Hi,
On 03/04/09 1:25 -0700, Nicholas A. Bellinger wrote:
> Hi Joel and co,
>
> This patch adds struct configfs_item_operations->check_link() and
> changes fs/configfs/symlink.c:configfs_unlink() so that
> when (*check_link) is present, an ConfigFS unlink will fail, based upon
> input by said symlinked struct config_item *parent_item.
>
> If a non zero return is returned from (*check_link), said non zero value is
> expected to use include/asm-generic/errno* values, and the failure is returned
> to userspace via the unlink(2) system call.
>
> Please consider this patch for v2.6.30. It requires no changes to existing consumers
> of ConfigFS like fs/ocfs2, and I have tested it with running LIO-Target v3.0 code.
>
> Many thanks for your most valuable of time,
I can't judge the actual need for that since I don't really know your usecase
(I've seen the second patch). However check_link() without target_item as
parameter looks a bit restrictive for no valuable reason.
See inline for a concern about the error returned.
Other than that, the patch looks ok.
Louis
>
> --nab
>
> Signed-off-by: Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx>
> ---
> fs/configfs/symlink.c | 13 +++++++++++++
> include/linux/configfs.h | 1 +
> 2 files changed, 14 insertions(+), 0 deletions(-)
>
> diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c
> index 932a92b..a5dede6 100644
> --- a/fs/configfs/symlink.c
> +++ b/fs/configfs/symlink.c
> @@ -202,6 +202,19 @@ int configfs_unlink(struct inode *dir, struct dentry *dentry)
> parent_item = configfs_get_config_item(dentry->d_parent);
> type = parent_item->ci_type;
>
> + /*
> + * See if the underlying struct config_item has dependent
> + * symlinks, and should return -EACCES here.
> + */
I think that -EPERM is more natural than -EACCES. check_link() actually checks
that the operation is permitted.
> + if (type && type->ct_item_ops &&
> + type->ct_item_ops->check_link) {
> + ret = type->ct_item_ops->check_link(parent_item);
> + if (ret != 0) {
> + config_item_put(parent_item);
> + goto out;
> + }
> + }
> +
> spin_lock(&configfs_dirent_lock);
> list_del_init(&sd->s_sibling);
> spin_unlock(&configfs_dirent_lock);
> diff --git a/include/linux/configfs.h b/include/linux/configfs.h
> index 7f62777..b026f16 100644
> --- a/include/linux/configfs.h
> +++ b/include/linux/configfs.h
> @@ -226,6 +226,7 @@ struct configfs_item_operations {
> ssize_t (*show_attribute)(struct config_item *, struct configfs_attribute *,char *);
> ssize_t (*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t);
> int (*allow_link)(struct config_item *src, struct config_item *target);
> + int (*check_link)(struct config_item *src);
> int (*drop_link)(struct config_item *src, struct config_item *target);
> };
>
> --
> 1.5.4.1
>
>
>
> --
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--
Dr Louis Rilling Kerlabs
Skype: louis.rilling Batiment Germanium
Phone: (+33|0) 6 80 89 08 23 80 avenue des Buttes de Coesmes
http://www.kerlabs.com/ 35700 Rennes
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