nvmet: reorder fields in 'struct nvmefc_fcp_req'

Group some variables based on their sizes to reduce holes.
On x86_64, this shrinks the size of 'struct nvmefc_fcp_req' from
112 to 104 bytes.

This structure is embedded in some other structures (nvme_fc_fcp_op
which itself is embedded in nvme_fcp_op_w_sgl), so it helps reducing the
size of these structures too.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/include/linux/nvme-fc-driver.h b/include/linux/nvme-fc-driver.h
index fa092b9..4109f1b 100644 (file)
--- a/include/linux/nvme-fc-driver.h
+++ b/include/linux/nvme-fc-driver.h
@@ -185,7 +185,6 @@ enum nvmefc_fcp_datadir {
  * @first_sgl: memory for 1st scatter/gather list segment for payload data
  * @sg_cnt:    number of elements in the scatter/gather list
  * @io_dir:    direction of the FCP request (see NVMEFC_FCP_xxx)
- * @sqid:      The nvme SQID the command is being issued on
  * @done:      The callback routine the LLDD is to invoke upon completion of
  *             the FCP operation. req argument is the pointer to the original
  *             FCP IO operation.
@@ -194,12 +193,13 @@ enum nvmefc_fcp_datadir {
  *             while processing the operation. The length of the buffer
  *             corresponds to the fcprqst_priv_sz value specified in the
  *             nvme_fc_port_template supplied by the LLDD.
+ * @sqid:      The nvme SQID the command is being issued on
  *
  * Values set by the LLDD indicating completion status of the FCP operation.
  * Must be set prior to calling the done() callback.
+ * @rcv_rsplen: length, in bytes, of the FCP RSP IU received.
  * @transferred_length: amount of payload data, in bytes, that were
  *             transferred. Should equal payload_length on success.
- * @rcv_rsplen: length, in bytes, of the FCP RSP IU received.
  * @status:    Completion status of the FCP operation. must be 0 upon success,
  *             negative errno value upon failure (ex: -EIO). Note: this is
  *             NOT a reflection of the NVME CQE completion status. Only the
@@ -219,14 +219,14 @@ struct nvmefc_fcp_req {
        int                     sg_cnt;
        enum nvmefc_fcp_datadir io_dir;
 
-       __le16                  sqid;
-
        void (*done)(struct nvmefc_fcp_req *req);
 
        void                    *private;
 
-       u32                     transferred_length;
+       __le16                  sqid;
+
        u16                     rcv_rsplen;
+       u32                     transferred_length;
        u32                     status;
 } __aligned(sizeof(u64));      /* alignment for other things alloc'd with */