From: Heinz Mauelshagen <[EMAIL PROTECTED]>

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 <[EMAIL PROTECTED]>
Signed-off-by: Alasdair G Kergon <[EMAIL PROTECTED]>
Cc: Milan Broz <[EMAIL PROTECTED]>
---

 drivers/md/dm-io.c |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

Index: linux-2.6.21/drivers/md/dm-io.c
===================================================================
--- linux-2.6.21.orig/drivers/md/dm-io.c        2007-05-01 17:38:32.000000000 
+0100
+++ linux-2.6.21/drivers/md/dm-io.c     2007-05-01 17:40:52.000000000 +0100
@@ -126,7 +126,8 @@ static void dec_count(struct io *io, uns
 
 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, unsign
        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;
 }
 
-
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