Skip to content

Commit

Permalink
um: Convert ubd driver to blk-mq
Browse files Browse the repository at this point in the history 
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 <richard@nod.at>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
  • Loading branch information
Richard Weinberger authored and Jens Axboe committed Oct 14, 2018
1 parent 6d1f9df commit 4e6da0f
Showing 1 changed file with 93 additions and 85 deletions.
178 changes: 93 additions & 85 deletions arch/um/drivers/ubd_kern.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -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;
Expand All @@ -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;
};
Expand All @@ -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 */
Expand All @@ -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);
Expand Down Expand Up @@ -436,11 +441,8 @@ __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
Expand Down Expand Up @@ -498,9 +500,6 @@ 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;

Expand All @@ -520,23 +519,17 @@ 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)
Expand Down Expand Up @@ -857,6 +850,7 @@ 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);
}

Expand Down Expand Up @@ -899,6 +893,11 @@ 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];
Expand All @@ -915,23 +914,32 @@ 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);

blk_queue_max_segments(ubd_dev->queue, MAX_SG);
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)
Expand All @@ -949,6 +957,8 @@ 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;
Expand Down Expand Up @@ -1333,80 +1343,78 @@ 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)
Expand Down

0 comments on commit 4e6da0f

Please sign in to comment.