bcachefs: Enumerate fsck errors

This patch adds a superblock error counter for every distinct fsck
error; this means that when analyzing filesystems out in the wild we'll
be able to see what sorts of inconsistencies are being found and repair,
and hence what bugs to look for.

Errors validating bkeys are not yet considered distinct fsck errors, but
this patch adds a new helper, bkey_fsck_err(), in order to add distinct
error types for them as well.

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

bcachefs: bch2_btree_bit_mod()

New helper for bitset btrees.

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

bcachefs: Change check for invalid key types

As part of the forward compatibility patch series, we need to allow for
new key types without complaining loudly when running an old version.

This patch changes the flags parameter of bkey_invalid to an enum, and
adds a new flag to indicate we're being called from the transaction
commit path.

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

bcachefs: bkey_ops.min_val_size

This adds a new field to bkey_ops for the minimum size of the value,
which standardizes that check and also enforces the new rule (previously
done somewhat ad-hoc) that we can extend value types by adding new
fields on to the end.

To make that work we do _not_ initialize min_val_size with sizeof,
instead we initialize it to the size of the first version of those
values.

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

bcachefs: Fragmentation LRU

Now that we have much more efficient updates to the LRU btree, this
patch adds a new LRU that indexes buckets by fragmentation.

This means copygc no longer has to scan every bucket to find buckets
that need to be evacuated.

Changes:
- A new field in bch_alloc_v4, fragmentation_lru - this corresponds to
the bucket's position in the fragmentation LRU. We add a new field
for this instead of calculating it as needed because we may make the
fragmentation LRU optional; this field indicates whether a bucket is
on the fragmentation LRU.

Also, zoned devices will introduce variable bucket sizes; explicitly
recording the LRU position will be safer for them.

- A new copygc path for using the fragmentation LRU instead of
scanning every bucket and building up an in-memory heap.

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

bcachefs: Improve invalidate_one_bucket() error messages

Make sure to check for lru entries that point to buckets that don't
exist as well as buckets in the wrong state, and improve the error
message we print out.

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

bcachefs: Change bkey_invalid() rw param to flags

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

bcachefs: Rework lru btree

This patch changes how the LRU index works:

Instead of using KEY_TYPE_lru where the bucket the lru entry points to
is part of the value, this switches to KEY_TYPE_set and encoding the
bucket we refer to in the low bits of the key.

This means that we no longer have to check for collisions when inserting
LRU entries. We'll be making using of this in the next patch, which adds
a btree write buffer - a pure write buffer for btree updates, where
updates are appended to a simple array and then periodically sorted and
batch inserted.

This is a new on disk format version, and a forced upgrade.

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

bcachefs: More style fixes

Fixes for various checkpatch errors.

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

bcachefs: LRU repair tweaks

- Drop old unneeded parameter for whether we're in initial GC - which
was from when btree updates had to be done differently before we
went RW.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Improve bch2_lru_delete() error messages

When we detect a filesystem inconsistency, we should include the
relevent keys in the error message. This patch adds a parameter to pass
the key with the lru entry to bch2_lru_delete(), so that it can be
printed.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Ensure buckets have io_time[READ] set

It's an error if a bucket is in state BCH_DATA_cached but not on the LRU
btree - i.e io_time[READ] == 0 - so, make sure it's set before adding
it.

Also, make some of the LRU code a bit clearer and more direct.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Add rw to .key_invalid()

This adds a new parameter to .key_invalid() methods for whether the key
is being read or written; the idea being that methods can do more
aggressive checks when a key is newly created and being written, when we
wouldn't want to delete the key because of those checks.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Convert .key_invalid methods to printbufs

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Fsck for need_discard & freespace btrees

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

bcachefs: LRU btree

This implements new persistent LRUs, to be used for buckets containing
cached data, as well as stripes ordered by time when a block became
empty.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>