scsi: fix discard page leak

We leak a page allocated for discard on some error conditions
(e.g. scsi_prep_state_check returns BLKPREP_DEFER in
scsi_setup_blk_pc_cmnd).

We unprep on requests that weren't prepped in the error path of
scsi_init_io. It makes the error path to clean up scsi commands messy.

Let's strictly apply the rule that we can't unprep on a request that
wasn't prepped.

Calling just scsi_put_command() in the error path of scsi_init_io() is
enough. We don't set REQ_DONTPREP yet.

scsi_setup_discard_cmnd can safely free a page on the error case with
the above rule.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 2 insertions, 5 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index ee836193f531..b8de389636f8 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1011,11 +1011,8 @@ int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
 
 err_exit:
 	scsi_release_buffers(cmd);
-	if (error == BLKPREP_KILL)
-		scsi_put_command(cmd);
-	else /* BLKPREP_DEFER */
-		scsi_unprep_request(cmd->request);
-
+	scsi_put_command(cmd);
+	cmd->request->special = NULL;
 	return error;
 }
 EXPORT_SYMBOL(scsi_init_io);