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Message-Id: <200701231927.l0NJRdFx005338@ccure.user-mode-linux.org>
Date: Tue, 23 Jan 2007 14:27:39 -0500
From: Jeff Dike <jdike@...toit.com>
To: akpm@...l.org
cc: linux-kernel@...r.kernel.org,
user-mode-linux-devel@...ts.sourceforge.net
Subject: [PATCH 1/7] UML - Add per-device queues and locks to ubd driver
Replace global queue and lock with per-device queues and locks. Mostly a
straightforward replacement of ubd_io_lock with dev->lock and ubd_queue with
dev->queue.
Complications -
There was no way to get a request struct (and queue) from the
structure sent to the io_thread, so a pointer to the request was
added. This is needed in ubd_handler in order to kick do_ubd_request
to process another request.
Queue initialization is moved from ubd_init to ubd_add.
Signed-off-by: Jeff Dike <jdike@...toit.com>
--
arch/um/drivers/ubd_kern.c | 70 +++++++++++++++++++++++++--------------------
1 file changed, 40 insertions(+), 30 deletions(-)
Index: linux-2.6.18-mm/arch/um/drivers/ubd_kern.c
===================================================================
--- linux-2.6.18-mm.orig/arch/um/drivers/ubd_kern.c 2007-01-17 12:46:25.000000000 +1100
+++ linux-2.6.18-mm/arch/um/drivers/ubd_kern.c 2007-01-17 12:46:28.000000000 +1100
@@ -56,6 +56,7 @@
enum ubd_req { UBD_READ, UBD_WRITE };
struct io_thread_req {
+ struct request *req;
enum ubd_req op;
int fds[2];
unsigned long offsets[2];
@@ -106,10 +107,6 @@ static inline void ubd_set_bit(__u64 bit
#define DRIVER_NAME "uml-blkdev"
-/* Can be taken in interrupt context, and is passed to the block layer to lock
- * the request queue. Kernel side code knows that. */
-static DEFINE_SPINLOCK(ubd_io_lock);
-
static DEFINE_MUTEX(ubd_lock);
/* XXX - this made sense in 2.4 days, now it's only used as a boolean, and
@@ -132,9 +129,6 @@ static const struct block_device_operati
.getgeo = ubd_getgeo,
};
-/* Protected by the queue_lock */
-static request_queue_t *ubd_queue;
-
/* Protected by ubd_lock */
static int fake_major = MAJOR_NR;
@@ -178,6 +172,8 @@ struct ubd {
unsigned no_cow:1;
struct cow cow;
struct platform_device pdev;
+ struct request_queue *queue;
+ spinlock_t lock;
};
#define DEFAULT_COW { \
@@ -198,6 +194,7 @@ struct ubd {
.no_cow = 0, \
.shared = 0, \
.cow = DEFAULT_COW, \
+ .lock = SPIN_LOCK_UNLOCKED, \
}
struct ubd ubd_devs[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
@@ -503,17 +500,20 @@ static void __ubd_finish(struct request
* spin_lock_irq()/spin_lock_irqsave() */
static inline void ubd_finish(struct request *req, int error)
{
- spin_lock(&ubd_io_lock);
+ struct ubd *dev = req->rq_disk->private_data;
+
+ spin_lock(&dev->lock);
__ubd_finish(req, error);
- spin_unlock(&ubd_io_lock);
+ spin_unlock(&dev->lock);
}
/* XXX - move this inside ubd_intr. */
-/* Called without ubd_io_lock held, and only in interrupt context. */
+/* Called without dev->lock held, and only in interrupt context. */
static void ubd_handler(void)
{
struct io_thread_req req;
- struct request *rq = elv_next_request(ubd_queue);
+ struct request *rq;
+ struct ubd *dev;
int n;
do_ubd = 0;
@@ -522,17 +522,17 @@ static void ubd_handler(void)
if(n != sizeof(req)){
printk(KERN_ERR "Pid %d - spurious interrupt in ubd_handler, "
"err = %d\n", os_getpid(), -n);
- spin_lock(&ubd_io_lock);
- end_request(rq, 0);
- spin_unlock(&ubd_io_lock);
return;
}
+ rq = req.req;
+ dev = rq->rq_disk->private_data;
+
ubd_finish(rq, req.error);
- reactivate_fd(thread_fd, UBD_IRQ);
- spin_lock(&ubd_io_lock);
- do_ubd_request(ubd_queue);
- spin_unlock(&ubd_io_lock);
+ reactivate_fd(thread_fd, UBD_IRQ);
+ spin_lock(&dev->lock);
+ do_ubd_request(dev->queue);
+ spin_unlock(&dev->lock);
}
static irqreturn_t ubd_intr(int irq, void *dev)
@@ -663,7 +663,7 @@ static int ubd_disk_register(int major,
}
disk->private_data = &ubd_devs[unit];
- disk->queue = ubd_queue;
+ disk->queue = ubd_devs[unit].queue;
add_disk(disk);
*disk_out = disk;
@@ -688,13 +688,23 @@ static int ubd_add(int n, char **error_o
ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
- err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
- if(err)
+ err = -ENOMEM;
+ ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
+ if (ubd_dev->queue == NULL) {
+ *error_out = "Failed to initialize device queue";
goto out;
+ }
+ ubd_dev->queue->queuedata = ubd_dev;
+
+ err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
+ if(err){
+ *error_out = "Failed to register device";
+ goto out_cleanup;
+ }
if(fake_major != MAJOR_NR)
ubd_disk_register(fake_major, ubd_dev->size, n,
- &fake_gendisk[n]);
+ &fake_gendisk[n]);
/* perhaps this should also be under the "if (fake_major)" above */
/* using the fake_disk->disk_name and also the fakehd_set name */
@@ -704,6 +714,10 @@ static int ubd_add(int n, char **error_o
err = 0;
out:
return err;
+
+out_cleanup:
+ blk_cleanup_queue(ubd_dev->queue);
+ goto out;
}
static int ubd_config(char *str, char **error_out)
@@ -815,6 +829,7 @@ static int ubd_remove(int n, char **erro
fake_gendisk[n] = NULL;
}
+ blk_cleanup_queue(ubd_dev->queue);
platform_device_unregister(&ubd_dev->pdev);
*ubd_dev = ((struct ubd) DEFAULT_UBD);
err = 0;
@@ -868,12 +883,6 @@ static int __init ubd_init(void)
if (register_blkdev(MAJOR_NR, "ubd"))
return -1;
- ubd_queue = blk_init_queue(do_ubd_request, &ubd_io_lock);
- if (!ubd_queue) {
- unregister_blkdev(MAJOR_NR, "ubd");
- return -1;
- }
-
if (fake_major != MAJOR_NR) {
char name[sizeof("ubd_nnn\0")];
@@ -1019,7 +1028,7 @@ static void cowify_req(struct io_thread_
req->bitmap_words, bitmap_len);
}
-/* Called with ubd_io_lock held */
+/* Called with dev->lock held */
static int prepare_request(struct request *req, struct io_thread_req *io_req)
{
struct gendisk *disk = req->rq_disk;
@@ -1038,6 +1047,7 @@ static int prepare_request(struct reques
offset = ((__u64) req->sector) << 9;
len = req->current_nr_sectors << 9;
+ io_req->req = req;
io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd : ubd_dev->fd;
io_req->fds[1] = ubd_dev->fd;
io_req->cow_offset = -1;
@@ -1059,7 +1069,7 @@ static int prepare_request(struct reques
return(0);
}
-/* Called with ubd_io_lock held */
+/* Called with dev->lock held */
static void do_ubd_request(request_queue_t *q)
{
struct io_thread_req io_req;
-
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