[deliverable/linux.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.
 * 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;

#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
a19b89ca	54	* create two different requests for the same page.
1da177e4 LT	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
1da177e4 LT	65	for (;;) {
	66	/* try to allocate the request struct */
	67	req = nfs_page_alloc();
	68	if (req != NULL)
	69	break;
	70
1da177e4 LT	71	if (signalled() && (server->flags & NFS_MOUNT_INTR))
	72	return ERR_PTR(-ERESTARTSYS);
	73	yield();
	74	}
	75
	76	/* Initialize the request struct. Initially, we assume a
	77	* long write-back delay. This will be adjusted in
	78	* update_nfs_request below if the region is not locked. */
	79	req->wb_page = page;
	80	atomic_set(&req->wb_complete, 0);
	81	req->wb_index = page->index;
	82	page_cache_get(page);
cd52ed35 TM	83	BUG_ON(PagePrivate(page));
	84	BUG_ON(!PageLocked(page));
	85	BUG_ON(page->mapping->host != inode);
1da177e4 LT	86	req->wb_offset = offset;
	87	req->wb_pgbase = offset;
	88	req->wb_bytes = count;
	89	atomic_set(&req->wb_count, 1);
	90	req->wb_context = get_nfs_open_context(ctx);
	91
	92	return req;
	93	}
	94
	95	/**
	96	* nfs_unlock_request - Unlock request and wake up sleepers.
	97	* @req:
	98	*/
	99	void nfs_unlock_request(struct nfs_page *req)
	100	{
	101	if (!NFS_WBACK_BUSY(req)) {
	102	printk(KERN_ERR "NFS: Invalid unlock attempted\n");
	103	BUG();
	104	}
	105	smp_mb__before_clear_bit();
	106	clear_bit(PG_BUSY, &req->wb_flags);
	107	smp_mb__after_clear_bit();
464a98bd	108	wake_up_bit(&req->wb_flags, PG_BUSY);
1da177e4 LT	109	nfs_release_request(req);
	110	}
	111
c6a556b8 TM	112	/**
	113	* nfs_set_page_writeback_locked - Lock a request for writeback
	114	* @req:
	115	*/
	116	int nfs_set_page_writeback_locked(struct nfs_page *req)
	117	{
	118	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
	119
	120	if (!nfs_lock_request(req))
	121	return 0;
	122	radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
	123	return 1;
	124	}
	125
	126	/**
	127	* nfs_clear_page_writeback - Unlock request and wake up sleepers
	128	*/
	129	void nfs_clear_page_writeback(struct nfs_page *req)
	130	{
	131	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
	132
deb7d638 TM	133	if (req->wb_page != NULL) {
	134	spin_lock(&nfsi->req_lock);
	135	radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
	136	spin_unlock(&nfsi->req_lock);
	137	}
c6a556b8 TM	138	nfs_unlock_request(req);
	139	}
	140
1da177e4 LT	141	/**
	142	* nfs_clear_request - Free up all resources allocated to the request
	143	* @req:
	144	*
	145	* Release page resources associated with a write request after it
	146	* has completed.
	147	*/
	148	void nfs_clear_request(struct nfs_page *req)
	149	{
cd52ed35 TM	150	struct page *page = req->wb_page;
cd52ed35 TM	151	if (page != NULL) {
cd52ed35	152	page_cache_release(page);
1da177e4 LT	153	req->wb_page = NULL;
	154	}
	155	}
	156
	157
	158	/**
	159	* nfs_release_request - Release the count on an NFS read/write request
	160	* @req: request to release
	161	*
	162	* Note: Should never be called with the spinlock held!
	163	*/
	164	void
	165	nfs_release_request(struct nfs_page *req)
	166	{
	167	if (!atomic_dec_and_test(&req->wb_count))
	168	return;
	169
	170	#ifdef NFS_PARANOIA
	171	BUG_ON (!list_empty(&req->wb_list));
	172	BUG_ON (NFS_WBACK_BUSY(req));
	173	#endif
	174
	175	/* Release struct file or cached credential */
	176	nfs_clear_request(req);
	177	put_nfs_open_context(req->wb_context);
	178	nfs_page_free(req);
	179	}
	180
464a98bd TM	181	static int nfs_wait_bit_interruptible(void *word)
	182	{
	183	int ret = 0;
	184
	185	if (signal_pending(current))
	186	ret = -ERESTARTSYS;
	187	else
	188	schedule();
	189	return ret;
	190	}
	191
1da177e4 LT	192	/**
	193	* nfs_wait_on_request - Wait for a request to complete.
	194	* @req: request to wait upon.
	195	*
	196	* Interruptible by signals only if mounted with intr flag.
	197	* The user is responsible for holding a count on the request.
	198	*/
	199	int
	200	nfs_wait_on_request(struct nfs_page *req)
	201	{
464a98bd TM	202	struct rpc_clnt *clnt = NFS_CLIENT(req->wb_context->dentry->d_inode);
	203	sigset_t oldmask;
	204	int ret = 0;
	205
	206	if (!test_bit(PG_BUSY, &req->wb_flags))
	207	goto out;
	208	/*
	209	* Note: the call to rpc_clnt_sigmask() suffices to ensure that we
	210	* are not interrupted if intr flag is not set
	211	*/
	212	rpc_clnt_sigmask(clnt, &oldmask);
	213	ret = out_of_line_wait_on_bit(&req->wb_flags, PG_BUSY,
	214	nfs_wait_bit_interruptible, TASK_INTERRUPTIBLE);
	215	rpc_clnt_sigunmask(clnt, &oldmask);
	216	out:
	217	return ret;
1da177e4 LT	218	}
	219
	220	/**
d8a5ad75 TM	221	* nfs_pageio_init - initialise a page io descriptor
d8a5ad75 TM	222	* @desc: pointer to descriptor
bcb71bba TM	223	* @inode: pointer to inode
	224	* @doio: pointer to io function
	225	* @bsize: io block size
	226	* @io_flags: extra parameters for the io function
d8a5ad75	227	*/
bcb71bba TM	228	void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
bcb71bba TM	229	struct inode *inode,
8d5658c9	230	int (doio)(struct inode , struct list_head *, unsigned int, size_t, int),
bcb71bba TM	231	unsigned int bsize,
bcb71bba TM	232	int io_flags)
d8a5ad75 TM	233	{
d8a5ad75 TM	234	INIT_LIST_HEAD(&desc->pg_list);
bcb71bba	235	desc->pg_bytes_written = 0;
d8a5ad75 TM	236	desc->pg_count = 0;
	237	desc->pg_bsize = bsize;
	238	desc->pg_base = 0;
bcb71bba TM	239	desc->pg_inode = inode;
	240	desc->pg_doio = doio;
	241	desc->pg_ioflags = io_flags;
	242	desc->pg_error = 0;
d8a5ad75 TM	243	}
	244
	245	/**
	246	* nfs_can_coalesce_requests - test two requests for compatibility
	247	* @prev: pointer to nfs_page
	248	* @req: pointer to nfs_page
	249	*
	250	* The nfs_page structures 'prev' and 'req' are compared to ensure that the
	251	* page data area they describe is contiguous, and that their RPC
	252	* credentials, NFSv4 open state, and lockowners are the same.
	253	*
	254	* Return 'true' if this is the case, else return 'false'.
	255	*/
	256	static int nfs_can_coalesce_requests(struct nfs_page *prev,
	257	struct nfs_page *req)
	258	{
	259	if (req->wb_context->cred != prev->wb_context->cred)
	260	return 0;
	261	if (req->wb_context->lockowner != prev->wb_context->lockowner)
	262	return 0;
	263	if (req->wb_context->state != prev->wb_context->state)
	264	return 0;
	265	if (req->wb_index != (prev->wb_index + 1))
	266	return 0;
	267	if (req->wb_pgbase != 0)
	268	return 0;
	269	if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
	270	return 0;
	271	return 1;
	272	}
	273
	274	/**
bcb71bba	275	* nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
d8a5ad75 TM	276	* @desc: destination io descriptor
	277	* @req: request
	278	*
	279	* Returns true if the request 'req' was successfully coalesced into the
	280	* existing list of pages 'desc'.
	281	*/
bcb71bba TM	282	static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
bcb71bba TM	283	struct nfs_page *req)
d8a5ad75 TM	284	{
	285	size_t newlen = req->wb_bytes;
	286
	287	if (desc->pg_count != 0) {
	288	struct nfs_page *prev;
	289
	290	/*
	291	* FIXME: ideally we should be able to coalesce all requests
	292	* that are not block boundary aligned, but currently this
	293	* is problematic for the case of bsize < PAGE_CACHE_SIZE,
	294	* since nfs_flush_multi and nfs_pagein_multi assume you
	295	* can have only one struct nfs_page.
	296	*/
8d5658c9 TM	297	if (desc->pg_bsize < PAGE_SIZE)
8d5658c9 TM	298	return 0;
d8a5ad75	299	newlen += desc->pg_count;
8d5658c9	300	if (newlen > desc->pg_bsize)
d8a5ad75 TM	301	return 0;
	302	prev = nfs_list_entry(desc->pg_list.prev);
	303	if (!nfs_can_coalesce_requests(prev, req))
	304	return 0;
	305	} else
	306	desc->pg_base = req->wb_pgbase;
	307	nfs_list_remove_request(req);
	308	nfs_list_add_request(req, &desc->pg_list);
	309	desc->pg_count = newlen;
	310	return 1;
	311	}
	312
bcb71bba TM	313	/*
	314	* Helper for nfs_pageio_add_request and nfs_pageio_complete
	315	*/
	316	static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
	317	{
	318	if (!list_empty(&desc->pg_list)) {
	319	int error = desc->pg_doio(desc->pg_inode,
	320	&desc->pg_list,
8d5658c9 TM	321	nfs_page_array_len(desc->pg_base,
8d5658c9 TM	322	desc->pg_count),
bcb71bba TM	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	379	int nfs_scan_list(struct nfs_inode nfsi, struct list_head head,
ca52fec1	380	struct list_head *dst, pgoff_t idx_start,
d2ccddf0	381	unsigned int npages)
1da177e4	382	{
d2ccddf0 TM	383	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
d2ccddf0 TM	384	struct nfs_page *req;
ca52fec1	385	pgoff_t idx_end;
d2ccddf0 TM	386	int found, i;
d2ccddf0 TM	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