Commit 82a373ae authored by Liang Zhen's avatar Liang Zhen Committed by Greg Kroah-Hartman
Browse files

lustre/ptlrpc: re-enqueue ptlrpcd worker 



osc_extent_wait can be stuck in scenario like this:

1) thread-1 held an active extent
2) thread-2 called flush cache, and marked this extent as "urgent"
   and "sync_wait"
3) thread-3 wants to write to the same extent, osc_extent_find will
   get "conflict" because this extent is "sync_wait", so it starts
   to wait...
4) cl_writeback_work has been scheduled by thread-4 to write some
   other extents, it has sent RPCs but not returned yet.
5) thread-1 finished his work, and called osc_extent_release()->
   osc_io_unplug_async()->ptlrpcd_queue_work(), but found
   cl_writeback_work is still running, so it's ignored (-EBUSY)
6) thread-3 is stuck because nobody will wake him up.

This patch allows ptlrpcd_work to be rescheduled, so it will not
miss request anymore

Signed-off-by: default avatarLiang Zhen <liang.zhen@intel.com>
Reviewed-on: http://review.whamcloud.com/8922
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4509


Reviewed-by: default avatarJinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: default avatarBobi Jam <bobijam@gmail.com>
Reviewed-by: default avatarOleg Drokin <oleg.drokin@intel.com>
Signed-off-by: default avatarOleg Drokin <oleg.drokin@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 15c50ccc

drivers/staging/lustre/lustre/ptlrpc/client.c

+40 −24
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ 
#include "ptlrpc_internal.h"



static int ptlrpc_send_new_req(struct ptlrpc_request *req);

static int ptlrpcd_check_work(struct ptlrpc_request *req);



/**

 * Initialize passed in client structure \a cl.
@@ -1779,6 +1780,10 @@ interpret: 


		ptlrpc_req_interpret(env, req, req->rq_status);



		if (ptlrpcd_check_work(req)) {

			atomic_dec(&set->set_remaining);

			continue;

		}

		ptlrpc_rqphase_move(req, RQ_PHASE_COMPLETE);



		CDEBUG(req->rq_reqmsg != NULL ? D_RPCTRACE : 0,
@@ -2952,22 +2957,50 @@ EXPORT_SYMBOL(ptlrpc_sample_next_xid); 
 *    have delay before it really runs by ptlrpcd thread.

 */

struct ptlrpc_work_async_args {

	__u64   magic;

	int   (*cb)(const struct lu_env *, void *);

	void   *cbdata;

};



#define PTLRPC_WORK_MAGIC 0x6655436b676f4f44ULL /* magic code */

static void ptlrpcd_add_work_req(struct ptlrpc_request *req)

{

	/* re-initialize the req */

	req->rq_timeout		= obd_timeout;

	req->rq_sent		= cfs_time_current_sec();

	req->rq_deadline	= req->rq_sent + req->rq_timeout;

	req->rq_reply_deadline	= req->rq_deadline;

	req->rq_phase		= RQ_PHASE_INTERPRET;

	req->rq_next_phase	= RQ_PHASE_COMPLETE;

	req->rq_xid		= ptlrpc_next_xid();

	req->rq_import_generation = req->rq_import->imp_generation;



	ptlrpcd_add_req(req, PDL_POLICY_ROUND, -1);

}



static int work_interpreter(const struct lu_env *env,

			    struct ptlrpc_request *req, void *data, int rc)

{

	struct ptlrpc_work_async_args *arg = data;



	LASSERT(arg->magic == PTLRPC_WORK_MAGIC);

	LASSERT(ptlrpcd_check_work(req));

	LASSERT(arg->cb != NULL);



	return arg->cb(env, arg->cbdata);

	rc = arg->cb(env, arg->cbdata);



	list_del_init(&req->rq_set_chain);

	req->rq_set = NULL;



	if (atomic_dec_return(&req->rq_refcount) > 1) {

		atomic_set(&req->rq_refcount, 2);

		ptlrpcd_add_work_req(req);

	}

	return rc;

}



static int worker_format;



static int ptlrpcd_check_work(struct ptlrpc_request *req)

{

	return req->rq_pill.rc_fmt == (void *)&worker_format;

}



/**
@@ -3000,6 +3033,7 @@ void *ptlrpcd_alloc_work(struct obd_import *imp, 
	req->rq_receiving_reply = 0;

	req->rq_must_unlink = 0;

	req->rq_no_delay = req->rq_no_resend = 1;

	req->rq_pill.rc_fmt = (void *)&worker_format;



	spin_lock_init(&req->rq_lock);

	INIT_LIST_HEAD(&req->rq_list);
@@ -3013,7 +3047,6 @@ void *ptlrpcd_alloc_work(struct obd_import *imp, 


	CLASSERT(sizeof(*args) <= sizeof(req->rq_async_args));

	args = ptlrpc_req_async_args(req);

	args->magic  = PTLRPC_WORK_MAGIC;

	args->cb     = cb;

	args->cbdata = cbdata;
@@ -3043,25 +3076,8 @@ int ptlrpcd_queue_work(void *handler) 
	 * req as opaque data. - Jinshan

	 */

	LASSERT(atomic_read(&req->rq_refcount) > 0);

	if (atomic_read(&req->rq_refcount) > 1)

		return -EBUSY;



	if (atomic_inc_return(&req->rq_refcount) > 2) { /* race */

		atomic_dec(&req->rq_refcount);

		return -EBUSY;

	}



	/* re-initialize the req */

	req->rq_timeout	= obd_timeout;

	req->rq_sent	   = cfs_time_current_sec();

	req->rq_deadline       = req->rq_sent + req->rq_timeout;

	req->rq_reply_deadline = req->rq_deadline;

	req->rq_phase	  = RQ_PHASE_INTERPRET;

	req->rq_next_phase     = RQ_PHASE_COMPLETE;

	req->rq_xid	    = ptlrpc_next_xid();

	req->rq_import_generation = req->rq_import->imp_generation;



	ptlrpcd_add_req(req, PDL_POLICY_ROUND, -1);

	if (atomic_inc_return(&req->rq_refcount) == 2)

		ptlrpcd_add_work_req(req);

	return 0;

}

EXPORT_SYMBOL(ptlrpcd_queue_work);

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