From 54cb8821de07f2ffcd28c380ce9b93d5784b40d7 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Thu, 19 Jul 2007 01:46:59 -0700 Subject: 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 Signed-off-by: Randy Dunlap Cc: Mark Fasheh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ncpfs/mmap.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) (limited to 'fs/ncpfs') diff --git a/fs/ncpfs/mmap.c b/fs/ncpfs/mmap.c index 5416673418b..af48b792ca0 100644 --- a/fs/ncpfs/mmap.c +++ b/fs/ncpfs/mmap.c @@ -25,8 +25,8 @@ /* * Fill in the supplied page for mmap */ -static struct page* ncp_file_mmap_nopage(struct vm_area_struct *area, - unsigned long address, int *type) +static struct page* ncp_file_mmap_fault(struct vm_area_struct *area, + struct fault_data *fdata) { struct file *file = area->vm_file; struct dentry *dentry = file->f_path.dentry; @@ -40,15 +40,17 @@ static struct page* ncp_file_mmap_nopage(struct vm_area_struct *area, page = alloc_page(GFP_HIGHUSER); /* ncpfs has nothing against high pages as long as recvmsg and memset works on it */ - if (!page) - return page; + if (!page) { + fdata->type = VM_FAULT_OOM; + return NULL; + } pg_addr = kmap(page); - address &= PAGE_MASK; - pos = address - area->vm_start + (area->vm_pgoff << PAGE_SHIFT); + pos = fdata->pgoff << PAGE_SHIFT; count = PAGE_SIZE; - if (address + PAGE_SIZE > area->vm_end) { - count = area->vm_end - address; + if (fdata->address + PAGE_SIZE > area->vm_end) { + WARN_ON(1); /* shouldn't happen? */ + count = area->vm_end - fdata->address; } /* what we can read in one go */ bufsize = NCP_SERVER(inode)->buffer_size; @@ -91,15 +93,14 @@ static struct page* ncp_file_mmap_nopage(struct vm_area_struct *area, * fetches from the network, here the analogue of disk. * -- wli */ - if (type) - *type = VM_FAULT_MAJOR; + fdata->type = VM_FAULT_MAJOR; count_vm_event(PGMAJFAULT); return page; } static struct vm_operations_struct ncp_file_mmap = { - .nopage = ncp_file_mmap_nopage, + .fault = ncp_file_mmap_fault, }; -- cgit v1.2.3