block: open code kobj_map into in block/genhd.c

Copy and paste the kobj_map functionality in the block code in preparation
for completely rewriting it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/genhd.c b/block/genhd.c
index d41176e..667d1d6 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -17,7 +17,6 @@
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/kmod.h>
-#include <linux/kobj_map.h>
 #include <linux/mutex.h>
 #include <linux/idr.h>
 #include <linux/log2.h>
@@ -29,6 +28,16 @@
 static DEFINE_MUTEX(block_class_lock);
 static struct kobject *block_depr;
 
+struct bdev_map {
+       struct bdev_map *next;
+       dev_t dev;
+       unsigned long range;
+       struct module *owner;
+       struct kobject *(*probe)(dev_t, int *, void *);
+       int (*lock)(dev_t, void *);
+       void *data;
+} *bdev_map[255];
+
 /* for extended dynamic devt allocation, currently only one major is used */
 #define NR_EXT_DEVT            (1 << MINORBITS)
 
@@ -520,8 +529,6 @@ void unregister_blkdev(unsigned int major, const char *name)
 
 EXPORT_SYMBOL(unregister_blkdev);
 
-static struct kobj_map *bdev_map;
-
 /**
  * blk_mangle_minor - scatter minor numbers apart
  * @minor: minor number to mangle
@@ -648,16 +655,60 @@ void blk_register_region(dev_t devt, unsigned long range, struct module *module,
                         struct kobject *(*probe)(dev_t, int *, void *),
                         int (*lock)(dev_t, void *), void *data)
 {
-       kobj_map(bdev_map, devt, range, module, probe, lock, data);
-}
+       unsigned n = MAJOR(devt + range - 1) - MAJOR(devt) + 1;
+       unsigned index = MAJOR(devt);
+       unsigned i;
+       struct bdev_map *p;
+
+       n = min(n, 255u);
+       p = kmalloc_array(n, sizeof(struct bdev_map), GFP_KERNEL);
+       if (p == NULL)
+               return;
 
+       for (i = 0; i < n; i++, p++) {
+               p->owner = module;
+               p->probe = probe;
+               p->lock = lock;
+               p->dev = devt;
+               p->range = range;
+               p->data = data;
+       }
+
+       mutex_lock(&block_class_lock);
+       for (i = 0, p -= n; i < n; i++, p++, index++) {
+               struct bdev_map **s = &bdev_map[index % 255];
+               while (*s && (*s)->range < range)
+                       s = &(*s)->next;
+               p->next = *s;
+               *s = p;
+       }
+       mutex_unlock(&block_class_lock);
+}
 EXPORT_SYMBOL(blk_register_region);
 
 void blk_unregister_region(dev_t devt, unsigned long range)
 {
-       kobj_unmap(bdev_map, devt, range);
-}
+       unsigned n = MAJOR(devt + range - 1) - MAJOR(devt) + 1;
+       unsigned index = MAJOR(devt);
+       unsigned i;
+       struct bdev_map *found = NULL;
 
+       mutex_lock(&block_class_lock);
+       for (i = 0; i < min(n, 255u); i++, index++) {
+               struct bdev_map **s;
+               for (s = &bdev_map[index % 255]; *s; s = &(*s)->next) {
+                       struct bdev_map *p = *s;
+                       if (p->dev == devt && p->range == range) {
+                               *s = p->next;
+                               if (!found)
+                                       found = p;
+                               break;
+                       }
+               }
+       }
+       mutex_unlock(&block_class_lock);
+       kfree(found);
+}
 EXPORT_SYMBOL(blk_unregister_region);
 
 static struct kobject *exact_match(dev_t devt, int *partno, void *data)
@@ -979,6 +1030,47 @@ static ssize_t disk_badblocks_store(struct device *dev,
        return badblocks_store(disk->bb, page, len, 0);
 }
 
+static struct gendisk *lookup_gendisk(dev_t dev, int *partno)
+{
+       struct kobject *kobj;
+       struct bdev_map *p;
+       unsigned long best = ~0UL;
+
+retry:
+       mutex_lock(&block_class_lock);
+       for (p = bdev_map[MAJOR(dev) % 255]; p; p = p->next) {
+               struct kobject *(*probe)(dev_t, int *, void *);
+               struct module *owner;
+               void *data;
+
+               if (p->dev > dev || p->dev + p->range - 1 < dev)
+                       continue;
+               if (p->range - 1 >= best)
+                       break;
+               if (!try_module_get(p->owner))
+                       continue;
+               owner = p->owner;
+               data = p->data;
+               probe = p->probe;
+               best = p->range - 1;
+               *partno = dev - p->dev;
+               if (p->lock && p->lock(dev, data) < 0) {
+                       module_put(owner);
+                       continue;
+               }
+               mutex_unlock(&block_class_lock);
+               kobj = probe(dev, partno, data);
+               /* Currently ->owner protects _only_ ->probe() itself. */
+               module_put(owner);
+               if (kobj)
+                       return dev_to_disk(kobj_to_dev(kobj));
+               goto retry;
+       }
+       mutex_unlock(&block_class_lock);
+       return NULL;
+}
+
+
 /**
  * get_gendisk - get partitioning information for a given device
  * @devt: device to get partitioning information for
@@ -996,11 +1088,7 @@ struct gendisk *get_gendisk(dev_t devt, int *partno)
        might_sleep();
 
        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));
+               disk = lookup_gendisk(devt, partno);
        } else {
                struct hd_struct *part;
 
@@ -1213,6 +1301,22 @@ static struct kobject *base_probe(dev_t devt, int *partno, void *data)
        return NULL;
 }
 
+static void bdev_map_init(void)
+{
+       struct bdev_map *base;
+       int i;
+
+       base = kzalloc(sizeof(*base), GFP_KERNEL);
+       if (!base)
+               panic("cannot allocate bdev_map");
+
+       base->dev = 1;
+       base->range = ~0 ;
+       base->probe = base_probe;
+       for (i = 0; i < 255; i++)
+               bdev_map[i] = base;
+}
+
 static int __init genhd_device_init(void)
 {
        int error;
@@ -1221,7 +1325,7 @@ static int __init genhd_device_init(void)
        error = class_register(&block_class);
        if (unlikely(error))
                return error;
-       bdev_map = kobj_map_init(base_probe, &block_class_lock);
+       bdev_map_init();
        blk_dev_init();
 
        register_blkdev(BLOCK_EXT_MAJOR, "blkext");