The goal of this ticket is to land into WC 1.8 branch next patches from Vladimir Saveliev (Oracle):

https://bugzilla.lustre.org/attachment.cgi?id=33145
https://bugzilla.lustre.org/attachment.cgi?id=33137
https://bugzilla.lustre.org/attachment.cgi?id=33106
https://bugzilla.lustre.org/attachment.cgi?id=33099

(details of these patches are in the https://bugzilla.lustre.org/show_bug.cgi?id=24450).

Patches summary:

ldlm_run_bl_ast_work() sends ASTs in set of PARALLEL_AST_LIMIT
requests and waits for whole set to complete and then sends another
set of requests and waits again. If there is a least one request per
set which timeouts, we have timeout serialization.

This patch changes ldlm_run_bl_ast_work() so that having sent one
set it then waits for any of its requests to complete and refills
the running set with requests which are yet to be sent. For a case
where number of timeout-ing requests is smaller than
PARALLEL_AST_LIMIT it is supposed to eliminate possibility of timeout
serailization.

This patch uses posibility to specify wait condition for
ptlrpc_set_wait().