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

/*
 * linux/fs/nfs/pagelist.c
 *
 * A set of helper functions for managing NFS read and write requests.
 * The main purpose of these routines is to provide support for the
 * coalescing of several requests into a single RPC call.
 *
 * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
 *
 */

#include <linux/slab.h>
#include <linux/file.h>
#include <linux/sched.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs3.h>
#include <linux/nfs4.h>
#include <linux/nfs_page.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>

#include "internal.h"

static struct kmem_cache *nfs_page_cachep;

static inline struct nfs_page *
nfs_page_alloc(void)
{
	struct nfs_page	*p;
	p = kmem_cache_alloc(nfs_page_cachep, GFP_KERNEL);
	if (p) {
		memset(p, 0, sizeof(*p));
		INIT_LIST_HEAD(&p->wb_list);
	}
	return p;
}

static inline void
nfs_page_free(struct nfs_page *p)
{
	kmem_cache_free(nfs_page_cachep, p);
}

/**
 * nfs_create_request - Create an NFS read/write request.
 * @file: file descriptor to use
 * @inode: inode to which the request is attached
 * @page: page to write
 * @offset: starting offset within the page for the write
 * @count: number of bytes to read/write
 *
 * The page must be locked by the caller. This makes sure we never
 * create two different requests for the same page.
 * User should ensure it is safe to sleep in this function.
 */
struct nfs_page *
nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
		   struct page *page,
		   unsigned int offset, unsigned int count)
{
	struct nfs_server *server = NFS_SERVER(inode);
	struct nfs_page		*req;

	for (;;) {
		/* try to allocate the request struct */
		req = nfs_page_alloc();
		if (req != NULL)
			break;

		if (signalled() && (server->flags & NFS_MOUNT_INTR))
			return ERR_PTR(-ERESTARTSYS);
		yield();
	}

	/* Initialize the request struct. Initially, we assume a
	 * long write-back delay. This will be adjusted in
	 * update_nfs_request below if the region is not locked. */
	req->wb_page    = page;
	atomic_set(&req->wb_complete, 0);
	req->wb_index	= page->index;
	page_cache_get(page);
	BUG_ON(PagePrivate(page));
	BUG_ON(!PageLocked(page));
	BUG_ON(page->mapping->host != inode);
	req->wb_offset  = offset;
	req->wb_pgbase	= offset;
	req->wb_bytes   = count;
	atomic_set(&req->wb_count, 1);
	req->wb_context = get_nfs_open_context(ctx);

	return req;
}

/**
 * nfs_unlock_request - Unlock request and wake up sleepers.
 * @req:
 */
void nfs_unlock_request(struct nfs_page *req)
{
	if (!NFS_WBACK_BUSY(req)) {
		printk(KERN_ERR "NFS: Invalid unlock attempted\n");
		BUG();
	}
	smp_mb__before_clear_bit();
	clear_bit(PG_BUSY, &req->wb_flags);
	smp_mb__after_clear_bit();
	wake_up_bit(&req->wb_flags, PG_BUSY);
	nfs_release_request(req);
}

/**
 * nfs_set_page_writeback_locked - Lock a request for writeback
 * @req:
 */
int nfs_set_page_writeback_locked(struct nfs_page *req)
{
	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);

	if (!nfs_lock_request(req))
		return 0;
	radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
	return 1;
}

/**
 * nfs_clear_page_writeback - Unlock request and wake up sleepers
 */
void nfs_clear_page_writeback(struct nfs_page *req)
{
	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);

	if (req->wb_page != NULL) {
		spin_lock(&nfsi->req_lock);
		radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
		spin_unlock(&nfsi->req_lock);
	}
	nfs_unlock_request(req);
}

/**
 * nfs_clear_request - Free up all resources allocated to the request
 * @req:
 *
 * Release page resources associated with a write request after it
 * has completed.
 */
void nfs_clear_request(struct nfs_page *req)
{
	struct page *page = req->wb_page;
	if (page != NULL) {
		page_cache_release(page);
		req->wb_page = NULL;
	}
}


/**
 * nfs_release_request - Release the count on an NFS read/write request
 * @req: request to release
 *
 * Note: Should never be called with the spinlock held!
 */
void
nfs_release_request(struct nfs_page *req)
{
	if (!atomic_dec_and_test(&req->wb_count))
		return;

	/* Release struct file or cached credential */
	nfs_clear_request(req);
	put_nfs_open_context(req->wb_context);
	nfs_page_free(req);
}

static int nfs_wait_bit_interruptible(void *word)
{
	int ret = 0;

	if (signal_pending(current))
		ret = -ERESTARTSYS;
	else
		schedule();
	return ret;
}

/**
 * nfs_wait_on_request - Wait for a request to complete.
 * @req: request to wait upon.
 *
 * Interruptible by signals only if mounted with intr flag.
 * The user is responsible for holding a count on the request.
 */
int
nfs_wait_on_request(struct nfs_page *req)
{
        struct rpc_clnt	*clnt = NFS_CLIENT(req->wb_context->dentry->d_inode);
	sigset_t oldmask;
	int ret = 0;

	if (!test_bit(PG_BUSY, &req->wb_flags))
		goto out;
	/*
	 * Note: the call to rpc_clnt_sigmask() suffices to ensure that we
	 *	 are not interrupted if intr flag is not set
	 */
	rpc_clnt_sigmask(clnt, &oldmask);
	ret = out_of_line_wait_on_bit(&req->wb_flags, PG_BUSY,
			nfs_wait_bit_interruptible, TASK_INTERRUPTIBLE);
	rpc_clnt_sigunmask(clnt, &oldmask);
out:
	return ret;
}

/**
 * nfs_pageio_init - initialise a page io descriptor
 * @desc: pointer to descriptor
 * @inode: pointer to inode
 * @doio: pointer to io function
 * @bsize: io block size
 * @io_flags: extra parameters for the io function
 */
void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
		     struct inode *inode,
		     int (*doio)(struct inode *, struct list_head *, unsigned int, size_t, int),
		     size_t bsize,
		     int io_flags)
{
	INIT_LIST_HEAD(&desc->pg_list);
	desc->pg_bytes_written = 0;
	desc->pg_count = 0;
	desc->pg_bsize = bsize;
	desc->pg_base = 0;
	desc->pg_inode = inode;
	desc->pg_doio = doio;
	desc->pg_ioflags = io_flags;
	desc->pg_error = 0;
}

/**
 * nfs_can_coalesce_requests - test two requests for compatibility
 * @prev: pointer to nfs_page
 * @req: pointer to nfs_page
 *
 * The nfs_page structures 'prev' and 'req' are compared to ensure that the
 * page data area they describe is contiguous, and that their RPC
 * credentials, NFSv4 open state, and lockowners are the same.
 *
 * Return 'true' if this is the case, else return 'false'.
 */
static int nfs_can_coalesce_requests(struct nfs_page *prev,
				     struct nfs_page *req)
{
	if (req->wb_context->cred != prev->wb_context->cred)
		return 0;
	if (req->wb_context->lockowner != prev->wb_context->lockowner)
		return 0;
	if (req->wb_context->state != prev->wb_context->state)
		return 0;
	if (req->wb_index != (prev->wb_index + 1))
		return 0;
	if (req->wb_pgbase != 0)
		return 0;
	if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
		return 0;
	return 1;
}

/**
 * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
 * @desc: destination io descriptor
 * @req: request
 *
 * Returns true if the request 'req' was successfully coalesced into the
 * existing list of pages 'desc'.
 */
static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
				     struct nfs_page *req)
{
	size_t newlen = req->wb_bytes;

	if (desc->pg_count != 0) {
		struct nfs_page *prev;

		/*
		 * FIXME: ideally we should be able to coalesce all requests
		 * that are not block boundary aligned, but currently this
		 * is problematic for the case of bsize < PAGE_CACHE_SIZE,
		 * since nfs_flush_multi and nfs_pagein_multi assume you
		 * can have only one struct nfs_page.
		 */
		if (desc->pg_bsize < PAGE_SIZE)
			return 0;
		newlen += desc->pg_count;
		if (newlen > desc->pg_bsize)
			return 0;
		prev = nfs_list_entry(desc->pg_list.prev);
		if (!nfs_can_coalesce_requests(prev, req))
			return 0;
	} else
		desc->pg_base = req->wb_pgbase;
	nfs_list_remove_request(req);
	nfs_list_add_request(req, &desc->pg_list);
	desc->pg_count = newlen;
	return 1;
}

/*
 * Helper for nfs_pageio_add_request and nfs_pageio_complete
 */
static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
{
	if (!list_empty(&desc->pg_list)) {
		int error = desc->pg_doio(desc->pg_inode,
					  &desc->pg_list,
					  nfs_page_array_len(desc->pg_base,
							     desc->pg_count),
					  desc->pg_count,
					  desc->pg_ioflags);
		if (error < 0)
			desc->pg_error = error;
		else
			desc->pg_bytes_written += desc->pg_count;
	}
	if (list_empty(&desc->pg_list)) {
		desc->pg_count = 0;
		desc->pg_base = 0;
	}
}

/**
 * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
 * @desc: destination io descriptor
 * @req: request
 *
 * Returns true if the request 'req' was successfully coalesced into the
 * existing list of pages 'desc'.
 */
int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
			   struct nfs_page *req)
{
	while (!nfs_pageio_do_add_request(desc, req)) {
		nfs_pageio_doio(desc);
		if (desc->pg_error < 0)
			return 0;
	}
	return 1;
}

/**
 * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
 * @desc: pointer to io descriptor
 */
void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
{
	nfs_pageio_doio(desc);
}

#define NFS_SCAN_MAXENTRIES 16
/**
 * nfs_scan_list - Scan a list for matching requests
 * @nfsi: NFS inode
 * @head: One of the NFS inode request lists
 * @dst: Destination list
 * @idx_start: lower bound of page->index to scan
 * @npages: idx_start + npages sets the upper bound to scan.
 *
 * Moves elements from one of the inode request lists.
 * If the number of requests is set to 0, the entire address_space
 * starting at index idx_start, is scanned.
 * The requests are *not* checked to ensure that they form a contiguous set.
 * You must be holding the inode's req_lock when calling this function
 */
int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *head,
		struct list_head *dst, pgoff_t idx_start,
		unsigned int npages)
{
	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
	struct nfs_page *req;
	pgoff_t idx_end;
	int found, i;
	int res;

	res = 0;
	if (npages == 0)
		idx_end = ~0;
	else
		idx_end = idx_start + npages - 1;

	for (;;) {
		found = radix_tree_gang_lookup(&nfsi->nfs_page_tree,
				(void **)&pgvec[0], idx_start,
				NFS_SCAN_MAXENTRIES);
		if (found <= 0)
			break;
		for (i = 0; i < found; i++) {
			req = pgvec[i];
			if (req->wb_index > idx_end)
				goto out;
			idx_start = req->wb_index + 1;
			if (req->wb_list_head != head)
				continue;
			if (nfs_set_page_writeback_locked(req)) {
				nfs_list_remove_request(req);
				nfs_list_add_request(req, dst);
				res++;
			}
		}

	}
out:
	return res;
}

int __init nfs_init_nfspagecache(void)
{
	nfs_page_cachep = kmem_cache_create("nfs_page",
					    sizeof(struct nfs_page),
					    0, SLAB_HWCACHE_ALIGN,
					    NULL, NULL);
	if (nfs_page_cachep == NULL)
		return -ENOMEM;

	return 0;
}

void nfs_destroy_nfspagecache(void)
{
	kmem_cache_destroy(nfs_page_cachep);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/nfs/pagelist.c
	3	*
	4	* A set of helper functions for managing NFS read and write requests.
	5	* The main purpose of these routines is to provide support for the
	6	* coalescing of several requests into a single RPC call.
	7	*
	8	* Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
	9	*
	10	*/
	11
1da177e4 LT	12	#include <linux/slab.h>
1da177e4 LT	13	#include <linux/file.h>
e8edc6e0	14	#include <linux/sched.h>
1da177e4 LT	15	#include <linux/sunrpc/clnt.h>
	16	#include <linux/nfs3.h>
	17	#include <linux/nfs4.h>
	18	#include <linux/nfs_page.h>
	19	#include <linux/nfs_fs.h>
	20	#include <linux/nfs_mount.h>
	21
8d5658c9 TM	22	#include "internal.h"
8d5658c9 TM	23
e18b890b	24	static struct kmem_cache *nfs_page_cachep;
1da177e4 LT	25
	26	static inline struct nfs_page *
	27	nfs_page_alloc(void)
	28	{
	29	struct nfs_page *p;
e94b1766	30	p = kmem_cache_alloc(nfs_page_cachep, GFP_KERNEL);
1da177e4 LT	31	if (p) {
	32	memset(p, 0, sizeof(*p));
	33	INIT_LIST_HEAD(&p->wb_list);
	34	}
	35	return p;
	36	}
	37
	38	static inline void
	39	nfs_page_free(struct nfs_page *p)
	40	{
	41	kmem_cache_free(nfs_page_cachep, p);
	42	}
	43
	44	/**
	45	* nfs_create_request - Create an NFS read/write request.
	46	* @file: file descriptor to use
	47	* @inode: inode to which the request is attached
	48	* @page: page to write
	49	* @offset: starting offset within the page for the write
	50	* @count: number of bytes to read/write
	51	*
	52	* The page must be locked by the caller. This makes sure we never
a19b89ca	53	* create two different requests for the same page.
1da177e4 LT	54	* User should ensure it is safe to sleep in this function.
	55	*/
	56	struct nfs_page *
	57	nfs_create_request(struct nfs_open_context ctx, struct inode inode,
	58	struct page *page,
	59	unsigned int offset, unsigned int count)
	60	{
	61	struct nfs_server *server = NFS_SERVER(inode);
	62	struct nfs_page *req;
	63
1da177e4 LT	64	for (;;) {
	65	/* try to allocate the request struct */
	66	req = nfs_page_alloc();
	67	if (req != NULL)
	68	break;
	69
1da177e4 LT	70	if (signalled() && (server->flags & NFS_MOUNT_INTR))
	71	return ERR_PTR(-ERESTARTSYS);
	72	yield();
	73	}
	74
	75	/* Initialize the request struct. Initially, we assume a
	76	* long write-back delay. This will be adjusted in
	77	* update_nfs_request below if the region is not locked. */
	78	req->wb_page = page;
	79	atomic_set(&req->wb_complete, 0);
	80	req->wb_index = page->index;
	81	page_cache_get(page);
cd52ed35 TM	82	BUG_ON(PagePrivate(page));
	83	BUG_ON(!PageLocked(page));
	84	BUG_ON(page->mapping->host != inode);
1da177e4 LT	85	req->wb_offset = offset;
	86	req->wb_pgbase = offset;
	87	req->wb_bytes = count;
	88	atomic_set(&req->wb_count, 1);
	89	req->wb_context = get_nfs_open_context(ctx);
	90
	91	return req;
	92	}
	93
	94	/**
	95	* nfs_unlock_request - Unlock request and wake up sleepers.
	96	* @req:
	97	*/
	98	void nfs_unlock_request(struct nfs_page *req)
	99	{
	100	if (!NFS_WBACK_BUSY(req)) {
	101	printk(KERN_ERR "NFS: Invalid unlock attempted\n");
	102	BUG();
	103	}
	104	smp_mb__before_clear_bit();
	105	clear_bit(PG_BUSY, &req->wb_flags);
	106	smp_mb__after_clear_bit();
464a98bd	107	wake_up_bit(&req->wb_flags, PG_BUSY);
1da177e4 LT	108	nfs_release_request(req);
	109	}
	110
c6a556b8 TM	111	/**
	112	* nfs_set_page_writeback_locked - Lock a request for writeback
	113	* @req:
	114	*/
	115	int nfs_set_page_writeback_locked(struct nfs_page *req)
	116	{
	117	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
	118
	119	if (!nfs_lock_request(req))
	120	return 0;
	121	radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
	122	return 1;
	123	}
	124
	125	/**
	126	* nfs_clear_page_writeback - Unlock request and wake up sleepers
	127	*/
	128	void nfs_clear_page_writeback(struct nfs_page *req)
	129	{
	130	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
	131
deb7d638 TM	132	if (req->wb_page != NULL) {
	133	spin_lock(&nfsi->req_lock);
	134	radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
	135	spin_unlock(&nfsi->req_lock);
	136	}
c6a556b8 TM	137	nfs_unlock_request(req);
	138	}
	139
1da177e4 LT	140	/**
	141	* nfs_clear_request - Free up all resources allocated to the request
	142	* @req:
	143	*
	144	* Release page resources associated with a write request after it
	145	* has completed.
	146	*/
	147	void nfs_clear_request(struct nfs_page *req)
	148	{
cd52ed35 TM	149	struct page *page = req->wb_page;
cd52ed35 TM	150	if (page != NULL) {
cd52ed35	151	page_cache_release(page);
1da177e4 LT	152	req->wb_page = NULL;
	153	}
	154	}
	155
	156
	157	/**
	158	* nfs_release_request - Release the count on an NFS read/write request
	159	* @req: request to release
	160	*
	161	* Note: Should never be called with the spinlock held!
	162	*/
	163	void
	164	nfs_release_request(struct nfs_page *req)
	165	{
	166	if (!atomic_dec_and_test(&req->wb_count))
	167	return;
	168
1da177e4 LT	169	/* Release struct file or cached credential */
	170	nfs_clear_request(req);
	171	put_nfs_open_context(req->wb_context);
	172	nfs_page_free(req);
	173	}
	174
464a98bd TM	175	static int nfs_wait_bit_interruptible(void *word)
	176	{
	177	int ret = 0;
	178
	179	if (signal_pending(current))
	180	ret = -ERESTARTSYS;
	181	else
	182	schedule();
	183	return ret;
	184	}
	185
1da177e4 LT	186	/**
	187	* nfs_wait_on_request - Wait for a request to complete.
	188	* @req: request to wait upon.
	189	*
	190	* Interruptible by signals only if mounted with intr flag.
	191	* The user is responsible for holding a count on the request.
	192	*/
	193	int
	194	nfs_wait_on_request(struct nfs_page *req)
	195	{
464a98bd TM	196	struct rpc_clnt *clnt = NFS_CLIENT(req->wb_context->dentry->d_inode);
	197	sigset_t oldmask;
	198	int ret = 0;
	199
	200	if (!test_bit(PG_BUSY, &req->wb_flags))
	201	goto out;
	202	/*
	203	* Note: the call to rpc_clnt_sigmask() suffices to ensure that we
	204	* are not interrupted if intr flag is not set
	205	*/
	206	rpc_clnt_sigmask(clnt, &oldmask);
	207	ret = out_of_line_wait_on_bit(&req->wb_flags, PG_BUSY,
	208	nfs_wait_bit_interruptible, TASK_INTERRUPTIBLE);
	209	rpc_clnt_sigunmask(clnt, &oldmask);
	210	out:
	211	return ret;
1da177e4 LT	212	}
	213
	214	/**
d8a5ad75 TM	215	* nfs_pageio_init - initialise a page io descriptor
d8a5ad75 TM	216	* @desc: pointer to descriptor
bcb71bba TM	217	* @inode: pointer to inode
	218	* @doio: pointer to io function
	219	* @bsize: io block size
	220	* @io_flags: extra parameters for the io function
d8a5ad75	221	*/
bcb71bba TM	222	void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
bcb71bba TM	223	struct inode *inode,
8d5658c9	224	int (doio)(struct inode , struct list_head *, unsigned int, size_t, int),
84dde76c	225	size_t bsize,
bcb71bba	226	int io_flags)
d8a5ad75 TM	227	{
d8a5ad75 TM	228	INIT_LIST_HEAD(&desc->pg_list);
bcb71bba	229	desc->pg_bytes_written = 0;
d8a5ad75 TM	230	desc->pg_count = 0;
	231	desc->pg_bsize = bsize;
	232	desc->pg_base = 0;
bcb71bba TM	233	desc->pg_inode = inode;
	234	desc->pg_doio = doio;
	235	desc->pg_ioflags = io_flags;
	236	desc->pg_error = 0;
d8a5ad75 TM	237	}
	238
	239	/**
	240	* nfs_can_coalesce_requests - test two requests for compatibility
	241	* @prev: pointer to nfs_page
	242	* @req: pointer to nfs_page
	243	*
	244	* The nfs_page structures 'prev' and 'req' are compared to ensure that the
	245	* page data area they describe is contiguous, and that their RPC
	246	* credentials, NFSv4 open state, and lockowners are the same.
	247	*
	248	* Return 'true' if this is the case, else return 'false'.
	249	*/
	250	static int nfs_can_coalesce_requests(struct nfs_page *prev,
	251	struct nfs_page *req)
	252	{
	253	if (req->wb_context->cred != prev->wb_context->cred)
	254	return 0;
	255	if (req->wb_context->lockowner != prev->wb_context->lockowner)
	256	return 0;
	257	if (req->wb_context->state != prev->wb_context->state)
	258	return 0;
	259	if (req->wb_index != (prev->wb_index + 1))
	260	return 0;
	261	if (req->wb_pgbase != 0)
	262	return 0;
	263	if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
	264	return 0;
	265	return 1;
	266	}
	267
	268	/**
bcb71bba	269	* nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
d8a5ad75 TM	270	* @desc: destination io descriptor
	271	* @req: request
	272	*
	273	* Returns true if the request 'req' was successfully coalesced into the
	274	* existing list of pages 'desc'.
	275	*/
bcb71bba TM	276	static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
bcb71bba TM	277	struct nfs_page *req)
d8a5ad75 TM	278	{
	279	size_t newlen = req->wb_bytes;
	280
	281	if (desc->pg_count != 0) {
	282	struct nfs_page *prev;
	283
	284	/*
	285	* FIXME: ideally we should be able to coalesce all requests
	286	* that are not block boundary aligned, but currently this
	287	* is problematic for the case of bsize < PAGE_CACHE_SIZE,
	288	* since nfs_flush_multi and nfs_pagein_multi assume you
	289	* can have only one struct nfs_page.
	290	*/
8d5658c9 TM	291	if (desc->pg_bsize < PAGE_SIZE)
8d5658c9 TM	292	return 0;
d8a5ad75	293	newlen += desc->pg_count;
8d5658c9	294	if (newlen > desc->pg_bsize)
d8a5ad75 TM	295	return 0;
	296	prev = nfs_list_entry(desc->pg_list.prev);
	297	if (!nfs_can_coalesce_requests(prev, req))
	298	return 0;
	299	} else
	300	desc->pg_base = req->wb_pgbase;
	301	nfs_list_remove_request(req);
	302	nfs_list_add_request(req, &desc->pg_list);
	303	desc->pg_count = newlen;
	304	return 1;
	305	}
	306
bcb71bba TM	307	/*
	308	* Helper for nfs_pageio_add_request and nfs_pageio_complete
	309	*/
	310	static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
	311	{
	312	if (!list_empty(&desc->pg_list)) {
	313	int error = desc->pg_doio(desc->pg_inode,
	314	&desc->pg_list,
8d5658c9 TM	315	nfs_page_array_len(desc->pg_base,
8d5658c9 TM	316	desc->pg_count),
bcb71bba TM	317	desc->pg_count,
	318	desc->pg_ioflags);
	319	if (error < 0)
	320	desc->pg_error = error;
	321	else
	322	desc->pg_bytes_written += desc->pg_count;
	323	}
	324	if (list_empty(&desc->pg_list)) {
	325	desc->pg_count = 0;
	326	desc->pg_base = 0;
	327	}
	328	}
	329
	330	/**
	331	* nfs_pageio_add_request - Attempt to coalesce a request into a page list.
	332	* @desc: destination io descriptor
	333	* @req: request
	334	*
	335	* Returns true if the request 'req' was successfully coalesced into the
	336	* existing list of pages 'desc'.
	337	*/
8b09bee3 TM	338	int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
8b09bee3 TM	339	struct nfs_page *req)
bcb71bba TM	340	{
	341	while (!nfs_pageio_do_add_request(desc, req)) {
	342	nfs_pageio_doio(desc);
	343	if (desc->pg_error < 0)
	344	return 0;
	345	}
	346	return 1;
	347	}
	348
bcb71bba TM	349	/**
	350	* nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
	351	* @desc: pointer to io descriptor
	352	*/
	353	void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
	354	{
	355	nfs_pageio_doio(desc);
	356	}
	357
3da28eb1	358	#define NFS_SCAN_MAXENTRIES 16
1da177e4 LT	359	/**
1da177e4 LT	360	* nfs_scan_list - Scan a list for matching requests
d2ccddf0	361	* @nfsi: NFS inode
1da177e4 LT	362	* @head: One of the NFS inode request lists
	363	* @dst: Destination list
	364	* @idx_start: lower bound of page->index to scan
	365	* @npages: idx_start + npages sets the upper bound to scan.
	366	*
	367	* Moves elements from one of the inode request lists.
	368	* If the number of requests is set to 0, the entire address_space
	369	* starting at index idx_start, is scanned.
	370	* The requests are not checked to ensure that they form a contiguous set.
	371	* You must be holding the inode's req_lock when calling this function
	372	*/
d2ccddf0	373	int nfs_scan_list(struct nfs_inode nfsi, struct list_head head,
ca52fec1	374	struct list_head *dst, pgoff_t idx_start,
d2ccddf0	375	unsigned int npages)
1da177e4	376	{
d2ccddf0 TM	377	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
d2ccddf0 TM	378	struct nfs_page *req;
ca52fec1	379	pgoff_t idx_end;
d2ccddf0 TM	380	int found, i;
d2ccddf0 TM	381	int res;
1da177e4 LT	382
	383	res = 0;
	384	if (npages == 0)
	385	idx_end = ~0;
	386	else
	387	idx_end = idx_start + npages - 1;
	388
d2ccddf0 TM	389	for (;;) {
	390	found = radix_tree_gang_lookup(&nfsi->nfs_page_tree,
	391	(void **)&pgvec[0], idx_start,
	392	NFS_SCAN_MAXENTRIES);
	393	if (found <= 0)
1da177e4	394	break;
d2ccddf0 TM	395	for (i = 0; i < found; i++) {
	396	req = pgvec[i];
	397	if (req->wb_index > idx_end)
	398	goto out;
	399	idx_start = req->wb_index + 1;
	400	if (req->wb_list_head != head)
	401	continue;
	402	if (nfs_set_page_writeback_locked(req)) {
	403	nfs_list_remove_request(req);
	404	nfs_list_add_request(req, dst);
	405	res++;
	406	}
	407	}
1da177e4	408
1da177e4	409	}
d2ccddf0	410	out:
1da177e4 LT	411	return res;
	412	}
	413
f7b422b1	414	int __init nfs_init_nfspagecache(void)
1da177e4 LT	415	{
	416	nfs_page_cachep = kmem_cache_create("nfs_page",
	417	sizeof(struct nfs_page),
	418	0, SLAB_HWCACHE_ALIGN,
	419	NULL, NULL);
	420	if (nfs_page_cachep == NULL)
	421	return -ENOMEM;
	422
	423	return 0;
	424	}
	425
266bee88	426	void nfs_destroy_nfspagecache(void)
1da177e4	427	{
1a1d92c1	428	kmem_cache_destroy(nfs_page_cachep);
1da177e4 LT	429	}
1da177e4 LT	430