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| author | Al Viro <viro@zeniv.linux.org.uk> | 2025-08-20 20:28:35 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2025-09-02 19:35:57 -0400 |
| commit | 6b448d7a7c4848fd6cbe0eee49834df7d25b25f8 (patch) | |
| tree | 7d8e60f6b968573fe50ff96f2456020f224b0a93 /fs/namespace.c | |
| parent | 747e91e5b7396eba699989072c61e8fb076bbea4 (diff) | |
| download | random-6b448d7a7c4848fd6cbe0eee49834df7d25b25f8.tar.gz | |
check_for_nsfs_mounts(): no need to take locks
Currently we are taking mount_writer; what that function needs is
either mount_locked_reader (we are not changing anything, we just
want to iterate through the subtree) or namespace_shared and
a reference held by caller on the root of subtree - that's also
enough to stabilize the topology.
The thing is, all callers are already holding at least namespace_shared
as well as a reference to the root of subtree.
Let's make the callers provide locking warranties - don't mess with
mount_lock in check_for_nsfs_mounts() itself and document the locking
requirements.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 16 |
1 files changed, 5 insertions, 11 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index a5d37b97088f5f..59948cbf9c47f7 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2402,21 +2402,15 @@ bool has_locked_children(struct mount *mnt, struct dentry *dentry) * specified subtree. Such references can act as pins for mount namespaces * that aren't checked by the mount-cycle checking code, thereby allowing * cycles to be made. + * + * locks: mount_locked_reader || namespace_shared && pinned(subtree) */ static bool check_for_nsfs_mounts(struct mount *subtree) { - struct mount *p; - bool ret = false; - - lock_mount_hash(); - for (p = subtree; p; p = next_mnt(p, subtree)) + for (struct mount *p = subtree; p; p = next_mnt(p, subtree)) if (mnt_ns_loop(p->mnt.mnt_root)) - goto out; - - ret = true; -out: - unlock_mount_hash(); - return ret; + return false; + return true; } /** |