btrfs: do not abort transaction on failure to write log tree when syncing log

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@leemhuis.info/
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>
This commit is contained in:
Filipe Manana 2023-01-10 14:56:37 +00:00 committed by David Sterba
parent 94cd63ae67
commit 16199ad9eb
2 changed files with 8 additions and 3 deletions

View File

@ -367,7 +367,14 @@ 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;
}

View File

@ -2980,7 +2980,6 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
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;
@ -3112,7 +3111,6 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
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;
}