staging/lustre/clio: cl_lock simplification

In this patch, the cl_lock cache is eliminated. cl_lock is turned
into a cacheless data container for the requirements of locks to
complete the IO. cl_lock is created before I/O starts and destroyed
when the I/O is complete.

cl_lock depends on LDLM lock to fulfill lock semantics. LDLM lock
is attached to cl_lock at OSC layer. LDLM lock is still cacheable.

Two major methods are supported for cl_lock: clo_enqueue and
clo_cancel.  A cl_lock is enqueued by cl_lock_request(), which will
call clo_enqueue() methods for each layer to enqueue the lock.
At the LOV layer, if a cl_lock consists of multiple sub cl_locks,
each sub locks will be enqueued correspondingly. At OSC layer, the
lock enqueue request will tend to reuse cached LDLM lock; otherwise
a new LDLM lock will have to be requested from OST side.

cl_lock_cancel() must be called to release a cl_lock after use.
clo_cancel() method will be called for each layer to release the
resource held by this lock. At OSC layer, the reference count of LDLM
lock, which is held at clo_enqueue time, is released.

LDLM lock can only be canceled if there is no cl_lock using it.

Signed-off-by: Bobi Jam <bobijam.xu@intel.com>
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-on: http://review.whamcloud.com/10858
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3259
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 8 insertions, 8 deletions

diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_request.c b/drivers/staging/lustre/lustre/ldlm/ldlm_request.c
index d5968e01edd8..42925ac3331c 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_request.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_request.c
@@ -347,7 +347,6 @@ int ldlm_cli_enqueue_fini(struct obd_export *exp, struct ptlrpc_request *req,
 	struct ldlm_lock *lock;
 	struct ldlm_reply *reply;
 	int cleanup_phase = 1;
-	int size = 0;
 
 	lock = ldlm_handle2lock(lockh);
 	/* ldlm_cli_enqueue is holding a reference on this lock. */
@@ -375,8 +374,8 @@ int ldlm_cli_enqueue_fini(struct obd_export *exp, struct ptlrpc_request *req,
 		goto cleanup;
 	}
 
-	if (lvb_len != 0) {
-		LASSERT(lvb);
+	if (lvb_len > 0) {
+		int size = 0;
 
 		size = req_capsule_get_size(&req->rq_pill, &RMF_DLM_LVB,
 					    RCL_SERVER);
@@ -390,12 +389,13 @@ int ldlm_cli_enqueue_fini(struct obd_export *exp, struct ptlrpc_request *req,
 			rc = -EINVAL;
 			goto cleanup;
 		}
+		lvb_len = size;
 	}
 
 	if (rc == ELDLM_LOCK_ABORTED) {
-		if (lvb_len != 0)
+		if (lvb_len > 0 && lvb)
 			rc = ldlm_fill_lvb(lock, &req->rq_pill, RCL_SERVER,
-					   lvb, size);
+					   lvb, lvb_len);
 		if (rc == 0)
 			rc = ELDLM_LOCK_ABORTED;
 		goto cleanup;
@@ -489,7 +489,7 @@ int ldlm_cli_enqueue_fini(struct obd_export *exp, struct ptlrpc_request *req,
 	/* If the lock has already been granted by a completion AST, don't
 	 * clobber the LVB with an older one.
 	 */
-	if (lvb_len != 0) {
+	if (lvb_len > 0) {
 		/* We must lock or a racing completion might update lvb without
 		 * letting us know and we'll clobber the correct value.
 		 * Cannot unlock after the check either, as that still leaves
@@ -498,7 +498,7 @@ int ldlm_cli_enqueue_fini(struct obd_export *exp, struct ptlrpc_request *req,
 		lock_res_and_lock(lock);
 		if (lock->l_req_mode != lock->l_granted_mode)
 			rc = ldlm_fill_lvb(lock, &req->rq_pill, RCL_SERVER,
-					   lock->l_lvb_data, size);
+					   lock->l_lvb_data, lvb_len);
 		unlock_res_and_lock(lock);
 		if (rc < 0) {
 			cleanup_phase = 1;
@@ -518,7 +518,7 @@ int ldlm_cli_enqueue_fini(struct obd_export *exp, struct ptlrpc_request *req,
 		}
 	}
 
-	if (lvb_len && lvb) {
+	if (lvb_len > 0 && lvb) {
 		/* Copy the LVB here, and not earlier, because the completion
 		 * AST (if any) can override what we got in the reply
 		 */