lkml.org 
[lkml]   [2009]   [Jun]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 5/5] NFS: Correct the NFS mount path when following a referral
    From
    Date
    On Tue, 2009-06-23 at 15:42 -0500, Serge E. Hallyn wrote:
    > Quoting Trond Myklebust (Trond.Myklebust@netapp.com):
    > > Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
    > > ---
    > >
    > > fs/nfs/super.c | 24 ++++++++++++++++++++++++
    > > 1 files changed, 24 insertions(+), 0 deletions(-)
    > >
    > >
    > > diff --git a/fs/nfs/super.c b/fs/nfs/super.c
    > > index 8da7e59..daecbad 100644
    > > --- a/fs/nfs/super.c
    > > +++ b/fs/nfs/super.c
    > > @@ -2548,6 +2548,27 @@ static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
    > > return root_mnt;
    > > }
    > >
    > > +static void nfs_fix_devname(const struct path *path, struct vfsmount *mnt)
    > > +{
    > > + char *page = (char *) __get_free_page(GFP_KERNEL);
    > > + char *devname, *tmp;
    > > +
    > > + if (page == NULL)
    > > + return;
    > > + devname = nfs_path(path->mnt->mnt_devname,
    > > + path->mnt->mnt_root, path->dentry,
    > > + page, PAGE_SIZE);
    > > + if (devname == NULL)
    > > + goto out_freepage;
    > > + tmp = kstrdup(devname, GFP_KERNEL);
    > > + if (tmp == NULL)
    > > + goto out_freepage;
    > > + kfree(mnt->mnt_devname);
    > > + mnt->mnt_devname = tmp;
    >
    > (looking through patch 3 a bit) is this expected to be safe because all
    > callers will send in a mnt which was privately mounted as nfs root_mnt through
    > vfs_kern_mount? So that at this point noone else can have a ref to
    > mnt?
    >
    > If that isn't the intent, then this seems problematic... (If it is, it
    > seems worth commenting both so that every reader doesn't feel compelled
    > to verify, and so that no new callers will naively violate that
    > expectation)

    The call to nfs_fix_devname() is only applied to the 'mnt_target'
    vfsmount, which is the one that was passed down directly from
    do_kern_mount() to the ->get_sb() method. It is entirely unreferenced by
    any other process since we haven't yet called 'do_add_mount()' to
    publish it.

    Cheers
    Trond

    > thanks,
    > -serge
    >
    > > +out_freepage:
    > > + free_page((unsigned long)page);
    > > +}
    > > +
    > > static int nfs_follow_remote_path(struct vfsmount *root_mnt,
    > > const char *export_path, struct vfsmount *mnt_target)
    > > {
    > > @@ -2574,6 +2595,9 @@ static int nfs_follow_remote_path(struct vfsmount *root_mnt,
    > > mnt_target->mnt_sb = s;
    > > mnt_target->mnt_root = dget(nd.path.dentry);
    > >
    > > + /* Correct the device pathname */
    > > + nfs_fix_devname(&nd.path, mnt_target);
    > > +
    > > path_put(&nd.path);
    > > down_write(&s->s_umount);
    > > return 0;
    > >
    > > --
    > > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
    > > the body of a message to majordomo@vger.kernel.org
    > > More majordomo info at http://vger.kernel.org/majordomo-info.html

    --
    Trond Myklebust
    Linux NFS client maintainer

    NetApp
    Trond.Myklebust@netapp.com
    www.netapp.com


    \
     
     \ /
      Last update: 2009-06-23 23:19    [W:0.024 / U:29.068 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site