* Long running balances can keep us blocked here for eternity, so
* simply skip deletion if we're unable to get the mutex.
*/
- if (!mutex_trylock(&fs_info->delete_unused_bgs_mutex))
+ if (!mutex_trylock(&fs_info->reclaim_bgs_lock))
return;
spin_lock(&fs_info->unused_bgs_lock);
spin_lock(&fs_info->unused_bgs_lock);
}
spin_unlock(&fs_info->unused_bgs_lock);
- mutex_unlock(&fs_info->delete_unused_bgs_mutex);
+ mutex_unlock(&fs_info->reclaim_bgs_lock);
return;
flip_async:
btrfs_end_transaction(trans);
- mutex_unlock(&fs_info->delete_unused_bgs_mutex);
+ mutex_unlock(&fs_info->reclaim_bgs_lock);
btrfs_put_block_group(block_group);
btrfs_discard_punt_unused_bgs_list(fs_info);
}
spin_unlock(&fs_info->unused_bgs_lock);
}
+void btrfs_reclaim_bgs_work(struct work_struct *work)
+{
+ struct btrfs_fs_info *fs_info =
+ container_of(work, struct btrfs_fs_info, reclaim_bgs_work);
+ struct btrfs_block_group *bg;
+ struct btrfs_space_info *space_info;
+ int ret;
+
+ if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags))
+ return;
+
+ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE))
+ return;
+
+ mutex_lock(&fs_info->reclaim_bgs_lock);
+ spin_lock(&fs_info->unused_bgs_lock);
+ while (!list_empty(&fs_info->reclaim_bgs)) {
+ bg = list_first_entry(&fs_info->reclaim_bgs,
+ struct btrfs_block_group,
+ bg_list);
+ list_del_init(&bg->bg_list);
+
+ space_info = bg->space_info;
+ spin_unlock(&fs_info->unused_bgs_lock);
+
+ /* Don't race with allocators so take the groups_sem */
+ down_write(&space_info->groups_sem);
+
+ spin_lock(&bg->lock);
+ if (bg->reserved || bg->pinned || bg->ro) {
+ /*
+ * We want to bail if we made new allocations or have
+ * outstanding allocations in this block group. We do
+ * the ro check in case balance is currently acting on
+ * this block group.
+ */
+ spin_unlock(&bg->lock);
+ up_write(&space_info->groups_sem);
+ goto next;
+ }
+ spin_unlock(&bg->lock);
+
+ /* Get out fast, in case we're unmounting the filesystem */
+ if (btrfs_fs_closing(fs_info)) {
+ up_write(&space_info->groups_sem);
+ goto next;
+ }
+
+ ret = inc_block_group_ro(bg, 0);
+ up_write(&space_info->groups_sem);
+ if (ret < 0)
+ goto next;
+
+ btrfs_info(fs_info, "reclaiming chunk %llu with %llu%% used",
+ bg->start, div_u64(bg->used * 100, bg->length));
+ trace_btrfs_reclaim_block_group(bg);
+ ret = btrfs_relocate_chunk(fs_info, bg->start);
+ if (ret)
+ btrfs_err(fs_info, "error relocating chunk %llu",
+ bg->start);
+
+next:
+ btrfs_put_block_group(bg);
+ spin_lock(&fs_info->unused_bgs_lock);
+ }
+ spin_unlock(&fs_info->unused_bgs_lock);
+ mutex_unlock(&fs_info->reclaim_bgs_lock);
+ btrfs_exclop_finish(fs_info);
+}
+
+void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info)
+{
+ spin_lock(&fs_info->unused_bgs_lock);
+ if (!list_empty(&fs_info->reclaim_bgs))
+ queue_work(system_unbound_wq, &fs_info->reclaim_bgs_work);
+ spin_unlock(&fs_info->unused_bgs_lock);
+}
+
+void btrfs_mark_bg_to_reclaim(struct btrfs_block_group *bg)
+{
+ struct btrfs_fs_info *fs_info = bg->fs_info;
+
+ spin_lock(&fs_info->unused_bgs_lock);
+ if (list_empty(&bg->bg_list)) {
+ btrfs_get_block_group(bg);
+ trace_btrfs_add_reclaim_block_group(bg);
+ list_add_tail(&bg->bg_list, &fs_info->reclaim_bgs);
+ }
+ spin_unlock(&fs_info->unused_bgs_lock);
+}
+
static int read_bg_from_eb(struct btrfs_fs_info *fs_info, struct btrfs_key *key,
struct btrfs_path *path)
{
struct btrfs_trans_handle *trans;
u64 alloc_flags;
int ret;
+ bool dirty_bg_running;
-again:
- trans = btrfs_join_transaction(fs_info->extent_root);
- if (IS_ERR(trans))
- return PTR_ERR(trans);
+ do {
+ trans = btrfs_join_transaction(fs_info->extent_root);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
- /*
- * we're not allowed to set block groups readonly after the dirty
- * block groups cache has started writing. If it already started,
- * back off and let this transaction commit
- */
- mutex_lock(&fs_info->ro_block_group_mutex);
- if (test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &trans->transaction->flags)) {
- u64 transid = trans->transid;
+ dirty_bg_running = false;
- mutex_unlock(&fs_info->ro_block_group_mutex);
- btrfs_end_transaction(trans);
+ /*
+ * We're not allowed to set block groups readonly after the dirty
+ * block group cache has started writing. If it already started,
+ * back off and let this transaction commit.
+ */
+ mutex_lock(&fs_info->ro_block_group_mutex);
+ if (test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &trans->transaction->flags)) {
+ u64 transid = trans->transid;
- ret = btrfs_wait_for_commit(fs_info, transid);
- if (ret)
- return ret;
- goto again;
- }
+ mutex_unlock(&fs_info->ro_block_group_mutex);
+ btrfs_end_transaction(trans);
+
+ ret = btrfs_wait_for_commit(fs_info, transid);
+ if (ret)
+ return ret;
+ dirty_bg_running = true;
+ }
+ } while (dirty_bg_running);
if (do_chunk_alloc) {
/*
*/
void check_system_chunk(struct btrfs_trans_handle *trans, u64 type)
{
+ struct btrfs_transaction *cur_trans = trans->transaction;
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_space_info *info;
u64 left;
lockdep_assert_held(&fs_info->chunk_mutex);
info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
+again:
spin_lock(&info->lock);
left = info->total_bytes - btrfs_space_info_used(info, true);
spin_unlock(&info->lock);
if (left < thresh) {
u64 flags = btrfs_system_alloc_profile(fs_info);
+ u64 reserved = atomic64_read(&cur_trans->chunk_bytes_reserved);
+
+ /*
+ * If there's not available space for the chunk tree (system
+ * space) and there are other tasks that reserved space for
+ * creating a new system block group, wait for them to complete
+ * the creation of their system block group and release excess
+ * reserved space. We do this because:
+ *
+ * *) We can end up allocating more system chunks than necessary
+ * when there are multiple tasks that are concurrently
+ * allocating block groups, which can lead to exhaustion of
+ * the system array in the superblock;
+ *
+ * *) If we allocate extra and unnecessary system block groups,
+ * despite being empty for a long time, and possibly forever,
+ * they end not being added to the list of unused block groups
+ * because that typically happens only when deallocating the
+ * last extent from a block group - which never happens since
+ * we never allocate from them in the first place. The few
+ * exceptions are when mounting a filesystem or running scrub,
+ * which add unused block groups to the list of unused block
+ * groups, to be deleted by the cleaner kthread.
+ * And even when they are added to the list of unused block
+ * groups, it can take a long time until they get deleted,
+ * since the cleaner kthread might be sleeping or busy with
+ * other work (deleting subvolumes, running delayed iputs,
+ * defrag scheduling, etc);
+ *
+ * This is rare in practice, but can happen when too many tasks
+ * are allocating blocks groups in parallel (via fallocate())
+ * and before the one that reserved space for a new system block
+ * group finishes the block group creation and releases the space
+ * reserved in excess (at btrfs_create_pending_block_groups()),
+ * other tasks end up here and see free system space temporarily
+ * not enough for updating the chunk tree.
+ *
+ * We unlock the chunk mutex before waiting for such tasks and
+ * lock it again after the wait, otherwise we would deadlock.
+ * It is safe to do so because allocating a system chunk is the
+ * first thing done while allocating a new block group.
+ */
+ if (reserved > trans->chunk_bytes_reserved) {
+ const u64 min_needed = reserved - thresh;
+
+ mutex_unlock(&fs_info->chunk_mutex);
+ wait_event(cur_trans->chunk_reserve_wait,
+ atomic64_read(&cur_trans->chunk_bytes_reserved) <=
+ min_needed);
+ mutex_lock(&fs_info->chunk_mutex);
+ goto again;
+ }
/*
* Ignore failure to create system chunk. We might end up not
ret = btrfs_block_rsv_add(fs_info->chunk_root,
&fs_info->chunk_block_rsv,
thresh, BTRFS_RESERVE_NO_FLUSH);
- if (!ret)
+ if (!ret) {
+ atomic64_add(thresh, &cur_trans->chunk_bytes_reserved);
trans->chunk_bytes_reserved += thresh;
+ }
}
}
}
spin_unlock(&info->unused_bgs_lock);
+ spin_lock(&info->unused_bgs_lock);
+ while (!list_empty(&info->reclaim_bgs)) {
+ block_group = list_first_entry(&info->reclaim_bgs,
+ struct btrfs_block_group,
+ bg_list);
+ list_del_init(&block_group->bg_list);
+ btrfs_put_block_group(block_group);
+ }
+ spin_unlock(&info->unused_bgs_lock);
+
spin_lock(&info->block_group_cache_lock);
while ((n = rb_last(&info->block_group_cache_tree)) != NULL) {
block_group = rb_entry(n, struct btrfs_block_group,
projects / linux-2.6-microblaze.git / blobdiff