linux-kernel - Re: observations on configfs

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Message-ID: <20060831021607.GN7715@ca-server1.us.oracle.com>
Date:	Wed, 30 Aug 2006 19:16:07 -0700
From:	Joel Becker <Joel.Becker@...cle.com>
To:	Johannes Berg <johannes@...solutions.net>,
	"Luis R. Rodriguez" <mcgrof@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: observations on configfs

On Tue, Aug 29, 2006 at 09:31:36AM -0700, Joel Becker wrote:
> On Tue, Aug 29, 2006 at 06:14:30PM +0200, Johannes Berg wrote:
> >  (1) it is possible to have
> > 
> >      | $ ls /config
> >      | 02-example  02-example
> > 
> >      Seems like that should be prohibited when registering the new
> > configfs subsystem.
> 
> 	Hmm, yeah, this is a bug.  I've added
> http://oss.oracle.com/bugzilla/show_bug.cgi?id=755.  Thanks for
> reporting this!

	Here's a fix, if you can try it:


diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index df02545..816e8ef 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -86,6 +86,32 @@ static struct configfs_dirent *configfs_
 	return sd;
 }
 
+/*
+ *
+ * Return -EEXIST if there is already a configfs element with the same
+ * name for the same parent.
+ *
+ * called with parent inode's i_mutex held
+ */
+int configfs_dirent_exists(struct configfs_dirent *parent_sd,
+			   const unsigned char *new)
+{
+	struct configfs_dirent * sd;
+
+	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+		if (sd->s_element) {
+			const unsigned char *existing = configfs_get_name(sd);
+			if (strcmp(existing, new))
+				continue;
+			else
+				return -EEXIST;
+		}
+	}
+
+	return 0;
+}
+
+
 int configfs_make_dirent(struct configfs_dirent * parent_sd,
 			 struct dentry * dentry, void * element,
 			 umode_t mode, int type)
@@ -136,8 +162,10 @@ static int create_dir(struct config_item
 	int error;
 	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 
-	error = configfs_make_dirent(p->d_fsdata, d, k, mode,
-				     CONFIGFS_DIR);
+	error = configfs_dirent_exists(p->d_fsdata, d->d_name.name);
+	if (!error)
+		error = configfs_make_dirent(p->d_fsdata, d, k, mode,
+					     CONFIGFS_DIR);
 	if (!error) {
 		error = configfs_create(d, mode, init_dir);
 		if (!error) {
-- 

"Not everything that can be counted counts, and not everything
 that counts can be counted."
        - Albert Einstein 

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@...cle.com
Phone: (650) 506-8127
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