[PATCH V4 10/12] block: call __bio_free in bio_endio

Shaohua Li
2017-06-28T16:31:39Z

From: Shaohua Li <shli@fb.com>

bio_free isn't a good place to free cgroup/integrity info. There are a
lot of cases bio is allocated in special way (for example, in stack) and
never gets called by bio_put hence bio_free, we are leaking memory. This
patch moves the free to bio endio, which should be called anyway. The
__bio_free call in bio_free is kept, in case the bio never gets called
bio endio.

This assumes ->bi_end_io() doesn't access cgroup/integrity info, which
seems true in my audit. Otherwise, we probably must add a flag to
distinguish if bio will be called by bio_put.

Signed-off-by: Shaohua Li <shli@fb.com>
---
block/bio-integrity.c | 1 +
block/bio.c | 2 ++
2 files changed, 3 insertions(+)

diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index b8a3a65..e7fa7d0 100644
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -120,6 +120,7 @@ void bio_integrity_free(struct bio *bio)
}

bio->bi_integrity = NULL;
+ bio->bi_opf &= ~REQ_INTEGRITY;
}
EXPORT_SYMBOL(bio_integrity_free);

diff --git a/block/bio.c b/block/bio.c
index 9cf98b2..4bf3a29 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1828,6 +1828,8 @@ void bio_endio(struct bio *bio)
}

blk_throtl_bio_endio(bio);
+ /* release cgroup/integrity info */
+ __bio_free(bio);
if (bio->bi_end_io)
bio->bi_end_io(bio);
}
--
2.9.3