[patch 3/7] epoll: Use sequential fdinfo engine

[Cyrill Gorcunov <gorcunov@openvz.org>]

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Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: James Bottomley <jbottomley@parallels.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matthew Helsley <matt.helsley@gmail.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 fs/eventpoll.c |   46 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 34 insertions(+), 12 deletions(-)

Index: linux-2.6.git/fs/eventpoll.c
===================================================================
--- linux-2.6.git.orig/fs/eventpoll.c
+++ linux-2.6.git/fs/eventpoll.c
@@ -833,32 +833,54 @@ static unsigned int ep_eventpoll_poll(st
 }
 
 #ifdef CONFIG_PROC_FS
-static int ep_show_fdinfo(struct seq_file *m, struct file *f)
+static void *seq_start(struct seq_file *m, loff_t *pos)
 {
-	struct eventpoll *ep = f->private_data;
+	struct eventpoll *ep = ((struct file *)m->private)->private_data;
 	struct rb_node *rbp;
-	int ret = 0;
+	loff_t num = *pos;
 
 	mutex_lock(&ep->mtx);
 	for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
-		struct epitem *epi = rb_entry(rbp, struct epitem, rbn);
-
-		ret = seq_printf(m, "tfd: %8d events: %8x data: %16llx\n",
-				 epi->ffd.fd, epi->event.events,
-				 (long long)epi->event.data);
-		if (ret)
-			break;
+		if (num-- == 0)
+			return rbp;
 	}
+	return NULL;
+}
+
+static void seq_stop(struct seq_file *m, void *v)
+{
+	struct eventpoll *ep = ((struct file *)m->private)->private_data;
 	mutex_unlock(&ep->mtx);
+}
 
-	return ret;
+static void *seq_next(struct seq_file *m, void *p, loff_t *pos)
+{
+	++*pos;
+	return (void *)rb_next(p);
 }
+
+static int seq_show(struct seq_file *m, void *v)
+{
+	struct epitem *epi = rb_entry(v, struct epitem, rbn);
+
+	seq_printf(m, "tfd: %8d events: %8x data: %16llx\n",
+		   epi->ffd.fd, epi->event.events,
+		   (long long)epi->event.data);
+	return 0;
+}
+
+static struct seq_operations ep_fdinfo_op = {
+	.start		= seq_start,
+	.next		= seq_next,
+	.stop		= seq_stop,
+	.show		= seq_show,
+};
 #endif
 
 /* File callbacks that implement the eventpoll file behaviour */
 static const struct file_operations eventpoll_fops = {
 #ifdef CONFIG_PROC_FS
-	.show_fdinfo	= ep_show_fdinfo,
+	.fdinfo_op	= &ep_fdinfo_op,
 #endif
 	.release	= ep_eventpoll_release,
 	.poll		= ep_eventpoll_poll,