1 files changed, 233 insertions, 32 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 1bf302d0478b..0505fb61aa74 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -27,6 +27,7 @@
 #include <linux/mount.h>
 #include <linux/ramfs.h>
 #include <linux/log2.h>
+#include <linux/idr.h>
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
 #include "pnode.h"
@@ -39,6 +40,8 @@
 __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
 
 static int event;
+static DEFINE_IDA(mnt_id_ida);
+static DEFINE_IDA(mnt_group_ida);
 
 static struct list_head *mount_hashtable __read_mostly;
 static struct kmem_cache *mnt_cache __read_mostly;
@@ -58,10 +61,63 @@ static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
 
 #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16)
 
+/* allocation is serialized by namespace_sem */
+static int mnt_alloc_id(struct vfsmount *mnt)
+{
+        int res;
+
+retry:
+        ida_pre_get(&mnt_id_ida, GFP_KERNEL);
+        spin_lock(&vfsmount_lock);
+        res = ida_get_new(&mnt_id_ida, &mnt->mnt_id);
+        spin_unlock(&vfsmount_lock);
+        if (res == -EAGAIN)
+                goto retry;
+
+        return res;
+}
+
+static void mnt_free_id(struct vfsmount *mnt)
+{
+        spin_lock(&vfsmount_lock);
+        ida_remove(&mnt_id_ida, mnt->mnt_id);
+        spin_unlock(&vfsmount_lock);
+}
+
+/*
+ * Allocate a new peer group ID
+ *
+ * mnt_group_ida is protected by namespace_sem
+ */
+static int mnt_alloc_group_id(struct vfsmount *mnt)
+{
+        if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL))
+                return -ENOMEM;
+
+        return ida_get_new_above(&mnt_group_ida, 1, &mnt->mnt_group_id);
+}
+
+/*
+ * Release a peer group ID
+ */
+void mnt_release_group_id(struct vfsmount *mnt)
+{
+        ida_remove(&mnt_group_ida, mnt->mnt_group_id);
+        mnt->mnt_group_id = 0;
+}
+
 struct vfsmount *alloc_vfsmnt(const char *name)
 {
         struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
         if (mnt) {
+                int err;
+
+                err = mnt_alloc_id(mnt);
+                if (err) {
+                        kmem_cache_free(mnt_cache, mnt);
+                        return NULL;
+                }
+
                 atomic_set(&mnt->mnt_count, 1);
                 INIT_LIST_HEAD(&mnt->mnt_hash);
                 INIT_LIST_HEAD(&mnt->mnt_child);
@@ -353,6 +409,7 @@ EXPORT_SYMBOL(simple_set_mnt);
 void free_vfsmnt(struct vfsmount *mnt)
 {
         kfree(mnt->mnt_devname);
+        mnt_free_id(mnt);
         kmem_cache_free(mnt_cache, mnt);
 }
 
@@ -499,6 +556,17 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
         struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
 
         if (mnt) {
+                if (flag & (CL_SLAVE | CL_PRIVATE))
+                        mnt->mnt_group_id = 0; /* not a peer of original */
+                else
+                        mnt->mnt_group_id = old->mnt_group_id;
+
+                if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
+                        int err = mnt_alloc_group_id(mnt);
+                        if (err)
+                                goto out_free;
+                }
+
                 mnt->mnt_flags = old->mnt_flags;
                 atomic_inc(&sb->s_active);
                 mnt->mnt_sb = sb;
@@ -528,6 +596,10 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
                 }
         }
         return mnt;
+
+ out_free:
+        free_vfsmnt(mnt);
+        return NULL;
 }
 
 static inline void __mntput(struct vfsmount *mnt)
@@ -652,20 +724,21 @@ void save_mount_options(struct super_block *sb, char *options)
 }
 EXPORT_SYMBOL(save_mount_options);
 
+#ifdef CONFIG_PROC_FS
 /* iterator */
 static void *m_start(struct seq_file *m, loff_t *pos)
 {
-        struct mnt_namespace *n = m->private;
+        struct proc_mounts *p = m->private;
 
         down_read(&namespace_sem);
-        return seq_list_start(&n->list, *pos);
+        return seq_list_start(&p->ns->list, *pos);
 }
 
 static void *m_next(struct seq_file *m, void *v, loff_t *pos)
 {
-        struct mnt_namespace *n = m->private;
+        struct proc_mounts *p = m->private;
 
-        return seq_list_next(v, &n->list, pos);
+        return seq_list_next(v, &p->ns->list, pos);
 }
 
 static void m_stop(struct seq_file *m, void *v)
@@ -673,20 +746,30 @@ static void m_stop(struct seq_file *m, void *v)
         up_read(&namespace_sem);
 }
 
-static int show_vfsmnt(struct seq_file *m, void *v)
+struct proc_fs_info {
+        int flag;
+        const char *str;
+};
+
+static void show_sb_opts(struct seq_file *m, struct super_block *sb)
 {
-        struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
-        int err = 0;
-        static struct proc_fs_info {
-                int flag;
-                char *str;
-        } fs_info[] = {
+        static const struct proc_fs_info fs_info[] = {
                 { MS_SYNCHRONOUS, ",sync" },
                 { MS_DIRSYNC, ",dirsync" },
                 { MS_MANDLOCK, ",mand" },
                 { 0, NULL }
         };
-        static struct proc_fs_info mnt_info[] = {
+        const struct proc_fs_info *fs_infop;
+
+        for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
+                if (sb->s_flags & fs_infop->flag)
+                        seq_puts(m, fs_infop->str);
+        }
+}
+
+static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
+{
+        static const struct proc_fs_info mnt_info[] = {
                 { MNT_NOSUID, ",nosuid" },
                 { MNT_NODEV, ",nodev" },
                 { MNT_NOEXEC, ",noexec" },
@@ -695,40 +778,108 @@ static int show_vfsmnt(struct seq_file *m, void *v)
                 { MNT_RELATIME, ",relatime" },
                 { 0, NULL }
         };
-        struct proc_fs_info *fs_infop;
+        const struct proc_fs_info *fs_infop;
+
+        for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
+                if (mnt->mnt_flags & fs_infop->flag)
+                        seq_puts(m, fs_infop->str);
+        }
+}
+
+static void show_type(struct seq_file *m, struct super_block *sb)
+{
+        mangle(m, sb->s_type->name);
+        if (sb->s_subtype && sb->s_subtype[0]) {
+                seq_putc(m, '.');
+                mangle(m, sb->s_subtype);
+        }
+}
+
+static int show_vfsmnt(struct seq_file *m, void *v)
+{
+        struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
+        int err = 0;
         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
 
         mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
         seq_putc(m, ' ');
         seq_path(m, &mnt_path, " \t\n\\");
         seq_putc(m, ' ');
-        mangle(m, mnt->mnt_sb->s_type->name);
-        if (mnt->mnt_sb->s_subtype && mnt->mnt_sb->s_subtype[0]) {
-                seq_putc(m, '.');
-                mangle(m, mnt->mnt_sb->s_subtype);
-        }
+        show_type(m, mnt->mnt_sb);
         seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
-        for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
-                if (mnt->mnt_sb->s_flags & fs_infop->flag)
-                        seq_puts(m, fs_infop->str);
-        }
-        for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
-                if (mnt->mnt_flags & fs_infop->flag)
-                        seq_puts(m, fs_infop->str);
-        }
+        show_sb_opts(m, mnt->mnt_sb);
+        show_mnt_opts(m, mnt);
         if (mnt->mnt_sb->s_op->show_options)
                 err = mnt->mnt_sb->s_op->show_options(m, mnt);
         seq_puts(m, " 0 0\n");
         return err;
 }
 
-struct seq_operations mounts_op = {
+const struct seq_operations mounts_op = {
         .start  = m_start,
         .next   = m_next,
         .stop   = m_stop,
         .show   = show_vfsmnt
 };
 
+static int show_mountinfo(struct seq_file *m, void *v)
+{
+        struct proc_mounts *p = m->private;
+        struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
+        struct super_block *sb = mnt->mnt_sb;
+        struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
+        struct path root = p->root;
+        int err = 0;
+
+        seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id,
+                   MAJOR(sb->s_dev), MINOR(sb->s_dev));
+        seq_dentry(m, mnt->mnt_root, " \t\n\\");
+        seq_putc(m, ' ');
+        seq_path_root(m, &mnt_path, &root, " \t\n\\");
+        if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) {
+                /*
+                 * Mountpoint is outside root, discard that one.  Ugly,
+                 * but less so than trying to do that in iterator in a
+                 * race-free way (due to renames).
+                 */
+                return SEQ_SKIP;
+        }
+        seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
+        show_mnt_opts(m, mnt);
+
+        /* Tagged fields ("foo:X" or "bar") */
+        if (IS_MNT_SHARED(mnt))
+                seq_printf(m, " shared:%i", mnt->mnt_group_id);
+        if (IS_MNT_SLAVE(mnt)) {
+                int master = mnt->mnt_master->mnt_group_id;
+                int dom = get_dominating_id(mnt, &p->root);
+                seq_printf(m, " master:%i", master);
+                if (dom && dom != master)
+                        seq_printf(m, " propagate_from:%i", dom);
+        }
+        if (IS_MNT_UNBINDABLE(mnt))
+                seq_puts(m, " unbindable");
+
+        /* Filesystem specific data */
+        seq_puts(m, " - ");
+        show_type(m, sb);
+        seq_putc(m, ' ');
+        mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+        seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
+        show_sb_opts(m, sb);
+        if (sb->s_op->show_options)
+                err = sb->s_op->show_options(m, mnt);
+        seq_putc(m, '\n');
+        return err;
+}
+
+const struct seq_operations mountinfo_op = {
+        .start  = m_start,
+        .next   = m_next,
+        .stop   = m_stop,
+        .show   = show_mountinfo,
+};
+
 static int show_vfsstat(struct seq_file *m, void *v)
 {
         struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
@@ -749,7 +900,7 @@ static int show_vfsstat(struct seq_file *m, void *v)
 
         /* file system type */
         seq_puts(m, "with fstype ");
-        mangle(m, mnt->mnt_sb->s_type->name);
+        show_type(m, mnt->mnt_sb);
 
         /* optional statistics */
         if (mnt->mnt_sb->s_op->show_stats) {
@@ -761,12 +912,13 @@ static int show_vfsstat(struct seq_file *m, void *v)
         return err;
 }
 
-struct seq_operations mountstats_op = {
+const struct seq_operations mountstats_op = {
         .start  = m_start,
         .next   = m_next,
         .stop   = m_stop,
         .show   = show_vfsstat,
 };
+#endif  /* CONFIG_PROC_FS */
 
 /**
  * may_umount_tree - check if a mount tree is busy
@@ -1108,6 +1260,33 @@ void drop_collected_mounts(struct vfsmount *mnt)
         release_mounts(&umount_list);
 }
 
+static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end)
+{
+        struct vfsmount *p;
+
+        for (p = mnt; p != end; p = next_mnt(p, mnt)) {
+                if (p->mnt_group_id && !IS_MNT_SHARED(p))
+                        mnt_release_group_id(p);
+        }
+}
+
+static int invent_group_ids(struct vfsmount *mnt, bool recurse)
+{
+        struct vfsmount *p;
+
+        for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) {
+                if (!p->mnt_group_id && !IS_MNT_SHARED(p)) {
+                        int err = mnt_alloc_group_id(p);
+                        if (err) {
+                                cleanup_group_ids(mnt, p);
+                                return err;
+                        }
+                }
+        }
+
+        return 0;
+}
+
 /*
  *  @source_mnt : mount tree to be attached
  *  @nd         : place the mount tree @source_mnt is attached
@@ -1178,9 +1357,16 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt,
         struct vfsmount *dest_mnt = path->mnt;
         struct dentry *dest_dentry = path->dentry;
         struct vfsmount *child, *p;
+        int err;
 
-        if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list))
-                return -EINVAL;
+        if (IS_MNT_SHARED(dest_mnt)) {
+                err = invent_group_ids(source_mnt, true);
+                if (err)
+                        goto out;
+        }
+        err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list);
+        if (err)
+                goto out_cleanup_ids;
 
         if (IS_MNT_SHARED(dest_mnt)) {
                 for (p = source_mnt; p; p = next_mnt(p, source_mnt))
@@ -1203,6 +1389,12 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt,
         }
         spin_unlock(&vfsmount_lock);
         return 0;
+
+ out_cleanup_ids:
+        if (IS_MNT_SHARED(dest_mnt))
+                cleanup_group_ids(source_mnt, NULL);
+ out:
+        return err;
 }
 
 static int graft_tree(struct vfsmount *mnt, struct path *path)
@@ -1243,6 +1435,7 @@ static noinline int do_change_type(struct nameidata *nd, int flag)
         struct vfsmount *m, *mnt = nd->path.mnt;
         int recurse = flag & MS_REC;
         int type = flag & ~MS_REC;
+        int err = 0;
 
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
@@ -1251,12 +1444,20 @@ static noinline int do_change_type(struct nameidata *nd, int flag)
                 return -EINVAL;
 
         down_write(&namespace_sem);
+        if (type == MS_SHARED) {
+                err = invent_group_ids(mnt, recurse);
+                if (err)
+                        goto out_unlock;
+        }
+
         spin_lock(&vfsmount_lock);
         for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
                 change_mnt_propagation(m, type);
         spin_unlock(&vfsmount_lock);
+
+ out_unlock:
         up_write(&namespace_sem);
-        return 0;
+        return err;
 }
 
 /*