    yp
> > > > [dyoung@dhcp-xx-xx dyoung]# mount -o bind /mnt/sda7/var tmp
> > > > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > > > adm    db     games  lock  mail  named  rwho   state  www
> > > > cache  empty  lib    log   man   run    spool  tmp    yp
> > > > [dyoung@dhcp-xx-xx dyoung]# umount /mnt/sda7
> > > > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > > > adm    db     games  lock  mail  named  rwho   state  www
> > > > cache  empty  lib    log   man   run    spool  tmp    yp
> > >
> > > Hi, Dave!
> > >
> > > Yes, but we can use the findmnt to recognize the directory is bind
> > > mounted or not, if the filesystem is not the btrfs.
> > >
> > > In your case, we can find the fact that real path of tmp directory is
> > > /dev/sda7[/var]. So we can dump core to the /dev/sda7[/var], if the
> > > target is tmp.
> > >
> > > The kdump's manner will be always correct, although the directory is
> > > bind mounted.
> >
> > How did findmnt know this is a bindmnt, is it stable?
> > OTOH, we need consider more cases, such as non-root case I believe you tested
> > on atomic host. Have you tested normal bind mount test case, dump to root,
> > dump to non root, nfs, etc.?
>
> Yes. I will test more cases to cover the generic testcase.

Also need consider nfs test case, especially it envolved [], you know ipv6 also use
[] in addresses..

Thanks
Dave

[Dave Young]

On 02/26/15 at 11:02am, Minfei Huang wrote:
> On 02/26/15 at 10:49am, Dave Young wrote:
> > Hi, Minfei
> > > > > -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
> > > > > /dev/mapper/atomicos-root
> > > >
> > > > There's no real dumping path for bind mount as we discussed in previous
> > > > thread, right?
> > >
> > > We can construct the real dump path for the bind mounted, using findmnt.
> > > As the above comment, we can identify the bind mount directory by using
> > > findmnt command.
> >
> > No, it did not answer my question, As Karel said for bind mount is same as
> > non-bind mount, see below the original source can be unmounted while the
> > later bind mount still exist:
> >
> > [dyoung@dhcp-xx-xx dyoung]# mount /dev/sda7 /mnt/sda7
> > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7
> > bin   dev  home  lib64       media  opt   dyoung  sbin  sys  usr
> > boot  etc  lib   lost+found  mnt    proc  run   srv   tmp  var
> > [dyoung@dhcp-xx-xx dyoung]# ls /mnt/sda7/var
> > adm    db     games  lock  mail  named  rwho   state  www
> > cache  empty  lib    log   man   run    spool  tmp    yp
> > [dyoung@dhcp-xx-xx dyoung]# mount -o bind /mnt/sda7/var tmp
> > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > adm    db     games  lock  mail  named  rwho   state  www
> > cache  empty  lib    log   man   run    spool  tmp    yp
> > [dyoung@dhcp-xx-xx dyoung]# umount /mnt/sda7
> > [dyoung@dhcp-xx-xx dyoung]# ls tmp
> > adm    db     games  lock  mail  named  rwho   state  www
> > cache  empty  lib    log   man   run    spool  tmp    yp
>
> Hi, Dave!
>
> Yes, but we can use the findmnt to recognize the directory is bind
> mounted or not, if the filesystem is not the btrfs.
>
> In your case, we can find the fact that real path of tmp directory is
> /dev/sda7[/var]. So we can dump core to the /dev/sda7[/var], if the
> target is tmp.
>
> The kdump's manner will be always correct, although the directory is
> bind mounted.

looking below code in mkdumprd:
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)

The _source will contain [] for bindmnt, I'm afraid it will fail on 2nd kernel

Thanks
Dave