[xfs-masters] Re: freeze vs freezer

[Eric Sandeen <sandeen@xxxxxxxxxxx>]

Rafael J. Wysocki wrote:

>>> I talked with Jens about it on a very general level, but it seems doable at
>>> first sight.
>> Why would you hack the blok layer when we already have a perfectly fine
>> facility to archive what you want?  freeze_bdev is there exactly for the
>> purpose to make the filesystem consistant on disk and then freeze all
>> I/O.
> 
> We tried that in the past and it didn't work very well due to some bad
> interactions with the md layer that we wanted to stay functional while we
> were saving the image.

Hm, details or a link?

> Also, do all of the supported filesystems implement this feature?


ext3, ext4, gfs2, jfs, reiserfs, xfs, all provide a write_super_lockfs
op, which is what freeze_bdev uses.  I think that the rest is generic,
for simpler filesystems.

-Eric