seq_file: add seq_list_*_percpu helpers

When we convert the file_lock_list to a set of percpu lists, we'll need
a way to iterate over them in order to output /proc/locks info. Add
some seq_list_*_percpu helpers to handle that.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 774c1eb7f1c926c73a7018ae47d9cfb03f75da76..3135c2525c76635606ae9722f6badb5a11e44543 100644 (file)
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -921,3 +921,57 @@ struct hlist_node *seq_hlist_next_rcu(void *v,
                return rcu_dereference(node->next);
 }
 EXPORT_SYMBOL(seq_hlist_next_rcu);
+
+/**
+ * seq_hlist_start_precpu - start an iteration of a percpu hlist array
+ * @head: pointer to percpu array of struct hlist_heads
+ * @cpu:  pointer to cpu "cursor"
+ * @pos:  start position of sequence
+ *
+ * Called at seq_file->op->start().
+ */
+struct hlist_node *
+seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
+{
+       struct hlist_node *node;
+
+       for_each_possible_cpu(*cpu) {
+               hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
+                       if (pos-- == 0)
+                               return node;
+               }
+       }
+       return NULL;
+}
+EXPORT_SYMBOL(seq_hlist_start_percpu);
+
+/**
+ * seq_hlist_next_percpu - move to the next position of the percpu hlist array
+ * @v:    pointer to current hlist_node
+ * @head: pointer to percpu array of struct hlist_heads
+ * @cpu:  pointer to cpu "cursor"
+ * @pos:  start position of sequence
+ *
+ * Called at seq_file->op->next().
+ */
+struct hlist_node *
+seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
+                       int *cpu, loff_t *pos)
+{
+       struct hlist_node *node = v;
+
+       ++*pos;
+
+       if (node->next)
+               return node->next;
+
+       for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
+            *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
+               struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
+
+               if (!hlist_empty(bucket))
+                       return bucket->first;
+       }
+       return NULL;
+}
+EXPORT_SYMBOL(seq_hlist_next_percpu);

diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 2da29ac178fc25ccf01fca81552bf9f515e3c945..4e32edc8f506b89f13b0260200498b5cf87b490a 100644 (file)
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -173,4 +173,10 @@ extern struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
 extern struct hlist_node *seq_hlist_next_rcu(void *v,
                                                   struct hlist_head *head,
                                                   loff_t *ppos);
+
+/* Helpers for iterating over per-cpu hlist_head-s in seq_files */
+extern struct hlist_node *seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos);
+
+extern struct hlist_node *seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head, int *cpu, loff_t *pos);
+
 #endif