scsi: core: Clean up allocation and freeing of sgtables

Rename scsi_init_io() to scsi_alloc_sgtables(), and ensure callers call
scsi_free_sgtables() to cleanup failures close to scsi_init_io() instead of
leaking it down the generic I/O submission path.

Link: https://lore.kernel.org/r/20201005084130.143273-9-hch@lst.deReviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_lib.c

@@ -515,7 +515,7 @@ static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
 	}
 }
 
-static void scsi_free_sgtables(struct scsi_cmnd *cmd)
+void scsi_free_sgtables(struct scsi_cmnd *cmd)
 {
 	if (cmd->sdb.table.nents)
 		sg_free_table_chained(&cmd->sdb.table,
@@ -524,6 +524,7 @@ static void scsi_free_sgtables(struct scsi_cmnd *cmd)
 		sg_free_table_chained(&cmd->prot_sdb->table,
 				SCSI_INLINE_PROT_SG_CNT);
 }
+EXPORT_SYMBOL_GPL(scsi_free_sgtables);
 
 static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
 {
@@ -983,7 +984,7 @@ static inline bool scsi_cmd_needs_dma_drain(struct scsi_device *sdev,
 }
 
 /**
- * scsi_init_io - SCSI I/O initialization function.
+ * scsi_alloc_sgtables - allocate S/G tables for a command
  * @cmd:  command descriptor we wish to initialize
  *
  * Returns:
@@ -991,7 +992,7 @@ static inline bool scsi_cmd_needs_dma_drain(struct scsi_device *sdev,
  * * BLK_STS_RESOURCE - if the failure is retryable
  * * BLK_STS_IOERR    - if the failure is fatal
  */
-blk_status_t scsi_init_io(struct scsi_cmnd *cmd)
+blk_status_t scsi_alloc_sgtables(struct scsi_cmnd *cmd)
 {
 	struct scsi_device *sdev = cmd->device;
 	struct request *rq = cmd->request;
@@ -1083,7 +1084,7 @@ blk_status_t scsi_init_io(struct scsi_cmnd *cmd)
 	scsi_free_sgtables(cmd);
 	return ret;
 }
-EXPORT_SYMBOL(scsi_init_io);
+EXPORT_SYMBOL(scsi_alloc_sgtables);
 
 /**
  * scsi_initialize_rq - initialize struct scsi_cmnd partially
@@ -1171,7 +1172,7 @@ static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev,
 	 * submit a request without an attached bio.
 	 */
 	if (req->bio) {
-		blk_status_t ret = scsi_init_io(cmd);
+		blk_status_t ret = scsi_alloc_sgtables(cmd);
 		if (unlikely(ret != BLK_STS_OK))
 			return ret;
 	} else {
@@ -1213,19 +1214,12 @@ static blk_status_t scsi_setup_cmnd(struct scsi_device *sdev,
 		struct request *req)
 {
 	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
-	blk_status_t ret;
 
 	cmd->sc_data_direction = rq_dma_dir(req);
 
 	if (blk_rq_is_scsi(req))
-		ret = scsi_setup_scsi_cmnd(sdev, req);
-	else
-		ret = scsi_setup_fs_cmnd(sdev, req);
-
-	if (ret != BLK_STS_OK)
-		scsi_free_sgtables(cmd);
-
-	return ret;
+		return scsi_setup_scsi_cmnd(sdev, req);
+	return scsi_setup_fs_cmnd(sdev, req);
 }
 
 static blk_status_t

drivers/scsi/sd.c

@@ -902,7 +902,7 @@ static blk_status_t sd_setup_unmap_cmnd(struct scsi_cmnd *cmd)
 	cmd->transfersize = data_len;
 	rq->timeout = SD_TIMEOUT;
 
-	return scsi_init_io(cmd);
+	return scsi_alloc_sgtables(cmd);
 }
 
 static blk_status_t sd_setup_write_same16_cmnd(struct scsi_cmnd *cmd,
@@ -934,7 +934,7 @@ static blk_status_t sd_setup_write_same16_cmnd(struct scsi_cmnd *cmd,
 	cmd->transfersize = data_len;
 	rq->timeout = unmap ? SD_TIMEOUT : SD_WRITE_SAME_TIMEOUT;
 
-	return scsi_init_io(cmd);
+	return scsi_alloc_sgtables(cmd);
 }
 
 static blk_status_t sd_setup_write_same10_cmnd(struct scsi_cmnd *cmd,
@@ -966,7 +966,7 @@ static blk_status_t sd_setup_write_same10_cmnd(struct scsi_cmnd *cmd,
 	cmd->transfersize = data_len;
 	rq->timeout = unmap ? SD_TIMEOUT : SD_WRITE_SAME_TIMEOUT;
 
-	return scsi_init_io(cmd);
+	return scsi_alloc_sgtables(cmd);
 }
 
 static blk_status_t sd_setup_write_zeroes_cmnd(struct scsi_cmnd *cmd)
@@ -1107,7 +1107,7 @@ static blk_status_t sd_setup_write_same_cmnd(struct scsi_cmnd *cmd)
 	 * knows how much to actually write.
 	 */
 	rq->__data_len = sdp->sector_size;
-	ret = scsi_init_io(cmd);
+	ret = scsi_alloc_sgtables(cmd);
 	rq->__data_len = blk_rq_bytes(rq);
 
 	return ret;
@@ -1226,23 +1226,24 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
 	unsigned int dif;
 	bool dix;
 
-	ret = scsi_init_io(cmd);
+	ret = scsi_alloc_sgtables(cmd);
 	if (ret != BLK_STS_OK)
 		return ret;
 
+	ret = BLK_STS_IOERR;
 	if (!scsi_device_online(sdp) || sdp->changed) {
 		scmd_printk(KERN_ERR, cmd, "device offline or changed\n");
-		return BLK_STS_IOERR;
+		goto fail;
 	}
 
 	if (blk_rq_pos(rq) + blk_rq_sectors(rq) > get_capacity(rq->rq_disk)) {
 		scmd_printk(KERN_ERR, cmd, "access beyond end of device\n");
-		return BLK_STS_IOERR;
+		goto fail;
 	}
 
 	if ((blk_rq_pos(rq) & mask) || (blk_rq_sectors(rq) & mask)) {
 		scmd_printk(KERN_ERR, cmd, "request not aligned to the logical block size\n");
-		return BLK_STS_IOERR;
+		goto fail;
 	}
 
 	/*
@@ -1264,7 +1265,7 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
 	if (req_op(rq) == REQ_OP_ZONE_APPEND) {
 		ret = sd_zbc_prepare_zone_append(cmd, &lba, nr_blocks);
 		if (ret)
-			return ret;
+			goto fail;
 	}
 
 	fua = rq->cmd_flags & REQ_FUA ? 0x8 : 0;
@@ -1292,7 +1293,7 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
 	}
 
 	if (unlikely(ret != BLK_STS_OK))
-		return ret;
+		goto fail;
 
 	/*
 	 * We shouldn't disconnect in the middle of a sector, so with a dumb
@@ -1316,10 +1317,12 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
 				     blk_rq_sectors(rq)));
 
 	/*
-	 * This indicates that the command is ready from our end to be
-	 * queued.
+	 * This indicates that the command is ready from our end to be queued.
 	 */
 	return BLK_STS_OK;
+fail:
+	scsi_free_sgtables(cmd);
+	return ret;
 }
 
 static blk_status_t sd_init_command(struct scsi_cmnd *cmd)

drivers/scsi/sr.c

@@ -392,15 +392,11 @@ static blk_status_t sr_init_command(struct scsi_cmnd *SCpnt)
 	struct request *rq = SCpnt->request;
 	blk_status_t ret;
 
-	ret = scsi_init_io(SCpnt);
+	ret = scsi_alloc_sgtables(SCpnt);
 	if (ret != BLK_STS_OK)
-		goto out;
+		return ret;
 	cd = scsi_cd(rq->rq_disk);
 
-	/* from here on until we're complete, any goto out
-	 * is used for a killable error condition */
-	ret = BLK_STS_IOERR;
-
 	SCSI_LOG_HLQUEUE(1, scmd_printk(KERN_INFO, SCpnt,
 		"Doing sr request, block = %d\n", block));
 
@@ -509,12 +505,12 @@ static blk_status_t sr_init_command(struct scsi_cmnd *SCpnt)
 	SCpnt->allowed = MAX_RETRIES;
 
 	/*
-	 * This indicates that the command is ready from our end to be
-	 * queued.
+	 * This indicates that the command is ready from our end to be queued.
 	 */
-	ret = BLK_STS_OK;
+	return BLK_STS_OK;
  out:
-	return ret;
+	scsi_free_sgtables(SCpnt);
+	return BLK_STS_IOERR;
 }
 
 static int sr_block_open(struct block_device *bdev, fmode_t mode)

include/scsi/scsi_cmnd.h

@@ -165,7 +165,8 @@ extern void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
 				 size_t *offset, size_t *len);
 extern void scsi_kunmap_atomic_sg(void *virt);
 
-extern blk_status_t scsi_init_io(struct scsi_cmnd *cmd);
+blk_status_t scsi_alloc_sgtables(struct scsi_cmnd *cmd);
+void scsi_free_sgtables(struct scsi_cmnd *cmd);
 
 #ifdef CONFIG_SCSI_DMA
 extern int scsi_dma_map(struct scsi_cmnd *cmd);