@@ -33,6 +33,7 @@
#include <linux/rculist_bl.h>
#include <linux/list_lru.h>
#include <linux/jump_label.h>
+#include <linux/debugfs.h>
#include "internal.h"
#include "mount.h"
@@ -136,6 +137,8 @@ static DEFINE_PER_CPU(long, nr_dentry_negative);
int dcache_dentry_dir_max_sysctl;
EXPORT_SYMBOL_GPL(dcache_dentry_dir_max_sysctl);
static int negative_dentry_dir_max __read_mostly;
+static unsigned long negative_dentry_reclaim_count;
+static atomic_t negative_dentry_kill_count;
#define DENTRY_DIR_MAX_MIN 0x100
static LLIST_HEAD(negative_reclaim_list);
@@ -204,6 +207,7 @@ int proc_dcache_dentry_dir_max(struct ctl_table *ctl, int write,
{
int old = dcache_dentry_dir_max_sysctl;
int ret;
+ static bool debugfs_file_created;
ret = proc_dointvec_minmax(ctl, write, buffer, lenp, ppos);
@@ -219,6 +223,14 @@ int proc_dcache_dentry_dir_max(struct ctl_table *ctl, int write,
return -EINVAL;
}
+ if (!debugfs_file_created) {
+ debugfs_create_ulong("negative_dentry_reclaimed", 0400, NULL,
+ &negative_dentry_reclaim_count);
+ debugfs_create_u32("negative_dentry_killed", 0400, NULL,
+ (u32 *)&negative_dentry_kill_count.counter);
+ debugfs_file_created = true;
+ }
+
negative_dentry_dir_max = dcache_dentry_dir_max_sysctl;
if (!old && dcache_dentry_dir_max_sysctl)
static_branch_enable(&negative_reclaim_enable);
@@ -1542,6 +1554,8 @@ static void negative_reclaim_workfn(struct work_struct *work)
kfree(dentry_node);
cond_resched();
}
+ if (quota < MAX_DENTRY_RECLAIM)
+ negative_dentry_reclaim_count += MAX_DENTRY_RECLAIM - quota;
}
/*
@@ -1609,6 +1623,7 @@ static void negative_reclaim_check(struct dentry *parent, struct dentry *child)
rcu_read_unlock();
__dentry_kill(child);
dput(parent);
+ atomic_inc(&negative_dentry_kill_count);
return;
}
spin_unlock(&child->d_lock);
The negative dentry reclaim process gave no visible indication that it was being activated. In order to allow system administrator to see if it is being activated as expected, two new debugfs variables "negative_dentry_reclaimed" and "negative_dentry_killed" are now added to report the total number of negative dentries that have been reclaimed and killed. These debugfs variables are only added after the negative dentry reclaim mechanism is activated for the first time. In reality, the actual number may be slightly less than the reported number as not all the negative dentries passed to shrink_dentry_list() and __dentry_kill() can be successfully reclaimed. Signed-off-by: Waiman Long <longman@redhat.com> --- fs/dcache.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)