On 2017年03月08日 16:45, lixi...@cmss.chinamobile.com wrote:
From: Xiubo Li <lixi...@cmss.chinamobile.com>

The t_data_nents and t_bidi_data_nents are all the numbers of the
segments, and we couldn't be sure the size of the data area block
will equal to size of the segment.

Use the actually block number needed intead of the sum of segments.

Signed-off-by: Xiubo Li <lixi...@cmss.chinamobile.com>
---
  drivers/target/target_core_user.c | 3 +--
  1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/target/target_core_user.c 
b/drivers/target/target_core_user.c
index 99cd239..117be07 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -650,8 +650,7 @@ static bool is_ring_space_avail(struct tcmu_dev *udev, 
struct tcmu_cmd *cmd,
         * expensive to tell how many regions are freed in the bitmap
        */
        base_command_size = max(offsetof(struct tcmu_cmd_entry,
-                               req.iov[se_cmd->t_bidi_data_nents +
-                                       se_cmd->t_data_nents]),
+                               req.iov[tcmu_cmd->dbi_len]),
For the old code:

If the segment size is larger than the DATA_BLOCK_SIZE, and at the same time all the data blocks won't be continues between each other(that to say each block will use one iov: iov_cnt == block cnt > nents), the entry's cdb data will overlap with entry's
iov[] data.

Thanks,

BRs
Xiubo


                                sizeof(struct tcmu_cmd_entry));
        command_size = base_command_size
                + round_up(scsi_command_size(se_cmd->t_task_cdb), 
TCMU_OP_ALIGN_SIZE);



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