From 936a6444d62856003f17e8ea857e2817d4582ae0 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Thu, 10 Jun 2021 23:33:27 -0400 Subject: bcachefs: Don't underflow c->sectors_available This rarely used error path should've been checking for underflow - oops. Signed-off-by: Kent Overstreet --- fs/bcachefs/buckets.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c index 6d5fe398007a..84f280b8525c 100644 --- a/fs/bcachefs/buckets.c +++ b/fs/bcachefs/buckets.c @@ -1433,7 +1433,14 @@ void bch2_trans_fs_usage_apply(struct btree_trans *trans, */ should_not_have_added = added - (s64) disk_res_sectors; if (unlikely(should_not_have_added > 0)) { - atomic64_sub(should_not_have_added, &c->sectors_available); + u64 old, new, v = atomic64_read(&c->sectors_available); + + do { + old = v; + new = max_t(s64, 0, old - should_not_have_added); + } while ((v = atomic64_cmpxchg(&c->sectors_available, + old, new)) != old); + added -= should_not_have_added; warn = true; } -- cgit v1.2.3