From 166e1f901b01872e8b70733a3f2e2c6980389cf8 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@infradead.org>
Date: Mon, 12 Sep 2011 12:08:27 +0200
Subject: block: export __make_request

Avoid the hacks need for request based device mappers currently by simply
exporting the symbol instead of trying to get it through the back door.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
---
 include/linux/blkdev.h | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'include/linux/blkdev.h')

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0e67c45b3bc..e9c3d9b0763 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -675,6 +675,8 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 			 struct scsi_ioctl_command __user *);
 
+extern int __make_request(struct request_queue *q, struct bio *bio);
+
 /*
  * A queue has just exitted congestion.  Note this in the global counter of
  * congested queues, and wake up anyone who was waiting for requests to be
-- 
cgit v1.2.3-70-g09d2


From c20e8de27fef9f59869c81c288ad6cf28200e00c Mon Sep 17 00:00:00 2001
From: Jens Axboe <jaxboe@fusionio.com>
Date: Mon, 12 Sep 2011 12:03:37 +0200
Subject: block: rename __make_request() to blk_queue_bio()

Now that it's exported, lets put it in a more sane namespace.

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
---
 block/blk-core.c       | 6 +++---
 drivers/md/dm.c        | 2 +-
 include/linux/blkdev.h | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

(limited to 'include/linux/blkdev.h')

diff --git a/block/blk-core.c b/block/blk-core.c
index 56ef387e7d2..ab673f0b8c3 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -540,7 +540,7 @@ blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn,
 	/*
 	 * This also sets hw/phys segments, boundary and size
 	 */
-	blk_queue_make_request(q, __make_request);
+	blk_queue_make_request(q, blk_queue_bio);
 
 	q->sg_reserved_size = INT_MAX;
 
@@ -1211,7 +1211,7 @@ void init_request_from_bio(struct request *req, struct bio *bio)
 	blk_rq_bio_prep(req->q, req, bio);
 }
 
-int __make_request(struct request_queue *q, struct bio *bio)
+int blk_queue_bio(struct request_queue *q, struct bio *bio)
 {
 	const bool sync = !!(bio->bi_rw & REQ_SYNC);
 	struct blk_plug *plug;
@@ -1315,7 +1315,7 @@ out_unlock:
 out:
 	return 0;
 }
-EXPORT_SYMBOL_GPL(__make_request);	/* for device mapper only */
+EXPORT_SYMBOL_GPL(blk_queue_bio);	/* for device mapper only */
 
 /*
  * If bio->bi_dev is a partition, remap the location
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index d8d7b8d9dd2..78b20868bcb 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1427,7 +1427,7 @@ static int dm_request(struct request_queue *q, struct bio *bio)
 	struct mapped_device *md = q->queuedata;
 
 	if (dm_request_based(md))
-		return __make_request(q, bio);
+		return blk_queue_bio(q, bio);
 
 	return _dm_request(q, bio);
 }
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e9c3d9b0763..085f95414c7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -675,7 +675,7 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 			 struct scsi_ioctl_command __user *);
 
-extern int __make_request(struct request_queue *q, struct bio *bio);
+extern int blk_queue_bio(struct request_queue *q, struct bio *bio);
 
 /*
  * A queue has just exitted congestion.  Note this in the global counter of
-- 
cgit v1.2.3-70-g09d2


From 5a7bbad27a410350e64a2d7f5ec18fc73836c14f Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@infradead.org>
Date: Mon, 12 Sep 2011 12:12:01 +0200
Subject: block: remove support for bio remapping from ->make_request

There is very little benefit in allowing to let a ->make_request
instance update the bios device and sector and loop around it in
__generic_make_request when we can archive the same through calling
generic_make_request from the driver and letting the loop in
generic_make_request handle it.

Note that various drivers got the return value from ->make_request and
returned non-zero values for errors.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
---
 arch/m68k/emu/nfblock.c         |   3 +-
 arch/powerpc/sysdev/axonram.c   |   8 +--
 block/blk-core.c                | 153 ++++++++++++++++------------------------
 drivers/block/aoe/aoeblk.c      |  14 ++--
 drivers/block/brd.c             |   4 +-
 drivers/block/drbd/drbd_int.h   |   2 +-
 drivers/block/drbd/drbd_req.c   |   8 +--
 drivers/block/loop.c            |   5 +-
 drivers/block/pktcdvd.c         |  11 ++-
 drivers/block/ps3vram.c         |   6 +-
 drivers/block/umem.c            |   4 +-
 drivers/md/dm.c                 |  14 ++--
 drivers/md/faulty.c             |  14 ++--
 drivers/md/linear.c             |  17 ++---
 drivers/md/md.c                 |  12 ++--
 drivers/md/md.h                 |   2 +-
 drivers/md/multipath.c          |   8 +--
 drivers/md/raid0.c              |  22 +++---
 drivers/md/raid1.c              |   8 +--
 drivers/md/raid10.c             |  19 +++--
 drivers/md/raid5.c              |   8 +--
 drivers/s390/block/dcssblk.c    |   7 +-
 drivers/s390/block/xpram.c      |   5 +-
 drivers/staging/zram/zram_drv.c |   8 +--
 include/linux/blkdev.h          |   4 +-
 25 files changed, 151 insertions(+), 215 deletions(-)

(limited to 'include/linux/blkdev.h')

diff --git a/arch/m68k/emu/nfblock.c b/arch/m68k/emu/nfblock.c
index 48e50f8c1c7..e3011338ab4 100644
--- a/arch/m68k/emu/nfblock.c
+++ b/arch/m68k/emu/nfblock.c
@@ -59,7 +59,7 @@ struct nfhd_device {
 	struct gendisk *disk;
 };
 
-static int nfhd_make_request(struct request_queue *queue, struct bio *bio)
+static void nfhd_make_request(struct request_queue *queue, struct bio *bio)
 {
 	struct nfhd_device *dev = queue->queuedata;
 	struct bio_vec *bvec;
@@ -76,7 +76,6 @@ static int nfhd_make_request(struct request_queue *queue, struct bio *bio)
 		sec += len;
 	}
 	bio_endio(bio, 0);
-	return 0;
 }
 
 static int nfhd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
index 265f0f09395..ba427191906 100644
--- a/arch/powerpc/sysdev/axonram.c
+++ b/arch/powerpc/sysdev/axonram.c
@@ -104,7 +104,7 @@ axon_ram_irq_handler(int irq, void *dev)
  * axon_ram_make_request - make_request() method for block device
  * @queue, @bio: see blk_queue_make_request()
  */
-static int
+static void
 axon_ram_make_request(struct request_queue *queue, struct bio *bio)
 {
 	struct axon_ram_bank *bank = bio->bi_bdev->bd_disk->private_data;
@@ -113,7 +113,6 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
 	struct bio_vec *vec;
 	unsigned int transfered;
 	unsigned short idx;
-	int rc = 0;
 
 	phys_mem = bank->io_addr + (bio->bi_sector << AXON_RAM_SECTOR_SHIFT);
 	phys_end = bank->io_addr + bank->size;
@@ -121,8 +120,7 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
 	bio_for_each_segment(vec, bio, idx) {
 		if (unlikely(phys_mem + vec->bv_len > phys_end)) {
 			bio_io_error(bio);
-			rc = -ERANGE;
-			break;
+			return;
 		}
 
 		user_mem = page_address(vec->bv_page) + vec->bv_offset;
@@ -135,8 +133,6 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
 		transfered += vec->bv_len;
 	}
 	bio_endio(bio, 0);
-
-	return rc;
 }
 
 /**
diff --git a/block/blk-core.c b/block/blk-core.c
index ab673f0b8c3..f58e019be67 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1211,7 +1211,7 @@ void init_request_from_bio(struct request *req, struct bio *bio)
 	blk_rq_bio_prep(req->q, req, bio);
 }
 
-int blk_queue_bio(struct request_queue *q, struct bio *bio)
+void blk_queue_bio(struct request_queue *q, struct bio *bio)
 {
 	const bool sync = !!(bio->bi_rw & REQ_SYNC);
 	struct blk_plug *plug;
@@ -1236,7 +1236,7 @@ int blk_queue_bio(struct request_queue *q, struct bio *bio)
 	 * any locks.
 	 */
 	if (attempt_plug_merge(current, q, bio))
-		goto out;
+		return;
 
 	spin_lock_irq(q->queue_lock);
 
@@ -1312,8 +1312,6 @@ get_rq:
 out_unlock:
 		spin_unlock_irq(q->queue_lock);
 	}
-out:
-	return 0;
 }
 EXPORT_SYMBOL_GPL(blk_queue_bio);	/* for device mapper only */
 
@@ -1441,112 +1439,85 @@ static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
 static inline void __generic_make_request(struct bio *bio)
 {
 	struct request_queue *q;
-	sector_t old_sector;
-	int ret, nr_sectors = bio_sectors(bio);
-	dev_t old_dev;
+	int nr_sectors = bio_sectors(bio);
 	int err = -EIO;
+	char b[BDEVNAME_SIZE];
+	struct hd_struct *part;
 
 	might_sleep();
 
 	if (bio_check_eod(bio, nr_sectors))
 		goto end_io;
 
-	/*
-	 * Resolve the mapping until finished. (drivers are
-	 * still free to implement/resolve their own stacking
-	 * by explicitly returning 0)
-	 *
-	 * NOTE: we don't repeat the blk_size check for each new device.
-	 * Stacking drivers are expected to know what they are doing.
-	 */
-	old_sector = -1;
-	old_dev = 0;
-	do {
-		char b[BDEVNAME_SIZE];
-		struct hd_struct *part;
-
-		q = bdev_get_queue(bio->bi_bdev);
-		if (unlikely(!q)) {
-			printk(KERN_ERR
-			       "generic_make_request: Trying to access "
-				"nonexistent block-device %s (%Lu)\n",
-				bdevname(bio->bi_bdev, b),
-				(long long) bio->bi_sector);
-			goto end_io;
-		}
-
-		if (unlikely(!(bio->bi_rw & REQ_DISCARD) &&
-			     nr_sectors > queue_max_hw_sectors(q))) {
-			printk(KERN_ERR "bio too big device %s (%u > %u)\n",
-			       bdevname(bio->bi_bdev, b),
-			       bio_sectors(bio),
-			       queue_max_hw_sectors(q));
-			goto end_io;
-		}
-
-		if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
-			goto end_io;
-
-		part = bio->bi_bdev->bd_part;
-		if (should_fail_request(part, bio->bi_size) ||
-		    should_fail_request(&part_to_disk(part)->part0,
-					bio->bi_size))
-			goto end_io;
+	q = bdev_get_queue(bio->bi_bdev);
+	if (unlikely(!q)) {
+		printk(KERN_ERR
+		       "generic_make_request: Trying to access "
+			"nonexistent block-device %s (%Lu)\n",
+			bdevname(bio->bi_bdev, b),
+			(long long) bio->bi_sector);
+		goto end_io;
+	}
 
-		/*
-		 * If this device has partitions, remap block n
-		 * of partition p to block n+start(p) of the disk.
-		 */
-		blk_partition_remap(bio);
+	if (unlikely(!(bio->bi_rw & REQ_DISCARD) &&
+		     nr_sectors > queue_max_hw_sectors(q))) {
+		printk(KERN_ERR "bio too big device %s (%u > %u)\n",
+		       bdevname(bio->bi_bdev, b),
+		       bio_sectors(bio),
+		       queue_max_hw_sectors(q));
+		goto end_io;
+	}
 
-		if (bio_integrity_enabled(bio) && bio_integrity_prep(bio))
-			goto end_io;
+	if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
+		goto end_io;
 
-		if (old_sector != -1)
-			trace_block_bio_remap(q, bio, old_dev, old_sector);
+	part = bio->bi_bdev->bd_part;
+	if (should_fail_request(part, bio->bi_size) ||
+	    should_fail_request(&part_to_disk(part)->part0,
+				bio->bi_size))
+		goto end_io;
 
-		old_sector = bio->bi_sector;
-		old_dev = bio->bi_bdev->bd_dev;
+	/*
+	 * If this device has partitions, remap block n
+	 * of partition p to block n+start(p) of the disk.
+	 */
+	blk_partition_remap(bio);
 
-		if (bio_check_eod(bio, nr_sectors))
-			goto end_io;
+	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio))
+		goto end_io;
 
-		/*
-		 * Filter flush bio's early so that make_request based
-		 * drivers without flush support don't have to worry
-		 * about them.
-		 */
-		if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
-			bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
-			if (!nr_sectors) {
-				err = 0;
-				goto end_io;
-			}
-		}
+	if (bio_check_eod(bio, nr_sectors))
+		goto end_io;
 
-		if ((bio->bi_rw & REQ_DISCARD) &&
-		    (!blk_queue_discard(q) ||
-		     ((bio->bi_rw & REQ_SECURE) &&
-		      !blk_queue_secdiscard(q)))) {
-			err = -EOPNOTSUPP;
+	/*
+	 * Filter flush bio's early so that make_request based
+	 * drivers without flush support don't have to worry
+	 * about them.
+	 */
+	if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
+		bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
+		if (!nr_sectors) {
+			err = 0;
 			goto end_io;
 		}
+	}
 
-		if (blk_throtl_bio(q, &bio))
-			goto end_io;
-
-		/*
-		 * If bio = NULL, bio has been throttled and will be submitted
-		 * later.
-		 */
-		if (!bio)
-			break;
-
-		trace_block_bio_queue(q, bio);
+	if ((bio->bi_rw & REQ_DISCARD) &&
+	    (!blk_queue_discard(q) ||
+	     ((bio->bi_rw & REQ_SECURE) &&
+	      !blk_queue_secdiscard(q)))) {
+		err = -EOPNOTSUPP;
+		goto end_io;
+	}
 
-		ret = q->make_request_fn(q, bio);
-	} while (ret);
+	if (blk_throtl_bio(q, &bio))
+		goto end_io;
 
+	/* if bio = NULL, bio has been throttled and will be submitted later. */
+	if (!bio)
+		return;
+	trace_block_bio_queue(q, bio);
+	q->make_request_fn(q, bio);
 	return;
 
 end_io:
diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index 528f6318ded..167ba0af47f 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -159,7 +159,7 @@ aoeblk_release(struct gendisk *disk, fmode_t mode)
 	return 0;
 }
 
-static int
+static void
 aoeblk_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct sk_buff_head queue;
@@ -172,25 +172,25 @@ aoeblk_make_request(struct request_queue *q, struct bio *bio)
 	if (bio == NULL) {
 		printk(KERN_ERR "aoe: bio is NULL\n");
 		BUG();
-		return 0;
+		return;
 	}
 	d = bio->bi_bdev->bd_disk->private_data;
 	if (d == NULL) {
 		printk(KERN_ERR "aoe: bd_disk->private_data is NULL\n");
 		BUG();
 		bio_endio(bio, -ENXIO);
-		return 0;
+		return;
 	} else if (bio->bi_io_vec == NULL) {
 		printk(KERN_ERR "aoe: bi_io_vec is NULL\n");
 		BUG();
 		bio_endio(bio, -ENXIO);
-		return 0;
+		return;
 	}
 	buf = mempool_alloc(d->bufpool, GFP_NOIO);
 	if (buf == NULL) {
 		printk(KERN_INFO "aoe: buf allocation failure\n");
 		bio_endio(bio, -ENOMEM);
-		return 0;
+		return;
 	}
 	memset(buf, 0, sizeof(*buf));
 	INIT_LIST_HEAD(&buf->bufs);
@@ -211,7 +211,7 @@ aoeblk_make_request(struct request_queue *q, struct bio *bio)
 		spin_unlock_irqrestore(&d->lock, flags);
 		mempool_free(buf, d->bufpool);
 		bio_endio(bio, -ENXIO);
-		return 0;
+		return;
 	}
 
 	list_add_tail(&buf->bufs, &d->bufq);
@@ -222,8 +222,6 @@ aoeblk_make_request(struct request_queue *q, struct bio *bio)
 
 	spin_unlock_irqrestore(&d->lock, flags);
 	aoenet_xmit(&queue);
-
-	return 0;
 }
 
 static int
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index dba1c32e1dd..d22119d49e5 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -323,7 +323,7 @@ out:
 	return err;
 }
 
-static int brd_make_request(struct request_queue *q, struct bio *bio)
+static void brd_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct block_device *bdev = bio->bi_bdev;
 	struct brd_device *brd = bdev->bd_disk->private_data;
@@ -359,8 +359,6 @@ static int brd_make_request(struct request_queue *q, struct bio *bio)
 
 out:
 	bio_endio(bio, err);
-
-	return 0;
 }
 
 #ifdef CONFIG_BLK_DEV_XIP
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index ef2ceed3be4..36eee3969a9 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1507,7 +1507,7 @@ extern void drbd_free_mdev(struct drbd_conf *mdev);
 extern int proc_details;
 
 /* drbd_req */
-extern int drbd_make_request(struct request_queue *q, struct bio *bio);
+extern void drbd_make_request(struct request_queue *q, struct bio *bio);
 extern int drbd_read_remote(struct drbd_conf *mdev, struct drbd_request *req);
 extern int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec);
 extern int is_valid_ar_handle(struct drbd_request *, sector_t);
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 3424d675b76..4a0f314086e 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1073,7 +1073,7 @@ static int drbd_fail_request_early(struct drbd_conf *mdev, int is_write)
 	return 0;
 }
 
-int drbd_make_request(struct request_queue *q, struct bio *bio)
+void drbd_make_request(struct request_queue *q, struct bio *bio)
 {
 	unsigned int s_enr, e_enr;
 	struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata;
@@ -1081,7 +1081,7 @@ int drbd_make_request(struct request_queue *q, struct bio *bio)
 
 	if (drbd_fail_request_early(mdev, bio_data_dir(bio) & WRITE)) {
 		bio_endio(bio, -EPERM);
-		return 0;
+		return;
 	}
 
 	start_time = jiffies;
@@ -1100,7 +1100,8 @@ int drbd_make_request(struct request_queue *q, struct bio *bio)
 
 	if (likely(s_enr == e_enr)) {
 		inc_ap_bio(mdev, 1);
-		return drbd_make_request_common(mdev, bio, start_time);
+		drbd_make_request_common(mdev, bio, start_time);
+		return;
 	}
 
 	/* can this bio be split generically?
@@ -1148,7 +1149,6 @@ int drbd_make_request(struct request_queue *q, struct bio *bio)
 
 		bio_pair_release(bp);
 	}
-	return 0;
 }
 
 /* This is called by bio_add_page().  With this function we reduce
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 76c8da78212..8360239d553 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -514,7 +514,7 @@ static struct bio *loop_get_bio(struct loop_device *lo)
 	return bio_list_pop(&lo->lo_bio_list);
 }
 
-static int loop_make_request(struct request_queue *q, struct bio *old_bio)
+static void loop_make_request(struct request_queue *q, struct bio *old_bio)
 {
 	struct loop_device *lo = q->queuedata;
 	int rw = bio_rw(old_bio);
@@ -532,12 +532,11 @@ static int loop_make_request(struct request_queue *q, struct bio *old_bio)
 	loop_add_bio(lo, old_bio);
 	wake_up(&lo->lo_event);
 	spin_unlock_irq(&lo->lo_lock);
-	return 0;
+	return;
 
 out:
 	spin_unlock_irq(&lo->lo_lock);
 	bio_io_error(old_bio);
-	return 0;
 }
 
 struct switch_request {
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index e133f094ab0..a63b0a2b780 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2444,7 +2444,7 @@ static void pkt_end_io_read_cloned(struct bio *bio, int err)
 	pkt_bio_finished(pd);
 }
 
-static int pkt_make_request(struct request_queue *q, struct bio *bio)
+static void pkt_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct pktcdvd_device *pd;
 	char b[BDEVNAME_SIZE];
@@ -2473,7 +2473,7 @@ static int pkt_make_request(struct request_queue *q, struct bio *bio)
 		cloned_bio->bi_end_io = pkt_end_io_read_cloned;
 		pd->stats.secs_r += bio->bi_size >> 9;
 		pkt_queue_bio(pd, cloned_bio);
-		return 0;
+		return;
 	}
 
 	if (!test_bit(PACKET_WRITABLE, &pd->flags)) {
@@ -2509,7 +2509,7 @@ static int pkt_make_request(struct request_queue *q, struct bio *bio)
 			pkt_make_request(q, &bp->bio1);
 			pkt_make_request(q, &bp->bio2);
 			bio_pair_release(bp);
-			return 0;
+			return;
 		}
 	}
 
@@ -2533,7 +2533,7 @@ static int pkt_make_request(struct request_queue *q, struct bio *bio)
 				}
 				spin_unlock(&pkt->lock);
 				spin_unlock(&pd->cdrw.active_list_lock);
-				return 0;
+				return;
 			} else {
 				blocked_bio = 1;
 			}
@@ -2584,10 +2584,9 @@ static int pkt_make_request(struct request_queue *q, struct bio *bio)
 		 */
 		wake_up(&pd->wqueue);
 	}
-	return 0;
+	return;
 end_io:
 	bio_io_error(bio);
-	return 0;
 }
 
 
diff --git a/drivers/block/ps3vram.c b/drivers/block/ps3vram.c
index b3bdb8af89c..7fad7af87eb 100644
--- a/drivers/block/ps3vram.c
+++ b/drivers/block/ps3vram.c
@@ -596,7 +596,7 @@ out:
 	return next;
 }
 
-static int ps3vram_make_request(struct request_queue *q, struct bio *bio)
+static void ps3vram_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct ps3_system_bus_device *dev = q->queuedata;
 	struct ps3vram_priv *priv = ps3_system_bus_get_drvdata(dev);
@@ -610,13 +610,11 @@ static int ps3vram_make_request(struct request_queue *q, struct bio *bio)
 	spin_unlock_irq(&priv->lock);
 
 	if (busy)
-		return 0;
+		return;
 
 	do {
 		bio = ps3vram_do_bio(dev, bio);
 	} while (bio);
-
-	return 0;
 }
 
 static int __devinit ps3vram_probe(struct ps3_system_bus_device *dev)
diff --git a/drivers/block/umem.c b/drivers/block/umem.c
index 031ca720d92..aa2712060bf 100644
--- a/drivers/block/umem.c
+++ b/drivers/block/umem.c
@@ -513,7 +513,7 @@ static void process_page(unsigned long data)
 	}
 }
 
-static int mm_make_request(struct request_queue *q, struct bio *bio)
+static void mm_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct cardinfo *card = q->queuedata;
 	pr_debug("mm_make_request %llu %u\n",
@@ -525,7 +525,7 @@ static int mm_make_request(struct request_queue *q, struct bio *bio)
 	card->biotail = &bio->bi_next;
 	spin_unlock_irq(&card->lock);
 
-	return 0;
+	return;
 }
 
 static irqreturn_t mm_interrupt(int irq, void *__card)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 78b20868bcb..7b986e77b75 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1388,7 +1388,7 @@ out:
  * The request function that just remaps the bio built up by
  * dm_merge_bvec.
  */
-static int _dm_request(struct request_queue *q, struct bio *bio)
+static void _dm_request(struct request_queue *q, struct bio *bio)
 {
 	int rw = bio_data_dir(bio);
 	struct mapped_device *md = q->queuedata;
@@ -1409,12 +1409,12 @@ static int _dm_request(struct request_queue *q, struct bio *bio)
 			queue_io(md, bio);
 		else
 			bio_io_error(bio);
-		return 0;
+		return;
 	}
 
 	__split_and_process_bio(md, bio);
 	up_read(&md->io_lock);
-	return 0;
+	return;
 }
 
 static int dm_request_based(struct mapped_device *md)
@@ -1422,14 +1422,14 @@ static int dm_request_based(struct mapped_device *md)
 	return blk_queue_stackable(md->queue);
 }
 
-static int dm_request(struct request_queue *q, struct bio *bio)
+static void dm_request(struct request_queue *q, struct bio *bio)
 {
 	struct mapped_device *md = q->queuedata;
 
 	if (dm_request_based(md))
-		return blk_queue_bio(q, bio);
-
-	return _dm_request(q, bio);
+		blk_queue_bio(q, bio);
+	else
+		_dm_request(q, bio);
 }
 
 void dm_dispatch_request(struct request *rq)
diff --git a/drivers/md/faulty.c b/drivers/md/faulty.c
index 23078dabb6d..5ef304d4341 100644
--- a/drivers/md/faulty.c
+++ b/drivers/md/faulty.c
@@ -169,7 +169,7 @@ static void add_sector(conf_t *conf, sector_t start, int mode)
 		conf->nfaults = n+1;
 }
 
-static int make_request(mddev_t *mddev, struct bio *bio)
+static void make_request(mddev_t *mddev, struct bio *bio)
 {
 	conf_t *conf = mddev->private;
 	int failit = 0;
@@ -181,7 +181,7 @@ static int make_request(mddev_t *mddev, struct bio *bio)
 			 * just fail immediately
 			 */
 			bio_endio(bio, -EIO);
-			return 0;
+			return;
 		}
 
 		if (check_sector(conf, bio->bi_sector, bio->bi_sector+(bio->bi_size>>9),
@@ -211,15 +211,15 @@ static int make_request(mddev_t *mddev, struct bio *bio)
 	}
 	if (failit) {
 		struct bio *b = bio_clone_mddev(bio, GFP_NOIO, mddev);
+
 		b->bi_bdev = conf->rdev->bdev;
 		b->bi_private = bio;
 		b->bi_end_io = faulty_fail;
-		generic_make_request(b);
-		return 0;
-	} else {
+		bio = b;
+	} else
 		bio->bi_bdev = conf->rdev->bdev;
-		return 1;
-	}
+
+	generic_make_request(bio);
 }
 
 static void status(struct seq_file *seq, mddev_t *mddev)
diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 6cd2c313e80..c6ee491d98e 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -264,14 +264,14 @@ static int linear_stop (mddev_t *mddev)
 	return 0;
 }
 
-static int linear_make_request (mddev_t *mddev, struct bio *bio)
+static void linear_make_request (mddev_t *mddev, struct bio *bio)
 {
 	dev_info_t *tmp_dev;
 	sector_t start_sector;
 
 	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 		md_flush_request(mddev, bio);
-		return 0;
+		return;
 	}
 
 	rcu_read_lock();
@@ -293,7 +293,7 @@ static int linear_make_request (mddev_t *mddev, struct bio *bio)
 		       (unsigned long long)start_sector);
 		rcu_read_unlock();
 		bio_io_error(bio);
-		return 0;
+		return;
 	}
 	if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
 		     tmp_dev->end_sector)) {
@@ -307,20 +307,17 @@ static int linear_make_request (mddev_t *mddev, struct bio *bio)
 
 		bp = bio_split(bio, end_sector - bio->bi_sector);
 
-		if (linear_make_request(mddev, &bp->bio1))
-			generic_make_request(&bp->bio1);
-		if (linear_make_request(mddev, &bp->bio2))
-			generic_make_request(&bp->bio2);
+		linear_make_request(mddev, &bp->bio1);
+		linear_make_request(mddev, &bp->bio2);
 		bio_pair_release(bp);
-		return 0;
+		return;
 	}
 		    
 	bio->bi_bdev = tmp_dev->rdev->bdev;
 	bio->bi_sector = bio->bi_sector - start_sector
 		+ tmp_dev->rdev->data_offset;
 	rcu_read_unlock();
-
-	return 1;
+	generic_make_request(bio);
 }
 
 static void linear_status (struct seq_file *seq, mddev_t *mddev)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 8e221a20f5d..5c2178562c9 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -330,18 +330,17 @@ static DEFINE_SPINLOCK(all_mddevs_lock);
  * call has finished, the bio has been linked into some internal structure
  * and so is visible to ->quiesce(), so we don't need the refcount any more.
  */
-static int md_make_request(struct request_queue *q, struct bio *bio)
+static void md_make_request(struct request_queue *q, struct bio *bio)
 {
 	const int rw = bio_data_dir(bio);
 	mddev_t *mddev = q->queuedata;
-	int rv;
 	int cpu;
 	unsigned int sectors;
 
 	if (mddev == NULL || mddev->pers == NULL
 	    || !mddev->ready) {
 		bio_io_error(bio);
-		return 0;
+		return;
 	}
 	smp_rmb(); /* Ensure implications of  'active' are visible */
 	rcu_read_lock();
@@ -366,7 +365,7 @@ static int md_make_request(struct request_queue *q, struct bio *bio)
 	 * go away inside make_request
 	 */
 	sectors = bio_sectors(bio);
-	rv = mddev->pers->make_request(mddev, bio);
+	mddev->pers->make_request(mddev, bio);
 
 	cpu = part_stat_lock();
 	part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
@@ -375,8 +374,6 @@ static int md_make_request(struct request_queue *q, struct bio *bio)
 
 	if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
 		wake_up(&mddev->sb_wait);
-
-	return rv;
 }
 
 /* mddev_suspend makes sure no new requests are submitted
@@ -475,8 +472,7 @@ static void md_submit_flush_data(struct work_struct *ws)
 		bio_endio(bio, 0);
 	else {
 		bio->bi_rw &= ~REQ_FLUSH;
-		if (mddev->pers->make_request(mddev, bio))
-			generic_make_request(bio);
+		mddev->pers->make_request(mddev, bio);
 	}
 
 	mddev->flush_bio = NULL;
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 1e586bb4452..bd47847cf7c 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -424,7 +424,7 @@ struct mdk_personality
 	int level;
 	struct list_head list;
 	struct module *owner;
-	int (*make_request)(mddev_t *mddev, struct bio *bio);
+	void (*make_request)(mddev_t *mddev, struct bio *bio);
 	int (*run)(mddev_t *mddev);
 	int (*stop)(mddev_t *mddev);
 	void (*status)(struct seq_file *seq, mddev_t *mddev);
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index 3535c23af28..407cb569142 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -106,7 +106,7 @@ static void multipath_end_request(struct bio *bio, int error)
 	rdev_dec_pending(rdev, conf->mddev);
 }
 
-static int multipath_make_request(mddev_t *mddev, struct bio * bio)
+static void multipath_make_request(mddev_t *mddev, struct bio * bio)
 {
 	multipath_conf_t *conf = mddev->private;
 	struct multipath_bh * mp_bh;
@@ -114,7 +114,7 @@ static int multipath_make_request(mddev_t *mddev, struct bio * bio)
 
 	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 		md_flush_request(mddev, bio);
-		return 0;
+		return;
 	}
 
 	mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
@@ -126,7 +126,7 @@ static int multipath_make_request(mddev_t *mddev, struct bio * bio)
 	if (mp_bh->path < 0) {
 		bio_endio(bio, -EIO);
 		mempool_free(mp_bh, conf->pool);
-		return 0;
+		return;
 	}
 	multipath = conf->multipaths + mp_bh->path;
 
@@ -137,7 +137,7 @@ static int multipath_make_request(mddev_t *mddev, struct bio * bio)
 	mp_bh->bio.bi_end_io = multipath_end_request;
 	mp_bh->bio.bi_private = mp_bh;
 	generic_make_request(&mp_bh->bio);
-	return 0;
+	return;
 }
 
 static void multipath_status (struct seq_file *seq, mddev_t *mddev)
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index e86bf3682e1..4066615d61a 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -466,7 +466,7 @@ static inline int is_io_in_chunk_boundary(mddev_t *mddev,
 	}
 }
 
-static int raid0_make_request(mddev_t *mddev, struct bio *bio)
+static void raid0_make_request(mddev_t *mddev, struct bio *bio)
 {
 	unsigned int chunk_sects;
 	sector_t sector_offset;
@@ -475,7 +475,7 @@ static int raid0_make_request(mddev_t *mddev, struct bio *bio)
 
 	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 		md_flush_request(mddev, bio);
-		return 0;
+		return;
 	}
 
 	chunk_sects = mddev->chunk_sectors;
@@ -495,13 +495,10 @@ static int raid0_make_request(mddev_t *mddev, struct bio *bio)
 		else
 			bp = bio_split(bio, chunk_sects -
 				       sector_div(sector, chunk_sects));
-		if (raid0_make_request(mddev, &bp->bio1))
-			generic_make_request(&bp->bio1);
-		if (raid0_make_request(mddev, &bp->bio2))
-			generic_make_request(&bp->bio2);
-
+		raid0_make_request(mddev, &bp->bio1);
+		raid0_make_request(mddev, &bp->bio2);
 		bio_pair_release(bp);
-		return 0;
+		return;
 	}
 
 	sector_offset = bio->bi_sector;
@@ -511,10 +508,9 @@ static int raid0_make_request(mddev_t *mddev, struct bio *bio)
 	bio->bi_bdev = tmp_dev->bdev;
 	bio->bi_sector = sector_offset + zone->dev_start +
 		tmp_dev->data_offset;
-	/*
-	 * Let the main block layer submit the IO and resolve recursion:
-	 */
-	return 1;
+
+	generic_make_request(bio);
+	return;
 
 bad_map:
 	printk("md/raid0:%s: make_request bug: can't convert block across chunks"
@@ -523,7 +519,7 @@ bad_map:
 	       (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
 
 	bio_io_error(bio);
-	return 0;
+	return;
 }
 
 static void raid0_status(struct seq_file *seq, mddev_t *mddev)
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 32323f0afd8..97f2a5f977b 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -785,7 +785,7 @@ do_sync_io:
 	PRINTK("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
 }
 
-static int make_request(mddev_t *mddev, struct bio * bio)
+static void make_request(mddev_t *mddev, struct bio * bio)
 {
 	conf_t *conf = mddev->private;
 	mirror_info_t *mirror;
@@ -870,7 +870,7 @@ read_again:
 		if (rdisk < 0) {
 			/* couldn't find anywhere to read from */
 			raid_end_bio_io(r1_bio);
-			return 0;
+			return;
 		}
 		mirror = conf->mirrors + rdisk;
 
@@ -928,7 +928,7 @@ read_again:
 			goto read_again;
 		} else
 			generic_make_request(read_bio);
-		return 0;
+		return;
 	}
 
 	/*
@@ -1119,8 +1119,6 @@ read_again:
 
 	if (do_sync || !bitmap || !plugged)
 		md_wakeup_thread(mddev->thread);
-
-	return 0;
 }
 
 static void status(struct seq_file *seq, mddev_t *mddev)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 8b29cd4f01c..04b625e1cb6 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -825,7 +825,7 @@ static void unfreeze_array(conf_t *conf)
 	spin_unlock_irq(&conf->resync_lock);
 }
 
-static int make_request(mddev_t *mddev, struct bio * bio)
+static void make_request(mddev_t *mddev, struct bio * bio)
 {
 	conf_t *conf = mddev->private;
 	mirror_info_t *mirror;
@@ -844,7 +844,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 
 	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 		md_flush_request(mddev, bio);
-		return 0;
+		return;
 	}
 
 	/* If this request crosses a chunk boundary, we need to
@@ -876,10 +876,8 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 		conf->nr_waiting++;
 		spin_unlock_irq(&conf->resync_lock);
 
-		if (make_request(mddev, &bp->bio1))
-			generic_make_request(&bp->bio1);
-		if (make_request(mddev, &bp->bio2))
-			generic_make_request(&bp->bio2);
+		make_request(mddev, &bp->bio1);
+		make_request(mddev, &bp->bio2);
 
 		spin_lock_irq(&conf->resync_lock);
 		conf->nr_waiting--;
@@ -887,14 +885,14 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 		spin_unlock_irq(&conf->resync_lock);
 
 		bio_pair_release(bp);
-		return 0;
+		return;
 	bad_map:
 		printk("md/raid10:%s: make_request bug: can't convert block across chunks"
 		       " or bigger than %dk %llu %d\n", mdname(mddev), chunk_sects/2,
 		       (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
 
 		bio_io_error(bio);
-		return 0;
+		return;
 	}
 
 	md_write_start(mddev, bio);
@@ -937,7 +935,7 @@ read_again:
 		slot = r10_bio->read_slot;
 		if (disk < 0) {
 			raid_end_bio_io(r10_bio);
-			return 0;
+			return;
 		}
 		mirror = conf->mirrors + disk;
 
@@ -985,7 +983,7 @@ read_again:
 			goto read_again;
 		} else
 			generic_make_request(read_bio);
-		return 0;
+		return;
 	}
 
 	/*
@@ -1157,7 +1155,6 @@ retry_write:
 
 	if (do_sync || !mddev->bitmap || !plugged)
 		md_wakeup_thread(mddev->thread);
-	return 0;
 }
 
 static void status(struct seq_file *seq, mddev_t *mddev)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index dbae459fb02..96b7f6a1b6f 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3695,7 +3695,7 @@ static struct stripe_head *__get_priority_stripe(raid5_conf_t *conf)
 	return sh;
 }
 
-static int make_request(mddev_t *mddev, struct bio * bi)
+static void make_request(mddev_t *mddev, struct bio * bi)
 {
 	raid5_conf_t *conf = mddev->private;
 	int dd_idx;
@@ -3708,7 +3708,7 @@ static int make_request(mddev_t *mddev, struct bio * bi)
 
 	if (unlikely(bi->bi_rw & REQ_FLUSH)) {
 		md_flush_request(mddev, bi);
-		return 0;
+		return;
 	}
 
 	md_write_start(mddev, bi);
@@ -3716,7 +3716,7 @@ static int make_request(mddev_t *mddev, struct bio * bi)
 	if (rw == READ &&
 	     mddev->reshape_position == MaxSector &&
 	     chunk_aligned_read(mddev,bi))
-		return 0;
+		return;
 
 	logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
 	last_sector = bi->bi_sector + (bi->bi_size>>9);
@@ -3851,8 +3851,6 @@ static int make_request(mddev_t *mddev, struct bio * bi)
 
 		bio_endio(bi, 0);
 	}
-
-	return 0;
 }
 
 static sector_t raid5_size(mddev_t *mddev, sector_t sectors, int raid_disks);
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 9b43ae94beb..a5a55da2a1a 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -27,7 +27,7 @@
 
 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
 static int dcssblk_release(struct gendisk *disk, fmode_t mode);
-static int dcssblk_make_request(struct request_queue *q, struct bio *bio);
+static void dcssblk_make_request(struct request_queue *q, struct bio *bio);
 static int dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
 				 void **kaddr, unsigned long *pfn);
 
@@ -814,7 +814,7 @@ out:
 	return rc;
 }
 
-static int
+static void
 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct dcssblk_dev_info *dev_info;
@@ -871,10 +871,9 @@ dcssblk_make_request(struct request_queue *q, struct bio *bio)
 		bytes_done += bvec->bv_len;
 	}
 	bio_endio(bio, 0);
-	return 0;
+	return;
 fail:
 	bio_io_error(bio);
-	return 0;
 }
 
 static int
diff --git a/drivers/s390/block/xpram.c b/drivers/s390/block/xpram.c
index 1f6a4d894e7..98f3e4ade92 100644
--- a/drivers/s390/block/xpram.c
+++ b/drivers/s390/block/xpram.c
@@ -181,7 +181,7 @@ static unsigned long xpram_highest_page_index(void)
 /*
  * Block device make request function.
  */
-static int xpram_make_request(struct request_queue *q, struct bio *bio)
+static void xpram_make_request(struct request_queue *q, struct bio *bio)
 {
 	xpram_device_t *xdev = bio->bi_bdev->bd_disk->private_data;
 	struct bio_vec *bvec;
@@ -221,10 +221,9 @@ static int xpram_make_request(struct request_queue *q, struct bio *bio)
 	}
 	set_bit(BIO_UPTODATE, &bio->bi_flags);
 	bio_endio(bio, 0);
-	return 0;
+	return;
 fail:
 	bio_io_error(bio);
-	return 0;
 }
 
 static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index d70ec1ad10d..02589cab671 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -556,24 +556,22 @@ static inline int valid_io_request(struct zram *zram, struct bio *bio)
 /*
  * Handler function for all zram I/O requests.
  */
-static int zram_make_request(struct request_queue *queue, struct bio *bio)
+static void zram_make_request(struct request_queue *queue, struct bio *bio)
 {
 	struct zram *zram = queue->queuedata;
 
 	if (!valid_io_request(zram, bio)) {
 		zram_stat64_inc(zram, &zram->stats.invalid_io);
 		bio_io_error(bio);
-		return 0;
+		return;
 	}
 
 	if (unlikely(!zram->init_done) && zram_init_device(zram)) {
 		bio_io_error(bio);
-		return 0;
+		return;
 	}
 
 	__zram_make_request(zram, bio, bio_data_dir(bio));
-
-	return 0;
 }
 
 void zram_reset_device(struct zram *zram)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 085f95414c7..c712efdafc3 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -193,7 +193,7 @@ struct request_pm_state
 #include <linux/elevator.h>
 
 typedef void (request_fn_proc) (struct request_queue *q);
-typedef int (make_request_fn) (struct request_queue *q, struct bio *bio);
+typedef void (make_request_fn) (struct request_queue *q, struct bio *bio);
 typedef int (prep_rq_fn) (struct request_queue *, struct request *);
 typedef void (unprep_rq_fn) (struct request_queue *, struct request *);
 
@@ -675,7 +675,7 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 			 struct scsi_ioctl_command __user *);
 
-extern int blk_queue_bio(struct request_queue *q, struct bio *bio);
+extern void blk_queue_bio(struct request_queue *q, struct bio *bio);
 
 /*
  * A queue has just exitted congestion.  Note this in the global counter of
-- 
cgit v1.2.3-70-g09d2


From 75df713627f28f88b901b329c8857747545fd4ab Mon Sep 17 00:00:00 2001
From: Suresh Jayaraman <sjayaraman@suse.de>
Date: Wed, 21 Sep 2011 10:00:16 +0200
Subject: block: document blk-plug

Thus spake Andrew Morton:

"And I have the usual maintainability whine.  If someone comes up to
vmscan.c and sees it calling blk_start_plug(), how are they supposed to
work out why that call is there?  They go look at the blk_start_plug()
definition and it is undocumented.  I think we can do better than this?"

Adapted from the LWN article - http://lwn.net/Articles/438256/ by Jens
Axboe and from an earlier attempt by Shaohua Li to document blk-plug.

[akpm@linux-foundation.org: grammatical and spelling tweaks]
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-core.c       | 14 ++++++++++++++
 include/linux/blkdev.h | 24 +++++++++++++++---------
 2 files changed, 29 insertions(+), 9 deletions(-)

(limited to 'include/linux/blkdev.h')

diff --git a/block/blk-core.c b/block/blk-core.c
index 684d7eb33d4..97e9e5405b8 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2595,6 +2595,20 @@ EXPORT_SYMBOL(kblockd_schedule_delayed_work);
 
 #define PLUG_MAGIC	0x91827364
 
+/**
+ * blk_start_plug - initialize blk_plug and track it inside the task_struct
+ * @plug:	The &struct blk_plug that needs to be initialized
+ *
+ * Description:
+ *   Tracking blk_plug inside the task_struct will help with auto-flushing the
+ *   pending I/O should the task end up blocking between blk_start_plug() and
+ *   blk_finish_plug(). This is important from a performance perspective, but
+ *   also ensures that we don't deadlock. For instance, if the task is blocking
+ *   for a memory allocation, memory reclaim could end up wanting to free a
+ *   page belonging to that request that is currently residing in our private
+ *   plug. By flushing the pending I/O when the process goes to sleep, we avoid
+ *   this kind of deadlock.
+ */
 void blk_start_plug(struct blk_plug *plug)
 {
 	struct task_struct *tsk = current;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c712efdafc3..1978655faa3 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -860,17 +860,23 @@ struct request_queue *blk_alloc_queue_node(gfp_t, int);
 extern void blk_put_queue(struct request_queue *);
 
 /*
- * Note: Code in between changing the blk_plug list/cb_list or element of such
- * lists is preemptable, but such code can't do sleep (or be very careful),
- * otherwise data is corrupted. For details, please check schedule() where
- * blk_schedule_flush_plug() is called.
+ * blk_plug permits building a queue of related requests by holding the I/O
+ * fragments for a short period. This allows merging of sequential requests
+ * into single larger request. As the requests are moved from a per-task list to
+ * the device's request_queue in a batch, this results in improved scalability
+ * as the lock contention for request_queue lock is reduced.
+ *
+ * It is ok not to disable preemption when adding the request to the plug list
+ * or when attempting a merge, because blk_schedule_flush_list() will only flush
+ * the plug list when the task sleeps by itself. For details, please see
+ * schedule() where blk_schedule_flush_plug() is called.
  */
 struct blk_plug {
-	unsigned long magic;
-	struct list_head list;
-	struct list_head cb_list;
-	unsigned int should_sort;
-	unsigned int count;
+	unsigned long magic; /* detect uninitialized use-cases */
+	struct list_head list; /* requests */
+	struct list_head cb_list; /* md requires an unplug callback */
+	unsigned int should_sort; /* list to be sorted before flushing? */
+	unsigned int count; /* number of queued requests */
 };
 #define BLK_MAX_REQUEST_COUNT 16
 
-- 
cgit v1.2.3-70-g09d2


From bc9fcbf9cb8ec76d340da16fbf48a9a316e14c52 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Wed, 19 Oct 2011 14:31:18 +0200
Subject: block: move blk_throtl prototypes to block/blk.h

blk_throtl interface is block internal and there's no reason to have
them in linux/blkdev.h.  Move them to block/blk.h.

This patch doesn't introduce any functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-throttle.c   |  1 +
 block/blk.h            | 15 ++++++++++++++-
 include/linux/blkdev.h | 14 --------------
 3 files changed, 15 insertions(+), 15 deletions(-)

(limited to 'include/linux/blkdev.h')

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index a19f58c6fc3..f3f495ea4ee 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -10,6 +10,7 @@
 #include <linux/bio.h>
 #include <linux/blktrace_api.h>
 #include "blk-cgroup.h"
+#include "blk.h"
 
 /* Max dispatch from a group in 1 round */
 static int throtl_grp_quantum = 8;
diff --git a/block/blk.h b/block/blk.h
index 20b900a377c..da247ba2aea 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -188,4 +188,17 @@ static inline int blk_do_io_stat(struct request *rq)
 	        (rq->cmd_flags & REQ_DISCARD));
 }
 
-#endif
+#ifdef CONFIG_BLK_DEV_THROTTLING
+extern int blk_throtl_bio(struct request_queue *q, struct bio **bio);
+extern int blk_throtl_init(struct request_queue *q);
+extern void blk_throtl_exit(struct request_queue *q);
+#else /* CONFIG_BLK_DEV_THROTTLING */
+static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
+{
+	return 0;
+}
+static inline int blk_throtl_init(struct request_queue *q) { return 0; }
+static inline void blk_throtl_exit(struct request_queue *q) { }
+#endif /* CONFIG_BLK_DEV_THROTTLING */
+
+#endif /* BLK_INTERNAL_H */
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0b68044e7ab..5267cd2f20d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1197,20 +1197,6 @@ static inline uint64_t rq_io_start_time_ns(struct request *req)
 }
 #endif
 
-#ifdef CONFIG_BLK_DEV_THROTTLING
-extern int blk_throtl_init(struct request_queue *q);
-extern void blk_throtl_exit(struct request_queue *q);
-extern int blk_throtl_bio(struct request_queue *q, struct bio **bio);
-#else /* CONFIG_BLK_DEV_THROTTLING */
-static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
-{
-	return 0;
-}
-
-static inline int blk_throtl_init(struct request_queue *q) { return 0; }
-static inline int blk_throtl_exit(struct request_queue *q) { return 0; }
-#endif /* CONFIG_BLK_DEV_THROTTLING */
-
 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
 	MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
-- 
cgit v1.2.3-70-g09d2


From de47725421ad5627a5c905f4e40bb844ebc06d29 Mon Sep 17 00:00:00 2001
From: Paul Gortmaker <paul.gortmaker@windriver.com>
Date: Thu, 26 May 2011 13:46:22 -0400
Subject: include: replace linux/module.h with "struct module" wherever
 possible

The <linux/module.h> pretty much brings in the kitchen sink along
with it, so it should be avoided wherever reasonably possible in
terms of being included from other commonly used <linux/something.h>
files, as it results in a measureable increase on compile times.

The worst culprit was probably device.h since it is used everywhere.
This file also had an implicit dependency/usage of mutex.h which was
masked by module.h, and is also fixed here at the same time.

There are over a dozen other headers that simply declare the
struct instead of pulling in the whole file, so follow their lead
and simply make it a few more.

Most of the implicit dependencies on module.h being present by
these headers pulling it in have been now weeded out, so we can
finally make this change with hopefully minimal breakage.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
 include/drm/drmP.h              | 3 ++-
 include/linux/blkdev.h          | 2 +-
 include/linux/cpuidle.h         | 3 ++-
 include/linux/device.h          | 3 ++-
 include/linux/firmware.h        | 2 +-
 include/linux/ftrace.h          | 2 +-
 include/linux/i2c.h             | 3 ++-
 include/linux/ipmi.h            | 3 ++-
 include/linux/ipmi_smi.h        | 1 -
 include/linux/mdio-bitbang.h    | 3 ++-
 include/linux/mtd/mtd.h         | 3 ++-
 include/linux/regmap.h          | 2 +-
 include/linux/sunrpc/svc_xprt.h | 3 ++-
 include/linux/textsearch.h      | 3 ++-
 include/linux/uio_driver.h      | 2 +-
 include/linux/vlynq.h           | 3 ++-
 include/media/saa7146.h         | 3 ++-
 include/media/v4l2-int-device.h | 3 ++-
 include/net/lib80211.h          | 3 ++-
 include/net/sock.h              | 2 +-
 include/sound/core.h            | 2 +-
 include/trace/events/module.h   | 2 +-
 22 files changed, 34 insertions(+), 22 deletions(-)

(limited to 'include/linux/blkdev.h')

diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 43538b64356..6bb4e629c09 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -42,7 +42,6 @@
  * can build the DRM (part of PI DRI). 4/21/2000 S + B */
 #include <asm/current.h>
 #endif				/* __alpha__ */
-#include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/miscdevice.h>
 #include <linux/fs.h>
@@ -80,6 +79,8 @@
 #define __OS_HAS_AGP (defined(CONFIG_AGP) || (defined(CONFIG_AGP_MODULE) && defined(MODULE)))
 #define __OS_HAS_MTRR (defined(CONFIG_MTRR))
 
+struct module;
+
 struct drm_file;
 struct drm_device;
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 7fbaa910334..d750a3a7929 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -14,7 +14,6 @@
 #include <linux/wait.h>
 #include <linux/mempool.h>
 #include <linux/bio.h>
-#include <linux/module.h>
 #include <linux/stringify.h>
 #include <linux/gfp.h>
 #include <linux/bsg.h>
@@ -22,6 +21,7 @@
 
 #include <asm/scatterlist.h>
 
+struct module;
 struct scsi_ioctl_command;
 
 struct request_queue;
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index b51629e15cf..583baf22cad 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -13,7 +13,6 @@
 
 #include <linux/percpu.h>
 #include <linux/list.h>
-#include <linux/module.h>
 #include <linux/kobject.h>
 #include <linux/completion.h>
 
@@ -21,6 +20,8 @@
 #define CPUIDLE_NAME_LEN	16
 #define CPUIDLE_DESC_LEN	32
 
+struct module;
+
 struct cpuidle_device;
 
 
diff --git a/include/linux/device.h b/include/linux/device.h
index 61f29f6a403..8ff7dc801fd 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -20,7 +20,7 @@
 #include <linux/lockdep.h>
 #include <linux/compiler.h>
 #include <linux/types.h>
-#include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/pm.h>
 #include <linux/atomic.h>
 #include <asm/device.h>
@@ -29,6 +29,7 @@ struct device;
 struct device_private;
 struct device_driver;
 struct driver_private;
+struct module;
 struct class;
 struct subsys_private;
 struct bus_type;
diff --git a/include/linux/firmware.h b/include/linux/firmware.h
index 21b3e7588ab..1e7c01189fa 100644
--- a/include/linux/firmware.h
+++ b/include/linux/firmware.h
@@ -1,7 +1,6 @@
 #ifndef _LINUX_FIRMWARE_H
 #define _LINUX_FIRMWARE_H
 
-#include <linux/module.h>
 #include <linux/types.h>
 #include <linux/compiler.h>
 #include <linux/gfp.h>
@@ -15,6 +14,7 @@ struct firmware {
 	struct page **pages;
 };
 
+struct module;
 struct device;
 
 struct builtin_fw {
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index f0c0e8a47ae..26eafcef75b 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -10,7 +10,6 @@
 #include <linux/kallsyms.h>
 #include <linux/linkage.h>
 #include <linux/bitops.h>
-#include <linux/module.h>
 #include <linux/ktime.h>
 #include <linux/sched.h>
 #include <linux/types.h>
@@ -19,6 +18,7 @@
 
 #include <asm/ftrace.h>
 
+struct module;
 struct ftrace_hash;
 
 #ifdef CONFIG_FUNCTION_TRACER
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 1be303bfc25..a81bf6d23b3 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -28,7 +28,6 @@
 
 #include <linux/types.h>
 #ifdef __KERNEL__
-#include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/device.h>	/* for struct device */
 #include <linux/sched.h>	/* for completion */
@@ -49,6 +48,8 @@ struct i2c_driver;
 union i2c_smbus_data;
 struct i2c_board_info;
 
+struct module;
+
 #if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
 /*
  * The master routines are the ones normally used to transmit data to devices
diff --git a/include/linux/ipmi.h b/include/linux/ipmi.h
index ca85cf894e3..bbd156bb953 100644
--- a/include/linux/ipmi.h
+++ b/include/linux/ipmi.h
@@ -220,10 +220,11 @@ struct kernel_ipmi_msg {
  * The in-kernel interface.
  */
 #include <linux/list.h>
-#include <linux/module.h>
 #include <linux/device.h>
 #include <linux/proc_fs.h>
 
+struct module;
+
 /* Opaque type for a IPMI message user.  One of these is needed to
    send and receive messages. */
 typedef struct ipmi_user *ipmi_user_t;
diff --git a/include/linux/ipmi_smi.h b/include/linux/ipmi_smi.h
index 204f9cd26c1..3ef0d8b6aa6 100644
--- a/include/linux/ipmi_smi.h
+++ b/include/linux/ipmi_smi.h
@@ -36,7 +36,6 @@
 
 #include <linux/ipmi_msgdefs.h>
 #include <linux/proc_fs.h>
-#include <linux/module.h>
 #include <linux/device.h>
 #include <linux/platform_device.h>
 #include <linux/ipmi.h>
diff --git a/include/linux/mdio-bitbang.h b/include/linux/mdio-bitbang.h
index 8ea9a42a4c0..0fe00cd4c93 100644
--- a/include/linux/mdio-bitbang.h
+++ b/include/linux/mdio-bitbang.h
@@ -2,7 +2,8 @@
 #define __LINUX_MDIO_BITBANG_H
 
 #include <linux/phy.h>
-#include <linux/module.h>
+
+struct module;
 
 struct mdiobb_ctrl;
 
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 2541fb848da..37be05bbfbc 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -21,7 +21,6 @@
 #define __MTD_MTD_H__
 
 #include <linux/types.h>
-#include <linux/module.h>
 #include <linux/uio.h>
 #include <linux/notifier.h>
 #include <linux/device.h>
@@ -125,6 +124,8 @@ struct nand_ecclayout {
 	struct nand_oobfree oobfree[MTD_MAX_OOBFREE_ENTRIES_LARGE];
 };
 
+struct module;	/* only needed for owner field in mtd_info */
+
 struct mtd_info {
 	u_char type;
 	uint32_t flags;
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 3daac2d8dc3..690276a642c 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -15,8 +15,8 @@
 
 #include <linux/device.h>
 #include <linux/list.h>
-#include <linux/module.h>
 
+struct module;
 struct i2c_client;
 struct spi_device;
 
diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index 7ad9751a0d8..8620f79658d 100644
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -8,7 +8,8 @@
 #define SUNRPC_SVC_XPRT_H
 
 #include <linux/sunrpc/svc.h>
-#include <linux/module.h>
+
+struct module;
 
 struct svc_xprt_ops {
 	struct svc_xprt	*(*xpo_create)(struct svc_serv *,
diff --git a/include/linux/textsearch.h b/include/linux/textsearch.h
index d9a85d61638..cfaee869146 100644
--- a/include/linux/textsearch.h
+++ b/include/linux/textsearch.h
@@ -4,10 +4,11 @@
 #include <linux/types.h>
 #include <linux/list.h>
 #include <linux/kernel.h>
-#include <linux/module.h>
 #include <linux/err.h>
 #include <linux/slab.h>
 
+struct module;
+
 struct ts_config;
 
 #define TS_AUTOLOAD	1 /* Automatically load textsearch modules when needed */
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index 73898189a97..1ad4724458d 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -14,10 +14,10 @@
 #ifndef _UIO_DRIVER_H_
 #define _UIO_DRIVER_H_
 
-#include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/interrupt.h>
 
+struct module;
 struct uio_map;
 
 /**
diff --git a/include/linux/vlynq.h b/include/linux/vlynq.h
index 8f6a95882b0..017d4a53d55 100644
--- a/include/linux/vlynq.h
+++ b/include/linux/vlynq.h
@@ -20,9 +20,10 @@
 #define __VLYNQ_H__
 
 #include <linux/device.h>
-#include <linux/module.h>
 #include <linux/types.h>
 
+struct module;
+
 #define VLYNQ_NUM_IRQS 32
 
 struct vlynq_mapping {
diff --git a/include/media/saa7146.h b/include/media/saa7146.h
index 79827143d5a..6e84cde44b8 100644
--- a/include/media/saa7146.h
+++ b/include/media/saa7146.h
@@ -1,7 +1,6 @@
 #ifndef __SAA7146__
 #define __SAA7146__
 
-#include <linux/module.h>	/* for module-version */
 #include <linux/delay.h>	/* for delay-stuff */
 #include <linux/slab.h>		/* for kmalloc/kfree */
 #include <linux/pci.h>		/* for pci-config-stuff, vendor ids etc. */
@@ -47,6 +46,8 @@ extern unsigned int saa7146_debug;
 #define SAA7146_ISR_CLEAR(x,y) \
 	saa7146_write(x, ISR, (y));
 
+struct module;
+
 struct saa7146_dev;
 struct saa7146_extension;
 struct saa7146_vv;
diff --git a/include/media/v4l2-int-device.h b/include/media/v4l2-int-device.h
index fbf58556157..e6aa2318367 100644
--- a/include/media/v4l2-int-device.h
+++ b/include/media/v4l2-int-device.h
@@ -25,7 +25,6 @@
 #ifndef V4L2_INT_DEVICE_H
 #define V4L2_INT_DEVICE_H
 
-#include <linux/module.h>
 #include <media/v4l2-common.h>
 
 #define V4L2NAMESIZE 32
@@ -41,6 +40,8 @@ enum v4l2_int_type {
 	v4l2_int_type_slave
 };
 
+struct module;
+
 struct v4l2_int_device;
 
 struct v4l2_int_master {
diff --git a/include/net/lib80211.h b/include/net/lib80211.h
index 2ec896bb72b..d178c26a555 100644
--- a/include/net/lib80211.h
+++ b/include/net/lib80211.h
@@ -25,7 +25,6 @@
 
 #include <linux/types.h>
 #include <linux/list.h>
-#include <linux/module.h>
 #include <linux/atomic.h>
 #include <linux/if.h>
 #include <linux/skbuff.h>
@@ -42,6 +41,8 @@ enum {
 	IEEE80211_CRYPTO_TKIP_COUNTERMEASURES = (1 << 0),
 };
 
+struct module;
+
 struct lib80211_crypto_ops {
 	const char *name;
 	struct list_head list;
diff --git a/include/net/sock.h b/include/net/sock.h
index 5ac682f73d6..beb1a911acb 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -46,7 +46,6 @@
 #include <linux/list_nulls.h>
 #include <linux/timer.h>
 #include <linux/cache.h>
-#include <linux/module.h>
 #include <linux/lockdep.h>
 #include <linux/netdevice.h>
 #include <linux/skbuff.h>	/* struct sk_buff */
@@ -729,6 +728,7 @@ struct request_sock_ops;
 struct timewait_sock_ops;
 struct inet_hashinfo;
 struct raw_hashinfo;
+struct module;
 
 /* Networking protocol blocks we attach to sockets.
  * socket layer -> transport layer interface
diff --git a/include/sound/core.h b/include/sound/core.h
index 1fa2407c966..a91d78eb2f0 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -22,7 +22,6 @@
  *
  */
 
-#include <linux/module.h>
 #include <linux/sched.h>		/* wake_up() */
 #include <linux/mutex.h>		/* struct mutex */
 #include <linux/rwsem.h>		/* struct rw_semaphore */
@@ -43,6 +42,7 @@
 #ifdef CONFIG_PCI
 struct pci_dev;
 #endif
+struct module;
 
 /* device allocation stuff */
 
diff --git a/include/trace/events/module.h b/include/trace/events/module.h
index 21a546d27c0..16193273741 100644
--- a/include/trace/events/module.h
+++ b/include/trace/events/module.h
@@ -1,6 +1,6 @@
 /*
  * Because linux/module.h has tracepoints in the header, and ftrace.h
- * eventually includes this file, define_trace.h includes linux/module.h
+ * used to include this file, define_trace.h includes linux/module.h
  * But we do not want the module.h to override the TRACE_SYSTEM macro
  * variable that define_trace.h is processing, so we only set it
  * when module events are being processed, which would happen when
-- 
cgit v1.2.3-70-g09d2