bcachefs: If we run merges at a lower watermark, they must be nonblocking

Fix another deadlock related to the merge path; previously, we switched
to always running merges at a lower watermark (because they are
noncritical); but when we run at a lower watermark we also need to run
nonblocking or we've introduced a new deadlock.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Reported-and-tested-by: s@m-h.ug

bcachefs: bch_member.btree_allocated_bitmap

This adds a small (64 bit) per-device bitmap that tracks ranges that
have btree nodes, for accelerating btree node scan if it is ever needed.

- New helpers, bch2_dev_btree_bitmap_marked() and
bch2_dev_bitmap_mark(), for checking and updating the bitmap

- Interior btree update path updates the bitmaps when required

- The check_allocations pass has a new fsck_err check,
btree_bitmap_not_marked

- New on disk format version, mi_btree_mitmap, which indicates the new
bitmap is present

- Upgrade table lists the required recovery pass and expected fsck error

- Btree node scan uses the bitmap to skip ranges if we're on the new
version

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

bcachefs: Disable merges from interior update path

There's been a bug in the btree write buffer where it wasn't triggering
btree node merges - and leaving behind a bunch of nearly empty btree
nodes.

Then during journal replay, when updates to the backpointers btree
aren't using the btree write buffer (because we require synchronization
with journal replay), we end up doing those merges all at once.

Then if it's the interior update path running them, we deadlock because
those run with the highest watermark.

There's no real need for the interior update path to be doing btree node
merges; other code paths can handle that at lower watermarks.

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

bcachefs: Run merges at BCH_WATERMARK_btree

This fixes a deadlock where the interior update path during journal
replay ends up doing a ton of merges on the backpointers btree, and
deadlocking.

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

bcachefs: Don't use bch2_btree_node_lock_write_nofail() in btree split path

It turns out - btree splits happen with the rest of the transaction
still locked, to avoid unnecessary restarts, which means using nofail
doesn't work here - we can deadlock.

Fortunately, we now have the ability to return errors here.

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

bcachefs: Fix a race in btree_update_nodes_written()

One btree update might have terminated in a node update, and then while
it is in flight another btree update might free that original node.

This race has to be handled in btree_update_nodes_written() - we were
missing a READ_ONCE().

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

bcachefs: JOURNAL_SPACE_LOW

"bcachefs; Fix deadlock in bch2_btree_update_start()" was a significant
performance regression (nearly 50%) on multithreaded random writes with
fio.

The reason is that the journal watermark checks multiple things,
including the state of the btree write buffer, and on multithreaded
update heavy workloads we're bottleneked on write buffer flushing - we
don't want kicknig off btree updates to depend on the state of the write
buffer.

This isn't strictly correct; the interior btree update path does do
write buffer updates, but it's a tiny fraction of total accounting
updates and we're more concerned with space in the journal itself.

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

bcachefs: Further improve btree_update_to_text()

Print start and end level of the btree update; also a bit of cleanup.

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

bcachefs: bch2_btree_root_alloc() -> bch2_btree_root_alloc_fake()

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

bcachefs: Improve bch2_btree_update_to_text()

Print out the mode as a string, and also print out the btree and
watermark.

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

bcachefs: BCH_WATERMARK_interior_updates

This adds a new watermark, higher priority than BCH_WATERMARK_reclaim,
for interior btree updates. We've seen a deadlock where journal replay
triggers a ton of btree node merges, and these use up all available open
buckets and then interior updates get stuck.

One cause of this is that we're currently lacking btree node merging on
write buffer btrees - that needs to be fixed as well.

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

bcachefs: Fix btree node reserve

Sign error when checking the watermark - oops.

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

bcachefs: Split out recovery_passes.c

We've grown a fair amount of code for managing recovery passes; tracking
which ones we're running, which ones need to be run, and flagging in the
superblock which ones need to be run on the next recovery.

So it's worth splitting out into its own file, this code is pretty
different from the code in recovery.c.

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

bcachefs: Fix bch2_btree_increase_depth()

When we haven't yet allocated any btree nodes for a given btree, we
first need to call the regular split path to allocate one.

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

bcachefs: Fix btree node keys accounting in topology repair path

When dropping keys now outside a now because we're changing the node
min/max, we need to redo the node's accounting as well.

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

bcachefs: Improved topology repair checks

Consolidate bch2_gc_check_topology() and btree_node_interior_verify(),
and replace them with an improved version,
bch2_btree_node_check_topology().

This checks that children of an interior node correctly span the full
range of the parent node with no overlaps.

Also, ensure that topology repairs at runtime are always a fatal error;
in particular, this adds a check in btree_iter_down() - if we don't find
a key while walking down the btree that's indicative of a topology error
and should be flagged as such, not a null ptr deref.

Some checks in btree_update_interior.c remaining BUG_ONS(), because we
already checked the node for topology errors when starting the update,
and the assertions indicate that we _just_ corrupted the btree node -
i.e. the problem can't be that existing on disk corruption, they
indicate an actual algorithmic bug.

In the future, we'll be annotating the fsck errors list with which
recovery pass corrects them; the open coded "run explicit recovery pass
or fatal error" in bch2_btree_node_check_topology() will in the future
be done for every fsck_err() call.

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

bcachefs: Be careful about btree node splits during journal replay

Don't pick a pivot that's going to be deleted.

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

bcachefs; Fix deadlock in bch2_btree_update_start()

BCH_TRANS_COMMIT_journal_reclaim with watermark != BCH_WATERMARK_reclaim
means nonblocking, and we need the journal_res_get() in
btree_update_start() to respect that.

In a future refactoring we'll be deleting
BCH_TRANS_COMMIT_journal_reclaim and replacing it with an explicit
BCH_TRANS_COMMIT_nonblocking.

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

bcachefs: ratelimit errors from async_btree_node_rewrite

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

bcachefs: Improve bch2_fatal_error()

error messages should always include __func__

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

bcachefs: Improve sysfs internal/btree_updates

Print out the function that launched the btree update.

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

bcachefs: Split out btree_node_rewrite_worker

This fixes a deadlock due to using btree_interior_update_worker for non
interior updates - async btree node rewrites were blocking, and then
blocking other interior updates.

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

bcachefs: Kill unused flags argument to btree_split()

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

bcachefs: Kill more -EIO error codes

This converts -EIOs related to btree node errors to private error codes,
which will help with some ongoing debugging by giving us better error
messages.

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

bcachefs: bump max_active on btree_interior_update_worker

WQ_UNBOUND with max_active 1 means ordered workqueue, but we don't
actually need or want ordered semantics - and probably want a higher
concurrency limit anyways.

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

bcachefs: Fix journal replay with unreadable btree roots

When a btree root is unreadable, we still might be able to get some data
back by replaying what's in the journal. Previously though, we got
confused when journal replay would attempt to replay a key for a level
that didn't exist.

This adds bch2_btree_increase_depth(), so that journal replay can handle
this.

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

bcachefs: Clamp replicas_required to replicas

This prevents going emergency read only when the user has specified
replicas_required > replicas.

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

bcachefs: Prep work for variable size btree node buffers

bcachefs btree nodes are big - typically 256k - and btree roots are
pinned in memory. As we're now up to 18 btrees, we now have significant
memory overhead in mostly empty btree roots.

And in the future we're going to start enforcing that certain btree node
boundaries exist, to solve lock contention issues - analagous to XFS's
AGIs.

Thus, we need to start allocating smaller btree node buffers when we
can. This patch changes code that refers to the filesystem constant
c->opts.btree_node_size to refer to the btree node buffer size -
btree_buf_bytes() - where appropriate.

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

bcachefs: Combine .trans_trigger, .atomic_trigger

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

bcachefs: trans_mark now takes bkey_s

Prep work for disk space accounting rewrite: we're going to want to use
a single callback for both of our current triggers, so we need to change
them to have the same type signature first.

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

bcachefs: Fix interior update path btree_path uses

Since the btree_paths array is now about to become growable, we have to
be careful not to refer to paths by pointer across contexts where they
may be reallocated.

This fixes the remaining btree_interior_update() paths - split and
merge.

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

bcachefs: get_unlocked_mut_path() -> btree_path_idx_t

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

bcachefs: trans_for_each_path_with_node() no longer uses path->idx

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

bcachefs: trans_for_each_path() no longer uses path->idx

path->idx is now a code smell: we should be using path_idx_t, since it's
stable across btree path reallocation.

This is also a bit faster, using the same loop counter vs. fetching
path->idx from each path we iterate over.

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

bcachefs: btree_iter -> btree_path_idx_t

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

bcachefs: bch2_btree_path_traverse() -> btree_path_idx_t

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

bcachefs: bch2_btree_path_make_mut() -> btree_path_idx_t

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

bcachefs; bch2_path_put() -> btree_path_idx_t

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

bcachefs: bch2_path_get() -> btree_path_idx_t

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

bcachefs: for_each_keylist_key() declares loop iter

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

bcachefs: Make sure allocation failure errors are logged

The previous patch fixed a bug in allocation path error handling, and it
would've been noticed sooner had it been logged properly.

Generally speaking, errors that shouldn't happen in normal operation and
are being returned up the stack should be logged: the write path was
already logging IO errors, but non IO errors were missed.

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

bcachefs: bch_err_(fn|msg) check if should print

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

bcachefs: bch2_trans_node_add no longer uses trans_for_each_path()

In the future we'll be making trans->paths resizable and potentially
having _many_ more paths (for fsck); we need to start fixing algorithms
that walk each path in a transaction where possible.

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

bcachefs: Improve trans->extra_journal_entries

Instead of using a darray, we now allocate journal entries for the
transaction commit path with our normal bump allocator - with an inlined
fastpath, and using btree_transaction_stats to remember how much to
initially allocate so as to avoid transaction restarts.

This is prep work for converting write buffer updates to use this
mechanism.

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

bcachefs: Include btree_trans in more tracepoints

This gives us more context information - e.g. which codepath is invoking
btree node reads.

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

bcachefs: convert bch_fs_flags to x-macro

Now we can print out filesystem flags in sysfs, useful for debugging
various "what's my filesystem doing" issues.

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

bcachefs: Rename BTREE_INSERT flags

BTREE_INSERT flags are actually transaction commit flags - rename them
for clarity.

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

bcachefs: Kill dead BTREE_INSERT flags

BTREE_INSERT_NOWAIT and BTREE_INSERT_GC_LOCK_HELD are no longer used,
and can be deleted.

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

bcachefs: Journal pins must always have a flush_fn

flush_fn is how we identify journal pins in debugfs - this is a
debugging aid.

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

bcachefs; guard against overflow in btree node split

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

bcachefs: btree_node_u64s_with_format() takes nr keys

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

bcachefs: Fix a journal deadlock in replay

Recently, journal pre-reservations were removed. They were for reserving
space ahead of time in the journal for operations that are required for
journal reclaim, e.g. btree key cache flushing and interior node btree
updates.

Instead we have watermarks - only operations for journal reclaim are
allowed when the journal is low on space, and in general we're quite
good about doing operations in the order that will free up space in the
journal quickest when we're low on space. If we're doing a journal
reclaim operation out of order, we usually do it in nonblocking mode if
it's not freeing up space at the end of the journal.

There's an exceptino though - interior btree node update operations have
to be BCH_WATERMARK_reclaim - once they've been started, and they can't
be nonblocking. Generally this is fine because they'll only be a very
small fraction of transaction commits - but there's an exception, which
is during journal replay.

Journal replay does many btree operations, but doesn't need to commit
them to the journal since they're already in the journal. So killing off
of pre-reservation, plus another change to make journal replay more
efficient by initially doing the replay in sorted btree order, made it
possible for the interior update operations replay generates to fill and
deadlock the journal.

Fix this by introducing a new check on journal space at the _start_ of
an interior update operation. This causes us to block if necessary in
exactly the same way as we used to when interior updates took a journal
pre-reservaiton, but without all the expensive accounting
pre-reservations required.

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

bcachefs: Fix race between btree writes and metadata drop

btree writes update the btree node key after every write, in order to
update sectors_written, and they also might need to drop pointers if one
of the writes failed in a replicated btree node.

But the btree node might also have had a pointer dropped while the write
was in flight, by bch2_dev_metadata_drop(), and thus there was a bug
where the btree node write would ovewrite the btree node's key with what
it had at the start of the write.

Fix this by dropping pointers not currently in the btree node key.

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

bcachefs: Fix split_race livelock

bch2_btree_update_start() calculates which nodes are going to have to be
split/rewritten, so that we know how many nodes to reserve and how deep
in the tree we have to take locks.

But btree node merges require inserting two keys into the parent node,
not just splits.

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

closures: CLOSURE_CALLBACK() to fix type punning

Control flow integrity is now checking that type signatures match on
indirect function calls. That breaks closures, which embed a work_struct
in a closure in such a way that a closure_fn may also be used as a
workqueue fn by the underlying closure code.

So we have to change closure fns to take a work_struct as their
argument - but that results in a loss of clarity, as closure fns have
different semantics from normal workqueue functions (they run owning a
ref on the closure, which must be released with continue_at() or
closure_return()).

Thus, this patc introduces CLOSURE_CALLBACK() and closure_type() macros
as suggested by Kees, to smooth things over a bit.

Suggested-by: Kees Cook <keescook@chromium.org>
Cc: Coly Li <colyli@suse.de>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bcachefs: Kill journal pre-reservations

This deletes the complicated and somewhat expensive journal
pre-reservation machinery in favor of just using journal watermarks:
when the journal is more than half full, we run journal reclaim more
aggressively, and when the journal is more than 3/4s full we only allow
journal reclaim to get new journal reservations.

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

bcachefs: Don't iterate over journal entries just for btree roots

Small performance optimization, and a bit of a code cleanup too.

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

bcachefs: Fix build errors with gcc 10

gcc 10 seems to complain about array bounds in situations where gcc 11
does not - curious.

This unfortunately requires adding some casts for now; we may
investigate getting rid of our __u64 _data[] VLA in a future patch so
that our start[0] members can be VLAs.

Reported-by: John Stoffel <john@stoffel.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bcachefs: Don't downgrade locks on transaction restart

We should only be downgrading locks on success - otherwise, our
transaction restarts won't be getting the correct locks and we'll
livelock.

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

bcachefs: Enumerate fsck errors

This patch adds a superblock error counter for every distinct fsck
error; this means that when analyzing filesystems out in the wild we'll
be able to see what sorts of inconsistencies are being found and repair,
and hence what bugs to look for.

Errors validating bkeys are not yet considered distinct fsck errors, but
this patch adds a new helper, bkey_fsck_err(), in order to add distinct
error types for them as well.

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

bcachefs: Heap allocate btree_trans

We're using more stack than we'd like in a number of functions, and
btree_trans is the biggest object that we stack allocate.

But we have to do a heap allocatation to initialize it anyways, so
there's no real downside to heap allocating the entire thing.

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

bcachefs: Fix W=12 build errors

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

bcachefs: remove redundant initialization of pointer d

The pointer d is being initialized with a value that is never read,
it is being re-assigned later on when it is used in a for-loop.
The initialization is redundant and can be removed.

Cleans up clang-scan build warning:
fs/bcachefs/buckets.c:1303:25: warning: Value stored to 'd' during its
initialization is never read [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bcachefs: Convert more code to bch_err_msg()

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

bcachefs: Fix silent enum conversion error

This changes mark_btree_node_locked() to take an enum
btree_node_locked_type, not a six_lock_type, since BTREE_NODE_UNLOCKED
is -1 which may cause problems converting back and forth to
six_lock_type if short enums are in use.

With this change, we never store BTREE_NODE_UNLOCKED in a six_lock_type
enum.

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

bcachefs: Don't open code closure_nr_remaining()

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

bcachefs: btree_journal_iter.c

Split out a new file from recovery.c for managing the list of keys we
read from the journal: before journal replay finishes the btree iterator
code needs to be able to iterate over and return keys from the journal
as well, so there's a fair bit of code here.

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

bcachefs: Assorted fixes for clang

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>

bcachefs: Fix a write buffer flush deadlock

We're not supposed to block if BTREE_INSERT_JOURNAL_RECLAIM && watermark
!= BCH_WATERMARK_reclaim.

This should really be a separate BTREE_INSERT_NONBLOCK flag - add some
comments to that effect, it's not important for this patch.

btree write buffer flush depends on this behaviour though - the first
loop tries to flush sequentially, which doesn't free up space in the
journal optimally. If that can't proceed we bail out and flush in
journal order - that won't work if we're blocked instead of returning an
error.

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

bcachefs: Assorted sparse fixes

- endianness fixes
- mark some things static
- fix a few __percpu annotations
- fix silent enum conversions

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

bcachefs: Allow for unknown btree IDs

We need to allow filesystems with metadata from newer versions to be
mountable and usable by older versions.

This patch enables us to roll out new btrees without a new major version
number; we can now handle btree roots for unknown btree types.

The unknown btree roots will be retained, and fsck (including
backpointers) will check them, the same as other btree types.

We add a dynamic array for the extra, unknown btree roots, in addition
to the fixed size btree root array, and add new helpers for looking up
btree roots.

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

bcachefs: Kill BTREE_INSERT_USE_RESERVE

Now that we have journal watermarks and alloc watermarks unified,
BTREE_INSERT_USE_RESERVE is redundant and can be deleted.

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

bcachefs: Fix a null ptr deref in bch2_fs_alloc() error path

This fixes a null ptr deref in bch2_free_pending_node_rewrites() when
the list head wasn't initialized.

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

bcachefs: Kill JOURNAL_WATERMARK

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>

bcachefs: Rename enum alloc_reserve -> bch_watermark

This is prep work for consolidating with JOURNAL_WATERMARK.

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

bcachefs: Fix bch2_btree_update_start()

The calculation for number of nodes to allocate in
bch2_btree_update_start() was incorrect - this fixes a BUG_ON() on the
small nodes test.

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

bcachefs: Delete weird hacky transaction restart injection

since we currently don't have a good fault injection library,
bch2_btree_insert_node() was randomly injecting faults based on
local_clock().

At the very least this should have been a debug mode only thing, but
this is a brittle method so let's just delete it.

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

bcachefs: More drop_locks_do() conversions

Using drop_locks_do() ensures that every unlock() is paired with a
relock(), with proper error checking.

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

bcachefs: drop_locks_do()

Add a new helper for the common pattern of:
- trans_unlock()
- do something
- trans_relock()

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

bcachefs: GFP_NOIO -> GFP_NOFS

GFP_NOIO dates from the bcache days, when we operated under the block
layer. Now, GFP_NOFS is more appropriate, so switch all GFP_NOIO uses to
GFP_NOFS.

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

six locks: Kill six_lock_state union

As suggested by Linus, this drops the six_lock_state union in favor of
raw bitmasks.

On the one hand, bitfields give more type-level structure to the code.
However, a significant amount of the code was working with
six_lock_state as a u64/atomic64_t, and the conversions from the
bitfields to the u64 were deemed a bit too out-there.

More significantly, because bitfield order is poorly defined (#ifdef
__LITTLE_ENDIAN_BITFIELD can be used, but is gross), incrementing the
sequence number would overflow into the rest of the bitfield if the
compiler didn't put the sequence number at the high end of the word.

The new code is a bit saner when we're on an architecture without real
atomic64_t support - all accesses to lock->state now go through
atomic64_*() operations.

On architectures with real atomic64_t support, we additionally use
atomic bit ops for setting/clearing individual bits.

Text size: 7467 bytes -> 4649 bytes - compilers still suck at
bitfields.

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

bcachefs: Improve trans_restart_split_race tracepoint

Seeing occasional test failures where we get stuck in a livelock that
involves this event - this will help track it down.

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

bcachefs: Fix bch2_extent_fallocate() in nocow mode

When we allocate disk space, we need to be incrementing the WRITE io
clock, which perhaps should be renamed to sectors allocated - copygc
uses this io clock to know when to run.

Also, we should be incrementing the same clock when allocating btree
nodes.

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

bcachefs: Private error codes: ENOMEM

This adds private error codes for most (but not all) of our ENOMEM uses,
which makes it easier to track down assorted allocation failures.

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

bcachefs: Drop some anonymous structs, unions

Rust bindgen doesn't cope well with anonymous structs and unions. This
patch drops the fancy anonymous structs & unions in bkey_i that let us
use the same helpers for bkey_i and bkey_packed; since bkey_packed is an
internal type that's never exposed to outside code, it's only a minor
inconvenienc.

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

bcachefs: BKEY_PADDED_ONSTACK()

Rust bindgen doesn't do anonymous structs very nicely: BKEY_PADDED()
only needs the anonymous struct when it's used on the stack, to
guarantee layout, not when it's embedded in another struct.

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

bcachefs: Plumb btree_trans through btree cache code

Soon, __bch2_btree_node_write() is going to require a btree_trans: zoned
device support is going to require a new allocation for every btree node
write. This is a bit of prep work.

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

bcachefs: Add tracepoint & counter for btree split race

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

bcachefs: bch2_journal_entries_postprocess()

This brings back journal_entries_compact(), but in a more efficient form
- we need to do multiple postprocess steps, so iterate over the
journal entries being written just once to make it more efficient.

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

bcachefs: Handle btree node rewrites before going RW

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

bcachefs: Add some logging for btree node rewrites due to errors

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

bcachefs: Debug mode for c->writes references

This adds a debug mode where we split up the c->writes refcount into
distinct refcounts for every codepath that takes a reference, and adds
sysfs code to print the value of each ref.

This will make it easier to debug shutdown hangs due to refcount leaks.

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

bcachefs: Fix btree_node_write_blocked() not being cleared

The btree_node_write_blocked bit was a later addition to this code,
it only mirrors the state of the b->write_blocked list (empty or
nonempty) - unfortunately, when it was added it wasn't correctly kept in
sync - oops.

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

bcachefs: Improve btree_reserve_get_fail tracepoint

Now we include the return code.

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

bcachefs: Convert EAGAIN errors to private error codes

More error code cleanup, for better error messages and debugability.

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

bcachefs: btree_iter->ip_allocated

In debug mode, we now track where btree iterators and paths are
initialized/allocated - helpful in tracking down btree path overflows.

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

bcachefs: New bpos_cmp(), bkey_cmp() replacements

This patch introduces
- bpos_eq()
- bpos_lt()
- bpos_le()
- bpos_gt()
- bpos_ge()

and equivalent replacements for bkey_cmp().

Looking at the generated assembly these could probably be improved
further, but we already see a significant code size improvement with
this patch.

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

bcachefs: Fix a race with b->write_type

b->write_type needs to be set atomically with setting the
btree_node_need_write flag, so move it into b->flags.

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

bcachefs: Btree split improvement

This improves the bkey_format calculation when splitting btree nodes.
Previously, we'd use a format calculated for the original node for the
lower of the two new nodes.

This was particularly bad on sequential insertions, where we iteratively
split the last btree node, whos format has to include KEY_MAX.

Now, we calculate formats precisely for the keys the two new nodes will
contain. This also should make splitting a bit more efficient, since
we're only copying keys once (from the original node to the new node,
instead of new node, replacement node, then upper split).

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

bcachefs: Improved btree write statistics

This replaces sysfs btree_avg_write_size with btree_write_stats, which
now breaks out statistics by the source of the btree write.

Btree writes that are too small are a source of inefficiency, and
excessive btree resort overhead - this will let us see what's causing
them.

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

bcachefs: Make error messages more uniform

Use __func__ in error messages that refer to function name, and do so
more uniformly - suggested by checkpatch.pl

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

bcachefs: Assorted checkpatch fixes

checkpatch.pl gives lots of warnings that we don't want - suggested
ignore list:

ASSIGN_IN_IF
UNSPECIFIED_INT - bcachefs coding style prefers single token type names
NEW_TYPEDEFS - typedefs are occasionally good
FUNCTION_ARGUMENTS - we prefer to look at functions in .c files
(hopefully with docbook documentation), not .h
file prototypes
MULTISTATEMENT_MACRO_USE_DO_WHILE
- we have _many_ x-macros and other macros where
we can't do this

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

bcachefs: Call bch2_btree_update_add_new_node() before dropping write lock

btree nodes can be written by other threads (shrinker, journal reclaim)
with only a read lock, but brand new nodes should only be written by the
thread doing the split/interior update. bch2_btree_update_add_new_node()
sets btree node flags to indicate that this is a new node and should not
be written out by other threads, thus we need to call it before dropping
our write lock.

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

bcachefs: Btree splits now only take the locks they need

Previously, bch2_btree_update_start() would always take all intent
locks, all the way up to the root.

We've finally got data from users where this became a scalability issue
- so, this patch fixes bch2_btree_update_start() to only take the locks
we need.

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

bcachefs: bch2_btree_insert_node() no longer uses lock_write_nofail

Now that we have an error path plumbed through, there's no need to be
using bch2_btree_node_lock_write_nofail().

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

bcachefs: Add error path to btree_split()

The next patch in the series is (finally!) going to change btree splits
(and interior updates in general) to not take intent locks all the way
up to the root - instead only locking the nodes they'll need to modify.

However, this will be introducing a race since if we're not holding a
write lock on a btree node it can be written out by another thread, and
then we might not have enough space for a new bset entry.

We can handle this by retrying - we just need to introduce a new error
path.

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

bcachefs: Write new btree nodes after parent update

In order to avoid locking all btree nodes up to the root for btree node
splits, we're going to have to introduce a new error path into
bch2_btree_insert_node(); this mean we can't have done any writes or
modified global state before that point.

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

bcachefs: Fix a deadlock in btree_update_nodes_written()

btree_node_lock_nopath() is something we'd like to get rid of, it's
always prone to deadlocks if we accidentally are holding other locks,
because it doesn't mark the lock it's taking in a path: we'll want to
get rid of it in the future, but for now this patch works it by calling
bch2_trans_unlock().

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

bcachefs; Mark __bch2_trans_iter_init as inline

This function is fairly small and only used in two places: one very hot,
the other cold, so it should definitely be inlined.

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

bcachefs: Fix blocking with locks held

This is a major oopsy - we should always be unlocking before calling
closure_sync(), else we'll cause a deadlock.

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

bcachefs: btree_update_nodes_written() needs BTREE_INSERT_USE_RESERVE

This fixes an obvious deadlock - whoops.

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

bcachefs: Fix error handling in bch2_btree_update_start()

We were checking for -EAGAIN, but we're not returned that when we didn't
pass a closure to wait with - oops.

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

bcachefs: All held locks must be in a btree path

With the new deadlock cycle detector, it's critical that all held locks
be marked in a btree_path, because that's what the cycle detector
traverses - any locks that aren't correctly marked will cause deadlocks.

This changes the btree_path to allocate some btree_paths for the new
nodes, since until the final update is done we otherwise don't have a
path referencing them.

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

bcachefs: bch2_btree_path_upgrade() now emits transaction restart

Centralizing the transaction restart/tracepoint in
bch2_btree_path_upgrade() lets us improve the tracepoint - now it emits
old and new locks_want.

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

bcachefs: Avoid using btree_node_lock_nopath()

With the upcoming cycle detector, we have to be careful about using
btree_node_lock_nopath - in particular, using it to take write locks can
cause deadlocks.

All held locks need to be tracked in a btree_path, so that the cycle
detector knows about them - unless we know that we cannot cause
deadlocks for other reasons: e.g. we are only taking read locks, or
we're in very early fsck (topology repair).

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

bcachefs: Convert more locking code to btree_bkey_cached_common

Ideally, all the code in btree_locking.c should be converted, but then
we'd want to convert btree_path to point to btree_key_cached_common too,
and then we'd be in for a much bigger cleanup - but a bit of incremental
cleanup will still be helpful for the next patches.

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

bcachefs: bch2_btree_node_lock_write_nofail()

Taking a write lock will be able to fail, with the new cycle detector -
unless we pass it nofail, which is possible but not preferred.

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

bcachefs: New locking functions

In the future, with the new deadlock cycle detector, we won't be using
bare six_lock_* anymore: lock wait entries will all be embedded in
btree_trans, and we will need a btree_trans context whenever locking a
btree node.

This patch plumbs a btree_trans to the few places that need it, and adds
two new locking functions
- btree_node_lock_nopath, which may fail returning a transaction
restart, and
- btree_node_lock_nopath_nofail, to be used in places where we know we
cannot deadlock (i.e. because we're holding no other locks).

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Add persistent counters for all tracepoints

Also, do some reorganizing/renaming, convert atomic counters in bch_fs
to persistent counters, and add a few missing counters.

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

bcachefs: Fix bch2_btree_update_start() to return -BCH_ERR_journal_reclaim_would_deadlock

On failure to get a journal pre-reservation because we're called from
journal reclaim we're not supposed to return a transaction restart error
- this fixes a livelock.

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

bcachefs: Improve trans_restart_journal_preres_get tracepoint

It now includes journal_flags.

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

bcachefs: Add assertions for unexpected transaction restarts

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Tracepoint improvements

Our types are exported to the tracepoint code, so it's not necessary to
break things out individually when passing them to tracepoints - we can
also call other functions from TP_fast_assign().

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: BTREE_ITER_NO_NODE -> BCH_ERR codes

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Don't set should_be_locked on paths that aren't locked

It doesn't make any sense to set should_be_locked on btree_paths that
aren't locked, and is often a bug - this patch adds assertions and fixes
some of those bugs.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: EINTR -> BCH_ERR_transaction_restart

Now that we have error codes, with subtypes, we can switch to our own
error code for transaction restarts - and even better, a distinct error
code for each transaction restart reason: clearer code and better
debugging.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: lock time stats prep work.

We need the caller name and a place to store our results, btree_trans provides this.

Signed-off-by: Daniel Hill <daniel@gluo.nz>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bcachefs: Rename __bch2_trans_do() -> commit_do()

Better/more descriptive naming, and prep for adding
nested_lockrestart_do() and nested_commit_do().

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Always use percpu_ref_tryget_live() on c->writes

If we're trying to get a ref and the refcount has been killed, it means
we're doing an emergency shutdown - we always want tryget_live().

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Printbuf rework

This converts bcachefs to the modern printbuf interface/implementation,
synced with the version to be submitted upstream.

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

bcachefs: Tracepoint improvements

Delete some obsolete tracepoints, organize alloc tracepoints better,
make a few tracepoints more consistent.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Lock ordering fix

Can't take btree node locks while holding btree_reserve_cache_lock - it
would be nice if we could check this with lockdep.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Shutdown path improvements

We're seeing occasional firings of the assertion in the key cache
shutdown code that nr_dirty == 0, which means we must sometimes be doing
transaction commits after we've gone read only.

Cleanups & changes:
- BCH_FS_ALLOC_CLEAN renamed to BCH_FS_CLEAN_SHUTDOWN
- new helper bch2_btree_interior_updates_flush(), which returns true if
it had to wait
- bch2_btree_flush_writes() now also returns true if there were btree
writes in flight
- __bch2_fs_read_only now checks if btree writes were in flight in the
shutdown loop: btree write completion does a transaction update, to
update the pointer in the parent node
- assert that !BCH_FS_CLEAN_SHUTDOWN in __bch2_trans_commit

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: btree_update_interior.c prep for backpointers

Previously, btree_update_interior.c passed keys to bch2_trans_mark_*
that hadn't been fully initialized - they didn't have the key field
filled out, just the value.

With backpointers, we need to make sure keys are fully initialized
before marking them - because the backpointer points back to the
original key.

This patch tweaks the interior update paths to fix this.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Plumb btree_id & level to trans_mark

For backpointers, we'll need the full key location - that means btree_id
and btree level. This patch plumbs it through.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Add rw to .key_invalid()

This adds a new parameter to .key_invalid() methods for whether the key
is being read or written; the idea being that methods can do more
aggressive checks when a key is newly created and being written, when we
wouldn't want to delete the key because of those checks.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Convert .key_invalid methods to printbufs

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Kill allocator threads & freelists

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>

bcachefs: Run btree updates after write out of write_point

In the write path, after the write to the block device(s) complete we
have to punt to process context to do the btree update.

Instead of using the work item embedded in op->cl, this patch switches
to a per write-point work item. This helps with two different issues:

- lock contention: btree updates to the same writepoint will (usually)
be updating the same alloc keys
- context switch overhead: when we're bottlenecked on btree updates,
having a thread (running out of a work item) checking the write point
for completed ops is cheaper than queueing up a new work item and
waking up a kworker.

In an arbitrary benchmark, 4k random writes with fio running inside a
VM, this patch resulted in a 10% improvement in total iops.

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

bcachefs: bch2_btree_update_start() refactoring

This simplifies the logic in bch2_btree_update_start() a bit, handling
the unlock/block logic more locally.

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

bcachefs: Introduce a separate journal watermark for copygc

Since journal reclaim -> btree key cache flushing may require the
allocation of new btree nodes, it has an implicit dependency on copygc
in order to make forward progress - so we should avoid blocking copygc
unless the journal is really close to full.

This introduces watermarks to replace our single MAY_GET_UNRESERVED bit
in the journal, and adds a watermark for copygc and plumbs it through.

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

bcachefs: x-macroize alloc_reserve enum

This makes an array of strings available, like our other enums.

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

bcachefs: Use darray for extra_journal_entries

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Add a missing btree_path_set_dirty() calls

bch2_btree_iter_next_node() was mucking with other btree_path state
without setting path->update to be consistent with the fact that the
path is very much no longer uptodate - oops.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Fix usage of six lock's percpu mode

Six locks have a percpu mode, which we use for interior btree nodes, as
well as btree key cache keys for the subvolumes btree. We've been
switching locks back and forth between percpu and non percpu mode as
needed, but it turns out this is racy - when we're reusing an existing
node, other threads could be attempting to lock it while we're switching
it between modes.

This patch fixes this by never switching 'struct btree' between the two
modes, and instead segragating them between two different freed lists.

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

bcachefs: Simplify parameters to bch2_btree_update_start()

We don't need to pass the number of nodes required to
bch2_btree_update_start, just whether we're doing a split at @level.
This is prep work for a fix to our usage of six lock's percpu mode,
which is going to require us to count up and allocate interior nodes and
leaf nodes seperately.

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

bcachefs: Drop unneeded journal pin in bch2_btree_update_start()

When we do an interior btree update, we create new btree nodes and link
them into the btree in memory, but they don't become reachable on disk
until later, when btree_update_nodes_written_trans() runs.

Updates to the new nodes can thus happen before they're reachable on
disk, and if the updates to those new nodes are written before the nodes
become reachable, we would then drop the journal pin for those updates
before the btree has them.

This is what the journal pin in bch2_btree_update_start() was protecting
against. However, it's not actually needed because we don't allow
subsequent append writes to btree nodes until the node is reachable on
disk.

Dropping this unneeded pin also fixes a bug introduced by "bcachefs:
Journal seq now incremented at entry open, not close" - in the new code,
if the journal is completely empty a journal pin list for
journal_cur_seq() won't exist.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Fix race leading to btree node write getting stuck

Checking btree_node_may_write() isn't atomic with the other btree flags,
dirty and need_write in particular. There was a rare race where we'd
unblock a node from writing while __btree_node_flush() was setting
need_write, and no thread would notice that the node was now both able
to write and needed to be written.

Fix this by adding btree node flags for will_make_reachable and
write_blocked that can be checked in the cmpxchg loop in
__bch2_btree_node_write.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Improve btree_node_write_if_need()

btree_node_write_if_need() kicks off a btree node write only if
need_write is set; this makes the locking easier to reason about by
moving the check into the cmpxchg loop in __bch2_btree_node_write().

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Use x-macros for btree node flags

This is for adding an array of strings for btree node flag names.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Kill BCH_FS_HOLD_BTREE_WRITES

This was just dead code.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Fix btree path sorting

In btree_update_interior.c, we were changing a path's level directly -
which affects path sort order - without re-sorting paths, leading to
assertions when bch2_path_get() verified paths were sorted correctly.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Heap allocate printbufs

This patch changes printbufs dynamically allocate and reallocate a
buffer as needed. Stack usage has become a bit of a problem, and a major
cause of that has been static size string buffers on the stack.

The most involved part of this refactoring is that printbufs must now be
exited with printbuf_exit().

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

bcachefs: bch2_trans_mark_key() now takes a bkey_i *

We're now coming up with triggers that modify the update being done. A
bkey_s_c is const - bkey_i is the correct type to be using here.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Set BTREE_NODE_SEQ() correctly in merge path

BTREE_NODE_SEQ() is supposed to give us a time ordering of btree nodes
on disk, so that we can tell which btree node is newer if we ever have
to scan the entire device to find btree nodes.

The btree node merge path wasn't setting it correctly on the new node -
oops.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Also show when blocked on write locks

This consolidates some of the btree node lock path, so that when we're
blocked taking a write lock on a node it shows up in
bch2_btree_trans_to_text(), along with intent and read locks.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Don't keep nodes in btree_reserve locked

These nodes aren't reachable by other threads, so there's no need to
keep it locked - and this fixes a bug with the assertion in
bch2_trans_unlock() firing on transaction restart.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Use BTREE_INSERT_USE_RESERVE in btree_update_key()

bch2_btree_update_key() is used in the btree node write path - before
delivering the completion we have to update the parent pointer with the
number of sectors written.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Switch to __func__for recording where btree_trans was initialized

Symbol decoding, via %ps, isn't supported in userspace - this will also
be faster when we're using trans->fn in the fast path, as with the new
BCH_JSET_ENTRY_log journal messages.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Simplify journal replay

With BTREE_ITER_WITH_JOURNAL, there's no longer any restrictions on the
order we have to replay keys from the journal in, and we can also start
up journal reclaim right away - and delete a bunch of code.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: BTREE_ITER_WITH_JOURNAL

This adds a new btree iterator flag, BTREE_ITER_WITH_JOURNAL, that is
automatically enabled when initializing a btree iterator before journal
replay has completed - it overlays the contents of the journal with the
btree.

This lets us delete bch2_btree_and_journal_walk() and just use the
normal btree iterator interface instead - which also lets us delete a
significant amount of duplicated code.

Note that BTREE_ITER_WITH_JOURNAL is still unoptimized in this patch -
we're redoing the binary search over keys in the journal every time we
call bch2_btree_iter_peek().

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

bcachefs: bch2_alloc_sectors_append_ptrs() now takes cached flag

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

bcachefs: Option improvements

This adds flags for options that must be a power of two (block size and
btree node size), and options that are stored in the superblock as a
power of two (encoded extent max).

Also: options are now stored in memory in the same units they're
displayed in (bytes): we now convert when getting and setting from the
superblock.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: BTREE_ITER_NOPRESERVE

This adds a flag to not mark the initial btree_path as preserve, for
paths that we expect to be cheap to reconstitute if necessary - this
solves a btree_path overflow caused by need_whiteout_for_snapshot().

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Add more time_stats

This adds more latency/event measurements and breaks some apart into
more events. Journal writes are broken apart into flush writes and
noflush writes, btree compactions are broken out from btree splits,
btree mergers are added, as well as btree_interior_updates - foreground
and total.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: bch2_btree_node_rewrite() now returns transaction restarts

We have been getting away from handling transaction restarts locally -
convert bch2_btree_node_rewrite() to the newer style.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: for_each_btree_node() now returns errors directly

This changes for_each_btree_node() to work like for_each_btree_key(),
and to that end bch2_btree_iter_peek_node() and next_node() also return
error ptrs.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: More btree iterator fixes

- check for getting to the end of the btree in bch2_path_verify_locks
and __btree_path_traverse_all(), this fixes an infinite loop in
__btree_path_traverse_all().
- relax requirement in bch2_btree_node_upgrade() that we must want an
intent lock, this fixes bugs with paths that point to interior nodes
(nonzero level).
- bch2_btree_node_update_key(): fix it to upgrade the path to an intent
lock, if necessary

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Fix an assertion

We can end up in a strange situation where a btree_path points to a node
being freed even after pointers to it should have been replaced by
pointers to the new node - if the btree node has been reused since the
pointer to it was created.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Kill retry loop in btree merge path

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Tighten up btree locking invariants

New rule is: if a btree path holds any locks it should be holding
precisely the locks wanted (accoringing to path->level and
path->locks_want).

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: btree_path

This splits btree_iter into two components: btree_iter is now the
externally visible componont, and it points to a btree_path which is now
reference counted.

This means we no longer have to clone iterators up front if they might
be mutated - btree_path can be shared by multiple iterators, and cloned
if an iterator would mutate a shared btree_path. This will help us use
iterators more efficiently, as well as slimming down the main long lived
state in btree_trans, and significantly cleans up the logic for iterator
lifetimes.

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

bcachefs: Add an assertion for removing btree nodes from cache

Chasing a bug that has something to do with the btree node cache.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: More renaming

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Clean up/rename bch2_trans_node_* fns

These utility functions are for managing btree node state within a
btree_trans - rename them for consistency, and drop some unneeded
arguments.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Further reduce iter->trans usage

This is prep work for splitting btree_path out from btree_iter -
btree_path will not have a pointer to btree_trans.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Reduce iter->trans usage

Disfavoured, and should go away.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Kill BTREE_INSERT_NOUNLOCK

With the recent transaction restart changes, it's no longer needed - all
transaction commits have BTREE_INSERT_NOUNLOCK semantics.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: trans->restarted

Start tracking when btree transactions have been restarted - and assert
that we're always calling bch2_trans_begin() immediately after
transaction restart.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Clean up interior update paths

Btree node merging now happens prior to transaction commit, not after,
so we don't need to pay attention to BTREE_INSERT_NOUNLOCK.

Also, foreground_maybe_merge shouldn't be calling
bch2_btree_iter_traverse_all() - this is becoming private to the btree
iterator code and should only be called by bch2_trans_begin().

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Update btree ptrs after every write

This closes a significant hole (and last known hole) in our ability to
verify metadata. Previously, since btree nodes are log structured, we
couldn't detect lost btree writes that weren't the first write to a
given node. Additionally, this seems to have lead to some significant
metadata corruption on multi device filesystems with metadata
replication: since a write may have made it to one device and not
another, if we read that btree node back from the replica that did have
that write and started appending after that point, the other replica
would have a gap in the bset entries and reading from that replica
wouldn't find the rest of the bsets.

But, since updates to interior btree nodes are now journalled, we can
close this hole by updating pointers to btree nodes after every write
with the currently written number of sectors, without negatively
affecting performance. This means we will always detect lost or corrupt
metadata - it also means that our btree is now a curious hybrid of COW
and non COW btrees, with all the benefits of both (excluding
complexity).

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Fix an allocator shutdown deadlock

On fstest generic/388, we were seeing sporadic deadlocks in the
emergency shutdown, where we'd get stuck shutting down the allocator
because bch2_btree_update_start() -> bch2_btree_reserve_get() allocated
and then deallocated some btree nodes, putting them back on the
btree_reserve_cache, after the allocator shutdown code had already
cleared out that cache.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Really don't hold btree locks while btree IOs are in flight

This is something we've attempted to stick to for quite some time, as it
helps guarantee filesystem latency - but there's a few remaining paths
that this patch fixes.

This is also necessary for an upcoming patch to update btree pointers
after every btree write - since the btree write completion path will now
be doing btree operations.

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

bcachefs: Regularize argument passing of btree_trans

btree_trans should always be passed when we have one - iter->trans is
disfavoured. This mainly updates old code in btree_update_interior.c,
some of which predates btree_trans.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Split out SPOS_MAX

Internal btree code really wants a POS_MAX with all fields ~0; external
code more likely wants the snapshot field to be 0, because when we're
passing it to bch2_trans_get_iter() it's used for the snapshot we're
operating in, which should be 0 for most btrees that don't use
snapshots.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Extensive triggers cleanups

- We no longer mark subsets of extents, they're marked like regular
keys now - which means we can drop the offset & sectors arguments
to trigger functions
- Drop other arguments that are no longer needed anymore in various
places - fs_usage
- Drop the logic for handling extents in bch2_mark_update() that isn't
needed anymore, to match bch2_trans_mark_update()
- Better logic for hanlding the BTREE_ITER_CACHED_NOFILL case, where we
don't have an old key to mark

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Improve iter->should_be_locked

Adding iter->should_be_locked introduced a regression where it ended up
not being set on the iterator passed to bch2_btree_update_start(), which
is definitely not what we want.

This patch requires it to be set when calling bch2_trans_update(), and
adds various fixups to make that happen.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Improve btree iterator tracepoints

This patch adds some new tracepoints to the btree iterator code, and
adds new fields to the existing tracepoints - primarily for the iterator
position.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Fix a deadlock

Waiting on a btree node write with btree locks held can deadlock, if the
write errors: the write error path has to do do a btree update to drop
the pointer to the replica that errored.

The interior update path has to wait on in flight btree writes before
freeing nodes on disk. Previously, this was done in
bch2_btree_interior_update_will_free_node(), and could deadlock; now, we
just stash a pointer to the node and do it in
btree_update_nodes_written(), just prior to the transactional part of
the update.

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

bcachefs: Add a workqueue for btree io completions

Also, clean up workqueue usage - we shouldn't be using system
workqueues, pretty much everything we do needs to be on our own
WQ_MEM_RECLAIM workqueues.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Don't repair btree nodes until after interior journal replay is done

We need the btree to be in a consistent state before we can rewrite
btree nodes.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: Fix an uninitialized var

this fixes a valgrind complaint

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

bcachefs: New and improved topology repair code

This splits out btree topology repair into a separate pass, and makes
some improvements:
- When we have to pick which of two overlapping nodes to drop keys
from, we use the btree node header sequence number to preserve the
newer node

- the gc code has been changed so that it doesn't bail out if we're
continuing/ignoring on fsck error - this way the dump tool can skip
running the repair pass but still walk all reachable metadata

- add a new superblock flag indicating when a filesystem is known to
have btree topology issues, and the topology repair pass should be
run

- changing the start/end of a node might mean keys in that node have to
be deleted: this patch handles that better by splitting it out into a
separate function and running it explicitly in the topology repair
code, previously those keys were only being dropped when the btree
node was read in.

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

bcachefs: New helper __bch2_btree_insert_keys_interior()

Consolidate common parts of bch2_btree_insert_keys_interior() and
btree_split_insert_keys() - prep work for adding some new topology
assertions.

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

bcachefs: Rewrite btree nodes with errors

This patch adds self healing functionality for btree nodes - if we
notice a problem when reading a btree node, we just rewrite it.

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

bcachefs: Don't BUG_ON() btree topology error

This replaces an assertion in the btree merge path with a
bch2_inconsistent_error() - fsck will fix it.

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

bcachefs: Fix a use after free

Turns out, we weren't waiting on in flight btree writes when freeing
existing btree nodes. This lead to stray btree writes overwriting newly
allocated buckets, but only started showing itself with some of the
recent allocator work and another patch to move submitting of btree
writes to worqueues.

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

bcachefs: Don't flush btree writes more aggressively because of btree key cache

We need to flush the btree key cache when it's too dirty, because
otherwise the shrinker won't be able to reclaim memory - this is done by
journal reclaim. But journal reclaim also kicks btree node writes: this
meant that btree node writes were getting kicked much too often just
because we needed to flush btree key cache keys.

This patch splits journal pins into two different lists, and teaches
journal reclaim to not flush btree node writes when it only needs to
flush key cache keys.

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

bcachefs: Kill bch2_fs_usage_scratch_get()

This is an important cleanup, eliminating an unnecessary copy in the
transaction commit path.

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

bcachefs: Be more careful about JOURNAL_RES_GET_RESERVED

JOURNAL_RES_GET_RESERVED should only be used for updatse that need to be
done to free up space in the journal. In particular, when we're flushing
keys from the key cache, if we're flushing them out of order we
shouldn't be using it, since we're using up our remaining space in the
journal without dropping a pin that will let us make forward progress.

With this patch, BTREE_INSERT_JOURNAL_RECLAIM without
BTREE_INSERT_JOURNAL_RESERVED may return -EAGAIN - we can't wait on
journal reclaim if we're already in journal reclaim.

This means we need to propagate these errors up to journal reclaim,
indicating that flushing a journal pin should be retried in the future.

This is prep work for a patch to change the way journal reclaim works,
to split out flushing key cache keys because the btree key cache is too
dirty from journal reclaim because we need space in the journal.

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

bcachefs: bch2_foreground_maybe_merge() now correctly reports lock restarts

This means that btree node splits don't have to automatically trigger a
transaction restart.

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

bcachefs: Kill bch2_btree_node_get_sibling()

This patch reworks the btree node merge path to use a second btree
iterator to get the sibling node - which means
bch2_btree_iter_get_sibling() can be deleted. Also, it uses
bch2_btree_iter_traverse_all() if necessary - which means it should be
more reliable. We don't currently even try to make it work when
trans->nounlock is set - after a BTREE_INSERT_NOUNLOCK transaction
commit, hopefully this will be a worthwhile tradeoff.

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

bcachefs: Change where merging of interior btree nodes is trigger from

Previously, we were doing btree node merging from
bch2_btree_insert_node() - but this is called from the split path, when
we're in the middle of creating new nodes and deleting new nodes and the
iterators are in a weird state.

Also, this means we're starting a new btree_update while in the middle
of an existing one, and that's asking for deadlocks.

Much simpler and saner to trigger btree node merging _after_ the whole
btree node split path is finished.

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

bcachefs: Improve bch2_btree_update_start()

bch2_btree_update_start() is now responsible for taking gc_lock and
upgrading the iterator to lock parent nodes - greatly simplifying error
handling and all of the callers.

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

bcachefs: Start using bpos.snapshot field

This patch starts treating the bpos.snapshot field like part of the key
in the btree code:

* bpos_successor() and bpos_predecessor() now include the snapshot field
* Keys in btrees that will be using snapshots (extents, inodes, dirents
and xattrs) now always have their snapshot field set to U32_MAX

The btree iterator code gets a new flag, BTREE_ITER_ALL_SNAPSHOTS, that
determines whether we're iterating over keys in all snapshots or not -
internally, this controlls whether bkey_(successor|predecessor)
increment/decrement the snapshot field, or only the higher bits of the
key.

We add a new member to struct btree_iter, iter->snapshot: when
BTREE_ITER_ALL_SNAPSHOTS is not set, iter->pos.snapshot should always
equal iter->snapshot, which will be 0 for btrees that don't use
snapshots, and alsways U32_MAX for btrees that will use snapshots
(until we enable snapshot creation).

This patch also introduces a new metadata version number, and compat
code for reading from/writing to older versions - this isn't a forced
upgrade (yet).

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

bcachefs: Split out bpos_cmp() and bkey_cmp()

With snapshots, we're going to need to differentiate between comparisons
that should and shouldn't include the snapshot field. bpos_cmp is now
the comparison function that does include the snapshot field, used by
core btree code.

Upper level filesystem code generally does _not_ want to compare against
the snapshot field - that code wants keys to compare as equal even when
one of them is in an ancestor snapshot.

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

bcachefs: Fix packed bkey format calculation for new btree roots

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

bcachefs: Generate better bkey formats when splitting nodes

On btree node split, we weren't ensuring the min_key of the new larger
node packs in the new format for this node. This triggers some painful
slowpaths in the bset.c aux search tree code - this patch fixes that by
calculating a new format for the new node with the new min_key.

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

bcachefs: Drop bkey noops

Bkey noops were introduced to deal with trimming inline data extents in
place in the btree: if the u64s field of a bkey was 0, that u64 was a
noop and we'd start looking for the next bkey immediately after it.

But extent handling has been lifted above the btree - we no longer
modify existing extents in place in the btree, and the compatibilty code
for old style extent btree nodes is gone, so we can completely drop this
code.

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

bcachefs: Use pcpu mode of six locks for interior nodes

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

bcachefs: Use bch2_bpos_to_text() more consistently

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

bcachefs: Rename BTREE_ID enums for consistency with other enums

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

bcachefs: KEY_TYPE_discard is no longer used

KEY_TYPE_discard used to be used for extent whiteouts, but when handling
over overlapping extents was lifted above the core btree code it became
unused. This patch updates various code to reflect that.

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

bcachefs: Kill support for !BTREE_NODE_NEW_EXTENT_OVERWRITE()

bcachefs has been aggressively migrating filesystems and btree nodes to
the new format for quite some time - this shouldn't affect anyone
anymore, and lets us delete a _lot_ of code. Also, it frees up
KEY_TYPE_discard for a new whiteout key type for snapshots.

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

bcachefs: Add code to scan for/rewite old btree nodes

This adds a new data job type to scan for btree nodes in the old extent
format, and rewrite them.

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

bcachefs: Add an option for metadata_target

Also, make journal writes obey foreground_target and metadata_target.

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

bcachefs: Add BTREE_PTR_RANGE_UPDATED

This is so that when we discover btree topology issues, we can just
update the pointer to a btree node and signal btree read path that the
min/max keys in the node header should be updated from the node pointer.

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

bcachefs: Fix btree node split after merge operations

A btree node merge operation deletes a key in the parent node; if when
inserting into the parent node we split the parent node, we can end up
with a whiteout in the parent node that we don't want.

The existing code drops them before doing the split, because they can
screw up picking the pivot, but we forgot about the unwritten writeouts
area - that needs to be cleared out too.

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

bcachefs: Reserve some open buckets for btree allocations

This reverts part of the change from "bcachefs: Don't use
BTREE_INSERT_USE_RESERVE so much" - it turns out we still should be
reserving open buckets for btree node allocations, because otherwise
data bucket allocations (especially with erasure coding enabled) can use
up all our open buckets and we won't be able to do the metadata update
that lets us release those open bucket references. Oops.

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

bcachefs: Reduce/kill BKEY_PADDED use

With various newer key types - stripe keys, inline data extents - the
old approach of calculating the maximum size of the value is becoming
more and more error prone. Better to switch to bkey_on_stack, which can
dynamically allocate if necessary to handle any size bkey.

In particular we also want to get rid of BKEY_EXTENT_VAL_U64s_MAX.

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

bcachefs: Don't use BTREE_INSERT_USE_RESERVE so much

Previously, we were using BTREE_INSERT_RESERVE in a lot of places where
it no longer makes sense.

- we now have more open_buckets than we used to, and the reserves work
better, so we shouldn't need to use BTREE_INSERT_RESERVE just because
we're holding open_buckets pinned anymore.

- We have the btree key cache for updates to the alloc btree, meaning
we no longer need the btree reserve to ensure the allocator can make
forward progress.

This means that we should only need a reserve for btree updates to
ensure that copygc can make forward progress.

Since it's now just for copygc, we can also fold RESERVE_BTREE into
RESERVE_MOVINGGC (the allocator's freelist reserve).

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

bcachefs: Update transactional triggers interface to pass old & new keys

This is needed to fix a bug where we're overflowing iterators within a
btree transaction, because we're updating the stripes btree (to update
block counts) and the stripes btree trigger is unnecessarily updating
the alloc btree - it doesn't need to update the alloc btree when the
pointers within a stripe aren't changing.

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

bcachefs: Don't issue btree writes that weren't journalled

If we have an error in the btree interior update path that prevents us
from journalling the update, we can't issue the corresponding btree node
write - we didn't get a journal sequence number that would cause it to
be ignored in recovery.

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

bcachefs: Fix spurious alloc errors on forced shutdown

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

bcachefs: Ensure we always have a journal pin in interior update path

For the new nodes an interior btree update makes reachable, updates to
those nodes may be journalled after the btree update starts but before
the transactional part - where we make those nodes reachable. Those
updates need to be kept in the journal until after the btree update
completes, hence we should always get a journal pin at the start of the
interior update.

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

bcachefs: Delete dead code

The interior btree node update path has changed, this is no longer
needed.

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

bcachefs: More debug code improvements

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

bcachefs: Add more debug checks

tracking down a bug where we see a btree node pointer in the wrong node

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

bcachefs: Set preallocated transaction mem to avoid restarts

this will reduce transaction restarts, from observation of tracepoints.

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

bcachefs: Add accounting for dirty btree nodes/keys

This lets us improve journal reclaim, so that it now tries to make sure
no more than 3/4s of the btree node cache and btree key cache are dirty
- ensuring the shrinkers can free memory.

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

bcachefs: Drop typechecking from bkey_cmp_packed()

This only did anything in two places, and those can just be replaced
wiht bkey_cmp_left_packed()).

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

bcachefs: Convert various code to printbuf

printbufs know how big the buffer is that was allocated, so we can get
rid of the random PAGE_SIZEs all over the place.

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

bcachefs: Ensure we wake up threads locking node when reusing it

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

bcachefs: Fix an error path

We were missing a 'goto retry' and continuing on with an error pointer.

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

bcachefs: Fix a faulty assertion

Now that updates to interior nodes are journalled, we shouldn't be
checking topology of interior nodes until we've finished replaying
updates to that node.

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

bcachefs: Mark btree nodes as needing rewrite when not all replicas are RW

This fixes a bug where recovery fails when one of the devices is read
only.

Also - consolidate the "must rewrite this node to insert it" behind a
new btree node flag.

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

bcachefs: Use btree reserve when appropriate

Whenever we're doing an update that has pointers, that generally means
we need to do the update in order to release open bucket references - so
we should be using the btree open bucket reserve.

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

bcachefs: Btree key cache

This introduces a new kind of btree iterator, cached iterators, which
point to keys cached in a hash table. The cache also acts as a write
cache - in the update path, we journal the update but defer updating the
btree until the cached entry is flushed by journal reclaim.

Cache coherency is for now up to the users to handle, which isn't ideal
but should be good enough for now.

These new iterators will be used for updating inodes and alloc info (the
alloc and stripes btrees).

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

bcachefs: Don't deadlock when btree node reuse changes lock ordering

Btree node lock ordering is based on the logical key. However, 'struct
btree' may be reused for a different btree node under memory pressure.
This patch uses the new six lock callback to check if a btree node is no
longer the node we wanted to lock before blocking.

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

bcachefs: Always give out journal pre-res if we already have one

This is better than skipping the journal pre-reservation if we already
have one - we should still acount for the journal reservation we're
going to have to get.

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

bcachefs: Fix a linked list bug

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

bcachefs: btree_update_nodes_written() requires alloc reserve

Also, in the btree_update_start() path, if we already have a journal
pre-reservation we don't want to take another - that's a deadlock.

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

bcachefs: Interior btree updates are now fully transactional

We now update the alloc info (bucket sector counts) atomically with
journalling the update to the interior btree nodes, and we also set new
btree roots atomically with the journalled part of the btree update.

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

bcachefs: Factor out bch2_fs_btree_interior_update_init()

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

bcachefs: Fix two more deadlocks

Deadlock on shutdown:

btree_update_nodes_written() unblocks btree nodes from being written;
after doing so, it has to check if they were marked as needing to be
written and if so kick off those writes - if that doesn't happen, we'll
never release journal pins and shutdown will get stuck when flushing the
journal.

There was an error path where this didn't happen, because in the error
path we don't actually want those btree nodes write to happen; however,
we still have to kick off the write path so the journal pins get
released. The btree write path checks if we're in a journal error state
and doesn't do the actual write if we are.

Also - there was another deadlock because btree_update_nodes_written()
was taking the btree update off of the unwritten_list too soon - before
getting a journal reservation, which could fail and have to be retried.

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

bcachefs: Fix another deadlock in btree_update_nodes_written()

We also can't be blocking on btree node write locks while holding
btree_interior_update_lock.

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

bcachefs: Add a few tracepoints

Transaction restart tracing should probably be overhaulled at some
point.

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

bcachefs: Fix another deadlock in the btree interior update path

Can't take read locks on btree nodes while holding
btree_interior_update_lock. Also, fix a bug where we were leaking
journal prereservations.

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

bcachefs: Fix a deadlock on starting an interior btree update

Not legal to block on a journal prereservation with btree locks held.

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

bcachefs: Fix a debug mode assertion

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

bcachefs: Fix another error path locking bug

btree_update_nodes_written() was leaking a btree node lock on failure to
get a journal reservation.

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

bcachefs: Fix journalling of interior node updates

We weren't journalling updates done while splitting/compacting nodes -
oops.

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

bcachefs: Don't allocate memory while holding journal reservation

This fixes a lockdep splat - allocating memory can call
bch2_clear_page_bits() which takes mark_lock.

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

bcachefs: Kill bkey_type_successor

Previously, BTREE_ID_INODES was special - inodes were indexed by the
inode field, which meant the offset field of struct bpos wasn't used,
which led to special cases in e.g. the btree iterator code.

Now, inodes in the inodes btree are indexed by the offset field.

Also: prevously min_key was special for extents btrees, min_key for
extents would equal max_key for the previous node. Now, min_key =
bkey_successor() of the previous node, same as non extent btrees.

This means we can completely get rid of
btree_type_sucessor/predecessor.

Also make some improvements to the metadata IO validate/compat code.

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

bcachefs: Various fixes for interior update path

The locking was wrong, and we could get a use after free in the error
path where we weren't taking the entrie being freed off the unwritten
list.

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

bcachefs: Journal updates to interior nodes

Previously, the btree has always been self contained and internally
consistent on disk without anything from the journal - the journal just
contained pointers to the btree roots.

However, this meant that btree node split or compact operations - i.e.
anything that changes btree node topology and involves updates to
interior nodes - would require that interior btree node to be written
immediately, which means emitting a btree node write that's mostly empty
(using 4k of space on disk if the filesystemm blocksize is 4k to only
write perhaps ~100 bytes of new keys).

More importantly, this meant most btree node writes had to be FUA, and
consumer drives have a history of slow and/or buggy FUA support - other
filesystes have been bit by this.

This patch changes the interior btree update path to journal updates to
interior nodes, after the writes for the new btree nodes have completed.
Best of all, it turns out to simplify the interior node update path
somewhat.

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

bcachefs: trans_commit() path can now insert to interior nodes

This will be needed for the upcoming patches to journal updates to
interior btree nodes.

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

bcachefs: Iterator debug code improvements

More aggressively checking iterator invariants, and fixing the resulting
bugs. Also greatly simplifying iter_next() and iter_next_slot() - they
were hyper optimized before, but the optimizations were getting too
brittle.

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

bcachefs: Journal pin cleanups

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

bcachefs: Fix incorrect initialization of btree_node_old_extent_overwrite()

b->level and b->btree_id weren't set when the code was checking
btree_node_is_extents()

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

bcachefs: Seralize btree_update operations at btree_update_nodes_written()

Prep work for journalling updates to interior nodes - enforcing ordering
will greatly simplify those changes.

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

bcachefs: btree_ptr_v2

Add a new btree ptr type which contains the sequence number (random 64
bit cookie, actually) for that btree node - this lets us verify that
when we read in a btree node it really is the btree node we wanted.

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

bcachefs: introduce b->hash_val

This is partly prep work for introducing bch_btree_ptr_v2, but it'll
also be a bit of a performance boost by moving the full key out of the
hot part of struct btree.

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

bcachefs: Change btree split threshold to be in u64s

This fixes a bug with very small btree nodes where splitting would end
up with one of the new nodes empty.

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

bcachefs: Rework iter->pos handling

- Rework some of the helper comparison functions for consistency

- Currently trying to refactor all the logic that's different for
extents in the btree iterator code. The main difference is that for non
extents we search for a key greater than or equal to the search key,
while for extents we search for a key strictly greater than the search
key (iter->pos).

So that logic is now handled by btree_iter_search_key(), which computes
the real search key based on iter->pos and whether or not we're
searching for a key >= or > iter->pos.

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

bcachefs: Split out btree_trigger_flags

The trigger flags really belong with individual btree_insert_entries,
not the transaction commit flags - this splits out those flags and
unifies them with the BCH_BUCKET_MARK flags. Todo - split out
btree_trigger.c from buckets.c

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

bcachefs: Use KEY_TYPE_deleted whitouts for extents

Previously, partial overwrites of existing extents were handled
implicitly by the btree code; when reading in a btree node, we'd do a
mergesort of the different bsets and detect and fix partially
overlapping extents during that mergesort.

That approach won't work with snapshots: this changes extents to work
like regular keys as far as the btree code is concerned, where a 0 size
KEY_TYPE_deleted whiteout will completely overwrite an existing extent.

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

bcachefs: Add an assertion to track down a heisenbug

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

bcachefs: bkey noops

For upcoming inline data extents, we're going to need to be able to
shorten the value of existing bkeys in the btree - and to make that work
we're going to be able to need to pad out the space the value previously
took up with something.

This patch changes the various code that iterates over bkeys to handle
k->u64s == 0 as meaning "skip the next 8 bytes".

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

bcachefs: Initialize btree_node flags field in bch2_btree_root_alloc.

Valgrind data indicated that the flags field was only partially
initialized when written to disk.

Signed-off-by: Justin Husted <sigstop@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bcachefs: Fix a subtle race in the btree split path

We have to free the old (in memory) btree node _before_ unlocking the
new nodes - else, some other thread with a read lock on the old node
could see stale data after another thread has already updated the new
node.

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

bcachefs: Rework calling convention for marking overwrites

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

bcachefs: Improve key marking interface

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

bcachefs: More work to avoid transaction restarts

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

bcachefs: Delete duplicate code

Also rename for consistency

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

bcachefs: improved btree locking tracepoints

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

bcachefs: Don't pass around may_drop_locks

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

bcachefs: Kill remaining bch2_btree_iter_unlock() uses

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

bcachefs: btree_bkey_cached_common

This is prep work for the btree key cache: btree iterators will point to
either struct btree, or a new struct bkey_cached.

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

bcachefs: Write out fs usage consistently

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

bcachefs: Caller now responsible for calling mark_key for gc

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

bcachefs: add missing bch2_btree_iter_node_drop() call

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

bcachefs: trans_for_each_iter()

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

bcachefs: Add time stats for btree updates

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

bcachefs: Allocate fs_usage in do_btree_insert_at()

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

bcachefs: fix more locking bugs

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

bcachefs: Fix double counting when gc is running

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

bcachefs: gc lock no longer needed for disk reservations

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

bcachefs: journal_replay_early()

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

bcachefs: Persist alloc info on clean shutdown

- Does not persist alloc info for stripes yet
- Also does not yet include filesystem block/sector counts yet, from
struct fs_usage
- Not made use of just yet

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

bcachefs: Fix check for if extent update is allocating

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

bcachefs: More allocator startup improvements

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

bcachefs: s/usage_lock/mark_lock

better describes what it's for, and we're going to call a new lock
usage_lock

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

bcachefs: drop bogus percpu_ref_tryget

caller should already be guarding against rw, and checking here breaks
when caller needs to finish updates for going RO

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

bcachefs: Make bkey types globally unique

this lets us get rid of a lot of extra switch statements - in a lot of
places we dispatch on the btree node type, and then the key type, so
this is a nice cleanup across a lot of code.

Also improve the on disk format versioning stuff.

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

bcachefs: Hold usage_lock over mark_key and fs_usage_apply

Fixes an inconsistency at the end of gc

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

bcachefs: Btree locking fix, refactoring

Hit an assertion, probably spurious, indicating an iterator was unlocked
when it shouldn't have been (spurious because it wasn't locked at all
when the caller called btree_insert_at()).

Add a flag, BTREE_ITER_NOUNLOCK, and tighten up the assertions

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

bcachefs: gc now operates on second set of bucket marks

This means we can now use gc to verify the allocation information -
important for testing persistant alloc info

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

bcachefs: Don't block on journal reservation with btree locks held

Fixes a deadlock between the allocator thread, when it first starts up,
and journal replay

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

bcachefs: Erasure coding

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

bcachefs: revamp to_text methods

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

bcachefs: more key marking refactoring

prep work for erasure coding

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

bcachefs: replicas: prep work for stripes

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

bcachefs: Allocation code refactoring

bch2_alloc_sectors_start() was a nightmare to work with - it's got some
tricky stuff to do, since it wants to use the buckets the writepoint
already has, unless they're not in the target it wants to write to,
unless it can't allocate from any other devices in which case it will
use those buckets if it has to - et cetera.

This restructures the code to start with a new empty list of open
buckets we're going to use for the new allocation, pulling buckets from
the write point's list as we decide that we really are going to use
them - making the code somewhat more functional and drastically easier
to understand.

Also fixes a bug where we could end up waiting on c->freelist_wait
(because allocating from one device failed) but return success from
bch2_bucket_alloc(), because allocating from a different device
succeeded.

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

bcachefs: Split out alloc_background.c

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

bcachefs: Fix a deadlock

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

bcachefs: Comparison function cleanups

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

bcachefs: lift ordering restriction on 0 size extents

This lifts the restriction that 0 size extents must not overlap with
other extents, which means we can now sort extents and non extents the
same way, and will let us simplify a bunch of other stuff as well.

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

bcachefs: Change how replicated data is accounted

Due to compression, the different replicas of a replicated extent don't
necessarily have to take up the same amount of space - so replicated
data sector counts shouldn't be stored divided by the number of
replicas.

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

bcachefs: Account for internal fragmentation better

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

bcachefs: kill s_alloc, use bch_data_type

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

bcachefs: bch2_mark_key() now takes bch_data_type

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

bcachefs: Invalidate buckets when writing to alloc btree

Prep work for persistent alloc information. Refactoring also lets us
make free_inc much smaller, which means a lot fewer buckets stranded on
freelists.

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

bcachefs: Fix a use after free in the journal code

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

bcachefs: Initial commit

Initially forked from drivers/md/bcache, bcachefs is a new copy-on-write
filesystem with every feature you could possibly want.

Website: https://bcachefs.org

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