text: /*
   * GPL HEADER START
   *
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 only,
   * as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License version 2 for more details (a copy is included
   * in the LICENSE file that accompanied this code).
   *
   * You should have received a copy of the GNU General Public License
   * version 2 along with this program; If not, see
   * http://www.gnu.org/licenses/gpl-2.0.html
   *
   * GPL HEADER END
   */
  /*
   * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
   * Use is subject to license terms.
   *
   * Copyright (c) 2012, 2015, Intel Corporation.
   */
  /*
   * This file is part of Lustre, http://www.lustre.org/
   * Lustre is a trademark of Sun Microsystems, Inc.
   */
  /*
   * This file is part of Lustre, http://www.lustre.org/
   * Lustre is a trademark of Sun Microsystems, Inc.
   *
   * Internal interfaces of OSC layer.
   *
   *   Author: Nikita Danilov <nikita.danilov@sun.com>
   *   Author: Jinshan Xiong <jinshan.xiong@whamcloud.com>
   */
  
  #ifndef OSC_CL_INTERNAL_H
  #define OSC_CL_INTERNAL_H
  
  #include <linux/libcfs/libcfs.h>
  
  #include <obd.h>
  /* osc_build_res_name() */
  #include <cl_object.h>
  #include "osc_internal.h"
  
  /** \defgroup osc osc
   *  @{
   */
  
  struct osc_extent;
  
  /**
   * State maintained by osc layer for each IO context.
   */
  struct osc_io {
  	/** super class */
  	struct cl_io_slice oi_cl;
  	/** true if this io is lockless. */
  	unsigned int		oi_lockless:1,
  	/** true if this io is counted as active IO */
  				oi_is_active:1;
  	/** how many LRU pages are reserved for this IO */
  	unsigned long		oi_lru_reserved;
  
  	/** active extents, we know how many bytes is going to be written,
  	 * so having an active extent will prevent it from being fragmented
  	 */
  	struct osc_extent *oi_active;
  	/** partially truncated extent, we need to hold this extent to prevent
  	 * page writeback from happening.
  	 */
  	struct osc_extent *oi_trunc;
  
  	/** write osc_lock for this IO, used by osc_extent_find(). */
  	struct osc_lock   *oi_write_osclock;
  	struct obdo	oi_oa;
  	struct osc_async_cbargs {
  		bool		  opc_rpc_sent;
  		int	       opc_rc;
  		struct completion	opc_sync;
  	} oi_cbarg;
  };
  
  /**
   * State maintained by osc layer for the duration of a system call.
   */
  struct osc_session {
  	struct osc_io       os_io;
  };
  
  #define OTI_PVEC_SIZE 256
  struct osc_thread_info {
  	struct ldlm_res_id      oti_resname;
  	union ldlm_policy_data	oti_policy;
  	struct cl_lock_descr    oti_descr;
  	struct cl_attr	  oti_attr;
  	struct lustre_handle    oti_handle;
  	struct cl_page_list     oti_plist;
  	struct cl_io		oti_io;
  	void			*oti_pvec[OTI_PVEC_SIZE];
  	/**
  	 * Fields used by cl_lock_discard_pages().
  	 */
  	pgoff_t			oti_next_index;
  	pgoff_t			oti_fn_index; /* first non-overlapped index */
  	struct cl_sync_io	oti_anchor;
  	struct cl_req_attr	oti_req_attr;
  };
  
  struct osc_object {
  	struct cl_object   oo_cl;
  	struct lov_oinfo  *oo_oinfo;
  	/**
  	 * True if locking against this stripe got -EUSERS.
  	 */
  	int		oo_contended;
  	unsigned long	 oo_contention_time;
  	/**
  	 * used by the osc to keep track of what objects to build into rpcs.
  	 * Protected by client_obd->cli_loi_list_lock.
  	 */
  	struct list_head	   oo_ready_item;
  	struct list_head	   oo_hp_ready_item;
  	struct list_head	   oo_write_item;
  	struct list_head	   oo_read_item;
  
  	/**
  	 * extent is a red black tree to manage (async) dirty pages.
  	 */
  	struct rb_root       oo_root;
  	/**
  	 * Manage write(dirty) extents.
  	 */
  	struct list_head	   oo_hp_exts; /* list of hp extents */
  	struct list_head	   oo_urgent_exts; /* list of writeback extents */
  	struct list_head	   oo_rpc_exts;
  
  	struct list_head	   oo_reading_exts;
  
  	atomic_t	 oo_nr_reads;
  	atomic_t	 oo_nr_writes;
  
  	/** Protect extent tree. Will be used to protect
  	 * oo_{read|write}_pages soon.
  	 */
  	spinlock_t	    oo_lock;
  
  	/**
  	 * Radix tree for caching pages
  	 */
  	struct radix_tree_root	oo_tree;
  	spinlock_t		oo_tree_lock;
  	unsigned long		oo_npages;
  
  	/* Protect osc_lock this osc_object has */
  	spinlock_t		oo_ol_spin;
  	struct list_head	oo_ol_list;
  
  	/** number of active IOs of this object */
  	atomic_t		oo_nr_ios;
  	wait_queue_head_t	oo_io_waitq;
  };
  
  static inline void osc_object_lock(struct osc_object *obj)
  {
  	spin_lock(&obj->oo_lock);
  }
  
  static inline int osc_object_trylock(struct osc_object *obj)
  {
  	return spin_trylock(&obj->oo_lock);
  }
  
  static inline void osc_object_unlock(struct osc_object *obj)
  {
  	spin_unlock(&obj->oo_lock);
  }
  
  static inline int osc_object_is_locked(struct osc_object *obj)
  {
  #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
  	return spin_is_locked(&obj->oo_lock);
  #else
  	/*
  	 * It is not perfect to return true all the time.
  	 * But since this function is only used for assertion
  	 * and checking, it seems OK.
  	 */
  	return 1;
  #endif
  }
  
  /*
   * Lock "micro-states" for osc layer.
   */
  enum osc_lock_state {
  	OLS_NEW,
  	OLS_ENQUEUED,
  	OLS_UPCALL_RECEIVED,
  	OLS_GRANTED,
  	OLS_CANCELLED
  };
  
  /**
   * osc-private state of cl_lock.
   *
   * Interaction with DLM.
   *
   * Once receive upcall is invoked, osc_lock remembers a handle of DLM lock in
   * osc_lock::ols_handle and a pointer to that lock in osc_lock::ols_dlmlock.
   *
   * This pointer is protected through a reference, acquired by
   * osc_lock_upcall0(). Also, an additional reference is acquired by
   * ldlm_lock_addref() call protecting the lock from cancellation, until
   * osc_lock_unuse() releases it.
   *
   * Below is a description of how lock references are acquired and released
   * inside of DLM.
   *
   * - When new lock is created and enqueued to the server (ldlm_cli_enqueue())
   *      - ldlm_lock_create()
   *	  - ldlm_lock_new(): initializes a lock with 2 references. One for
   *	    the caller (released when reply from the server is received, or on
   *	    error), and another for the hash table.
   *      - ldlm_lock_addref_internal(): protects the lock from cancellation.
   *
   * - When reply is received from the server (osc_enqueue_interpret())
   *      - ldlm_cli_enqueue_fini()
   *	  - LDLM_LOCK_PUT(): releases caller reference acquired by
   *	    ldlm_lock_new().
   *	  - if (rc != 0)
   *		ldlm_lock_decref(): error case: matches ldlm_cli_enqueue().
   *      - ldlm_lock_decref(): for async locks, matches ldlm_cli_enqueue().
   *
   * - When lock is being cancelled (ldlm_lock_cancel())
   *      - ldlm_lock_destroy()
   *	  - LDLM_LOCK_PUT(): releases hash-table reference acquired by
   *	    ldlm_lock_new().
   *
   * osc_lock is detached from ldlm_lock by osc_lock_detach() that is called
   * either when lock is cancelled (osc_lock_blocking()), or when locks is
   * deleted without cancellation (e.g., from cl_locks_prune()). In the latter
   * case ldlm lock remains in memory, and can be re-attached to osc_lock in the
   * future.
   */
  struct osc_lock {
  	struct cl_lock_slice     ols_cl;
  	/** Internal lock to protect states, etc. */
  	spinlock_t		ols_lock;
  	/** Owner sleeps on this channel for state change */
  	struct cl_sync_io	*ols_owner;
  	/** waiting list for this lock to be cancelled */
  	struct list_head	ols_waiting_list;
  	/** wait entry of ols_waiting_list */
  	struct list_head	ols_wait_entry;
  	/** list entry for osc_object::oo_ol_list */
  	struct list_head	ols_nextlock_oscobj;
  
  	/** underlying DLM lock */
  	struct ldlm_lock	*ols_dlmlock;
  	/** DLM flags with which osc_lock::ols_lock was enqueued */
  	__u64		    ols_flags;
  	/** osc_lock::ols_lock handle */
  	struct lustre_handle     ols_handle;
  	struct ldlm_enqueue_info ols_einfo;
  	enum osc_lock_state      ols_state;
  	/** lock value block */
  	struct ost_lvb		ols_lvb;
  
  	/**
  	 * true, if ldlm_lock_addref() was called against
  	 * osc_lock::ols_lock. This is used for sanity checking.
  	 *
  	 * \see osc_lock::ols_has_ref
  	 */
  	unsigned		  ols_hold :1,
  	/**
  	 * this is much like osc_lock::ols_hold, except that this bit is
  	 * cleared _after_ reference in released in osc_lock_unuse(). This
  	 * fine distinction is needed because:
  	 *
  	 *     - if ldlm lock still has a reference, osc_ast_data_get() needs
  	 *       to return associated cl_lock (so that a flag is needed that is
  	 *       cleared after ldlm_lock_decref() returned), and
  	 *
  	 *     - ldlm_lock_decref() can invoke blocking ast (for a
  	 *       LDLM_FL_CBPENDING lock), and osc_lock functions like
  	 *       osc_lock_cancel() called from there need to know whether to
  	 *       release lock reference (so that a flag is needed that is
  	 *       cleared before ldlm_lock_decref() is called).
  	 */
  				 ols_has_ref:1,
  	/**
  	 * inherit the lockless attribute from top level cl_io.
  	 * If true, osc_lock_enqueue is able to tolerate the -EUSERS error.
  	 */
  				 ols_locklessable:1,
  	/**
  	 * if set, the osc_lock is a glimpse lock. For glimpse locks, we treat
  	 * the EVAVAIL error as tolerable, this will make upper logic happy
  	 * to wait all glimpse locks to each OSTs to be completed.
  	 * Glimpse lock converts to normal lock if the server lock is
  	 * granted.
  	 * Glimpse lock should be destroyed immediately after use.
  	 */
  				 ols_glimpse:1,
  	/**
  	 * For async glimpse lock.
  	 */
  				 ols_agl:1;
  };
  
  /**
   * Page state private for osc layer.
   */
  struct osc_page {
  	struct cl_page_slice  ops_cl;
  	/**
  	 * Page queues used by osc to detect when RPC can be formed.
  	 */
  	struct osc_async_page ops_oap;
  	/**
  	 * An offset within page from which next transfer starts. This is used
  	 * by cl_page_clip() to submit partial page transfers.
  	 */
  	int		   ops_from;
  	/**
  	 * An offset within page at which next transfer ends.
  	 *
  	 * \see osc_page::ops_from.
  	 */
  	int		   ops_to;
  	/**
  	 * Boolean, true iff page is under transfer. Used for sanity checking.
  	 */
  	unsigned	      ops_transfer_pinned:1,
  	/**
  	 * in LRU?
  	 */
  			      ops_in_lru:1,
  	/**
  	 * Set if the page must be transferred with OBD_BRW_SRVLOCK.
  	 */
  			      ops_srvlock:1;
  	/**
  	 * lru page list. See osc_lru_{del|use}() in osc_page.c for usage.
  	 */
  	struct list_head	      ops_lru;
  	/**
  	 * Submit time - the time when the page is starting RPC. For debugging.
  	 */
  	unsigned long	    ops_submit_time;
  };
  
  extern struct kmem_cache *osc_lock_kmem;
  extern struct kmem_cache *osc_object_kmem;
  extern struct kmem_cache *osc_thread_kmem;
  extern struct kmem_cache *osc_session_kmem;
  extern struct kmem_cache *osc_extent_kmem;
  
  extern struct lu_device_type osc_device_type;
  extern struct lu_context_key osc_key;
  extern struct lu_context_key osc_session_key;
  
  #define OSC_FLAGS (ASYNC_URGENT | ASYNC_READY)
  
  int osc_lock_init(const struct lu_env *env,
  		  struct cl_object *obj, struct cl_lock *lock,
  		  const struct cl_io *io);
  int osc_io_init(const struct lu_env *env,
  		struct cl_object *obj, struct cl_io *io);
  struct lu_object *osc_object_alloc(const struct lu_env *env,
  				   const struct lu_object_header *hdr,
  				   struct lu_device *dev);
  int osc_page_init(const struct lu_env *env, struct cl_object *obj,
  		  struct cl_page *page, pgoff_t ind);
  
  void osc_index2policy(union ldlm_policy_data *policy,
  		      const struct cl_object *obj,
  		      pgoff_t start, pgoff_t end);
  int osc_lvb_print(const struct lu_env *env, void *cookie,
  		  lu_printer_t p, const struct ost_lvb *lvb);
  
  void osc_lru_add_batch(struct client_obd *cli, struct list_head *list);
  void osc_page_submit(const struct lu_env *env, struct osc_page *opg,
  		     enum cl_req_type crt, int brw_flags);
  int osc_cancel_async_page(const struct lu_env *env, struct osc_page *ops);
  int osc_set_async_flags(struct osc_object *obj, struct osc_page *opg,
  			u32 async_flags);
  int osc_prep_async_page(struct osc_object *osc, struct osc_page *ops,
  			struct page *page, loff_t offset);
  int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
  		       struct osc_page *ops);
  int osc_page_cache_add(const struct lu_env *env,
  		       const struct cl_page_slice *slice, struct cl_io *io);
  int osc_teardown_async_page(const struct lu_env *env, struct osc_object *obj,
  			    struct osc_page *ops);
  int osc_flush_async_page(const struct lu_env *env, struct cl_io *io,
  			 struct osc_page *ops);
  int osc_queue_sync_pages(const struct lu_env *env, struct osc_object *obj,
  			 struct list_head *list, int cmd, int brw_flags);
  int osc_cache_truncate_start(const struct lu_env *env, struct osc_object *obj,
  			     u64 size, struct osc_extent **extp);
  void osc_cache_truncate_end(const struct lu_env *env, struct osc_extent *ext);
  int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
  			      pgoff_t start, pgoff_t end, int hp, int discard);
  int osc_cache_wait_range(const struct lu_env *env, struct osc_object *obj,
  			 pgoff_t start, pgoff_t end);
  void osc_io_unplug(const struct lu_env *env, struct client_obd *cli,
  		   struct osc_object *osc);
  int lru_queue_work(const struct lu_env *env, void *data);
  
  void osc_object_set_contended(struct osc_object *obj);
  void osc_object_clear_contended(struct osc_object *obj);
  int  osc_object_is_contended(struct osc_object *obj);
  
  int  osc_lock_is_lockless(const struct osc_lock *olck);
  
  /*****************************************************************************
   *
   * Accessors.
   *
   */
  
  static inline struct osc_thread_info *osc_env_info(const struct lu_env *env)
  {
  	struct osc_thread_info *info;
  
  	info = lu_context_key_get(&env->le_ctx, &osc_key);
  	LASSERT(info);
  	return info;
  }
  
  static inline struct osc_session *osc_env_session(const struct lu_env *env)
  {
  	struct osc_session *ses;
  
  	ses = lu_context_key_get(env->le_ses, &osc_session_key);
  	LASSERT(ses);
  	return ses;
  }
  
  static inline struct osc_io *osc_env_io(const struct lu_env *env)
  {
  	return &osc_env_session(env)->os_io;
  }
  
  static inline int osc_is_object(const struct lu_object *obj)
  {
  	return obj->lo_dev->ld_type == &osc_device_type;
  }
  
  static inline struct osc_device *lu2osc_dev(const struct lu_device *d)
  {
  	LINVRNT(d->ld_type == &osc_device_type);
  	return container_of0(d, struct osc_device, od_cl.cd_lu_dev);
  }
  
  static inline struct obd_export *osc_export(const struct osc_object *obj)
  {
  	return lu2osc_dev(obj->oo_cl.co_lu.lo_dev)->od_exp;
  }
  
  static inline struct client_obd *osc_cli(const struct osc_object *obj)
  {
  	return &osc_export(obj)->exp_obd->u.cli;
  }
  
  static inline struct osc_object *cl2osc(const struct cl_object *obj)
  {
  	LINVRNT(osc_is_object(&obj->co_lu));
  	return container_of0(obj, struct osc_object, oo_cl);
  }
  
  static inline struct cl_object *osc2cl(const struct osc_object *obj)
  {
  	return (struct cl_object *)&obj->oo_cl;
  }
  
  static inline enum ldlm_mode osc_cl_lock2ldlm(enum cl_lock_mode mode)
  {
  	LASSERT(mode == CLM_READ || mode == CLM_WRITE || mode == CLM_GROUP);
  	if (mode == CLM_READ)
  		return LCK_PR;
  	else if (mode == CLM_WRITE)
  		return LCK_PW;
  	else
  		return LCK_GROUP;
  }
  
  static inline enum cl_lock_mode osc_ldlm2cl_lock(enum ldlm_mode mode)
  {
  	LASSERT(mode == LCK_PR || mode == LCK_PW || mode == LCK_GROUP);
  	if (mode == LCK_PR)
  		return CLM_READ;
  	else if (mode == LCK_PW)
  		return CLM_WRITE;
  	else
  		return CLM_GROUP;
  }
  
  static inline struct osc_page *cl2osc_page(const struct cl_page_slice *slice)
  {
  	LINVRNT(osc_is_object(&slice->cpl_obj->co_lu));
  	return container_of0(slice, struct osc_page, ops_cl);
  }
  
  static inline struct osc_page *oap2osc(struct osc_async_page *oap)
  {
  	return container_of0(oap, struct osc_page, ops_oap);
  }
  
  static inline pgoff_t osc_index(struct osc_page *opg)
  {
  	return opg->ops_cl.cpl_index;
  }
  
  static inline struct cl_page *oap2cl_page(struct osc_async_page *oap)
  {
  	return oap2osc(oap)->ops_cl.cpl_page;
  }
  
  static inline struct osc_page *oap2osc_page(struct osc_async_page *oap)
  {
  	return (struct osc_page *)container_of(oap, struct osc_page, ops_oap);
  }
  
  static inline struct osc_page *
  osc_cl_page_osc(struct cl_page *page, struct osc_object *osc)
  {
  	const struct cl_page_slice *slice;
  
  	LASSERT(osc);
  	slice = cl_object_page_slice(&osc->oo_cl, page);
  	return cl2osc_page(slice);
  }
  
  static inline struct osc_lock *cl2osc_lock(const struct cl_lock_slice *slice)
  {
  	LINVRNT(osc_is_object(&slice->cls_obj->co_lu));
  	return container_of0(slice, struct osc_lock, ols_cl);
  }
  
  static inline struct osc_lock *osc_lock_at(const struct cl_lock *lock)
  {
  	return cl2osc_lock(cl_lock_at(lock, &osc_device_type));
  }
  
  static inline int osc_io_srvlock(struct osc_io *oio)
  {
  	return (oio->oi_lockless && !oio->oi_cl.cis_io->ci_no_srvlock);
  }
  
  enum osc_extent_state {
  	OES_INV       = 0, /** extent is just initialized or destroyed */
  	OES_ACTIVE    = 1, /** process is using this extent */
  	OES_CACHE     = 2, /** extent is ready for IO */
  	OES_LOCKING   = 3, /** locking page to prepare IO */
  	OES_LOCK_DONE = 4, /** locking finished, ready to send */
  	OES_RPC       = 5, /** in RPC */
  	OES_TRUNC     = 6, /** being truncated */
  	OES_STATE_MAX
  };
  
  /**
   * osc_extent data to manage dirty pages.
   * osc_extent has the following attributes:
   * 1. all pages in the same must be in one RPC in write back;
   * 2. # of pages must be less than max_pages_per_rpc - implied by 1;
   * 3. must be covered by only 1 osc_lock;
   * 4. exclusive. It's impossible to have overlapped osc_extent.
   *
   * The lifetime of an extent is from when the 1st page is dirtied to when
   * all pages inside it are written out.
   *
   * LOCKING ORDER
   * =============
   * page lock -> cl_loi_list_lock -> object lock(osc_object::oo_lock)
   */
  struct osc_extent {
  	/** red-black tree node */
  	struct rb_node     oe_node;
  	/** osc_object of this extent */
  	struct osc_object *oe_obj;
  	/** refcount, removed from red-black tree if reaches zero. */
  	atomic_t       oe_refc;
  	/** busy if non-zero */
  	atomic_t       oe_users;
  	/** link list of osc_object's oo_{hp|urgent|locking}_exts. */
  	struct list_head	 oe_link;
  	/** state of this extent */
  	enum osc_extent_state	oe_state;
  	/** flags for this extent. */
  	unsigned int       oe_intree:1,
  	/** 0 is write, 1 is read */
  			   oe_rw:1,
  	/** sync extent, queued by osc_queue_sync_pages() */
  				oe_sync:1,
  	/** set if this extent has partial, sync pages.
  	 * Extents with partial page(s) can't merge with others in RPC
  	 */
  				oe_no_merge:1,
  			   oe_srvlock:1,
  			   oe_memalloc:1,
  	/** an ACTIVE extent is going to be truncated, so when this extent
  	 * is released, it will turn into TRUNC state instead of CACHE.
  	 */
  			   oe_trunc_pending:1,
  	/** this extent should be written asap and someone may wait for the
  	 * write to finish. This bit is usually set along with urgent if
  	 * the extent was CACHE state.
  	 * fsync_wait extent can't be merged because new extent region may
  	 * exceed fsync range.
  	 */
  			   oe_fsync_wait:1,
  	/** covering lock is being canceled */
  			   oe_hp:1,
  	/** this extent should be written back asap. set if one of pages is
  	 * called by page WB daemon, or sync write or reading requests.
  	 */
  			   oe_urgent:1;
  	/** how many grants allocated for this extent.
  	 *  Grant allocated for this extent. There is no grant allocated
  	 *  for reading extents and sync write extents.
  	 */
  	unsigned int       oe_grants;
  	/** # of dirty pages in this extent */
  	unsigned int       oe_nr_pages;
  	/** list of pending oap pages. Pages in this list are NOT sorted. */
  	struct list_head	 oe_pages;
  	/** Since an extent has to be written out in atomic, this is used to
  	 * remember the next page need to be locked to write this extent out.
  	 * Not used right now.
  	 */
  	struct osc_page   *oe_next_page;
  	/** start and end index of this extent, include start and end
  	 * themselves. Page offset here is the page index of osc_pages.
  	 * oe_start is used as keyword for red-black tree.
  	 */
  	pgoff_t	    oe_start;
  	pgoff_t	    oe_end;
  	/** maximum ending index of this extent, this is limited by
  	 * max_pages_per_rpc, lock extent and chunk size.
  	 */
  	pgoff_t	    oe_max_end;
  	/** waitqueue - for those who want to be notified if this extent's
  	 * state has changed.
  	 */
  	wait_queue_head_t	oe_waitq;
  	/** lock covering this extent */
  	struct ldlm_lock	*oe_dlmlock;
  	/** terminator of this extent. Must be true if this extent is in IO. */
  	struct task_struct	*oe_owner;
  	/** return value of writeback. If somebody is waiting for this extent,
  	 * this value can be known by outside world.
  	 */
  	int		oe_rc;
  	/** max pages per rpc when this extent was created */
  	unsigned int       oe_mppr;
  };
  
  int osc_extent_finish(const struct lu_env *env, struct osc_extent *ext,
  		      int sent, int rc);
  void osc_extent_release(const struct lu_env *env, struct osc_extent *ext);
  
  int osc_lock_discard_pages(const struct lu_env *env, struct osc_object *osc,
  			   pgoff_t start, pgoff_t end, enum cl_lock_mode mode);
  
  typedef int (*osc_page_gang_cbt)(const struct lu_env *, struct cl_io *,
  				 struct osc_page *, void *);
  int osc_page_gang_lookup(const struct lu_env *env, struct cl_io *io,
  			 struct osc_object *osc, pgoff_t start, pgoff_t end,
  			 osc_page_gang_cbt cb, void *cbdata);
  /** @} osc */
  
  #endif /* OSC_CL_INTERNAL_H */
  