Pull bcachefs updates from Kent Overstreet:

 - Metadata version 1.8: Stripe sectors accounting, BCH_DATA_unstriped

   This splits out the accounting of dirty sectors and stripe sectors in
   alloc keys; this lets us see stripe buckets that still have unstriped
   data in them.

   This is needed for ensuring that erasure coding is working correctly,
   as well as completing stripe creation after a crash.

 - Metadata version 1.9: Disk accounting rewrite

   The previous disk accounting scheme relied heavily on percpu counters
   that were also sharded by outstanding journal buffer; it was fast but
   not extensible or scalable, and meant that all accounting counters
   were recorded in every journal entry.

   The new disk accounting scheme stores accounting as normal btree
   keys; updates are deltas until they are flushed by the btree write
   buffer.

   This means we have no practical limit on the number of counters, and
   a new tagged union format that's easy to extend.

   We now have counters for compression type/ratio, per-snapshot-id
   usage, per-btree-id usage, and pending rebalance work.

 - Self healing on read IO/checksum error

   Data is now automatically rewritten if we get a read error and then a
   successful retry

 - Mount API conversion (thanks to Thomas Bertschinger)

 - Better lockdep coverage

   Previously, btree node locks were tracked individually by lockdep,
   like any other lock. But we may take _many_ btree node locks
   simultaneously, we easily blow through the limit of 48 locks that
   lockdep can track, leading to lockdep turning itself off.

   Tracking each btree node lock individually isn't really necessary
   since we have our own cycle detector for deadlock avoidance and
   centralized tracking of btree node locks, so we now have a single
   lockdep_map in btree_trans for "any btree nodes are locked".

 - Some more small incremental work towards online check_allocations

 - Lots more debugging improvements

 - Fixes, including:
    - undefined behaviour fixes, originally noted as breaking userspace
      LTO builds
    - fix a spurious warning in fsck_err, reported by Marcin
    - fix an integer overflow on trans->nr_updates, also reported by
      Marcin; this broke during deletion of highly fragmented indirect
      extents

* tag 'bcachefs-2024-07-18.2' of https://evilpiepirate.org/git/bcachefs: (120 commits)
  lockdep: Add comments for lockdep_set_no{validate,track}_class()
  bcachefs: Fix integer overflow on trans->nr_updates
  bcachefs: silence silly kdoc warning
  bcachefs: Fix fsck warning about btree_trans not passed to fsck error
  bcachefs: Add an error message for insufficient rw journal devs
  bcachefs: varint: Avoid left-shift of a negative value
  bcachefs: darray: Don't pass NULL to memcpy()
  bcachefs: Kill bch2_assert_btree_nodes_not_locked()
  bcachefs: Rename BCH_WRITE_DONE -> BCH_WRITE_SUBMITTED
  bcachefs: __bch2_read(): call trans_begin() on every loop iter
  bcachefs: show none if label is not set
  bcachefs: drop packed, aligned from bkey_inode_buf
  bcachefs: btree node scan: fall back to comparing by journal seq
  bcachefs: Add lockdep support for btree node locks
  lockdep: lockdep_set_notrack_class()
  bcachefs: Improve copygc_wait_to_text()
  bcachefs: Convert clock code to u64s
  bcachefs: Improve startup message
  bcachefs: Self healing on read IO error
  bcachefs: Make read_only a mount option again, but hidden
  ...