linux-toradex.git/fs/bcachefs/six.c, branch v6.17

bcachefs: Replace rcu_read_lock() with guards

2025-06-01T04:03:12+00:00

The new guard(), scoped_guard() allow for more natural code.

Some of the uses with creative flow control have been left.

Signed-off-by: Kent Overstreet

bcachefs: Fix deadlock

2025-02-27T00:31:05+00:00

This fixes two deadlocks:

1.pcpu_alloc_mutex involved one as pointed by syzbot[1]
2.recursion deadlock.

The root cause is that we hold the bc lock during alloc_percpu, fix it
by following the pattern used by __btree_node_mem_alloc().

[1] https://lore.kernel.org/all/66f97d9a.050a0220.6bad9.001d.GAE@google.com/T/

Reported-by: syzbot+fe63f377148a6371a9db@syzkaller.appspotmail.com
Tested-by: syzbot+fe63f377148a6371a9db@syzkaller.appspotmail.com
Signed-off-by: Alan Huang 
Signed-off-by: Kent Overstreet

bcachefs: Merge the condition to avoid additional invocation

2025-01-14T15:45:08+00:00

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 
Signed-off-by: Kent Overstreet

bcachefs: six locks: write locks can now be held recursively

2025-01-10T04:38:41+00:00

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

Merge tag 'bcachefs-2024-09-28' of git://evilpiepirate.org/bcachefs

2024-09-29T16:17:44+00:00

Pull more bcachefs updates from Kent Overstreet:
 "Assorted minor syzbot fixes, and for bigger stuff:

  Fix two disk accounting rewrite bugs:

   - Disk accounting keys use the version field of bkey so that journal
     replay can tell which updates have been applied to the btree.

     This is set in the transaction commit path, after we've gotten our
     journal reservation (and our time ordering), but the
     BCH_TRANS_COMMIT_skip_accounting_apply flag that journal replay
     uses was incorrectly skipping this for new updates generated prior
     to journal replay.

     This fixes the underlying cause of an assertion pop in
     disk_accounting_read.

   - A couple of fixes for disk accounting + device removal.

     Checking if acocunting replicas entries were marked in the
     superblock was being done at the wrong point, when deltas in the
     journal could still zero them out, and then additionally we'd try
     to add a missing replicas entry to the superblock without checking
     if it referred to an invalid (removed) device.

  A whole slew of repair fixes:

   - fix infinite loop in propagate_key_to_snapshot_leaves(), this fixes
     an infinite loop when repairing a filesystem with many snapshots

   - fix incorrect transaction restart handling leading to occasional
     "fsck counted ..." warnings

   - fix warning in __bch2_fsck_err() for bkey fsck errors

   - check_inode() in fsck now correctly checks if the filesystem was
     clean

   - there shouldn't be pending logged ops if the fs was clean, we now
     check for this

   - remove_backpointer() doesn't remove a dirent that doesn't actually
     point to the inode

   - many more fsck errors are AUTOFIX"

* tag 'bcachefs-2024-09-28' of git://evilpiepirate.org/bcachefs: (35 commits)
  bcachefs: check_subvol_path() now prints subvol root inode
  bcachefs: remove_backpointer() now checks if dirent points to inode
  bcachefs: dirent_points_to_inode() now warns on mismatch
  bcachefs: Fix lost wake up
  bcachefs: Check for logged ops when clean
  bcachefs: BCH_FS_clean_recovery
  bcachefs: Convert disk accounting BUG_ON() to WARN_ON()
  bcachefs: Fix BCH_TRANS_COMMIT_skip_accounting_apply
  bcachefs: Check for accounting keys with bversion=0
  bcachefs: rename version -> bversion
  bcachefs: Don't delete unlinked inodes before logged op resume
  bcachefs: Fix BCH_SB_ERRS() so we can reorder
  bcachefs: Fix fsck warnings from bkey validation
  bcachefs: Move transaction commit path validation to as late as possible
  bcachefs: Fix disk accounting attempting to mark invalid replicas entry
  bcachefs: Fix unlocked access to c->disk_sb.sb in bch2_replicas_entry_validate()
  bcachefs: Fix accounting read + device removal
  bcachefs: bch_accounting_mode
  bcachefs: fix transaction restart handling in check_extents(), check_dirents()
  bcachefs: kill inode_walker_entry.seen_this_pos
  ...

bcachefs: Fix lost wake up

2024-09-28T02:32:23+00:00

If the reader acquires the read lock and then the writer enters the slow
path, while the reader proceeds to the unlock path, the following scenario
can occur without the change:

writer: pcpu_read_count(lock) return 1 (so __do_six_trylock will return 0)
reader: this_cpu_dec(*lock->readers)
reader: smp_mb()
reader: state = atomic_read(&lock->state) (there is no waiting flag set)
writer: six_set_bitmask()

then the writer will sleep forever.

Signed-off-by: Alan Huang 
Signed-off-by: Kent Overstreet

sched/rt: Rename realtime_{prio, task}() to rt_or_dl_{prio, task}()

2024-08-07T16:32:38+00:00

Some find the name realtime overloaded. Use rt_or_dl() as an
alternative, hopefully better, name.

Suggested-by: Daniel Bristot de Oliveira 
Signed-off-by: Qais Yousef 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20240610192018.1567075-4-qyousef@layalina.io

sched/rt: Clean up usage of rt_task()

2024-08-07T16:32:37+00:00

rt_task() checks if a task has RT priority. But depends on your
dictionary, this could mean it belongs to RT class, or is a 'realtime'
task, which includes RT and DL classes.

Since this has caused some confusion already on discussion [1], it
seemed a clean up is due.

I define the usage of rt_task() to be tasks that belong to RT class.
Make sure that it returns true only for RT class and audit the users and
replace the ones required the old behavior with the new realtime_task()
which returns true for RT and DL classes. Introduce similar
realtime_prio() to create similar distinction to rt_prio() and update
the users that required the old behavior to use the new function.

Move MAX_DL_PRIO to prio.h so it can be used in the new definitions.

Document the functions to make it more obvious what is the difference
between them. PI-boosted tasks is a factor that must be taken into
account when choosing which function to use.

Rename task_is_realtime() to realtime_task_policy() as the old name is
confusing against the new realtime_task().

No functional changes were intended.

[1] https://lore.kernel.org/lkml/20240506100509.GL40213@noisy.programming.kicks-ass.net/

Signed-off-by: Qais Yousef 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Phil Auld 
Reviewed-by: "Steven Rostedt (Google)" 
Reviewed-by: Sebastian Andrzej Siewior 
Link: https://lore.kernel.org/r/20240610192018.1567075-2-qyousef@layalina.io

bcachefs: six locks: Simplify optimistic spinning

2024-01-01T16:47:38+00:00

osq lock maintainers don't want it to be used outside of kernel/locking/
- but, we can do better.

Since we have lock handoff signalled via waitlist entries, there's no
reason for optimistic spinning to have to look at the lock at all -
aside from checking lock-owner; we can just spin looking at our waitlist
entry.

Signed-off-by: Kent Overstreet

bcachefs: six locks: Fix lost wakeup

2023-11-15T04:44:44+00:00

In percpu reader mode, trylock() for read had a lost wakeup: on failure
to get the lock, we may have caused a writer to fail to get the lock,
because we temporarily elevated the reader count.

We need to check for waiters after decrementing the read count - not
before.

Signed-off-by: Kent Overstreet