bcachefs: Check for journal entries overruning end of sb clean section

Fix a missing bounds check in superblock validation.

Note that we don't yet have repair code for this case - repair code for
individual items is generally low priority, since the whole superblock
is checksummed, validated prior to write, and we have backups.

Reported-by: lei lu <llfamsec@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bcachefs: jset_entry_datetime

This gives us a way to record the date and time every journal entry was
written - useful for debugging.

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

bcachefs: bch_fs_usage_base

Split out base filesystem usage into its own type; prep work for
breaking up bch2_trans_fs_usage_apply().

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

bcachefs: for_each_member_device() now declares loop iter

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

bcachefs: Kill dev_usage->buckets_ec

This counter is redundant; it's simply the sum of BCH_DATA_stripe and
BCH_DATA_parity buckets.

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

bcachefs: Rename bch_replicas_entry -> bch_replicas_entry_v1

Prep work for introducing bch_replicas_entry_v2

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

bcachefs: bch_sb_field_downgrade

Add a new superblock section that contains a list of
{ minor version, recovery passes, errors_to_fix }

that is - a list of recovery passes that must be run when downgrading
past a given version, and a list of errors to silently fix.

The upcoming disk accounting rewrite is not going to be fully
compatible: we're going to have to regenerate accounting both when
upgrading to the new version, and also from downgrading from the new
version, since the new method of doing disk space accounting is a
completely different architecture based on deltas, and synchronizing
them for every jounal entry write to maintain compatibility is going to
be too expensive and impractical.

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

bcachefs: Don't iterate over journal entries just for btree roots

Small performance optimization, and a bit of a code cleanup too.

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

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_sb_field_get() refactoring

Instead of using token pasting to generate methods for each superblock
section, just make the type a parameter to bch2_sb_field_get().

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

bcachefs: sb-clean.c

Pull code for bch_sb_field_clean out into its own file.

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