This is part of a larger series cleaning up the semantics of
should_be_locked and adding assertions around it; if we don't need an
iterator/path anymore, it clearly doesn't need to be locked.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
drop_locks_do() should not be used in a fastpath without first trying
the do in nonblocking mode - the unlock and relock will cause excessive
transaction restarts and potentially livelocking with other threads that
are contending for the same locks.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
XXX: we're allocating memory with btree locks held - bad
We need to plumb through an error path so we can do
allocate_dropping_locks() - but we're merging this now because it fixes
a transaction path overflow caused by indirect extent fragmentation, and
the resize path is rare.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Start to plumb through dynamically growable btree_paths; this patch
replaces most BTREE_ITER_MAX references with trans->nr_paths.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Upcoming patches are going to be changing trans->paths to a
reallocatable buffer. We need to guard against use after free when it's
used by other threads; this introduces RCU protection to those paths and
changes them to check for trans->paths == NULL
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
path->idx is now a code smell: we should be using path_idx_t, since it's
stable across btree path reallocation.
This is also a bit faster, using the same loop counter vs. fetching
path->idx from each path we iterate over.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
In the future we'll be making trans->paths resizable and potentially
having _many_ more paths (for fsck); we need to start fixing algorithms
that walk each path in a transaction where possible.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
for_each_btree_key() handles transaction restarts, like
for_each_btree_key2(), but only calls bch2_trans_begin() after a
transaction restart - for_each_btree_key2() wraps every loop iteration
in a transaction.
The for_each_btree_key() behaviour is problematic when it leads to
holding the SRCU lock that prevents key cache reclaim for an unbounded
amount of time - there's no real need to keep it around.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
For BTREE_ITER_WITH_JOURNAL, we memoize lookups in the journal keys, to
avoid the binary search overhead.
Previously we stashed the pos of the last key returned from the journal,
in order to force the lookup to be redone when rewinding.
Now bch2_journal_keys_peek_upto() handles rewinding itself when
necessary - so we can slim down btree_iter.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
As discussed in the previous patch, BTREE_ITER_ALL_LEVELS appears to be
racy with concurrent interior node updates - and perhaps it is fixable,
but it's tricky and unnecessary.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
When bch2_fs_alloc() gets an error before calling
bch2_fs_btree_iter_init(), bch2_fs_btree_iter_exit() makes an invalid
memory access because btree_trans_list is uninitialized.
Signed-off-by: Thomas Bertschinger <tahbertschinger@gmail.com>
Fixes: 6bd68ec266 ("bcachefs: Heap allocate btree_trans")
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
BTREE_INSERT_NOJOURNAL is primarily used for a performance optimization
related to inode updates and fsync - document it.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
rebalance_work entries may refer to entries in the extents btree, which
is a snapshots btree, or they may also refer to entries in the reflink
btree, which is not.
Hence rebalance_work keys may use the snapshot field but it's not
required to be nonzero - add a new btree flag to reflect this.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
The SRCU read lock that btree_trans takes exists to make it safe for
bch2_trans_relock() to deref pointers to btree nodes/key cache items we
don't have locked, but as a side effect it blocks reclaim from freeing
those items.
Thus, it's important to not hold it for too long: we need to
differentiate between bch2_trans_unlock() calls that will be only for a
short duration, and ones that will be for an unbounded duration.
This introduces bch2_trans_unlock_long(), to be used mainly by the data
move paths.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
More forwards compatibility fixups: having BKEY_TYPE_btree at the end of
the enum conflicts with unnkown btree IDs, this shifts BKEY_TYPE_btree
to slot 0 and fixes things up accordingly.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
We're using more stack than we'd like in a number of functions, and
btree_trans is the biggest object that we stack allocate.
But we have to do a heap allocatation to initialize it anyways, so
there's no real downside to heap allocating the entire thing.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
When we handle a transaction restart in a nested context, we need to
return -BCH_ERR_transaction_restart_nested because we invalidated the
outer context's iterators and locks.
bch2_propagate_key_to_snapshot_leaves() wasn't doing this, this patch
fixes it to use trans_was_restarted().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This extents KEY_TYPE_snapshot to include some new fields:
- depth, to indicate depth of this particular node from the root
- skip[3], skiplist entries for quickly walking back up to the root
These are to improve bch2_snapshot_is_ancestor(), making it O(ln(n))
instead of O(n) in the snapshot tree depth.
Skiplist nodes are picked at random from the set of ancestor nodes, not
some fixed fraction.
This introduces bcachefs_metadata_version 1.1, snapshot_skiplists.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
- endianness fixes
- mark some things static
- fix a few __percpu annotations
- fix silent enum conversions
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Add two new helpers for allocating memory with btree locks held: The
idea is to first try the allocation with GFP_NOWAIT|__GFP_NOWARN, then
if that fails - unlock, retry with GFP_KERNEL, and then call
trans_relock().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Add a new helper for the common pattern of:
- trans_unlock()
- do something
- trans_relock()
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet