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