From: Alan Huang <mmpgouride@gmail.com>
Date: Tue, 18 Mar 2025 07:50:00 +0000 (+0800)
Subject: bcachefs: Add missing smp_rmb()
X-Git-Tag: v6.15-rc1~146^2~21
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5d361ae5afeef075264b369c413dbed0a0d04cfa;p=thirdparty%2Flinux.git

bcachefs: Add missing smp_rmb()

The smp_rmb() guarantees that reads from reservations.counter
occur before accessing cur_entry_u64s. It's paired with the
atomic64_try_cmpxchg in journal_entry_open.

Signed-off-by: Alan Huang <mmpgouride@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---

diff --git a/fs/bcachefs/journal.h b/fs/bcachefs/journal.h
index ab68c5c4d8d8c..47828771f9c23 100644
--- a/fs/bcachefs/journal.h
+++ b/fs/bcachefs/journal.h
@@ -350,8 +350,10 @@ static inline int journal_res_get_fast(struct journal *j,
 
 		/*
 		 * Check if there is still room in the current journal
-		 * entry:
+		 * entry, smp_rmb() guarantees that reads from reservations.counter
+		 * occur before accessing cur_entry_u64s:
 		 */
+		smp_rmb();
 		if (new.cur_entry_offset + res->u64s > j->cur_entry_u64s)
 			return 0;