diff options
| author | Jeff Layton <jlayton@kernel.org> | 2025-02-06 07:51:52 -0500 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2025-02-12 12:12:28 +0100 |
| commit | 8f6116b5b77b0536d2ad7482ee42bfe58b8fac01 (patch) | |
| tree | f88e3a5804fccacf49ec0f524ccea67f089f54c7 /fs/namespace.c | |
| parent | 312994674eb1748c3c7b07b82935250a980262b7 (diff) | |
statmount: add a new supported_mask field
Some of the fields in the statmount() reply can be optional. If the
kernel has nothing to emit in that field, then it doesn't set the flag
in the reply. This presents a problem: There is currently no way to
know what mask flags the kernel supports since you can't always count on
them being in the reply.
Add a new STATMOUNT_SUPPORTED_MASK flag and field that the kernel can
set in the reply. Userland can use this to determine if the fields it
requires from the kernel are supported. This also gives us a way to
deprecate fields in the future, if that should become necessary.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20250206-statmount-v2-1-6ae70a21c2ab@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index d470a369d42b..c5ada826d488 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -5410,6 +5410,21 @@ static int grab_requested_root(struct mnt_namespace *ns, struct path *root) return 0; } +/* This must be updated whenever a new flag is added */ +#define STATMOUNT_SUPPORTED (STATMOUNT_SB_BASIC | \ + STATMOUNT_MNT_BASIC | \ + STATMOUNT_PROPAGATE_FROM | \ + STATMOUNT_MNT_ROOT | \ + STATMOUNT_MNT_POINT | \ + STATMOUNT_FS_TYPE | \ + STATMOUNT_MNT_NS_ID | \ + STATMOUNT_MNT_OPTS | \ + STATMOUNT_FS_SUBTYPE | \ + STATMOUNT_SB_SOURCE | \ + STATMOUNT_OPT_ARRAY | \ + STATMOUNT_OPT_SEC_ARRAY | \ + STATMOUNT_SUPPORTED_MASK) + static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, struct mnt_namespace *ns) { @@ -5479,9 +5494,17 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, if (!err && s->mask & STATMOUNT_MNT_NS_ID) statmount_mnt_ns_id(s, ns); + if (!err && s->mask & STATMOUNT_SUPPORTED_MASK) { + s->sm.mask |= STATMOUNT_SUPPORTED_MASK; + s->sm.supported_mask = STATMOUNT_SUPPORTED; + } + if (err) return err; + /* Are there bits in the return mask not present in STATMOUNT_SUPPORTED? */ + WARN_ON_ONCE(~STATMOUNT_SUPPORTED & s->sm.mask); + return 0; } |