include/linux/nfs_page.h

   1 /*
   2  * linux/include/linux/nfs_page.h
   3  *
   4  * Copyright (C) 2000 Trond Myklebust
   5  *
   6  * NFS page cache wrapper.
   7  */
   8
   9 #ifndef _LINUX_NFS_PAGE_H
  10 #define _LINUX_NFS_PAGE_H
  11
  12
  13 #include <linux/list.h>
  14 #include <linux/pagemap.h>
  15 #include <linux/wait.h>
  16 #include <linux/nfs_fs_sb.h>
  17 #include <linux/sunrpc/auth.h>
  18 #include <linux/nfs_xdr.h>
  19
  20 #include <asm/atomic.h>
  21
  22 /*
  23  * Valid flags for a dirty buffer
  24  */
  25 #define PG_BUSY                 0
  26 #define PG_NEED_COMMIT          1
  27 #define PG_NEED_RESCHED         2
  28
  29 struct nfs_page {
  30         struct list_head        wb_list,        /* Defines state of page: */
  31                                 *wb_list_head;  /*      read/write/commit */
  32         struct page             *wb_page;       /* page to read in/write out */
  33         struct nfs_open_context *wb_context;    /* File state context info */
  34         atomic_t                wb_complete;    /* i/os we're waiting for */
  35         unsigned long           wb_index;       /* Offset >> PAGE_CACHE_SHIFT */
  36         unsigned int            wb_offset,      /* Offset & ~PAGE_CACHE_MASK */
  37                                 wb_pgbase,      /* Start of page data */
  38                                 wb_bytes;       /* Length of request */
  39         atomic_t                wb_count;       /* reference count */
  40         unsigned long           wb_flags;
  41         struct nfs_writeverf    wb_verf;        /* Commit cookie */
  42 };
  43
  44 #define NFS_WBACK_BUSY(req)     (test_bit(PG_BUSY,&(req)->wb_flags))
  45 #define NFS_NEED_COMMIT(req)    (test_bit(PG_NEED_COMMIT,&(req)->wb_flags))
  46 #define NFS_NEED_RESCHED(req)   (test_bit(PG_NEED_RESCHED,&(req)->wb_flags))
  47
  48 extern  struct nfs_page *nfs_create_request(struct nfs_open_context *ctx,
  49                                             struct inode *inode,
  50                                             struct page *page,
  51                                             unsigned int offset,
  52                                             unsigned int count);
  53 extern  void nfs_clear_request(struct nfs_page *req);
  54 extern  void nfs_release_request(struct nfs_page *req);
  55
  56
  57 extern  void nfs_list_add_request(struct nfs_page *, struct list_head *);
  58
  59 extern  int nfs_scan_list(struct list_head *, struct list_head *,
  60                           unsigned long, unsigned int);
  61 extern  int nfs_coalesce_requests(struct list_head *, struct list_head *,
  62                                   unsigned int);
  63 extern  int nfs_wait_on_request(struct nfs_page *);
  64 extern  void nfs_unlock_request(struct nfs_page *req);
  65
  66 /*
  67  * Lock the page of an asynchronous request without incrementing the wb_count
  68  */
  69 static inline int
  70 nfs_lock_request_dontget(struct nfs_page *req)
  71 {
  72         if (test_and_set_bit(PG_BUSY, &req->wb_flags))
  73                 return 0;
  74         return 1;
  75 }
  76
  77 /*
  78  * Lock the page of an asynchronous request
  79  */
  80 static inline int
  81 nfs_lock_request(struct nfs_page *req)
  82 {
  83         if (test_and_set_bit(PG_BUSY, &req->wb_flags))
  84                 return 0;
  85         atomic_inc(&req->wb_count);
  86         return 1;
  87 }
  88
  89
  90 /**
  91  * nfs_list_remove_request - Remove a request from its wb_list
  92  * @req: request
  93  */
  94 static inline void
  95 nfs_list_remove_request(struct nfs_page *req)
  96 {
  97         if (list_empty(&req->wb_list))
  98                 return;
  99         if (!NFS_WBACK_BUSY(req)) {
 100                 printk(KERN_ERR "NFS: unlocked request attempted removed from list!\n");
 101                 BUG();
 102         }
 103         list_del_init(&req->wb_list);
 104         req->wb_list_head = NULL;
 105 }
 106
 107 static inline int
 108 nfs_defer_commit(struct nfs_page *req)
 109 {
 110         if (test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags))
 111                 return 0;
 112         return 1;
 113 }
 114
 115 static inline void
 116 nfs_clear_commit(struct nfs_page *req)
 117 {
 118         smp_mb__before_clear_bit();
 119         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
 120         smp_mb__after_clear_bit();
 121 }
 122
 123 static inline int
 124 nfs_defer_reschedule(struct nfs_page *req)
 125 {
 126         if (test_and_set_bit(PG_NEED_RESCHED, &req->wb_flags))
 127                 return 0;
 128         return 1;
 129 }
 130
 131 static inline void
 132 nfs_clear_reschedule(struct nfs_page *req)
 133 {
 134         smp_mb__before_clear_bit();
 135         clear_bit(PG_NEED_RESCHED, &req->wb_flags);
 136         smp_mb__after_clear_bit();
 137 }
 138
 139 static inline struct nfs_page *
 140 nfs_list_entry(struct list_head *head)
 141 {
 142         return list_entry(head, struct nfs_page, wb_list);
 143 }
 144
 145 static inline
 146 loff_t req_offset(struct nfs_page *req)
 147 {
 148         return (((loff_t)req->wb_index) << PAGE_CACHE_SHIFT) + req->wb_offset;
 149 }
 150
 151 #endif /* _LINUX_NFS_PAGE_H */