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It now includes more info - whether the bucket was for metadata or data
- and also call it in the same place as the bucket_alloc_fail
tracepoint.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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This deletes our old lock ordering based deadlock avoidance code.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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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>
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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>
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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>
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It now includes journal_flags.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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It now prints the error name when the btree node is an error pointer;
also, don't trace failures when the the btree node is
BCH_ERR_no_btree_node_up.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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This is just some type safety cleanup.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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six_lock_count now counts up whether a write lock held, and this patch
now also correctly counts six_lock->intent_lock_recurse.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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This message fires when the data update path races with a foreground
write that overwrote the data that was being moved - this isn't a
concerning event as long as it's not happening too often, so switch it
to a tracepoint.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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This is to fix a livelock in the btree split path described by the
previous patch.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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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>
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- use strlcpy(), not strncpy()
- add tracepoints for btree_path alloc and free
- give the tracepoint for key cache upgrade fail a proper name
- add a tracepoint for btree_node_upgrade_fail
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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In CONFIG_BCACHEFS_DEBUG mode, we'll now randomly issue transaction
restarts - with a decaying probability based on the number of restarts
we've already had, to ensure that transactions eventually make forward
progress. This should help shake out some bugs.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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All transaction restarts need a tracepoint - this is essential for
debugging
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Instead of overloading standard error codes (EINTR/EAGAIN), and defining
short lists of error codes in multiple places that potentially end up
overlapping & conflicting, we're now going to have one master list of
error codes.
Error codes are defined with an x-macro: thus we also have
bch2_err_str() now.
Also, error codes have a class field. Now, instead of checking for
errors with ==, code should use bch2_err_matches(), which returns true
if the error is equal to or a sub-error of the error class.
This means we can define unique errors for every source location where
an error is generated, which will help improve our error messages.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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We should be printing the number of free buckets, not just the number of
available buckets.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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- invalidate_one_bucket() now returns 1 when we don't have any buckets
on this device to invalidate, ensuring we don't spin
- the tracepoint invocation is moved to after the transaction commit,
and we now include the number of cached sectors in the tracepoint
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Delete some obsolete tracepoints, organize alloc tracepoints better,
make a few tracepoints more consistent.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Now that the bucket_alloc_fail tracepoint includes the error code, the
open_bucket_alloc_fail tracepoint is redundant.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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This behavior dates from the early, early days of bcache, and upon
further delving appears to not make any sense. The shrinker only works
in terms of 'objects' of unknown size; normalizing to pages only had the
effect of changing the batch size, which we could do directly - if we
wanted; we probably don't. Normalizing to pages meant our batch size was
very small, which seems to have been keeping us from doing as much
shrinking as we should be under heavy memory pressure; this patch
appears to alleviate some OOMs we've been seeing.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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- bch2_clear_need_discard() was using bch2_trans_relock() incorrectly,
and always bailing out before doing any work - ouch.
- Add a tracepoint that fires every time bch2_do_discards() runs, and
tells us about the work it did
- When too many buckets aren't able to be discarded because they need a
journal commit, bch2_do_discards now flushes the journal.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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For backpointers, we'll need to delete old backpointers before adding
new backpointers - otherwise we'll run into spurious duplicate
backpointer errors.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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This adds counters for each of the reasons we may skip allocating a
bucket - we're seeing a bug where we loop endlessly trying to allocate
when we should have plenty of buckets available, so hopefully this will
help us track down why.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Previously, we'd go into an infinite loop when attempting to cache a
bkey in the key cache larger than 128 u64s - since we were only using a
u8 for the size field, it'd get rounded up to 256 then truncated to 0.
Oops.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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- bucket_alloc_fail now indicates whether allocation was nonblocking
- we now return strings, not integers, for alloc reserve.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Also include the number of buckets available, and the number of buckets
awaiting journal commit - and add a sysfs counter, too.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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This fixes a regression from "bcachefs: Stash a copy of key being
overwritten in btree_insert_entry". In btree_key_can_insert_cached(), we
may reallocate the key cache key, invalidating pointers previously
returned by peek() - fix it by issuing a transaction restart.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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The error code when we fail to allocate a node in the btree node cache
doesn't make it to bch2_btree_path_traverse_all(). Instead, we need to
stash a flag in btree_trans so we know we have to take the cannibalize
lock.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Some of our tracepoints were calling snprintf("pS") - which does symbol
table lookups - in TP_fast_assign(), which turns out to be a really bad
idea.
This was done because perf trace wasn't correctly printing tracepoints
that use %pS anymore - but it turns out trace-cmd does handle it
correctly.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Updates to non key cache iterators will now be transparently redirected
to the key cache for cached btrees.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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This improves the transaction restart tracepoints - adding distinct
tracepoints for all the locations and reasons a transaction might have
been restarted, and ensures that there's a tracepoint for every
transaction restart.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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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>
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Add a field to bch_dev for the dev_t of the underlying block device -
this fixes a null ptr deref in tracepoints.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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This is to help with diagnosing why the btree node can doesn't seem to
be shrinking - we've had issues in the past with granularity/batch size,
since btree nodes are so big.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Instead of unconditionally upgrading read locks to intent locks in
do_bch2_trans_commit(), this patch changes the path that takes write
locks to first trylock, and then if trylock fails check if we have a
conflicting read lock, and restart the transaction if necessary.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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These haven't turned out to be useful
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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If an extent ends up with a replica that is encrypted an a replica that
isn't encrypted (due the user changing options), and then
copygc/rebalance moves one of the replicas by reading from the
unencrypted replica, we had a bug where we wouldn't correctly initialize
op->nonce - for each crc field in an extent, crc.offset + crc.nonce must
be equal.
This patch fixes that by moving op.nonce initialization to
bch2_migrate_write_init.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Btree iterator tracepoints should print whether they're for the key
cache.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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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>
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%pU for printing out pointers to uuids doesn't work in perf trace
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Trying to debug an issue where after traverse_all() we shouldn't have to
traverse any iterators... yet we are
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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This uses the kthread_wait_freezable() macro to simplify a lot of the
allocator thread code, along with cleaning up bch2_invalidate_bucket2().
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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By changing it to upgrade iterators to intent locks to avoid lock
restarts we can simplify __bch2_btree_node_lock() quite a bit - this
fixes a probable bug where it could potentially drop a lock on an
unrelated error but still succeed instead of causing a transaction
restart.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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We have foreground btree node merging now, and any future btree node
merging improvements are going to be based off of that code.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
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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>
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