procfs: switch /proc/self away from proc_dir_entry

Just have it pinned in dcache all along and let procfs ->kill_sb()
drop it before kill_anon_super().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

5 files changed, 55 insertions, 12 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 69078c7cef1f..593e7c5ddb49 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2794,7 +2794,7 @@ retry:
         return iter;
 }
 
-#define TGID_OFFSET (FIRST_PROCESS_ENTRY)
+#define TGID_OFFSET (FIRST_PROCESS_ENTRY + 1)
 
 static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
         struct tgid_iter iter)
@@ -2817,13 +2817,21 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
         struct tgid_iter iter;
         struct pid_namespace *ns;
         filldir_t __filldir;
+        loff_t pos = filp->f_pos;
 
-        if (filp->f_pos >= PID_MAX_LIMIT + TGID_OFFSET)
+        if (pos >= PID_MAX_LIMIT + TGID_OFFSET)
                 goto out;
 
-        ns = filp->f_dentry->d_sb->s_fs_info;
+        if (pos == TGID_OFFSET - 1) {
+                if (proc_fill_cache(filp, dirent, filldir, "self", 4,
+                                        NULL, NULL, NULL) < 0)
+                        goto out;
+                iter.tgid = 0;
+        } else {
+                iter.tgid = pos - TGID_OFFSET;
+        }
         iter.task = NULL;
-        iter.tgid = filp->f_pos - TGID_OFFSET;
+        ns = filp->f_dentry->d_sb->s_fs_info;
         for (iter = next_tgid(ns, iter);
              iter.task;
              iter.tgid += 1, iter = next_tgid(ns, iter)) {
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 869116c2afbe..908e97457319 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -506,5 +506,5 @@ int proc_fill_super(struct super_block *s)
                 return -ENOMEM;
         }
 
-        return 0;
+        return proc_setup_self(s);
 }
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 85ff3a4598b3..9c93a53f371d 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -205,3 +205,4 @@ int proc_setattr(struct dentry *dentry, struct iattr *attr);
 extern const struct inode_operations proc_ns_dir_inode_operations;
 extern const struct file_operations proc_ns_dir_operations;
 
+extern int proc_setup_self(struct super_block *);
diff --git a/fs/proc/root.c b/fs/proc/root.c
index c6e9fac26bac..20834b3c8ea3 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -137,6 +137,8 @@ static void proc_kill_sb(struct super_block *sb)
         struct pid_namespace *ns;
 
         ns = (struct pid_namespace *)sb->s_fs_info;
+        if (ns->proc_self)
+                dput(ns->proc_self);
         kill_anon_super(sb);
         put_pid_ns(ns);
 }
diff --git a/fs/proc/self.c b/fs/proc/self.c
index d8a025296613..21940d89977e 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -1,6 +1,7 @@
-#include <linux/proc_fs.h>
 #include <linux/sched.h>
 #include <linux/namei.h>
+#include <linux/pid_namespace.h>
+#include "internal.h"
 
 /*
  * /proc/self:
@@ -48,12 +49,43 @@ static const struct inode_operations proc_self_inode_operations = {
         .put_link       = proc_self_put_link,
 };
 
-void __init proc_self_init(void)
+static unsigned self_inum;
+
+int proc_setup_self(struct super_block *s)
 {
-        struct proc_dir_entry *proc_self_symlink;
-        umode_t mode;
+        struct inode *root_inode = s->s_root->d_inode;
+        struct pid_namespace *ns = s->s_fs_info;
+        struct dentry *self;
+        
+        mutex_lock(&root_inode->i_mutex);
+        self = d_alloc_name(s->s_root, "self");
+        if (self) {
+                struct inode *inode = new_inode_pseudo(s);
+                if (inode) {
+                        inode->i_ino = self_inum;
+                        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+                        inode->i_mode = S_IFLNK | S_IRWXUGO;
+                        inode->i_uid = GLOBAL_ROOT_UID;
+                        inode->i_gid = GLOBAL_ROOT_GID;
+                        inode->i_op = &proc_self_inode_operations;
+                        d_add(self, inode);
+                } else {
+                        dput(self);
+                        self = ERR_PTR(-ENOMEM);
+                }
+        } else {
+                self = ERR_PTR(-ENOMEM);
+        }
+        mutex_unlock(&root_inode->i_mutex);
+        if (IS_ERR(self)) {
+                pr_err("proc_fill_super: can't allocate /proc/self\n");
+                return PTR_ERR(self);
+        }
+        ns->proc_self = self;
+        return 0;
+}
 
-        mode = S_IFLNK | S_IRWXUGO;
-        proc_self_symlink = proc_create("self", mode, NULL, NULL );
-        proc_self_symlink->proc_iops = &proc_self_inode_operations;
+void __init proc_self_init(void)
+{
+        proc_alloc_inum(&self_inum);
 }