linux-kernel - [PATCH] proc: calculate the correct /proc/<pid> link count

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Message-ID: <20080603131659.GA2970@damson.getinternet.no>
Date:	Tue, 3 Jun 2008 15:16:59 +0200
From:	Vegard Nossum <vegard.nossum@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Pavel Emelyanov <xemul@...nvz.org>, linux-kernel@...r.kernel.org
Subject: [PATCH] proc: calculate the correct /proc/<pid> link count

From: Vegard Nossum <vegard.nossum@...il.com>
Date: Mon, 2 Jun 2008 08:57:45 +0200
Subject: [PATCH] proc: calculate the correct /proc/<pid> link count

commit e9720acd728a46cb40daa52c99a979f7c4ff195c introduced a
/proc/self/net directory without bumping the corresponding link count
for /proc/self.

This patch replaces the static link count initializations with a call
that counts the number of directory entries in the given pid_entry
table whenever it is instantiated, and thus relieves the burden of
manually keeping the two in sync.

Cc: Eric W. Biederman <ebiederm@...ssion.com>
Cc: Pavel Emelyanov <xemul@...nvz.org>
Signed-off-by: Vegard Nossum <vegard.nossum@...il.com>
---
 fs/proc/base.c |   31 +++++++++++++++++++++++--------
 1 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index c447e07..334ce46 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -127,6 +127,23 @@ struct pid_entry {
 		NULL, &proc_single_file_operations,	\
 		{ .proc_show = &proc_##OTYPE } )
 
+/* Count the number of hardlinks for the pid_entry table, excluding the .
+ * and .. links. */
+static unsigned int pid_entry_count_dirs(const struct pid_entry *entries,
+	unsigned int n)
+{
+	unsigned int i;
+	unsigned int count;
+
+	count = 0;
+	for (i = 0; i < n; ++i) {
+		if (S_ISDIR(entries[i].mode))
+			++count;
+	}
+
+	return count;
+}
+
 int maps_protect;
 EXPORT_SYMBOL(maps_protect);
 
@@ -2585,10 +2602,9 @@ static struct dentry *proc_pid_instantiate(struct inode *dir,
 	inode->i_op = &proc_tgid_base_inode_operations;
 	inode->i_fop = &proc_tgid_base_operations;
 	inode->i_flags|=S_IMMUTABLE;
-	inode->i_nlink = 5;
-#ifdef CONFIG_SECURITY
-	inode->i_nlink += 1;
-#endif
+
+	inode->i_nlink = 2 + pid_entry_count_dirs(tgid_base_stuff,
+		ARRAY_SIZE(tgid_base_stuff));
 
 	dentry->d_op = &pid_dentry_operations;
 
@@ -2816,10 +2832,9 @@ static struct dentry *proc_task_instantiate(struct inode *dir,
 	inode->i_op = &proc_tid_base_inode_operations;
 	inode->i_fop = &proc_tid_base_operations;
 	inode->i_flags|=S_IMMUTABLE;
-	inode->i_nlink = 4;
-#ifdef CONFIG_SECURITY
-	inode->i_nlink += 1;
-#endif
+
+	inode->i_nlink = 2 + pid_entry_count_dirs(tid_base_stuff,
+		ARRAY_SIZE(tid_base_stuff));
 
 	dentry->d_op = &pid_dentry_operations;
 
-- 
1.5.4.1

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