fs/ceph/cache.c - kernel/msm-5.4 - Gitiles

 /*
  * Ceph cache definitions.
  *
  *  Copyright (C) 2013 by Adfin Solutions, Inc. All Rights Reserved.
  *  Written by Milosz Tanski (milosz@adfin.com)
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2
  *  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 for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to:
  *  Free Software Foundation
  *  51 Franklin Street, Fifth Floor
  *  Boston, MA  02111-1301  USA
  *
  */

 #include "super.h"
 #include "cache.h"

 struct ceph_aux_inode {
 	u64 		version;
 	struct timespec	mtime;
 	loff_t          size;
 };

 struct fscache_netfs ceph_cache_netfs = {
 	.name		= "ceph",
 	.version	= 0,
 };

 static DEFINE_MUTEX(ceph_fscache_lock);
 static LIST_HEAD(ceph_fscache_list);

 struct ceph_fscache_entry {
 	struct list_head list;
 	struct fscache_cookie *fscache;
 	struct ceph_fsid fsid;
 	size_t uniq_len;
 	char uniquifier[0];
 };

 static uint16_t ceph_fscache_session_get_key(const void *cookie_netfs_data,
 					     void *buffer, uint16_t maxbuf)
 {
 	const struct ceph_fs_client* fsc = cookie_netfs_data;
 	const char *fscache_uniq = fsc->mount_options->fscache_uniq;
 	uint16_t fsid_len, uniq_len;

 	fsid_len = sizeof(fsc->client->fsid);
 	uniq_len = fscache_uniq ? strlen(fscache_uniq) : 0;
 	if (fsid_len + uniq_len > maxbuf)
 		return 0;

 	memcpy(buffer, &fsc->client->fsid, fsid_len);
 	if (uniq_len)
 		memcpy(buffer + fsid_len, fscache_uniq, uniq_len);

 	return fsid_len + uniq_len;
 }

 static const struct fscache_cookie_def ceph_fscache_fsid_object_def = {
 	.name		= "CEPH.fsid",
 	.type		= FSCACHE_COOKIE_TYPE_INDEX,
 	.get_key	= ceph_fscache_session_get_key,
 };

 int ceph_fscache_register(void)
 {
 	return fscache_register_netfs(&ceph_cache_netfs);
 }

 void ceph_fscache_unregister(void)
 {
 	fscache_unregister_netfs(&ceph_cache_netfs);
 }

 int ceph_fscache_register_fs(struct ceph_fs_client* fsc)
 {
 	const struct ceph_fsid *fsid = &fsc->client->fsid;
 	const char *fscache_uniq = fsc->mount_options->fscache_uniq;
 	size_t uniq_len = fscache_uniq ? strlen(fscache_uniq) : 0;
 	struct ceph_fscache_entry *ent;
 	int err = 0;

 	mutex_lock(&ceph_fscache_lock);
 	list_for_each_entry(ent, &ceph_fscache_list, list) {
 		if (memcmp(&ent->fsid, fsid, sizeof(*fsid)))
 			continue;
 		if (ent->uniq_len != uniq_len)
 			continue;
 		if (uniq_len && memcmp(ent->uniquifier, fscache_uniq, uniq_len))
 			continue;

 		pr_err("fscache cookie already registered for fsid %pU\n", fsid);
 		pr_err("  use fsc=%%s mount option to specify a uniquifier\n");
 		err = -EBUSY;
 		goto out_unlock;
 	}

 	ent = kzalloc(sizeof(*ent) + uniq_len, GFP_KERNEL);
 	if (!ent) {
 		err = -ENOMEM;
 		goto out_unlock;
 	}

 	fsc->fscache = fscache_acquire_cookie(ceph_cache_netfs.primary_index,
 					      &ceph_fscache_fsid_object_def,
 					      fsc, true);

 	if (fsc->fscache) {
 		memcpy(&ent->fsid, fsid, sizeof(*fsid));
 		if (uniq_len > 0) {
 			memcpy(&ent->uniquifier, fscache_uniq, uniq_len);
 			ent->uniq_len = uniq_len;
 		}
 		ent->fscache = fsc->fscache;
 		list_add_tail(&ent->list, &ceph_fscache_list);
 	} else {
 		kfree(ent);
 		pr_err("unable to register fscache cookie for fsid %pU\n",
 		       fsid);
 		/* all other fs ignore this error */
 	}
 out_unlock:
 	mutex_unlock(&ceph_fscache_lock);
 	return err;
 }

 static uint16_t ceph_fscache_inode_get_key(const void *cookie_netfs_data,
 					   void *buffer, uint16_t maxbuf)
 {
 	const struct ceph_inode_info* ci = cookie_netfs_data;
 	uint16_t klen;

 	/* use ceph virtual inode (id + snapshot) */
 	klen = sizeof(ci->i_vino);
 	if (klen > maxbuf)
 		return 0;

 	memcpy(buffer, &ci->i_vino, klen);
 	return klen;
 }

 static uint16_t ceph_fscache_inode_get_aux(const void *cookie_netfs_data,
 					   void *buffer, uint16_t bufmax)
 {
 	struct ceph_aux_inode aux;
 	const struct ceph_inode_info* ci = cookie_netfs_data;
 	const struct inode* inode = &ci->vfs_inode;

 	memset(&aux, 0, sizeof(aux));
 	aux.version = ci->i_version;
 	aux.mtime = inode->i_mtime;
 	aux.size = i_size_read(inode);

 	memcpy(buffer, &aux, sizeof(aux));

 	return sizeof(aux);
 }

 static void ceph_fscache_inode_get_attr(const void *cookie_netfs_data,
 					uint64_t *size)
 {
 	const struct ceph_inode_info* ci = cookie_netfs_data;
 	*size = i_size_read(&ci->vfs_inode);
 }

 static enum fscache_checkaux ceph_fscache_inode_check_aux(
 	void *cookie_netfs_data, const void *data, uint16_t dlen)
 {
 	struct ceph_aux_inode aux;
 	struct ceph_inode_info* ci = cookie_netfs_data;
 	struct inode* inode = &ci->vfs_inode;

 	if (dlen != sizeof(aux))
 		return FSCACHE_CHECKAUX_OBSOLETE;

 	memset(&aux, 0, sizeof(aux));
 	aux.version = ci->i_version;
 	aux.mtime = inode->i_mtime;
 	aux.size = i_size_read(inode);

 	if (memcmp(data, &aux, sizeof(aux)) != 0)
 		return FSCACHE_CHECKAUX_OBSOLETE;

 	dout("ceph inode 0x%p cached okay", ci);
 	return FSCACHE_CHECKAUX_OKAY;
 }

 static void ceph_fscache_inode_now_uncached(void* cookie_netfs_data)
 {
 	struct ceph_inode_info* ci = cookie_netfs_data;
 	struct pagevec pvec;
 	pgoff_t first;
 	int loop, nr_pages;

 	pagevec_init(&pvec, 0);
 	first = 0;

 	dout("ceph inode 0x%p now uncached", ci);

 	while (1) {
 		nr_pages = pagevec_lookup(&pvec, ci->vfs_inode.i_mapping, first,
 					  PAGEVEC_SIZE - pagevec_count(&pvec));

 		if (!nr_pages)
 			break;

 		for (loop = 0; loop < nr_pages; loop++)
 			ClearPageFsCache(pvec.pages[loop]);

 		first = pvec.pages[nr_pages - 1]->index + 1;

 		pvec.nr = nr_pages;
 		pagevec_release(&pvec);
 		cond_resched();
 	}
 }

 static const struct fscache_cookie_def ceph_fscache_inode_object_def = {
 	.name		= "CEPH.inode",
 	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
 	.get_key	= ceph_fscache_inode_get_key,
 	.get_attr	= ceph_fscache_inode_get_attr,
 	.get_aux	= ceph_fscache_inode_get_aux,
 	.check_aux	= ceph_fscache_inode_check_aux,
 	.now_uncached	= ceph_fscache_inode_now_uncached,
 };

 void ceph_fscache_register_inode_cookie(struct inode *inode)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);

 	/* No caching for filesystem */
 	if (fsc->fscache == NULL)
 		return;

 	/* Only cache for regular files that are read only */
 	if (!S_ISREG(inode->i_mode))
 		return;

 	inode_lock_nested(inode, I_MUTEX_CHILD);
 	if (!ci->fscache) {
 		ci->fscache = fscache_acquire_cookie(fsc->fscache,
 					&ceph_fscache_inode_object_def,
 					ci, false);
 	}
 	inode_unlock(inode);
 }

 void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci)
 {
 	struct fscache_cookie* cookie;

 	if ((cookie = ci->fscache) == NULL)
 		return;

 	ci->fscache = NULL;

 	fscache_uncache_all_inode_pages(cookie, &ci->vfs_inode);
 	fscache_relinquish_cookie(cookie, 0);
 }

 static bool ceph_fscache_can_enable(void *data)
 {
 	struct inode *inode = data;
 	return !inode_is_open_for_write(inode);
 }

 void ceph_fscache_file_set_cookie(struct inode *inode, struct file *filp)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);

 	if (!fscache_cookie_valid(ci->fscache))
 		return;

 	if (inode_is_open_for_write(inode)) {
 		dout("fscache_file_set_cookie %p %p disabling cache\n",
 		     inode, filp);
 		fscache_disable_cookie(ci->fscache, false);
 		fscache_uncache_all_inode_pages(ci->fscache, inode);
 	} else {
 		fscache_enable_cookie(ci->fscache, ceph_fscache_can_enable,
 				inode);
 		if (fscache_cookie_enabled(ci->fscache)) {
 			dout("fscache_file_set_cookie %p %p enabling cache\n",
 			     inode, filp);
 		}
 	}
 }

 static void ceph_vfs_readpage_complete(struct page *page, void *data, int error)
 {
 	if (!error)
 		SetPageUptodate(page);
 }

 static void ceph_vfs_readpage_complete_unlock(struct page *page, void *data, int error)
 {
 	if (!error)
 		SetPageUptodate(page);

 	unlock_page(page);
 }

 static inline bool cache_valid(struct ceph_inode_info *ci)
 {
 	return ci->i_fscache_gen == ci->i_rdcache_gen;
 }


 /* Atempt to read from the fscache,
  *
  * This function is called from the readpage_nounlock context. DO NOT attempt to
  * unlock the page here (or in the callback).
  */
 int ceph_readpage_from_fscache(struct inode *inode, struct page *page)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	int ret;

 	if (!cache_valid(ci))
 		return -ENOBUFS;

 	ret = fscache_read_or_alloc_page(ci->fscache, page,
 					 ceph_vfs_readpage_complete, NULL,
 					 GFP_KERNEL);

 	switch (ret) {
 		case 0: /* Page found */
 			dout("page read submitted\n");
 			return 0;
 		case -ENOBUFS: /* Pages were not found, and can't be */
 		case -ENODATA: /* Pages were not found */
 			dout("page/inode not in cache\n");
 			return ret;
 		default:
 			dout("%s: unknown error ret = %i\n", __func__, ret);
 			return ret;
 	}
 }

 int ceph_readpages_from_fscache(struct inode *inode,
 				  struct address_space *mapping,
 				  struct list_head *pages,
 				  unsigned *nr_pages)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	int ret;

 	if (!cache_valid(ci))
 		return -ENOBUFS;

 	ret = fscache_read_or_alloc_pages(ci->fscache, mapping, pages, nr_pages,
 					  ceph_vfs_readpage_complete_unlock,
 					  NULL, mapping_gfp_mask(mapping));

 	switch (ret) {
 		case 0: /* All pages found */
 			dout("all-page read submitted\n");
 			return 0;
 		case -ENOBUFS: /* Some pages were not found, and can't be */
 		case -ENODATA: /* some pages were not found */
 			dout("page/inode not in cache\n");
 			return ret;
 		default:
 			dout("%s: unknown error ret = %i\n", __func__, ret);
 			return ret;
 	}
 }

 void ceph_readpage_to_fscache(struct inode *inode, struct page *page)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	int ret;

 	if (!PageFsCache(page))
 		return;

 	if (!cache_valid(ci))
 		return;

 	ret = fscache_write_page(ci->fscache, page, GFP_KERNEL);
 	if (ret)
 		 fscache_uncache_page(ci->fscache, page);
 }

 void ceph_invalidate_fscache_page(struct inode* inode, struct page *page)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);

 	if (!PageFsCache(page))
 		return;

 	fscache_wait_on_page_write(ci->fscache, page);
 	fscache_uncache_page(ci->fscache, page);
 }

 void ceph_fscache_unregister_fs(struct ceph_fs_client* fsc)
 {
 	if (fscache_cookie_valid(fsc->fscache)) {
 		struct ceph_fscache_entry *ent;
 		bool found = false;

 		mutex_lock(&ceph_fscache_lock);
 		list_for_each_entry(ent, &ceph_fscache_list, list) {
 			if (ent->fscache == fsc->fscache) {
 				list_del(&ent->list);
 				kfree(ent);
 				found = true;
 				break;
 			}
 		}
 		WARN_ON_ONCE(!found);
 		mutex_unlock(&ceph_fscache_lock);

 		__fscache_relinquish_cookie(fsc->fscache, 0);
 	}
 	fsc->fscache = NULL;
 }

 /*
  * caller should hold CEPH_CAP_FILE_{RD,CACHE}
  */
 void ceph_fscache_revalidate_cookie(struct ceph_inode_info *ci)
 {
 	if (cache_valid(ci))
 		return;

 	/* resue i_truncate_mutex. There should be no pending
 	 * truncate while the caller holds CEPH_CAP_FILE_RD */
 	mutex_lock(&ci->i_truncate_mutex);
 	if (!cache_valid(ci)) {
 		if (fscache_check_consistency(ci->fscache))
 			fscache_invalidate(ci->fscache);
 		spin_lock(&ci->i_ceph_lock);
 		ci->i_fscache_gen = ci->i_rdcache_gen;
 		spin_unlock(&ci->i_ceph_lock);
 	}
 	mutex_unlock(&ci->i_truncate_mutex);
 }
	/*
	* Ceph cache definitions.
	*
	* Copyright (C) 2013 by Adfin Solutions, Inc. All Rights Reserved.
	* Written by Milosz Tanski (milosz@adfin.com)
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2
	* 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 for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to:
	* Free Software Foundation
	* 51 Franklin Street, Fifth Floor
	* Boston, MA 02111-1301 USA
	*
	*/

	#include "super.h"
	#include "cache.h"

	struct ceph_aux_inode {
	u64 version;
	struct timespec mtime;
	loff_t size;
	};

	struct fscache_netfs ceph_cache_netfs = {
	.name = "ceph",
	.version = 0,
	};

	static DEFINE_MUTEX(ceph_fscache_lock);
	static LIST_HEAD(ceph_fscache_list);

	struct ceph_fscache_entry {
	struct list_head list;
	struct fscache_cookie *fscache;
	struct ceph_fsid fsid;
	size_t uniq_len;
	char uniquifier[0];
	};

	static uint16_t ceph_fscache_session_get_key(const void *cookie_netfs_data,
	void *buffer, uint16_t maxbuf)
	{
	const struct ceph_fs_client* fsc = cookie_netfs_data;
	const char *fscache_uniq = fsc->mount_options->fscache_uniq;
	uint16_t fsid_len, uniq_len;

	fsid_len = sizeof(fsc->client->fsid);
	uniq_len = fscache_uniq ? strlen(fscache_uniq) : 0;
	if (fsid_len + uniq_len > maxbuf)
	return 0;

	memcpy(buffer, &fsc->client->fsid, fsid_len);
	if (uniq_len)
	memcpy(buffer + fsid_len, fscache_uniq, uniq_len);

	return fsid_len + uniq_len;
	}

	static const struct fscache_cookie_def ceph_fscache_fsid_object_def = {
	.name = "CEPH.fsid",
	.type = FSCACHE_COOKIE_TYPE_INDEX,
	.get_key = ceph_fscache_session_get_key,
	};

	int ceph_fscache_register(void)
	{
	return fscache_register_netfs(&ceph_cache_netfs);
	}

	void ceph_fscache_unregister(void)
	{
	fscache_unregister_netfs(&ceph_cache_netfs);
	}

	int ceph_fscache_register_fs(struct ceph_fs_client* fsc)
	{
	const struct ceph_fsid *fsid = &fsc->client->fsid;
	const char *fscache_uniq = fsc->mount_options->fscache_uniq;
	size_t uniq_len = fscache_uniq ? strlen(fscache_uniq) : 0;
	struct ceph_fscache_entry *ent;
	int err = 0;

	mutex_lock(&ceph_fscache_lock);
	list_for_each_entry(ent, &ceph_fscache_list, list) {
	if (memcmp(&ent->fsid, fsid, sizeof(*fsid)))
	continue;
	if (ent->uniq_len != uniq_len)
	continue;
	if (uniq_len && memcmp(ent->uniquifier, fscache_uniq, uniq_len))
	continue;

	pr_err("fscache cookie already registered for fsid %pU\n", fsid);
	pr_err(" use fsc=%%s mount option to specify a uniquifier\n");
	err = -EBUSY;
	goto out_unlock;
	}

	ent = kzalloc(sizeof(*ent) + uniq_len, GFP_KERNEL);
	if (!ent) {
	err = -ENOMEM;
	goto out_unlock;
	}

	fsc->fscache = fscache_acquire_cookie(ceph_cache_netfs.primary_index,
	&ceph_fscache_fsid_object_def,
	fsc, true);

	if (fsc->fscache) {
	memcpy(&ent->fsid, fsid, sizeof(*fsid));
	if (uniq_len > 0) {
	memcpy(&ent->uniquifier, fscache_uniq, uniq_len);
	ent->uniq_len = uniq_len;
	}
	ent->fscache = fsc->fscache;
	list_add_tail(&ent->list, &ceph_fscache_list);
	} else {
	kfree(ent);
	pr_err("unable to register fscache cookie for fsid %pU\n",
	fsid);
	/* all other fs ignore this error */
	}
	out_unlock:
	mutex_unlock(&ceph_fscache_lock);
	return err;
	}

	static uint16_t ceph_fscache_inode_get_key(const void *cookie_netfs_data,
	void *buffer, uint16_t maxbuf)
	{
	const struct ceph_inode_info* ci = cookie_netfs_data;
	uint16_t klen;

	/* use ceph virtual inode (id + snapshot) */
	klen = sizeof(ci->i_vino);
	if (klen > maxbuf)
	return 0;

	memcpy(buffer, &ci->i_vino, klen);
	return klen;
	}

	static uint16_t ceph_fscache_inode_get_aux(const void *cookie_netfs_data,
	void *buffer, uint16_t bufmax)
	{
	struct ceph_aux_inode aux;
	const struct ceph_inode_info* ci = cookie_netfs_data;
	const struct inode* inode = &ci->vfs_inode;

	memset(&aux, 0, sizeof(aux));
	aux.version = ci->i_version;
	aux.mtime = inode->i_mtime;
	aux.size = i_size_read(inode);

	memcpy(buffer, &aux, sizeof(aux));

	return sizeof(aux);
	}

	static void ceph_fscache_inode_get_attr(const void *cookie_netfs_data,
	uint64_t *size)
	{
	const struct ceph_inode_info* ci = cookie_netfs_data;
	*size = i_size_read(&ci->vfs_inode);
	}

	static enum fscache_checkaux ceph_fscache_inode_check_aux(
	void cookie_netfs_data, const void data, uint16_t dlen)
	{
	struct ceph_aux_inode aux;
	struct ceph_inode_info* ci = cookie_netfs_data;
	struct inode* inode = &ci->vfs_inode;

	if (dlen != sizeof(aux))
	return FSCACHE_CHECKAUX_OBSOLETE;

	memset(&aux, 0, sizeof(aux));
	aux.version = ci->i_version;
	aux.mtime = inode->i_mtime;
	aux.size = i_size_read(inode);

	if (memcmp(data, &aux, sizeof(aux)) != 0)
	return FSCACHE_CHECKAUX_OBSOLETE;

	dout("ceph inode 0x%p cached okay", ci);
	return FSCACHE_CHECKAUX_OKAY;
	}

	static void ceph_fscache_inode_now_uncached(void* cookie_netfs_data)
	{
	struct ceph_inode_info* ci = cookie_netfs_data;
	struct pagevec pvec;
	pgoff_t first;
	int loop, nr_pages;

	pagevec_init(&pvec, 0);
	first = 0;

	dout("ceph inode 0x%p now uncached", ci);

	while (1) {
	nr_pages = pagevec_lookup(&pvec, ci->vfs_inode.i_mapping, first,
	PAGEVEC_SIZE - pagevec_count(&pvec));

	if (!nr_pages)
	break;

	for (loop = 0; loop < nr_pages; loop++)
	ClearPageFsCache(pvec.pages[loop]);

	first = pvec.pages[nr_pages - 1]->index + 1;

	pvec.nr = nr_pages;
	pagevec_release(&pvec);
	cond_resched();
	}
	}

	static const struct fscache_cookie_def ceph_fscache_inode_object_def = {
	.name = "CEPH.inode",
	.type = FSCACHE_COOKIE_TYPE_DATAFILE,
	.get_key = ceph_fscache_inode_get_key,
	.get_attr = ceph_fscache_inode_get_attr,
	.get_aux = ceph_fscache_inode_get_aux,
	.check_aux = ceph_fscache_inode_check_aux,
	.now_uncached = ceph_fscache_inode_now_uncached,
	};

	void ceph_fscache_register_inode_cookie(struct inode *inode)
	{
	struct ceph_inode_info *ci = ceph_inode(inode);
	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);

	/* No caching for filesystem */
	if (fsc->fscache == NULL)
	return;

	/* Only cache for regular files that are read only */
	if (!S_ISREG(inode->i_mode))
	return;

	inode_lock_nested(inode, I_MUTEX_CHILD);
	if (!ci->fscache) {
	ci->fscache = fscache_acquire_cookie(fsc->fscache,
	&ceph_fscache_inode_object_def,
	ci, false);
	}
	inode_unlock(inode);
	}

	void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci)
	{
	struct fscache_cookie* cookie;

	if ((cookie = ci->fscache) == NULL)
	return;

	ci->fscache = NULL;

	fscache_uncache_all_inode_pages(cookie, &ci->vfs_inode);
	fscache_relinquish_cookie(cookie, 0);
	}

	static bool ceph_fscache_can_enable(void *data)
	{
	struct inode *inode = data;
	return !inode_is_open_for_write(inode);
	}

	void ceph_fscache_file_set_cookie(struct inode inode, struct file filp)
	{
	struct ceph_inode_info *ci = ceph_inode(inode);

	if (!fscache_cookie_valid(ci->fscache))
	return;

	if (inode_is_open_for_write(inode)) {
	dout("fscache_file_set_cookie %p %p disabling cache\n",
	inode, filp);
	fscache_disable_cookie(ci->fscache, false);
	fscache_uncache_all_inode_pages(ci->fscache, inode);
	} else {
	fscache_enable_cookie(ci->fscache, ceph_fscache_can_enable,
	inode);
	if (fscache_cookie_enabled(ci->fscache)) {
	dout("fscache_file_set_cookie %p %p enabling cache\n",
	inode, filp);
	}
	}
	}

	static void ceph_vfs_readpage_complete(struct page page, void data, int error)
	{
	if (!error)
	SetPageUptodate(page);
	}

	static void ceph_vfs_readpage_complete_unlock(struct page page, void data, int error)
	{
	if (!error)
	SetPageUptodate(page);

	unlock_page(page);
	}

	static inline bool cache_valid(struct ceph_inode_info *ci)
	{
	return ci->i_fscache_gen == ci->i_rdcache_gen;
	}


	/* Atempt to read from the fscache,
	*
	* This function is called from the readpage_nounlock context. DO NOT attempt to
	* unlock the page here (or in the callback).
	*/
	int ceph_readpage_from_fscache(struct inode inode, struct page page)
	{
	struct ceph_inode_info *ci = ceph_inode(inode);
	int ret;

	if (!cache_valid(ci))
	return -ENOBUFS;

	ret = fscache_read_or_alloc_page(ci->fscache, page,
	ceph_vfs_readpage_complete, NULL,
	GFP_KERNEL);

	switch (ret) {
	case 0: /* Page found */
	dout("page read submitted\n");
	return 0;
	case -ENOBUFS: /* Pages were not found, and can't be */
	case -ENODATA: /* Pages were not found */
	dout("page/inode not in cache\n");
	return ret;
	default:
	dout("%s: unknown error ret = %i\n", __func__, ret);
	return ret;
	}
	}

	int ceph_readpages_from_fscache(struct inode *inode,
	struct address_space *mapping,
	struct list_head *pages,
	unsigned *nr_pages)
	{
	struct ceph_inode_info *ci = ceph_inode(inode);
	int ret;

	if (!cache_valid(ci))
	return -ENOBUFS;

	ret = fscache_read_or_alloc_pages(ci->fscache, mapping, pages, nr_pages,
	ceph_vfs_readpage_complete_unlock,
	NULL, mapping_gfp_mask(mapping));

	switch (ret) {
	case 0: /* All pages found */
	dout("all-page read submitted\n");
	return 0;
	case -ENOBUFS: /* Some pages were not found, and can't be */
	case -ENODATA: /* some pages were not found */
	dout("page/inode not in cache\n");
	return ret;
	default:
	dout("%s: unknown error ret = %i\n", __func__, ret);
	return ret;
	}
	}

	void ceph_readpage_to_fscache(struct inode inode, struct page page)
	{
	struct ceph_inode_info *ci = ceph_inode(inode);
	int ret;

	if (!PageFsCache(page))
	return;

	if (!cache_valid(ci))
	return;

	ret = fscache_write_page(ci->fscache, page, GFP_KERNEL);
	if (ret)
	fscache_uncache_page(ci->fscache, page);
	}

	void ceph_invalidate_fscache_page(struct inode* inode, struct page *page)
	{
	struct ceph_inode_info *ci = ceph_inode(inode);

	if (!PageFsCache(page))
	return;

	fscache_wait_on_page_write(ci->fscache, page);
	fscache_uncache_page(ci->fscache, page);
	}

	void ceph_fscache_unregister_fs(struct ceph_fs_client* fsc)
	{
	if (fscache_cookie_valid(fsc->fscache)) {
	struct ceph_fscache_entry *ent;
	bool found = false;

	mutex_lock(&ceph_fscache_lock);
	list_for_each_entry(ent, &ceph_fscache_list, list) {
	if (ent->fscache == fsc->fscache) {
	list_del(&ent->list);
	kfree(ent);
	found = true;
	break;
	}
	}
	WARN_ON_ONCE(!found);
	mutex_unlock(&ceph_fscache_lock);

	__fscache_relinquish_cookie(fsc->fscache, 0);
	}
	fsc->fscache = NULL;
	}

	/*
	* caller should hold CEPH_CAP_FILE_{RD,CACHE}
	*/
	void ceph_fscache_revalidate_cookie(struct ceph_inode_info *ci)
	{
	if (cache_valid(ci))
	return;

	/* resue i_truncate_mutex. There should be no pending
	* truncate while the caller holds CEPH_CAP_FILE_RD */
	mutex_lock(&ci->i_truncate_mutex);
	if (!cache_valid(ci)) {
	if (fscache_check_consistency(ci->fscache))
	fscache_invalidate(ci->fscache);
	spin_lock(&ci->i_ceph_lock);
	ci->i_fscache_gen = ci->i_rdcache_gen;
	spin_unlock(&ci->i_ceph_lock);
	}
	mutex_unlock(&ci->i_truncate_mutex);
	}