From: Kevin Corry <kevcorry@us.ibm.com>
Keep track of allocated minor numbers with an IDR instead of a bit-set.
Signed-off-by: Kevin Corry <kevcorry@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/drivers/md/dm.c | 124 +++++++++++++++++-------------------------------
1 files changed, 45 insertions(+), 79 deletions(-)
diff -puN drivers/md/dm.c~dm-use-idr drivers/md/dm.c
--- 25/drivers/md/dm.c~dm-use-idr Fri Jul 2 16:10:54 2004
+++ 25-akpm/drivers/md/dm.c Fri Jul 2 16:10:54 2004
@@ -15,15 +15,13 @@
#include <linux/buffer_head.h>
#include <linux/mempool.h>
#include <linux/slab.h>
+#include <linux/idr.h>
static const char *_name = DM_NAME;
static unsigned int major = 0;
static unsigned int _major = 0;
-static int realloc_minor_bits(unsigned long requested_minor);
-static void free_minor_bits(void);
-
/*
* One of these is allocated per bio.
*/
@@ -113,19 +111,11 @@ static int __init local_init(void)
return -ENOMEM;
}
- r = realloc_minor_bits(1024);
- if (r < 0) {
- kmem_cache_destroy(_tio_cache);
- kmem_cache_destroy(_io_cache);
- return r;
- }
-
_major = major;
r = register_blkdev(_major, _name);
if (r < 0) {
kmem_cache_destroy(_tio_cache);
kmem_cache_destroy(_io_cache);
- free_minor_bits();
return r;
}
@@ -139,7 +129,6 @@ static void local_exit(void)
{
kmem_cache_destroy(_tio_cache);
kmem_cache_destroy(_io_cache);
- free_minor_bits();
if (unregister_blkdev(_major, _name) < 0)
DMERR("devfs_unregister_blkdev failed");
@@ -639,59 +628,15 @@ static int dm_any_congested(void *conges
}
/*-----------------------------------------------------------------
- * A bitset is used to keep track of allocated minor numbers.
+ * An IDR is used to keep track of allocated minor numbers.
*---------------------------------------------------------------*/
static DECLARE_MUTEX(_minor_lock);
-static unsigned long *_minor_bits = NULL;
-static unsigned long _max_minors = 0;
-
-#define MINORS_SIZE(minors) ((minors / BITS_PER_LONG) * sizeof(unsigned long))
-
-static int realloc_minor_bits(unsigned long requested_minor)
-{
- unsigned long max_minors;
- unsigned long *minor_bits, *tmp;
-
- if (requested_minor < _max_minors)
- return -EINVAL;
-
- /* Round up the requested minor to the next power-of-2. */
- max_minors = 1 << fls(requested_minor - 1);
- if (max_minors > (1 << MINORBITS))
- return -EINVAL;
-
- minor_bits = kmalloc(MINORS_SIZE(max_minors), GFP_KERNEL);
- if (!minor_bits)
- return -ENOMEM;
- memset(minor_bits, 0, MINORS_SIZE(max_minors));
-
- /* Copy the existing bit-set to the new one. */
- if (_minor_bits)
- memcpy(minor_bits, _minor_bits, MINORS_SIZE(_max_minors));
-
- tmp = _minor_bits;
- _minor_bits = minor_bits;
- _max_minors = max_minors;
- if (tmp)
- kfree(tmp);
-
- return 0;
-}
-
-static void free_minor_bits(void)
-{
- down(&_minor_lock);
- kfree(_minor_bits);
- _minor_bits = NULL;
- _max_minors = 0;
- up(&_minor_lock);
-}
+static DEFINE_IDR(_minor_idr);
static void free_minor(unsigned int minor)
{
down(&_minor_lock);
- if (minor < _max_minors)
- clear_bit(minor, _minor_bits);
+ idr_remove(&_minor_idr, minor);
up(&_minor_lock);
}
@@ -700,24 +645,37 @@ static void free_minor(unsigned int mino
*/
static int specific_minor(unsigned int minor)
{
- int r = 0;
+ int r, m;
if (minor > (1 << MINORBITS))
return -EINVAL;
down(&_minor_lock);
- if (minor >= _max_minors) {
- r = realloc_minor_bits(minor);
- if (r) {
- up(&_minor_lock);
- return r;
- }
+
+ if (idr_find(&_minor_idr, minor)) {
+ r = -EBUSY;
+ goto out;
}
- if (test_and_set_bit(minor, _minor_bits))
+ r = idr_pre_get(&_minor_idr, GFP_KERNEL);
+ if (!r) {
+ r = -ENOMEM;
+ goto out;
+ }
+
+ r = idr_get_new_above(&_minor_idr, specific_minor, minor, &m);
+ if (r) {
+ goto out;
+ }
+
+ if (m != minor) {
+ idr_remove(&_minor_idr, m);
r = -EBUSY;
- up(&_minor_lock);
+ goto out;
+ }
+out:
+ up(&_minor_lock);
return r;
}
@@ -727,21 +685,29 @@ static int next_free_minor(unsigned int
unsigned int m;
down(&_minor_lock);
- m = find_first_zero_bit(_minor_bits, _max_minors);
- if (m >= _max_minors) {
- r = realloc_minor_bits(_max_minors * 2);
- if (r) {
- up(&_minor_lock);
- return r;
- }
- m = find_first_zero_bit(_minor_bits, _max_minors);
+
+ r = idr_pre_get(&_minor_idr, GFP_KERNEL);
+ if (!r) {
+ r = -ENOMEM;
+ goto out;
+ }
+
+ r = idr_get_new(&_minor_idr, next_free_minor, &m);
+ if (r) {
+ goto out;
+ }
+
+ if (m > (1 << MINORBITS)) {
+ idr_remove(&_minor_idr, m);
+ r = -ENOSPC;
+ goto out;
}
- set_bit(m, _minor_bits);
*minor = m;
- up(&_minor_lock);
- return 0;
+out:
+ up(&_minor_lock);
+ return r;
}
static struct block_device_operations dm_blk_dops;
_