dm io: delay dec_count
Delay decrementing the 'struct io' reference count until after the bio has
been freed so that a bio destructor function may reference it. Required by a
later patch.
Signed-off-by: Heinz Mauelshagen <hjm@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Milan Broz <mbroz@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 8bdc8a8..4d19c45 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -126,7 +126,8 @@
static int endio(struct bio *bio, unsigned int done, int error)
{
- struct io *io = (struct io *) bio->bi_private;
+ struct io *io;
+ unsigned region;
/* keep going until we've finished */
if (bio->bi_size)
@@ -135,10 +136,17 @@
if (error && bio_data_dir(bio) == READ)
zero_fill_bio(bio);
- dec_count(io, bio_get_region(bio), error);
+ /*
+ * The bio destructor in bio_put() may use the io object.
+ */
+ io = bio->bi_private;
+ region = bio_get_region(bio);
+
bio->bi_max_vecs++;
bio_put(bio);
+ dec_count(io, region, error);
+
return 0;
}