[PATCH 0/2 v2] Crash dump is saved in /sysroot/crash instead of /var/crash in Atomic

[Minfei Huang]

The kdump cannot dump the core in the correct directory in Atomic,
if set the path "/var/crash" in the /etc/kdump.conf. We found that
kdump cannot deal with the bind mounts correctly.

Fix this issue to make kdump dump core correctly.

v2:
- fix the issue to dump directory /var/crash correctly in Atomic.
- wrap the common function dump_common_fs to handle the dump core
- Add a new function to determine the directory is bind mounts or not

v1:
- fix the issue to dump directory /sysroot/var/crash instead of /sysroot/crash in Atomic

Minfei Huang (2):
  dracut-moduel-setup: Filte the bind mounted directory in the Atomic
  kdump-lib-initramfs: Dump the correct directory in the Atomic

 kdump-lib-initramfs.sh | 91 +++++++++++++++++++++++++++++++++++++++++++-------
 kdump-lib.sh           | 43 +++++++++++++++++++++++-
 2 files changed, 121 insertions(+), 13 deletions(-)

-- 
2.2.2

[PATCH 1/2 v2] dracut-moduel-setup: Filte the bind mounted directory in the Atomic

[Minfei Huang]

The crash dump is saved in the /sysroot/crash directory, not the
/sysroot/var/crash in the atomic system.

We found we have the uncorrect dump directory, when we use command
"findmnt" to find the dump directory's mountpoint which is a bind
mounted directory.

To solve this issue, we should determine the real mountpont, if the
directory is a bind mounted directory.

Signed-off-by: Minfei Huang <mhuang(a)redhat.com&gt;
---
 kdump-lib.sh | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/kdump-lib.sh b/kdump-lib.sh
index f24f08d..e4df376 100755
--- a/kdump-lib.sh
+++ b/kdump-lib.sh
@@ -86,9 +86,41 @@ get_root_fs_device()
     return
 }
 
+# findmnt uses the option "-v, --nofsroot" to exclusive the [/dir]
+# in the SOURCE column for bind-mounts, then if $_dev equals to
+# $_dev_no_bind, the mountpoint is not bind mounted directory.
+is_bind_mount()
+{
+    local _dev=$(findmnt -k -n -r -o SOURCE $1)
+    local _dev_no_bind=$(findmnt -k -n -r -v -o SOURCE $1)
+
+    if [[ $_dev = $_dev_no_bind ]]; then
+        return 1
+    else
+        return 0
+    fi
+}
+
+# We are looking to see if a part of dump path is mounted on some disk.
+# But we don't want to look for bind mounted directories. So we should
+# determine the real mountpoint, if the directory is a bind mounted
+# directory.
 get_mntpoint_from_path() 
 {
-    echo $(df $1 | tail -1 |  awk '{print $NF}')
+    local _mnt=$(df $1 | tail -1 |  awk '{print $NF}')
+
+    if is_bind_mount $mnt; then
+        # bind mounted directory, we should find the real mount point
+        # where the device mounts.
+        for m in `findmnt -k -n -r -o TARGET $_dev_no_bind`; do
+            if ! is_bind_mount $m; then
+                echo $m
+                break
+            fi
+        done
+    else
+        echo $_mnt
+    fi
 }
 
 get_target_from_path()
-- 
2.2.2

[PATCH 2/2 v2] kdump-lib-initramfs: Dump the correct directory in the Atomic

[Minfei Huang]

If set the dump target "/var/crash", the kdump will save the core in
/sysroot/var/crash, instead of /var/crash.

The mount point "/sysroot" is a special directory in Atomic, that it
will conflict in 2nd kernel where kdump will mount the "/" on the mount
point "/sysroot/".

To solve it, handle the Atomic kdump specially. If is the Atomic and
kdump path is the subdirectory in "/var/", save the core to the path
which specified in the /etc/kdump.conf directly.

Signed-off-by: Minfei Huang <mhuang(a)redhat.com&gt;
---
 kdump-lib-initramfs.sh | 91 +++++++++++++++++++++++++++++++++++++++++++-------
 kdump-lib.sh           |  9 +++++
 2 files changed, 88 insertions(+), 12 deletions(-)

diff --git a/kdump-lib-initramfs.sh b/kdump-lib-initramfs.sh
index 57b8304..8ccd72c 100755
--- a/kdump-lib-initramfs.sh
+++ b/kdump-lib-initramfs.sh
@@ -81,10 +81,74 @@ get_kdump_confs()
     fi
 }
 
-# dump_fs <mount point| device>
-dump_fs()
+dump_common_fs()
+{
+    local _mp=$1
+
+    # Remove -F in makedumpfile case. We don't want a flat format dump here.
+    [[ $CORE_COLLECTOR = *makedumpfile* ]] && CORE_COLLECTOR=`echo
$CORE_COLLECTOR | sed -e "s/-F//g"`
+
+    mkdir -p $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR || return 1
+
+    save_vmcore_dmesg_fs ${DMESG_COLLECTOR}
"$_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/"
+
+    echo "kdump: saving vmcore"
+    $CORE_COLLECTOR /proc/vmcore $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore-incomplete ||
return 1
+    mv $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore-incomplete
$_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore
+    sync
+
+    echo "kdump: saving vmcore complete"
+}
+
+is_ostree() {
+    local _ostree=$(getarg ostree=)
+    if test -n "${_ostree}"; then
+        return 0
+    fi
+    return 1
+}
+
+# find out the specified target in Atomic, like /var
+atomic_specified_path()
+{
+    local _path=""
+
+    for p in "var/" "/var/"; do
+        if [[ $KDUMP_PATH =~ "$p"* ]]; then
+            _path="/$p"
+            break
+        fi
+    done
+    echo $_path
+}
+
+is_atomic_specified_path()
 {
+    local _path=$(atomic_specified_path)
+    if [[ "x" = "x$_path" ]]; then
+        echo 1
+    else
+        echo 0
+    fi
+}
+
+# handle the special case Atomic, if the target is "/var". Due to the
+# bind mounted directory /var, we hard code the real path of /var
+# where the /var is in.
+dump_atomic_rootfs()
+{
+    local _mp=$NEWROOT
+    local _bind_mp="$_mp/ostree/deploy/rhel-atomic-host"
+
+    echo "kdump: saving to $_bind_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/"
+    mount -o remount,rw $_mp || return 1
 
+    dump_common_fs $_bind_mp
+    return $?
+}
+
+dump_generic_fs()
+{
     local _dev=$(findmnt -k -f -n -r -o SOURCE $1)
     local _mp=$(findmnt -k -f -n -r -o TARGET $1)
 
@@ -95,22 +159,25 @@ dump_fs()
         return 1
     fi
 
-    # Remove -F in makedumpfile case. We don't want a flat format dump here.
-    [[ $CORE_COLLECTOR = *makedumpfile* ]] && CORE_COLLECTOR=`echo
$CORE_COLLECTOR | sed -e "s/-F//g"`
-
     echo "kdump: saving to $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/"
 
     mount -o remount,rw $_mp || return 1
-    mkdir -p $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR || return 1
 
-    save_vmcore_dmesg_fs ${DMESG_COLLECTOR}
"$_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/"
+    dump_common_fs $_mp
 
-    echo "kdump: saving vmcore"
-    $CORE_COLLECTOR /proc/vmcore $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore-incomplete ||
return 1
-    mv $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore-incomplete
$_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore
-    sync
+    return $?
+}
 
-    echo "kdump: saving vmcore complete"
+# dump_fs <mount point| device>
+dump_fs()
+{
+
+    if is_ostree && is_atomic_specified_path && is_rootfs; then
+        dump_atomic_rootfs
+    else
+        dump_generic_fs $1
+    fi
+    return $?
 }
 
 save_vmcore_dmesg_fs() {
diff --git a/kdump-lib.sh b/kdump-lib.sh
index e4df376..81f2969 100755
--- a/kdump-lib.sh
+++ b/kdump-lib.sh
@@ -17,6 +17,15 @@ is_nfs_dump_target()
     grep -q "^nfs" /etc/kdump.conf
 }
 
+is_rootfs()
+{
+    if is_ssh_dump_target || is_nfs_dump_target; then
+        return 1
+    else
+        return 0
+    fi
+}
+
 is_raw_dump_target()
 {
     grep -q "^raw" /etc/kdump.conf
-- 
2.2.2

[PATCH 1/2 v2] dracut-moduel-setup: Filte the bind mounted directory in the Atomic

[Dave Young]

Karel Zak is maintaining util-linux, he as a blog about bind mount:
http://karelzak.blogspot.sg/2011/04/bind-mounts-mtab-and-read-only.html

Ccing him. Karel, can you help reviewing this patch to differenciate
bind mount?

On 02/10/15 at 06:46pm, Minfei Huang wrote:
>  The crash dump is saved in the /sysroot/crash directory, not the
>  /sysroot/var/crash in the atomic system.
>  
>  We found we have the uncorrect dump directory, when we use command
>  "findmnt" to find the dump directory's mountpoint which is a bind
>  mounted directory.
>  
>  To solve this issue, we should determine the real mountpont, if the
>  directory is a bind mounted directory.
>  
>  Signed-off-by: Minfei Huang <mhuang(a)redhat.com&gt;
>  ---
>   kdump-lib.sh | 34 +++++++++++++++++++++++++++++++++-
>   1 file changed, 33 insertions(+), 1 deletion(-)
>  
>  diff --git a/kdump-lib.sh b/kdump-lib.sh
>  index f24f08d..e4df376 100755
>  --- a/kdump-lib.sh
>  +++ b/kdump-lib.sh
>  @@ -86,9 +86,41 @@ get_root_fs_device()
>       return
>   }
>   
>  +# findmnt uses the option "-v, --nofsroot" to exclusive the [/dir]
>  +# in the SOURCE column for bind-mounts, then if $_dev equals to
>  +# $_dev_no_bind, the mountpoint is not bind mounted directory.
>  +is_bind_mount()
>  +{
>  +    local _dev=$(findmnt -k -n -r -o SOURCE $1)
>  +    local _dev_no_bind=$(findmnt -k -n -r -v -o SOURCE $1)
>  +
>  +    if [[ $_dev = $_dev_no_bind ]]; then
>  +        return 1
>  +    else
>  +        return 0
>  +    fi
>  +}
>  +
>  +# We are looking to see if a part of dump path is mounted on some disk.
>  +# But we don't want to look for bind mounted directories. So we should
>  +# determine the real mountpoint, if the directory is a bind mounted
>  +# directory.
>   get_mntpoint_from_path() 
>   {
>  -    echo $(df $1 | tail -1 |  awk '{print $NF}')
>  +    local _mnt=$(df $1 | tail -1 |  awk '{print $NF}')
>  +
>  +    if is_bind_mount $mnt; then
>  +        # bind mounted directory, we should find the real mount point
>  +        # where the device mounts.
>  +        for m in `findmnt -k -n -r -o TARGET $_dev_no_bind`; do
>  +            if ! is_bind_mount $m; then
>  +                echo $m
>  +                break
>  +            fi
>  +        done
>  +    else
>  +        echo $_mnt
>  +    fi
>   }
>   
>   get_target_from_path()
>  -- 
>  2.2.2
>  
>  _______________________________________________
>  kexec mailing list
>  kexec(a)lists.fedoraproject.org
>  https://lists.fedoraproject.org/mailman/listinfo/kexec
>  
>

[PATCH 2/2 v2] kdump-lib-initramfs: Dump the correct directory in the Atomic

[Dave Young]

On 02/10/15 at 06:46pm, Minfei Huang wrote:
>  If set the dump target "/var/crash", the kdump will save
> the core in
>  /sysroot/var/crash, instead of /var/crash.
>  
>  The mount point "/sysroot" is a special directory in Atomic, that it
>  will conflict in 2nd kernel where kdump will mount the "/" on the mount
>  point "/sysroot/".
>  
>  To solve it, handle the Atomic kdump specially. If is the Atomic and
>  kdump path is the subdirectory in "/var/", save the core to the path
>  which specified in the /etc/kdump.conf directly. 
Minfei, it does not explain why it does not works originally, I will assume
it is because dracut use /sysroot as NEWROOT mount point but there's already
/sysroot, thus the rootfs mounting fails, right? Please explain it in changelog
so that we will know the problem better.

I did not look the patch detail but I feel it is bad to add another special case.

Here is a line in dracut to set NEWROOT:
Have you tried to provide some parameters to dracut so that it can use a different
NEWROOT? 
modules.d/98systemd/dracut-mount.service:Environment=NEWROOT=/sysroot

Rethink about it, since dracut is use /sysroot as mount point, really atomic should 
choose another dir name instead of /sysroot which conflicts with dracut.

Jeremy and Colin?

>  
>  Signed-off-by: Minfei Huang <mhuang(a)redhat.com&gt;
>  ---
>   kdump-lib-initramfs.sh | 91 +++++++++++++++++++++++++++++++++++++++++++-------
>   kdump-lib.sh           |  9 +++++
>   2 files changed, 88 insertions(+), 12 deletions(-)
>  
>  diff --git a/kdump-lib-initramfs.sh b/kdump-lib-initramfs.sh
>  index 57b8304..8ccd72c 100755
>  --- a/kdump-lib-initramfs.sh
>  +++ b/kdump-lib-initramfs.sh
>  @@ -81,10 +81,74 @@ get_kdump_confs()
>       fi
>   }
>   
>  -# dump_fs <mount point| device>
>  -dump_fs()
>  +dump_common_fs()
>  +{
>  +    local _mp=$1
>  +
>  +    # Remove -F in makedumpfile case. We don't want a flat format dump here.
>  +    [[ $CORE_COLLECTOR = *makedumpfile* ]] && CORE_COLLECTOR=`echo
> $CORE_COLLECTOR | sed -e "s/-F//g"`
>  +
>  +    mkdir -p $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR || return 1
>  +
>  +    save_vmcore_dmesg_fs ${DMESG_COLLECTOR}
> "$_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/"
>  +
>  +    echo "kdump: saving vmcore"
>  +    $CORE_COLLECTOR /proc/vmcore $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore-incomplete ||
> return 1
>  +    mv $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore-incomplete
> $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore
>  +    sync
>  +
>  +    echo "kdump: saving vmcore complete"
>  +}
>  +
>  +is_ostree() {
>  +    local _ostree=$(getarg ostree=)
>  +    if test -n "${_ostree}"; then
>  +        return 0
>  +    fi
>  +    return 1
>  +}
>  +
>  +# find out the specified target in Atomic, like /var
>  +atomic_specified_path()
>  +{
>  +    local _path=""
>  +
>  +    for p in "var/" "/var/"; do
>  +        if [[ $KDUMP_PATH =~ "$p"* ]]; then
>  +            _path="/$p"
>  +            break
>  +        fi
>  +    done
>  +    echo $_path
>  +}
>  +
>  +is_atomic_specified_path()
>   {
>  +    local _path=$(atomic_specified_path)
>  +    if [[ "x" = "x$_path" ]]; then
>  +        echo 1
>  +    else
>  +        echo 0
>  +    fi
>  +}
>  +
>  +# handle the special case Atomic, if the target is "/var". Due to the
>  +# bind mounted directory /var, we hard code the real path of /var
>  +# where the /var is in.
>  +dump_atomic_rootfs()
>  +{
>  +    local _mp=$NEWROOT
>  +    local _bind_mp="$_mp/ostree/deploy/rhel-atomic-host"
>  +
>  +    echo "kdump: saving to $_bind_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/"
>  +    mount -o remount,rw $_mp || return 1
>   
>  +    dump_common_fs $_bind_mp
>  +    return $?
>  +}
>  +
>  +dump_generic_fs()
>  +{
>       local _dev=$(findmnt -k -f -n -r -o SOURCE $1)
>       local _mp=$(findmnt -k -f -n -r -o TARGET $1)
>   
>  @@ -95,22 +159,25 @@ dump_fs()
>           return 1
>       fi
>   
>  -    # Remove -F in makedumpfile case. We don't want a flat format dump here.
>  -    [[ $CORE_COLLECTOR = *makedumpfile* ]] && CORE_COLLECTOR=`echo
> $CORE_COLLECTOR | sed -e "s/-F//g"`
>  -
>       echo "kdump: saving to $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/"
>   
>       mount -o remount,rw $_mp || return 1
>  -    mkdir -p $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR || return 1
>   
>  -    save_vmcore_dmesg_fs ${DMESG_COLLECTOR}
> "$_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/"
>  +    dump_common_fs $_mp
>   
>  -    echo "kdump: saving vmcore"
>  -    $CORE_COLLECTOR /proc/vmcore $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore-incomplete ||
> return 1
>  -    mv $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore-incomplete
> $_mp/$KDUMP_PATH/$HOST_IP-$DATEDIR/vmcore
>  -    sync
>  +    return $?
>  +}
>   
>  -    echo "kdump: saving vmcore complete"
>  +# dump_fs <mount point| device>
>  +dump_fs()
>  +{
>  +
>  +    if is_ostree && is_atomic_specified_path && is_rootfs; then
>  +        dump_atomic_rootfs
>  +    else
>  +        dump_generic_fs $1
>  +    fi
>  +    return $?
>   }
>   
>   save_vmcore_dmesg_fs() {
>  diff --git a/kdump-lib.sh b/kdump-lib.sh
>  index e4df376..81f2969 100755
>  --- a/kdump-lib.sh
>  +++ b/kdump-lib.sh
>  @@ -17,6 +17,15 @@ is_nfs_dump_target()
>       grep -q "^nfs" /etc/kdump.conf
>   }
>   
>  +is_rootfs()
>  +{
>  +    if is_ssh_dump_target || is_nfs_dump_target; then
>  +        return 1
>  +    else
>  +        return 0
>  +    fi
>  +}
>  +
>   is_raw_dump_target()
>   {
>       grep -q "^raw" /etc/kdump.conf
>  -- 
>  2.2.2
>  
>  _______________________________________________
>  kexec mailing list
>  kexec(a)lists.fedoraproject.org
>  https://lists.fedoraproject.org/mailman/listinfo/kexec
>  
>

[PATCH 1/2 v2] dracut-moduel-setup: Filte the bind mounted directory in the Atomic

[Karel Zak]

On Wed, Feb 11, 2015 at 03:17:48PM +0800, Dave Young wrote:
>  Karel Zak is maintaining util-linux, he as a blog about bind mount:
>  http://karelzak.blogspot.sg/2011/04/bind-mounts-mtab-and-read-only.html
>  
>  Ccing him. Karel, can you help reviewing this patch to differenciate
>  bind mount? 
It seems I need new blog post to more explicitly explain that there is
no "bind mounts" at all, the "bind" is operation, not status.

>  On 02/10/15 at 06:46pm, Minfei Huang wrote:
>  > To solve this issue, we should determine the real mountpont, if the
>  > directory is a bind mounted directory. 
There is no real and bind mountpoint, both is the same thing. The
bind operation creates another independent connection to the filesystem.

>  > +# findmnt uses the option "-v, --nofsroot" to
> exclusive the [/dir]
>  > +# in the SOURCE column for bind-mounts, then if $_dev equals to
>  > +# $_dev_no_bind, the mountpoint is not bind mounted directory. 
The [/dir] means that you have mounted subdirectory rather than root
of the filesystem.

  mount /dev/sdc1 /mnt/A
  mkdir /mnt/A/subdir

  mount --bind /mnt/A/subdir /mnt/B
  mount --bind /mnt/A        /mnt/C

  TARGET SOURCE             FSTYPE OPTIONS
  /mnt/A /dev/sdc1          ext4   rw,relatime,seclabel,stripe=32,data=ordered
  /mnt/B /dev/sdc1[/subdir] ext4   rw,relatime,seclabel,stripe=32,data=ordered
  /mnt/C /dev/sdc1          ext4   rw,relatime,seclabel,stripe=32,data=ordered

... for /mnt/C there is no [/dir]


Note that btrfs uses the same if you mount btrfs subvolume.

>  > +is_bind_mount()
>  > +{
>  > +    local _dev=$(findmnt -k -n -r -o SOURCE $1)
>  > +    local _dev_no_bind=$(findmnt -k -n -r -v -o SOURCE $1)
>  > +
>  > +    if [[ $_dev = $_dev_no_bind ]]; then
>  > +        return 1
>  > +    else
>  > +        return 0
>  > +    fi
>  > +}
>  > +
>  > +# We are looking to see if a part of dump path is mounted on some disk.
>  > +# But we don't want to look for bind mounted directories. So we should
>  > +# determine the real mountpoint, if the directory is a bind mounted
>  > +# directory.
>  >  get_mntpoint_from_path() 
>  >  {
>  > -    echo $(df $1 | tail -1 |  awk '{print $NF}')
>  > +    local _mnt=$(df $1 | tail -1 |  awk '{print $NF}') 
 local _mnt=$(findmnt -n -o TARGET --target $1)

>  > +
>  > +    if is_bind_mount $mnt; then
>  > +        # bind mounted directory, we should find the real mount point
>  > +        # where the device mounts.
>  > +        for m in `findmnt -k -n -r -o TARGET $_dev_no_bind`; do
>  > +            if ! is_bind_mount $m; then
>  > +                echo $m
>  > +                break
>  > +            fi
>  > +        done 
 The mountpoint created by bind operation is independent on previous
 mounts,

  mount /mnt/sda1 /A
  mount --bind /A /B
  umount /A

 is pretty valid situation and /B still points to the filesystem.

>  > +    else
>  > +        echo $_mnt
>  > +    fi
>  >  } 
 I'm not sure if I good understand the original problem, but I'm sure
 that care about bind mounts is mistake ;-)  If the problem is that
 dump is not in the filesystem root then you can try to check if the
 root of the filesystem is mounted somewhere else, but maybe the best
 would be avoid such fragile setup at all.

    Karel

-- 
 Karel Zak  <kzak(a)redhat.com&gt;
 http://karelzak.blogspot.com

[PATCH 2/2 v2] kdump-lib-initramfs: Dump the correct directory in the Atomic

[Colin Walters]

>  Rethink about it, since dracut is use /sysroot as mount point, really
> atomic
>  should
>  choose another dir name instead of /sysroot which conflicts with dracut. 
Without investigating closely, there's no conflict here, it's just confusing.
In the initramfs, there exists a /sysroot that points to the physical storage.

Thus, there is a:

/sysroot/ostree/deploy/rhel-atomic-host/deploy/$checksum.$serial/sysroot

When booted, there is also a /sysroot which points to the physical storage.

But I don't believe there is a point where there is an actual conflict.

[PATCH 1/2 v2] dracut-moduel-setup: Filte the bind mounted directory in the Atomic

[Dave Young]

Karel

Thanks a lot for your comments, it is helpful to us.

On 02/11/15 at 12:39pm, Karel Zak wrote:
>  On Wed, Feb 11, 2015 at 03:17:48PM +0800, Dave Young wrote:
>  > Karel Zak is maintaining util-linux, he as a blog about bind mount:
>  > http://karelzak.blogspot.sg/2011/04/bind-mounts-mtab-and-read-only.html
>  > 
>  > Ccing him. Karel, can you help reviewing this patch to differenciate
>  > bind mount?
>  
>  It seems I need new blog post to more explicitly explain that there is
>  no "bind mounts" at all, the "bind" is operation, not status. 
Ok, so there's nothing we can do to differenciate them because they are
just same..

>  
>  > On 02/10/15 at 06:46pm, Minfei Huang wrote:
>  > > To solve this issue, we should determine the real mountpont, if the
>  > > directory is a bind mounted directory.
>  
>  There is no real and bind mountpoint, both is the same thing. The
>  bind operation creates another independent connection to the filesystem.
>  
>  > > +# findmnt uses the option "-v, --nofsroot" to exclusive the [/dir]
>  > > +# in the SOURCE column for bind-mounts, then if $_dev equals to
>  > > +# $_dev_no_bind, the mountpoint is not bind mounted directory.
>  
>  The [/dir] means that you have mounted subdirectory rather than root
>  of the filesystem.
>  
>    mount /dev/sdc1 /mnt/A
>    mkdir /mnt/A/subdir
>  
>    mount --bind /mnt/A/subdir /mnt/B
>    mount --bind /mnt/A        /mnt/C
>  
>    TARGET SOURCE             FSTYPE OPTIONS
>    /mnt/A /dev/sdc1          ext4   rw,relatime,seclabel,stripe=32,data=ordered
>    /mnt/B /dev/sdc1[/subdir] ext4   rw,relatime,seclabel,stripe=32,data=ordered
>    /mnt/C /dev/sdc1          ext4   rw,relatime,seclabel,stripe=32,data=ordered
>  
>  ... for /mnt/C there is no [/dir]
>  
>  
>  Note that btrfs uses the same if you mount btrfs subvolume.
>  
>  > > +is_bind_mount()
>  > > +{
>  > > +    local _dev=$(findmnt -k -n -r -o SOURCE $1)
>  > > +    local _dev_no_bind=$(findmnt -k -n -r -v -o SOURCE $1)
>  > > +
>  > > +    if [[ $_dev = $_dev_no_bind ]]; then
>  > > +        return 1
>  > > +    else
>  > > +        return 0
>  > > +    fi
>  > > +}
>  > > +
>  > > +# We are looking to see if a part of dump path is mounted on some disk.
>  > > +# But we don't want to look for bind mounted directories. So we should
>  > > +# determine the real mountpoint, if the directory is a bind mounted
>  > > +# directory.
>  > >  get_mntpoint_from_path() 
>  > >  {
>  > > -    echo $(df $1 | tail -1 |  awk '{print $NF}')
>  > > +    local _mnt=$(df $1 | tail -1 |  awk '{print $NF}')
>  
>   local _mnt=$(findmnt -n -o TARGET --target $1)
>  
>  > > +
>  > > +    if is_bind_mount $mnt; then
>  > > +        # bind mounted directory, we should find the real mount point
>  > > +        # where the device mounts.
>  > > +        for m in `findmnt -k -n -r -o TARGET $_dev_no_bind`; do
>  > > +            if ! is_bind_mount $m; then
>  > > +                echo $m
>  > > +                break
>  > > +            fi
>  > > +        done
>  
>   The mountpoint created by bind operation is independent on previous
>   mounts,
>  
>    mount /mnt/sda1 /A
>    mount --bind /A /B
>    umount /A
>  
>   is pretty valid situation and /B still points to the filesystem. 
Hmm, got it, so they are equal, but for subdirectory mount there will be
dependency?

>  
>  > > +    else
>  > > +        echo $_mnt
>  > > +    fi
>  > >  }
>  
>   I'm not sure if I good understand the original problem, but I'm sure
>   that care about bind mounts is mistake ;-)  If the problem is that
>   dump is not in the filesystem root then you can try to check if the
>   root of the filesystem is mounted somewhere else, but maybe the best
>   would be avoid such fragile setup at all. 
We need to know more about the setup of atomic systems, will add you to
the rh bug cc

Thanks
Dave

[PATCH 2/2 v2] kdump-lib-initramfs: Dump the correct directory in the Atomic

[Dave Young]

On 02/11/15 at 04:19pm, Colin Walters wrote:
>  > Rethink about it, since dracut is use /sysroot as mount point,
> really atomic
>  > should
>  > choose another dir name instead of /sysroot which conflicts with dracut.
>  
>  Without investigating closely, there's no conflict here, it's just confusing.
>  In the initramfs, there exists a /sysroot that points to the physical storage. 
Dracut is using /sysroot as mounting point for real root since the very beginning
Also see below systemd doc (Sectin "Bootup in the Initial RAM Disk):
http://www.freedesktop.org/software/systemd/man/bootup.html

It says " If the root device can be mounted at /sysroot, the sysroot.mount unit
becomes active and initrd-root-fs.target is reached.

So there's many assumptions about /sysroot...
>  
>  Thus, there is a:
>  
>  /sysroot/ostree/deploy/rhel-atomic-host/deploy/$checksum.$serial/sysroot
>  
>  When booted, there is also a /sysroot which points to the physical storage.
>  
>  But I don't believe there is a point where there is an actual conflict.
>  
>

[PATCH 2/2 v2] kdump-lib-initramfs: Dump the correct directory in the Atomic

[Harald Hoyer]

On 12.02.2015 07:00, Dave Young wrote:
>  On 02/11/15 at 04:19pm, Colin Walters wrote:
> >> Rethink about it, since dracut is use /sysroot as mount point, really atomic
> >> should
> >> choose another dir name instead of /sysroot which conflicts with dracut.
> >
> > Without investigating closely, there's no conflict here, it's just
> confusing.
> > In the initramfs, there exists a /sysroot that points to the physical storage.
>  
>  Dracut is using /sysroot as mounting point for real root since the very beginning
>  Also see below systemd doc (Sectin "Bootup in the Initial RAM Disk):
>  http://www.freedesktop.org/software/systemd/man/bootup.html
>  
>  It says " If the root device can be mounted at /sysroot, the sysroot.mount unit
>  becomes active and initrd-root-fs.target is reached.
>  
>  So there's many assumptions about /sysroot... 
Note:  initrd-root-fs.target 
also has an additional condition

ConditionPathExists=/etc/initrd-release

So, that on normal systems, the target is not activated.

> >
> > Thus, there is a:
> >
> > /sysroot/ostree/deploy/rhel-atomic-host/deploy/$checksum.$serial/sysroot
> >
> > When booted, there is also a /sysroot which points to the physical storage.
> >
> > But I don't believe there is a point where there is an actual conflict.
> >
> >

[PATCH 1/2 v2] dracut-moduel-setup: Filte the bind mounted directory in the Atomic

[Karel Zak]

On Thu, Feb 12, 2015 at 01:50:32PM +0800, Dave Young wrote:
>  >  The mountpoint created by bind operation is independent on
> previous
>  >  mounts,
>  > 
>  >   mount /mnt/sda1 /A
>  >   mount --bind /A /B
>  >   umount /A
>  > 
>  >  is pretty valid situation and /B still points to the filesystem.
>  
>  Hmm, got it, so they are equal, but for subdirectory mount there will be
>  dependency? 
 No, you can still umount, it's just kernel feature that mount can
 points to non-root filesystem directory.

 # findmnt /dev/sdc1
 TARGET SOURCE             FSTYPE OPTIONS
 /mnt/B /dev/sdc1[/subdir] ext4   rw,relatime,seclabel,stripe=32,data=ordered
 /mnt/A /dev/sdc1          ext4   rw,relatime,seclabel,stripe=32,data=ordered

 # umount /mnt/A

 # findmnt /dev/sdc1
 TARGET SOURCE             FSTYPE OPTIONS
 /mnt/B /dev/sdc1[/subdir] ext4   rw,relatime,seclabel,stripe=32,data=ordered


    Karel

-- 
 Karel Zak  <kzak(a)redhat.com&gt;
 http://karelzak.blogspot.com

[PATCH 1/2 v2] dracut-moduel-setup: Filte the bind mounted directory in the Atomic

[Minfei Huang]

On 02/11/15 at 12:39pm, Karel Zak wrote:
>  On Wed, Feb 11, 2015 at 03:17:48PM +0800, Dave Young wrote:
>  > Karel Zak is maintaining util-linux, he as a blog about bind mount:
>  > http://karelzak.blogspot.sg/2011/04/bind-mounts-mtab-and-read-only.html
>  > 
>  > Ccing him. Karel, can you help reviewing this patch to differenciate
>  > bind mount?
>  
>  It seems I need new blog post to more explicitly explain that there is
>  no "bind mounts" at all, the "bind" is operation, not status.
>  
>  > On 02/10/15 at 06:46pm, Minfei Huang wrote:
>  > > To solve this issue, we should determine the real mountpont, if the
>  > > directory is a bind mounted directory.
>  
>  There is no real and bind mountpoint, both is the same thing. The
>  bind operation creates another independent connection to the filesystem.
>  
>  > > +# findmnt uses the option "-v, --nofsroot" to exclusive the [/dir]
>  > > +# in the SOURCE column for bind-mounts, then if $_dev equals to
>  > > +# $_dev_no_bind, the mountpoint is not bind mounted directory.
>  
>  The [/dir] means that you have mounted subdirectory rather than root
>  of the filesystem.
>  
>    mount /dev/sdc1 /mnt/A
>    mkdir /mnt/A/subdir
>  
>    mount --bind /mnt/A/subdir /mnt/B
>    mount --bind /mnt/A        /mnt/C
>  
>    TARGET SOURCE             FSTYPE OPTIONS
>    /mnt/A /dev/sdc1          ext4   rw,relatime,seclabel,stripe=32,data=ordered
>    /mnt/B /dev/sdc1[/subdir] ext4   rw,relatime,seclabel,stripe=32,data=ordered
>    /mnt/C /dev/sdc1          ext4   rw,relatime,seclabel,stripe=32,data=ordered
>  
>  ... for /mnt/C there is no [/dir]
>  
>  
>  Note that btrfs uses the same if you mount btrfs subvolume.
>  
>  > > +is_bind_mount()
>  > > +{
>  > > +    local _dev=$(findmnt -k -n -r -o SOURCE $1)
>  > > +    local _dev_no_bind=$(findmnt -k -n -r -v -o SOURCE $1)
>  > > +
>  > > +    if [[ $_dev = $_dev_no_bind ]]; then
>  > > +        return 1
>  > > +    else
>  > > +        return 0
>  > > +    fi
>  > > +}
>  > > +
>  > > +# We are looking to see if a part of dump path is mounted on some disk.
>  > > +# But we don't want to look for bind mounted directories. So we should
>  > > +# determine the real mountpoint, if the directory is a bind mounted
>  > > +# directory.
>  > >  get_mntpoint_from_path() 
>  > >  {
>  > > -    echo $(df $1 | tail -1 |  awk '{print $NF}')
>  > > +    local _mnt=$(df $1 | tail -1 |  awk '{print $NF}')
>  
>   local _mnt=$(findmnt -n -o TARGET --target $1)
>  
>  > > +
>  > > +    if is_bind_mount $mnt; then
>  > > +        # bind mounted directory, we should find the real mount point
>  > > +        # where the device mounts.
>  > > +        for m in `findmnt -k -n -r -o TARGET $_dev_no_bind`; do
>  > > +            if ! is_bind_mount $m; then
>  > > +                echo $m
>  > > +                break
>  > > +            fi
>  > > +        done
>  
>   The mountpoint created by bind operation is independent on previous
>   mounts,
>  
>    mount /mnt/sda1 /A
>    mount --bind /A /B
>    umount /A
>  
>   is pretty valid situation and /B still points to the filesystem.
>  
>  > > +    else
>  > > +        echo $_mnt
>  > > +    fi
>  > >  }
>  
>   I'm not sure if I good understand the original problem, but I'm sure
>   that care about bind mounts is mistake ;-)  If the problem is that
>   dump is not in the filesystem root then you can try to check if the
>   root of the filesystem is mounted somewhere else, but maybe the best
>   would be avoid such fragile setup at all. 
It is complicate for kdump, if we deal with the bind mounted. So in
order to simplify the process, how about add the bind mounted path to
the dump target, if the target is bind mounted?

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.


Here is the scratch path to fix this issue.

diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
index 6a7da8c..5b45714 100755
--- a/dracut-module-setup.sh
+++ b/dracut-module-setup.sh
@@ -345,6 +345,16 @@ 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
@@ -359,23 +369,23 @@ 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##"$_mntpoint"}
+        _path=$(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
-
         _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
 
 }
diff --git a/kdump-lib.sh b/kdump-lib.sh
index cb1bab7..02b4253 100755
--- a/kdump-lib.sh
+++ b/kdump-lib.sh
@@ -86,6 +86,31 @@ get_root_fs_device()
     return
 }
 
+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 = $_mntpoint_nofsroot ]]; then
+        return 1
+    else
+        return 0
+    fi
+}
+
+get_bind_mount_directory()
+{
+    local _mntpoint=$(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}')

Thanks
Minfei

>  
>      Karel
>  
>  -- 
>   Karel Zak  <kzak(a)redhat.com&gt;
>   http://karelzak.blogspot.com

[PATCH 1/2 v2] dracut-moduel-setup: Filte the bind mounted directory in the Atomic

[Minfei Huang]

On 02/12/15 at 01:03pm, Karel Zak wrote:
>  On Thu, Feb 12, 2015 at 01:50:32PM +0800, Dave Young wrote:
>  > >  The mountpoint created by bind operation is independent on previous
>  > >  mounts,
>  > > 
>  > >   mount /mnt/sda1 /A
>  > >   mount --bind /A /B
>  > >   umount /A
>  > > 
>  > >  is pretty valid situation and /B still points to the filesystem.
>  > 
>  > Hmm, got it, so they are equal, but for subdirectory mount there will be
>  > dependency?
>  
>   No, you can still umount, it's just kernel feature that mount can
>   points to non-root filesystem directory.
>  
>   # findmnt /dev/sdc1
>   TARGET SOURCE             FSTYPE OPTIONS
>   /mnt/B /dev/sdc1[/subdir] ext4   rw,relatime,seclabel,stripe=32,data=ordered
>   /mnt/A /dev/sdc1          ext4   rw,relatime,seclabel,stripe=32,data=ordered
>  
>   # umount /mnt/A
>  
>   # findmnt /dev/sdc1
>   TARGET SOURCE             FSTYPE OPTIONS
>   /mnt/B /dev/sdc1[/subdir] ext4   rw,relatime,seclabel,stripe=32,data=ordered
>  
>  
>      Karel 
Hi, All!

Thanks Karel for explaination.

Dave, I think we should not mount the root in the 2nd kernel. Since
the root and "/var" are bind mount directory, we don't need to mount the
root firstly. I think we can do whatever we want, if we mount the device
where the root and "/var" are in.

Following is the tree in atomic.
-bash-4.2# findmnt /
TARGET SOURCE                                                    FSTYPE OPTIONS
/     
/dev/mapper/atomicos-root[/ostree/deploy/rhel-atomic-host/deploy/4b513b5012db32d51b411f8e54e357a231f92b94ff6343bc0fb44cb53b9e0941.0]
                                                                 xfs    rw,relat
-bash-4.2# findmnt /var
TARGET SOURCE                                                    FSTYPE OPTIONS
/var   /dev/mapper/atomicos-root[/ostree/deploy/rhel-atomic-host/var]
                                                                 xfs    rw,relat

We can find the fact that the root directory is a bind mount directory which
points to the
/ostree/deploy/rhel-atomic-host/deploy/4b513b5012db32d51b411f8e54e357a231f92b94ff6343bc0fb44cb53b9e0941.0
directory, and "/var" points to the /ostree/deploy/rhel-atomic-host/var
directory.

To summarize the point, we can mount the device (/dev/mapper/atomicos-root) to
dump to the corresponding subdirecotry (/ostree/deploy/rhel-atomic-host/var).

Thanks
Minfei

>  
>  -- 
>   Karel Zak  <kzak(a)redhat.com&gt;
>   http://karelzak.blogspot.com

[PATCH 2/2 v2] kdump-lib-initramfs: Dump the correct directory in the Atomic

[Minfei Huang]

On 02/12/15 at 02:00pm, Dave Young wrote:
>  On 02/11/15 at 04:19pm, Colin Walters wrote:
>  > > Rethink about it, since dracut is use /sysroot as mount point, really atomic
>  > > should
>  > > choose another dir name instead of /sysroot which conflicts with dracut.
>  > 
>  > Without investigating closely, there's no conflict here, it's just
> confusing.
>  > In the initramfs, there exists a /sysroot that points to the physical storage.
>  
>  Dracut is using /sysroot as mounting point for real root since the very beginning
>  Also see below systemd doc (Sectin "Bootup in the Initial RAM Disk):
>  http://www.freedesktop.org/software/systemd/man/bootup.html
>  
>  It says " If the root device can be mounted at /sysroot, the sysroot.mount unit
>  becomes active and initrd-root-fs.target is reached.
>  
>  So there's many assumptions about /sysroot... 
Hi, Dave!

I think /sysroot is ok in the 2nd kernel. It fails to mount the root in
the 2nd kernel, if we just use command "mount /dev/mapper/atomicos-root
/sysroot". Due to the fact that "/" is a bind mounted directory, so we
should mount the subdirectory to the mountpoint "/", if we want to
mount the root directory.

I think the kdump works, if we find the subdirectory correctly.


Thanks
Minfei

>  > 
>  > Thus, there is a:
>  > 
>  > /sysroot/ostree/deploy/rhel-atomic-host/deploy/$checksum.$serial/sysroot
>  > 
>  > When booted, there is also a /sysroot which points to the physical storage.
>  > 
>  > But I don't believe there is a point where there is an actual conflict.
>  > 
>  >

[PATCH 1/2 v2] dracut-moduel-setup: Filte the bind mounted directory in the Atomic

[Vivek Goyal]

On Wed, Feb 11, 2015 at 12:39:48PM +0100, Karel Zak wrote:

[..]
>   I'm not sure if I good understand the original problem, but
> I'm sure
>   that care about bind mounts is mistake ;-)  If the problem is that
>   dump is not in the filesystem root then you can try to check if the
>   root of the filesystem is mounted somewhere else, but maybe the best
>   would be avoid such fragile setup at all. 
Hi Karel,

So problem in a nutshell is figuring out where to dump the core when
second kernel boots. As we are in second kernel, we have lost all the
context of first kernel (including bind mount relations) and that means
we need to sort out all the information in first kernel and store it
so that kdump can parse it in second kernel.

Now what's the information we are looking for. Primarily we are looking
for what disk do we want to dump to and what path with-in disk we should
dump to.

For example, by default kdump dumps to /var/crash/ directory. Now one
could bind mount /var/crash to say /dev/foo[/foo-subdir]. Now the question
is when second kernel boots, where should we put crash dump.

Should it go in /var/crash of root disk or should it do in /foo-subdir of
/dev/foo disk?

In simple case we could say that we always put it in /var/crash of root
disk but one could argue that it should put it on /dev/foo disk in
foo-subdir.

To handle more complicated case, kdump script will have to have find a way
where given a path (/var/crash/ by default), it can traverse through whole
path, figure out what components are mounted/bind mounted where and finally
zoom on to final disk and path with-in disk and then ask dracut to mount
that disk.

Thanks
Vivek

[PATCH 1/2 v2] dracut-moduel-setup: Filte the bind mounted directory in the Atomic

[Vivek Goyal]

On Sun, Feb 15, 2015 at 09:15:43PM +0800, Minfei Huang wrote:

[..]
>  >  I'm not sure if I good understand the original problem, but
> I'm sure
>  >  that care about bind mounts is mistake ;-)  If the problem is that
>  >  dump is not in the filesystem root then you can try to check if the
>  >  root of the filesystem is mounted somewhere else, but maybe the best
>  >  would be avoid such fragile setup at all.
>  
>  It is complicate for kdump, if we deal with the bind mounted. So in
>  order to simplify the process, how about add the bind mounted path to
>  the dump target, if the target is bind mounted?
>  
>  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.
>  
>  
>  Here is the scratch path to fix this issue.
>   
Minfei,

So what you are suggesting is that let us figure out where is the real
disk and path with-in disk which is mounted on "path" as specified in
kdump.conf. 

I think that will work. So basically we will say that we will not ignore
bind mounts instead resolve the "path" to map to real disk and path
with-in disk. We just need to make sure that logic is generic enough that
it can detect and sort out even complicated cases of bind mounts like multiple
bind mounts.

mount /dev/foo /
mount /dev/foo1 /var
mount /dev/foo2 /var/crash

Thanks
Vivek

[PATCH 1/2 v2] dracut-moduel-setup: Filte the bind mounted directory in the Atomic

[Minfei Huang]

On 02/16/15 at 07:44pm, Vivek Goyal wrote:
>  On Sun, Feb 15, 2015 at 09:15:43PM +0800, Minfei Huang wrote:
>  
>  [..]
>  > >  I'm not sure if I good understand the original problem, but I'm sure
>  > >  that care about bind mounts is mistake ;-)  If the problem is that
>  > >  dump is not in the filesystem root then you can try to check if the
>  > >  root of the filesystem is mounted somewhere else, but maybe the best
>  > >  would be avoid such fragile setup at all.
>  > 
>  > It is complicate for kdump, if we deal with the bind mounted. So in
>  > order to simplify the process, how about add the bind mounted path to
>  > the dump target, if the target is bind mounted?
>  > 
>  > 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.
>  > 
>  > 
>  > Here is the scratch path to fix this issue.
>  > 
>  
>  Minfei,
>  
>  So what you are suggesting is that let us figure out where is the real
>  disk and path with-in disk which is mounted on "path" as specified in
>  kdump.conf. 
>  
>  I think that will work. So basically we will say that we will not ignore
>  bind mounts instead resolve the "path" to map to real disk and path
>  with-in disk. We just need to make sure that logic is generic enough that
>  it can detect and sort out even complicated cases of bind mounts like multiple
>  bind mounts.
>  
>  mount /dev/foo /
>  mount /dev/foo1 /var
>  mount /dev/foo2 /var/crash
>  
>  Thanks
>  Vivek 
Hi, Vivek!

Yes, I think it can simplify our working on the bind mounted issue.

Finding the real disk and path with-in disk is a simple way to solve the
bind mounted issue. It is complicated to sort out the mount point in 2nd
kernel, if the 1st kernel uses bind mounted.

Thanks
Minfei

[PATCH 2/2 v2] kdump-lib-initramfs: Dump the correct directory in the Atomic

[Dave Young]

On 02/11/15 at 04:19pm, Colin Walters wrote:
>  > Rethink about it, since dracut is use /sysroot as mount point,
> really atomic
>  > should
>  > choose another dir name instead of /sysroot which conflicts with dracut.
>  
>  Without investigating closely, there's no conflict here, it's just confusing.
>  In the initramfs, there exists a /sysroot that points to the physical storage.
>  
>  Thus, there is a:
>  
>  /sysroot/ostree/deploy/rhel-atomic-host/deploy/$checksum.$serial/sysroot
>  
>  When booted, there is also a /sysroot which points to the physical storage.
>  
>  But I don't believe there is a point where there is an actual conflict. 
Ok, so ostree-prepare-root will move physical root to somewhere under deploy/
then it will move a cooked sysroot dir to /sysroot. So maybe the right way is
to do same in kdump initrd.

Thanks
Dave

[PATCH 2/2 v2] kdump-lib-initramfs: Dump the correct directory in the Atomic

[Dave Young]

On 02/12/15 at 12:57pm, Harald Hoyer wrote:
>  On 12.02.2015 07:00, Dave Young wrote:
>  > On 02/11/15 at 04:19pm, Colin Walters wrote:
>  >>> Rethink about it, since dracut is use /sysroot as mount point, really
> atomic
>  >>> should
>  >>> choose another dir name instead of /sysroot which conflicts with dracut.
>  >>
>  >> Without investigating closely, there's no conflict here, it's just
> confusing.
>  >> In the initramfs, there exists a /sysroot that points to the physical storage.
>  > 
>  > Dracut is using /sysroot as mounting point for real root since the very beginning
>  > Also see below systemd doc (Sectin "Bootup in the Initial RAM Disk):
>  > http://www.freedesktop.org/software/systemd/man/bootup.html
>  > 
>  > It says " If the root device can be mounted at /sysroot, the sysroot.mount
> unit
>  > becomes active and initrd-root-fs.target is reached.
>  > 
>  > So there's many assumptions about /sysroot...
>  Note:  initrd-root-fs.target  also has an additional condition
>  
>  ConditionPathExists=/etc/initrd-release
>  
>  So, that on normal systems, the target is not activated. 
There's below logic for ostree prepare root, not sure if this is the one in RHEL
though
https://github.com/GNOME/ostree/blob/master/src/switchroot/ostree-prepare...

It setup /sysroot and leave it for systemd initrd-switch-root.target to take over

Looks like it is running in initrd?

But from the code it is restruct /sysroot so there seems no conflict.

>  
>  >>
>  >> Thus, there is a:
>  >>
>  >> /sysroot/ostree/deploy/rhel-atomic-host/deploy/$checksum.$serial/sysroot
>  >>
>  >> When booted, there is also a /sysroot which points to the physical storage.
>  >>
>  >> But I don't believe there is a point where there is an actual conflict.
>  >>
>  >>
>  
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