[PATCH 6.1.y 08/18] NFSD: Fix frame size warning in svc_export_parse()

cel
2024-08-10T20:01:01Z

From: Chuck Lever <chuck.lever@oracle.com>

[ Upstream commit 6939ace1f22681fface7841cdbf34d3204cc94b5 ]

fs/nfsd/export.c: In function 'svc_export_parse':
fs/nfsd/export.c:737:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]
737 | }

On my systems, svc_export_parse() has a stack frame of over 800
bytes, not 1040, but nonetheless, it could do with some reduction.

When a struct svc_export is on the stack, it's a temporary structure
used as an argument, and not visible as an actual exported FS. No
need to reserve space for export_stats in such cases.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310012359.YEw5IrK6-lkp@intel.com/
Cc: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Stable-dep-of: 4b14885411f7 ("nfsd: make all of the nfsd stats per-network namespace")
[ cel: adjusted to apply to v6.1.y ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
fs/nfsd/export.c | 32 +++++++++++++++++++++++---------
fs/nfsd/export.h | 4 ++--
fs/nfsd/stats.h | 12 ++++++------
3 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index 668c7527b17e..16fadade86cc 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -339,12 +339,16 @@ static int export_stats_init(struct export_stats *stats)

static void export_stats_reset(struct export_stats *stats)
{
- nfsd_percpu_counters_reset(stats->counter, EXP_STATS_COUNTERS_NUM);
+ if (stats)
+ nfsd_percpu_counters_reset(stats->counter,
+ EXP_STATS_COUNTERS_NUM);
}

static void export_stats_destroy(struct export_stats *stats)
{
- nfsd_percpu_counters_destroy(stats->counter, EXP_STATS_COUNTERS_NUM);
+ if (stats)
+ nfsd_percpu_counters_destroy(stats->counter,
+ EXP_STATS_COUNTERS_NUM);
}

static void svc_export_put(struct kref *ref)
@@ -353,7 +357,8 @@ static void svc_export_put(struct kref *ref)
path_put(&exp->ex_path);
auth_domain_put(exp->ex_client);
nfsd4_fslocs_free(&exp->ex_fslocs);
- export_stats_destroy(&exp->ex_stats);
+ export_stats_destroy(exp->ex_stats);
+ kfree(exp->ex_stats);
kfree(exp->ex_uuid);
kfree_rcu(exp, ex_rcu);
}
@@ -744,13 +749,15 @@ static int svc_export_show(struct seq_file *m,
seq_putc(m, '\t');
seq_escape(m, exp->ex_client->name, " \t\n\\");
if (export_stats) {
- seq_printf(m, "\t%lld\n", exp->ex_stats.start_time);
+ struct percpu_counter *counter = exp->ex_stats->counter;
+
+ seq_printf(m, "\t%lld\n", exp->ex_stats->start_time);
seq_printf(m, "\tfh_stale: %lld\n",
- percpu_counter_sum_positive(&exp->ex_stats.counter[EXP_STATS_FH_STALE]));
+ percpu_counter_sum_positive(&counter[EXP_STATS_FH_STALE]));
seq_printf(m, "\tio_read: %lld\n",
- percpu_counter_sum_positive(&exp->ex_stats.counter[EXP_STATS_IO_READ]));
+ percpu_counter_sum_positive(&counter[EXP_STATS_IO_READ]));
seq_printf(m, "\tio_write: %lld\n",
- percpu_counter_sum_positive(&exp->ex_stats.counter[EXP_STATS_IO_WRITE]));
+ percpu_counter_sum_positive(&counter[EXP_STATS_IO_WRITE]));
seq_putc(m, '\n');
return 0;
}
@@ -796,7 +803,7 @@ static void svc_export_init(struct cache_head *cnew, struct cache_head *citem)
new->ex_layout_types = 0;
new->ex_uuid = NULL;
new->cd = item->cd;
- export_stats_reset(&new->ex_stats);
+ export_stats_reset(new->ex_stats);
}

static void export_update(struct cache_head *cnew, struct cache_head *citem)
@@ -832,7 +839,14 @@ static struct cache_head *svc_export_alloc(void)
if (!i)
return NULL;

- if (export_stats_init(&i->ex_stats)) {
+ i->ex_stats = kmalloc(sizeof(*(i->ex_stats)), GFP_KERNEL);
+ if (!i->ex_stats) {
+ kfree(i);
+ return NULL;
+ }
+
+ if (export_stats_init(i->ex_stats)) {
+ kfree(i->ex_stats);
kfree(i);
return NULL;
}
diff --git a/fs/nfsd/export.h b/fs/nfsd/export.h
index d03f7f6a8642..f73e23bb24a1 100644
--- a/fs/nfsd/export.h
+++ b/fs/nfsd/export.h
@@ -64,10 +64,10 @@ struct svc_export {
struct cache_head h;
struct auth_domain * ex_client;
int ex_flags;
+ int ex_fsid;
struct path ex_path;
kuid_t ex_anon_uid;
kgid_t ex_anon_gid;
- int ex_fsid;
unsigned char * ex_uuid; /* 16 byte fsid */
struct nfsd4_fs_locations ex_fslocs;
uint32_t ex_nflavors;
@@ -76,7 +76,7 @@ struct svc_export {
struct nfsd4_deviceid_map *ex_devid_map;
struct cache_detail *cd;
struct rcu_head ex_rcu;
- struct export_stats ex_stats;
+ struct export_stats *ex_stats;
};

/* an "export key" (expkey) maps a filehandlefragement to an
diff --git a/fs/nfsd/stats.h b/fs/nfsd/stats.h
index c3abe1830da5..ac58c4b2ab70 100644
--- a/fs/nfsd/stats.h
+++ b/fs/nfsd/stats.h
@@ -60,22 +60,22 @@ static inline void nfsd_stats_rc_nocache_inc(void)
static inline void nfsd_stats_fh_stale_inc(struct svc_export *exp)
{
percpu_counter_inc(&nfsdstats.counter[NFSD_STATS_FH_STALE]);
- if (exp)
- percpu_counter_inc(&exp->ex_stats.counter[EXP_STATS_FH_STALE]);
+ if (exp && exp->ex_stats)
+ percpu_counter_inc(&exp->ex_stats->counter[EXP_STATS_FH_STALE]);
}

static inline void nfsd_stats_io_read_add(struct svc_export *exp, s64 amount)
{
percpu_counter_add(&nfsdstats.counter[NFSD_STATS_IO_READ], amount);
- if (exp)
- percpu_counter_add(&exp->ex_stats.counter[EXP_STATS_IO_READ], amount);
+ if (exp && exp->ex_stats)
+ percpu_counter_add(&exp->ex_stats->counter[EXP_STATS_IO_READ], amount);
}

static inline void nfsd_stats_io_write_add(struct svc_export *exp, s64 amount)
{
percpu_counter_add(&nfsdstats.counter[NFSD_STATS_IO_WRITE], amount);
- if (exp)
- percpu_counter_add(&exp->ex_stats.counter[EXP_STATS_IO_WRITE], amount);
+ if (exp && exp->ex_stats)
+ percpu_counter_add(&exp->ex_stats->counter[EXP_STATS_IO_WRITE], amount);
}

static inline void nfsd_stats_payload_misses_inc(struct nfsd_net *nn)
--
2.45.1