1 files changed, 92 insertions, 0 deletions

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index f03ef97c3b21..0037427d8a9d 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -2178,3 +2178,95 @@ void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
         cluster->block_group = NULL;
 }
 
+int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
+                           u64 *trimmed, u64 start, u64 end, u64 minlen)
+{
+        struct btrfs_free_space *entry = NULL;
+        struct btrfs_fs_info *fs_info = block_group->fs_info;
+        u64 bytes = 0;
+        u64 actually_trimmed;
+        int ret = 0;
+
+        *trimmed = 0;
+
+        while (start < end) {
+                spin_lock(&block_group->tree_lock);
+
+                if (block_group->free_space < minlen) {
+                        spin_unlock(&block_group->tree_lock);
+                        break;
+                }
+
+                entry = tree_search_offset(block_group, start, 0, 1);
+                if (!entry)
+                        entry = tree_search_offset(block_group,
+                                                   offset_to_bitmap(block_group,
+                                                                    start),
+                                                   1, 1);
+
+                if (!entry || entry->offset >= end) {
+                        spin_unlock(&block_group->tree_lock);
+                        break;
+                }
+
+                if (entry->bitmap) {
+                        ret = search_bitmap(block_group, entry, &start, &bytes);
+                        if (!ret) {
+                                if (start >= end) {
+                                        spin_unlock(&block_group->tree_lock);
+                                        break;
+                                }
+                                bytes = min(bytes, end - start);
+                                bitmap_clear_bits(block_group, entry,
+                                                  start, bytes);
+                                if (entry->bytes == 0)
+                                        free_bitmap(block_group, entry);
+                        } else {
+                                start = entry->offset + BITS_PER_BITMAP *
+                                        block_group->sectorsize;
+                                spin_unlock(&block_group->tree_lock);
+                                ret = 0;
+                                continue;
+                        }
+                } else {
+                        start = entry->offset;
+                        bytes = min(entry->bytes, end - start);
+                        unlink_free_space(block_group, entry);
+                        kfree(entry);
+                }
+
+                spin_unlock(&block_group->tree_lock);
+
+                if (bytes >= minlen) {
+                        int update_ret;
+                        update_ret = btrfs_update_reserved_bytes(block_group,
+                                                                 bytes, 1, 1);
+
+                        ret = btrfs_error_discard_extent(fs_info->extent_root,
+                                                         start,
+                                                         bytes,
+                                                         &actually_trimmed);
+
+                        btrfs_add_free_space(block_group,
+                                             start, bytes);
+                        if (!update_ret)
+                                btrfs_update_reserved_bytes(block_group,
+                                                            bytes, 0, 1);
+
+                        if (ret)
+                                break;
+                        *trimmed += actually_trimmed;
+                }
+                start += bytes;
+                bytes = 0;
+
+                if (fatal_signal_pending(current)) {
+                        ret = -ERESTARTSYS;
+                        break;
+                }
+
+                cond_resched();
+        }
+
+        return ret;
+}