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Message-ID: <20100923201548.GJ20338@redhat.com>
Date: Thu, 23 Sep 2010 16:15:48 -0400
From: Vivek Goyal <vgoyal@...hat.com>
To: linux-kernel@...r.kernel.org, axboe@...nel.dk
Cc: hch@....de
Subject: Re: [PATCH 2/2] atari floppy: Stop sharing request queue across
multiple gendisks
On Thu, Sep 23, 2010 at 03:54:06PM -0400, Vivek Goyal wrote:
> o Use one request queue per gendisk instead of sharing the queue.
>
> o Don't have hardware. No compile testing or run time testing done. Completely
> untested.
>
> Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
> ---
> drivers/block/ataflop.c | 50 ++++++++++++++++++++++++++++++++++++----------
> 1 files changed, 39 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/block/ataflop.c b/drivers/block/ataflop.c
> index aceb964..bad514cb 100644
> --- a/drivers/block/ataflop.c
> +++ b/drivers/block/ataflop.c
> @@ -79,8 +79,8 @@
>
> #undef DEBUG
>
> -static struct request_queue *floppy_queue;
> static struct request *fd_request;
> +static int fdc_queue;
>
> /* Disk types: DD, HD, ED */
> static struct atari_disk_type {
> @@ -1391,6 +1391,29 @@ static void setup_req_params( int drive )
> ReqTrack, ReqSector, (unsigned long)ReqData ));
> }
>
> +/*
> + * Round-robin between our available drives, doing one request from each
> + */
> +static int set_next_request(void)
While scanning the patch found one bug. set_next_request() should be
returning "struct request *". Second version of patch is attached.
o Use one request queue per gendisk instead of sharing the queue.
o Don't have hardware. No compile testing or run time testing done. Completely
untested.
Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
---
drivers/block/ataflop.c | 50 +++++++++++++++++++++++++++++++++++++-----------
1 file changed, 39 insertions(+), 11 deletions(-)
Index: linux-2.6-block/drivers/block/ataflop.c
===================================================================
--- linux-2.6-block.orig/drivers/block/ataflop.c 2010-09-21 15:56:35.000000000 -0400
+++ linux-2.6-block/drivers/block/ataflop.c 2010-09-23 16:12:35.826001335 -0400
@@ -79,8 +79,8 @@
#undef DEBUG
-static struct request_queue *floppy_queue;
static struct request *fd_request;
+static int fdc_queue;
/* Disk types: DD, HD, ED */
static struct atari_disk_type {
@@ -1391,6 +1391,29 @@ static void setup_req_params( int drive
ReqTrack, ReqSector, (unsigned long)ReqData ));
}
+/*
+ * Round-robin between our available drives, doing one request from each
+ */
+static struct request *set_next_request(void)
+{
+ struct request_queue *q;
+ int old_pos = fdc_queue;
+ struct request *rq;
+
+ do {
+ q = unit[fdc_queue].disk->queue;
+ if (++fdc_queue == FD_MAX_UNITS)
+ fdc_queue = 0;
+ if (q) {
+ rq = blk_fetch_request(q);
+ if (rq)
+ break;
+ }
+ } while (fdc_queue != old_pos);
+
+ return rq;
+}
+
static void redo_fd_request(void)
{
@@ -1405,7 +1428,7 @@ static void redo_fd_request(void)
repeat:
if (!fd_request) {
- fd_request = blk_fetch_request(floppy_queue);
+ fd_request = set_next_request();
if (!fd_request)
goto the_end;
}
@@ -1932,10 +1955,6 @@ static int __init atari_floppy_init (voi
PhysTrackBuffer = virt_to_phys(TrackBuffer);
BufferDrive = BufferSide = BufferTrack = -1;
- floppy_queue = blk_init_queue(do_fd_request, &ataflop_lock);
- if (!floppy_queue)
- goto Enomem;
-
for (i = 0; i < FD_MAX_UNITS; i++) {
unit[i].track = -1;
unit[i].flags = 0;
@@ -1944,7 +1963,10 @@ static int __init atari_floppy_init (voi
sprintf(unit[i].disk->disk_name, "fd%d", i);
unit[i].disk->fops = &floppy_fops;
unit[i].disk->private_data = &unit[i];
- unit[i].disk->queue = floppy_queue;
+ unit[i].disk->queue = blk_init_queue(do_fd_request,
+ &ataflop_lock);
+ if (!unit[i].disk->queue)
+ goto Enomem;
set_capacity(unit[i].disk, MAX_DISK_SIZE * 2);
add_disk(unit[i].disk);
}
@@ -1959,10 +1981,14 @@ static int __init atari_floppy_init (voi
return 0;
Enomem:
- while (i--)
+ while (i--) {
+ struct request_queue *q = unit[i].disk->queue;
+
put_disk(unit[i].disk);
- if (floppy_queue)
- blk_cleanup_queue(floppy_queue);
+ if (q)
+ blk_cleanup_queue(q);
+ }
+
unregister_blkdev(FLOPPY_MAJOR, "fd");
return -ENOMEM;
}
@@ -2011,12 +2037,14 @@ static void __exit atari_floppy_exit(voi
int i;
blk_unregister_region(MKDEV(FLOPPY_MAJOR, 0), 256);
for (i = 0; i < FD_MAX_UNITS; i++) {
+ struct request_queue *q = unit[i].disk->queue;
+
del_gendisk(unit[i].disk);
put_disk(unit[i].disk);
+ blk_cleanup_queue(q);
}
unregister_blkdev(FLOPPY_MAJOR, "fd");
- blk_cleanup_queue(floppy_queue);
del_timer_sync(&fd_timer);
atari_stram_free( DMABuffer );
}
--
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