btrfs: Add a helper try_merge_free_space()
When adding a new extent, we'll firstly see if we can merge
this extent to the left or/and right extent. Extract this as
a helper try_merge_free_space().
As a side effect, we fix a small bug that if the new extent
has non-bitmap left entry but is unmergeble, we'll directly
link the extent without trying to drop it into bitmap.
This also prepares for the next patch.
Reviewed-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 2974c47..cf67dc3 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1363,22 +1363,14 @@
return ret;
}
-int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
- u64 offset, u64 bytes)
+bool try_merge_free_space(struct btrfs_block_group_cache *block_group,
+ struct btrfs_free_space *info)
{
- struct btrfs_free_space *right_info = NULL;
- struct btrfs_free_space *left_info = NULL;
- struct btrfs_free_space *info = NULL;
- int ret = 0;
-
- info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
- if (!info)
- return -ENOMEM;
-
- info->offset = offset;
- info->bytes = bytes;
-
- spin_lock(&block_group->tree_lock);
+ struct btrfs_free_space *left_info;
+ struct btrfs_free_space *right_info;
+ bool merged = false;
+ u64 offset = info->offset;
+ u64 bytes = info->bytes;
/*
* first we want to see if there is free space adjacent to the range we
@@ -1392,27 +1384,11 @@
else
left_info = tree_search_offset(block_group, offset - 1, 0, 0);
- /*
- * If there was no extent directly to the left or right of this new
- * extent then we know we're going to have to allocate a new extent, so
- * before we do that see if we need to drop this into a bitmap
- */
- if ((!left_info || left_info->bitmap) &&
- (!right_info || right_info->bitmap)) {
- ret = insert_into_bitmap(block_group, info);
-
- if (ret < 0) {
- goto out;
- } else if (ret) {
- ret = 0;
- goto out;
- }
- }
-
if (right_info && !right_info->bitmap) {
unlink_free_space(block_group, right_info);
info->bytes += right_info->bytes;
kfree(right_info);
+ merged = true;
}
if (left_info && !left_info->bitmap &&
@@ -1421,8 +1397,43 @@
info->offset = left_info->offset;
info->bytes += left_info->bytes;
kfree(left_info);
+ merged = true;
}
+ return merged;
+}
+
+int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
+ u64 offset, u64 bytes)
+{
+ struct btrfs_free_space *info;
+ int ret = 0;
+
+ info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
+ if (!info)
+ return -ENOMEM;
+
+ info->offset = offset;
+ info->bytes = bytes;
+
+ spin_lock(&block_group->tree_lock);
+
+ if (try_merge_free_space(block_group, info))
+ goto link;
+
+ /*
+ * There was no extent directly to the left or right of this new
+ * extent then we know we're going to have to allocate a new extent, so
+ * before we do that see if we need to drop this into a bitmap
+ */
+ ret = insert_into_bitmap(block_group, info);
+ if (ret < 0) {
+ goto out;
+ } else if (ret) {
+ ret = 0;
+ goto out;
+ }
+link:
ret = link_free_space(block_group, info);
if (ret)
kfree(info);