linux-stable.git/fs/dlm/memory.c, branch v6.11

dlm: add rcu_barrier before destroy kmem cache

2024-06-13T17:48:46+00:00

In the case we trigger dlm_free_rsb() that does a call_rcu() and the
responding kfree() of res_lvbptr and a kmem_cache_free() of the rsb
pointer we need to wait until this pending operation is done before
calling kmem_cache_destroy(). We doing that by using rcu_barrier() that
waits until all pending call_rcu() are done. This avoids that
kmem_cache_destroy() complains about active objects around that are not
being freed yet by call_rcu().

There is currently more discussions about to make this behaviour better,
see:

https://lore.kernel.org/netdev/20240609082726.32742-1-Julia.Lawall@inria.fr/

However this is only for call_rcu() if the callback calls
kmem_cache_destroy() only to replace it by kfree_rcu() call which has
currently some issue. This isn't our case because we also free the
res_lvbptr if being set.

For our case, to avoid the above race rcu_barrier() should be used before
calling kmem_cache_destroy() to be sure that there are no active objects
around. This is exactly what net/batman-adv is also doing before calling their
kmem_cache_destroy() in module unloading.

Fixes: 01fdeca1cc2d ("dlm: use rcu to avoid an extra rsb struct lookup")
Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

dlm: use rcu to avoid an extra rsb struct lookup

2024-06-10T20:26:03+00:00

Use rcu to free rsb structs, and hold the rcu read lock
while looking up rsb structs.  This allows us to avoid an
extra hash table lookup for an rsb.  A new rsb flag HASHED
is added which is set while the rsb is in the hash table.
This flag is checked in place of repeating the hash table
lookup.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

dlm: switch to GFP_ATOMIC in dlm allocations

2024-04-09T16:43:49+00:00

Replace GFP_NOFS with GFP_ATOMIC.  Also stop using idr_preload which
uses a non-bh spin_lock.  This is further preparation for softirq
message processing.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

dlm: remove allocation parameter in msg allocation

2024-04-09T14:58:14+00:00

Remove the context parameter for message allocations and
always use GFP_ATOMIC. This prepares for softirq message
processing.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

dlm: remove callback reference counting

2024-04-01T18:31:13+00:00

Get rid of the unnecessary refcounting on callback structs.
Copy interesting callback info into the lkb struct rather
than maintaining pointers to callback structs from the lkb.
This goes back to the way things were done prior to
commit 61bed0baa4db ("fs: dlm: use a non-static queue for callbacks").

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: change dflags to use atomic bits

2023-03-06T21:49:07+00:00

Currently manipulating lkb_dflags assumes to held the rsb lock assigned
to the lkb. This is held by dlm message processing after certain
time to lookup the right rsb from the received lkb message id. For user
space locks flags, which is currently the only use case for lkb_dflags,
flags are also being set during dlm character device handling without
holding the rsb lock. To minimize the risk that bit operations are
getting corrupted we switch to atomic bit operations. This patch will
also introduce helpers to snapshot atomic bit values in an non atomic
way. There might be still issues with the flag handling e.g. running in
case of manipulating bit ops and snapshot them at the same time, but this
patch minimize them and will start to use atomic bit operations.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: store lkb distributed flags into own value

2023-03-06T21:49:07+00:00

This patch stores lkb distributed flags value in an separate value
instead of sharing internal and distributed flags in lkb->lkb_flags value.
This has the advantage to not mask/write back flag values in
receive_flags() functionality. The dlm debug_fs does not provide the
distributed flags anymore, those can be added in future.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: fix return value check in dlm_memory_init()

2023-01-05T21:37:51+00:00

It should check 'cb_cache', after calling kmem_cache_create("dlm_cb").

Fixes: 61bed0baa4db ("fs: dlm: use a non-static queue for callbacks")
Signed-off-by: Yang Yingliang 
Signed-off-by: David Teigland

fs: dlm: allow different allocation context per _create_message

2022-11-08T18:59:41+00:00

This patch allows to give the use control about the allocation context
based on a per message basis. Currently all messages forced to be
created under GFP_NOFS context.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: use a non-static queue for callbacks

2022-11-08T18:59:41+00:00

This patch will introducde a queue implementation for callbacks by using
the Linux lists. The current callback queue handling is implemented by a
static limit of 6 entries, see DLM_CALLBACKS_SIZE. The sequence number
inside the callback structure was used to see if the entries inside the
static entry is valid or not. We don't need any sequence numbers anymore
with a dynamic datastructure with grows and shrinks during runtime to
offer such functionality.

We assume that every callback will be delivered to the DLM user if once
queued. Therefore the callback flag DLM_CB_SKIP was dropped and the
check for skipping bast was moved before worker handling and not skip
while the callback worker executes. This will reduce unnecessary queues
of the callback worker.

All last callback saves are pointers now and don't need to copied over.
There is a reference counter for callback structures which will care
about to free the callback structures at the right time if they are not
referenced anymore.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland