From: Filipe Manana fdmanana@suse.com
commit 16199ad9eb6db60a6b10794a09fc1ac6d09312ff upstream.
When syncing the log, if we fail to write log tree extent buffers, we mark the log for a full commit and abort the transaction. However we don't need to abort the transaction, all we really need to do is to make sure no one can commit a superblock pointing to new log tree roots. Just because we got a failure writing extent buffers for a log tree, it does not mean we will also fail to do a transaction commit.
One particular case is if due to a bug somewhere, when writing log tree extent buffers, the tree checker detects some corruption and the writeout fails because of that. Aborting the transaction can be very disruptive for a user, specially if the issue happened on a root filesystem. One example is the scenario in the Link tag below, where an isolated corruption on log tree leaves was causing transaction aborts when syncing the log.
Link: https://lore.kernel.org/linux-btrfs/ae169fc6-f504-28f0-a098-6fa6a4dfb612@lee... CC: stable@vger.kernel.org # 5.15+ Reviewed-by: Josef Bacik josef@toxicpanda.com Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/disk-io.c | 9 ++++++++- fs/btrfs/tree-log.c | 2 -- 2 files changed, 8 insertions(+), 3 deletions(-)
--- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -344,7 +344,14 @@ error: btrfs_print_tree(eb, 0); btrfs_err(fs_info, "block=%llu write time tree block corruption detected", eb->start); - WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); + /* + * Be noisy if this is an extent buffer from a log tree. We don't abort + * a transaction in case there's a bad log tree extent buffer, we just + * fallback to a transaction commit. Still we want to know when there is + * a bad log tree extent buffer, as that may signal a bug somewhere. + */ + WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG) || + btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID); return ret; }
--- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -3011,7 +3011,6 @@ int btrfs_sync_log(struct btrfs_trans_ha ret = 0; if (ret) { blk_finish_plug(&plug); - btrfs_abort_transaction(trans, ret); btrfs_set_log_full_commit(trans); mutex_unlock(&root->log_mutex); goto out; @@ -3143,7 +3142,6 @@ int btrfs_sync_log(struct btrfs_trans_ha goto out_wake_log_root; } else if (ret) { btrfs_set_log_full_commit(trans); - btrfs_abort_transaction(trans, ret); mutex_unlock(&log_root_tree->log_mutex); goto out_wake_log_root; }