On Thu, 2002-05-16 at 12:31, Stephenson, Dale wrote:
> The xfs_freeze command uses xfs_fs_freeze() to flush out and freeze new
> writes to a file system, and xfs_fs_thaw() to let writes through again. In
> between an xfs_freeze -f and xfs_freeze -u, the file system should be
> effectively frozen.
>
> The last thing xfs_fs_freeze() does before returning is call
> xfs_unmountfs_writesb(). The first thing xfs_fs_thaw() does call it again.
> Since all new writes between the two calls should be waiting for the
> filesystem to be thawed, why does xfs_unmountfs_writesb() need to be called
> again? What does xfs_unmountfs_writesb() accomplish in these two functions?
>
> Dale Stephenson
> steph@xxxxxxxxxxxxxx
The function ensures the on disk superblock is uptodate, since we just
made the log clean. As for why both functions do it, good question,
probably just overzealous coding - rather like typing sync sync sync
before reboot.
Steve
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