[linux-2.6-block.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/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"

#define NFS_PARANOIA 1

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, and avoids
 * a possible deadlock when we reach the hard limit on the number
 * of dirty pages.
 * 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;

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

		/* Try to free up at least one request in order to stay
		 * below the hard limit
		 */
		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;

#ifdef NFS_PARANOIA
	BUG_ON (!list_empty(&req->wb_list));
	BUG_ON (NFS_WBACK_BUSY(req));
#endif

	/* 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),
		     unsigned int 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>
	13	#include <linux/file.h>
	14	#include <linux/sunrpc/clnt.h>
	15	#include <linux/nfs3.h>
	16	#include <linux/nfs4.h>
	17	#include <linux/nfs_page.h>
	18	#include <linux/nfs_fs.h>
	19	#include <linux/nfs_mount.h>
	20
8d5658c9 TM	21	#include "internal.h"
8d5658c9 TM	22
1da177e4 LT	23	#define NFS_PARANOIA 1
1da177e4 LT	24
e18b890b	25	static struct kmem_cache *nfs_page_cachep;
1da177e4 LT	26
	27	static inline struct nfs_page *
	28	nfs_page_alloc(void)
	29	{
	30	struct nfs_page *p;
e94b1766	31	p = kmem_cache_alloc(nfs_page_cachep, GFP_KERNEL);
1da177e4 LT	32	if (p) {
	33	memset(p, 0, sizeof(*p));
	34	INIT_LIST_HEAD(&p->wb_list);
	35	}
	36	return p;
	37	}
	38
	39	static inline void
	40	nfs_page_free(struct nfs_page *p)
	41	{
	42	kmem_cache_free(nfs_page_cachep, p);
	43	}
	44
	45	/**
	46	* nfs_create_request - Create an NFS read/write request.
	47	* @file: file descriptor to use
	48	* @inode: inode to which the request is attached
	49	* @page: page to write
	50	* @offset: starting offset within the page for the write
	51	* @count: number of bytes to read/write
	52	*
	53	* The page must be locked by the caller. This makes sure we never
	54	* create two different requests for the same page, and avoids
	55	* a possible deadlock when we reach the hard limit on the number
	56	* of dirty pages.
	57	* User should ensure it is safe to sleep in this function.
	58	*/
	59	struct nfs_page *
	60	nfs_create_request(struct nfs_open_context ctx, struct inode inode,
	61	struct page *page,
	62	unsigned int offset, unsigned int count)
	63	{
	64	struct nfs_server *server = NFS_SERVER(inode);
	65	struct nfs_page *req;
	66
	67	/* Deal with hard limits. */
	68	for (;;) {
	69	/* try to allocate the request struct */
	70	req = nfs_page_alloc();
	71	if (req != NULL)
	72	break;
	73
	74	/* Try to free up at least one request in order to stay
	75	* below the hard limit
	76	*/
	77	if (signalled() && (server->flags & NFS_MOUNT_INTR))
	78	return ERR_PTR(-ERESTARTSYS);
	79	yield();
	80	}
	81
	82	/* Initialize the request struct. Initially, we assume a
	83	* long write-back delay. This will be adjusted in
	84	* update_nfs_request below if the region is not locked. */
	85	req->wb_page = page;
	86	atomic_set(&req->wb_complete, 0);
	87	req->wb_index = page->index;
	88	page_cache_get(page);
cd52ed35 TM	89	BUG_ON(PagePrivate(page));
	90	BUG_ON(!PageLocked(page));
	91	BUG_ON(page->mapping->host != inode);
1da177e4 LT	92	req->wb_offset = offset;
	93	req->wb_pgbase = offset;
	94	req->wb_bytes = count;
	95	atomic_set(&req->wb_count, 1);
	96	req->wb_context = get_nfs_open_context(ctx);
	97
	98	return req;
	99	}
	100
	101	/**
	102	* nfs_unlock_request - Unlock request and wake up sleepers.
	103	* @req:
	104	*/
	105	void nfs_unlock_request(struct nfs_page *req)
	106	{
	107	if (!NFS_WBACK_BUSY(req)) {
	108	printk(KERN_ERR "NFS: Invalid unlock attempted\n");
	109	BUG();
	110	}
	111	smp_mb__before_clear_bit();
	112	clear_bit(PG_BUSY, &req->wb_flags);
	113	smp_mb__after_clear_bit();
464a98bd	114	wake_up_bit(&req->wb_flags, PG_BUSY);
1da177e4 LT	115	nfs_release_request(req);
	116	}
	117
c6a556b8 TM	118	/**
	119	* nfs_set_page_writeback_locked - Lock a request for writeback
	120	* @req:
	121	*/
	122	int nfs_set_page_writeback_locked(struct nfs_page *req)
	123	{
	124	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
	125
	126	if (!nfs_lock_request(req))
	127	return 0;
	128	radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
	129	return 1;
	130	}
	131
	132	/**
	133	* nfs_clear_page_writeback - Unlock request and wake up sleepers
	134	*/
	135	void nfs_clear_page_writeback(struct nfs_page *req)
	136	{
	137	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
	138
deb7d638 TM	139	if (req->wb_page != NULL) {
	140	spin_lock(&nfsi->req_lock);
	141	radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
	142	spin_unlock(&nfsi->req_lock);
	143	}
c6a556b8 TM	144	nfs_unlock_request(req);
	145	}
	146
1da177e4 LT	147	/**
	148	* nfs_clear_request - Free up all resources allocated to the request
	149	* @req:
	150	*
	151	* Release page resources associated with a write request after it
	152	* has completed.
	153	*/
	154	void nfs_clear_request(struct nfs_page *req)
	155	{
cd52ed35 TM	156	struct page *page = req->wb_page;
cd52ed35 TM	157	if (page != NULL) {
cd52ed35	158	page_cache_release(page);
1da177e4 LT	159	req->wb_page = NULL;
	160	}
	161	}
	162
	163
	164	/**
	165	* nfs_release_request - Release the count on an NFS read/write request
	166	* @req: request to release
	167	*
	168	* Note: Should never be called with the spinlock held!
	169	*/
	170	void
	171	nfs_release_request(struct nfs_page *req)
	172	{
	173	if (!atomic_dec_and_test(&req->wb_count))
	174	return;
	175
	176	#ifdef NFS_PARANOIA
	177	BUG_ON (!list_empty(&req->wb_list));
	178	BUG_ON (NFS_WBACK_BUSY(req));
	179	#endif
	180
	181	/* Release struct file or cached credential */
	182	nfs_clear_request(req);
	183	put_nfs_open_context(req->wb_context);
	184	nfs_page_free(req);
	185	}
	186
464a98bd TM	187	static int nfs_wait_bit_interruptible(void *word)
	188	{
	189	int ret = 0;
	190
	191	if (signal_pending(current))
	192	ret = -ERESTARTSYS;
	193	else
	194	schedule();
	195	return ret;
	196	}
	197
1da177e4 LT	198	/**
	199	* nfs_wait_on_request - Wait for a request to complete.
	200	* @req: request to wait upon.
	201	*
	202	* Interruptible by signals only if mounted with intr flag.
	203	* The user is responsible for holding a count on the request.
	204	*/
	205	int
	206	nfs_wait_on_request(struct nfs_page *req)
	207	{
464a98bd TM	208	struct rpc_clnt *clnt = NFS_CLIENT(req->wb_context->dentry->d_inode);
	209	sigset_t oldmask;
	210	int ret = 0;
	211
	212	if (!test_bit(PG_BUSY, &req->wb_flags))
	213	goto out;
	214	/*
	215	* Note: the call to rpc_clnt_sigmask() suffices to ensure that we
	216	* are not interrupted if intr flag is not set
	217	*/
	218	rpc_clnt_sigmask(clnt, &oldmask);
	219	ret = out_of_line_wait_on_bit(&req->wb_flags, PG_BUSY,
	220	nfs_wait_bit_interruptible, TASK_INTERRUPTIBLE);
	221	rpc_clnt_sigunmask(clnt, &oldmask);
	222	out:
	223	return ret;
1da177e4 LT	224	}
	225
	226	/**
d8a5ad75 TM	227	* nfs_pageio_init - initialise a page io descriptor
d8a5ad75 TM	228	* @desc: pointer to descriptor
bcb71bba TM	229	* @inode: pointer to inode
	230	* @doio: pointer to io function
	231	* @bsize: io block size
	232	* @io_flags: extra parameters for the io function
d8a5ad75	233	*/
bcb71bba TM	234	void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
bcb71bba TM	235	struct inode *inode,
8d5658c9	236	int (doio)(struct inode , struct list_head *, unsigned int, size_t, int),
bcb71bba TM	237	unsigned int bsize,
bcb71bba TM	238	int io_flags)
d8a5ad75 TM	239	{
d8a5ad75 TM	240	INIT_LIST_HEAD(&desc->pg_list);
bcb71bba	241	desc->pg_bytes_written = 0;
d8a5ad75 TM	242	desc->pg_count = 0;
	243	desc->pg_bsize = bsize;
	244	desc->pg_base = 0;
bcb71bba TM	245	desc->pg_inode = inode;
	246	desc->pg_doio = doio;
	247	desc->pg_ioflags = io_flags;
	248	desc->pg_error = 0;
d8a5ad75 TM	249	}
	250
	251	/**
	252	* nfs_can_coalesce_requests - test two requests for compatibility
	253	* @prev: pointer to nfs_page
	254	* @req: pointer to nfs_page
	255	*
	256	* The nfs_page structures 'prev' and 'req' are compared to ensure that the
	257	* page data area they describe is contiguous, and that their RPC
	258	* credentials, NFSv4 open state, and lockowners are the same.
	259	*
	260	* Return 'true' if this is the case, else return 'false'.
	261	*/
	262	static int nfs_can_coalesce_requests(struct nfs_page *prev,
	263	struct nfs_page *req)
	264	{
	265	if (req->wb_context->cred != prev->wb_context->cred)
	266	return 0;
	267	if (req->wb_context->lockowner != prev->wb_context->lockowner)
	268	return 0;
	269	if (req->wb_context->state != prev->wb_context->state)
	270	return 0;
	271	if (req->wb_index != (prev->wb_index + 1))
	272	return 0;
	273	if (req->wb_pgbase != 0)
	274	return 0;
	275	if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
	276	return 0;
	277	return 1;
	278	}
	279
	280	/**
bcb71bba	281	* nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
d8a5ad75 TM	282	* @desc: destination io descriptor
	283	* @req: request
	284	*
	285	* Returns true if the request 'req' was successfully coalesced into the
	286	* existing list of pages 'desc'.
	287	*/
bcb71bba TM	288	static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
bcb71bba TM	289	struct nfs_page *req)
d8a5ad75 TM	290	{
	291	size_t newlen = req->wb_bytes;
	292
	293	if (desc->pg_count != 0) {
	294	struct nfs_page *prev;
	295
	296	/*
	297	* FIXME: ideally we should be able to coalesce all requests
	298	* that are not block boundary aligned, but currently this
	299	* is problematic for the case of bsize < PAGE_CACHE_SIZE,
	300	* since nfs_flush_multi and nfs_pagein_multi assume you
	301	* can have only one struct nfs_page.
	302	*/
8d5658c9 TM	303	if (desc->pg_bsize < PAGE_SIZE)
8d5658c9 TM	304	return 0;
d8a5ad75	305	newlen += desc->pg_count;
8d5658c9	306	if (newlen > desc->pg_bsize)
d8a5ad75 TM	307	return 0;
	308	prev = nfs_list_entry(desc->pg_list.prev);
	309	if (!nfs_can_coalesce_requests(prev, req))
	310	return 0;
	311	} else
	312	desc->pg_base = req->wb_pgbase;
	313	nfs_list_remove_request(req);
	314	nfs_list_add_request(req, &desc->pg_list);
	315	desc->pg_count = newlen;
	316	return 1;
	317	}
	318
bcb71bba TM	319	/*
	320	* Helper for nfs_pageio_add_request and nfs_pageio_complete
	321	*/
	322	static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
	323	{
	324	if (!list_empty(&desc->pg_list)) {
	325	int error = desc->pg_doio(desc->pg_inode,
	326	&desc->pg_list,
8d5658c9 TM	327	nfs_page_array_len(desc->pg_base,
8d5658c9 TM	328	desc->pg_count),
bcb71bba TM	329	desc->pg_count,
	330	desc->pg_ioflags);
	331	if (error < 0)
	332	desc->pg_error = error;
	333	else
	334	desc->pg_bytes_written += desc->pg_count;
	335	}
	336	if (list_empty(&desc->pg_list)) {
	337	desc->pg_count = 0;
	338	desc->pg_base = 0;
	339	}
	340	}
	341
	342	/**
	343	* nfs_pageio_add_request - Attempt to coalesce a request into a page list.
	344	* @desc: destination io descriptor
	345	* @req: request
	346	*
	347	* Returns true if the request 'req' was successfully coalesced into the
	348	* existing list of pages 'desc'.
	349	*/
8b09bee3 TM	350	int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
8b09bee3 TM	351	struct nfs_page *req)
bcb71bba TM	352	{
	353	while (!nfs_pageio_do_add_request(desc, req)) {
	354	nfs_pageio_doio(desc);
	355	if (desc->pg_error < 0)
	356	return 0;
	357	}
	358	return 1;
	359	}
	360
bcb71bba TM	361	/**
	362	* nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
	363	* @desc: pointer to io descriptor
	364	*/
	365	void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
	366	{
	367	nfs_pageio_doio(desc);
	368	}
	369
3da28eb1	370	#define NFS_SCAN_MAXENTRIES 16
1da177e4 LT	371	/**
1da177e4 LT	372	* nfs_scan_list - Scan a list for matching requests
d2ccddf0	373	* @nfsi: NFS inode
1da177e4 LT	374	* @head: One of the NFS inode request lists
	375	* @dst: Destination list
	376	* @idx_start: lower bound of page->index to scan
	377	* @npages: idx_start + npages sets the upper bound to scan.
	378	*
	379	* Moves elements from one of the inode request lists.
	380	* If the number of requests is set to 0, the entire address_space
	381	* starting at index idx_start, is scanned.
	382	* The requests are not checked to ensure that they form a contiguous set.
	383	* You must be holding the inode's req_lock when calling this function
	384	*/
d2ccddf0	385	int nfs_scan_list(struct nfs_inode nfsi, struct list_head head,
ca52fec1	386	struct list_head *dst, pgoff_t idx_start,
d2ccddf0	387	unsigned int npages)
1da177e4	388	{
d2ccddf0 TM	389	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
d2ccddf0 TM	390	struct nfs_page *req;
ca52fec1	391	pgoff_t idx_end;
d2ccddf0 TM	392	int found, i;
d2ccddf0 TM	393	int res;
1da177e4 LT	394
	395	res = 0;
	396	if (npages == 0)
	397	idx_end = ~0;
	398	else
	399	idx_end = idx_start + npages - 1;
	400
d2ccddf0 TM	401	for (;;) {
	402	found = radix_tree_gang_lookup(&nfsi->nfs_page_tree,
	403	(void **)&pgvec[0], idx_start,
	404	NFS_SCAN_MAXENTRIES);
	405	if (found <= 0)
1da177e4	406	break;
d2ccddf0 TM	407	for (i = 0; i < found; i++) {
	408	req = pgvec[i];
	409	if (req->wb_index > idx_end)
	410	goto out;
	411	idx_start = req->wb_index + 1;
	412	if (req->wb_list_head != head)
	413	continue;
	414	if (nfs_set_page_writeback_locked(req)) {
	415	nfs_list_remove_request(req);
	416	nfs_list_add_request(req, dst);
	417	res++;
	418	}
	419	}
1da177e4	420
1da177e4	421	}
d2ccddf0	422	out:
1da177e4 LT	423	return res;
	424	}
	425
f7b422b1	426	int __init nfs_init_nfspagecache(void)
1da177e4 LT	427	{
	428	nfs_page_cachep = kmem_cache_create("nfs_page",
	429	sizeof(struct nfs_page),
	430	0, SLAB_HWCACHE_ALIGN,
	431	NULL, NULL);
	432	if (nfs_page_cachep == NULL)
	433	return -ENOMEM;
	434
	435	return 0;
	436	}
	437
266bee88	438	void nfs_destroy_nfspagecache(void)
1da177e4	439	{
1a1d92c1	440	kmem_cache_destroy(nfs_page_cachep);
1da177e4 LT	441	}
1da177e4 LT	442