[PATCH] bdev->bd_disk introduced

There we go - now we can put a reference to gendisk into block_device.  Which
we do in do_open().  Most of the callers of get_gendisk() are simply using
bdev->bd_disk now (and most of the put_disk() calls introduced on previous
step disappear).  We also put that pointer into struct request - ->rq_disk.
That allows to get rid of disk_index() kludges in md.c (we simply count
relevant IO in the struct gendisk fields) and kill the export of get_gendisk().
	Notice that by now we can move _all_ IO counters into gendisk.  That
will kill a bunch of per-major arrays and more importantly, allow to merge
sard in clean way.  FWIW, we probably could show them as disk/partitions
attributes in driverfs...

drivers/block/genhd.c

@@ -61,10 +61,7 @@ void add_disk(struct gendisk *disk)
 {
 	write_lock(&gendisk_lock);
 	list_add(&disk->list, &gendisks[disk->major].list);
-	if (disk->minors > 1)
 	list_add_tail(&disk->full_list, &gendisk_list);
-	else
-		INIT_LIST_HEAD(&disk->full_list);
 	write_unlock(&gendisk_lock);
 	disk->flags |= GENHD_FL_UP;
 	register_disk(disk);
@@ -120,8 +117,6 @@ get_gendisk(dev_t dev, int *part)
 	return NULL;
 }
 
-EXPORT_SYMBOL(get_gendisk);
-
 #ifdef CONFIG_PROC_FS
 /* iterator */
 static void *part_start(struct seq_file *part, loff_t *pos)
@@ -158,7 +153,7 @@ static int show_partition(struct seq_file *part, void *v)
 		seq_puts(part, "major minor  #blocks  name\n\n");
 
 	/* Don't show non-partitionable devices or empty devices */
-	if (!get_capacity(sgp))
+	if (!get_capacity(sgp) || sgp->minors == 1)
 		return 0;
 
 	/* show the full disk and all non-0 size partitions of it */
@@ -239,6 +234,7 @@ struct gendisk *alloc_disk(int minors)
 		disk->minors = minors;
 		while (minors >>= 1)
 			disk->minor_shift++;
+		INIT_LIST_HEAD(&disk->full_list);
 		disk->disk_dev.bus = &disk_bus;
 		disk->disk_dev.release = disk_release;
 		disk->disk_dev.driver_data = disk;

drivers/block/ioctl.c

@@ -22,21 +22,12 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg *arg)
 		return -EFAULT;
 	if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition)))
 		return -EFAULT;
-	disk = get_gendisk(bdev->bd_dev, &part);
-	if (!disk)
-		return -ENXIO;
-	if (bdev != bdev->bd_contains) {
-		put_disk(disk);
+	disk = bdev->bd_disk;
+	if (bdev != bdev->bd_contains)
 		return -EINVAL;
-	}
-	if (part)
-		BUG();
 	part = p.pno;
-	if (part <= 0 || part >= disk->minors) {
-		put_disk(disk);
+	if (part <= 0 || part >= disk->minors)
 		return -EINVAL;
-	}
-
 	switch (a.op) {
 		case BLKPG_ADD_PARTITION:
 			start = p.start >> 9;
@@ -46,49 +37,33 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg *arg)
 			    sizeof(long long) > sizeof(long)) {
 				long pstart = start, plength = length;
 				if (pstart != start || plength != length
-				    || pstart < 0 || plength < 0) {
-					put_disk(disk);
+				    || pstart < 0 || plength < 0)
 					return -EINVAL;
 			}
-			}
-
 			/* partition number in use? */
-			if (disk->part[part - 1].nr_sects != 0) {
-				put_disk(disk);
+			if (disk->part[part - 1].nr_sects != 0)
 				return -EBUSY;
-			}
-
 			/* overlap? */
 			for (i = 0; i < disk->minors - 1; i++) {
 				struct hd_struct *s = &disk->part[i];
 				if (!(start+length <= s->start_sect ||
-				      start >= s->start_sect + s->nr_sects)) {
-					put_disk(disk);
+				      start >= s->start_sect + s->nr_sects))
 					return -EBUSY;
 			}
-			}
 			/* all seems OK */
 			add_partition(disk, part, start, length);
-			put_disk(disk);
 			return 0;
 		case BLKPG_DEL_PARTITION:
-			if (disk->part[part - 1].nr_sects == 0) {
-				put_disk(disk);
+			if (disk->part[part - 1].nr_sects == 0)
 				return -ENXIO;
-			}
-
 			/* partition in use? Incomplete check for now. */
 			bdevp = bdget(MKDEV(disk->major, disk->first_minor) + part);
-			if (!bdevp) {
-				put_disk(disk);
+			if (!bdevp)
 				return -ENOMEM;
-			}
 			if (bd_claim(bdevp, &holder) < 0) {
 				bdput(bdevp);
-				put_disk(disk);
 				return -EBUSY;
 			}
-
 			/* all seems OK */
 			fsync_bdev(bdevp);
 			invalidate_bdev(bdevp, 0);
@@ -96,39 +71,25 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg *arg)
 			delete_partition(disk, part);
 			bd_release(bdevp);
 			bdput(bdevp);
-			put_disk(disk);
 			return 0;
 		default:
-			put_disk(disk);
 			return -EINVAL;
 	}
 }
 
 static int blkdev_reread_part(struct block_device *bdev)
 {
-	int part;
-	struct gendisk *disk = get_gendisk(bdev->bd_dev, &part);
-	int res = 0;
+	struct gendisk *disk = bdev->bd_disk;
+	int res;
 
-	if (!disk)
-		return -EINVAL;
-	if (disk->minors == 1 || bdev != bdev->bd_contains) {
-		put_disk(disk);
+	if (disk->minors == 1 || bdev != bdev->bd_contains)
 		return -EINVAL;
-	}
-	if (part)
-		BUG();
-	if (!capable(CAP_SYS_ADMIN)) {
-		put_disk(disk);
+	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
-	}
-	if (down_trylock(&bdev->bd_sem)) {
-		put_disk(disk);
+	if (down_trylock(&bdev->bd_sem))
 		return -EBUSY;
-	}
 	res = rescan_partitions(disk, bdev);
 	up(&bdev->bd_sem);
-	put_disk(disk);
 	return res;
 }
 

drivers/block/ll_rw_blk.c

@@ -1427,7 +1427,19 @@ void drive_stat_acct(struct request *rq, int nr_sectors, int new_io)
 	int rw = rq_data_dir(rq);
 	unsigned int index;
 
-	index = disk_index(rq->rq_dev);
+	if (!rq->rq_disk)
+		return;
+
+	if (rw == READ) {
+		rq->rq_disk->rio += new_io;
+		rq->rq_disk->reads += nr_sectors;
+	} else if (rw == WRITE) {
+		rq->rq_disk->wio += new_io;
+		rq->rq_disk->writes += nr_sectors;
+	}
+
+	index = rq->rq_disk->first_minor >> rq->rq_disk->minor_shift;
+
 	if ((index >= DK_MAX_DISK) || (major >= DK_MAX_MAJOR))
 		return;
 
@@ -1747,6 +1759,7 @@ static int __make_request(request_queue_t *q, struct bio *bio)
 	req->waiting = NULL;
 	req->bio = req->biotail = bio;
 	req->rq_dev = to_kdev_t(bio->bi_bdev->bd_dev);
+	req->rq_disk = bio->bi_bdev->bd_disk;
 	add_request(q, req, insert_here);
 out:
 	if (freereq)

drivers/block/rd.c

@@ -381,6 +381,7 @@ static int rd_open(struct inode * inode, struct file * filp)
 		rd_bdev[unit]->bd_inode->i_mapping->a_ops = &ramdisk_aops;
 		rd_bdev[unit]->bd_inode->i_size = rd_length[unit];
 		rd_bdev[unit]->bd_queue = &blk_dev[MAJOR_NR].request_queue;
+		rd_bdev[unit]->bd_disk = get_disk(rd_disks[unit]);
 	}
 
 	return 0;

drivers/md/md.c

@@ -2731,18 +2731,9 @@ int unregister_md_personality(int pnum)
 	return 0;
 }
 
-static unsigned int sync_io[DK_MAX_MAJOR][DK_MAX_DISK];
 void md_sync_acct(mdk_rdev_t *rdev, unsigned long nr_sectors)
 {
-	kdev_t dev = to_kdev_t(rdev->bdev->bd_dev);
-	unsigned int major = major(dev);
-	unsigned int index;
-
-	index = disk_index(dev);
-	if ((index >= DK_MAX_DISK) || (major >= DK_MAX_MAJOR))
-		return;
-
-	sync_io[major][index] += nr_sectors;
+	rdev->bdev->bd_disk->sync_io += nr_sectors;
 }
 
 static int is_mddev_idle(mddev_t *mddev)
@@ -2754,16 +2745,8 @@ static int is_mddev_idle(mddev_t *mddev)
 
 	idle = 1;
 	ITERATE_RDEV(mddev,rdev,tmp) {
-		kdev_t dev = to_kdev_t(rdev->bdev->bd_dev);
-		int major = major(dev);
-		int idx = disk_index(dev);
-
-		if ((idx >= DK_MAX_DISK) || (major >= DK_MAX_MAJOR))
-			continue;
-
-		curr_events = kstat.dk_drive_rblk[major][idx] +
-						kstat.dk_drive_wblk[major][idx] ;
-		curr_events -= sync_io[major][idx];
+		struct gendisk *disk = rdev->bdev->bd_disk;
+		curr_events = disk->reads + disk->writes - disk->sync_io;
 		if ((curr_events - rdev->last_events) > 32) {
 			rdev->last_events = curr_events;
 			idle = 0;

fs/block_dev.c

@@ -526,8 +526,6 @@ int check_disk_change(struct block_device *bdev)
 {
 	struct block_device_operations * bdops = bdev->bd_op;
 	kdev_t dev = to_kdev_t(bdev->bd_dev);
-	struct gendisk *disk;
-	int part;
 
 	if (bdops->check_media_change == NULL)
 		return 0;
@@ -537,26 +535,21 @@ int check_disk_change(struct block_device *bdev)
 	if (invalidate_device(dev, 0))
 		printk("VFS: busy inodes on changed media.\n");
 
-	disk = get_gendisk(bdev->bd_dev, &part);
 	if (bdops->revalidate)
 		bdops->revalidate(dev);
-	if (disk && disk->minors > 1)
+	if (bdev->bd_disk->minors > 1)
 		bdev->bd_invalidated = 1;
-	put_disk(disk);
 	return 1;
 }
 
 int full_check_disk_change(struct block_device *bdev)
 {
 	int res = 0;
-	int n;
 	if (bdev->bd_contains != bdev)
 		BUG();
 	down(&bdev->bd_sem);
 	if (check_disk_change(bdev)) {
-		struct gendisk *disk = get_gendisk(bdev->bd_dev, &n);
-		rescan_partitions(disk, bdev);
-		put_disk(disk);
+		rescan_partitions(bdev->bd_disk, bdev);
 		res = 1;
 	}
 	up(&bdev->bd_sem);
@@ -598,6 +591,8 @@ static int do_open(struct block_device *bdev, struct inode *inode, struct file *
 	kdev_t dev = to_kdev_t(bdev->bd_dev);
 	struct module *owner = NULL;
 	struct block_device_operations *ops, *old;
+	struct gendisk *disk;
+	int part;
 
 	lock_kernel();
 	ops = get_blkfops(major(dev));
@@ -617,53 +612,41 @@ static int do_open(struct block_device *bdev, struct inode *inode, struct file *
 		if (owner)
 			__MOD_DEC_USE_COUNT(owner);
 	}
+	disk = get_gendisk(bdev->bd_dev, &part);
+	if (!disk)
+		goto out1;
 	if (!bdev->bd_contains) {
-		int part;
-		struct gendisk *g = get_gendisk(bdev->bd_dev, &part);
 		bdev->bd_contains = bdev;
-		if (g && part) {
-			struct block_device *disk;
-			disk = bdget(MKDEV(g->major, g->first_minor));
+		if (part) {
+			struct block_device *whole;
+			whole = bdget(MKDEV(disk->major, disk->first_minor));
 			ret = -ENOMEM;
-			if (!disk) {
-				put_disk(g);
+			if (!whole)
 				goto out1;
-			}
-			ret = blkdev_get(disk, file->f_mode, file->f_flags, BDEV_RAW);
-			if (ret) {
-				put_disk(g);
+			ret = blkdev_get(whole, file->f_mode, file->f_flags, BDEV_RAW);
+			if (ret)
 				goto out1;
+			bdev->bd_contains = whole;
 		}
-			bdev->bd_contains = disk;
-		}
-		put_disk(g);
 	}
 	if (bdev->bd_contains == bdev) {
-		int part;
-		struct gendisk *g = get_gendisk(bdev->bd_dev, &part);
-
+		if (!bdev->bd_openers)
+			bdev->bd_disk = disk;
 		if (!bdev->bd_queue) {
 			struct blk_dev_struct *p = blk_dev + major(dev);
 			bdev->bd_queue = &p->request_queue;
 			if (p->queue)
 				bdev->bd_queue =  p->queue(dev);
 		}
-
 		if (bdev->bd_op->open) {
 			ret = bdev->bd_op->open(inode, file);
-			if (ret) {
-				put_disk(g);
+			if (ret)
 				goto out2;
 		}
-		}
 		if (!bdev->bd_openers) {
 			struct backing_dev_info *bdi;
-			sector_t sect = 0;
-
 			bdev->bd_offset = 0;
-			if (g)
-				sect = get_capacity(g);
-			bd_set_size(bdev, (loff_t)sect << 9);
+			bd_set_size(bdev, (loff_t)get_capacity(disk) << 9);
 			bdi = blk_get_backing_dev_info(bdev);
 			if (bdi == NULL)
 				bdi = &default_backing_dev_info;
@@ -671,34 +654,31 @@ static int do_open(struct block_device *bdev, struct inode *inode, struct file *
 			bdev->bd_inode->i_data.backing_dev_info = bdi;
 		}
 		if (bdev->bd_invalidated)
-			rescan_partitions(g, bdev);
-		put_disk(g);
+			rescan_partitions(disk, bdev);
 	} else {
 		down(&bdev->bd_contains->bd_sem);
 		bdev->bd_contains->bd_part_count++;
 		if (!bdev->bd_openers) {
-			int part;
-			struct gendisk *g = get_gendisk(bdev->bd_dev, &part);
 			struct hd_struct *p;
-			p = g->part + part - 1;
+			p = disk->part + part - 1;
 			inode->i_data.backing_dev_info =
 			   bdev->bd_inode->i_data.backing_dev_info =
 			   bdev->bd_contains->bd_inode->i_data.backing_dev_info;
-			if (!(g->flags & GENHD_FL_UP) || !p->nr_sects) {
+			if (!(disk->flags & GENHD_FL_UP) || !p->nr_sects) {
 				bdev->bd_contains->bd_part_count--;
 				up(&bdev->bd_contains->bd_sem);
-				put_disk(g);
 				ret = -ENXIO;
 				goto out2;
 			}
 			bdev->bd_queue = bdev->bd_contains->bd_queue;
 			bdev->bd_offset = p->start_sect;
 			bd_set_size(bdev, (loff_t) p->nr_sects << 9);
-			put_disk(g);
+			bdev->bd_disk = disk;
 		}
 		up(&bdev->bd_contains->bd_sem);
 	}
-	bdev->bd_openers++;
+	if (bdev->bd_openers++)
+		put_disk(disk);
 	up(&bdev->bd_sem);
 	unlock_kernel();
 	return 0;
@@ -712,6 +692,7 @@ static int do_open(struct block_device *bdev, struct inode *inode, struct file *
 		}
 	}
 out1:
+	put_disk(disk);
 	if (!old) {
 		bdev->bd_op = NULL;
 		if (owner)
@@ -785,15 +766,18 @@ int blkdev_put(struct block_device *bdev, int kind)
 		up(&bdev->bd_contains->bd_sem);
 	}
 	if (!bdev->bd_openers) {
+		struct gendisk *disk = bdev->bd_disk;
 		if (bdev->bd_op->owner)
 			__MOD_DEC_USE_COUNT(bdev->bd_op->owner);
 		bdev->bd_op = NULL;
 		bdev->bd_queue = NULL;
+		bdev->bd_disk = NULL;
 		bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
 		if (bdev != bdev->bd_contains) {
 			blkdev_put(bdev->bd_contains, BDEV_RAW);
 			bdev->bd_contains = NULL;
 		}
+		put_disk(disk);
 	}
 	unlock_kernel();
 	up(&bdev->bd_sem);

include/linux/blkdev.h

@@ -34,6 +34,7 @@ struct request {
 
 	int rq_status;	/* should split this into a few status bits */
 	kdev_t rq_dev;
+	struct gendisk *rq_disk;
 	int errors;
 	sector_t sector;
 	unsigned long nr_sectors;

include/linux/fs.h

@@ -359,6 +359,7 @@ struct block_device {
 	sector_t		bd_offset;
 	unsigned		bd_part_count;
 	int			bd_invalidated;
+	struct gendisk *	bd_disk;
 };
 
 struct inode {

include/linux/genhd.h

@@ -90,6 +90,10 @@ struct gendisk {
 	devfs_handle_t disk_de;		/* piled higher and deeper */
 	struct device *driverfs_dev;
 	struct device disk_dev;
+
+	unsigned sync_io;		/* RAID */
+	unsigned reads, writes;
+	unsigned rio, wio;
 };
 
 /* drivers/block/genhd.c */
@@ -272,15 +276,6 @@ extern void put_disk(struct gendisk *disk);
 /* will go away */
 extern void blk_set_probe(int major, struct gendisk *(p)(int));
 
-static inline unsigned int disk_index (kdev_t dev)
-{
-	int part, res;
-	struct gendisk *g = get_gendisk(kdev_t_to_nr(dev), &part);
-	res = g ? (minor(dev) >> g->minor_shift) : 0;
-	put_disk(g);
-	return res;
-}
-
 #endif
 
 #endif