Split out a new file for bch_sb_field_members - we'll likely want to
move more code here in the future.

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

This is prep work for consolidating with JOURNAL_WATERMARK.

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

This implements a new shutdown path for erasure coding, which is needed
for the upcoming BCH_WRITE_WAIT_FOR_EC write path.

The process is:
 - Cancel new stripes being built up
 - Close out/cancel open buckets on write points or the partial list
   that are for stripes
 - Shutdown rebalance/copygc
 - Then wait for in flight new stripes to finish

With BCH_WRITE_WAIT_FOR_EC, move ops will be waiting on stripes to fill
up before they complete; the new ec shutdown path is needed for shutting
down copygc/rebalance without deadlocking.

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

Now, any open_bucket can go on the partial list: allocating from the
partial list has been moved to its own dedicated function,
open_bucket_add_bucets() -> bucket_alloc_set_partial().

In particular, this means that erasure coded buckets can safely go on
the partial list; the new location works with the "allocate an ec bucket
first, then the rest" logic.

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

Factor out a common helper

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

This code predates plumbing btree_trans through the bucket allocation
path: switching to it fixes a deadlock due to using multiple btree_trans
at the same time, which we never want to do.

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

Provide inline versions of some allocation functions
 - bch2_alloc_sectors_done_inlined()
 - bch2_alloc_sectors_append_ptrs_inlined()

and use them in the core IO path.

Also, inline bch2_extent_update_i_size_sectors() and
bch2_bkey_append_ptr().

In the core write path, function call overhead matters - every function
call is a jump to a new location and a potential cache miss.

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

Only used in one place, just inline it there.

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

Now that we have new persistent data structures for the allocator, this
patch converts the allocator to use them.

Now, foreground bucket allocation uses the freespace btree to find
buckets to allocate, instead of popping buckets off the freelist.

The background allocator threads are no longer needed and are deleted,
as well as the allocator freelists. Now we only need background tasks
for invalidating buckets containing cached data (when we are low on
empty buckets), and for issuing discards.

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

This adds two new btrees for the upcoming allocator rewrite: an extents
btree of free buckets, and a btree for buckets awaiting discards.

We also add a new trigger for alloc keys to keep the new btrees up to
date, and a compatibility path to initialize them on existing
filesystems.

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