From: Eric W. Biederman <ebied...@xmission.com>

Reorganize proc_get_sb so it can be called before the struct pid
of the first process is allocated.

Signed-off-by: Eric W. Biederman <ebied...@xmission.com>
Signed-off-by: Daniel Lezcano <daniel.lezc...@free.fr>
---
 fs/proc/root.c         |   25 +++++++------------------
 kernel/fork.c          |    6 ------
 kernel/pid_namespace.c |    4 ++++
 3 files changed, 11 insertions(+), 24 deletions(-)

diff --git a/fs/proc/root.c b/fs/proc/root.c
index ef9fa8e..e5e2bfa 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -43,17 +43,6 @@ static struct dentry *proc_mount(struct file_system_type 
*fs_type,
        struct pid_namespace *ns;
        struct proc_inode *ei;
 
-       if (proc_mnt) {
-               /* Seed the root directory with a pid so it doesn't need
-                * to be special in base.c.  I would do this earlier but
-                * the only task alive when /proc is mounted the first time
-                * is the init_task and it doesn't have any pids.
-                */
-               ei = PROC_I(proc_mnt->mnt_sb->s_root->d_inode);
-               if (!ei->pid)
-                       ei->pid = find_get_pid(1);
-       }
-
        if (flags & MS_KERNMOUNT)
                ns = (struct pid_namespace *)data;
        else
@@ -71,16 +60,16 @@ static struct dentry *proc_mount(struct file_system_type 
*fs_type,
                        return ERR_PTR(err);
                }
 
-               ei = PROC_I(sb->s_root->d_inode);
-               if (!ei->pid) {
-                       rcu_read_lock();
-                       ei->pid = get_pid(find_pid_ns(1, ns));
-                       rcu_read_unlock();
-               }
-
                sb->s_flags |= MS_ACTIVE;
        }
 
+       ei = PROC_I(sb->s_root->d_inode);
+       if (!ei->pid) {
+               rcu_read_lock();
+               ei->pid = get_pid(find_pid_ns(1, ns));
+               rcu_read_unlock();
+       }
+
        return dget(sb->s_root);
 }
 
diff --git a/kernel/fork.c b/kernel/fork.c
index c9f0784..e7a5907 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1180,12 +1180,6 @@ static struct task_struct *copy_process(unsigned long 
clone_flags,
                pid = alloc_pid(p->nsproxy->pid_ns);
                if (!pid)
                        goto bad_fork_cleanup_io;
-
-               if (clone_flags & CLONE_NEWPID) {
-                       retval = pid_ns_prepare_proc(p->nsproxy->pid_ns);
-                       if (retval < 0)
-                               goto bad_fork_free_pid;
-               }
        }
 
        p->pid = pid_nr(pid);
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index a5aff94..b90e4ab 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -14,6 +14,7 @@
 #include <linux/err.h>
 #include <linux/acct.h>
 #include <linux/slab.h>
+#include <linux/proc_fs.h>
 
 #define BITS_PER_PAGE          (PAGE_SIZE*8)
 
@@ -96,6 +97,9 @@ static struct pid_namespace *create_pid_namespace(struct 
pid_namespace *parent_p
        for (i = 1; i < PIDMAP_ENTRIES; i++)
                atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
 
+       if (pid_ns_prepare_proc(ns))
+               goto out_free_map;
+
        return ns;
 
 out_free_map:
-- 
1.7.1

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