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/sunrpc/auth.h>
  17 #include <linux/nfs_xdr.h>
  18
  19 #include <asm/atomic.h>
  20
  21 /*
  22  * Valid flags for the radix tree
  23  */
  24 #define NFS_PAGE_TAG_DIRTY      0
  25 #define NFS_PAGE_TAG_WRITEBACK  1
  26
  27 /*
  28  * Valid flags for a dirty buffer
  29  */
  30 #define PG_BUSY                 0
  31 #define PG_NEED_COMMIT          1
  32 #define PG_NEED_RESCHED         2
  33 #define PG_NEED_FLUSH           3
  34 #define PG_FLUSHING             4
  35
  36 struct nfs_inode;
  37 struct nfs_page {
  38         struct list_head        wb_list,        /* Defines state of page: */
  39                                 *wb_list_head;  /*      read/write/commit */
  40         struct page             *wb_page;       /* page to read in/write out */
  41         struct nfs_open_context *wb_context;    /* File state context info */
  42         atomic_t                wb_complete;    /* i/os we're waiting for */
  43         unsigned long           wb_index;       /* Offset >> PAGE_CACHE_SHIFT */
  44         unsigned int            wb_offset,      /* Offset & ~PAGE_CACHE_MASK */
  45                                 wb_pgbase,      /* Start of page data */
  46                                 wb_bytes;       /* Length of request */
  47         atomic_t                wb_count;       /* reference count */
  48         unsigned long           wb_flags;
  49         struct nfs_writeverf    wb_verf;        /* Commit cookie */
  50 };
  51
  52 #define NFS_WBACK_BUSY(req)     (test_bit(PG_BUSY,&(req)->wb_flags))
  53 #define NFS_NEED_COMMIT(req)    (test_bit(PG_NEED_COMMIT,&(req)->wb_flags))
  54 #define NFS_NEED_RESCHED(req)   (test_bit(PG_NEED_RESCHED,&(req)->wb_flags))
  55
  56 extern  struct nfs_page *nfs_create_request(struct nfs_open_context *ctx,
  57                                             struct inode *inode,
  58                                             struct page *page,
  59                                             unsigned int offset,
  60                                             unsigned int count);
  61 extern  void nfs_clear_request(struct nfs_page *req);
  62 extern  void nfs_release_request(struct nfs_page *req);
  63
  64
  65 extern  long nfs_scan_dirty(struct address_space *mapping,
  66                                 struct writeback_control *wbc,
  67                                 struct list_head *dst);
  68 extern  int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *head, struct list_head *dst,
  69                           unsigned long idx_start, unsigned int npages);
  70 extern  int nfs_coalesce_requests(struct list_head *, struct list_head *,
  71                                   unsigned int);
  72 extern  int nfs_wait_on_request(struct nfs_page *);
  73 extern  void nfs_unlock_request(struct nfs_page *req);
  74 extern  int nfs_set_page_writeback_locked(struct nfs_page *req);
  75 extern  void nfs_clear_page_writeback(struct nfs_page *req);
  76
  77
  78 /*
  79  * Lock the page of an asynchronous request without incrementing the wb_count
  80  */
  81 static inline int
  82 nfs_lock_request_dontget(struct nfs_page *req)
  83 {
  84         return !test_and_set_bit(PG_BUSY, &req->wb_flags);
  85 }
  86
  87 /*
  88  * Lock the page of an asynchronous request
  89  */
  90 static inline int
  91 nfs_lock_request(struct nfs_page *req)
  92 {
  93         if (test_and_set_bit(PG_BUSY, &req->wb_flags))
  94                 return 0;
  95         atomic_inc(&req->wb_count);
  96         return 1;
  97 }
  98
  99 /**
 100  * nfs_list_add_request - Insert a request into a list
 101  * @req: request
 102  * @head: head of list into which to insert the request.
 103  */
 104 static inline void
 105 nfs_list_add_request(struct nfs_page *req, struct list_head *head)
 106 {
 107         list_add_tail(&req->wb_list, head);
 108         req->wb_list_head = head;
 109 }
 110
 111
 112 /**
 113  * nfs_list_remove_request - Remove a request from its wb_list
 114  * @req: request
 115  */
 116 static inline void
 117 nfs_list_remove_request(struct nfs_page *req)
 118 {
 119         if (list_empty(&req->wb_list))
 120                 return;
 121         list_del_init(&req->wb_list);
 122         req->wb_list_head = NULL;
 123 }
 124
 125 static inline int
 126 nfs_defer_commit(struct nfs_page *req)
 127 {
 128         return !test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags);
 129 }
 130
 131 static inline void
 132 nfs_clear_commit(struct nfs_page *req)
 133 {
 134         smp_mb__before_clear_bit();
 135         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
 136         smp_mb__after_clear_bit();
 137 }
 138
 139 static inline int
 140 nfs_defer_reschedule(struct nfs_page *req)
 141 {
 142         return !test_and_set_bit(PG_NEED_RESCHED, &req->wb_flags);
 143 }
 144
 145 static inline void
 146 nfs_clear_reschedule(struct nfs_page *req)
 147 {
 148         smp_mb__before_clear_bit();
 149         clear_bit(PG_NEED_RESCHED, &req->wb_flags);
 150         smp_mb__after_clear_bit();
 151 }
 152
 153 static inline struct nfs_page *
 154 nfs_list_entry(struct list_head *head)
 155 {
 156         return list_entry(head, struct nfs_page, wb_list);
 157 }
 158
 159 static inline
 160 loff_t req_offset(struct nfs_page *req)
 161 {
 162         return (((loff_t)req->wb_index) << PAGE_CACHE_SHIFT) + req->wb_offset;
 163 }
 164
 165 #endif /* _LINUX_NFS_PAGE_H */