diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2025-05-01 20:40:57 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2025-06-29 18:13:42 -0400 |
| commit | ec3265a245b22f8b8a0b20e04dd1d3f4f4a9ce09 (patch) | |
| tree | ba0191e8d8a4e352d6bc97ea2c1b8948762c7836 /fs/namespace.c | |
| parent | a8c764e1a580c2128e905ad6e42beef413fb7177 (diff) | |
| download | random-ec3265a245b22f8b8a0b20e04dd1d3f4f4a9ce09.tar.gz | |
take ->mnt_expire handling under mount_lock [read_seqlock_excl]
Doesn't take much massage, and we no longer need to make sure that
by the time of final mntput() the victim has been removed from the
list. Makes life safer for ->d_automount() instances...
Rules:
* all ->mnt_expire accesses are under mount_lock.
* insertion into the list is done by mnt_set_expiry(), and
caller (->d_automount() instance) must hold a reference to mount
in question. It shouldn't be done more than once for a mount.
* if a mount on an expiry list is not yet mounted, it will
be ignored by anything that walks that list.
* if the final mntput() finds its victim still on an expiry
list (in which case it must've never been mounted - umount_tree()
would've taken it out), it will remove the victim from the list.
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 | 28 |
1 files changed, 11 insertions, 17 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index e8dc8af87548d7..ff2281f780dc59 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1353,13 +1353,6 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, list_add(&mnt->mnt_slave, &old->mnt_slave); mnt->mnt_master = old->mnt_master; } - - /* stick the duplicate mount on the same expiry list - * as the original if that was on one */ - if (flag & CL_EXPIRE) { - if (!list_empty(&old->mnt_expire)) - list_add(&mnt->mnt_expire, &old->mnt_expire); - } return mnt; out_free: @@ -1452,6 +1445,8 @@ static void mntput_no_expire(struct mount *mnt) rcu_read_unlock(); list_del(&mnt->mnt_instance); + if (unlikely(!list_empty(&mnt->mnt_expire))) + list_del(&mnt->mnt_expire); if (unlikely(!list_empty(&mnt->mnt_mounts))) { struct mount *p, *tmp; @@ -2273,6 +2268,13 @@ struct mount *copy_tree(struct mount *src_root, struct dentry *dentry, lock_mount_hash(); if (src_mnt->mnt.mnt_flags & MNT_LOCKED) dst_mnt->mnt.mnt_flags |= MNT_LOCKED; + if (unlikely(flag & CL_EXPIRE)) { + /* stick the duplicate mount on the same expiry + * list as the original if that was on one */ + if (!list_empty(&src_mnt->mnt_expire)) + list_add(&dst_mnt->mnt_expire, + &src_mnt->mnt_expire); + } list_add_tail(&dst_mnt->mnt_list, &res->mnt_list); attach_mnt(dst_mnt, dst_parent, src_parent->mnt_mp); unlock_mount_hash(); @@ -3891,12 +3893,6 @@ discard_locked: namespace_unlock(); inode_unlock(dentry->d_inode); discard: - /* remove m from any expiration list it may be on */ - if (!list_empty(&mnt->mnt_expire)) { - namespace_lock(); - list_del_init(&mnt->mnt_expire); - namespace_unlock(); - } mntput(m); return err; } @@ -3908,11 +3904,9 @@ discard: */ void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) { - namespace_lock(); - + read_seqlock_excl(&mount_lock); list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); - - namespace_unlock(); + read_sequnlock_excl(&mount_lock); } EXPORT_SYMBOL(mnt_set_expiry); |