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authorDavid Gibson <david@gibson.dropbear.id.au>2006-01-06 00:10:44 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-06 08:33:23 -0800
commit1e8f889b10d8d2223105719e36ce45688fedbd59 (patch)
tree86dee89e4363aaf6c7ec7c9751ea37f725c95bb9 /fs/hugetlbfs
parent86e5216f8d8aa258ba836caffe2613d79cc9aead (diff)
[PATCH] Hugetlb: Copy on Write support
Implement copy-on-write support for hugetlb mappings so MAP_PRIVATE can be supported. This helps us to safely use hugetlb pages in many more applications. The patch makes the following changes. If needed, I also have it broken out according to the following paragraphs. 1. Add a pair of functions to set/clear write access on huge ptes. The writable check in make_huge_pte is moved out to the caller for use by COW later. 2. Hugetlb copy-on-write requires special case handling in the following situations: - copy_hugetlb_page_range() - Copied pages must be write protected so a COW fault will be triggered (if necessary) if those pages are written to. - find_or_alloc_huge_page() - Only MAP_SHARED pages are added to the page cache. MAP_PRIVATE pages still need to be locked however. 3. Provide hugetlb_cow() and calls from hugetlb_fault() and hugetlb_no_page() which handles the COW fault by making the actual copy. 4. Remove the check in hugetlbfs_file_map() so that MAP_PRIVATE mmaps will be allowed. Make MAP_HUGETLB exempt from the depricated VM_RESERVED mapping check. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Adam Litke <agl@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: "Seth, Rohit" <rohit.seth@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/hugetlbfs')
-rw-r--r--fs/hugetlbfs/inode.c3
1 files changed, 0 insertions, 3 deletions
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 8c1cef3bb67..8c41315a6e4 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -100,9 +100,6 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
loff_t len, vma_len;
int ret;
- if ((vma->vm_flags & (VM_MAYSHARE | VM_WRITE)) == VM_WRITE)
- return -EINVAL;
-
if (vma->vm_pgoff & (HPAGE_SIZE / PAGE_SIZE - 1))
return -EINVAL;