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| author |   James Morris <jmorris@namei.org> | 2009-05-08 17:56:47 +1000 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2009-05-08 17:56:47 +1000 |
| commit | d254117099d711f215e62427f55dfb8ebd5ad011 (patch) | |
| tree | 0848ff8dd74314fec14a86497f8d288c86ba7c65 /Documentation/filesystems/Locking | |
| parent | integrity: remove __setup auditing msgs (diff) | |
| parent | NOMMU: Don't check vm_region::vm_start is page aligned in add_nommu_region() (diff) | |
| download | linux-dev-d254117099d711f215e62427f55dfb8ebd5ad011.tar.xz linux-dev-d254117099d711f215e62427f55dfb8ebd5ad011.zip | |
Merge branch 'master' into next
Diffstat (limited to 'Documentation/filesystems/Locking')
| -rw-r--r-- | Documentation/filesystems/Locking | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 4e78ce677843..3120f8dd2c31 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -505,23 +505,31 @@ prototypes: void (*open)(struct vm_area_struct*); 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 (*page_mkwrite)(struct vm_area_struct *, struct vm_fault *); int (*access)(struct vm_area_struct *, unsigned long, void*, int, int); locking rules: BKL mmap_sem PageLocked(page) open: no yes close: no yes -fault: no yes -page_mkwrite: no yes no +fault: no yes can return with page locked +page_mkwrite: no yes can return with page locked access: no yes - ->page_mkwrite() is called when a previously read-only page is -about to become writeable. The file system is responsible for -protecting against truncate races. Once appropriate action has been -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. + ->fault() is called when a previously not present pte is about +to be faulted in. The filesystem must find and return the page associated +with the passed in "pgoff" in the vm_fault structure. If it is possible that +the page may be truncated and/or invalidated, then the filesystem must lock +the page, then ensure it is not already truncated (the page lock will block +subsequent truncate), and then return with VM_FAULT_LOCKED, and the page +locked. The VM will unlock the page. + + ->page_mkwrite() is called when a previously read-only pte is +about to become writeable. The filesystem again must ensure that there are +no truncate/invalidate races, and then return with the page locked. If +the page has been truncated, the filesystem should not look up a new page +like the ->fault() handler, but simply return with VM_FAULT_NOPAGE, which +will cause the VM to retry the fault. ->access() is called when get_user_pages() fails in acces_process_vm(), typically used to debug a process through |