[patch 6/7] fs, epoll: Add procfs fdinfo helper v2

From: Cyrill Gorcunov
Date: Wed Sep 12 2012 - 17:35:19 EST


This allow us to print out eventpoll target file descriptor,
events and data, the /proc/pid/fdinfo/fd consists of

| pos: 0
| flags: 02
| tfd: 5 events: 1d data: ffffffffffffffff

This feature is CONFIG_CHECKPOINT_RESTORE only.

[avagin@: fix for unitialized ret variable]

Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
CC: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
CC: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
CC: Alexey Dobriyan <adobriyan@xxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: James Bottomley <jbottomley@xxxxxxxxxxxxx>
CC: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
CC: Alexey Dobriyan <adobriyan@xxxxxxxxx>
CC: Matthew Helsley <matt.helsley@xxxxxxxxx>
CC: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
CC: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
CC: Andrey Vagin <avagin@xxxxxxxxxx>
---
fs/eventpoll.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

Index: linux-2.6.git/fs/eventpoll.c
===================================================================
--- linux-2.6.git.orig/fs/eventpoll.c
+++ linux-2.6.git/fs/eventpoll.c
@@ -38,6 +38,8 @@
#include <asm/io.h>
#include <asm/mman.h>
#include <linux/atomic.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>

/*
* LOCKING:
@@ -783,8 +785,34 @@ static unsigned int ep_eventpoll_poll(st
return pollflags != -1 ? pollflags : 0;
}

+#ifdef CONFIG_PROC_FS
+static int ep_show_fdinfo(struct seq_file *m, struct file *f)
+{
+ struct eventpoll *ep = f->private_data;
+ struct rb_node *rbp;
+ int ret = 0;
+
+ 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;
+ }
+ mutex_unlock(&ep->mtx);
+
+ return ret;
+}
+#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,
+#endif
.release = ep_eventpoll_release,
.poll = ep_eventpoll_poll,
.llseek = noop_llseek,

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