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[46.135.85.110]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490bc3d663csm631420525e9.11.2026.06.10.07.40.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jun 2026 07:40:05 -0700 (PDT) From: Mateusz Guzik To: brauner@kernel.org Cc: viro@zeniv.linux.org.uk, jack@suse.cz, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, adobriyan@gmail.com, cuiyunhui@bytedance.com, Mateusz Guzik Subject: [PATCH] fs: fix ups and tidy ups to /proc/filesystems caching Date: Wed, 10 Jun 2026 16:39:54 +0200 Message-ID: <20260610143954.34185-1-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit - add missing unlocks in some corner cases - whitespace touch ups - s/smp_store_release/rcu_assign_pointer/ [nop, the macro expands to the same thing] - mark file_systems_string as __read_mostly Signed-off-by: Mateusz Guzik --- Preferably this will get folded into the patch which introduces caching to begin with, I'm posting a "full patch" just in case a separate entry is preferred. fs/filesystems.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/fs/filesystems.c b/fs/filesystems.c index 771fc31a69b8..673a03b5f32b 100644 --- a/fs/filesystems.c +++ b/fs/filesystems.c @@ -54,7 +54,7 @@ struct file_systems_string { }; static unsigned long file_systems_gen; -static struct file_systems_string __rcu *file_systems_string; +static struct file_systems_string __read_mostly __rcu *file_systems_string; static void invalidate_filesystems_string(void); #else @@ -269,7 +269,7 @@ static __cold noinline int regen_filesystems_string(void) hlist_for_each_entry_rcu(p, &file_systems, list) { if (!(p->fs_flags & FS_REQUIRES_DEV)) newlen += strlen("nodev"); - newlen += strlen("\t") + strlen(p->name) + strlen("\n"); + newlen += strlen("\t") + strlen(p->name) + strlen("\n"); } spin_unlock(&file_systems_lock); @@ -289,6 +289,7 @@ static __cold noinline int regen_filesystems_string(void) * Did someone beat us to it? */ if (old && old->gen == file_systems_gen) { + spin_unlock(&file_systems_lock); kfree(new); return 0; } @@ -297,6 +298,7 @@ static __cold noinline int regen_filesystems_string(void) * Did the list change in the meantime? */ if (gen != file_systems_gen) { + spin_unlock(&file_systems_lock); kfree(new); goto retry; } @@ -321,15 +323,11 @@ static __cold noinline int regen_filesystems_string(void) * generation above and messes it up. */ spin_unlock(&file_systems_lock); - if (old) - kfree_rcu(old, rcu); + kfree(new); return -EINVAL; } - /* - * Paired with consume fence in READ_ONCE() in filesystems_proc_show() - */ - smp_store_release(&file_systems_string, new); + rcu_assign_pointer(file_systems_string, new); spin_unlock(&file_systems_lock); if (old) kfree_rcu(old, rcu); -- 2.48.1