From: Ted Ts'o <tytso@mit.edu>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH] ext4: fix races in ext4_sync_parent()
Date: Sat, 30 Jul 2011 12:32:04 -0400 [thread overview]
Message-ID: <20110730163204.GH7361@thunk.org> (raw)
In-Reply-To: <20110728011129.GO22133@ZenIV.linux.org.uk>
On Thu, Jul 28, 2011 at 02:11:29AM +0100, Al Viro wrote:
> Once d_move() has happened, there's nothing to protect the old parent
> anymore... Granted, it's a hell of a narrow race window, but you
> need at least ->d_lock on your dentry...
Right, got it. So the following should be safe according to the
dcache locking protocols, right?
while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
dentry = NULL;
spin_lock(&inode->i_lock);
if (!list_empty(&inode->i_dentry)) {
dentry = list_first_entry(&inode->i_dentry,
struct dentry, d_alias);
dget(dentry);
}
spin_unlock(&inode->i_lock);
if (!dentry)
break;
next = igrab(dentry->d_parent->d_inode);
dput(dentry);
if (!next)
break;
iput(inode);
inode = next;
...
Let me know if I've missed anything....
- Ted
next prev parent reply other threads:[~2011-07-30 16:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-27 1:13 [PATCH] ext4: fix races in ext4_sync_parent() Theodore Ts'o
2011-07-27 1:15 ` Al Viro
2011-07-28 0:34 ` Ted Ts'o
2011-07-28 1:11 ` Al Viro
2011-07-30 16:32 ` Ted Ts'o [this message]
2011-07-30 16:42 ` Al Viro
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