From: Heinz Mauelshagen <hjm@redhat.com>
Date: Wed, 9 May 2007 09:33:00 +0000 (-0700)
Subject: dm io: delay dec_count
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c897feb3dcf3c3300849056ee82b01df7bf66d3c;p=linux-beck.git

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 8bdc8a87b249..4d19c45158b4 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -126,7 +126,8 @@ static void dec_count(struct io *io, unsigned int region, int error)
 
 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 @@ static int endio(struct bio *bio, unsigned int done, int error)
 	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;
 }