From 57f2d2097603fea102330e8cfe6be4a8db24809e Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Wed, 10 Jan 2024 23:47:04 -0500
Subject: [PATCH] bcachefs: Reduce would_deadlock restarts
We don't have to take locks in any particular ordering - we'll make
forward progress just fine - but if we try to stick to an ordering, it
can help to avoid excessive would_deadlock transaction restarts.
This tweaks the reflink path to take extents btree locks in the right
order.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
fs/bcachefs/reflink.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/fs/bcachefs/reflink.c b/fs/bcachefs/reflink.c
index 6070109174210..98255aa64e226 100644
--- a/fs/bcachefs/reflink.c
+++ b/fs/bcachefs/reflink.c
@@ -486,6 +486,13 @@ s64 bch2_remap_range(struct bch_fs *c,
bch2_btree_iter_set_snapshot(&dst_iter, dst_snapshot);
+ if (dst_inum.inum < src_inum.inum) {
+ /* Avoid some lock cycle transaction restarts */
+ ret = bch2_btree_iter_traverse(&dst_iter);
+ if (ret)
+ continue;
+ }
+
dst_done = dst_iter.pos.offset - dst_start.offset;
src_want = POS(src_start.inode, src_start.offset + dst_done);
bch2_btree_iter_set_pos(&src_iter, src_want);
--
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