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[uml-devel] [PATCH] um: Convert ubd driver to blk-mq
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From: Richard W. <ri...@no...> - 2017-12-03 21:49:10
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Convert the driver to the modern blk-mq framework.
As byproduct we get rid of our open coded restart logic and let
blk-mq handle it.
Signed-off-by: Richard Weinberger <ri...@no...>
---
arch/um/drivers/ubd_kern.c | 178 +++++++++++++++++++++++----------------------
1 file changed, 93 insertions(+), 85 deletions(-)
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index b55fe9bf5d3e..deceb8022a28 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -23,6 +23,7 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
#include <linux/ata.h>
#include <linux/hdreg.h>
#include <linux/cdrom.h>
@@ -142,7 +143,6 @@ struct cow {
#define MAX_SG 64
struct ubd {
- struct list_head restart;
/* name (and fd, below) of the file opened for writing, either the
* backing or the cow file. */
char *file;
@@ -156,9 +156,12 @@ struct ubd {
struct cow cow;
struct platform_device pdev;
struct request_queue *queue;
+ struct blk_mq_tag_set tag_set;
spinlock_t lock;
+};
+
+struct ubd_pdu {
struct scatterlist sg[MAX_SG];
- struct request *request;
int start_sg, end_sg;
sector_t rq_pos;
};
@@ -182,10 +185,6 @@ struct ubd {
.shared = 0, \
.cow = DEFAULT_COW, \
.lock = __SPIN_LOCK_UNLOCKED(ubd_devs.lock), \
- .request = NULL, \
- .start_sg = 0, \
- .end_sg = 0, \
- .rq_pos = 0, \
}
/* Protected by ubd_lock */
@@ -196,6 +195,12 @@ static int fake_ide = 0;
static struct proc_dir_entry *proc_ide_root = NULL;
static struct proc_dir_entry *proc_ide = NULL;
+static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
+ const struct blk_mq_queue_data *bd);
+static int ubd_init_request(struct blk_mq_tag_set *set,
+ struct request *req, unsigned int hctx_idx,
+ unsigned int numa_node);
+
static void make_proc_ide(void)
{
proc_ide_root = proc_mkdir("ide", NULL);
@@ -448,11 +453,8 @@ __uml_help(udb_setup,
" in the boot output.\n\n"
);
-static void do_ubd_request(struct request_queue * q);
-
/* Only changed by ubd_init, which is an initcall. */
static int thread_fd = -1;
-static LIST_HEAD(restart);
/* Function to read several request pointers at a time
* handling fractional reads if (and as) needed
@@ -510,9 +512,6 @@ static int bulk_req_safe_read(
/* Called without dev->lock held, and only in interrupt context. */
static void ubd_handler(void)
{
- struct ubd *ubd;
- struct list_head *list, *next_ele;
- unsigned long flags;
int n;
int count;
@@ -532,23 +531,17 @@ static void ubd_handler(void)
return;
}
for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
- blk_end_request(
- (*irq_req_buffer)[count]->req,
- BLK_STS_OK,
- (*irq_req_buffer)[count]->length
- );
- kfree((*irq_req_buffer)[count]);
+ struct io_thread_req *io_req = (*irq_req_buffer)[count];
+ int err = io_req->error ? BLK_STS_IOERR : BLK_STS_OK;
+
+ if (!blk_update_request(io_req->req, err, io_req->length))
+ __blk_mq_end_request(io_req->req, err);
+
+ kfree(io_req);
}
}
- reactivate_fd(thread_fd, UBD_IRQ);
- list_for_each_safe(list, next_ele, &restart){
- ubd = container_of(list, struct ubd, restart);
- list_del_init(&ubd->restart);
- spin_lock_irqsave(&ubd->lock, flags);
- do_ubd_request(ubd->queue);
- spin_unlock_irqrestore(&ubd->lock, flags);
- }
+ reactivate_fd(thread_fd, UBD_IRQ);
}
static irqreturn_t ubd_intr(int irq, void *dev)
@@ -869,6 +862,7 @@ static void ubd_device_release(struct device *dev)
struct ubd *ubd_dev = dev_get_drvdata(dev);
blk_cleanup_queue(ubd_dev->queue);
+ blk_mq_free_tag_set(&ubd_dev->tag_set);
*ubd_dev = ((struct ubd) DEFAULT_UBD);
}
@@ -911,6 +905,11 @@ static int ubd_disk_register(int major, u64 size, int unit,
#define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
+static const struct blk_mq_ops ubd_mq_ops = {
+ .queue_rq = ubd_queue_rq,
+ .init_request = ubd_init_request,
+};
+
static int ubd_add(int n, char **error_out)
{
struct ubd *ubd_dev = &ubd_devs[n];
@@ -927,15 +926,24 @@ static int ubd_add(int n, char **error_out)
ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
- INIT_LIST_HEAD(&ubd_dev->restart);
- sg_init_table(ubd_dev->sg, MAX_SG);
+ ubd_dev->tag_set.ops = &ubd_mq_ops;
+ ubd_dev->tag_set.queue_depth = 64;
+ ubd_dev->tag_set.numa_node = NUMA_NO_NODE;
+ ubd_dev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
+ ubd_dev->tag_set.cmd_size = sizeof(struct ubd_pdu);
+ ubd_dev->tag_set.driver_data = ubd_dev;
+ ubd_dev->tag_set.nr_hw_queues = 1;
- 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";
+ err = blk_mq_alloc_tag_set(&ubd_dev->tag_set);
+ if (err)
goto out;
+
+ ubd_dev->queue = blk_mq_init_queue(&ubd_dev->tag_set);
+ if (IS_ERR(ubd_dev->queue)) {
+ err = PTR_ERR(ubd_dev->queue);
+ goto out_cleanup;
}
+
ubd_dev->queue->queuedata = ubd_dev;
blk_queue_write_cache(ubd_dev->queue, true, false);
@@ -943,7 +951,7 @@ static int ubd_add(int n, char **error_out)
err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]);
if(err){
*error_out = "Failed to register device";
- goto out_cleanup;
+ goto out_cleanup_tags;
}
if (fake_major != UBD_MAJOR)
@@ -961,6 +969,8 @@ static int ubd_add(int n, char **error_out)
out:
return err;
+out_cleanup_tags:
+ blk_mq_free_tag_set(&ubd_dev->tag_set);
out_cleanup:
blk_cleanup_queue(ubd_dev->queue);
goto out;
@@ -1345,80 +1355,78 @@ static void prepare_flush_request(struct request *req,
io_req->op = UBD_FLUSH;
}
-static bool submit_request(struct io_thread_req *io_req, struct ubd *dev)
+static void submit_request(struct io_thread_req *io_req, struct ubd *dev)
{
int n = os_write_file(thread_fd, &io_req,
sizeof(io_req));
+
if (n != sizeof(io_req)) {
if (n != -EAGAIN)
- printk("write to io thread failed, "
- "errno = %d\n", -n);
- else if (list_empty(&dev->restart))
- list_add(&dev->restart, &restart);
+ pr_err("write to io thread failed: %d\n", -n);
+ blk_mq_requeue_request(io_req->req, true);
kfree(io_req);
- return false;
}
- return true;
}
-/* Called with dev->lock held */
-static void do_ubd_request(struct request_queue *q)
+static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
+ const struct blk_mq_queue_data *bd)
{
+ struct request *req = bd->rq;
+ struct ubd *dev = hctx->queue->queuedata;
+ struct ubd_pdu *pdu = blk_mq_rq_to_pdu(req);
struct io_thread_req *io_req;
- struct request *req;
- while(1){
- struct ubd *dev = q->queuedata;
- if(dev->request == NULL){
- struct request *req = blk_fetch_request(q);
- if(req == NULL)
- return;
+ blk_mq_start_request(req);
+
+ pdu->rq_pos = blk_rq_pos(req);
+ pdu->start_sg = 0;
+ pdu->end_sg = blk_rq_map_sg(req->q, req, pdu->sg);
- dev->request = req;
- dev->rq_pos = blk_rq_pos(req);
- dev->start_sg = 0;
- dev->end_sg = blk_rq_map_sg(q, req, dev->sg);
+ if (req_op(req) == REQ_OP_FLUSH) {
+ io_req = kmalloc(sizeof(struct io_thread_req), GFP_ATOMIC);
+ if (io_req == NULL) {
+ blk_mq_requeue_request(req, true);
+ goto done;
}
+ prepare_flush_request(req, io_req);
+ submit_request(io_req, dev);
- req = dev->request;
+ goto done;
+ }
- if (req_op(req) == REQ_OP_FLUSH) {
- io_req = kmalloc(sizeof(struct io_thread_req),
- GFP_ATOMIC);
- if (io_req == NULL) {
- if (list_empty(&dev->restart))
- list_add(&dev->restart, &restart);
- return;
- }
- prepare_flush_request(req, io_req);
- if (submit_request(io_req, dev) == false)
- return;
+ while (pdu->start_sg < pdu->end_sg) {
+ struct scatterlist *sg = &pdu->sg[pdu->start_sg];
+
+ io_req = kmalloc(sizeof(struct io_thread_req),
+ GFP_ATOMIC);
+ if (io_req == NULL) {
+ blk_mq_requeue_request(req, true);
+ goto done;
}
+ prepare_request(req, io_req,
+ (unsigned long long)pdu->rq_pos << 9,
+ sg->offset, sg->length, sg_page(sg));
- while(dev->start_sg < dev->end_sg){
- struct scatterlist *sg = &dev->sg[dev->start_sg];
+ submit_request(io_req, dev);
- io_req = kmalloc(sizeof(struct io_thread_req),
- GFP_ATOMIC);
- if(io_req == NULL){
- if(list_empty(&dev->restart))
- list_add(&dev->restart, &restart);
- return;
- }
- prepare_request(req, io_req,
- (unsigned long long)dev->rq_pos << 9,
- sg->offset, sg->length, sg_page(sg));
+ pdu->rq_pos += sg->length >> 9;
+ pdu->start_sg++;
+ }
- if (submit_request(io_req, dev) == false)
- return;
+done:
+ return BLK_STS_OK;
+}
- dev->rq_pos += sg->length >> 9;
- dev->start_sg++;
- }
- dev->end_sg = 0;
- dev->request = NULL;
- }
+static int ubd_init_request(struct blk_mq_tag_set *set,
+ struct request *req, unsigned int hctx_idx,
+ unsigned int numa_node)
+{
+ struct ubd_pdu *pdu = blk_mq_rq_to_pdu(req);
+
+ sg_init_table(pdu->sg, MAX_SG);
+
+ return 0;
}
static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
--
2.13.6
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