On 3/14/19 4:04 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Back when I was designing xfs_scrub_all, I naïvely assumed that the
> emitted output would always list physical storage before the virtual
> devices stacked atop it. However, this is not actually true when one
> omits the "NAME" column,
I think I asked this on IRC but for the record, is this incidental
or guaranteed by lsblk? I don't see this distinction in the manpage.
I worry about depending on undocumented behavior...
Looking back through IRC, I think we shrugged over this, I asked kzak
but didn't get a reply, will try to find him again.
(also FWIW, older lsblk rejects -J, do we care?)
-Eric
> which is crucial to forcing the output (json or
> otherwise) to capture the block device hierarchy. If the assumption is
> violated, the program crashes with a python exception.
>
> To fix this, force the hierarchal json output and restructure the
> discovery routines to walk the json object that we receive, from the top
> (physical devices) downwards to wherever there are live xfs filesystems.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> scrub/xfs_scrub_all.in | 28 +++++++++++++++++-----------
> 1 file changed, 17 insertions(+), 11 deletions(-)
>
>
> diff --git a/scrub/xfs_scrub_all.in b/scrub/xfs_scrub_all.in
> index c4e9899d..5b76b49a 100644
> --- a/scrub/xfs_scrub_all.in
> +++ b/scrub/xfs_scrub_all.in
> @@ -28,9 +28,21 @@ def DEVNULL():
>
> def find_mounts():
> '''Map mountpoints to physical disks.'''
> + def find_xfs_mounts(bdev, fs, lastdisk):
> + '''Attach lastdisk to each fs found under bdev.'''
> + if bdev['fstype'] == 'xfs' and bdev['mountpoint'] is not None:
> + mnt = bdev['mountpoint']
> + if mnt in fs:
> + fs[mnt].add(lastdisk)
> + else:
> + fs[mnt] = set([lastdisk])
> + if 'children' not in bdev:
> + return
> + for child in bdev['children']:
> + find_xfs_mounts(child, fs, lastdisk)
>
> fs = {}
> - cmd=['lsblk', '-o', 'KNAME,TYPE,FSTYPE,MOUNTPOINT', '-J']
> + cmd=['lsblk', '-o', 'NAME,KNAME,TYPE,FSTYPE,MOUNTPOINT', '-J']
> result = subprocess.Popen(cmd, stdout=subprocess.PIPE)
> result.wait()
> if result.returncode != 0:
> @@ -38,18 +50,12 @@ def find_mounts():
> sarray = [x.decode(sys.stdout.encoding) for x in result.stdout.readlines()]
> output = ' '.join(sarray)
> bdevdata = json.loads(output)
> +
> # The lsblk output had better be in disks-then-partitions order
> for bdev in bdevdata['blockdevices']:
> - if bdev['type'] in ('disk', 'loop'):
> - lastdisk = bdev['kname']
> - if bdev['fstype'] == 'xfs':
> - mnt = bdev['mountpoint']
> - if mnt is None:
> - continue
> - if mnt in fs:
> - fs[mnt].add(lastdisk)
> - else:
> - fs[mnt] = set([lastdisk])
> + lastdisk = bdev['kname']
> + find_xfs_mounts(bdev, fs, lastdisk)
> +
> return fs
>
> def kill_systemd(unit, proc):
>
