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-rw-r--r--fs/btrfs/block-group.c49
1 files changed, 47 insertions, 2 deletions
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 08017b180..9f77565bd 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1318,6 +1318,7 @@ out:
*/
void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
{
+ LIST_HEAD(retry_list);
struct btrfs_block_group *block_group;
struct btrfs_space_info *space_info;
struct btrfs_trans_handle *trans;
@@ -1339,6 +1340,7 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
spin_lock(&fs_info->unused_bgs_lock);
while (!list_empty(&fs_info->unused_bgs)) {
+ u64 used;
int trimming;
block_group = list_first_entry(&fs_info->unused_bgs,
@@ -1374,9 +1376,9 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
goto next;
}
+ spin_lock(&space_info->lock);
spin_lock(&block_group->lock);
- if (block_group->reserved || block_group->pinned ||
- block_group->used || block_group->ro ||
+ if (btrfs_is_block_group_used(block_group) || block_group->ro ||
list_is_singular(&block_group->list)) {
/*
* We want to bail if we made new allocations or have
@@ -1386,10 +1388,49 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
*/
trace_btrfs_skip_unused_block_group(block_group);
spin_unlock(&block_group->lock);
+ spin_unlock(&space_info->lock);
+ up_write(&space_info->groups_sem);
+ goto next;
+ }
+
+ /*
+ * The block group may be unused but there may be space reserved
+ * accounting with the existence of that block group, that is,
+ * space_info->bytes_may_use was incremented by a task but no
+ * space was yet allocated from the block group by the task.
+ * That space may or may not be allocated, as we are generally
+ * pessimistic about space reservation for metadata as well as
+ * for data when using compression (as we reserve space based on
+ * the worst case, when data can't be compressed, and before
+ * actually attempting compression, before starting writeback).
+ *
+ * So check if the total space of the space_info minus the size
+ * of this block group is less than the used space of the
+ * space_info - if that's the case, then it means we have tasks
+ * that might be relying on the block group in order to allocate
+ * extents, and add back the block group to the unused list when
+ * we finish, so that we retry later in case no tasks ended up
+ * needing to allocate extents from the block group.
+ */
+ used = btrfs_space_info_used(space_info, true);
+ if (space_info->total_bytes - block_group->length < used) {
+ /*
+ * Add a reference for the list, compensate for the ref
+ * drop under the "next" label for the
+ * fs_info->unused_bgs list.
+ */
+ btrfs_get_block_group(block_group);
+ list_add_tail(&block_group->bg_list, &retry_list);
+
+ trace_btrfs_skip_unused_block_group(block_group);
+ spin_unlock(&block_group->lock);
+ spin_unlock(&space_info->lock);
up_write(&space_info->groups_sem);
goto next;
}
+
spin_unlock(&block_group->lock);
+ spin_unlock(&space_info->lock);
/* We don't want to force the issue, only flip if it's ok. */
ret = inc_block_group_ro(block_group, 0);
@@ -1513,12 +1554,16 @@ next:
btrfs_put_block_group(block_group);
spin_lock(&fs_info->unused_bgs_lock);
}
+ list_splice_tail(&retry_list, &fs_info->unused_bgs);
spin_unlock(&fs_info->unused_bgs_lock);
mutex_unlock(&fs_info->reclaim_bgs_lock);
return;
flip_async:
btrfs_end_transaction(trans);
+ spin_lock(&fs_info->unused_bgs_lock);
+ list_splice_tail(&retry_list, &fs_info->unused_bgs);
+ spin_unlock(&fs_info->unused_bgs_lock);
mutex_unlock(&fs_info->reclaim_bgs_lock);
btrfs_put_block_group(block_group);
btrfs_discard_punt_unused_bgs_list(fs_info);