[Linux-cluster] Re: GFS
David Teigland
teigland at redhat.com
Wed Aug 10 05:59:45 UTC 2005
On Mon, Aug 08, 2005 at 05:14:45PM +0300, Pekka J Enberg wrote:
if (!dumping)
down_read(&mm->mmap_sem);
> >+
> >+ for (vma = find_vma(mm, start); vma; vma = vma->vm_next) {
> >+ if (end <= vma->vm_start)
> >+ break;
> >+ if (vma->vm_file &&
> >+ vma->vm_file->f_dentry->d_inode->i_sb == sb) {
> >+ num_gh++;
> >+ }
> >+ }
> >+
> >+ ghs = kmalloc((num_gh + 1) * sizeof(struct gfs2_holder),
> >+ GFP_KERNEL);
> >+ if (!ghs) {
> >+ if (!dumping)
> >+ up_read(&mm->mmap_sem);
> >+ return -ENOMEM;
> >+ }
> >+
> >+ for (vma = find_vma(mm, start); vma; vma = vma->vm_next) {
>
> Sorry if this is an obvious question but what prevents another thread from
> doing mmap() before we do the second walk and messing up num_gh?
mm->mmap_sem ?
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