Masatake YAMATO wrote:
> (The disscussion can be found at
>> I understand reason when it use with device-mapper.
>> I think, fsfreeze command need for filesystem on physical block device
>> without device-mapper.
>> For example, by storage controller based LUN snapshot.
>> # fsfreeze -f /data
>> # ssh root@xxxxxxxxxxx "take snapshot lun0"
>> # fsfreeze -u /data
>> * /data is mounted physical block device(/dev/sdb1)
> As Hajime wrote, taking snapshot in physical storage level is popular
> situation. It seems that xfs_freeze can be used for the purpose but
> the name `xfs_freeze' gives the impression that the command is only
> for xfs.
> My argument can be applicable to gfs2_tool, too. "gfs2_tool freeze"
> also does ``ioctl(fd, FIFREEZE, 0)''.
> One of the solution is to add xxx_freeze for each file system implementation
> which has freeze/unfreeze methods to eash util-xxx, xxx-progs or xxx-utils.
> e.g. Adding ext4_freeze or ext3_freeze command to e2fsprogs package.
> However, I think this is not good idea. Linux provides file system neutral
> interface already. So it is better to have file system neutral
> and the command is included in file system neutral package, util-linux-ng.
I tend to agree, since there is a common interface, there is no reason to
have filesystem-specific tools which all do the same thing.
Note that xfs_freeze existed long before the common interface, and in fact
the common ioctl number was chosen based on the xfs number, so that explains
the existence of the xfs-specific tool, and why it does happen to work
now on non-xfs filesystems....