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

clang had a few more warnings about enum conversion, and also didn't
like the opts.c initializer.

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

This unifies JOURNAL_WATERMARK with BCH_WATERMARK; we're working towards
specifying watermarks once in the transaction commit path.

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

Add another watermark for journal reclaim - this is needed for the next
patches, that unify BCH_WATERMARK with JOURNAL_WATERMARK.

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>

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>

Rework stripe creation path - new algorithm for deciding when to create
new stripes or reuse existing stripes.

We add a new allocation watermark, RESERVE_stripe, above RESERVE_none.
Then we always try to create a new stripe by doing RESERVE_stripe
allocations; if this fails, we reuse an existing stripe and allocate
buckets for it with the reserve watermark for the given write
(RESERVE_none or RESERVE_movinggc).

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

Now we also print the number of buckets reserved for each watermark.

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

This adds support for nocow mode, where we do writes in-place when
possible. Patch components:

 - New boolean filesystem and inode option, nocow: note that when nocow
   is enabled, data checksumming and compression are implicitly disabled

 - To prevent in-place writes from racing with data moves
   (data_update.c) or bucket reuse (i.e. a bucket being reused and
   re-allocated while a nocow write is in flight, we have a new locking
   mechanism.

   Buckets can be locked for either data update or data move, using a
   fixed size hash table of two_state_shared locks. We don't have any
   chaining, meaning updates and moves to different buckets that hash to
   the same lock will wait unnecessarily - we'll want to watch for this
   becoming an issue.

 - The allocator path also needs to check for in-place writes in flight
   to a given bucket before giving it out: thus we add another counter
   to bucket_alloc_state so we can track this.

 - Fsync now may need to issue cache flushes to block devices instead of
   flushing the journal. We add a device bitmask to bch_inode_info,
   ei_devs_need_flush, which tracks devices that need to have flushes
   issued - note that this will lead to unnecessary flushes when other
   codepaths have already issued flushes, we may want to replace this with
   a sequence number.

 - New nocow write path: look up extents, and if they're writable write
   to them - otherwise fall back to the normal COW write path.

XXX: switch to sequence numbers instead of bitmask for devs needing
journal flush

XXX: ei_quota_lock being a mutex means bch2_nocow_write_done() needs to
run in process context - see if we can improve this

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

This refactoring puts our various allocation path counters into a
dedicated struct - the upcoming nocow patch is going to add another
counter.

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