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SubjectRe: [PATCH net-next 3/8] fs/quota: use nla_put_u64_64bit()
On Tue 26-04-16 10:06:13, Nicolas Dichtel wrote:
> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>

OK, so I somewhat miss a description of what will this do to the netlink
message so that I can judge whether the change is fine for the userspace
counterpart parsing these messages. AFAIU this changes the message format
by adding a QUOTA_NL_A_PAD field before each 64-bit field which needs an
alignment, am I guessing right? Thus when the userspace counterpart uses
genlmsg_parse() it should just silently ignore these attributes if I read
the documentation right. Did I understand this correctly?

Honza

> ---
> fs/quota/netlink.c | 12 +++++++-----
> include/uapi/linux/quota.h | 1 +
> 2 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/fs/quota/netlink.c b/fs/quota/netlink.c
> index d07a2f91d858..8b252673d454 100644
> --- a/fs/quota/netlink.c
> +++ b/fs/quota/netlink.c
> @@ -47,7 +47,7 @@ void quota_send_warning(struct kqid qid, dev_t dev,
> void *msg_head;
> int ret;
> int msg_size = 4 * nla_total_size(sizeof(u32)) +
> - 2 * nla_total_size(sizeof(u64));
> + 2 * nla_total_size_64bit(sizeof(u64));
>
> /* We have to allocate using GFP_NOFS as we are called from a
> * filesystem performing write and thus further recursion into
> @@ -68,8 +68,9 @@ void quota_send_warning(struct kqid qid, dev_t dev,
> ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, qid.type);
> if (ret)
> goto attr_err_out;
> - ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID,
> - from_kqid_munged(&init_user_ns, qid));
> + ret = nla_put_u64_64bit(skb, QUOTA_NL_A_EXCESS_ID,
> + from_kqid_munged(&init_user_ns, qid),
> + QUOTA_NL_A_PAD);
> if (ret)
> goto attr_err_out;
> ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
> @@ -81,8 +82,9 @@ void quota_send_warning(struct kqid qid, dev_t dev,
> ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));
> if (ret)
> goto attr_err_out;
> - ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID,
> - from_kuid_munged(&init_user_ns, current_uid()));
> + ret = nla_put_u64_64bit(skb, QUOTA_NL_A_CAUSED_ID,
> + from_kuid_munged(&init_user_ns, current_uid()),
> + QUOTA_NL_A_PAD);
> if (ret)
> goto attr_err_out;
> genlmsg_end(skb, msg_head);
> diff --git a/include/uapi/linux/quota.h b/include/uapi/linux/quota.h
> index 38baddb807f5..4d2489ef6f10 100644
> --- a/include/uapi/linux/quota.h
> +++ b/include/uapi/linux/quota.h
> @@ -191,6 +191,7 @@ enum {
> QUOTA_NL_A_DEV_MAJOR,
> QUOTA_NL_A_DEV_MINOR,
> QUOTA_NL_A_CAUSED_ID,
> + QUOTA_NL_A_PAD,
> __QUOTA_NL_A_MAX,
> };
> #define QUOTA_NL_A_MAX (__QUOTA_NL_A_MAX - 1)
> --
> 2.8.1
>
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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