+static int should_retry_reserve(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_block_rsv *block_rsv,
+ u64 num_bytes, int *retries)
+{
+ struct btrfs_space_info *space_info = block_rsv->space_info;
+ int ret;
+
+ if ((*retries) > 2)
+ return -ENOSPC;
+
+ ret = maybe_allocate_chunk(trans, root, space_info, num_bytes);
+ if (ret)
+ return 1;
+
+ if (trans && trans->transaction->in_commit)
+ return -ENOSPC;
+
+ ret = shrink_delalloc(trans, root, space_info, num_bytes);
+ if (ret)
+ return ret;
+
+ spin_lock(&space_info->lock);
+ if (space_info->bytes_pinned < num_bytes)
+ ret = 1;
+ spin_unlock(&space_info->lock);
+ if (ret)
+ return -ENOSPC;
+
+ (*retries)++;
+
+ if (trans)
+ return -EAGAIN;
+
+ trans = btrfs_join_transaction(root, 1);
+ BUG_ON(IS_ERR(trans));
+ ret = btrfs_commit_transaction(trans, root);
+ BUG_ON(ret);
+
+ return 1;
+}
+
+static int reserve_metadata_bytes(struct btrfs_block_rsv *block_rsv,
+ u64 num_bytes)
+{
+ struct btrfs_space_info *space_info = block_rsv->space_info;
+ u64 unused;
+ int ret = -ENOSPC;
+
+ spin_lock(&space_info->lock);
+ unused = space_info->bytes_used + space_info->bytes_reserved +
+ space_info->bytes_pinned + space_info->bytes_readonly;
+
+ if (unused < space_info->total_bytes)
+ unused = space_info->total_bytes - unused;
+ else
+ unused = 0;
+
+ if (unused >= num_bytes) {
+ if (block_rsv->priority >= 10) {
+ space_info->bytes_reserved += num_bytes;
+ ret = 0;
+ } else {
+ if ((unused + block_rsv->reserved) *
+ block_rsv->priority >=
+ (num_bytes + block_rsv->reserved) * 10) {
+ space_info->bytes_reserved += num_bytes;
+ ret = 0;
+ }
+ }
+ }
+ spin_unlock(&space_info->lock);
+
+ return ret;
+}
+
+static struct btrfs_block_rsv *get_block_rsv(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ struct btrfs_block_rsv *block_rsv;
+ if (root->ref_cows)
+ block_rsv = trans->block_rsv;
+ else
+ block_rsv = root->block_rsv;
+
+ if (!block_rsv)
+ block_rsv = &root->fs_info->empty_block_rsv;
+
+ return block_rsv;
+}
+
+static int block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv,
+ u64 num_bytes)
+{
+ int ret = -ENOSPC;
+ spin_lock(&block_rsv->lock);
+ if (block_rsv->reserved >= num_bytes) {
+ block_rsv->reserved -= num_bytes;
+ if (block_rsv->reserved < block_rsv->size)
+ block_rsv->full = 0;
+ ret = 0;
+ }
+ spin_unlock(&block_rsv->lock);
+ return ret;
+}
+
+static void block_rsv_add_bytes(struct btrfs_block_rsv *block_rsv,
+ u64 num_bytes, int update_size)
+{
+ spin_lock(&block_rsv->lock);
+ block_rsv->reserved += num_bytes;
+ if (update_size)
+ block_rsv->size += num_bytes;
+ else if (block_rsv->reserved >= block_rsv->size)
+ block_rsv->full = 1;
+ spin_unlock(&block_rsv->lock);
+}
+
+void block_rsv_release_bytes(struct btrfs_block_rsv *block_rsv,
+ struct btrfs_block_rsv *dest, u64 num_bytes)
+{
+ struct btrfs_space_info *space_info = block_rsv->space_info;
+
+ spin_lock(&block_rsv->lock);
+ if (num_bytes == (u64)-1)
+ num_bytes = block_rsv->size;
+ block_rsv->size -= num_bytes;
+ if (block_rsv->reserved >= block_rsv->size) {
+ num_bytes = block_rsv->reserved - block_rsv->size;
+ block_rsv->reserved = block_rsv->size;
+ block_rsv->full = 1;
+ } else {
+ num_bytes = 0;
+ }
+ spin_unlock(&block_rsv->lock);
+
+ if (num_bytes > 0) {
+ if (dest) {
+ block_rsv_add_bytes(dest, num_bytes, 0);
+ } else {
+ spin_lock(&space_info->lock);
+ space_info->bytes_reserved -= num_bytes;
+ spin_unlock(&space_info->lock);
+ }
+ }
+}
+
+static int block_rsv_migrate_bytes(struct btrfs_block_rsv *src,
+ struct btrfs_block_rsv *dst, u64 num_bytes)
+{
+ int ret;
+
+ ret = block_rsv_use_bytes(src, num_bytes);
+ if (ret)
+ return ret;
+
+ block_rsv_add_bytes(dst, num_bytes, 1);
+ return 0;
+}
+
+void btrfs_init_block_rsv(struct btrfs_block_rsv *rsv)
+{
+ memset(rsv, 0, sizeof(*rsv));
+ spin_lock_init(&rsv->lock);
+ atomic_set(&rsv->usage, 1);
+ rsv->priority = 6;
+ INIT_LIST_HEAD(&rsv->list);
+}
+
+struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_root *root)
+{
+ struct btrfs_block_rsv *block_rsv;
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ u64 alloc_target;
+
+ block_rsv = kmalloc(sizeof(*block_rsv), GFP_NOFS);
+ if (!block_rsv)
+ return NULL;
+
+ btrfs_init_block_rsv(block_rsv);
+
+ alloc_target = btrfs_get_alloc_profile(root, 0);
+ block_rsv->space_info = __find_space_info(fs_info,
+ BTRFS_BLOCK_GROUP_METADATA);
+
+ return block_rsv;
+}
+
+void btrfs_free_block_rsv(struct btrfs_root *root,
+ struct btrfs_block_rsv *rsv)
+{
+ if (rsv && atomic_dec_and_test(&rsv->usage)) {
+ btrfs_block_rsv_release(root, rsv, (u64)-1);
+ if (!rsv->durable)
+ kfree(rsv);
+ }
+}
+
+/*
+ * make the block_rsv struct be able to capture freed space.
+ * the captured space will re-add to the the block_rsv struct
+ * after transaction commit
+ */
+void btrfs_add_durable_block_rsv(struct btrfs_fs_info *fs_info,
+ struct btrfs_block_rsv *block_rsv)
+{
+ block_rsv->durable = 1;
+ mutex_lock(&fs_info->durable_block_rsv_mutex);
+ list_add_tail(&block_rsv->list, &fs_info->durable_block_rsv_list);
+ mutex_unlock(&fs_info->durable_block_rsv_mutex);
+}
+
+int btrfs_block_rsv_add(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_block_rsv *block_rsv,
+ u64 num_bytes, int *retries)
+{
+ int ret;
+
+ if (num_bytes == 0)
+ return 0;
+again:
+ ret = reserve_metadata_bytes(block_rsv, num_bytes);
+ if (!ret) {
+ block_rsv_add_bytes(block_rsv, num_bytes, 1);
+ return 0;
+ }
+
+ ret = should_retry_reserve(trans, root, block_rsv, num_bytes, retries);
+ if (ret > 0)
+ goto again;
+
+ return ret;
+}
+
+int btrfs_block_rsv_check(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_block_rsv *block_rsv,
+ u64 min_reserved, int min_factor)
+{
+ u64 num_bytes = 0;
+ int commit_trans = 0;
+ int ret = -ENOSPC;
+
+ if (!block_rsv)
+ return 0;
+
+ spin_lock(&block_rsv->lock);
+ if (min_factor > 0)
+ num_bytes = div_factor(block_rsv->size, min_factor);
+ if (min_reserved > num_bytes)
+ num_bytes = min_reserved;
+
+ if (block_rsv->reserved >= num_bytes) {
+ ret = 0;
+ } else {
+ num_bytes -= block_rsv->reserved;
+ if (block_rsv->durable &&
+ block_rsv->freed[0] + block_rsv->freed[1] >= num_bytes)
+ commit_trans = 1;
+ }
+ spin_unlock(&block_rsv->lock);
+ if (!ret)
+ return 0;
+
+ if (block_rsv->refill_used) {
+ ret = reserve_metadata_bytes(block_rsv, num_bytes);
+ if (!ret) {
+ block_rsv_add_bytes(block_rsv, num_bytes, 0);
+ return 0;
+ }
+ }
+
+ if (commit_trans) {
+ if (trans)
+ return -EAGAIN;
+
+ trans = btrfs_join_transaction(root, 1);
+ BUG_ON(IS_ERR(trans));
+ ret = btrfs_commit_transaction(trans, root);
+ return 0;
+ }
+
+ WARN_ON(1);
+ printk(KERN_INFO"block_rsv size %llu reserved %llu freed %llu %llu\n",
+ block_rsv->size, block_rsv->reserved,
+ block_rsv->freed[0], block_rsv->freed[1]);
+
+ return -ENOSPC;
+}
+
+int btrfs_block_rsv_migrate(struct btrfs_block_rsv *src_rsv,
+ struct btrfs_block_rsv *dst_rsv,
+ u64 num_bytes)
+{
+ return block_rsv_migrate_bytes(src_rsv, dst_rsv, num_bytes);
+}
+
+void btrfs_block_rsv_release(struct btrfs_root *root,
+ struct btrfs_block_rsv *block_rsv,
+ u64 num_bytes)
+{
+ struct btrfs_block_rsv *global_rsv = &root->fs_info->global_block_rsv;
+ if (global_rsv->full || global_rsv == block_rsv ||
+ block_rsv->space_info != global_rsv->space_info)
+ global_rsv = NULL;
+ block_rsv_release_bytes(block_rsv, global_rsv, num_bytes);
+}
+
+static void init_global_block_rsv(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_space_info *space_info;
+
+ space_info = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
+ fs_info->chunk_block_rsv.space_info = space_info;
+ fs_info->chunk_block_rsv.priority = 10;
+
+ space_info = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
+ fs_info->trans_block_rsv.space_info = space_info;
+ fs_info->empty_block_rsv.space_info = space_info;
+ fs_info->empty_block_rsv.priority = 10;
+
+ fs_info->chunk_root->block_rsv = &fs_info->chunk_block_rsv;
+}
+