[LU-17744] small fixes for LU-12103 ldiskfs: don't search large block range if disk full

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.16.0
• Severity: 3
• Assignee: Alexander Zarochentsev
• Reporter: Alexander Zarochentsev

Description

the original patches from LU-12103 has defects:
1: the array for the "useless" loop counters should have 4 elements, one for each cr value

{ 0, 1, 2, 3 }

        /* cX loop didn't find blocks */
        atomic64_t s_bal_cX_failed[3];
        atomic64_t s_bal_cX_skipped[3];
        spinlock_t s_bal_lock;

accessing the last element is almost impossible, but it is theoretically possible.

2. the output to the sysfs mb_alloc_stat file should count useless and skipped loops from 0 to 3:

        seq_printf(seq, "\tuseless_c1_loops: %llu\n",
                   (unsigned long long)atomic64_read(&sbi->s_bal_cX_failed[0]));
        seq_printf(seq, "\tuseless_c2_loops: %llu\n",
                   (unsigned long long)atomic64_read(&sbi->s_bal_cX_failed[1]));
        seq_printf(seq, "\tuseless_c3_loops: %llu\n",
                   (unsigned long long)atomic64_read(&sbi->s_bal_cX_failed[2]));
        seq_printf(seq, "\tskipped_c1_loops: %llu\n",
                   (unsigned long long)atomic64_read(&sbi->s_bal_cX_skipped[0]));
        seq_printf(seq, "\tskipped_c2_loops: %llu\n",
                   (unsigned long long)atomic64_read(&sbi->s_bal_cX_skipped[1]));
        seq_printf(seq, "\tskipped_c3_loops: %llu\n",
                   (unsigned long long)atomic64_read(&sbi->s_bal_cX_skipped[2]));

in the kernel messages, the counters named correctly:

++                      "mballoc: (%lu, %lu, %lu) useless c(0,1,2) loops",
++                              atomic64_read(&sbi->s_bal_cX_failed[0]),
++                              atomic64_read(&sbi->s_bal_cX_failed[1]),
++                              atomic64_read(&sbi->s_bal_cX_failed[2]));
++              ext4_msg(sb, KERN_INFO,
++                      "mballoc: (%lu, %lu, %lu) skipped c(0,1,2) loops",
++                              atomic64_read(&sbi->s_bal_cX_skipped[0]),
++                              atomic64_read(&sbi->s_bal_cX_skipped[1]),
++                              atomic64_read(&sbi->s_bal_cX_skipped[2]));