Re: GFS

["Pekka J Enberg" <penberg@cs.helsinki.fi>]

David Teigland writes:
> +static ssize_t walk_vm_hard(struct file *file, char *buf, size_t size,
> +                         loff_t *offset, do_rw_t operation)
> +{
> +     struct gfs2_holder *ghs;
> +     unsigned int num_gh = 0;
> +     ssize_t count;
> +
> +     {

Can we please get rid of the extra braces everywhere? 

[snip] 

David Teigland writes:
> +
> +             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? 

> +                     if (end <= vma->vm_start)
> +                             break;
> +                     if (vma->vm_file) {
> +                             struct inode *inode;
> +                             inode = vma->vm_file->f_dentry->d_inode;
> +                             if (inode->i_sb == sb)
> +                                     gfs2_holder_init(get_v2ip(inode)->i_gl,
> +                                                      vma2state(vma),
> +                                                      0, &ghs[x++]);
> +                     }
> +             }

            Pekka