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>
It turns out that it's currently impossible to invalidate buckets
containing only cached data if they're part of a stripe. The normal
bucket invalidate path can't do it because we have to be able to
incerement the bucket's gen, which isn't correct becasue it's still a
member of the stripe - and the bucket invalidate path makes the bucket
availabel for reuse right away, which also isn't correct for buckets in
stripes.
What would work is invalidating cached data by following backpointers,
except that cached replicas don't currently get backpointers - because
they would be awkward for the existing bucket invalidate path to delete
and they haven't been needed elsewhere.
So for the time being, to prevent running out of space in stripes,
switch the data update path to not leave cached replicas; we may revisit
this in the future.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Previously, copygc used a fifo for tracking buckets in flight - this had
the disadvantage of being fixed size, since we pass references to
elements into the move code.
This restructures it to be a hash table and linked list, since with
erasure coding we need to be able to pipeline across an arbitrary number
of buckets.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This adds a flags param to bch2_backpointer_get_key() so that we can
pass BTREE_ITER_INTENT, since ec_stripe_update_extent() is updating the
extent immediately.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
It appears freespace init can still take awhile, and we've had a report
or two of it getting stuck - let's have it print out where it's at every
10 seconds.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Like in the recovery, and device add, we have to check if devices don't
have the freespace btree initialized - this was missed in the device hot
add path.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This just adds a line for how long copygc has been waiting to sysfs
copygc_wait, helpful for debugging why copygc isn't running.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
bch2_path_put_nokeep() is sketchy, and we should consider removing it:
it unconditionally frees btree_paths once their ref hits 0.
The assumption is that we only use it for paths that have never been
visible outside the btree core btree code; i.e. higher level code will
never be making assumptions about locking based on these paths.
However, there's subtle brokenness with this approach:
- If we call bch2_path_put(), then bch2_path_put_nokeep(),
bch2_path_put() may free the first path on the assumption that we we
have another path keeping a node locked - but then
bch2_path_put_nokeep() just unconditionally frees it.
The same bug may arise if we're calling bch2_path_put() and
bch2_path_put_nokeep() on the same (refcounted) path, or two adjacent
paths that point to the same btree node.
This patch hacks around one of these bugs by calling
bch2_path_put_nokeep() first in bch2_trans_iter_exit.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
The journal stucking check in bch2_journal_space_available() is
particularly aggressive and can lead to premature shutdown in some
rare cases. This is difficult to reproduce, but also comes along
with a fatal error and so is worthwhile to be cautious.
For example, we've seen instances where the journal is under heavy
reservation pressure, the journal allocation path transitions into
the final available journal bucket, the journal write path
immediately consumes that bucket and calls into
bch2_journal_space_available(), which then in turn flags the journal
as stuck because there is no available space and shuts down the
filesystem instead of submitting the journal write (that would have
otherwise succeeded).
To avoid this problem, simplify the journal stuck checking by just
relying on the higher level logic in the journal reservation path.
This produces more useful debug output and is a more reliable
indicator that things have bogged down.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
bcachefs checks for journal stuck conditions both in the journal
space calculation code and the journal reservation slow path. The
logic in both places is rather tricky and can result in
non-deterministic failure characteristics and debug output.
In preparation to condense journal stuck handling to a single place,
refactor the __journal_res_get() logic into a standalone helper.
Since multiple callers into the reservation code can result in
duplicate reports, use the ->err_seq field as a serialization
mechanism for the debug dump. Finally, add some comments to help
explain the logic and hopefully facilitate further improvements in
the future.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
bcachefs detects journal stuck conditions in a couple different
places. If the logic in the journal reservation slow path happens to
detect the problem, I've seen instances where the filesystem remains
deadlocked even though it has been shut down. This is occasionally
reproduced by generic/333, and usually manifests as one or more
tasks stuck in the journal reservation slow path.
To help avoid this problem, repeat the journal error check in
__journal_res_get() once under spinlock to cover the case where the
previous lock holder might have triggered shutdown. This also helps
avoid spurious/duplicate stuck reports. Also, wake the journal from
the halt code to make sure blocked callers of the journal res
slowpath have a chance to wake up and observe the pending error.
This survives an overnight looping run of generic/333 without the
aforementioned lockups.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
The btree write buffer flush code is prone to causing journal
deadlock due to inefficient use and release of reservation space.
Reservation is not pre-reserved for write buffered keys (as is done
for key cache keys, for example), because the write buffer flush
side uses a fast path that attempts insertion without need for any
reservation at all.
The write buffer flush attempts to deal with this by inserting keys
using the BTREE_INSERT_JOURNAL_RECLAIM flag to return an error on
journal reservations that require blocking. Upon first error, it
falls back to a slow path that inserts in journal order and supports
moving the associated journal pin forward.
The problem is that under pathological conditions (i.e. smaller log,
larger write buffer and journal reservation pressure), we've seen
instances where the fast path fails fairly quickly without having
completed many insertions, and then the slow path is unable to push
the journal pin forward enough to free up the space it needs to
completely flush the buffer. This problem is occasionally reproduced
by fstest generic/333.
To avoid this problem, update the fast path algorithm to skip key
inserts that fail due to inability to acquire needed journal
reservation without immediately breaking out of the loop. Instead,
insert as many keys as possible, zap the sequence numbers to mark
them as processed, and then fall back to the slow path to process
the remaining set in journal order. This reduces the amount of
journal reservation that might be required to flush the entire
buffer and increases the odds that the slow path is able to move the
journal pin forward and free up space as keys are processed.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
A workqueue resource deadlock has been observed when running fsck
on a filesystem with a full/stuck journal. fsck is not currently
able to repair the fs due to fairly rapid emergency shutdown, but
rather than exit gracefully the fsck process hangs during the
shutdown sequence. Fortunately this is easily recoverable from
userspace, but the root cause involves code shared between the
kernel and userspace and so should be addressed.
The deadlock scenario involves the main task in the bch2_fs_stop()
-> bch2_fs_read_only() path waiting on write references to drain
with the fs state lock held. A bch2_read_only_work() workqueue task
is scheduled on the system_long_wq, blocked on the state lock.
Finally, various other write ref holding workqueue tasks are
scheduled to run on the same workqueue and must complete in order to
release references that the initial task is waiting on.
To avoid this problem, we can split the dependent workqueue tasks
across different workqueues. It's a bit of a waste to create a
dedicated wq for the read-only worker, but there are several tasks
throughout the fs that follow the pattern of acquiring a write
reference and then scheduling to the system wq. Use a local wq
for such tasks to break the subtle dependency between these and the
read-only worker.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
We were going into an infinite loop when printing out backpointers, due
to never incrementing bp_offset - whoops.
Also limit the number of backpointers we print to 10; this is debug code
and we only need to print a sample, not all of them.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
We shouldn't be printing out fsck errors for expected errors - this
helps make test logs more readable, and makes it easier to see what the
actual failure was.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This is a bit awkward: we're passing around a btree_trans, but we're not
in a context where transaction restarts are handled - we should try to
come up with a better way to denote situations like this.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
With regular waitlists, we need to ensure we always call finish_wait().
With closures, the equivalent is that we need to call closure_sync()
before returning with a stack-allocated closure.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
The nocow write error path was iterating over pointers in an extent,
aftre we'd dropped btree locks - oops.
Fortunately we'd already stashed what we need in nocow_lock_bucket, so
use that instead.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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>
This fixes a bug in bch2_evict_subvolume_inodes(): d_mark_dontcache()
doesn't handle the case where i_count is already 0, we need to grab and
put the inode in order for it to be dropped.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Subvolumes, including their root inodes, get deleted asynchronously
after an unlink. But we still need to ensure that we tell the VFS the
inode has been deleted, otherwise VFS writeback could fire after
asynchronous deletion has finished, and try to write to an
inode/subvolume that no longer exists.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
transaction hooks aren't supposed to run unless we know the transaction
is going to commit succesfully: this fixes a bug with attempting to
delete a subvolume multiple times.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
We may end up in a situation where allocating the buffer for the sorted
journal_keys fails - but it would likely succeed, post compaction where
we drop duplicates.
We've had reports of this allocation failing, so this adds a slowpath to
do the compaction incrementally.
This is only a band-aid fix; we need to look at limiting the number of
keys in the journal based on the amount of system RAM.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
We now print the pos where the backpointer was found in the btree, as
well as the exact bucket:bucket_offset of the data, to aid in grepping
through logs.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This implements a new shutdown path for erasure coding, which is needed
for the upcoming BCH_WRITE_WAIT_FOR_EC write path.
The process is:
- Cancel new stripes being built up
- Close out/cancel open buckets on write points or the partial list
that are for stripes
- Shutdown rebalance/copygc
- Then wait for in flight new stripes to finish
With BCH_WRITE_WAIT_FOR_EC, move ops will be waiting on stripes to fill
up before they complete; the new ec shutdown path is needed for shutting
down copygc/rebalance without deadlocking.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This also adds bch2_write_op_to_text(): now we can see outstand moves,
useful for debugging shutdown with the upcoming BCH_WRITE_WAIT_FOR_EC
and likely for other things in the future.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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>
In rare cases, bch2_check_extents_to_backpointers() would incorrectly
flag an extent has having a missing backpointer when we just needed to
flush the btree write buffer - we weren't tracking the last flushed
position correctly.
This adds a level field to the last_flushed pos, fixing a bug where we'd
sometimes fail on a new root node.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
We're not supposed to have nested (locked) btree_trans on the stack:
this means copygc shutdown needs to exit our btree_trans before exiting
the move_ctxt, which calls bch2_write().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
BTREE_ITER_CACHED should really be the default for cached btrees - this
is an easy mistake to make.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This is a workaround for a btree path overflow - searching with
BTREE_ITER_INTENT periodically saves the iterator position for updates,
which eventually overflows.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
If we errored out on a new stripe before fully allocating it, we
shouldn't be zeroing out unwritten data.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This fixes a null ptr deref when creating new snapshots:
bch2_create_trans() will lookup the subvolume and find the _new_
snapshot in the BCH_CREATE_SUBVOL path that's being created in that
transaction.
We have to call bch2_mark_snapshot() earlier so that it's properly
initialized, instead of leaving it for transaction commit.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This changes the write path to not add write ops to to the write_point's
list of pending work items until it's ready; this means we have to
change the lock protecting it to an irq-safe lock, but means
bch2_write_point_do_index_updates() no longer has to iterate over the
list, which is beneficial with the way the new BCH_WRITE_WAIT_FOR_EC
code works.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This is not technically correct - it's subject to a race if we ever end
up with a stripe with all empty blocks (that needs to be deleted) being
held open. But the "correct" version was much too inefficient, and soon
we'll be adding a stripes LRU.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This will be used for move writes, which will be waiting until the
stripe is created to do the index update. They need to prevent the
stripe from being reclaimed until their index update is done, so we need
another refcount that just keeps the stripe open.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
# Conflicts:
# fs/bcachefs/ec.c
# fs/bcachefs/io.c
This makes some improvements to the logic for adding/removing replicas,
as part of the larger erasure coding improvements. We now directly
consider number of replicas desired for the given inode, and
extent/pointer durability: this ensures that the extent ends up with the
desired number of replicas when we're replacing multiple pointers with
one that has higher durability (e.g. erasure coded).
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
- __bch2_bkey_drop_ptr() -> bch2_bkey_drop_ptr_noerror(), now available
outside extents.
- Split bch2_bkey_has_device() and bch2_bkey_has_device_c(), const and
non const versions
- bch2_extent_has_ptr() now returns the pointer it found
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
