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authorIlya Dryomov <idryomov@gmail.com>2019-02-28 14:20:28 +0100
committerIlya Dryomov <idryomov@gmail.com>2019-03-05 18:55:17 +0100
commit89a59c1ca73b8dd43c208cdbd3658bd302cd41b4 (patch)
tree43904f9dc9c6660cd7c1421ecaed9afbd3b45228 /drivers/block
parent3a482501cf701f56a454f9397aa96f477db87769 (diff)
rbd: copyup with an empty snapshot context (aka deep-copyup)
This is the core of deep-flatten feature: sending a copyup request (i.e. a guarded write of the data read from the parent) with an empty snapshot context (snaps = [], seq = 0) causes the OSD to reflect the write in all existing snapshots. This allows "rbd flatten" to fully disconnect the clone image and its snapshots from the parent and make the parent snapshot removable. The actual modification request is sent only after deep-copyup request is completed. Waiting for deep-copyup reply is unnecessary, this will be improved in the future. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/rbd.c89
1 files changed, 79 insertions, 10 deletions
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index aa95227fdee2..4befd8f6ac9c 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -221,22 +221,32 @@ enum obj_operation_type {
* Writes go through the following state machine to deal with
* layering:
*
- * need copyup
- * RBD_OBJ_WRITE_GUARD ---------------> RBD_OBJ_WRITE_COPYUP
- * | ^ |
- * v \------------------------------/
- * done
- * ^
- * |
- * RBD_OBJ_WRITE_FLAT
+ * . . . . . RBD_OBJ_WRITE_GUARD. . . . . . . . . . . . . .
+ * . | .
+ * . v .
+ * . RBD_OBJ_WRITE_READ_FROM_PARENT. . . .
+ * . | . .
+ * . v v (deep-copyup .
+ * (image . RBD_OBJ_WRITE_COPYUP_EMPTY_SNAPC . not needed) .
+ * flattened) v | . .
+ * . v . .
+ * . . . .RBD_OBJ_WRITE_COPYUP_OPS. . . . . (copyup .
+ * | not needed) v
+ * v .
+ * done . . . . . . . . . . . . . . . . . .
+ * ^
+ * |
+ * RBD_OBJ_WRITE_FLAT
*
* Writes start in RBD_OBJ_WRITE_GUARD or _FLAT, depending on whether
- * there is a parent or not.
+ * assert_exists guard is needed or not (in some cases it's not needed
+ * even if there is a parent).
*/
enum rbd_obj_write_state {
RBD_OBJ_WRITE_FLAT = 1,
RBD_OBJ_WRITE_GUARD,
RBD_OBJ_WRITE_READ_FROM_PARENT,
+ RBD_OBJ_WRITE_COPYUP_EMPTY_SNAPC,
RBD_OBJ_WRITE_COPYUP_OPS,
};
@@ -422,6 +432,10 @@ static DEFINE_IDA(rbd_dev_id_ida);
static struct workqueue_struct *rbd_wq;
+static struct ceph_snap_context rbd_empty_snapc = {
+ .nref = REFCOUNT_INIT(1),
+};
+
/*
* single-major requires >= 0.75 version of userspace rbd utility.
*/
@@ -2461,6 +2475,38 @@ static bool is_zero_bvecs(struct bio_vec *bvecs, u32 bytes)
#define MODS_ONLY U32_MAX
+static int rbd_obj_issue_copyup_empty_snapc(struct rbd_obj_request *obj_req,
+ u32 bytes)
+{
+ int ret;
+
+ dout("%s obj_req %p bytes %u\n", __func__, obj_req, bytes);
+ rbd_assert(obj_req->osd_req->r_ops[0].op == CEPH_OSD_OP_STAT);
+ rbd_assert(bytes > 0 && bytes != MODS_ONLY);
+ rbd_osd_req_destroy(obj_req->osd_req);
+
+ obj_req->osd_req = __rbd_osd_req_create(obj_req, &rbd_empty_snapc, 1);
+ if (!obj_req->osd_req)
+ return -ENOMEM;
+
+ ret = osd_req_op_cls_init(obj_req->osd_req, 0, "rbd", "copyup");
+ if (ret)
+ return ret;
+
+ osd_req_op_cls_request_data_bvecs(obj_req->osd_req, 0,
+ obj_req->copyup_bvecs,
+ obj_req->copyup_bvec_count,
+ bytes);
+ rbd_osd_req_format_write(obj_req);
+
+ ret = ceph_osdc_alloc_messages(obj_req->osd_req, GFP_NOIO);
+ if (ret)
+ return ret;
+
+ rbd_obj_request_submit(obj_req);
+ return 0;
+}
+
static int rbd_obj_issue_copyup_ops(struct rbd_obj_request *obj_req, u32 bytes)
{
struct rbd_img_request *img_req = obj_req->img_request;
@@ -2469,7 +2515,8 @@ static int rbd_obj_issue_copyup_ops(struct rbd_obj_request *obj_req, u32 bytes)
int ret;
dout("%s obj_req %p bytes %u\n", __func__, obj_req, bytes);
- rbd_assert(obj_req->osd_req->r_ops[0].op == CEPH_OSD_OP_STAT);
+ rbd_assert(obj_req->osd_req->r_ops[0].op == CEPH_OSD_OP_STAT ||
+ obj_req->osd_req->r_ops[0].op == CEPH_OSD_OP_CALL);
rbd_osd_req_destroy(obj_req->osd_req);
switch (img_req->op_type) {
@@ -2531,6 +2578,17 @@ static int rbd_obj_issue_copyup(struct rbd_obj_request *obj_req, u32 bytes)
bytes = 0;
}
+ if (obj_req->img_request->snapc->num_snaps && bytes > 0) {
+ /*
+ * Send a copyup request with an empty snapshot context to
+ * deep-copyup the object through all existing snapshots.
+ * A second request with the current snapshot context will be
+ * sent for the actual modification.
+ */
+ obj_req->write_state = RBD_OBJ_WRITE_COPYUP_EMPTY_SNAPC;
+ return rbd_obj_issue_copyup_empty_snapc(obj_req, bytes);
+ }
+
obj_req->write_state = RBD_OBJ_WRITE_COPYUP_OPS;
return rbd_obj_issue_copyup_ops(obj_req, bytes);
}
@@ -2632,6 +2690,17 @@ static bool rbd_obj_handle_write(struct rbd_obj_request *obj_req)
return true;
}
return false;
+ case RBD_OBJ_WRITE_COPYUP_EMPTY_SNAPC:
+ if (obj_req->result)
+ return true;
+
+ obj_req->write_state = RBD_OBJ_WRITE_COPYUP_OPS;
+ ret = rbd_obj_issue_copyup_ops(obj_req, MODS_ONLY);
+ if (ret) {
+ obj_req->result = ret;
+ return true;
+ }
+ return false;
default:
BUG();
}