* [PATCH v2] notify block layer when using temporary change to cache_type
@ 2014-06-03 9:37 Vaughan Cao
2014-06-11 12:07 ` Christoph Hellwig
0 siblings, 1 reply; 2+ messages in thread
From: Vaughan Cao @ 2014-06-03 9:37 UTC (permalink / raw)
To: JBottomley; +Cc: hch, linux-scsi, linux-kernel, vaughan.cao
This is a fix for commit:
39c60a0948cc06139e2fbfe084f83cb7e7deae3b sd: fix array cache flushing bug causing performance problems
We must notify the block layer via q->flush_flags after temporary change the cache_type to write through.
If not, SYNCHRONIZE CACHE command will still be generated.
This patch factors out a helper that can be called from sd_revalidate_disk and cache_type_store.
Signed-off-by: Vaughan Cao <vaughan.cao@oracle.com>
---
drivers/scsi/sd.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index efcbcd1..e4774aa 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -132,6 +132,19 @@ static const char *sd_cache_types[] = {
"write back, no read (daft)"
};
+static void sd_set_flush_flag(struct scsi_disk *sdkp)
+{
+ unsigned flush = 0;
+
+ if (sdkp->WCE) {
+ flush |= REQ_FLUSH;
+ if (sdkp->DPOFUA)
+ flush |= REQ_FUA;
+ }
+
+ blk_queue_flush(sdkp->disk->queue, flush);
+}
+
static ssize_t
cache_type_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
@@ -175,6 +188,7 @@ cache_type_store(struct device *dev, struct device_attribute *attr,
if (sdkp->cache_override) {
sdkp->WCE = wce;
sdkp->RCD = rcd;
+ sd_set_flush_flag(sdkp);
return count;
}
@@ -2712,7 +2726,6 @@ static int sd_revalidate_disk(struct gendisk *disk)
struct scsi_disk *sdkp = scsi_disk(disk);
struct scsi_device *sdp = sdkp->device;
unsigned char *buffer;
- unsigned flush = 0;
SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
"sd_revalidate_disk\n"));
@@ -2758,13 +2771,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
* We now have all cache related info, determine how we deal
* with flush requests.
*/
- if (sdkp->WCE) {
- flush |= REQ_FLUSH;
- if (sdkp->DPOFUA)
- flush |= REQ_FUA;
- }
-
- blk_queue_flush(sdkp->disk->queue, flush);
+ sd_set_flush_flag(sdkp);
set_capacity(disk, sdkp->capacity);
sd_config_write_same(sdkp);
--
1.9.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] notify block layer when using temporary change to cache_type
2014-06-03 9:37 [PATCH v2] notify block layer when using temporary change to cache_type Vaughan Cao
@ 2014-06-11 12:07 ` Christoph Hellwig
0 siblings, 0 replies; 2+ messages in thread
From: Christoph Hellwig @ 2014-06-11 12:07 UTC (permalink / raw)
To: Vaughan Cao; +Cc: JBottomley, hch, linux-scsi, linux-kernel
On Tue, Jun 03, 2014 at 05:37:30PM +0800, Vaughan Cao wrote:
> This is a fix for commit:
> 39c60a0948cc06139e2fbfe084f83cb7e7deae3b sd: fix array cache flushing bug causing performance problems
> We must notify the block layer via q->flush_flags after temporary change the cache_type to write through.
> If not, SYNCHRONIZE CACHE command will still be generated.
> This patch factors out a helper that can be called from sd_revalidate_disk and cache_type_store.
>
> Signed-off-by: Vaughan Cao <vaughan.cao@oracle.com>
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2014-06-11 12:07 ` Christoph Hellwig
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