lkml.org 
[lkml]   [2008]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[patch 7/7] vfs: mountinfo: show dominating group id
    From: Miklos Szeredi <mszeredi@suse.cz>

    Show peer group ID of nearest dominating group that has intersection
    with the mount's namespace.

    Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
    ---
    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);
    +}
    +
    +static struct vfsmount *get_peer_under_root(struct vfsmount *mnt,
    + struct mnt_namespace *ns,
    + const struct path *root)
    +{
    + struct vfsmount *m = mnt;
    +
    + do {
    + /* Check the namespace first for optimization */
    + if (m->mnt_ns == ns && is_path_reachable(m, m->mnt_root, root))
    + return m;
    +
    + m = next_peer(m);
    + } while (m != mnt);
    +
    + return NULL;
    +}
    +
    +/*
    + * Get ID of closest dominating peer group having a representative
    + * under the given root.
    + *
    + * Caller must hold namespace_sem
    + */
    +int get_dominating_id(struct vfsmount *mnt, const struct path *root)
    +{
    + struct vfsmount *m;
    +
    + for (m = mnt->mnt_master; m != NULL; m = m->mnt_master) {
    + struct vfsmount *d = get_peer_under_root(m, mnt->mnt_ns, root);
    + if (d)
    + return d->mnt_group_id;
    + }
    +
    + return 0;
    +}
    +
    static int do_make_slave(struct vfsmount *mnt)
    {
    struct vfsmount *peer_mnt = mnt, *master = mnt->mnt_master;
    Index: vfs-2.6/fs/pnode.h
    ===================================================================
    --- vfs-2.6.orig/fs/pnode.h 2008-03-27 12:06:10.000000000 +0100
    +++ vfs-2.6/fs/pnode.h 2008-03-27 12:06:17.000000000 +0100
    @@ -36,4 +36,5 @@ int propagate_mnt(struct vfsmount *, str
    int propagate_umount(struct list_head *);
    int propagate_mount_busy(struct vfsmount *, int);
    void mnt_release_group_id(struct vfsmount *);
    +int get_dominating_id(struct vfsmount *mnt, const struct path *root);
    #endif /* _LINUX_PNODE_H */
    --


    \
     
     \ /
      Last update: 2008-03-27 13:31    [W:0.027 / U:30.400 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site