Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Long form version of bch2_btree_path_to_text() - useful in error
messages and tracepoints.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

small cleanup
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

debug helper
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

better btree node read path error messages
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

- fix assorted (harmless) off-by-one errors
- we were inconsistent on whether out->pos stays <= out->size on
  overflow; now it does, and printbuf.overflow exists to indicate if a
  printbuf has overflowed
- factor out printbuf_advance_pos()
- printbuf_nul_terminate_reserved(); use this to reduce the number of
  printbuf_make_room() calls
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

We need to be able to test these paths in dry run mode.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

When a superblock write is silently dropped or it's been modified by
another process we need to know which device it was.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Fix another shift-by-64 by factoring out a common helper for
bch2_bkey_format_invalid() and bformat_needs_redo() (where it was
already fixed).

Reported-by: syzbot+9833a1d29d4a44361e2c@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Btree nodes are log structured; thus, we need to emit whiteouts when
we're deleting a key that's been written out to disk.

k->needs_whiteout tracks whether a key will need a whiteout when it's
deleted, and this requires some careful handling; e.g. the key we're
deleting may not have been written out to disk, but it may have
overwritten a key that was - thus we need to carry this flag around on
overwrites.

Invariants:
There may be multiple key for the same position in a given node (because
of overwrites), but only one of them will be a live (non deleted) key,
and only one key for a given position will have the needs_whiteout flag
set.

Additionally, we don't want to carry around whiteouts that need to be
written in the main searchable part of a btree node - btree_iter_peek()
will have to skip past them, and this can lead to an O(n^2) issues when
doing sequential deletions (e.g. inode rm/truncate). So there's a
separate region in the btree node buffer for unwritten whiteouts; these
are merge sorted with the rest of the keys we're writing in the btree
node write path.

The unwritten whiteouts was a later optimization that bch2_sort_keys()
didn't take into account; the unwritten whiteouts area means that we
never have deleted keys with needs_whiteout set in the main searchable
part of a btree node.

That means we can simplify and optimize some sort paths, and eliminate
an assertion that syzbot found:

- Unless we're in the btree node write path, it's always ok to drop
  whiteouts when sorting
- When sorting for a btree node write, we drop the whiteout if it's not
  from the unwritten whiteouts area, or if it's overwritten by a real
  key at the same position.

This completely eliminates some tricky logic for propagating the
needs_whiteout flag: syzbot was able to hit the assertion that checked
that there shouldn't be more than one key at the same pos with
needs_whiteout set, likely due to a combination of flipping on
needs_whiteout on all written keys (they need whiteouts if overwritten),
combined with not always dropping unneeded whiteouts, and the tricky
logic in the sort path for preserving needs_whiteout that wasn't really
needed.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bch2_write_super() was looping over online devices multiple times -
dropping and retaking io_ref each time.

This meant it could race with device removal; it could increment the
sequence number on a device but fail to write it - and then if the
device was re-added, it would get confused the next time around thinking
a superblock write was silently dropped.

Fix this by taking io_ref once, and stashing pointers to online devices
in a darray.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Define a constant for the max superblock size, to avoid a too-large
shift.

Reported-by: syzbot+a8b0fb419355c91dda7f@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bch2_fs_quota_read_inode() wasn't entirely updated to the
bch2_snapshot_tree() helper, which takes rcu lock.

Reported-by: syzbot+a3a9a61224ed3b7f0010@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Ancient versions of bcachefs produced packed formats that could
represent keys that our in memory format cannot represent;
bformat_needs_redo() has some tricky shifts to check for this sort of
overflow.

Reported-by: syzbot+594427aebfefeebe91c6@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

For forwards compatibility we have to allow unknown key types, and only
run the checks that make sense against them.

Fix a missing guard on k.k->type being known.

Reported-by: syzbot+ae4dc916da3ce51f284f@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

We were forgetting to check for jset entries that overrun the end of the
section - both in validate and to_text(); to_text() needs to be safe for
types that fail to validate.

Reported-by: syzbot+c48865e11e7e893ec4ab@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Reported-by: syzbot+10827fa6b176e1acf1d0@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

filefrag (and potentially other utilities that call fiemap) sometimes
pass ULONG_MAX as the length.  fiemap_prep clamps excessively large
lengths - but the calculation of end can overflow if it occurs before
calling fiemap_prep.  When this happens, filefrag assumes it has read to
the end and exits.
Signed-off-by: Reed Riley <reed@riley.engineer>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

The bucket_gens array is a single array allocation (one byte per
bucket), and kernel allocations are still limited to INT_MAX.

Check this limit to avoid failing the bucket_gens array allocation.

Reported-by: syzbot+b29f436493184ea42e2b@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bch2_get_next_dev() and bch2_get_next_online_dev() iterate over devices,
dropping and taking refs as they go; we can't access the previous device
(for ca->dev_idx) after we've dropped our ref to it, unless we take
rcu_read_lock() first.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bch2_dev_lookup() is supposed to take a ref on the device it returns, but
for_each_member_device() takes refs as it iterates,
for_each_member_device_rcu() does not.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Normally this is initialized in __bch2_write(), which is executed in a
loop, but the inline data path skips this.

Reported-by: syzbot+fd3ccb331eb21f05d13b@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Reported-by: syzbot+66b9b74f6520068596a9@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Reported-by: syzbot+a35cdb62ec34d44fb062@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

We don't want the assert when we're checking if the backpointer is
valid.

Reported-by: syzbot+bf7215c0525098e7747a@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Reported-by: syzbot+3333603f569fc2ef258c@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

We're using mutex_lock() inside a wait_event() conditional -
prepare_to_wait() has already flipped task state, so potentially
blocking ops need annotation.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Pull scheduler fixes from Ingo Molnar:

 - Fix EEVDF corner cases

 - Fix two nohz_full= related bugs that can cause boot crashes
   and warnings

* tag 'sched-urgent-2024-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/isolation: Fix boot crash when maxcpus < first housekeeping CPU
  sched/isolation: Prevent boot crash when the boot CPU is nohz_full
  sched/eevdf: Prevent vlag from going out of bounds in reweight_eevdf()
  sched/eevdf: Fix miscalculation in reweight_entity() when se is not curr
  sched/eevdf: Always update V if se->on_rq when reweighting