*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; If not, see
- * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
+ * http://www.gnu.org/licenses/gpl-2.0.html
*
* GPL HEADER END
*/
* Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
* Use is subject to license terms.
*
- * Copyright (c) 2012, 2013, Intel Corporation.
+ * Copyright (c) 2012, 2014 Intel Corporation.
*/
/*
* This file is part of Lustre, http://www.lustre.org/
*
* lustre/ofd/ofd_lvb.c
*
- * Author: Mikhail Pershin <tappro@whamcloud.com>
- * Author: Alexey Zhuravlev <bzzz@whamcloud.com>
+ * This file contains methods for OBD Filter Device (OFD)
+ * Lock Value Block (LVB) operations.
+ *
+ * LVB is special opaque (to LDLM) data that is associated with an LDLM lock
+ * and transferred from client to server and back. OFD LVBs are used to
+ * maintain current object size/times.
+ *
+ * Author: Andreas Dilger <andreas.dilger@intel.com>
+ * Author: Mikhail Pershin <mike.pershin@intel.com>
+ * Author: Alexey Zhuravlev <alexey.zhuravlev@intel.com>
*/
#define DEBUG_SUBSYSTEM S_FILTER
#include "ofd_internal.h"
+/**
+ * Implementation of ldlm_valblock_ops::lvbo_free for OFD.
+ *
+ * This function frees allocated LVB data if it associated with the given
+ * LDLM resource.
+ *
+ * \param[in] res LDLM resource
+ *
+ * \retval 0 on successful setup
+ * \retval negative value on error
+ */
static int ofd_lvbo_free(struct ldlm_resource *res)
{
if (res->lr_lvb_data)
return 0;
}
-/* Called with res->lr_lvb_sem held */
+/**
+ * Implementation of ldlm_valblock_ops::lvbo_init for OFD.
+ *
+ * This function allocates and initializes new LVB data for the given
+ * LDLM resource if it is not allocated yet. New LVB is filled with attributes
+ * of the object associated with that resource. Function does nothing if LVB
+ * for the given LDLM resource is allocated already.
+ *
+ * Called with res->lr_lvb_sem held.
+ *
+ * \param[in] res LDLM resource
+ *
+ * \retval 0 on successful setup
+ * \retval negative value on error
+ */
static int ofd_lvbo_init(struct ldlm_resource *res)
{
struct ost_lvb *lvb;
return rc;
}
-/* This will be called in two ways:
+/**
+ * Implementation of ldlm_valblock_ops::lvbo_update for OFD.
+ *
+ * When a client generates a glimpse enqueue, it wants to get the current
+ * file size and updated attributes for a stat() type operation, but these
+ * attributes may be writeback cached on another client. The client with
+ * the DLM extent lock at the highest offset is asked for its current
+ * attributes via a glimpse callback on its extent lock, on the assumption
+ * that it has the highest file size and the newest timestamps. The timestamps
+ * are guaranteed to be correct if there is only a single writer on the file,
+ * but may be slightly inaccurate if there are multiple concurrent writers on
+ * the same object. In order to avoid race conditions between the glimpse AST
+ * and the client cancelling the lock, ofd_lvbo_update() also updates
+ * the attributes from the local object. If the last client hasn't done any
+ * writes yet, or has already written its data and cancelled its lock before
+ * it processed the glimpse, then the local inode will have more uptodate
+ * information.
+ *
+ * This is called in two ways:
+ * \a req != NULL : called by the DLM itself after a glimpse callback
+ * \a req == NULL : called by the OFD after a disk write
*
- * r != NULL : called by the DLM itself after a glimpse callback
- * r == NULL : called by the ofd after a disk write
+ * \param[in] res LDLM resource
+ * \param[in] req PTLRPC request
+ * \param[in] increase_only don't allow LVB values to decrease
*
- * If 'increase_only' is true, don't allow values to move backwards.
+ * \retval 0 on successful setup
+ * \retval negative value on error
*/
static int ofd_lvbo_update(struct ldlm_resource *res,
struct ptlrpc_request *req, int increase_only)
return rc;
}
+/**
+ * Implementation of ldlm_valblock_ops::lvbo_size for OFD.
+ *
+ * This function returns size of LVB data so appropriate RPC size will be
+ * reserved. This is used for compatibility needs between server and client
+ * of different Lustre versions.
+ *
+ * \param[in] lock LDLM lock
+ *
+ * \retval size of LVB data
+ */
static int ofd_lvbo_size(struct ldlm_lock *lock)
{
if (lock->l_export != NULL && exp_connect_lvb_type(lock->l_export))
return sizeof(struct ost_lvb_v1);
}
+/**
+ * Implementation of ldlm_valblock_ops::lvbo_fill for OFD.
+ *
+ * This function is called to fill the given RPC buffer \a buf with LVB data
+ *
+ * \param[in] lock LDLM lock
+ * \param[in] buf RPC buffer to fill
+ * \param[in] buflen buffer length
+ *
+ * \retval size of LVB data written into \a buf buffer
+ */
static int ofd_lvbo_fill(struct ldlm_lock *lock, void *buf, int buflen)
{
struct ldlm_resource *res = lock->l_resource;