> On Jun 26, 2018, at 7:56 PM, Dave Wysochanski <dwysocha@xxxxxxxxxx> wrote:
>
> The existing rpc_print_iostats has a few shortcomings. First, the naming
> is not consistent with other functions in the kernel that display stats.
> Second, it is really displaying stats for an rpc_clnt structure as it
> displays both xprt stats and per-op stats. Third, it does not handle
> rpc_clnt clones, which is important for the one in-kernel tree caller
> of this function, the NFS client's nfs_show_stats function.
>
> Fix all of the above by renaming the rpc_print_iostats to
> rpc_clnt_show_stats and looping through any rpc_clnt clones via
> cl_parent.
>
> Once this interface is fixed, this addresses a problem with NFSv4.
> Before this patch, the /proc/self/mountstats always showed incorrect
> counts for NFSv4 state related opcodes such as SEQUENCE and RENEW.
> These counts were always 0 even though many ops would go over the
> wire. The reason for this is there are multiple rpc_clnt structures
> allocated for any given NFSv4 mount, and inside nfs_show_stats() we callled
> into rpc_print_iostats() which only handled one of them, nfs_server->client.
> Fix these counts by calling sunrpc's new rpc_clnt_show_stats() function,
> which handles cloned rpc_clnt structs and prints the stats together.
>
> Note that one side-effect of the above is that multiple mounts from
> the same NFS server will show identical counts in the above ops due
> to the fact the one rpc_clnt (representing the NFSv4 client state)
> is shared across mounts.
>
> Signed-off-by: Dave Wysochanski <dwysocha@xxxxxxxxxx>
> ---
> fs/nfs/super.c | 2 +-
> include/linux/sunrpc/metrics.h | 6 +++---
> net/sunrpc/stats.c | 17 ++++++++++++-----
> 3 files changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index 5e470e233c83..bdf39fa1bfbc 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -884,7 +884,7 @@ int nfs_show_stats(struct seq_file *m, struct dentry *root)
> #endif
> seq_printf(m, "\n");
>
> - rpc_print_iostats(m, nfss->client);
> + rpc_clnt_show_stats(m, nfss->client);
>
> return 0;
> }
> diff --git a/include/linux/sunrpc/metrics.h b/include/linux/sunrpc/metrics.h
> index 9baed7b355b2..3daa5b42d871 100644
> --- a/include/linux/sunrpc/metrics.h
> +++ b/include/linux/sunrpc/metrics.h
> @@ -30,7 +30,7 @@
> #include <linux/ktime.h>
> #include <linux/spinlock.h>
>
> -#define RPC_IOSTATS_VERS "1.0"
> +#define RPC_IOSTATS_VERS "1.1"
A quick browse does not reveal a format change in /proc/self/mountstats.
Did I miss it? If there's no change, VERS should stay "1.0".
> struct rpc_iostats {
> spinlock_t om_lock;
> @@ -82,7 +82,7 @@ void rpc_count_iostats(const struct rpc_task *,
> struct rpc_iostats *);
> void rpc_count_iostats_metrics(const struct rpc_task *,
> struct rpc_iostats *);
> -void rpc_print_iostats(struct seq_file *, struct rpc_clnt *);
> +void rpc_clnt_show_stats(struct seq_file *, struct rpc_clnt *);
> void rpc_free_iostats(struct rpc_iostats *);
>
> #else /* CONFIG_PROC_FS */
> @@ -95,7 +95,7 @@ static inline void rpc_count_iostats_metrics(const struct rpc_task *task,
> {
> }
>
> -static inline void rpc_print_iostats(struct seq_file *seq, struct rpc_clnt *clnt) {}
> +static inline void rpc_clnt_show_stats(struct seq_file *seq, struct rpc_clnt *clnt) {}
> static inline void rpc_free_iostats(struct rpc_iostats *stats) {}
>
> #endif /* CONFIG_PROC_FS */
> diff --git a/net/sunrpc/stats.c b/net/sunrpc/stats.c
> index 32adddd7fb78..2c9453465c78 100644
> --- a/net/sunrpc/stats.c
> +++ b/net/sunrpc/stats.c
> @@ -235,13 +235,12 @@ static void _print_rpc_iostats(struct seq_file *seq, struct rpc_iostats *stats,
> ktime_to_ms(stats->om_execute));
> }
>
> -void rpc_print_iostats(struct seq_file *seq, struct rpc_clnt *clnt)
> +void rpc_clnt_show_stats(struct seq_file *seq, struct rpc_clnt *clnt)
> {
> - struct rpc_iostats *stats = clnt->cl_metrics;
> struct rpc_xprt *xprt;
> unsigned int op, maxproc = clnt->cl_maxproc;
>
> - if (!stats)
> + if (!clnt->cl_metrics)
> return;
>
> seq_printf(seq, "\tRPC iostats version: %s ", RPC_IOSTATS_VERS);
> @@ -256,10 +255,18 @@ void rpc_print_iostats(struct seq_file *seq, struct rpc_clnt *clnt)
>
> seq_printf(seq, "\tper-op statistics\n");
> for (op = 0; op < maxproc; op++) {
> - _print_rpc_iostats(seq, &stats[op], op, clnt->cl_procinfo);
> + struct rpc_iostats stats = { 0 };
> + struct rpc_clnt *next = clnt;
> + do {
> + _add_rpc_iostats(&stats, &next->cl_metrics[op]);
> + if (next == next->cl_parent)
> + break;
> + next = next->cl_parent;
> + } while (next);
> + _print_rpc_iostats(seq, &stats, op, clnt->cl_procinfo);
> }
> }
> -EXPORT_SYMBOL_GPL(rpc_print_iostats);
> +EXPORT_SYMBOL_GPL(rpc_clnt_show_stats);
>
> /*
> * Register/unregister RPC proc files
> --
> 2.14.3
>
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--
Chuck Lever
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