From: Heinz Mauelshagen 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 Signed-off-by: Alasdair G Kergon Cc: Milan Broz Signed-off-by: Andrew Morton --- drivers/md/dm-io.c | 12 ++++++++++-- 1 files changed, 10 insertions(+), 2 deletions(-) diff -puN drivers/md/dm-io.c~dm-io-delay-dec_count drivers/md/dm-io.c --- a/drivers/md/dm-io.c~dm-io-delay-dec_count +++ a/drivers/md/dm-io.c @@ -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; } _