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fs: use boolean to indicate anonymous mount namespace 

Stop playing games with the namespace id and use a boolean instead:

* This will remove the special-casing we need to do everywhere for mount
  namespaces.

* It will allow us to use asserts on the namespace id for initial
  namespaces everywhere.

* It will allow us to put anonymous mount namespaces on the namespaces
  trees in the future and thus make them available to statmount() and
  listmount().

Link: https://patch.msgid.link/20251110-work-namespace-nstree-fixes-v1-10-e8a9264e0fb9@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2025-11-10 16:08:22 +01:00
parent 6bf253855a
commit d9a44089ac
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GPG Key ID: 91C61BC06578DCA2
2 changed files with 5 additions and 3 deletions
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3
fs/mount.h
View File

@ -27,6 +27,7 @@ struct mnt_namespace {
unsigned int nr_mounts; /* # of mounts in the namespace */ unsigned int nr_mounts; /* # of mounts in the namespace */
unsigned int pending_mounts; unsigned int pending_mounts;
refcount_t passive; /* number references not pinning @mounts */ refcount_t passive; /* number references not pinning @mounts */
bool is_anon;
} __randomize_layout; } __randomize_layout;
struct mnt_pcp { struct mnt_pcp {
@ -175,7 +176,7 @@ static inline bool is_local_mountpoint(const struct dentry *dentry)
static inline bool is_anon_ns(struct mnt_namespace *ns) static inline bool is_anon_ns(struct mnt_namespace *ns)
{ {
return ns->ns.ns_id == 0; return ns->is_anon;
} }
static inline bool anon_ns_root(const struct mount *m) static inline bool anon_ns_root(const struct mount *m)

5
fs/namespace.c
View File

@ -4093,8 +4093,9 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool a
dec_mnt_namespaces(ucounts); dec_mnt_namespaces(ucounts);
return ERR_PTR(ret); return ERR_PTR(ret);
} }
if (!anon) ns_tree_gen_id(new_ns);
ns_tree_gen_id(new_ns);
new_ns->is_anon = anon;
refcount_set(&new_ns->passive, 1); refcount_set(&new_ns->passive, 1);
new_ns->mounts = RB_ROOT; new_ns->mounts = RB_ROOT;
init_waitqueue_head(&new_ns->poll); init_waitqueue_head(&new_ns->poll);