[lustre-devel] [PATCH 36/42] lustre: don't take spinlock to read a 'long'.
James Simmons
jsimmons at infradead.org
Mon Oct 5 17:06:15 PDT 2020
From: Mr NeilBrown <neilb at suse.de>
Reading a 'long' (or unsigned long) is always an atomic operation.
There is never a need to take a spinlock to just read a single 'long'.
There are several procfs/debugfs/sysfs handlers which needlessly take
a spinlock for this purpose.
This patch:
- removes the taking of the spinlock
- changes the printf to scnprintf() as appropriate
- directly returns the value returned by scnprintf rather than
storing it in a variable
- accesses the 'long' as an arg to the scnprintf(), rather than
introducing a variabe to hold it.
WC-bug-id: https://jira.whamcloud.com/browse/LU-6142
Lustre-commit: 023a9e4cde5498 ("LU-6142 lustre: don't take spinlock to read a 'long'.")
Signed-off-by: Mr NeilBrown <neilb at suse.de>
Reviewed-on: https://review.whamcloud.com/39743
Reviewed-by: Andreas Dilger <adilger at whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.super at gmail.com>
Reviewed-by: James Simmons <jsimmons at infradead.org>
Signed-off-by: James Simmons <jsimmons at infradead.org>
---
fs/lustre/llite/lproc_llite.c | 24 ++++++------------------
fs/lustre/mdc/lproc_mdc.c | 7 +------
fs/lustre/osc/lproc_osc.c | 23 ++++++++---------------
3 files changed, 15 insertions(+), 39 deletions(-)
diff --git a/fs/lustre/llite/lproc_llite.c b/fs/lustre/llite/lproc_llite.c
index 54db7eb..9b1c392 100644
--- a/fs/lustre/llite/lproc_llite.c
+++ b/fs/lustre/llite/lproc_llite.c
@@ -326,13 +326,9 @@ static ssize_t max_read_ahead_mb_show(struct kobject *kobj,
{
struct ll_sb_info *sbi = container_of(kobj, struct ll_sb_info,
ll_kset.kobj);
- unsigned long ra_max_mb;
- spin_lock(&sbi->ll_lock);
- ra_max_mb = PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages);
- spin_unlock(&sbi->ll_lock);
-
- return scnprintf(buf, PAGE_SIZE, "%lu\n", ra_max_mb);
+ return scnprintf(buf, PAGE_SIZE, "%lu\n",
+ PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages));
}
static ssize_t max_read_ahead_mb_store(struct kobject *kobj,
@@ -374,13 +370,9 @@ static ssize_t max_read_ahead_per_file_mb_show(struct kobject *kobj,
{
struct ll_sb_info *sbi = container_of(kobj, struct ll_sb_info,
ll_kset.kobj);
- unsigned long ra_max_file_mb;
- spin_lock(&sbi->ll_lock);
- ra_max_file_mb = PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages_per_file);
- spin_unlock(&sbi->ll_lock);
-
- return scnprintf(buf, PAGE_SIZE, "%lu\n", ra_max_file_mb);
+ return scnprintf(buf, PAGE_SIZE, "%lu\n",
+ PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages_per_file));
}
static ssize_t max_read_ahead_per_file_mb_store(struct kobject *kobj,
@@ -419,13 +411,9 @@ static ssize_t max_read_ahead_whole_mb_show(struct kobject *kobj,
{
struct ll_sb_info *sbi = container_of(kobj, struct ll_sb_info,
ll_kset.kobj);
- unsigned long ra_max_whole_mb;
-
- spin_lock(&sbi->ll_lock);
- ra_max_whole_mb = PAGES_TO_MiB(sbi->ll_ra_info.ra_max_read_ahead_whole_pages);
- spin_unlock(&sbi->ll_lock);
- return scnprintf(buf, PAGE_SIZE, "%lu\n", ra_max_whole_mb);
+ return scnprintf(buf, PAGE_SIZE, "%lu\n",
+ PAGES_TO_MiB(sbi->ll_ra_info.ra_max_read_ahead_whole_pages));
}
static ssize_t max_read_ahead_whole_mb_store(struct kobject *kobj,
diff --git a/fs/lustre/mdc/lproc_mdc.c b/fs/lustre/mdc/lproc_mdc.c
index d7506ea..662be42 100644
--- a/fs/lustre/mdc/lproc_mdc.c
+++ b/fs/lustre/mdc/lproc_mdc.c
@@ -44,13 +44,8 @@ static int mdc_max_dirty_mb_seq_show(struct seq_file *m, void *v)
{
struct obd_device *obd = m->private;
struct client_obd *cli = &obd->u.cli;
- unsigned long val;
- spin_lock(&cli->cl_loi_list_lock);
- val = PAGES_TO_MiB(cli->cl_dirty_max_pages);
- spin_unlock(&cli->cl_loi_list_lock);
-
- seq_printf(m, "%lu\n", val);
+ seq_printf(m, "%lu\n", PAGES_TO_MiB(cli->cl_dirty_max_pages));
return 0;
}
diff --git a/fs/lustre/osc/lproc_osc.c b/fs/lustre/osc/lproc_osc.c
index 14cbe54..7ea9530 100644
--- a/fs/lustre/osc/lproc_osc.c
+++ b/fs/lustre/osc/lproc_osc.c
@@ -87,7 +87,7 @@ static ssize_t max_rpcs_in_flight_show(struct kobject *kobj,
obd_kset.kobj);
struct client_obd *cli = &obd->u.cli;
- return sprintf(buf, "%u\n", cli->cl_max_rpcs_in_flight);
+ return scnprintf(buf, PAGE_SIZE, "%u\n", cli->cl_max_rpcs_in_flight);
}
static ssize_t max_rpcs_in_flight_store(struct kobject *kobj,
@@ -139,13 +139,9 @@ static ssize_t max_dirty_mb_show(struct kobject *kobj,
struct obd_device *obd = container_of(kobj, struct obd_device,
obd_kset.kobj);
struct client_obd *cli = &obd->u.cli;
- unsigned long val;
- spin_lock(&cli->cl_loi_list_lock);
- val = PAGES_TO_MiB(cli->cl_dirty_max_pages);
- spin_unlock(&cli->cl_loi_list_lock);
-
- return scnprintf(buf, PAGE_SIZE, "%lu\n", val);
+ return scnprintf(buf, PAGE_SIZE, "%lu\n",
+ PAGES_TO_MiB(cli->cl_dirty_max_pages));
}
static ssize_t max_dirty_mb_store(struct kobject *kobj,
@@ -252,7 +248,8 @@ static ssize_t cur_dirty_bytes_show(struct kobject *kobj,
obd_kset.kobj);
struct client_obd *cli = &obd->u.cli;
- return sprintf(buf, "%lu\n", cli->cl_dirty_pages << PAGE_SHIFT);
+ return scnprintf(buf, PAGE_SIZE, "%lu\n",
+ cli->cl_dirty_pages << PAGE_SHIFT);
}
LUSTRE_RO_ATTR(cur_dirty_bytes);
@@ -264,7 +261,7 @@ static ssize_t cur_grant_bytes_show(struct kobject *kobj,
obd_kset.kobj);
struct client_obd *cli = &obd->u.cli;
- return sprintf(buf, "%lu\n", cli->cl_avail_grant);
+ return scnprintf(buf, PAGE_SIZE, "%lu\n", cli->cl_avail_grant);
}
static ssize_t cur_grant_bytes_store(struct kobject *kobj,
@@ -284,12 +281,8 @@ static ssize_t cur_grant_bytes_store(struct kobject *kobj,
return rc;
/* this is only for shrinking grant */
- spin_lock(&cli->cl_loi_list_lock);
- if (val >= cli->cl_avail_grant) {
- spin_unlock(&cli->cl_loi_list_lock);
+ if (val >= cli->cl_avail_grant)
return -EINVAL;
- }
- spin_unlock(&cli->cl_loi_list_lock);
with_imp_locked(obd, imp, rc)
if (imp->imp_state == LUSTRE_IMP_FULL)
@@ -307,7 +300,7 @@ static ssize_t cur_lost_grant_bytes_show(struct kobject *kobj,
obd_kset.kobj);
struct client_obd *cli = &obd->u.cli;
- return sprintf(buf, "%lu\n", cli->cl_lost_grant);
+ return scnprintf(buf, PAGE_SIZE, "%lu\n", cli->cl_lost_grant);
}
LUSTRE_RO_ATTR(cur_lost_grant_bytes);
--
1.8.3.1
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