On Wed, Dec 16, 2020 at 8:50 PM Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
> When we added the btime feature in mainline ceph, we had to extend
> struct ceph_mds_request_args so that it could be set. Implement the same
> in the kernel client.
>
> Rename ceph_mds_request_head with a _old extension, and a union
> ceph_mds_request_args_ext to allow for the extended size of the new
> header format.
>
> Add the appropriate code to handle both formats in struct
> create_request_message and key the behavior on whether the peer supports
> CEPH_FEATURE_FS_BTIME.
>
> The gid_list field in the payload is now populated from the saved
> credential. For now, we don't add any support for setting the btime via
> setattr, but this does enable us to add that in the future.
>
> [ idryomov: break unnecessarily long lines ]
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/ceph/mds_client.c | 101 ++++++++++++++++++++++++++---------
> include/linux/ceph/ceph_fs.h | 32 ++++++++++-
> 2 files changed, 108 insertions(+), 25 deletions(-)
>
> v2: fix encoding of unsafe request resends
> add encode_payload_tail helper
> rework find_old_request_head to take a "legacy" flag argument
>
> Ilya,
>
> I'll go ahead and merge this into testing, but your call on whether we
> should take this for v5.11, or wait for v5.12. We don't have anything
> blocked on this just yet.
>
> I dropped your SoB and Xiubo Reviewed-by tags as well, as the patch is
> a bit different from the original.
>
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 0ff76f21466a..cd0cc5d8c4f0 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -2475,15 +2475,46 @@ static int set_request_path_attr(struct inode *rinode, struct dentry *rdentry,
> return r;
> }
>
> +static struct ceph_mds_request_head_old *
> +find_old_request_head(void *p, bool legacy)
> +{
> + struct ceph_mds_request_head *new_head;
> +
> + if (legacy)
> + return (struct ceph_mds_request_head_old *)p;
> + new_head = (struct ceph_mds_request_head *)p;
> + return (struct ceph_mds_request_head_old *)&new_head->oldest_client_tid;
> +}
> +
> +static void encode_payload_tail(void **p, struct ceph_mds_request *req, bool legacy)
> +{
> + struct ceph_timespec ts;
> +
> + ceph_encode_timespec64(&ts, &req->r_stamp);
> + ceph_encode_copy(p, &ts, sizeof(ts));
> +
> + /* gid list */
> + if (!legacy) {
> + int i;
> +
> + ceph_encode_32(p, req->r_cred->group_info->ngroups);
> + for (i = 0; i < req->r_cred->group_info->ngroups; i++)
> + ceph_encode_64(p, from_kgid(&init_user_ns,
> + req->r_cred->group_info->gid[i]));
> + }
> +}
> +
> /*
> * called under mdsc->mutex
> */
> -static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
> +static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
> struct ceph_mds_request *req,
> - int mds, bool drop_cap_releases)
> + bool drop_cap_releases)
> {
> + int mds = session->s_mds;
> + struct ceph_mds_client *mdsc = session->s_mdsc;
> struct ceph_msg *msg;
> - struct ceph_mds_request_head *head;
> + struct ceph_mds_request_head_old *head;
> const char *path1 = NULL;
> const char *path2 = NULL;
> u64 ino1 = 0, ino2 = 0;
> @@ -2493,6 +2524,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
> u16 releases;
> void *p, *end;
> int ret;
> + bool legacy = !(session->s_con.peer_features & CEPH_FEATURE_FS_BTIME);
>
> ret = set_request_path_attr(req->r_inode, req->r_dentry,
> req->r_parent, req->r_path1, req->r_ino1.ino,
> @@ -2514,14 +2546,23 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
> goto out_free1;
> }
>
> - len = sizeof(*head) +
> - pathlen1 + pathlen2 + 2*(1 + sizeof(u32) + sizeof(u64)) +
> + if (legacy) {
> + /* Old style */
> + len = sizeof(*head);
> + } else {
> + /* New style: add gid_list and any later fields */
> + len = sizeof(struct ceph_mds_request_head) + sizeof(u32) +
> + (sizeof(u64) * req->r_cred->group_info->ngroups);
> + }
> +
> + len += pathlen1 + pathlen2 + 2*(1 + sizeof(u32) + sizeof(u64)) +
> sizeof(struct ceph_timespec);
>
> /* calculate (max) length for cap releases */
> len += sizeof(struct ceph_mds_request_release) *
> (!!req->r_inode_drop + !!req->r_dentry_drop +
> !!req->r_old_inode_drop + !!req->r_old_dentry_drop);
> +
> if (req->r_dentry_drop)
> len += pathlen1;
> if (req->r_old_dentry_drop)
> @@ -2533,11 +2574,25 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
> goto out_free2;
> }
>
> - msg->hdr.version = cpu_to_le16(3);
> msg->hdr.tid = cpu_to_le64(req->r_tid);
>
> - head = msg->front.iov_base;
> - p = msg->front.iov_base + sizeof(*head);
> + /*
> + * The old ceph_mds_request_header didn't contain a version field, and
> + * one was added when we moved the message version from 3->4.
> + */
> + if (legacy) {
> + msg->hdr.version = cpu_to_le16(3);
> + p = msg->front.iov_base + sizeof(*head);
> + } else {
> + struct ceph_mds_request_head *new_head = msg->front.iov_base;
> +
> + msg->hdr.version = cpu_to_le16(4);
> + new_head->version = cpu_to_le16(CEPH_MDS_REQUEST_HEAD_VERSION);
> + p = msg->front.iov_base + sizeof(*new_head);
> + }
> +
> + head = find_old_request_head(msg->front.iov_base, legacy);
> +
> end = msg->front.iov_base + msg->front.iov_len;
>
> head->mdsmap_epoch = cpu_to_le32(mdsc->mdsmap->m_epoch);
> @@ -2583,12 +2638,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
>
> head->num_releases = cpu_to_le16(releases);
>
> - /* time stamp */
> - {
> - struct ceph_timespec ts;
> - ceph_encode_timespec64(&ts, &req->r_stamp);
> - ceph_encode_copy(&p, &ts, sizeof(ts));
> - }
> + encode_payload_tail(&p, req, legacy);
>
> if (WARN_ON_ONCE(p > end)) {
> ceph_msg_put(msg);
> @@ -2642,9 +2692,10 @@ static int __prepare_send_request(struct ceph_mds_session *session,
> {
> int mds = session->s_mds;
> struct ceph_mds_client *mdsc = session->s_mdsc;
> - struct ceph_mds_request_head *rhead;
> + struct ceph_mds_request_head_old *rhead;
> struct ceph_msg *msg;
> int flags = 0;
> + bool legacy = !(session->s_con.peer_features & CEPH_FEATURE_FS_BTIME);
>
> req->r_attempts++;
> if (req->r_inode) {
> @@ -2661,6 +2712,7 @@ static int __prepare_send_request(struct ceph_mds_session *session,
>
> if (test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags)) {
> void *p;
> +
> /*
> * Replay. Do not regenerate message (and rebuild
> * paths, etc.); just use the original message.
> @@ -2668,7 +2720,7 @@ static int __prepare_send_request(struct ceph_mds_session *session,
> * d_move mangles the src name.
> */
> msg = req->r_request;
> - rhead = msg->front.iov_base;
> + rhead = find_old_request_head(msg->front.iov_base, legacy);
>
> flags = le32_to_cpu(rhead->flags);
> flags |= CEPH_MDS_FLAG_REPLAY;
> @@ -2682,13 +2734,14 @@ static int __prepare_send_request(struct ceph_mds_session *session,
> /* remove cap/dentry releases from message */
> rhead->num_releases = 0;
>
> - /* time stamp */
> + /* verify that we haven't got mixed-feature MDSs */
> + if (legacy)
> + WARN_ON_ONCE(le16_to_cpu(msg->hdr.version) >= 4);
> + else
> + WARN_ON_ONCE(le16_to_cpu(msg->hdr.version) < 4);
As mentioned in the ticket, I already did a minimal encode_gid_list()
helper -- just haven't pushed because I had to leave. Looking at this,
I not clear on why even bother with v3 vs v4 and the legacy branch.
The only that is conditional on CEPH_FEATURE_FS_BTIME is the head, we
can encode gids and set the version to 4 unconditionally.
Thanks,
Ilya
