On Mon, Feb 21, 2011 at 11:47:09AM +0100, Jiri Slaby wrote:
> > I think you're right about the superfluous test, but I need more
> > investigation to see what's going on. Thanks for the report.
> > What was causing attach_group() to fail? Do you know?
>
> Dunno, I just modprobe'd the configfs example from Doc dir
> (configfs_example_macros).
I'm going to revisit the failed example (which shouldn't fail, I
would think). Can you try the following patch to safely handle the
failure rather than crashing the kernel?
Joel
>From 68bbb327c48fdcdc48b71435d19b9e899745adf0 Mon Sep 17 00:00:00 2001
From: Joel Becker <jlbec@xxxxxxxxxxxx>
Date: Tue, 22 Feb 2011 01:09:49 -0800
Subject: [PATCH] configfs: Don't try to d_delete() negative dentries.
When configfs is faking mkdir() on its subsystem or default group
objects, it starts by adding a negative dentry. It then tries to
instantiate the group. If that should fail, it must clean up after
itself.
I was using d_delete() here, but configfs_attach_group() promises to
return an empty dentry on error. d_delete() explodes with the entry
dentry. Let's try d_drop() instead. The unhashing is what we want for
our dentry.
Signed-off-by: Joel Becker <jlbec@xxxxxxxxxxxx>
---
fs/configfs/dir.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 90ff3cb..2af26b8 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -689,7 +689,8 @@ static int create_default_group(struct config_group *parent_group,
sd = child->d_fsdata;
sd->s_type |= CONFIGFS_USET_DEFAULT;
} else {
- d_delete(child);
+ BUG_ON(child->d_inode);
+ d_drop(child);
dput(child);
}
}
@@ -1683,7 +1684,8 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
err = configfs_attach_group(sd->s_element, &group->cg_item,
dentry);
if (err) {
- d_delete(dentry);
+ BUG_ON(dentry->d_inode);
+ d_drop(dentry);
dput(dentry);
} else {
spin_lock(&configfs_dirent_lock);
--
1.7.3.1
--
"But then she looks me in the eye
And says, 'We're going to last forever,'
And man you know I can't begin to doubt it.
Cause it just feels so good and so free and so right,
I know we ain't never going to change our minds about it, Hey!
Here comes my girl."
http://www.jlbec.org/
jlbec@xxxxxxxxxxxx
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