diff options
| 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/stat.c | |
| parent | b85ea95d086471afb4ad062012a4d73cd328fa86 (diff) | |
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/stat.c')
| -rw-r--r-- | fs/stat.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/stat.c b/fs/stat.c index 24bb0209e459..e44f0625c24f 100644 --- a/fs/stat.c +++ b/fs/stat.c @@ -243,8 +243,13 @@ retry: error = vfs_getattr(&path, stat, request_mask, flags); - stat->mnt_id = real_mount(path.mnt)->mnt_id; - stat->result_mask |= STATX_MNT_ID; + if (request_mask & STATX_MNT_ID_UNIQUE) { + stat->mnt_id = real_mount(path.mnt)->mnt_id_unique; + stat->result_mask |= STATX_MNT_ID_UNIQUE; + } else { + stat->mnt_id = real_mount(path.mnt)->mnt_id; + stat->result_mask |= STATX_MNT_ID; + } if (path.mnt->mnt_root == path.dentry) stat->attributes |= STATX_ATTR_MOUNT_ROOT; |