From c251267c8826027af32fe7195650d29797539847 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 17 Nov 2017 14:50:46 -0500 Subject: btrfs: clear space cache inode generation always commit 8e138e0d92c6c9d3d481674fb14e3439b495be37 upstream. We discovered a box that had double allocations, and suspected the space cache may be to blame. While auditing the write out path I noticed that if we've already setup the space cache we will just carry on. This means that any error we hit after cache_save_setup before we go to actually write the cache out we won't reset the inode generation, so whatever was already written will be considered correct, except it'll be stale. Fix this by _always_ resetting the generation on the block group inode, this way we only ever have valid or invalid cache. With this patch I was no longer able to reproduce cache corruption with dm-log-writes and my bpf error injection tool. Signed-off-by: Josef Bacik Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/extent-tree.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'fs') diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 705bb5f5a87f..c4cff5cc9c93 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3397,13 +3397,6 @@ again: goto again; } - /* We've already setup this transaction, go ahead and exit */ - if (block_group->cache_generation == trans->transid && - i_size_read(inode)) { - dcs = BTRFS_DC_SETUP; - goto out_put; - } - /* * We want to set the generation to 0, that way if anything goes wrong * from here on out we know not to trust this cache when we load up next @@ -3427,6 +3420,13 @@ again: } WARN_ON(ret); + /* We've already setup this transaction, go ahead and exit */ + if (block_group->cache_generation == trans->transid && + i_size_read(inode)) { + dcs = BTRFS_DC_SETUP; + goto out_put; + } + if (i_size_read(inode) > 0) { ret = btrfs_check_trunc_cache_free_space(root, &root->fs_info->global_block_rsv); -- cgit v1.2.3