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-rw-r--r--block/blk-cgroup-fc-appid.c57
1 files changed, 57 insertions, 0 deletions
diff --git a/block/blk-cgroup-fc-appid.c b/block/blk-cgroup-fc-appid.c
new file mode 100644
index 000000000..842e5e1c0
--- /dev/null
+++ b/block/blk-cgroup-fc-appid.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "blk-cgroup.h"
+
+/**
+ * blkcg_set_fc_appid - set the fc_app_id field associted to blkcg
+ * @app_id: application identifier
+ * @cgrp_id: cgroup id
+ * @app_id_len: size of application identifier
+ */
+int blkcg_set_fc_appid(char *app_id, u64 cgrp_id, size_t app_id_len)
+{
+ struct cgroup *cgrp;
+ struct cgroup_subsys_state *css;
+ struct blkcg *blkcg;
+ int ret = 0;
+
+ if (app_id_len > FC_APPID_LEN)
+ return -EINVAL;
+
+ cgrp = cgroup_get_from_id(cgrp_id);
+ if (IS_ERR(cgrp))
+ return PTR_ERR(cgrp);
+ css = cgroup_get_e_css(cgrp, &io_cgrp_subsys);
+ if (!css) {
+ ret = -ENOENT;
+ goto out_cgrp_put;
+ }
+ blkcg = css_to_blkcg(css);
+ /*
+ * There is a slight race condition on setting the appid.
+ * Worst case an I/O may not find the right id.
+ * This is no different from the I/O we let pass while obtaining
+ * the vmid from the fabric.
+ * Adding the overhead of a lock is not necessary.
+ */
+ strlcpy(blkcg->fc_app_id, app_id, app_id_len);
+ css_put(css);
+out_cgrp_put:
+ cgroup_put(cgrp);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(blkcg_set_fc_appid);
+
+/**
+ * blkcg_get_fc_appid - get the fc app identifier associated with a bio
+ * @bio: target bio
+ *
+ * On success return the fc_app_id, on failure return NULL
+ */
+char *blkcg_get_fc_appid(struct bio *bio)
+{
+ if (!bio->bi_blkg || bio->bi_blkg->blkcg->fc_app_id[0] == '\0')
+ return NULL;
+ return bio->bi_blkg->blkcg->fc_app_id;
+}
+EXPORT_SYMBOL_GPL(blkcg_get_fc_appid);