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fs: record sequence number of origin mount namespace

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Store the sequence number of the mount namespace the anonymous mount
namespace has been created from. This information will be used in
follow-up patches.

Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-1-dbcfcb98c676@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2025-02-21 14:13:00 +01:00
parent 822c115925
commit 3b0cdba4da
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
2 changed files with 18 additions and 2 deletions
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1
fs/mount.h
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@ -20,6 +20,7 @@ struct mnt_namespace {
wait_queue_head_t poll;
struct rcu_head mnt_ns_rcu;
};
u64 seq_origin; /* Sequence number of origin mount namespace */
u64 event;
unsigned int nr_mounts; /* # of mounts in the namespace */
unsigned int pending_mounts;

19
fs/namespace.c
View File

@ -2853,15 +2853,30 @@ static int do_loopback(struct path *path, const char *old_name,
static struct file *open_detached_copy(struct path *path, bool recursive)
{
struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
struct mnt_namespace *ns = alloc_mnt_ns(user_ns, true);
struct mnt_namespace *ns, *mnt_ns = current->nsproxy->mnt_ns, *src_mnt_ns;
struct user_namespace *user_ns = mnt_ns->user_ns;
struct mount *mnt, *p;
struct file *file;
ns = alloc_mnt_ns(user_ns, true);
if (IS_ERR(ns))
return ERR_CAST(ns);
namespace_lock();
/*
* Record the sequence number of the source mount namespace.
* This needs to hold namespace_sem to ensure that the mount
* doesn't get attached.
*/
if (is_mounted(path->mnt)) {
src_mnt_ns = real_mount(path->mnt)->mnt_ns;
if (is_anon_ns(src_mnt_ns))
ns->seq_origin = src_mnt_ns->seq_origin;
else
ns->seq_origin = src_mnt_ns->seq;
}
mnt = __do_loopback(path, recursive);
if (IS_ERR(mnt)) {
namespace_unlock();