* [RFC][PATCH 6/8] namespace: use mnt_base for proc
@ 2005-05-30 13:32 Miklos Szeredi
2005-05-30 19:54 ` Mike Waychison
0 siblings, 1 reply; 3+ messages in thread
From: Miklos Szeredi @ 2005-05-30 13:32 UTC (permalink / raw)
To: linux-fsdevel; +Cc: mike, jamie, viro
This patch makes /proc/PID/mounts use fs->rootmnt->mnt_base instead of
namespace->root. This means, that if a process changes it's root to a
different namespace, or a detached subtree, the base of that tree will
be used, instead of the process's namespace.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Index: linux/fs/namespace.c
===================================================================
--- linux.orig/fs/namespace.c 2005-05-29 17:15:56.000000000 +0200
+++ linux/fs/namespace.c 2005-05-29 17:20:32.000000000 +0200
@@ -242,8 +242,7 @@ static void destroy_vfsmnt(struct vfsmou
/* iterator */
static void *m_start(struct seq_file *m, loff_t *pos)
{
- struct namespace *n = m->private;
- struct vfsmount *mnt = n->root;
+ struct vfsmount *mnt = m->private;
struct vfsmount *p;
loff_t l = *pos;
@@ -256,8 +255,7 @@ static void *m_start(struct seq_file *m,
static void *m_next(struct seq_file *m, void *v, loff_t *pos)
{
- struct namespace *n = m->private;
- struct vfsmount *mnt = n->root;
+ struct vfsmount *mnt = m->private;
struct vfsmount *p = v;
(*pos)++;
return next_mnt(p, mnt);
Index: linux/include/linux/mount.h
===================================================================
--- linux.orig/include/linux/mount.h 2005-05-29 16:55:56.000000000 +0200
+++ linux/include/linux/mount.h 2005-05-29 17:25:53.000000000 +0200
@@ -51,6 +51,18 @@ static inline struct vfsmount *mntget(st
return mnt;
}
+static inline struct vfsmount *mntget_base(struct vfsmount *mnt)
+{
+ if (mnt) {
+ read_lock(&vfsmountref_lock);
+ mnt = mnt->mnt_base;
+ atomic_inc(&mnt->mnt_count);
+ atomic_inc(&mnt->mnt_group_count);
+ read_unlock(&vfsmountref_lock);
+ }
+ return mnt;
+}
+
extern void destroy_mount_group(struct vfsmount *mnt);
static inline void mntput_no_expire(struct vfsmount *mnt)
Index: linux/fs/proc/base.c
===================================================================
--- linux.orig/fs/proc/base.c 2005-05-29 17:18:40.000000000 +0200
+++ linux/fs/proc/base.c 2005-05-29 17:27:14.000000000 +0200
@@ -581,16 +581,13 @@ static int mounts_open(struct inode *ino
if (!ret) {
struct seq_file *m = file->private_data;
- struct namespace *namespace;
- task_lock(task);
- namespace = task->namespace;
- if (namespace)
- get_namespace(namespace);
- task_unlock(task);
-
- if (namespace)
- m->private = namespace;
- else {
+ struct fs_struct *fs = get_fs_struct(task);
+ if (fs) {
+ read_lock(&fs->lock);
+ m->private = mntget_base(fs->rootmnt);
+ read_unlock(&fs->lock);
+ put_fs_struct(fs);
+ } else {
seq_release(inode, file);
ret = -EINVAL;
}
@@ -601,8 +598,8 @@ static int mounts_open(struct inode *ino
static int mounts_release(struct inode *inode, struct file *file)
{
struct seq_file *m = file->private_data;
- struct namespace *namespace = m->private;
- put_namespace(namespace);
+ struct vfsmount *mnt = m->private;
+ mntput(mnt);
return seq_release(inode, file);
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC][PATCH 6/8] namespace: use mnt_base for proc
2005-05-30 13:32 [RFC][PATCH 6/8] namespace: use mnt_base for proc Miklos Szeredi
@ 2005-05-30 19:54 ` Mike Waychison
2005-05-31 5:58 ` Miklos Szeredi
0 siblings, 1 reply; 3+ messages in thread
From: Mike Waychison @ 2005-05-30 19:54 UTC (permalink / raw)
To: Miklos Szeredi; +Cc: linux-fsdevel, jamie, viro
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Miklos Szeredi wrote:
> This patch makes /proc/PID/mounts use fs->rootmnt->mnt_base instead of
> namespace->root. This means, that if a process changes it's root to a
> different namespace, or a detached subtree, the base of that tree will
> be used, instead of the process's namespace.
>
We are going to want to block out any modifications of the tree between
start and stop. This should be possible by grabbing a read lock on
vfsmountref_lock IIRC.
> Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
>
> Index: linux/fs/namespace.c
> ===================================================================
> --- linux.orig/fs/namespace.c 2005-05-29 17:15:56.000000000 +0200
> +++ linux/fs/namespace.c 2005-05-29 17:20:32.000000000 +0200
> @@ -242,8 +242,7 @@ static void destroy_vfsmnt(struct vfsmou
> /* iterator */
> static void *m_start(struct seq_file *m, loff_t *pos)
> {
> - struct namespace *n = m->private;
> - struct vfsmount *mnt = n->root;
> + struct vfsmount *mnt = m->private;
> struct vfsmount *p;
> loff_t l = *pos;
>
> @@ -256,8 +255,7 @@ static void *m_start(struct seq_file *m,
>
> static void *m_next(struct seq_file *m, void *v, loff_t *pos)
> {
> - struct namespace *n = m->private;
> - struct vfsmount *mnt = n->root;
> + struct vfsmount *mnt = m->private;
> struct vfsmount *p = v;
> (*pos)++;
> return next_mnt(p, mnt);
> Index: linux/include/linux/mount.h
> ===================================================================
> --- linux.orig/include/linux/mount.h 2005-05-29 16:55:56.000000000 +0200
> +++ linux/include/linux/mount.h 2005-05-29 17:25:53.000000000 +0200
> @@ -51,6 +51,18 @@ static inline struct vfsmount *mntget(st
> return mnt;
> }
>
> +static inline struct vfsmount *mntget_base(struct vfsmount *mnt)
> +{
> + if (mnt) {
> + read_lock(&vfsmountref_lock);
> + mnt = mnt->mnt_base;
> + atomic_inc(&mnt->mnt_count);
> + atomic_inc(&mnt->mnt_group_count);
> + read_unlock(&vfsmountref_lock);
> + }
> + return mnt;
> +}
> +
> extern void destroy_mount_group(struct vfsmount *mnt);
>
> static inline void mntput_no_expire(struct vfsmount *mnt)
> Index: linux/fs/proc/base.c
> ===================================================================
> --- linux.orig/fs/proc/base.c 2005-05-29 17:18:40.000000000 +0200
> +++ linux/fs/proc/base.c 2005-05-29 17:27:14.000000000 +0200
> @@ -581,16 +581,13 @@ static int mounts_open(struct inode *ino
>
> if (!ret) {
> struct seq_file *m = file->private_data;
> - struct namespace *namespace;
> - task_lock(task);
> - namespace = task->namespace;
> - if (namespace)
> - get_namespace(namespace);
> - task_unlock(task);
> -
> - if (namespace)
> - m->private = namespace;
> - else {
> + struct fs_struct *fs = get_fs_struct(task);
> + if (fs) {
> + read_lock(&fs->lock);
> + m->private = mntget_base(fs->rootmnt);
> + read_unlock(&fs->lock);
> + put_fs_struct(fs);
> + } else {
> seq_release(inode, file);
> ret = -EINVAL;
> }
> @@ -601,8 +598,8 @@ static int mounts_open(struct inode *ino
> static int mounts_release(struct inode *inode, struct file *file)
> {
> struct seq_file *m = file->private_data;
> - struct namespace *namespace = m->private;
> - put_namespace(namespace);
> + struct vfsmount *mnt = m->private;
> + mntput(mnt);
> return seq_release(inode, file);
> }
>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.0 (GNU/Linux)
Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org
iD8DBQFCm29jdQs4kOxk3/MRAh82AJ9KkQ1ZSaXBXICKVmwXIqybmOvlNACfdkc1
BhAJt+HydEmWeYHQkt1Uc3Y=
=+YA1
-----END PGP SIGNATURE-----
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC][PATCH 6/8] namespace: use mnt_base for proc
2005-05-30 19:54 ` Mike Waychison
@ 2005-05-31 5:58 ` Miklos Szeredi
0 siblings, 0 replies; 3+ messages in thread
From: Miklos Szeredi @ 2005-05-31 5:58 UTC (permalink / raw)
To: mike; +Cc: linux-fsdevel, jamie, viro
> We are going to want to block out any modifications of the tree between
> start and stop. This should be possible by grabbing a read lock on
> vfsmountref_lock IIRC.
It's now protected by namespace_sem. There's some overlap between
vfsmount_lock, vfsmountref_lock and namespace_sem. All of them are
held when modifying the tree.
Do you have an idea on how to consolidate the three locks?
Thanks,
Miklos
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2005-05-31 5:59 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2005-05-30 13:32 [RFC][PATCH 6/8] namespace: use mnt_base for proc Miklos Szeredi
2005-05-30 19:54 ` Mike Waychison
2005-05-31 5:58 ` Miklos Szeredi
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).