[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 <linux/writeback.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'.
 */
static 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_add_list - Split coalesced requests out from a list.
 * @desc: destination io descriptor
 * @head: source list
 *
 * Moves a maximum of 'nmax' elements from one list to another.
 * The elements are checked to ensure that they form a contiguous set
 * of pages, and that the RPC credentials are the same.
 */
void nfs_pageio_add_list(struct nfs_pageio_descriptor *desc,
			 struct list_head *head)
{
	while (!list_empty(head)) {
		struct nfs_page *req = nfs_list_entry(head->next);
		if (!nfs_pageio_add_request(desc, req))
			break;
	}
}

/**
 * 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_dirty - Scan the radix tree for dirty requests
 * @mapping: pointer to address space
 * @wbc: writeback_control structure
 * @dst: Destination list
 *
 * 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
 */
long nfs_scan_dirty(struct address_space *mapping,
			struct writeback_control *wbc,
			struct list_head *dst)
{
	struct nfs_inode *nfsi = NFS_I(mapping->host);
	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
	struct nfs_page *req;
	pgoff_t idx_start, idx_end;
	long res = 0;
	int found, i;

	if (nfsi->ndirty == 0)
		return 0;
	if (wbc->range_cyclic) {
		idx_start = 0;
		idx_end = ULONG_MAX;
	} else if (wbc->range_end == 0) {
		idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
		idx_end = ULONG_MAX;
	} else {
		idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
		idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
	}

	for (;;) {
		unsigned int toscan = NFS_SCAN_MAXENTRIES;

		found = radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree,
				(void **)&pgvec[0], idx_start, toscan,
				NFS_PAGE_TAG_DIRTY);

		/* Did we make progress? */
		if (found <= 0)
			break;

		for (i = 0; i < found; i++) {
			req = pgvec[i];
			if (!wbc->range_cyclic && req->wb_index > idx_end)
				goto out;

			/* Try to lock request and mark it for writeback */
			if (!nfs_set_page_writeback_locked(req))
				goto next;
			radix_tree_tag_clear(&nfsi->nfs_page_tree,
					req->wb_index, NFS_PAGE_TAG_DIRTY);
			nfsi->ndirty--;
			nfs_list_remove_request(req);
			nfs_list_add_request(req, dst);
			res++;
			if (res == LONG_MAX)
				goto out;
next:
			idx_start = req->wb_index + 1;
		}
	}
out:
	WARN_ON ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty));
	return res;
}

/**
 * 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>
3f442547	20	#include <linux/writeback.h>
1da177e4 LT	21
	22	#define NFS_PARANOIA 1
	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
	53	* create two different requests for the same page, and avoids
	54	* a possible deadlock when we reach the hard limit on the number
	55	* of dirty pages.
	56	* User should ensure it is safe to sleep in this function.
	57	*/
	58	struct nfs_page *
	59	nfs_create_request(struct nfs_open_context ctx, struct inode inode,
	60	struct page *page,
	61	unsigned int offset, unsigned int count)
	62	{
	63	struct nfs_server *server = NFS_SERVER(inode);
	64	struct nfs_page *req;
	65
	66	/* Deal with hard limits. */
	67	for (;;) {
	68	/* try to allocate the request struct */
	69	req = nfs_page_alloc();
	70	if (req != NULL)
	71	break;
	72
	73	/* Try to free up at least one request in order to stay
	74	* below the hard limit
	75	*/
	76	if (signalled() && (server->flags & NFS_MOUNT_INTR))
	77	return ERR_PTR(-ERESTARTSYS);
	78	yield();
	79	}
	80
	81	/* Initialize the request struct. Initially, we assume a
	82	* long write-back delay. This will be adjusted in
	83	* update_nfs_request below if the region is not locked. */
	84	req->wb_page = page;
	85	atomic_set(&req->wb_complete, 0);
	86	req->wb_index = page->index;
	87	page_cache_get(page);
cd52ed35 TM	88	BUG_ON(PagePrivate(page));
	89	BUG_ON(!PageLocked(page));
	90	BUG_ON(page->mapping->host != inode);
1da177e4 LT	91	req->wb_offset = offset;
	92	req->wb_pgbase = offset;
	93	req->wb_bytes = count;
	94	atomic_set(&req->wb_count, 1);
	95	req->wb_context = get_nfs_open_context(ctx);
	96
	97	return req;
	98	}
	99
	100	/**
	101	* nfs_unlock_request - Unlock request and wake up sleepers.
	102	* @req:
	103	*/
	104	void nfs_unlock_request(struct nfs_page *req)
	105	{
	106	if (!NFS_WBACK_BUSY(req)) {
	107	printk(KERN_ERR "NFS: Invalid unlock attempted\n");
	108	BUG();
	109	}
	110	smp_mb__before_clear_bit();
	111	clear_bit(PG_BUSY, &req->wb_flags);
	112	smp_mb__after_clear_bit();
464a98bd	113	wake_up_bit(&req->wb_flags, PG_BUSY);
1da177e4 LT	114	nfs_release_request(req);
	115	}
	116
c6a556b8 TM	117	/**
	118	* nfs_set_page_writeback_locked - Lock a request for writeback
	119	* @req:
	120	*/
	121	int nfs_set_page_writeback_locked(struct nfs_page *req)
	122	{
	123	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
	124
	125	if (!nfs_lock_request(req))
	126	return 0;
	127	radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
	128	return 1;
	129	}
	130
	131	/**
	132	* nfs_clear_page_writeback - Unlock request and wake up sleepers
	133	*/
	134	void nfs_clear_page_writeback(struct nfs_page *req)
	135	{
	136	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
	137
deb7d638 TM	138	if (req->wb_page != NULL) {
	139	spin_lock(&nfsi->req_lock);
	140	radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
	141	spin_unlock(&nfsi->req_lock);
	142	}
c6a556b8 TM	143	nfs_unlock_request(req);
	144	}
	145
1da177e4 LT	146	/**
	147	* nfs_clear_request - Free up all resources allocated to the request
	148	* @req:
	149	*
	150	* Release page resources associated with a write request after it
	151	* has completed.
	152	*/
	153	void nfs_clear_request(struct nfs_page *req)
	154	{
cd52ed35 TM	155	struct page *page = req->wb_page;
cd52ed35 TM	156	if (page != NULL) {
cd52ed35	157	page_cache_release(page);
1da177e4 LT	158	req->wb_page = NULL;
	159	}
	160	}
	161
	162
	163	/**
	164	* nfs_release_request - Release the count on an NFS read/write request
	165	* @req: request to release
	166	*
	167	* Note: Should never be called with the spinlock held!
	168	*/
	169	void
	170	nfs_release_request(struct nfs_page *req)
	171	{
	172	if (!atomic_dec_and_test(&req->wb_count))
	173	return;
	174
	175	#ifdef NFS_PARANOIA
	176	BUG_ON (!list_empty(&req->wb_list));
	177	BUG_ON (NFS_WBACK_BUSY(req));
	178	#endif
	179
	180	/* Release struct file or cached credential */
	181	nfs_clear_request(req);
	182	put_nfs_open_context(req->wb_context);
	183	nfs_page_free(req);
	184	}
	185
464a98bd TM	186	static int nfs_wait_bit_interruptible(void *word)
	187	{
	188	int ret = 0;
	189
	190	if (signal_pending(current))
	191	ret = -ERESTARTSYS;
	192	else
	193	schedule();
	194	return ret;
	195	}
	196
1da177e4 LT	197	/**
	198	* nfs_wait_on_request - Wait for a request to complete.
	199	* @req: request to wait upon.
	200	*
	201	* Interruptible by signals only if mounted with intr flag.
	202	* The user is responsible for holding a count on the request.
	203	*/
	204	int
	205	nfs_wait_on_request(struct nfs_page *req)
	206	{
464a98bd TM	207	struct rpc_clnt *clnt = NFS_CLIENT(req->wb_context->dentry->d_inode);
	208	sigset_t oldmask;
	209	int ret = 0;
	210
	211	if (!test_bit(PG_BUSY, &req->wb_flags))
	212	goto out;
	213	/*
	214	* Note: the call to rpc_clnt_sigmask() suffices to ensure that we
	215	* are not interrupted if intr flag is not set
	216	*/
	217	rpc_clnt_sigmask(clnt, &oldmask);
	218	ret = out_of_line_wait_on_bit(&req->wb_flags, PG_BUSY,
	219	nfs_wait_bit_interruptible, TASK_INTERRUPTIBLE);
	220	rpc_clnt_sigunmask(clnt, &oldmask);
	221	out:
	222	return ret;
1da177e4 LT	223	}
	224
	225	/**
d8a5ad75 TM	226	* nfs_pageio_init - initialise a page io descriptor
d8a5ad75 TM	227	* @desc: pointer to descriptor
bcb71bba TM	228	* @inode: pointer to inode
	229	* @doio: pointer to io function
	230	* @bsize: io block size
	231	* @io_flags: extra parameters for the io function
d8a5ad75	232	*/
bcb71bba TM	233	void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
	234	struct inode *inode,
	235	int (doio)(struct inode , struct list_head *, size_t, int),
	236	unsigned int bsize,
	237	int io_flags)
d8a5ad75 TM	238	{
d8a5ad75 TM	239	INIT_LIST_HEAD(&desc->pg_list);
bcb71bba	240	desc->pg_bytes_written = 0;
d8a5ad75 TM	241	desc->pg_count = 0;
	242	desc->pg_bsize = bsize;
	243	desc->pg_base = 0;
bcb71bba TM	244	desc->pg_inode = inode;
	245	desc->pg_doio = doio;
	246	desc->pg_ioflags = io_flags;
	247	desc->pg_error = 0;
d8a5ad75 TM	248	}
	249
	250	/**
	251	* nfs_can_coalesce_requests - test two requests for compatibility
	252	* @prev: pointer to nfs_page
	253	* @req: pointer to nfs_page
	254	*
	255	* The nfs_page structures 'prev' and 'req' are compared to ensure that the
	256	* page data area they describe is contiguous, and that their RPC
	257	* credentials, NFSv4 open state, and lockowners are the same.
	258	*
	259	* Return 'true' if this is the case, else return 'false'.
	260	*/
	261	static int nfs_can_coalesce_requests(struct nfs_page *prev,
	262	struct nfs_page *req)
	263	{
	264	if (req->wb_context->cred != prev->wb_context->cred)
	265	return 0;
	266	if (req->wb_context->lockowner != prev->wb_context->lockowner)
	267	return 0;
	268	if (req->wb_context->state != prev->wb_context->state)
	269	return 0;
	270	if (req->wb_index != (prev->wb_index + 1))
	271	return 0;
	272	if (req->wb_pgbase != 0)
	273	return 0;
	274	if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
	275	return 0;
	276	return 1;
	277	}
	278
	279	/**
bcb71bba	280	* nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
d8a5ad75 TM	281	* @desc: destination io descriptor
	282	* @req: request
	283	*
	284	* Returns true if the request 'req' was successfully coalesced into the
	285	* existing list of pages 'desc'.
	286	*/
bcb71bba TM	287	static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
bcb71bba TM	288	struct nfs_page *req)
d8a5ad75 TM	289	{
	290	size_t newlen = req->wb_bytes;
	291
	292	if (desc->pg_count != 0) {
	293	struct nfs_page *prev;
	294
	295	/*
	296	* FIXME: ideally we should be able to coalesce all requests
	297	* that are not block boundary aligned, but currently this
	298	* is problematic for the case of bsize < PAGE_CACHE_SIZE,
	299	* since nfs_flush_multi and nfs_pagein_multi assume you
	300	* can have only one struct nfs_page.
	301	*/
	302	newlen += desc->pg_count;
	303	if (desc->pg_base + newlen > desc->pg_bsize)
	304	return 0;
	305	prev = nfs_list_entry(desc->pg_list.prev);
	306	if (!nfs_can_coalesce_requests(prev, req))
	307	return 0;
	308	} else
	309	desc->pg_base = req->wb_pgbase;
	310	nfs_list_remove_request(req);
	311	nfs_list_add_request(req, &desc->pg_list);
	312	desc->pg_count = newlen;
	313	return 1;
	314	}
	315
bcb71bba TM	316	/*
	317	* Helper for nfs_pageio_add_request and nfs_pageio_complete
	318	*/
	319	static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
	320	{
	321	if (!list_empty(&desc->pg_list)) {
	322	int error = desc->pg_doio(desc->pg_inode,
	323	&desc->pg_list,
	324	desc->pg_count,
	325	desc->pg_ioflags);
	326	if (error < 0)
	327	desc->pg_error = error;
	328	else
	329	desc->pg_bytes_written += desc->pg_count;
	330	}
	331	if (list_empty(&desc->pg_list)) {
	332	desc->pg_count = 0;
	333	desc->pg_base = 0;
	334	}
	335	}
	336
	337	/**
	338	* nfs_pageio_add_request - Attempt to coalesce a request into a page list.
	339	* @desc: destination io descriptor
	340	* @req: request
	341	*
	342	* Returns true if the request 'req' was successfully coalesced into the
	343	* existing list of pages 'desc'.
	344	*/
	345	static int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
	346	struct nfs_page *req)
	347	{
	348	while (!nfs_pageio_do_add_request(desc, req)) {
	349	nfs_pageio_doio(desc);
	350	if (desc->pg_error < 0)
	351	return 0;
	352	}
	353	return 1;
	354	}
	355
d8a5ad75 TM	356	/**
	357	* nfs_pageio_add_list - Split coalesced requests out from a list.
	358	* @desc: destination io descriptor
1da177e4	359	* @head: source list
1da177e4 LT	360	*
	361	* Moves a maximum of 'nmax' elements from one list to another.
	362	* The elements are checked to ensure that they form a contiguous set
	363	* of pages, and that the RPC credentials are the same.
	364	*/
d8a5ad75 TM	365	void nfs_pageio_add_list(struct nfs_pageio_descriptor *desc,
d8a5ad75 TM	366	struct list_head *head)
1da177e4	367	{
1da177e4	368	while (!list_empty(head)) {
d8a5ad75 TM	369	struct nfs_page *req = nfs_list_entry(head->next);
d8a5ad75 TM	370	if (!nfs_pageio_add_request(desc, req))
1da177e4 LT	371	break;
1da177e4 LT	372	}
1da177e4 LT	373	}
1da177e4 LT	374
bcb71bba TM	375	/**
	376	* nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
	377	* @desc: pointer to io descriptor
	378	*/
	379	void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
	380	{
	381	nfs_pageio_doio(desc);
	382	}
	383
3da28eb1 TM	384	#define NFS_SCAN_MAXENTRIES 16
3da28eb1 TM	385	/**
3f442547 TM	386	* nfs_scan_dirty - Scan the radix tree for dirty requests
	387	* @mapping: pointer to address space
	388	* @wbc: writeback_control structure
3da28eb1	389	* @dst: Destination list
3da28eb1 TM	390	*
	391	* Moves elements from one of the inode request lists.
	392	* If the number of requests is set to 0, the entire address_space
	393	* starting at index idx_start, is scanned.
	394	* The requests are not checked to ensure that they form a contiguous set.
	395	* You must be holding the inode's req_lock when calling this function
	396	*/
3f442547 TM	397	long nfs_scan_dirty(struct address_space *mapping,
	398	struct writeback_control *wbc,
	399	struct list_head *dst)
3da28eb1	400	{
3f442547	401	struct nfs_inode *nfsi = NFS_I(mapping->host);
3da28eb1 TM	402	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
3da28eb1 TM	403	struct nfs_page *req;
3f442547	404	pgoff_t idx_start, idx_end;
3f442547	405	long res = 0;
3da28eb1	406	int found, i;
3da28eb1	407
9cf85e0a	408	if (nfsi->ndirty == 0)
3f442547 TM	409	return 0;
	410	if (wbc->range_cyclic) {
	411	idx_start = 0;
	412	idx_end = ULONG_MAX;
	413	} else if (wbc->range_end == 0) {
	414	idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
	415	idx_end = ULONG_MAX;
	416	} else {
	417	idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
	418	idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
	419	}
3da28eb1 TM	420
3da28eb1 TM	421	for (;;) {
3f442547 TM	422	unsigned int toscan = NFS_SCAN_MAXENTRIES;
3f442547 TM	423
3da28eb1	424	found = radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree,
3f442547	425	(void **)&pgvec[0], idx_start, toscan,
3da28eb1	426	NFS_PAGE_TAG_DIRTY);
3f442547 TM	427
3f442547 TM	428	/* Did we make progress? */
3da28eb1 TM	429	if (found <= 0)
3da28eb1 TM	430	break;
3f442547	431
3da28eb1 TM	432	for (i = 0; i < found; i++) {
3da28eb1 TM	433	req = pgvec[i];
3f442547	434	if (!wbc->range_cyclic && req->wb_index > idx_end)
3da28eb1 TM	435	goto out;
3da28eb1 TM	436
3f442547 TM	437	/* Try to lock request and mark it for writeback */
	438	if (!nfs_set_page_writeback_locked(req))
	439	goto next;
	440	radix_tree_tag_clear(&nfsi->nfs_page_tree,
	441	req->wb_index, NFS_PAGE_TAG_DIRTY);
	442	nfsi->ndirty--;
	443	nfs_list_remove_request(req);
	444	nfs_list_add_request(req, dst);
3f442547 TM	445	res++;
	446	if (res == LONG_MAX)
	447	goto out;
3f442547 TM	448	next:
3f442547 TM	449	idx_start = req->wb_index + 1;
3da28eb1 TM	450	}
	451	}
	452	out:
3f442547	453	WARN_ON ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty));
3da28eb1 TM	454	return res;
	455	}
	456
1da177e4 LT	457	/**
1da177e4 LT	458	* nfs_scan_list - Scan a list for matching requests
d2ccddf0	459	* @nfsi: NFS inode
1da177e4 LT	460	* @head: One of the NFS inode request lists
	461	* @dst: Destination list
	462	* @idx_start: lower bound of page->index to scan
	463	* @npages: idx_start + npages sets the upper bound to scan.
	464	*
	465	* Moves elements from one of the inode request lists.
	466	* If the number of requests is set to 0, the entire address_space
	467	* starting at index idx_start, is scanned.
	468	* The requests are not checked to ensure that they form a contiguous set.
	469	* You must be holding the inode's req_lock when calling this function
	470	*/
d2ccddf0 TM	471	int nfs_scan_list(struct nfs_inode nfsi, struct list_head head,
	472	struct list_head *dst, unsigned long idx_start,
	473	unsigned int npages)
1da177e4	474	{
d2ccddf0 TM	475	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
	476	struct nfs_page *req;
	477	unsigned long idx_end;
	478	int found, i;
	479	int res;
1da177e4 LT	480
	481	res = 0;
	482	if (npages == 0)
	483	idx_end = ~0;
	484	else
	485	idx_end = idx_start + npages - 1;
	486
d2ccddf0 TM	487	for (;;) {
	488	found = radix_tree_gang_lookup(&nfsi->nfs_page_tree,
	489	(void **)&pgvec[0], idx_start,
	490	NFS_SCAN_MAXENTRIES);
	491	if (found <= 0)
1da177e4	492	break;
d2ccddf0 TM	493	for (i = 0; i < found; i++) {
	494	req = pgvec[i];
	495	if (req->wb_index > idx_end)
	496	goto out;
	497	idx_start = req->wb_index + 1;
	498	if (req->wb_list_head != head)
	499	continue;
	500	if (nfs_set_page_writeback_locked(req)) {
	501	nfs_list_remove_request(req);
	502	nfs_list_add_request(req, dst);
	503	res++;
	504	}
	505	}
1da177e4	506
1da177e4	507	}
d2ccddf0	508	out:
1da177e4 LT	509	return res;
	510	}
	511
f7b422b1	512	int __init nfs_init_nfspagecache(void)
1da177e4 LT	513	{
	514	nfs_page_cachep = kmem_cache_create("nfs_page",
	515	sizeof(struct nfs_page),
	516	0, SLAB_HWCACHE_ALIGN,
	517	NULL, NULL);
	518	if (nfs_page_cachep == NULL)
	519	return -ENOMEM;
	520
	521	return 0;
	522	}
	523
266bee88	524	void nfs_destroy_nfspagecache(void)
1da177e4	525	{
1a1d92c1	526	kmem_cache_destroy(nfs_page_cachep);
1da177e4 LT	527	}
1da177e4 LT	528