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Subject[PATCH 2/4] fs/dcache: Report negative dentry number in dentry-state
Date
The number of negative dentries currently in the system is now reported
in the /proc/sys/fs/dentry-state file.

Signed-off-by: Waiman Long <longman@redhat.com>
---
fs/dcache.c | 16 +++++++++++++++-
include/linux/dcache.h | 7 ++++---
2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 6a0a844..bb0a519 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -135,6 +135,7 @@ struct dentry_stat_t dentry_stat = {
*/
#define NEG_DENTRY_BATCH (1 << 8)
static long neg_dentry_percpu_limit __read_mostly;
+static long neg_dentry_nfree_init __read_mostly; /* Free pool initial value */
static struct {
raw_spinlock_t nfree_lock;
long nfree; /* Negative dentry free pool */
@@ -176,11 +177,23 @@ static long get_nr_dentry_unused(void)
return sum < 0 ? 0 : sum;
}

+static long get_nr_dentry_neg(void)
+{
+ int i;
+ long sum = 0;
+
+ for_each_possible_cpu(i)
+ sum += per_cpu(nr_dentry_neg, i);
+ sum += neg_dentry_nfree_init - ndblk.nfree;
+ return sum < 0 ? 0 : sum;
+}
+
int proc_nr_dentry(struct ctl_table *table, int write, void __user *buffer,
size_t *lenp, loff_t *ppos)
{
dentry_stat.nr_dentry = get_nr_dentry();
dentry_stat.nr_unused = get_nr_dentry_unused();
+ dentry_stat.nr_negative = get_nr_dentry_neg();
return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
}
#endif
@@ -3704,7 +3717,8 @@ static void __init neg_dentry_init(void)
raw_spin_lock_init(&ndblk.nfree_lock);

/* 20% in global pool & 80% in percpu free */
- ndblk.nfree = totalram_pages * nr_dentry_page * neg_dentry_pc / 500;
+ ndblk.nfree = neg_dentry_nfree_init
+ = totalram_pages * nr_dentry_page * neg_dentry_pc / 500;
cnt = ndblk.nfree * 4 / num_possible_cpus();
if (unlikely(cnt < 2 * NEG_DENTRY_BATCH))
cnt = 2 * NEG_DENTRY_BATCH;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 498233b..184669f 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -63,9 +63,10 @@ struct qstr {
struct dentry_stat_t {
long nr_dentry;
long nr_unused;
- long age_limit; /* age in seconds */
- long want_pages; /* pages requested by system */
- long dummy[2];
+ long nr_negative; /* # of negative dentries */
+ long age_limit; /* age in seconds */
+ long want_pages; /* pages requested by system */
+ long dummy;
};
extern struct dentry_stat_t dentry_stat;

--
1.8.3.1
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