linux-stable.git/fs/dlm/user.c, branch linux-6.3.y

fs: dlm: fix DLM_IFL_CB_PENDING gets overwritten

2023-05-11T14:16:53+00:00

commit a034c1370ded2ae6cbdc73a78241b3ed98c86d3d upstream.

This patch introduce a new internal flag per lkb value to handle
internal flags which are handled not on wire. The current lkb internal
flags stored as lkb->lkb_flags are split in upper and lower bits, the
lower bits are used to share internal flags over wire for other cluster
wide lkb copies on other nodes.

In commit 61bed0baa4db ("fs: dlm: use a non-static queue for callbacks")
we introduced a new internal flag for pending callbacks for the dlm
callback queue. This flag is protected by the lkb->lkb_cb_lock lock.
This patch overlooked that on dlm receive path and the mentioned upper
and lower bits, that dlm will read the flags, mask it and write it
back. As example receive_flags() in fs/dlm/lock.c. This flag
manipulation is not done atomically and is not protected by
lkb->lkb_cb_lock. This has unknown side effects of the current callback
handling.

In future we should move to set/clear/test bit functionality and avoid
read, mask and writing back flag values. In later patches we will move
the upper parts to the new introduced internal lkb flags which are not
shared between other cluster nodes to the new non shared internal flag
field to avoid similar issues.

Cc: stable@vger.kernel.org
Fixes: 61bed0baa4db ("fs: dlm: use a non-static queue for callbacks")
Reported-by: Bob Peterson 
Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland 
Signed-off-by: Greg Kroah-Hartman

fs: dlm: rename DLM_IFL_NEED_SCHED to DLM_IFL_CB_PENDING

2022-11-21T15:45:49+00:00

This patch renames DLM_IFL_NEED_SCHED to DLM_IFL_CB_PENDING because
CB_PENDING is a proper name to describe this flag. This flag is set when
callback enqueue will return DLM_ENQUEUE_CALLBACK_NEED_SCHED because the
callback worker need to be queued. The flag tells that callbacks are
currently pending to be called and will be unset if the callback work
for the specific lkb is done. The term need schedule is part of this
time but a proper name is to say that there are some callbacks pending
to being called.

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

fs: dlm: ast do WARN_ON_ONCE() on hotpath

2022-11-21T15:45:49+00:00

This patch changes the ast hotpath functionality in very unlikely cases
that we do WARN_ON_ONCE() instead of WARN_ON() to not spamming the
console output if we run into states that it would occur over and over
again.

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

fs: dlm: use list_first_entry marco

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

Instead of using list_entry() this patch moves to using the
list_first_entry() macro.

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

fs: dlm: remove DLM_LSFL_FS from uapi

2022-08-23T19:54:54+00:00

The DLM_LSFL_FS flag is set in lockspaces created directly
for a kernel user, as opposed to those lockspaces created
for user space applications.  The user space libdlm allowed
this flag to be set for lockspaces created from user space,
but then used by a kernel user.  No kernel user has ever
used this method, so remove the ability to do it.

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

fs: dlm: trace user space callbacks

2022-08-23T19:54:04+00:00

This patch adds trace callbacks for user locks. Unfortenately user locks
are handled in a different way than kernel locks in some cases. User
locks never call the dlm_lock()/dlm_unlock() kernel API and use the next
step internal API of dlm. Adding those traces from user API callers
should make it possible for dlm trace system to see lock handling for
user locks as well.

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

fs: dlm: change ls_clear_proc_locks to spinlock

2022-08-23T19:54:02+00:00

This patch changes the ls_clear_proc_locks to a spinlock because there
is no need to handle it as a mutex as there is no sleepable context when
ls_clear_proc_locks is held. This allows us to call those functionality
in non-sleepable contexts.

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

fs: dlm: don't use deprecated timeout features by default

2022-08-01T14:31:38+00:00

This patch will disable use of deprecated timeout features if
CONFIG_DLM_DEPRECATED_API is not set.  The deprecated features
will be removed in upcoming kernel release v6.2.

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

fs: dlm: add deprecation Kconfig and warnings for timeouts

2022-08-01T14:31:32+00:00

This patch adds a CONFIG_DLM_DEPRECATED_API Kconfig option
that must be enabled to use two timeout-related features
that we intend to remove in kernel v6.2.  Warnings are
printed if either is enabled and used.  Neither has ever
been used as far as we know.

. The DLM_LSFL_TIMEWARN lockspace creation flag will be
  removed, along with the associated configfs entry for
  setting the timeout.  Setting the flag and configfs file
  would cause dlm to track how long locks were waiting
  for reply messages.  After a timeout, a kernel message
  would be logged, and a netlink message would be sent
  to userspace.  Recently, midcomms messages have been
  added that produce much better logging about actual
  problems with messages.  No use has ever been found
  for the netlink messages.

. The userspace libdlm API has allowed the DLM_LKF_TIMEOUT
  flag with a timeout value to be set in lock requests.
  The lock request would be cancelled after the timeout.

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