drivers/staging/lustre/lustre/llite/vvp_page.c - nest-learning-thermostat/5.7.1/linux-imx-ul - Git at Google

 /*
  * 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.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.
  *
  * GPL HEADER END
  */
 /*
  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
  * Copyright (c) 2011, 2012, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
  * Lustre is a trademark of Sun Microsystems, Inc.
  *
  * Implementation of cl_page for VVP layer.
  *
  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  *   Author: Jinshan Xiong <jinshan.xiong@whamcloud.com>
  */

 #define DEBUG_SUBSYSTEM S_LLITE


 #include "../include/obd.h"
 #include "../include/lustre_lite.h"

 #include "vvp_internal.h"

 /*****************************************************************************
  *
  * Page operations.
  *
  */

 static void vvp_page_fini_common(struct ccc_page *cp)
 {
 	struct page *vmpage = cp->cpg_page;

 	LASSERT(vmpage != NULL);
 	page_cache_release(vmpage);
 }

 static void vvp_page_fini(const struct lu_env *env,
 			  struct cl_page_slice *slice)
 {
 	struct ccc_page *cp = cl2ccc_page(slice);
 	struct page *vmpage  = cp->cpg_page;

 	/*
 	 * vmpage->private was already cleared when page was moved into
 	 * VPG_FREEING state.
 	 */
 	LASSERT((struct cl_page *)vmpage->private != slice->cpl_page);
 	vvp_page_fini_common(cp);
 }

 static int vvp_page_own(const struct lu_env *env,
 			const struct cl_page_slice *slice, struct cl_io *io,
 			int nonblock)
 {
 	struct ccc_page *vpg    = cl2ccc_page(slice);
 	struct page      *vmpage = vpg->cpg_page;

 	LASSERT(vmpage != NULL);
 	if (nonblock) {
 		if (!trylock_page(vmpage))
 			return -EAGAIN;

 		if (unlikely(PageWriteback(vmpage))) {
 			unlock_page(vmpage);
 			return -EAGAIN;
 		}

 		return 0;
 	}

 	lock_page(vmpage);
 	wait_on_page_writeback(vmpage);
 	return 0;
 }

 static void vvp_page_assume(const struct lu_env *env,
 			    const struct cl_page_slice *slice,
 			    struct cl_io *unused)
 {
 	struct page *vmpage = cl2vm_page(slice);

 	LASSERT(vmpage != NULL);
 	LASSERT(PageLocked(vmpage));
 	wait_on_page_writeback(vmpage);
 }

 static void vvp_page_unassume(const struct lu_env *env,
 			      const struct cl_page_slice *slice,
 			      struct cl_io *unused)
 {
 	struct page *vmpage = cl2vm_page(slice);

 	LASSERT(vmpage != NULL);
 	LASSERT(PageLocked(vmpage));
 }

 static void vvp_page_disown(const struct lu_env *env,
 			    const struct cl_page_slice *slice, struct cl_io *io)
 {
 	struct page *vmpage = cl2vm_page(slice);

 	LASSERT(vmpage != NULL);
 	LASSERT(PageLocked(vmpage));

 	unlock_page(cl2vm_page(slice));
 }

 static void vvp_page_discard(const struct lu_env *env,
 			     const struct cl_page_slice *slice,
 			     struct cl_io *unused)
 {
 	struct page	   *vmpage  = cl2vm_page(slice);
 	struct address_space *mapping;
 	struct ccc_page      *cpg     = cl2ccc_page(slice);

 	LASSERT(vmpage != NULL);
 	LASSERT(PageLocked(vmpage));

 	mapping = vmpage->mapping;

 	if (cpg->cpg_defer_uptodate && !cpg->cpg_ra_used)
 		ll_ra_stats_inc(mapping, RA_STAT_DISCARDED);

 	/*
 	 * truncate_complete_page() calls
 	 * a_ops->invalidatepage()->cl_page_delete()->vvp_page_delete().
 	 */
 	truncate_complete_page(mapping, vmpage);
 }

 static int vvp_page_unmap(const struct lu_env *env,
 			  const struct cl_page_slice *slice,
 			  struct cl_io *unused)
 {
 	struct page *vmpage = cl2vm_page(slice);
 	__u64       offset;

 	LASSERT(vmpage != NULL);
 	LASSERT(PageLocked(vmpage));

 	offset = vmpage->index << PAGE_CACHE_SHIFT;

 	/*
 	 * XXX is it safe to call this with the page lock held?
 	 */
 	ll_teardown_mmaps(vmpage->mapping, offset, offset + PAGE_CACHE_SIZE);
 	return 0;
 }

 static void vvp_page_delete(const struct lu_env *env,
 			    const struct cl_page_slice *slice)
 {
 	struct page       *vmpage = cl2vm_page(slice);
 	struct inode     *inode  = vmpage->mapping->host;
 	struct cl_object *obj    = slice->cpl_obj;

 	LASSERT(PageLocked(vmpage));
 	LASSERT((struct cl_page *)vmpage->private == slice->cpl_page);
 	LASSERT(inode == ccc_object_inode(obj));

 	vvp_write_complete(cl2ccc(obj), cl2ccc_page(slice));
 	ClearPagePrivate(vmpage);
 	vmpage->private = 0;
 	/*
 	 * Reference from vmpage to cl_page is removed, but the reference back
 	 * is still here. It is removed later in vvp_page_fini().
 	 */
 }

 static void vvp_page_export(const struct lu_env *env,
 			    const struct cl_page_slice *slice,
 			    int uptodate)
 {
 	struct page *vmpage = cl2vm_page(slice);

 	LASSERT(vmpage != NULL);
 	LASSERT(PageLocked(vmpage));
 	if (uptodate)
 		SetPageUptodate(vmpage);
 	else
 		ClearPageUptodate(vmpage);
 }

 static int vvp_page_is_vmlocked(const struct lu_env *env,
 				const struct cl_page_slice *slice)
 {
 	return PageLocked(cl2vm_page(slice)) ? -EBUSY : -ENODATA;
 }

 static int vvp_page_prep_read(const struct lu_env *env,
 			      const struct cl_page_slice *slice,
 			      struct cl_io *unused)
 {
 	/* Skip the page already marked as PG_uptodate. */
 	return PageUptodate(cl2vm_page(slice)) ? -EALREADY : 0;
 }

 static int vvp_page_prep_write(const struct lu_env *env,
 			       const struct cl_page_slice *slice,
 			       struct cl_io *unused)
 {
 	struct page *vmpage = cl2vm_page(slice);

 	LASSERT(PageLocked(vmpage));
 	LASSERT(!PageDirty(vmpage));

 	set_page_writeback(vmpage);
 	vvp_write_pending(cl2ccc(slice->cpl_obj), cl2ccc_page(slice));

 	return 0;
 }

 /**
  * Handles page transfer errors at VM level.
  *
  * This takes inode as a separate argument, because inode on which error is to
  * be set can be different from \a vmpage inode in case of direct-io.
  */
 static void vvp_vmpage_error(struct inode *inode, struct page *vmpage, int ioret)
 {
 	struct ccc_object *obj = cl_inode2ccc(inode);

 	if (ioret == 0) {
 		ClearPageError(vmpage);
 		obj->cob_discard_page_warned = 0;
 	} else {
 		SetPageError(vmpage);
 		if (ioret == -ENOSPC)
 			set_bit(AS_ENOSPC, &inode->i_mapping->flags);
 		else
 			set_bit(AS_EIO, &inode->i_mapping->flags);

 		if ((ioret == -ESHUTDOWN || ioret == -EINTR) &&
 		     obj->cob_discard_page_warned == 0) {
 			obj->cob_discard_page_warned = 1;
 			ll_dirty_page_discard_warn(vmpage, ioret);
 		}
 	}
 }

 static void vvp_page_completion_read(const struct lu_env *env,
 				     const struct cl_page_slice *slice,
 				     int ioret)
 {
 	struct ccc_page *cp     = cl2ccc_page(slice);
 	struct page      *vmpage = cp->cpg_page;
 	struct cl_page  *page   = cl_page_top(slice->cpl_page);
 	struct inode    *inode  = ccc_object_inode(page->cp_obj);

 	LASSERT(PageLocked(vmpage));
 	CL_PAGE_HEADER(D_PAGE, env, page, "completing READ with %d\n", ioret);

 	if (cp->cpg_defer_uptodate)
 		ll_ra_count_put(ll_i2sbi(inode), 1);

 	if (ioret == 0)  {
 		if (!cp->cpg_defer_uptodate)
 			cl_page_export(env, page, 1);
 	} else
 		cp->cpg_defer_uptodate = 0;

 	if (page->cp_sync_io == NULL)
 		unlock_page(vmpage);
 }

 static void vvp_page_completion_write(const struct lu_env *env,
 				      const struct cl_page_slice *slice,
 				      int ioret)
 {
 	struct ccc_page *cp     = cl2ccc_page(slice);
 	struct cl_page  *pg     = slice->cpl_page;
 	struct page      *vmpage = cp->cpg_page;

 	LASSERT(ergo(pg->cp_sync_io != NULL, PageLocked(vmpage)));
 	LASSERT(PageWriteback(vmpage));

 	CL_PAGE_HEADER(D_PAGE, env, pg, "completing WRITE with %d\n", ioret);

 	/*
 	 * TODO: Actually it makes sense to add the page into oap pending
 	 * list again and so that we don't need to take the page out from
 	 * SoM write pending list, if we just meet a recoverable error,
 	 * -ENOMEM, etc.
 	 * To implement this, we just need to return a non zero value in
 	 * ->cpo_completion method. The underlying transfer should be notified
 	 * and then re-add the page into pending transfer queue.  -jay
 	 */

 	cp->cpg_write_queued = 0;
 	vvp_write_complete(cl2ccc(slice->cpl_obj), cp);

 	/*
 	 * Only mark the page error only when it's an async write because
 	 * applications won't wait for IO to finish.
 	 */
 	if (pg->cp_sync_io == NULL)
 		vvp_vmpage_error(ccc_object_inode(pg->cp_obj), vmpage, ioret);

 	end_page_writeback(vmpage);
 }

 /**
  * Implements cl_page_operations::cpo_make_ready() method.
  *
  * This is called to yank a page from the transfer cache and to send it out as
  * a part of transfer. This function try-locks the page. If try-lock failed,
  * page is owned by some concurrent IO, and should be skipped (this is bad,
  * but hopefully rare situation, as it usually results in transfer being
  * shorter than possible).
  *
  * \retval 0      success, page can be placed into transfer
  *
  * \retval -EAGAIN page is either used by concurrent IO has been
  * truncated. Skip it.
  */
 static int vvp_page_make_ready(const struct lu_env *env,
 			       const struct cl_page_slice *slice)
 {
 	struct page *vmpage = cl2vm_page(slice);
 	struct cl_page *pg = slice->cpl_page;
 	int result = 0;

 	lock_page(vmpage);
 	if (clear_page_dirty_for_io(vmpage)) {
 		LASSERT(pg->cp_state == CPS_CACHED);
 		/* This actually clears the dirty bit in the radix
 		 * tree. */
 		set_page_writeback(vmpage);
 		vvp_write_pending(cl2ccc(slice->cpl_obj),
 				cl2ccc_page(slice));
 		CL_PAGE_HEADER(D_PAGE, env, pg, "readied\n");
 	} else if (pg->cp_state == CPS_PAGEOUT) {
 		/* is it possible for osc_flush_async_page() to already
 		 * make it ready? */
 		result = -EALREADY;
 	} else {
 		CL_PAGE_DEBUG(D_ERROR, env, pg, "Unexpecting page state %d.\n",
 			      pg->cp_state);
 		LBUG();
 	}
 	unlock_page(vmpage);
 	return result;
 }

 static int vvp_page_print(const struct lu_env *env,
 			  const struct cl_page_slice *slice,
 			  void *cookie, lu_printer_t printer)
 {
 	struct ccc_page *vp = cl2ccc_page(slice);
 	struct page      *vmpage = vp->cpg_page;

 	(*printer)(env, cookie, LUSTRE_VVP_NAME "-page@%p(%d:%d:%d) vm@%p ",
 		   vp, vp->cpg_defer_uptodate, vp->cpg_ra_used,
 		   vp->cpg_write_queued, vmpage);
 	if (vmpage != NULL) {
 		(*printer)(env, cookie, "%lx %d:%d %lx %lu %slru",
 			   (long)vmpage->flags, page_count(vmpage),
 			   page_mapcount(vmpage), vmpage->private,
 			   page_index(vmpage),
 			   list_empty(&vmpage->lru) ? "not-" : "");
 	}
 	(*printer)(env, cookie, "\n");
 	return 0;
 }

 static const struct cl_page_operations vvp_page_ops = {
 	.cpo_own	   = vvp_page_own,
 	.cpo_assume	= vvp_page_assume,
 	.cpo_unassume      = vvp_page_unassume,
 	.cpo_disown	= vvp_page_disown,
 	.cpo_vmpage	= ccc_page_vmpage,
 	.cpo_discard       = vvp_page_discard,
 	.cpo_delete	= vvp_page_delete,
 	.cpo_unmap	 = vvp_page_unmap,
 	.cpo_export	= vvp_page_export,
 	.cpo_is_vmlocked   = vvp_page_is_vmlocked,
 	.cpo_fini	  = vvp_page_fini,
 	.cpo_print	 = vvp_page_print,
 	.cpo_is_under_lock = ccc_page_is_under_lock,
 	.io = {
 		[CRT_READ] = {
 			.cpo_prep	= vvp_page_prep_read,
 			.cpo_completion  = vvp_page_completion_read,
 			.cpo_make_ready  = ccc_fail,
 		},
 		[CRT_WRITE] = {
 			.cpo_prep	= vvp_page_prep_write,
 			.cpo_completion  = vvp_page_completion_write,
 			.cpo_make_ready  = vvp_page_make_ready,
 		}
 	}
 };

 static void vvp_transient_page_verify(const struct cl_page *page)
 {
 	struct inode *inode = ccc_object_inode(page->cp_obj);

 	LASSERT(!mutex_trylock(&inode->i_mutex));
 }

 static int vvp_transient_page_own(const struct lu_env *env,
 				  const struct cl_page_slice *slice,
 				  struct cl_io *unused, int nonblock)
 {
 	vvp_transient_page_verify(slice->cpl_page);
 	return 0;
 }

 static void vvp_transient_page_assume(const struct lu_env *env,
 				      const struct cl_page_slice *slice,
 				      struct cl_io *unused)
 {
 	vvp_transient_page_verify(slice->cpl_page);
 }

 static void vvp_transient_page_unassume(const struct lu_env *env,
 					const struct cl_page_slice *slice,
 					struct cl_io *unused)
 {
 	vvp_transient_page_verify(slice->cpl_page);
 }

 static void vvp_transient_page_disown(const struct lu_env *env,
 				      const struct cl_page_slice *slice,
 				      struct cl_io *unused)
 {
 	vvp_transient_page_verify(slice->cpl_page);
 }

 static void vvp_transient_page_discard(const struct lu_env *env,
 				       const struct cl_page_slice *slice,
 				       struct cl_io *unused)
 {
 	struct cl_page *page = slice->cpl_page;

 	vvp_transient_page_verify(slice->cpl_page);

 	/*
 	 * For transient pages, remove it from the radix tree.
 	 */
 	cl_page_delete(env, page);
 }

 static int vvp_transient_page_is_vmlocked(const struct lu_env *env,
 					  const struct cl_page_slice *slice)
 {
 	struct inode    *inode = ccc_object_inode(slice->cpl_obj);
 	int	locked;

 	locked = !mutex_trylock(&inode->i_mutex);
 	if (!locked)
 		mutex_unlock(&inode->i_mutex);
 	return locked ? -EBUSY : -ENODATA;
 }

 static void
 vvp_transient_page_completion(const struct lu_env *env,
 			      const struct cl_page_slice *slice,
 			      int ioret)
 {
 	vvp_transient_page_verify(slice->cpl_page);
 }

 static void vvp_transient_page_fini(const struct lu_env *env,
 				    struct cl_page_slice *slice)
 {
 	struct ccc_page *cp = cl2ccc_page(slice);
 	struct cl_page *clp = slice->cpl_page;
 	struct ccc_object *clobj = cl2ccc(clp->cp_obj);

 	vvp_page_fini_common(cp);
 	LASSERT(!mutex_trylock(&clobj->cob_inode->i_mutex));
 	clobj->cob_transient_pages--;
 }

 static const struct cl_page_operations vvp_transient_page_ops = {
 	.cpo_own	   = vvp_transient_page_own,
 	.cpo_assume	= vvp_transient_page_assume,
 	.cpo_unassume      = vvp_transient_page_unassume,
 	.cpo_disown	= vvp_transient_page_disown,
 	.cpo_discard       = vvp_transient_page_discard,
 	.cpo_vmpage	= ccc_page_vmpage,
 	.cpo_fini	  = vvp_transient_page_fini,
 	.cpo_is_vmlocked   = vvp_transient_page_is_vmlocked,
 	.cpo_print	 = vvp_page_print,
 	.cpo_is_under_lock = ccc_page_is_under_lock,
 	.io = {
 		[CRT_READ] = {
 			.cpo_prep	= ccc_transient_page_prep,
 			.cpo_completion  = vvp_transient_page_completion,
 		},
 		[CRT_WRITE] = {
 			.cpo_prep	= ccc_transient_page_prep,
 			.cpo_completion  = vvp_transient_page_completion,
 		}
 	}
 };

 int vvp_page_init(const struct lu_env *env, struct cl_object *obj,
 		struct cl_page *page, struct page *vmpage)
 {
 	struct ccc_page *cpg = cl_object_page_slice(obj, page);

 	CLOBINVRNT(env, obj, ccc_object_invariant(obj));

 	cpg->cpg_page = vmpage;
 	page_cache_get(vmpage);

 	INIT_LIST_HEAD(&cpg->cpg_pending_linkage);
 	if (page->cp_type == CPT_CACHEABLE) {
 		SetPagePrivate(vmpage);
 		vmpage->private = (unsigned long)page;
 		cl_page_slice_add(page, &cpg->cpg_cl, obj,
 				&vvp_page_ops);
 	} else {
 		struct ccc_object *clobj = cl2ccc(obj);

 		LASSERT(!mutex_trylock(&clobj->cob_inode->i_mutex));
 		cl_page_slice_add(page, &cpg->cpg_cl, obj,
 				&vvp_transient_page_ops);
 		clobj->cob_transient_pages++;
 	}
 	return 0;
 }
	/*
	* 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.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.
	*
	* GPL HEADER END
	*/
	/*
	* Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
	* Use is subject to license terms.
	*
	* Copyright (c) 2011, 2012, Intel Corporation.
	*/
	/*
	* This file is part of Lustre, http://www.lustre.org/
	* Lustre is a trademark of Sun Microsystems, Inc.
	*
	* Implementation of cl_page for VVP layer.
	*
	* Author: Nikita Danilov <nikita.danilov@sun.com>
	* Author: Jinshan Xiong <jinshan.xiong@whamcloud.com>
	*/

	#define DEBUG_SUBSYSTEM S_LLITE


	#include "../include/obd.h"
	#include "../include/lustre_lite.h"

	#include "vvp_internal.h"

	/*****************************************************************************
	*
	* Page operations.
	*
	*/

	static void vvp_page_fini_common(struct ccc_page *cp)
	{
	struct page *vmpage = cp->cpg_page;

	LASSERT(vmpage != NULL);
	page_cache_release(vmpage);
	}

	static void vvp_page_fini(const struct lu_env *env,
	struct cl_page_slice *slice)
	{
	struct ccc_page *cp = cl2ccc_page(slice);
	struct page *vmpage = cp->cpg_page;

	/*
	* vmpage->private was already cleared when page was moved into
	* VPG_FREEING state.
	*/
	LASSERT((struct cl_page *)vmpage->private != slice->cpl_page);
	vvp_page_fini_common(cp);
	}

	static int vvp_page_own(const struct lu_env *env,
	const struct cl_page_slice slice, struct cl_io io,
	int nonblock)
	{
	struct ccc_page *vpg = cl2ccc_page(slice);
	struct page *vmpage = vpg->cpg_page;

	LASSERT(vmpage != NULL);
	if (nonblock) {
	if (!trylock_page(vmpage))
	return -EAGAIN;

	if (unlikely(PageWriteback(vmpage))) {
	unlock_page(vmpage);
	return -EAGAIN;
	}

	return 0;
	}

	lock_page(vmpage);
	wait_on_page_writeback(vmpage);
	return 0;
	}

	static void vvp_page_assume(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused)
	{
	struct page *vmpage = cl2vm_page(slice);

	LASSERT(vmpage != NULL);
	LASSERT(PageLocked(vmpage));
	wait_on_page_writeback(vmpage);
	}

	static void vvp_page_unassume(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused)
	{
	struct page *vmpage = cl2vm_page(slice);

	LASSERT(vmpage != NULL);
	LASSERT(PageLocked(vmpage));
	}

	static void vvp_page_disown(const struct lu_env *env,
	const struct cl_page_slice slice, struct cl_io io)
	{
	struct page *vmpage = cl2vm_page(slice);

	LASSERT(vmpage != NULL);
	LASSERT(PageLocked(vmpage));

	unlock_page(cl2vm_page(slice));
	}

	static void vvp_page_discard(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused)
	{
	struct page *vmpage = cl2vm_page(slice);
	struct address_space *mapping;
	struct ccc_page *cpg = cl2ccc_page(slice);

	LASSERT(vmpage != NULL);
	LASSERT(PageLocked(vmpage));

	mapping = vmpage->mapping;

	if (cpg->cpg_defer_uptodate && !cpg->cpg_ra_used)
	ll_ra_stats_inc(mapping, RA_STAT_DISCARDED);

	/*
	* truncate_complete_page() calls
	* a_ops->invalidatepage()->cl_page_delete()->vvp_page_delete().
	*/
	truncate_complete_page(mapping, vmpage);
	}

	static int vvp_page_unmap(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused)
	{
	struct page *vmpage = cl2vm_page(slice);
	__u64 offset;

	LASSERT(vmpage != NULL);
	LASSERT(PageLocked(vmpage));

	offset = vmpage->index << PAGE_CACHE_SHIFT;

	/*
	* XXX is it safe to call this with the page lock held?
	*/
	ll_teardown_mmaps(vmpage->mapping, offset, offset + PAGE_CACHE_SIZE);
	return 0;
	}

	static void vvp_page_delete(const struct lu_env *env,
	const struct cl_page_slice *slice)
	{
	struct page *vmpage = cl2vm_page(slice);
	struct inode *inode = vmpage->mapping->host;
	struct cl_object *obj = slice->cpl_obj;

	LASSERT(PageLocked(vmpage));
	LASSERT((struct cl_page *)vmpage->private == slice->cpl_page);
	LASSERT(inode == ccc_object_inode(obj));

	vvp_write_complete(cl2ccc(obj), cl2ccc_page(slice));
	ClearPagePrivate(vmpage);
	vmpage->private = 0;
	/*
	* Reference from vmpage to cl_page is removed, but the reference back
	* is still here. It is removed later in vvp_page_fini().
	*/
	}

	static void vvp_page_export(const struct lu_env *env,
	const struct cl_page_slice *slice,
	int uptodate)
	{
	struct page *vmpage = cl2vm_page(slice);

	LASSERT(vmpage != NULL);
	LASSERT(PageLocked(vmpage));
	if (uptodate)
	SetPageUptodate(vmpage);
	else
	ClearPageUptodate(vmpage);
	}

	static int vvp_page_is_vmlocked(const struct lu_env *env,
	const struct cl_page_slice *slice)
	{
	return PageLocked(cl2vm_page(slice)) ? -EBUSY : -ENODATA;
	}

	static int vvp_page_prep_read(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused)
	{
	/* Skip the page already marked as PG_uptodate. */
	return PageUptodate(cl2vm_page(slice)) ? -EALREADY : 0;
	}

	static int vvp_page_prep_write(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused)
	{
	struct page *vmpage = cl2vm_page(slice);

	LASSERT(PageLocked(vmpage));
	LASSERT(!PageDirty(vmpage));

	set_page_writeback(vmpage);
	vvp_write_pending(cl2ccc(slice->cpl_obj), cl2ccc_page(slice));

	return 0;
	}

	/**
	* Handles page transfer errors at VM level.
	*
	* This takes inode as a separate argument, because inode on which error is to
	* be set can be different from \a vmpage inode in case of direct-io.
	*/
	static void vvp_vmpage_error(struct inode inode, struct page vmpage, int ioret)
	{
	struct ccc_object *obj = cl_inode2ccc(inode);

	if (ioret == 0) {
	ClearPageError(vmpage);
	obj->cob_discard_page_warned = 0;
	} else {
	SetPageError(vmpage);
	if (ioret == -ENOSPC)
	set_bit(AS_ENOSPC, &inode->i_mapping->flags);
	else
	set_bit(AS_EIO, &inode->i_mapping->flags);

	if ((ioret == -ESHUTDOWN \|\| ioret == -EINTR) &&
	obj->cob_discard_page_warned == 0) {
	obj->cob_discard_page_warned = 1;
	ll_dirty_page_discard_warn(vmpage, ioret);
	}
	}
	}

	static void vvp_page_completion_read(const struct lu_env *env,
	const struct cl_page_slice *slice,
	int ioret)
	{
	struct ccc_page *cp = cl2ccc_page(slice);
	struct page *vmpage = cp->cpg_page;
	struct cl_page *page = cl_page_top(slice->cpl_page);
	struct inode *inode = ccc_object_inode(page->cp_obj);

	LASSERT(PageLocked(vmpage));
	CL_PAGE_HEADER(D_PAGE, env, page, "completing READ with %d\n", ioret);

	if (cp->cpg_defer_uptodate)
	ll_ra_count_put(ll_i2sbi(inode), 1);

	if (ioret == 0) {
	if (!cp->cpg_defer_uptodate)
	cl_page_export(env, page, 1);
	} else
	cp->cpg_defer_uptodate = 0;

	if (page->cp_sync_io == NULL)
	unlock_page(vmpage);
	}

	static void vvp_page_completion_write(const struct lu_env *env,
	const struct cl_page_slice *slice,
	int ioret)
	{
	struct ccc_page *cp = cl2ccc_page(slice);
	struct cl_page *pg = slice->cpl_page;
	struct page *vmpage = cp->cpg_page;

	LASSERT(ergo(pg->cp_sync_io != NULL, PageLocked(vmpage)));
	LASSERT(PageWriteback(vmpage));

	CL_PAGE_HEADER(D_PAGE, env, pg, "completing WRITE with %d\n", ioret);

	/*
	* TODO: Actually it makes sense to add the page into oap pending
	* list again and so that we don't need to take the page out from
	* SoM write pending list, if we just meet a recoverable error,
	* -ENOMEM, etc.
	* To implement this, we just need to return a non zero value in
	* ->cpo_completion method. The underlying transfer should be notified
	* and then re-add the page into pending transfer queue. -jay
	*/

	cp->cpg_write_queued = 0;
	vvp_write_complete(cl2ccc(slice->cpl_obj), cp);

	/*
	* Only mark the page error only when it's an async write because
	* applications won't wait for IO to finish.
	*/
	if (pg->cp_sync_io == NULL)
	vvp_vmpage_error(ccc_object_inode(pg->cp_obj), vmpage, ioret);

	end_page_writeback(vmpage);
	}

	/**
	* Implements cl_page_operations::cpo_make_ready() method.
	*
	* This is called to yank a page from the transfer cache and to send it out as
	* a part of transfer. This function try-locks the page. If try-lock failed,
	* page is owned by some concurrent IO, and should be skipped (this is bad,
	* but hopefully rare situation, as it usually results in transfer being
	* shorter than possible).
	*
	* \retval 0 success, page can be placed into transfer
	*
	* \retval -EAGAIN page is either used by concurrent IO has been
	* truncated. Skip it.
	*/
	static int vvp_page_make_ready(const struct lu_env *env,
	const struct cl_page_slice *slice)
	{
	struct page *vmpage = cl2vm_page(slice);
	struct cl_page *pg = slice->cpl_page;
	int result = 0;

	lock_page(vmpage);
	if (clear_page_dirty_for_io(vmpage)) {
	LASSERT(pg->cp_state == CPS_CACHED);
	/* This actually clears the dirty bit in the radix
	* tree. */
	set_page_writeback(vmpage);
	vvp_write_pending(cl2ccc(slice->cpl_obj),
	cl2ccc_page(slice));
	CL_PAGE_HEADER(D_PAGE, env, pg, "readied\n");
	} else if (pg->cp_state == CPS_PAGEOUT) {
	/* is it possible for osc_flush_async_page() to already
	* make it ready? */
	result = -EALREADY;
	} else {
	CL_PAGE_DEBUG(D_ERROR, env, pg, "Unexpecting page state %d.\n",
	pg->cp_state);
	LBUG();
	}
	unlock_page(vmpage);
	return result;
	}

	static int vvp_page_print(const struct lu_env *env,
	const struct cl_page_slice *slice,
	void *cookie, lu_printer_t printer)
	{
	struct ccc_page *vp = cl2ccc_page(slice);
	struct page *vmpage = vp->cpg_page;

	(*printer)(env, cookie, LUSTRE_VVP_NAME "-page@%p(%d:%d:%d) vm@%p ",
	vp, vp->cpg_defer_uptodate, vp->cpg_ra_used,
	vp->cpg_write_queued, vmpage);
	if (vmpage != NULL) {
	(*printer)(env, cookie, "%lx %d:%d %lx %lu %slru",
	(long)vmpage->flags, page_count(vmpage),
	page_mapcount(vmpage), vmpage->private,
	page_index(vmpage),
	list_empty(&vmpage->lru) ? "not-" : "");
	}
	(*printer)(env, cookie, "\n");
	return 0;
	}

	static const struct cl_page_operations vvp_page_ops = {
	.cpo_own = vvp_page_own,
	.cpo_assume = vvp_page_assume,
	.cpo_unassume = vvp_page_unassume,
	.cpo_disown = vvp_page_disown,
	.cpo_vmpage = ccc_page_vmpage,
	.cpo_discard = vvp_page_discard,
	.cpo_delete = vvp_page_delete,
	.cpo_unmap = vvp_page_unmap,
	.cpo_export = vvp_page_export,
	.cpo_is_vmlocked = vvp_page_is_vmlocked,
	.cpo_fini = vvp_page_fini,
	.cpo_print = vvp_page_print,
	.cpo_is_under_lock = ccc_page_is_under_lock,
	.io = {
	[CRT_READ] = {
	.cpo_prep = vvp_page_prep_read,
	.cpo_completion = vvp_page_completion_read,
	.cpo_make_ready = ccc_fail,
	},
	[CRT_WRITE] = {
	.cpo_prep = vvp_page_prep_write,
	.cpo_completion = vvp_page_completion_write,
	.cpo_make_ready = vvp_page_make_ready,
	}
	}
	};

	static void vvp_transient_page_verify(const struct cl_page *page)
	{
	struct inode *inode = ccc_object_inode(page->cp_obj);

	LASSERT(!mutex_trylock(&inode->i_mutex));
	}

	static int vvp_transient_page_own(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused, int nonblock)
	{
	vvp_transient_page_verify(slice->cpl_page);
	return 0;
	}

	static void vvp_transient_page_assume(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused)
	{
	vvp_transient_page_verify(slice->cpl_page);
	}

	static void vvp_transient_page_unassume(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused)
	{
	vvp_transient_page_verify(slice->cpl_page);
	}

	static void vvp_transient_page_disown(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused)
	{
	vvp_transient_page_verify(slice->cpl_page);
	}

	static void vvp_transient_page_discard(const struct lu_env *env,
	const struct cl_page_slice *slice,
	struct cl_io *unused)
	{
	struct cl_page *page = slice->cpl_page;

	vvp_transient_page_verify(slice->cpl_page);

	/*
	* For transient pages, remove it from the radix tree.
	*/
	cl_page_delete(env, page);
	}

	static int vvp_transient_page_is_vmlocked(const struct lu_env *env,
	const struct cl_page_slice *slice)
	{
	struct inode *inode = ccc_object_inode(slice->cpl_obj);
	int locked;

	locked = !mutex_trylock(&inode->i_mutex);
	if (!locked)
	mutex_unlock(&inode->i_mutex);
	return locked ? -EBUSY : -ENODATA;
	}

	static void
	vvp_transient_page_completion(const struct lu_env *env,
	const struct cl_page_slice *slice,
	int ioret)
	{
	vvp_transient_page_verify(slice->cpl_page);
	}

	static void vvp_transient_page_fini(const struct lu_env *env,
	struct cl_page_slice *slice)
	{
	struct ccc_page *cp = cl2ccc_page(slice);
	struct cl_page *clp = slice->cpl_page;
	struct ccc_object *clobj = cl2ccc(clp->cp_obj);

	vvp_page_fini_common(cp);
	LASSERT(!mutex_trylock(&clobj->cob_inode->i_mutex));
	clobj->cob_transient_pages--;
	}

	static const struct cl_page_operations vvp_transient_page_ops = {
	.cpo_own = vvp_transient_page_own,
	.cpo_assume = vvp_transient_page_assume,
	.cpo_unassume = vvp_transient_page_unassume,
	.cpo_disown = vvp_transient_page_disown,
	.cpo_discard = vvp_transient_page_discard,
	.cpo_vmpage = ccc_page_vmpage,
	.cpo_fini = vvp_transient_page_fini,
	.cpo_is_vmlocked = vvp_transient_page_is_vmlocked,
	.cpo_print = vvp_page_print,
	.cpo_is_under_lock = ccc_page_is_under_lock,
	.io = {
	[CRT_READ] = {
	.cpo_prep = ccc_transient_page_prep,
	.cpo_completion = vvp_transient_page_completion,
	},
	[CRT_WRITE] = {
	.cpo_prep = ccc_transient_page_prep,
	.cpo_completion = vvp_transient_page_completion,
	}
	}
	};

	int vvp_page_init(const struct lu_env env, struct cl_object obj,
	struct cl_page page, struct page vmpage)
	{
	struct ccc_page *cpg = cl_object_page_slice(obj, page);

	CLOBINVRNT(env, obj, ccc_object_invariant(obj));

	cpg->cpg_page = vmpage;
	page_cache_get(vmpage);

	INIT_LIST_HEAD(&cpg->cpg_pending_linkage);
	if (page->cp_type == CPT_CACHEABLE) {
	SetPagePrivate(vmpage);
	vmpage->private = (unsigned long)page;
	cl_page_slice_add(page, &cpg->cpg_cl, obj,
	&vvp_page_ops);
	} else {
	struct ccc_object *clobj = cl2ccc(obj);

	LASSERT(!mutex_trylock(&clobj->cob_inode->i_mutex));
	cl_page_slice_add(page, &cpg->cpg_cl, obj,
	&vvp_transient_page_ops);
	clobj->cob_transient_pages++;
	}
	return 0;
	}