CVE-2023-53622: gfs2: Fix possible data races in gfs2_show_options()

In the Linux kernel, the following vulnerability has been resolved:

gfs2: Fix possible data races in gfs2showoptions()

Some fields such as gtlogdsecs of the struct gfs2tune are accessed without holding the lock gtspin in gfs2showoptions():

val = sdp->sdtune.gtlogdsecs; if (val != 30) seqprintf(s, ",commit=%d", val);

And thus can cause data races when gfs2showoptions() and other functions such as gfs2reconfigure() are concurrently executed:

spinlock(&gt->gtspin); gt->gtlogdsecs = newargs->arcommit;

To fix these possible data races, the lock sdp->sdtune.gtspin is acquired before accessing the fields of gfs2tune and released after these accesses.

Further changes by Andreas:

- Don't hold the spin lock over the seqprintf operations.