linux/fs/gfs2/locking/dlm, branch v3.4.7

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: Send useful information with uevent messages

2009-01-05T07:39:15Z

In order to distinguish between two differing uevent messages and to avoid using the (racy) method of reading status from sysfs in future, this adds some status information to our uevent messages. Btw, before anybody says "sysfs isn't racy", I'm aware of that, but the way that GFS2 was using it (send an ambiugous uevent and then expect the receiver to read sysfs to find out the status of the reported operation) was. The additional benefit of using the new interface is that it should be possible for a node to recover multiple journals at the same time, since there is no longer any confusion as to which journal the status belongs to. At some future stage, when all the userland programs have been converted, I intend to remove the old interface. Signed-off-by: Steven Whitehouse

GFS2: Send some sensible sysfs stuff

2009-01-05T07:39:10Z

We ought to inform the user of the locktable and lockproto for each uevent we generate. Signed-off-by: Steven Whitehouse

dlm: allow multiple lockspace creates

2008-08-28T16:49:15Z

Add a count for lockspace create and release so that create can be called multiple times to use the lockspace from different places. Also add the new flag DLM_LSFL_NEWEXCL to create a lockspace with the previous behavior of returning -EEXIST if the lockspace already exists. Signed-off-by: David Teigland

[GFS2] Fix module building

2008-06-27T08:40:57Z

Two lines missed from the previous patch. Signed-off-by: Steven Whitehouse

[GFS2] Remove all_list from lock_dlm

2008-06-27T08:39:50Z

I discovered that we had a list onto which every lock_dlm lock was being put. Its only function was to discover whether we'd got any locks left after umount. Since there was already a counter for that purpose as well, I removed the list. The saving is sizeof(struct list_head) per glock - well worth having. Signed-off-by: Steven Whitehouse

[GFS2] Remove obsolete conversion deadlock avoidance code

2008-06-27T08:39:47Z

This is only used by GFS1 so can be removed. 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] Clean up the glock core

2008-06-27T08:39:22Z

This patch implements a number of cleanups to the core of the GFS2 glock code. As a result a lot of code is removed. It looks like a really big change, but actually a large part of this patch is either removing or moving existing code. There are some new bits too though, such as the new run_queue() function which is considerably streamlined. Highlights of this patch include: o Fixes a cluster coherency bug during SH -> EX lock conversions o Removes the "glmutex" code in favour of a single bit lock o Removes the ->go_xmote_bh() for inodes since it was duplicating ->go_lock() o We now only use the ->lm_lock() function for both locks and unlocks (i.e. unlock is a lock with target mode LM_ST_UNLOCKED) o The fast path is considerably shortly, giving performance gains especially with lock_nolock o The glock_workqueue is now used for all the callbacks from the DLM which allows us to simplify the lock_dlm module (see following patch) o The way is now open to make further changes such as eliminating the two threads (gfs2_glockd and gfs2_scand) in favour of a more efficient scheme. This patch has undergone extensive testing with various test suites so it should be pretty stable by now. Signed-off-by: Steven Whitehouse Cc: Bob Peterson