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pnfs: new locking model for layouts

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exclusive locks are no longer held over LAYOUTGET, LAYOUTRETURN, or GETDEVICEINFO rpcs.  this prevents a deadlock when CB_LAYOUTRECALL needs an exclusive lock while another operation is on the wire

introduced a 'pending' condition variable to protect access to state->layout while the layout's lock is not held

updated file_layout_recall() to compare the stateid sequence numbers to determine if the server has processed an outstanding LAYOUTGET or LAYOUTRETURN, where we're required to reply with NFS4ERR_DELAY

LAYOUTGET, LAYOUTRETURN, and GETDEVICEINFO can now be sent with try_recovery=TRUE because they no longer hold an exclusive lock.  this makes it possible for recover_client_state() to recall all of the client's layouts without deadlocking

Signed-off-by: Casey Bodley <cbodley@citi.umich.edu>
This commit is contained in:
Casey Bodley 2011-03-10 12:46:34 -05:00 • committed by unknown
parent c9585d937f
commit bf53e3dc1a
4 changed files with 77 additions and 24 deletions
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21
daemon/callback_server.c
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@ -41,20 +41,23 @@ static enum_t handle_cb_layoutrecall(
OUT struct cb_layoutrecall_res *res)
{
enum pnfs_status status;
/* forgetful model for layout recalls; return NOMATCHING_LAYOUT
* and flag the layout(s) to prevent further use */
res->status = NFS4ERR_NOMATCHING_LAYOUT;
status = pnfs_file_layout_recall(rpc_clnt->client, args);
switch (status) {
case PNFS_PENDING:
/* not enough information to process the recall yet */
res->status = NFS4ERR_DELAY;
break;
default:
/* forgetful model for layout recalls */
res->status = NFS4ERR_NOMATCHING_LAYOUT;
break;
}
dprintf(CBSLVL, " OP_CB_LAYOUTRECALL { %s, %s, recall %u } %s\n",
pnfs_layout_type_string(args->type),
pnfs_iomode_string(args->iomode), args->recall.type,
nfs_error_string(res->status));
status = pnfs_file_layout_recall(rpc_clnt->client, args);
if (status)
eprintf("pnfs_file_layout_recall() failed with %s\n",
pnfs_error_string(status));
return res->status;
}