[RFC PATCH 22/35] libceph, rbd: Convert ceph_osdc_notify() reply to ceph_databuf

David Howells
2025-03-13T23:35:18Z

Convert the reply buffer of ceph_osdc_notify() to ceph_databuf rather than
an array of pages.

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
---
drivers/block/rbd.c | 36 +++++++++++++++++----------
include/linux/ceph/databuf.h | 16 ++++++++++++
include/linux/ceph/osd_client.h | 7 ++----
net/ceph/osd_client.c | 44 +++++++++++----------------------
4 files changed, 55 insertions(+), 48 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index eea12c7ab2a0..a2674077edea 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -3585,8 +3585,7 @@ static void rbd_unlock(struct rbd_device *rbd_dev)

static int __rbd_notify_op_lock(struct rbd_device *rbd_dev,
enum rbd_notify_op notify_op,
- struct page ***preply_pages,
- size_t *preply_len)
+ struct ceph_databuf *reply)
{
struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
struct rbd_client_id cid = rbd_get_cid(rbd_dev);
@@ -3604,13 +3603,13 @@ static int __rbd_notify_op_lock(struct rbd_device *rbd_dev,

return ceph_osdc_notify(osdc, &rbd_dev->header_oid,
&rbd_dev->header_oloc, buf, buf_size,
- RBD_NOTIFY_TIMEOUT, preply_pages, preply_len);
+ RBD_NOTIFY_TIMEOUT, reply);
}

static void rbd_notify_op_lock(struct rbd_device *rbd_dev,
enum rbd_notify_op notify_op)
{
- __rbd_notify_op_lock(rbd_dev, notify_op, NULL, NULL);
+ __rbd_notify_op_lock(rbd_dev, notify_op, NULL);
}

static void rbd_notify_acquired_lock(struct work_struct *work)
@@ -3631,23 +3630,29 @@ static void rbd_notify_released_lock(struct work_struct *work)

static int rbd_request_lock(struct rbd_device *rbd_dev)
{
- struct page **reply_pages;
- size_t reply_len;
+ struct ceph_databuf *reply;
bool lock_owner_responded = false;
int ret;

dout("%s rbd_dev %p\n", __func__, rbd_dev);

- ret = __rbd_notify_op_lock(rbd_dev, RBD_NOTIFY_OP_REQUEST_LOCK,
- &reply_pages, &reply_len);
+ /* The actual reply pages will be allocated in the read path and then
+ * pasted in in handle_watch_notify().
+ */
+ reply = ceph_databuf_reply_alloc(0, 0, GFP_KERNEL);
+ if (!reply)
+ return -ENOMEM;
+
+ ret = __rbd_notify_op_lock(rbd_dev, RBD_NOTIFY_OP_REQUEST_LOCK, reply);
if (ret && ret != -ETIMEDOUT) {
rbd_warn(rbd_dev, "failed to request lock: %d", ret);
goto out;
}

- if (reply_len > 0 && reply_len <= PAGE_SIZE) {
- void *p = page_address(reply_pages[0]);
- void *const end = p + reply_len;
+ if (ceph_databuf_len(reply) > 0 && ceph_databuf_len(reply) <= PAGE_SIZE) {
+ void *s = kmap_ceph_databuf_page(reply, 0);
+ void *p = s;
+ void *const end = p + ceph_databuf_len(reply);
u32 n;

ceph_decode_32_safe(&p, end, n, e_inval); /* num_acks */
@@ -3659,10 +3664,12 @@ static int rbd_request_lock(struct rbd_device *rbd_dev)
p += 8 + 8; /* skip gid and cookie */

ceph_decode_32_safe(&p, end, len, e_inval);
- if (!len)
+ if (!len) {
continue;
+ }

if (lock_owner_responded) {
+ kunmap_local(s);
rbd_warn(rbd_dev,
"duplicate lock owners detected");
ret = -EIO;
@@ -3673,6 +3680,7 @@ static int rbd_request_lock(struct rbd_device *rbd_dev)
ret = ceph_start_decoding(&p, end, 1, "ResponseMessage",
&struct_v, &len);
if (ret) {
+ kunmap_local(s);
rbd_warn(rbd_dev,
"failed to decode ResponseMessage: %d",
ret);
@@ -3681,6 +3689,8 @@ static int rbd_request_lock(struct rbd_device *rbd_dev)

ret = ceph_decode_32(&p);
}
+
+ kunmap_local(s);
}

if (!lock_owner_responded) {
@@ -3689,7 +3699,7 @@ static int rbd_request_lock(struct rbd_device *rbd_dev)
}

out:
- ceph_release_page_vector(reply_pages, calc_pages_for(0, reply_len));
+ ceph_databuf_release(reply);
return ret;

e_inval:
diff --git a/include/linux/ceph/databuf.h b/include/linux/ceph/databuf.h
index 54b76d0c91a0..25154b3d08fa 100644
--- a/include/linux/ceph/databuf.h
+++ b/include/linux/ceph/databuf.h
@@ -150,4 +150,20 @@ static inline bool ceph_databuf_is_all_zero(struct ceph_databuf *dbuf, size_t co
ceph_databuf_scan_for_nonzero) == count;
}

+static inline void ceph_databuf_transfer(struct ceph_databuf *to,
+ struct ceph_databuf *from)
+{
+ BUG_ON(to->nr_bvec || to->bvec);
+ to->bvec = from->bvec;
+ to->nr_bvec = from->nr_bvec;
+ to->max_bvec = from->max_bvec;
+ to->limit = from->limit;
+ to->iter = from->iter;
+
+ from->bvec = NULL;
+ from->nr_bvec = from->max_bvec = 0;
+ from->limit = 0;
+ iov_iter_discard(&from->iter, ITER_DEST, 0);
+}
+
#endif /* __FS_CEPH_DATABUF_H */
diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index 5a1ee66ca216..7eff589711cc 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -333,9 +333,7 @@ struct ceph_osd_linger_request {

struct ceph_databuf *request_pl;
struct ceph_databuf *notify_id_buf;
-
- struct page ***preply_pages;
- size_t *preply_len;
+ struct ceph_databuf *reply;
};

struct ceph_watch_item {
@@ -589,8 +587,7 @@ int ceph_osdc_notify(struct ceph_osd_client *osdc,
void *payload,
u32 payload_len,
u32 timeout,
- struct page ***preply_pages,
- size_t *preply_len);
+ struct ceph_databuf *reply);
int ceph_osdc_list_watchers(struct ceph_osd_client *osdc,
struct ceph_object_id *oid,
struct ceph_object_locator *oloc,
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 1a0cb2cdcc52..92aaa5ed9145 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -4523,17 +4523,11 @@ static void handle_watch_notify(struct ceph_osd_client *osdc,
dout("lreq %p notify_id %llu != %llu, ignoring\n", lreq,
lreq->notify_id, notify_id);
} else if (!completion_done(&lreq->notify_finish_wait)) {
- struct ceph_msg_data *data =
- msg->num_data_items ? &msg->data[0] : NULL;
-
- if (data) {
- if (lreq->preply_pages) {
- WARN_ON(data->type !=
- CEPH_MSG_DATA_PAGES);
- *lreq->preply_pages = data->pages;
- *lreq->preply_len = data->length;
- data->own_pages = false;
- }
+ if (msg->num_data_items && lreq->reply) {
+ struct ceph_msg_data *data = &msg->data[0];
+
+ WARN_ON(data->type != CEPH_MSG_DATA_DATABUF);
+ ceph_databuf_transfer(lreq->reply, data->dbuf);
}
lreq->notify_finish_error = return_code;
complete_all(&lreq->notify_finish_wait);
@@ -4823,10 +4817,7 @@ EXPORT_SYMBOL(ceph_osdc_notify_ack);
/*
* @timeout: in seconds
*
- * @preply_{pages,len} are initialized both on success and error.
- * The caller is responsible for:
- *
- * ceph_release_page_vector(reply_pages, calc_pages_for(0, reply_len))
+ * @reply should be an empty ceph_databuf.
*/
int ceph_osdc_notify(struct ceph_osd_client *osdc,
struct ceph_object_id *oid,
@@ -4834,8 +4825,7 @@ int ceph_osdc_notify(struct ceph_osd_client *osdc,
void *payload,
u32 payload_len,
u32 timeout,
- struct page ***preply_pages,
- size_t *preply_len)
+ struct ceph_databuf *reply)
{
struct ceph_osd_linger_request *lreq;
void *p;
@@ -4845,10 +4835,6 @@ int ceph_osdc_notify(struct ceph_osd_client *osdc,
return -EIO;

WARN_ON(!timeout);
- if (preply_pages) {
- *preply_pages = NULL;
- *preply_len = 0;
- }

lreq = linger_alloc(osdc);
if (!lreq)
@@ -4875,8 +4861,7 @@ int ceph_osdc_notify(struct ceph_osd_client *osdc,
goto out_put_lreq;
}

- lreq->preply_pages = preply_pages;
- lreq->preply_len = preply_len;
+ lreq->reply = reply;

ceph_oid_copy(&lreq->t.base_oid, oid);
ceph_oloc_copy(&lreq->t.base_oloc, oloc);
@@ -5383,7 +5368,7 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
return m;
}

-static struct ceph_msg *alloc_msg_with_page_vector(struct ceph_msg_header *hdr)
+static struct ceph_msg *alloc_msg_with_data_buffer(struct ceph_msg_header *hdr)
{
struct ceph_msg *m;
int type = le16_to_cpu(hdr->type);
@@ -5395,16 +5380,15 @@ static struct ceph_msg *alloc_msg_with_page_vector(struct ceph_msg_header *hdr)
return NULL;

if (data_len) {
- struct page **pages;
+ struct ceph_databuf *dbuf;

- pages = ceph_alloc_page_vector(calc_pages_for(0, data_len),
- GFP_NOIO);
- if (IS_ERR(pages)) {
+ dbuf = ceph_databuf_reply_alloc(0, data_len, GFP_NOIO);
+ if (!dbuf) {
ceph_msg_put(m);
return NULL;
}

- ceph_msg_data_add_pages(m, pages, data_len, 0, true);
+ ceph_msg_data_add_databuf(m, dbuf);
}

return m;
@@ -5422,7 +5406,7 @@ static struct ceph_msg *osd_alloc_msg(struct ceph_connection *con,
case CEPH_MSG_OSD_MAP:
case CEPH_MSG_OSD_BACKOFF:
case CEPH_MSG_WATCH_NOTIFY:
- return alloc_msg_with_page_vector(hdr);
+ return alloc_msg_with_data_buffer(hdr);
case CEPH_MSG_OSD_OPREPLY:
return get_reply(con, hdr, skip);