rbd: round off and ignore discards that are too small

If, after rounding off, the discard request is smaller than alloc_size,
drop it on the floor in __rbd_img_fill_request().

Default alloc_size to 64k.  This should cover both HDD and SSD based
bluestore OSDs and somewhat improve things for filestore.  For OSDs on
filestore with filestore_punch_hole = false, alloc_size is best set to
object size in order to allow deletes and truncates and disallow zero
op.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Jason Dillaman <dillaman@redhat.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 3ef97121a8f54a3eaf23823247eb0305c095c9c3..3bd1af5a3d931b8eaeb4dcbe22a8324c74cf50e4 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -733,6 +733,7 @@ static struct rbd_client *rbd_client_find(struct ceph_options *ceph_opts)
  */
 enum {
        Opt_queue_depth,
+       Opt_alloc_size,
        Opt_lock_timeout,
        Opt_last_int,
        /* int args above */
@@ -749,6 +750,7 @@ enum {
 
 static match_table_t rbd_opts_tokens = {
        {Opt_queue_depth, "queue_depth=%d"},
+       {Opt_alloc_size, "alloc_size=%d"},
        {Opt_lock_timeout, "lock_timeout=%d"},
        /* int args above */
        {Opt_pool_ns, "_pool_ns=%s"},
@@ -765,6 +767,7 @@ static match_table_t rbd_opts_tokens = {
 
 struct rbd_options {
        int     queue_depth;
+       int     alloc_size;
        unsigned long   lock_timeout;
        bool    read_only;
        bool    lock_on_read;
@@ -773,6 +776,7 @@ struct rbd_options {
 };
 
 #define RBD_QUEUE_DEPTH_DEFAULT        BLKDEV_MAX_RQ
+#define RBD_ALLOC_SIZE_DEFAULT (64 * 1024)
 #define RBD_LOCK_TIMEOUT_DEFAULT 0  /* no timeout */
 #define RBD_READ_ONLY_DEFAULT  false
 #define RBD_LOCK_ON_READ_DEFAULT false
@@ -812,6 +816,17 @@ static int parse_rbd_opts_token(char *c, void *private)
                }
                pctx->opts->queue_depth = intval;
                break;
+       case Opt_alloc_size:
+               if (intval < 1) {
+                       pr_err("alloc_size out of range\n");
+                       return -EINVAL;
+               }
+               if (!is_power_of_2(intval)) {
+                       pr_err("alloc_size must be a power of 2\n");
+                       return -EINVAL;
+               }
+               pctx->opts->alloc_size = intval;
+               break;
        case Opt_lock_timeout:
                /* 0 is "wait forever" (i.e. infinite timeout) */
                if (intval < 0 || intval > INT_MAX / 1000) {
@@ -1853,8 +1868,27 @@ static u16 truncate_or_zero_opcode(struct rbd_obj_request *obj_req)
 
 static int rbd_obj_setup_discard(struct rbd_obj_request *obj_req)
 {
+       struct rbd_device *rbd_dev = obj_req->img_request->rbd_dev;
+       u64 off = obj_req->ex.oe_off;
+       u64 next_off = obj_req->ex.oe_off + obj_req->ex.oe_len;
        int ret;
 
+       /*
+        * Align the range to alloc_size boundary and punt on discards
+        * that are too small to free up any space.
+        *
+        * alloc_size == object_size && is_tail() is a special case for
+        * filestore with filestore_punch_hole = false, needed to allow
+        * truncate (in addition to delete).
+        */
+       if (rbd_dev->opts->alloc_size != rbd_dev->layout.object_size ||
+           !rbd_obj_is_tail(obj_req)) {
+               off = round_up(off, rbd_dev->opts->alloc_size);
+               next_off = round_down(next_off, rbd_dev->opts->alloc_size);
+               if (off >= next_off)
+                       return 1;
+       }
+
        /* reverse map the entire object onto the parent */
        ret = rbd_obj_calc_img_extents(obj_req, true);
        if (ret)
@@ -1867,10 +1901,12 @@ static int rbd_obj_setup_discard(struct rbd_obj_request *obj_req)
        if (rbd_obj_is_entire(obj_req) && !obj_req->num_img_extents) {
                osd_req_op_init(obj_req->osd_req, 0, CEPH_OSD_OP_DELETE, 0);
        } else {
+               dout("%s %p %llu~%llu -> %llu~%llu\n", __func__,
+                    obj_req, obj_req->ex.oe_off, obj_req->ex.oe_len,
+                    off, next_off - off);
                osd_req_op_extent_init(obj_req->osd_req, 0,
                                       truncate_or_zero_opcode(obj_req),
-                                      obj_req->ex.oe_off, obj_req->ex.oe_len,
-                                      0, 0);
+                                      off, next_off - off, 0, 0);
        }
 
        obj_req->write_state = RBD_OBJ_WRITE_FLAT;
@@ -1953,10 +1989,10 @@ static int rbd_obj_setup_zeroout(struct rbd_obj_request *obj_req)
  */
 static int __rbd_img_fill_request(struct rbd_img_request *img_req)
 {
-       struct rbd_obj_request *obj_req;
+       struct rbd_obj_request *obj_req, *next_obj_req;
        int ret;
 
-       for_each_obj_request(img_req, obj_req) {
+       for_each_obj_request_safe(img_req, obj_req, next_obj_req) {
                switch (img_req->op_type) {
                case OBJ_OP_READ:
                        ret = rbd_obj_setup_read(obj_req);
@@ -1973,8 +2009,14 @@ static int __rbd_img_fill_request(struct rbd_img_request *img_req)
                default:
                        rbd_assert(0);
                }
-               if (ret)
+               if (ret < 0)
                        return ret;
+               if (ret > 0) {
+                       img_req->xferred += obj_req->ex.oe_len;
+                       img_req->pending_count--;
+                       rbd_img_obj_request_del(img_req, obj_req);
+                       continue;
+               }
 
                ret = ceph_osdc_alloc_messages(obj_req->osd_req, GFP_NOIO);
                if (ret)
@@ -3764,7 +3806,7 @@ static void rbd_queue_workfn(struct work_struct *work)
        else
                result = rbd_img_fill_from_bio(img_request, offset, length,
                                               rq->bio);
-       if (result)
+       if (result || !img_request->pending_count)
                goto err_img_request;
 
        rbd_img_request_submit(img_request);
@@ -5425,6 +5467,7 @@ static int rbd_add_parse_args(const char *buf,
 
        pctx.opts->read_only = RBD_READ_ONLY_DEFAULT;
        pctx.opts->queue_depth = RBD_QUEUE_DEPTH_DEFAULT;
+       pctx.opts->alloc_size = RBD_ALLOC_SIZE_DEFAULT;
        pctx.opts->lock_timeout = RBD_LOCK_TIMEOUT_DEFAULT;
        pctx.opts->lock_on_read = RBD_LOCK_ON_READ_DEFAULT;
        pctx.opts->exclusive = RBD_EXCLUSIVE_DEFAULT;
@@ -5922,6 +5965,12 @@ static ssize_t do_rbd_add(struct bus_type *bus,
        if (rbd_dev->spec->snap_id != CEPH_NOSNAP)
                rbd_dev->opts->read_only = true;
 
+       if (rbd_dev->opts->alloc_size > rbd_dev->layout.object_size) {
+               rbd_warn(rbd_dev, "alloc_size adjusted to %u",
+                        rbd_dev->layout.object_size);
+               rbd_dev->opts->alloc_size = rbd_dev->layout.object_size;
+       }
+
        rc = rbd_dev_device_setup(rbd_dev);
        if (rc)
                goto err_out_image_probe;