[RFC PATCH 23/35] rbd: Use ceph_databuf_enc_start/stop()

David Howells
2025-03-13T23:35:20Z

Make rbd 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
---
drivers/block/rbd.c | 64 ++++++++++++++++++++++-----------------------
1 file changed, 31 insertions(+), 33 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index a2674077edea..956fc4a8f1da 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1970,19 +1970,19 @@ static int rbd_cls_object_map_update(struct ceph_osd_request *req,
int which, u64 objno, u8 new_state,
const u8 *current_state)
{
- struct ceph_databuf *dbuf;
- void *p, *start;
+ struct ceph_databuf *request;
+ void *p;
int ret;

ret = osd_req_op_cls_init(req, which, "rbd", "object_map_update");
if (ret)
return ret;

- dbuf = ceph_databuf_req_alloc(1, PAGE_SIZE, GFP_NOIO);
- if (!dbuf)
+ request = ceph_databuf_req_alloc(1, 8 * 2 + 3 * 1, GFP_NOIO);
+ if (!request)
return -ENOMEM;

- p = start = kmap_ceph_databuf_page(dbuf, 0);
+ p = ceph_databuf_enc_start(request);
ceph_encode_64(&p, objno);
ceph_encode_64(&p, objno + 1);
ceph_encode_8(&p, new_state);
@@ -1992,10 +1992,9 @@ static int rbd_cls_object_map_update(struct ceph_osd_request *req,
} else {
ceph_encode_8(&p, 0);
}
- kunmap_local(p);
- ceph_databuf_added_data(dbuf, p - start);
+ ceph_databuf_enc_stop(request, p);

- osd_req_op_cls_request_databuf(req, which, dbuf);
+ osd_req_op_cls_request_databuf(req, which, request);
return 0;
}

@@ -2108,7 +2107,7 @@ static int rbd_obj_calc_img_extents(struct rbd_obj_request *obj_req,

static int rbd_osd_setup_stat(struct ceph_osd_request *osd_req, int which)
{
- struct ceph_databuf *dbuf;
+ struct ceph_databuf *request;

/*
* The response data for a STAT call consists of:
@@ -2118,12 +2117,12 @@ static int rbd_osd_setup_stat(struct ceph_osd_request *osd_req, int which)
* le32 tv_nsec;
* } mtime;
*/
- dbuf = ceph_databuf_reply_alloc(1, 8 + sizeof(struct ceph_timespec), GFP_NOIO);
- if (!dbuf)
+ request = ceph_databuf_reply_alloc(1, 8 + sizeof(struct ceph_timespec), GFP_NOIO);
+ if (!request)
return -ENOMEM;

osd_req_op_init(osd_req, which, CEPH_OSD_OP_STAT, 0);
- osd_req_op_raw_data_in_databuf(osd_req, which, dbuf);
+ osd_req_op_raw_data_in_databuf(osd_req, which, request);
return 0;
}

@@ -2964,16 +2963,16 @@ static int rbd_obj_copyup_current_snapc(struct rbd_obj_request *obj_req,

static int setup_copyup_buf(struct rbd_obj_request *obj_req, u64 obj_overlap)
{
- struct ceph_databuf *dbuf;
+ struct ceph_databuf *request;

rbd_assert(!obj_req->copyup_buf);

- dbuf = ceph_databuf_req_alloc(calc_pages_for(0, obj_overlap),
+ request = ceph_databuf_req_alloc(calc_pages_for(0, obj_overlap),
obj_overlap, GFP_NOIO);
- if (!dbuf)
+ if (!request)
return -ENOMEM;

- obj_req->copyup_buf = dbuf;
+ obj_req->copyup_buf = request;
return 0;
}

@@ -4580,10 +4579,9 @@ static int rbd_obj_method_sync(struct rbd_device *rbd_dev,
if (!request)
return -ENOMEM;

- p = kmap_ceph_databuf_page(request, 0);
- memcpy(p, outbound, outbound_size);
- kunmap_local(p);
- ceph_databuf_added_data(request, outbound_size);
+ p = ceph_databuf_enc_start(request);
+ ceph_encode_copy(&p, outbound, outbound_size);
+ ceph_databuf_enc_stop(request, p);
}

reply = ceph_databuf_reply_alloc(1, inbound_size, GFP_KERNEL);
@@ -4712,7 +4710,7 @@ static void rbd_free_disk(struct rbd_device *rbd_dev)
static int rbd_obj_read_sync(struct rbd_device *rbd_dev,
struct ceph_object_id *oid,
struct ceph_object_locator *oloc,
- struct ceph_databuf *dbuf, int len)
+ struct ceph_databuf *request, int len)
{
struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
struct ceph_osd_request *req;
@@ -4727,7 +4725,7 @@ static int rbd_obj_read_sync(struct rbd_device *rbd_dev,
req->r_flags = CEPH_OSD_FLAG_READ;

osd_req_op_extent_init(req, 0, CEPH_OSD_OP_READ, 0, len, 0, 0);
- osd_req_op_extent_osd_databuf(req, 0, dbuf);
+ osd_req_op_extent_osd_databuf(req, 0, request);

ret = ceph_osdc_alloc_messages(req, GFP_KERNEL);
if (ret)
@@ -4750,16 +4748,16 @@ static int rbd_dev_v1_header_info(struct rbd_device *rbd_dev,
bool first_time)
{
struct rbd_image_header_ondisk *ondisk;
- struct ceph_databuf *dbuf = NULL;
+ struct ceph_databuf *request = NULL;
u32 snap_count = 0;
u64 names_size = 0;
u32 want_count;
int ret;

- dbuf = ceph_databuf_req_alloc(1, sizeof(*ondisk), GFP_KERNEL);
- if (!dbuf)
+ request = ceph_databuf_req_alloc(1, sizeof(*ondisk), GFP_KERNEL);
+ if (!request)
return -ENOMEM;
- ondisk = kmap_ceph_databuf_page(dbuf, 0);
+ ondisk = kmap_ceph_databuf_page(request, 0);

/*
* The complete header will include an array of its 64-bit
@@ -4776,13 +4774,13 @@ static int rbd_dev_v1_header_info(struct rbd_device *rbd_dev,
size += names_size;

ret = -ENOMEM;
- if (size > dbuf->limit &&
- ceph_databuf_reserve(dbuf, size - dbuf->limit,
+ if (size > request->limit &&
+ ceph_databuf_reserve(request, size - request->limit,
GFP_KERNEL) < 0)
goto out;

ret = rbd_obj_read_sync(rbd_dev, &rbd_dev->header_oid,
- &rbd_dev->header_oloc, dbuf, size);
+ &rbd_dev->header_oloc, request, size);
if (ret < 0)
goto out;
if ((size_t)ret < size) {
@@ -4806,7 +4804,7 @@ static int rbd_dev_v1_header_info(struct rbd_device *rbd_dev,
ret = rbd_header_from_disk(header, ondisk, first_time);
out:
kunmap_local(ondisk);
- ceph_databuf_release(dbuf);
+ ceph_databuf_release(request);
return ret;
}

@@ -5625,10 +5623,10 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev,
if (!reply)
goto out_free;

- p = kmap_ceph_databuf_page(request, 0);
+ p = ceph_databuf_enc_start(request);
ceph_encode_64(&p, rbd_dev->spec->snap_id);
- kunmap_local(p);
- ceph_databuf_added_data(request, sizeof(__le64));
+ ceph_databuf_enc_stop(request, p);
+
ret = __get_parent_info(rbd_dev, request, reply, pii);
if (ret > 0)
ret = __get_parent_info_legacy(rbd_dev, request, reply, pii);