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| author | Miklos Szeredi <mszeredi@redhat.com> | 2023-10-25 16:01:59 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2023-11-18 14:56:16 +0100 |
| commit | 98d2b43081972abeb5bb5a087bc3e3197531c46e (patch) | |
| tree | b56d8e448127d642c39b6fad6f14a5166666d3f1 /fs/mount.h | |
| parent | Linux 6.7-rc1 (diff) | |
| download | linux-98d2b43081972abeb5bb5a087bc3e3197531c46e.tar.xz linux-98d2b43081972abeb5bb5a087bc3e3197531c46e.zip | |
add unique mount ID
If a mount is released then its mnt_id can immediately be reused. This is
bad news for user interfaces that want to uniquely identify a mount.
Implementing a unique mount ID is trivial (use a 64bit counter).
Unfortunately userspace assumes 32bit size and would overflow after the
counter reaches 2^32.
Introduce a new 64bit ID alongside the old one. Initialize the counter to
2^32, this guarantees that the old and new IDs are never mixed up.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Link: https://lore.kernel.org/r/20231025140205.3586473-2-mszeredi@redhat.com
Reviewed-by: Ian Kent <raven@themaw.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/mount.h')
| -rw-r--r-- | fs/mount.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/mount.h b/fs/mount.h index 130c07c2f8d2..a14f762b3f29 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -72,7 +72,8 @@ struct mount { struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks; __u32 mnt_fsnotify_mask; #endif - int mnt_id; /* mount identifier */ + int mnt_id; /* mount identifier, reused */ + u64 mnt_id_unique; /* mount ID unique until reboot */ int mnt_group_id; /* peer group identifier */ int mnt_expiry_mark; /* true if marked for expiry */ struct hlist_head mnt_pins; |