More bcachefs bugfixes for 6.7: - Fix a rare emergency shutdown path bug: dropping journal pins after the filesystem has mostly been torn down is not what we want. - Fix some concurrency issues with the btree write buffer and journal replay by not using the btree write buffer until journal replay is finished - A fixup from the prior patch to kill journal pre-reservations: at the start of the btree update path, where previously we took a pre-reservation, we do at least want to check the journal watermark. - Fix a race between dropping device metadata and btree node writes, which would re-add a pointer to a device that had just been dropped - Fix one of the SCRU lock warnings, in bch2_compression_stats_to_text(). - Partial fix for a rare transaction paths overflow, when indirect extents had been split by background tasks, by not running certain triggers when they're not needed. - Fix for creating a snapshot with implicit source in a subdirectory of the containing subvolume - Don't unfreeze when we're emergency read-only - Fix for rebalance spinning trying to compress unwritten extentns - Another deleted_inodes fix, for directories - Fix a rare deadlock (usually just an unecessary wait) when flushing the journal with an open journal entry.