Re: [PATCH linux-2.6-block:post-2.6.15 04/10] blk: update SCSI to use new blk_ordered

From: Tejun Heo
Date: Thu Nov 17 2005 - 10:37:25 EST

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04_blk_scsi-update-ordered.patch

All ordered request related stuff delegated to HLD. Midlayer
now doens't deal with ordered setting or prepare_flush
callback. sd.c updated to deal with blk_queue_ordered
setting. Currently, ordered tag isn't used as SCSI midlayer
cannot guarantee request ordering.

Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>

drivers/scsi/hosts.c | 9 ------
drivers/scsi/scsi_lib.c | 46 ----------------------------------
drivers/scsi/sd.c | 60 ++++++++++++++++-----------------------------
include/scsi/scsi_driver.h | 1
include/scsi/scsi_host.h | 1
5 files changed, 22 insertions(+), 95 deletions(-)

Index: work/drivers/scsi/hosts.c
===================================================================
--- work.orig/drivers/scsi/hosts.c 2005-11-18 00:14:21.000000000 +0900
+++ work/drivers/scsi/hosts.c 2005-11-18 00:35:05.000000000 +0900
@@ -347,17 +347,8 @@ struct Scsi_Host *scsi_host_alloc(struct
shost->cmd_per_lun = sht->cmd_per_lun;
shost->unchecked_isa_dma = sht->unchecked_isa_dma;
shost->use_clustering = sht->use_clustering;
- shost->ordered_flush = sht->ordered_flush;
shost->ordered_tag = sht->ordered_tag;

- /*
- * hosts/devices that do queueing must support ordered tags
- */
- if (shost->can_queue > 1 && shost->ordered_flush) {
- printk(KERN_ERR "scsi: ordered flushes don't support queueing\n");
- shost->ordered_flush = 0;
- }
-
if (sht->max_host_blocked)
shost->max_host_blocked = sht->max_host_blocked;
else
Index: work/drivers/scsi/scsi_lib.c
===================================================================
--- work.orig/drivers/scsi/scsi_lib.c 2005-11-18 00:35:04.000000000 +0900
+++ work/drivers/scsi/scsi_lib.c 2005-11-18 00:35:05.000000000 +0900
@@ -765,9 +765,6 @@ void scsi_io_completion(struct scsi_cmnd
int sense_valid = 0;
int sense_deferred = 0;

- if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
- return;
-
/*
* Free up any indirection buffers we allocated for DMA purposes.
* For the case of a READ, we need to copy the data out of the
@@ -1031,38 +1028,6 @@ static int scsi_init_io(struct scsi_cmnd
return BLKPREP_KILL;
}

-static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
-{
- struct scsi_device *sdev = q->queuedata;
- struct scsi_driver *drv;
-
- if (sdev->sdev_state == SDEV_RUNNING) {
- drv = *(struct scsi_driver **) rq->rq_disk->private_data;
-
- if (drv->prepare_flush)
- return drv->prepare_flush(q, rq);
- }
-
- return 0;
-}
-
-static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
-{
- struct scsi_device *sdev = q->queuedata;
- struct request *flush_rq = rq->end_io_data;
- struct scsi_driver *drv;
-
- if (flush_rq->errors) {
- printk("scsi: barrier error, disabling flush support\n");
- blk_queue_ordered(q, QUEUE_ORDERED_NONE);
- }
-
- if (sdev->sdev_state == SDEV_RUNNING) {
- drv = *(struct scsi_driver **) rq->rq_disk->private_data;
- drv->end_flush(q, rq);
- }
-}
-
static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
sector_t *error_sector)
{
@@ -1520,17 +1485,6 @@ struct request_queue *scsi_alloc_queue(s
blk_queue_segment_boundary(q, shost->dma_boundary);
blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);

- /*
- * ordered tags are superior to flush ordering
- */
- if (shost->ordered_tag)
- blk_queue_ordered(q, QUEUE_ORDERED_TAG);
- else if (shost->ordered_flush) {
- blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
- q->prepare_flush_fn = scsi_prepare_flush_fn;
- q->end_flush_fn = scsi_end_flush_fn;
- }
-
if (!shost->use_clustering)
clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
return q;
Index: work/drivers/scsi/sd.c
===================================================================
--- work.orig/drivers/scsi/sd.c 2005-11-18 00:35:04.000000000 +0900
+++ work/drivers/scsi/sd.c 2005-11-18 00:35:05.000000000 +0900
@@ -121,8 +121,7 @@ static void sd_shutdown(struct device *d
static void sd_rescan(struct device *);
static int sd_init_command(struct scsi_cmnd *);
static int sd_issue_flush(struct device *, sector_t *);
-static void sd_end_flush(request_queue_t *, struct request *);
-static int sd_prepare_flush(request_queue_t *, struct request *);
+static void sd_prepare_flush(request_queue_t *, struct request *);
static void sd_read_capacity(struct scsi_disk *sdkp, char *diskname,
unsigned char *buffer);

@@ -137,8 +136,6 @@ static struct scsi_driver sd_template =
.rescan = sd_rescan,
.init_command = sd_init_command,
.issue_flush = sd_issue_flush,
- .prepare_flush = sd_prepare_flush,
- .end_flush = sd_end_flush,
};

/*
@@ -743,42 +740,13 @@ static int sd_issue_flush(struct device
return ret;
}

-static void sd_end_flush(request_queue_t *q, struct request *flush_rq)
+static void sd_prepare_flush(request_queue_t *q, struct request *rq)
{
- struct request *rq = flush_rq->end_io_data;
- struct scsi_cmnd *cmd = rq->special;
- unsigned int bytes = rq->hard_nr_sectors << 9;
-
- if (!flush_rq->errors) {
- spin_unlock(q->queue_lock);
- scsi_io_completion(cmd, bytes, 0);
- spin_lock(q->queue_lock);
- } else if (blk_barrier_postflush(rq)) {
- spin_unlock(q->queue_lock);
- scsi_io_completion(cmd, 0, bytes);
- spin_lock(q->queue_lock);
- } else {
- /*
- * force journal abort of barriers
- */
- end_that_request_first(rq, -EOPNOTSUPP, rq->hard_nr_sectors);
- end_that_request_last(rq, -EOPNOTSUPP);
- }
-}
-
-static int sd_prepare_flush(request_queue_t *q, struct request *rq)
-{
- struct scsi_device *sdev = q->queuedata;
- struct scsi_disk *sdkp = dev_get_drvdata(&sdev->sdev_gendev);
-
- if (!sdkp || !sdkp->WCE)
- return 0;
-
memset(rq->cmd, 0, sizeof(rq->cmd));
- rq->flags |= REQ_BLOCK_PC | REQ_SOFTBARRIER;
+ rq->flags |= REQ_BLOCK_PC;
rq->timeout = SD_TIMEOUT;
rq->cmd[0] = SYNCHRONIZE_CACHE;
- return 1;
+ rq->cmd_len = 10;
}

static void sd_rescan(struct device *dev)
@@ -1476,6 +1444,7 @@ static int sd_revalidate_disk(struct gen
struct scsi_disk *sdkp = scsi_disk(disk);
struct scsi_device *sdp = sdkp->device;
unsigned char *buffer;
+ unsigned ordered;

SCSI_LOG_HLQUEUE(3, printk("sd_revalidate_disk: disk=%s\n", disk->disk_name));

@@ -1514,7 +1483,21 @@ static int sd_revalidate_disk(struct gen
buffer);
sd_read_cache_type(sdkp, disk->disk_name, buffer);
}
-
+
+ /*
+ * We now have all cache related info, determine how we deal
+ * with ordered requests. Note that as the current SCSI
+ * dispatch function can alter request order, we cannot use
+ * QUEUE_ORDERED_TAG_* even when ordered tag is supported.
+ */
+ if (sdkp->WCE)
+ ordered = QUEUE_ORDERED_DRAIN_FLUSH;
+ else
+ ordered = QUEUE_ORDERED_DRAIN;
+
+ blk_queue_ordered(sdkp->disk->queue, ordered, sd_prepare_flush,
+ GFP_KERNEL);
+
set_capacity(disk, sdkp->capacity);
kfree(buffer);

@@ -1614,6 +1597,7 @@ static int sd_probe(struct device *dev)
strcpy(gd->devfs_name, sdp->devfs_name);

gd->private_data = &sdkp->driver;
+ gd->queue = sdkp->device->request_queue;

sd_revalidate_disk(gd);

@@ -1621,7 +1605,6 @@ static int sd_probe(struct device *dev)
gd->flags = GENHD_FL_DRIVERFS;
if (sdp->removable)
gd->flags |= GENHD_FL_REMOVABLE;
- gd->queue = sdkp->device->request_queue;

dev_set_drvdata(dev, sdkp);
add_disk(gd);
@@ -1654,6 +1637,7 @@ static int sd_remove(struct device *dev)
{
struct scsi_disk *sdkp = dev_get_drvdata(dev);

+ blk_queue_ordered(sdkp->disk->queue, QUEUE_ORDERED_NONE, NULL, 0);
del_gendisk(sdkp->disk);
sd_shutdown(dev);

Index: work/include/scsi/scsi_driver.h
===================================================================
--- work.orig/include/scsi/scsi_driver.h 2005-11-18 00:06:46.000000000 +0900
+++ work/include/scsi/scsi_driver.h 2005-11-18 00:35:05.000000000 +0900
@@ -15,7 +15,6 @@ struct scsi_driver {
void (*rescan)(struct device *);
int (*issue_flush)(struct device *, sector_t *);
int (*prepare_flush)(struct request_queue *, struct request *);
- void (*end_flush)(struct request_queue *, struct request *);
};
#define to_scsi_driver(drv) \
container_of((drv), struct scsi_driver, gendrv)
Index: work/include/scsi/scsi_host.h
===================================================================
--- work.orig/include/scsi/scsi_host.h 2005-11-18 00:14:29.000000000 +0900
+++ work/include/scsi/scsi_host.h 2005-11-18 00:35:05.000000000 +0900
@@ -392,7 +392,6 @@ struct scsi_host_template {
/*
* ordered write support
*/
- unsigned ordered_flush:1;
unsigned ordered_tag:1;

/*

-
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Next message: Tejun Heo: "Re: [PATCH linux-2.6-block:post-2.6.15 05/10] blk: add FUA support to SCSI disk"
Previous message: Tejun Heo: "Re: [PATCH linux-2.6-block:post-2.6.15 02/10] blk: separate out bio init part from __make_request"
In reply to: Tejun Heo: "Re: [PATCH linux-2.6-block:post-2.6.15 02/10] blk: separate out bio init part from __make_request"
Next in thread: Tejun Heo: "Re: [PATCH linux-2.6-block:post-2.6.15 05/10] blk: add FUA support to SCSI disk"
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