pagelist.c 27.4 KB
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/*
 * 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>
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#include <linux/sched.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/nfs.h>
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#include <linux/nfs3.h>
#include <linux/nfs4.h>
#include <linux/nfs_page.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
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#include <linux/export.h>
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#include "internal.h"
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#include "pnfs.h"
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#define NFSDBG_FACILITY		NFSDBG_PAGECACHE

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static struct kmem_cache *nfs_page_cachep;
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static const struct rpc_call_ops nfs_pgio_common_ops;
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static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
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{
	p->npages = pagecount;
	if (pagecount <= ARRAY_SIZE(p->page_array))
		p->pagevec = p->page_array;
	else {
		p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_KERNEL);
		if (!p->pagevec)
			p->npages = 0;
	}
	return p->pagevec != NULL;
}

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void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
		       struct nfs_pgio_header *hdr,
		       void (*release)(struct nfs_pgio_header *hdr))
{
	hdr->req = nfs_list_entry(desc->pg_list.next);
	hdr->inode = desc->pg_inode;
	hdr->cred = hdr->req->wb_context->cred;
	hdr->io_start = req_offset(hdr->req);
	hdr->good_bytes = desc->pg_count;
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	hdr->dreq = desc->pg_dreq;
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	hdr->layout_private = desc->pg_layout_private;
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	hdr->release = release;
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	hdr->completion_ops = desc->pg_completion_ops;
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	if (hdr->completion_ops->init_hdr)
		hdr->completion_ops->init_hdr(hdr);
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}
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EXPORT_SYMBOL_GPL(nfs_pgheader_init);
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void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
{
	spin_lock(&hdr->lock);
	if (pos < hdr->io_start + hdr->good_bytes) {
		set_bit(NFS_IOHDR_ERROR, &hdr->flags);
		clear_bit(NFS_IOHDR_EOF, &hdr->flags);
		hdr->good_bytes = pos - hdr->io_start;
		hdr->error = error;
	}
	spin_unlock(&hdr->lock);
}

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static inline struct nfs_page *
nfs_page_alloc(void)
{
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	struct nfs_page	*p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
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	if (p)
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		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);
}

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static void
nfs_iocounter_inc(struct nfs_io_counter *c)
{
	atomic_inc(&c->io_count);
}

static void
nfs_iocounter_dec(struct nfs_io_counter *c)
{
	if (atomic_dec_and_test(&c->io_count)) {
		clear_bit(NFS_IO_INPROGRESS, &c->flags);
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		smp_mb__after_atomic();
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		wake_up_bit(&c->flags, NFS_IO_INPROGRESS);
	}
}

static int
__nfs_iocounter_wait(struct nfs_io_counter *c)
{
	wait_queue_head_t *wq = bit_waitqueue(&c->flags, NFS_IO_INPROGRESS);
	DEFINE_WAIT_BIT(q, &c->flags, NFS_IO_INPROGRESS);
	int ret = 0;

	do {
		prepare_to_wait(wq, &q.wait, TASK_KILLABLE);
		set_bit(NFS_IO_INPROGRESS, &c->flags);
		if (atomic_read(&c->io_count) == 0)
			break;
		ret = nfs_wait_bit_killable(&c->flags);
	} while (atomic_read(&c->io_count) != 0);
	finish_wait(wq, &q.wait);
	return ret;
}

/**
 * nfs_iocounter_wait - wait for i/o to complete
 * @c: nfs_io_counter to use
 *
 * returns -ERESTARTSYS if interrupted by a fatal signal.
 * Otherwise returns 0 once the io_count hits 0.
 */
int
nfs_iocounter_wait(struct nfs_io_counter *c)
{
	if (atomic_read(&c->io_count) == 0)
		return 0;
	return __nfs_iocounter_wait(c);
}

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static int nfs_wait_bit_uninterruptible(void *word)
{
	io_schedule();
	return 0;
}

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/*
 * nfs_page_group_lock - lock the head of the page group
 * @req - request in group that is to be locked
 *
 * this lock must be held if modifying the page group list
 */
void
nfs_page_group_lock(struct nfs_page *req)
{
	struct nfs_page *head = req->wb_head;

	WARN_ON_ONCE(head != head->wb_head);

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	wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
			nfs_wait_bit_uninterruptible,
			TASK_UNINTERRUPTIBLE);
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}

/*
 * nfs_page_group_unlock - unlock the head of the page group
 * @req - request in group that is to be unlocked
 */
void
nfs_page_group_unlock(struct nfs_page *req)
{
	struct nfs_page *head = req->wb_head;

	WARN_ON_ONCE(head != head->wb_head);

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	smp_mb__before_atomic();
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	clear_bit(PG_HEADLOCK, &head->wb_flags);
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	smp_mb__after_atomic();
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	wake_up_bit(&head->wb_flags, PG_HEADLOCK);
}

/*
 * nfs_page_group_sync_on_bit_locked
 *
 * must be called with page group lock held
 */
static bool
nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
{
	struct nfs_page *head = req->wb_head;
	struct nfs_page *tmp;

	WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
	WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));

	tmp = req->wb_this_page;
	while (tmp != req) {
		if (!test_bit(bit, &tmp->wb_flags))
			return false;
		tmp = tmp->wb_this_page;
	}

	/* true! reset all bits */
	tmp = req;
	do {
		clear_bit(bit, &tmp->wb_flags);
		tmp = tmp->wb_this_page;
	} while (tmp != req);

	return true;
}

/*
 * nfs_page_group_sync_on_bit - set bit on current request, but only
 *   return true if the bit is set for all requests in page group
 * @req - request in page group
 * @bit - PG_* bit that is used to sync page group
 */
bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
{
	bool ret;

	nfs_page_group_lock(req);
	ret = nfs_page_group_sync_on_bit_locked(req, bit);
	nfs_page_group_unlock(req);

	return ret;
}

/*
 * nfs_page_group_init - Initialize the page group linkage for @req
 * @req - a new nfs request
 * @prev - the previous request in page group, or NULL if @req is the first
 *         or only request in the group (the head).
 */
static inline void
nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
{
	WARN_ON_ONCE(prev == req);

	if (!prev) {
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		/* a head request */
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		req->wb_head = req;
		req->wb_this_page = req;
	} else {
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		/* a subrequest */
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		WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
		WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
		req->wb_head = prev->wb_head;
		req->wb_this_page = prev->wb_this_page;
		prev->wb_this_page = req;

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		/* All subrequests take a ref on the head request until
		 * nfs_page_group_destroy is called */
		kref_get(&req->wb_head->wb_kref);

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		/* grab extra ref if head request has extra ref from
		 * the write/commit path to handle handoff between write
		 * and commit lists */
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		if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
			set_bit(PG_INODE_REF, &req->wb_flags);
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			kref_get(&req->wb_kref);
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		}
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	}
}

/*
 * nfs_page_group_destroy - sync the destruction of page groups
 * @req - request that no longer needs the page group
 *
 * releases the page group reference from each member once all
 * members have called this function.
 */
static void
nfs_page_group_destroy(struct kref *kref)
{
	struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
	struct nfs_page *tmp, *next;

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	/* subrequests must release the ref on the head request */
	if (req->wb_head != req)
		nfs_release_request(req->wb_head);

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	if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
		return;

	tmp = req;
	do {
		next = tmp->wb_this_page;
		/* unlink and free */
		tmp->wb_this_page = tmp;
		tmp->wb_head = tmp;
		nfs_free_request(tmp);
		tmp = next;
	} while (tmp != req);
}

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/**
 * nfs_create_request - Create an NFS read/write request.
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 * @ctx: open context to use
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 * @page: page to write
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 * @last: last nfs request created for this page group or NULL if head
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 * @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
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 * create two different requests for the same page.
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 * User should ensure it is safe to sleep in this function.
 */
struct nfs_page *
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nfs_create_request(struct nfs_open_context *ctx, struct page *page,
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		   struct nfs_page *last, unsigned int offset,
		   unsigned int count)
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{
	struct nfs_page		*req;
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	struct nfs_lock_context *l_ctx;
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	if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
		return ERR_PTR(-EBADF);
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	/* try to allocate the request struct */
	req = nfs_page_alloc();
	if (req == NULL)
		return ERR_PTR(-ENOMEM);
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	/* get lock context early so we can deal with alloc failures */
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	l_ctx = nfs_get_lock_context(ctx);
	if (IS_ERR(l_ctx)) {
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		nfs_page_free(req);
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		return ERR_CAST(l_ctx);
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	}
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	req->wb_lock_context = l_ctx;
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	nfs_iocounter_inc(&l_ctx->io_count);
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	/* 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;
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	req->wb_index	= page_file_index(page);
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	page_cache_get(page);
	req->wb_offset  = offset;
	req->wb_pgbase	= offset;
	req->wb_bytes   = count;
	req->wb_context = get_nfs_open_context(ctx);
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	kref_init(&req->wb_kref);
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	nfs_page_group_init(req, last);
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	return req;
}

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

/**
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 * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 * @req:
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 */
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void nfs_unlock_and_release_request(struct nfs_page *req)
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{
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	nfs_unlock_request(req);
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	nfs_release_request(req);
}

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/*
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 * nfs_clear_request - Free up all resources allocated to the request
 * @req:
 *
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 * Release page and open context resources associated with a read/write
 * request after it has completed.
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 */
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static void nfs_clear_request(struct nfs_page *req)
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{
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	struct page *page = req->wb_page;
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	struct nfs_open_context *ctx = req->wb_context;
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	struct nfs_lock_context *l_ctx = req->wb_lock_context;
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	if (page != NULL) {
		page_cache_release(page);
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		req->wb_page = NULL;
	}
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	if (l_ctx != NULL) {
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		nfs_iocounter_dec(&l_ctx->io_count);
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		nfs_put_lock_context(l_ctx);
		req->wb_lock_context = NULL;
	}
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	if (ctx != NULL) {
		put_nfs_open_context(ctx);
		req->wb_context = NULL;
	}
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}

/**
 * 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!
 */
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void nfs_free_request(struct nfs_page *req)
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{
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	WARN_ON_ONCE(req->wb_this_page != req);

	/* extra debug: make sure no sync bits are still set */
	WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
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	WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
	WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
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	WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
	WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
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	/* Release struct file and open context */
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	nfs_clear_request(req);
	nfs_page_free(req);
}

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void nfs_release_request(struct nfs_page *req)
{
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	kref_put(&req->wb_kref, nfs_page_group_destroy);
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}

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/**
 * nfs_wait_on_request - Wait for a request to complete.
 * @req: request to wait upon.
 *
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 * Interruptible by fatal signals only.
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 * The user is responsible for holding a count on the request.
 */
int
nfs_wait_on_request(struct nfs_page *req)
{
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	return wait_on_bit(&req->wb_flags, PG_BUSY,
			nfs_wait_bit_uninterruptible,
			TASK_UNINTERRUPTIBLE);
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}

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/*
 * nfs_generic_pg_test - determine if requests can be coalesced
 * @desc: pointer to descriptor
 * @prev: previous request in desc, or NULL
 * @req: this request
 *
 * Returns zero if @req can be coalesced into @desc, otherwise it returns
 * the size of the request.
 */
size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
			   struct nfs_page *prev, struct nfs_page *req)
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{
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	if (desc->pg_count > desc->pg_bsize) {
		/* should never happen */
		WARN_ON_ONCE(1);
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		return 0;
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	}
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	return min(desc->pg_bsize - desc->pg_count, (size_t)req->wb_bytes);
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}
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EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
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static inline struct nfs_rw_header *NFS_RW_HEADER(struct nfs_pgio_header *hdr)
{
	return container_of(hdr, struct nfs_rw_header, header);
}

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/**
 * nfs_rw_header_alloc - Allocate a header for a read or write
 * @ops: Read or write function vector
 */
struct nfs_rw_header *nfs_rw_header_alloc(const struct nfs_rw_ops *ops)
{
	struct nfs_rw_header *header = ops->rw_alloc_header();

	if (header) {
		struct nfs_pgio_header *hdr = &header->header;

		INIT_LIST_HEAD(&hdr->pages);
		spin_lock_init(&hdr->lock);
		atomic_set(&hdr->refcnt, 0);
		hdr->rw_ops = ops;
	}
	return header;
}
EXPORT_SYMBOL_GPL(nfs_rw_header_alloc);

/*
 * nfs_rw_header_free - Free a read or write header
 * @hdr: The header to free
 */
void nfs_rw_header_free(struct nfs_pgio_header *hdr)
{
	hdr->rw_ops->rw_free_header(NFS_RW_HEADER(hdr));
}
EXPORT_SYMBOL_GPL(nfs_rw_header_free);

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/**
 * nfs_pgio_data_alloc - Allocate pageio data
 * @hdr: The header making a request
 * @pagecount: Number of pages to create
 */
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static struct nfs_pgio_data *nfs_pgio_data_alloc(struct nfs_pgio_header *hdr,
						 unsigned int pagecount)
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{
	struct nfs_pgio_data *data, *prealloc;

	prealloc = &NFS_RW_HEADER(hdr)->rpc_data;
	if (prealloc->header == NULL)
		data = prealloc;
	else
		data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (!data)
		goto out;

	if (nfs_pgarray_set(&data->pages, pagecount)) {
		data->header = hdr;
		atomic_inc(&hdr->refcnt);
	} else {
		if (data != prealloc)
			kfree(data);
		data = NULL;
	}
out:
	return data;
}

/**
 * nfs_pgio_data_release - Properly free pageio data
 * @data: The data to release
 */
void nfs_pgio_data_release(struct nfs_pgio_data *data)
{
	struct nfs_pgio_header *hdr = data->header;
	struct nfs_rw_header *pageio_header = NFS_RW_HEADER(hdr);

	put_nfs_open_context(data->args.context);
	if (data->pages.pagevec != data->pages.page_array)
		kfree(data->pages.pagevec);
	if (data == &pageio_header->rpc_data) {
		data->header = NULL;
		data = NULL;
	}
	if (atomic_dec_and_test(&hdr->refcnt))
		hdr->completion_ops->completion(hdr);
	/* Note: we only free the rpc_task after callbacks are done.
	 * See the comment in rpc_free_task() for why
	 */
	kfree(data);
}
EXPORT_SYMBOL_GPL(nfs_pgio_data_release);

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/**
 * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 * @data: The pageio data
 * @count: Number of bytes to read
 * @offset: Initial offset
 * @how: How to commit data (writes only)
 * @cinfo: Commit information for the call (writes only)
 */
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static void nfs_pgio_rpcsetup(struct nfs_pgio_data *data,
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			      unsigned int count, unsigned int offset,
			      int how, struct nfs_commit_info *cinfo)
{
	struct nfs_page *req = data->header->req;

	/* Set up the RPC argument and reply structs
	 * NB: take care not to mess about with data->commit et al. */

	data->args.fh     = NFS_FH(data->header->inode);
	data->args.offset = req_offset(req) + offset;
	/* pnfs_set_layoutcommit needs this */
	data->mds_offset = data->args.offset;
	data->args.pgbase = req->wb_pgbase + offset;
	data->args.pages  = data->pages.pagevec;
	data->args.count  = count;
	data->args.context = get_nfs_open_context(req->wb_context);
	data->args.lock_context = req->wb_lock_context;
	data->args.stable  = NFS_UNSTABLE;
	switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
	case 0:
		break;
	case FLUSH_COND_STABLE:
		if (nfs_reqs_to_commit(cinfo))
			break;
	default:
		data->args.stable = NFS_FILE_SYNC;
	}

	data->res.fattr   = &data->fattr;
	data->res.count   = count;
	data->res.eof     = 0;
	data->res.verf    = &data->verf;
	nfs_fattr_init(&data->fattr);
}

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/**
 * nfs_pgio_prepare - Prepare pageio data to go over the wire
 * @task: The current task
 * @calldata: pageio data to prepare
 */
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static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
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{
	struct nfs_pgio_data *data = calldata;
	int err;
	err = NFS_PROTO(data->header->inode)->pgio_rpc_prepare(task, data);
	if (err)
		rpc_exit(task, err);
}

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int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_data *data,
		      const struct rpc_call_ops *call_ops, int how, int flags)
{
	struct rpc_task *task;
	struct rpc_message msg = {
		.rpc_argp = &data->args,
		.rpc_resp = &data->res,
		.rpc_cred = data->header->cred,
	};
	struct rpc_task_setup task_setup_data = {
		.rpc_client = clnt,
		.task = &data->task,
		.rpc_message = &msg,
		.callback_ops = call_ops,
		.callback_data = data,
		.workqueue = nfsiod_workqueue,
		.flags = RPC_TASK_ASYNC | flags,
	};
	int ret = 0;

	data->header->rw_ops->rw_initiate(data, &msg, &task_setup_data, how);

	dprintk("NFS: %5u initiated pgio call "
		"(req %s/%llu, %u bytes @ offset %llu)\n",
		data->task.tk_pid,
		data->header->inode->i_sb->s_id,
		(unsigned long long)NFS_FILEID(data->header->inode),
		data->args.count,
		(unsigned long long)data->args.offset);

	task = rpc_run_task(&task_setup_data);
	if (IS_ERR(task)) {
		ret = PTR_ERR(task);
		goto out;
	}
	if (how & FLUSH_SYNC) {
		ret = rpc_wait_for_completion_task(task);
		if (ret == 0)
			ret = task->tk_status;
	}
	rpc_put_task(task);
out:
	return ret;
}
EXPORT_SYMBOL_GPL(nfs_initiate_pgio);

659 660 661 662 663
/**
 * nfs_pgio_error - Clean up from a pageio error
 * @desc: IO descriptor
 * @hdr: pageio header
 */
664
static int nfs_pgio_error(struct nfs_pageio_descriptor *desc,
665 666 667
			  struct nfs_pgio_header *hdr)
{
	set_bit(NFS_IOHDR_REDO, &hdr->flags);
668 669
	nfs_pgio_data_release(hdr->data);
	hdr->data = NULL;
670 671 672 673
	desc->pg_completion_ops->error_cleanup(&desc->pg_list);
	return -ENOMEM;
}

674 675 676 677
/**
 * nfs_pgio_release - Release pageio data
 * @calldata: The pageio data to release
 */
678
static void nfs_pgio_release(void *calldata)
679 680 681 682 683 684 685
{
	struct nfs_pgio_data *data = calldata;
	if (data->header->rw_ops->rw_release)
		data->header->rw_ops->rw_release(data);
	nfs_pgio_data_release(data);
}

L
Linus Torvalds 已提交
686
/**
687 688
 * nfs_pageio_init - initialise a page io descriptor
 * @desc: pointer to descriptor
689 690 691 692
 * @inode: pointer to inode
 * @doio: pointer to io function
 * @bsize: io block size
 * @io_flags: extra parameters for the io function
693
 */
694 695
void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
		     struct inode *inode,
696
		     const struct nfs_pageio_ops *pg_ops,
697
		     const struct nfs_pgio_completion_ops *compl_ops,
698
		     const struct nfs_rw_ops *rw_ops,
699
		     size_t bsize,
700
		     int io_flags)
701 702
{
	INIT_LIST_HEAD(&desc->pg_list);
703
	desc->pg_bytes_written = 0;
704 705 706
	desc->pg_count = 0;
	desc->pg_bsize = bsize;
	desc->pg_base = 0;
707
	desc->pg_moreio = 0;
708
	desc->pg_recoalesce = 0;
709
	desc->pg_inode = inode;
710
	desc->pg_ops = pg_ops;
711
	desc->pg_completion_ops = compl_ops;
712
	desc->pg_rw_ops = rw_ops;
713 714
	desc->pg_ioflags = io_flags;
	desc->pg_error = 0;
715
	desc->pg_lseg = NULL;
716
	desc->pg_dreq = NULL;
717
	desc->pg_layout_private = NULL;
718
}
B
Bryan Schumaker 已提交
719
EXPORT_SYMBOL_GPL(nfs_pageio_init);
720

721 722 723 724 725
/**
 * nfs_pgio_result - Basic pageio error handling
 * @task: The task that ran
 * @calldata: Pageio data to check
 */
726
static void nfs_pgio_result(struct rpc_task *task, void *calldata)
727 728 729 730 731 732 733 734 735 736 737 738 739 740 741
{
	struct nfs_pgio_data *data = calldata;
	struct inode *inode = data->header->inode;

	dprintk("NFS: %s: %5u, (status %d)\n", __func__,
		task->tk_pid, task->tk_status);

	if (data->header->rw_ops->rw_done(task, data, inode) != 0)
		return;
	if (task->tk_status < 0)
		nfs_set_pgio_error(data->header, task->tk_status, data->args.offset);
	else
		data->header->rw_ops->rw_result(task, data);
}

742 743 744 745 746 747 748 749
/*
 * Create an RPC task for the given read or write request and kick it.
 * The page must have been locked by the caller.
 *
 * It may happen that the page we're passed is not marked dirty.
 * This is the case if nfs_updatepage detects a conflicting request
 * that has been written but not committed.
 */
750 751
int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
		     struct nfs_pgio_header *hdr)
752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778
{
	struct nfs_page		*req;
	struct page		**pages;
	struct nfs_pgio_data	*data;
	struct list_head *head = &desc->pg_list;
	struct nfs_commit_info cinfo;

	data = nfs_pgio_data_alloc(hdr, nfs_page_array_len(desc->pg_base,
							   desc->pg_count));
	if (!data)
		return nfs_pgio_error(desc, hdr);

	nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
	pages = data->pages.pagevec;
	while (!list_empty(head)) {
		req = nfs_list_entry(head->next);
		nfs_list_remove_request(req);
		nfs_list_add_request(req, &hdr->pages);
		*pages++ = req->wb_page;
	}

	if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
	    (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
		desc->pg_ioflags &= ~FLUSH_COND_STABLE;

	/* Set up the argument struct */
	nfs_pgio_rpcsetup(data, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
779
	hdr->data = data;
780 781 782
	desc->pg_rpc_callops = &nfs_pgio_common_ops;
	return 0;
}
783
EXPORT_SYMBOL_GPL(nfs_generic_pgio);
784

785
static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
786 787 788 789 790 791 792 793 794 795 796 797 798 799 800
{
	struct nfs_rw_header *rw_hdr;
	struct nfs_pgio_header *hdr;
	int ret;

	rw_hdr = nfs_rw_header_alloc(desc->pg_rw_ops);
	if (!rw_hdr) {
		desc->pg_completion_ops->error_cleanup(&desc->pg_list);
		return -ENOMEM;
	}
	hdr = &rw_hdr->header;
	nfs_pgheader_init(desc, hdr, nfs_rw_header_free);
	atomic_inc(&hdr->refcnt);
	ret = nfs_generic_pgio(desc, hdr);
	if (ret == 0)
801 802 803
		ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
					hdr->data, desc->pg_rpc_callops,
					desc->pg_ioflags, 0);
804 805 806 807 808
	if (atomic_dec_and_test(&hdr->refcnt))
		hdr->completion_ops->completion(hdr);
	return ret;
}

809 810 811 812 813 814 815 816 817 818 819 820 821
static bool nfs_match_open_context(const struct nfs_open_context *ctx1,
		const struct nfs_open_context *ctx2)
{
	return ctx1->cred == ctx2->cred && ctx1->state == ctx2->state;
}

static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
		const struct nfs_lock_context *l2)
{
	return l1->lockowner.l_owner == l2->lockowner.l_owner
		&& l1->lockowner.l_pid == l2->lockowner.l_pid;
}

822 823 824 825 826 827 828 829 830 831 832
/**
 * 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'.
 */
833 834 835
static bool nfs_can_coalesce_requests(struct nfs_page *prev,
				      struct nfs_page *req,
				      struct nfs_pageio_descriptor *pgio)
836
{
837 838
	size_t size;

839 840 841 842 843 844 845 846 847 848
	if (prev) {
		if (!nfs_match_open_context(req->wb_context, prev->wb_context))
			return false;
		if (req->wb_context->dentry->d_inode->i_flock != NULL &&
		    !nfs_match_lock_context(req->wb_lock_context,
					    prev->wb_lock_context))
			return false;
		if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
			return false;
	}
849
	size = pgio->pg_ops->pg_test(pgio, prev, req);
850 851 852
	WARN_ON_ONCE(size > req->wb_bytes);
	if (size && size < req->wb_bytes)
		req->wb_bytes = size;
853
	return size > 0;
854 855 856
}

/**
857
 * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
858 859 860 861 862 863
 * @desc: destination io descriptor
 * @req: request
 *
 * Returns true if the request 'req' was successfully coalesced into the
 * existing list of pages 'desc'.
 */
864 865
static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
				     struct nfs_page *req)
866
{
867
	struct nfs_page *prev = NULL;
868 869
	if (desc->pg_count != 0) {
		prev = nfs_list_entry(desc->pg_list.prev);
870
	} else {
871 872
		if (desc->pg_ops->pg_init)
			desc->pg_ops->pg_init(desc, req);
873
		desc->pg_base = req->wb_pgbase;
874
	}
875 876
	if (!nfs_can_coalesce_requests(prev, req, desc))
		return 0;
877 878
	nfs_list_remove_request(req);
	nfs_list_add_request(req, &desc->pg_list);
879
	desc->pg_count += req->wb_bytes;
880 881 882
	return 1;
}

883 884 885 886 887 888
/*
 * 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)) {
889
		int error = desc->pg_ops->pg_doio(desc);
890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905
		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
 *
906 907 908
 * This may split a request into subrequests which are all part of the
 * same page group.
 *
909 910 911
 * Returns true if the request 'req' was successfully coalesced into the
 * existing list of pages 'desc'.
 */
912
static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
913
			   struct nfs_page *req)
914
{
915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958
	struct nfs_page *subreq;
	unsigned int bytes_left = 0;
	unsigned int offset, pgbase;

	nfs_page_group_lock(req);

	subreq = req;
	bytes_left = subreq->wb_bytes;
	offset = subreq->wb_offset;
	pgbase = subreq->wb_pgbase;

	do {
		if (!nfs_pageio_do_add_request(desc, subreq)) {
			/* make sure pg_test call(s) did nothing */
			WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
			WARN_ON_ONCE(subreq->wb_offset != offset);
			WARN_ON_ONCE(subreq->wb_pgbase != pgbase);

			nfs_page_group_unlock(req);
			desc->pg_moreio = 1;
			nfs_pageio_doio(desc);
			if (desc->pg_error < 0)
				return 0;
			desc->pg_moreio = 0;
			if (desc->pg_recoalesce)
				return 0;
			/* retry add_request for this subreq */
			nfs_page_group_lock(req);
			continue;
		}

		/* check for buggy pg_test call(s) */
		WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
		WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
		WARN_ON_ONCE(subreq->wb_bytes == 0);

		bytes_left -= subreq->wb_bytes;
		offset += subreq->wb_bytes;
		pgbase += subreq->wb_bytes;

		if (bytes_left) {
			subreq = nfs_create_request(req->wb_context,
					req->wb_page,
					subreq, pgbase, bytes_left);
959 960
			if (IS_ERR(subreq))
				goto err_ptr;
961 962 963 964 965 966 967
			nfs_lock_request(subreq);
			subreq->wb_offset  = offset;
			subreq->wb_index = req->wb_index;
		}
	} while (bytes_left > 0);

	nfs_page_group_unlock(req);
968
	return 1;
969 970 971 972
err_ptr:
	desc->pg_error = PTR_ERR(subreq);
	nfs_page_group_unlock(req);
	return 0;
973 974
}

975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015
static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
{
	LIST_HEAD(head);

	do {
		list_splice_init(&desc->pg_list, &head);
		desc->pg_bytes_written -= desc->pg_count;
		desc->pg_count = 0;
		desc->pg_base = 0;
		desc->pg_recoalesce = 0;

		while (!list_empty(&head)) {
			struct nfs_page *req;

			req = list_first_entry(&head, struct nfs_page, wb_list);
			nfs_list_remove_request(req);
			if (__nfs_pageio_add_request(desc, req))
				continue;
			if (desc->pg_error < 0)
				return 0;
			break;
		}
	} while (desc->pg_recoalesce);
	return 1;
}

int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
		struct nfs_page *req)
{
	int ret;

	do {
		ret = __nfs_pageio_add_request(desc, req);
		if (ret)
			break;
		if (desc->pg_error < 0)
			break;
		ret = nfs_do_recoalesce(desc);
	} while (ret);
	return ret;
}
B
Bryan Schumaker 已提交
1016
EXPORT_SYMBOL_GPL(nfs_pageio_add_request);
1017

1018 1019 1020 1021 1022 1023
/**
 * 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)
{
1024 1025 1026 1027 1028 1029 1030
	for (;;) {
		nfs_pageio_doio(desc);
		if (!desc->pg_recoalesce)
			break;
		if (!nfs_do_recoalesce(desc))
			break;
	}
1031
}
B
Bryan Schumaker 已提交
1032
EXPORT_SYMBOL_GPL(nfs_pageio_complete);
1033

1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049
/**
 * nfs_pageio_cond_complete - Conditional I/O completion
 * @desc: pointer to io descriptor
 * @index: page index
 *
 * It is important to ensure that processes don't try to take locks
 * on non-contiguous ranges of pages as that might deadlock. This
 * function should be called before attempting to wait on a locked
 * nfs_page. It will complete the I/O if the page index 'index'
 * is not contiguous with the existing list of pages in 'desc'.
 */
void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
{
	if (!list_empty(&desc->pg_list)) {
		struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
		if (index != prev->wb_index + 1)
1050
			nfs_pageio_complete(desc);
1051 1052 1053
	}
}

D
David Howells 已提交
1054
int __init nfs_init_nfspagecache(void)
L
Linus Torvalds 已提交
1055 1056 1057 1058
{
	nfs_page_cachep = kmem_cache_create("nfs_page",
					    sizeof(struct nfs_page),
					    0, SLAB_HWCACHE_ALIGN,
1059
					    NULL);
L
Linus Torvalds 已提交
1060 1061 1062 1063 1064 1065
	if (nfs_page_cachep == NULL)
		return -ENOMEM;

	return 0;
}

1066
void nfs_destroy_nfspagecache(void)
L
Linus Torvalds 已提交
1067
{
1068
	kmem_cache_destroy(nfs_page_cachep);
L
Linus Torvalds 已提交
1069 1070
}

1071
static const struct rpc_call_ops nfs_pgio_common_ops = {
1072 1073 1074 1075
	.rpc_call_prepare = nfs_pgio_prepare,
	.rpc_call_done = nfs_pgio_result,
	.rpc_release = nfs_pgio_release,
};
1076 1077 1078 1079 1080

const struct nfs_pageio_ops nfs_pgio_rw_ops = {
	.pg_test = nfs_generic_pg_test,
	.pg_doio = nfs_generic_pg_pgios,
};