[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>

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