The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ad1d8c439978ede77cbf73cbdd11bafe810421a5 Mon Sep 17 00:00:00 2001

From: Filipe Manana fdmanana@suse.com Date: Mon, 2 Dec 2019 11:01:03 +0000 Subject: [PATCH] Btrfs: make tree checker detect checksum items with overlapping ranges

Having checksum items, either on the checksums tree or in a log tree, that represent ranges that overlap each other is a sign of a corruption. Such case confuses the checksum lookup code and can result in not being able to find checksums or find stale checksums.

So add a check for such case.

This is motivated by a recent fix for a case where a log tree had checksum items covering ranges that overlap each other due to extent cloning, and resulted in missing checksums after replaying the log tree. It also helps detect past issues such as stale and outdated checksums due to overlapping, commit 27b9a8122ff71a ("Btrfs: fix csum tree corruption, duplicate and outdated checksums").

CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: David Sterba dsterba@suse.com

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index 092b8ece36d7..97f3520b8d98 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -332,7 +332,7 @@ static int check_extent_data_item(struct extent_buffer *leaf, }

static int check_csum_item(struct extent_buffer *leaf, struct btrfs_key *key, - int slot) + int slot, struct btrfs_key *prev_key) { struct btrfs_fs_info *fs_info = leaf->fs_info; u32 sectorsize = fs_info->sectorsize; @@ -356,6 +356,20 @@ static int check_csum_item(struct extent_buffer *leaf, struct btrfs_key *key, btrfs_item_size_nr(leaf, slot), csumsize); return -EUCLEAN; } + if (slot > 0 && prev_key->type == BTRFS_EXTENT_CSUM_KEY) { + u64 prev_csum_end; + u32 prev_item_size; + + prev_item_size = btrfs_item_size_nr(leaf, slot - 1); + prev_csum_end = (prev_item_size / csumsize) * sectorsize; + prev_csum_end += prev_key->offset; + if (prev_csum_end > key->offset) { + generic_err(leaf, slot - 1, +"csum end range (%llu) goes beyond the start range (%llu) of the next csum item", + prev_csum_end, key->offset); + return -EUCLEAN; + } + } return 0; }

@@ -1355,7 +1369,7 @@ static int check_leaf_item(struct extent_buffer *leaf, ret = check_extent_data_item(leaf, key, slot, prev_key); break; case BTRFS_EXTENT_CSUM_KEY: - ret = check_csum_item(leaf, key, slot); + ret = check_csum_item(leaf, key, slot, prev_key); break; case BTRFS_DIR_ITEM_KEY: case BTRFS_DIR_INDEX_KEY: