On Tue, Aug 24, 2010 at 09:04:13AM +0800, Li Zefan wrote:
> Josef Bacik wrote:
> > On Mon, Aug 23, 2010 at 09:24:07AM +0800, Li Zefan wrote:
> >> After returing extents from a cluster to the block group, some
> >> extents in the block group may be mergeable.
> >>
> >> Signed-off-by: Li Zefan <l...@cn.fujitsu.com>
> >> ---
> >> fs/btrfs/free-space-cache.c | 26 ++++++++++++++++++++------
> >> 1 files changed, 20 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
> >> index faeec8f..c11f4f7 100644
> >> --- a/fs/btrfs/free-space-cache.c
> >> +++ b/fs/btrfs/free-space-cache.c
> >> @@ -234,11 +234,18 @@ tree_search_offset(struct btrfs_block_group_cache
> >> *block_group,
> >> return entry;
> >> }
> >>
> >> -static void unlink_free_space(struct btrfs_block_group_cache *block_group,
> >> - struct btrfs_free_space *info)
> >> +static inline void
> >> +__unlink_free_space(struct btrfs_block_group_cache *block_group,
> >> + struct btrfs_free_space *info)
> >> {
> >> rb_erase(&info->offset_index, &block_group->free_space_offset);
> >> block_group->free_extents--;
> >> +}
> >> +
> >> +static void unlink_free_space(struct btrfs_block_group_cache *block_group,
> >> + struct btrfs_free_space *info)
> >> +{
> >> + __unlink_free_space(block_group, info);
> >> block_group->free_space -= info->bytes;
> >> }
> >>
> >> @@ -611,7 +618,7 @@ out:
> >> }
> >>
> >> bool try_merge_free_space(struct btrfs_block_group_cache *block_group,
> >> - struct btrfs_free_space *info)
> >> + struct btrfs_free_space *info, bool update_stat)
> >> {
> >> struct btrfs_free_space *left_info;
> >> struct btrfs_free_space *right_info;
> >> @@ -632,7 +639,10 @@ bool try_merge_free_space(struct
> >> btrfs_block_group_cache *block_group,
> >> left_info = tree_search_offset(block_group, offset - 1, 0, 0);
> >>
> >> if (right_info && !right_info->bitmap) {
> >> - unlink_free_space(block_group, right_info);
> >> + if (update_stat)
> >> + unlink_free_space(block_group, right_info);
> >> + else
> >> + __unlink_free_space(block_group, right_info);
> >> info->bytes += right_info->bytes;
> >> kfree(right_info);
> >> merged = true;
> >> @@ -640,7 +650,10 @@ bool try_merge_free_space(struct
> >> btrfs_block_group_cache *block_group,
> >>
> >> if (left_info && !left_info->bitmap &&
> >> left_info->offset + left_info->bytes == offset) {
> >> - unlink_free_space(block_group, left_info);
> >> + if (update_stat)
> >> + unlink_free_space(block_group, left_info);
> >> + else
> >> + __unlink_free_space(block_group, left_info);
> >> info->offset = left_info->offset;
> >> info->bytes += left_info->bytes;
> >> kfree(left_info);
> >> @@ -665,7 +678,7 @@ int btrfs_add_free_space(struct
> >> btrfs_block_group_cache *block_group,
> >>
> >> spin_lock(&block_group->tree_lock);
> >>
> >> - if (try_merge_free_space(block_group, info))
> >> + if (try_merge_free_space(block_group, info, true))
> >> goto link;
> >>
> >> /*
> >> @@ -883,6 +896,7 @@ __btrfs_return_cluster_to_free_space(
> >> node = rb_next(&entry->offset_index);
> >> rb_erase(&entry->offset_index, &cluster->root);
> >> BUG_ON(entry->bitmap);
> >> + try_merge_free_space(block_group, entry, false);
> >> tree_insert_offset(&block_group->free_space_offset,
> >> entry->offset, &entry->offset_index, 0);
> >
> > It's early in the morning here, so forgive me if I'm missing something
> > obvious,
> > but if try_merge_free_space() succeeds here, then won't tree_insert_offset()
> > then add an entry that overlaps the same spot? Should we do something like
> >
> > merged = try_merge_free_space();
> > if (!merged)
> > tree_insert_offset();
> >
> > ? Thanks,
> >
>
> In try_merge_free_space() we try to merge the left and right entry into
> @entry, and then the caller has to insert the @entry into the tree by
> itself.
>
> Similarly, In btrfs_add_free_space() we call link_free_space() no matter
> try_merge_free_space() returns success or not.
Ah ok I see now, thanks.
Reviewed-by: Josef Bacik <jo...@redhat.com>
Thanks,
Josef
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