such that we don't actually hold a simplelock while we are doing
a pool_get(), but that we still effectively protecting critical code.
This should fix all of the outstanding LOCKDEBUG warnings related to
rebuilding RAID sets.
- remove callbackArg2 from RF_CallbackDesc_s -- it is only ever set,
never read.
- now that this is done, all callbacks should only take a single argument,
and we can simplify things further.
- change function signature of rf_LookupRUStatus(). The last argument
is now a pointer to a new PSS, in case one is needed. Rather than
having rf_LookupRUStatus() allocate a new PSS, we pre-allocate one
beforehand, where necessary, just in case.
- change callers of rf_lookupRUStatus() to deal with the new way of
calling rf_lookupRUStatus().
[no improvement or worsening of parity rebuild/initialization performance.]
[For the record: The mcpair mutex is being used to protect mcpair->flag.
mcpair gets allocated before each call to rf_DispatchDAG(), so there is no
other process/thread that could be mucking with it. It is only used to
detect the completion of a given parity unit, and rf_DispatchDAG()
only uses it to setup the callback argument for rf_MCPairWakeupFunc()
which will be called when the IO completes. The code after the call
to rf_DispatchDAG() sits and waits for a 'wakeup' on mcpair->cond
(rf_MCPairWakeupFunc() does that). If mcpair->flag is 0 when
rf_DispatchDAG() completes, then rf_MCPairWakeupFunc() hasn't been
called yet (the IO hasn't completed). If it is 1, then the IO is
already done, and we continue on our merry way without sleeping.
Thus, we don't need to hold any lock on mcpair while calling
rf_DispatchDAG().]
~forever. This requires a number of things:
1) If we can't create a DAG, set desc->numStripes to 0 in
rf_SelectAlgorithm. This will ensure that we don't attempt to free
any dagArray[] elements in rf_StateCleanup.
2) Modify rf_State_CreateDAG() to not panic in the event of a DAG
failure. Instead, set the bp->b_flags and bp->b_error, and set things
up to skip to rf_State_Cleanup().
3) Need to mark desc->status as "bad" so that we actually stop looking
for a different DAG. (which we won't find... no matter how many times
we try).
4) rf_State_LastState() will then do the biodone(), and return EIO for
the IO in question.
5) Remove some " || 1 "'s from ProcessNode(). These were for
debugging, and we don't need the failure notices spewing
over and over again as the failing DAGs are processed.
6) Needed to change
if (asmap->numDataFailed + asmap->numParityFailed > 1)
to
if ((asmap->numDataFailed + asmap->numParityFailed > 1) ||
(raidPtr->numFailures > 1)){
in rf_raid5.c so that it doesn't try to return
rf_CreateNonRedundantWriteDAG as the creation function.
7) Note that we can't apply the above change to the RAID 1 code as
with the silly "fake 2-D" RAID 1 sets, it is possible to have 2 failed
components in the RAID 1 set, and that would stop them from working.
(I really don't know why/how those "fake 2-D" RAID 1 sets even work
with all the "single-fault" assumptions present in the rest of the
code.)
8) Needed to protect rf_RAID0DagSelect() in a similar way -- it should
return NULL as the createFunc.
9) No point printing out "Multiple disks failed..." a zillion times.
was just an accident in the first place. Cleanup function decls and
a few comments. [ok.. so I wasn't going to fix this many.. but once
you're on a roll....]
of strenuous agreement, and some general agreement, this commit is
going ahead because it's now starting to block some other changes I
wish to make.]
Remove most of the support for the concept of "rows" from RAIDframe.
While the "row" interface has been exported to the world, RAIDframe
internals have really only supported a single row, even though they
have feigned support of multiple rows.
Nothing changes in configuration land -- config files still need to
specify a single row, etc. All auto-config structures remain fully
forward/backwards compatible.
The only visible difference to the average user should be a
reduction in the size of a GENERIC kernel (i386) by 4.5K. For those
of us trolling through RAIDframe kernel code, a lot of the driver
configuration code has become a LOT easier to read.
out-dated comments, and other unneeded stuff. This helps prepare
for cleaning up the rest of the code, and adding new functionality.
No functional changes to the kernel code in this commit.
Carnegie Mellon University. Full RAID implementation, including
levels 0, 1, 4, 5, 6, parity logging, and a few other goodies.
Ported to NetBSD by Greg Oster.
mrg