This patch converts dm-multipath target driver to request-based.
Request-based dm itself is still under development and not ready
for inclusion.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
---
dm-mpath.c | 227 +++++++++++++++++++++++++++++++++++++++++---------------- dm-rq-record.h | 36 +++++++++
2 files changed, 203 insertions(+), 60 deletions(-)
diff -rupN a1-rqdm-core/drivers/md/dm-mpath.c a2-rqdm-mpath/drivers/md/dm-mpath.c
--- a1-rqdm-core/drivers/md/dm-mpath.c 2007-08-13 00:25:24.000000000 -0400
+++ a2-rqdm-mpath/drivers/md/dm-mpath.c 2007-08-29 14:07:39.000000000 -0400
@@ -8,8 +8,7 @@
#include "dm.h"
#include "dm-path-selector.h"
#include "dm-hw-handler.h"
-#include "dm-bio-list.h"
-#include "dm-bio-record.h"
+#include "dm-rq-record.h"
#include <linux/ctype.h>
#include <linux/init.h>
@@ -77,7 +76,7 @@ struct multipath {
unsigned saved_queue_if_no_path;/* Saved state during suspension */
struct work_struct process_queued_ios;
- struct bio_list queued_ios;
+ struct list_head queued_ios;
unsigned queue_size;
struct work_struct trigger_event;
@@ -86,22 +85,22 @@ struct multipath {
* We must use a mempool of dm_mpath_io structs so that we
* can resubmit bios on error.
*/
- mempool_t *mpio_pool;
+ mempool_t *mpio_pool; //REMOVE ME
};
/*
* Context information attached to each bio we process.
*/
-struct dm_mpath_io {
+struct dm_mpath_io { //REMOVE ME
struct pgpath *pgpath;
- struct dm_bio_details details;
+ struct dm_rq_details details;
};
typedef int (*action_fn) (struct pgpath *pgpath);
#define MIN_IOS 256 /* Mempool size */
-static struct kmem_cache *_mpio_cache;
+static struct kmem_cache *_mpio_cache; //REMOVE ME
struct workqueue_struct *kmultipathd;
static void process_queued_ios(struct work_struct *work);
@@ -171,6 +170,7 @@ static struct multipath *alloc_multipath
m = kzalloc(sizeof(*m), GFP_KERNEL);
if (m) {
INIT_LIST_HEAD(&m->priority_groups);
+ INIT_LIST_HEAD(&m->queued_ios);
spin_lock_init(&m->lock);
m->queue_io = 1;
INIT_WORK(&m->process_queued_ios, process_queued_ios);
@@ -299,7 +299,7 @@ static int __must_push_back(struct multi
dm_noflush_suspending(m->ti));
}
-static int map_io(struct multipath *m, struct bio *bio,
+static int map_io(struct multipath *m, struct request *clone,
struct dm_mpath_io *mpio, unsigned was_queued)
{
int r = DM_MAPIO_REMAPPED;
@@ -321,19 +321,27 @@ static int map_io(struct multipath *m, s
if ((pgpath && m->queue_io) ||
(!pgpath && m->queue_if_no_path)) {
/* Queue for the daemon to resubmit */
- bio_list_add(&m->queued_ios, bio);
+ list_add_tail(&clone->queuelist, &m->queued_ios);
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;
+ clone->q = NULL;
+ clone->rq_disk = NULL;
r = DM_MAPIO_SUBMITTED;
- } else if (pgpath)
- bio->bi_bdev = pgpath->path.dev->bdev;
- else if (__must_push_back(m))
+ } else if (pgpath) {
+ clone->q = bdev_get_queue(pgpath->path.dev->bdev);
+ clone->rq_disk = pgpath->path.dev->bdev->bd_disk;
+ } else if (__must_push_back(m)) {
+ clone->q = NULL;
+ clone->rq_disk = NULL;
r = DM_MAPIO_REQUEUE;
- else
+ } else {
+ clone->q = NULL;
+ clone->rq_disk = NULL;
r = -EIO; /* Failed */
+ }
mpio->pgpath = pgpath;
@@ -373,30 +381,28 @@ static void dispatch_queued_ios(struct m
{
int r;
unsigned long flags;
- struct bio *bio = NULL, *next;
struct dm_mpath_io *mpio;
union map_info *info;
+ struct request *clone, *n;
+ LIST_HEAD(cl);
spin_lock_irqsave(&m->lock, flags);
- bio = bio_list_get(&m->queued_ios);
+ list_splice_init(&m->queued_ios, &cl);
spin_unlock_irqrestore(&m->lock, flags);
- while (bio) {
- next = bio->bi_next;
- bio->bi_next = NULL;
+ list_for_each_entry_safe(clone, n, &cl, queuelist) {
+ list_del(&clone->queuelist);
- info = dm_get_mapinfo(bio);
+ info = dm_get_rq_mapinfo(clone);
mpio = info->ptr;
- r = map_io(m, bio, mpio, 1);
+ r = map_io(m, clone, mpio, 1);
if (r < 0)
- bio_endio(bio, bio->bi_size, r);
+ blk_end_request(clone, r, blk_rq_size(clone));
else if (r == DM_MAPIO_REMAPPED)
- generic_make_request(bio);
+ dm_dispatch_request(clone->q, clone);
else if (r == DM_MAPIO_REQUEUE)
- bio_endio(bio, bio->bi_size, -EIO);
-
- bio = next;
+ blk_end_request(clone, -EIO, blk_rq_size(clone));
}
}
@@ -789,21 +795,26 @@ static void multipath_dtr(struct dm_targ
}
/*
- * Map bios, recording original fields for later in case we have to resubmit
+ * Map cloned requests
*/
-static int multipath_map(struct dm_target *ti, struct bio *bio,
+static int multipath_map(struct dm_target *ti, struct request *clone,
union map_info *map_context)
{
int r;
struct dm_mpath_io *mpio;
struct multipath *m = (struct multipath *) ti->private;
- mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
- dm_bio_record(&mpio->details, bio);
+ mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC);
+ if (!mpio)
+ /* ENOMEM, requeue */
+ return DM_MAPIO_REQUEUE;
+ memset(mpio, 0, sizeof(*mpio));
+ clone->cmd_flags |= REQ_FAILFAST;
+ dm_rq_record(&mpio->details, clone);
map_context->ptr = mpio;
- bio->bi_rw |= (1 << BIO_RW_FAILFAST);
- r = map_io(m, bio, mpio, 0);
+
+ r = map_io(m, clone, mpio, 0);
if (r < 0 || r == DM_MAPIO_REQUEUE)
mempool_free(mpio, m->mpio_pool);
@@ -1007,25 +1018,37 @@ void dm_pg_init_complete(struct dm_path
spin_unlock_irqrestore(&m->lock, flags);
}
+static void multipath_queue_in_tgt(struct dm_target *ti, struct request *clone,
+ union map_info *map_context)
+{
+ struct multipath *m = (struct multipath *) ti->private;
+ struct dm_mpath_io *mpio = (struct dm_mpath_io *) map_context->ptr;
+ unsigned long flags = 0UL;
+
+ dm_rq_restore(&mpio->details, clone);
+
+ /* queue for the daemon to resubmit or fail */
+ spin_lock_irqsave(&m->lock, flags);
+ list_add_tail(&clone->queuelist, &m->queued_ios);
+ m->queue_size++;
+ if (!m->queue_io)
+ queue_work(kmultipathd, &m->process_queued_ios);
+ spin_unlock_irqrestore(&m->lock, flags);
+}
+
/*
* end_io handling
*/
-static int do_end_io(struct multipath *m, struct bio *bio,
- int error, struct dm_mpath_io *mpio)
+static int do_end_io(struct multipath *m, struct request *clone, int error,
+ struct dm_mpath_io *mpio)
{
struct hw_handler *hwh = &m->hw_handler;
unsigned err_flags = MP_FAIL_PATH; /* Default behavior */
- unsigned long flags;
+ unsigned long flags = 0UL;
- if (!error)
+ if (!clone->errors && !error)
return 0; /* I/O complete */
- if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
- return error;
-
- if (error == -EOPNOTSUPP)
- return error;
-
spin_lock_irqsave(&m->lock, flags);
if (!m->nr_valid_paths) {
if (__must_push_back(m)) {
@@ -1041,8 +1064,8 @@ static int do_end_io(struct multipath *m
}
spin_unlock_irqrestore(&m->lock, flags);
- if (hwh->type && hwh->type->error)
- err_flags = hwh->type->error(hwh, bio);
+ if (hwh->type && hwh->type->error_rq)
+ err_flags = hwh->type->error_rq(hwh, clone);
if (mpio->pgpath) {
if (err_flags & MP_FAIL_PATH)
@@ -1056,21 +1079,14 @@ static int do_end_io(struct multipath *m
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);
- spin_unlock_irqrestore(&m->lock, flags);
-
return DM_ENDIO_INCOMPLETE; /* io not complete */
}
-static int multipath_end_io(struct dm_target *ti, struct bio *bio,
- int error, union map_info *map_context)
+/*
+ * clone->q's lock must be held
+ */
+static int multipath_end_io_first(struct dm_target *ti, struct request *clone,
+ int error, union map_info *map_context)
{
struct multipath *m = ti->private;
struct dm_mpath_io *mpio = map_context->ptr;
@@ -1078,18 +1094,28 @@ 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(m, clone, error, mpio);
if (pgpath) {
ps = &pgpath->pg->ps;
if (ps->type->end_io)
ps->type->end_io(ps, &pgpath->path);
}
- if (r != DM_ENDIO_INCOMPLETE)
- 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 dm_mpath_io *mpio = (struct dm_mpath_io *) map_context->ptr;
+
+ if (mpio)
+ mempool_free(mpio, m->mpio_pool);
+
+ return 0;
+}
+
/*
* Suspend can't complete until all the I/O is processed so if
* the last path fails we must error any remaining I/O.
@@ -1320,6 +1346,84 @@ static int multipath_ioctl(struct dm_tar
bdev->bd_disk, cmd, arg);
}
+static int __pgpath_congested(struct pgpath *pgpath)
+{
+ struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
+
+ if (dm_underlying_device_congested(q))
+ return 1;
+
+ return 0;
+}
+
+#if 0
+#define READY_PATH_EXIST 0
+#define ALL_PATH_CONGESTED 1
+#define NO_ACTIVE_PATH 2
+
+static int __pg_congested(struct priority_group *pg)
+{
+ int r = READY_PATH_EXIST, has_active = 0, has_ready = 0;
+ struct pgpath *pgpath;
+
+ list_for_each_entry(pgpath, &pg->list, list) {
+ if (pgpath->path.is_active) {
+ has_active = 1;
+
+ if (!__pgpath_congested(pgpath))
+ has_ready = 1;
+ }
+ }
+
+ if (!has_active)
+ r = NO_ACTIVE_PATH;
+ else if (!has_ready)
+ r = ALL_PATH_CONGESTED;
+
+ return r;
+}
+#endif
+
+static int multipath_congested(struct dm_target *ti)
+{
+ int r = 0;
+ struct multipath *m = (struct multipath *) ti->private;
+ unsigned long flags = 0UL;
+
+ spin_lock_irqsave(&m->lock, flags);
+
+ if (m->current_pgpath && m->repeat_count > 1) {
+ /* m->current_pgpath is surely used at next mapping time. */
+ if (__pgpath_congested(m->current_pgpath)) {
+ r = 1;
+ }
+ goto out;
+ }
+
+ /*
+ * We are here means that path selection is executed
+ * at next mapping time.
+ * We run the path selection here and check congestion status
+ * of the next path.
+ * And increment repeat_count to avoid path selection again
+ * in map_io(). (This is a hack for pre-decrementing repeat_count
+ * in map_io(). Needs to be fixed this repeat_count bug.)
+ */
+ __choose_pgpath(m);
+ if (m->current_pgpath) {
+ if (__pgpath_congested(m->current_pgpath)) {
+ r = 1;
+ }
+
+ m->repeat_count++;
+ }
+
+out:
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ return r;
+}
+
/*-----------------------------------------------------------------
* Module setup
*---------------------------------------------------------------*/
@@ -1329,13 +1433,16 @@ static struct target_type multipath_targ
.module = THIS_MODULE,
.ctr = multipath_ctr,
.dtr = multipath_dtr,
- .map = multipath_map,
- .end_io = multipath_end_io,
+ .map_rq = multipath_map,
+ .rq_end_io_first = multipath_end_io_first,
+ .rq_end_io = multipath_end_io,
+ .queue_in_tgt = multipath_queue_in_tgt,
.presuspend = multipath_presuspend,
.resume = multipath_resume,
.status = multipath_status,
.message = multipath_message,
.ioctl = multipath_ioctl,
+ .congested = multipath_congested,
};
static int __init dm_multipath_init(void)
diff -rupN a1-rqdm-core/drivers/md/dm-rq-record.h a2-rqdm-mpath/drivers/md/dm-rq-record.h
--- a1-rqdm-core/drivers/md/dm-rq-record.h 1969-12-31 19:00:00.000000000 -0500
+++ a2-rqdm-mpath/drivers/md/dm-rq-record.h 2007-08-28 16:08:35.000000000 -0400
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2007 NEC Corporation.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef DM_RQ_RECORD_H
+#define DM_RQ_RECORD_H
+
+#include <linux/blkdev.h>
+
+/*
+ * There are lots of mutable fields in the request struct that get
+ * changed by the lower levels of the block layer. Some targets,
+ * such as multipath, may wish to resubmit a request on error. The
+ * functions in this file help the target record and restore the
+ * original request state.
+ */
+struct dm_rq_details {
+ unsigned int cmd_flags;
+ int ref_count;
+};
+
+static inline void dm_rq_record(struct dm_rq_details *rd, struct request *rq)
+{
+ rd->cmd_flags = rq->cmd_flags;
+ rd->ref_count = rq->ref_count;
+}
+
+static inline void dm_rq_restore(struct dm_rq_details *rd, struct request *rq)
+{
+ rq->cmd_flags = rd->cmd_flags;
+ rq->ref_count = rd->ref_count;
+}
+
+#endif