xfs_check: sb_fdblocks x, counted x+1

["L. A. Walsh" <xfs@xxxxxxxxx>]

I had (have) some strangeness in a root filesystem.

After going into single-user and going read-only on the
root filesystem, xfs_check tells me that I have a 1 block
discrepancy in my fdblocks.  xfs_repair runs but doesn't seem
to do anything: it ran, but it's not clear it changed anything.
Rerunning xfs_check brings up the same message.   I tried
running xfs_repair with & w/o the "-d" option.  I also tried
xfs_repair -n (&-f dev) to check the exit status. The
return status was fine -- supposedly indicating no corruption,
but no change in xfs_check.

Anyone know why I would get a persistent message out of
xfs_check?

Thanks,
Linda