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scsi: fix discard page leak

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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>
This commit is contained in:
FUJITA Tomonori 2010-07-08 10:16:17 +02:00 committed by Jens Axboe
parent 9e094383b6
commit 610a63498f
2 changed files with 10 additions and 7 deletions
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7
drivers/scsi/scsi_lib.c
View file

@ -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);

10
drivers/scsi/sd.c
View file

@ -468,6 +468,10 @@ static int scsi_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq)
blk_add_request_payload(rq, page, len);
ret = scsi_setup_blk_pc_cmnd(sdp, rq);
rq->buffer = page_address(page);
if (ret != BLKPREP_OK) {
__free_page(page);
rq->buffer = NULL;
}
return ret;
}
@ -485,8 +489,10 @@ static int scsi_setup_flush_cmnd(struct scsi_device *sdp, struct request *rq)
static void sd_unprep_fn(struct request_queue *q, struct request *rq)
{
if (rq->cmd_flags & REQ_DISCARD)
__free_page(virt_to_page(rq->buffer));
if (rq->cmd_flags & REQ_DISCARD) {
free_page((unsigned long)rq->buffer);
rq->buffer = NULL;
}
}
/**