Re: [RFC][PATCH 2/3] vfs: Add a function to lazily unmount all mounts from any dentry.

[Eric W. Biederman]

Miklos Szeredi <miklos@xxxxxxxxxx> writes:

> On Fri, Oct 04, 2013 at 03:43:18PM -0700, Eric W. Biederman wrote:
>> 
>> +void detach_mounts(struct dentry *dentry)
>> +{
>> +	struct mount *mnt, *next;
>> +	struct mountpoint *mp;
>> +
>> +	namespace_lock();
>> +	if (!d_mountpoint(dentry)) {
>> +		namespace_unlock();
>> +		return;
>> +	}
>> +	mp = new_mountpoint(dentry);
>> +	if (IS_ERR(mp)) {
>> +		return;
>> +	}
>> +	br_write_lock(&vfsmount_lock);
>> +	list_for_each_entry_safe(mnt, next, &mp->m_list, mnt_mp_list) {
>
> I don't think list_for_each_entry_safe is actually safe enough here.  Because
> propageted umounts will likely remove other mounts from the same mountpoint as
> well.  Doing it with "while (!list_empty(&mp->m_list))" should be better, and
> AFAICS it will always make progress.

Thanks I will take a look.  But on the surface that logic sounds
correct.

Eric
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/