rbd: move to obj_req->img_extents

In preparation for rbd "fancy" striping, replace obj_req->img_offset
with obj_req->img_extents.  A single starting offset isn't sufficient
because we want only one OSD request per object and will merge adjacent
object extents in ceph_file_to_extents().  The final object extent may
map into multiple different byte ranges in the image.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 568e974..0aa95e0 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -253,7 +253,8 @@ struct rbd_obj_request {
        };
 
        struct rbd_img_request  *img_request;
-       u64                     img_offset;
+       struct ceph_file_extent *img_extents;
+       u32                     num_img_extents;
 
        union {
                struct ceph_bio_iter    bio_pos;
@@ -1279,14 +1280,6 @@ static void rbd_obj_zero_range(struct rbd_obj_request *obj_req, u32 off,
        }
 }
 
-static bool obj_request_overlaps_parent(struct rbd_obj_request *obj_request)
-{
-       struct rbd_device *rbd_dev = obj_request->img_request->rbd_dev;
-
-       return obj_request->img_offset <
-           round_up(rbd_dev->parent_overlap, rbd_obj_bytes(&rbd_dev->header));
-}
-
 static void rbd_obj_request_get(struct rbd_obj_request *obj_request)
 {
        dout("%s: obj %p (was %d)\n", __func__, obj_request,
@@ -1415,6 +1408,12 @@ static bool rbd_obj_is_tail(struct rbd_obj_request *obj_req)
                                        rbd_dev->layout.object_size;
 }
 
+static u64 rbd_obj_img_extents_bytes(struct rbd_obj_request *obj_req)
+{
+       return ceph_file_extents_bytes(obj_req->img_extents,
+                                      obj_req->num_img_extents);
+}
+
 static bool rbd_img_is_write(struct rbd_img_request *img_req)
 {
        switch (img_req->op_type) {
@@ -1544,6 +1543,7 @@ static void rbd_obj_request_destroy(struct kref *kref)
                rbd_assert(0);
        }
 
+       kfree(obj_request->img_extents);
        if (obj_request->copyup_bvecs) {
                for (i = 0; i < obj_request->copyup_bvec_count; i++) {
                        if (obj_request->copyup_bvecs[i].bv_page)
@@ -1718,6 +1718,53 @@ static void rbd_parent_request_destroy(struct kref *kref)
        rbd_img_request_destroy(kref);
 }
 
+static void prune_extents(struct ceph_file_extent *img_extents,
+                         u32 *num_img_extents, u64 overlap)
+{
+       u32 cnt = *num_img_extents;
+
+       /* drop extents completely beyond the overlap */
+       while (cnt && img_extents[cnt - 1].fe_off >= overlap)
+               cnt--;
+
+       if (cnt) {
+               struct ceph_file_extent *ex = &img_extents[cnt - 1];
+
+               /* trim final overlapping extent */
+               if (ex->fe_off + ex->fe_len > overlap)
+                       ex->fe_len = overlap - ex->fe_off;
+       }
+
+       *num_img_extents = cnt;
+}
+
+/*
+ * Determine the byte range(s) covered by either just the object extent
+ * or the entire object in the parent image.
+ */
+static int rbd_obj_calc_img_extents(struct rbd_obj_request *obj_req,
+                                   bool entire)
+{
+       struct rbd_device *rbd_dev = obj_req->img_request->rbd_dev;
+       int ret;
+
+       if (!rbd_dev->parent_overlap)
+               return 0;
+
+       ret = ceph_extent_to_file(&rbd_dev->layout, obj_req->ex.oe_objno,
+                                 entire ? 0 : obj_req->ex.oe_off,
+                                 entire ? rbd_dev->layout.object_size :
+                                                       obj_req->ex.oe_len,
+                                 &obj_req->img_extents,
+                                 &obj_req->num_img_extents);
+       if (ret)
+               return ret;
+
+       prune_extents(obj_req->img_extents, &obj_req->num_img_extents,
+                     rbd_dev->parent_overlap);
+       return 0;
+}
+
 static void rbd_osd_req_setup_data(struct rbd_obj_request *obj_req, u32 which)
 {
        switch (obj_req->img_request->data_type) {
@@ -1803,7 +1850,12 @@ static int rbd_obj_setup_write(struct rbd_obj_request *obj_req)
        unsigned int num_osd_ops, which = 0;
        int ret;
 
-       if (obj_request_overlaps_parent(obj_req)) {
+       /* reverse map the entire object onto the parent */
+       ret = rbd_obj_calc_img_extents(obj_req, true);
+       if (ret)
+               return ret;
+
+       if (obj_req->num_img_extents) {
                obj_req->write_state = RBD_OBJ_WRITE_GUARD;
                num_osd_ops = 3; /* stat + setallochint + write/writefull */
        } else {
@@ -1815,7 +1867,7 @@ static int rbd_obj_setup_write(struct rbd_obj_request *obj_req)
        if (!obj_req->osd_req)
                return -ENOMEM;
 
-       if (obj_request_overlaps_parent(obj_req)) {
+       if (obj_req->num_img_extents) {
                ret = __rbd_obj_setup_stat(obj_req, which++);
                if (ret)
                        return ret;
@@ -1831,7 +1883,7 @@ static void __rbd_obj_setup_discard(struct rbd_obj_request *obj_req,
        u16 opcode;
 
        if (rbd_obj_is_entire(obj_req)) {
-               if (obj_request_overlaps_parent(obj_req)) {
+               if (obj_req->num_img_extents) {
                        opcode = CEPH_OSD_OP_TRUNCATE;
                } else {
                        osd_req_op_init(obj_req->osd_req, which++,
@@ -1858,11 +1910,16 @@ static int rbd_obj_setup_discard(struct rbd_obj_request *obj_req)
        unsigned int num_osd_ops, which = 0;
        int ret;
 
+       /* reverse map the entire object onto the parent */
+       ret = rbd_obj_calc_img_extents(obj_req, true);
+       if (ret)
+               return ret;
+
        if (rbd_obj_is_entire(obj_req)) {
                obj_req->write_state = RBD_OBJ_WRITE_FLAT;
                num_osd_ops = 1; /* truncate/delete */
        } else {
-               if (obj_request_overlaps_parent(obj_req)) {
+               if (obj_req->num_img_extents) {
                        obj_req->write_state = RBD_OBJ_WRITE_GUARD;
                        num_osd_ops = 2; /* stat + truncate/zero */
                } else {
@@ -1875,8 +1932,7 @@ static int rbd_obj_setup_discard(struct rbd_obj_request *obj_req)
        if (!obj_req->osd_req)
                return -ENOMEM;
 
-       if (!rbd_obj_is_entire(obj_req) &&
-           obj_request_overlaps_parent(obj_req)) {
+       if (!rbd_obj_is_entire(obj_req) && obj_req->num_img_extents) {
                ret = __rbd_obj_setup_stat(obj_req, which++);
                if (ret)
                        return ret;
@@ -1980,8 +2036,6 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request,
                        ceph_bvec_iter_advance(&bvec_it, length);
                }
 
-               obj_request->img_offset = img_offset;
-
                img_offset += length;
                resid -= length;
        }
@@ -2009,14 +2063,15 @@ static void rbd_img_request_submit(struct rbd_img_request *img_request)
        rbd_img_request_put(img_request);
 }
 
-static int rbd_obj_read_from_parent(struct rbd_obj_request *obj_req,
-                                   u64 img_offset, u32 bytes)
+static int rbd_obj_read_from_parent(struct rbd_obj_request *obj_req)
 {
        struct rbd_img_request *img_req = obj_req->img_request;
        struct rbd_img_request *child_img_req;
        int ret;
 
-       child_img_req = rbd_parent_request_create(obj_req, img_offset, bytes);
+       child_img_req = rbd_parent_request_create(obj_req,
+                                       obj_req->img_extents[0].fe_off,
+                                       obj_req->img_extents[0].fe_len);
        if (!child_img_req)
                return -ENOMEM;
 
@@ -2038,7 +2093,7 @@ static int rbd_obj_read_from_parent(struct rbd_obj_request *obj_req,
        } else {
                struct ceph_bvec_iter it = {
                        .bvecs = obj_req->copyup_bvecs,
-                       .iter = { .bi_size = bytes },
+                       .iter = { .bi_size = obj_req->img_extents[0].fe_len },
                };
 
                ret = rbd_img_request_fill(child_img_req, OBJ_REQUEST_BVECS,
@@ -2059,19 +2114,23 @@ static bool rbd_obj_handle_read(struct rbd_obj_request *obj_req)
        int ret;
 
        if (obj_req->result == -ENOENT &&
-           obj_req->img_offset < rbd_dev->parent_overlap &&
-           !obj_req->tried_parent) {
-               u64 obj_overlap = min(obj_req->ex.oe_len,
-                             rbd_dev->parent_overlap - obj_req->img_offset);
-
-               obj_req->tried_parent = true;
-               ret = rbd_obj_read_from_parent(obj_req, obj_req->img_offset,
-                                              obj_overlap);
+           rbd_dev->parent_overlap && !obj_req->tried_parent) {
+               /* reverse map this object extent onto the parent */
+               ret = rbd_obj_calc_img_extents(obj_req, false);
                if (ret) {
                        obj_req->result = ret;
                        return true;
                }
-               return false;
+
+               if (obj_req->num_img_extents) {
+                       obj_req->tried_parent = true;
+                       ret = rbd_obj_read_from_parent(obj_req);
+                       if (ret) {
+                               obj_req->result = ret;
+                               return true;
+                       }
+                       return false;
+               }
        }
 
        /*
@@ -2189,11 +2248,12 @@ static int setup_copyup_bvecs(struct rbd_obj_request *obj_req, u64 obj_overlap)
 static int rbd_obj_handle_write_guard(struct rbd_obj_request *obj_req)
 {
        struct rbd_device *rbd_dev = obj_req->img_request->rbd_dev;
-       u64 img_offset;
-       u64 obj_overlap;
        int ret;
 
-       if (!obj_request_overlaps_parent(obj_req)) {
+       rbd_assert(obj_req->num_img_extents);
+       prune_extents(obj_req->img_extents, &obj_req->num_img_extents,
+                     rbd_dev->parent_overlap);
+       if (!obj_req->num_img_extents) {
                /*
                 * The overlap has become 0 (most likely because the
                 * image has been flattened).  Use rbd_obj_issue_copyup()
@@ -2207,29 +2267,12 @@ static int rbd_obj_handle_write_guard(struct rbd_obj_request *obj_req)
                return rbd_obj_issue_copyup(obj_req, 0);
        }
 
-       /*
-        * Determine the byte range covered by the object in the
-        * child image to which the original request was to be sent.
-        */
-       img_offset = obj_req->img_offset - obj_req->ex.oe_off;
-       obj_overlap = rbd_dev->layout.object_size;
-
-       /*
-        * There is no defined parent data beyond the parent
-        * overlap, so limit what we read at that boundary if
-        * necessary.
-        */
-       if (img_offset + obj_overlap > rbd_dev->parent_overlap) {
-               rbd_assert(img_offset < rbd_dev->parent_overlap);
-               obj_overlap = rbd_dev->parent_overlap - img_offset;
-       }
-
-       ret = setup_copyup_bvecs(obj_req, obj_overlap);
+       ret = setup_copyup_bvecs(obj_req, rbd_obj_img_extents_bytes(obj_req));
        if (ret)
                return ret;
 
        obj_req->write_state = RBD_OBJ_WRITE_COPYUP;
-       return rbd_obj_read_from_parent(obj_req, img_offset, obj_overlap);
+       return rbd_obj_read_from_parent(obj_req);
 }
 
 static bool rbd_obj_handle_write(struct rbd_obj_request *obj_req)
@@ -2335,6 +2378,9 @@ static void rbd_img_end_child_request(struct rbd_img_request *img_req)
        struct rbd_obj_request *obj_req = img_req->obj_request;
 
        rbd_assert(test_bit(IMG_REQ_CHILD, &img_req->flags));
+       rbd_assert((!img_req->result &&
+                   img_req->xferred == rbd_obj_img_extents_bytes(obj_req)) ||
+                  (img_req->result < 0 && !img_req->xferred));
 
        obj_req->result = img_req->result;
        obj_req->xferred = img_req->xferred;