linux/fs/gfs2/locking/dlm/thread.c, branch master

GFS2: Merge lock_dlm module into GFS2

2009-03-24T11:21:14Z

This is the big patch that I've been working on for some time now. There are many reasons for wanting to make this change such as: o Reducing overhead by eliminating duplicated fields between structures o Simplifcation of the code (reduces the code size by a fair bit) o The locking interface is now the DLM interface itself as proposed some time ago. o Fewer lookups of glocks when processing replies from the DLM o Fewer memory allocations/deallocations for each glock o Scope to do further optimisations in the future (but this patch is more than big enough for now!) Please note that (a) this patch relates to the lock_dlm module and not the DLM itself, that is still a separate module; and (b) that we retain the ability to build GFS2 as a standalone single node filesystem with out requiring the DLM. This patch needs a lot of testing, hence my keeping it I restarted my -git tree after the last merge window. That way, this has the maximum exposure before its merged. This is (modulo a few minor bug fixes) the same patch that I've been posting on and off the the last three months and its passed a number of different tests so far. Signed-off-by: Steven Whitehouse

[GFS2] Remove remote lock dropping code

2008-06-27T08:39:44Z

There are several reasons why this is undesirable: 1. It never happens during normal operation anyway 2. If it does happen it causes performance to be very, very poor 3. It isn't likely to solve the original problem (memory shortage on remote DLM node) it was supposed to solve 4. It uses a bunch of arbitrary constants which are unlikely to be correct for any particular situation and for which the tuning seems to be a black art. 5. In an N node cluster, only 1/N of the dropped locked will actually contribute to solving the problem on average. So all in all we are better off without it. This also makes merging the lock_dlm module into GFS2 a bit easier. Signed-off-by: Steven Whitehouse

[GFS2] Fix ordering bug in lock_dlm

2008-06-27T08:39:25Z

This looks like a lot of change, but in fact its not. Mostly its things moving from one file to another. The change is just that instead of queuing lock completions and callbacks from the DLM we now pass them directly to GFS2. This gives us a net loss of two list heads per glock (a fair saving in memory) plus a reduction in the latency of delivering the messages to GFS2, plus we now have one thread fewer as well. There was a bug where callbacks and completions could be delivered in the wrong order due to this unnecessary queuing which is fixed by this patch. Signed-off-by: Steven Whitehouse Cc: Bob Peterson

[GFS2] Invalidate cache at correct point

2008-03-31T09:41:44Z

GFS2 wasn't invalidating its cache before it called into the lock manager with a request that could potentially drop a lock. This was leaving a window where the lock could be actually be held by another node, but the file's page cache would still appear valid, causing coherency problems. This patch moves the cache invalidation to before the lock manager call when dropping a lock. It also adds the option to the lock_dlm lock manager to not use conversion mode deadlock avoidance, which, on a conversion from shared to exclusive, could internally drop the lock, and then reacquire in. GFS2 now asks lock_dlm to not do this. Instead, GFS2 manually drops the lock and reacquires it. Signed-off-by: Benjamin Marzinski Signed-off-by: Steven Whitehouse

[GFS2] check kthread_should_stop when waiting

2008-01-25T08:07:49Z

Use wait_event_interruptible() in the lock_dlm thread instead of an open coded equivalent, and include a kthread_should_stop() check in the wait test so we don't miss a kthread_stop(). Signed-off-by: David Teigland Signed-off-by: Steven Whitehouse

[GFS2] GFS2: chmod hung - fix race in thread creation

2007-10-10T07:56:22Z

The problem boiled down to a race between the gdlm_init_threads() function initializing thread1 and its setting of blist = 1. Essentially, "if (current == ls->thread1)" was checked by the thread before the thread creator set ls->thread1. Since thread1 is the only thread who is allowed to work on the blocking queue, and since neither thread thought it was thread1, no one was working on the queue. So everything just sat. This patch reuses the ls->async_lock spin_lock to fix the race, and it fixes the problem. I've done more than 2000 iterations of the loop that was recreating the failure and it seems to work. Signed-off-by: Bob Peterson Signed-off-by: Steven Whitehouse --

[GFS2] Reduce size of struct gdlm_lock

2007-07-09T07:22:21Z

This patch removes the completion (which is rather large) from struct gdlm_lock in favour of using the wait_on_bit() functions. We don't need to add any extra fields to the structure to do this, so we save 32 bytes (on x86_64) per structure. This adds up to quite a lot when we may potentially have millions of these lock structures, Signed-off-by: Steven Whitehouse Acked-by: David Teigland

[GFS2/DLM] Fix trailing whitespace

2006-09-25T13:26:04Z

As per Andrew Morton's request, removed trailing whitespace. Cc: Andrew Morton Signed-off-by: Steven Whitehouse

[GFS2] Remove one typedef

2006-09-07T19:50:20Z

This removes one of the typedefs from the locking interface. It is replaced by a forward declaration of the gfs2 superblock. The other two are not so easy to solve since in their case, they can refer to one of two possible structures. Cc: David Teigland Cc: Jan Engelhardt Signed-off-by: Steven Whitehouse

[GFS2] Change all types to uX style

2006-09-04T16:49:07Z

This makes all fixed size types have consistent names. Cc: Jan Engelhardt Signed-off-by: Steven Whitehouse