When flags & btree_id are constants, we can constant fold the entire
calculation of the actual iterator flags - and the whole thing becomes
small enough to inline.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
- Marking a non-static function as inline doesn't actually work and is
now causing problems - drop that
- Introduce BCACHEFS_LOG_PREFIX for when we want to prefix log messages
with bcachefs (filesystem name)
- Userspace doesn't have real percpu variables (maybe we can get this
fixed someday), put an #ifdef around bch2_disk_reservation_add()
fastpath
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
btree_path_copy() doesn't need to call
bch2_btree_path_check_sort_fast() - the newly allocated path will always
be in the correct position, post copy; also delete some redundant
branches from __bch2_btree_path_make_mut().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
- Don't call into bch2_encrypt_bio() when we're not encrypting
- Pull slowpath out of trans_lock_write()
- Make sure bc2h_trans_journal_res_get() gets inlined.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
- In the btree iterator code that overlays keys from the journal, we
were incorrectly specifying level=0 instead of the btree_path's
current level in a few places
- When we didn't do journal replay, we shouldn't free the journal keys:
this fixes cmd_list and cmd_dump, which run in norecovery mode
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This moves the JOURNAL_REPLAY_DONE flag check from
bch2_trans_iter_init() to bch2_trans_init(), where we stash a copy in
btree_trans - gaining us a small performance improvement.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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>
Now we store the transaction's fn idx in a local variable, instead of
redoing the lookup every time we call bch2_trans_init().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
local_clock() isn't always completely accurate - e.g. on machines with
TSC drift - but ktime_get_ns() overhead is too high, unfortunately.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
We were forgetting to count down the number of nodes to prefetch, firing
off _way_ more than intended - whoops.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
In the drop_alloc tests, we may end up calling
bch2_btree_iter_peek_slot() on an interior level that doesn't exist.
Previously, this would hit the path->uptodate assertion in
bch2_btree_path_peek_slot(); this path first checks a NULL btree node,
which is how we know we're at the end of the btree.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
The btree iterator code may allocate extra btree paths, temporarily,
that do not refer to keys being returned: we don't need to wait until
transaction restart to drop these, when they're not referenced they
should be deleted right away.
This fixes a transaction path overflow bug.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
There was a rare bug when path->locks_want was nonzero, but not
BTREE_MAX_DEPTH, where we'd return on a valid node that wasn't locked -
oops.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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>
- move slowpath code to a separate function, btree_path_overflow()
- no need to use hweight64
- copy nr_max_paths from btree_transaction_stats to btree_trans,
avoiding a data dependency in the fast path
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This adds a helper for printing a large buffer one line at a time, to
avoid the 1k printk limit.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Most of the node_relock_fail trace events are generated from
bch2_btree_path_verify_level(), when debugcheck_iterators is enabled -
but we're not interested in these trace events, they don't indicate that
we're in a slowpath.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
In the event that we're not finished debugging the cycle detector, this
adds a new file to debugfs that shows what the cycle detector finds, if
anything. By comparing this with btree_transactions, which shows held
locks for every btree_transaction, we'll be able to determine if it's
the cycle detector that's buggy or something else.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
We've outgrown our own deadlock avoidance strategy.
The btree iterator API provides an interface where the user doesn't need
to concern themselves with lock ordering - different btree iterators can
be traversed in any order. Without special care, this will lead to
deadlocks.
Our previous strategy was to define a lock ordering internally, and
whenever we attempt to take a lock and trylock() fails, we'd check if
the current btree transaction is holding any locks that cause a lock
ordering violation. If so, we'd issue a transaction restart, and then
bch2_trans_begin() would re-traverse all previously used iterators, but
in the correct order.
That approach had some issues, though.
- Sometimes we'd issue transaction restarts unnecessarily, when no
deadlock would have actually occured. Lock ordering restarts have
become our primary cause of transaction restarts, on some workloads
totally 20% of actual transaction commits.
- To avoid deadlock or livelock, we'd often have to take intent locks
when we only wanted a read lock: with the lock ordering approach, it
is actually illegal to hold _any_ read lock while blocking on an intent
lock, and this has been causing us unnecessary lock contention.
- It was getting fragile - the various lock ordering rules are not
trivial, and we'd been seeing occasional livelock issues related to
this machinery.
So, since bcachefs is already a relational database masquerading as a
filesystem, we're stealing the next traditional database technique and
switching to a cycle detector for avoiding deadlocks.
When we block taking a btree lock, after adding ourself to the waitlist
but before sleeping, we do a DFS of btree transactions waiting on other
btree transactions, starting with the current transaction and walking
our held locks, and transactions blocking on our held locks.
If we find a cycle, we emit a transaction restart. Occasionally (e.g.
the btree split path) we can not allow the lock() operation to fail, so
if necessary we'll tell another transaction that it has to fail.
Result: trans_restart_would_deadlock events are reduced by a factor of
10 to 100, and we'll be able to delete a whole bunch of grotty, fragile
code.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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>
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>
Add a type descriptor to btree_bkey_cached_common - there's no reason
not to since we've got padding that was otherwise unused, and this is a
nice cleanup (and helpful in later patches).
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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>
Improve our debugfs output, to help in debugging deadlocks: this shows,
for every btree node we print, the current number of readers/intent
locks/write locks held.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This patch
- tracks maximum bch2_trans_kmalloc() memory used in btree_transaction_stats
- makes it available in debugfs
- switches bch2_trans_init() to using that for the amount of memory to
preallocate, instead of the parameter passed in
This drastically reduces transaction restarts, and means we no longer
need to track this in the source code.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Previously, we used two different bit arrays for tracking held btree
node locks. This patch switches to an array of two bit integers, which
will let us track, in a future patch, when we hold a write lock.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Held btree locks are tracked in btree_path->nodes_locked and
btree_path->nodes_intent_locked. Upcoming patches are going to change
the representation in struct btree_path, so this patch switches to
proper helpers instead of direct access to these fields.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Start to centralize some of the locking code in a new file; more locking
code will be moving here in the future.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
- fsck_inode_rm() wasn't returning BCH_ERR_transaction_restart_nested
- change bch2_trans_verify_not_restarted() to call panic() - we don't
want these errors to be missed
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
iter->k needs to be consistent with iter->pos - required for
bch2_btree_iter_(rewind|advance) to work correctly.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
When returning a key from the key cache, in BTREE_ITER_WITH_KEY_CACHE
mode, we don't want to set should_be_locked on iter->path; we're not
returning a key from that path, so we donn't need to, and also since we
traversed the key cache iterator before setting should_be_locked on that
path it might be unlocked (if we unlocked, bch2_trans_relock() won't
have relocked it).
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
We should be calling btree_node_mem_ptr_set() before path_level_init(),
since we already touched the key that btree_node_mem_ptr_set() will
modify and path_level_init() will be doing the lookup in the child btree
node we're recursing to.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Instead of counting transaction restarts, count when the transaction is
restarted: if bch2_trans_begin() was called when the transaction wasn't
restarted we need to ensure restart_count is still incremented.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
We need a way to check if the machinery for handling btree_paths with in
a transaction is behaving reasonably, as it often has not been - we've
had bugs with transaction path overflows caused by duplicate paths and
plenty of other things.
This patch tracks, per transaction fn, the most btree paths ever
allocated by that transaction and makes it available in debugfs.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Going to be adding more things to this in the next patch.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
bch2_path_put() is supposed to drop paths that aren't needed on
transaction restart, or to hold locks that we're supposed to keep until
transaction commit: but it was failing to free paths in some cases that
it should have, leading to transaction path overflows with lots of
duplicate paths.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
These were used more prior to getting rid of the in-memory bucket arrays
- they don't serve much purpose anymore, and deleting them lets us write
better assertions.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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>
