mm: Make default vm_ops provide ->page_mkwrite handler

Make default vm_ops provide ->page_mkwrite handler. Currently it only updates
file's modification times and gets locked page but later it will also handle
filesystem freezing.

BugLink: https://bugs.launchpad.net/bugs/897421
Tested-by: Kamal Mostafa <kamal@canonical.com>
Tested-by: Peter M. Petrakis <peter.petrakis@canonical.com>
Tested-by: Dann Frazier <dann.frazier@canonical.com>
Tested-by: Massimo Morana <massimo.morana@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index b36d08c..15987d8 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1411,6 +1411,7 @@ extern void truncate_inode_pages_range(struct address_space *,
 
 /* generic vm_area_ops exported for stackable file systems */
 extern int filemap_fault(struct vm_area_struct *, struct vm_fault *);
+extern int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
 
 /* mm/page-writeback.c */
 int write_one_page(struct page *page, int wait);

diff --git a/mm/filemap.c b/mm/filemap.c
index a4a5260..51efee6 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1712,8 +1712,27 @@ page_not_uptodate:
 }
 EXPORT_SYMBOL(filemap_fault);
 
+int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+       struct page *page = vmf->page;
+       struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
+       int ret = VM_FAULT_LOCKED;
+
+       file_update_time(vma->vm_file);
+       lock_page(page);
+       if (page->mapping != inode->i_mapping) {
+               unlock_page(page);
+               ret = VM_FAULT_NOPAGE;
+               goto out;
+       }
+out:
+       return ret;
+}
+EXPORT_SYMBOL(filemap_page_mkwrite);
+
 const struct vm_operations_struct generic_file_vm_ops = {
        .fault          = filemap_fault,
+       .page_mkwrite   = filemap_page_mkwrite,
 };
 
 /* This is used for a general mmap of a disk file */

diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 213ca1f..80b34ef 100644 (file)
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -304,6 +304,7 @@ out:
 
 static const struct vm_operations_struct xip_file_vm_ops = {
        .fault  = xip_file_fault,
+       .page_mkwrite   = filemap_page_mkwrite,
 };
 
 int xip_file_mmap(struct file * file, struct vm_area_struct * vma)