scsi: reintroduce scsi_driver.init_command

Instead of letting the ULD play games with the prep_fn move back to
the model of a central prep_fn with a callback to the ULD.  This
already cleans up and shortens the code by itself, and will be required
to properly support blk-mq in the SCSI midlayer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nicholas Bellinger <nab@linux-iscsi.org>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Hannes Reinecke <hare@suse.de>

4 files changed, 62 insertions, 76 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 045822befad9..9f841df6add8 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1073,15 +1073,7 @@ static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
 
 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
 {
-        struct scsi_cmnd *cmd;
-        int ret = scsi_prep_state_check(sdev, req);
-
-        if (ret != BLKPREP_OK)
-                return ret;
-
-        cmd = scsi_get_cmd_from_req(sdev, req);
-        if (unlikely(!cmd))
-                return BLKPREP_DEFER;
+        struct scsi_cmnd *cmd = req->special;
 
         /*
          * BLOCK_PC requests may transfer data, in which case they must
@@ -1125,15 +1117,11 @@ EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
  */
 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
 {
-        struct scsi_cmnd *cmd;
-        int ret = scsi_prep_state_check(sdev, req);
-
-        if (ret != BLKPREP_OK)
-                return ret;
+        struct scsi_cmnd *cmd = req->special;
 
         if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
                          && sdev->scsi_dh_data->scsi_dh->prep_fn)) {
-                ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
+                int ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
                 if (ret != BLKPREP_OK)
                         return ret;
         }
@@ -1143,16 +1131,13 @@ int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
          */
         BUG_ON(!req->nr_phys_segments);
 
-        cmd = scsi_get_cmd_from_req(sdev, req);
-        if (unlikely(!cmd))
-                return BLKPREP_DEFER;
-
         memset(cmd->cmnd, 0, BLK_MAX_CDB);
         return scsi_init_io(cmd, GFP_ATOMIC);
 }
 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
 
-int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
+static int
+scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
 {
         int ret = BLKPREP_OK;
 
@@ -1204,9 +1189,9 @@ int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
         }
         return ret;
 }
-EXPORT_SYMBOL(scsi_prep_state_check);
 
-int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
+static int
+scsi_prep_return(struct request_queue *q, struct request *req, int ret)
 {
         struct scsi_device *sdev = q->queuedata;
 
@@ -1237,18 +1222,44 @@ int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
 
         return ret;
 }
-EXPORT_SYMBOL(scsi_prep_return);
 
-int scsi_prep_fn(struct request_queue *q, struct request *req)
+static int scsi_prep_fn(struct request_queue *q, struct request *req)
 {
         struct scsi_device *sdev = q->queuedata;
-        int ret = BLKPREP_KILL;
+        struct scsi_cmnd *cmd;
+        int ret;
 
-        if (req->cmd_type == REQ_TYPE_BLOCK_PC)
+        ret = scsi_prep_state_check(sdev, req);
+        if (ret != BLKPREP_OK)
+                goto out;
+
+        cmd = scsi_get_cmd_from_req(sdev, req);
+        if (unlikely(!cmd)) {
+                ret = BLKPREP_DEFER;
+                goto out;
+        }
+
+        if (req->cmd_type == REQ_TYPE_FS)
+                ret = scsi_cmd_to_driver(cmd)->init_command(cmd);
+        else if (req->cmd_type == REQ_TYPE_BLOCK_PC)
                 ret = scsi_setup_blk_pc_cmnd(sdev, req);
+        else
+                ret = BLKPREP_KILL;
+
+out:
         return scsi_prep_return(q, req, ret);
 }
-EXPORT_SYMBOL(scsi_prep_fn);
+
+static void scsi_unprep_fn(struct request_queue *q, struct request *req)
+{
+        if (req->cmd_type == REQ_TYPE_FS) {
+                struct scsi_cmnd *cmd = req->special;
+                struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
+
+                if (drv->uninit_command)
+                        drv->uninit_command(cmd);
+        }
+}
 
 /*
  * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
@@ -1669,6 +1680,7 @@ struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
                 return NULL;
 
         blk_queue_prep_rq(q, scsi_prep_fn);
+        blk_queue_unprep_rq(q, scsi_unprep_fn);
         blk_queue_softirq_done(q, scsi_softirq_done);
         blk_queue_rq_timed_out(q, scsi_times_out);
         blk_queue_lld_busy(q, scsi_lld_busy);
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index efcbcd182863..aa028d8ae774 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -109,6 +109,8 @@ static int sd_suspend_system(struct device *);
 static int sd_suspend_runtime(struct device *);
 static int sd_resume(struct device *);
 static void sd_rescan(struct device *);
+static int sd_init_command(struct scsi_cmnd *SCpnt);
+static void sd_uninit_command(struct scsi_cmnd *SCpnt);
 static int sd_done(struct scsi_cmnd *);
 static int sd_eh_action(struct scsi_cmnd *, int);
 static void sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer);
@@ -503,6 +505,8 @@ static struct scsi_driver sd_template = {
                 .pm             = &sd_pm_ops,
         },
         .rescan                 = sd_rescan,
+        .init_command           = sd_init_command,
+        .uninit_command         = sd_uninit_command,
         .done                   = sd_done,
         .eh_action              = sd_eh_action,
 };
@@ -838,9 +842,9 @@ static int scsi_setup_flush_cmnd(struct scsi_device *sdp, struct request *rq)
         return scsi_setup_blk_pc_cmnd(sdp, rq);
 }
 
-static void sd_unprep_fn(struct request_queue *q, struct request *rq)
+static void sd_uninit_command(struct scsi_cmnd *SCpnt)
 {
-        struct scsi_cmnd *SCpnt = rq->special;
+        struct request *rq = SCpnt->request;
 
         if (rq->cmd_flags & REQ_DISCARD) {
                 free_page((unsigned long)rq->buffer);
@@ -853,18 +857,10 @@ static void sd_unprep_fn(struct request_queue *q, struct request *rq)
         }
 }
 
-/**
- *      sd_prep_fn - build a scsi (read or write) command from
- *      information in the request structure.
- *      @SCpnt: pointer to mid-level's per scsi command structure that
- *      contains request and into which the scsi command is written
- *
- *      Returns 1 if successful and 0 if error (or cannot be done now).
- **/
-static int sd_prep_fn(struct request_queue *q, struct request *rq)
+static int sd_init_command(struct scsi_cmnd *SCpnt)
 {
-        struct scsi_cmnd *SCpnt;
-        struct scsi_device *sdp = q->queuedata;
+        struct request *rq = SCpnt->request;
+        struct scsi_device *sdp = SCpnt->device;
         struct gendisk *disk = rq->rq_disk;
         struct scsi_disk *sdkp;
         sector_t block = blk_rq_pos(rq);
@@ -886,12 +882,6 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq)
         } else if (rq->cmd_flags & REQ_FLUSH) {
                 ret = scsi_setup_flush_cmnd(sdp, rq);
                 goto out;
-        } else if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
-                ret = scsi_setup_blk_pc_cmnd(sdp, rq);
-                goto out;
-        } else if (rq->cmd_type != REQ_TYPE_FS) {
-                ret = BLKPREP_KILL;
-                goto out;
         }
         ret = scsi_setup_fs_cmnd(sdp, rq);
         if (ret != BLKPREP_OK)
@@ -903,11 +893,10 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq)
          * is used for a killable error condition */
         ret = BLKPREP_KILL;
 
-        SCSI_LOG_HLQUEUE(1, scmd_printk(KERN_INFO, SCpnt,
-                                        "sd_prep_fn: block=%llu, "
-                                        "count=%d\n",
-                                        (unsigned long long)block,
-                                        this_count));
+        SCSI_LOG_HLQUEUE(1,
+                scmd_printk(KERN_INFO, SCpnt,
+                        "%s: block=%llu, count=%d\n",
+                        __func__, (unsigned long long)block, this_count));
 
         if (!sdp || !scsi_device_online(sdp) ||
             block + blk_rq_sectors(rq) > get_capacity(disk)) {
@@ -1127,7 +1116,7 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq)
          */
         ret = BLKPREP_OK;
  out:
-        return scsi_prep_return(q, rq, ret);
+        return ret;
 }
 
 /**
@@ -2878,9 +2867,6 @@ static void sd_probe_async(void *data, async_cookie_t cookie)
 
         sd_revalidate_disk(gd);
 
-        blk_queue_prep_rq(sdp->request_queue, sd_prep_fn);
-        blk_queue_unprep_rq(sdp->request_queue, sd_unprep_fn);
-
         gd->driverfs_dev = &sdp->sdev_gendev;
         gd->flags = GENHD_FL_EXT_DEVT;
         if (sdp->removable) {
@@ -3028,8 +3014,6 @@ static int sd_remove(struct device *dev)
 
         async_synchronize_full_domain(&scsi_sd_pm_domain);
         async_synchronize_full_domain(&scsi_sd_probe_domain);
-        blk_queue_prep_rq(sdkp->device->request_queue, scsi_prep_fn);
-        blk_queue_unprep_rq(sdkp->device->request_queue, NULL);
         device_del(&sdkp->dev);
         del_gendisk(sdkp->disk);
         sd_shutdown(dev);
diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 40d85929aefe..93cbd36c990b 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -79,6 +79,7 @@ MODULE_ALIAS_SCSI_DEVICE(TYPE_WORM);
 static DEFINE_MUTEX(sr_mutex);
 static int sr_probe(struct device *);
 static int sr_remove(struct device *);
+static int sr_init_command(struct scsi_cmnd *SCpnt);
 static int sr_done(struct scsi_cmnd *);
 static int sr_runtime_suspend(struct device *dev);
 
@@ -94,6 +95,7 @@ static struct scsi_driver sr_template = {
                 .remove         = sr_remove,
                 .pm             = &sr_pm_ops,
         },
+        .init_command           = sr_init_command,
         .done                   = sr_done,
 };
 
@@ -378,21 +380,14 @@ static int sr_done(struct scsi_cmnd *SCpnt)
         return good_bytes;
 }
 
-static int sr_prep_fn(struct request_queue *q, struct request *rq)
+static int sr_init_command(struct scsi_cmnd *SCpnt)
 {
         int block = 0, this_count, s_size;
         struct scsi_cd *cd;
-        struct scsi_cmnd *SCpnt;
-        struct scsi_device *sdp = q->queuedata;
+        struct request *rq = SCpnt->request;
+        struct scsi_device *sdp = SCpnt->device;
         int ret;
 
-        if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
-                ret = scsi_setup_blk_pc_cmnd(sdp, rq);
-                goto out;
-        } else if (rq->cmd_type != REQ_TYPE_FS) {
-                ret = BLKPREP_KILL;
-                goto out;
-        }
         ret = scsi_setup_fs_cmnd(sdp, rq);
         if (ret != BLKPREP_OK)
                 goto out;
@@ -517,7 +512,7 @@ static int sr_prep_fn(struct request_queue *q, struct request *rq)
          */
         ret = BLKPREP_OK;
  out:
-        return scsi_prep_return(q, rq, ret);
+        return ret;
 }
 
 static int sr_block_open(struct block_device *bdev, fmode_t mode)
@@ -718,7 +713,6 @@ static int sr_probe(struct device *dev)
 
         /* FIXME: need to handle a get_capabilities failure properly ?? */
         get_capabilities(cd);
-        blk_queue_prep_rq(sdev->request_queue, sr_prep_fn);
         sr_vendor_init(cd);
 
         disk->driverfs_dev = &sdev->sdev_gendev;
@@ -993,7 +987,6 @@ static int sr_remove(struct device *dev)
 
         scsi_autopm_get_device(cd->device);
 
-        blk_queue_prep_rq(cd->device->request_queue, scsi_prep_fn);
         del_gendisk(cd->disk);
 
         mutex_lock(&sr_ref_mutex);
diff --git a/include/scsi/scsi_driver.h b/include/scsi/scsi_driver.h
index 20fdfc2526ad..36c4114ed9bc 100644
--- a/include/scsi/scsi_driver.h
+++ b/include/scsi/scsi_driver.h
@@ -4,17 +4,17 @@
 #include <linux/device.h>
 
 struct module;
+struct request;
 struct scsi_cmnd;
 struct scsi_device;
-struct request;
-struct request_queue;
-
 
 struct scsi_driver {
         struct module           *owner;
         struct device_driver    gendrv;
 
         void (*rescan)(struct device *);
+        int (*init_command)(struct scsi_cmnd *);
+        void (*uninit_command)(struct scsi_cmnd *);
         int (*done)(struct scsi_cmnd *);
         int (*eh_action)(struct scsi_cmnd *, int);
 };
@@ -31,8 +31,5 @@ extern int scsi_register_interface(struct class_interface *);
 
 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req);
 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req);
-int scsi_prep_state_check(struct scsi_device *sdev, struct request *req);
-int scsi_prep_return(struct request_queue *q, struct request *req, int ret);
-int scsi_prep_fn(struct request_queue *, struct request *);
 
 #endif /* _SCSI_SCSI_DRIVER_H */