| title: | Re RFC 02 22 configfs Add struct configfs |
|
On Fri, 2010-09-10 at 12:44 -0700, Joel Becker wrote:
On Fri, Sep 10, 2010 at 12:06:46PM -0700, Nicholas A. Bellinger wrote:
On Fri, 2010-09-10 at 08:28 -0700, Joel Becker wrote:
The trivial solution is to refcount your ACLs. You get both
allow_link() calls, so you should be able to increment a counter there,
and then drop them when the last drop_link() call is made. That will
keep your consumer structures around until all links are exhausted.
So I am a bit confused wrt to this last response.. The - check_link()
patch and its use in the fabric independent code within
target_core_fabric_configfs.c does exactly this for the MappedLUN
symlink case, eg: requires the consumer to do the allow_link() +
drop_link() refcounting, and add the
API check into fs/configfs/symlink.c:configfs_unlink()
You can refcount without check_link().
So what do you recommend here..?
Is there another form of configfs consumer refcounting that you had in
mind beyond using an atomic_t for this with - check_link() here..?
Im saying that you wont crash if you dont free the ACLs on
the first drop_link(). That is, the drop_link() goes through as
configfs wants it to, but you dont crash.
The problem is that the unlink sub_child/group1/src_0/src_link cant
signal to the other struct config_group to also call an internal unlink
sub_child/group2/dst_0/dst_link to drop the child link outside of its
struct config_group.
So beyond a configfs consumer solution, what do you think about checking
for the sub_child/group2/dst_0/dst_link style of symlink
in fs/configfs/symlink.c:configfs_symlink() in order to add some form of
internal refcount when the symlink source is within the same consumer
LKM, but outside of the parent struct config_group..?
This would involve the conversion of fs/configfs/symlink.c:
configfs_unlink() path to check for the existence of this internal
refcount and returning -EPERM when any sub_child/group2/dst_0/dst_link
exist when unlink sub_child/group1/src_0/src_link is attempted.
Youre still fighting allowing the links to go away. You
havent explained why that is necessary. You had a problem with a crash
because you expected one reference to your ACLs and actually have two,
but you can fix that without modifying configfs.
If this is the case then I must be mis-understanding what you mean by
configfs consumer refcounting from allow_link() and drop_link(). Can
you give me a bit more detail where I should be looking..?
Thanks!
--nab
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at rel="nofollow" vger.kernel.org/majordomo-info.html vger.kernel.org/majordomo-info.html
|
