blk-cgroup: Introduce cgroup changes for throttling policy

o cgroup chagnes for throttle policy.

o Introduces READ and WRITE bytes per second throttling rules.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

2 files changed, 167 insertions, 8 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 7762987fdf9e..aae8c930a6f8 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -128,6 +128,27 @@ blkio_update_group_weight(struct blkio_group *blkg, unsigned int weight)
         }
 }
 
+static inline void blkio_update_group_bps(struct blkio_group *blkg, u64 bps,
+                                int fileid)
+{
+        struct blkio_policy_type *blkiop;
+
+        list_for_each_entry(blkiop, &blkio_list, list) {
+
+                /* If this policy does not own the blkg, do not send updates */
+                if (blkiop->plid != blkg->plid)
+                        continue;
+
+                if (fileid == BLKIO_THROTL_read_bps_device
+                    && blkiop->ops.blkio_update_group_read_bps_fn)
+                        blkiop->ops.blkio_update_group_read_bps_fn(blkg, bps);
+
+                if (fileid == BLKIO_THROTL_write_bps_device
+                    && blkiop->ops.blkio_update_group_write_bps_fn)
+                        blkiop->ops.blkio_update_group_write_bps_fn(blkg, bps);
+        }
+}
+
 /*
  * Add to the appropriate stat variable depending on the request type.
  * This should be called with the blkg->stats_lock held.
@@ -612,6 +633,7 @@ static int blkio_policy_parse_and_set(char *buf,
         unsigned long major, minor, temp;
         int i = 0;
         dev_t dev;
+        u64 bps;
 
         memset(s, 0, sizeof(s));
 
@@ -667,7 +689,16 @@ static int blkio_policy_parse_and_set(char *buf,
 
                 newpn->plid = plid;
                 newpn->fileid = fileid;
-                newpn->weight = temp;
+                newpn->val.weight = temp;
+                break;
+        case BLKIO_POLICY_THROTL:
+                ret = strict_strtoull(s[1], 10, &bps);
+                if (ret)
+                        return -EINVAL;
+
+                newpn->plid = plid;
+                newpn->fileid = fileid;
+                newpn->val.bps = bps;
                 break;
         default:
                 BUG();
@@ -684,18 +715,45 @@ unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
                                 BLKIO_PROP_weight_device);
         if (pn)
-                return pn->weight;
+                return pn->val.weight;
         else
                 return blkcg->weight;
 }
 EXPORT_SYMBOL_GPL(blkcg_get_weight);
 
+uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
+{
+        struct blkio_policy_node *pn;
+
+        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
+                                BLKIO_THROTL_read_bps_device);
+        if (pn)
+                return pn->val.bps;
+        else
+                return -1;
+}
+
+uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev)
+{
+        struct blkio_policy_node *pn;
+        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
+                                BLKIO_THROTL_write_bps_device);
+        if (pn)
+                return pn->val.bps;
+        else
+                return -1;
+}
+
 /* Checks whether user asked for deleting a policy rule */
 static bool blkio_delete_rule_command(struct blkio_policy_node *pn)
 {
         switch(pn->plid) {
         case BLKIO_POLICY_PROP:
-                if (pn->weight == 0)
+                if (pn->val.weight == 0)
+                        return 1;
+                break;
+        case BLKIO_POLICY_THROTL:
+                if (pn->val.bps == 0)
                         return 1;
                 break;
         default:
@@ -710,7 +768,10 @@ static void blkio_update_policy_rule(struct blkio_policy_node *oldpn,
 {
         switch(oldpn->plid) {
         case BLKIO_POLICY_PROP:
-                oldpn->weight = newpn->weight;
+                oldpn->val.weight = newpn->val.weight;
+                break;
+        case BLKIO_POLICY_THROTL:
+                oldpn->val.bps = newpn->val.bps;
                 break;
         default:
                 BUG();
@@ -725,13 +786,23 @@ static void blkio_update_blkg_policy(struct blkio_cgroup *blkcg,
                 struct blkio_group *blkg, struct blkio_policy_node *pn)
 {
         unsigned int weight;
+        u64 bps;
 
         switch(pn->plid) {
         case BLKIO_POLICY_PROP:
-                weight = pn->weight ? pn->weight :
+                weight = pn->val.weight ? pn->val.weight :
                                 blkcg->weight;
                 blkio_update_group_weight(blkg, weight);
                 break;
+        case BLKIO_POLICY_THROTL:
+                switch(pn->fileid) {
+                case BLKIO_THROTL_read_bps_device:
+                case BLKIO_THROTL_write_bps_device:
+                        bps = pn->val.bps ? pn->val.bps : (-1);
+                        blkio_update_group_bps(blkg, bps, pn->fileid);
+                        break;
+                }
+                break;
         default:
                 BUG();
         }
@@ -826,7 +897,17 @@ blkio_print_policy_node(struct seq_file *m, struct blkio_policy_node *pn)
                 case BLKIO_POLICY_PROP:
                         if (pn->fileid == BLKIO_PROP_weight_device)
                                 seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
-                                        MINOR(pn->dev), pn->weight);
+                                        MINOR(pn->dev), pn->val.weight);
+                        break;
+                case BLKIO_POLICY_THROTL:
+                        if (pn->fileid == BLKIO_THROTL_read_bps_device)
+                                seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
+                                        MINOR(pn->dev), pn->val.bps);
+                        else if (pn->fileid == BLKIO_THROTL_write_bps_device)
+                                seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
+                                        MINOR(pn->dev), pn->val.bps);
+                        else
+                                BUG();
                         break;
                 default:
                         BUG();
@@ -869,6 +950,16 @@ static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
                         BUG();
                 }
                 break;
+        case BLKIO_POLICY_THROTL:
+                switch(name){
+                case BLKIO_THROTL_read_bps_device:
+                case BLKIO_THROTL_write_bps_device:
+                        blkio_read_policy_node_files(cft, blkcg, m);
+                        return 0;
+                default:
+                        BUG();
+                }
+                break;
         default:
                 BUG();
         }
@@ -959,7 +1050,18 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
                         BUG();
                 }
                 break;
-
+        case BLKIO_POLICY_THROTL:
+                switch(name){
+                case BLKIO_THROTL_io_service_bytes:
+                        return blkio_read_blkg_stats(blkcg, cft, cb,
+                                                BLKIO_STAT_SERVICE_BYTES, 1);
+                case BLKIO_THROTL_io_serviced:
+                        return blkio_read_blkg_stats(blkcg, cft, cb,
+                                                BLKIO_STAT_SERVICED, 1);
+                default:
+                        BUG();
+                }
+                break;
         default:
                 BUG();
         }
@@ -1053,6 +1155,23 @@ struct cftype blkio_files[] = {
                 .write_u64 = blkiocg_file_write_u64,
         },
         {
+                .name = "throttle.read_bps_device",
+                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
+                                BLKIO_THROTL_read_bps_device),
+                .read_seq_string = blkiocg_file_read,
+                .write_string = blkiocg_file_write,
+                .max_write_len = 256,
+        },
+
+        {
+                .name = "throttle.write_bps_device",
+                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
+                                BLKIO_THROTL_write_bps_device),
+                .read_seq_string = blkiocg_file_read,
+                .write_string = blkiocg_file_write,
+                .max_write_len = 256,
+        },
+        {
                 .name = "time",
                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
                                 BLKIO_PROP_time),
@@ -1071,12 +1190,24 @@ struct cftype blkio_files[] = {
                 .read_map = blkiocg_file_read_map,
         },
         {
+                .name = "throttle.io_service_bytes",
+                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
+                                BLKIO_THROTL_io_service_bytes),
+                .read_map = blkiocg_file_read_map,
+        },
+        {
                 .name = "io_serviced",
                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
                                 BLKIO_PROP_io_serviced),
                 .read_map = blkiocg_file_read_map,
         },
         {
+                .name = "throttle.io_serviced",
+                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
+                                BLKIO_THROTL_io_serviced),
+                .read_map = blkiocg_file_read_map,
+        },
+        {
                 .name = "io_service_time",
                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
                                 BLKIO_PROP_io_service_time),
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index c8de2598429d..1b738827b2f6 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -17,6 +17,7 @@
 
 enum blkio_policy_id {
         BLKIO_POLICY_PROP = 0,          /* Proportional Bandwidth division */
+        BLKIO_POLICY_THROTL,            /* Throttling */
 };
 
 #if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
@@ -88,6 +89,14 @@ enum blkcg_file_name_prop {
         BLKIO_PROP_dequeue,
 };
 
+/* cgroup files owned by throttle policy */
+enum blkcg_file_name_throtl {
+        BLKIO_THROTL_read_bps_device,
+        BLKIO_THROTL_write_bps_device,
+        BLKIO_THROTL_io_service_bytes,
+        BLKIO_THROTL_io_serviced,
+};
+
 struct blkio_cgroup {
         struct cgroup_subsys_state css;
         unsigned int weight;
@@ -146,23 +155,42 @@ struct blkio_group {
 struct blkio_policy_node {
         struct list_head node;
         dev_t dev;
-        unsigned int weight;
         /* This node belongs to max bw policy or porportional weight policy */
         enum blkio_policy_id plid;
         /* cgroup file to which this rule belongs to */
         int fileid;
+
+        union {
+                unsigned int weight;
+                /*
+                 * Rate read/write in terms of byptes per second
+                 * Whether this rate represents read or write is determined
+                 * by file type "fileid".
+                 */
+                u64 bps;
+        } val;
 };
 
 extern unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
                                      dev_t dev);
+extern uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg,
+                                     dev_t dev);
+extern uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg,
+                                     dev_t dev);
 
 typedef void (blkio_unlink_group_fn) (void *key, struct blkio_group *blkg);
 typedef void (blkio_update_group_weight_fn) (struct blkio_group *blkg,
                                                 unsigned int weight);
+typedef void (blkio_update_group_read_bps_fn) (struct blkio_group *blkg,
+                                                u64 read_bps);
+typedef void (blkio_update_group_write_bps_fn) (struct blkio_group *blkg,
+                                                u64 write_bps);
 
 struct blkio_policy_ops {
         blkio_unlink_group_fn *blkio_unlink_group_fn;
         blkio_update_group_weight_fn *blkio_update_group_weight_fn;
+        blkio_update_group_read_bps_fn *blkio_update_group_read_bps_fn;
+        blkio_update_group_write_bps_fn *blkio_update_group_write_bps_fn;
 };
 
 struct blkio_policy_type {