[dm-devel] device-mapper mirror module (dm-raid)
Penguin Lin
penguin.taiwan at gmail.com
Fri Apr 13 09:49:07 UTC 2007
Dear all:
Recently I am keeping tracing the device-mapper codes in kernel-2.6.20.1
There are still some question that confuse me...
and I hope to change something in mirror driver...
---------------------------------------------------------------
1. Is recovery here really necessary ?
Every time when a bio is written to a mirrred target, mirror driver will
queue
this io to the write bio_list whthin the mirror_set, finally a kcopyd will
be
invoke to write this bio to all mirrored device. Is the flow correct?
But... there are nothing doing in the write callback function
(write_callback).... right ?
So in the current version, we won't have any regions that is needed to be
recovered.
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2. Should we put all read action into the read bio_list of the mirror_set ?
In mirror_map.... should we put all read requests into the read bio_list of
the
mirror_set after check the return value from log->type->in_sync(), since
do_read() method does the same thing and it will be invoke when a do_work
is invoke? Or shoulwe d move all read actions including the checking
(in mirror_map) to the do_read() function ?
----------------------------------------------------------------
Thanks for all...
and please forgive my Chinese English..... is too poor....
(hopes some one understand what I am talking about in above...)
regard.
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