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32 .Dd September 12, 2014
38 .Nd read or write VM pages from a file
44 .Fn VOP_GETPAGES "struct vnode *vp" "vm_page_t *ma" "int count" "int reqpage"
46 .Fn VOP_PUTPAGES "struct vnode *vp" "vm_page_t *ma" "int count" "int sync" "int *rtvals"
50 method is called to read in pages of virtual memory which are backed by
52 If other adjacent pages are backed by adjacent regions of the same file,
54 is requested to read those pages as well, although it is not required to
58 method does the converse; that is to say, it writes out adjacent dirty
59 pages of virtual memory.
61 On entry, the vnode lock is held but neither the page queue nor VM object
63 Both methods return in the same state on both success and error returns.
66 .Bl -tag -width reqpage
70 Pointer to the first element of an array of pages representing a
71 contiguous region of the file to be read or written.
73 The number of bytes that should be read into the pages of the array.
76 if the write should be synchronous.
78 An array of VM system result codes indicating the status of each
82 The index in the page array of the requested page; i.e., the one page which
83 the implementation of this method must handle.
88 method is returned on a page-by-page basis in the array
90 The possible status values are as follows:
91 .Bl -tag -width VM_PAGER_ERROR
93 The page was successfully written.
94 The implementation must call
96 to mark the page as clean.
98 The page was scheduled to be written asynchronously.
99 When the write completes, the completion callback should
101 .Xr vm_object_pip_wakeup 9
103 .Xr vm_page_sunbusy 9
104 to clear the busy flag and awaken any other threads waiting for this page,
105 in addition to calling
106 .Xr vm_page_undirty 9 .
108 The page was entirely beyond the end of the backing file.
109 This condition should not be possible if the vnode's file system
110 is correctly implemented.
111 .It Dv VM_PAGER_ERROR
112 The page could not be written because of an error on the underlying storage
115 Treated identically to
117 .It Dv VM_PAGER_AGAIN
118 The page was not handled by this request.
123 method is expected to release any pages in
125 that it does not successfully handle, by calling
129 must set the valid bits appropriately.
134 It must unbusy all other successfully handled pages and put them
135 on appropriate page queue(s).
138 may either activate a page (if its wanted bit is set)
139 or deactivate it (otherwise), and finally call
140 .Xr vm_page_xunbusy 9
141 to arouse any threads currently waiting for the page to be faulted in.
143 If it successfully reads
150 By convention, the return value of
155 .Xr vm_object_pip_wakeup 9 ,
157 .Xr vm_page_sunbusy 9 ,
158 .Xr vm_page_undirty 9 ,
159 .Xr vm_page_xunbusy 9 ,
162 This manual page was written by
164 and then substantially rewritten by
165 .An Garrett Wollman .