From 2c47e605a91dde6b0514f689645e7ab336c8592a Mon Sep 17 00:00:00 2001 From: Yan Zheng Date: Sat, 27 Jun 2009 21:07:35 -0400 Subject: Btrfs: update backrefs while dropping snapshot The new backref format has restriction on type of backref item. If a tree block isn't referenced by its owner tree, full backrefs must be used for the pointers in it. When a tree block loses its owner tree's reference, backrefs for the pointers in it should be updated to full backrefs. Current btrfs_drop_snapshot misses the code that updates backrefs, so it's unsafe for general use. This patch adds backrefs update code to btrfs_drop_snapshot. It isn't a problem in the restricted form btrfs_drop_snapshot is used today, but for general snapshot deletion this update is required. Signed-off-by: Yan Zheng Signed-off-by: Chris Mason --- fs/btrfs/transaction.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'fs/btrfs/transaction.c') diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 4e83457ea253..2dbf1c1f56ee 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -593,6 +593,7 @@ int btrfs_defrag_root(struct btrfs_root *root, int cacheonly) return 0; } +#if 0 /* * when dropping snapshots, we generate a ton of delayed refs, and it makes * sense not to join the transaction while it is trying to flush the current @@ -681,6 +682,7 @@ int btrfs_drop_dead_root(struct btrfs_root *root) btrfs_btree_balance_dirty(tree_root, nr); return ret; } +#endif /* * new snapshots need to be created at a very specific time in the @@ -1081,7 +1083,7 @@ int btrfs_clean_old_snapshots(struct btrfs_root *root) while (!list_empty(&list)) { root = list_entry(list.next, struct btrfs_root, root_list); list_del_init(&root->root_list); - btrfs_drop_dead_root(root); + btrfs_drop_snapshot(root, 0); } return 0; } -- cgit v1.2.3-58-ga151