1 files changed, 634 insertions, 331 deletions

diff --git a/block/genhd.c b/block/genhd.c
index e0ce23ac2ece..4cd3433c99ac 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -16,6 +16,7 @@
 #include <linux/kobj_map.h>
 #include <linux/buffer_head.h>
 #include <linux/mutex.h>
+#include <linux/idr.h>
 
 #include "blk.h"
 
@@ -24,8 +25,194 @@ static DEFINE_MUTEX(block_class_lock);
 struct kobject *block_depr;
 #endif
 
+/* for extended dynamic devt allocation, currently only one major is used */
+#define MAX_EXT_DEVT		(1 << MINORBITS)
+
+/* For extended devt allocation.  ext_devt_mutex prevents look up
+ * results from going away underneath its user.
+ */
+static DEFINE_MUTEX(ext_devt_mutex);
+static DEFINE_IDR(ext_devt_idr);
+
 static struct device_type disk_type;
 
+/**
+ * disk_get_part - get partition
+ * @disk: disk to look partition from
+ * @partno: partition number
+ *
+ * Look for partition @partno from @disk.  If found, increment
+ * reference count and return it.
+ *
+ * CONTEXT:
+ * Don't care.
+ *
+ * RETURNS:
+ * Pointer to the found partition on success, NULL if not found.
+ */
+struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
+{
+	struct hd_struct *part = NULL;
+	struct disk_part_tbl *ptbl;
+
+	if (unlikely(partno < 0))
+		return NULL;
+
+	rcu_read_lock();
+
+	ptbl = rcu_dereference(disk->part_tbl);
+	if (likely(partno < ptbl->len)) {
+		part = rcu_dereference(ptbl->part[partno]);
+		if (part)
+			get_device(part_to_dev(part));
+	}
+
+	rcu_read_unlock();
+
+	return part;
+}
+EXPORT_SYMBOL_GPL(disk_get_part);
+
+/**
+ * disk_part_iter_init - initialize partition iterator
+ * @piter: iterator to initialize
+ * @disk: disk to iterate over
+ * @flags: DISK_PITER_* flags
+ *
+ * Initialize @piter so that it iterates over partitions of @disk.
+ *
+ * CONTEXT:
+ * Don't care.
+ */
+void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
+			  unsigned int flags)
+{
+	struct disk_part_tbl *ptbl;
+
+	rcu_read_lock();
+	ptbl = rcu_dereference(disk->part_tbl);
+
+	piter->disk = disk;
+	piter->part = NULL;
+
+	if (flags & DISK_PITER_REVERSE)
+		piter->idx = ptbl->len - 1;
+	else if (flags & DISK_PITER_INCL_PART0)
+		piter->idx = 0;
+	else
+		piter->idx = 1;
+
+	piter->flags = flags;
+
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(disk_part_iter_init);
+
+/**
+ * disk_part_iter_next - proceed iterator to the next partition and return it
+ * @piter: iterator of interest
+ *
+ * Proceed @piter to the next partition and return it.
+ *
+ * CONTEXT:
+ * Don't care.
+ */
+struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
+{
+	struct disk_part_tbl *ptbl;
+	int inc, end;
+
+	/* put the last partition */
+	disk_put_part(piter->part);
+	piter->part = NULL;
+
+	/* get part_tbl */
+	rcu_read_lock();
+	ptbl = rcu_dereference(piter->disk->part_tbl);
+
+	/* determine iteration parameters */
+	if (piter->flags & DISK_PITER_REVERSE) {
+		inc = -1;
+		if (piter->flags & DISK_PITER_INCL_PART0)
+			end = -1;
+		else
+			end = 0;
+	} else {
+		inc = 1;
+		end = ptbl->len;
+	}
+
+	/* iterate to the next partition */
+	for (; piter->idx != end; piter->idx += inc) {
+		struct hd_struct *part;
+
+		part = rcu_dereference(ptbl->part[piter->idx]);
+		if (!part)
+			continue;
+		if (!(piter->flags & DISK_PITER_INCL_EMPTY) && !part->nr_sects)
+			continue;
+
+		get_device(part_to_dev(part));
+		piter->part = part;
+		piter->idx += inc;
+		break;
+	}
+
+	rcu_read_unlock();
+
+	return piter->part;
+}
+EXPORT_SYMBOL_GPL(disk_part_iter_next);
+
+/**
+ * disk_part_iter_exit - finish up partition iteration
+ * @piter: iter of interest
+ *
+ * Called when iteration is over.  Cleans up @piter.
+ *
+ * CONTEXT:
+ * Don't care.
+ */
+void disk_part_iter_exit(struct disk_part_iter *piter)
+{
+	disk_put_part(piter->part);
+	piter->part = NULL;
+}
+EXPORT_SYMBOL_GPL(disk_part_iter_exit);
+
+/**
+ * disk_map_sector_rcu - map sector to partition
+ * @disk: gendisk of interest
+ * @sector: sector to map
+ *
+ * Find out which partition @sector maps to on @disk.  This is
+ * primarily used for stats accounting.
+ *
+ * CONTEXT:
+ * RCU read locked.  The returned partition pointer is valid only
+ * while preemption is disabled.
+ *
+ * RETURNS:
+ * Found partition on success, part0 is returned if no partition matches
+ */
+struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
+{
+	struct disk_part_tbl *ptbl;
+	int i;
+
+	ptbl = rcu_dereference(disk->part_tbl);
+
+	for (i = 1; i < ptbl->len; i++) {
+		struct hd_struct *part = rcu_dereference(ptbl->part[i]);
+
+		if (part && part->start_sect <= sector &&
+		    sector < part->start_sect + part->nr_sects)
+			return part;
+	}
+	return &disk->part0;
+}
+EXPORT_SYMBOL_GPL(disk_map_sector_rcu);
+
 /*
  * Can be deleted altogether. Later.
  *
@@ -43,14 +230,14 @@ static inline int major_to_index(int major)
 }
 
 #ifdef CONFIG_PROC_FS
-void blkdev_show(struct seq_file *f, off_t offset)
+void blkdev_show(struct seq_file *seqf, off_t offset)
 {
 	struct blk_major_name *dp;
 
 	if (offset < BLKDEV_MAJOR_HASH_SIZE) {
 		mutex_lock(&block_class_lock);
 		for (dp = major_names[offset]; dp; dp = dp->next)
-			seq_printf(f, "%3d %s\n", dp->major, dp->name);
+			seq_printf(seqf, "%3d %s\n", dp->major, dp->name);
 		mutex_unlock(&block_class_lock);
 	}
 }
@@ -136,6 +323,118 @@ EXPORT_SYMBOL(unregister_blkdev);
 
 static struct kobj_map *bdev_map;
 
+/**
+ * blk_mangle_minor - scatter minor numbers apart
+ * @minor: minor number to mangle
+ *
+ * Scatter consecutively allocated @minor number apart if MANGLE_DEVT
+ * is enabled.  Mangling twice gives the original value.
+ *
+ * RETURNS:
+ * Mangled value.
+ *
+ * CONTEXT:
+ * Don't care.
+ */
+static int blk_mangle_minor(int minor)
+{
+#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
+	int i;
+
+	for (i = 0; i < MINORBITS / 2; i++) {
+		int low = minor & (1 << i);
+		int high = minor & (1 << (MINORBITS - 1 - i));
+		int distance = MINORBITS - 1 - 2 * i;
+
+		minor ^= low | high;	/* clear both bits */
+		low <<= distance;	/* swap the positions */
+		high >>= distance;
+		minor |= low | high;	/* and set */
+	}
+#endif
+	return minor;
+}
+
+/**
+ * blk_alloc_devt - allocate a dev_t for a partition
+ * @part: partition to allocate dev_t for
+ * @gfp_mask: memory allocation flag
+ * @devt: out parameter for resulting dev_t
+ *
+ * Allocate a dev_t for block device.
+ *
+ * RETURNS:
+ * 0 on success, allocated dev_t is returned in *@devt.  -errno on
+ * failure.
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
+{
+	struct gendisk *disk = part_to_disk(part);
+	int idx, rc;
+
+	/* in consecutive minor range? */
+	if (part->partno < disk->minors) {
+		*devt = MKDEV(disk->major, disk->first_minor + part->partno);
+		return 0;
+	}
+
+	/* allocate ext devt */
+	do {
+		if (!idr_pre_get(&ext_devt_idr, GFP_KERNEL))
+			return -ENOMEM;
+		rc = idr_get_new(&ext_devt_idr, part, &idx);
+	} while (rc == -EAGAIN);
+
+	if (rc)
+		return rc;
+
+	if (idx > MAX_EXT_DEVT) {
+		idr_remove(&ext_devt_idr, idx);
+		return -EBUSY;
+	}
+
+	*devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx));
+	return 0;
+}
+
+/**
+ * blk_free_devt - free a dev_t
+ * @devt: dev_t to free
+ *
+ * Free @devt which was allocated using blk_alloc_devt().
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+void blk_free_devt(dev_t devt)
+{
+	might_sleep();
+
+	if (devt == MKDEV(0, 0))
+		return;
+
+	if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
+		mutex_lock(&ext_devt_mutex);
+		idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
+		mutex_unlock(&ext_devt_mutex);
+	}
+}
+
+static char *bdevt_str(dev_t devt, char *buf)
+{
+	if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
+		char tbuf[BDEVT_SIZE];
+		snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
+		snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
+	} else
+		snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));
+
+	return buf;
+}
+
 /*
  * Register device numbers dev..(dev+range-1)
  * range must be nonzero
@@ -157,11 +456,11 @@ void blk_unregister_region(dev_t devt, unsigned long range)
 
 EXPORT_SYMBOL(blk_unregister_region);
 
-static struct kobject *exact_match(dev_t devt, int *part, void *data)
+static struct kobject *exact_match(dev_t devt, int *partno, void *data)
 {
 	struct gendisk *p = data;
 
-	return &p->dev.kobj;
+	return &disk_to_dev(p)->kobj;
 }
 
 static int exact_lock(dev_t devt, void *data)
@@ -179,21 +478,46 @@ static int exact_lock(dev_t devt, void *data)
  *
  * This function registers the partitioning information in @disk
  * with the kernel.
+ *
+ * FIXME: error handling
  */
 void add_disk(struct gendisk *disk)
 {
 	struct backing_dev_info *bdi;
+	dev_t devt;
 	int retval;
 
+	/* minors == 0 indicates to use ext devt from part0 and should
+	 * be accompanied with EXT_DEVT flag.  Make sure all
+	 * parameters make sense.
+	 */
+	WARN_ON(disk->minors && !(disk->major || disk->first_minor));
+	WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT));
+
 	disk->flags |= GENHD_FL_UP;
-	blk_register_region(MKDEV(disk->major, disk->first_minor),
-			    disk->minors, NULL, exact_match, exact_lock, disk);
+
+	retval = blk_alloc_devt(&disk->part0, &devt);
+	if (retval) {
+		WARN_ON(1);
+		return;
+	}
+	disk_to_dev(disk)->devt = devt;
+
+	/* ->major and ->first_minor aren't supposed to be
+	 * dereferenced from here on, but set them just in case.
+	 */
+	disk->major = MAJOR(devt);
+	disk->first_minor = MINOR(devt);
+
+	blk_register_region(disk_devt(disk), disk->minors, NULL,
+			    exact_match, exact_lock, disk);
 	register_disk(disk);
 	blk_register_queue(disk);
 
 	bdi = &disk->queue->backing_dev_info;
-	bdi_register_dev(bdi, MKDEV(disk->major, disk->first_minor));
-	retval = sysfs_create_link(&disk->dev.kobj, &bdi->dev->kobj, "bdi");
+	bdi_register_dev(bdi, disk_devt(disk));
+	retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
+				   "bdi");
 	WARN_ON(retval);
 }
 
@@ -202,78 +526,71 @@ EXPORT_SYMBOL(del_gendisk);	/* in partitions/check.c */
 
 void unlink_gendisk(struct gendisk *disk)
 {
-	sysfs_remove_link(&disk->dev.kobj, "bdi");
+	sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
 	bdi_unregister(&disk->queue->backing_dev_info);
 	blk_unregister_queue(disk);
-	blk_unregister_region(MKDEV(disk->major, disk->first_minor),
-			      disk->minors);
+	blk_unregister_region(disk_devt(disk), disk->minors);
 }
 
 /**
  * get_gendisk - get partitioning information for a given device
- * @dev: device to get partitioning information for
+ * @devt: device to get partitioning information for
+ * @part: returned partition index
  *
  * This function gets the structure containing partitioning
- * information for the given device @dev.
+ * information for the given device @devt.
  */
-struct gendisk *get_gendisk(dev_t devt, int *part)
+struct gendisk *get_gendisk(dev_t devt, int *partno)
 {
-	struct kobject *kobj = kobj_lookup(bdev_map, devt, part);
-	struct device *dev = kobj_to_dev(kobj);
+	struct gendisk *disk = NULL;
+
+	if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
+		struct kobject *kobj;
+
+		kobj = kobj_lookup(bdev_map, devt, partno);
+		if (kobj)
+			disk = dev_to_disk(kobj_to_dev(kobj));
+	} else {
+		struct hd_struct *part;
 
-	return  kobj ? dev_to_disk(dev) : NULL;
+		mutex_lock(&ext_devt_mutex);
+		part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
+		if (part && get_disk(part_to_disk(part))) {
+			*partno = part->partno;
+			disk = part_to_disk(part);
+		}
+		mutex_unlock(&ext_devt_mutex);
+	}
+
+	return disk;
 }
 
-/*
- * print a partitions - intended for places where the root filesystem can't be
- * mounted and thus to give the victim some idea of what went wrong
+/**
+ * bdget_disk - do bdget() by gendisk and partition number
+ * @disk: gendisk of interest
+ * @partno: partition number
+ *
+ * Find partition @partno from @disk, do bdget() on it.
+ *
+ * CONTEXT:
+ * Don't care.
+ *
+ * RETURNS:
+ * Resulting block_device on success, NULL on failure.
  */
-static int printk_partition(struct device *dev, void *data)
+struct block_device *bdget_disk(struct gendisk *disk, int partno)
 {
-	struct gendisk *sgp;
-	char buf[BDEVNAME_SIZE];
-	int n;
-
-	if (dev->type != &disk_type)
-		goto exit;
+	struct hd_struct *part;
+	struct block_device *bdev = NULL;
 
-	sgp = dev_to_disk(dev);
-	/*
-	 * Don't show empty devices or things that have been surpressed
-	 */
-	if (get_capacity(sgp) == 0 ||
-	    (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
-		goto exit;
+	part = disk_get_part(disk, partno);
+	if (part)
+		bdev = bdget(part_devt(part));
+	disk_put_part(part);
 
-	/*
-	 * Note, unlike /proc/partitions, I am showing the numbers in
-	 * hex - the same format as the root= option takes.
-	 */
-	printk("%02x%02x %10llu %s",
-		sgp->major, sgp->first_minor,
-		(unsigned long long)get_capacity(sgp) >> 1,
-		disk_name(sgp, 0, buf));
-	if (sgp->driverfs_dev != NULL &&
-	    sgp->driverfs_dev->driver != NULL)
-		printk(" driver: %s\n",
-			sgp->driverfs_dev->driver->name);
-	else
-		printk(" (driver?)\n");
-
-	/* now show the partitions */
-	for (n = 0; n < sgp->minors - 1; ++n) {
-		if (sgp->part[n] == NULL)
-			goto exit;
-		if (sgp->part[n]->nr_sects == 0)
-			goto exit;
-		printk("  %02x%02x %10llu %s\n",
-			sgp->major, n + 1 + sgp->first_minor,
-			(unsigned long long)sgp->part[n]->nr_sects >> 1,
-			disk_name(sgp, n + 1, buf));
-	}
-exit:
-	return 0;
+	return bdev;
 }
+EXPORT_SYMBOL(bdget_disk);
 
 /*
  * print a full list of all partitions - intended for places where the root
@@ -282,120 +599,145 @@ exit:
  */
 void __init printk_all_partitions(void)
 {
-	mutex_lock(&block_class_lock);
-	class_for_each_device(&block_class, NULL, NULL, printk_partition);
-	mutex_unlock(&block_class_lock);
+	struct class_dev_iter iter;
+	struct device *dev;
+
+	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
+	while ((dev = class_dev_iter_next(&iter))) {
+		struct gendisk *disk = dev_to_disk(dev);
+		struct disk_part_iter piter;
+		struct hd_struct *part;
+		char name_buf[BDEVNAME_SIZE];
+		char devt_buf[BDEVT_SIZE];
+
+		/*
+		 * Don't show empty devices or things that have been
+		 * surpressed
+		 */
+		if (get_capacity(disk) == 0 ||
+		    (disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
+			continue;
+
+		/*
+		 * Note, unlike /proc/partitions, I am showing the
+		 * numbers in hex - the same format as the root=
+		 * option takes.
+		 */
+		disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
+		while ((part = disk_part_iter_next(&piter))) {
+			bool is_part0 = part == &disk->part0;
+
+			printk("%s%s %10llu %s", is_part0 ? "" : "  ",
+			       bdevt_str(part_devt(part), devt_buf),
+			       (unsigned long long)part->nr_sects >> 1,
+			       disk_name(disk, part->partno, name_buf));
+			if (is_part0) {
+				if (disk->driverfs_dev != NULL &&
+				    disk->driverfs_dev->driver != NULL)
+					printk(" driver: %s\n",
+					      disk->driverfs_dev->driver->name);
+				else
+					printk(" (driver?)\n");
+			} else
+				printk("\n");
+		}
+		disk_part_iter_exit(&piter);
+	}
+	class_dev_iter_exit(&iter);
 }
 
 #ifdef CONFIG_PROC_FS
 /* iterator */
-static int find_start(struct device *dev, void *data)
+static void *disk_seqf_start(struct seq_file *seqf, loff_t *pos)
 {
-	loff_t *k = data;
+	loff_t skip = *pos;
+	struct class_dev_iter *iter;
+	struct device *dev;
 
-	if (dev->type != &disk_type)
-		return 0;
-	if (!*k)
-		return 1;
-	(*k)--;
-	return 0;
+	iter = kmalloc(sizeof(*iter), GFP_KERNEL);
+	if (!iter)
+		return ERR_PTR(-ENOMEM);
+
+	seqf->private = iter;
+	class_dev_iter_init(iter, &block_class, NULL, &disk_type);
+	do {
+		dev = class_dev_iter_next(iter);
+		if (!dev)
+			return NULL;
+	} while (skip--);
+
+	return dev_to_disk(dev);
 }
 
-static void *part_start(struct seq_file *part, loff_t *pos)
+static void *disk_seqf_next(struct seq_file *seqf, void *v, loff_t *pos)
 {
 	struct device *dev;
-	loff_t k = *pos;
-
-	if (!k)
-		part->private = (void *)1LU;	/* tell show to print header */
 
-	mutex_lock(&block_class_lock);
-	dev = class_find_device(&block_class, NULL, &k, find_start);
-	if (dev) {
-		put_device(dev);
+	(*pos)++;
+	dev = class_dev_iter_next(seqf->private);
+	if (dev)
 		return dev_to_disk(dev);
-	}
+
 	return NULL;
 }
 
-static int find_next(struct device *dev, void *data)
+static void disk_seqf_stop(struct seq_file *seqf, void *v)
 {
-	if (dev->type == &disk_type)
-		return 1;
-	return 0;
-}
+	struct class_dev_iter *iter = seqf->private;
 
-static void *part_next(struct seq_file *part, void *v, loff_t *pos)
-{
-	struct gendisk *gp = v;
-	struct device *dev;
-	++*pos;
-	dev = class_find_device(&block_class, &gp->dev, NULL, find_next);
-	if (dev) {
-		put_device(dev);
-		return dev_to_disk(dev);
+	/* stop is called even after start failed :-( */
+	if (iter) {
+		class_dev_iter_exit(iter);
+		kfree(iter);
 	}
-	return NULL;
 }
 
-static void part_stop(struct seq_file *part, void *v)
+static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
 {
-	mutex_unlock(&block_class_lock);
+	static void *p;
+
+	p = disk_seqf_start(seqf, pos);
+	if (!IS_ERR(p) && p && !*pos)
+		seq_puts(seqf, "major minor  #blocks  name\n\n");
+	return p;
 }
 
-static int show_partition(struct seq_file *part, void *v)
+static int show_partition(struct seq_file *seqf, void *v)
 {
 	struct gendisk *sgp = v;
-	int n;
+	struct disk_part_iter piter;
+	struct hd_struct *part;
 	char buf[BDEVNAME_SIZE];
 
-	/*
-	 * Print header if start told us to do.  This is to preserve
-	 * the original behavior of not printing header if no
-	 * partition exists.  This hackery will be removed later with
-	 * class iteration clean up.
-	 */
-	if (part->private) {
-		seq_puts(part, "major minor  #blocks  name\n\n");
-		part->private = NULL;
-	}
-
 	/* Don't show non-partitionable removeable devices or empty devices */
-	if (!get_capacity(sgp) ||
-			(sgp->minors == 1 && (sgp->flags & GENHD_FL_REMOVABLE)))
+	if (!get_capacity(sgp) || (!disk_partitionable(sgp) &&
+				   (sgp->flags & GENHD_FL_REMOVABLE)))
 		return 0;
 	if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
 		return 0;
 
 	/* show the full disk and all non-0 size partitions of it */
-	seq_printf(part, "%4d  %4d %10llu %s\n",
-		sgp->major, sgp->first_minor,
-		(unsigned long long)get_capacity(sgp) >> 1,
-		disk_name(sgp, 0, buf));
-	for (n = 0; n < sgp->minors - 1; n++) {
-		if (!sgp->part[n])
-			continue;
-		if (sgp->part[n]->nr_sects == 0)
-			continue;
-		seq_printf(part, "%4d  %4d %10llu %s\n",
-			sgp->major, n + 1 + sgp->first_minor,
-			(unsigned long long)sgp->part[n]->nr_sects >> 1 ,
-			disk_name(sgp, n + 1, buf));
-	}
+	disk_part_iter_init(&piter, sgp, DISK_PITER_INCL_PART0);
+	while ((part = disk_part_iter_next(&piter)))
+		seq_printf(seqf, "%4d  %7d %10llu %s\n",
+			   MAJOR(part_devt(part)), MINOR(part_devt(part)),
+			   (unsigned long long)part->nr_sects >> 1,
+			   disk_name(sgp, part->partno, buf));
+	disk_part_iter_exit(&piter);
 
 	return 0;
 }
 
 const struct seq_operations partitions_op = {
-	.start	= part_start,
-	.next	= part_next,
-	.stop	= part_stop,
+	.start	= show_partition_start,
+	.next	= disk_seqf_next,
+	.stop	= disk_seqf_stop,
 	.show	= show_partition
 };
 #endif
 
 
-static struct kobject *base_probe(dev_t devt, int *part, void *data)
+static struct kobject *base_probe(dev_t devt, int *partno, void *data)
 {
 	if (request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt)) > 0)
 		/* Make old-style 2.4 aliases work */
@@ -431,29 +773,29 @@ static ssize_t disk_range_show(struct device *dev,
 	return sprintf(buf, "%d\n", disk->minors);
 }
 
-static ssize_t disk_removable_show(struct device *dev,
+static ssize_t disk_ext_range_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
 	struct gendisk *disk = dev_to_disk(dev);
 
-	return sprintf(buf, "%d\n",
-		       (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
+	return sprintf(buf, "%d\n", disk_max_parts(disk));
 }
 
-static ssize_t disk_ro_show(struct device *dev,
+static ssize_t disk_removable_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
 	struct gendisk *disk = dev_to_disk(dev);
 
-	return sprintf(buf, "%d\n", disk->policy ? 1 : 0);
+	return sprintf(buf, "%d\n",
+		       (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
 }
 
-static ssize_t disk_size_show(struct device *dev,
-			      struct device_attribute *attr, char *buf)
+static ssize_t disk_ro_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
 {
 	struct gendisk *disk = dev_to_disk(dev);
 
-	return sprintf(buf, "%llu\n", (unsigned long long)get_capacity(disk));
+	return sprintf(buf, "%d\n", get_disk_ro(disk) ? 1 : 0);
 }
 
 static ssize_t disk_capability_show(struct device *dev,
@@ -464,73 +806,26 @@ static ssize_t disk_capability_show(struct device *dev,
 	return sprintf(buf, "%x\n", disk->flags);
 }
 
-static ssize_t disk_stat_show(struct device *dev,
-			      struct device_attribute *attr, char *buf)
-{
-	struct gendisk *disk = dev_to_disk(dev);
-
-	preempt_disable();
-	disk_round_stats(disk);
-	preempt_enable();
-	return sprintf(buf,
-		"%8lu %8lu %8llu %8u "
-		"%8lu %8lu %8llu %8u "
-		"%8u %8u %8u"
-		"\n",
-		disk_stat_read(disk, ios[READ]),
-		disk_stat_read(disk, merges[READ]),
-		(unsigned long long)disk_stat_read(disk, sectors[READ]),
-		jiffies_to_msecs(disk_stat_read(disk, ticks[READ])),
-		disk_stat_read(disk, ios[WRITE]),
-		disk_stat_read(disk, merges[WRITE]),
-		(unsigned long long)disk_stat_read(disk, sectors[WRITE]),
-		jiffies_to_msecs(disk_stat_read(disk, ticks[WRITE])),
-		disk->in_flight,
-		jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
-		jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
-}
-
-#ifdef CONFIG_FAIL_MAKE_REQUEST
-static ssize_t disk_fail_show(struct device *dev,
-			      struct device_attribute *attr, char *buf)
-{
-	struct gendisk *disk = dev_to_disk(dev);
-
-	return sprintf(buf, "%d\n", disk->flags & GENHD_FL_FAIL ? 1 : 0);
-}
-
-static ssize_t disk_fail_store(struct device *dev,
-			       struct device_attribute *attr,
-			       const char *buf, size_t count)
-{
-	struct gendisk *disk = dev_to_disk(dev);
-	int i;
-
-	if (count > 0 && sscanf(buf, "%d", &i) > 0) {
-		if (i == 0)
-			disk->flags &= ~GENHD_FL_FAIL;
-		else
-			disk->flags |= GENHD_FL_FAIL;
-	}
-
-	return count;
-}
-
-#endif
-
 static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
+static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
 static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
 static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL);
-static DEVICE_ATTR(size, S_IRUGO, disk_size_show, NULL);
+static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
 static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);
-static DEVICE_ATTR(stat, S_IRUGO, disk_stat_show, NULL);
+static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
 #ifdef CONFIG_FAIL_MAKE_REQUEST
 static struct device_attribute dev_attr_fail =
-	__ATTR(make-it-fail, S_IRUGO|S_IWUSR, disk_fail_show, disk_fail_store);
+	__ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
+#endif
+#ifdef CONFIG_FAIL_IO_TIMEOUT
+static struct device_attribute dev_attr_fail_timeout =
+	__ATTR(io-timeout-fail,  S_IRUGO|S_IWUSR, part_timeout_show,
+		part_timeout_store);
 #endif
 
 static struct attribute *disk_attrs[] = {
 	&dev_attr_range.attr,
+	&dev_attr_ext_range.attr,
 	&dev_attr_removable.attr,
 	&dev_attr_ro.attr,
 	&dev_attr_size.attr,
@@ -539,6 +834,9 @@ static struct attribute *disk_attrs[] = {
 #ifdef CONFIG_FAIL_MAKE_REQUEST
 	&dev_attr_fail.attr,
 #endif
+#ifdef CONFIG_FAIL_IO_TIMEOUT
+	&dev_attr_fail_timeout.attr,
+#endif
 	NULL
 };
 
@@ -551,13 +849,87 @@ static struct attribute_group *disk_attr_groups[] = {
 	NULL
 };
 
+static void disk_free_ptbl_rcu_cb(struct rcu_head *head)
+{
+	struct disk_part_tbl *ptbl =
+		container_of(head, struct disk_part_tbl, rcu_head);
+
+	kfree(ptbl);
+}
+
+/**
+ * disk_replace_part_tbl - replace disk->part_tbl in RCU-safe way
+ * @disk: disk to replace part_tbl for
+ * @new_ptbl: new part_tbl to install
+ *
+ * Replace disk->part_tbl with @new_ptbl in RCU-safe way.  The
+ * original ptbl is freed using RCU callback.
+ *
+ * LOCKING:
+ * Matching bd_mutx locked.
+ */
+static void disk_replace_part_tbl(struct gendisk *disk,
+				  struct disk_part_tbl *new_ptbl)
+{
+	struct disk_part_tbl *old_ptbl = disk->part_tbl;
+
+	rcu_assign_pointer(disk->part_tbl, new_ptbl);
+	if (old_ptbl)
+		call_rcu(&old_ptbl->rcu_head, disk_free_ptbl_rcu_cb);
+}
+
+/**
+ * disk_expand_part_tbl - expand disk->part_tbl
+ * @disk: disk to expand part_tbl for
+ * @partno: expand such that this partno can fit in
+ *
+ * Expand disk->part_tbl such that @partno can fit in.  disk->part_tbl
+ * uses RCU to allow unlocked dereferencing for stats and other stuff.
+ *
+ * LOCKING:
+ * Matching bd_mutex locked, might sleep.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int disk_expand_part_tbl(struct gendisk *disk, int partno)
+{
+	struct disk_part_tbl *old_ptbl = disk->part_tbl;
+	struct disk_part_tbl *new_ptbl;
+	int len = old_ptbl ? old_ptbl->len : 0;
+	int target = partno + 1;
+	size_t size;
+	int i;
+
+	/* disk_max_parts() is zero during initialization, ignore if so */
+	if (disk_max_parts(disk) && target > disk_max_parts(disk))
+		return -EINVAL;
+
+	if (target <= len)
+		return 0;
+
+	size = sizeof(*new_ptbl) + target * sizeof(new_ptbl->part[0]);
+	new_ptbl = kzalloc_node(size, GFP_KERNEL, disk->node_id);
+	if (!new_ptbl)
+		return -ENOMEM;
+
+	INIT_RCU_HEAD(&new_ptbl->rcu_head);
+	new_ptbl->len = target;
+
+	for (i = 0; i < len; i++)
+		rcu_assign_pointer(new_ptbl->part[i], old_ptbl->part[i]);
+
+	disk_replace_part_tbl(disk, new_ptbl);
+	return 0;
+}
+
 static void disk_release(struct device *dev)
 {
 	struct gendisk *disk = dev_to_disk(dev);
 
 	kfree(disk->random);
-	kfree(disk->part);
-	free_disk_stats(disk);
+	disk_replace_part_tbl(disk, NULL);
+	free_part_stats(&disk->part0);
 	kfree(disk);
 }
 struct class block_class = {
@@ -578,83 +950,31 @@ static struct device_type disk_type = {
  * The output looks suspiciously like /proc/partitions with a bunch of
  * extra fields.
  */
-
-static void *diskstats_start(struct seq_file *part, loff_t *pos)
-{
-	struct device *dev;
-	loff_t k = *pos;
-
-	mutex_lock(&block_class_lock);
-	dev = class_find_device(&block_class, NULL, &k, find_start);
-	if (dev) {
-		put_device(dev);
-		return dev_to_disk(dev);
-	}
-	return NULL;
-}
-
-static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
-{
-	struct gendisk *gp = v;
-	struct device *dev;
-
-	++*pos;
-	dev = class_find_device(&block_class, &gp->dev, NULL, find_next);
-	if (dev) {
-		put_device(dev);
-		return dev_to_disk(dev);
-	}
-	return NULL;
-}
-
-static void diskstats_stop(struct seq_file *part, void *v)
-{
-	mutex_unlock(&block_class_lock);
-}
-
-static int diskstats_show(struct seq_file *s, void *v)
+static int diskstats_show(struct seq_file *seqf, void *v)
 {
 	struct gendisk *gp = v;
+	struct disk_part_iter piter;
+	struct hd_struct *hd;
 	char buf[BDEVNAME_SIZE];
-	int n = 0;
+	int cpu;
 
 	/*
-	if (&gp->dev.kobj.entry == block_class.devices.next)
-		seq_puts(s,	"major minor name"
+	if (&disk_to_dev(gp)->kobj.entry == block_class.devices.next)
+		seq_puts(seqf,	"major minor name"
 				"     rio rmerge rsect ruse wio wmerge "
 				"wsect wuse running use aveq"
 				"\n\n");
 	*/
  
-	preempt_disable();
-	disk_round_stats(gp);
-	preempt_enable();
-	seq_printf(s, "%4d %4d %s %lu %lu %llu %u %lu %lu %llu %u %u %u %u\n",
-		gp->major, n + gp->first_minor, disk_name(gp, n, buf),
-		disk_stat_read(gp, ios[0]), disk_stat_read(gp, merges[0]),
-		(unsigned long long)disk_stat_read(gp, sectors[0]),
-		jiffies_to_msecs(disk_stat_read(gp, ticks[0])),
-		disk_stat_read(gp, ios[1]), disk_stat_read(gp, merges[1]),
-		(unsigned long long)disk_stat_read(gp, sectors[1]),
-		jiffies_to_msecs(disk_stat_read(gp, ticks[1])),
-		gp->in_flight,
-		jiffies_to_msecs(disk_stat_read(gp, io_ticks)),
-		jiffies_to_msecs(disk_stat_read(gp, time_in_queue)));
-
-	/* now show all non-0 size partitions of it */
-	for (n = 0; n < gp->minors - 1; n++) {
-		struct hd_struct *hd = gp->part[n];
-
-		if (!hd || !hd->nr_sects)
-			continue;
-
-		preempt_disable();
-		part_round_stats(hd);
-		preempt_enable();
-		seq_printf(s, "%4d %4d %s %lu %lu %llu "
+	disk_part_iter_init(&piter, gp, DISK_PITER_INCL_PART0);
+	while ((hd = disk_part_iter_next(&piter))) {
+		cpu = part_stat_lock();
+		part_round_stats(cpu, hd);
+		part_stat_unlock();
+		seq_printf(seqf, "%4d %7d %s %lu %lu %llu "
 			   "%u %lu %lu %llu %u %u %u %u\n",
-			   gp->major, n + gp->first_minor + 1,
-			   disk_name(gp, n + 1, buf),
+			   MAJOR(part_devt(hd)), MINOR(part_devt(hd)),
+			   disk_name(gp, hd->partno, buf),
 			   part_stat_read(hd, ios[0]),
 			   part_stat_read(hd, merges[0]),
 			   (unsigned long long)part_stat_read(hd, sectors[0]),
@@ -668,14 +988,15 @@ static int diskstats_show(struct seq_file *s, void *v)
 			   jiffies_to_msecs(part_stat_read(hd, time_in_queue))
 			);
 	}
+	disk_part_iter_exit(&piter);
  
 	return 0;
 }
 
 const struct seq_operations diskstats_op = {
-	.start	= diskstats_start,
-	.next	= diskstats_next,
-	.stop	= diskstats_stop,
+	.start	= disk_seqf_start,
+	.next	= disk_seqf_next,
+	.stop	= disk_seqf_stop,
 	.show	= diskstats_show
 };
 #endif /* CONFIG_PROC_FS */
@@ -690,7 +1011,7 @@ static void media_change_notify_thread(struct work_struct *work)
 	 * set enviroment vars to indicate which event this is for
 	 * so that user space will know to go check the media status.
 	 */
-	kobject_uevent_env(&gd->dev.kobj, KOBJ_CHANGE, envp);
+	kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
 	put_device(gd->driverfs_dev);
 }
 
@@ -703,42 +1024,29 @@ void genhd_media_change_notify(struct gendisk *disk)
 EXPORT_SYMBOL_GPL(genhd_media_change_notify);
 #endif  /*  0  */
 
-struct find_block {
-	const char *name;
-	int part;
-};
-
-static int match_id(struct device *dev, void *data)
+dev_t blk_lookup_devt(const char *name, int partno)
 {
-	struct find_block *find = data;
+	dev_t devt = MKDEV(0, 0);
+	struct class_dev_iter iter;
+	struct device *dev;
 
-	if (dev->type != &disk_type)
-		return 0;
-	if (strcmp(dev->bus_id, find->name) == 0) {
+	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
+	while ((dev = class_dev_iter_next(&iter))) {
 		struct gendisk *disk = dev_to_disk(dev);
-		if (find->part < disk->minors)
-			return 1;
-	}
-	return 0;
-}
+		struct hd_struct *part;
 
-dev_t blk_lookup_devt(const char *name, int part)
-{
-	struct device *dev;
-	dev_t devt = MKDEV(0, 0);
-	struct find_block find;
+		if (strcmp(dev->bus_id, name))
+			continue;
 
-	mutex_lock(&block_class_lock);
-	find.name = name;
-	find.part = part;
-	dev = class_find_device(&block_class, NULL, &find, match_id);
-	if (dev) {
-		put_device(dev);
-		devt = MKDEV(MAJOR(dev->devt),
-			     MINOR(dev->devt) + part);
+		part = disk_get_part(disk, partno);
+		if (part) {
+			devt = part_devt(part);
+			disk_put_part(part);
+			break;
+		}
+		disk_put_part(part);
 	}
-	mutex_unlock(&block_class_lock);
-
+	class_dev_iter_exit(&iter);
 	return devt;
 }
 EXPORT_SYMBOL(blk_lookup_devt);
@@ -747,6 +1055,7 @@ struct gendisk *alloc_disk(int minors)
 {
 	return alloc_disk_node(minors, -1);
 }
+EXPORT_SYMBOL(alloc_disk);
 
 struct gendisk *alloc_disk_node(int minors, int node_id)
 {
@@ -755,32 +1064,28 @@ struct gendisk *alloc_disk_node(int minors, int node_id)
 	disk = kmalloc_node(sizeof(struct gendisk),
 				GFP_KERNEL | __GFP_ZERO, node_id);
 	if (disk) {
-		if (!init_disk_stats(disk)) {
+		if (!init_part_stats(&disk->part0)) {
 			kfree(disk);
 			return NULL;
 		}
-		if (minors > 1) {
-			int size = (minors - 1) * sizeof(struct hd_struct *);
-			disk->part = kmalloc_node(size,
-				GFP_KERNEL | __GFP_ZERO, node_id);
-			if (!disk->part) {
-				free_disk_stats(disk);
-				kfree(disk);
-				return NULL;
-			}
+		if (disk_expand_part_tbl(disk, 0)) {
+			free_part_stats(&disk->part0);
+			kfree(disk);
+			return NULL;
 		}
+		disk->part_tbl->part[0] = &disk->part0;
+
 		disk->minors = minors;
 		rand_initialize_disk(disk);
-		disk->dev.class = &block_class;
-		disk->dev.type = &disk_type;
-		device_initialize(&disk->dev);
+		disk_to_dev(disk)->class = &block_class;
+		disk_to_dev(disk)->type = &disk_type;
+		device_initialize(disk_to_dev(disk));
 		INIT_WORK(&disk->async_notify,
 			media_change_notify_thread);
+		disk->node_id = node_id;
 	}
 	return disk;
 }
-
-EXPORT_SYMBOL(alloc_disk);
 EXPORT_SYMBOL(alloc_disk_node);
 
 struct kobject *get_disk(struct gendisk *disk)
@@ -793,7 +1098,7 @@ struct kobject *get_disk(struct gendisk *disk)
 	owner = disk->fops->owner;
 	if (owner && !try_module_get(owner))
 		return NULL;
-	kobj = kobject_get(&disk->dev.kobj);
+	kobj = kobject_get(&disk_to_dev(disk)->kobj);
 	if (kobj == NULL) {
 		module_put(owner);
 		return NULL;
@@ -807,27 +1112,28 @@ EXPORT_SYMBOL(get_disk);
 void put_disk(struct gendisk *disk)
 {
 	if (disk)
-		kobject_put(&disk->dev.kobj);
+		kobject_put(&disk_to_dev(disk)->kobj);
 }
 
 EXPORT_SYMBOL(put_disk);
 
 void set_device_ro(struct block_device *bdev, int flag)
 {
-	if (bdev->bd_contains != bdev)
-		bdev->bd_part->policy = flag;
-	else
-		bdev->bd_disk->policy = flag;
+	bdev->bd_part->policy = flag;
 }
 
 EXPORT_SYMBOL(set_device_ro);
 
 void set_disk_ro(struct gendisk *disk, int flag)
 {
-	int i;
-	disk->policy = flag;
-	for (i = 0; i < disk->minors - 1; i++)
-		if (disk->part[i]) disk->part[i]->policy = flag;
+	struct disk_part_iter piter;
+	struct hd_struct *part;
+
+	disk_part_iter_init(&piter, disk,
+			    DISK_PITER_INCL_EMPTY | DISK_PITER_INCL_PART0);
+	while ((part = disk_part_iter_next(&piter)))
+		part->policy = flag;
+	disk_part_iter_exit(&piter);
 }
 
 EXPORT_SYMBOL(set_disk_ro);
@@ -836,18 +1142,15 @@ int bdev_read_only(struct block_device *bdev)
 {
 	if (!bdev)
 		return 0;
-	else if (bdev->bd_contains != bdev)
-		return bdev->bd_part->policy;
-	else
-		return bdev->bd_disk->policy;
+	return bdev->bd_part->policy;
 }
 
 EXPORT_SYMBOL(bdev_read_only);
 
-int invalidate_partition(struct gendisk *disk, int index)
+int invalidate_partition(struct gendisk *disk, int partno)
 {
 	int res = 0;
-	struct block_device *bdev = bdget_disk(disk, index);
+	struct block_device *bdev = bdget_disk(disk, partno);
 	if (bdev) {
 		fsync_bdev(bdev);
 		res = __invalidate_device(bdev);