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/*
 * 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/nfs_fs_sb.h>
#include <linux/sunrpc/auth.h>
#include <linux/nfs_xdr.h>

/*
 * Valid flags for a dirty buffer
 */

#define PG_BUSY                 0

struct nfs_page {
        struct list_head        wb_list,        /* Defines state of page: */
                                *wb_list_head;  /*      read/write/commit */
        struct file             *wb_file;
        struct inode            *wb_inode;
        struct rpc_cred         *wb_cred;
        struct nfs4_state       *wb_state;
        struct page             *wb_page;       /* page to read in/write out */
        wait_queue_head_t       wb_wait;        /* wait queue */
        unsigned long           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 */
                                wb_count;       /* reference count */
        unsigned long           wb_flags;
        struct nfs_writeverf    wb_verf;        /* Commit cookie */
};

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

extern  struct nfs_page *nfs_create_request(struct file *, struct inode *,
                                            struct page *,
                                            unsigned int, unsigned int);
extern  void nfs_clear_request(struct nfs_page *req);
extern  void nfs_release_request(struct nfs_page *req);


extern  void nfs_list_add_request(struct nfs_page *, struct list_head *);

extern  int nfs_scan_list(struct list_head *, struct list_head *,
                          struct file *, unsigned long, unsigned int);
extern  int nfs_coalesce_requests(struct list_head *, struct list_head *,
                                  unsigned int);
extern  int nfs_wait_on_request(struct nfs_page *);

extern  spinlock_t nfs_wreq_lock;

/*
 * Lock the page of an asynchronous request without incrementing the wb_count
 */

static inline int
nfs_lock_request_dontget(struct nfs_page *req)
{
        if (test_and_set_bit(PG_BUSY, &req->wb_flags))
                return 0;
        return 1;
}

/*
 * Lock the page of an asynchronous request
 */

static inline int
nfs_lock_request(struct nfs_page *req)
{
        if (test_and_set_bit(PG_BUSY, &req->wb_flags))
                return 0;
        req->wb_count++;
        return 1;
}

static inline 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();
        if (waitqueue_active(&req->wb_wait))
                wake_up_all(&req->wb_wait);
        nfs_release_request(req);
}

/**
 * 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;
        if (!NFS_WBACK_BUSY(req)) {
                printk(KERN_ERR "NFS: unlocked request attempted removed from list!\n");
                BUG();
        }
        list_del_init(&req->wb_list);
        req->wb_list_head = NULL;
}

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 */