Re: [RFC PATCH 21/35] libceph: Make notify code use ceph_databuf_enc_start/stop

Viacheslav Dubeyko
2025-03-18T20:13:06Z

On Thu, 2025-03-13 at 23:33 +0000, David Howells wrote:
> Make the ceph_osdc_notify*() functions use ceph_databuf_enc_start() and
> ceph_databuf_enc_stop() when filling out the request data. Also use
> ceph_encode_*() rather than ceph_databuf_encode_*() as the latter will do
> an iterator copy to deal with page crossing and misalignment (the latter
> being something that the CPU will handle on some arches).
>
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: Viacheslav Dubeyko <slava@dubeyko.com>
> cc: Alex Markuze <amarkuze@redhat.com>
> cc: Ilya Dryomov <idryomov@gmail.com>
> cc: ceph-devel@vger.kernel.org
> cc: linux-fsdevel@vger.kernel.org
> ---
> net/ceph/osd_client.c | 55 +++++++++++++++++++++----------------------
> 1 file changed, 27 insertions(+), 28 deletions(-)
>
> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> index 0ac439e7e730..1a0cb2cdcc52 100644
> --- a/net/ceph/osd_client.c
> +++ b/net/ceph/osd_client.c
> @@ -4759,7 +4759,10 @@ static int osd_req_op_notify_ack_init(struct ceph_osd_request *req, int which,
> {
> struct ceph_osd_req_op *op;
> struct ceph_databuf *dbuf;
> - int ret;
> + void *p;
> +
> + if (!payload)
> + payload_len = 0;
>
> op = osd_req_op_init(req, which, CEPH_OSD_OP_NOTIFY_ACK, 0);
>
> @@ -4767,18 +4770,13 @@ static int osd_req_op_notify_ack_init(struct ceph_osd_request *req, int which,
> if (!dbuf)
> return -ENOMEM;
>
> - ret = ceph_databuf_encode_64(dbuf, notify_id);
> - ret |= ceph_databuf_encode_64(dbuf, cookie);
> - if (payload) {
> - ret |= ceph_databuf_encode_32(dbuf, payload_len);
> - ret |= ceph_databuf_append(dbuf, payload, payload_len);
> - } else {
> - ret |= ceph_databuf_encode_32(dbuf, 0);
> - }
> - if (ret) {
> - ceph_databuf_release(dbuf);
> - return -ENOMEM;
> - }
> + p = ceph_databuf_enc_start(dbuf);
> + ceph_encode_64(&p, notify_id);
> + ceph_encode_64(&p, cookie);
> + ceph_encode_32(&p, payload_len);
> + if (payload)
> + ceph_encode_copy(&p, payload, payload_len);
> + ceph_databuf_enc_stop(dbuf, p);
>
> ceph_osd_databuf_init(&op->notify_ack.request_data, dbuf);
> op->indata_len = ceph_databuf_len(dbuf);
> @@ -4840,8 +4838,12 @@ int ceph_osdc_notify(struct ceph_osd_client *osdc,
> size_t *preply_len)
> {
> struct ceph_osd_linger_request *lreq;
> + void *p;
> int ret;
>
> + if (WARN_ON_ONCE(payload_len > PAGE_SIZE - 3 * 4))

Why PAGE_SIZE - 3 * 4? Could make this more clear here?

> + return -EIO;
> +
> WARN_ON(!timeout);
> if (preply_pages) {
> *preply_pages = NULL;
> @@ -4852,20 +4854,19 @@ int ceph_osdc_notify(struct ceph_osd_client *osdc,
> if (!lreq)
> return -ENOMEM;
>
> - lreq->request_pl = ceph_databuf_req_alloc(1, PAGE_SIZE, GFP_NOIO);
> + lreq->request_pl = ceph_databuf_req_alloc(0, 3 * 4 + payload_len,

The same question... :)

Thanks,
Slava.

> + GFP_NOIO);
> if (!lreq->request_pl) {
> ret = -ENOMEM;
> goto out_put_lreq;
> }
>
> - ret = ceph_databuf_encode_32(lreq->request_pl, 1); /* prot_ver */
> - ret |= ceph_databuf_encode_32(lreq->request_pl, timeout);
> - ret |= ceph_databuf_encode_32(lreq->request_pl, payload_len);
> - ret |= ceph_databuf_append(lreq->request_pl, payload, payload_len);
> - if (ret) {
> - ret = -ENOMEM;
> - goto out_put_lreq;
> - }
> + p = ceph_databuf_enc_start(lreq->request_pl);
> + ceph_encode_32(&p, 1); /* prot_ver */
> + ceph_encode_32(&p, timeout);
> + ceph_encode_32(&p, payload_len);
> + ceph_encode_copy(&p, payload, payload_len);
> + ceph_databuf_enc_stop(lreq->request_pl, p);
>
> /* for notify_id */
> lreq->notify_id_buf = ceph_databuf_reply_alloc(1, PAGE_SIZE, GFP_NOIO);
> @@ -5217,7 +5218,7 @@ int osd_req_op_copy_from_init(struct ceph_osd_request *req,
> {
> struct ceph_osd_req_op *op;
> struct ceph_databuf *dbuf;
> - void *p, *end;
> + void *p;
>
> dbuf = ceph_databuf_req_alloc(1, PAGE_SIZE, GFP_KERNEL);
> if (!dbuf)
> @@ -5230,15 +5231,13 @@ int osd_req_op_copy_from_init(struct ceph_osd_request *req,
> op->copy_from.flags = copy_from_flags;
> op->copy_from.src_fadvise_flags = src_fadvise_flags;
>
> - p = kmap_ceph_databuf_page(dbuf, 0);
> - end = p + PAGE_SIZE;
> + p = ceph_databuf_enc_start(dbuf);
> ceph_encode_string(&p, src_oid->name, src_oid->name_len);
> encode_oloc(&p, src_oloc);
> ceph_encode_32(&p, truncate_seq);
> ceph_encode_64(&p, truncate_size);
> - op->indata_len = PAGE_SIZE - (end - p);
> - ceph_databuf_added_data(dbuf, op->indata_len);
> - kunmap_local(p);
> + ceph_databuf_enc_stop(dbuf, p);
> + op->indata_len = ceph_databuf_len(dbuf);
>
> ceph_osd_databuf_init(&op->copy_from.osd_data, dbuf);
> return 0;
>