On Sun 10-11-19 12:49:06, Konstantin Khlebnikov wrote:
> Quota statistics counted as 64-bit per-cpu counter. Reading sums per-cpu
> fractions as signed 64-bit int, filters negative values and then reports
> lower half as signed 32-bit int.
>
> Result may looks like:
>
> fs.quota.allocated_dquots = 22327
> fs.quota.cache_hits = -489852115
> fs.quota.drops = -487288718
> fs.quota.free_dquots = 22083
> fs.quota.lookups = -486883485
> fs.quota.reads = 22327
> fs.quota.syncs = 335064
> fs.quota.writes = 3088689
>
> Values bigger than 2^31-1 reported as negative.
>
> All counters except "allocated_dquots" and "free_dquots" are monotonic,
> thus they should be reported as is without filtering negative values.
>
> Kernel doesn't have generic helper for 64-bit sysctl yet,
> let's use at least unsigned long.
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Thanks! I've added the patch to my tree.
Honza
> ---
> fs/quota/dquot.c | 29 +++++++++++++++++------------
> include/linux/quota.h | 2 +-
> 2 files changed, 18 insertions(+), 13 deletions(-)
>
> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
> index 6e826b454082..fa6ec4f96791 100644
> --- a/fs/quota/dquot.c
> +++ b/fs/quota/dquot.c
> @@ -2860,68 +2860,73 @@ EXPORT_SYMBOL(dquot_quotactl_sysfile_ops);
> static int do_proc_dqstats(struct ctl_table *table, int write,
> void __user *buffer, size_t *lenp, loff_t *ppos)
> {
> - unsigned int type = (int *)table->data - dqstats.stat;
> + unsigned int type = (unsigned long *)table->data - dqstats.stat;
> + s64 value = percpu_counter_sum(&dqstats.counter[type]);
> +
> + /* Filter negative values for non-monotonic counters */
> + if (value < 0 && (type == DQST_ALLOC_DQUOTS ||
> + type == DQST_FREE_DQUOTS))
> + value = 0;
>
> /* Update global table */
> - dqstats.stat[type] =
> - percpu_counter_sum_positive(&dqstats.counter[type]);
> - return proc_dointvec(table, write, buffer, lenp, ppos);
> + dqstats.stat[type] = value;
> + return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
> }
>
> static struct ctl_table fs_dqstats_table[] = {
> {
> .procname = "lookups",
> .data = &dqstats.stat[DQST_LOOKUPS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(unsigned long),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "drops",
> .data = &dqstats.stat[DQST_DROPS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(unsigned long),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "reads",
> .data = &dqstats.stat[DQST_READS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(unsigned long),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "writes",
> .data = &dqstats.stat[DQST_WRITES],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(unsigned long),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "cache_hits",
> .data = &dqstats.stat[DQST_CACHE_HITS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(unsigned long),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "allocated_dquots",
> .data = &dqstats.stat[DQST_ALLOC_DQUOTS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(unsigned long),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "free_dquots",
> .data = &dqstats.stat[DQST_FREE_DQUOTS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(unsigned long),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "syncs",
> .data = &dqstats.stat[DQST_SYNCS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(unsigned long),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> diff --git a/include/linux/quota.h b/include/linux/quota.h
> index f32dd270b8e3..27aab84fcbaa 100644
> --- a/include/linux/quota.h
> +++ b/include/linux/quota.h
> @@ -263,7 +263,7 @@ enum {
> };
>
> struct dqstats {
> - int stat[_DQST_DQSTAT_LAST];
> + unsigned long stat[_DQST_DQSTAT_LAST];
> struct percpu_counter counter[_DQST_DQSTAT_LAST];
> };
>
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
