diff --git a/Documentation/sysctl/fs.txt b/Documentation/sysctl/fs.txt
index 819caf8ca05f8b4b16226c0f5d6f76068de09131..58649bd4fcfcc30de978b071143f6560b3d5a1e4 100644
--- a/Documentation/sysctl/fs.txt
+++ b/Documentation/sysctl/fs.txt
@@ -56,26 +56,32 @@ of any kernel data structures.
dentry-state:
-From linux/fs/dentry.c:
+From linux/include/linux/dcache.h:
--------------------------------------------------------------
-struct {
+struct dentry_stat_t dentry_stat {
int nr_dentry;
int nr_unused;
int age_limit; /* age in seconds */
int want_pages; /* pages requested by system */
- int dummy[2];
-} dentry_stat = {0, 0, 45, 0,};
---------------------------------------------------------------
-
-Dentries are dynamically allocated and deallocated, and
-nr_dentry seems to be 0 all the time. Hence it's safe to
-assume that only nr_unused, age_limit and want_pages are
-used. Nr_unused seems to be exactly what its name says.
+ int nr_negative; /* # of unused negative dentries */
+ int dummy; /* Reserved for future use */
+};
+--------------------------------------------------------------
+
+Dentries are dynamically allocated and deallocated.
+
+nr_dentry shows the total number of dentries allocated (active
++ unused). nr_unused shows the number of dentries that are not
+actively used, but are saved in the LRU list for future reuse.
+
Age_limit is the age in seconds after which dcache entries
can be reclaimed when memory is short and want_pages is
nonzero when shrink_dcache_pages() has been called and the
dcache isn't pruned yet.
+nr_negative shows the number of unused dentries that are also
+negative dentries which do not mapped to actual files.
+
==============================================================
dquot-max & dquot-nr:
diff --git a/fs/dcache.c b/fs/dcache.c
index 44e5652b266483863b6d77894060456c17b08ea2..aac41adf474336ba11488cc025e1e8d46afd0e32 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -119,6 +119,7 @@ struct dentry_stat_t dentry_stat = {
static DEFINE_PER_CPU(long, nr_dentry);
static DEFINE_PER_CPU(long, nr_dentry_unused);
+static DEFINE_PER_CPU(long, nr_dentry_negative);
#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
@@ -152,11 +153,22 @@ static long get_nr_dentry_unused(void)
return sum < 0 ? 0 : sum;
}
+static long get_nr_dentry_negative(void)
+{
+ int i;
+ long sum = 0;
+
+ for_each_possible_cpu(i)
+ sum += per_cpu(nr_dentry_negative, i);
+ 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_negative();
return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
}
#endif
@@ -317,6 +329,8 @@ static inline void __d_clear_type_and_inode(struct dentry *dentry)
flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
WRITE_ONCE(dentry->d_flags, flags);
dentry->d_inode = NULL;
+ if (dentry->d_flags & DCACHE_LRU_LIST)
+ this_cpu_inc(nr_dentry_negative);
}
static void dentry_free(struct dentry *dentry)
@@ -371,6 +385,11 @@ static void dentry_unlink_inode(struct dentry * dentry)
* The per-cpu "nr_dentry_unused" counters are updated with
* the DCACHE_LRU_LIST bit.
*
+ * The per-cpu "nr_dentry_negative" counters are only updated
+ * when deleted from or added to the per-superblock LRU list, not
+ * from/to the shrink list. That is to avoid an unneeded dec/inc
+ * pair when moving from LRU to shrink list in select_collect().
+ *
* These helper functions make sure we always follow the
* rules. d_lock must be held by the caller.
*/
@@ -380,6 +399,8 @@ static void d_lru_add(struct dentry *dentry)
D_FLAG_VERIFY(dentry, 0);
dentry->d_flags |= DCACHE_LRU_LIST;
this_cpu_inc(nr_dentry_unused);
+ if (d_is_negative(dentry))
+ this_cpu_inc(nr_dentry_negative);
WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
}
@@ -388,6 +409,8 @@ static void d_lru_del(struct dentry *dentry)
D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
dentry->d_flags &= ~DCACHE_LRU_LIST;
this_cpu_dec(nr_dentry_unused);
+ if (d_is_negative(dentry))
+ this_cpu_dec(nr_dentry_negative);
WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
}
@@ -418,6 +441,8 @@ static void d_lru_isolate(struct list_lru_one *lru, struct dentry *dentry)
D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
dentry->d_flags &= ~DCACHE_LRU_LIST;
this_cpu_dec(nr_dentry_unused);
+ if (d_is_negative(dentry))
+ this_cpu_dec(nr_dentry_negative);
list_lru_isolate(lru, &dentry->d_lru);
}
@@ -426,6 +451,8 @@ static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry,
{
D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
dentry->d_flags |= DCACHE_SHRINK_LIST;
+ if (d_is_negative(dentry))
+ this_cpu_dec(nr_dentry_negative);
list_lru_isolate_move(lru, &dentry->d_lru, list);
}
@@ -1816,6 +1843,11 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
WARN_ON(d_in_lookup(dentry));
spin_lock(&dentry->d_lock);
+ /*
+ * Decrement negative dentry count if it was in the LRU list.
+ */
+ if (dentry->d_flags & DCACHE_LRU_LIST)
+ this_cpu_dec(nr_dentry_negative);
hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
raw_write_seqcount_begin(&dentry->d_seq);
__d_set_inode_and_type(dentry, inode, add_flags);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index ef4b70f64f333ac6c29bd93031a3a80b71c7b439..60996e64c579851accbcf0e70d2aa10f60181179 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -62,9 +62,10 @@ extern const struct qstr slash_name;
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 age_limit; /* age in seconds */
+ long want_pages; /* pages requested by system */
+ long nr_negative; /* # of unused negative dentries */
+ long dummy; /* Reserved for future use */
};
extern struct dentry_stat_t dentry_stat;