diff options
| author | Mark Fasheh <mark.fasheh@oracle.com> | 2007-07-19 01:47:01 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-19 10:04:41 -0700 |
| commit | ed2f2f9b3ff8debdf512f7687b232c3c1d7d60d7 (patch) | |
| tree | f935333e6d233ba0f119d4642b15063ba544fddf /Documentation/filesystems | |
| parent | 6967614761fd305b3414d9485d89dc2e0a407410 (diff) | |
| download | lwn-ed2f2f9b3ff8debdf512f7687b232c3c1d7d60d7.tar.gz lwn-ed2f2f9b3ff8debdf512f7687b232c3c1d7d60d7.zip | |
Document ->page_mkwrite() locking
There seems to be very little documentation about this callback in general.
The locking in particular is a bit tricky, so it's worth having this in
writing.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/Locking | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 970c8ec1a05b..91ec4b40ebfe 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -512,13 +512,22 @@ prototypes: void (*close)(struct vm_area_struct*); struct page *(*fault)(struct vm_area_struct*, struct fault_data *); struct page *(*nopage)(struct vm_area_struct*, unsigned long, int *); + int (*page_mkwrite)(struct vm_area_struct *, struct page *); locking rules: - BKL mmap_sem + BKL mmap_sem PageLocked(page) open: no yes close: no yes fault: no yes nopage: no yes +page_mkwrite: no yes no + + ->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. ================================================================================ Dubious stuff |