1 files changed, 34 insertions, 9 deletions

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 3b8d8fa8d767..9cb511d8cd9d 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -306,25 +306,19 @@ static inline u64 calc_global_rsv_need_space(struct btrfs_block_rsv *global)
 	return (global->size << 1);
 }
 
-int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
-			 struct btrfs_space_info *space_info, u64 bytes,
-			 enum btrfs_reserve_flush_enum flush)
+static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
+			  struct btrfs_space_info *space_info,
+			  enum btrfs_reserve_flush_enum flush)
 {
 	u64 profile;
 	u64 avail;
-	u64 used;
 	int factor;
 
-	/* Don't overcommit when in mixed mode. */
-	if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
-		return 0;
-
 	if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
 		profile = btrfs_system_alloc_profile(fs_info);
 	else
 		profile = btrfs_metadata_alloc_profile(fs_info);
 
-	used = btrfs_space_info_used(space_info, true);
 	avail = atomic64_read(&fs_info->free_chunk_space);
 
 	/*
@@ -345,6 +339,22 @@ int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
 		avail >>= 3;
 	else
 		avail >>= 1;
+	return avail;
+}
+
+int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
+			 struct btrfs_space_info *space_info, u64 bytes,
+			 enum btrfs_reserve_flush_enum flush)
+{
+	u64 avail;
+	u64 used;
+
+	/* Don't overcommit when in mixed mode */
+	if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
+		return 0;
+
+	used = btrfs_space_info_used(space_info, true);
+	avail = calc_available_free_space(fs_info, space_info, flush);
 
 	if (used + bytes < space_info->total_bytes + avail)
 		return 1;
@@ -776,6 +786,7 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
 {
 	struct reserve_ticket *ticket;
 	u64 used;
+	u64 avail;
 	u64 expected;
 	u64 to_reclaim = 0;
 
@@ -783,6 +794,20 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
 		to_reclaim += ticket->bytes;
 	list_for_each_entry(ticket, &space_info->priority_tickets, list)
 		to_reclaim += ticket->bytes;
+
+	avail = calc_available_free_space(fs_info, space_info,
+					  BTRFS_RESERVE_FLUSH_ALL);
+	used = btrfs_space_info_used(space_info, true);
+
+	/*
+	 * We may be flushing because suddenly we have less space than we had
+	 * before, and now we're well over-committed based on our current free
+	 * space.  If that's the case add in our overage so we make sure to put
+	 * appropriate pressure on the flushing state machine.
+	 */
+	if (space_info->total_bytes + avail < used)
+		to_reclaim += used - (space_info->total_bytes + avail);
+
 	if (to_reclaim)
 		return to_reclaim;