From: Christian Brauner <brauner@kernel.org>
Date: Fri, 19 Jul 2024 11:41:48 +0000 (+0200)
Subject: fs: use all available ids
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=8eac5358ad3bbc007156a0f9ea5637ee7ae421b5;p=linux.git

fs: use all available ids

The counter is unconditionally incremented for each mount allocation.
If we set it to 1ULL << 32 we're losing 4294967296 as the first valid
non-32 bit mount id.

Link: https://lore.kernel.org/r/20240719-work-mount-namespace-v1-1-834113cab0d2@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
---

diff --git a/fs/namespace.c b/fs/namespace.c
index 221db9de4729..328087a4df8a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -70,7 +70,7 @@ static DEFINE_IDA(mnt_id_ida);
 static DEFINE_IDA(mnt_group_ida);
 
 /* Don't allow confusion with old 32bit mount ID */
-#define MNT_UNIQUE_ID_OFFSET (1ULL << 32)
+#define MNT_UNIQUE_ID_OFFSET (1ULL << 31)
 static atomic64_t mnt_id_ctr = ATOMIC64_INIT(MNT_UNIQUE_ID_OFFSET);
 
 static struct hlist_head *mount_hashtable __ro_after_init;