In one special case, recovery is unable to reliably rebuild
lock state by simply recreating lkb structs as sent from the
lock holders. That case is when the lkb's include conversions
between PR and CW modes.
The recovery code has always recognized this special case,
but the implemention has always been broken, and would set
invalid modes in recovered lkb's. Unpredictable or bogus
errors could then be returned for further locking calls on
these locks.
This bug has gone unnoticed for so long due to some
combination of:
- applications never or infrequently converting between PR/CW
- recovery not occuring during these conversions
- if the recovery bug does occur, the caller may not notice,
depending on what further locking calls are made, e.g. if
the lock is simply unlocked it may go unnoticed
However, a core analysis from a recent gfs2 bug report points
to this broken code.
PR = Protected Read
CW = Concurrent Write
PR and CW are incompatible
PR and PR are compatible
CW and CW are compatible
Example 1
node C, resource R
granted: PR node A
granted: PR node B
granted: NL node C
granted: NL node D
- A sends convert PR->CW to C
- C fails before A gets a reply
- recovery occurs
At this point, A does not know if it still holds
the lock in PR, or if its conversion to CW was granted:
- If A's conversion to CW was granted, then another
node's CW lock may also have been granted.
- If A's conversion to CW was not granted, it still
holds a PR lock, and other nodes may also hold PR locks.
So, the new master of R cannot simply recreate the lock
from A using granted mode PR and requested mode CW.
The new master must look at all the recovered locks to
determine the correct granted modes, and ensure that all
the recovered locks are recreated in compatible states.
The correct lock recovery steps in this example are:
- node D becomes the new master of R
- node B sends D its lkb, granted PR
- node A sends D its lkb, convert PR->CW
- D determines the correct lock state is:
granted: PR node B
convert: PR->CW node A
The lkb sent by each node was recreated without
any change on the new master node.
Example 2
node C, resource R
granted: PR node A
granted: NL node C
granted: NL node D
waiting: CW node B
- A sends convert PR->CW to C
- C grants the conversion to CW for A
- C grants the waiting request for CW to B
- C sends granted message to B, but fails
before it can send the granted message to A
- B receives the granted message from C
At this point:
- A believes it is converting PR->CW
- B believes it is holding a CW lock
The correct lock recovery steps in this example are:
- node D becomes the new master of R
- node A sends D its lkb, convert PR->CW
- node B sends D its lkb, granted CW
- D determins the correct lock state is:
granted: CW node B
granted: CW node A
The lkb sent by B is recreated without change,
but the lkb sent by A is changed because the
granted mode was not compatible.
Fixes to make this work correctly:
recover_convert_waiter: should not make any changes
to a converting lkb that is still waiting for a reply
message. It was previously setting grmode to IV, which
is invalid state, so the lkb would not be handled
correctly by other code.
receive_rcom_lock_args: was checking the wrong lkb field
(wait_type instead of status) to determine if the lkb is
being converted, and in need of inspection for this special
recovery. It was also setting grmode to IV in the lkb,
causing it to be mishandled by other code.
Now, this function just puts the lkb, directly as sent,
onto the convert queue of the resource being recovered,
and corrects it in recover_conversion() later, if needed.
recover_conversion: the job of this function is to detect
and correct lkb states for the special PR/CW conversions.
The new code now checks for recovered lkbs on the granted
queue with grmode PR or CW, and takes the real grmode from
that. Then it looks for lkbs on the convert queue with an
incompatible grmode (i.e. grmode PR when the real grmode is
CW, or v.v.) These converting lkbs need to be fixed.
They are fixed by temporarily setting their grmode to NL,
so that grmodes are not incompatible and won't confuse other
locking code. The converting lkb will then be granted at
the end of recovery, replacing the temporary NL grmode.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
If add_to_waiters() fails we have a problem because the previous called
functions such as validate_lock_args() or validate_unlock_args() sets
specific lkb values that are set for a request, there exists no way back
to revert those changes. When there is a pending lock request the
original request arguments will be overwritten with unknown
consequences.
The good news are that I believe those cases that we fail in
add_to_waiters() can't happen or very unlikely to happen (only if the DLM
user does stupid API things), but if so we have the above mentioned
problem.
There are two conditions that will be removed here. The first one is the
-EINVAL case which contains is_overlap_unlock() or (is_overlap_cancel()
and mstype == DLM_MSG_CANCEL).
The is_overlap_unlock() is missing for the normal UNLOCK case which is
moved to validate_unlock_args(). The is_overlap_cancel() already happens
in validate_unlock_args() when DLM_LKF_CANCEL is set. In case of
validate_lock_args() we check on is_overlap() when it is not a new request,
on a new request the lkb is always new and does not have those values set.
The -EBUSY check can't happen in case as for non new lock requests (when
DLM_LKF_CONVERT is set) we already check in validate_lock_args() for
lkb_wait_type and is_overlap(). Then there is only
validate_unlock_args() that will never hit the default case because
dlm_unlock() will produce DLM_MSG_UNLOCK and DLM_MSG_CANCEL messages.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch fixes a possible null pointer dereference when this function is
called from request_lock() as lkb->lkb_resource is not assigned yet,
only after validate_lock_args() by calling attach_lkb(). Another issue
is that a resource name could be a non printable bytearray and we cannot
assume to be ASCII coded.
The log functionality is probably never being hit when DLM is used in
normal way and no debug logging is enabled. The null pointer dereference
can only occur on a new created lkb that does not have the resource
assigned yet, it probably never hits the null pointer dereference but we
should be sure that other changes might not change this behaviour and we
actually can hit the mentioned null pointer dereference.
In this patch we just drop the printout of the resource name, the lkb id
is enough to make a possible connection to a resource name if this
exists.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch moves the xarray lookup functionality for the lkb out of the
ls_lkbxa_lock read lock handling. We can do that as the xarray should be
possible to access lockless in case of reader like xa_load(). We confirm
under ls_lkbxa_lock that the lkb is still part of the data structure and
take a reference when its still part of ls_lkbxa to avoid being freed
after doing the lookup. To do a check if the lkb is still part of the
ls_lkbxa data structure we use a kref_read() as the last put will remove
it from the ls_lkbxa data structure and any reference taken means it is
still part of ls_lkbxa.
A similar approach was done with the DLM rsb rhashtable just with a flag
instead of the refcounter because the refcounter has a slightly
different meaning.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
The rhashtable structure is lockless for readers such as
rhashtable_lookup_fast(). It should be save to call this lookup
functionality out of holding ls_rsbtbl_lock to get the rsb pointer out
of the hash. This reduce the contention time of ls_rsbtbl_lock in some
cases. We still need to check if the rsb is part of the check as this
state can be changed while ls_rsbtbl_lock is not held. If its part of
the rhashtable data structure we take a reference to be sure it will not
be freed after we drop the ls_rsbtbl_lock read lock.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Since commit 01fdeca1cc2d ("dlm: use rcu to avoid an extra rsb struct
lookup") _dlm_master_lookup() is called under rcu lock that prevents
that the rsb structure is being freed. There was a missing change to
avoid an additional lookup and just check that the rsb is still part of
the ls_rsbtbl structure. This patch is doing such check instead of
lookup the rsb structure again.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch adds a warn on if is_master() and dlm_is_removed() checks on
invalid nodeid states that are probably not what the caller wants to do
here. The is_master() function checking on r->res_nodeid is invalid when
it is set to -1, whereas the dlm_is_removed() has a different meaning
as "nodeid member" and also 0 is invalid.
We run into these cases and this patch changes those cases as we never
will run into them. There should be no functional changes as the
condition should return the same result. However this patch signals now
on caller level that there might be an "extra" case to handle here.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch removes unnecessary refcounts that are obviously not
necessary because either when the pointer is passed as parameter or it
is part of a list we should already hold a reference to it.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch removes a unnecessary parameter from DLM memory allocation
helpers and reduce some functions by just directly reply the pointer
address of the allocated memory.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
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 <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Remove a few calls to add_scan() and del_scan() in cases where
the rsb is a dir record, so the rsb should never be placed on
the scan list at all. Add WARN_ON to catch cases where this
is done.
Signed-off-by: David Teigland <teigland@redhat.com>
The old terminology of "toss" and "keep" is no longer an
accurate description of the rsb states and lists, so change
the names to "inactive" and "active". The old names had
also been copied into the scanning code, which is changed
back to use the "scan" name.
- "active" rsb structs have lkb's attached, and are ref counted.
- "inactive" rsb structs have no lkb's attached, are not ref counted.
- "scan" list is for rsb's that can be freed after a timeout period.
- "slow" lists are for infrequent iterations through active or
inactive rsb structs.
- inactive rsb structs that are directory records will not be put
on the scan list, since they are not freed based on timeouts.
- inactive rsb structs that are not directory records will be
put on the scan list to be freed, since they are not longer needed.
Signed-off-by: David Teigland <teigland@redhat.com>
According to kernel doc idr is deprecated and xarrays should be used
nowadays. This patch is moving the lkb idr implementation to xarrays.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch drops the own written rsb pre allocation mechanism as this is
already done by using kmem caches, we don't need another layer on top of
that to running some pre allocation scheme.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch removes a kref_init() that isn't necessary because the rsb is
created for toss list. Under toss list the rsb should not have any
reference counting logic. If in theory the rsb gets to into keep list
then a kref_init() for res_ref will be initiated.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch changes the orphans mutex to a spinlock since commit
c288745f1d4a ("dlm: avoid blocking receive at the end of recovery") is
using a rwlock_t to lock the DLM message receive path and do_purge() can
be called while this lock is held that forbids to sleep.
We need to use spin_lock_bh() because also a user context that calls
dlm_user_purge() can call do_purge() and since commit 92d59adfaf71
("dlm: do message processing in softirq context") the DLM message
receive path is done under softirq context.
Fixes: c288745f1d4a ("dlm: avoid blocking receive at the end of recovery")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/gfs2/9ad928eb-2ece-4ad9-a79c-d2bce228e4bc@moroto.mountain/
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Convert the lock for lkbidr to an rwlock. Most idr lookups will use
the read lock.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
The conversion to rhashtable introduced a hash table lock per lockspace,
in place of per bucket locks. To make this more scalable, switch to
using a rwlock for hash table access. The common case fast path uses
it as a read lock.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Currently the scand kthread acts like a garbage collection for expired
rsbs on toss list, to clean them up after a certain timeout. It triggers
every couple of seconds and iterates over the toss list while holding
ls_rsbtbl_lock for the whole hash bucket iteration.
To reduce the amount of time holding ls_rsbtbl_lock, we now handle the
disposal of expired rsbs using a per-lockspace timer that expires for the
earliest tossed rsb on the lockspace toss queue. This toss queue is
ordered according to the rsb res_toss_time with the earliest tossed rsb
as the first entry. The toss timer will only trylock() necessary locks,
since it is low priority garbage collection, and will rearm the timer
if trylock() fails. If the timer function does not find any expired
rsb's, it rearms the timer with the next earliest expired rsb.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
In the past we had problems when an rsb had a reference counter greater
than one while in the toss state. An rsb in the toss state is not
actively used for locking, and should not have any other references
apart from the single ref keeping it on the rsb hash. Shift to freeing
rsb's directly rather than using kref_put to free them, since the ref
counting is not meant to be used in this state. Add warnings if ref
counting is seen while an rsb is in the toss state.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Replace our own hash table with the more advanced rhashtable
for keeping rsb structs.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
To prepare for using rhashtable, add two rsb lists for iterating
through rsb's in two uncommon cases where this is necesssary:
- when dumping rsb state from debugfs, now using seq_list.
- when looking at all rsb's during recovery.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
There are several places where lock processing can perform two hash table
lookups, first in the "keep" list, and if not found, in the "toss" list.
This patch introduces a new rsb state flag "RSB_TOSS" to represent the
difference between the state of being on keep vs toss list, so that the
two lists can be combined. This avoids cases of two lookups.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Prepare to replace our own hash table with rhashtable by replacing
the per-bucket locks in our own hash table with a single lock.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Use spin_lock_bh for all spinlocks involved in message processing,
in preparation for softirq message processing. DLM lock requests
from user space involve dlm processing in user context, in addition
to the standard kernel context, necessitating bh variants.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Remove an explicit schedule() call in the message processing path,
in preparation for softirq message processing.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Convert ls_recv_active rw_semaphore to an rwlock to avoid
sleeping, in preparation for softirq message processing.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
The end of the recovery process transitioned to normal message
processing by temporarily blocking the receiving context,
processing saved messages, then unblocking the receiving
context. To avoid blocking the receiving context, the old
wait_queue and mutex are replaced by a new rwlock and the new
RECV_MSG_BLOCKED flag. Received messages are added to the
list of saved messages, protected by the rwlock, until the
flag is cleared, which happens when all saved messages have
been processed.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Convert the rsb struct res_lock from a mutex to a spinlock
in preparation for processing messages in softirq context.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Convert the waiters mutex to a spinlock in prepration for
processing messages in softirq context.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
The waiters_mutex no longer needs to be used in the waiters recovery
functions dlm_recover_waiters_pre() and dlm_recover_waiters_pre().
During recovery, ordinary locking operations are paused, and the
recovery thread is the only context accessing the waiters list,
so the lock is not needed.
Access to the waiters list from debugfs functions is avoided by
taking the top level recovery lock in the debugfs dump function.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Move the rsb root_list from the lockspace to a stack variable since
it is now only used by the ls_recover() function.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Add a new "masters_list" for master rsb structs, with a new
rwlock. The new list is created and used during the recovery
process to send the master rsb names to new nodes. With this
change, the current "root_list" can be used without locking.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
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 <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Remove the context parameter for message allocations and
always use GFP_ATOMIC. This prepares for softirq message
processing.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
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 <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch fixes the following issue:
node 1 is dir
node 2 is master
node 3 is other
1->2: unlock
2: put final lkb, rsb moved to toss
2->1: unlock_reply
1: queue lkb callback with EUNLOCK
2->1: remove
1: receive_remove ignored (rsb on keep because of queued lkb callback)
1: complete lkb callback, put_lkb, move rsb to toss
3->1: lookup
1->3: lookup_reply master=2
3->2: request
2->3: request_reply EBADR
In summary:
An unexpected lkb reference causes the rsb to remain on the wrong list.
The rsb being on the wrong list causes receive_remove to be ignored.
An ignored receive_remove causes inconsistent dir and master state.
This sequence requires an unusually long delay in delivering the unlock
callback, because the remove message from 2->1 usually happens after
some seconds. So, it's not known exactly how frequently this sequence
occurs in pratice. It's possible that the same end result could also
have another unknown cause.
The solution for this issue is to further separate callback state
from the lkb, so that an lkb reference (and from that, an rsb ref)
are not held while a callback remains queued. Then, within the
unlock_reply, the lkb will be freed and the rsb moved to the toss
list. So, the receive_remove will not be ignored.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
When a lock is waiting for a reply for a remote operation, and recovery
interrupts this "waiters" state, the remote operation is voided by the
recovery, and no reply will be processed. The lkb waiters state for the
remote operation is forcibly reset/cleared, so that the lock operation
can be restarted after recovery. Improve the comments describing this.
Signed-off-by: David Teigland <teigland@redhat.com>
Revert "fs: dlm: handle lkb wait count as atomic_t"
This reverts commit 75a7d60134ce84209f2c61ec4619ee543aa8f466.
This counter does not need to be atomic. As the comment in
the reverted commit mentions, the counter is protected by
the rsb lock.
Signed-off-by: David Teigland <teigland@redhat.com>
The dlm receive buffer should be never manipulated as DLM is the last
instance of parsing layer. This patch constify the whole receive buffer
so we are sure it never gets manipulated when it's being parsed.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Currently dlm_recover_master_copy() manipulates the receive buffer of an
rcom lock message and modifies it on the fly so a later memcpy() to a
new rcom message with the same message has those new values. This patch
avoids manipulating the received rcom message by store the values for
the new rcom message in paremter assigned with call by reference. Later
when dlm_send_rcom_lock() constructs a new message and memcpy() the
receive buffer those values will be set on the new constructed message.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch removes a read of the ls->ls_recover_seq uint64_t number in
_create_rcom(). If the ls->ls_recover_seq is readed the ls_recover_lock
need to held. However this number was always readed before when any rcom
message is received and it's not necessary to read it again from a per
lockspace variable to use it for the replying message. This patch will
pass the sequence number as parameter so another read of ls->ls_recover_seq
and holding the ls->ls_recover_lock is not required.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Currently the lkb_wait_count is locked by the rsb lock and it should be
fine to handle lkb_wait_count as non atomic_t value. However for the
overall process of reducing locking this patch converts it to an
atomic_t value.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch warns about messages which are received from nodes who
already left the lockspace resource signaled by the cluster manager.
Before commit 489d8e559c65 ("fs: dlm: add reliable connection if
reconnect") there was a synchronization issue with the socket
lifetime and the cluster event of leaving a lockspace and other
nodes did not stop of sending messages because the cluster manager has a
pending message to leave the lockspace. The reliable session layer for
dlm use sequence numbers to ensure dlm message were never being dropped.
If this is not corrected synchronized we have a problem, this patch will
use the filter case and turn it into a WARN_ON_ONCE() so we seeing such
issue on the kernel log because it should never happen now.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Commit 7175e131ebba ("fs: dlm: fix invalid derefence of sb_lvbptr")
fixes an issue when the lkb->lkb_lvbptr set to an dangled pointer and an
followed memcpy() would fail. It was fixed by an additional check of
DLM_LKF_VALBLK flag. The mentioned commit forgot to add an additional check
if DLM_LKF_VALBLK is set for the additional amount of LVB data allocated
in a dlm message. This patch is changing the message allocation to check
additionally if DLM_LKF_VALBLK is set otherwise a dangled lkb->lkb_lvbptr
pointer would allocated zero LVB message data which not gets filled with
actual data.
This patch is however only a cleanup to reduce the amount of zero bytes
transmitted over network as receive_lvb() will only evaluates message LVB
data if DLM_LKF_VALBLK is set.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch moves lkb_sbflags handling to atomic bits ops. This should
prepare for a possible manipulating of lkb_sbflags flags at the same
time by concurrent execution.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch moves the rsb hash table handling to atomic flag operations.
The flag operations for DLM_RTF_SHRINK are protected by
ls->ls_rsbtbl[b].lock. However we switch to atomic ops if new possible
flags will be used in a different way and don't assume such lock
dependencies.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This patch will move the lkb_flags value to the recently introduced
lkb_iflags value. For lkb_iflags we use atomic bit operations because
some flags like DLM_IFL_CB_PENDING are used while non rsb lock is held
to avoid issues with other flag manipulations which might run at the
same time we switch to atomic bit operations. Snapshot the bit values to
an uint32_t value is only used for debugging/logging use cases and don't
need to be 100% correct.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
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 <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
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 <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
