This adds a new helper, bch2_trans_mutex_lock(), for locking a mutex -
dropping and retaking btree locks as needed.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
A thread should never be using more than one btree_trans - doing so is
an invitation for deadlocks.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This code predates plumbing btree_trans through the bucket allocation
path: switching to it fixes a deadlock due to using multiple btree_trans
at the same time, which we never want to do.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Like bch2_trans_mark_bucket(), we shouldn't be incrementing a bucket gen
while it's still open - erasure coding was hitting this.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Now that we have much more efficient updates to the LRU btree, this
patch adds a new LRU that indexes buckets by fragmentation.
This means copygc no longer has to scan every bucket to find buckets
that need to be evacuated.
Changes:
- A new field in bch_alloc_v4, fragmentation_lru - this corresponds to
the bucket's position in the fragmentation LRU. We add a new field
for this instead of calculating it as needed because we may make the
fragmentation LRU optional; this field indicates whether a bucket is
on the fragmentation LRU.
Also, zoned devices will introduce variable bucket sizes; explicitly
recording the LRU position will be safer for them.
- A new copygc path for using the fragmentation LRU instead of
scanning every bucket and building up an in-memory heap.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
- We were failing to set the key type on the whiteouts it was creating,
oops.
- Also, we need to create whiteouts when generating front splits, not
just back splits.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This fixes a bug where bch2_mark_snapshot() wasn't called for existing
snapshot nodes being updated when child nodes were added.
This led to the data update path thinking the key being updated was for
a snapshot that didn't have children, causing it to fail to insert
whiteouts when splitting existing extents.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
When fully overwriting an existing extent, we may need to generate a
whiteout - not just if the extent being overwritten was in an older
snapshot, but also if it was overwriting an extent in an older snapshot.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Repair now checks if overlapping extents exist in the same snapshot
and calls update_trans_update_extent to do the repair work.
Signed-off-by: Daniel Hill <daniel@gluo.nz>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This fixes a very-rare race in our assertion, with needs_whiteout being
modified in the btree key.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This fixes a rare buffer overrun when one field is growing and another
field is shrinking - and is a nice simplification as well.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
If failed to read a btree root - or if we're not using a btree root,
because of the reconstruct_alloc option - make sure we update the
corresponding info for the key/level for the root on disk.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Triggers current trip-up on the faulty reflink we're trying to repair,
Disabling them lets us fix broken reflink and continue.
Signed-off-by: Daniel Hill <daniel@gluo.nz>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Tweak journal reclaim to ensure the btree node cache isn't more
than half dirty so that memory reclaim can always make progress - the
same as we do for the btree key cache.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
The promote path calls data_update_init() and now that we take locks here,
there's potential for promote to block our read path, just error
when we can't take the lock instead of blocking.
Signed-off-by: Daniel Hill <daniel@gluo.nz>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Make sure to check for lru entries that point to buckets that don't
exist as well as buckets in the wrong state, and improve the error
message we print out.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
We shouldn't be evaluating cond again if it already returned true.
This fixes a bug when this helper is used for taking nocow locks.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
The recent nocow locking rework introduced a deadlock in the data move
path: the new nocow locking scheme uses a hash table with a fixed size
array for chaining, meaning on hash collision we may have to wait for
other locks to be released before we can lock a bucket.
And since the data move path needs to submit writes from the same thread
that's taking nocow locks and submitting reads, this introduces a
deadlock.
This shouldn't happen often in practice, but since the data move path
can keep large numbers of IOs in flight simultaneously, it's something
we have to handle.
This patch makes move_ctxt_wait_event() available to
bch2_data_update_init() and uses it when appropriate, which is our
normal solution to this kind of thing.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This patch changes how the LRU index works:
Instead of using KEY_TYPE_lru where the bucket the lru entry points to
is part of the value, this switches to KEY_TYPE_set and encoding the
bucket we refer to in the low bits of the key.
This means that we no longer have to check for collisions when inserting
LRU entries. We'll be making using of this in the next patch, which adds
a btree write buffer - a pure write buffer for btree updates, where
updates are appended to a simple array and then periodically sorted and
batch inserted.
This is a new on disk format version, and a forced upgrade.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This improves the nocow lock table so that hash table entries have
multiple locks, and locks specify which bucket they're for - i.e. we can
now resolve hash collisions.
This is important because the allocator has to skip buckets that are
locked in the nocow lock table, and previously hash collisions would
cause it to spuriously skip unlocked buckets.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
data_update_init allocates several resources, but we forget to clean
these up when it fails.
Signed-off-by: Daniel Hill <daniel@gluo.nz>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
To improve mount times, add a btree for just bucket gens, 256 of them
per key: this means we'll have to scan drastically less metadata at
startup.
This adds
- trigger for keeping it in sync with the all btree
- initialization code, for filesystems from previous versions
- new path for reading bucket gens
- new fsck code
And a new on disk format version.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This adds support for nocow mode, where we do writes in-place when
possible. Patch components:
- New boolean filesystem and inode option, nocow: note that when nocow
is enabled, data checksumming and compression are implicitly disabled
- To prevent in-place writes from racing with data moves
(data_update.c) or bucket reuse (i.e. a bucket being reused and
re-allocated while a nocow write is in flight, we have a new locking
mechanism.
Buckets can be locked for either data update or data move, using a
fixed size hash table of two_state_shared locks. We don't have any
chaining, meaning updates and moves to different buckets that hash to
the same lock will wait unnecessarily - we'll want to watch for this
becoming an issue.
- The allocator path also needs to check for in-place writes in flight
to a given bucket before giving it out: thus we add another counter
to bucket_alloc_state so we can track this.
- Fsync now may need to issue cache flushes to block devices instead of
flushing the journal. We add a device bitmask to bch_inode_info,
ei_devs_need_flush, which tracks devices that need to have flushes
issued - note that this will lead to unnecessary flushes when other
codepaths have already issued flushes, we may want to replace this with
a sequence number.
- New nocow write path: look up extents, and if they're writable write
to them - otherwise fall back to the normal COW write path.
XXX: switch to sequence numbers instead of bitmask for devs needing
journal flush
XXX: ei_quota_lock being a mutex means bch2_nocow_write_done() needs to
run in process context - see if we can improve this
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
