[patch 3/4] proc: Show open file ID in /proc/pid/fdinfo/*

[Cyrill Gorcunov <gorcunov@openvz.org>]

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This patch adds "id" field in /proc/pid/fdinfo/<file>
output which represent generic ID for 'struct file'
being used by a task.

Based-on-patch-from: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: Glauber Costa <glommer@parallels.com>
CC: Andi Kleen <andi@firstfloor.org>
CC: Tejun Heo <tj@kernel.org>
CC: Matt Helsley <matthltc@us.ibm.com>
CC: Pekka Enberg <penberg@kernel.org>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Vasiliy Kulikov <segoon@openwall.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Alexey Dobriyan <adobriyan@gmail.com>
---
 fs/proc/base.c             |   35 ++++++++++++++++++++++++++++++-----
 include/linux/gen_obj_id.h |    1 +
 2 files changed, 31 insertions(+), 5 deletions(-)

Index: linux-2.6.git/fs/proc/base.c
===================================================================
--- linux-2.6.git.orig/fs/proc/base.c
+++ linux-2.6.git/fs/proc/base.c
@@ -84,6 +84,7 @@
 #include <linux/fs_struct.h>
 #include <linux/slab.h>
 #include <linux/flex_array.h>
+#include <linux/gen_obj_id.h>
 #ifdef CONFIG_HARDWALL
 #include <asm/hardwall.h>
 #endif
@@ -1888,8 +1889,36 @@ out:
 	return ~0U;
 }
 
+#ifdef CONFIG_GENERIC_OBJECT_ID
+
+#define PROC_FDINFO_MAX 128
+
+static void proc_fd_info_fill(char *info, struct file *file, unsigned int f_flags)
+{
+	snprintf(info, PROC_FDINFO_MAX,
+		"pos:\t%lli\n"
+		"flags:\t0%o\n"
+		"id:\t%lu\n",
+		(long long)file->f_pos,
+		f_flags,
+		gen_obj_id(file, GEN_OBJ_ID_FILE));
+}
+
+#else /* CONFIG_GENERIC_OBJECT_ID */
+
 #define PROC_FDINFO_MAX 64
 
+static void proc_fd_info_fill(char *info, struct file *file, unsigned int f_flags)
+{
+	snprintf(info, PROC_FDINFO_MAX,
+		"pos:\t%lli\n"
+		"flags:\t0%o\n",
+		(long long)file->f_pos,
+		f_flags);
+}
+
+#endif /* CONFIG_GENERIC_OBJECT_ID */
+
 static int proc_fd_info(struct inode *inode, struct path *path, char *info)
 {
 	struct task_struct *task = get_proc_task(inode);
@@ -1922,11 +1951,7 @@ static int proc_fd_info(struct inode *in
 				path_get(&file->f_path);
 			}
 			if (info)
-				snprintf(info, PROC_FDINFO_MAX,
-					 "pos:\t%lli\n"
-					 "flags:\t0%o\n",
-					 (long long) file->f_pos,
-					 f_flags);
+				proc_fd_info_fill(info, file, f_flags);
 			spin_unlock(&files->file_lock);
 			put_files_struct(files);
 			return 0;
Index: linux-2.6.git/include/linux/gen_obj_id.h
===================================================================
--- linux-2.6.git.orig/include/linux/gen_obj_id.h
+++ linux-2.6.git/include/linux/gen_obj_id.h
@@ -4,6 +4,7 @@
 #ifdef __KERNEL__
 
 enum {
+	GEN_OBJ_ID_FILE,
 	GEN_OBJ_ID_NS,
 	GEN_OBJ_ID_TYPES,
 };