On Mon, Dec 11, 2017 at 05:04:05PM +1100, NeilBrown wrote: > 1/ Always return the mnt_id, even if some other error occurs. > It can be useful without the file handle. > An application can initialise the memory to, e.g. -1 > and if there is some other value after name_to_handle_at() > returns, then it is a valid mnt_id. > If the value is unchanged, then the kernel does not > have this patch.
That's interesting--not the interface we might have chosen if we were starting from scratch, but I can't see why it wouldn't work. OK! ACK.--b. > > 2/ Don't return -EINVAL if the requested handle_bytes is > larger than MAX_HANDLE_SZ. There is no need for an > error and it causes unnecessary behavior change > in the kernel ever needs to increase MAX_HANDLE_SZ. > Simple limit handle_bytes to MAX_HANDLE_SZ silently. > > Signed-off-by: NeilBrown <ne...@suse.com> > --- > fs/fhandle.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > diff --git a/fs/fhandle.c b/fs/fhandle.c > index 0ace128f5d23..04afffaeb742 100644 > --- a/fs/fhandle.c > +++ b/fs/fhandle.c > @@ -23,9 +23,16 @@ static long do_sys_name_to_handle(struct path *path, > int handle_dwords, handle_bytes; > struct file_handle *handle = NULL; > > + /* > + * Always return the mnt_id, it might be useful even > + * without the file handle > + */ > + if (copy_to_user(mnt_id, &real_mount(path->mnt)->mnt_id, > + sizeof(*mnt_id))) > + return -EFAULT; > /* > * We need to make sure whether the file system > - * support decoding of the file handle > + * supports decoding of the file handle. > */ > if (!path->dentry->d_sb->s_export_op || > !path->dentry->d_sb->s_export_op->fh_to_dentry) > @@ -35,7 +42,7 @@ static long do_sys_name_to_handle(struct path *path, > return -EFAULT; > > if (f_handle.handle_bytes > MAX_HANDLE_SZ) > - return -EINVAL; > + f_handle.handle_bytes = MAX_HANDLE_SZ; > > handle = kmalloc(sizeof(struct file_handle) + f_handle.handle_bytes, > GFP_KERNEL); > @@ -68,10 +75,7 @@ static long do_sys_name_to_handle(struct path *path, > retval = -EOVERFLOW; > } else > retval = 0; > - /* copy the mount id */ > - if (copy_to_user(mnt_id, &real_mount(path->mnt)->mnt_id, > - sizeof(*mnt_id)) || > - copy_to_user(ufh, handle, > + if (copy_to_user(ufh, handle, > sizeof(struct file_handle) + handle_bytes)) > retval = -EFAULT; > kfree(handle); > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
