On Fri 23-03-12 15:45:02, Andrew Morton wrote:
> On Mon, 5 Mar 2012 17:00:59 +0100
> Jan Kara <jack@xxxxxxx> wrote:
>
> > --- a/mm/filemap.c
> > +++ b/mm/filemap.c
> > @@ -1759,8 +1759,28 @@ 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) ||
> > + (page_offset(page) > i_size_read(inode))) {
>
> Would benefit from a comment explaining how the page can come to be
> outside i_size, and why we fail in that case.
>
> I don't think i_mutex is held here, so this test is rather meaningless
> and racy anyway?
i_size test is racy if that's what you mean by "this test". Just I did
the test this way because it's like this in other places and I figured
truncate_pagecache() can take relatively long time so the test has some
effect. But if you think it's not worth it, I can remove it.
Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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