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@@ -508,3 +508,106 @@ u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
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int off)
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{
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struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off);
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+
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+ return __blkg_prfill_rwstat(sf, pd, &rwstat);
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+}
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+EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
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+
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+/**
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+ * blkg_conf_prep - parse and prepare for per-blkg config update
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+ * @blkcg: target block cgroup
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+ * @pol: target policy
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+ * @input: input string
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+ * @ctx: blkg_conf_ctx to be filled
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+ *
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+ * Parse per-blkg config update from @input and initialize @ctx with the
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+ * result. @ctx->blkg points to the blkg to be updated and @ctx->v the new
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+ * value. This function returns with RCU read lock and queue lock held and
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+ * must be paired with blkg_conf_finish().
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+ */
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+int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
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+ const char *input, struct blkg_conf_ctx *ctx)
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+ __acquires(rcu) __acquires(disk->queue->queue_lock)
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+{
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+ struct gendisk *disk;
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+ struct blkcg_gq *blkg;
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+ unsigned int major, minor;
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+ unsigned long long v;
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+ int part, ret;
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+
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+ if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3)
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+ return -EINVAL;
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+
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+ disk = get_gendisk(MKDEV(major, minor), &part);
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+ if (!disk || part)
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+ return -EINVAL;
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+
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+ rcu_read_lock();
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+ spin_lock_irq(disk->queue->queue_lock);
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+
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+ if (blkcg_policy_enabled(disk->queue, pol))
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+ blkg = blkg_lookup_create(blkcg, disk->queue);
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+ else
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+ blkg = ERR_PTR(-EINVAL);
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+
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+ if (IS_ERR(blkg)) {
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+ ret = PTR_ERR(blkg);
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+ rcu_read_unlock();
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+ spin_unlock_irq(disk->queue->queue_lock);
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+ put_disk(disk);
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+ /*
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+ * If queue was bypassing, we should retry. Do so after a
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+ * short msleep(). It isn't strictly necessary but queue
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+ * can be bypassing for some time and it's always nice to
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+ * avoid busy looping.
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+ */
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+ if (ret == -EBUSY) {
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+ msleep(10);
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+ ret = restart_syscall();
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+ }
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+ return ret;
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+ }
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+
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+ ctx->disk = disk;
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+ ctx->blkg = blkg;
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+ ctx->v = v;
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+ return 0;
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+}
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+EXPORT_SYMBOL_GPL(blkg_conf_prep);
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+
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+/**
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+ * blkg_conf_finish - finish up per-blkg config update
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+ * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep()
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+ *
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+ * Finish up after per-blkg config update. This function must be paired
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+ * with blkg_conf_prep().
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+ */
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+void blkg_conf_finish(struct blkg_conf_ctx *ctx)
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+ __releases(ctx->disk->queue->queue_lock) __releases(rcu)
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+{
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+ spin_unlock_irq(ctx->disk->queue->queue_lock);
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+ rcu_read_unlock();
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+ put_disk(ctx->disk);
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+}
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+EXPORT_SYMBOL_GPL(blkg_conf_finish);
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+
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+struct cftype blkcg_files[] = {
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+ {
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+ .name = "reset_stats",
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+ .write_u64 = blkcg_reset_stats,
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+ },
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+ { } /* terminate */
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+};
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+
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+/**
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+ * blkcg_css_offline - cgroup css_offline callback
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+ * @cgroup: cgroup of interest
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+ *
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+ * This function is called when @cgroup is about to go away and responsible
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+ * for shooting down all blkgs associated with @cgroup. blkgs should be
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+ * removed while holding both q and blkcg locks. As blkcg lock is nested
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+ * inside q lock, this function performs reverse double lock dancing.
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+ *
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+ * This is the blkcg counterpart of ioc_release_fn().
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+ */
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+static void blkcg_css_offline(struct cgroup *cgroup)
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