/*
* linux/include/linux/nfs_page.h
*
* Copyright (C) 2000 Trond Myklebust
*
* NFS page cache wrapper.
*/

#ifndef _LINUX_NFS_PAGE_H
#define _LINUX_NFS_PAGE_H


#include <linux/list.h>
#include <linux/pagemap.h>
#include <linux/wait.h>
#include <linux/sunrpc/auth.h>
#include <linux/nfs_xdr.h>

#include <linux/kref.h>

/*
* Valid flags for a dirty buffer
*/
enum {
PG_BUSY = 0,
PG_MAPPED,
PG_CLEAN,
PG_NEED_COMMIT,
PG_NEED_RESCHED,
PG_COMMIT_TO_DS,
};

struct nfs_inode;
struct nfs_page {
struct list_head wb_list; /* Defines state of page: */
struct page *wb_page; /* page to read in/write out */
struct nfs_open_context *wb_context; /* File state context info */
struct nfs_lock_context *wb_lock_context; /* lock context info */
pgoff_t wb_index; /* Offset >> PAGE_CACHE_SHIFT */
unsigned int wb_offset, /* Offset & ~PAGE_CACHE_MASK */
wb_pgbase, /* Start of page data */
wb_bytes; /* Length of request */
struct kref wb_kref; /* reference count */
unsigned long wb_flags;
struct nfs_write_verifier wb_verf; /* Commit cookie */
};

struct nfs_pageio_descriptor;
struct nfs_pageio_ops {
void (*pg_init)(struct nfs_pageio_descriptor *, struct nfs_page *);
bool (*pg_test)(struct nfs_pageio_descriptor *, struct nfs_page *, struct nfs_page *);
int (*pg_doio)(struct nfs_pageio_descriptor *);
};

struct nfs_pageio_descriptor {
struct list_head pg_list;
unsigned long pg_bytes_written;
size_t pg_count;
size_t pg_bsize;
unsigned int pg_base;
unsigned char pg_moreio : 1,
pg_recoalesce : 1;

struct inode *pg_inode;
const struct nfs_pageio_ops *pg_ops;
int pg_ioflags;
int pg_error;
const struct rpc_call_ops *pg_rpc_callops;
const struct nfs_pgio_completion_ops *pg_completion_ops;
struct pnfs_layout_segment *pg_lseg;
struct nfs_direct_req *pg_dreq;
void *pg_layout_private;
};

#define NFS_WBACK_BUSY(req) (test_bit(PG_BUSY,&(req)->wb_flags))

extern struct nfs_page *nfs_create_request(struct nfs_open_context *ctx,
struct inode *inode,
struct page *page,
unsigned int offset,
unsigned int count);
extern void nfs_release_request(struct nfs_page *req);


extern void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
struct inode *inode,
const struct nfs_pageio_ops *pg_ops,
const struct nfs_pgio_completion_ops *compl_ops,
size_t bsize,
int how);
extern int nfs_pageio_add_request(struct nfs_pageio_descriptor *,
struct nfs_page *);
extern void nfs_pageio_complete(struct nfs_pageio_descriptor *desc);
extern void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *, pgoff_t);
extern bool nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
struct nfs_page *prev,
struct nfs_page *req);
extern int nfs_wait_on_request(struct nfs_page *);
extern void nfs_unlock_request(struct nfs_page *req);
extern void nfs_unlock_and_release_request(struct nfs_page *req);

/*
* Lock the page of an asynchronous request
*/
static inline int
nfs_lock_request(struct nfs_page *req)
{
return !test_and_set_bit(PG_BUSY, &req->wb_flags);
}

/**
* nfs_list_add_request - Insert a request into a list
* @req: request
* @head: head of list into which to insert the request.
*/
static inline void
nfs_list_add_request(struct nfs_page *req, struct list_head *head)
{
list_add_tail(&req->wb_list, head);
}


/**
* nfs_list_remove_request - Remove a request from its wb_list
* @req: request
*/
static inline void
nfs_list_remove_request(struct nfs_page *req)
{
if (list_empty(&req->wb_list))
return;
list_del_init(&req->wb_list);
}

static inline struct nfs_page *
nfs_list_entry(struct list_head *head)
{
return list_entry(head, struct nfs_page, wb_list);
}

static inline
loff_t req_offset(struct nfs_page *req)
{
return (((loff_t)req->wb_index) << PAGE_CACHE_SHIFT) + req->wb_offset;
}

#endif /* _LINUX_NFS_PAGE_H */