do we support using a file as logdev?

[Wengang Wang]

Hi experts,

Do we support using a file as log device?
If no, it's strange that we support running xfs on a file but don't support log
file.
If yes, it fails at mount.

[root at desk test-xfsprogs]# mkfs.xfs
-llogdev=/root/test-xfsprogs/test-xfsprogs-tmp/imagefile,size=32768b
/dev/sda10 -f
meta-data=/dev/sda10             isize=256    agcount=4, agsize=1250558
blks
         =                       sectsz=512   attr=2
data     =                       bsize=4096   blocks=5002231, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =/root/test-xfsprogs/test-xfsprogs-tmp/imagefile bsize=4096
blocks=32768, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=0
realtime =none                   extsz=4096   blocks=0, rtextents=0
[root at desk test-xfsprogs]# mount
-ologdev=/root/test-xfsprogs/test-xfsprogs-tmp/imagefile /dev/sda10 /xfs
mount: the kernel does not recognize /dev/sda10 as a block device
       (maybe `insmod driver'?)

regards,
wengang.