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authorJosef Bacik <jbacik@fb.com>2018-07-03 18:14:50 +0300
committerJens Axboe <axboe@kernel.dk>2018-07-09 18:07:53 +0300
commit08e18eab0c579ad84399c1899c11899734854eb2 (patch)
tree2125489ae5f5c74c6fd23146d374c85dfc4228c0 /block/bio.c
parent6e768717304bdbe8d2897ca8298f6b58863fdc41 (diff)
downloadlinux-08e18eab0c579ad84399c1899c11899734854eb2.tar.xz
block: add bi_blkg to the bio for cgroups
Currently io.low uses a bi_cg_private to stash its private data for the blkg, however other blkcg policies may want to use this as well. Since we can get the private data out of the blkg, move this to bi_blkg in the bio and make it generic, then we can use bio_associate_blkg() to attach the blkg to the bio. Theoretically we could simply replace the bi_css with this since we can get to all the same information from the blkg, however you have to lookup the blkg, so for example wbc_init_bio() would have to lookup and possibly allocate the blkg for the css it was trying to attach to the bio. This could be problematic and result in us either not attaching the css at all to the bio, or falling back to the root blkcg if we are unable to allocate the corresponding blkg. So for now do this, and in the future if possible we could just replace the bi_css with bi_blkg and update the helpers to do the correct translation. Signed-off-by: Josef Bacik <jbacik@fb.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bio.c')
-rw-r--r--block/bio.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/block/bio.c b/block/bio.c
index 67eff5eddc49..044571538574 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -28,6 +28,7 @@
#include <linux/mempool.h>
#include <linux/workqueue.h>
#include <linux/cgroup.h>
+#include <linux/blk-cgroup.h>
#include <trace/events/block.h>
#include "blk.h"
@@ -2037,6 +2038,24 @@ int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css)
EXPORT_SYMBOL_GPL(bio_associate_blkcg);
/**
+ * bio_associate_blkg - associate a bio with the specified blkg
+ * @bio: target bio
+ * @blkg: the blkg to associate
+ *
+ * Associate @bio with the blkg specified by @blkg. This is the queue specific
+ * blkcg information associated with the @bio, a reference will be taken on the
+ * @blkg and will be freed when the bio is freed.
+ */
+int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg)
+{
+ if (unlikely(bio->bi_blkg))
+ return -EBUSY;
+ blkg_get(blkg);
+ bio->bi_blkg = blkg;
+ return 0;
+}
+
+/**
* bio_disassociate_task - undo bio_associate_current()
* @bio: target bio
*/
@@ -2050,6 +2069,10 @@ void bio_disassociate_task(struct bio *bio)
css_put(bio->bi_css);
bio->bi_css = NULL;
}
+ if (bio->bi_blkg) {
+ blkg_put(bio->bi_blkg);
+ bio->bi_blkg = NULL;
+ }
}
/**