[Devel] [RFC][PATCH 1/4] seed /proc root inode in proc_fill_super()

[Dave Hansen]

Here's a set of patches which I believe allows multiple
instances of /proc to exist.  We want these because it
allows each pid_namespace to have a completely diffferent
view of /proc.

---

/proc currently has some special code to make sure
that the root directory gets set up correctly.  It
uses the global proc_mnt variable in order to find
its way to the root inode.

In order to try to get multiple /proc mounts, I'm
attempting to kill this variable.  But, I noticed
that we have all of the data to fill in the inode's
pid in proc_fill_super(), where it takes a wee bit
more work in proc_get_sb().

Any reason not to just do it in proc_fill_super()?

---

 lxc-dave/fs/proc/inode.c |    9 +++++++++
 lxc-dave/fs/proc/root.c  |   11 -----------
 2 files changed, 9 insertions(+), 11 deletions(-)

diff -puN fs/proc/inode.c~A0-seed-proc-differently fs/proc/inode.c
--- lxc/fs/proc/inode.c~A0-seed-proc-differently	2007-01-26 14:29:16.000000000 -0800
+++ lxc-dave/fs/proc/inode.c	2007-01-26 14:29:16.000000000 -0800
@@ -183,6 +183,7 @@ out_mod:
 
 int proc_fill_super(struct super_block *s, void *data, int silent)
 {
+	struct proc_inode *ei;
 	struct inode * root_inode;
 
 	s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
@@ -200,6 +201,14 @@ int proc_fill_super(struct super_block *
 	s->s_root = d_alloc_root(root_inode);
 	if (!s->s_root)
 		goto out_no_root;
+	/* 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(root_inode);
+	if (!ei->pid)
+		ei->pid = find_get_pid(1);
 	return 0;
 
 out_no_root:
diff -puN fs/proc/root.c~A0-seed-proc-differently fs/proc/root.c
--- lxc/fs/proc/root.c~A0-seed-proc-differently	2007-01-26 14:29:16.000000000 -0800
+++ lxc-dave/fs/proc/root.c	2007-01-26 14:29:16.000000000 -0800
@@ -30,17 +30,6 @@ struct proc_dir_entry *proc_sys_root;
 static int proc_get_sb(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
-	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.
-		 */
-		struct proc_inode *ei;
-		ei = PROC_I(proc_mnt->mnt_sb->s_root->d_inode);
-		if (!ei->pid)
-			ei->pid = find_get_pid(1);
-	}
 	return get_sb_single(fs_type, flags, data, proc_fill_super, mnt);
 }
 
_
_______________________________________________
Containers mailing list
Containers at lists.osdl.org
https://lists.osdl.org/mailman/listinfo/containers