xfs: report ag header corruption errors to the health tracking system

Whenever we encounter a corrupt AG header, we should report that to the
health monitoring system for later reporting.  Buffer readers that don't
respond to corruption events with a _mark_sick call can be detected with
the following script:

#!/bin/bash

# Detect missing calls to xfs_*_mark_sick

filter=cat
tty -s && filter=less

git grep -A10  -E '( = xfs_trans_read_buf| = xfs_buf_read\()' fs/xfs/*.[ch] fs/xfs/libxfs/*.[ch] | awk '
BEGIN {
	ignore = 0;
	lineno = 0;
	delete lines;
}
{
	if ($0 == "--") {
		if (!ignore) {
			for (i = 0; i < lineno; i++) {
				print(lines[i]);
			}
			printf("--\n");
		}
		delete lines;
		lineno = 0;
		ignore = 0;
	} else if ($0 ~ /mark_sick/) {
		ignore = 1;
	} else {
		lines[lineno++] = $0;
	}
}
' | $filter

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>