On Thu, 2008-03-27 at 13:06 +0100, Miklos Szeredi wrote:
> plain text document attachment (mountinfo_dominator.patch)
> From: Miklos Szeredi <mszeredi@xxxxxxx>
>
> Show peer group ID of nearest dominating group that has intersection
> with the mount's namespace.
>
> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
> ---
> Documentation/filesystems/proc.txt | 6 ++++
> fs/namespace.c | 9 +++++-
> fs/pnode.c | 51 +++++++++++++++++++++++++++++++++++++
> fs/pnode.h | 1
> 4 files changed, 65 insertions(+), 2 deletions(-)
>
> Index: vfs-2.6/Documentation/filesystems/proc.txt
> ===================================================================
> --- vfs-2.6.orig/Documentation/filesystems/proc.txt 2008-03-27 12:06:15.000000000 +0100
> +++ vfs-2.6/Documentation/filesystems/proc.txt 2008-03-27 12:06:17.000000000 +0100
> @@ -2374,8 +2374,14 @@ possible optional fields are:
>
> shared:X mount is shared in peer group X
> master:X mount is slave to peer group X
> +propagate_from:X mount is slave and receives propagation from peer group X (*)
> unbindable mount is unbindable
>
> +(*) X is the closest dominant peer group under the process's root. If
> +X is the immediate master of the mount, or if there's no dominant peer
> +group under the same root, then only the "master:X" field is present
> +and not the "propagate_from:X" field.
> +
> For more information on mount propagation see:
>
> Documentation/filesystems/sharedsubtree.txt
> Index: vfs-2.6/fs/namespace.c
> ===================================================================
> --- vfs-2.6.orig/fs/namespace.c 2008-03-27 12:06:15.000000000 +0100
> +++ vfs-2.6/fs/namespace.c 2008-03-27 12:06:17.000000000 +0100
> @@ -836,8 +836,13 @@ static int show_mountinfo(struct seq_fil
> /* 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))
> - seq_printf(m, " master:%i", mnt->mnt_master->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");
>
> Index: vfs-2.6/fs/pnode.c
> ===================================================================
> --- vfs-2.6.orig/fs/pnode.c 2008-03-27 12:06:10.000000000 +0100
> +++ vfs-2.6/fs/pnode.c 2008-03-27 12:06:17.000000000 +0100
> @@ -28,6 +28,57 @@ static inline struct vfsmount *next_slav
> return list_entry(p->mnt_slave.next, struct vfsmount, mnt_slave);
> }
>
> +/*
> + * Return true if path is reachable from root
> + *
> + * namespace_sem is held, and mnt is attached
> + */
> +static bool is_path_reachable(struct vfsmount *mnt, struct dentry *dentry,
> + const struct path *root)
> +{
> + while (mnt != root->mnt && mnt->mnt_parent != mnt) {
> + dentry = mnt->mnt_mountpoint;
> + mnt = mnt->mnt_parent;
> + }
> + return mnt == root->mnt && is_subdir(dentry, root->dentry);
> +}
This function belongs somewhere else, maybe namespace.c since it has
nothing to do with propagation and is generally provides a useful
service.
RP
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