Messages in this thread | | | Date | Tue, 27 Mar 2012 09:55:27 +0200 | From | Jan Kara <> | Subject | Re: [PATCH 01/19] mm: Make default vm_ops provide ->page_mkwrite handler |
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On Fri 23-03-12 15:45:02, Andrew Morton wrote: > On Mon, 5 Mar 2012 17:00:59 +0100 > Jan Kara <jack@suse.cz> 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@suse.cz> SUSE Labs, CR
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