X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=fs%2Fbio.c;h=73922abba832d0a41c1cb01bbf5bcc0fec1cb78b;hb=96c3f4331a8c1cd0a58307e4ac7e73e09d7dab23;hp=84da88539046fa21a6db865454db135df40be080;hpb=4b781474682434e7881f20e9dfbe6687ea619795;p=karo-tx-linux.git

diff --git a/fs/bio.c b/fs/bio.c
index 84da88539046..73922abba832 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -19,12 +19,14 @@
 #include <linux/swap.h>
 #include <linux/bio.h>
 #include <linux/blkdev.h>
+#include <linux/iocontext.h>
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/mempool.h>
 #include <linux/workqueue.h>
+#include <linux/cgroup.h>
 #include <scsi/sg.h>		/* for struct sg_iovec */
 
 #include <trace/events/block.h>
@@ -418,6 +420,7 @@ void bio_put(struct bio *bio)
 	 * last put frees it
 	 */
 	if (atomic_dec_and_test(&bio->bi_cnt)) {
+		bio_disassociate_task(bio);
 		bio->bi_next = NULL;
 		bio->bi_destructor(bio);
 	}
@@ -1646,6 +1649,64 @@ bad:
 }
 EXPORT_SYMBOL(bioset_create);
 
+#ifdef CONFIG_BLK_CGROUP
+/**
+ * bio_associate_current - associate a bio with %current
+ * @bio: target bio
+ *
+ * Associate @bio with %current if it hasn't been associated yet.  Block
+ * layer will treat @bio as if it were issued by %current no matter which
+ * task actually issues it.
+ *
+ * This function takes an extra reference of @task's io_context and blkcg
+ * which will be put when @bio is released.  The caller must own @bio,
+ * ensure %current->io_context exists, and is responsible for synchronizing
+ * calls to this function.
+ */
+int bio_associate_current(struct bio *bio)
+{
+	struct io_context *ioc;
+	struct cgroup_subsys_state *css;
+
+	if (bio->bi_ioc)
+		return -EBUSY;
+
+	ioc = current->io_context;
+	if (!ioc)
+		return -ENOENT;
+
+	/* acquire active ref on @ioc and associate */
+	get_io_context_active(ioc);
+	bio->bi_ioc = ioc;
+
+	/* associate blkcg if exists */
+	rcu_read_lock();
+	css = task_subsys_state(current, blkio_subsys_id);
+	if (css && css_tryget(css))
+		bio->bi_css = css;
+	rcu_read_unlock();
+
+	return 0;
+}
+
+/**
+ * bio_disassociate_task - undo bio_associate_current()
+ * @bio: target bio
+ */
+void bio_disassociate_task(struct bio *bio)
+{
+	if (bio->bi_ioc) {
+		put_io_context(bio->bi_ioc);
+		bio->bi_ioc = NULL;
+	}
+	if (bio->bi_css) {
+		css_put(bio->bi_css);
+		bio->bi_css = NULL;
+	}
+}
+
+#endif /* CONFIG_BLK_CGROUP */
+
 static void __init biovec_init_slabs(void)
 {
 	int i;