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