fellow_log: fix logbuffer flush threshold

It does not make sense to have it larger than the logbuffer itself.

Because the logbuffer can be larger than the threshold, we need to flush
also for n >= thr.

Fixes 7e986ecc

src/fellow_log.c

@@ -2201,8 +2201,8 @@ logbuffer_init(struct fellow_fd *ffd, struct fellow_logbuffer *lbuf,
 	// sane upper limit to not eat up all of the membuddy
 	b = buddy_size(ffd->membuddy) / 8;
 	b >>= MIN_FELLOW_BITS;
-	if (b > UINT_MAX)
-		b = UINT_MAX;
+	if (b > lbuf->space)
+		b = lbuf->space;
 	lbuf->thr = (unsigned)b;
 
 	BUDDY_POOL_INIT(lbuf->ffpool, lbuf->membuddy, FEP_MEM_LOG,
@@ -3260,7 +3260,7 @@ logbuffer_addblks(struct fellow_fd *ffd,
 		/* if we need memory, just flush blocks
 		 */
 		if (canflush && lbuf->space > 0) {
-			if (lbuf->n == lbuf->thr)
+			if (lbuf->n >= lbuf->thr)
 				can |= LBUF_CAN_FLUSH;
 			else if (lbuf->n * 2 > lbuf->thr)
 				kick = 1;