Add a function for walking backpointers to find a path from a given
inode number, and convert various error messages to use it.

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

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

Add a new parameter to bkey validate functions, and use it to improve
invalid bkey error messages: we can now print the btree and depth it
came from, or if it came from the journal, or is a btree root.

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

Factor out a common helper, need_discard_or_freespace_err(), which is
now used by both fsck and the runtime checks, and can repair.

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

If we find an error that indicates that we need to run fsck, we can
specify that directly with run_explicit_recovery_pass().

These are now log_fsck_err() calls: we're just logging in the superblock
that an error occurred - and possibly doing an emergency shutdown,
depending on policy.

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

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

Newly generated keys, in the transaction commit path or write path,
should not be AUTOFIX; those indicate bugs that we need to fail fast
for.

Fixes: 5612daafb764 ("bcachefs: Fix fsck warnings from bkey validation")
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

__bch2_fsck_err() warns if the current task has a btree_trans object and
it wasn't passed in, because if it has to prompt for user input it has
to be able to unlock it.

But plumbing the btree_trans through bkey_validate(), as well as
transaction restarts, is problematic - so instead make bkey fsck errors
FSCK_AUTOFIX, which doesn't need to warn.

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

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>

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>