From 1465af12e254a68706e110846f59cf0f09683184 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Tue, 22 Sep 2020 10:37:01 +0800 Subject: btrfs: tree-checker: fix false alert caused by legacy btrfs root item Commit 259ee7754b67 ("btrfs: tree-checker: Add ROOT_ITEM check") introduced btrfs root item size check, however btrfs root item has two versions, the legacy one which just ends before generation_v2 member, is smaller than current btrfs root item size. This caused btrfs kernel to reject valid but old tree root leaves. Fix this problem by also allowing legacy root item, since kernel can already handle them pretty well and upgrade to newer root item format when needed. Reported-by: Martin Steigerwald Fixes: 259ee7754b67 ("btrfs: tree-checker: Add ROOT_ITEM check") CC: stable@vger.kernel.org # 5.4+ Tested-By: Martin Steigerwald Reviewed-by: Josef Bacik Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/tree-checker.c | 17 ++++++++++++----- include/uapi/linux/btrfs_tree.h | 14 ++++++++++++++ 2 files changed, 26 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index 7b1fee630f97..f0ffd5ee77bd 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -1035,7 +1035,7 @@ static int check_root_item(struct extent_buffer *leaf, struct btrfs_key *key, int slot) { struct btrfs_fs_info *fs_info = leaf->fs_info; - struct btrfs_root_item ri; + struct btrfs_root_item ri = { 0 }; const u64 valid_root_flags = BTRFS_ROOT_SUBVOL_RDONLY | BTRFS_ROOT_SUBVOL_DEAD; int ret; @@ -1044,14 +1044,21 @@ static int check_root_item(struct extent_buffer *leaf, struct btrfs_key *key, if (ret < 0) return ret; - if (btrfs_item_size_nr(leaf, slot) != sizeof(ri)) { + if (btrfs_item_size_nr(leaf, slot) != sizeof(ri) && + btrfs_item_size_nr(leaf, slot) != btrfs_legacy_root_item_size()) { generic_err(leaf, slot, - "invalid root item size, have %u expect %zu", - btrfs_item_size_nr(leaf, slot), sizeof(ri)); + "invalid root item size, have %u expect %zu or %u", + btrfs_item_size_nr(leaf, slot), sizeof(ri), + btrfs_legacy_root_item_size()); } + /* + * For legacy root item, the members starting at generation_v2 will be + * all filled with 0. + * And since we allow geneartion_v2 as 0, it will still pass the check. + */ read_extent_buffer(leaf, &ri, btrfs_item_ptr_offset(leaf, slot), - sizeof(ri)); + btrfs_item_size_nr(leaf, slot)); /* Generation related */ if (btrfs_root_generation(&ri) > diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h index 9ba64ca6b4ac..6b885982ece6 100644 --- a/include/uapi/linux/btrfs_tree.h +++ b/include/uapi/linux/btrfs_tree.h @@ -4,6 +4,11 @@ #include #include +#ifdef __KERNEL__ +#include +#else +#include +#endif /* * This header contains the structure definitions and constants used @@ -644,6 +649,15 @@ struct btrfs_root_item { __le64 reserved[8]; /* for future */ } __attribute__ ((__packed__)); +/* + * Btrfs root item used to be smaller than current size. The old format ends + * at where member generation_v2 is. + */ +static inline __u32 btrfs_legacy_root_item_size(void) +{ + return offsetof(struct btrfs_root_item, generation_v2); +} + /* * this is used for both forward and backward root refs */ -- cgit v1.2.3