[PATCH 6/6] btrfs: check mergeable free space when removing a cluster

[Li Zefan]

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);
        }
-- 
1.7.0.1

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