[mirror_ubuntu-artful-kernel.git] / fs / nfs / fscache.c

/* NFS filesystem cache interface
 *
 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/in6.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

#include "internal.h"
#include "iostat.h"
#include "fscache.h"

#define NFSDBG_FACILITY		NFSDBG_FSCACHE

static struct rb_root nfs_fscache_keys = RB_ROOT;
static DEFINE_SPINLOCK(nfs_fscache_keys_lock);

/*
 * Get the per-client index cookie for an NFS client if the appropriate mount
 * flag was set
 * - We always try and get an index cookie for the client, but get filehandle
 *   cookies on a per-superblock basis, depending on the mount flags
 */
void nfs_fscache_get_client_cookie(struct nfs_client *clp)
{
	/* create a cache index for looking up filehandles */
	clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
					      &nfs_fscache_server_index_def,
					      clp, true);
	dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
		 clp, clp->fscache);
}

/*
 * Dispose of a per-client cookie
 */
void nfs_fscache_release_client_cookie(struct nfs_client *clp)
{
	dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
		 clp, clp->fscache);

	fscache_relinquish_cookie(clp->fscache, 0);
	clp->fscache = NULL;
}

/*
 * Get the cache cookie for an NFS superblock.  We have to handle
 * uniquification here because the cache doesn't do it for us.
 *
 * The default uniquifier is just an empty string, but it may be overridden
 * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
 * superblock across an automount point of some nature.
 */
void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
{
	struct nfs_fscache_key *key, *xkey;
	struct nfs_server *nfss = NFS_SB(sb);
	struct rb_node **p, *parent;
	int diff;

	if (!uniq) {
		uniq = "";
		ulen = 1;
	}

	key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
	if (!key)
		return;

	key->nfs_client = nfss->nfs_client;
	key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
	key->key.nfs_server.flags = nfss->flags;
	key->key.nfs_server.rsize = nfss->rsize;
	key->key.nfs_server.wsize = nfss->wsize;
	key->key.nfs_server.acregmin = nfss->acregmin;
	key->key.nfs_server.acregmax = nfss->acregmax;
	key->key.nfs_server.acdirmin = nfss->acdirmin;
	key->key.nfs_server.acdirmax = nfss->acdirmax;
	key->key.nfs_server.fsid = nfss->fsid;
	key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;

	key->key.uniq_len = ulen;
	memcpy(key->key.uniquifier, uniq, ulen);

	spin_lock(&nfs_fscache_keys_lock);
	p = &nfs_fscache_keys.rb_node;
	parent = NULL;
	while (*p) {
		parent = *p;
		xkey = rb_entry(parent, struct nfs_fscache_key, node);

		if (key->nfs_client < xkey->nfs_client)
			goto go_left;
		if (key->nfs_client > xkey->nfs_client)
			goto go_right;

		diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
		if (diff < 0)
			goto go_left;
		if (diff > 0)
			goto go_right;

		if (key->key.uniq_len == 0)
			goto non_unique;
		diff = memcmp(key->key.uniquifier,
			      xkey->key.uniquifier,
			      key->key.uniq_len);
		if (diff < 0)
			goto go_left;
		if (diff > 0)
			goto go_right;
		goto non_unique;

	go_left:
		p = &(*p)->rb_left;
		continue;
	go_right:
		p = &(*p)->rb_right;
	}

	rb_link_node(&key->node, parent, p);
	rb_insert_color(&key->node, &nfs_fscache_keys);
	spin_unlock(&nfs_fscache_keys_lock);
	nfss->fscache_key = key;

	/* create a cache index for looking up filehandles */
	nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
					       &nfs_fscache_super_index_def,
					       nfss, true);
	dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
		 nfss, nfss->fscache);
	return;

non_unique:
	spin_unlock(&nfs_fscache_keys_lock);
	kfree(key);
	nfss->fscache_key = NULL;
	nfss->fscache = NULL;
	printk(KERN_WARNING "NFS:"
	       " Cache request denied due to non-unique superblock keys\n");
}

/*
 * release a per-superblock cookie
 */
void nfs_fscache_release_super_cookie(struct super_block *sb)
{
	struct nfs_server *nfss = NFS_SB(sb);

	dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
		 nfss, nfss->fscache);

	fscache_relinquish_cookie(nfss->fscache, 0);
	nfss->fscache = NULL;

	if (nfss->fscache_key) {
		spin_lock(&nfs_fscache_keys_lock);
		rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
		spin_unlock(&nfs_fscache_keys_lock);
		kfree(nfss->fscache_key);
		nfss->fscache_key = NULL;
	}
}

/*
 * Initialise the per-inode cache cookie pointer for an NFS inode.
 */
void nfs_fscache_init_inode(struct inode *inode)
{
	struct nfs_inode *nfsi = NFS_I(inode);

	nfsi->fscache = NULL;
	if (!S_ISREG(inode->i_mode))
		return;
	nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
					       &nfs_fscache_inode_object_def,
					       nfsi, false);
}

/*
 * Release a per-inode cookie.
 */
void nfs_fscache_clear_inode(struct inode *inode)
{
	struct nfs_inode *nfsi = NFS_I(inode);
	struct fscache_cookie *cookie = nfs_i_fscache(inode);

	dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);

	fscache_relinquish_cookie(cookie, false);
	nfsi->fscache = NULL;
}

static bool nfs_fscache_can_enable(void *data)
{
	struct inode *inode = data;

	return !inode_is_open_for_write(inode);
}

/*
 * Enable or disable caching for a file that is being opened as appropriate.
 * The cookie is allocated when the inode is initialised, but is not enabled at
 * that time.  Enablement is deferred to file-open time to avoid stat() and
 * access() thrashing the cache.
 *
 * For now, with NFS, only regular files that are open read-only will be able
 * to use the cache.
 *
 * We enable the cache for an inode if we open it read-only and it isn't
 * currently open for writing.  We disable the cache if the inode is open
 * write-only.
 *
 * The caller uses the file struct to pin i_writecount on the inode before
 * calling us when a file is opened for writing, so we can make use of that.
 *
 * Note that this may be invoked multiple times in parallel by parallel
 * nfs_open() functions.
 */
void nfs_fscache_open_file(struct inode *inode, struct file *filp)
{
	struct nfs_inode *nfsi = NFS_I(inode);
	struct fscache_cookie *cookie = nfs_i_fscache(inode);

	if (!fscache_cookie_valid(cookie))
		return;

	if (inode_is_open_for_write(inode)) {
		dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);
		clear_bit(NFS_INO_FSCACHE, &nfsi->flags);
		fscache_disable_cookie(cookie, true);
		fscache_uncache_all_inode_pages(cookie, inode);
	} else {
		dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi);
		fscache_enable_cookie(cookie, nfs_fscache_can_enable, inode);
		if (fscache_cookie_enabled(cookie))
			set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
	}
}
EXPORT_SYMBOL_GPL(nfs_fscache_open_file);

/*
 * Release the caching state associated with a page, if the page isn't busy
 * interacting with the cache.
 * - Returns true (can release page) or false (page busy).
 */
int nfs_fscache_release_page(struct page *page, gfp_t gfp)
{
	if (PageFsCache(page)) {
		struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);

		BUG_ON(!cookie);
		dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
			 cookie, page, NFS_I(page->mapping->host));

		if (!fscache_maybe_release_page(cookie, page, gfp))
			return 0;

		nfs_inc_fscache_stats(page->mapping->host,
				      NFSIOS_FSCACHE_PAGES_UNCACHED);
	}

	return 1;
}

/*
 * Release the caching state associated with a page if undergoing complete page
 * invalidation.
 */
void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
{
	struct fscache_cookie *cookie = nfs_i_fscache(inode);

	BUG_ON(!cookie);

	dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
		 cookie, page, NFS_I(inode));

	fscache_wait_on_page_write(cookie, page);

	BUG_ON(!PageLocked(page));
	fscache_uncache_page(cookie, page);
	nfs_inc_fscache_stats(page->mapping->host,
			      NFSIOS_FSCACHE_PAGES_UNCACHED);
}

/*
 * Handle completion of a page being read from the cache.
 * - Called in process (keventd) context.
 */
static void nfs_readpage_from_fscache_complete(struct page *page,
					       void *context,
					       int error)
{
	dfprintk(FSCACHE,
		 "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
		 page, context, error);

	/* if the read completes with an error, we just unlock the page and let
	 * the VM reissue the readpage */
	if (!error) {
		SetPageUptodate(page);
		unlock_page(page);
	} else {
		error = nfs_readpage_async(context, page->mapping->host, page);
		if (error)
			unlock_page(page);
	}
}

/*
 * Retrieve a page from fscache
 */
int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
				struct inode *inode, struct page *page)
{
	int ret;

	dfprintk(FSCACHE,
		 "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
		 nfs_i_fscache(inode), page, page->index, page->flags, inode);

	ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
					 page,
					 nfs_readpage_from_fscache_complete,
					 ctx,
					 GFP_KERNEL);

	switch (ret) {
	case 0: /* read BIO submitted (page in fscache) */
		dfprintk(FSCACHE,
			 "NFS:    readpage_from_fscache: BIO submitted\n");
		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
		return ret;

	case -ENOBUFS: /* inode not in cache */
	case -ENODATA: /* page not in cache */
		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
		dfprintk(FSCACHE,
			 "NFS:    readpage_from_fscache %d\n", ret);
		return 1;

	default:
		dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
	}
	return ret;
}

/*
 * Retrieve a set of pages from fscache
 */
int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
				 struct inode *inode,
				 struct address_space *mapping,
				 struct list_head *pages,
				 unsigned *nr_pages)
{
	unsigned npages = *nr_pages;
	int ret;

	dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
		 nfs_i_fscache(inode), npages, inode);

	ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
					  mapping, pages, nr_pages,
					  nfs_readpage_from_fscache_complete,
					  ctx,
					  mapping_gfp_mask(mapping));
	if (*nr_pages < npages)
		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
				      npages);
	if (*nr_pages > 0)
		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
				      *nr_pages);

	switch (ret) {
	case 0: /* read submitted to the cache for all pages */
		BUG_ON(!list_empty(pages));
		BUG_ON(*nr_pages != 0);
		dfprintk(FSCACHE,
			 "NFS: nfs_getpages_from_fscache: submitted\n");

		return ret;

	case -ENOBUFS: /* some pages aren't cached and can't be */
	case -ENODATA: /* some pages aren't cached */
		dfprintk(FSCACHE,
			 "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
		return 1;

	default:
		dfprintk(FSCACHE,
			 "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
	}

	return ret;
}

/*
 * Store a newly fetched page in fscache
 * - PG_fscache must be set on the page
 */
void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
{
	int ret;

	dfprintk(FSCACHE,
		 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
		 nfs_i_fscache(inode), page, page->index, page->flags, sync);

	ret = fscache_write_page(nfs_i_fscache(inode), page, GFP_KERNEL);
	dfprintk(FSCACHE,
		 "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
		 page, page->index, page->flags, ret);

	if (ret != 0) {
		fscache_uncache_page(nfs_i_fscache(inode), page);
		nfs_inc_fscache_stats(inode,
				      NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
	} else {
		nfs_inc_fscache_stats(inode,
				      NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
	}
}
Commit	Line	Data
14727281 DH	1	/* NFS filesystem cache interface
	2	*
	3	* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public Licence
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the Licence, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/init.h>
	13	#include <linux/kernel.h>
	14	#include <linux/sched.h>
	15	#include <linux/mm.h>
	16	#include <linux/nfs_fs.h>
	17	#include <linux/nfs_fs_sb.h>
	18	#include <linux/in6.h>
	19	#include <linux/seq_file.h>
5a0e3ad6	20	#include <linux/slab.h>
14727281 DH	21
14727281 DH	22	#include "internal.h"
545db45f	23	#include "iostat.h"
14727281 DH	24	#include "fscache.h"
	25
	26	#define NFSDBG_FACILITY NFSDBG_FSCACHE
	27
08734048 DH	28	static struct rb_root nfs_fscache_keys = RB_ROOT;
	29	static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
	30
14727281 DH	31	/*
	32	* Get the per-client index cookie for an NFS client if the appropriate mount
	33	* flag was set
	34	* - We always try and get an index cookie for the client, but get filehandle
	35	* cookies on a per-superblock basis, depending on the mount flags
	36	*/
	37	void nfs_fscache_get_client_cookie(struct nfs_client *clp)
	38	{
	39	/* create a cache index for looking up filehandles */
	40	clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
	41	&nfs_fscache_server_index_def,
94d30ae9	42	clp, true);
14727281 DH	43	dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
	44	clp, clp->fscache);
	45	}
	46
	47	/*
	48	* Dispose of a per-client cookie
	49	*/
	50	void nfs_fscache_release_client_cookie(struct nfs_client *clp)
	51	{
	52	dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
	53	clp, clp->fscache);
	54
	55	fscache_relinquish_cookie(clp->fscache, 0);
	56	clp->fscache = NULL;
	57	}
08734048 DH	58
	59	/*
	60	* Get the cache cookie for an NFS superblock. We have to handle
	61	* uniquification here because the cache doesn't do it for us.
2df54806 DH	62	*
	63	* The default uniquifier is just an empty string, but it may be overridden
	64	* either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
	65	* superblock across an automount point of some nature.
08734048	66	*/
2311b943	67	void nfs_fscache_get_super_cookie(struct super_block sb, const char uniq, int ulen)
08734048 DH	68	{
	69	struct nfs_fscache_key key, xkey;
	70	struct nfs_server *nfss = NFS_SB(sb);
	71	struct rb_node *p, parent;
2311b943	72	int diff;
2df54806 DH	73
	74	if (!uniq) {
	75	uniq = "";
	76	ulen = 1;
	77	}
	78
08734048 DH	79	key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
	80	if (!key)
	81	return;
	82
	83	key->nfs_client = nfss->nfs_client;
	84	key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
	85	key->key.nfs_server.flags = nfss->flags;
	86	key->key.nfs_server.rsize = nfss->rsize;
	87	key->key.nfs_server.wsize = nfss->wsize;
	88	key->key.nfs_server.acregmin = nfss->acregmin;
	89	key->key.nfs_server.acregmax = nfss->acregmax;
	90	key->key.nfs_server.acdirmin = nfss->acdirmin;
	91	key->key.nfs_server.acdirmax = nfss->acdirmax;
	92	key->key.nfs_server.fsid = nfss->fsid;
	93	key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
	94
	95	key->key.uniq_len = ulen;
	96	memcpy(key->key.uniquifier, uniq, ulen);
	97
	98	spin_lock(&nfs_fscache_keys_lock);
	99	p = &nfs_fscache_keys.rb_node;
	100	parent = NULL;
	101	while (*p) {
	102	parent = *p;
	103	xkey = rb_entry(parent, struct nfs_fscache_key, node);
	104
	105	if (key->nfs_client < xkey->nfs_client)
	106	goto go_left;
	107	if (key->nfs_client > xkey->nfs_client)
	108	goto go_right;
	109
	110	diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
	111	if (diff < 0)
	112	goto go_left;
	113	if (diff > 0)
	114	goto go_right;
	115
	116	if (key->key.uniq_len == 0)
	117	goto non_unique;
	118	diff = memcmp(key->key.uniquifier,
	119	xkey->key.uniquifier,
	120	key->key.uniq_len);
	121	if (diff < 0)
	122	goto go_left;
	123	if (diff > 0)
	124	goto go_right;
	125	goto non_unique;
	126
	127	go_left:
	128	p = &(*p)->rb_left;
	129	continue;
	130	go_right:
	131	p = &(*p)->rb_right;
	132	}
	133
	134	rb_link_node(&key->node, parent, p);
	135	rb_insert_color(&key->node, &nfs_fscache_keys);
	136	spin_unlock(&nfs_fscache_keys_lock);
	137	nfss->fscache_key = key;
	138
	139	/* create a cache index for looking up filehandles */
	140	nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
	141	&nfs_fscache_super_index_def,
94d30ae9	142	nfss, true);
08734048 DH	143	dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
	144	nfss, nfss->fscache);
	145	return;
	146
	147	non_unique:
	148	spin_unlock(&nfs_fscache_keys_lock);
	149	kfree(key);
	150	nfss->fscache_key = NULL;
	151	nfss->fscache = NULL;
	152	printk(KERN_WARNING "NFS:"
	153	" Cache request denied due to non-unique superblock keys\n");
	154	}
	155
	156	/*
	157	* release a per-superblock cookie
	158	*/
	159	void nfs_fscache_release_super_cookie(struct super_block *sb)
	160	{
	161	struct nfs_server *nfss = NFS_SB(sb);
	162
	163	dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
	164	nfss, nfss->fscache);
	165
	166	fscache_relinquish_cookie(nfss->fscache, 0);
	167	nfss->fscache = NULL;
	168
	169	if (nfss->fscache_key) {
	170	spin_lock(&nfs_fscache_keys_lock);
	171	rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
	172	spin_unlock(&nfs_fscache_keys_lock);
	173	kfree(nfss->fscache_key);
	174	nfss->fscache_key = NULL;
	175	}
	176	}
ef79c097 DH	177
	178	/*
	179	* Initialise the per-inode cache cookie pointer for an NFS inode.
	180	*/
f1fe29b4	181	void nfs_fscache_init_inode(struct inode *inode)
ef79c097	182	{
ef79c097 DH	183	struct nfs_inode *nfsi = NFS_I(inode);
ef79c097 DH	184
f1fe29b4 DH	185	nfsi->fscache = NULL;
f1fe29b4 DH	186	if (!S_ISREG(inode->i_mode))
ef79c097	187	return;
f1fe29b4 DH	188	nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
	189	&nfs_fscache_inode_object_def,
	190	nfsi, false);
ef79c097 DH	191	}
	192
	193	/*
	194	* Release a per-inode cookie.
	195	*/
f1fe29b4	196	void nfs_fscache_clear_inode(struct inode *inode)
ef79c097 DH	197	{
ef79c097 DH	198	struct nfs_inode *nfsi = NFS_I(inode);
f1fe29b4	199	struct fscache_cookie *cookie = nfs_i_fscache(inode);
ef79c097	200
f1fe29b4	201	dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);
ef79c097	202
f1fe29b4	203	fscache_relinquish_cookie(cookie, false);
ef79c097 DH	204	nfsi->fscache = NULL;
	205	}
	206
f1fe29b4	207	static bool nfs_fscache_can_enable(void *data)
ef79c097	208	{
f1fe29b4	209	struct inode *inode = data;
ef79c097	210
f1fe29b4	211	return !inode_is_open_for_write(inode);
ef79c097 DH	212	}
	213
	214	/*
f1fe29b4 DH	215	* Enable or disable caching for a file that is being opened as appropriate.
	216	* The cookie is allocated when the inode is initialised, but is not enabled at
	217	* that time. Enablement is deferred to file-open time to avoid stat() and
	218	* access() thrashing the cache.
	219	*
	220	* For now, with NFS, only regular files that are open read-only will be able
	221	* to use the cache.
	222	*
	223	* We enable the cache for an inode if we open it read-only and it isn't
	224	* currently open for writing. We disable the cache if the inode is open
	225	* write-only.
	226	*
	227	* The caller uses the file struct to pin i_writecount on the inode before
	228	* calling us when a file is opened for writing, so we can make use of that.
	229	*
	230	* Note that this may be invoked multiple times in parallel by parallel
	231	* nfs_open() functions.
ef79c097	232	*/
f1fe29b4	233	void nfs_fscache_open_file(struct inode inode, struct file filp)
ef79c097 DH	234	{
ef79c097 DH	235	struct nfs_inode *nfsi = NFS_I(inode);
f1fe29b4	236	struct fscache_cookie *cookie = nfs_i_fscache(inode);
ef79c097	237
f1fe29b4 DH	238	if (!fscache_cookie_valid(cookie))
f1fe29b4 DH	239	return;
ef79c097	240
f1fe29b4 DH	241	if (inode_is_open_for_write(inode)) {
	242	dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);
	243	clear_bit(NFS_INO_FSCACHE, &nfsi->flags);
	244	fscache_disable_cookie(cookie, true);
	245	fscache_uncache_all_inode_pages(cookie, inode);
	246	} else {
	247	dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi);
	248	fscache_enable_cookie(cookie, nfs_fscache_can_enable, inode);
	249	if (fscache_cookie_enabled(cookie))
	250	set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
ef79c097	251	}
ef79c097	252	}
f1fe29b4	253	EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
545db45f DH	254
	255	/*
	256	* Release the caching state associated with a page, if the page isn't busy
	257	* interacting with the cache.
	258	* - Returns true (can release page) or false (page busy).
	259	*/
	260	int nfs_fscache_release_page(struct page *page, gfp_t gfp)
	261	{
545db45f	262	if (PageFsCache(page)) {
f1fe29b4	263	struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
2c174009 TM	264
2c174009 TM	265	BUG_ON(!cookie);
545db45f	266	dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
f1fe29b4	267	cookie, page, NFS_I(page->mapping->host));
545db45f	268
201a1542 DH	269	if (!fscache_maybe_release_page(cookie, page, gfp))
	270	return 0;
	271
e9f456ca LR	272	nfs_inc_fscache_stats(page->mapping->host,
e9f456ca LR	273	NFSIOS_FSCACHE_PAGES_UNCACHED);
545db45f DH	274	}
	275
	276	return 1;
	277	}
	278
	279	/*
	280	* Release the caching state associated with a page if undergoing complete page
	281	* invalidation.
	282	*/
	283	void __nfs_fscache_invalidate_page(struct page page, struct inode inode)
	284	{
f1fe29b4	285	struct fscache_cookie *cookie = nfs_i_fscache(inode);
545db45f DH	286
	287	BUG_ON(!cookie);
	288
	289	dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
f1fe29b4	290	cookie, page, NFS_I(inode));
545db45f DH	291
	292	fscache_wait_on_page_write(cookie, page);
	293
	294	BUG_ON(!PageLocked(page));
	295	fscache_uncache_page(cookie, page);
e9f456ca LR	296	nfs_inc_fscache_stats(page->mapping->host,
e9f456ca LR	297	NFSIOS_FSCACHE_PAGES_UNCACHED);
545db45f	298	}
9a9fc1c0 DH	299
	300	/*
	301	* Handle completion of a page being read from the cache.
	302	* - Called in process (keventd) context.
	303	*/
	304	static void nfs_readpage_from_fscache_complete(struct page *page,
	305	void *context,
	306	int error)
	307	{
	308	dfprintk(FSCACHE,
	309	"NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
	310	page, context, error);
	311
	312	/* if the read completes with an error, we just unlock the page and let
	313	* the VM reissue the readpage */
	314	if (!error) {
	315	SetPageUptodate(page);
	316	unlock_page(page);
	317	} else {
	318	error = nfs_readpage_async(context, page->mapping->host, page);
	319	if (error)
	320	unlock_page(page);
	321	}
	322	}
	323
	324	/*
	325	* Retrieve a page from fscache
	326	*/
	327	int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
	328	struct inode inode, struct page page)
	329	{
	330	int ret;
	331
	332	dfprintk(FSCACHE,
	333	"NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
f1fe29b4	334	nfs_i_fscache(inode), page, page->index, page->flags, inode);
9a9fc1c0	335
f1fe29b4	336	ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
9a9fc1c0 DH	337	page,
	338	nfs_readpage_from_fscache_complete,
	339	ctx,
	340	GFP_KERNEL);
	341
	342	switch (ret) {
	343	case 0: /* read BIO submitted (page in fscache) */
	344	dfprintk(FSCACHE,
	345	"NFS: readpage_from_fscache: BIO submitted\n");
e9f456ca	346	nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
9a9fc1c0 DH	347	return ret;
	348
	349	case -ENOBUFS: /* inode not in cache */
	350	case -ENODATA: /* page not in cache */
e9f456ca	351	nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
9a9fc1c0 DH	352	dfprintk(FSCACHE,
	353	"NFS: readpage_from_fscache %d\n", ret);
	354	return 1;
	355
	356	default:
	357	dfprintk(FSCACHE, "NFS: readpage_from_fscache %d\n", ret);
e9f456ca	358	nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
9a9fc1c0 DH	359	}
	360	return ret;
	361	}
	362
	363	/*
	364	* Retrieve a set of pages from fscache
	365	*/
	366	int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
	367	struct inode *inode,
	368	struct address_space *mapping,
	369	struct list_head *pages,
	370	unsigned *nr_pages)
	371	{
0f15c53d CL	372	unsigned npages = *nr_pages;
0f15c53d CL	373	int ret;
9a9fc1c0 DH	374
9a9fc1c0 DH	375	dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
f1fe29b4	376	nfs_i_fscache(inode), npages, inode);
9a9fc1c0	377
f1fe29b4	378	ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
9a9fc1c0 DH	379	mapping, pages, nr_pages,
	380	nfs_readpage_from_fscache_complete,
	381	ctx,
	382	mapping_gfp_mask(mapping));
	383	if (*nr_pages < npages)
	384	nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
	385	npages);
	386	if (*nr_pages > 0)
	387	nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
	388	*nr_pages);
	389
	390	switch (ret) {
	391	case 0: /* read submitted to the cache for all pages */
	392	BUG_ON(!list_empty(pages));
	393	BUG_ON(*nr_pages != 0);
	394	dfprintk(FSCACHE,
	395	"NFS: nfs_getpages_from_fscache: submitted\n");
	396
	397	return ret;
	398
	399	case -ENOBUFS: /* some pages aren't cached and can't be */
	400	case -ENODATA: /* some pages aren't cached */
	401	dfprintk(FSCACHE,
	402	"NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
	403	return 1;
	404
	405	default:
	406	dfprintk(FSCACHE,
	407	"NFS: nfs_getpages_from_fscache: ret %d\n", ret);
	408	}
	409
	410	return ret;
	411	}
7f8e05f6 DH	412
	413	/*
	414	* Store a newly fetched page in fscache
	415	* - PG_fscache must be set on the page
	416	*/
	417	void __nfs_readpage_to_fscache(struct inode inode, struct page page, int sync)
	418	{
	419	int ret;
	420
	421	dfprintk(FSCACHE,
	422	"NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
f1fe29b4	423	nfs_i_fscache(inode), page, page->index, page->flags, sync);
7f8e05f6	424
f1fe29b4	425	ret = fscache_write_page(nfs_i_fscache(inode), page, GFP_KERNEL);
7f8e05f6 DH	426	dfprintk(FSCACHE,
	427	"NFS: readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
	428	page, page->index, page->flags, ret);
	429
	430	if (ret != 0) {
f1fe29b4	431	fscache_uncache_page(nfs_i_fscache(inode), page);
e9f456ca LR	432	nfs_inc_fscache_stats(inode,
	433	NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
	434	nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
7f8e05f6	435	} else {
e9f456ca LR	436	nfs_inc_fscache_stats(inode,
e9f456ca LR	437	NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
7f8e05f6 DH	438	}
7f8e05f6 DH	439	}