linux-kernel - Re: [PATCH] block: export SSD/non-rotational queue flag through sysfs

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Message-Id: <200901052002.15984.bzolnier@gmail.com>
Date:	Mon, 5 Jan 2009 20:02:15 +0100
From:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH] block: export SSD/non-rotational queue flag through sysfs

On Monday 05 January 2009, Jens Axboe wrote:
> On Mon, Jan 05 2009, Bartlomiej Zolnierkiewicz wrote:
> > From: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
> > Subject: [PATCH] block: export SSD/non-rotational queue flag through sysfs
> > 
> > For some devices (i.e. CFA ATA) we can't reliably detect whether
> > the device is of rotational or non-rotational type so we need to
> > leave the final decision about this setting to the user-space.
> 
> I agree with that, was actually planning on doing that myself.
> 
> > @@ -146,8 +167,8 @@ static ssize_t queue_nomerges_store(stru
> >  		queue_flag_set(QUEUE_FLAG_NOMERGES, q);
> >  	else
> >  		queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
> > -
> >  	spin_unlock_irq(q->queue_lock);
> > +
> >  	return ret;
> >  }
> >  
> 
> Hmm?

This is just a "bonus". :)

> > @@ -210,6 +231,12 @@ static struct queue_sysfs_entry queue_hw
> >  	.show = queue_hw_sector_size_show,
> >  };
> >  
> > +static struct queue_sysfs_entry queue_nonrot_entry = {
> > +	.attr = {.name = "nonrot", .mode = S_IRUGO | S_IWUSR },
> > +	.show = queue_nonrot_show,
> > +	.store = queue_nonrot_store,
> > +};
> > +
> 
> Lets please use a better name for export reasons, non-rotational is a
> lot better. Nobody will know what nonrot means :-)

Yeah...

From: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
Subject: [PATCH v2] block: export SSD/non-rotational queue flag through sysfs

For some devices (i.e. CFA ATA) we can't reliably detect whether
the device is of rotational or non-rotational type so we need to
leave the final decision about this setting to the user-space.

As a bonus do a minor CodingStyle fixup in queue_nomerges_store().

Suggested-by: Alan Cox <alan@...rguk.ukuu.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
---
 block/blk-sysfs.c |   30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

Index: b/block/blk-sysfs.c
===================================================================
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -130,6 +130,27 @@ static ssize_t queue_max_hw_sectors_show
 	return queue_var_show(max_hw_sectors_kb, (page));
 }
 
+static ssize_t queue_nonrot_show(struct request_queue *q, char *page)
+{
+	return queue_var_show(blk_queue_nonrot(q), page);
+}
+
+static ssize_t queue_nonrot_store(struct request_queue *q, const char *page,
+				  size_t count)
+{
+	unsigned long nm;
+	ssize_t ret = queue_var_store(&nm, page, count);
+
+	spin_lock_irq(q->queue_lock);
+	if (nm)
+		queue_flag_set(QUEUE_FLAG_NONROT, q);
+	else
+		queue_flag_clear(QUEUE_FLAG_NONROT, q);
+	spin_unlock_irq(q->queue_lock);
+
+	return ret;
+}
+
 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
 {
 	return queue_var_show(blk_queue_nomerges(q), page);
@@ -146,8 +167,8 @@ static ssize_t queue_nomerges_store(stru
 		queue_flag_set(QUEUE_FLAG_NOMERGES, q);
 	else
 		queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
-
 	spin_unlock_irq(q->queue_lock);
+
 	return ret;
 }
 
@@ -210,6 +231,12 @@ static struct queue_sysfs_entry queue_hw
 	.show = queue_hw_sector_size_show,
 };
 
+static struct queue_sysfs_entry queue_nonrot_entry = {
+	.attr = {.name = "non-rotational", .mode = S_IRUGO | S_IWUSR },
+	.show = queue_nonrot_show,
+	.store = queue_nonrot_store,
+};
+
 static struct queue_sysfs_entry queue_nomerges_entry = {
 	.attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
 	.show = queue_nomerges_show,
@@ -229,6 +256,7 @@ static struct attribute *default_attrs[]
 	&queue_max_sectors_entry.attr,
 	&queue_iosched_entry.attr,
 	&queue_hw_sector_size_entry.attr,
+	&queue_nonrot_entry.attr,
 	&queue_nomerges_entry.attr,
 	&queue_rq_affinity_entry.attr,
 	NULL,
--
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