[dm-devel] [RFC PATCH 8/8] rqbased-dm: change dm-multipath from bio-based to request-based
Kiyoshi Ueda
k-ueda at ct.jp.nec.com
Tue Dec 19 22:14:45 UTC 2006
This patch changes multipath target from bio-based to request-based.
Multipath internal queue is deleted because md->queue is used.
md->queue is kept in dm_target for easy access from target drivers.
Target internal data (mpath_io) is allocated in prep_map function
and the destination path is determined there.
Signed-off-by: Kiyoshi Ueda <k-ueda at ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura at ce.jp.nec.com>
diff -rupN 7-rqbase-dm-core/drivers/md/dm-hw-handler.h 8-rqbase-dm-mpath/drivers/md/dm-hw-handler.h
--- 7-rqbase-dm-core/drivers/md/dm-hw-handler.h 2006-12-11 14:32:53.000000000 -0500
+++ 8-rqbase-dm-mpath/drivers/md/dm-hw-handler.h 2006-12-15 10:46:53.000000000 -0500
@@ -34,6 +34,7 @@ struct hw_handler_type {
void (*pg_init) (struct hw_handler *hwh, unsigned bypassed,
struct path *path);
unsigned (*error) (struct hw_handler *hwh, struct bio *bio);
+ unsigned (*error_rq) (struct hw_handler *hwh, struct request *rq);
int (*status) (struct hw_handler *hwh, status_type_t type,
char *result, unsigned int maxlen);
};
diff -rupN 7-rqbase-dm-core/drivers/md/dm-mpath.c 8-rqbase-dm-mpath/drivers/md/dm-mpath.c
--- 7-rqbase-dm-core/drivers/md/dm-mpath.c 2006-12-11 14:32:53.000000000 -0500
+++ 8-rqbase-dm-mpath/drivers/md/dm-mpath.c 2006-12-15 11:04:13.000000000 -0500
@@ -76,8 +76,6 @@ struct multipath {
unsigned queue_if_no_path; /* Queue I/O if last path fails? */
unsigned saved_queue_if_no_path;/* Saved state during suspension */
- struct work_struct process_queued_ios;
- struct bio_list queued_ios;
unsigned queue_size;
struct work_struct trigger_event;
@@ -94,7 +92,7 @@ struct multipath {
*/
struct mpath_io {
struct pgpath *pgpath;
- struct dm_bio_details details;
+ unsigned int err_flags;
};
typedef int (*action_fn) (struct pgpath *pgpath);
@@ -104,7 +102,6 @@ typedef int (*action_fn) (struct pgpath
static kmem_cache_t *_mpio_cache;
struct workqueue_struct *kmultipathd;
-static void process_queued_ios(void *data);
static void trigger_event(void *data);
@@ -173,7 +170,6 @@ static struct multipath *alloc_multipath
INIT_LIST_HEAD(&m->priority_groups);
spin_lock_init(&m->lock);
m->queue_io = 1;
- INIT_WORK(&m->process_queued_ios, process_queued_ios, m);
INIT_WORK(&m->trigger_event, trigger_event, m);
m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
if (!m->mpio_pool) {
@@ -282,10 +278,9 @@ failed:
m->current_pg = NULL;
}
-static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio,
- unsigned was_queued)
+static int prep_map_io(struct multipath *m, struct mpath_io *mpio)
{
- int r = 1;
+ int r = BLKPREP_OK;
unsigned long flags;
struct pgpath *pgpath;
@@ -298,25 +293,38 @@ static int map_io(struct multipath *m, s
pgpath = m->current_pgpath;
- if (was_queued)
- m->queue_size--;
-
if ((pgpath && m->queue_io) ||
(!pgpath && m->queue_if_no_path)) {
- /* Queue for the daemon to resubmit */
- bio_list_add(&m->queued_ios, bio);
- m->queue_size++;
- if ((m->pg_init_required && !m->pg_init_in_progress) ||
- !m->queue_io)
- queue_work(kmultipathd, &m->process_queued_ios);
- pgpath = NULL;
- r = 0;
- } else if (!pgpath)
- r = -EIO; /* Failed */
- else
- bio->bi_bdev = pgpath->path.dev->bdev;
+ /*
+ * Block layer requeue. Will run queue when we get a path,
+ * timeout, or manual intervention.
+ * No need m->ti->queue->queue_lock because of already held.
+ */
+ blk_stop_queue(m->ti->queue);
- mpio->pgpath = pgpath;
+/*
+ * FIXME
+ * hw-handler stuffs are not implemented yet.
+
+ if (m->pg_init_required && !m->pg_init_in_progress) {
+ m->pg_init_required = 0;
+ m->pg_init_in_progress = 1;
+ schedule_work(&mpath->init_pg);
+ }
+*/
+
+ /*
+ * TODO from Mike Christie:
+ * if we have no paths and we are waiting on
+ * queue_if_no_path, set a timer so we do not have to wait
+ * forever or for manual intervantion.
+ */
+
+ r = BLKPREP_DEFER;
+ } else if (pgpath) {
+ mpio->pgpath = pgpath;
+ } else
+ r = BLKPREP_KILL; /* Failed */
spin_unlock_irqrestore(&m->lock, flags);
@@ -338,10 +346,12 @@ static int queue_if_no_path(struct multi
else
m->saved_queue_if_no_path = queue_if_no_path;
m->queue_if_no_path = queue_if_no_path;
- if (!m->queue_if_no_path && m->queue_size)
- queue_work(kmultipathd, &m->process_queued_ios);
- spin_unlock_irqrestore(&m->lock, flags);
+ if (!m->queue_if_no_path) {
+ spin_unlock_irqrestore(&m->lock, flags);
+ dm_start_queue(m->ti->queue);
+ } else
+ spin_unlock_irqrestore(&m->lock, flags);
return 0;
}
@@ -350,73 +360,6 @@ static int queue_if_no_path(struct multi
* The multipath daemon is responsible for resubmitting queued ios.
*---------------------------------------------------------------*/
-static void dispatch_queued_ios(struct multipath *m)
-{
- int r;
- unsigned long flags;
- struct bio *bio = NULL, *next;
- struct mpath_io *mpio;
- union map_info *info;
-
- spin_lock_irqsave(&m->lock, flags);
- bio = bio_list_get(&m->queued_ios);
- spin_unlock_irqrestore(&m->lock, flags);
-
- while (bio) {
- next = bio->bi_next;
- bio->bi_next = NULL;
-
- info = dm_get_mapinfo(bio);
- mpio = info->ptr;
-
- r = map_io(m, bio, mpio, 1);
- if (r < 0)
- bio_endio(bio, bio->bi_size, r);
- else if (r == 1)
- generic_make_request(bio);
-
- bio = next;
- }
-}
-
-static void process_queued_ios(void *data)
-{
- struct multipath *m = (struct multipath *) data;
- struct hw_handler *hwh = &m->hw_handler;
- struct pgpath *pgpath = NULL;
- unsigned init_required = 0, must_queue = 1;
- unsigned long flags;
-
- spin_lock_irqsave(&m->lock, flags);
-
- if (!m->queue_size)
- goto out;
-
- if (!m->current_pgpath)
- __choose_pgpath(m);
-
- pgpath = m->current_pgpath;
-
- if ((pgpath && !m->queue_io) ||
- (!pgpath && !m->queue_if_no_path))
- must_queue = 0;
-
- if (m->pg_init_required && !m->pg_init_in_progress) {
- m->pg_init_required = 0;
- m->pg_init_in_progress = 1;
- init_required = 1;
- }
-
-out:
- spin_unlock_irqrestore(&m->lock, flags);
-
- if (init_required)
- hwh->type->pg_init(hwh, pgpath->pg->bypassed, &pgpath->path);
-
- if (!must_queue)
- dispatch_queued_ios(m);
-}
-
/*
* An event is triggered whenever a path is taken out of use.
* Includes path failure and PG bypass.
@@ -697,6 +640,7 @@ static int multipath_ctr(struct dm_targe
struct arg_set as;
unsigned pg_count = 0;
unsigned next_pg_num;
+ struct mapped_device *md;
as.argc = argc;
as.argv = argv;
@@ -747,6 +691,16 @@ static int multipath_ctr(struct dm_targe
goto bad;
}
+ md = dm_table_get_md(m->ti->table);
+ m->ti->queue = dm_get_queue(md);
+ if (!m->ti->queue) {
+ dm_put(md);
+ ti->error = "can't get queue";
+ r = -EINVAL;
+ goto bad;
+ }
+ dm_put(md);
+
return 0;
bad:
@@ -759,32 +713,69 @@ static void multipath_dtr(struct dm_targ
struct multipath *m = (struct multipath *) ti->private;
flush_workqueue(kmultipathd);
+ dm_put_queue(ti->queue);
free_multipath(m);
}
/*
- * Map bios, recording original fields for later in case we have to resubmit
+ * Called with ti->queue->queue_lock held
*/
-static int multipath_map(struct dm_target *ti, struct bio *bio,
- union map_info *map_context)
+static int multipath_prep_map(struct dm_target *ti, struct request *rq,
+ struct request_queue *q)
{
int r;
struct mpath_io *mpio;
struct multipath *m = (struct multipath *) ti->private;
+ struct dm_map_info *mi;
- if (bio_barrier(bio))
- return -EOPNOTSUPP;
+ if (blk_barrier_rq(rq))
+//FIXME return -EOPNOTSUPP;
+ return BLKPREP_KILL;
+
+ mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
+ if (!mpio)
+ return BLKPREP_DEFER;
+ memset(mpio, 0, sizeof(*mpio));
- mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
- dm_bio_record(&mpio->details, bio);
+ r = prep_map_io(m, mpio);
+ if (r != BLKPREP_OK) {
+ mempool_free(mpio, m->mpio_pool);
+ return r;
+ }
- map_context->ptr = mpio;
- bio->bi_rw |= (1 << BIO_RW_FAILFAST);
- r = map_io(m, bio, mpio, 0);
- if (r < 0)
+ /*
+ * FIXME
+ * memory has to be alloced preliminarily like mempool in md or so.
+ */
+ mi = kzalloc(sizeof(*mi), GFP_ATOMIC);
+ if (!mi) {
mempool_free(mpio, m->mpio_pool);
+ return BLKPREP_DEFER;
+ }
- return r;
+ BUG_ON(!mpio->pgpath);
+
+ mi->devs = mpio->pgpath->path.dev->bdev;
+ mi->map_context.ptr = mpio;
+ //mi->num_devs++;
+ rq->special = mi;
+
+ return BLKPREP_OK;
+}
+
+static int multipath_map_rq(struct dm_target *ti, struct request *clone,
+ union map_info *map_context, struct dm_map_info *mi)
+{
+ struct mpath_io *mpio = (struct mpath_io *)mi->map_context.ptr;
+
+ if (!mpio)
+ BUG();
+
+ clone->cmd_flags |= REQ_FAILFAST;
+ clone->rq_disk = mi->devs->bd_disk;
+ map_context->ptr = mpio;
+
+ return 0;
}
/*
@@ -847,8 +838,11 @@ static int reinstate_path(struct pgpath
pgpath->path.is_active = 1;
m->current_pgpath = NULL;
- if (!m->nr_valid_paths++ && m->queue_size)
- queue_work(kmultipathd, &m->process_queued_ios);
+ if (!m->nr_valid_paths++) {
+ spin_unlock_irqrestore(&m->lock, flags);
+ dm_start_queue(m->ti->queue);
+ spin_lock_irqsave(&m->lock, flags);
+ }
queue_work(kmultipathd, &m->trigger_event);
@@ -980,43 +974,44 @@ void dm_pg_init_complete(struct path *pa
m->queue_io = 0;
m->pg_init_in_progress = 0;
- queue_work(kmultipathd, &m->process_queued_ios);
+/* FIXME
+ dm_start_queue(m->ti->queue);
+*/
spin_unlock_irqrestore(&m->lock, flags);
}
+static void multipath_free_context(struct dm_target *ti, struct request *rq)
+{
+ struct multipath *m = (struct multipath *) ti->private;
+ struct dm_map_info *mi = (struct dm_map_info *) rq->special;
+ struct mpath_io *mpio = (struct mpath_io *) mi->map_context.ptr;
+
+ if (mpio)
+ mempool_free(mpio, m->mpio_pool);
+}
+
/*
* end_io handling
*/
-static int do_end_io(struct multipath *m, struct bio *bio,
- int error, struct mpath_io *mpio)
+static int do_end_io_first(struct multipath *m, struct request *clone,
+ int uptodate, struct mpath_io *mpio)
{
struct hw_handler *hwh = &m->hw_handler;
- unsigned err_flags = MP_FAIL_PATH; /* Default behavior */
+ unsigned err_flags = MP_FAIL_PATH; /* Default behavior */
unsigned long flags;
- if (!error)
- return 0; /* I/O complete */
-
- if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
- return error;
-
- if (error == -EOPNOTSUPP)
- return error;
+ if (!clone->errors && !end_io_error(uptodate))
+ return 0; /* I/O complete */
- spin_lock_irqsave(&m->lock, flags);
- if (!m->nr_valid_paths) {
- if (!m->queue_if_no_path) {
- spin_unlock_irqrestore(&m->lock, flags);
- return -EIO;
- } else {
- spin_unlock_irqrestore(&m->lock, flags);
- goto requeue;
- }
- }
- spin_unlock_irqrestore(&m->lock, flags);
-
- if (hwh->type && hwh->type->error)
- err_flags = hwh->type->error(hwh, bio);
+ /*
+ * TODO: check for different types of errors (transport, device etc)
+ * This is where the block layer error values will come in handy.
+ *
+ * The hw handler just handles its device specific errors (for scsi
+ * this would be when we have a CHECK_CONDITION for example
+ */
+ if (hwh->type && hwh->type->error_rq)
+ err_flags = hwh->type->error_rq(hwh, clone);
if (mpio->pgpath) {
if (err_flags & MP_FAIL_PATH)
@@ -1029,22 +1024,30 @@ static int do_end_io(struct multipath *m
if (err_flags & MP_ERROR_IO)
return -EIO;
- requeue:
- dm_bio_restore(&mpio->details, bio);
-
- /* queue for the daemon to resubmit or fail */
spin_lock_irqsave(&m->lock, flags);
- bio_list_add(&m->queued_ios, bio);
- m->queue_size++;
- if (!m->queue_io)
- queue_work(kmultipathd, &m->process_queued_ios);
+ if (!m->nr_valid_paths) {
+ if (!m->queue_if_no_path) {
+ spin_unlock_irqrestore(&m->lock, flags);
+ return -EIO;
+ }
+ }
spin_unlock_irqrestore(&m->lock, flags);
- return 1; /* io not complete */
+ /* we are going to requeue from end_that_request_last */
+ mpio->err_flags = err_flags;
+
+ /*
+ * For scsi the initial call is with bytes=0 uptodate=1 then from
+ * failfast we get bytes=complete_request uptodate=0. This is our
+ * clone so we can do with it what we want.
+ *
+ * this will not work for old SG_IO ioctls but how cares dm didn't
+ */
+ return clone->hard_nr_sectors > 0 ? 1 : 0;
}
-static int multipath_end_io(struct dm_target *ti, struct bio *bio,
- int error, union map_info *map_context)
+static int multipath_end_io_first(struct dm_target *ti, struct request *clone,
+ int uptodate, union map_info *map_context)
{
struct multipath *m = (struct multipath *) ti->private;
struct mpath_io *mpio = (struct mpath_io *) map_context->ptr;
@@ -1052,18 +1055,34 @@ static int multipath_end_io(struct dm_ta
struct path_selector *ps;
int r;
- r = do_end_io(m, bio, error, mpio);
+ r = do_end_io_first(m, clone, uptodate, mpio);
if (pgpath) {
ps = &pgpath->pg->ps;
if (ps->type->end_io)
ps->type->end_io(ps, &pgpath->path);
}
- if (r <= 0)
- mempool_free(mpio, m->mpio_pool);
return r;
}
+static int multipath_end_io(struct dm_target *ti, struct request *clone,
+ int error, union map_info *map_context)
+{
+ struct multipath *m = (struct multipath *) ti->private;
+ struct mpath_io *mpio = (struct mpath_io *) map_context->ptr;
+ int requeue = 0;
+
+ if (mpio->err_flags) {
+ /* we have parts that need a requeue */
+ DMINFO("requeue request %d\n", error);
+ requeue = 1;
+ }
+
+ mempool_free(mpio, m->mpio_pool);
+
+ return requeue;
+}
+
/*
* Suspend can't complete until all the I/O is processed so if
* the last path fails we must error any remaining I/O.
@@ -1303,8 +1322,11 @@ static struct target_type multipath_targ
.module = THIS_MODULE,
.ctr = multipath_ctr,
.dtr = multipath_dtr,
- .map = multipath_map,
- .end_io = multipath_end_io,
+ .prep_map = multipath_prep_map,
+ .map_rq = multipath_map_rq,
+ .free_context = multipath_free_context,
+ .rq_end_io_first = multipath_end_io_first,
+ .rq_end_io = multipath_end_io,
.presuspend = multipath_presuspend,
.resume = multipath_resume,
.status = multipath_status,
diff -rupN 7-rqbase-dm-core/include/linux/device-mapper.h 8-rqbase-dm-mpath/include/linux/device-mapper.h
--- 7-rqbase-dm-core/include/linux/device-mapper.h 2006-12-15 10:45:34.000000000 -0500
+++ 8-rqbase-dm-mpath/include/linux/device-mapper.h 2006-12-15 10:46:53.000000000 -0500
@@ -165,6 +165,8 @@ struct dm_target {
/* Used to provide an error string from the ctr */
char *error;
+
+ struct request_queue *queue;
};
int dm_register_target(struct target_type *t);
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