bkey_fsck_err() was added as an interface that looks like fsck_err(),
but previously all it did was ensure that the appropriate error counter
was incremented in the superblock.

This is a cleanup and bugfix patch that converts it to a wrapper around
fsck_err(). This is needed to fix an issue with the upgrade path to
disk_accounting_v3, where the "silent fix" error list now includes
bkey_fsck errors; fsck_err() handles this in a unified way, and since we
need to change printing of bkey fsck errors from the caller to the inner
bkey_fsck_err() calls, this ends up being a pretty big change.

Als,, rename .invalid() methods to .validate(), for clarity, while we're
changing the function signature anyways (to drop the printbuf argument).

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

for_each_btree_node() now works similarly to for_each_btree_key(), where
the loop body is passed as an argument to be passed to lockrestart_do().

This now calls trans_begin() on every loop iteration - which fixes an
SRCU warning in backpointers fsck.

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

fsck_err() now optionally takes a btree_trans; if the current thread has
one, it is required that it be passed.

The next patch will use this to unlock when waiting for user input.

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

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

this fixes a 'transaction should be locked' error in backpointers fsck

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

Add a new helper for checking references to write buffer btrees, where
we need a flush before we definitively know we have an inconsistency.

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

Can't actually be used uninitialized, but gcc was being silly.

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

We're about to start using bch_validate_flags for superblock section
validation - it's no longer bkey specific.

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>