path: root/ipc/shm.c
diff options
authorNick Piggin <npiggin@suse.de>2007-07-19 01:46:59 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-19 10:04:41 -0700
commit54cb8821de07f2ffcd28c380ce9b93d5784b40d7 (patch)
tree1de676534963d96af42863b20191bc9f80060dea /ipc/shm.c
parentd00806b183152af6d24f46f0c33f14162ca1262a (diff)
mm: merge populate and nopage into fault (fixes nonlinear)
Nonlinear mappings are (AFAIKS) simply a virtual memory concept that encodes the virtual address -> file offset differently from linear mappings. ->populate is a layering violation because the filesystem/pagecache code should need to know anything about the virtual memory mapping. The hitch here is that the ->nopage handler didn't pass down enough information (ie. pgoff). But it is more logical to pass pgoff rather than have the ->nopage function calculate it itself anyway (because that's a similar layering violation). Having the populate handler install the pte itself is likewise a nasty thing to be doing. This patch introduces a new fault handler that replaces ->nopage and ->populate and (later) ->nopfn. Most of the old mechanism is still in place so there is a lot of duplication and nice cleanups that can be removed if everyone switches over. The rationale for doing this in the first place is that nonlinear mappings are subject to the pagefault vs invalidate/truncate race too, and it seemed stupid to duplicate the synchronisation logic rather than just consolidate the two. After this patch, MAP_NONBLOCK no longer sets up ptes for pages present in pagecache. Seems like a fringe functionality anyway. NOPAGE_REFAULT is removed. This should be implemented with ->fault, and no users have hit mainline yet. [akpm@linux-foundation.org: cleanup] [randy.dunlap@oracle.com: doc. fixes for readahead] [akpm@linux-foundation.org: build fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/shm.c')
1 files changed, 5 insertions, 4 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
index 242c3f66493a..e2d090348b1e 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -224,13 +224,13 @@ static void shm_close(struct vm_area_struct *vma)
-static struct page *shm_nopage(struct vm_area_struct *vma,
- unsigned long address, int *type)
+static struct page *shm_fault(struct vm_area_struct *vma,
+ struct fault_data *fdata)
struct file *file = vma->vm_file;
struct shm_file_data *sfd = shm_file_data(file);
- return sfd->vm_ops->nopage(vma, address, type);
+ return sfd->vm_ops->fault(vma, fdata);
@@ -269,6 +269,7 @@ static int shm_mmap(struct file * file, struct vm_area_struct * vma)
if (ret != 0)
return ret;
sfd->vm_ops = vma->vm_ops;
+ BUG_ON(!sfd->vm_ops->fault);
vma->vm_ops = &shm_vm_ops;
@@ -327,7 +328,7 @@ static const struct file_operations shm_file_operations = {
static struct vm_operations_struct shm_vm_ops = {
.open = shm_open, /* callback for a new vm-area open */
.close = shm_close, /* callback for when the vm-area is released */
- .nopage = shm_nopage,
+ .fault = shm_fault,
#if defined(CONFIG_NUMA)
.set_policy = shm_set_policy,
.get_policy = shm_get_policy,