rcu_pending, btree key cache rework: this solves lock contenting in the
key cache, eliminating the biggest source of the srcu lock hold time
warnings, and drastically improving performance on some metadata heavy
workloads - on multithreaded creates we're now 3-4x faster than xfs.
We're now using an rhashtable instead of the system inode hash table;
this is another significant performance improvement on multithreaded
metadata workloads, eliminating more lock contention.
for_each_btree_key_in_subvolume_upto(): new helper for iterating over
keys within a specific subvolume, eliminating a lot of open coded
"subvolume_get_snapshot()" and also fixing another source of srcu lock
time warnings, by running each loop iteration in its own transaction (as
the existing for_each_btree_key() does).
More work on btree_trans locking asserts; we now assert that we don't
hold btree node locks when trans->locked is false, which is important
because we don't use lockdep for tracking individual btree node locks.
Some cleanups and improvements in the bset.c btree node lookup code,
from Alan.
Rework of btree node pinning, which we use in backpointers fsck. The old
hacky implementation, where the shrinker just skipped over nodes in the
pinned range, was causing OOMs; instead we now use another shrinker with
a much higher seeks number for pinned nodes.
Rebalance now uses BCH_WRITE_ONLY_SPECIFIED_DEVS; this fixes an issue
where rebalance would sometimes fall back to allocating from the full
filesystem, which is not what we want when it's trying to move data to a
specific target.
Use __GFP_ACCOUNT, GFP_RECLAIMABLE for btree node, key cache
allocations.
Idmap mounts are now supported - Hongbo.
Rename whiteouts are now supported - Hongbo.
Erasure coding can now handle devices being marked as failed, or
forcibly removed. We still need the evacuate path for erasure coding,
but it's getting very close to ready for people to start using.
Status, and when will we be taking off experimental:
----------------------------------------------------
Going by critical, user facing bugs getting found and fixed, we're
nearly there. There are a couple key items that need to be finished
before we can take off the experimental label:
- The end-user experience is still pretty painful when the root
filesystem needs a fsck; we need some form of limited self healing so
that necessary repair gets run automatically. Errors (by type) are
recorded in the superblock, so what we need to do next is convert
remaining inconsistent() errors to fsck() errors (so that all runtime
inconsistencies are logged in the superblock), and we need to go
through the list of fsck errors and classify them by which fsck passes
are needed to repair them.
- We need comprehensive torture testing for all our repair paths, to
shake out remaining bugs there. Thomas has been working on the tooling
for this, so this is coming soonish.
Slightly less critical items:
- We need to improve the end-user experience for degraded mounts: right
now, a degraded root filesystem means dropping to an initramfs shell
or somehow inputting mount options manually (we don't want to allow
degraded mounts without some form of user input, except on unattended
servers) - we need the mount helper to prompt the user to allow
mounting degraded, and make sure this works with systemd.
- Scalabiity: we have users running 100TB+ filesystems, and that's
effectively the limit right now due to fsck times. We have some
reworks in the pipeline to address this, we're aiming to make petabyte
sized filesystems practical.
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Merge tag 'bcachefs-2024-09-21' of git://evilpiepirate.org/bcachefs
Pull bcachefs updates from Kent Overstreet:
- rcu_pending, btree key cache rework: this solves lock contenting in
the key cache, eliminating the biggest source of the srcu lock hold
time warnings, and drastically improving performance on some metadata
heavy workloads - on multithreaded creates we're now 3-4x faster than
xfs.
- We're now using an rhashtable instead of the system inode hash table;
this is another significant performance improvement on multithreaded
metadata workloads, eliminating more lock contention.
- for_each_btree_key_in_subvolume_upto(): new helper for iterating over
keys within a specific subvolume, eliminating a lot of open coded
"subvolume_get_snapshot()" and also fixing another source of srcu
lock time warnings, by running each loop iteration in its own
transaction (as the existing for_each_btree_key() does).
- More work on btree_trans locking asserts; we now assert that we don't
hold btree node locks when trans->locked is false, which is important
because we don't use lockdep for tracking individual btree node
locks.
- Some cleanups and improvements in the bset.c btree node lookup code,
from Alan.
- Rework of btree node pinning, which we use in backpointers fsck. The
old hacky implementation, where the shrinker just skipped over nodes
in the pinned range, was causing OOMs; instead we now use another
shrinker with a much higher seeks number for pinned nodes.
- Rebalance now uses BCH_WRITE_ONLY_SPECIFIED_DEVS; this fixes an issue
where rebalance would sometimes fall back to allocating from the full
filesystem, which is not what we want when it's trying to move data
to a specific target.
- Use __GFP_ACCOUNT, GFP_RECLAIMABLE for btree node, key cache
allocations.
- Idmap mounts are now supported (Hongbo Li)
- Rename whiteouts are now supported (Hongbo Li)
- Erasure coding can now handle devices being marked as failed, or
forcibly removed. We still need the evacuate path for erasure coding,
but it's getting very close to ready for people to start using.
* tag 'bcachefs-2024-09-21' of git://evilpiepirate.org/bcachefs: (99 commits)
bcachefs: return err ptr instead of null in read sb clean
bcachefs: Remove duplicated include in backpointers.c
bcachefs: Don't drop devices with stripe pointers
bcachefs: bch2_ec_stripe_head_get() now checks for change in rw devices
bcachefs: bch_fs.rw_devs_change_count
bcachefs: bch2_dev_remove_stripes()
bcachefs: bch2_trigger_ptr() calculates sectors even when no device
bcachefs: improve error messages in bch2_ec_read_extent()
bcachefs: improve error message on too few devices for ec
bcachefs: improve bch2_new_stripe_to_text()
bcachefs: ec_stripe_head.nr_created
bcachefs: bch_stripe.disk_label
bcachefs: stripe_to_mem()
bcachefs: EIO errcode cleanup
bcachefs: Rework btree node pinning
bcachefs: split up btree cache counters for live, freeable
bcachefs: btree cache counters should be size_t
bcachefs: Don't count "skipped access bit" as touched in btree cache scan
bcachefs: Failed devices no longer require mounting in degraded mode
bcachefs: bch2_dev_rcu_noerror()
...
b3f391fddf