access_process_vm device memory infrastructure

[pandora-kernel.git] / Documentation / filesystems / Locking

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 8b22d7d..680fb56 100644 (file)
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -510,6 +510,7 @@ prototypes:
        void (*close)(struct vm_area_struct*);
        int (*fault)(struct vm_area_struct*, struct vm_fault *);
        int (*page_mkwrite)(struct vm_area_struct *, struct page *);
+       int (*access)(struct vm_area_struct *, unsigned long, void*, int, int);
 
 locking rules:
                BKL     mmap_sem        PageLocked(page)
@@ -517,6 +518,7 @@ open:               no      yes
 close:         no      yes
 fault:         no      yes
 page_mkwrite:  no      yes             no
+access:                no      yes
 
        ->page_mkwrite() is called when a previously read-only page is
 about to become writeable. The file system is responsible for
@@ -525,6 +527,11 @@ taking to lock out truncate, the page range should be verified to be
 within i_size. The page mapping should also be checked that it is not
 NULL.
 
+       ->access() is called when get_user_pages() fails in
+acces_process_vm(), typically used to debug a process through
+/proc/pid/mem or ptrace.  This function is needed only for
+VM_IO | VM_PFNMAP VMAs.
+
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                        Dubious stuff