On Fri, Feb 08, 2013 at 04:35:00PM +0100, Jan Kara wrote:
[snip]
> > -static int __es_insert_extent(struct ext4_es_tree *tree, ext4_lblk_t offset,
> > - ext4_lblk_t len)
> > +static int __es_insert_extent(struct ext4_es_tree *tree,
> > + struct extent_status *newes)
> > {
> > struct rb_node **p = &tree->root.rb_node;
> > struct rb_node *parent = NULL;
> > struct extent_status *es;
> > - ext4_lblk_t end = offset + len - 1;
> > -
> > - BUG_ON(end < offset);
> > - es = tree->cache_es;
> > - if (es && offset == (extent_status_end(es) + 1)) {
> > - es_debug("cached by [%u/%u)\n", es->start, es->len);
> > - es->len += len;
> > - es = ext4_es_try_to_merge_right(tree, es);
> > - goto out;
> > - } else if (es && es->start == end + 1) {
> > - es_debug("cached by [%u/%u)\n", es->start, es->len);
> > - es->start = offset;
> > - es->len += len;
> > - es = ext4_es_try_to_merge_left(tree, es);
> > - goto out;
> > - } else if (es && es->start <= offset &&
> > - end <= extent_status_end(es)) {
> > - es_debug("cached by [%u/%u)\n", es->start, es->len);
> > - goto out;
> > - }
> >
> > while (*p) {
> > parent = *p;
> > es = rb_entry(parent, struct extent_status, rb_node);
> >
> > - if (offset < es->start) {
> > - if (es->start == end + 1) {
> > - es->start = offset;
> > - es->len += len;
> > + if (newes->es_lblk < es->es_lblk) {
> > + if (ext4_es_can_be_merged(newes, es)) {
> > + es->es_lblk = newes->es_lblk;
> > + es->es_len += newes->es_len;
> This is wrong, isn't it? You cannot change es->es_lblk because that can
> break ordering of elements in the tree... thinking ... ah, it's OK because
> you have non-overlapping intervals. But it deserves a comment I guess.
Hi Jan,
Sorry for the delay reply. I will add a comment here to describe why
es_lblk can be changed directly.
Thanks,
- Zheng
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