diff options
| -rw-r--r-- | fs/mount.h | 1 | ||||
| -rw-r--r-- | fs/namespace.c | 52 |
2 files changed, 25 insertions, 28 deletions
diff --git a/fs/mount.h b/fs/mount.h index 6250de544760..84aa8cdf4971 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -69,7 +69,6 @@ struct mount { int mnt_expiry_mark; /* true if marked for expiry */ struct hlist_head mnt_pins; struct fs_pin mnt_umount; - struct dentry *mnt_ex_mountpoint; } __randomize_layout; #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */ diff --git a/fs/namespace.c b/fs/namespace.c index b7059a4f07e3..e0902fda6f07 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -69,6 +69,8 @@ static struct hlist_head *mount_hashtable __read_mostly; static struct hlist_head *mountpoint_hashtable __read_mostly; static struct kmem_cache *mnt_cache __read_mostly; static DECLARE_RWSEM(namespace_sem); +static HLIST_HEAD(unmounted); /* protected by namespace_sem */ +static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */ /* /sys/fs */ struct kobject *fs_kobj; @@ -172,7 +174,6 @@ unsigned int mnt_get_count(struct mount *mnt) static void drop_mountpoint(struct fs_pin *p) { struct mount *m = container_of(p, struct mount, mnt_umount); - dput(m->mnt_ex_mountpoint); pin_remove(p); mntput(&m->mnt); } @@ -739,7 +740,7 @@ mountpoint: /* Add the new mountpoint to the hash table */ read_seqlock_excl(&mount_lock); - new->m_dentry = dentry; + new->m_dentry = dget(dentry); new->m_count = 1; hlist_add_head(&new->m_hash, mp_hash(dentry)); INIT_HLIST_HEAD(&new->m_list); @@ -752,7 +753,11 @@ done: return mp; } -static void put_mountpoint(struct mountpoint *mp) +/* + * vfsmount lock must be held. Additionally, the caller is responsible + * for serializing calls for given disposal list. + */ +static void __put_mountpoint(struct mountpoint *mp, struct list_head *list) { if (!--mp->m_count) { struct dentry *dentry = mp->m_dentry; @@ -760,11 +765,18 @@ static void put_mountpoint(struct mountpoint *mp) spin_lock(&dentry->d_lock); dentry->d_flags &= ~DCACHE_MOUNTED; spin_unlock(&dentry->d_lock); + dput_to_list(dentry, list); hlist_del(&mp->m_hash); kfree(mp); } } +/* called with namespace_lock and vfsmount lock */ +static void put_mountpoint(struct mountpoint *mp) +{ + __put_mountpoint(mp, &ex_mountpoints); +} + static inline int check_mnt(struct mount *mnt) { return mnt->mnt_ns == current->nsproxy->mnt_ns; @@ -813,7 +825,7 @@ static struct mountpoint *unhash_mnt(struct mount *mnt) */ static void detach_mnt(struct mount *mnt, struct path *old_path) { - old_path->dentry = mnt->mnt_mountpoint; + old_path->dentry = dget(mnt->mnt_mountpoint); old_path->mnt = &mnt->mnt_parent->mnt; put_mountpoint(unhash_mnt(mnt)); } @@ -823,8 +835,6 @@ static void detach_mnt(struct mount *mnt, struct path *old_path) */ static void umount_mnt(struct mount *mnt) { - /* old mountpoint will be dropped when we can do that */ - mnt->mnt_ex_mountpoint = mnt->mnt_mountpoint; put_mountpoint(unhash_mnt(mnt)); } @@ -837,7 +847,7 @@ void mnt_set_mountpoint(struct mount *mnt, { mp->m_count++; mnt_add_count(mnt, 1); /* essentially, that's mntget */ - child_mnt->mnt_mountpoint = dget(mp->m_dentry); + child_mnt->mnt_mountpoint = mp->m_dentry; child_mnt->mnt_parent = mnt; child_mnt->mnt_mp = mp; hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list); @@ -864,7 +874,6 @@ static void attach_mnt(struct mount *mnt, void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt) { struct mountpoint *old_mp = mnt->mnt_mp; - struct dentry *old_mountpoint = mnt->mnt_mountpoint; struct mount *old_parent = mnt->mnt_parent; list_del_init(&mnt->mnt_child); @@ -874,22 +883,6 @@ void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct m attach_mnt(mnt, parent, mp); put_mountpoint(old_mp); - - /* - * Safely avoid even the suggestion this code might sleep or - * lock the mount hash by taking advantage of the knowledge that - * mnt_change_mountpoint will not release the final reference - * to a mountpoint. - * - * During mounting, the mount passed in as the parent mount will - * continue to use the old mountpoint and during unmounting, the - * old mountpoint will continue to exist until namespace_unlock, - * which happens well after mnt_change_mountpoint. - */ - spin_lock(&old_mountpoint->d_lock); - old_mountpoint->d_lockref.count--; - spin_unlock(&old_mountpoint->d_lock); - mnt_add_count(old_parent, -1); } @@ -1142,6 +1135,8 @@ static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput); static void mntput_no_expire(struct mount *mnt) { + LIST_HEAD(list); + rcu_read_lock(); if (likely(READ_ONCE(mnt->mnt_ns))) { /* @@ -1182,10 +1177,11 @@ static void mntput_no_expire(struct mount *mnt) if (unlikely(!list_empty(&mnt->mnt_mounts))) { struct mount *p, *tmp; list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { - umount_mnt(p); + __put_mountpoint(unhash_mnt(p), &list); } } unlock_mount_hash(); + shrink_dentry_list(&list); if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) { struct task_struct *task = current; @@ -1371,16 +1367,18 @@ int may_umount(struct vfsmount *mnt) EXPORT_SYMBOL(may_umount); -static HLIST_HEAD(unmounted); /* protected by namespace_sem */ - static void namespace_unlock(void) { struct hlist_head head; + LIST_HEAD(list); hlist_move_list(&unmounted, &head); + list_splice_init(&ex_mountpoints, &list); up_write(&namespace_sem); + shrink_dentry_list(&list); + if (likely(hlist_empty(&head))) return; |