From: Pavel Emelyanov <xemul@parallels.com>
Date: Tue, 1 Nov 2011 00:10:04 +0000 (-0700)
Subject: fs/pipe.c: add ->statfs callback for pipefs
X-Git-Tag: firefly_0821_release~3680^2~4252^2~56
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d70ef97baf048412c395bb5d65791d8fe133a52b;p=firefly-linux-kernel-4.4.55.git

fs/pipe.c: add ->statfs callback for pipefs

Currently a statfs on a pipe's /proc/<pid>/fd/ link returns -ENOSYS.  Wire
pipfs up so that the statfs succeeds.

This is required by checkpoint-restart in the userspace to make it
possible to distinguish pipes from fifos.

When we dump information about task's open files we use the /proc/pid/fd
directoy's symlinks and the fact that opening any of them gives us exactly
the same dentry->inode pair as the original process has.  Now if a task
we're dumping has opened pipe and fifo we need to detect this and act
accordingly.  Knowing that an fd with type S_ISFIFO resides on a pipefs is
the most precise way.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/fs/pipe.c b/fs/pipe.c
index 0e0be1dc0f8e..4065f07366b3 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1254,6 +1254,7 @@ out:
 
 static const struct super_operations pipefs_ops = {
 	.destroy_inode = free_inode_nonrcu,
+	.statfs = simple_statfs,
 };
 
 /*