Kent Overstreet [Sat, 25 Jan 2025 02:29:24 +0000 (21:29 -0500)]
bcachefs: Journal writes are now IOPRIO_CLASS_RT
System performance is particularly sensitive to journal write latency,
the number of outstanding journal writes is bounded and we can't issue
journal flushes until other journal writes have completed.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sun, 26 Jan 2025 00:22:50 +0000 (19:22 -0500)]
bcachefs: Improve journal pin flushing
Running the preempt tiering tests with a lower than normal journal
reclaim delay turned up a shutdown hang - a lost wakeup, caused because
flushing a journal pin (e.g. key cache/write buffer) can generate a new
journal pin.
The "simple" fix of adding the correct wakeup didn't work because of
ordering issues; if we flush btree node pins too aggressively before
other pins have completed, we end up spinning where each flush iteration
generates new work.
So to fix this correctly:
- The list of flushed journal pins is now broken out by type, so that
we can wait for key cache/write buffer pin flushing to complete
before flushing dirty btree nodes
- A new closure_waitlist is added for bch2_journal_flush_pins; this one
is only used under or when we're taking the journal lock, so it's
pretty cheap to add rigorously correct wakeups to journal_pin_set()
and journal_pin_drop().
Additionally, bch2_journal_seq_pins_to_text() is moved to
journal_reclaim.c, where it belongs, along with a bit of other small
renaming and refactoring.
Besides fixing the hang, the better ordering between key cache/write
buffer flushing and btree node flushing should help or fix the "unmount
taking excessively long" a few users have been noticing.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Tue, 21 Jan 2025 22:42:25 +0000 (17:42 -0500)]
bcachefs: "Journal stuck" timeout now takes into account device latency
If a block device (e.g. your typical consumer SSD) is taking multiple
seconds for IOs (typically flushes), we don't want to emit the "journal
stuck" message prematurely.
Also, make sure to drop the btree_trans srcu lock if we're blocking for
more than a second.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Tue, 21 Jan 2025 07:26:13 +0000 (02:26 -0500)]
bcachefs: Fix btree_trans_peek_key_cache()
BTREE_ITER_cached_nofill has some tricky corner cases; it's used
internally for iterators that aren't walking the key cache, but need to
be coherent with the key cache.
It tells traverse to look up and lock the key cache entry if present,
but don't create one if it doesn't exist.
That means we have to have a BTREE_ITER_UPTODATE path (because after
traverse the path has to be UPTODATE, or we pop assertions) that doesn't
point to anything (which is the less bad option, taken by the previous
fix).
The previous fix for this path missed an issue that can happen in
bch2_trans_peek_key_cache(): we can't set should_be_locked on a path
that doesn't point to anything and doesn't hold locks.
Fixes: bd5b09727f3d ("bcachefs: Don't set btree_path to updtodate if we don't fill") Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Mon, 13 Jan 2025 20:41:50 +0000 (15:41 -0500)]
bcachefs: Document issue with bch_stripe layout
We've got a problem with bch_stripe that is going to take an on disk
format rev to fix - we can't access the block sector counts if the
checksum type is unknown.
Document it for now, there are a few other things to fix as well.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Alan Huang [Wed, 2 Oct 2024 19:06:32 +0000 (03:06 +0800)]
bcachefs: Only abort the transactions in the cycle
When the cycle doesn't involve the initiator of the cycle detection,
we might choose a transaction that is not involved in the cycle to abort.
It shouldn't be that since it won't break the cycle, this patch
therefore chooses the transaction in the cycle to abort.
Signed-off-by: Alan Huang <mmpgouride@gmail.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Alan Huang [Thu, 10 Oct 2024 13:21:50 +0000 (21:21 +0800)]
bcachefs: Do not allow no fail lock request to fail
If the transaction chose itself as a victim before and restarted, it
might request a no fail lock request this time. But it might be added to
others' lock graph and be chose as the victim again, it's no longer safe
without additional check. We can also convert the cycle detector to be
fully RCU-based to solve that unsoundness, but the latency added to trans_put
and additional memory required may not worth it.
Signed-off-by: Alan Huang <mmpgouride@gmail.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Alan Huang [Wed, 25 Sep 2024 16:45:00 +0000 (00:45 +0800)]
bcachefs: Merge the condition to avoid additional invocation
If the lock has been acquired and unlocked, we don't have to do clear
and wakeup again, though harmless since we hold the intent lock. Merge
the condition might be clearer.
Signed-off-by: Alan Huang <mmpgouride@gmail.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This adds another metadata version for accounting directory size.
For the new version of the filesystem, when new subdirectory items
are created or deleted, the parent directory's size will change
accordingly. For the old version of the existed file system, running
fsck will automatically upgrade the metadata version, and it will
do the check and recalculationg of the directory size.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Hongbo Li [Tue, 7 Jan 2025 13:18:40 +0000 (13:18 +0000)]
bcachefs: make directory i_size meaningful
The isize of directory is 0 in bcachefs if the directory is empty.
With more child dirents created, its size ought to change. Many
other filesystems changed as that (ie. xfs and btrfs). And many of
them changed as the size of child dirent name. Although the directory
size may not seem to convey much, we can still give it some meaning.
The formula of dentry size as follow:
occupied_size = 40 + ALIGN(9 + namelen, 8)
Signed-off-by: Hongbo Li <lihongbo22@huawei.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sat, 4 Jan 2025 17:10:25 +0000 (12:10 -0500)]
bcachefs: check_unreachable_inodes is not actually PASS_ONLINE yet
check_unreachable_inodes does work in online mode, with the one caveat
that it assumes check_dirents has also run - and check_dirents is not
PASS_ONLINE yet.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sat, 21 Dec 2024 07:33:53 +0000 (02:33 -0500)]
bcachefs: six locks: write locks can now be held recursively
This is needed for the interior update locking rework, where we'll be
holding node write locks for the duration of the update - which is
needed for synchronizing with online check_allocations.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Fri, 20 Dec 2024 09:46:00 +0000 (04:46 -0500)]
bcachefs: Fixes for snapshot_tree.master_subvol
Ensure that snapshot_tree.master_subvol is cleared when we delete the
master subvolume in a tree of snapshots, and allow for snapshot trees
that don't have a master subvolume in fsck.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sat, 21 Dec 2024 04:56:42 +0000 (23:56 -0500)]
bcachefs: Don't rely on snapshot_tree.master_subvol for reattaching
Previously, fsck used the snapshot tree's master subvol for finding the
root inode number - but the master subvol might have been deleting, and
setting a new one should be a user operation; meaning we can't rely on
it existing.
Fortunately, for finding the root inode number in a tree of snapshots,
finding any associated subvolume works.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Mon, 16 Dec 2024 18:58:02 +0000 (13:58 -0500)]
bcachefs: Handle -BCH_ERR_need_mark_replicas in gc
Locking considerations (possibly no longer relevant?) mean that when an
accounting update needs a new superblock replicas entry to be created,
it's deferred to the transaction commit error path.
But accounting updates for gc/fcsk aren't done from the transaction
commit path - so we need to handle
-BCH_ERR_btree_insert_need_mark_replicas locally.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sun, 15 Dec 2024 07:24:30 +0000 (02:24 -0500)]
bcachefs: kill __bch2_btree_iter_flags()
bch2_btree_iter_flags() now takes a level parameter; this fixes a bug
where using a node iterator on a leaf wouldn't set
BTREE_ITER_with_key_cache, leading to fun cache coherency bugs.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sun, 15 Dec 2024 07:03:11 +0000 (02:03 -0500)]
bcachefs: Drop redundant "read error" call from btree_gc
The btree node read error path already calls topology error, so this is
entirely redundant, and we're not specific enough about our error codes
- this was triggering for bucket_ref_update() errors.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Hongbo Li [Tue, 12 Nov 2024 08:15:47 +0000 (16:15 +0800)]
bcachefs: add counter_flags for counters
In bcachefs, io_read and io_write counter record the amount
of data which has been read and written. They increase in
unit of sector, so to display correctly, they need to be
shifted to the left by the size of a sector. Other counters
like io_move, move_extent_{read, write, finish} also have
this problem.
In order to support different unit, we add extra column to
mark the counter type by using TYPE_COUNTER and TYPE_SECTORS
in BCH_PERSISTENT_COUNTERS().
Fixes: 1c6fdbd8f246 ("bcachefs: Initial commit") Signed-off-by: Hongbo Li <lihongbo22@huawei.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Thu, 3 Aug 2023 00:27:38 +0000 (20:27 -0400)]
bcachefs: bcachefs_metadata_version_inode_depth
This adds a new inode field, bi_depth, for directory inodes: this allows
us to make the check_directory_structure pass much more efficient.
Currently, to ensure the filesystem is fully connect and has no loops,
for every directory we follow backpointers until we find the root. But
by adding a depth counter, it sufficies to only check the parent of each
directory, and check that the parent's bi_depth is smaller.
(fsck doesn't require that bi_depth = parent->bi_depth + 1; if a rename
causes bi_depth off, but the chain to the root is still strictly
decreasing, then the algorithm still works and there's no need for fsck
to fixup the bi_depth fields).
We've already checked backpointers, so we know that every directory
(excluding the root)has a valid parent: if bi_depth is always
decreasing, every chain must terminate, and terminate at the root
directory.
bi_depth will not necessarily be correct when fsck runs, due to
directory renames - we can't change bi_depth on every child directory
when renaming a directory. That's ok; fsck will silently fix the
bi_depth field as needed, and future fsck runs will be much faster.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sun, 20 Oct 2024 06:12:21 +0000 (02:12 -0400)]
bcachefs: Option changes now get propagated to reflinked data
Now that bch2_move_get_io_opts() re-propagates changed inode io options
to bch_extent_rebalance, we can properly suport changing IO path options
for reflinked data.
Changing a per-file IO path option, either via the xattr interface or
via the BCHFS_IOC_REINHERIT_ATTRS ioctl, will now trigger a scan (the
inode number is marked as needing a scan, via
bch2_set_rebalance_needs_scan()), and rebalance will use
bch2_move_data(), which will walk the inode number and pick up the new
options.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Previously, io path option changes on a file would be picked up
automatically and applied to existing data - but not for reflinked data,
as we had no way of doing this safely. A user may have had permission to
copy (and reflink) a given file, but not write to it, and if so they
shouldn't be allowed to change e.g. nr_replicas or other options.
This uses the incompat feature mechanism in the previous patch to add a
new incompatible flag to bch_reflink_p, indicating whether a given
reflink pointer may propagate io path option changes back to the
indirect extent.
In this initial patch we're only setting it for the source extents.
We'd like to set it for the destination in a reflink copy, when the user
has write access to the source, but that requires mnt_idmap which is not
curretly plumbed up to remap_file_range.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Tue, 12 Nov 2024 02:50:29 +0000 (21:50 -0500)]
bcachefs: BCH_SB_VERSION_INCOMPAT
We've been getting away from feature bits: they don't have any kind of
ordering, and thus it's possible for people to enable weird combinations
of features that were never tested or intended to be run.
Much better to just give every new feature, compatible or incompatible,
a version number.
Additionally, we probably won't ever rev the major version number: major
version numbers represent incompatible versions, but that doesn't really
fit with how we actually roll out incompatible features - we need a
better way of rolling out incompatible features.
So, this patch adds two new superblock fields:
- BCH_SB_VERSION_INCOMPAT
- BCH_SB_VERSION_INCOMPAT_ALLOWED
BCH_SB_VERSION_INCOMPAT_ALLOWED indicates that incompatible features up
to version number x are allowed to be used without user prompting, but
it does not by itself deny old versions from mounting.
BCH_SB_VERSION_INCOMPAT does deny old versions from mounting, and must
be <= BCH_SB_VERSION_INCOMPAT_ALLOWED.
BCH_SB_VERSION_INCOMPAT will only be set when a codepath attempts to use
an incompatible feature, so as to not unnecessarily break compatibility
with old versions.
bch2_request_incompat_feature() is the new interface to check if an
incompatible feature may be used.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Fri, 15 Nov 2024 01:47:32 +0000 (20:47 -0500)]
bcachefs: Only run check_backpointers_to_extents in debug mode
The backpointers passes, check_backpointers_to_extents() and
check_extents_to_backpointers() are the most expensive fsck passes.
Now that we're running the same check and repair code when using a
backpointer at runtime (via bch2_backpointer_get_key()) that fsck does,
there's no reason fsck needs to - except to verify that the filesystem
really has no errors in debug mode.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Tue, 12 Nov 2024 08:46:31 +0000 (03:46 -0500)]
bcachefs: bch2_backpointer_get_key() now repairs dangling backpointers
Continuing on with the self healing theme, we should be running any
check and repair code at runtime that we can - instead of declaring the
filesystemt inconsistent.
This will also let us skip running the backpointers -> extents fsck pass
except in debug mode.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Fri, 15 Nov 2024 21:31:54 +0000 (16:31 -0500)]
bcachefs: check_extents_to_backpointers() now only checks buckets with mismatches
Instead of walking every extent and every backpointer it points to,
first sum up backpointers in each bucket and check for mismatches, and
only look for missing backpointers if mismatches were detected, and only
check extents in those buckets.
This is a major fsck scalability improvement, since the two backpointers
passes (backpointers -> extents and extents -> backpointers) are the
most expensive fsck passes by far.
Additionally, to speed up the upgrade for backpointer bucket gens, or in
situations when we have to rebuild alloc info, add a special case for
when no backpointers are found in a bucket - don't check each individual
backpointer (in particular, avoiding the write buffer flushes), just
recreate them.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Fri, 15 Nov 2024 03:13:29 +0000 (22:13 -0500)]
bcachefs: Add write buffer flush param to backpointer_get_key()
In an upcoming patch bch2_backpointer_get_key() will be repairing when
it finds a dangling backpointer; it will need to flush the btree write
buffer before it can definitively say there's an error.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Mon, 18 Nov 2024 04:58:21 +0000 (23:58 -0500)]
bcachefs: bch2_extent_ptr_to_bp() no longer depends on device
bch_backpointer no longer contains the bucket_offset field, it's just a
direct LBA mapping (with low bits to account for compressed extent
splitting), so we don't need to refer to the device to construct it
anymore.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Fix sort order for disk accounting keys, in order to fix a regression on
mount times.
The typetag is now the most significant byte of the key, meaning disk
accounting keys of the same type now sort together.
This lets us skip over disk accounting keys that aren't mirrored in
memory when reading accounting at startup, instead of having them
interleaved with other counter types.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
New on disk format version: backpointers new include the generation
number of the bucket they refer to, and the obsolete bucket_offset field
(no longer needed because we no longer store backpointers in alloc keys)
is gone.
This is an expensive forced upgrade - hopefully the last; we have to run
the extents_to_backpointers recovery pass to regenerate backpointers.
It's a forced incompatible upgrade because the alternative would've been
permamently making backpointers bigger, and as one of the biggest btrees
(along with the extents btree) that's not an ideal option.
It's worth it though, because this allows us to make the
check_extents_to_backpointers pass drastically cheaper: an upcoming
patch changes it to sum up backpointers in a bucket and check the sum
against the sector counts for that bucket, only looking for missing
backpointers if they don't match (and then only for specific buckets).
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Thu, 12 Dec 2024 08:03:58 +0000 (03:03 -0500)]
bcachefs: Snapshot deletion no longer uses snapshot_t->equiv
Switch to generating a private list of interior nodes to delete, instead
of using the equivalence class in the global data structure.
This eliminates possible races with snapshot creation, and is much
cleaner - it'll let us delete a lot of janky code for calculating and
maintaining the equivalence classes.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Thu, 12 Dec 2024 07:41:37 +0000 (02:41 -0500)]
bcachefs: Kill equiv_seen arg to delete_dead_snapshots_process_key()
When deleting dead snapshots, we move keys from redundant interior
snapshot nodes to child nodes - unless there's already a key, in which
case the ancestor key is deleted.
Previously, we tracked via equiv_seen whether the child snapshot had a
key, but this was tricky w.r.t. transaction restarts, and not
transactionally safe w.r.t. updates in the child snapshot.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Thu, 12 Dec 2024 07:32:32 +0000 (02:32 -0500)]
bcachefs: alloc_data_type_set() happens in alloc trigger
Originally, we ran insert triggers before overwrite so that if an extent
was being moved (by fallocate insert/collapse range), the bucket sector
count wouldn't hit 0 partway through, and so we don't trigger state
changes caused by that too soon.
But this is better solved by just moving the data type change to the
alloc trigger itself, where it's already called.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Normally, whitouts (KEY_TYPE_whitout) are filtered from btree lookups,
since they exist only to represent deletions of keys in ancestor
snapshots - except, they should not be filtered in
BTREE_ITER_all_snapshots mode, so that e.g. snapshot deletion can clean
them up.
This means that that the key cache has to store whiteouts, and key cache
fills cannot filter them.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
In BTREE_ITER_all_snapshots mode, we're required to only return keys
where the snapshot field matches the iterator position -
BTREE_ITER_filter_snapshots requires pulling keys into the key cache
from ancestor snapshots, so we have to check for that.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Nathan Chancellor [Tue, 10 Dec 2024 18:12:07 +0000 (11:12 -0700)]
bcachefs: Add empty statement between label and declaration in check_inode_hash_info_matches_root()
Clang 18 and newer warns (or errors with CONFIG_WERROR=y):
fs/bcachefs/str_hash.c:164:2: error: label followed by a declaration is a C23 extension [-Werror,-Wc23-extensions]
164 | struct bch_inode_unpacked inode;
| ^
In Clang 17 and prior, this is an unconditional hard error:
fs/bcachefs/str_hash.c:164:2: error: expected expression
164 | struct bch_inode_unpacked inode;
| ^
fs/bcachefs/str_hash.c:165:30: error: use of undeclared identifier 'inode'
165 | ret = bch2_inode_unpack(k, &inode);
| ^
fs/bcachefs/str_hash.c:169:55: error: use of undeclared identifier 'inode'
169 | struct bch_hash_info hash2 = bch2_hash_info_init(c, &inode);
| ^
fs/bcachefs/str_hash.c:171:40: error: use of undeclared identifier 'inode'
171 | ret = repair_inode_hash_info(trans, &inode);
| ^
Add an empty statement between the label and the declaration to fix the
warning/error without disturbing the code too much.
Fixes: 2519d3b0d656 ("bcachefs: bch2_str_hash_check_key() now checks inode hash info") Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202412092339.QB7hffGC-lkp@intel.com/ Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Mon, 9 Dec 2024 02:47:34 +0000 (21:47 -0500)]
bcachefs: bch2_str_hash_check_key() now checks inode hash info
Versions of the same inode in different snapshots must have the same
hash info; this is critical for lookups to work correctly.
We're going to be running the str_hash checks online, at readdir or
xattr list time, so we now need str_hash_check_key() to check for inode
hash seed mismatches, since it won't be run right after check_inodes().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Mon, 9 Dec 2024 03:00:36 +0000 (22:00 -0500)]
bcachefs: Don't BUG_ON() inode unpack error
Bkey validation checks that inodes are well-formed and unpack
successfully, so an unpack error should always indicate memory
corruption or some other kind of hardware bug - but these are still
errors we can recover from.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sun, 8 Dec 2024 09:11:21 +0000 (04:11 -0500)]
bcachefs: Kill unnecessary mark_lock usage
We can't hold mark_lock while calling fsck_err() - that's a deadlock,
mark_lock is meant to be a leaf node lock.
It's also unnecessary for gc_bucket() and bucket_gen(); rcu suffices
since the bucket_gens array describes its size, and we can't race with
device removal or resize during gc/fsck since that takes state lock.
Reported-by: syzbot+38641fcbda1aaffefdd4@syzkaller.appspotmail.com Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sat, 7 Dec 2024 04:15:05 +0000 (23:15 -0500)]
bcachefs: Fix reuse of bucket before journal flush on multiple empty -> nonempty transition
For each bucket we track when the bucket became nonempty and when it
became empty again: if we can ensure that there will be no journal
flushes in the range [nonempty, empty) (possibly because they occured at
the same journal sequence number), then it's safe to reuse the bucket
without waiting for a journal commit.
This is a major performance optimization for erasure coding, where
writes are initially replicated, but the extra replicas are quickly
dropped: if those buckets are reused and overwritten without issuing a
cache flush to the underlying device, then they only cost bus bandwidth.
But there's a tricky corner case when there's multiple empty -> nonempty
-> empty transitions in quick succession, i.e. when data is getting
overwritten immediately as it's being written.
If this happens and the previous empty transition hasn't been flushed,
we need to continue tracking the previous nonempty transition - not
start a new one.
Fixing this means we now need to track both the nonempty and empty
transitions in bch_alloc_v4.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sun, 8 Dec 2024 05:28:16 +0000 (00:28 -0500)]
bcachefs: bch2_journal_noflush_seq() now takes [start, end)
Harder to screw up if we're explicit about the range, and more correct
as journal reservations can be outstanding on multiple journal entries
simultaneously.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sat, 7 Dec 2024 00:23:22 +0000 (19:23 -0500)]
bcachefs: Use a heap for handling overwrites in btree node scan
Fix an O(n^2) issue when we find many overlapping (overwritten) btree
nodes - especially when one node overwrites many smaller nodes.
This was discovered to be an issue with the bcachefs
merge_torture_flakey test - if we had a large btree that was then
emptied, the number of difficult overwrites can be unbounded.
Cc: Kuan-Wei Chiu <visitorckw@gmail.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Sat, 7 Dec 2024 00:16:02 +0000 (19:16 -0500)]
lib min_heap: Switch to size_t
size_t is the correct type for a count of objects that can fit in
memory: this also means heaps now have the same memory layout as darrays
(fs/bcachefs/darray.h), and darrays can be used as heaps.
Cc: Kuan-Wei Chiu <visitorckw@gmail.com> Cc: Ian Rogers <irogers@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Coly Li <colyli@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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