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From: Josef Bacik <>
Cc: Nikolay Borisov <>
Subject: [PATCH v5 3/8] btrfs: delayed refs pre-flushing should only run the heads we have
Date: Fri, 18 Dec 2020 14:24:21 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Previously our delayed ref running used the total number of items as the
items to run.  However we changed that to number of heads to run with
the delayed_refs_rsv, as generally we want to run all of the operations
for one bytenr.

But with btrfs_run_delayed_refs(trans, 0) we set our count to 2x the
number of items that we have.  This is generally fine, but if we have
some operation generation loads of delayed refs while we're doing this
pre-flushing in the transaction commit, we'll just spin forever doing
delayed refs.

Fix this to simply pick the number of delayed refs we currently have,
that way we do not end up doing a lot of extra work that's being
generated in other threads.

Signed-off-by: Josef Bacik <>
Reviewed-by: Nikolay Borisov <>
 fs/btrfs/extent-tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index d79b8369e6aa..b6d774803a2c 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2160,7 +2160,7 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
 	delayed_refs = &trans->transaction->delayed_refs;
 	if (count == 0)
-		count = atomic_read(&delayed_refs->num_entries) * 2;
+		count = delayed_refs->num_heads_ready;

  parent reply	other threads:[~2020-12-18 19:25 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-18 19:24 [PATCH v5 0/8] A variety of lock contention fixes Josef Bacik
2020-12-18 19:24 ` [PATCH v5 1/8] btrfs: do not block on deleted bgs mutex in the cleaner Josef Bacik
2020-12-18 19:24 ` [PATCH v5 2/8] btrfs: only let one thread pre-flush delayed refs in commit Josef Bacik
2021-01-08 16:01   ` David Sterba
2021-01-11  8:33     ` Nikolay Borisov
2021-01-11 21:50       ` David Sterba
2021-01-12  9:17         ` Nikolay Borisov
2021-01-26 17:36           ` David Sterba
2020-12-18 19:24 ` Josef Bacik [this message]
2020-12-18 19:24 ` [PATCH v5 4/8] btrfs: only run delayed refs once before committing Josef Bacik
2020-12-18 19:24 ` [PATCH v5 5/8] btrfs: move delayed ref flushing for qgroup into qgroup helper Josef Bacik
2020-12-18 19:24 ` [PATCH v5 6/8] btrfs: remove bogus BUG_ON in alloc_reserved_tree_block Josef Bacik
2020-12-18 19:24 ` [PATCH v5 7/8] btrfs: stop running all delayed refs during snapshot Josef Bacik
2020-12-18 19:24 ` [PATCH v5 8/8] btrfs: run delayed refs less often in commit_cowonly_roots Josef Bacik
2021-01-26 17:51 ` [PATCH v5 0/8] A variety of lock contention fixes David Sterba

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