On Thu, Feb 13, 2020 at 1:29 AM Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
> ...and ensure that such requests are never queued. The MDS has need to
> know that a request is asynchronous so add flags and proper
> infrastructure for that.
>
> Also, delegated inode numbers and directory caps are associated with the
> session, so ensure that async requests are always transmitted on the
> first attempt and are never queued to wait for session reestablishment.
>
> If it does end up looking like we'll need to queue the request, then
> have it return -EJUKEBOX so the caller can reattempt with a synchronous
> request.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/ceph/inode.c | 1 +
> fs/ceph/mds_client.c | 11 +++++++++++
> fs/ceph/mds_client.h | 1 +
> include/linux/ceph/ceph_fs.h | 5 +++--
> 4 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index 094b8fc37787..9869ec101e88 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -1311,6 +1311,7 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req)
> err = fill_inode(in, req->r_locked_page, &rinfo->targeti, NULL,
> session,
> (!test_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags) &&
> + !test_bit(CEPH_MDS_R_ASYNC, &req->r_req_flags) &&
> rinfo->head->result == 0) ? req->r_fmode : -1,
> &req->r_caps_reservation);
> if (err < 0) {
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 2980e57ca7b9..9f2aeb6908b2 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -2527,6 +2527,8 @@ static int __prepare_send_request(struct ceph_mds_client *mdsc,
> rhead->oldest_client_tid = cpu_to_le64(__get_oldest_tid(mdsc));
> if (test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags))
> flags |= CEPH_MDS_FLAG_REPLAY;
> + if (test_bit(CEPH_MDS_R_ASYNC, &req->r_req_flags))
> + flags |= CEPH_MDS_FLAG_ASYNC;
> if (req->r_parent)
> flags |= CEPH_MDS_FLAG_WANT_DENTRY;
> rhead->flags = cpu_to_le32(flags);
> @@ -2634,6 +2636,15 @@ static void __do_request(struct ceph_mds_client *mdsc,
> err = -EACCES;
> goto out_session;
> }
> + /*
> + * We cannot queue async requests since the caps and delegated
> + * inodes are bound to the session. Just return -EJUKEBOX and
> + * let the caller retry a sync request in that case.
> + */
> + if (test_bit(CEPH_MDS_R_ASYNC, &req->r_req_flags)) {
> + err = -EJUKEBOX;
> + goto out_session;
> + }
the code near __choose_mds also can queue request
> if (session->s_state == CEPH_MDS_SESSION_NEW ||
> session->s_state == CEPH_MDS_SESSION_CLOSING) {
> __open_session(mdsc, session);
> diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
> index 27a7446e10d3..0327974d0763 100644
> --- a/fs/ceph/mds_client.h
> +++ b/fs/ceph/mds_client.h
> @@ -255,6 +255,7 @@ struct ceph_mds_request {
> #define CEPH_MDS_R_GOT_RESULT (5) /* got a result */
> #define CEPH_MDS_R_DID_PREPOPULATE (6) /* prepopulated readdir */
> #define CEPH_MDS_R_PARENT_LOCKED (7) /* is r_parent->i_rwsem wlocked? */
> +#define CEPH_MDS_R_ASYNC (8) /* async request */
> unsigned long r_req_flags;
>
> struct mutex r_fill_mutex;
> diff --git a/include/linux/ceph/ceph_fs.h b/include/linux/ceph/ceph_fs.h
> index cb21c5cf12c3..9f747a1b8788 100644
> --- a/include/linux/ceph/ceph_fs.h
> +++ b/include/linux/ceph/ceph_fs.h
> @@ -444,8 +444,9 @@ union ceph_mds_request_args {
> } __attribute__ ((packed)) lookupino;
> } __attribute__ ((packed));
>
> -#define CEPH_MDS_FLAG_REPLAY 1 /* this is a replayed op */
> -#define CEPH_MDS_FLAG_WANT_DENTRY 2 /* want dentry in reply */
> +#define CEPH_MDS_FLAG_REPLAY 1 /* this is a replayed op */
> +#define CEPH_MDS_FLAG_WANT_DENTRY 2 /* want dentry in reply */
> +#define CEPH_MDS_FLAG_ASYNC 4 /* request is asynchronous */
>
> struct ceph_mds_request_head {
> __le64 oldest_client_tid;
> --
> 2.24.1
>
