diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/mount.h | 12 | ||||
| -rw-r--r-- | fs/namespace.c | 91 | ||||
| -rw-r--r-- | fs/proc_namespace.c | 4 |
3 files changed, 87 insertions, 20 deletions
diff --git a/fs/mount.h b/fs/mount.h index 711a4093e475..c7abb7b394d8 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -9,7 +9,13 @@ struct mnt_namespace { atomic_t count; struct ns_common ns; struct mount * root; + /* + * Traversal and modification of .list is protected by either + * - taking namespace_sem for write, OR + * - taking namespace_sem for read AND taking .ns_lock. + */ struct list_head list; + spinlock_t ns_lock; struct user_namespace *user_ns; struct ucounts *ucounts; u64 seq; /* Sequence number to prevent loops */ @@ -133,9 +139,7 @@ struct proc_mounts { struct mnt_namespace *ns; struct path root; int (*show)(struct seq_file *, struct vfsmount *); - void *cached_mount; - u64 cached_event; - loff_t cached_index; + struct mount cursor; }; extern const struct seq_operations mounts_op; @@ -153,3 +157,5 @@ static inline bool is_anon_ns(struct mnt_namespace *ns) { return ns->seq == 0; } + +extern void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor); diff --git a/fs/namespace.c b/fs/namespace.c index a28e4db075ed..3ee236f228a2 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -648,6 +648,21 @@ struct vfsmount *lookup_mnt(const struct path *path) return m; } +static inline void lock_ns_list(struct mnt_namespace *ns) +{ + spin_lock(&ns->ns_lock); +} + +static inline void unlock_ns_list(struct mnt_namespace *ns) +{ + spin_unlock(&ns->ns_lock); +} + +static inline bool mnt_is_cursor(struct mount *mnt) +{ + return mnt->mnt.mnt_flags & MNT_CURSOR; +} + /* * __is_local_mountpoint - Test to see if dentry is a mountpoint in the * current mount namespace. @@ -673,11 +688,15 @@ bool __is_local_mountpoint(struct dentry *dentry) goto out; down_read(&namespace_sem); + lock_ns_list(ns); list_for_each_entry(mnt, &ns->list, mnt_list) { + if (mnt_is_cursor(mnt)) + continue; is_covered = (mnt->mnt_mountpoint == dentry); if (is_covered) break; } + unlock_ns_list(ns); up_read(&namespace_sem); out: return is_covered; @@ -1245,46 +1264,71 @@ struct vfsmount *mnt_clone_internal(const struct path *path) } #ifdef CONFIG_PROC_FS +static struct mount *mnt_list_next(struct mnt_namespace *ns, + struct list_head *p) +{ + struct mount *mnt, *ret = NULL; + + lock_ns_list(ns); + list_for_each_continue(p, &ns->list) { + mnt = list_entry(p, typeof(*mnt), mnt_list); + if (!mnt_is_cursor(mnt)) { + ret = mnt; + break; + } + } + unlock_ns_list(ns); + + return ret; +} + /* iterator; we want it to have access to namespace_sem, thus here... */ static void *m_start(struct seq_file *m, loff_t *pos) { struct proc_mounts *p = m->private; + struct list_head *prev; down_read(&namespace_sem); - if (p->cached_event == p->ns->event) { - void *v = p->cached_mount; - if (*pos == p->cached_index) - return v; - if (*pos == p->cached_index + 1) { - v = seq_list_next(v, &p->ns->list, &p->cached_index); - return p->cached_mount = v; - } + if (!*pos) { + prev = &p->ns->list; + } else { + prev = &p->cursor.mnt_list; + + /* Read after we'd reached the end? */ + if (list_empty(prev)) + return NULL; } - p->cached_event = p->ns->event; - p->cached_mount = seq_list_start(&p->ns->list, *pos); - p->cached_index = *pos; - return p->cached_mount; + return mnt_list_next(p->ns, prev); } static void *m_next(struct seq_file *m, void *v, loff_t *pos) { struct proc_mounts *p = m->private; + struct mount *mnt = v; - p->cached_mount = seq_list_next(v, &p->ns->list, pos); - p->cached_index = *pos; - return p->cached_mount; + ++*pos; + return mnt_list_next(p->ns, &mnt->mnt_list); } static void m_stop(struct seq_file *m, void *v) { + struct proc_mounts *p = m->private; + struct mount *mnt = v; + + lock_ns_list(p->ns); + if (mnt) + list_move_tail(&p->cursor.mnt_list, &mnt->mnt_list); + else + list_del_init(&p->cursor.mnt_list); + unlock_ns_list(p->ns); up_read(&namespace_sem); } static int m_show(struct seq_file *m, void *v) { struct proc_mounts *p = m->private; - struct mount *r = list_entry(v, struct mount, mnt_list); + struct mount *r = v; return p->show(m, &r->mnt); } @@ -1294,6 +1338,15 @@ const struct seq_operations mounts_op = { .stop = m_stop, .show = m_show, }; + +void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor) +{ + down_read(&namespace_sem); + lock_ns_list(ns); + list_del(&cursor->mnt_list); + unlock_ns_list(ns); + up_read(&namespace_sem); +} #endif /* CONFIG_PROC_FS */ /** @@ -3202,6 +3255,7 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool a atomic_set(&new_ns->count, 1); INIT_LIST_HEAD(&new_ns->list); init_waitqueue_head(&new_ns->poll); + spin_lock_init(&new_ns->ns_lock); new_ns->user_ns = get_user_ns(user_ns); new_ns->ucounts = ucounts; return new_ns; @@ -3842,10 +3896,14 @@ static bool mnt_already_visible(struct mnt_namespace *ns, bool visible = false; down_read(&namespace_sem); + lock_ns_list(ns); list_for_each_entry(mnt, &ns->list, mnt_list) { struct mount *child; int mnt_flags; + if (mnt_is_cursor(mnt)) + continue; + if (mnt->mnt.mnt_sb->s_type != sb->s_type) continue; @@ -3893,6 +3951,7 @@ static bool mnt_already_visible(struct mnt_namespace *ns, next: ; } found: + unlock_ns_list(ns); up_read(&namespace_sem); return visible; } diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c index 273ee82d8aa9..e4d70c0dffe9 100644 --- a/fs/proc_namespace.c +++ b/fs/proc_namespace.c @@ -279,7 +279,8 @@ static int mounts_open_common(struct inode *inode, struct file *file, p->ns = ns; p->root = root; p->show = show; - p->cached_event = ~0ULL; + INIT_LIST_HEAD(&p->cursor.mnt_list); + p->cursor.mnt.mnt_flags = MNT_CURSOR; return 0; @@ -296,6 +297,7 @@ static int mounts_release(struct inode *inode, struct file *file) struct seq_file *m = file->private_data; struct proc_mounts *p = m->private; path_put(&p->root); + mnt_cursor_del(p->ns, &p->cursor); put_mnt_ns(p->ns); return seq_release_private(inode, file); } |