The discard path is supposed to issue journal flushes when there's too
many buckets empty buckets that need a journal commit before they can be
written to again, but at some point this code seems to have been lost.

Bring it back with a new optimization to make sure we don't issue too
many journal flushes: the journal now tracks the sequence number of the
most recent flush in progress, which the discard path uses when deciding
which buckets need a journal flush.

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

We can't hold mark_lock while calling fsck_err() - that's a deadlock,
mark_lock is meant to be a leaf node lock.

It's also unnecessary for gc_bucket() and bucket_gen(); rcu suffices
since the bucket_gens array describes its size, and we can't race with
device removal or resize during gc/fsck since that takes state lock.

Reported-by: syzbot+38641fcbda1aaffefdd4@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Check open buckets and buckets waiting for journal commit before doing
other expensive lookups.

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

This lets us use darray macros on dev_alloc_list (and it will become a
darray eventually, when we increase the maximum number of devices).

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

The function bch2_bucket_alloc_trans() lacked a description for the
nowait parameter in its documentation comment block. This patch adds the
missing description to ensure all parameters are properly documented.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=12179
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

When calling check_discard_freeespace_key from the allocator, we can't
repair without recursing - run it asynchronously instead.

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

The early-early allocation path, bch2_bucket_alloc_new_fs(), is no
longer needed - and inconsistencies around new_fs_bucket_idx have been a
frequent source of bugs.

Reported-by: syzbot+592425844580a6598410@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

try_alloc_bucket() has a "safety" check, which avoids allocating a
bucket if there's any backpointers present.

But backpointers are not the source of truth for live data in a bucket,
the bucket sector counts are; this check was fairly useless, and we're
also deferring backpointers checks from fsck to runtime in the near
future.

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

check_discard_freespace_key() was doing all the same checks as
try_alloc_bucket(), but with repair.

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

Prep work for converting try_alloc_bucket() to use
bch2_check_discard_freespace_key().

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