[PATCH v2] Fix the sync issue for dump_fs

[Tao Liu]

Previously the sync for dump_fs is problematic, it always
return success according to man 2 sync. So it cannot detect
the error of the dump target is full and not all of vmcore
data been written back the disk, which will leave the vmcore
imcomplete and report misleading log as "saving vmcore
complete".

In this patch, we will use "sync -f vmcore" instead, which
will return error if syncfs on the dump target fails. In
this way, vmcore sync related failures, such as autoextend
of lvm2 thinpool fails, can be detected and handled properly.

Signed-off-by: Tao Liu

v1 -> v2:
make "sync -f" against vmcore-incomplete.

---
 dracut-kdump.sh | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/dracut-kdump.sh b/dracut-kdump.sh
index f4456a1..4852c01 100755
--- a/dracut-kdump.sh
+++ b/dracut-kdump.sh
@@ -174,9 +174,15 @@ dump_fs()
    $CORE_COLLECTOR /proc/vmcore "$_dump_fs_path/vmcore-incomplete"
    _dump_exitcode=$?
    if [ $_dump_exitcode -eq 0 ]; then
-		mv "$_dump_fs_path/vmcore-incomplete" "$_dump_fs_path/vmcore"
-		sync
-		dinfo "saving vmcore complete"
+		sync -f "$_dump_fs_path/vmcore-incomplete"
+		_sync_exitcode=$?
+		if [ $_sync_exitcode -eq 0 ]; then
+			mv "$_dump_fs_path/vmcore-incomplete" "$_dump_fs_path/vmcore"
+			dinfo "saving vmcore complete"
+		else
+			derror "sync vmcore failed, exitcode:$_sync_exitcode"
+			return 1
+		fi
    else
    	derror "saving vmcore failed, exitcode:$_dump_exitcode"
    	return 1

[Vivek Goyal]

On Mon, Jun 06, 2022 at 10:33:17PM +0800, Tao Liu wrote:
> Previously the sync for dump_fs is problematic, it always
> return success according to man 2 sync. So it cannot detect
> the error of the dump target is full and not all of vmcore
> data been written back the disk, which will leave the vmcore
> imcomplete and report misleading log as "saving vmcore
> complete".
>
> In this patch, we will use "sync -f vmcore" instead, which
> will return error if syncfs on the dump target fails. In
> this way, vmcore sync related failures, such as autoextend
> of lvm2 thinpool fails, can be detected and handled properly.
>
> Signed-off-by: Tao Liu

Hi Tao,

This looks good to me. I have not tested it though. So somebody will
need to test to make sure things are working as expected.

Vivek
> v1 -> v2:
> make "sync -f" against vmcore-incomplete.
>
> dracut-kdump.sh | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/dracut-kdump.sh b/dracut-kdump.sh
> index f4456a1..4852c01 100755
> --- a/dracut-kdump.sh
> +++ b/dracut-kdump.sh
> @@ -174,9 +174,15 @@ dump_fs()
>    $CORE_COLLECTOR /proc/vmcore "$_dump_fs_path/vmcore-incomplete"
>    _dump_exitcode=$?
>    if [ $_dump_exitcode -eq 0 ]; then
> mv "$_dump_fs_path/vmcore-incomplete" "$_dump_fs_path/vmcore"
> sync
> dinfo "saving vmcore complete"
> sync -f "$_dump_fs_path/vmcore-incomplete"
> _sync_exitcode=$?
> if [ $_sync_exitcode -eq 0 ]; then
> 	mv "$_dump_fs_path/vmcore-incomplete" "$_dump_fs_path/vmcore"
> 	dinfo "saving vmcore complete"
> else
> 	derror "sync vmcore failed, exitcode:$_sync_exitcode"
> 	return 1
> fi
> else
> derror "saving vmcore failed, exitcode:$_dump_exitcode"
> return 1
>
> -- 
> 2.33.1

[Tao Liu]

Hi Vivek,

On Mon, Jun 6, 2022 at 10:40 PM Vivek Goyal  wrote:
> On Mon, Jun 06, 2022 at 10:33:17PM +0800, Tao Liu wrote:
> > Previously the sync for dump_fs is problematic, it always
> > return success according to man 2 sync. So it cannot detect
> > the error of the dump target is full and not all of vmcore
> > data been written back the disk, which will leave the vmcore
> > imcomplete and report misleading log as "saving vmcore
> > complete".
> >
> > In this patch, we will use "sync -f vmcore" instead, which
> > will return error if syncfs on the dump target fails. In
> > this way, vmcore sync related failures, such as autoextend
> > of lvm2 thinpool fails, can be detected and handled properly.
> >
> > Signed-off-by: Tao Liu
>
> Hi Tao,
>
> This looks good to me. I have not tested it though. So somebody will
> need to test to make sure things are working as expected.

Thanks for your review and comments!

Thanks,
Tao Liu
> Vivek
> > v1 -> v2:
> > make "sync -f" against vmcore-incomplete.
> >
> > dracut-kdump.sh | 12 +++++++++---
> >  1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/dracut-kdump.sh b/dracut-kdump.sh
> > index f4456a1..4852c01 100755
> > --- a/dracut-kdump.sh
> > +++ b/dracut-kdump.sh
> > @@ -174,9 +174,15 @@ dump_fs()
> >       $CORE_COLLECTOR /proc/vmcore "$_dump_fs_path/vmcore-incomplete"
> >       _dump_exitcode=$?
> >       if [ $_dump_exitcode -eq 0 ]; then
> >         mv "$_dump_fs_path/vmcore-incomplete" "$_dump_fs_path/vmcore"
> >         sync
> >         dinfo "saving vmcore complete"
> >         sync -f "$_dump_fs_path/vmcore-incomplete"
> >         _sync_exitcode=$?
> >         if [ $_sync_exitcode -eq 0 ]; then
> >                 mv "$_dump_fs_path/vmcore-incomplete" "$_dump_fs_path/vmcore"
> >                 dinfo "saving vmcore complete"
> >         else
> >                 derror "sync vmcore failed, exitcode:$_sync_exitcode"
> >                 return 1
> >         fi
> > else
> >         derror "saving vmcore failed, exitcode:$_dump_exitcode"
> >         return 1
> >
> > --
> > 2.33.1