Messages in this thread | | | Date | Mon, 23 Aug 2010 09:15:05 -0400 | From | Josef Bacik <> | Subject | Re: [PATCH 6/6] btrfs: check mergeable free space when removing a cluster |
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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 <lizf@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,
Josef
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