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authorLinus Torvalds <torvalds@linux-foundation.org>2020-06-01 16:44:06 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-01 16:44:06 -0700
commitf359287765c04711ff54fbd11645271d8e5ff763 (patch)
tree73792cb8ca8ca289e66d18356667a781b3408eb7 /fs/namespace.c
parent8b39a57e965403c12a27d0859901a8a7d1d7318f (diff)
parentc8ffd8bcdd28296a198f237cc595148a8d4adfbe (diff)
Merge branch 'from-miklos' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro: "Assorted patches from Miklos. An interesting part here is /proc/mounts stuff..." The "/proc/mounts stuff" is using a cursor for keeeping the location data while traversing the mount listing. Also probably worth noting is the addition of faccessat2(), which takes an additional set of flags to specify how the lookup is done (AT_EACCESS, AT_SYMLINK_NOFOLLOW, AT_EMPTY_PATH). * 'from-miklos' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: vfs: add faccessat2 syscall vfs: don't parse "silent" option vfs: don't parse "posixacl" option vfs: don't parse forbidden flags statx: add mount_root statx: add mount ID statx: don't clear STATX_ATIME on SB_RDONLY uapi: deprecate STATX_ALL utimensat: AT_EMPTY_PATH support vfs: split out access_override_creds() proc/mounts: add cursor aio: fix async fsync creds vfs: allow unprivileged whiteout creation
Diffstat (limited to 'fs/namespace.c')
-rw-r--r--fs/namespace.c91
1 files changed, 75 insertions, 16 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 5f036dc711b6..a6baee3c7904 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;
}